System and method for producing an image with a screen using erase (off) and image (on) light sources

• US 7,180,555 B2
• Filed: 05/15/2001
• Issued: 02/20/2007
• Est. Priority Date: 05/15/2001
• Status: Expired due to Fees

• Current Assignee: Microvision, Inc.
• Original Assignee: Microvision, Inc.
• Inventors: Tegreene, Clarence T., Lewis, John R.
• Primary Examiner(s): Yenke; Brian P.
• Application Number:
  US09/858,287
• Publication Number:
  US 20020171937A1
• Time in Patent Office: 2,107 Days
• Field of Search: 348/744, 348/745, 348/753, 348/763, 348/768, 348/777, 348/786, 348/811, 359/495
• US Class Current: 348/744
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
• CPC Class Codes: H04N 5/7491 of head mounted projectors
• CPC Class Codes: H04N 9/3102 using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13
• 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

Abstract

An image system includes a beam generator and a screen having a region with an adjustable brightness. The beam generator directs first and second electromagnetic beams onto the region. The first beam changes the brightness of the region according to a first polarity and the second beam changes the brightness of the region according to a second polarity. Such an imaging system can generate a video frame on a projection screen such that each pixel of the frame is “on” for the same or approximately the same amount of time as each of the other pixels. This technique prevents portions of the image from appearing visibly dimmer than other portions. It also allows the persistence of the screen regions to be relatively long, e.g., longer than the frame rate, and thus allows the screen to display/project relatively high-quality video frames.

Claims

1. An image system, comprising:

a projection screen including a scan surface and a projection surface having a region of adjustable brightness, the scan surface parallel or substantially paraller to the projection surface; and

a beam generator operable to simultaneously direct an electromagnetic off-beam and an electromagnetic on-beam onto respective first and second regions of the scan surface from a single side of the projection screen, the regions of the scan surface perpendicularly aligned or substantially perpendicularly aligned with respective first and second regions of the projection surface, the off- and on-beams narrower than a dimension of the projection screen at the scan surface, the off-beam operable to change the brightness of the first region of the projection surface to a selected off-condition, and the on-beam operable to change the brightness of the second region of the projection surface from the selected off-condition to a desired brightness level.

2. The image system of claim 1 wherein the beam generator is operable to generate the on-and off-beams during non-overlapping time periods.

3. The image system of claim 1, further comprising:

a display screen that faces the projection surface of the projection screen; and

wherein the projection screen is operable to project an image onto the display screen.

4. The image system of claim 1 wherein:

the projection surface has a plurality of regions of adjustable brightness;

the off-beam is operable to change the respective brightness of each region of the projection surface to the selected off-condition; and

the on-beam is operable to change the brightness of at least one of the regions of the projection surface to a first brightness level that is different from the off condition and another of the regions of the projection surface to a second brightness level different from the first brightness level and the off-condition.

5. The image system of claim 1 wherein the scan surface is different from and faces away from the projection surface.

6. The image system of claim 1 wherein the scan surface and the projection surface are the same surface.

7. The image system of claim 1 wherein the scan surface is disposed on the side of the projection screen from which the beam generator directs the electromagnetic on-beam and the electromagnetic off-beam.

8. The image system of claim 1 wherein:

the scan surface is parallel to the projection surface;

the beam generator is operable to respectively direct the off-beam and on-beam onto first and second regions of the scan surface that are perpendicularly aligned or substantially perpendicularly aligned with the first and second regions, respectively, of the projection surface;

the brightness of the first region of the projection surface is operable to change to the selected off-condition in response to the off-beam striking the first region of the scan surface; and

the brightness of the second region of the projection surface is operable to change from the selected off-condition to the desired brightness level in response to the on-beam striking the second region of the scan surface.

9. An image system, comprising:

a screen having first and second regions responsive to electromagnetic energy to produce an adjustable brightness; and

a beam generator operable to simultaneously direct first and second electromagnetic beams onto the first and second regions, respectively, from a single side of the screen, the first and second beams being narrower than a dimension of the screen at the screen, the first beam operable to change the brightness of the first region according to a first polarity and the second beam operable to change the brightness of the second region according to a second polarity.

10. The image system of claim 9 wherein the beam generator is operable to direct the first beam onto the second region before directing the second beam onto the second region.

