Point source scanning apparatus and method

• US 6,046,720 A
• Filed: 05/04/1998
• Issued: 04/04/2000
• Est. Priority Date: 05/07/1997
• Status: Expired due to Term

• Current Assignee: Washington University In St Louis
• Original Assignee: University of Washington
• Inventors: Tidwell, Michael, Melville, Charles D.
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): NGUYEN, KEVIN M
• Application Number:
  US09/072,013
• Time in Patent Office: 701 Days
• Field of Search: 345/7, 345/8, 345/9, 345/108, 345/111, 359/198, 359/199, 359/213, 359/214, 359/223, 359/630, 359/631
• US Class Current: 345/108
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/02 by tracing or scanning a light beam on a screen
• CPC Class Codes: G09G 3/025 with scanning or deflecting the beams in two directions or dimensions

Abstract

A scanning display device directly scans a light source along at least one scanning path, rather than scanning a light beam emitted from such source along such scanning path. By scanning the light source a smaller, lighter weight scanner without a mirror can be used to achieve light source scanning along the desired scan path. A resonant cantilever translates one or more point sources (e.g., one for a monochromatic display; red, green and blue for an RGB display). The cantilever motion is driven by an electromagnetic drive circuit or by a piezoelectric drive actuator. The light source is one or more light emitting diode point sources, one or more a fiber optic point sources, or one or more light emitting polymer light sources.

Claims

1. A scanning display apparatus, comprising:

an image signal source operative to produce an image signal;

a scanning signal source generating a scanning signal;

a light emitter coupled to the image signal source and responsive to the image signal to emit light;

a support carrying the light emitter at a first portion of the support; and

a drive circuit coupled to the support and responsive to the scanning signal to move at least the first portion of the support through a predetermined angular range, wherein the light emitter is moved through said predetermined angular range to scan the emitted light along a desired scan path.

2. The apparatus of claim 1, in which the light emitter comprises a plurality of light emitting devices emitting respective beams of light, and wherein the respective beams of light scan an image.

3. The apparatus of claim 2, in which the respective beams of light are of a monotone.

4. The apparatus of claim 2, in which the respective beams of light are of a differing color.

5. The apparatus of claim 1, in which the light emitter comprises a point source of light and a modulator positioned to receive the emitted light and responsive to the image signal.

6. The apparatus of claim 1, in which the light emitter is directly modulated in response to the image signal.

7. The apparatus of claim 1, in which the light emitter comprises a light emitting diode.

8. The apparatus of claim 1, in which the light emitter comprises a plurality of light emitting diodes of differing wavelength.

9. The apparatus of claim 1, in which the light emitter comprises a plurality of light emitting diodes of the same wavelength.

10. The apparatus of claim 1, in which the light emitter comprises a fiber optic.

11. The apparatus of claim 1, in which the light emitter comprises a light emitting plasma.

12. The apparatus of claim 1, in which the light emitter comprises a plurality of light emitting devices emitting respective beams of colored light, wherein the plurality of light emitting devices are aligned in a common plane, wherein the movement of the plurality of light emitters caused by the drive circuit occurs with the common plane, and wherein the image signal is operative with a timing to modulate each one of the light emitters to define an image pixel of a desired color at a given pixel location as each one of the light emitters is in position to address said image pixel.

13. The apparatus of claim 1, in which the drive circuit is an electromagnetic drive circuit.

14. The apparatus of claim 13, further comprising a clamp, in which the drive circuit comprises an electromagnetic coil and a permanent magnet, in which the support comprises a cantilever spring responsive to a changing magnetic field, the cantilever spring having a first end held fixed relative to the permanent magnet by the clamp and a second end which moves through said predetermined angular range in response to the changing magnetic field, and wherein the electromagnetic coil receives the scanning signal and in response generates the changing magnetic field.

15. The apparatus of claim 1, in which the drive circuit comprises a piezoelectric actuator.

16. The apparatus of claim 1, wherein the support and light emitter move at a resonant frequency of said support and light emitter.

