Liquid crystal display apparatus

• US 5,042,921 A
• Filed: 10/23/1989
• Issued: 08/27/1991
• Est. Priority Date: 10/25/1988
• Status: Expired due to Term

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Umeda, Osamu, Ogawa, Masahiro, Sato, Makoto, Nakakusu, Tohru
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US07/426,871
• Time in Patent Office: 673 Days
• Field of Search: 350/345, 350/331 R, 350/338, 350/337, 350/334, 353/122, 353/38, 353/69
• US Class Current: 349/9
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

In order to effectively use light from a light source, the light from the light source is split into P-polarized light and S-polarized light by a splitter or the like. The split P-polarized light is directly incident on a liquid crystal display apparatus for displaying an image by using P-polarized light. The split S-polarized light is optically rotated by a wavelength plate or the like and converted into P-polarized light. This P-polarized light is also incident on the liquid crystal display apparatus. The liquid crystal display apparatus effectively utilizes the light from the light source and displays an image with high luminance.

Claims

1. A liquid crystal display apparatus, comprising:

a first liquid crystal panel;

a second liquid crystal panel;

a light source;

a projecting lens;

splitting means for splitting light emitted from said light source into two light beams; and

optical means having transmission surfaces and reflection surfaces, for guiding the light beams from said splitting means to said projecting lens, said optical means including means for causing one of the light beams to be incident upon said projecting lens through substantially only said transmission surfaces and said first liquid crystal display panel, and means for causing other light beam to be incident upon said projecting lens through substantially only said reflection surfaces and said second liquid crystal display panel.

2. An apparatus according to claim 1 wherein said splitting means splits the light emitted from said light source into S-polarized light and P-polarized light.

3. An apparatus according to claim 1 wherein one of said two light beams, which passes through only said transmission surfaces, is P-polarized light, and other light beam, which passes through only said reflection surfaces, is S-polarized light.

4. An apparatus according to claim 1, wherein said first liquid crystal display panel displays an image of one of three primary colors, and said second liquid crystal display panel displays an image of other two colors.

5. A liquid crystal display apparatus, comprising:

a light source;

a projecting lens;

a first liquid crystal display means, opposite to said light source, for displaying an image;

a polarizing beam splitter arranged between said light source and said first liquid crystal display means, for splitting light emitted from said light source into P-polarized light and S-polarized light and for causing the P-polarized light to be incident upon said first liquid crystal display means and the S-polarized light to be reflected to the side of said polarizing beam splitter;

image synthesizing means arranged between said first liquid crystal display means and said projecting lens, for synthesizing the P-polarized light entered through said first liquid crystal display means and the S-polarized light entered from the side of said image synthesizing means, and for emitting the synthesized light to said projecting lens;

two mirror means arranged between the side of said polarizing beam splitter and the side of said image synthesizing means, for reflecting the S-polarized light reflected by said polarizing beam splitter and for further reflecting the reflected S-polarized light to form a light path through which the S-polarized light is incident upon said image synthesizing means; and

second liquid crystal display means arranged in said light path for displaying an image.

6. An apparatus according to claim 5, wherein said first liquid crystal display means displays an image of at least one of three primary colors, and said second liquid crystal display means displays an image of at least one of other two colors.

7. A liquid crystal display apparatus, comprising:

liquid crystal display means for displaying an image;

a light source;

a half mirror for splitting light emitted from said light source into transmission light and reflection light;

splitter means for splitting the light transmitted through said half mirror into two light beams; and

optical means for causing one of the light beams obtained by said splitter means to be incident upon said liquid crystal display means and the other light beam to be incident upon said liquid crystal display means through said half mirror, and for causing the light reflected by said half mirror to be incident upon said liquid crystal display means.

8. An apparatus according to claim 7, wherein said splitter means includes means for splitting the light emitted from said light source into S-polarized light and P-polarized light.

9. An apparatus according to claim 7, wherein:

said splitter means includes means for splitting the light emitted from said light source into S-polarized light and P-polarized light; and

said optical means includes means for causing the P-polarized light to be directly incident upon said liquid crystal display means.

10. An apparatus according to claim 7, wherein:

said splitter means includes means for splitting the light emitted from said light source into S-polarized light and P-polarized light; and

said optical means includes means for causing the P-polarized light to be directly incident upon said liquid crystal display means; and

wherein said apparatus further comprises converting means for converting the S-polarized light into P-polarized light.

