Illumination device, electrooptical device having the illumination device as front light, and electronic equipment

• US 6,494,585 B1
• Filed: 11/08/2000
• Issued: 12/17/2002
• Est. Priority Date: 03/15/1999
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Wada, Hiroshi
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Ton, Anabel
• Application Number:
  US09/674,856
• Time in Patent Office: 769 Days
• Field of Search: 362/26, 362/31, 362/339, 362/327, 362/560, 385/146, 349/63
• US Class Current: 362/26
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0071 with elongated shape, e.g. tube

Abstract

The surface of a light guide plate is provided with face portions obliquely oriented. Since the face portions form leakage lights whose directional components are deviated from the principal viewing direction on the surface of the light guide plate, the orientation distribution of the leakage light differs from the conventional one, and the peak orientations of the leakage light are formed on both sides of the viewing direction. Moreover, the peak intensities on both sides significantly decrease.

Claims

1. An illumination device, comprising:

a light source; and

a light guide plate having an end face, a first surface and a second surface opposing the first surface, the light guide plate introducing light emitted from said light source from the end face and emitting the light from the first surface,

the second surface of said light guide plate having a reflective face section for reflecting the light from said light source toward said first surface or emitting the light from said second surface according to an incident angle of the light, said reflective face section including at least a first face and a second face, and an emitting direction of the light emitted from said first face differing from an emitting direction of the light emitted from said second face.

2. The illumination device according to claim 1, an angle formed by the emitting direction of light projected onto the second surface of said light guide plate and emitted from said first face and the emitting direction of light projected onto the second surface of said light guide plate and emitted from said second face being within 0°

and 180°

.

3. The illumination device according to claim 1, said first face and said second face being formed alternately and continuously.

4. The illumination device according to claim 1, said light guide plate being made of a substantially transparent material, and said reflective face section being formed of an inclined surface disposed at a predetermined angle with respect to a plane parallel to said first surface.

5. An electrooptical device, comprising:

an electrooptical element having an electrooptical layer disposed between a pair of substrates and a reflective film disposed on one side of said electrooptical layer; and

an illumination device placed on a viewer side of said electrooptical element, and including a light source and a light guide plate that introduces light emitted from said light source from an end face and principally emitting the light toward said electrooptical element,

said light guide plate having a viewer-side surface on the viewer side provided with a reflective face section for reflecting the light emitted from said light source toward said electrooptical element or emitting the light from said viewer-side surface according to an incident angle of the light, and a transmissive face section for allowing said electrooptical element to be visible therethrough from the viewer side, and

said reflective face section including a first face and second face, an emitting direction of the light emitted from said first face differing from an emitting direction of the light emitted from said second face.

6. The electrooptical device according to claim 5, an angle formed by the emitting direction of light projected onto the viewer-side surface of said light guide plate and emitted from said first face and the emitting direction of light projected onto the viewer-side surface of said light guide plate and emitted from said second face being within 0°

and 180°

.

7. The electrooptical device according to claim 5, said first face and said second face being formed alternately and continuously.

8. The electrooptical device according to claim 5, said light guide plate being made of a substantially transparent material and further having a back surface opposing the viewer-side surface, and said reflective face section being formed of an inclined surface disposed at a predetermined angle with respect to a plane parallel to said back surface.

9. An electronic equipment that comprises an electrooptical device as a display section, and an input device that supplies an image signal to said electrooptical device, said electrooptical device comprising:

an electrooptical element having an electrooptical layer disposed between a pair of substrates and a reflective film disposed on one side of said electrooptical layer; and

an illumination device placed on a viewer side of said electrooptical element, and including a light source and a light guide plate that introduces light emitted from said light source from an end face and principally emitting the light toward said electrooptical element,

said light guide plate having a viewer-side surface on the viewer side provided with a reflective face section for reflecting the light emitted from said light source toward said electrooptical element or emitting the light from said viewer-side surface according to an incident angle of the light, and a transmissive face section for allowing said electrooptical element to be visible therethrough from the viewer side, and

said reflective face section including a first face and second face, an emitting direction of the light emitted from said first face differing from an emitting direction of the light emitted from said second face.

10. The electronic equipment according to claim 9, an angle formed by the emitting direction of light projected onto the viewer-side surface of said light guide plate and emitted from said first face and the emitting direction of light projected onto the viewer-side surface of said light guide plate and emitted from said second face being within 0°

and 180°

.

11. The electronic equipment according to claim 9, said first face and said second face being formed alternately and continuously.

12. The electronic equipment according to claim 9, said light guide plate being made of a substantially transparent material and further having a back surface opposing the viewer-side surface, and said reflective face section being formed of an inclined surface disposed at a predetermined angle with respect to a plane parallel to said back surface.