Surface illuminator

• US 5,377,083 A
• Filed: 06/16/1993
• Issued: 12/27/1994
• Est. Priority Date: 10/16/1992
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Tada, Masahiko
• Primary Examiner(s): Cole, Richard R.
• Application Number:
  US08/077,061
• Time in Patent Office: 559 Days
• Field of Search: 362/31, 362/26, 362/327, 362/326
• US Class Current: 362/613
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0026 Wavelength selective element, sheet or layer, e.g. filter or grating
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G09F 13/0422 Reflectors
• CPC Class Codes: G09F 13/14 Arrangements of reflectors therein
• CPC Class Codes: G09F 2013/145 curved reflectors

Abstract

A surface illuminator provided with a light guide plate having circular end faces which surround light sources, the light guide plate being long in a direction in which the light sources are high in luminance and having a back which is inclined so as to be smaller in plate thickness gradually as the distance from the light sources becomes longer, and also provided with a reflection frame, the reflection frame having end-face reflective portions which cover the portions of the light guide plate near the light sources and also having inclined reflective portions which are contiguous to the end-face reflective portions and which are inclined approximately 45° in longitudinal and thickness directions of the light guide plate at positions spaced apart from the light sources. By this construction, the intensity of radiation light is rendered uniform throughout the whole radiation surface.

Claims

1. A directional light guide, comprising:

a reflector, symmetric about an axis;

a light source emitting light rays, lying on the axis, the axis defining a first direction from the reflector to the light source;

a solid transmission medium, including a surface, in conjunction with said reflector, surrounds said light source, said surface formed so as to bend light rays toward the first direction if the light rays are not travelling in the first direction plus or minus ninety degrees, when the light rays enter the transmission medium.

3. A surface illuminator comprising:

a plurality of light sources having strong and weak portions in luminance distribution;

a light guide plate being long in a direction in which said light sources are high in luminance and having a back which is inclined so as to be smaller in plate thickness gradually as the distance from the light sources becomes longer; and

a reflection frame having end-face reflective portions which cover the portions of said light guide plate close to said light sources and also having inclined reflection portions which are contiguous to said end-face reflective portions and which are inclined approximately 45°

in longitudinal and thickness directions of the light guide plate an positions spaced apart from said light sources;

said light guide plate including,

an end face surface, which, in conjunction with the reflection frame, encircles each light source of said plurality of light sources; and

the end face surface adjacent to each of said plurality of light sources being formed in the shape of a partial cylinder for a part of the end face surface below the center of a light source and being formed in the shape of two planes tangentially extending from the partial cylinder to the reflection frame for a part of the end face surface above the center of the light source so as to tend to bend light away from the reflection frame when light enters the light guide plate.

4. The surface illuminator of claim 3, wherein each end face surface adjacent to each of said plurality of said light sources is formed in the shape of a partial with the center of the light source lying on the axis of the cylinder.

5. The surface illuminator of claim 3, wherein

each end face surface adjacent to each of said plurality of light sources is formed in the shape of two parallel planes tangentially extending from the partial cylinder to the reflection frame.

6. An illuminator comprising:

at least one light source;

a reflection surface, disposed above said at least one light source;

a solid light transmission medium, having an end face, and for each light source of the at least one light source, the end face having a portion which, in conjunction with said reflection surface, surround each of the at least one light source;

wherein

each portion having a cross-section of a partial circle for a part of the portion below a center of the light source and straight lines tangentially connecting ends of the partial circle to the reflection surface for a part of the portion above the center of the light source.

7. The illuminator of claim 6, wherein

each portion, has a cross-section of a partial circle having the center of the light source as a center.

8. The illuminator of claim 6, wherein

each portion has a cross-section of parallel lines tangentially connecting the ends of the partial circle to the reflection surface.

9. The illuminator of claim 8, wherein

each portion, has a cross-section of a partial circle having the center of the light source as a center.

10. The illuminator of claim 9, wherein

said solid light transmission medium has a width which diminishes as a function of the distance from the reflection surface.

11. The illuminator of claim 10, wherein

said reflection surface includes multiple planar reflection surfaces joined at an angle.

12. The illuminator of claim 11, wherein

said multiple planar reflection surfaces are joined at approximately forty-five degrees.

13. The illuminator of claim 12, wherein

each of said at least one light source includes a filament which substantially lies in a vertical plane.

14. A directional light guide, comprising

a light source emitting light rays in many directions;

a reflector disposed behind the light source, a majority of said reflector lying in a plane;

a solid light transmission medium including an end face, which, in conjunction with said reflector, surrounds said light source, said end face formed so as to refract a light ray having a direction towards the plane away from the plane, with respect to the original direction of the light ray, upon the light ray entering said transmission medium.

2. The light guide of claim 14, wherein

said surface is formed so as not to bend light rays if the light rays are travelling in the first direction plus or minus ninety degrees.

15. The directional light guide of claim 14, wherein

said end face is formed so as to not bend a light ray having a direction away from the plane, upon the light ray entering said transmission medium.