Projection type color liquid crystal optical apparatus

• US 5,648,860 A
• Filed: 02/18/1994
• Issued: 07/15/1997
• Est. Priority Date: 10/09/1992
• Status: Expired due to Term

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Original Assignee: AG Technology Co., Ltd.
• Inventors: Ooi, Yoshiharu, Serizawa, Shigeyuki, Sonda, Yoshiyuki, Hirai, Yoshinori, Kunigita, Masaya, Wakabayashi, Tsuneo
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US08/198,275
• Time in Patent Office: 1,243 Days
• Field of Search: 359/40, 359/87, 359/41, 359/70, 359/51, 359/71, 359/52, 359/48, 359/49, 353/31, 353/102, 353/34, 353/122, 353/33, 353/37, 348/751, 348/756, 348/757
• US Class Current: 349/10
• 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 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A light source optical system for projection 1, dichroic mirrors 21, 22 disposed to have a predetermined included angle β, a reflection type liquid crystal optical element blocks 31-33 each including a closely contacted converging lens and having a reflection surface and a projection optical system 4 are provided, wherein the normal line of a dichroic mirror surface and the optical axis of incident light form an included angle α; the normal line of the reflection surface and the optical axis of incident light form an included angle γ; light emitted from a light source is color-separated so as to become color lights; the color lights are rendered to be parallel light beams, and are modulated and reflected by means of the reflection type liquid crystal optical elements; the reflected light beams are color-synthesized; and the color-synthesized light is projected through a projection lens. A projection type color liquid crystal optical apparatus having a compact shape and a high brightness is obtainable.

Claims

1. A projection type color liquid crystal optical apparatus, comprising:

a light source system which produces light along an optical axis;

a color separating and synthesizing optical system comprising,

two color separating and synthesizing means being angularly arranged in a horizontal plane at an angle in a range of 40°

to 70°

with respect to each other and each disposed at respective incident angles α

1, α

2 with respect to said optical axis, wherein α

1 and α

2 are in a range of 20°

to 35°

, said two color separating and synthesizing means each separating at least one color from said light to form respectively a first color light, a second color light, and a third color light;

a light modulation system configured to modulate, reflect and condense, respectively, each of the first, second and third color lights, said light modulating system comprising three optical elements each of which comprises,

a liquid crystal optical element configured to modulate incident light to produce a modulated light, said liquid crystal optical element comprising,

a front substrate having a transparent front electrode,

a back substrate having a back electrode, and

a liquid crystal and solidified matrix composite layer disposed between said front substrate and said back substrate and comprising a nematic liquid crystal dispersed and held in a solidified matrix,

a reflection layer configured to reflect said modulated light with an incident angle, γ

, in a range of 1°

to 20°

, and

a condenser lens configured to converge the modulated light reflected by said reflection layer,

wherein said three optical elements respectively modulate, converge and output the first, second and third color lights; and

a light projection optical system which projects the first, second, and third color lights in at least one of a look-up projection angle or a look-down projection angle with respect to said horizontal plane.

2. A projection type color liquid crystal optical apparatus according to claim 1, wherein the angle α

1 is nearly equal to the angle α

2 and the angle γ

is in the range of 2°

-10°

.

3. A projection type color liquid crystal optical apparatus according to claim 1, wherein the three condenser lenses are attached on the front side of the each liquid crystal optical element respectively.

4. A projection type color liquid crystal optical apparatus according to claim 1, wherein the reflection layer is within the liquid crystal optical element.

5. The apparatus of claim 1, wherein:

said condenser lens is disposed between said liquid crystal optical element and at least one of the two color separating and synthesizing means;

said back substrate comprises a charge transfer plate comprising a plurality of thin conductive wires embedded in an insulating material; and

said reflection layer is interposed between said charge transfer plate and the liquid crystal and solidified matrix composite layer.

6. The apparatus of claim 1 or 5, wherein the light source system further comprises:

an ellipsoidal reflection mirror having a first focal point and a second focal point;

a light source positioned close to the first focal point;

an aperture device having an opening located near the second focal point; and

a cone-like prism or a cone-like reflector arranged near the second focal point.

7. The apparatus of claim 1, wherein:

said liquid crystal optical element further comprises a transparent insulating front substrate;

said back substrate comprises,

a plurality of row electrode lines, and

a plurality of column electrode lines that intersect said plurality of row electrode lines at intersections; and

said apparatus further comprising,

a plurality of active elements disposed near each intersection of the row electrode-lines and the column electrode lines,

a multi-layered dielectric film mirror which at least partially covers said row electrode lines, said column electrode lines and said active elements, and

a plurality of transparent pixel electrodes formed on or above said multi-layered dielectric film mirror.

8. The apparatus of claim 7, wherein said back substrate further comprises:

a third electrode arranged to at least partially cover said plurality of row electrodes, said plurality of column electrodes, said plurality of active elements, and a gap between neighboring pixels of said plurality of pixels, and wherein

an electric potential between said third electrode and said front electrode is less than or equal to a threshold potential level of the liquid crystal and solidified matrix composite layer.

9. The apparatus of claim 1, wherein at least one of said two color separating and synthesizing means further comprises:

means for changing a spectral transmittance of said at least one of said two color separating and synthesizing means based on a position of incident light so that compensate for a difference in spectral transmittance corresponding to an incident angle of said incident light.

10. A projection type color liquid crystal optical apparatus according to any of claim 4, 1 or 5, wherein the reflection layer further comprises a multi-layered dielectric film having a relatively high refractive index and a relatively low refractive index formed alternatively therein.

11. A projection type color liquid crystal optical apparatus according to any of claim 4, 1 or 5, wherein minute concaves and convexes are formed on a surface of front electrode or on an interface of the front substrate.

12. A projection type color liquid crystal optical apparatus according to claim 1, wherein the reflection layer being for compensating a color purity characteristic of at least one of the two color separating and synthesizing means.

13. A projection type color liquid crystal optical apparatus according to claim 1, wherein at least one of the condenser lens, the reflection layer or the liquid crystal optical element comprises wavelength selecting and absorbing means for compensating a color purity characteristic of at least one of the two color separating and synthesizing means.