17. The apparatus of claim 1, wherein the drive circuit moves the support through the predetermined angular range at a resonant frequency of said support and light emitter.

18. The apparatus of claim 1, wherein the scanning signal is a periodic, display synchronization signal.

19. The apparatus of claim 1, wherein the support is a cantilever spring and the movement of the cantilever spring is a twisting motion which causes the light emitter to rotate about an axis of rotation.

20. The apparatus of claim 1, further comprising an eyepiece receiving the emitted light, and wherein the emitted light is focused to define an exit pupil at a location adjacent the eyepiece where a viewer'"'"'s eye may be positioned to perceive an image generated by the apparatus.

21. The apparatus of claim 1, in which the desired scan path occurs along a first axis, and further comprising a scanner having a mirror which receives the emitted light to deflect the emitted light along a second axis.

22. The apparatus of claim 20, in which the first axis is a horizontal axis and the second axis is a vertical axis, and the deflected emitted light moves along a raster pattern to scan an image.

24. The apparatus of claim 22, in which the light emitter comprises a plurality of light emitting devices emitting respective beams of light, and wherein the respective beams of light scan an image.

25. The apparatus of claim 22, in which the light emitter comprises a point source of light and a modulator positioned to receive the emitted light and responsive to the image signal.

26. The apparatus of claim 22, in which the light emitter comprises a light emitting diode.

27. The apparatus of claim 22, in which the light emitter comprises a fiber optic.

28. The apparatus of claim 22, in which the light emitter comprises a light emitting plasma.

30. The apparatus of claim 28, in which the first axis is a horizontal axis and the second axis is a vertical axis, and the emitted light moves along a raster pattern to scan the image.

31. The apparatus of claim 28, in which the light emitter comprises a plurality of light emitting devices emitting respective beams of colored light, and wherein the respective beams of colored light scan an image.

32. The apparatus of claim 28, in which the light emitter comprises a light emitting diode.

33. The apparatus of claim 28, in which the light emitter comprises a fiber optic.

34. The apparatus of claim 32, in which the drive circuit is an electromagnetic drive circuit.

35. The apparatus of claim 32, in which the drive circuit comprises a piezoelectric actuator.

36. The apparatus of claim 32, wherein the drive circuit moves the support through the predetermined angular range at a resonant frequency of said support and light emitter.

39. The apparatus of claim 28, in which the drive circuit is an electromagnetic drive circuit.

40. The apparatus of claim 28, in which the drive circuit comprises a piezoelectric actuator.

41. The apparatus of claim 28, wherein the drive circuit moves the support through the predetermined angular range at a resonant frequency of said support and light emitter.

42. The apparatus of claim 28, wherein the support is a cantilever spring and the movement of the cantilever spring is a twisting motion which causes the light emitter to rotate about an axis of rotation.

44. The method of claim 42, in which the scanning signal is periodic having a period which includes a first portion and a second portion, and in which the step of moving comprises:

during the first portion of the scanning signal period, driving motion of the support and light emitter in a first direction to a first extreme position in response to the scanning signal;

during a second portion of the scanning signal period, driving motion of the support and light emitter in a second direction opposite the first direction to a second extreme position in response to the scanning signal; and

repeating the steps of receiving, driving in a first direction and driving in a second direction for subsequent periods of the scanning signal to generate oscillatory motion of the support and light emitter in alternating first and second directions during the respective first and second portions of said subsequent scanning signal periods to scan a plurality of lines of image pixel components of an image.

45. The method of claim 42, in which the support carries a plurality of light emitters, and wherein the step of modulating comprises modulating the plurality of light emitters with the image signal to generate respective modulated light beams at a timing which creates image color pixels.

46. The method of claim 42, further comprising the step of receiving the emitted light at an eyepiece which focuses the emitted light to define an exit pupil at a location adjacent the eyepiece where a viewer'"'"'s eye may be positioned to perceive an image.

