WO1996005533A1

WO1996005533A1 - Method and apparatus for direct retinal projection

Info

Publication number: WO1996005533A1
Application number: PCT/US1995/010270
Authority: WO
Inventors: Lawrence Vandewalle
Original assignee: Lawrence Vandewalle
Priority date: 1994-08-10
Filing date: 1995-08-10
Publication date: 1996-02-22
Also published as: AU3323195A

Abstract

A method and apparatus for direct retinal projection is disclosed. The present invention utilizes miniature reflective surface (14) for the direct projection of a display image onto a user's retina, thus superimposing the display image over the user's perceived visual environment.

Description

BACKGROUND OF THE INVENTION The present invention relates generally to a method and apparatus for projecting an image directly onto a person's retina through the use of an unobtrusive image projector. More specifically, the present invention relates to a device and method for causing an image to overlay onto a user's normal field of vision, thus causing the projected image to appear to be "hanging in space" at a infinitely focused distance in front of the user's eyes. Recently, developments in computer and video applications have sought to minimize the work space occupied by video display terminals, televisions and similar projection devices. In response to this problem, manufacturers have developed various arrangements for displaying images on more portable screens. However, the resolution of such miniaturized devices is often limited by the size of the individual pixels or screen projection elements. Likewise, there have been attempts to develop devices which project images onto a mirrored visor, such as a pair of goggles mounted on the user's head. To date, such devices are bulky, often uncomfortable, and can seriously obstruct the user's field of vision. Accordingly, there is a need for an unobtrusive image projection device that offers comparable image quality to a computer or television screen without occupying any work space. My invention utilizes an image focusing arrangement composed of lenses and/or mirrors, and an image source device. The image source itself could be any number of image generators, from Cathode Ray Tubes (CRT's) , to Liquid Crystal Displays (LCD's), to Light Emitting Diode Arrays (LEDA's) , to small illuminated analog devices, to scanned, gated light sources. This image is directed obliquely to the user/wearer's eye. In a preferred embodiment of the invention a direct retinal projection ("DRP") device receives the image that is focused by an objective lens and/or a collimating lens. These focusing lenses are user adjustable and are attached to the user's headgear, typically a pair of glasses. The DRP consists of one or more microscopic (at most 1/3 eye pupil diameter) image redirection and refocusing devices. These devices could consist of microscopic focusing mirrors; or microscopic prisms coupled with microscopic lenses; or microscopic flat mirrors coupled with microscopic lenses, or any type of focusing and redirecting optics of sufficiently small size, and proper focusing and reflecting qualities. DESCRIPTION OF THE PRIOR ART

United States Patent No. 5,184,250 (Lacroix) discloses a device for the display of simulated images for helmets. Lacroix uses an apparatus that displays an image to a helmet that contains a series of at least semi-reflective surfaces. Lacroix does not teach or suggest a device for the unobtrusive presentation of a display image into the retina of a viewer. The use of a helmet in an office would be awkward and aesthetically displeasing. The present invention, by contrast, offers a device that projects an image onto a user's retina and yet is unobtrusive and not easily noticed by the user or those near the user. Also, the invention offers the option of letting the user concentrate on the displayed image, or on his or her actual environment. It has a smaller visual profile that allows the user to view his or her environment by focusing around the DRP, as opposed to Lacroix which has a larger visual profile covering the entire surface of the user's goggles or helmet and thus must be only partially transparent.

United States Patent 4,205,224 (Mecklenborg) discloses a binocular viewing technique whereby only an image corresponding with a particular eye is viewed by the particular eye.

Specifically, Mecklenborg discusses the ability of a simulator to provide a realistic binocular visual cue to an observer.

Unlike the present invention, Mecklenborg does not suggest the ability to provide alternating or overlaid images onto the actual environment of an observer. Nor does it suggest any unobtrusive means for presenting any display image onto the retina of a user.

United States Patent 4,993,808 (Braakman) discusses an apparatus for directed optical signaling for improving the angle of sight and light markings of keys on a keyboard.

Braakman is not directed towards a direct retinal projection of a display image.

