CA1191942A - Solid state image pick-up devices - Google Patents
Solid state image pick-up devicesInfo
- Publication number
- CA1191942A CA1191942A CA000433615A CA433615A CA1191942A CA 1191942 A CA1191942 A CA 1191942A CA 000433615 A CA000433615 A CA 000433615A CA 433615 A CA433615 A CA 433615A CA 1191942 A CA1191942 A CA 1191942A
- Authority
- CA
- Canada
- Prior art keywords
- photo
- elements
- shutter
- sensitive elements
- shift registers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000007787 solid Substances 0.000 title claims abstract description 16
- 238000012546 transfer Methods 0.000 claims abstract description 17
- 239000011159 matrix material Substances 0.000 claims abstract description 4
- 230000003287 optical effect Effects 0.000 claims abstract description 3
- 230000000694 effects Effects 0.000 description 4
- 230000001360 synchronised effect Effects 0.000 description 4
- 238000012937 correction Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 244000187656 Eucalyptus cornuta Species 0.000 description 1
- 101150087426 Gnal gene Proteins 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000002146 bilateral effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
- H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
- H04N3/14—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by means of electrically scanned solid-state devices
- H04N3/15—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by means of electrically scanned solid-state devices for picture signal generation
- H04N3/155—Control of the image-sensor operation, e.g. image processing within the image-sensor
- H04N3/1568—Control of the image-sensor operation, e.g. image processing within the image-sensor for disturbance correction or prevention within the image-sensor, e.g. biasing, blooming, smearing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
- H04N25/62—Detection or reduction of noise due to excess charges produced by the exposure, e.g. smear, blooming, ghost image, crosstalk or leakage between pixels
- H04N25/625—Detection or reduction of noise due to excess charges produced by the exposure, e.g. smear, blooming, ghost image, crosstalk or leakage between pixels for the control of smear
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S358/00—Facsimile and static presentation processing
- Y10S358/906—Hand-held camera with recorder in a single unit
Abstract
ABSTRACT OF THE DISCLOSURE
A solid state image pick-up device comprises a matrix of first and second photo-sensitive elements, vertical shift registers disposed parallel to each other to shift charges from the first and second elements, respective transfer gates between each first and second element and the adjacent vertical shift register, and a horizontal shift register connected to one end of each of the vertical shift registers. An optical shutter is controlled such that the first find second elements are simultaneously exposed to incident light, and a system controller ccntrols the trasnfer gates and the vertical and horizontal shift registers whereby equal predetermined maximum intervals are available for charging each of the first and second elements, the predetermined intervals being at least two frame periods long, but the starting time for charging for the first and second elements being relatively shifted by a predetermined interval, and reading of the signals from the first and second elements being performed sequentially in a frame period subsequent to closure of the shutter.
A solid state image pick-up device comprises a matrix of first and second photo-sensitive elements, vertical shift registers disposed parallel to each other to shift charges from the first and second elements, respective transfer gates between each first and second element and the adjacent vertical shift register, and a horizontal shift register connected to one end of each of the vertical shift registers. An optical shutter is controlled such that the first find second elements are simultaneously exposed to incident light, and a system controller ccntrols the trasnfer gates and the vertical and horizontal shift registers whereby equal predetermined maximum intervals are available for charging each of the first and second elements, the predetermined intervals being at least two frame periods long, but the starting time for charging for the first and second elements being relatively shifted by a predetermined interval, and reading of the signals from the first and second elements being performed sequentially in a frame period subsequent to closure of the shutter.
Description
BACK~.ROUND OF THE INVENTION
-Field of thelnvention This invention relates to solid state image pick-up devices, and is particularly concerned with a video camera induding a solid state image sensor for deriving a still image video signal.
Description of the Prior Art It is known to provide a solid state ima~e pick-up device including a solid state image sensor such as a charged coupled device (CCD), which can derive an output video signal during one -Field period or one frame period, so 10 as to Form one complete still image video signal.
If the CCD is oF the so-called interline transfer type, the picked-up charge signals due to the irradiation of the incident light on photo-sensitive elements of the CCD are transferred to vertical shift registers continuously during each field or frame period. However, in this type of CCD, a so-15 called smearing effect or smearing noise can occur because some unwanted charges which are not picked-up or captured in the photo-sensitive regions leak out to the regions of the vertical shift registers. Such smearing is particularly likely to occur when incident light having a long wavelength, such as red light, is irradiated onto the CCD. The ef fect is to cause a 20 blurred image when the signal is reproduced on a television receiver.
Moreover, dark-current noise can also occur, this being due to thermal excitation oF electrons in the silicon substrate of the CCDD The extent of the thermal excitation depends on the thermal condition of the substrate and occurs even if the phot~sensitive regions are shielded from 25 incident lil~ht by a shutter.
If the amounts of the dark-current charges ~ccumulated in difFerent photo-sensitive reyions differ in successive fields, that is in successive odd and even -field periods, then the output levels of the picked-up video signals, which are made up of the combination of the chsrges due to the incident ~0 light and the dark-current charyes, will also differ. The dark-current has the effect o~ adding a clirect current component to each video signal. In consequence, if the dark currents are different in odd and even field periods, the overall levels o-F the video signQls will be different and this will cause flicker on a television receiver when the video signals are reproduced. This flicker will hereinafter be called flicker of the First kind.
Attempts have been made in the past to overcome both smearing and dark-current effects, but these have resl~ted in solid-state ima~e sensors which are extremely complicated in structure and e~pensive to make because of the highly advanced techniques which are used in manufscturing 10 th em .
