Projection type displaying apparatus and illumination system

• US 5,422,691 A
• Filed: 11/13/1992
• Issued: 06/06/1995
• Est. Priority Date: 03/15/1991
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Tanimoto, Akihito, Shinozaki, Junichiro, Ishikawa, Masaki, Ninomiya, Noboru
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Dowling, William C.
• Application Number:
  US07/949,243
• Time in Patent Office: 935 Days
• Field of Search: 353/70, 353/69, 353/38, 353/98, 353/99, 353/100, 353/37, 353/102, 359/454, 359/455, 359/456, 359/457, 362/260, 362/309, 362/308, 362/307, 362/299, 362/326, 362/328
• US Class Current: 353/69
• CPC Class Codes: G03B 21/10 Projectors with built-in or built-on screen
• CPC Class Codes: G03B 21/132 Overhead projectors, i.e. capable of projecting hand-writing or drawing during action epidiascopic projectors G03B21/08
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells

Abstract

To provide an oblique projection type displaying apparatus for radiating rays of light which are nearly parallel with a light bulb, thereby preventing the brightness of a resultant image from becoming uneven, the apparatus comprises a light source, optical modulating means, projecting means for projecting an image generated by the optical modulating means on a screen, and the screen, wherein a center optical axis of rays of light projected by the projecting means are obliquely entered into the screen, wherein the projecting means comprises first projecting optical means for converting an image generated by the optical modulating means into an intermediate image with trapezoidal distortion, and second projecting optical means for converting the intermediate image with trapezoidal distortion into an image without trapezoidal distortion on the screen, and wherein the first projecting optical means comprises two lenses which are not parallel each other. In addition, the constructions of the light source, the reflection mirror for changing the optical path, and the screen are modified.

Claims

1. A projection type displaying apparatus, comprising:

a light source;

optical modulating means;

projecting means for projecting an image generated by said optical modulating means on a screen; and

said screen;

wherein a center optical axis of rays of light projected by said projecting means are obliquely entered into said screen;

wherein said projecting means comprises;

first projecting optical means for converting an image generated by said optical modulating means into an intermediate image with trapezoidal distortion; and

second projecting optical means for converting said intermediate image with trapezoidal distortion into an image without trapezoidal distortion on said screen; and

wherein said first projecting optical means comprises two lenses which are not parallel to each other.

2. The projection type displaying apparatus as set forth in claim 1, wherein said two lenses which are not parallel to each other of said first projecting optical means are disposed in such a way that a line of intersection of a screen side focal plane of a light source side lens and a light Source side focal plane of a screen side lens passes through a line which connects a principal point of the light source side lens and a principal point of the screen side lens.

3. The projection type displaying apparatus as set forth in claim 1, wherein said first projecting optical means comprises at least two sets of two lenses which are not parallel to each other.

7. The projection type displaying apparatus as set forth in claim 1, wherein said light source comprises a lamp and a reflector, and a light transmitting optical device adapted for equalizing a distribution of rays of light reflected by said reflector, said light transmitting optical device being disposed on a light exit side of said reflector.

4. A projection type displaying apparatus, comprising:

a light source;

optical modulating means;

projecting means for projecting an image generated by said optical modulating means on a screen; and

said screen;

wherein a center optical axis of rays of light projected by said projecting means are obliquely entered into said screen;

wherein said projecting means comprises;

first projecting optical means for converting an image generated by said optical modulating means into an intermediate image with trapezoidal distortion;

second projecting optical means for converting said intermediate image with trapezoidal distortion into an image without trapezoidal distortion on said screen; and

an aperture stop mechanism for performing an optical adjustment, that is, for improving the quality of an image; and

wherein said first projecting optical means comprises at least one set of two lenses which are not parallel to each other, said aperture stop mechanism being disposed in projecting optical means.

5. The projection type displaying apparatus as set forth in claim 4, wherein said aperture stop mechanism is disposed in the vicinity of a point of intersection where a line of intersection of focal planes of said two lenses which are not parallel to each other intersects a line which connects principal points of said two lenses.

6. The projection type displaying apparatus as set forth in claim 4, wherein said aperture stop mechanism is in a flat shape.

8. A projection type displaying apparatus, comprising:

optical modulating means;

projecting means for projecting an image generated by said optical modulating means on a screen;

a reflection mirror for reflecting rays of light projected by said projecting means to said screen;

wherein said reflecting mirror includes a plurality of successive elements in the path of the rays of light, the last of said elements of said reflection mirror being disposed parallel to said screen; and

wherein a center optical axis of the rays of light projected by said projecting means has an incident angle α

to said screen, the incident angle α

being 60°

or more.

9. An illumination system having a lighting unit, said lighting unit comprising a lamp, a reflector for reflecting, at an exit side of the reflector, a beam of light rays having a width greater than that of the reflector, and a light transmitting optical element arranged on the exit side of the reflector and having a face with a wall thickness which is gradually reduced at restricted sides of the beam, so that the light rays of the beam reflected by the reflector have a substantially even distribution.

10. An illumination system comprising a lamp, a reflector and a light transmitting optical device disposed on an exit side of the reflector, said optical device having a conical surface to produce a distribution of light rays in a beam reflected by the reflector which is substantially even.

11. The illumination system as set forth in claim 10, wherein said optical device comprises two right-circular conical members facing in opposite directions.

12. The illumination system as set forth in claim 10, wherein said optical device comprises a first right-circular conical member facing in one direction and a second member having a right-circular conical recess therein pointing in the same direction as said first conical member.

13. The illumination system as set forth in claim 10, wherein said optical device comprises a body having end faces of right circular conical shape facing in opposite directions.

14. The illumination system as set forth in claim 10, wherein said optical device comprises a body having end surfaces one of which is of right-circular conical shape pointed in one direction and the other of which has a right-circular conical recess also pointed in said one direction.

15. The illumination system as set forth in claim 10, wherein said optical device comprises a first element having end surfaces one of which is of right-circular conical shape pointed in one direction and the other of which is a right-circular conical recess also pointed in said one direction, and a second element having a right-circular conical surface pointed in said one direction.

16. An illumination system comprising a lamp, a reflector, and a light transmitting optical element disposed at an exit side of the reflector for displacing rays of light reflected by the reflector at sides thereof towards a central part of the rays of light, and for displacing rays of light at said central part towards said sides.

17. An illumination system as set forth in claim 16, wherein said optical element is conical.

18. An illumination system as set forth in claim 17, wherein said optical element comprises two convex optical members.

19. An illumination system as set forth in claim 17, wherein said optical element comprises an optical member having opposite faces of convex shape.

20. An illumination system as set forth in claim 17, wherein said optical element comprises two optical members, one of which has one face of convex shape and an opposite face of concave shape, and the other of which elements is convex.

21. An illumination system comprising a lamp, a reflector, and a plurality of light transmitting optical elements disposed on an exit side of the reflector for condensing rays of light reflected by the reflector, one of said light transmitting optical elements including two conical optical members, a first of which is convex, and a second of which is concave.

22. An illumination system comprising a lamp, a reflector, and a light transmitting optical element disposed on an exit side of said reflector for condensing rays of light reflected by the reflector, said optical element comprising a conical member having one face of convex shape and an opposite face of concave shape.