Reflection illumination device for object to be illuminated

• US 6,435,687 B1
• Filed: 03/01/2000
• Issued: 08/20/2002
• Est. Priority Date: 03/03/1999
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Fukiharu, Eiichi
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): TRUONG, BAO Q
• Application Number:
  US09/516,138
• Publication Number:
  US 20020080596A1
• Time in Patent Office: 902 Days
• Field of Search: 362/31, 362/27, 362/561, 362/26, 362/330, 362/339, 349/67, 349/62, 349/63-65, 359/49
• US Class Current: 362/609
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide

Abstract

A reflection illumination device includes a light guide, light sources, and a reflecting mirror. The light guide is placed in front of an object to be illuminated. The light sources are arranged around the light guide. The reflecting mirror is placed behind the object. One or a plurality of total reflection areas on which projections or recesses each having a triangular cross-section and serving to totally reflect light emitted from the light source toward the object are formed are arranged on the surface of the light guide. Each of the projections or recesses is constituted by an inclined surface inclined at a predetermined angle toward a reference portion positioned at a predetermined position on the light guide, and a vertical surface vertical to the light guide. The light sources and irradiation means for parallelly irradiating the total reflection areas with light from the light sources are arranged at edges of the light guide in correspondence with the total reflection areas.

Claims

1. A reflection illumination device comprising a light guide placed in front of an object to be illuminated, a light source arranged around said light guide, and a reflecting mirror placed behind the object,

wherein one or a plurality of total reflection areas on which adjacent projections or recesses each having a triangular cross-section and serving to totally reflect light emitted from said light source toward the object are formed and are arranged on a surface of said light guide,

each of the projections or recesses is constituted by an inclined surface inclined at a predetermined angle smaller than 90°

−

(β

+θ

₀) where β

is the irradiation direction of illumination light from the light source and θ

₀ is a critical angle of a material for said light guide, toward a reference portion positioned at a predetermined position on said light guide, and a vertical surface vertical to said light guide, and

said light source and irradiation means surrounding the light source except for the area illuminating the light guide for parallelly irradiating the total reflection area with light from said light source are arranged at an edge of said light guide in correspondence with the total reflection area.

2. A device according to claim 1, wherein the total reflection area comprises a plurality of total reflection areas arranged on two sides or around the reference portion.

3. A device according to claim 1, wherein the projection or recess is formed to have a circular shape, an elliptic shape, or a closed curved shape, and

said light source and said irradiation means are arranged at predetermined portions of the edge of said light guide.

4. A device according to claim 1, wherein the reference portion is positioned to the center of said light guide.

5. A device according to claim 1, wherein said irradiation means inclines an irradiation direction of illumination light at a predetermined angle with respect to said light guide to directly irradiate all the projections or recesses in the total reflection area with collimated light.

6. A device according to claim 1, further comprising a reflecting member surrounding a peripheral portion of said light guide.