In short, none of the references, alone or in combination, teaches an apparatus for directly and unobtrusively projecting an image onto a user's retina. Specifically, none of the references teaches the use of microscopic refocusing and redirecting devices for allowing the co-incident viewing of either a projected image or the viewer's actual environment. SUMMARY OF THE INVENTION

Some of the qualities of the invention are its small size (i.e., it is too small to be readily discernible at a close distance to the eye — much like a small speck on the inside of a pair of glasses) and its redirecting and potential refocusing optical qualities. This focusing optical quality could be of either negative or positive focal length, resulting in an image that is either upright, or inverted from the original source (respectively) . If a positive focal length is used, the original image source is simply mounted in an inverted position, resulting in an upright image for the user of the device. Further, direct retinal projection devices that have a flat (neutral) surface can be used in my invention if a pre-focusing mirror or lens of a sufficient size is first place in the path of the image being projected.

If a wider field of view is desired than can be obtained from one single device, multiple devices can be employed from the same image-source beam or beams, mounted above and/or below each other, or on either side of each other, or both. The only requirements are that these multiple devices be aligned optically parallel to each other, and be located close enough to each other to allow the images from these respective devices to overlap, and all be within reasonable focal distance within their respective image-source beam. The outputs from these multiple devices overlap and are perceived as one continuous image by the user.

For example, a typical completed device would receive an image projected by a miniature CRT. This image would be focused through a collimating lens, to make the light rays from the image parallel; this collimated image would then be focused through an objective lens. This focused image would then be directed to a first surface mirror, located just to the outside of, and at a 45 degree angle to the user's eye, across (or oblique to) the user's eye. This now focused image would be intercepted by a DRP device consisting of a very small elliptical convex mirror mounted at a 45 degree angle to the user's eye and at a 90 degree angle to the previously mentioned mirror. This mirror would have a negative focal length, and be located that amount short of the focal length of the objective lens in the image path of the objective lens. This mirror is fastened to the inside surface of the lens of a pair of glasses being worn by the device user, which would also provide a convenient frame for the other components (i.e., the CRT, the collimating lens, the objective lens, and the 45 degree first surface mirror.) The wearer of these glasses would see not only the "normal" view through these glasses, but also the image being projected by the DRP device. The DRP device itself would not be discernible, due to its small size and proximity to the user's eye (i.e., it is inside the depth of field of the user's eye).

The function of the present invention is analogous to being able to see through a pin hole punched in a piece of paper, yet being unable to see the tip of the pin (that made the pin hole) when held at the same distance as that piece of paper. Even though the pin is the same diameter as the hole, you cannot see the pin.

This device could make any computer application truly miniaturized and mobile. Further, such a device allows for superimposing any projected image over the user's actual environment.

Such a device would be useful, for instance, for military personnel, who could use this device in a personal mobile battlefield computer that would link them to a central dispatch site, as well as each other, so that messages (as well as limited volume video and audio data) could be shared via an encrypted wireless LAN (Local Area Network) system. This device has the advantage of being much smaller, and much more durable than standard LCD screens, CRTs, or other "full-size" screen-based computers. It would also be much more discreet (because it emits much less light than other types of viewing screens) . Law enforcement personnel would also find similar uses for such a device. The device could further be employed on a rifle to project the virtual image of a reticle or gunsight on the desired target. Such a device would include a light source on the side of the rifle barrel (near the muzzle) , projecting back towards the stock, reflecting off of a mirror, projecting through an objective lens, and off of a DRP positioned on the top of the stock in place of the gunsight.

This device would also be useful for stock and commodity traders who could use it to view certain confidential financial information in privacy, while interacting in a public place (like the trading pits), and maintaining the privacy of that data.

It would be useful for consumers as a private-view portable television, integrated into a pair of sunglasses, for example.

Accordingly, it is an object of the present invention to provide an unobtrusive device for directly projecting an image onto the retina of a user.

It is a further of the present invention to provide a device that allows a user to process significant amounts of customer data while still interacting with his or her surrounding human environment. This device could be used as the monitor screen of a computer terminal, and would allow continued eye contact by a user with his or her clients while performing the required data inquiry and data entry functions. It is still a further object of the present invention to free up the desk/work station "real estate" taken by a conventional CRT.

It is yet a further object of the present invention to offer a direct retinal projection device that is conventional in appearance, thus creating less user resistance to wearing it (as compared with many of the other CRT "goggles" type devices) .

Yet another object of the present invention is to provide a pair of "night vision" glasses wherein the charge-coupled devices of two night vision scopes would be mounted on the outside edges of the glasses. The DRP devices would then constitute the viewing screens of the two respective night vision scopes. The wearer of these glasses would then see a "night vision" scene superimposed upon the real world view of the world around him.

