Light source unit and projection type video display apparatus using the same

• US 7,806,566 B2
• Filed: 01/13/2005
• Issued: 10/05/2010
• Est. Priority Date: 01/16/2004
• Status: Expired due to Fees

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamasaki, Futoshi, Yatsu, Masahiko
• Primary Examiner(s): Sohn; Seung C
• Assistant Examiner(s): LE, BAO-LUAN Q
• Application Number:
  US11/035,709
• Publication Number:
  US 20050190307A1
• Time in Patent Office: 2,091 Days
• Field of Search: 353/98, 362/296, 362/310, 362/241, 362/249.02, 362/296.01, 362/296.07, 362/296.08, 362/346, 362/350
• US Class Current: 362/298
• 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

In a projection type video display apparatus, in order to assure sufficient brightness by suppressing a decrease in light utilization efficiency inside a limited output aperture area of a light source unit, a transmission or reflection type liquid crystal is used for a video display device and the light source unit having a plurality of reflectors or focusing mirrors in correspondence with LED'"'"'s representing light sources is so constructed as to satisfy D<4×f or D<4×Z, where D represents an effective diameter of a reflector, f represents a focal distance of a mirror and Z represents a distance between a light emitter of the light source and an apex at a center of the mirror.

Claims

1. A light source unit for use in a projection type video display apparatus having a video display device for modulating light on the basis of a video signal and a projection lens for projecting output light emitted from said video display device upon a screen, comprising:

at least two arrayed light sources; and

a focusing mirror in the form of a reflector disposed in correspondence with each of said light sources and having a shape of paraboloid or non-spherical form approximating the paraboloid,

wherein each light source in the arrayed light sources emits light semi-spherically towards an apex at a center of said focusing mirror; and

wherein when D represents an effective diameter of said reflector, f represents a focal distance of said mirror and Z represents a distance between a light emitter of said light source and the apex at the center of said focusing mirror, said light source unit is so constructed as to satisfy

1.6×

f<

D<

3.2×

f or 1.6×

Z<

D<

3.2×

Z.

2. A light source unit according to claim 1, wherein said light source is formed of an LED.

3. A projection type video display apparatus comprising:

a light source unit;

a video display device which modulates luminous flux from said light source unit on the basis of a video signal; and

a projection lens which projects output light from said video display device upon a screen,

wherein said light source unit includes at least two arrayed light sources and a focusing mirror in a form of a reflector disposed in correspondence with each of said light sources and having a shape of paraboloid or non-spherical form approximating the paraboloid,

wherein each light source in the arrayed light sources emits light semi-spherically towards an apex at a center of said focusing mirror; and

wherein when D represents an effective diameter of said reflector, f represents a focal distance of said mirror and Z represents a distance between a light emitter of said light source and the apex at the center of said focusing mirror, said light source unit is so constructed as to satisfy

1.6×

f<

D<

3.2×

f or 1.6 ×

Z<

D<

3.2×

Z.

4. A projection type video display apparatus according to claim 3, wherein said light source is formed of an LED.