In the case of a video camera which is to produce a still image video signal for reproduction on a television receiver, the output video signal must be in the general form of a standard television sicJnal such as an NTSC, PAL
or SECAM signal. Thus the output video signal of such a video camera 15 should comprise a frame signal consisting of two field signals which are raster interleaved with each other in the usual way.
The need to have two field signals which are derived sequentially introduces Q further problem of -flicker when picking up an image of a moving object. This is because of the movement between the times of the 20 two fields, which has the result that the video signals oF the individual fields are spatially different from one another. This leads in particular to substantial deterioration in the vertical resolution Df the reproduced picture. Hereinafter this will be called flicker of the second kind.
Thus flicker of the first kind causes luminance variations in the 25 reproduced picture on a television receiver and flicker of the second kind causes spatially displaced images on the television receiver. Moreover, the smearin9 results in colour blurring and this is spatially non--niform.
SUMMARY OF THE INVENTION
____ One object of the present invention is to provide a solid state image 30 pick-up device which is capable of forming a still im~ge video signal without flicker or dark-current noise.
Another object of the present invention is to provide a solid state image pick-up device in the form oF a video camera to produce a still image video signalJ and which prevents deterioration of the image quality resulting 5 f rom sm earing.
Yet another object of the present invention is to provide a solid state image pick-up device in the form ol a camera having a shutter whereby the exposure time of the solid sl:ate image sensor can be controlled to effect still image pick-up.
According to the present invention there is provided a solid st~te image pick-up device comprising:
first and second photo-sensitive elements corresponding to odd and even fields of a television signal arranged al~ernately in a matrix;
a plurality of vertical shift registers mounted parallel to each other for 15 shifting charges from said first and second photo-sensitive elements;
a plurality of transfer gates respectively disposed between said first and second elements and said vertical shift registers for shifting charges from said first and second photo-sensitive elements to said vertical shift re gi sters;
20 a horizontal shift register coupled to one end oF each of said vertical shift re gi sters;
an optical shutter for controlling the irradiation of light on said first and second elements;
means for controlling said shutter to open so that said first and second 25 elements are exposed simultaneously to said light; and controller means For controlliny said transfer gates and said vertical and hori~ontal shift registers such that the maximum intervals available for charging each of said first and second photo-sensitive elements are the sarne and have a duration of at least two frame periods, the start times of said 30 charging intervals for said first and 3econd photo-sensitive elements respectively are relatively shifted by a predeterrmined interval, and the charges from said first and second photo-sensitive elements respectiYely res~ting from said irradiation are read out sequentially after said shutter has closed.
Accordingly, in embodiments of the invention, the output video signals for each field and resulting from the picture scene and unavoidable dark-current components~ are picked up sequen~i ally from the image sensor device in such a way that the charges due to the dark currents are adjusted to be the same in each of the fields, so as to eliminate flicker of the first 10 kind. Moreover, the spatial variation between the odd and even ~ields which gives rise to flicker of the second kind is eliminated, although the signals d~
of course differ to give the proper interline relationship.
Preferably~ said output video signals are read out subsequent to clearing undesired residual electrons from the vertical shift registers, so 15 that smesring can also be avoided.
The above, and other objects, features and advantages of this invention will be apparent from the following detailed description of illustrative embodiments which is to be read in conjunction with the accrrnpanying drawings.
__ _ Figure 1 is a schematic diagrsrn of the general arrangement and circuit configuration of a video camera;
Figure 2 is fl plan view of a solid state image sensor used in the camera of Figure 1; and Figures 3A to 3H are time charts used in explaining the operation of the camera of Figure 1.
.
Referring toFigure 1, the camera comprises a charge coupled device (CCD) 1 of the interline transfer type, from which a still image video signal 30 i8 obtained as will be described in detail below. A Yideo signal recording and reproducing section 3 records the picked-up video signal on a rotary rnagnetic disc 2 formecl of sheet material and the video signal can be reproduced from the ma~netic disc 2 so as to produce a still image on a television reoeiver (not shown). A system controiler 23 controls the operation of the camera, including the CCD 1.
As shown in Figure 2, the CCD 1 comprises first and second photo-sensitive elements S0 and SE alternately arranged in a matrix. The photo-sensitive elements S0 correspond to odd fields and the photo-sensitive elements SE correspond to even fields9 so the photo-sensitive elements S0 10 are aligned horizontally and the photo-sensitive elements SE are aligned horizontally. The CCD 1 also comprises a plurality of bilateral vertical shift registers 4 which are disposed in vertical spaces between adjacent photo-sensitive elements S0 and SE. Respective transFer gates 4a and 4b are disposed between the phot~sensitive elements S0 and SE and the 15 adjacent vertical shift register 4, to shift charges thereto. The CCD 1 also indudes a horizontal output shift register 5 coupled to one end of each of the vertical shift registers 4.
The operation of the CCD 1 will be explained with reference also to Figure 1 and the time charts in Figure 3. The maximum intervals available 20 for charging the first and second photo-sensitive elements S0 and SE are set to have the same length, and the period may for example be two frame periods. The amount of chflrge in the sensor regions at the end of a charging interval depends on the intensity of the incident light, and is proportional to the amount of light irradiated on the sensor regions in the two frame period.
25 The charges in the first and second photo-sensitive elements S0 and SE are shifted to the vertical transfer registers 4 through the transfer gates 4a and 4b respectively. The solid line and dotted line arrows in Figure 2 indicate respectively the flow of electrons from the sensor regions during the odd and e ven fi eld transfers respecti vely.
