Servo-assisted scanning beam display systems using fluorescent screens

• US 20070188417A1
• Filed: 09/01/2006
• Published: 08/16/2007
• Est. Priority Date: 02/15/2006
• Status: Active Grant

• Current Assignee: Prysm Systems, Inc.
• Original Assignee: Prysm, Inc.
• Inventors: Uebbing, John, Krall, Donald A., Hajjar, Roger A., