Abstract: A thin schaukasten which is composed of a diffusive transparent plate, a light homogenizing member, a fluorescent lamp and a reflection member and in which the light homogenizing member has a reflection pattern formed on a transparent support media to provide a distribution of transmission for preventing non-uniform luminous intensity on one surface of the diffusive transparent plate and the reflection member is disposed in such a manner as to reduce non-uniformity in luminous intensity on one surface of the light homogenizing member. A lighting circuit for the fluorescent lamp includes a frequency converter for preventing flicker when the fluorescent lamp is lit, and the lighting circuit is used in common to a plurality of fluorescent lamps.