Other

Akihiro Horibe

Tsuyoshi Ishikawa

Yasuhiro Koike

Eizaburo Higuchi

A set of light guide blocks B L,&tilde;B L,provide a tandem arrangement. The light guide block B L,is supplied with light from a primary light source L,. The other primary light sources L,, L,are arranged in recesses formed around distal portions of the light guide blocks B L,, B L,, supplying the light guide blocks B L,, B L,with primary light, respectively. Overlap of mutually neighboring light guide blocks gives tang-shaped overlapping portions,as well as overlapping bands,, thereby avoiding electrodes at both ends of the primary light sources L,, L,from causing short of brightness. The light guide blocks B L,&tilde;B L,may be in the form of unified single guide plate. Primary light sources L,&tilde;L,may have a shape such that electrode sections of both ends are curved. A compact surface light source device with a large emission area is provided.

Tandem lighting panel

A light source device outputs illumination light with highly uniform tint. The light source device is comprises a scattering guide provided with scattering power inside, a light supplier to supply light to an end face portion of the scattering guide. Light is introduced into the scattering guide plate to be followed by emission from an emission face of the scattering guide. Scattering efficiency is intentionally balanced in a long wavelength region and in a short wavelength region so that regions near the end face and far from the end face are approximately equal in color temperature of output light. Relation between Q(R), efficiency in a long wavelength region, and Q(B), scattering efficiency in a short wavelength region, are designed so that k&equals;Q(B)/Q(R) falls within a range 0.75&lE;k&lE;1.25.

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Yamato, Japan

Akihiro Horibe