3û The gating operation of t:he transfer gates 4a and 4b is controlled by 3'~
gate 3ignals ~15 generated by a gAte signal generator 6. After this gating and transferriny operation, the charges in the vertical shi~t register 4 are shiFted successively line by line to the horizontal shift register 5 under control of a signal ~v generated by a vertical drive signsl generator 7b. The 5 charges in the horizontal output shift register 5 are then read out as the output video signal under control of a signal ~h generated by a horizontal drive signal generator 7a. These driving operations of the shift rec~isters 4 and 5 are carried out in synchronisrn with the vertical synchroni~ing signals oF a standard television signal such as an NTSC, PAL or SECAM systern 10 signal, which vertical synchronizing signals form a reFerence signal. Figure 3A shows this reference signal, the cycle of which is egual to one frame period .
Th~ gate gignals ~5 generated by a gate signal generator 6 comprise two pulse trains generated alternately field by field for supply to the 15 transfer gates 4a and 4b in the odd and even fields respectively of each frame. For the first photo-sensitive elements SO, correspondiny to the odd field, the maximum available charqing interval TSOA (Figure 3B) of two frame periods is predetermined and for the second photctsensitive elements SE, corresponding to the even fields, the maximum available charging 20 interval TSEA is of the same duration, that is to say two frame periocls, but does not start until half a frame period, that is one field period, later as shown in Figure 3C. Comparison of the time charts of Figures 3B and 3C
shows that the maximum available charging period for the first photo-sensitive elementsSO starts at time to and the maximum available charging 25 period for the second photo-sensitive elements SE starts one field periocl later at time tE.
The transfer gates 4a and 4b are periodically opened for short intervals TTO and TTE as shown in Figures 3B and 3C, and during these short intervals the charges in the photo-sensitive elements SO and SE are 30 shifted tothe verticalshiftregisters 4.
It is to be noted that the intervals TSOA and TSEA ars the theoretricE~l maxirr~um available charging ;ntervals ancl that the actual charging intervals are controlled by a shutter 9 8S shown in Figure 1. The shutter 9 is disposed together with an iris ~ in the light path to the CCI~ 1 nnd is controlled in dependence on the incident light to provide an adequate charging period for the sensor regions of the CCD 1. The operation of the shutter 9 is controlled by the system controller 23 through a shutter drive cjrcuit 10, and the iris 8 is likewise controlled by the system controller 23 by way of an iris drive circuit 11.
The iris 8 is normally kept Fully open and the shutter 9 is normally kept open, so that the incident light can pass therethroughJ so enabling the light intensity to be detected. The shutter 9 is closed and the iris 8 set to the required value under control of the system controller 23. The system controller 23 is in turn controlled by a shutter-triyger pulse p triggered by 15 closure oF a shutter switch 22. When the trigger pulse p is supplied to the system controller 23 at the time tS as shown in Figure 3D, the system controller 23 is activated so that just after the time to synchronized with the odd field reference signal (Figure 3A), this being the first frame start time following the time t~;, the control process is initiated so as to derive 2D the output two-field still video signals vn and VE within a three frame period TFS (Figures 3H and 3A~. A three frame period is necessary, due to the offset between the starting times to and tE and the time taken for read-out. The two Frame periods within which the charging of the photo-sensitive elements SO and SEcan take place are determined by inhibiting the 25 normal transfer operation of the transfer gates ~a and ~Ib until the ends of these periods.
The shutter 9 is closed at the time to which is synchronized with the first leading edge of an odd field interval after the trigger pulse p and the shutter 9 is opened to start the operative exposure at the time tE
30 synchronized with the trailing edge of the above odd Field interval. That is to say, the clcsed ir~erv~l TCL of the shutter 9 cnrresponds to the interval between the beyinning of the odd-field chQrginy time and the beginning of the even-~ield charging tirne of the photc-sensitive regions SO and SE. The shutter 9 is then closed not later th~n one field period before the end of the 5 odd field available charging interval TSOA. Thus the effective exposure time TSA is variable from substantially zero to an actual msximum of two field periods, which for a sixty field per second television system is 1/30 second. In other words, the e-ffective exposure time TSA is variable, in dependence c~n the incident light, as indicated by an arrow g inFigure 3E.
As a result of the above-described operation of the shutter 9 and the time control thereof, together with control of the iris ~, the appropriate amount of incident light is irradiated on the CCD 1, and moreover the incident light is irradisted ~n the first and second photo-sensitive elements SO and SE at the same time. Consequently, each field has the 15 identical picture signal, although the picture is deviated by one line due to the interlace relation of the television signal. ~ecause the exposure is at the same time, flicker of the first kind described above does not OCCUr.
Moreover, because the maximum availsble charging periods TSOA
and TSEA for the first and second photo-sensitive elesnents SO and SE
20 respectively are the same, each having a duration of two frame periods, then even although the incident light is not irradiated on the first and second photc~sensitive elements SO and SE For the whole of these periods, the accumulated charges due to dark-currents in each of the photo-sensitive elements SO and SE are the same, and therefore flicker of the second 25 kind described above is also eliminated. Thus, as seen inFigures 3F and 3G, the dark-current charges DO and DE accum~ate substantially linearly with respect to time during the maximum available charging periods. These dark-curlent charges DO and DE are cosnbined with the actual image signals SO and S(~ accumul~sted in the photo-sensitive elements SO and SE c~ring 30 the effective expnsure time TSA, and then the combined image signals are re~d out as the output video signals VO and VE after a certain tirne interval TSM which is selected so as to prevent noise resulting from smear. In consequence, the total amounts of charge For each field are substantially the same because:
SO ~ DO = SE ~ DE
It should be noted that the output video sisnals VO and VE are read out while the shutter 9 is closed. Moreover, the output video signals VO and 10 VE are read out at least one field period TSM after the end of the exposure eime. During this period any unwanted charges, that is to say the smear noise charges for example, stored in the vertical shift registers 4 are swept out while the transfer yates 4a and 4b are maintained closed.