11. The image system of claim 9 wherein the first beam is different than the second beam.

12. The image system of claim 9 wherein:

the second beam has an intensity; and

the second beam is operable to change the brightness of the second region to a brightness level that is related to the intensity.

13. The image system of claim 9 wherein:

the second beam has a duration; and

the second beam is operable to change the brightness of the second region to a brightness level that is related to the duration.

14. The image system of claim 9 wherein the first beam has a different wave length than the second beam.

15. The image system of claim 9 wherein:

the first beam is operable to decrease the brightness of the first region; and

the second beam is operable to inclease the brightness of the second region.

16. The image system of claim 9 wherein:

the screen has multiple regions of adjustable brightness;

the beam generator is operable to direct the first and second beams onto the regions;

the first beam is operable to change the respective brightnesses of the regions of the screen according to the first polarity; and

the second beam is operable to change the brightness of at least one of the regions of the screen according to the second polarity.

17. The image system of claim 9, further comprising an illuminator operable to illuminate the screen.

18. The image system of claim 9 wherein:

the brightness of the first region of the screen is operable to change according to the first polarity in response to the first beam impinging on the first region; and

the brightness of the second region is operable to change according to the second polarity in response to the second beam impinging on the second region.

19. An image system, comprising:

a screen having first and second regions with adjustable reflectivities; and

a beam generator operable to simultaneously direct first and second electromagnetic beams onto the first and second regions, respectively, from a same side of the screen, the first and second beams being narrower than a dimension of the screen at the screen, the first beam operable to change the reflectivity of the first region according to a polarity and the second beam operable to change the reflectivity of the second region according to an opposite polarity.

20. The image system of claim 19 wherein:

the second beam has an intensity; and

the second beam is operable to change the reflectivity of the second region to a reflectivity level that is related to the intensity.

21. The image system of claim 19 wherein:

the second beam has a duration; and

the second beam is operable to change the reflectivity of the second region to a reflectivity level that is related to the duration.

22. The image system of claim 19, further comprising an illuminator operable to illuminate the screen.

23. The image system of claim 19 wherein:

the direction corresponds to increasing the reflectivity; and

the opposite direction corresponds to decreasing the reflectivity.

24. The image system of claim 19 wherein:

the projection screen has multiple regions of adjustable reflectivity;

the beam generator is operable to direct the first and second beams onto the regions;

the first beam is operable to change the respective reflectivities of the regions of the projection screen according to the polarity; and

the second beam is operable to change the reflectivity of at least one of the regions of the projection screen according to the opposite polarity.

25. The image system of claim 19 wherein:

the reflectivity of the first region of the screen is operable to change according to the polarity in response to the first beam being incident on the first region; and

the reflectivity of the second region is operable to change according to the opposite polarity in response to the second beam being incident on the second region.

26. An image system, comprising:

a projection screen having a scan surface and a projection surface that faces away from and that is parallel to the scan surface, the projection surface having regions of adjustable reflectivity; and

a beam generator operable to simultaneously direct an electromagnetic off beam and an electromagnetic on beam onto first and second regions of the scan surface from a single side of the projection screen, the first and second regions of the scan surface perpendicularly aligned with respective first and second regions of the projection surface, the off and on beams being narrower than a dimension of the projection screen at the projection screen, the off beam operable to change the reflectivity of the first region of the projection surface according to a first polarity and the on beam operable to change the reflectivity of the second region of the projection surface according to second polarity.

27. The image system of claim 26, further comprising:

an illuminator operable to illuminate the projection surface of the projection screen;

a display screen that faces the projection surface of the projection screen; and

wherein the projection screen is operable to project an image onto the display screen.

28. The image system of claim 26 wherein:

the off beam is operable to change the respective reflectivity of each region of the projection surface according to the first polarity; and

the on beam is operable to change the reflectivity of at least one of the regions of the projection surface according to the second polarity.

29. The image system of claim 26 wherein:

the scan surface is parallel to the projection surface;

the beam scanner is operable to direct the off beam and on beam onto respective first and second regions of the scan surface that are perpendicularly aligned with the first and second regions of the projection surface, respectively;

the reflectivity of the first region of the projection surface is operable to change according to the first polarity in response to the off beam striking the first region of the scan surface; and

the reflectivity of the second region of the projection surface is operable to change according to the opposite polarity in response to the on beam striking the second region of the scan surface.

