LCD apparatus

• US 8,149,341 B2
• Filed: 04/14/2008
• Issued: 04/03/2012
• Est. Priority Date: 04/16/2007
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Furuta, Yoshihiro
• Primary Examiner(s): WONG, ERIC K
• Application Number:
  US12/102,364
• Publication Number:
  US 20080252801A1
• Time in Patent Office: 1,450 Days
• Field of Search: 349 5- 9
• US Class Current: 349/9
• CPC Class Codes: G02F 1/133531 characterised by the arrangement of polariser or analyser axes
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

An LCD panel (214) is provided on the light-incidence side thereof with a reflective polarizer. An optical compensator (213) is provided between a reflective polarizer (211) and the LCD panel (214) to reduce birefringence that takes place in the liquid crystal of the LCD panel (214). A further absorptive polarizer (212) is provided between a reflective polarizer (211) and the optical compensator (213). The reflective polarizer (211) and the absorptive polarizer (212) are arranged so that their transmission axes coincide to each other. Thus, the absorptive polarizer and optical compensator together cooperate to compensate for the deficient polarization degree of the reflective polarizer to improve the contrast of a displayed image. The absorptive polarizer absorbs unwanted catoptric light. The optical compensator removes irregularity in the blackness of the LCD panel that would otherwise appear in the black display screen. Thus, degradation of picture quality of a displayed image caused by unwanted catoptric light undergoing multiple reflections in the LCD panel can be eliminated by the absorptive polarizer in collaboration with the optical compensator.

Claims

1. An LCD apparatus, comprising:

a plurality of LCD panels adapted to modulate irradiated light by picture signals;

a projection lens for projecting said light modulated by said LCD panels; and

a light source for emitting light to irradiate said LCD panels wherein each of said LCD panels includes,

a reflective polarizer disposed on each light-incidence side of each one of said LCD panels;

an optical compensator for reducing the birefringence that takes place in the liquid crystal of the LCD panel, said optical compensator being disposed between said reflective polarizer and the LCD panel associated therewith; and

an absorptive polarizer arranged between said reflective polarizer and optical compensator such that the light transmission axes of said reflective polarizer and absorptive polarizer coincide with each other, said absorptive polarizer having a lower degree of polarization than said reflective polarizer.

2. The LCD apparatus according to claim 1, wherein said reflective polarizer consists of inorganic materials.

3. The LCD apparatus according to claim 1, wherein said reflective polarizer and absorptive polarizer are respectively rotatable in planes perpendicular to the common optical axis thereof.

4. The LCD apparatus according to claim 1, wherein either one of said reflective polarizer or absorptive polarizer is rotatable in the plane perpendicular to the optical axis thereof.

5. The LCD apparatus according to claim 1, wherein said optical compensator is rotatable in a plane perpendicular to the optical axis thereof.

6. The LCD apparatus according to claim 3, wherein said optical compensator is rotatable in a plane perpendicular to the optical axis thereof.

7. The LCD apparatus according to claim 4, wherein said optical compensator is rotatable in a plane perpendicular to the optical axis thereof.