Liquid crystal display device with improved convergence efficiency and converting reflector of the same

• US 5,295,005 A
• Filed: 10/01/1991
• Issued: 03/15/1994
• Est. Priority Date: 12/19/1990
• Status: Expired due to Fees

• Current Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Original Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Inventors: Tsuchiya, Kunimoto, Nishida, Masami, Izawa, Masataka
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US07/771,000
• Time in Patent Office: 896 Days
• Field of Search: 359/40, 359/867, 359/41, 359/869, 359/48, 359/49, 353/31, 353/33, 353/34, 353/37, 353/98, 362/296, 362/347, 362/350
• US Class Current: 349/8
• CPC Class Codes: F21V 7/04 Optical design
• CPC Class Codes: G02B 27/1046 for use with transmissive spatial light modulators
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• 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 liquid crystal display device comprises a converging reflector, a liquid crystal panel, a condenser lens and a projection lens, wherein a correlation between these optical parts and structure of sizes of the optical parts is considered. Accordingly, a convergence efficiency of the device as whole system can be improved. A converging reflector comprises a light source and a reflecting mirror reflecting a light from the light source, wherein a curved plane shape of the mirror is offset radially to the same length as a radius of a light emitting tube of the light source. Accordingly, a convergence efficiency of the converging reflector can be improved.

Claims

1. A liquid crystal display device comprising:

a converging reflector provided with a linear light source positioned at a central axis of the converging reflector and a plane of reflection formed by a reflecting mirror of paraboloid of revolution;

a liquid crystal panel for selectively passing a light reflected from the converging reflector;

a condenser lens arranged between the converging reflector and the liquid crystal panel for transmitting a ray of the light from the converging reflector to the liquid crystal panel; and

a projection lens for projecting the ray of the light from the liquid crystal panel on an irradiation plane,

wherein a curvature of the paraboloid of the converging reflector is about 0.015±

0.0025 mm^-1, a length of the linear light source is about 5 to 7 mm, an aperture of the converging reflector is about 100±

20 mm, and an effective display size of the liquid crystal panel is about 2.8 to 3.3 inches.

2. A liquid crystal display device according to claim 1, wherein a first end point of the light source is arranged at a focal point of a plane of reflection and a second end point of the light source is arranged toward the liquid crystal panel from the focal point.

3. A liquid crystal display device according to claim 1, wherein a white light from the light source is separated into rays of light of three colors of red, green and blue by using dichroic mirrors positioned between the light source and the liquid crystal panel.

4. A liquid crystal display device according to claim 1, wherein the light source is comprised of a metal halide lamp.

5. A liquid crystal display device according to claim 1, wherein in a region where an F-number in an F-number-length coordinate plane indicated by an F-number of the projection lens and a length from an end of the aperture of the converging reflector to the liquid crystal panel is 3.0 to 4.5 and the length in the F-number-length coordinate is 200 to 300 mm, a coordinate axis perpendicular to the F-number-length coordinate plane is set as a focal length of the condenser lens, wherein, in the region, when the F-number is 3.0 and the length is 200 mm, the focal length is set in a range of 350 to 750 mm, when the F-number is 3.0 and the length is 300 mm, the focal length is set in a range of 250 to 1000 mm, when the F-number is 4.5 and the length is 200 mm, the focal length is set in a range of 1400 to 1800 mm, and when the F-number is 4.5 and the length is 300 mm, the focal length is set in a range of 300 to 1000 mm.

6. A liquid crystal display device according to claim 1, wherein the light source of the converging reflector comprises a light emitting tube having a predetermined radius and a curved plane shape of the reflecting mirror of the converging reflector is offset radially to the same length as the radius of the light emitting tube according to the central axis.

7. A liquid crystal display device according to claim 6, wherein a length of an offset of the mirror plane is satisfied with a following equation and relationship between the radius and z-coordinate is decided to the equation;

space="preserve" listing-type="equation">z=a (y-r).sup.2 -(1/4a)

where a is a curvature of paraboloid of revolution of the reflecting mirror, y is a length of the curved plane shape of the mirror plane from the central axis, and z is a coordinate axis having the same direction as the central axis.