Projector with adjustably positioned image plate

• US 6,609,797 B2
• Filed: 01/22/2002
• Issued: 08/26/2003
• Est. Priority Date: 01/29/1999
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Yamaguchi, Takao, Aoki, Shin, Guan, Haike, Ejiri, Koichi
• Primary Examiner(s): Adams, Russell
• Assistant Examiner(s): Koval, Melissa J
• Application Number:
  US10/055,222
• Publication Number:
  US 20020089651A1
• Time in Patent Office: 581 Days
• Field of Search: 353/30, 353/31, 353/69, 353/70, 353/88, 353/101, 353/121, 353/122, 348/745, 348/746, 348/747, 348/766, 348/771, 348/761, 348/806, 396/115, 396/149, 396/150, 396/430, 349/5, 349/6, 349/7, 349/58, 359/242
• US Class Current: 353/69
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: H04N 17/04 for receivers
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 9/317 Convergence or focusing systems electronic adjustment of convergence H04N9/3185; convergence or focusing arrangements for cathode ray tubes H04N9/28; means for automatic focusing of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/53
• CPC Class Codes: H04N 9/3185 Geometric adjustment, e.g. keystone or convergence optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

A projector is often positioned so that its optical axis is at an imperfect orthogonal angle with respect to a projection screen. This position causes a keystone distortion as well as imperfect focus in the projected image. To correct these undesirable problems, initially, a lens and/or an image-forming plate is independently repositioned to bring the projected image into focus based upon user input data. The keystone distortion is also corrected by redrawing the image on an image-forming surface based upon additional user input data.

Claims

1. A method of projecting an image, comprising the steps of:

projecting the image contained in an image plate to form a projected image on an image-projection surface via an optical component, an optical axis of the optical component being positioned at a non-perpendicular angle with respect to the image-projection surface;

collecting keystone correction data for ultimately correcting keystone distortion in the projected image;

determining a conversion matrix based upon the keystone correction data for correcting the image contained in the image plate;

correcting the image on the image plate based upon the conversion matrix to substantially eliminate the keystone distortion; and

projecting the corrected image on the image plate onto the image-projection surface.

2. The method of projecting an image according to claim 1, comprising additional steps of:

inputting predetermined focus data for adjusting focus of the projected image on the image-projection surface; and

mechanically adjusting a parameter selected from the group consisting of the optical axis of the optical component and a tilting angle of the image plate with respect to the image projection surface based on the predetermined focus date, whereby the projected image is focused on the image-projection surface.

3. The method of projecting an image according to claim 1, wherein the optical axis of the optical component with respect to the image-projection surface is independently adjusted.

4. The method of projecting an image according to claim 1, wherein the tilting angle of the imaging plate with respect to the image-projection surface is independently adjusted.

5. The method of projecting an image according to claim 1, wherein the keystone correction data is collected by projecting a predetermined image containing vertical and horizontal line segments with equal lengths on the image projection surface to form the projected image containing respective projected vertical and horizontal line segments, and wherein a ratio in length between the projected vertical and horizontal line segments is determine, the ratio being the predetermined focus data.

6. The method of projecting an image according to claim 1, wherein the keystone correction data includes a predetermined number of pairs of coordinates of an image of a predetermined shape and corresponding pairs of coordinates of a projected image of the predetermined shape.

7. A system for projecting an image onto an image-projection surface to form a projected image, comprising:

an optical component having an optical axis, the optical axis initially being positioned at a non-perpendicular angle with respect to the image-projection surface;

an image forming unit for generating image data for the image;

an image plate connected to said image forming unit for forming the image based upon the image data, the image being projected on the image-projection surface via said optical component;

an input unit for collecting keystone correction data for ultimately correcting keystone distortion in the projected image;

a calculation unit connected to said input unit for determining a conversion matrix based upon the keystone correcting data; and

a correction unit connected to the calculation unit and said image forming unit for correcting the image on the image plate based upon the conversion matrix to substantially eliminate the keystone distortion in the projected image.

8. The system for projecting an image according to claim 7 wherein said input unit connected to said optical component and image plate inputs predetermined focus data for adjusting the projected image in focus on the image-projection surface, claim 8 further comprises:

an angle adjustment unit connected to said optical component and said image plate for mechanically adjusting a parameter selected from the group consisting of the optical axis of said optical component and a tilting angle of said image plate with respect to the image-projection surface based on the predetermined focus data, whereby the projected image is focused on the image-projection surface.

