Patent ID: 7092164

Claim:
A lens array comprising: a plurality of lenses and used for a liquid crystal display device, wherein the lenses are formed in such manner that a focal length fx in a cross-section surface including a direction connecting a bright vision direction and a reverse bright vision direction of liquid crystal and an optical axis of the lenses is longer than a focal length fy in a cross-section surface including a direction orthogonal to the direction connecting the bright vision direction and the reverse bright vision direction of the liquid crystal and the optical axis of the lenses, wherein, when a pitch of the lenses is represented by 2 D, a divergence angle of an incident light with respect to the lenses is represented by 2 δ, an angle, at which a contrast ratio on the reverse bright vision side in the cross-section surface including the direction connecting the bright vision direction and the reverse bright vision direction of the liquid crystal and the optical axis of the lenses is ½ of a maximum value, is represented by θ 1 , and an angle, at which the contrast ratio in the cross-section surface including the direction orthogonal to the direction connecting the bright vision direction and the reverse bright vision direction of the liquid crystal and the optical axis of the lenses is ½ of a maximum value, is represented by θ 2 , the focal length of the lenses fx in the cross-section surface including the direction connecting the bright vision direction and the reverse bright vision direction of the liquid crystal and the optical axis of the lenses and the focal length of the lenses fy in the cross-section surface including the direction orthogonal to the direction connecting the bright vision direction and the reverse bright vision direction of the liquid crystal and the optical axis of the lenses satisfy the following formulas: fx≦D /tan(θ1−δ) fy≦D /tan(θ2−δ).