Patent ID: 7614775

Claim:
A transparent light guide member comprising: a first light guide unit in a form of a transparent plate having a rectangular light emitting plane and a parallel groove formed on a rear surface located opposite from the rectangular light emitting plane and parallel to one side of the rectangular light emitting plane; and a second light guide unit, which is transparent, having a columnar external shape to be accommodated in the parallel groove and containing light-scattering particles; wherein Φ·L G ·N p ·K C is not smaller than 1.1 and not greater than 8.2, and K C , a compensation coefficient, is not smaller than 0.005 and not greater than 0.1, where Φ is a scattering cross section of the particles, L G a length of the second light guide unit in a direction in which light propagates, N p a particle density, and K C the compensation coefficient.