CA2185729A1 - Color sequential display panels - Google Patents

Abstract

A color active matrix display system allows random access of pixel electrodes. The control electronics is fabricated with the active matrix circuitry using single crystal silicon technology. The control electronics includes a random access data scanner and random access spec scanners. By selectively actuating pixel electrodes in the active matrix display region, compressed video information can be directly displayed on the active matrix display panel. Color stripes are used to generate sequential color systems to produce a color image from the active matrix display panel.

Description

~o ~sl2 61 l 0 2 1 8 5 7 2 ~ PCT~Ss~sJo36 70 .

COLOR ~ Ju~;Nl I AT DISP~-AY pAN~T,q Back~rollnfl of=the Tnven~ion Flat-panel displays are being developed which utilize liquid crystals or electr~l n~o~cent materials to produce 5 high quality images. These displays are expected to supplant cathode ray tube (CRT) te~hn~ y and provide a more highly defined television picture or computer monitor image . The most ~,, 1 Fl j n~ route to large scale high quality liquid cry6tal displays (LCDs), for example, i9 10 the active-matrix approach in which thin-film transistors (TFTs) are co-located with LCD pixels. The primary advantage of t~e active matrix approach using TFTs is the elimination of cross-talk between pixels, and the ~rr~ nt grey 8cale that can be ~ttqln~d with 15 TFT- s ~ t;hle ~CDs.
Flat panel displays employing LCDs ~on~orql 1 y include five different layers: a white light source, a first polarizing filter that is mounted on one side of a circuit panel on which the TFTs are arrayed to form pixels, a 20 filter plate ~ntq;n;n~ at least three primary colors arranged into pixels, and f inally a second polarizing filter. h volume between the circuit panel and the filter plate is filled with a liquid crystal material. This material will alter the polarization of light in the 25 ~qt~o~; ql when an electric ~ield is applied across the TY=t~;ql between the circuit panel and a ground affixed to WO9~/26110 PCTNS95103670 the filter plate. Thus, when a particular pixel of the display is turned on, the liquid crystal material rotates polarized light being transmitted through the material so that the light will pa6s through the second polarizing 5 filter.
The primary approach to TFT formation over the large areas required for flat panel displays has involved the use of amorphous silicon, which has previously been developed for large-area photovoltaic devices. Although l0 the TFT approach has proven to be feasible, the use of amorphous silicon ~1 _, ' qes certain aspects of the panel performance. For example, amorphous silicon TFTs lack the frequency response needed for large area displays due to the low electron mobility inherent in amorphous material.
15 Thus the use of amorphous silicon limits display speed, and is also unsuitable for the fast logic needed to drlve the display.
As the display resolution increases, the required clock rate to drive the pixels also increases. In 20 addition, the advent of colored displays places additional speed requirements on the display panel. To produce a se~auential color display, the display panel is triple scanned, once for each primary color. For example, to produce color frames at 20 Hz, the active matrix must be 25 driven at a frequency of 60 ~Iz. In brighter ambient light conditions, the active matrix may need to be driven at 180 Hz to produce a 60 Hz color image. At over 60 Hz, visible flicker is reduced.
One such color sequential system has been described 30 by Peter Jansen in ~A Novel Single ~ight Valve High Bri~htn~fls HD Color Projector, " Society For Information Display (SID), Technical Paper, France 1993. In this system, dichroic filters are used to separate light from an arc lamp into three primary colors that are shaped into 35 rectangular stripes which are sequentially scanned across ~0 g~l2611~ 7zg PC~lUSg~Jo3G70 a single light valve using a rotating prism. The control circuitry for this system was fabricated using discrete t~ for the active matrix, the column drivers and three commercially available random access row drivers mounted separately onto a glass panel with the column drivers and the active matrix. The active matrix was fabricated in poly-silicon and connected to the drivers using pin connections.
Owing to the limitations of amorphous silicon, other alternative materials include polycrystalline silicon, or laser recryst;~l l; 7ed silicon. These materials are limited as they use silicon that is already on glass, which generally restricts further circuit pr~ q;n~ to low temperatures .
A cnnt;nllln~ need exists for systems and methods of controlling pixels and drive circuits of panel displays having the desired speed, r~oAn1l~t;nn and size and providing f or ~ease, and reduced cost of f abrication .
Summarv of the Invention A preferred: ' -';- of the invention is an integrated circuit random access video display for displaying an image from a video source. An active matrix drive circuit and an active matrix display region are fabricated in a common integrated circuit module. The integrated circuit module can be formed in a silicon-on-insulator (SOI) structure that is transferred onto an optically tr~nrm; ~;ve substrate such as glass. A light box module translates a digital video signal into an active matrix drive signal. The active matrix display region has an array of pixel electrodes and an array of pixel transistors registered to the array of pixel electrodes. The pixel transistors actuate the pixel electrodes in response to the active matrix drive signal from the control circuit. The integrated circuit module WO 9512611n ~ PCr/Ussslo3670 can then be used to fabricate a liquid crystal display device for use in a projection display system or a head-mounted display system.
In particular, the control circuit includes one (or 5 more) random access select scanner and a column driver.
The select scanner can enable a row of pixel transistors at random. The column driver can provide actuation signals to the tr~nP-; Psion gates that allow video data to f low into the enabled pixel transistors . Timing 10 infnrr-t;n~ for the select scanner and the column driver is provided by a control signal generator, which is also fabricated in the integrated circuit module. The circuit module can also include a video memory, D/A converters, and at least one frame buffer for storing at least one 15 video signal from algital data le~ st~ ing the video image. In a particular preferred: ' ~ '; , the display generates color images and there is a frame buffer for the digital data, ;:~PAor~;;ltP~ with each primary color (e.g., red, green, blue) . In another preferred: ' ~ ~; ', the 20 frame memory is partitioned into channels. The column driver preferably actuates individual pixel electrodes that can be randomly selected by the control circuit.
In a preferred embodiment of the invention, the video source is any analog or digital video source including a 25 computer, television receiver, high-definition television (HDTV) receiver or other similar sources. In particular, the active matrix display region is ~_ ~ t; hl e with HDTV
formats and is a 1280-by-1024 pixel array. The pixels have a pitch that is preferably in the range of 10-55 3 0 microns such that multiple integrated circuit modules can be fabricated on a single five inch wafer.
In a particular preferred ' ';I , the control circuit generates compressed video data to obtain further bandwidth r~ lrt; nn~ . A9 such, only pixel3 whose data 35 value has changed since the last video frame needs to be ~ ~18S~,i?g '.',J

- updated. Preferably, the control circuit is compatible with standard active matrix drive techniques.
AB referenced above, a preferred embodiment of the invention includes a proce~s of ~abricating an active 5 matrix display in which a circuit i8 fabricated with an SOI structure and then transferred onto an optically tr~n~; Rsive substrate. The pixel electrodes can be fabricated prior to transfer using processes described in U.S. Patent No. 5,206,749 entitled "Liquid Crystal Display 10 Having Essentially-Single Crystal Transistors Pixels and Driving Circuits, " the t~h;ngR of which are incorporated herein by reference. The pixel electrodes can be made of a transmissive silicon material or a conductive metal oxide such as indium tin oxide. The pixel electrodes can 15 also be formed after transfer of the circuit and connected through the insulator as described by Vu et al . in U. S .
Patent No. 5,256,562 entitled "Method For Manufacturing A
Semiconductor Device Using a Circuit Transfer Film, " the t~ h;n~ of which are incorporated herein by reference.
20 Other methods for fabricating pixel electrodes are described by Zavracky et al. U.S. Serial No. 08/215,555 filed on March 21, 1994 and entitled "Methods of Fabricating Active Matrix Pixel Electrodes, " the teachings of which are incorporated herein by reference.
25 Brie~ Descril~tion of the Drawinqs The above and other features of the invention, including various novel details of construction and ~ ~n;lt;~n of partg, will now be more particularly described with reference to the ao~ ying drawings and 30 pointed out in the claims. It will be understood that the particular color sequential display panels embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in varied and wo g~n6~ 9 PCT/US9~103670 ~ ' numerous embodiment~ without departing from the scope'of the invention.
FIG. 1 is a block diagram of a control system for a color active matrix display.
FIG. 2 is a block diagram of the light box circuitry 7 of FIG. 1.
FIG. 3 is a schematic block diagram of a display panel drive circuit.
FIG. 4 is a schematic diagram illustrating a preferred ~ of a color c.or~ nt;:~l display system using a scanning prism.
FIGs. 5A-5C are views of the sca~ning prism 120 of FIG. 3 illustrating color scannirlg.
FIGs. 6A-6C are views of the active matrix display go of FIG. 3 corrPcpr,n~i;nr~ to the color scanning of FIGs.
5A-5C.
FIG. 7 is a schematic diagram of a preferred ~ ' ~,flir- t of a color ger~ nt~l digplay system using a rotating cone.
FIG. 8 i9 a ~' tir block diagram of a color shutter display system.
FIG. 9 is a schematic diagram illustrating a preferred ~ ' ~ '; t of a ferroelectric li~auid crystal color generator as a color filter system.
FIG. 10 is a schematic block diagram of a digital falling raster system.
FIG. 11 is a 8~' tic diagram of an F~C color filter having an arbitrary number of electrodes.
FIGs. 12A-12B are schematic timiIlg diagrams for the color ~hutter systems of FIG. 8.
FIG. 13 is a schematic block diagram of a digital drive circuit having wide low-speed RAM.
FIG. 14 is a schematic block diagram of a digital drive circuit having narrow high-speed RAM.

~O '35126110 ~1~ j PCT~JS95103670 FIGs. 15A-15B are ~ ;c block diagrams o~ an analog drive circuit.
FIG. 16 is a timing diagram of the drive circuit of FIG. 15B.
FIG. 17 is a schematic diagram of a preferred color display system ll~;1;7;ng electronically-controlled color shutters .
FIGs. 18A-18B are schematic diagram illustrating another preferred Pmho~; of the invention employing a rotating prism.
FIG. 19 is a 3chematic illustration of a color sequential projection system llt;1;7;n3 a binary optic.
FIG. 20 is a schematic elevational view of pixel rows in a color sequential LCD display.
FIG. 21 is a 8-~ t; c diagram of a head mounted color sequential ~CD ~ play system.
FIG. 22 is a perspective view of an optics module and partial broken view of the housing for the module in a head-mounted display system.
FIG. 23 is a back view of two modules for a h;nnclll;~r head mounted display.
FIG. 24 is a cross-sectional view of an optics module housing for a head mounted display.
FIG. 25 is a perspective view of a sliding ramp system for the housing.
FIG. 26 is an alternative -'; t for the optical system of a color sequential head mounted display.
FIG. 27 is another preferred embodiment of a color sPquPnt; ~1 head mounted optical system.
FIG. 28 is a perspective view of a monocular head mounted color sequential LCD system.
FIGs. 29A-29D are perspective and side views of a head mounted computer system having a monocular color 8PqllPnt;~l display.