A further object is to provide "heads-up" type displays for anyone who needs to see a real world view of his or her surroundings, as well as additional data superimposed on that real world view, such as pilots, cyclists, automotive and freight drivers, surgeons, laboratory technicians, and so forth. Yet another object of the present invention is to allow for a mobile computer display to operate in conjunction with a miniaturized CPU (Central Processing Unit) .

These and other objects and advantages of the present invention will become apparent to those skilled in the art from reviewing the following drawings, the detailed description of the preferred embodiments and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a top plan of one preferred embodiment of the invention, including an objective lens that receives an image source and a plurality of DRP's (exploded from their supporting frame) that reflect the focused image source onto the viewer's retina.

Figure 2 shows a top plan of another/alternative preferred embodiment of the invention, showing the passage of an image source through a collimating and an objective lens, through an image diverter comprising a Fresnel (or stepped) prism or similar reflective surface, and finally reflected off of a series of DRP's (shown in an exploded position from their supporting frame) that place the focused image onto the viewer's retina. The stepped or fresnel prism causes all image beams to have the same focal length for all DRP's.

Figure 3 shows a schematic diagram of a lens counterpart of a preferred embodiment of the present invention, showing an example arrangement of a concave DRP and an objective lens.

Figure 4 shows a schematic diagram of a lens counterpart of a preferred embodiment of the present invention, showing an example arrangement of a convex DRP and an objective lens. Figure 5 shows a partial three-quarter, front view of an embodiment of my present invention, displaying the relationship and positioning of the image source and reflective prism to the frame of the glasses and the paths for the virtual and real- world images seen by the user.

Figure 6 shows a frontal view of a spacing of DRP's within a lens for a full field virtual image projection in a preferred embodiment of my invention.

Figure 7 shows a top view example of the placement of DRP's within the lens of a preferred embodiment of my present invention.

Figure 8 shows a second example of the placement of DRP's within the lens of a preferred embodiment of my present invention. Figures 9A-E show the steps for the method of manufacture of a series of DRP surfaces within a lens for a preferred embodiment of my invention.

Figure 10 shows a perspective view of a gunsight embodiment of my present invention, including a light source at the tip of a gun barrel that is projected through an objective lens, reflected by a plurality of prisms, and finally reflected off of a DRP that is positioned as a sight immediately in front of the marksman's eye. Figure 11 shows a partial perspective view of a field of DRP's set in a lens section. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention is a device to project an image directly onto the retina of the user/wearer of the device, causing the image to appear to be "hanging in space" at an infinitely focused distance in front of the user's eyes. Thus, for example, if the user is staring at a blank wall, the image appears to be projected on the wall, if the user is staring at the sky, the image appears to "hang", suspended, in the sky; and so forth. As shown in Figures 1 and 2, my device incorporates a image focusing apparatus 10 composed of lenses and/or mirrors using optical procedures and an image source 12. The image source itself could be any of a number of image generators, from Cathode Ray Tubes (CRT's), to Liquid Crystal Displays (LCD's), to Light Emitting Diode Arrays (LEDA's), to small illuminated analog devices, to scanned-gated light sources. The technology for creating such an image source is already known. In its most basic form the invention would not require a miniaturized image source but rather could redirect any standard image (such as a television or a computer screen) . This image is directed obliquely to the user/wearer's eye.

This device consists of one or more microscopic Direct Retinal Projection (DRP) devices 14 for image redirection and potential focusing. The diameter of each DRP should be no greater than approximately one-third the diameter of the pupil (i.e. on the order of 1mm in diameter or less). These devices consist of microscopic focusing mirrors, microscopic prisms coupled with microscopic lenses, microscopic flat mirrors coupled with microscopic lenses, or any type of redirecting and potential focusing optics of sufficiently small size, and proper focusing and reflecting qualities. The qualities of this device are its small size (too small to be readily discernable at a close distance to the eye - much like a small speck on the inside of a pair of glasses) and its redirecting and potential focusing optical qualities. This focusing optical quality could be of either negative or positive focal length, resulting in an image that is either upright, or inverted from the original source, respectively. If a positive focal length is used, the original image source is simply mounted in an inverted position, resulting in an upright image for the user of the device.

