Short throw projection system and method

• US 20030231261A1
• Filed: 06/12/2003
• Published: 12/18/2003
• Est. Priority Date: 06/12/2002
• Status: Active Grant

• Current Assignee: Geo Semiconductor Incorporated
• Original Assignee: Silicon Optix (Renesas Electronics Corporation)
• Inventors: Bassi, Zorawar S., Smith, Gregory Lionel, Lee, Louie
• Granted Patent: US 7,239,360 B2
• Time in Patent Office: Days
• US Class Current: 348/745
• CPC Class Codes: H04N 5/7408 Direct viewing projectors, e.g. an image displayed on a video CRT or LCD display being projected on a screen
• CPC Class Codes: H04N 9/3141 Constructional details thereof details not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

A short throw projection system and method for displaying a corrected optical image on a projection screen based on input image data that includes an electronic correction unit, an image projector and a reflection assembly. The electronic correction unit receives the input image data and generates pre-distorted image data. The image projector receives the pre-distorted image data from the electronic correction unit and projects a pre-distorted optical image that corresponds to the pre-distorted image data or a pre-distorted image compensated by the projection optic distortion. The optical reflection assembly is positioned in the optical path of the pre-distorted optical image to project an optical image on the projection screen. The reflection assembly can consist of various combinations of curved and planar mirrors as desired. The electronic correction unit is encoded to pre-distort the geometry of the image represented by the image data such that when the pre-distorted optical image is projected through the image projector and reflected within the reflection assembly, the optical and geometric distortions associated with the image projector and the mirrors within the reflection assembly are eliminated in the displayed optical image.

Claims

1. A projection system for displaying a distortion corrected optical image on a projection screen based on input image data, comprising:

(a) an electronic correction unit for receiving the input image data and generating pre-distorted image data;

(b) an image projector coupled to the electronic correction unit for receiving the pre-distorted image data and providing an pre-distorted optical image that corresponds to the pre-distorted image data;

(c) a reflection assembly that includes at least one of a planar and a curved mirror, said optical reflection assembly being positioned in the optical path of the pre-distorted optical image to produce a displayed optical image for projection on the projection screen; and

(d) said electronic correction unit being adapted to pre-distort the geometry of the input image data such that when said pre-distorted optical image based on said pre-distorted image data provided through the image projector and reflected within the optical reflection assembly, the optical, geometric, and alignment distortions associated with said image projector and said reflection assembly are eliminated in the displayed optical image.

2. The projection system of claim 1, further comprising a display device associated with the image projector, wherein the electronic correction unit also modifies the image brightness associated with said input image data such that brightness variations due to characteristics of the optical components, projection path and the display device are compensated for.

3. The projection system of claim 1, wherein said electronic correction unit is further adapted to independently pre-distort the geometry of each primary color represented by the input image data and generate a pre-distorted primary color image data to compensate for differences in the optical refraction of each color, such that when the pre-distorted primary color image associated with the pre-distorted primary color image data is projected through the image projector and the reflection assembly to the projection screen, the optical and geometric distortions associated with each primary color optical image are eliminated.

4. The projection system of claim 3, wherein said image projector comprises:

(i) a light generator for generating a collimated beam of light;

(ii) a color separator coupled to the light generator that separates the light beam into separated primary color light streams that correspond to those represented in the pre-distorted primary color image data;

(iii) a display device positioned in front of the light separator for modulating the separated primary color light streams with the pre-distorted primary color image data; and

(iv) an optical assembly positioned in front of the display device for projecting and focusing the pre-distorted optical image onto the projection screen.

5. The projection system of claim 4, wherein said light generator is selected from the group consisting of a lamp and a laser, said display device is a micro-display, and said optical assembly is an array of lenses.

6. The projection system of claim 4, further comprising a plurality of display devices, wherein said light separator directs separated primary color light streams to said plurality of display devices, each display device being adapted to concurrently modulate each one of the primary color light streams with corresponding primary color image data and wherein said optical assembly is further adapted to direct and focus all primary color optical images to a composite color optical image.

7. The projection system of claim 4, where the optical assembly of said image projector contains astigmatic elements designed to at least partially compensate for focus astigmatism in the optical path of said pre-distorted optical image.

8. The projection system of claim 4, where the optical assembly of said image projector contains wide angle lenses having at least one of uncorrected optical distortion and lateral chromatic aberration.

9. The projection system of claim 1, wherein said reflection assembly comprises at least one curved mirror adapted to substantially correct for at least one of optical and geometric distortion and a planar mirror wherein the reflective surfaces of the at least one curved mirror and planar mirror is placed within the optical path of the pre-distorted optical image.

10. The projection system of claim 1, wherein said reflection assembly comprises a convex mirror wherein the convex reflective surface is placed within the optical path of the pre-distorted optical image.

11. The projection system of claim 1, wherein said reflection assembly comprises a concave mirror wherein the concave reflective surface is placed within the optical path of the pre-distorted optical image.

12. The projection system of claim 1, wherein said at least one curved mirror of said reflection assembly comprises a hyperbolic/hyperboloid mirror.

13. The projection system of claim 1, wherein said reflection assembly comprises a first curved mirror and a second curved mirror, such that the optical path of the pre-distorted optical image is reflected from the surface of said first curved mirror onto the surface of said second curved mirror.

