Projection system for projecting a color video picture and transformation optical system for same

• US 5,694,180 A
• Filed: 05/14/1996
• Issued: 12/02/1997
• Est. Priority Date: 07/23/1993
• Status: Expired due to Fees

• Current Assignee: JENOPTIK LDT GmbH (Rheinmetall AG)
• Original Assignee: LDT GmbH & Co. Laser-Display-Technologie KG
• Inventors: Holota, Wolfgang, Ruder, Rolf, Hiller, Klaus, Elster, Gunther, Deter, Christhard
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): Miller, John W.
• Application Number:
  US08/645,923
• Time in Patent Office: 567 Days
• Field of Search: 348/744-747, 348/752, 348/753, 348/756, 348/757, 348/760, 348/762, 348/763, 348/767, 348/768, 348/789, 348/800-803, 359/618, 359/634, 359/652, 359/654, 359/793-795
• US Class Current: 348/746
• CPC Class Codes: G02B 13/0005 having F-Theta characteristic scanning systems employing movable or deformable optical elements G02B26/10
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/3141 Constructional details thereof details not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

In a projection system for projecting a video picture composed of picture points on a screen with at least one light source which emits a light bundle and can be varied in intensity and with a deflecting device which deflects the light bundle to illuminate the picture points on the screen, a transformation optical system having at least two stages is arranged between the deflecting device and the screen and is corrected according to the tangent condition so as to be free of distortion. The transformation optical system has at least two optical stages. The first optical stage produces an intermediate image plane which is imaged on the screen by means of the subsequent optical stage (s).

Claims

1. A transformation optical system, particularly for use in a projection system for projecting a video picture on a planar screen comprising:

at least first and second optical stages, said first optical stage producing an intermediate plane which is imaged on the screen by means of subsequent optical stages, said transformation optical system being afocal and corrected according to a required tangent condition so as to be free of distortion, said transformation optical system enabling enlargement of a video picture while being structurally small in depth.

2. The transformation optical system according to claim 1, wherein the intermediate image plane contains an image-side focal point of said first optical stage in the case of parallel incidence of light.

3. The transformation optical system according to claim 1, wherein said second optical stage has a focal length which is less than half of the focal length of the first optical stage.

4. The transformation optical system according to claim 3, wherein said second optical stage has a focal length which is less than 1/5 of the focal length of the first optical stage.

5. The transformation optical system according to claim 1, having an object-side principal plane and an object-side focal point of the first optical stage, wherein said object-side principal plane of said transformation optical system is situated outside a first lens vertex and said object-side focal point of said first optical stage is situated between said object-side principal plane and said first lens vertex.

6. The transformation optical system according to claim 1, wherein said first optical stage and said second optical stage are multiple-lens arrangements.

7. The transformation optical system according to claim 1, having intermediate image planes between individual optical stages, wherein each intermediate image plane is situated between a last lens vertex of an optical stage and a first lens vertex of a subsequent optical stage.

8. In a projection system for projecting a video picture composed of picture points on a planar screen having at least one light source which emits a light bundle and can be varied in intensity and a deflecting device which deflects the light bundle to illuminate the picture points on the screen, the improvement comprising:

a transformation system having at least two stages being arranged between said deflecting device and said screen, said transformation optical system being afocal and corrected according to a required tangent condition so as to be free of distortion, said transformation optical system enabling enlargement of said projected video picture while providing a projection system with reduced depth.

9. The projection system according to claim 8, including a field lens arranged between said transformation optical system and said screen.

10. The projection system according to claim 9, wherein said field lens is a Fresnel lens.

11. The projection system according to claim 10, wherein the picture produced by said transformation optical system is at a distance from the deflecting device in the focal point of the Fresnel lens.

12. The projection system according to claim 10, wherein the picture produced by said transformation optical system is at a distance corresponding to ±

20% of the focal length of the Fresnel lens from its focal point.

13. The projection system according to claim 10, wherein the Fresnel lens has a flat surface facing said transformation optical system.

14. The projection system according to claim 8, wherein an object-side principal plane is associated with the transformation optical system, said deflecting device being arranged between said object-side principal plane of the transformation optical system and a first object-side lens vertex of the transformation optical system.

15. The projection system according to claim 8, wherein said two stages comprise a first and second optical stage, said first optical stage producing an intermediate image plane which is imaged on the screen by means of subsequent optical stages.

16. The projection system according claim 15, wherein the intermediate image plane contains an image-side focal point of said first optical stage in the case of parallel incidence of light.

17. The projection system according claim 15, wherein said second optical stage has a focal length which is less than half of the focal length of the first optical stage.

18. The projection system according claim 17, wherein said second optical stage has a focal length which is less than 1/5 of the focal length of the first optical stage.

19. The projection system according claim 15, wherein said object-side principal plane of said transformation optical system is situated outside a first lens vertex and said object-side focal point of said first optical stage is situated between said object-side principal plane and said first lens vertex.

20. The projection system according claim 15, wherein said first optical stage and said second optical stage are multiple-lens arrangements.

21. The projection system according claim 15, wherein each intermediate image plane is situated between a first lens vertex of an optical stage and a first lens vertex of a subsequent optical stage.