Wo !)5126110 PcTn~sss/o367o ?~9 FIG. 30 is a schematic communications network for a head mounted color sequential display system.
FIG. 31 i6 a perspective view of a head mounted color s~qU~nt;~l display 6ystem.
FIG. 32 is a schematic view of the eye-piece module for a color SPSr1,on~;~1 head mounted system.
FIG. 33 is a cross-sectional view of a transerred 6ilicon active matrix liquid crystal display.
FIG. 34 is a partial cross-s~ ~i on~l view of an active matrix display circuit with a preferred pixel structure for a color sequential sy6tem.
~et~;led De3cri~tion o~ Preferred r ~ of the Invention A preferred ' 'i-- ~ o a control system for a color active matrix display is shown in FIG. 1. A video signal adaptor 2 provide6 color video 6ignals to a light box module 7. The video signal adaptor 2 can include any analog or digital video signal squrce 1, 4 including a Video Graphics Array ~VGA) adaptor, the Apple'M M;-~;
family of computers, a National Tslevision Systems Committee (NTSC) composite video source, a High-Definition Television (HDTV) receiver, a high-resolution prof~ 3ion~1 display adapter, a Charge-Coupled-Device (CCD), a PA~
video source, a SECAM video 60urce, or other similar sources. A6 illustrated, the work 6tation or computer-generated video signal6 from a yraphics controller 1 are processed by a monitor electronic6 module 3 to provide the color video signal, typically a 24-bit RGB signal with Hsync and Vsync information, to the light box 7. Similarly, television broadcasts 4 are processed by a televi6ion electronics module 5 to provide the color video signal to the light box module 7. In a particular preferred e~nbodiment, an active matrix display panel g is adapted a6 a computer-controlled light valve that displays 09~/26110 PCTIUS95J0367~
218~72g _ g _ color images to a viewer. The images can be displayed directly to the viewer or by projection onto a viewing surface. In a particular preferred embodiment, the light valve is part of a head-mounted display (HMD) device.
Flat panel displays have pixels where the analog RGB
signal must contain information on screen position. For the position information to be accurate, each scan line of the analog RGB signal must be divided into discrete values. That task is performed by the video signal adaptor 2, which provides digital color data for each pixel .
The active matrix display panel 9 operates as a variable multi-frequency display device. Video signals from the video signal source may not be synchronized to a known fixed frequency. A change in the video mode can change the resolution of the data, measured in pixels.
For example, a VGA adaptor 1 generates synchronization signals that vary ~ rf~n~;n~ on the particular video mode in which the adaptor is operating. A standard VGA adaptor 1 can generate a vertical synchrnn;7~t;nn (Vsync) frequency between about 56 and 70 Xz and a horizontal synchronization (Hsync) frequency between about 15 and 35 Khz. For prof~RRinn~l display purposes (e.g., CAD/CAM) the Hsync and Vsync f requencies can be higher than described. To handle current high resolution diaplay ~rrl;c~t;nnR, the display device can preferably adapt to Vsync freque~cies up to about 100 Hz and horizontal synchrnn;7~t;on frequencies up to about 66 Khz. In addition, a change in the video mode can also invert the 3 0 polarities of the synchronization signals . Consequently, a preferred ~ ;r ' of the invention adapts to changes in the synchrnn;7~t;nn signals caused by changes in the video mode.
FIG. 2 is a block diagram of the light box module 7 35 of FIG. 1. The light box module 7 receives the Hsync signal ll, the Vsync aignal 13 and a color data signal 15, which is typically operating at 300 M~Iz from the video signal adaptor 2. In a preferred ~ ; ' of the invention, the color data signal 15 represents the color-5 of each pixel as a 24-bit digital value. The video signals 11,13 ,15 are received by a video receiver interface iO, which formats the color data signal 15 for storage in a video frame memory 25. In particular, the video receiver interface 10 converts the serial color data 10 input stream 15 into parallel data 22 for storage in th~
video frame memory 25. The ~sync signal 11 and the Vs~vnc signal 13 are also provided to a control signal generator 12 .
The control signal generator 12 generates control 15 signals for operating the active matrix display panel 9 in response to the ~sync 11 and Vsync 13 signals from the video signal source 2 . In a pref erred ~mho~ , the control aignal generator 12 permits display of video images at a horizontal rocQll~tinn of at least 640 pixels 20 and a vertical resolution of at least 480 pixels 1640H x 480V). In a preferred: ',o1i t of a HMD, the image resolution is at least 1280~ x 1024V.
In another preferred embodiment, the aspect ratio= of the active matrix display panel 9 is selected to be 25 ~ ,-t;hle with ~Iigh-Definition Television (HDTV) formats, such as 1920X x 1080V, 1824H x 1026V and 1600H x 900V.
Furthermore an ~IDTV~ t~hle 1280H x 720V image can be formed in a 1280H x ~ 024V display or a 1280H x 1024V image can be formed in an 1824H x 1026V or 1920H x 1080V
3 0 display . It is understood that other video modes having different video rates and resolutions can be supported as well, with minor modif ications .
The control signal generator 12 converts the synchronization signals 11,13 into pixel timing 35 information for the pixel columns and celect line timing O~5/26110 r~ '/0~670 ~ 21~s7~9 information for the pixel rows of the active matrix. The control signal generator 12 provides control registers to ad]ust and delay the pixel clock 143, pixel data 142, select clock 147, and select data 146 80 the image 5 generated by the video source 1,4 (e.g. VGA, EIDTV) can be precisely mapped to the active matrix pixel resolution (e.g., 640H x 480V; 1280E/ x 1024V). The control signal generator 12 provides a pixel data signal 142 and a pixel clock signal 143 to a data scanner 42 ~FIG. 3). The video 10 signal generator 12 also provides a select line data signal 146 and a select line clock signal 147 to select scanners 46 (FIG. 3).
Preferred embodiments of the invention supply one or four clocks for each clock signal 143 ,147 . By supplying 15 multiple clocks for each clock signal 143,147, the circuitry of the scanners 42,46 can be simplified. This is especially important where the scanners 42, 46 are monolithically fabricated on an SOI structure with the active matrix region 9o and the light box module 7 is a 20 discrete component.
Furthermore, the control signal generator 12 provides a frame switch signal 121 to the video receiver interface 10. The data scanner clock and data pulse rate is ~ t~t~rn;n~-l by the number of parallel video input l-h~nn~lR.
25 The data scanner can scan ~ n~n~;~lly, or alternatively, it can use a random access ~ dLlLe. Note that in another embodiment, the select data 146 or select clock 147 can be used as a serial address line.
Because the video data is received in digital form, 3 0 the video receiver interf ace 10 can generate normal or inverted video data signals in response to the f rame switch signal 121 from the video signal generator 12.
Preferably, the polarity of the video signal is switched every video field (every Vsync). The switch can occur 35 more or less often, as might be desirable to inhibit wo 9~126110 PCrlUS9~103670 crosstalk or other~ purposes.~ The frame switch signal 121 is synchronized to the frame rate.
In a preferred embodiment, a column inversion technique is used to reduce crosstalk between select lines to reduce or avoid the production of a DC offset voltage.
A video switch provides an alternating opposite polarity for the column pixels. The even column pixels are operated at the opposite polarity of the odd column pixels. The polarities of the column pixels are switched on each sequential frame. For example, on one frame even column pixels operate at a positive polarity and odd column pixels operate at a negative polarity relative to the display common electrode. On the next sequential frame, the polarities of the odd and even columns are switched. As a result, the even column pixels operate at a negative polarity and the odd column pixels operate at a positive polarity.
Another preferred ~mho~; of the invention uses a frame inversion technique instead of column inversion.
Using frame inversion, each column during any one frame has the same polarity. On alt~rn~t;n~ frames, as clocked by the frame switch signal 121, the polarity of each column is ~ ever ~e~. In that way, the polarity of the entire active matrix region 90 (FIG. 3~ is inverted on each succesaive frame. This frame inversion Pmho~
does not require the use of distinct odd and even data registers or video drive lines. Other preferred are row inversion or pixel inversion techniques .
The control signal generator 12 can also adapt the writing of each line. For example, in a preferred : ' '; of the invention the image is written for each select line from the edges of the display panel 9 toward the center of the display panel 9. Another preferred ' -'; writes the video data from the center of the .

0 ~5126110 PCTIU~5~0367~
~,31 display panel 9 outward toward the edges. In yet another preferred embodiment, the video data is scanned left to right across the display panel. Each column of the display can also be randomly accessed. These various video data writing techniques are provided under the co~trol of the control signal generator 12.
In a preferred '~ of the invention, the display panel g is driven at 60 Hz frame rate. During each frame, the display panel g is overwritten with data for the three primary color3 (e.g., RGB). Conser~uently, there are 180 subframes displayed per second. This produces a pixel data rate of about 300 Mhz. Because the video data must be in digital form to be stored in memory for time compression, it must be converted to analog signal by digital to analog converters (DACS). However, it would require a super-high speed DAC to operate at 300 Mhz. Consequently, a preferred embodiment of the invention separates the video signal into n rh~nn~l c . The number of channels is a design decision where an increase in the number of channels becomes more difficult to manage while the operating speed of the DACs is lowered.
Preferably, there are sixteen (n = 16) rh~nn~l A of video data and each channel has its own DAC operating at one-s; ~tel-n~h of the total pixel data rate .
Accordingly, the video receiver interface 10 partitions the incoming video data signal 15 into channels of - video data . Each channel carries video data at an offset from the edge of the panel 80 that the rh~nn~l q stagger the video data for the pixels across the display.
For example, with the number of channels being 16 (n=16), the first channel can carry data for every 16th pixel starting from the left-most pixel ~(Cl, C17, C33,...) and the second channel can carry data for every 16th pixel starting form the second left-most pixel (C2, Cl8, Wo9512611(~ q: PCTIUS95/0367 C34, . . . ), etc. The offset fo~ each channel can be selected by the video receiver interface 10.
The video data are fed through an input bus 22 to a video frame memory 25. The vldeo frame memory 25 is 5 addressed by an addressing signal 125 from the control signal generator 12.
An output bus 27 delivers the addressed video data from the video memory 25 to a line memory 32 for each channel. A DAC 34 for each channel reads the video data 10 from the line memory 32, converts the digital video data to an analog video signals input to the panel drive circuit. The analog video signals are amplified by output amplifiers 36-1, . . . ,36-n to yield video drive signals 35-1, . . ., 35-n which are used to drive the columns 44 of 15 the display panel 9 .
The data supplied from the output bus 27 at any one time is either red data from a red frame buffer, or green data from a green frame buffer, or blue data from a blue frame buffer. The appropriate data value is provided via 20 the output bus 27 by the output color select signal 127 f rom the control signal generator 12 .
In a preferred embodiment where the inputs are red, green, and blue data, the color select signals 127 are two-bit data signals. The chosen data value for each 25 channel is converted back into an analog video signal by the channel DAC 34. Each output l;f;Pr 36 amplifies the analog video signal to levels resEuired to drive the LCD circuitry.
The video receiver interface 10 can also receive 30 control ;n~prf~re signals from a user at 17A for adjusting hue, contrast, and brightness and at 17B for inverslon, gamma correction and lir~,uid crystal voltage of f set .
Except for hue, these control interface signals can instead be received by the output amplifiers 36-1,...,36-35 n.

