Liquid crystal display unit

Claim 1

A liquid crystal display unit for displaying characters and/or images comprising: a liquid crystal display panel including a liquid crystal interposed between first and second transparent plates, a first polarizing plate disposed on the upper surface of said first transparent plate, and a second polarizing plate disposed on the rear surface of said second transparent plate; a substrate carrying an electric circuit for driving said liquid crystal display panel; means for interconnecting said electric circuit and said liquid crystal display panel; a planar light source disposed between said liquid crystal display panel and said substrate and comprising two linear fluorescent lamps and a light guiding member, said light guiding member comprising a light guiding plate extending substantially in parallel with said liquid crystal display panel and disposed substantially in a first plane, said linear fluorescent lamps being disposed at opposite side surfaces of said light guiding plate and extending substantially in parallel to each other and disposed in said first plane, said light guiding plate including means for controlling light coupling so as to direct light substantially orthogonal to said first plane direction and toward said liquid crystal display panel; said light guiding plate having opposite upper and lower surfaces, said upper surface facing said liquid crystal display panel, said means for controlling light coupling from the light guiding plate comprising a concave surface portion on each of the upper and lower surfaces of said light guiding plate to enhance uniformity of brightness; a casing for containing said fluorescent lamps and light guiding member and including a reflecting plate for efficiently and uniformly utilizing the light from the fluorescent lamps; said casing reflecting plate extending under said light guiding plate and having a convex surface portion disposed adjacent to and in symmetric alignment with the concave surface portion of said lower surface of said means for controlling light coupling, and end walls disposed closely adjacent respective linear fluorescent lamps for reflecting light therefrom; wherein said casing member and said planar light source contained therein are disposed between said liquid crystal display panel and said substrate and are detachably mounted to the rear surface of said liquid crystal display panel, thereby said planar light source illuminates said liquid crystal display panel with uniform intensity from behind.