Discharge lamp and lighting apparatus and liquid crystal display apparatus using the charge lamp

• US 5,673,998 A
• Filed: 05/15/1995
• Issued: 10/07/1997
• Est. Priority Date: 06/07/1994
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Inoue, Naoto
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US08/440,714
• Time in Patent Office: 876 Days
• Field of Search: 362/260, 313/493, 313/634, 313/636
• US Class Current: 362/260
• CPC Class Codes: G02F 1/1336 Illuminating devices
• CPC Class Codes: H01J 61/025 Associated optical elements
• CPC Class Codes: H01J 61/302 characterised by the material of the vessel

Abstract

In a lamp main body in a discharge lamp provided in a lighting apparatus of an edge-lighting type which is used as a back-lighting section of a liquid crystal display apparatus, refractive indexes are distributed such that a light emitted from an inner space traveling in the lamp main body can be guided to a specific direction. In other words, the lamp main body is divided into a plurality of portions and the portions are formed such that refractive indexes become gradually smaller from a light converging side towards a back surface side which is opposite to the light converging side. With this arrangement, a discharge lamp, which is capable of emitting a light from a surface of the lamp main body to a specific direction, can be obtained. Moreover, when the discharge lamp is used, efficiency of utilization of a light is improved, thereby making it possible to obtain a lighting apparatus with high surface brightness and low power consumption. As a result, a liquid crystal display apparatus with high brightness and low power consumption can be obtained.

Claims

1. A discharge lamp, comprising:

a cylindrical lamp main body where a fluorescent material is coated on an inner circumferential surface of said lamp main body;

wherein an inner area of said lamp main body between the inner circumferential surface and an outer circumferential surface of said lamp main body has uneven refractive indexes so that light, which is emitted from the inner circumferential surface of the lamp main body and enters said inner areas so as to travel to the outer circumferential surface, is guided to a specified predetermined direction.

2. The discharge lamp as defined in claim 1, wherein said lamp main body is composed of a family of soda glass containing alkaline ion.

3. The discharge lamp as defined in claim 1, wherein said lamp main body is gradually divided into a plurality of portions by boundary lines on a lamp main body cross-sectional circle, said plurality of portions being formed such that the refractive indexes become gradually lower from a light converging side where light is converged towards a back surface which is opposite to the converging side.

4. The discharge lamp as defined in claim 3, wherein the boundary lines are parallel to a surface on which the light emitted from said lamp main body is irradiated.

5. The discharge lamp as defined in claim 3, wherein the boundary lines are curved lines which spread from an arbitrary point around an outer periphery of the converging side to the back surface side.

6. The discharge lamp as defined in claim 3, wherein the plurality of boundary lines are on a cross sectional circle of the lamp body, said cross sectional circle lying at right angles to a cylinder axis of the lamp body.

7. The discharge lamp as defined in claim 1, wherein said lamp main body is arranged such that the refractive indexes continuously become lower from a converging side towards a back surface of the lamp main body.

8. The discharge lamp as defined in claim 1, wherein said lamp main body is divided by boundary lines on a cross-sectional circle which crosses at right angles to a cylinder axis of the lamp main body into a portion with a low refractive index which occupies a greater area of the lamp main body and a portion with an extremely high refractive index with respect to the low refractive index which is positioned on a back surface side of the portion with a low refractive index.

9. The discharge lamp as defined in claim 8, wherein the portion with a high refractive index is further divided into a plurality of portions gradually, said plurality of portions being formed such that refractive indexes become higher from a converging side towards a back surface of the lamp main body.

10. The discharge lamp as defined in claim 9, wherein the boundary lines are parallel to a surface where a light emitted from said lamp main body is converged.

11. The discharge lamp as defined in claim 9, wherein the boundary lines are curved lines which spread from an arbitrary point around an outer periphery of the back surface to the converging side.

12. The discharge lamp as defined in claim 1, wherein said lamp main body is divided into a first portion, a second portion and a third portion, the first portion being gradually divided by boundary lines on a cross-sectional circle which crosses at right angles to a cylindrical axis of said lamp main body such that refractive indexes become lower from a converging side towards a back surface of said main body, the second portion provided on a back surface side of the first portion having a lower refractive index, the third portion positioned on a back surface side of the second portion having an extremely high refractive index with respect to the refractive index of the second portion.