| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection type stereoscopic display device having a low intensity irregularity and high homogeneity of screen intensity by mixing an acute angle component and an obtuse angle component to form the included angle of a composite mirror group, and making the difference between the acute angle component and a right angle equal to the difference between the obtuse angle component and a right angle in a directional screen made of the composite mirror group having the included angle which is not a right angle. SOLUTION: The included angle of this composite mirror group has an obtuse angle componentα1 and an acute angle componentα2, and the difference between the obtuse angle componentα1 and a right angles is made equal to the difference between the acute angle componentα2 and a right angle. The included angle is mixed with the obtuse angle component ofα1=(90+β) deg. and the acute angle component ofα2=(90-β) deg., whereβis a positive numeral below 90. A directional screen is formed with the composite mirror group having the included angle constituted of only the obtuse angle and acute angle, and it is adapted to an image display device. When such a directional screen is formed, it has a good characteristic that it is nearly symmetrical with respect to the plane center and the horizontal irregularity of screen intensity is suppressed.
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