PURPOSE: To uniform contrast and density over the entire surface of a liquid crystal display surface by putting a Fresnel lens between a liquid crystal display panel and an observer and varying the saw-tooth angle of the Fresnel lens locally.

CONSTITUTION: Emitted light 13 from a back light is transmitted through the liquid crystal display panel 12 and then refracted by the Fresnel lens 11 to enter the eye of the observer 14. When an angle 15 is θ5, 16 θ4, 17 θ3, 18θ2, and 19 θ1 (angle to a line perpendicular to the panel), equations (1)W(4) hold, where ψ is the saw-tooth angle as shown in a figure. When the Fresnel lens 27 is so designed that only light incident at a constant angle 20 of incidence enters the eye 23 of the observer over the entire surface of the display surface, the saw-tooth angle ψ at a point 2 is only set to about 37.8° so that θ5(20)=30° and θ1(22)=10°.