The read out video signals VO and VE are s-pplied to a sampling-hold 15 circuit 13 through an amplifier 12, so that the output video signals VO and VE are sampled and smoothed. The smoothed signals are supplied through a DC-removing capacitor 14 to a clarnping circuit 15 so as to be clamped at a suitable level.
As indicated in Figure 2 the CCD 1 has a shielded portion so that st 20 least one phot~senstive element 5' in each horizontal line is shielded frorn the incident light. This enables a reference black signal for use in adjusting the output video signals VO and VE to be obtained together with the image signal. The output video signals VO and VE are clamped in the clamp circuit 15 using this reference signal, and therefore the black level of the output Z5 video signals VO and VE are maintained at a required predetermined level and the black levels do not change undesirably in dependence on the input scene or variations in the camera. The clamp output signals from the clamp circuit 15 are then supplied to a processing circuit 16 in which gamma correction, and if the input signal is a color signal, a while balhnce 30 correction are carried out.
The processed video signal is encoded into a suitable signal format for recording on the magnetic disc 2 in an encoding circuit 17 and is then supplied by way of a recording circuît 1~, which may for example be an amplifier9 to a video recording head 19 for recording on the magnetic disc 2.
If the video signal is a color video signal, the encoding circuit 17 may derive snd supply color different signals R - Y and B - Y line by line together with a luminance signal Y.
In the case of a 60 field per second television system, the magnetic disc 2 is driven at 60 revolutions per second by a motor 20 under control of a 10 motor drive circuit 21 which in turn is controlled by the system controller 23 so as to be properly synchronized with the vertical shift signal ~V from the V - drive si gnal generator 7b .
As described above the maximum period for which the shutter 9 may be opened is, in a ~0-field per second television system, one 1/30, but if this 15 interval is insufficient then longer exposure times can be made available by increasing the total processing interval TFS (Figure 3A) from three frarne periods to a longer ir7terval, such as four frame periods. In this case the read-out of the output video signal VO and VE is of course shifted so as to be one frame period later than shown in Figure 3H.
Although illustrative embodiments of the invention have been described herein with reference to the accompanying drawings, it is to be understood the invention is not limited to those precise embodiments, and thflt various changes and modifications can be effected therein by one skilled in the art without departing from the scope and spirit of the 25 invention as defined by the appended clairns.
-Field of thelnvention This invention relates to solid state image pick-up devices, and is particularly concerned with a video camera induding a solid state image sensor for deriving a still image video signal.
Description of the Prior Art It is known to provide a solid state ima~e pick-up device including a solid state image sensor such as a charged coupled device (CCD), which can derive an output video signal during one -Field period or one frame period, so 10 as to Form one complete still image video signal.
If the CCD is oF the so-called interline transfer type, the picked-up charge signals due to the irradiation of the incident light on photo-sensitive elements of the CCD are transferred to vertical shift registers continuously during each field or frame period. However, in this type of CCD, a so-15 called smearing effect or smearing noise can occur because some unwanted charges which are not picked-up or captured in the photo-sensitive regions leak out to the regions of the vertical shift registers. Such smearing is particularly likely to occur when incident light having a long wavelength, such as red light, is irradiated onto the CCD. The ef fect is to cause a 20 blurred image when the signal is reproduced on a television receiver.
Moreover, dark-current noise can also occur, this being due to thermal excitation oF electrons in the silicon substrate of the CCDD The extent of the thermal excitation depends on the thermal condition of the substrate and occurs even if the phot~sensitive regions are shielded from 25 incident lil~ht by a shutter.
If the amounts of the dark-current charges ~ccumulated in difFerent photo-sensitive reyions differ in successive fields, that is in successive odd and even -field periods, then the output levels of the picked-up video signals, which are made up of the combination of the chsrges due to the incident ~0 light and the dark-current charyes, will also differ. The dark-current has the effect o~ adding a clirect current component to each video signal. In consequence, if the dark currents are different in odd and even field periods, the overall levels o-F the video signQls will be different and this will cause flicker on a television receiver when the video signals are reproduced. This flicker will hereinafter be called flicker of the First kind.
Attempts have been made in the past to overcome both smearing and dark-current effects, but these have resl~ted in solid-state ima~e sensors which are extremely complicated in structure and e~pensive to make because of the highly advanced techniques which are used in manufscturing 10 th em .
In the case of a video camera which is to produce a still image video signal for reproduction on a television receiver, the output video signal must be in the general form of a standard television sicJnal such as an NTSC, PAL
or SECAM signal. Thus the output video signal of such a video camera 15 should comprise a frame signal consisting of two field signals which are raster interleaved with each other in the usual way.
The need to have two field signals which are derived sequentially introduces Q further problem of -flicker when picking up an image of a moving object. This is because of the movement between the times of the 20 two fields, which has the result that the video signals oF the individual fields are spatially different from one another. This leads in particular to substantial deterioration in the vertical resolution Df the reproduced picture. Hereinafter this will be called flicker of the second kind.
Thus flicker of the first kind causes luminance variations in the 25 reproduced picture on a television receiver and flicker of the second kind causes spatially displaced images on the television receiver. Moreover, the smearin9 results in colour blurring and this is spatially non--niform.
SUMMARY OF THE INVENTION
____ One object of the present invention is to provide a solid state image 30 pick-up device which is capable of forming a still im~ge video signal without flicker or dark-current noise.
