| 摘要 |
PROBLEM TO BE SOLVED: To reduce luminance spots as much as possible to illuminate a character plate from a back with uniform light.SOLUTION: A light guide plate 10 having an arc shape in a front face view arranged between a front character plate and a diffuse reflection plate arranged on the back of the character plate includes: many arc-shaped grooves 11 that extend along the circumferential direction of the arc shape on a front 10A opposite to the character plate, and are formed at intervals in the radial direction of the arc shape; many radial projections 12 that radially extend along the radial direction of the arc shape on a back 10B opposite to the diffuse reflection plate, and are formed at intervals in the circumferential direction of the arc shape. The intervals in the radial projections are set so as to gradually become smaller as being away from a light incident end 18. |