9. The system for projecting an image according to claim 8, wherein said angle adjustment unit independently adjusts an optical axis of said lens with respect to the image projection surface.

10. The system for projecting an image according to claim 8, wherein said angle adjustment unit independently adjusts the tilting angle of said image plate with respect to the image projection surface.

11. The system for projecting an image according to claim 8, wherein said input unit collects the keystone correction data by projecting a predetermined image containing vertical and horizontal line segments with equal lengths on the image-projection surface to form a projected image containing respective projected vertical and horizontal line segments, and wherein a ratio in length between the projected vertical and horizontal line segments is determined, the ratio being the predetermined focus data.

12. The system for projecting an image according to claim 7, wherein said optical component further includes a series of lenses.

13. The system for projecting an image according to claim 7, wherein said keystone correction data includes a predetermined number of pairs of coordinates of an image of a predetermined shape and corresponding pairs of coordinates of a projected image of the predetermined shape.

14. An apparatus for substantially eliminating keystone distortions in a projected image, comprising:

an image plate for forming an image based upon predetermined standard image data;

an optical component located near said image plate to focus the standard image on a projection surface;

an input unit for collecting keystone correction data for ultimately correcting keystone distortion in the projected image;

a calculation unit connected to said input unit for determining a conversion matrix based upon the keystone correcting data; and

a correction unit connected to the calculation unit and said image forming unit for correcting the image on the image plate based upon the conversion matrix to substantially eliminate the keystone distortion in the projected image.

15. The apparatus for substantially eliminating keystone distortions according to claim 14 further comprising:

an angle adjustment unit connected to said optical component and said image plate for mechanically adjusting a parameter selected from the group consisting of the optical axis of said optical component and a tilting angle of said image plate with respect to the image-projection surface based on the predetermined focus data, whereby the projected image is focused on the image-projection surface.

16. The apparatus for substantially eliminating keystone distortions according to claim 15 wherein said angle adjustment unit independently adjusts an optical axis of said lens with respect to the image projection surface.

17. The apparatus for substantially eliminating keystone distortions according to claim 15, wherein said angle adjustment unit independently adjusts the tilting angle of said image plate with respect to the image projection surface.

18. The apparatus for substantially eliminating keystone distortions according to claim 14, wherein said input unit collects the keystone correction data based upon the standard image data containing vertical and horizontal line segments with equal lengths on the image-projection surface to form a projected image containing respective projected vertical and horizontal line segments, and wherein a ratio in length between the projected vertical and horizontal line segments is determined, the ratio being the predetermined focus data.

19. The apparatus for substantially eliminating keystone distortions according to claim 14 wherein the keystone correction data includes a predetermined number of pairs of coordinates of an image of a predetermined shape and corresponding pairs of coordinates of a projected image of the predetermined shape.

20. An apparatus for substantially eliminating keystone distortions in a projected image, keystone correction data being collected by an external unit for ultimately correcting keystone distortion in a projected image, a conversion matrix being determined by the external unit based upon the keystone correction data;

comprising;

an image plate for forming an image based upon predetermined standard image data;

an optical component located near said image plate to focus the standard image on an image projection surface; and

a correction unit connected to said image forming unit for correcting the image on the image plate based upon the conversion matrix to substantially eliminate the keystone distortion in the projected image.

21. The apparatus for substantially eliminating keystone distortions according to claim 20 further comprising:

an angle adjustment unit connected to said optical component and said image plate for mechanically adjusting a parameter selected from the group consisting of the optical axis of said optical component and a tilting angle of said image plate with respect to the image projection surface based on the predetermined focus data, whereby the projected image is focused on the image-projection surface.

22. The apparatus for substantially eliminating keystone distortions according to claim 21, wherein said angle adjustment unit independently adjusts an optical axis of said lens with respect to the image projection surface.

23. The apparatus for substantially eliminating keystone distortions according to claim 21 wherein said angle adjustment unit independently adjusts the tilting angle of said image plate with respect to the image projection surface.

