Reflective display device and retro-reflector used therefor

• US 6,844,956 B2
• Filed: 06/30/2003
• Issued: 01/18/2005
• Est. Priority Date: 03/31/2000
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Ueki, Shun, Okamoto, Masayuki, Minoura, Kiyoshi, Mitsui, Seiichi, Tomikawa, Masahiko, Sako, Teiyu
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): HASAN, MOHAMMED A
• Application Number:
  US10/608,216
• Publication Number:
  US 20040085611A1
• Time in Patent Office: 568 Days
• Field of Search: 359/263, 359/245, 359/530
• US Class Current: 359/263
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605

Abstract

A reflective display device includes a switching layer, placed between substrates, for switching between a transmissive state for allowing transmission of incident light and a scattering state for scattering the incident light, and a retro-reflector for reflecting an incident ray from the liquid crystal layer so that an outgoing ray of the reflected light is parallel to the incident ray. A pitch of smallest unit structures of the retro-reflector is set to be larger than 0 mm and not more than 5 mm. The retro-reflector is preferably in a form of a corner cube array and has light absorbing surface portions at borders of the smallest unit structures. With this reflective display device, brightness of white state and contrast ratio can be improved.

Claims

1. A retro-reflector, comprising:

a plurality of adjoining retro-reflecting sections for reflecting incident light so that an outgoing ray of the reflected light is substantially parallel to the incident light,

wherein light absorbing surface portions for absorbing light are provided at borders of the retro-reflecting sections.

2. The retro-reflector as set forth in claim 1, wherein said light absorbing surface portions are provided in a standing direction with respect to a surface direction of the retro-reflecting section.

3. The retro-reflector as set forth in claim 1, wherein the retro-reflecting sections are in a form of a corner cube array, and the light absorbing surface portions are formed so that front end portions thereof make up a single plane with respect to an imaginary plane connecting respective vertices of the retro-reflecting sections.