1. Field of the Invention
This invention relates to an eye movement tracking display for presenting a realistic visual image to a person.
2. Description of the Prior Art
Head mounted displays have been developed for visually presenting a person with a scene taken by a TV camera or with a realistic virtual image generated in a computer and displayed graphically. The head mounted display is equipped with a pair of independent TV monitors disposed one in front of each eye so as to enable the viewer to perceive a 3D sensation with stereo effects.
With such a head mounted display, when images taken by TV cameras or graphic images generated on computer displays are manipulated in accordance with movements of the viewer's head detected by a goniometer or magnetic means, the viewer is given the sensation of viewing the environment imaged by the cameras from the position of the camera or of being present in the world of imagery presented by computer graphics. Since the images are presented to the left and right eyes by two small image displays, however, the frames of the image displays are constantly within the viewer's field of view. This detracts from the sense of reality of the experience.
It is known that most human beings have a field of vision that extends .+-.40.degree. from the central axis of the eyeball. Therefore, unless the head mounted display is equipped with TV monitors whose picture areas are large enough to cover this region, the viewer will be able to see the monitor frames and be given the impression of viewing the displayed images as if peering through the frames. One conceivable way of overcoming this problem is to use TV monitors with picture areas large enough to cover the maximum field of vision of humans. However, this solution is not generally feasible because of the limit on the number scanning lines that TV monitors use to display images (525 lines in the NTSC system monitors and 2,000 lines in high-definition TV monitors). Since the number of scanning lines cannot easily be increased, making the monitor large enough to cover the field of vision of the human eye would decrease its resolution, and when the resolutions decreases, the viewer sees a less distinct image that distracts from the sense of reality of the experience.
While it would be possible to overcome this problem by using TV monitors with enough scanning lines to display pictures that the human eye perceives as sharply defined even when enlarged to cover the whole of a person's field of vision, the development of such a high-resolution TV monitor is difficult with today's technology. The inventor therefore conducted studies in search of a method for expanding the current narrow field of vision of the head mounted displays without increasing the number of scanning lines and without lowering resolution.
It is known that the human eye can see an object clearly only in a small region near its view point (the position on the object toward which the central axis of the eyeball is directed). The range of this region is ordinarily .+-.5.degree. of the view point and vision outside this region is blurred. From this it can be concluded that it suffices to display a high-resolution image only within the small area of clear vision in the vicinity of the view point and to display a low-resolution image over the remainder of the field of vision. The display of the high-resolution image within the small area of clear vision can be achieved by causing the high-resolution image to track the detected movement of the viewer's eye (the view point). For this it is necessary to use an image display that is able to display a high-resolution narrow view angle image only in a small area near the view point and display a low-resolution wide view angle image in the peripheral region outside the small area. No image display developed up to now is able to display images in this manner.
The present invention was accomplished in view of the foregoing circumstances and has as its object to provide an eye movement tracking display which comprises an image display able to display a wide view angle image while simultaneously displaying a high-resolution image in the vicinity of the view point of the viewer's eye and which is compact enough to be easily mounted on the viewer's head.