Another object of the present invention is to provide a solid state image pick-up device in the form oF a video camera to produce a still image video signalJ and which prevents deterioration of the image quality resulting 5 f rom sm earing.
Yet another object of the present invention is to provide a solid state image pick-up device in the form ol a camera having a shutter whereby the exposure time of the solid sl:ate image sensor can be controlled to effect still image pick-up.
According to the present invention there is provided a solid st~te image pick-up device comprising:
first and second photo-sensitive elements corresponding to odd and even fields of a television signal arranged al~ernately in a matrix;
a plurality of vertical shift registers mounted parallel to each other for 15 shifting charges from said first and second photo-sensitive elements;
a plurality of transfer gates respectively disposed between said first and second elements and said vertical shift registers for shifting charges from said first and second photo-sensitive elements to said vertical shift re gi sters;
20 a horizontal shift register coupled to one end oF each of said vertical shift re gi sters;
an optical shutter for controlling the irradiation of light on said first and second elements;
means for controlling said shutter to open so that said first and second 25 elements are exposed simultaneously to said light; and controller means For controlliny said transfer gates and said vertical and hori~ontal shift registers such that the maximum intervals available for charging each of said first and second photo-sensitive elements are the sarne and have a duration of at least two frame periods, the start times of said 30 charging intervals for said first and 3econd photo-sensitive elements respectively are relatively shifted by a predeterrmined interval, and the charges from said first and second photo-sensitive elements respectiYely res~ting from said irradiation are read out sequentially after said shutter has closed.
Accordingly, in embodiments of the invention, the output video signals for each field and resulting from the picture scene and unavoidable dark-current components~ are picked up sequen~i ally from the image sensor device in such a way that the charges due to the dark currents are adjusted to be the same in each of the fields, so as to eliminate flicker of the first 10 kind. Moreover, the spatial variation between the odd and even ~ields which gives rise to flicker of the second kind is eliminated, although the signals d~
of course differ to give the proper interline relationship.
Preferably~ said output video signals are read out subsequent to clearing undesired residual electrons from the vertical shift registers, so 15 that smesring can also be avoided.
The above, and other objects, features and advantages of this invention will be apparent from the following detailed description of illustrative embodiments which is to be read in conjunction with the accrrnpanying drawings.
__ _ Figure 1 is a schematic diagrsrn of the general arrangement and circuit configuration of a video camera;
Figure 2 is fl plan view of a solid state image sensor used in the camera of Figure 1; and Figures 3A to 3H are time charts used in explaining the operation of the camera of Figure 1.
.
Referring toFigure 1, the camera comprises a charge coupled device (CCD) 1 of the interline transfer type, from which a still image video signal 30 i8 obtained as will be described in detail below. A Yideo signal recording and reproducing section 3 records the picked-up video signal on a rotary rnagnetic disc 2 formecl of sheet material and the video signal can be reproduced from the ma~netic disc 2 so as to produce a still image on a television reoeiver (not shown). A system controiler 23 controls the operation of the camera, including the CCD 1.
As shown in Figure 2, the CCD 1 comprises first and second photo-sensitive elements S0 and SE alternately arranged in a matrix. The photo-sensitive elements S0 correspond to odd fields and the photo-sensitive elements SE correspond to even fields9 so the photo-sensitive elements S0 10 are aligned horizontally and the photo-sensitive elements SE are aligned horizontally. The CCD 1 also comprises a plurality of bilateral vertical shift registers 4 which are disposed in vertical spaces between adjacent photo-sensitive elements S0 and SE. Respective transFer gates 4a and 4b are disposed between the phot~sensitive elements S0 and SE and the 15 adjacent vertical shift register 4, to shift charges thereto. The CCD 1 also indudes a horizontal output shift register 5 coupled to one end of each of the vertical shift registers 4.
The operation of the CCD 1 will be explained with reference also to Figure 1 and the time charts in Figure 3. The maximum intervals available 20 for charging the first and second photo-sensitive elements S0 and SE are set to have the same length, and the period may for example be two frame periods. The amount of chflrge in the sensor regions at the end of a charging interval depends on the intensity of the incident light, and is proportional to the amount of light irradiated on the sensor regions in the two frame period.
25 The charges in the first and second photo-sensitive elements S0 and SE are shifted to the vertical transfer registers 4 through the transfer gates 4a and 4b respectively. The solid line and dotted line arrows in Figure 2 indicate respectively the flow of electrons from the sensor regions during the odd and e ven fi eld transfers respecti vely.
3û The gating operation of t:he transfer gates 4a and 4b is controlled by 3'~
gate 3ignals ~15 generated by a gAte signal generator 6. After this gating and transferriny operation, the charges in the vertical shi~t register 4 are shiFted successively line by line to the horizontal shift register 5 under control of a signal ~v generated by a vertical drive signsl generator 7b. The 5 charges in the horizontal output shift register 5 are then read out as the output video signal under control of a signal ~h generated by a horizontal drive signal generator 7a. These driving operations of the shift rec~isters 4 and 5 are carried out in synchronisrn with the vertical synchroni~ing signals oF a standard television signal such as an NTSC, PAL or SECAM systern 10 signal, which vertical synchronizing signals form a reFerence signal. Figure 3A shows this reference signal, the cycle of which is egual to one frame period .
