Jan. 2000
Recently research on 3-dimensional display technology is prospering. It is because various innovative systems are expectable with the application to each field. However, the system has the general-purpose as popular performance as the present television is not yet developed. It is because some problems, such as the property of vision, viewing zone, cost performance, and the amount of information, have not been settled. Although it is difficult to settle them, I set up the actual purpose of this research to develop a component technology an ideal 3-dimensional display will be popularized in the future.
The factors of human depth perception contain various things, such as binocular disparity, vergence, accommodation, motion parallax, and mental factors. Human being processes them in parallel and perceives the depth synthetically. The stereoscopic display system adopted in this research supplies the parallax images for left and right eye respectively, and is made to perceive the depth from the factor of binocular disparity.
The researches of the conventional 3-dimensional image display can be roughly divided into stereoscopic display system and 3-dimensional display system. Many of the stereoscopic display systems use special spectacles, such as polarizing spectacles, and generates effect of binocular disparity using them, while 3-dimensional display system displays the parallax images from many viewpoints, and can represent motion parallax, and can be observed by two or more persons simultaneously. Particularly, holography can also represent accommodation. Judging from the above problems, these researches have both advantages and disadvantages.
In this research, I proposed a new technology called total reflection stereoscopic display system. This system based on the principle of the total reflection occurs on the interface. With the critical angle, the parallax images of right and left are divided, the directions of the lights are controlled, and separate images are supplied to each eye. Since it is desirable that stereoscopic vision is practicable from front of the displays, I verified about the suitable angle of an air layer. And I found the condition to realize stereoscopic vision. To realize this system, a system using a water tank and a system using prism sheets are proposed. The former consists of a water tank, water, and two glass sheets sandwiched an air layer. It has a simple structure. The latter realizes parallax images division inside minute prisms, and brings about the same effect by arranging them continuously. Furthermore I tried to extend the viewing angle, and relieve from inconsistency of the property of vision by arranging a convex lens in front of both systems. However, these systems have a problem about cross talk. As the measure, I restrained reflection using a polarizing filter whose property that the reflectance varies with the polarized light, and tried to reduce cross talk.
I actually made the two prototypes of stereoscopic displays using a water tank and using prism sheets, respectively. I connected a PC to two liquid crystal displays for parallax image using the multi monitor function of Windows98, and displayed a CG object using OpenGL. Moreover, I used the prism sheets of the pitch of 0.1mm that the slot of prisms is not conspicuous and the influence of diffraction is small. First, I measured the viewing zone of the prototypes of display, and the result was sufficient width for observing individually. Next, I evaluated the range of the stereoscopic image display depth with subjective evaluation method, and the result was it could display in the depth over 30 cm. Finally, I evaluated the effect of reduction of the cross talk by the polarizing filter, I found that cross talk is unable to be recognized under lighting in the room and no effect on observation.
Above experiments showed that a satisfactory performance, as a result of examining the pitch of minute prisms, the range of stereoscopic image display depth, and the influence of cross talk. Moreover, by comparing between the systems using a water tank and using prism sheets, I concluded that it is in no way inferior to the system using a water tank in performance in spite of the system using prism sheets achieves light weight and safety.
The total reflection system which I proposed in this research is a new system different from the existing stereoscopic display technology, and does not need special spectacles, and is high resolution and flicker-free. It conquered the problem of the conventional 3-dimensional display technology that the cost is high and the amount of information is much, and the property of the vision, which was the fault of the stereoscopic display system. As problems to settle, it should realize that more than one person are observable, and the relief inconsistency of the property of the vision in the future.