Patent ID: 7777950

Claim:
A stereoscopic image display apparatus, comprising: a plane display device having a display face formed of a plurality of pixels arranged in a matrix form; an optical plate comprising a plurality of lenses which are arranged in front of the display face of the plane display device and which have a uniaxial double refractive material inserted therein, and controlling light rays from the pixels; and a sheet polarizer provided between the plane display device and the optical plate to align a polarization direction of light ray, wherein in the double refractive material, a maximum primary axis of refractive index is parallel to ridgelines of the lenses and is inclined in a direction opposed to a viewer; and wherein in each of a plurality of lenses, lens faces have opposed convex shapes in opposite directions, 2θ denotes a viewing angle, s p denotes a sub-pixel pitch in a horizontal direction, m denotes a number of parallaxes in the horizontal direction, n lens denotes an average value of a refractive index of a medium located from a position corresponding to half of a length between tops of the convexo-convex lenses to the plane display device, r denotes a radius of curvature of both faces of the lenses, d denotes a thickness of lenses between tops of the lenses, N e denotes a refractive index in a maximum primary axis direction of the double refractive material formed inside the lenses, N o [[(<N e )]] which is less than N e denotes a refractive index in a minor axis direction perpendicular to the maximum primary axis direction, n denotes a refractive index of an isotropic substance formed outside the lens faces of the lenses, θ vert denotes a depression angle of a viewer with respect to a direction of the ridgeline of the lenses, θ tilt denotes an angle of inclination of the maximum primary axis direction to a direction opposed to the viewer, and θ real denotes an angle formed by a light ray which passes through the double refractive material and the maximum primary axis direction, and θ real is represented by the following expression θ real =arccos(cos θ vert /N e )+θ tilt and if a refractive index obtained when the light ray has passed through the double refractive material is represented by the following expression, N ⁡ ( θ real ) = N e ⁢ N o N e 2 ⁢ sin 2 ⁢ θ real + N o 2 ⁢ cos 2 ⁢ θ real the angle θ tilt satisfies the following condition 0.95 < 2 ⁢ nr 2 ⁢ N ⁡ ( θ real ) ⁢ sin ( arccos ⁡ ( cos ⁢ ⁢ θ vert / n ) ⁢ tan ⁢ ⁢ θ ( N ⁡ ( θ real ) - n ) ⁢ ( 2 ⁢ N ⁡ ( θ real ) ⁢ r - ( N ⁡ ( θ real ) - n ) ⁢ d ) ⁢ s p ⁢ m < 1.05 .