Th~ gate gignals ~5 generated by a gate signal generator 6 comprise two pulse trains generated alternately field by field for supply to the 15 transfer gates 4a and 4b in the odd and even fields respectively of each frame. For the first photo-sensitive elements SO, correspondiny to the odd field, the maximum available charqing interval TSOA (Figure 3B) of two frame periods is predetermined and for the second photctsensitive elements SE, corresponding to the even fields, the maximum available charging 20 interval TSEA is of the same duration, that is to say two frame periocls, but does not start until half a frame period, that is one field period, later as shown in Figure 3C. Comparison of the time charts of Figures 3B and 3C
shows that the maximum available charging period for the first photo-sensitive elementsSO starts at time to and the maximum available charging 25 period for the second photo-sensitive elements SE starts one field periocl later at time tE.
The transfer gates 4a and 4b are periodically opened for short intervals TTO and TTE as shown in Figures 3B and 3C, and during these short intervals the charges in the photo-sensitive elements SO and SE are 30 shifted tothe verticalshiftregisters 4.
It is to be noted that the intervals TSOA and TSEA ars the theoretricE~l maxirr~um available charging ;ntervals ancl that the actual charging intervals are controlled by a shutter 9 8S shown in Figure 1. The shutter 9 is disposed together with an iris ~ in the light path to the CCI~ 1 nnd is controlled in dependence on the incident light to provide an adequate charging period for the sensor regions of the CCD 1. The operation of the shutter 9 is controlled by the system controller 23 through a shutter drive cjrcuit 10, and the iris 8 is likewise controlled by the system controller 23 by way of an iris drive circuit 11.
The iris 8 is normally kept Fully open and the shutter 9 is normally kept open, so that the incident light can pass therethroughJ so enabling the light intensity to be detected. The shutter 9 is closed and the iris 8 set to the required value under control of the system controller 23. The system controller 23 is in turn controlled by a shutter-triyger pulse p triggered by 15 closure oF a shutter switch 22. When the trigger pulse p is supplied to the system controller 23 at the time tS as shown in Figure 3D, the system controller 23 is activated so that just after the time to synchronized with the odd field reference signal (Figure 3A), this being the first frame start time following the time t~;, the control process is initiated so as to derive 2D the output two-field still video signals vn and VE within a three frame period TFS (Figures 3H and 3A~. A three frame period is necessary, due to the offset between the starting times to and tE and the time taken for read-out. The two Frame periods within which the charging of the photo-sensitive elements SO and SEcan take place are determined by inhibiting the 25 normal transfer operation of the transfer gates ~a and ~Ib until the ends of these periods.
The shutter 9 is closed at the time to which is synchronized with the first leading edge of an odd field interval after the trigger pulse p and the shutter 9 is opened to start the operative exposure at the time tE
30 synchronized with the trailing edge of the above odd Field interval. That is to say, the clcsed ir~erv~l TCL of the shutter 9 cnrresponds to the interval between the beyinning of the odd-field chQrginy time and the beginning of the even-~ield charging tirne of the photc-sensitive regions SO and SE. The shutter 9 is then closed not later th~n one field period before the end of the 5 odd field available charging interval TSOA. Thus the effective exposure time TSA is variable from substantially zero to an actual msximum of two field periods, which for a sixty field per second television system is 1/30 second. In other words, the e-ffective exposure time TSA is variable, in dependence c~n the incident light, as indicated by an arrow g inFigure 3E.
As a result of the above-described operation of the shutter 9 and the time control thereof, together with control of the iris ~, the appropriate amount of incident light is irradiated on the CCD 1, and moreover the incident light is irradisted ~n the first and second photo-sensitive elements SO and SE at the same time. Consequently, each field has the 15 identical picture signal, although the picture is deviated by one line due to the interlace relation of the television signal. ~ecause the exposure is at the same time, flicker of the first kind described above does not OCCUr.
Moreover, because the maximum availsble charging periods TSOA
and TSEA for the first and second photo-sensitive elesnents SO and SE
20 respectively are the same, each having a duration of two frame periods, then even although the incident light is not irradiated on the first and second photc~sensitive elements SO and SE For the whole of these periods, the accumulated charges due to dark-currents in each of the photo-sensitive elements SO and SE are the same, and therefore flicker of the second 25 kind described above is also eliminated. Thus, as seen inFigures 3F and 3G, the dark-current charges DO and DE accum~ate substantially linearly with respect to time during the maximum available charging periods. These dark-curlent charges DO and DE are cosnbined with the actual image signals SO and S(~ accumul~sted in the photo-sensitive elements SO and SE c~ring 30 the effective expnsure time TSA, and then the combined image signals are re~d out as the output video signals VO and VE after a certain tirne interval TSM which is selected so as to prevent noise resulting from smear. In consequence, the total amounts of charge For each field are substantially the same because:
SO ~ DO = SE ~ DE
It should be noted that the output video sisnals VO and VE are read out while the shutter 9 is closed. Moreover, the output video signals VO and 10 VE are read out at least one field period TSM after the end of the exposure eime. During this period any unwanted charges, that is to say the smear noise charges for example, stored in the vertical shift registers 4 are swept out while the transfer yates 4a and 4b are maintained closed.
The read out video signals VO and VE are s-pplied to a sampling-hold 15 circuit 13 through an amplifier 12, so that the output video signals VO and VE are sampled and smoothed. The smoothed signals are supplied through a DC-removing capacitor 14 to a clarnping circuit 15 so as to be clamped at a suitable level.
As indicated in Figure 2 the CCD 1 has a shielded portion so that st 20 least one phot~senstive element 5' in each horizontal line is shielded frorn the incident light. This enables a reference black signal for use in adjusting the output video signals VO and VE to be obtained together with the image signal. The output video signals VO and VE are clamped in the clamp circuit 15 using this reference signal, and therefore the black level of the output Z5 video signals VO and VE are maintained at a required predetermined level and the black levels do not change undesirably in dependence on the input scene or variations in the camera. The clamp output signals from the clamp circuit 15 are then supplied to a processing circuit 16 in which gamma correction, and if the input signal is a color signal, a while balhnce 30 correction are carried out.
