Computer graphics processing and selective visual display system – Image superposition by optical means
Reexamination Certificate
1998-06-05
2001-08-07
Hjerpe, Richard (Department: 2774)
Computer graphics processing and selective visual display system
Image superposition by optical means
C345S008000
Reexamination Certificate
active
06271808
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of personal display devices. More particularly, this invention is directed toward a portable head mounted display using a single display device that displays animated images in either a three-dimensional stereo perspective or a non-stereo mode.
BACKGROUND OF THE INVENTION
People with typical eyesight perceive depth of field while viewing three dimensional objects. They also rely on their depth of field perception when they undertake ordinary, commonplace activities such as driving a car, walking down the street, and playing sports. Most people closely associate their ability to perceive depth with reality. However, the majority of computer images, digitally generated images, movies and television programs are viewed as a series of two-dimensional images. While viewing computer images, digitally generated images, movies and television programs in two dimensions, the audience does not experience a realistic three-dimensional, stereoscopic perspective. Viewing movies and television programs in this three-dimensional perspective gives the viewer an additional element of reality.
For a person with normal eyesight, perceiving depth of field is achieved by close interactions between the person's nerve endings, brain, and eyes. When viewing an object, the right eye perceives a slightly different image than the left eye. This slightly different image between the right eye and left eye is normal because the right and left eyes reside in different locations relative to the object being viewed. The nerve endings of each eye perceive the right image and left image of the right and left eye, respectively. The nerve endings then transmit these images to the brain. The brain utilizes both the right and left images to produce a depth of field or stereoscopic perspective for the person viewing the object. These interactions occur very rapidly and appear naturally to the viewer.
There are numerous prior devices that attempt to provide viewers with a stereoscopic perspective while viewing a two-dimensional image. For example, U.S. Pat. Nos. 3,802,769 and 4,012,116 both only provide a stereo-effect image for still images. Further, both of these references require the viewers to be located at a center location relative to each device in order to experience the stereo-effect image. Accordingly, since each device is not attached to the viewer, these devices fail to provide the viewer with the stereo-effect image, once the viewer changes position such that the viewer is no longer aligned with the center of the device; it is unreasonable to expect an average viewer to remain motionless so that these types of applications are only temporarily effective. In addition, these devices taught by U.S. Pat. Nos. 3,802,769 and 4,012,116, only display still images. As a result, these devices have very limited applications.
Other stereoscopic viewers utilize polarizing filters to display right and left images to each corresponding eye of the user. For example, U.S. Pat. Nos. 4,623,219, 4,719,507, and 4,744,633, teach the use of polarizing filters to display stereoscopic, animated images. In these references, one image is modulated by linearly polarized high intensity light. The other image is modulated by an orthogonally disposed component of the above linearly polarized high intensity light. The viewers wear polarized glasses to allow each eye to view the respective left and right images. These systems suffer the drawback of only being effective for three-dimensional viewing when the image has been specially encoded for left and right images. Further, the use of these polarizing filters decreases the efficiency of the system because a portion of the light waves are lost in the decoding process. This decrease in efficiency results in images that lack the more vivid qualities of unfiltered images.
Three-dimensional glasses, with one red lens and one blue lens, are also very well known. Similar to the polarizing filters discussed above, this technique utilizes color filter so that one image is modulated by blue light waves and the other image is modulated by red light waves. This suffers similar drawbacks of the polarizing filters described above which include the need to encode a left image and a right image and the loss in efficiency because the left and right images need to be decoded. Further, because of the colored lenses, the viewer cannot perceive natural, balanced colors.
Some stereo viewing devices use two full displays. One display is provided for each of the user's eyes. Each of the display is provided with the appropriate data for forming the image that would naturally be seen by that one of the user's eye. Such a system adds cost due to duplication of display and light sources. Additionally, it has been observed that errors in registration between the displays, errors in focus, color and update rates of the two displays relative to one another can disorient or nauseate a user.
What is needed in a low cost method and apparatus of producing appropriate stereo images for a user's left and right eyes which are uniform and eliminates optical errors. What is needed is a device which displays three-dimensional stereoscopic images from a two-dimensional image source. What is further needed is a device which allows the user to view three-dimensional stereoscopic images without utilizing filters and while allowing the user to move freely. What is further needed is a device that does not expose the viewer to potentially harmful radiation from a cathode ray tube.
SUMMARY OF THE INVENTION
The present invention utilizes a single display to produce both a left image and a right image. The right image is directed to a right eye of the user, and the left image is directed to the left eye of the user. When in the stereoscopic mode, the right and left images differ from each other such that when viewed by the user, the combined right and left images give the user a stereoscopic, three-dimensional effect. When in non-stereoscopic, two-dimensional mode, the right and left images are the same. By providing the same images to the right and left eyes, the present invention provides the viewer with an image which appears brighter.
The present invention has many advantages over the prior devices by using a head mounted display. When worn on the head of the user, the present invention is properly aligned to provide the right image to the right eye and the left image to the left eye. Further, as the user moves, the present invention remains properly aligned such that the user can continue viewing the right image with the right eye and the left image with the left eye independent of movement by the user so long as the user keeps wearing the present invention.
The present invention also utilizes a single display which comprises a plurality of grating light valves. For example, both left and right light sources are directed to the display. The grating light valve receives the light from the left light source as the right image and selectively directs the light to the user's right eye. Similarly, the grating light valve receives light from the right light source as the left image and selectively directs the light to the user's left eye. The modulation of light by the grating light valve is configured to be accomplished sequentially and also sufficiently fast to multiplex both complete right and left images in a single time frame thereby preventing flicker. By using only one display, the present invention is inherently aligned to produce an accurate right and left images viewed by each respective eye without internal adjustments. Further, by using the grating light valve, the user is only exposed to either diffracted or reflected light. The present invention avoids exposing the user to harmful radiation such as from a cathode ray tube. Additionally, the grating light valve creates two images without the use of any filters. Further, by using frame sequential color and line sequential color with the single display, ftill color images are produced wi
Dinh Duc Q.
Haverstock & Owens LLP
Hjerpe Richard
Silicon Light Machines
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