24. The apparatus for substantially eliminating keystone distortions according to claim 20 wherein the external unit collects the keystone correction data based upon the standard image data containing vertical and horizontal line segments with equal lengths on the image-projection surface to form a projected image containing respective projected vertical and horizontal line segments, and wherein a ratio in length between the projected vertical and horizontal line segments is determined, the ratio being the predetermined focus data.

25. The apparatus for substantially eliminating keystone distortions according to claim 20, wherein the keystone correction data includes a predetermined number of pairs of coordinates of an image of a predetermined shape and corresponding pairs of coordinates of a projected image of the predetermined shape.

26. A method of substantially eliminating keystone distortion in a projected image, comprising the steps of:

projecting an image on an image-projection surface from an image-forming source at a non-perpendicular angle, the projected image containing keystone distortion;

specifying at least two points with respect to the image-projection surface to define a desired projection area;

generating keystone distortion correction data based upon the points specified on the image-projection surface; and

correcting the keystone distortion in the projected image based upon the keystone distortion correction data.

27. The method of substantially eliminating keystone distortion according to claim 26 wherein the points include four corners of the desired projection area that is rectangular.

28. The method of substantially eliminating keystone distortion according to claim 26 wherein the points include four corners of the desired projection area that is square.

29. The method of substantially eliminating keystone distortion according to claim 26 wherein said specifying step further comprises additional steps of:

moving a cursor via a pointing device, the cursor being projected on the image-projection surface; and

clicking on the pointing device to specify one of the points for the desired projection area.

30. The method of substantially eliminating keystone distortion according to claim 29 wherein the pointing device is a mouse.

31. The method of substantially eliminating keystone distortion according to claim 29 wherein the pointing device is a wireless remote control device.

32. The method of substantially eliminating keystone distortion according to claim 26 wherein said specifying step further comprises an additional step of inputting numerical coordinates.

33. The method of substantially eliminating keystone distortion according to claim 26 wherein said specifying step further comprises additional steps of:

moving a cursor to a desired position via a keyboard, the cursor being projected on the image-projection surface; and

entering the desired position as one of the points by the keyboard.

34. The method of substantially eliminating keystone distortion according to claim 26 wherein the projected image is predetermined image.

35. The method of substantially eliminating keystone distortion according to claim 26 wherein the keystone distortion correction data includes parameters in a matrix.

36. The method of substantially eliminating keystone distortion according to claim 26 wherein the keystone distortion correction data includes an equation.

37. The method of substantially eliminating keystone distortion according to claim 26 wherein the keystone distortion correction data includes a look table.

38. The method of substantially eliminating keystone distortion according to claim 26 wherein said correcting step further includes an additional step of mechanically adjusting a parameter selected from the group consisting of an optical axis of an optical component and a tilting angle of the image-forming source with respect to the image-projection surface.

39. The method of substantially eliminating keystone distortion according to claim 26 wherein said correcting step further includes an additional step of correcting the image at the image-forming source.

40. An apparatus for substantially eliminating keystone distortion in a projected image, comprising:

an image-forming source for generating an image to be projected;

an optical unit connected to said image-forming source for projecting the image on an image-projection surface;

an input unit for specifying at least two points with respect to the image-projection surface to define a desired projection area, the image being projected to the image-projection surface, the projected image containing keystone distortion;

a calculation unit in response to said input unit for generating keystone distortion correction data based upon the points specified on the image-projection surface; and

a correction unit connected to said calculation unit for correcting the keystone distortion in the projected image based upon the keystone distortion correction data.

41. The apparatus for substantially eliminating keystone distortion according to claim 40 wherein said input unit specifies four points representing four corners of the desired projection area that is rectangular.

42. The apparatus for substantially eliminating keystone distortion according to claim 40 wherein said input unit specifies four points repesenting four corners of the desired projection area that is square.

43. The apparatus for substantially eliminating keystone distortion according to claim 40 wherein said input further comprises a pointing device for indicating a cursor, the cursor being projected on the image-projection surface, said pointing device clicking to specify one of the points for the desired projection area.

44. The apparatus for substantially eliminating keystone distortion according to claim 43 wherein said pointing device is a mouse.

45. The apparatus for substantially eliminating keystone distortion according to claim 43 wherein said pointing device is a wireless remote control.

46. The apparatus for substantially eliminating keystone distortion according to claim 40 wherein said input unit inputs numerical coordinates representing the points.

