Front light, reflective type of display, and light controlling method

• US 7,163,330 B2
• Filed: 05/11/2004
• Issued: 01/16/2007
• Est. Priority Date: 05/15/2003
• Status: Expired due to Fees

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Aoyama, Shigeru, Matsushita, Motohiko, Funamoto, Akihiro, Ohhira, Makoto, Matsui, Yuki
• Primary Examiner(s): Luebke; Renee
• Assistant Examiner(s): MAY, ROBERT J
• Application Number:
  US10/843,213
• Publication Number:
  US 20050002175A1
• Time in Patent Office: 980 Days
• Field of Search: 362/561, 362/603, 349/63, 349/65
• US Class Current: 362/603
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• 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
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02F 1/133616 Front illuminating devices

Abstract

According to a front light comprising an optical waveguide 25 and a light source 24 arranged on the side of the optical waveguide 25, the optical waveguide 25 comprises a light input surface and light emission surface 28, and a plurality of deflection patterns 26 are formed on the surface opposed to the light emission surface 28. Light from the light source 24 is input from the light input surface of the optical waveguide 25 and propagated in the optical waveguide 25. The light totally reflected by the deflection patterns 26 among the light propagated in the optical waveguide 25 is emitted from the light emission surface 28 in the direction oblique to the normal direction of the light emission surface 28. The light is emitted from the light emission surface 28 so as to be aligned in one direction regardless of its position.

Claims

1. A front light comprising:

an optical waveguide having a first surface and a second surface facing the first surface; and

a point light source arranged to emit light into the optical waveguide,

wherein a plurality of patterns comprising inclination surfaces for deflecting the light are provided on the first surface,

wherein an angle formed by a direction connecting the point light source to an inclination surface of one of the patterns and a normal line of the inclination surface of the one of the patterns is selected depending on the direction connecting the point light source to the inclination surface of the one of the patterns, and

wherein normal lines of the inclination surfaces of the patterns on a circumference centering around the point light source are converged on one point existing at a position different from that of the point light source when viewed from a direction vertical to the second surface of the optical waveguide.

2. The front light according to claim 1, wherein a longitudinal direction of at least one of the patterns on the circumference centering around the point light source is substantially parallel to a tangential direction of an ellipse, a focal point of which coincides with the point light source, at an intersection of a line, which connects the point light source to the at least one of the patterns, with the ellipse.

3. The front light according to claim 1, wherein the patterns on the circumference centering around the point light source are configured such that an angle formed by each of the inclination surfaces of the patterns and the first surface increases in accordance with an increase in an angle formed by the direction connecting the point, where the normal lines of the inclination surfaces are converged, to the point light source and the direction connecting the point light source to each of the inclination surfaces.

4. The front light according to claim 1, wherein the first surface is positioned at an upper portion of the optical waveguide in a vertical direction of an object illuminated with the light passed through the second surface.

5. The front light according to claim 1, wherein the point light source is arranged in the vicinity of a corner of an effective emission region of the optical waveguide.

6. A reflective type display comprising a front light according to claim 1, and a reflective type display panel arranged on the second surface side of the front light and having a reflection surface for reflecting the light emitted from the second surface.

7. A reflective type display comprising a front light according to claim 1, and a reflective type display panel arranged on the second surface side of the front light and having a reflection surface for reflecting the light emitted from the second surface, wherein the reflection surface reflects the light input from a direction oblique to a normal line of the second surface in a direction vertical to the second surface.

8. A front light comprising:

an optical waveguide having a first surface and a second surface facing the first surface; and

a point light source arranged to emit light into the optical waveguide,

wherein a plurality of patterns comprising inclination surfaces for deflecting the light are provided on the first surface,

wherein an angle fonned by a direction connecting the point light source to an inclination surface of one of the patterns and a normal line of the inclination surface of the one of the patterns is selected depending on the direction connecting the point light source to the inclination surface of the one of the patterns, and

wherein at least one of the patterns is arranged on a circumference of an ellipse, a focal point which coincides with the point light source, in such a manner that a longitudinal direction of the at least one of the patterns is substantially parallel to a tangential direction of the ellipse when viewed from a direction vertical to the second surface of the optical waveguide.

9. The front light according to claim 8, wherein the first surface is positioned at an upper portion of the optical waveguide in a vertical direction of an object illuminated with the light passed through the second surface.

10. The front light according to claim 8, wherein the point light source is arranged in vicinity of a corner of an effective emission region of the optical waveguide.

11. A reflective type display comprising a front light according to claim 8, and a reflective type display panel disposed on the second surface side of the front light and having a reflection surface for reflecting the light emitted from the second surface.

12. A reflective type display comprising a front light according to claim 8, and a reflective type display panel arranged on a second surface side of the front light and having a reflection surface for reflecting light emitted from the second surface, wherein the reflection surface reflects the light input from a direction oblique to a normal line of the second surface in a direction vertical to the second surface.

13. A front light comprising:

an optical waveguide having a first surface and a second surface facing the first surface; and

a point light source arranged to emit light into the optical waveguide,

wherein a plurality of patterns comprising inclination surfaces for deflecting the light are provided on the first surface,

wherein an angle formed by a direction connecting the point light source to an inclination surface of one of the patterns and a normal line of the inclination surface of the one of the patterns is selected depending on the direction connecting the point light source to the inclination surface of the one of the patterns, and

wherein normal lines of the inclination surfaces of the patterns on a circumference centering around the point light source are converged on one point that does not coincide with the point light source, and wherein an angle formed by each of the normal lines and the first surface varies depending on a position of each of the patterns.

14. The front light according to claim 13, wherein the first surface is positioned at an upper portion of the optical waveguide in a vertical direction of an object illuminated with the light passed through the second surface.

15. The front light according to claim 13, wherein the point light source is arranged in vicinity of a corner of an effective emission region of the optical waveguide.

16. A reflective type display comprising a front light according to claim 13, and a reflective type display panel disposed on the second surface side of the front light and having a reflection surface for reflecting the light emitted from the second surface.

17. A reflective type display comprising a front light according to claim 13, and a reflective type display panel arranged on a second surface side of the front light and having a reflection surface for reflecting light emitted from the second surface, wherein the reflection surface reflects the light input from a direction oblique to a normal line of the second surface in a direction vertical to the second surface.