-0 ~5/2C110 PCrlllS951036~0 ~V ~9 - The drive circuitry can incorporate gamma corrections and shading corrections as noted above. Gamma corrections may be re~!auired for each primary color if the electro-optical transfer characteristic (transmission vs. pixel 5 voltage) in the li~uid crystal varies with wavelength Shading correction may be re~uired to compensate f or the length of time that an image row is displayed on the panel 9. The drive circuitry can also incorporate inversion techniques and of f sets .
FIG. 3 is a schematic block diagram of the active matrix drive circuitry. A video signal bus 35 carries the analog video signals from the DAC amplifiers 36 to the column drivers 44. Because signal interference and signal 1088 can occur as the analog video signal crosses each 15 signal line in the signal bus 35, the channels of video signals are arranged to reduce interf erence . As illustrated, there are four column drivers 44a-44d, two column drivers 44a, 44b at the top of the active matrix region 9o and two column drivers 44c, 44d at the bottom of 20 the active matrix region 90. ~ach channel is allocated to one of the column drivers 44 such that each column driver 44 receives video from four channels. As illustrated, the top column drivers 44a,44b receive video from =he channels that drive the odd-numbered columns and the b~ttom column 25 driver~ 44c, 44d receive video from the channels that drive the even-numbered columns. As shown, no video signal has to cross the path of more than one other video signal.
The illustrated - ~ L~lly of column drivers is particularly suited for edge-to-center and center-to-edge 30 video writing, although the data can also be written from left-to-right or right-to-left. It should be understood that more or less than four column drivers 44 can be employed in preferred ~mhC~; ~A of the invention.
The data scanners 42 are responsive to the pixel data 35 signal 142 and the pixel clock signal 143. The data _ wossn6ll0 ~ . PCTnJS95/03670 ~,~' scanners 42 can use a shift register array to store data for each scan. An odd shift register array can be used to store data to odd column pixels and an even shi~t register array can be used to store data to even column pixels. As 5 illustrated, there are left and right odd data scanners 42a,42b and left and right even data scanners 42c,42d.
The column drivers 44 selected by the data scanner ~2 will transmit video data to a selected column C in the active matrix region 90. The select scanner 46 determines lO by control lines which pixels accept this column data.
To reduce signal loss across the active matrix region 90, the select lines are driven ~rom both sides by select scanners 46. As viewed in E'IG. 3, a left select scanner 46a and right select scanner 46b are connected to the 15 select data line 146 and the select clock line 147.
A third enabling line 148 can also be used aEter specific applirat;~ . The left select scanner 46a provides a select line signal at the end of the select line nearest the lowest-valued pixel column (Cl) and right select 20 scanner 46b provides a select line signal at the end of the select line nearest the highest-valued pixel column (CN). Thus, an identical select line signal is supplied=
at both ends of the select line.
although static shift registers can be used, the 25 shift registers of the data scanner 42 and the select scanners 46 are implemented as dynamic shift registers.
The dynamic shift registers rely on capacitor storage without leakage. However, dynamic shift registers are susceptible to leakage, especially when they are exposed 3 0 to light . Hence, light shields are needed to protect the s~ .e,~ 42,46 from exposure to light. Similarly, light shields are also used to protect the transmission gates 44 and pixels.
In another preferred, '1 t of the invention, the 35 select scanners 46 are random access select scanners.

~VO~5/26110 ~ PCT/US95/03670 ~' i ,~, ~
) Each random access select scanner can be addressed to drive any row of pixels during any pixel clock period. As such the select scanners 46 need not include shift registers. The select line i8 directly provided by the row select signal 146, which is implemented as an address bus .
In another preferred: ~_a; t of the invention, the data scanner 42 is a random access data scanner to select any column of pixels for any clock period. When used in conjunction with random access select scanners, the light box module 7 can actuate any pixel on the active matrix region 90 during any pixel clock period. This: ~ ~a~; t requires the use of double gate pixel transistors for receiving two digita~ select inputs (row select and column 1~ select) to signal pixel act~l~ti~n with the video signal for the selected pixel. With a fully random access active matrix region 90, data compression technigues with burst mode refresh of the video frame memory 25 can be used to write changed pixels to the display.
In a preferred ~ of the invention, the panel drive circuitry of FIG. 3 is fabricated as an integrated circuit with the active matrix region 90. The integrated circuitry i5 preferably fabricated in single crystal silicon having a silicon-on-insulator (SOI) structure using the fabrication and trangfer ~LU~ uL~8 ~ c-~r;h~
previously. By fabricating the row and column drive circuitry 42,44,46 in single crystal with the active matrix region 90, the size of the display panel is not constrained by the c~nn~ t;n~ pins for the various discrete .- ~ q. The integrated fabrication also increases the operating speed of the display over displays constructed from discrete . r,n,ontc. Furthermore, the drive circuitry can be optimized to increase display perf~rr^n~.o. For example, it is easier to construct a 3~ 35mm format-~ _ tihle 1280H x 1024V display panel with u~o ~5/2Gll0 rel/u~j5/03670 dual select sca~ners through integrated fabrication than it is using discrete ~ ^nt~, The pixels in a pref erred ' '; t are:
approximately 24 microns sguare. Conseguently, a 1280~I x 5 1024V active matrix with the control system can be fa~ricated such that there are two such integrated circuits on a four inch wafer, four circuits on a five inch wafer and six circuits on a six inch wafer. In another preferred embodiment of the invention, the select 10 scanners 46, the data scanner 42 and the column driver 44 are integrated on chip with the active matrix region 90.
FIG. 4 is a schematic diagram illustrating a pref erred color seguential display system according to the invention. AB illustrated, a light source 200 having a 15 reflector generates a beam of white light 205 that i8 focused on a dichroic mirror assembly 210. The dichroic~
mirror assembly 210 separates the white light 205 into three parallel strips of primary color light 211, 212, 213 separated by unlit black bands 214. Preferably, the 20 primary color light i~ red light 211, green light 212, and blue light 213. The strips of red, green and blue light become ;nr~rl.ont on a prism 220 which is rotatably about a center axis 225 under the control of the drive signal 145 from the control ~ystem of FIG. a. The prism 220 is 25 rotated such that the color strips 211, 212, 213 scan vertically downward relative to the f igure .
FIG. 5A-5C are views of the rotating prism 220 of FIG. 4. The prism acts as a tilted parallel plate to move the color stripes as it rotates. When the facing surface 30 221 is perpendicular to the incident li~ht rays (FIG. 6A) the light rays are passed directly through the prism 220.
AB the prism is rotated, the facing surface 221 becomes ~
tilted relative to the ; n~ .nt rays (FIG. 6B) . The bottom color stripe 213 is scrolled to the top position 35 and the other color stripes 211,212 are scrolled downward.

~095/26110 ~7~ P~TIIIS95/03670 This process i3 rnn~ i n~ d in FIG . 5C . Each time a color stripe reaches the bottom, rotating of the prism 220 redirects the color stripe to the top from where the stripe repeats its downward motion.
Rrtllrn;n~ to FIG. 4, a field lens 230 can be used to align the color stripes exiting from the rotating prism 220 with the active matrix display 90. Using the scanning prism 220, every part of the light valve is exposed equally with rapidly altrrnAt;nrj colors and the full spectrum of the light source 200 i8 utilized at all times.
Immediately af ter a color stripe passes a row of pixels, refresh begins with picture information pertaining to the next color. The prism 220 inherently produces dark bands betwee~l the RGB color stripes which Ar~ ' te the finite response time of the light valve.
A projection lens 240 can be used to project the image generated on the active matrix region 90 to a user.
The active matrix region 9o must be addressed and supplied with video information consistent with the scrolling illumination. To this end, the active matrix region 9o is partitioned into three equal height segments as shown in the views of FIGs. 6A-6C.
Each segment is scanned by the row dr, vers 46a, 46b (FIG. 3). The row drivers 46a,46b can be enabled seqn~nt;Ally in a fixed top-middle-bottom order. However, the row drivers 46a, 46b can also implement non-linear 8rAnn; n~ . The control gignal generator 12 also ac~ '-t,o~ non-linear scanning, which is a function of the rotating prism (and liquid crystal speed). The liquid 3 o crystal speed can vary due to temperature wavelength . The control signal generator 12 compensates for any liquid crystal speed variations when producing control signals.
Timing is ~y . -~ such that active rows closely track the ill~;nAt;nn pattern in each segment. The video data, written to the ;n~lDr~nfl~nt RGB frame buffers 25-xR, ,, Wo 95/26110 PCT/US9~103670 25-xG, 25-xB is re~rieved under -control of the color ~ ~
select signal 127 offset by one-third of~ the display height. The RGB data are first time compressed and then line-by-line multiplexed into the serial format required 5 by the column driver 44. FIGs. 6A-6C illustrate the color segments 91,92,93 corresponding to the red stripe 211, green stripe 212 and blue stripe 213 as scrolled in respective FIGs. 5A-5C.
By using color stripes, the duty cycle of the 10 available light incident on the display can be m_~; m; 7,orl .
Additionally, there is reduced variation in the hr; ~htnf.~z~
from the top to the bottom of the display because each line is active with each color for exactly the same amount of time. This is not true with color schemes that change 15 the color of the entire display after writing a frame of data where two of the colors have been removed ~rom light being transmitted through the light valve at any one time.
FIG. 7 is a schematic diagram of a preferred color sequential system using a rotating color cone. A light 20 source 200 having a reflector generates a white light 205 focused on a cone 250. The cone 250 is divided into three equal segments, one red, one green, and one blue. As the white light 205 becomes iIlcident and passes through the color cone 250, an ~Yr~n~;nq beam of color light 251 is 25 produced. The color of the colored light 251 is rlPr,on~nt on the color of the cone segment transmitting the light.
The color light 251 is focused by a field lens 260 into parallel rays of light which are transmitted through the active matrix region 90.
The color cone 250 is rotated by a motor 255 coupled to the cone 250-by an axle 256. The motor is synchronized to the frequency of the drive signal 145 from the video signal generator 12 of FIG. 2. ~he color select signal 127 is also synchronized to the retention of the cone:250 to provide data from the red buffer 25-xR, green buffer O~5/~6110 1~ 67û
~8S72D
, 25-xG and blue buffer 25-xB in sequence to the column driver 44.
FIG. 8 i9 a schematic block diagram of a color shutter display system, Illustrated i8 a color sequential drive circuit 407, which accepts VGA input in either analog or digltal form and other standard or proprietary video inputs. The drive circuit 407 itself can be either digital or analog as will be described in detail below.
A lamp 410 projects white or RGB light through a field lens 420. The lamp 410 can either be a rnnt;n7ln1lq light source or a flashing light source. The light output from the field lens 420 is collimated on an electronic color filter system 430.
The drive circuit 407 controls the color filter system 430 over a color signal bus 435. Under the control of the drive circuit 407, the color filter system 430 passes either red, green or blue light. In certain applications, it is adv~nt~ u~ for the color filter system 430 to also block all light.
The filtered light from the color filter system 430 is roll;r~tPfl on an active matrix LCD 90. Preferably, the color filter system 430 is transferred from a substrate and epoxied to the LCD 9o to form a single module.
Alternatively, the color filter system 430 can be transferred and epoxied to the field lens 420 or elsewhere in the optical path. The active matrix LCD 90 is controlled by the drive circuit 407 over a data bus 495 to form an image. The image formed on the active matrix panel 90 i9 projected by an output l-.ls 440 onto a viewing surface 450, which may be a projection screen or rear projection Fresnel lens. The output lens 440 can also be a viewing lens f or use in direct viewing of the active matrix image.
FIG. 9 is a schematic diagram of a ferroelectric liquid crystal (FLC) color generator as a color filter _ _ _ _ _ _ WO95/2611~ rC~/Uss~103670 'l.'~

