Projector apparatus having three liquid crystal panels

• US 5,105,265 A
• Filed: 01/19/1989
• Issued: 04/14/1992
• Est. Priority Date: 01/25/1988
• Status: Expired due to Term

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Ogawa, Masahiro, Sato, Makoto
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Metjahic, Safet
• Application Number:
  US07/300,078
• Time in Patent Office: 1,181 Days
• Field of Search: 358/60, 358/61, 358/62, 358/63, 358/231, 358/230, 350/171, 350/172, 350/173, 350/174, 350/394, 350/397, 350/398, 350/331 R, 350/445, 350/452, 350/401, 350/402, 350/403, 353/31, 353/34
• US Class Current: 348/757
• 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

All of first to third liquid crystal panels have the same structure. A plurality of dichroic mirrors separate light from a light source into the three primary color (red, green, and blue) beams, and cause the red, green, and blue beams to be respectively incident on the first, second, and the third liquid crystal panels. A dichroic prism superposes the red, green, and blue beams which are respectively transmitted through the liquid crystal panels. A projection lens projects a full-color image beam formed by the dichroic prism. Correcting devices are respectively arranged to oppose the incident surfaces of the first to third liquid crystal panels, and cause the respective color beams separated by the dichroic mirrors to be incident as beams in which the intensities of light components oscillating in the same direction are high.

Claims

1. A liquid crystal projector, comprising:

first, second and third liquid crystal panels having the same structure;

a light source;

a plurality of dichroic mirrors for separating light from light source into three primary color beams,. including red, green, and blue beams, and for causing the red, green, and blue beams to be respectively incident on said first, second, and third liquid crystal panels;

a dichroic prism for superposing the red, green, and blue beams which are transmitted through said liquid crystal panels;

a projection lens for projecting a full-color image beam formed by said dichroic prism; and

correcting means including a plurality of mirror means, arranged in light paths between said light source and said first, second and third liquid crystal panels for causing the intensities of the three primary color beams including the red, green, and blue beams to be such that the intensities of light components of the beams oscillating in the same direction with respect to said first to third liquid crystal panels, are all relatively higher than that of light components of the beams oscillating in another direction which is perpendicular to said same direction.

2. A liquid crystal projector, comprising:

three liquid crystal panels having the same structure;

a light source;

optical means for separating a light beam from said light source into three primary light color beams including red, green, and blue beams, for mixing the three primary color beams by causing the three primary beams to be respectively transmitted through said liquid crystal panels, and for outputting a full-color image beam;

a projection lens for projecting the full-color image beam; and

correcting means including a plurality of mirror means, arranged in light paths between said light source and said three liquid crystal panels, for causing the intensities of the three primary color beams including the red, green, and blue beams to be such that the intensities of light components of the beams oscillating in the same direction with respect to said three liquid crystal panels, are all relatively higher than that of light components of the beams oscillating in another direction which is perpendicular to said same direction.

3. A projector according to claim 2, wherein said optical means equalizes the number of reflections of all three separated primary color beams, i.e., red, green, and blue beams and equalizes the number of transmissions of the three primary color beams, i.e., the red, green, and blue beams.

4. A liquid crystal projector, comprising:

three liquid crystal panels having the same structure;

a light source;

optical means for separating a light beam from said light source into three primary light color beams, including red, green, and blue beams, for mixing the three primary color beams by causing the three primary beams to be respectively transmitted through said liquid crystal panels, and for outputting a full-color image beam;

a projection lens for projecting the full-color image beam; and

correcting means including a plurality of mirror means, arranged in light paths between said light source and said three liquid crystal panels, for causing the intensities of the three primary color beams including the red, green, and blue beams to be such that the intensities of light components of the beams oscillating in the same direction with respect to said three liquid crystal panels, are all relatively higher than that of light components of the beams oscillating in another direction which is perpendicular to said same direction;

wherein said optical means equalizes optical path lengths of all three separated primary beams including the red, green, and blue beams, from said light source to said projection lens.