The processed video signal is encoded into a suitable signal format for recording on the magnetic disc 2 in an encoding circuit 17 and is then supplied by way of a recording circuît 1~, which may for example be an amplifier9 to a video recording head 19 for recording on the magnetic disc 2.
If the video signal is a color video signal, the encoding circuit 17 may derive snd supply color different signals R - Y and B - Y line by line together with a luminance signal Y.
In the case of a 60 field per second television system, the magnetic disc 2 is driven at 60 revolutions per second by a motor 20 under control of a 10 motor drive circuit 21 which in turn is controlled by the system controller 23 so as to be properly synchronized with the vertical shift signal ~V from the V - drive si gnal generator 7b .
As described above the maximum period for which the shutter 9 may be opened is, in a ~0-field per second television system, one 1/30, but if this 15 interval is insufficient then longer exposure times can be made available by increasing the total processing interval TFS (Figure 3A) from three frarne periods to a longer ir7terval, such as four frame periods. In this case the read-out of the output video signal VO and VE is of course shifted so as to be one frame period later than shown in Figure 3H.
Although illustrative embodiments of the invention have been described herein with reference to the accompanying drawings, it is to be understood the invention is not limited to those precise embodiments, and thflt various changes and modifications can be effected therein by one skilled in the art without departing from the scope and spirit of the 25 invention as defined by the appended clairns.
Claims (4)
1. A solid state image pick-up device comprising first and second photo-sensitive elements corresponding to odd and even fields of a television signal arranged alternately in a matrix;
a plurality of vertical shift registers mounted parallel to each other for shifting charges from said first and second photo-sensitive elements;
a plurality of transfer gates respectively disposed between said first and second elements and said vertical shift registers for shifting charges from said first and second photo-sensitive elements to said vertical shift registers;
a horizontal shift register coupled to one end of each of said vertical shift registers;
an optical shutter for controlling the irradiation of light on said first and second elements;
means for controlling said shutter to open so that said first and second elements are exposed simultaneously to said light; and controller means for controlling said transfer gates and said vertical and horizontal shift registers such that the maximum intervals available for charging each of said first and second photo-sensitive elements are the same and have a duration of at least two frame periods, the start times of said charging intervals for said first and second photo-sensitive elements respectively are relatively shifted by a predetermined interval, and the charges from said first and second photo-sensitive elements respectively resulting from said irradiation are read out sequentially after said shutter has closed.
a plurality of vertical shift registers mounted parallel to each other for shifting charges from said first and second photo-sensitive elements;
a plurality of transfer gates respectively disposed between said first and second elements and said vertical shift registers for shifting charges from said first and second photo-sensitive elements to said vertical shift registers;
a horizontal shift register coupled to one end of each of said vertical shift registers;
an optical shutter for controlling the irradiation of light on said first and second elements;
means for controlling said shutter to open so that said first and second elements are exposed simultaneously to said light; and controller means for controlling said transfer gates and said vertical and horizontal shift registers such that the maximum intervals available for charging each of said first and second photo-sensitive elements are the same and have a duration of at least two frame periods, the start times of said charging intervals for said first and second photo-sensitive elements respectively are relatively shifted by a predetermined interval, and the charges from said first and second photo-sensitive elements respectively resulting from said irradiation are read out sequentially after said shutter has closed.
2. A solid state image pick-up device according to claim 1 wherein before said charges resulting from said irradiation are read out from said first and second photo-sensitive elements said controller means causes any residual charges in said vertical shift registers to be swept out during an interval after said shutter has closed and before said read out.
3. A solid state image pick-up device according to claim 2 wherein said interval after said shutter has closed and before said read out is one field period.
4. A solid state image pick-up device according to claim 1 wherein said predetermined interval by which said start times of said charging intervals are relatively shifted is one field period.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57137861A JPS5928769A (en) | 1982-08-10 | 1982-08-10 | Still video camera |
| JP137861/82 | 1982-08-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1191942A true CA1191942A (en) | 1985-08-13 |
Family
ID=15208465