system 430 according to a preferred embodiment of the invention. Illustrated is a two-stage multiple wavelength blocking filter, incorporating fast switching ferroelectric liquid crystal surface stabilized SSFLC~
5 cells (Fl...F5). The stages are defined by polarizers Pl . . . P3 and there are two FLC cells Fl, F2 in a f irst stage bounded by crossed polarizers Pl, P2 and three FLC cells F3, F4, F5 in a second stage, bounded by parallel polarizers P2,P3. The color filter system 430 i8 designed to lO selectively transmit three visible colors (red, green and blue), and is capable of rapid color switching to ge~erate a visual display of a continuous range of visible colors.
The tWo-Etage blocking filter of FIG. 9 generates a tr~nr ~ ; nn output centered at 465 nm (blue), 530 nm (green) and 653 nm (red). The color filter system 430 consists of three ;n-l~or~nA~n~ two-stage birefringent filter designs which are electronically selectable. For each output, the product of the transmission spectrum of each stage yields a narrow highly transmitted band 20 centered at a chosen wavelength, here a primary color, while effectively hlnrk;n~ all other visible wavelengths.
Preferably each stage should have a common maximum centered at a selected color (i.e., primary color). For effective out-of-band rejection, additional maxima for a 25 particular stage must rr;nr;-l~ with minima of another stage .
Each selected band to be transmitted (for example, each primary color band) is produced by switching at least one FLC cell in each stage. Switching more than one FLC
30 cell in a particular stage increases retardation, -thus changing the transmission spectrum . The blocking f ilter consists o~ two stages, one bounded by crossed polari2ers ~?l,P2, the other bounded by parallel polarizers P2,P3.
The polarization of each polarizer is shown by the arrows.
35 The filter contains the five FLC cells Pl...P5, each with _ -~o 9~/2Cl~() ` 8S7~9 ~ PCT/US9~/03670 "

a selected thickness of liquid crystal, arranged between the polarizers. The arrows shown on each FLC cell, and the corresponding angles (~Yl-0~5), represent the orientation of the optic axes with respect to the input 5 polarizer. These angles can be either 0 or ~r/4 radians.
The transmission of the filter is the product of the transmission spectra of the individual stages. A stage with multiple ;n~ r~n~l~ntly switchable FLC cells can produce multiple tr~nrm;c,sjnn spectra.
The irst stage consists of two FLC cells Fl,F2 between the crossed polarizers Pl,P2. By switching the second cell F2 (cY2=7r/4 ), the output is centered in the green (530 nm) and has minima at 446 nm and 715 nm.
Switching both cells F1, F2 (~ 2=1r/4 ) produces a spectrum 15 that has maxima at 465 nm (blue) and 653 nm (red), with a minima at 530 nm.
The second stage consists of three cells F3, F4, F5 between the parallel polarizers P2, P3 . With only the fifth cell F5 switched, the output has a maximum at 442 nm 20 (blue) and a minimum at 700 nm. Switching all three cells F3, F4, F5 produces an output having a narrow band centered at 530 nm. The function of the second stage is to narrow the green output (obtained with cell F1 switched), and to select between the blue or red outputs produced when the 25 first stage FLC cells Fl,F2 are both switched. Switching the f if th cell F5 blocks the red output of the f irst stage while transmitting blue output. Switching both the fourth and fifth cells F4,F5 strongly transmits the red at 610 nm, while h1nnl~;n~ blue output at 470 nm. Switching all 3 0 three cells F3, F4, F5 of the second stage narrows the green output (530 nm) from the first s~age.
The source ,.~e.:LLu"l (i.e., white light) can be transmitted by the filter by switching the first FLC cell F1 only. The first cell F1 is a zero order half-~aveplate 35 over most of the visible. Therefore, when the first cell v.o95/2611~ ~?9 PCTIU~9S/03670 ~
.

Fl is switched, the i~put polarization is rotated by 7r/2 to align with the optic axis of the second cell F2 and the exit polarizer P2. Because the second stage is between parallel polarizers, none of those cells F3,F4,F5 need be 5 switched. A summary of switching re~uirements llPrl'R~ lry to obtain all outputs i8 provided below in Table l.
Table l. Summary of Switching Re~auirements for the FLC -Blocking Filter of FI~ 7.
OUTPUT al a2 a3 a4 aS
10 ~HITE 7r/4 0 0 0 0 Bl~UE 1r/4 7r/4 o O r/4 GREEN 0 ~r/4 ~r/4 7r/4 ~r/4 RED 7r/4 ~r/4 0 1r/4 ~r/4 15 The thi~kn~R~es of the FI-C cells Fl.. F5 are; 1.8 fim, 5 . 2 ~m, 2 . 6 ~m, 1. 7 ,um, and 6 .1 ~lm, respectively . The cell substrates are two )~/l0 optical flats, each having one side coated with an ITO transparent electrode. The ;1l ;~ ' R layer i8 preferably an oblislue vacuum deposited 20 layer of sio. Typically, the transmission of a single cell without an antireflective (AR) coating is 90~6. By using HN42HE dichroic polarizers Pl . . . P3, i n~ the cells in each stage together with index matching epoxy and AR coating exterior surfaces, the filter can transmit 50~6 25 of ;n~ nt polarized light.
The blocking filters have been described specifically for use with an apparently white light source. They have been ~Ri~nPri particularly to produce ~ -t~ wavelength transmission in the visible spectrum. ~ more detailed o ~5126110 8$7~ PCTIUS95103670 description of tunable filters employing FLC cells i8 provided by Johnson et al. in U.S. Patent No. 5,132,826, entitled "Ferroelectric Liquid Crystal Tunable Filters and Color Generators, " the ~Arh;nrJ~ of which are incorporated herein by reference. It will be clear to those of ordinary skill in the art that sources other than white light can be employed with FLC blocking filters. The modifications in FLC thickness, choice of materials, source light, etc. required to employ FLC filters for different light sources and in different wavelength region can be readily made by those of ordinary skill in the art.
In blocking f ilters, the thickness of the FLC cells and the relative orientations of the polarizer elements are selected to optimize trAnr~; QQion of desired wavelengths in the hlnrk;nr filter and minimize transmission of undesired wavelengths. FLC cells with the required ~h; rkn~ A and optical tr~nrm; QAinn properties for a particular color generation application can be readily fabricated using techniques known in the art. The color blocking filters, like those of FIG. 9 can be readily adapted for temporal color mixing such as for Lyot-type f ilters . Application of an appropriate voltage duty cycle scheme to switch the desired pairs of FLC cells can generate a range of perceived colors (color space).
In addition, a hlok;n~ filter can be designed to transmit the sGuYce light (moat often white) with no wavelength ef~ect in one switched configuration state, and transmit no light in another switched state (black). FLC
pulsing schemes of such a filter can include switching to white and black to allow more flexible selection of generated colors. Blocking filters switching between two selected wavelengths or more than three selected wavelengths can be implemented by appropriate selection of FLC cells (thi rknP,QQ) and positioning and orientation of 35 polarizers. Additional spectral purity of transmitted ;- i Wo95/2GI1o ~ r PCT/US~5/0367 color ~i.e., narrower band width) can be achieved while retaining hl ~rk; n~ of unwanted colors by i~creasing the number of stages in the f ilter with appropriately selected FLC cells in the stages.
In a preferred: air ' of the invention, chiral smectic liquid crystal ~CSLC) cells are used as the FLC
cells Fl...F5. Color generators using CSLC cells are available from The University of Colorado Foundation, Inc.
as described by Johnson et al . in U. S . Patent No .
10 5,243,455 entitled "Chiral Smectic I,iquid Crystal Polarization Interference Filters, " the t~ h;ngq of which are incorporated herein ~y reference. A unique characteristic of CS~C cells is their f ast switching speeds ~order of 10'8 to 100'8 of ~sec). Filters of the 15 present invention are capable of greater than 10 kXz tuning rates, for example between two or more discrete wavelengths. In situations where relatively slow response detectors are used, such as with photographic or movie film, or the human eye, pseudo colors can be generated 20 using the rapidly switching filters described herein.
Rapid switching between two primary color stimuli can be used to generate other colors, as- perceived by the slow detector, which are mixtures of the primary colors. For example, the two ~l ' ; c stimuli, 540 nm ~green) and 25 630 nm (red) can be mixed in various portions to create the perception of orange (600 nm) and yellow (570 nm).
Optically, this mixing can be done by varying the quantity of power of the primary stimuli in a transmission. The same result can be achieved by 30 switching between the two stimuli~ (spatially superimposed or closely adjacent) at rates faster than the response time of the eye (or any detector which averages over many periods). Color can be generated in this way using the filters described herein by varying the time ~or which the 35 filter is tuned to any particular primary stimulus ~o~sl26l~n 8~ PCTlllS9~103670 ~l8s729 compared to another primary stimuli. By changing the percentage of a square wave period during which the filter is tuned to one of the primary stimuli with respect to another (i.e., varying the duty cycle of an applied 5 voltage, for~example), there is a perceived generation of colors which are mixtures of the primary inputs. In effect, the r~,uantity of optical power transmitted in each primary stimulus is varied by changing the ratio of time which the f ilter is tuned to each of the primary bands .
10 Because the response time of the human eye is about 50 Hz, the eye will average optical power over many cycles of filter switching, and many colors can be generated for visual detection.
FIG. 10 is a schematic block diagram of a digital 15 falling raster system. The digital falling raster system is similar in construction to the FLC color filter system 430 illustrated in FIG. 9. Here, the color filters F1', F2', F3', F4', F5' of the color filter system 430~ are each eriually divided into three horizontal sections Fla', 20 Flb~, Flc', . . ., F5a~, F5b', F5c' . Each section Fla', . . . ,F5c' is separately addressed and controlled by the FLC driver 270' 50 the system produces three color stripes as an output at any one time. Each color strip may be either red, green, blue or black, with black used 25 during data writing to the LCD 9o . This is ~ l; Fzh~
by using three individual electrodes on each color filter, instead of the single electrode described above with respect to FIG. 9.
As can be seen, the number of electrodes on the FLC
3 o f ilters F1~, . . ., F5 ' can be increased to increase the number of color stripes for displaying color images and thus the duty cycle of the light ; nr; ~-~nt on the color filter system 430. For example, there can be one color stripe for each line of the LCD 90. This would permit 35 more ~ff;r;f~nt color display techniques.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Wo 95126110 Q~'19 Pcr/Uss~/03670 --2 8 ~
FIG. ll is a schematic diagram of a preferred embodiment of an FLC color filter Fx' ' having an arbitrary number of electrodes El...E~. Preferably, there is one electrode B per display line of the ~CD. An FLC Driver 270~ ~ is preferably fabricated with the electrodes as a single circuit module, one for each F~C filter Fx' ' . The FLC Driver 270 ~ ~ ; nr~ a color decoder 276 and a select line scanner 278 ~ The F~C Driver 270 ~ ~ receives a row address from the select data address bus 146~ the select clock signal 147~ and a color select signal 127 from control circuitry (not shown).
The decoder 276 of each FLC Drive 270~ ~ is tailored to the specific FI.C color filter Fx' ' in the resulting color filter system. Conse~auently, the decoder 276 will either enable operation of the select scanner 278 for a particular color or inhibit such operation, according to the above table in response to the color selection signal 127~ The enablement signal is provided to the select scanner over enable line 148~
The select scanner 278 receives the select line addres3 279 and, if enabled by the decoder 276~ energizes the selected electrode B. If the decoder 276 has not enabled the select 8canner 278 ~ then no action is taken by the select scanner 278 for the addressed row.
As another alternative, each display pixel or block of display pixels (i.e., superpixel) on the ICD 90 can correspond to an individual color filter by forming an active matrix on the color filter system 430, which are registered to the pixel electrodes on the I,CD 90. This ' ~i t permits random color access for each pixel on the display 9o. Such a random color access in combination with random access select and data scanners of the display panel 90 permits full color burst mode re~resh of the displayed image.
.

