Liquid crystal display device having fluorescent tube illuminator

• US 4,664,481 A
• Filed: 08/07/1986
• Issued: 05/12/1987
• Est. Priority Date: 08/09/1985
• Status: Expired due to Fees

• Current Assignee: Hitachi Automotive Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Original Assignee: Hitachi Automotive Engineering Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Ito, Hiroshi, Kugo, Masaru
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Gallivan, Richard F.
• Application Number:
  US06/894,046
• Time in Patent Office: 278 Days
• Field of Search: 350/345
• US Class Current: 349/62
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: H01J 61/35 provided with coatings on the walls thereof; Selection of materials for the coatings using coloured coatings H01J61/40; using luminescent coatings H01J61/42

Abstract

A reflecting plate is disposed in such a manner as to surround a fluorescent tube in a U shape in its axial direction. A light diffusion-transmission plate is disposed in such a manner as to bridge over the open end portions of the U-shaped reflecting plate and to extend in the axial direction of the fluorescent tube. A liquid crystal display element is disposed on this light diffusion-transmission plate. In the liquid crystal display device having the construction described above, the present invention disposes shading means for increasing the quantity of light near the filament portions and limiting the quantity of light on the light emission surface inside the fluorescent tube.

Claims

1. In a liquid crystal display device consisting essentially of:

a fluorescent tube having a fluorescent material coated therein and an inert gas and a mercury vapor sealed therein and emitting light by discharge;

a reflecting plate dispoeed in such a manner as to surround said fluorescent tube in a U shape in an axial direction of said fluorescent tube;

a light diffusion-transmission plate disposed in such a manner as to bridge over the open end portion of said U-shaped reflecting plate and extend in the axial direction of said fluorescent tube; and

a liquid crystal element disposed on said light diffusion-transmission plate;

the improvement wherein shading means for increasing the quantity of light near filament portions and restricting the quantity of light of the light emission surface is disposed on said fluorescent tube.

2. The liquid crystal display device as defined in claim 1 wherein said shading means consists of a shade curtain disposed on the light emission surface of said fluorescent tube other than its filament portions and having a reflection function and a transmission function.

3. The liquid crystal display device as defined in claim 2 wherein said shade curtain is fixed tightly to the outer periphery of the light emission surface.

4. The liquid crystal display device as defined in claim 2 wherein said shade curtain is formed coarsely in such a fashion that the light transmission quantity becomes progressively greater towards both end portions of said fluorescent tube.

5. The liquid crystal display device as defined in claim 2 wherein said shade curtain is produced by vacuum-depositing reflecting members in a mesh or dot form on a light transmission film.