| 摘要 |
Provided are a light guide plate realizing a high and uniformalized illumination brightness without reducing emission directivity, a surface light source device and an image display which employ the light guide plate. The light guide plate has an emission face provided with a great number of projection rows. Each projection row consists of a pair of slopes, a first slope (a slope far from an incidence end face) and a second slope (another slope near to the incidence end face). Angle thetaa is defined as an inclination angle of the first slope with respect to an imaginary plane perpendicular to a frontal direction. Inclination angle thetaa decreases gradually in first region L 1 on the emission face (or back face) according to an increasing distance from the incidence end face, then increasing gradually in second region L 2 according to an increasing distance from the incidence end face, Inclination angle thetaa at an incidence-end-face-side end of first region L 1 is greater that at a distal-end-face-side end of second region L 2 . Variation Deltathetaa in first region L 1 is greater that in second region L 2.
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