30. A display, comprising:

a screen having first and second regions with an adjustable luminance; and

a beam generator operable to simultaneously direct an electromagnetic erase beam and an electromagnetic image beam onto the first and second regions, respectively, from a same side of the screen, the erase and image beams being narrower than a dimension of the screen at the screen, the erase beam operable to set the luminance of the first region to a predetermined level and the image beam operable to change the luminance of the second region to a level other than the predetermined level.

31. The display system of claim 30 wherein the beam generator is operable to direct the erase beam onto the second region before directing the image beam onto the second region.

32. The display system of claim 30 wherein:

the image beam has an intensity; and

the image beam is operable to change the luminance of the second region to a level that is related to the intensity.

33. The display system of claim 30 wherein:

the image beam has a duration; and

the image beam is operable to change the luminance of the second region to a level that is related to the duration.

34. The display system of claim 30 wherein:

the projection screen has more than two regions of adjustable luminance;

the beam generator is operable to direct the erase beam and the image beam onto the regions;

the erase beam is operable to set the respective luminances of the regions of the projection screen to the predetermined level; and

the image beam is operable to change the luminance of at least one of the regions of the projection screen to the level other than the predetermined level.

35. The display system of claim 30, further comprising an illuminator operable to illuminate the pmjection screen.

36. The display of claim 30 wherein:

the luminance of the first region of the screen is operable to have the predetermined level in response to the erase beam being incident on the first region; and

the luminance of the second region is operable to change to a level other than the predetermined level in response to the image beam being incident on the second region.

37. An image system, comprising:

a projection screen having a scan surface and a projection surface that faces away from the scan surface, the projection surface having regions of adjustable luminance;

a beam generator operable to simultaneously and respectively direct an electromagnetic erase beam and an electromagnetic image beam onto first and second regions of the scan surface from a same side of the projection screen, the erase and image beams narrower than a dimension of the projection screen at the projection screen, the erase beam operable to set the luminance of a corresponding first region of the projection surface to a predetermined level and the image beam operable to change the luminance of a corresponding second region of the projection surface to a level other than the predetermined level;

wherein the scan surface is parallel to the projection surface; and

wherein the first and second regions of the scan surface are perpendicularly aligned with the corresponding first and second regions, respectively, of the projection surface.

38. The image system of claim 37 wherein:

the projection surface has more than two regions of adjustable luminance;

the erase beam is operable to set the respective luminance of each region of the projection surface to the predetermined level; and

the image beam is operable to change the luminance of at least one of the regions of the projection surface to a level other than the predetermIned level.

39. The image system of claim 37 wherein:

the scan surface is parallel to the projection surface;

the beam generator is operable to direct the erase beam and image beam onto respective first and second regions of the scan surface that are perpendicularly aligned with the first and second regions of the projection surface, respectively; and

the luminance of the first region of the projection surface is operable to have the predetermined level in response to the erase beam impinging on the first region of the scan surface; and

the luminance of the second region of the projection surface is operable to change to a level other than the predetermined level in response to the image beam impinging on the second region of the scan surface.

40. An image system, comprising:

a screen having regions with an adjustable luminance; and

a light emitter operable to simultaneously direct an erase light and a write light onto respective first and second regions from a single side of the screen, the erase and write lights narrower than a dimension of the screen at the screen, the erase light operable to set the luminance of the first region to a predetermined level and the write light operable to change the luminance of the second region to a level other than the predetermined level.

41. The image system of claim 40 wherein the erase and write lights are visible.

42. The image system of claim 40 wherein the erase and write lights are invisible.

43. The image system of claim 40 wherein the light emitter comprises an organic light-emitting device that is operable to generate the erase light.

44. The image system of claim 40 wherein:

the regions comprise respective lines of the screen; and

the light emitter comprises a row of devices operable to generate the erase light.

45. The image system of claim 40 wherein:

the regions comprise respective lines of the screen; and

the light emitter comprises a row of organic light-emitting devices operable to generate the erase light.

