Flat light source device for illumination use

Abstract

An object of the invention is to provide a thin flat light source device for illumination use such as for a back-illumination of an LCD display etc. which is obtained by thinning a light-guiding plate even when it is illuminated by a multi-colored source. A rear surface of the light-guiding plate 1 having a planar front light-emitting surface 2 is worked by a tapered knurling method to form a light-diffusing surface 3. Two discharge tubes are disposed as light sources outside a side surface 4 of the light-guiding plate 1 in parallel to the light-emitting surface 2 as well as to the side surface 4 so that a virtual plane defined by both central axes of the two tubes intersects substantially perpedicularly the side surface 4. One of the discharge tubes located inside is a red neon tube 5 formed of a transparent glass while another of the discharge tubes located outside is a cold cathode fluorescent tube 6 which emits a desirable luminescent color except for the red. A reflecting plate 7 is disposed enclosing those discharge tubes.

Dependencies are inferred from the claim text.