Reflective diffraction grating for use in display devices

• US 6,351,334 B1
• Filed: 10/10/2000
• Issued: 02/26/2002
• Est. Priority Date: 10/10/2000
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Chen, Wen-Jong, Lee, Chih-Kung, Kuo, Hui-Lung, Hsieh, Pao-Ju
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Juba, Jr., John
• Application Number:
  US09/688,374
• Time in Patent Office: 504 Days
• Field of Search: 359/566, 359/567, 359/568, 359/569, 359/570, 359/571, 359/572, 359/576, 359/581, 359/618, 359/619, 359/627, 359/628, 359/629, 359/634, 359/639, 359/615, 349/61, 349/95, 349/104, 349/105, 349/62, 349/113, 349/114
• US Class Current: 359/571
• CPC Class Codes: G02B 5/1861 Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 2201/305 diffraction grating
• CPC Class Codes: G02F 2203/34 Colour display without the use of colour mosaic filters

Abstract

A reflective-type diffraction grating structure for use in color display devices such as liquid crystal displays (LCDs). It contains: (1) a plurality of micro-lenses each having a smooth top surface and a blazed zig-zag-shaped grating surface at the bottom; (2) an optical coating formed below the zig-zag-shaped grating surface; and (3) a reflective member formed below the optical coating. With the cooperative actions of the zig-zag-shaped grating surface, the optical coating layer, and the reflective member, an incident light, when reflected, is separated into repeated sequences of red, green, and blue color components and a black matrix segregating the red, green, and blue color components. A sequence of micro-light valves are placed in the path of the reflected incident light to block the undesired color components. The reflective-type diffraction grating structure dispenses with the need for the various layers of color filters. As a result, it improves the brightness of the image and reduces power consumption, as well as reducing the manufacturing cost.

Claims

1. A reflective-type diffraction grating structure comprising:

(1) a plurality of micro-lenses each having a zig-zag-shaped grating surface in a bottom of said micro-lenses;

(2) an optical coating formed on said zig-zag-shaped grating surface; and

(3) a reflective member formed below said optical coating;

(4) wherein said optical coating, said zig-zag shaped grating surface, and said reflective member cooperatively cause an incident light to form a series of red, green, and blue color components at predefined positions, and said red, green, and blue color components are respectively segregated by black shadings.

2. The reflective-type diffraction grating structure according to claim 1 wherein said optical coating also has a zig-zag shaped bottom surface matching said zig-zag shaped grating surface of said micro-lenses.

3. The reflective-type diffraction grating structure according to claim 2 wherein said reflective member has a zig-zag shaped surface matching said zig-zag shaped grating surface of said optical coating.

4. The reflective-type diffraction grating structure according to claim 1 wherein said reflective member comprises:

(a) a flat transparent substrate formed below said optical coating in a spaced apart manner;

(b) a transparent material filled between said optical coating and said flat substrate, said transparent material having a different refraction index than both said substrate and said micro-lenses; and

(c) a reflective coating formed on a bottom of said flat substrate.

5. The reflective-type diffraction grating structure according to claim 1 which further comprises an external optical coating formed on a top surface of said micro-lenses.

6. The reflective-type diffraction grating structure according to claim 1, wherein said zig-zag-shaped grating surface has an angle of about 90 degrees.

7. The reflective-type diffraction grating structure according to claim 1 wherein said optical coating comprises a plurality of alternating layers of SiO₂ and ZrO₂.

8. A liquid crystal display (LCD) containing a liquid crystal, at least one ITO layer and a reflective-type diffraction grating structure, wherein said reflective-type diffraction grating structure comprises:

(a) a plurality of micro-lenses each having a zig-zag-shaped grating surface in a bottom of said micro-lenses;

(b) an optical coating formed on said zig-zag-shaped grating surface; and

(c) a reflective member formed below said optical coating;

(d) wherein said optical coating, said zig-zag shaped grating surface, and said reflective member cooperatively cause an incident light to form a series of red, green, and blue color components at predefined positions, and said red, green, and blue color components are respectively segregated by black shadings.

9. The liquid crystal display according to claim 8 wherein said optical coating also has a zig-zag shaped bottom surface matching said zig-zag shaped grating surface of said micro-lenses.

10. The liquid crystal display according to claim 8 wherein said reflective member has a zig-zag-shaped surface matching said zig-zag-shaped grating surface of said optical coating.

11. The liquid crystal display according to claim 8 wherein said reflective member comprises:

(a) a flat transparent substrate formed below said optical coating in a spaced apart manner;

(b) a transparent material filled between said optical coating and said flat substrate, said transparent material having a different refraction index than either said substrate or said micro-lenses; and

(c) a reflective coating formed on a bottom of said flat substrate.

12. The liquid crystal display according to claim 8 wherein said reflective-type diffraction grating structure further comprises an external optical coating formed on an outer surface of said micro-lenses.

13. The liquid crystal display according to claim 8, wherein said zig-zag-shaped grating surface has an angle of about 90 degrees.

14. The liquid crystal display according to claim 8 wherein said optical coating comprises a plurality of alternating layers of SiO₂ and ZrO₂.