11. An apparatus according to claim 7, wherein said optical means includes a plurality of mirrors.

12. An apparatus according to claim 7, wherein said optical means includes means for causing the light split by said splitting means and transmitted through said half mirror to be incident upon said liquid crystal display means through said splitter means again.

13. A liquid crystal display apparatus for causing light emitted from a light source to be incident upon a liquid crystal display panel and displaying an image on the liquid crystal display panel, comprising:

a polarizing beam splitter arranged between said light source and said liquid crystal display panel, for splitting the light emitted from said light source into P-polarized light and S-polarized light and to transmit the P-polarized light in an incident direction of said liquid crystal display panel and to reflect the S-polarized light;

an optical rotatory means arranged for converting the S-polarized light reflected by said polarizing beam splitter into P-polarized light;

a half mirror arranged between said polarizing beam splitter and said light source;

a first mirror arranged in a reflection direction of said half mirror;

a second mirror arranged opposite to said optical rotatory means, with said polarizing beam splitter interposed therebetween;

a third mirror for reflecting the light which is converted into the P-polarized light by said optical rotatory means in a direction of said light source; and

a fourth mirror for reflecting the light reflected by said third mirror in a direction of said half mirror.

14. A liquid crystal display apparatus, comprising:

a light source having a reflector;

liquid crystal display means for displaying an image;

splitter means arranged between said light sources and said liquid crystal display means, for splitting light emitted from said light source into P-polarized light and S-polarized light and to transmit the P-polarized light and reflect the S-polarized light in a direction of said light source; and

optical rotatory means arranged between said splitter means and said light source, for optically rotating the transmitted light approximately 45 degrees.

15. A liquid crystal display apparatus, comprising:

a light source having a reflector;

a liquid crystal display means for displaying an image; and

optical means arranged between said light source and said liquid crystal display means, for slitting light emitted from said light source into two light beams, one of said light beams being transmitted and incident upon said liquid crystal display means, and other light beam being reflected by said reflector in a direction of said light source and the reflected light beam being incident upon said liquid crystal display means.

16. An apparatus according to claim 15, further comprising optical rotary means arranged between said optical means and said light source, for optically rotating the transmitted light beam.

17. A liquid crystal display apparatus, comprising:

a light source;

splitter means for splitting the light emitted from said light source into S-polarized light and P-polarized light;

first liquid crystal display means irradiated with the S-polarized light;

second liquid crystal display means irradiated with the P-polarized light; and

means for synthesizing an image displayed on said first liquid crystal display means and an image displayed on said second liquid crystal display means;

said first and second liquid crystal display means each including three liquid crystal display panels for displaying images of three primary colors.

18. A liquid crystal display apparatus, comprising:

a light source;

splitter means for splitting light emitted from said light source into two light beams;

first liquid crystal display means irradiated with one of said two light beams;

second liquid crystal display means irradiated with the other of said two light beams;

means for synthesizing an image displayed on said first liquid crystal display means and an image displayed on said second liquid crystal display means;

a drive circuit board connected to said first and second liquid crystal display means; and

a drive circuit arranged on said drive circuit board, for driving said first and second liquid crystal display means.

19. An apparatus according to claim 18, wherein said splitter means includes means for splitting the light emitted from said light-source into S-polarized light and P-polarized light.

20. An apparatus according to claim 18, wherein:

said splitter means includes means for splitting the light emitted from said light source into S-polarized light and P-polarized light; and

said apparatus further comprises optical rotatory means arranged for optically rotating one of the S-polarized light and P-polarized light.

21. A liquid crystal display apparatus, comprising:

a light source;

reduction means for reducing a cross section of a region through which light passes from said light source;

an optical member for converting the light emitted from said reduction means into parallel light;

splitter means for splitting the parallel light into P-polarized light and S-polarized light;

optical rotatory means arranged for optically rotating a polarization direction of one of the P-polarized light and S-polarized light by π

/2 radians; and

synthesizing means for synthesizing the P-polarized light and S-polarized light.

22. A light source apparatus for use in a projection-type liquid crystal display apparatus, comprising:

a light source;

means for splitting light emitted from said light source into P-polarized light and S-polarized light, and for rotating a polarization direction of one of the P-polarized light and S-polarized light so as to coincide with a polarization direction of other polarized light; and

an optical member for synthesizing the P-polarized light and S-polarized light whose polarization directions coincide with each other, and for emitting a beam of parallel light rays.