If a wider field of view is desired than can be obtained from one single device, multiple devices can be employed from the same image-source beam, mounted above and/or below each other, or on either side of each other, or both. For example, my experimentation, examples of which are detailed below, indicates that a group of DRP's spaced approximately 5 millimeters apart in a 2 by 3 grid will be sufficient to project a virtual image roughly the size of a large television screen at a distance of 1 meter to the viewer. The only requirement is that these multiple devices be aligned optically parallel to each other, and be located close enough to each other to allow the images from these respective devices to overlap. The outputs from these multiple devices overlap and are perceived as one continuous image by the user. Closer spacing of the DRP's would result in a brighter image. The ultimate limiting factor however would be the ability of the user to focus around and/or through the increasing number of DRP's.

A basic preferred embodiment of my device as shown in Figure 1 would consists of an image source 12, such as a miniature CRT. The image is focused through an objective lens 18. This image would then be projected onto the surface of a DRP 14 consisting of a very small convex mirror mounted at an angle to a user's eye that is approximately one half the angle of the user's eye to the image source 12. The DRP 14 would be integral to a surface lens 20 which is attached to a frame 22 of a pair of glasses worn by the user (although the invention covers other support vehicles, e.g., contact lenses). The wearer of the glasses would see not only a normal surrounding view but also the image projected by the DRP. The DRP 14 would not itself be discernable due to its small size and proximity to the user's eye (i.e., it is inside the depth of field of the user's eye for an object of its size) .

A second preferred embodiment, as shown in Figure 2, consists of an image source 12 projecting the virtual image through a collimating lens 16 and focusing the image through an objective lens 18. This focused image would then be directed off of a Fresnel (stepped) prism or stepped first surface mirror 24. The stepped prism or mirror 24 is located just to the outside of, and at just over 45 degree angle to the user's eye and is across from (or oblique to) the user's eye. This pre-focused image is intercepted by a DRP 14 at a 90 degree optical angle to the stepped prism or mirror 24. In Figure 2, the Fresnel prism 24 converts the image into a number of component images which are reflected off of individual DRP's 14 of complimentary length, thus assuring a substantially identical length of projection for each portion of the image being projected into the user's retina. However, any reflective surface could be used to practice this embodiment of my invention so long as the DRP's are all substantially within the depth of field of the focal length of the objective lens.

As shown in Figures 3 and 4 (which are counterpart lens based optical representations, with a convex lens substituted for a concave reflective surfaces and vice versa) , the image travels through at least one objective lens 18 and a DRP of coincident focal length (i.e. their distance of separation is approximately the sum of their focal lengths) . The optics of my invention are such that the use of a convex DRP 14, as shown schematically in figure 4, will project a virtual image onto the bottom of the user's retina, thus appearing as an "upright" image. However, a concave DRP 14 used in conjunction with a convex objective lens 18 (as shown in Figure 3) are such that the image will appear to be turned upside down. This effect can be compensated for by inverted the image source 12 being projected. Similarly, the reversal of the image by its reflection by the DRPs 14 can be compensated by the projection of a left-to-right reversed image from the image source 12, or through the imposition of a second reflective surface within the path of the image being projected.

As shown in Figure 5, the image source 12, collimating lens, 16, objective lens 18, and a first surface mirror 24 (if used) can be attached to or made integral with the frame 22 of the glasses. Since the glasses into which this device are incorporated could be made to be quite conventional in appearance, there would be less user resistance to wearing them (as compared with many of the other CRT "goggles" type devices) . As shown in Figures 6 and 11, a preferred embodiment of my invention includes a grid of DRPs, with each DRP being 1 millimeter in diameter. The DRP's are spaced approximately 5 millimeters apart. This grid would offer a full field view of the-CRT or other image source 12.

My invention could also extend to support frames other than glasses. For instance, as shown in Figure 10, my invention would include a virtual image gunsight. Such an embodiment would include a light source 26 mounted on the side of the tip of a gun barrel 28. The light source would project a cross¬ hair or other target acquisition indicator image back along the length of the barrel towards the shooter. The image would be first focused by an objective lens 18, then directed off of a first reflective prism 30, a second reflective prism 32 and onto a DRP 14. The DRP would be placed onto the top of the barrel directly in front of the shooter's eye, in the position normally occupied by a gunsight. Thus, the virtual image projected into the shooter's eye would be on substantially the spot at which the gun barrel would be aimed. As shown in Figures 7-9, the DRPs of my invention could be manufactured through being embedded within the surface lens 20 of pair of glasses. Such a method of manufacture would include grinding a number of notches or slits on the surface of the lenses. Second, the lens surface would be covered with a reflective material. Third, the lens surface would be ground to remove any reflective material not inlaid in the notches or slits. Finally, the lens could be mated with another lens of similar optical density, using a filling adhesive of similar optical density, thus embedding the DRPs within an optically uniform surface lens 20.

