Patent ID: 6532116
Filing Date: 2003-03-11
Classification: G02B

Abstract:
An image display apparatus, comprising:an image display device for displaying an image; and an optical system for projecting an image formed by said image display device without forming an intermediate image and for leading the projected image to an observer's eyeball, said optical system including a concave mirror having a reflecting surface differing in power depending on the azimuth direction which is concave toward the observer's eyeball and an optical element of positive refractive power which is disposed between said concave mirror and said image display device, wherein a direction of an optical axis incident on an observer's pupil is defined as a Z-axis direction, a Y-axis is defined so that decentration of said concave mirror is made in a YZ-plane, and an X-axis is defined so as to intersect both the Y- and Z-axes at right angles, and wherein when an aspherical surface is defined by the following expression: X=Z2/r1+1-(K+1)&it;(Z/r)2+BZ4+CZ6+DZ8where r is a paraxial radius of curvature, said image display apparatus has the following properties: radius ofrefractivecurvaturespacingindexAbbe(mm)(mm)(nd)numberR1âˆž5.0R216804.335.01.5163364.15R3140.45723.88parallel-(toric aspherical surface) eccentricK = 0, B = 2.11374E-5, C = âˆ’8.33915E-84 mm97.0315 (not shown, azimuth direction in a planeperpendicular to the cross-sectional view)R488.41116mirror(toric aspherical surface)K = 0, B = 7.36902E-7, C = âˆ’3.61139E-10parallel-68.4073 (not shown, azimuth direction in a plane eccentricperpendicular to the cross-sectional view)3 mmK = 0, B = 0, C = 0IP = 31 mmâ€ƒ&thgr;= 50Â°â€ƒ&phgr;0/&phgr;90 = 0.77E-i represents X10â€²wherein R1 corresponds to said image display device, R2 and R3 correspond to said optical element, and R4 corresponds to said concave mirror.