14. The projection system of claim 13, wherein said first mirror is a convex mirror and said second mirror is concave mirror, such that the optical path of the pre-distorted optical image is reflected from the convex surface of said first curved mirror onto the concave surface of said second curved mirror.

15. The projection system of claim 1, wherein said reflection assembly comprises at least one curved mirror and at least one planar mirror to reduce the optical envelope.

16. The projection system of claim 1, wherein said electronic correction unit and projection unit, and reflection assembly are adapted to operate in a front projection configuration.

17. The projection system of claim 1, wherein said electronic correction unit and projection unit, and reflection assembly are adapted to operate in a rear projection configuration.

18. The projection system of claim 1, wherein said projection system includes a pivoting assembly for retracting said optical assembly towards the plane of the projection screen to reduce obstruction in front of the projection screen.

19. The projection system of claim 1, wherein the pre-distorted optical image is split into at least two optical paths where at least one mirror of said reflection assembly is positioned in each of at least two optical paths such that each optical path contains a different portion of the displayed optical image, each of which illuminates a different portion of the projection screen.

20. The projection system of claim 1 in combination with at least one other projection system of claim 1, wherein each projection system displays a different portion of the optical image on the projection screen.

21. The projection system of claim 19 or 20, wherein said different portions of the optical image displayed on the projection screen are slightly overlapping and where the electronic correction unit uses edge softening in respect of the displayed optical images in order to reduce or eliminate visible seams therein.

22. A projection method for displaying a distortion corrected optical image on a projection screen based on input image data, comprising:

(a) receiving input image data and generating pre-distorted image data;

(b) providing a pre-distorted optical image through an image projector, said pre-distorted optical image corresponding to the pre-distorted image data;

(c) reflecting the pre-distorted optical image in a reflection assembly comprising at least one of a planar mirror and a curved mirror to produce a displayed optical image for projection on the projection screen;

(d) wherein (a) further consists of pre-distorting the geometry of the input image data such that when said pre-distorted optical image based on said pre-distorted image data is provided through the image projector and reflected within the reflection assembly, the optical, geometric, and alignment distortions associated with the image projector and the reflection assembly are eliminated in the displayed optical image.

23. The method of claim 22, further comprising modifying the image brightness associated with said input image data such that optical brightness variations due to characteristics of the optical components, optical path, and the display device are compensated for.

24. The method of claim 22, further comprising independently pre-distorting the geometry of each primary color represented by the input image data to compensate for difference in optical refraction of each color, such that when the pre-distorted primary color image associated with the pre-distorted primary color image data is projected through the image projector and the reflection assembly to the projection screen, the optical and geometric distortions associated with each primary color optical image are eliminated.

25. The method of claim 24, where (b) further comprises generating a collimated beam of light, separating the light beam into primary color light streams, positioning a display device for modulating the pre-distorted primary color image data, and projecting and focusing the pre-distorted optical image onto the projection screen.

26. The method of claim 25, where each of the primary colors separated light streams are directed to a separate display device, each display device being adapted to concurrently modulate each one of the primary color light streams with corresponding primary color image data and to direct and focus each primary color optical images into a composite color optical image.

27. The method of claim 22, further comprising providing astigmatic elements within the path of the pre-distorted optical image to compensate for focus astigmatism effects.

28. The method of claim 22, further comprising providing a wide angle lens having at least one of uncorrected optical distortion and lateral chromatic aberration within the path of the pre-distorted optical image.

29. The method of claim 22, wherein (c) comprises reflecting said pre-distorted optical image in the surface of a convex mirror.

30. The method of claim 22, wherein (c) comprises reflecting said pre-distorted optical image in the surface of a concave mirror.

31. The method of claim 22, wherein (c) comprises reflecting said pre-distorted optical image in the surface of a hyperbolic/hyperboloid mirror.

32. The method of claim 22, wherein (c) comprises reflecting said pre-distorted optical image sequentially from the surface of a first curved mirror onto the surface of a second curved mirror.

33. The method of claim 22, wherein (c) comprises reflecting said pre-distorted optical image sequentially from the surface of at least one of a curved mirror that substantially corrects for at least one of optical and geometric distortion and a planar mirror onto the surface of the other of a curved mirror and a planar mirror to reduce the optical envelope.

34. The method of claim 22, wherein said first mirror is a convex mirror and said second mirror is concave mirror.

35. The method of claim 22, wherein the projection system is operated in a front projection configuration.

36. The method of claim 22, wherein the projection system is operated in a rear projection configuration.

37. The method of claim 22, further comprising retracting the optical assembly towards the plane of the projection screen to reduce obstruction in front of the projection screen.

38. The method of claim 22, further comprising splitting the pre-distorted optical image into at least two optical paths where at least one mirror of said reflection assembly is positioned in each at least two optical paths such that each optical path contains a different portion of the displayed optical image, each of which illuminates a different portion of the projection screen.

39. The method of claim 22 implemented by at least two separate projector systems, each projector systems implementing the method of claim 22 to display a different portion of the optical image on the projection screen.

40. The method of claim 36 or 37, further comprising edge softening the different portions of the displayed optical image to reduce or eliminate visible seams therein.