47. The method of claim 42, in which the desired scan path occurs along a first scanning axis, and further comprising the step of:

receiving the emitted light at a scanner mirror which moves relative to a second scanning axis; and

deflecting the emitted light with the mirror along the second scanning axis.

48. The method of claim 46, in which the first scanning axis is a horizontal axis and the second scanning axis is a vertical axis, and wherein the deflected emitted light moves along a raster pattern to scan an image.

49. The method of claim 42, in which the support is responsive to a changing magnetic field, and further comprising the step of generating a changing magnetic field with the drive circuit in response to the scanning signal to drive motion of the support.

50. The method of claim 42, in which the support is coupled to a piezoelectric actuator, and further comprising the step of deforming the piezoelectric actuator in response to the scanning signal to drive motion of the support.

51. The method of claim 42, in which the light emitter is a point source of light, and in which the step of modulating comprises modulating the point source with the image signal to generate modulated light defining, over time, a plurality of image pixel components.

52. The method of claim 42, in which the light emitter comprises a plurality of point sources of light of respective color, wherein the plurality of point sources are aligned in a common plane, in which the step of modulating comprises modulating the plurality of point sources with the image signal, in which the step of moving comprises moving the plurality of point sources through the predetermined angular range in the common plane, and wherein the image signal is operative with a timing to modulate each one of the point sources so that the plurality of point sources cumulatively define an image pixel of a desired color at a given pixel location as each one of the plurality of point sources is in position to address said image pixel.

53. The method of claim 42, in which the support carries a plurality of light emitters which output respective beams of light, and wherein the step of modulating comprises modulating the respective beams of light with the image signal to generate respective modulated light beams at a timing which creates image color pixels.

23. A scanning display apparatus, comprising:

an image signal source operative to produce an image signal;

a scanning signal source generating a scanning signal;

a light emitter coupled to the image signal source and responsive to the image signal to emit light;

a support carrying the light emitter at a first portion of the support and moving in response to the scanning signal to move at least the first portion of the support through a predetermined angular range, wherein the light emitter is moved through said predetermined angular range to scan the emitted light along a desired scan path.

29. A retinal scanning display apparatus, comprising:

an image signal source operative to produce an image signal;

a scanning signal source generating a first periodic scanning signal and a second periodic scanning signal;

a light emitter coupled to the image signal source and responsive to the image signal to emit light;

a support carrying the light emitter at a first portion of the support;

a drive circuit coupled to the support and responsive to the first scanning signal to move at least the first portion of the support through a predetermined angular range, wherein the light emitter is moved through said predetermined angular range to scan the emitted light along a desired scan path for a first scanning axis;

a scanner for scanning the emitted light along a second scan path for a second scanning axis; and

an eyepiece receiving the emitted light being scanned for the first scanning axis and the second scanning axis, wherein the emitted light is focused to define an exit pupil at a location adjacent the eyepiece where a viewer'"'"'s eye may be positioned to perceive an image.

38. The apparatus of claim 38, in which the light emitter comprises a plurality of light emitting devices emitting respective beams of colored light, wherein the plurality of light emitting devices are aligned in a common plane, wherein the movement of the plurality of light emitters caused by the drive circuit occurs with the common plane, and wherein the image signal is operative with a timing to modulate each one of the light emitters to define an image pixel of a desired color at a given pixel location as each one of the light emitters is in position to address said image pixel.

37. The apparatus of claim 38, in which the light emitter comprises a light emitting plasma.

43. A method of scanning an optical beam responsive to a scanning signal, comprising the steps of:

modulating a light emitter with an image signal to generate a modulated light beam of image pixel components;

receiving a scanning signal at a drive circuit operative to drive motion of a support, the support carrying the light emitter;

moving the support through a predetermined angular range as controlled by the drive circuit, wherein the light emitter is moved through said predetermined angular range with the support to scan the emitted light along a desired scan path.