o 95/261 l0 PCT~ss~/o367o ~ 218~72~

Returning to FIG. 8, if the lamp 410 is a flashing light source, then a lamp controller 415 (shown in phantom) is used to control the fl~qhin~r of the lamp 410 via a flash synchronization line 417. The lamp controller 5 415 is under the control of the drive circuit 407.
FIG. 12A is a schematic timing diagram for a flash color shutter system. Illustrated i5 one frame of standard parallel RGB video. Typically, there are 60 f rames of RGB video per second . For each color to be 10 displayed, the drive circuit 407 writes data to the LCD 90 over the data bus 495. The drive circuit 407, while writing the color data, switches the color filter system 430 to the color corr~Rr~n~lin~ to the color being written to the 1: CD 9 0 . Af ter the color data in the video f rame has been written, the drive controller 407 signals the lamp controller 415 to flash the lamp 410. The steps repeat with the next color. Tvpically, the color filter system 430 is switched and the lamp 410 flashes at 180 Hz (i.e., three times per video frame, once for each color).
FIG. 12B is a timing diagram of a continuous light color shutter system . Illustrated is one f rame of standard parallel ~GB video. The drive circuit 407 of data switches the color filter system 430 to black and color data is written to the LCD 90. After a complete video frame of data has been written to the LCD 90, the drive circuit 407 signals over signal line 435 to the color filter system 430 to switch to the color filter corrF'qprn~li ng to the color data written to the ~CD 90 .
FIG. 13 is a schematic block diagram of a digital drive circuit 407 having a wide bit width low-speed R~M.
An analog digital signal is separated into red, green and blue ch~nn~ . For the red channel, the analog signal is adjusted by an input circuit 510R, which inrl~ a variable gain amplifier 512R to adjust contrast and a potentiometer 514R to adjust brightness of the video ,, , , , _ _ _ . . . _ ...... .

WO 75/2G I l o 1, ~ ,, 5 1~70 signal. The output from the input circuit 510R i5 converted to an 8-bit digital signal by an analog-to-digital (A/D) converter 515R. The A/D converter :515R
preferably operates at about 108 MHz for a 1280H x 1024V
display.
A series of parallel latches 520R separates the input digital into m channels 520R-l, . . . ,520R-m. As illustrated, there are m=16 channels and therefore there are 16 latches. ~ach latch represents one column of the o display. The latched outputs ara fed to a frame memory 530R, where the digital read data is stored in either a play frame memory 532R or a capture frame memory 534R in a 16 column by 8-bit format. Preferably, the latches 520 and the frame memory 530 operate at about 6.75 MHz for a 1280H x 1024V display. Such c ~ n~a are readily available. The total frame memory 530 required is about 7. 8 Mbytes for this particular ~
The appropriate frame memory 530R is selected by a digital 2:1 multiplexer 540R and the 16 column by 8-bit data stream is fed to a digital RGB multiplexer 550. The green and blue channels are identical to the above described red channel . The digital 2 :1 multiplexer preferably operates at about 21.25 MHz for a 1280H x 1024V
display .
The digital RGB multiplexer 550 is a 3 :1 8-bit multiplexer for time multiplexing the red, green and blue video data . The output f rom the digital RGs multiplexer 550 is fed over a 128-bit video bus to m DACs 560-1, . . ., 560-m. E:ach DAC 560 represents an input channel 3 0 to the active matrix drive circuitry . An output network 570 is disposed between each DAC 560 for providing amplified analog signals to the drive circuitry. The output network 570 can invert the analog signal to implement column or frame inversions on alternate video 35 frames. As illustrated, the even columns are driven by .

O~512611n ICIllJ.. 'IQ~670 the positive gain amplifiers and the odd columns are driven by the negative gain amplifiers. This reverses on each succe6sive video f rame .
FIG. 14 is a schematic block diagram of a digital drive circuit 407 having a narrow bit width high-speed R~M. The RGB analog signals are separated into separate channels and input to respective input circuits 610R, 610G, 610B, which each include a variable gain amplifier 612R, 612G, 612B to adjust contrast and a potentiometer 614R, 614G, 614B to adjust brightness of the input video signal. The output from the input circuits are fed to respective A/D converters 615R, 615G, 615B to produce respective 8-bit digital color data. A8 above, the A/D
converters 615 operate at about lOa MHz for a 1280H x 1024V display.
The 8-bit color data is stored in respective R~M
620R, 620G, 620B. The R~M is divided into two video frames 622, 624, one for capture and one for playback.
Capture is at 108 MHz (60 frames/sec) while playback is at 324 MHz (180 frames/sec) . At present, special multiplexed memory must be used to operate at such high rates. For a 1280H x 1024V display, 7.8 Mbytes of R~M is re~uired.
The s~ ctinn of the video frame is selected by a 2:1 multiplexer 630R, 630G, 630B under the control of a capture/play signal. The multiplexers 630R, 630G, 630B
input 8-bit color data into an RGs multiplexer 640.
The RGB multiplexer 640 is operated under control of a timing signal generated at three times the vertical synchronization signal (VSync). A phase lock loop (PLL) 690 generates pixel clocks (PClk) coherent with the horizontal synchronization signal (HSync) at three times the original input rate. The output from the PLL 690 is ~, ~.c~ss~d by a divide-by-three circuit 695 to generate color data timing signals (PClk) for controlling the 35 , , l in~ at the original input rate and a divide-by-Wo 9~/26110 PCTIUS95/03670 ~ 5~

sixteen circuit 697 to generate pixel multiplex (i.e., capture/playback) signals (PIXE~IUX) for controlling the latch outputs for playback of the video signal.
The RGB multiplexer 640 separates the 24-bit color 5 data into 16 video input channels to the LCD 90. Each channel includes a pair of latches 650. A multiplexer 660 selects output from one of the latches 650 and feeds that output to a DAC 670. For a 1280H x 1024V display, the latches operate at about 21.25 MHz. An output network 680 10 amplifies the analog voltage for use by the active matrix drive circuitry and provides column inversion.
PIGs. 15A-15B are schematic block diagrams of an analog drive circuit 407. FIG. 15A is an analog front end circuit. The red, green and blue analog signal are each 15 processed by a respective A/D converter 715R, 715G, 715B
to produce an 8-bit digital, data signal. The 8-bit color data is received by a frame memory 720R, 720G, 720B. Each frame memory is divided into even and odd frames 722, 724.
Por a 1280H x 1024V display, the frame memory 720 operates 20 at about 108 MHz.
A 2 :1 multiplexer 730R, 730G, 730B operates under control of an alternate frame signal to select one of either the even or odd frame. The 8-bit output from the multiplexers 730R, 730G, 730B are received by a 3 :1 RGB
25 multiplexer 740. The three colors are time sequenced by the RGB multiplexer 740 to yield a 24-bit digital signal.
A DAC 750 converts the 24-bit digital signal to a sequential RGB analog video signal. Por a 1280H x 1024V
display, the sequential RCB signal is operating at about 3 0 324 MHz .
FIG. 15B illustrates the drive circuitry for processing the ~ n~i~l RGB analog video signal from FIG. 16A. The sequential RGB video signal is received by an input circuit 760 which includes variable gain 35 amplifier 762 to adjust contrast and a potentiometer 764 ~'O 95/26110 8S7~ ~ r.~ 670 to adjust brightness. The input circuit 760 provide6 both even and odd video signals. A switch 770 selects between the even and odd video signals to provide for column inversion. An output network 780 is also switched to provide two sets of 16 channels - one set holds signals to display while the other set sampling data for display on the next cycle. The output network 780 is preferably a sample and hold network. The sample and hold circuitry of the output network 780 may be too slow to operate for a 1280H x 1024V display, but would be suitable for a 640H x 480V display.
FIG. 16 is a timing diagram of the drive circuit o FIG. 15B. There are 32 sample-hold amplifiers in the output network 780, two for each of the 16 output channels . The , l; f i ~s are switched in response to a signal generated every 1/16 of the pixel clock period.
While one of the amplifiers per output channel is sampling the RGB signal, the other is holding the previously sampled data for the display.
FIG. 17 is a ~ ' t;c diagram illustrating a color seguential system using liquid crystal shutters. Liquid crystal cells S1, S2, S3 are used as a light switch instead of mechanical switches or other types of switches.
A beam of white light 205' passes through a first polarizer~P1' and is divided into blue, green and red ~ -ntq by respective mirrors Mla, M2a, M3a. The first mirror Mla passes blue light to the blue shutter S1 and reflects red and green light to a second mirror M2a. The second mirror M2a receives the red and green light r~fl !~rtf~ from the first mirror Mla and reflects the green light to the green shutter S2 and passes the red light to the third input mirror M3a. The third mirror M3a reflects the red light toward the red shutter S3. The shutters S1, S2, S3 are controller by a shutter drive 280. The shutter 35 drive 280 is tied to the color select signal 127 from the Wo 95/2611U PCTIUS9S/03670 ~:' .

video signal generator 12 of FIG. 2. The shutter driver decodes the color select signal and actuates the appropriate shutter S1, S2, S3 to pass the corresponding colored light.
If the blue shutter Sl is actuated, the blue light is passed through the first exit mirror Mlb. If the green shutter S2 is actuated, the green light is reflected by the second exit mirror M2b and the first exit mirror Mlb.
If the red shutter S3 is actuated, the red light is reflected by the third exit mirror M3b, passed through the second exit mirror M2b and reflected by the first exit mirror Mlb. The selected exit light 219 is then passed through the active matrix region 90 as prçviously described herein ri1 FlpQ5~'~ between parallel polarizers:
P2' ,P3~ . The active matrix display 90 is controlled in con~unction with driver 280 to provide color ~ .onti~l imaging .
FIGs. 18A-18B are schematic diagrams illustrating another preferred ~mho~i~ of the invention employing a rotating prism. In FIG. 18A, a light source 200' generates a strip beam of white light 205', which is focused as a linear horizontal stripe 335 on a deflector 330. The deflector 330 can be tilted relative to the vertical plane by a translator 331. The translator 331 is coupled to the deflector 330 via an axle 332. The tr;~n~l ~t~r operates under the control of the drive signaI
145 from the video controller signal generator 12 of FIG.

2. As the deflector 330 is rotated, a deflected strip of white light 205~ ~ is directed toward a color shutter 340.
The optics are aligned such that a strip of light 345 is incident horizontally across the color shutter 340.
The resulting strip of colored light 219' ' is focused as a color strip 95 on the active matrix region 90.
Rotation of the deflector 330 thus results in a color light beam 95 scanning down the active matrix region 90.
.

