Computer graphics processing and selective visual display system – Image superposition by optical means – Operator body-mounted heads-up display
Reexamination Certificate
1995-04-10
2001-05-15
Luu, Matthew (Department: 2779)
Computer graphics processing and selective visual display system
Image superposition by optical means
Operator body-mounted heads-up display
C345S007000
Reexamination Certificate
active
06232934
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to a head mounted display system and more particularly to a single display, binocular system that projects an image in the direct line of sight of the user's eyes while maintaining the user's peripheral vision relatively free from obstruction to allow the user to selectively focus on the virtual image or not.
BACKGROUND OF THE INVENTION
Binocular head mounted display systems allow a user to view an image or images of displayed information with both eyes. Typical binocular head mounted display systems include two displays, one for each of the user's eyes, as well as two sets of identical optics so as to be very costly and heavy. Binocular head mounted display systems that include only a single display are also known. Both types of systems typically direct the user's eyes such that the axes of the eyes are parallel for viewing a projected image focused at infinity. For virtual reality applications in which the user is to be totally immersed in the video image, these binocular systems are further formed so that the user's field of view is completely blocked, the user being unable to see anything but the displayed image.
These known systems have a number of problems. For example, it has been found that with head mounted display systems in which the user cannot focus on anything but the projected image, eye fatigue often occurs. Such systems can cause feelings of claustrophobia because the user's view is completely enclosed and feelings of anxiety because the user can hear things going on in his surroundings but is not able to see what is happening. With these systems the user can also experience “sea sickness” when the motion of the image that he is viewing does not coincide with the motion that the user's body is experiencing.
Binocular systems in which the user's eyes are directed such that the axes of the eyes are parallel have been found to contribute to eye fatigue when the image is focused at less than infinity. Eye fatigue and feelings of discomfort result because it is unnatural for a person's eyes to be such that the axes of the eyes are parallel when viewing an image that is only two or three feet away.
Known binocular systems are typically designed for users having a particular “average” or “normal” interpupillary distance (hereinafter referred to as IPD). Because the IPD of users can vary considerably, these systems are usable only by a very limited portion of the population and are not suitable for general consumer applications. If a user has an IPD that varies considerably from the average IPD for which the system is designed his eye will be off of the axis of the optical system. User's who are off-axis typically see right eye and left eye images that do not line up. They may also see distortions in the image wherein one side of the image will look bigger than the other side, and/or a part of the image will be in focus while other parts of the image will be out of focus. Further, a portion of the image depicted on the display may be cut off when viewed off axis through the optics of the system.
SUMMARY OF THE INVENTION
In accordance with the present invention, the disadvantages of prior binocular head mounted display systems have been overcome. The head mounted display system of the present invention is a single display binocular system that is usable by a large portion of the population without modification. The head mounted display system of the present invention is suitable for applications requiring the user to comfortably focus at less than infinity, as well as applications requiring the user to focus at infinity, and is further suitable for applications requiring the user to view his surroundings while viewing the projected image, as well as for virtual reality applications.
More particularly, the head mounted display system of the present invention includes a support to mount the display system on a user's head; a single video image source, such as a display, that is mounted on the support; and a compact binocular optical system of minimal weight for projecting an enlarged virtual image of the video from the image source at a distance from the user that is greater than the actual path length of the optical system. Because the optical system is compact and lightweight, the support may be similar to the frame of a pair of glasses or other conventional eyewear and does not require the support to take the form of a helmet or other substantial arrangement in order to act as a counter weight for the optics as in known systems.
One feature of the binocular optical system of the present invention is that it projects a virtual image in the central field of view of each of the user's eyes, wherein the optical system and support are such as to maintain at least a portion of the peripheral view of each of the user's eyes free from obstruction. Because at least a portion of the peripheral view of each of the user's eyes is free from obstruction, the user can selectively focus on the projected image or not to minimize or substantially eliminate eye fatigue. Further, because the user is visually cognizant of his surroundings while he is viewing the virtual image, feelings of anxiety and claustrophobia are eliminated. It is also noted, that because the user can selectively view his surroundings, the system of the present invention does not promote feelings of “sea sickness” as frequently encountered with other systems.
Although the user can simultaneously view his surroundings as well as the virtual image with the head mounted display system of the present invention, it has been found that the present system creates a feeling of total immersion in the video image. Therefore the system is suitable for virtual reality applications without having the problems associated with binocular head mounted display systems typically used for such applications. This feeling of total immersion in the video image with the system of the present invention is quite surprising since heretofore it was thought that for total immersion, the user should not see anything but the projected video image. It has further been found that because the user has at least some vision of the real world, as well as the virtual image, the three-dimensional cues in the real world cause the user to perceive that the virtual image has depth, i.e. is three dimensional without requiring a stereo image source.
Another feature of the binocular optical system of the present invention is that it includes a right eye optical centerline path and a left eye optical centerline path with at least one optical element in each of these paths, wherein the right eye and left eye optical centerline paths are angled in towards the virtual image perceived by the user. Because the optical, centerline paths of the system are angle in towards the virtual image, the user's eyes are directed inward at an angle that is natural for a person viewing an object at a distance that is less than infinity as opposed to being directed so that the axes of the eyes are parallel. With the user's eyes directed naturally inward to the location of the virtual image, the head mounted display system of the present invention is more comfortable and less eye straining than prior systems.
A further feature of the binocular optical system of the present invention is that it automatically compensates for variations in the interpupillary distance of different users, wherein those variations may be as great as one inch. Therefore, the head mounted display system of the present invention is suitable for use by a vast majority of the population without requiring manual adjustment to any of the optical elements. In one embodiment, variations in interpupillary distance are automatically compensated for utilizing in each of the right eye and left eye paths a prism that bends the light from any location along the width thereof, representing various positions of users' eyes with different IPDs, towards a central area on a concave reflecto
Heacock Gregory Lee
Kuenster Gordon B.
Shimasaki Kevin W.
Luu Matthew
McAndrews Held & Malloy Ltd.
Virtual Vision
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