The method for practicing my direct retinal projection invention comprises a first step of focusing a virtual image 34 through an objective lens. The second step of the invention comprises directing 36 the image off of a miniature reflective surface directly in front of the user's eye, thus projecting the image onto the user's retina. Alternatively, the method for practicing my invention would include reflecting 38 the image from the objective lens off of a second reflective surface onto the miniature reflective surface.

Of course, it should be noted that various changes and modifications to the preferred embodiments of this invention will be apparent to those skilled in the art, such changes and modifications can be made without departing from the spirit and scope of the present invention. For example, my invention could be useful as a pair of "night vision" glasses wherein the Charge-Coupled-Devices of two night-vision scopes would be mounted on the outside edges of the glasses. The DRP devices would then constitute the viewing screens of the two respective night-vision scopes. The wearer of these glasses would then see a "night-vision" scene super imposed upon the real-world view of the world around him.

A further alternative embodiment would consist of a miniature CRT (or other image source) mounted so that its image is oblique to and at roughly a right angle to the user's eye. This image of the screen would be focused, magnified, and re¬ directed towards the user's eye by one or more objective lenses 18 having an overall positive focal length incorporated into the DRP. This device could consist of a microscopic convex lens before and/or after the image redirecting portion of the DRP, or it could consist of an appropriately ground concave mirrored DRP itself. An additional alternative embodiment would incorporate a scanned, gated, light source as the image source of my invention. Such an embodiment would employ a scanner in place of some or all of the focusing lenses, but project a similar, focused image off of a DRP and onto the retina of the user. It is, therefore, intended that such changes and modifications be covered by the following claims.

Claims

CLAIMS I claim:

1. An apparatus for the direct projection of an image on a user's retina, said apparatus comprising: a. a miniature reflective surface for directing a virtual image directly onto the user's retina; b. a support for holding the reflective surface in a fixed position in the user's field of vision.

2. An apparatus for the direct projection of an image on a user's retina, thus providing an image overlay to the user's visual environment, said apparatus comprising: a. a miniature reflective surface for directing an image directly onto the user's retina; b. a support for holding the miniature reflective surface in a fixed position, said support having sufficient scope to view the image projected by said reflective surface and the user's environment simultaneously.

3. A method for projecting a image directly onto a user's retina, said method comprising the steps of: a. focusing the image through an objective lens; and

b. reflecting the image off of a microscopic reflective surface onto the user's retina.

4. A method for projecting a image directly onto a user's retina, said method comprising the steps of: a. focusing the image through an objective lens; b. directing the image off of a first reflective surface; and c. reflecting the image off of a second microscopic reflective surface into the user's retina.

5. An apparatus for the direct projection of an image onto a user's retina, thus providing a virtual image overlay to the user's visual environment, said apparatus comprising: a. a miniature reflective surface for directing an image directly onto a user's retina; b. a support frame for holding said miniature reflective surface in a fixed position, said support frame further providing an unobstructed field of vision for the user; and c. a plurality of lenses for refocusing and directing the image to said reflective surface, said plurality of lenses being operatively attached to said support frame.

6. The apparatus of claim 5, further comprising image projecting means fixed to said support frame, said image projecting means directing said image towards said plurality of lenses.

7. The apparatus of claim 6, wherein said image projecting means comprises a cathode ray tube.

8. The apparatus of claim 6, wherein said image projecting means comprises a light emitting diode array.

9. The apparatus of claim 6, wherein said image projecting means comprises a liquid crystal display.

10. The apparatus of claim 5, wherein said support frame comprises a frame for a pair of glasses.

11. The apparatus of claim 10, wherein said frame further comprises at least one support lens for receiving said reflective surface.

12. The apparatus of claim 11, wherein said reflective surface is mounted between a plurality of support lenses.

13. The apparatus of claim 5, further comprising a first surface mirror for redirecting said image from said plurality of lenses onto said miniature reflective surface.