~5/2C110 ~ 7~ PCT/US95/03670 In the preferred ~mh~rl;r^nt of the invention, the strip of colored light 95 incident on the active matrix region 90 i8 registered to a line of pixel electrodes registered to the operation of the translator 331. Although the 5 translator 331 is shown as a mechanical device, an electronically actuated beam deflector 330 could be substituted. In another~ preferred embodiment of the invention, the lit pixel row 95 can be randomly selected by operation of the deflector 330.
FIG. 18B is a schematic diagram that illustrates the use of a sr~nn;n~ dot or point to ;llllm;n~te the active matrix region 90. The system of FIG. 18B differs from that of FIG. 18A in that a light source 200 generates a converging beam of light 205, which is focused to be 15 ;n~ nt at a point 339 on a deflector 330. The deflected white light 205''' is deflected to be in~;tl.-nt on the color shutter 340 also at a point 349. The colored beam of light 209' ' ' then becomes ;n~ pnt at a pixel location 99 of the active matrix region 90. The ~ lP~-tor 330 is 20 controlled by a vertical translator 331 as in FIG. lOA and a horizontal translator 333. The vertical translator 331 is controlled by the control signal generator 12 of FIG. 2 by the row address signal 125. The horizontal translator 333 is controlled by the video control generator 12 of 25 FIG. 2 via the pixel data signal 142.
The pixel 99 of the active matrix display region 90 is registered to the v of the translators 331,333 such that the translators can position of the deflector 330 in a plurality of discrete ori~ntPti~n~, one discrete 30 orientation for each pixel of the active matrix region 90.
As discussed with rega~d to FIG. 18A, the beam deflector 330 can be electronically actuated. In addition, the beam can be scanned across the active matrix region 90 in a raster scan fashion.

WO95126110 ~ ~, PCTIUS9S/03670 J~
~,9 FIG. 19 is a ~ t; ~ illustration of one embodiment of a LCD projection system 1300 using color sequencing to produce a full-color image. The 8ystem 1300 ;nf-lllrl~c three monochromatic LED point or line sources 1350, 1352, 5 1354, which produce red, green and blue light, respectively. A parabolic mirror 1356 behind the point or line sources 1350, 1352 and 1354 directs light from the sources through a diffractive or binary optic element 1358. The binary optic element 1358 splits the ;n~ nS
10 light into multiple parallel horizontal bands of ~ L tic light which are perpendicular to the page of the drawing. The bands of light are ordered in color along the vertical axis in a repeating pattern. For example, a red band is followed by a green band which is 15 followed by a blue band which is followed by another red band, etc. The colored bands are pro~ected by a field lens 1360 onto the LCD panel 1362. The colored bands from the binary optic 1358 are spaced such that alternating rows of pixels in the ~CD are; l l nAte~l by a single 20 colored band. The pixel rows between the illl m; nAtPtl rows remain black, i.e., unill nAt~d. Light passing through the LCD 1362 is projected by projection lens 1364 onto a pro~ection screen 1368.
A full-color imagé from the LCD 1362 is produced by 25 color seS~uencing through the pixels. To perform the color seSIuencing, the binary optic 1358 is movable along the vertical axis as indicated by the arrow 1370. A
controllable actuator 1372 controlled by a controller 1374 is coupled to the binary optic 135a 80 as to control the 30 vertical ,v~ of the optic 1358. I~ one :~` '; - t, the A~tl~t-lr 1372 is a stepping actuator controlled by step pulses on control lines 1376 from the controller 1374. In an alternative: ' '; ~, the field lens can be controllably moved along the vertical axis and/or tilted 35 about its normal axis. The alternative actuator 1332 and ~!095/26ll0 ~l8s PcT/Uss~/03670 72~

its associated controller 1334 are shown in phantom in FIG. 19 coupled to the field lens 1360.
In each stationary position of the binary optic 1358, alternating rows of pixels of the LCD 1362 receive light of a single color and transmit the light according to pixel data loaded into the LCD 13 62 . At the same time, the unillllm;n~ted rows interposed between the illl~m;n~
rows are addressed and loaded with pixel data from a LCD
controller 1378 along lines 1380. When the unilluminated rows are ;~ m;n~ted in a subsequent step, they transmit the light according to the loaded pixel data.
The pixel data controls whether particular pixels will pass or block the light of a particular color when they are illuminated by tha~ color band. To control the intensity of the color, in an LCD using a ferroelectric LC, the pixel data also includes data which controls the duration of time during which the pixel will transmit light of the color. That is, pixels which require a large amount of blue in their final colors will be set for tr~nr=;RR;on durations longer than those requiring a small amount of blue. In an LCD using a twisted nematic LC, the pixel data for each pixel encodes an analog voltage level applied to the pixel to control grey scale level and, therefore, the color intensity transmitted by that pixel.
The stepping actuator 1372 is pulsed by the controller 1374 to step the binary optic element 1358 through successive stationary position6. At every other position, each row of pixels transmits light of a particular color. When the binary optic element 1358 steps through six positions, each row of pixels has received all three color bands and has theref ore produced a frame of full-color data.
The binary optic element 1358 can be produced by etching desired shapes directly into the surface of an optical material, such as glass, using photolithographic wo ~5/26110 , ~ u.,,5l~3670 and microfabrication technir~ues in order to produce a controlled variation in gla3æ thickness. The binary optic element 1358 then creates the desired output light pattern by ~7i ffrRrtinn . The controlled_variation ir, thickne~s of 5 the element 1358 breaks up the wave front of incoming light at each point on the element' 8 surface and reconstitutes it as a wave traveling in the desired:
direction. The phase delay introduced by the variation in element thickness causes the controlled redirection of the 10 light emerging from the back surface of the optical element 1358. The surface o~ the element 1358 is therefore c~racterized by a custom phase profile r7~rtatrr7 by the desired output optical pattern, which, in this ~ - ~i , is a pattern of evenly spaced continuous 15 parallel bands of light.
The de~ired phase profile can be tr;7nRl-7t~7. i~to a pattern of thickness steps fabricated on the surface ~of the element 1358. The thickness steps dictated by the desired phase profile are formed by a series of 20 photolithography and micrnf-7hr;r~t;on process steps. For example, the element 1358 is first coated with a photoresist which is then masked, exposed and developed to produce a pattern on the element for the iirst layer of etching. The element 1358 is then etched by reactive ion 25 etching or other controllable etching process to remove material as desired for the layer. The next layer of steps is produced by again coating the element with photoresist and masking, expo3ing and developing the ~
photoresist. The subser~uent etching step produces the 3 0 second layer of steps in the phase prof ile . The process rnnt;nl7f~ until the entire phase profile of the element 1358 is produced by the varying th; rkn~q~ steps in the element 1358 .
The phase profile for the binary optic element 1358 35 can be generated using a commercially available optical -~095/26110 218S PCTlUS95lû3670 design tool, such as CODE V for eYample, a commercially available software package manufactured and sold by optical Research Aq50r; ~tes of Pasadena, California. The user of the package provides inputs to CODE V in the form 5 of coordinates which def ine the conf iguration of the desired optical output, e.g., the evenly spaced parallel illumination bands . From the phase prof ile generated by the designer using CODE V, the required thickness step profile and associated masks used to fabricate the steps 10 on the element 1358 are generated.
In another ' ~ , the process described above is used to produce a mold which can then be used to produce the binary optic element 1358 in large r~,uantities. The above steps are performed c.; a mold material to form a 15 master. The master is then ~sed to stamp a moldable optical material such as plastic into the optical element 1358 having the desired phase profile.
FIG. 20 is a Arh' t;C elevational view of pixel rows in a LCD display 24 used to illustrate the color 20 seguencing process of the invention. The figure illustrates a single stationary position of the colored ; n~tion bandg relative to rows 24a-240 of pixels . It therefore represents one step, for example, the first step, of the color seguencing process. In the following 25 r1; qc~qqirn, row 24f of pixels will be referred to by way of example. It will be understood that the description is applicable to all rows of pixels.
In the position shown, rows 24b, 24d and 24f are ;ll~-m;n~ted with red, green and blue ill n~tirn bands, 3 0 respectively . The pixels in these rows transmit the color with which they are ; 11--~; n~t~ according to the pixel data previously loaded into the pixel rows. That is, row 24f transmits its blue contribution to the final full-color image. Pixel rows 24a, 24c and 24e are not 35 ;1lllm;n~t~ black") gince they fall between the wo gsn6ll0 ~ PCT/US95/03670 2~S~

