| 摘要 |
PROBLEM TO BE SOLVED: To reduce unnecessary light from a video element, to obtain a wide angle of view and to make resolution excellent by specifying the distance between the surface top of a reverse surface mirror and a video display element flank. SOLUTION: This device consists of a prism optical system formed of a transparent medium having a >=1 refractive index and the light beam from the video display element 1 is transmitted through the video display element flank 2 of the prism optical system P, reflected by the reverse surface mirror 3 and then reflected by a translucent film 4, and then transmitted through the pupil-side projection surface 5 of the prism optical system P and made incident on an observer's pupil 6; and the regular see- through light beam is made incident on the prism optical system P from a transmission surface 7 facing the exit surface 5 on the observer's eyeball side, transmitted through the exit surface 5, and made incident on the observer's eyeball 6. In this case, the distance between the surface top of the reverse surface mirror 3 and the surface top of the video display element surface 2 is so set as to meet 0.8<=θmin/θmax<=1.5. In the expression,θmin is the smallest angle to a virtual screen center axis, andθmax is the angle between the light beam from the exit pupil center point of the optical system to the upper end of the virtual screen and the center axis of the virtual screen.
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