5. A liquid crystal projector comprising:

a light source for emitting three primary color beams including first, second, and third color beams;

a first dichroic mirror for transmitting the first color beam of the three primary color beams emitted from said light source, and reflecting the second and third color beams;

first mirror for reflecting the second and third color beams reflected by said first dichroic mirror in a direction parallel to and the same as the first color beam which is transmitted through said first dichroic mirror;

a second dichroic mirror for transmitting the second color beam of the beams reflected by said first mirror, and reflecting the third color beam in a direction parallel to and opposite to the second and third color beams reflected by said first dichroic mirror;

a second mirror for reflecting the first color beam transmitted through said first dichroic mirror in the same direction as that of the third color beam reflected by said second dichroic mirror;

a third mirror for reflecting the first color beam reflected by said second mirror in a direction parallel to and the same as the first color beam transmitted through said first dichroic mirror;

a fourth mirror for reflecting the first color beam reflected by said third mirror in a direction parallel to and opposite to the first color beam reflected by said second mirror;

a fifth mirror for reflecting the second color beam transmitted through said second dichroic mirror in a direction parallel to and the same as the third color beam reflected by said second dichroic mirror;

a sixth mirror for reflecting the third color beam reflected by said second dichroic mirror in the same direction as that of the first color beam transmitted through said first dichroic mirror;

first to third TN type liquid crystal panels, having the same pixel arrangement and the same liquid crystal alignment, for transmitting the first, second, and third color beams reflected by said fourth, fifth, and sixth mirrors;

a dichroic prism for superposing the first, second, and third color beams which are respectively transmitted through said first to third TN type liquid crystal panels and outputting a full-color image beam; and

a projection lens for projecting the full-color image output from said dichroic prism on an external screen.

6. A projector according to claim 5, wherein the respective beams are reflected by said first and second dichroic mirrors and said first, second, third, and fourth mirrors as beams in which intensities of light components oscillating in the same direction are high.

7. A liquid crystal projector, comprising:

a case;

a transmission type screen arranged on a front surface of said case; and

a projection unit arranged in said case, said projection unit including;

first, second and third liquid crystal panels having the same structure;

a light source;

a plurality of dichroic mirrors for separating light from said light source into three primary color beams including red, green, and blue beams, and for causing the red, green, and blue beams to be respectively incident on said first, second, and third liquid crystal panels;

a dichroic prism for superposing the red, green, and blue beams which are transmitted through said liquid crystal panels;

a projection lens for projecting a full-color image beam formed by said dichroic prism; and

correcting means including a plurality of mirror means, arranged in light paths between said light source and said three liquid crystal panels, for causing the intensities of the three primary color beams including the red, green, and blue beams to be such that the intensities of light components of the beams oscillating in the same direction with respect to said three liquid crystal panels, are all relatively higher than that of light components of the beams oscillating in another direction which is perpendicular to said same direction.

8. A projector according to claim 7, wherein a lenticular lens is formed on a surface of said transmission type screen, said lenticular lens comprising a plurality of stripe lens portions which are arranged to be parallel to each other.

9. A projector according to claim 7, further comprising optical means for causing a full-color image beam from said projection lens to be vertically incident on said transmission type screen.

10. A projector according to claim 9, wherein said optical means comprises a mirror.

11. A projector according to claim 10, wherein said mirror reflects as an incident beam a beam in which an intensity of a light component oscillating in the same direction as that of the incident beam is high.

12. A projector according to claim 8, wherein a longitudinal direction of lens portions of said transmission type screen is perpendicular to an oscillating direction of the full-color image beam from said projection lens.

13. A liquid crystal projector, comprising:

a case;

a transmission type screen arranged on a front surface of said case; and

a projection unit including first, second and third liquid crystal panels arranged in said case and having the same structure, a light source, a plurality of dichroic mirrors for separating light from said light source into three primary color beams including red, green, and blue beams, and for causing the red, green, and blue beams to be respectively incident on said first, second, and third liquid crystal panels,

a dichroic prism for superposing the red, green, and blue beams which are transmitted through said liquid crystal panels,

a projection lens for projecting a full-color image beam formed by said dichroic prism; and

optical means for causing the full-color image beam from said projection lens of said projection unit to be one in which the intensities of light components oscillating in the same direction are relatively higher than that of light components of the beams oscillating in another direction which is perpendicular to said same direction, and for causing the beam to be incident on said screen.