illumination bands. These rows are presently loaded with pixel data for the next step depending upon the next color in the sequence . For example, assuming the; l l llm; n~tion bands are to be shifted down in the next step, row 24e is presently loaded with green pixel data.
In the next step, rows 24b, 24d and 24f become black and are loaded with pixel data for the next step. For example, row 24f is loaded with green pixel data. In the following step, the green band illuminates row 24f, and the green light i8 transmitted according to the loaded pixel data. In the fourth 6tep, row 24f is again black while red pixel data is loaded. The binary optic is then stepped once again to move the red illumination band onto row 24f. Red data is transmitted to complete the full-color data for the particular frame for row 24f. Finally, in the sixth step, the optic 1358 is moved down one more step such that row 24f is not illuminated. During this step, row 24f is loaded with blue pixel data for the next f rame .
2 0 In a pref erred ~ ; r ', to begin the next f rame , the binary optic 1358 is moved back in the reverse direction a distance of six pixel line heights such that the first step in the se5r~nre is repeated. Rows 24a, 24c, 24e are once again black, and row 24b is ill~m;nAt~
with red light, row 24d is ; l l n~ted with green light and row 24f is ill~ n~to~ with blue light. Xence, in this: ~ , the color sequencing process is a periodic six-step process in which six~stepper pulses are applied to the stepper actuator 1372 (FIG. 1) to produce a single complete full-color frame.~ To ensure a full-color frame rate of 60 Hz, for example, the stepper pulse freSEuency is 360 Hz.
It will be seen from FIG. 2 that for a given number of pixel rows in a display, half as many illl ;n;~tirn 35 bands are required, one-third of which are ~1P~ t~d to ~'095/26110 t8S72~Q r~l~v~ -~70 each single color. That is, in a display having 480 pixel rows, a total of 240 spaced illllmin~t;rn bands are required, 80 of each color. The binary optic element 1358 is fabricated to produce the required quantity and pattern 5 of illllm; n~t~d lines .
In another ' ~; t, the binary optic is configured to produce multiple rows of equal intensity colored spots instead of the multiple continuous; 11 llrn; nAtion bands of the ~ ~1;r ' de9cribed above. In this ~ ' _';l t, the 10 binary optic produces a two-~ nAl rectangular array of spots in corr~prn~lpnre with the two-dimensional array of pixels in the LCD. That is, each single-colored ;lll--;nRt;on band of the embodiment described above is replaced with a row of ~separate equal-intensity spots of 15 the single color. The -spotg are evenly gpaced to rr; nr;
with pixels along pixel rows in the LCD 1362. This embodiment results in less light from the sources being lost and is therefore more optically efficie~lt. Optical efficiency is further improved by shaping the LCD pixels 20 such that as much as possible of each spot of light impinges on LCD pixels.
The foregoing description refers to seq-l~nt;Ally illuminating rows of pixels with horizontal bands or spots of colored light. It will be understood that the 25 invention can also be implemented by s~ nti~lly illuminating columns of pixels with vertical bands of colored light. The binary optic element 20 can be made to produce the vertical i l l llm; nAt; ^n bands, and the process described above of stepping vertically through rows of 30 pixels can be altered to step hor;~nt~lly across vertical columns of pixels.
FIG. 21 is a srh--~t;c diagram of a head-mounted : ' - '; - t 1301 of the full-color display of the invention using a diffractive or binary optic element 1314 to 35 perform the color sequencing operation. The system 1301 wo ssn6ll0 - PCT/US95/03670 includes an eyepiece 1302 and a control and drive circuit module 130~ coupled together by conductive leads The functional operation of the embodiment 1301 shown in FIG.
3 is essentially the same as that for the embodiment 1300 shown in FIG. 1, except that it i8 adapted to be implemented in a head-mounted environment. In the pmh~tl; t of FIG. 3, as in the previous ~ ' ~rl; r- t, three individual ~ED 60urces 1306, 1308 and 1310 provide the illumination for the three separate colors red, green and blue. The parabolic mirror 1312 directs the illumination light onto the diffraction or binary optic element 1314 which produce6 the multiple parallel bands of monochromatic light. As in the previous embodiment, a stepper actuator 1322, operating via step pulses under the control of the stepper controller 1324, causes the binary optic element 1314 to move as described above to produce the s~ npnt;r~l color ;ll~lmln~t;nn as flP~r;hP~ above. The light passes through the LCD 1316 which receives control and data from the LCD controller 1326 and then reflects from fold mirror 1318 through the eyepiece lens 1320 where the full-color image can be viewed. The stepper cQntrol circuitry and the I,CD control circuitry are mounted on the f rame of the head mounted system as described in greater detail below.
Color s~ pnti~l systems in accordance with the invention are well suited for use in head mounted displays due to their compact and light weight structure. They provide a Sisn; f; ~nt ; _ ~v~ ' over existing head-mounted systems as the resolution provided by a color 3 0 se~uential system is substantively higher than the resolution of color filter based li~uid crystal displays~
presently in use. When combined with the compact structure of the transferred silicon active matrix display which provides a high resolution display having a diameter 218S72 ~999N3G711 of less than 1 inch as well as integrated high speed driver circuitry described herein.
FIG. 22 i5 a perspective view of an optics module sub-a~sembly 1410 with portions of the housing broken 5 away. Two of these modules 1410 are mounted to a triangulated rail system 1480 having rods 1482a, 1482b, 1482c and comprise an optics assembly. Each optics module 1410 consists of the following: A display 1420; a backlight and color sequential system 1490; a lens 1430; a 10 mirror 1432; an optic housing 1412a; a focus adjust slide 1403; an IPD adjust/cover 1406; and a rail slide 1488.
The backlight system can be two or three LEDS, or alternatively two or three miniature fluorescent lamps to provide two or three p-imary colors respectively.
FIG. 23 is a bac~ side view of two modules 1410, 1410' mounted on a rail system 1480. As shown the two modules 1410, 1410' are mounted on rail system 1480. In addition to the triangulated rods 1482a, 1482b, 1482c, the rail system 1480 ;n~ lrloq rod and supports 1484. The rods 20 1482 are supported by a central triangulated support member 1486. Also illustrated are a backlight cable 1492 and a display cable 1485. Each display cable 1485 is fixed to the rail slide 1488 by an adhegive or r- ~h:qn; r~l contact 1494. The display cable 1485 includes a cable 25 travel bend 1483, where the display cable 1485 folds and unfolds to permit adjustments to the IPD 1407.
FIG. 2~ is a side cross sectional view of the optics module housing 1412 which is mounted on rails 1482a, 1482b, and 1482c. The optical 6ystem include~ lens 1430, 30 mirror 1432, the color sequential generator 1490 and display 1420. Generator 1490 can be any of the compact color sequential systems described herein including, for example, the ~ of Figure 9 or Figure 10, or that depicted in Figure 21 or Figure 32. Focus can be a~ hod with a 81iding ramp system, shown in FIG. 25 wos~/26llo ~ PCTNSgS/03670 which i8 incorporated into the focus adjust slide 1403 and the generator housing 1491. Tabæ 1443 protruding from the generator housing are engaged in slots 1445 incorporated in the focus slide_l403. As the focus slide button 1407 5 i5 moved horizontally, the backlight housing (along with the attached display) move vertically. Multiple tabs 1443 ensure positive alignment throughout the motion range.
The button 1403a serves as the top of the assembly capturing the top on the focus slide.
FIG. 26 show~ the display placed at the focal length of the lens 1430, thus producing an image of the dis~lay at an apparent distance of inf inity to the viewer .
Generator and display module 1420 can include any of the compact color se,rluential systems described herein. The 15 lens has a small focal length, preferable about 1 inch and can be moved aæ indicted at 1437 to provide a manual focus adjust. The flat optical element is present to correct for lateral color separation in the lens. This element consists of a diffractive optic 1434 designed to 20 compensate for the lateral color. The mirror serves to fold the optical path to minimize the depth of the head mounted device while ~tF~n~l;nr,~its height. The mirror is optional to ~he system and is present for desired form factor. Two such modules make up a h;nr~r~ r head mounted 25 display system: one $or each eye. The distance that the displays appear to the viewer can be adjusted for personal comfort, ronP~lly between 15 feet and infinity. The lens 1430 can slide forward and backward 1437 using frame assembly 1435. The magnification of the system is about 30 10. ~
Other lens systems can be used and are available from Kaiser Electro-opticg, Inc. of ~Carl8bad, r~l;fnrn;~ Such a system is descrihed in U.S. Patent No. 4,859,031 (issued August 22, 1989), the t~rh;nrJ~ of which are incorporated 35 herein by reference. Such a system 1500 is shown in FIG.
.

og5/26110 8S7.~,~ PCT/USg~;/03670 :, 27. The display system 1500 includes an active matrix display 1502, a polarizing filter 1504, a semi-reflective concave mirror 1506, and a cholesteric lir~uid crystal element 1508. The image that i8 generated by the display 5 1502 is transmitted through the filter 1504, the semi-reflective concave mirror 1506, to the element 1508. The element 1508 reflects the image back onto mirror 1506 which rotates the light 80 that, upon reflection back to element 1508, it is transmitted through element 1508 to 10 the viewer' 8 eye 1509 . A lens can be used with this system rlPrPn~l;nrj upon the size, resolution, and distance to the viewer~ s eye of the optical system components and the particular application. A color sequential generator 1505 can lnclude the backlight system and any of the 15 compact color 5Pr~ Ont;~l systems described herein.
FIG. 28 is a perspective view of a preferred head-mounted computer 1510. As illustrated, there is a head band 1512, stereo h~Arhnn~q 1603a, 1603b, a display arm 1516 connecting the hP~lh~n~ 1512 to a display pod 1100, 20 which ln~ s a display panel and color s~qu~n~
generator as described herein. The CPU and video drive circuitry are fabricated as an integral part of the head band 1512. Shown on the head band 1512 are plurality of ports 1557 which accept ~ r~nq; nn modules . As shown, 25 there is a Personal Computer Memory Card Tnt~rn;~tion~l Association (PCMCIA) ; nt.~r~re module 1554 coupled to the head band 1512. A PCMIA card 1558 is inserted into the PCMCIA interface module 1554. Also illustrated are .~rrF,nR; rn modules 1514, such as an infrared communication 30 sensor 1555a and a Charge Coupled Device (CCD) camera 1555b .
FIG. 29A is a partial exploded perspective view of another head-mounted computer 1511 in accordance with the present invention. The head band 1515 ; n(~ q a CPU, a 35 disk drive 1564 and expansion modules 1525a, 1525b, 1525c _ _ _ _ _ . , .. , . . .... . _ .. . _ . _ . . .. _ _ _ _ WO95/26110 PCT~595/03670 ~,~S~ ~

all interrnnn~r~ together by a flexible bus 1563. ~ach module 1564, 1525a, 1525b, 1525c connects to the bus 1563 by a respective rnnnf~ctn~ 1517a.
Also shown in FIG. 29A are earphones 1603a, 1603b for 5 providing audio information to the wearer. Attached to one of the earphones is a microphone arm 1690 having a microphone 1559 at its distal end. The earphones 1603a, 1603b are hinged to the head band 1515 to provide a comfortable fit for the wearer.
1~ frame assembly 1600 is coupled to each ena of the head band 1515 by a respective pin 1602a, 1602b. The pi~ls 1602a, 1602b allow the frame assembly 1600 to be rotated up and over the head band 1515. In that position, the =
head-mounted computer 1511 is compactly stored and easy to 15 carry.
The frame assembly 1600 ;nrl~ a pair of distal arms 1610a, 1610b which are coupled to the head band 1512 by the pins 1602a, 1602b. A horizontal support 1630 telescopes out from the proximal arms 1610a, 1610b and 20 around the forehead o the wearer. At least one display pod 1100 is mounted to the horizontal support 1630. As illustrated, a single display pod 1100 provides for monocular display. The display pod llOO is preferably slidable along the horizontal frame 1630 for use with 25 either the lef t or right eye of the wearer . The display pod 1100 includes an eye cup 1102.
FIG. 29B is a side elevation of the head-mounted computer 1511 o~ FIG. 29A.
FIG. 29C is a perspective view of the head-mounted 3 0 computer 1511 of FIG . 29A with the frame assembly pivoted .
The head-mounted computer 1511 can be worn in this position by a person or it can be stored or carried in this position.
FIG. 29D is a perspective view of the head-mounted 35 computer 1511 of FIG. 29A worn by a wearer. The display -~S/2611~ S7~ ~ .,,s~670 pod 1100 i8 positioned for viewing before either eye and the microphone 1559 i5 positioned to receive voice signals .
~IG. 30 is a fllnrti~n~l block diagram of a preferred head-mounted computer architecture according to the invention. The head-mounted computer 1710 ; n~ P~ a CPU
1712 having read and write access over the bus to a local data storage device 1714, which can be a floppy disk, a hard disk, a CD-ROM or other suitable mass storage devices. The CPU 1712 also drives a display driver 1716 to form images on t~e display panel 1700 for viewing by the wearer.
Either the head or body mounted platforms can house a memory modem or other expansion card 1741 conforming to the PCMCIA standards. Thes~ cards are restricted to fit within a rectangular space of about 55mm in width, 85mm in length, and 5mm in depth.
A servo 1760 communicates with the CPU 1712 to vary the position of the display panel 1700 relative to the wearer~ 8 eyes. The servo 1760 is controlled by the wearer through an irput device 1718. The servo 1760 operates a motor 1518 to raise or lower the vertical position of the display panel 1700. Thus the display panel 1700 can be positioned 80 the wearer can glance up or down at the image without the display panel 1700 interferir,g with normal vision. Additionally, the display panel 1700 can be stowed outside the field of view. The CPU or display driver can be used to control color sequential sy~tem operation .
The CPU 1712 also sends and receives data from a communication module 1720 for interfacing with the outside world. Preferably, the communication module 1720 includes a wireless transducer for transmitting and receiving digital audio, video and data signals. A communication module 1720 can also include a cellular tPl PrhnnF-Wo95126110 ~8~ PCTIUS95103670 , ~ .

cnnn~ct;on. The communication module 1720 can likewise interface directly with the Plain Old T~1 P~hnn,- Service (POTS) for normal voice, facsimile or modem communications. The communication module 1720 can include a tuner to receive over-the-air radio and television broadcasts .
The CPU 1712 can also receive and process data from an external sensor module 1730. The external sensor module 1730 receives data signals from sensors 1735, which lo provide data representing the external environment around the wearer. Such sensors are particularly important where the wearer is encased in protective gear.
When the wearer is clothed in protective gear, an ;ntPrnAl 8engor module :1740 can receive sensor data from sensors 1745 within the protective gear. The data from the ;ntorn:~l sensors 1745 provide information regarding the wearer~ 8 local environment . :In particular, the ;n~rnz~l 8engorg 1745 can warn the wearer of a breach or failure of the protective gear.
In addition, the CPU 1712 can also receiYe data from a life sign module 1750. The life sign module 1750 receives data from probes 1755 implanted in or attached to the wearer. The life sign data from the probes 1755 provides the CPU 1712 with information regarding the wearer~ 8 bodily condition 80 that corrective actions can be taken.
The sensor modules 1730, 1740, 1750 receive data from associated detectors and format the data for transmission over the bus 1513 to the CPU 1712. The sensor modules can also filter or otherwise preprocess the data before transmitting the ~ ucessed data to the CPU 1712. Thus, each f~nq; nn module can contain a microprocessor.
The wearer can control the operation of the CPU 1712 through the input device 1718. The input device 1718 can include a keyboard, a mouse, a joystick, a pen, a track .
, . .. _ _ _.. _ . _ .... , _ _ .:.. _. .. ,. .. :~ ,, ,,: .