47. The apparatus for substantially eliminating keystone distortion according to claim 40 wherein said input unit further comprises a keyboard for moving a cursor to a desired position, the cursor being projected on the image-projection surface, said keyboard entering the desired position as one of the points.

48. The apparatus for substantially eliminating keystone distortion according to claim 40 wherein the projected image is predetermined image.

49. The apparatus eliminating keystone distortion according to claim 40 wherein the keystone distortion correction data includes a matrix.

50. The apparatus for substantially eliminating keystone distortion according to claim 40 wherein said correction unit further includes an angle adjustment unit for mechanically adjusting a parameter selected from the group consisting of an optical axis of an optical component and a tilting angle of the image-forming source with respect to the image-projection surface.

51. The apparatus for substantially eliminating keystone distortion according to claim 40 wherein said correction unit is connected to said image-forming source for correcting the image at said image-forming source.

52. A system for substantially eliminating keystone distortion in a projected image with a device for projecting an image on an image-projection surface, comprising:

an image-forming source for generating the image to be projected;

an input unit for specifying at least two points with respect to the image-projection surface to define a desired projection area, the image being projected to the image-projection surface, the projectd image containing keystone distortion;

a calculation unit in response to said input unit for generating keystone distortion correction data based upon the points specified on the image-projection surface; and

a correction unit connected to said calculation unit for correcting the keystone distortion in the projected image based upon the keystone distortion correction data.

53. A system for substantially eliminating keystone distortion in a projected image with a computer, the computer having an input unit for specifying at least two points with respect to an image-projection surface to define a desired projection area, the image being projected to the image-projection surface, the projected image containing keystone distortion, the computer generating keystone distortion correction data based upon the points specified on the image-projection surface, comprising:

an image-forming source for generating an image to be projected;

an optical unit connected to said image-forming source for projecting the image on the image-projection surface; and

a correction unit connected to the computer for correcting the keystone distortion in the projected image based upon the keystone distortion correction data.

54. A system for substantially eliminating keystone distortion in a projected image with a computer for correcting the keystone distortion in the projected image based upon keystone distortion correction data, comprising:

an image-forming source for generating an image to be projected;

an optical unit connected to said image-forming source for projecting the image on an image-projection surface;

an input unit for specifying at least two points with respect to the image-projection surface to define a desired projection area, the image being projected to the image-projection surface, the projected image containing keystone distortion; and

a calculation unit in response to said input unit for generating the keystone distortion correction data based upon the points specified on the image-projection surface.

55. A system for substantially eliminating keystone distortion in a projected image, comprising:

a device for projecting an image onto an image-projection surface, the projected image containing keystone distortion;

an input unit for specifying at least two points with respect to the image-projection surface to define a define a desired projection area; and

a computer connected to said input unit for generating an image to be projected on the image-projection surface, the computer in response to said input unit for generating keystone distortion correction data based upon the points specified on the image-projection surface, the computer correcting the keystone distortion in the projected image based upon the keystone distortion correction data.

56. A system for substantially eliminating keystone distortion in a projected image, comprising:

an input unit specifying at least two points with respect to the image-projection surface to define a desired projection area;

a computer connected to said input unit for generating an image to be projected onto the image-projection surface, the computer in response to said input unit for generating keystone distortion correction data based upon the points specified on the image-projection surface, the computer correcting the keystone distortion in the projected image based upon the keystone distortion correction data; and

a device connected to said computer for projecting an image onto the image-projection surface, the projected image containing keystone distortion, the device correcting the keystone distortion in the projection image based upon the keystone distortion correction data.

57. A software program for substantially eliminating keystone distortion in a projected image, the software program residing on a computer and receiving input points, the software program comprising:

an image formation module for forming an image to be projected onto the image-projection surface;

a calculation module for generating keystone distortion correction data based upon the input points specified on the image-projection surface; and

a correction module in response to said calculation module for correcting the keystone distortion in the projected image based upon the keystone distortion correction data.

58. A software program for substantially eliminating keystone distortion in a projected image, the software program residing in a computer and a device connected to the computer, the software program comprising:

an image formation module residing in the computer for forming an image to be projected onto the image-projection surface;

a calculation module residing in the device for generating keystone distortion correction data based upon input points specified on the image-projection surface; and

a correction module residing in the device in response to said calculation module for correcting the keystone distortion in the projected image based upon the keystone distortion correction data.