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000433615A Expired CA1191942A (en) | 1982-08-10 | 1983-07-29 | Solid state image pick-up devices |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4556912A (en) |
| JP (1) | JPS5928769A (en) |
| CA (1) | CA1191942A (en) |
| DE (1) | DE3328737A1 (en) |
| GB (1) | GB2125250B (en) |
| NL (1) | NL192554C (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3344274A1 (en) * | 1982-12-07 | 1984-06-07 | Canon K.K., Tokio/Tokyo | IMAGE RECORDING DEVICE WITH AN EXPOSURE CONTROL DEVICE |
| US5745646A (en) * | 1983-08-02 | 1998-04-28 | Canon Kabushiki Kaisha | Image pick-up apparatus for recording when recording medium is moved at a stable speed |
| JPH0666906B2 (en) * | 1984-01-31 | 1994-08-24 | キヤノン株式会社 | Optical device |
| EP0177570A1 (en) * | 1984-04-05 | 1986-04-16 | EASTMAN KODAK COMPANY (a New Jersey corporation) | Jitter-free still-framing |
| JPS60220829A (en) * | 1984-04-18 | 1985-11-05 | Olympus Optical Co Ltd | Real-time photometry system of single-lens reflex camera |
| JPH07114470B2 (en) * | 1984-05-25 | 1995-12-06 | オリンパス光学工業株式会社 | Solid-state imaging device |
| JPS6132687A (en) * | 1984-07-24 | 1986-02-15 | Canon Inc | Image pickup device |
| US4704633A (en) * | 1985-04-01 | 1987-11-03 | Fuji Photo Film Co., Ltd. | Method for reading out image information on an image having a wide dynamic range |
| US5212599A (en) * | 1985-04-17 | 1993-05-18 | Canon Kabushiki Kaisha | Electronic camera for synchronous recording of still pictures on rotating record medium |
| EP0205189B1 (en) * | 1985-06-14 | 1991-10-16 | Fuji Photo Film Co., Ltd. | Electronic still camera system |
| JPS6266468U (en) * | 1985-10-16 | 1987-04-24 | ||
| US4945379A (en) * | 1985-12-28 | 1990-07-31 | Canon Kabushiki Kaisha | Camera shutter and viewfinder control apparatus |
| JPH0797830B2 (en) * | 1986-04-08 | 1995-10-18 | ソニー株式会社 | Black level correction circuit for video camera |
| US4714963A (en) * | 1986-07-03 | 1987-12-22 | Eastman Kodak Company | Asynchronous still timing for a video camera producing movie or still images |
| JPS63177664A (en) * | 1987-01-19 | 1988-07-21 | Canon Inc | Electronic still camera |
| US4972267A (en) * | 1988-06-14 | 1990-11-20 | Fuji Photo Film Co., Ltd. | Still-video camera for eliminating dark current differences |
| JP2674135B2 (en) * | 1988-09-20 | 1997-11-12 | 株式会社ニコン | Electronic still camera |
| JPH02101878A (en) * | 1988-10-11 | 1990-04-13 | Nec Corp | Solid-state image pickup device |
| DE3839513A1 (en) * | 1988-11-23 | 1990-05-31 | Messerschmitt Boelkow Blohm | IMAGE SENSOR |
| JP2538684B2 (en) * | 1989-11-30 | 1996-09-25 | 富士写真フイルム株式会社 | Control device for electronic shutter |
| JP2660594B2 (en) * | 1990-02-23 | 1997-10-08 | 富士写真フイルム株式会社 | Electronic still camera |
| US5153732A (en) * | 1990-02-16 | 1992-10-06 | Fuji Photo Film Co., Ltd. | Electronic still camera which reduces the influence of smear and dark current |
| JP3153918B2 (en) * | 1991-09-30 | 2001-04-09 | ソニー株式会社 | Solid-state imaging device and light-shielding detection device |
| US6185044B1 (en) * | 1998-01-19 | 2001-02-06 | Fuji Photo Optical Co., Ltd. | TV lens with still-taking function |
| JP3674413B2 (en) * | 1999-10-07 | 2005-07-20 | 日本ビクター株式会社 | Image shooting device |
| DE102009054578A1 (en) * | 2009-12-11 | 2011-06-16 | Carl Zeiss Imaging Solutions Gmbh | Image recording unit and method for controlling an image recording unit |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5112724A (en) * | 1974-07-23 | 1976-01-31 | Nippon Electric Co | |
| US4366501A (en) * | 1978-04-23 | 1982-12-28 | Canon Kabushiki Kaisha | Image recording system |
| JPS5518064A (en) * | 1978-07-26 | 1980-02-07 | Sony Corp | Charge trsnsfer device |
| JPS6033345B2 (en) * | 1979-06-08 | 1985-08-02 | 日本電気株式会社 | Charge transfer imaging device and its driving method |
| JPS55163957A (en) * | 1979-06-08 | 1980-12-20 | Nec Corp | Driving method for electric charge transfer device |
| US4338514A (en) * | 1980-04-07 | 1982-07-06 | Spin Physics, Inc. | Apparatus for controlling exposure of a solid state image sensor array |
| JPS57190472A (en) * | 1981-05-19 | 1982-11-24 | Fuji Photo Film Co Ltd | Two-dimensional solid state image pickup device |
| JPS5815375A (en) * | 1981-07-22 | 1983-01-28 | Olympus Optical Co Ltd | Solid-state image pickup device |
| JPS58117776A (en) * | 1981-12-30 | 1983-07-13 | Sony Corp | Solid-state image pickup device |
| JPS59115676A (en) * | 1982-12-22 | 1984-07-04 | Canon Inc | Image pickup device |
| FR2539568B1 (en) * | 1983-01-14 | 1987-12-11 | Asahi Optical Co Ltd | SEMICONDUCTOR IMAGE ANALYZER DEVICE |
-
1982
- 1982-08-10 JP JP57137861A patent/JPS5928769A/en active Pending
-
1983
- 1983-07-29 CA CA000433615A patent/CA1191942A/en not_active Expired
- 1983-08-02 GB GB08320799A patent/GB2125250B/en not_active Expired
- 1983-08-02 NL NL8302737A patent/NL192554C/en not_active IP Right Cessation
- 1983-08-09 DE DE19833328737 patent/DE3328737A1/en active Granted
- 1983-08-10 US US06/521,968 patent/US4556912A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5928769A (en) | 1984-02-15 |
| GB2125250A (en) | 1984-02-29 |
| NL192554B (en) | 1997-05-01 |
| NL192554C (en) | 1997-09-02 |
| US4556912A (en) | 1985-12-03 |
| GB2125250B (en) | 1985-10-09 |
| GB8320799D0 (en) | 1983-09-01 |
| DE3328737A1 (en) | 1984-02-16 |
| DE3328737C2 (en) | 1993-07-01 |
| NL8302737A (en) | 1984-03-01 |
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| MKEC | Expiry (correction) | ||
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Effective date: 20030729 |