14. A projector according to claim 13, wherein said optical means comprises a plurality of mirrors for reflecting the full-color image beam from said projection lens.

15. A projector according to claim 14, wherein all said plurality of mirrors are tilted in a direction perpendicular to an oscillating direction of the full-color image beam from said projection lens.

16. A light crystal projector, comprising:

first to third liquid crystal panels having the same structure, each of said liquid crystal panels including a pair of polarizing plates;

a light source;

a plurality of dichroic mirrors for separating light from the light source into three primary color beams, including red, green, and blue beams, and for causing the beams to be incident on said first to third liquid crystal display panels;

light superposing means for superposing the three primary light beams, including the red, green, and blue beams which have been transmitted through said first to third liquid crystal display panels;

a projection lens for projecting a full-color image beam formed by said light superposing means; and

correcting means, located in light paths between the light source and the incident surfaces of the first to third liquid display crystal panels, for causing the intensities of the three primary color beams, including the red, green, and blue beams, to be such that the intensities of light components of the beams oscillating in the same direction are all relatively higher than that of light components of the beams oscillating in another direction which is perpendicular to said same direction.

17. A liquid crystal projector according to claim 16, wherein said light superposing means equalizes the lengths of the light paths between the light source and said first to third liquid crystal display panels for the three primary color beams including the red, green, and blue beams.

18. A liquid crystal projector, comprising:

a light source;

first to third liquid crystal panels having the same structure, each of said liquid crystal panels including a pair of polarizing plates;

optical means including light separating means for separating light from said light source into three primary color beams including red, green, and blue beams, and mirrors for causing the intensities of the three primary color beams, including the red, green and blue beams to be such that the intensities of light components of the beams polarized in the same direction are all relatively higher than that of light components of the beams oscillating in another direction which is perpendicular to said same direction, and to be incident on said first to third liquid crystal display panels;

light superposing means for superposing the three primary color beams, including the red, green, and blue beams which have been transmitted through said first to third liquid crystal display panels; and

projecting means for projecting a full-color image beam formed by said light superposing means.

19. A liquid crystal projector according to claim 18, wherein said optical means equalizes the lengths of the light paths between the light source and said first to third crystal display panels for the three primary color beams including the red, green, and blue beams.

20. A liquid crystal projector, comprising:

first to third liquid crystal panels having the same structure, each of said liquid crystal panels including a pair of polarizing plates;

a light source;

optical means including a plurality of dichroic mirrors for separating light from the light source into three primary color beams including red, green, and blue beams in which intensities of light components polarized in the same direction are all relatively higher than that of light components of the beams oscillating in another direction which is perpendicular to said same direction;

light superposing means for superposing the three primary color beams, including the red, green, and blue beams which have been transmitted through said first to third liquid crystal display panels; and

a projecting lens for projecting a full-color image beam formed by said light superposing means.

21. A liquid crystal projector according to claim 20, wherein said optical means equalizes the number of reflections as well as the number of transmissions of said three primary color beams including red, green and blue beams.

22. A projection system comprising a light source and a color selection system for selecting three color light beams and for passing said beams towards the entrance windows of a color recombination system, in which the light path from the light source to the entrance window is equal for each color light beam and in which the color selecting system comprises a first color-selective mirror for splitting a first color beam and a second color-selective mirror for splitting the remaining beam into a second and a third color light beam, characterized in that the color selection system further comprises a first, a second and a third mirror for passing the first color light beam to the first entrance window, a fourth mirror being arranged in the light path between the first and the second color-selective mirror, a fifth mirror being arranged in the light path of the second color light beam and a sixth mirror being arranged in the third color light beam to the second and the third entrance window, respectively, the first and the fifth mirror being arranged proximate and parallel to each other with their reflective sides remote from each other.