46. The image system of claim 40 wherein:

the luminance of the first region of the screen is operable to have the predetermined level in response to the erase light striking the first region; and

the luminance of the second region of the screen is operable to change to a level other than the predetermined level in response to the write light striking the second region.

47. An image system, comprising:

a screen having regions with an adjustable luminance; and

a light emitter operable to simultaneously direct a first light at an erase wavelength and a second light at a write wavelength onto respective first and second regions from a single side of the screen, the first and second lights narrower than a dimension of the screen at the screen, the first light operable to set the luminance of the first region to a predetermined level and the second light operable to change the luminance of the second region to a level other than the predetermined level.

48. The image system of claim 47 wherein the erase and write wavelengths are in a visible portion of the electromagnetic spectrum.

49. The image system of claim 47 wherein the erase and write wavelengths are in an invisible portion of the electromagnetic spectrum.

50. The image system of claim 47 wherein:

the luminance of the first region of the screen is operable to have the predetermined level in response to the first light being incident on the first region; and

the luminance of the second region of the screen is operable to change to a level other than the predetermined level in response to the second light being incident on the second region.

51. A method, comprising:

changing the brightness of a first region of an image screen according to a first polarity with a first electromagnetic beam that is incident on the first region of the image screen from a direction and that is narrower than a dimension of the image screen at the image screen; and

simultaneously changing the brightness of a second region according to a second polarity with a second electromagnetic beam that is incident on the second region of the image screen from the direction and that is narrower than a dimension of the image screen at the image screen.

52. The method of claim 51, further comprising changing the brightness of the second region of the image with the first beam before changing the brightness of the second region with the second beam.

53. The method of claim 51 wherein the first beam has a different characteristic than the second beam.

54. The method of claim 51 wherein:

changing the brightness of the first region according to the first polarity comprises decreasing the brightness of the first region; and

changing the brightness of the second region according to the second polarity comprises increasing the brightness of the second region.

55. The method of claim 51 wherein changing the brightness of the second region in the second direction comprises setting the brightness of the second region to a level that is proportional to the intensity of the second beam.

56. The method of claim 51 wherein changing the brightness of the second region in the second direction comprises setting the brightness of the second region to a level that is proportional to the duration of the second beam.

57. The method of claim 51, further comprising illuminating the first and second regions of the screen.

58. The method of claim 51 wherein the changing the brightness of the first region in the first direction comprises setting the brightness of the first region to a predetermined level.

59. The method of claim 51 wherein:

changing the brightness of the first region according to the first polarity comprises scanning a scan surface of the image screen with the first beam; and

changing the brightness of the second region according to the second polarity comprises scanning the scan surface of the image screen with the second beam.

60. The method of claim 51, further comprising generating the first and second beams during different time periods.

61. The method of claim 51 wherein:

changing the brightness of the first region of the image screen according to the first polarity comprises changing the reflectivity of the first region according to the first polarity with the first beam; and

changing the brightness of the second region according to the second polarity comprises changing the reflectivity of the second region according to the second polarity with the second beam.

62. The method of claim 51 wherein:

changing the brightness of the first region of the image screen according to the first polarity comprises changing the brightness of the first region according to the first polarity in response to the first electromagnetic beam being incident on the first region; and

changing the brightness of the second region according to the second polarity comprises changing the brightness of the second region according to the second polarity in response to the second electromagnetic beam being incident on the second region.

63. An image system, comprising:

a projection screen including a scan surface and a projection surface having regions of adjustable brightness; and

a beam generator operable to simultaneously direct an electromagnetic off-beam and a spatially separate electromagnetic on-beam onto first and second regions, respectively, of the scan surface from a same direction, the off-beam operable to change the brightness of a first region of the projection surface that is substantially perpendicularly aligned with the first region of the scan surface to a selected off-condition and the on-beam operable to change the brightness of a second region of the projection surface that is substantially perpendicularly aligned with the second region of the scan surface from the selected off-condition to a desired brightness level.

64. A method, comprising:

changing the brightness of a first region of an image screen according to a first polarity with a first electromagnetic beam that is incident on the first region; and

simultaneously changing the brightness of a second region of the image screen according to a second polarity with a second electromagnetic beam that is incident on the second region, the first and second beams striking the image screen from a same direction.