095/26110 PCTIUS9~103670 ~ 218S7~

ball, a microphone for voice activated commands, a virtual reality data glove, an eyetracker, or other suitable input devices. A preferred eyetracker is described in U.S.
Patent No. 5,331,149 (issued July 19, 1994), the tp~rh;n~
5 of which are incorporated herein by reference. In a particular preferred P ~ of the invention, the input device 1718 is a portable collapsible keyboard.
Alternatively, the input device 1718 i3 a wrist-mounted keypad .
As illustrated, the head-mounted computer 1710 i9 a node on a distributed computing network. The head-mounted computer 1710 i9 in communication with a distributed command computer 1770 via the ;~-A~i~)n module 1720.
The distributed command computer 1770 has access to 15 distributed data storage 1775 for providing audio, video and data signals to the head-mounted computer. The distributed command computer 1770 can also be in communication with a central operations computer 1780 having central data storage 1785. Such external networks 20 can be particularly adapted to applications of the head-mounted display or may be general purpose distributed data n~t~ JL k ~
FIG. 31 shows a detailed perspective view of a preferred ' '; t of a -clllAr head mounted display.
25 The display pod 1900 includes an eyecup 1902 that is fabricated from a pliable material. The pod can be turned by a wearer to adjust the vertical position of the display pod 1900 in the wearer's field of view. The wearer can also adjust the distance of the display pod 1900 from the 30 wearer's eye, can swivel the pod relative to the visor at pivoting r onnPctor 1920, or can tilt the pod up by the - wearer out of the field of view. The visor 1930 can also house the video interface circuitry including the color ~PqllPn~;Al drive circuitry, as well as the circuit harness 35 for the display which can be connected either through the _ _ _ ~, . .. . _ . _ , ., .. , , . . . _ _ _ _ _ _ _ _ .

wo ss/26l 10 P~ 670 Ct.~

arm 1932 suspending the pod at hinge 1938 or through optional cable 1934. A microphone 1940 can be connected to visor 1935 or to audio unit 1942 by connector 1330 and input cable (not shown) can be connected on the oppo3ite 5 side.
The display pod can be positioned against a user' 8 glasses, or against the eye, or retracted above the eye, or pressed against the visor.
The display pod 1950 can include several different 10 color se~uential optical systems. FIG. 32 illustrates another preferred: ' ~;r ' l't; l; 7;nrJ three different color lamps 1952, 1954, 1956 a reflector 1958, a diffuser 1960, and active matrix liquid crystal display 1955 and lens 1962.
The active matrix and liquid crystal displays f;~hr;r;lted and usea in conjunction with the color sequential systems described herein can be made using a transf erred silicon process .
Fir,ure 33 illustrates a partial cross-sectional view 20 of a transferred silicon active matrix liquid crystal display which 1968 includes a transistor formed with a thin f ilm single crystal silicon layer 1970 over an insulating substrate 1974. The areas or regions of the circuit in which pixel electrodes 1972 are formed with 25 silicon or can be formed by subjecting the area to a silicon etch to expose the underlying oxide followed by deposition of the transparent r~nril1rt;ve pixel electrode 1972 on or over the exposed oxide with a portion of the deposited electrode l~t~n~;nr up the transistor ~
30 to the contact t~l;7~tirn of the transistor sidewall to the contact metali2:ation of the transistor. A passivation layer 1972 is then formed over the entire device, which is then transferred to a optically tr~n~r~r~nt substrate 1978. A transparent adhesive 1977 is used to secure the 35 circuit to the substrate 1978. The composite structure ~'095/26110 PCT/US9~/03670 1975 i3 then attached to a counterelectrode 1973 and polarization elements (not shown) and a liquid crystal material 1979 is then inserted into the cavity formed between the oxide layer 1974 and the counterelectrode 5 1973.
A further i ' ~; ' 1980 of the display is fabricated in a manner similar to that described in Figure 33, but which employs a different pixel electrode and insulator structure i8 shown in Figure 34. This involves 10 exposing a portion of the single crystal 9ilicon layer in which the transistor circuit i8 formed by removing the exposed portion through openings 1984 in the insulator 1974 after transfer ~substrate 1978 and adhesive 1977 not shown) to forme the structure shown in Figure 34. The 15 conductive transparent electrode 1982 is formed as _hown that can directly contact the transistor circuit at a contact area or the exposed silicon can be treated prior to contact formation as described previously. A further optional passivation layer (not shown) can also be added 20 to cover the pixel electrode 1982 to provide electrical isolation, and planarization of the pixel area. The circuit can then be packaged with the liquid crystal material to form the display. The circuits can also be used to form a active matrix electrolllm;n~q~ ~n~ displays 25 as described in U.S. Serial No. 07/943,896, filed on September ll, 1992, the contents of which are incorporated herein by reference. Instead of color filters, however, a color sequential system such as that described in connection with Figure 9 and Figure 10 herein can be 30 mounted onto the circuit and driven by the n~ aqi~ry control circuit for color sequential operation.

Wo 95/26110 rCr~SsS/03670 Eauivalents Those skilled in the art will know, or be able to ascertain using no more than routine experimentation, many equivalents to the specif ic embot~; R of the invention described herein. These and all other equivalents are intended to be f~nt , ~R5t~tl by the following claims.

Claims (20)

-53-The invention claimed is:

1. A color display apparatus comprising:
an array of pixel transistors formed from a single silicon material (1970);
an array of pixel electrodes (1972) conductively connected to the array of pixel transistors to form an active matrix region (90);
a drive circuit (46) formed from the single crystal silicon material (1970) and conductively connected to the array of pixel transistors to generate active matrix drive signals for actuating the pixel transistors to form an image;
a color generator (220) optically disposed between a light source (200) that generates light (205) and the active matrix region (90), the color generator separating the light (205) from the light source (200) into primary colors (211, 212, 213) that illuminate the array of pixel electrodes (1972), each pixel electrode (1972) illuminated by a selected primary color (211, 212, 213) at a selected time.

2. The apparatus of Claim 1 further comprising:
a video source (2) for providing video information; and a sequential color driver (407) responsive to the video information and in response thereto actuating the color generator (220) to sequentially illuminate each pixel electrode (1972) with the primary colors (211, 212, 213) so a viewer perceives a color image from the active matrix region (90) over time.

3. The apparatus of Claim 1 wherein the color generator (220) is an electronically switched color filter (430).

4. The apparatus of Claim 1 wherein the drive circuit (46) includes a dual line driver (46a, 46b) for activating each line (R) of the active matrix region (90) with two signals, each signal applied to a respective end of the line (R).

5. The apparatus of Claim 1 wherein each primary color (211, 212, 213) is directed onto each pixel electrode (1972) in temporal sequence.

6. The apparatus of Claim 1 further comprising a viewing lens (1430) for direct viewing of the formed image by the viewer.

7. The apparatus of Claim 6 further comprising a housing (1410) for mounting the active matrix region (90) proximate to an eye of the viewer, the active matrix region having at least 480 pixel electrodes along a first direction and at least 640 pixel electrodes along a second direction.

8. The apparatus of Claim 7 wherein the houaing (1410) further includes the light source (200).

9. The apparatus of Claim 1 further comprising a projection lens (1320) for projecting the formed image onto a viewing surface.

10. A head mounted color display apparatus comprising:
an array of pixel transistors formed from a single silicon material (1970); and an array of pixel electrodes (1972) conductively connected to the array of pixel transistors to form an active matrix region (90);
a drive circuit (46) formed from the single crystal silicon material (1970) and conductively connected to the array of pixel transistors to generate active matrix drive signals for actuating the pixel transistors to form an image;
a color generator (220) optically disposed between a light source (200) generating light (205) and the active matrix region (90) for separating the light (205) from the light source (200) into primary colors (211, 212, 213) that illuminate the array of pixel electrodes (1972), each pixel electrode (1972) illuminated by a selected primary color (211, 212, 213) at a selected time; and a frame (1512) for mounting the active matrix region (90) and the color generator (220) on a user's head.

11. The apparatus of Claim 10 further comprising:
a video source (2) for providing video information; and a sequential color driver (407) responsive to the video information and in response thereto actuating the color generator (220) to sequentially illuminate each pixel electrode (1972) with the primary colors (211, 212, 213) so a viewer perceives a color image from the active matrix region (90) over time.

12. The apparatus of Claim 10 wherein the color generator (220) is an electronically switched color filter (430).

13. The apparatus of Claim 10 wherein the drive circuit (46) includes a dual line driver (46a, 46b) for activating each line (R) of the active matrix region (90) with two signals, each signal applied to a respective end of the line (R).

14. A method of displaying a color image to a viewer, comprising the steps of:
forming an array of pixel transistors from a single crystal silicon material (1970);
forming an active matrix region (90) by conductively coupling an array of pixel electrodes (1972) to the array of pixel transistors;
forming a drive circuit (46) from the single crystal silicon material (1970);
conductively coupling the array of transistors to the drive circuit (46) to generate active matrix drive signals for actuating the pixel transistors to form an image;
providing light (205) having a plurality of colors (211, 212, 213) from a light source (200);
providing a color generator (220) in the optical path between the light source (200) and a viewer;
directing the plurality of colors (211, 212, 213) through the active matrix region (90) with the color generator (220) such that each pixel electrode (1972) is illuminated by a selected color at a selected time;
and displaying a partial image to the viewer on the active matrix region (90) in sequence to provide a color image.

15. The method of Claim 14 wherein the step of generating colors (211, 212, 213) includes generating color stripes (91, 92, 93).

16. The method of Claim 15 wherein the displaying step comprises illuminating at least one row (R) of the active matrix region (90) with one selected color at the selected time.

17. The method of Claim 14 wherein the step of generating colors (211, 212, 213) includes generating color blocks (91, 92, 93).

18. The method of Claim 17 wherein each block registers to at least one pixel electrode (1972) of the display panel.

19. The method of Claim 14 wherein the step of generating colors includes generating colors from the group comprising red, green, blue and black.

20. The method of Claim 14 wherein the step of displaying further comprises electronically switching a color filter (430).