Television – Stereoscopic
Reexamination Certificate
1998-09-02
2003-07-15
Kelley, Chris (Department: 2613)
Television
Stereoscopic
Reexamination Certificate
active
06593957
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to creation and viewing of three-dimensional moving or still images, and in particular to “autostereoscopic” systems that do not require special wearable peripheral devices.
BACKGROUND OF THE INVENTION
For well over a century, researchers have proposed and developed a variety of devices that allow viewing of images or graphic designs in three dimensions. The concept of true “stereoscopic” viewing holds tremendous potential for applications ranging from entertainment to scientific visualization and basic research. Stereoscopically portrayed stories and events carry the impact and immediacy of true realism, allowing viewers to be drawn into an experience with the sense that they are truly there.
Efforts to date have largely been confined to specific, controlled environments. For example, for decades movie-goers have donned special glasses to view stereoscopic films; for this application, the restricted presentation atmosphere and a captive audience willing to tolerate special viewing aids facilitated use of relatively unsophisticated optical arrangements. Similar audience receptivity underlies the current generation of commercial “virtual reality” devices, which require the user to wear full-vision headgear that imparts an “immersive” three-dimensional environment.
Displays involving eyeglasses or headgear control what enters the eyes rather than what exits the display. The wearable apparatus covering the user's eyes allows separate information to be provided to each eye. The left-eye and right-eye images differ in perspective but not content, so the viewer integrates the images into a single, stereoscopic picture. Early three-dimensional film systems displayed left-eye and right-eye images in separate colors, which were directed to the appropriate eye by special glasses having lenses tinted with one or the other of these colors. More recent adaptations of this approach code the left-eye and right-eye images with orthogonal polarizations, and utilize eyeglasses with orthogonally oriented polarizers.
The disadvantages to systems that require eyeglasses or wearable headgear are numerous and well-known. Beyond the inconvenience and unnaturalness of wearing an appliance, the user may also experience headaches or eye strain. Head-mounted displays suffer the additional disadvantage of being single-user devices, isolating viewers from one another and preventing them from sharing the three-dimensional experience with others.
Another popular form of stereoscopic display relies on lenticular optical technology, which utilizes a linear array of narrow cylindrical lenses to create separate spatial viewing zones for each eye. Image information for the different view zones is spatially separated in the back focal plane of the cylindrical lenslets, allowing the lenslets to direct this information only to a narrow area of the viewing plane. Recent adaptations of this approach utilize liquid crystal display (LCD) panels or LCD-projected images to provide an updatable display medium for creating the spatially separated information behind the cylindrical lenses. Lenticular displays also suffer from certain drawbacks, however, such as poor image resolution (due both to the need to divide the overall resolution of the single image-producing device over a plurality of view zones, and to diffraction). Lenticular designs are also difficult to adapt to multi-user environments.
Other approaches to stereoscopic image presentation include so-called “volumetric” displays (which utilize a medium to fill or scan through a three-dimensional space, small volumes of which are individually addressed and illuminated), and electronic holography displays. Both of these types of display require rapid processing of enormous quantities of data, even for lower resolution images, and both have significant obstacles to overcome when the displays are scaled up to accommodate larger image sizes. In addition, the volumetric displays produce transparent images which, while suitable for applications (such as air-traffic control or scientific visualization) where the illusion of solidity is less important than a wide viewing zone, do not typically provide a fully convincing experience of three-dimensionality.
Macro-optic display systems utilize large-scale optics and mirrors, as opposed to lenticular displays, to deliver each image of a stereopair to a different viewing zone. A system designed by Hattori et al. (see Hattori et al., “Stereoscopic Liquid Crystal Display,”
Proc. Telecom. Advance. Org
. (TAO) 1st Int'l. Symp. (1993)) utilizes two LCDs, one providing left-eye information and the other providing right-eye information. The outputs of both LCDs are combined by a beamsplitter, with the light passing through each LCD being focused to a separate viewing zone. The Hattori et al. system utilizes a monochrome cathode-ray tube (CRT) monitor behind each LCD as the illuminating light source. Each monochrome monitor is driven by a To camera that records the viewing area in front of the display, capturing a picture of the viewer. A pair of infrared (IR) illuminators, each emitting at a different wavelength, are angled toward the viewer from different sides. Each recording camera is equipped with a bandpass filter tuned to the emitting frequency of one or the other IR illuminator. Because the illuminators each face the viewer at an angle, one of the cameras records an image of the left side of the viewer's face, while the other records an image of the right side. A fresnel lens near each LCD projects the left-side or right-side image of the viewer's face, as appropriate, onto the corresponding side of the viewer's actual face. As a result, the image information from each LCD reaches only the appropriate left or right eye; for example, because light passing through the left-eye image LCD goes only to the left side of the viewer's face, the viewer's left eye sees only left-eye information. As the viewer moves within the viewing space, the image on the monitors moves with him, so the view zones for the left-eye and right-eye images remain properly positioned over the viewer's left and right eyes.
This type of display offers a number of advantages over prior designs. It is “autostereoscopic,” so that the user receives a three-dimensional image without special wearable peripheral devices. It is capable of delivering three-dimensional images to a moving viewer anywhere within the viewing area, and can accommodate several viewers at once. In addition, because the system uses LCDs as the primary image source for the stereopairs, it is capable of generating strongly realistic, full-color images of naturalistic scenes (as well as displaying ordinary two-dimensional television or other information). And since only two LCDs are used, the total amount of information needed to drive the display is only twice that of a standard television or monitor.
The Hattori et al. design poses problems in terms of scalability, however. Because the viewer-tracking system is implemented with CRTs, larger displays will require proportionally larger CRTs and more powerful lenses. As a result, the display size, cost, and complexity expand dramatically with increase in the size of the stereoscopic image. Moreover, because this design requires a final beamsplitter to be placed between the display medium and the viewer, the resulting three-dimensional images give the psychological impression of being inaccessible to the viewer; this arises from the fact that stereoscopic images display the least distortion when the three-dimensional content is localized at or near the surface of the display medium, which is positioned behind the final beamsplitter. Other limitations of the design stem from shortcomings that generally affect CRT displays, such as varying image intensities.
Another macro-optical design was recently proposed by Ezra et al. (see Ezra et al., “New Autostereoscopic Display System,” SPIE Proc. #2409 (1995)). Starting once again with two image LCDs combined b
Kelley Chris
Massachusetts Institute of Technology
Testa Hurwitz & Thibeault LLP
Vo Tung
LandOfFree
Multiple-viewer auto-stereoscopic display systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multiple-viewer auto-stereoscopic display systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multiple-viewer auto-stereoscopic display systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3030147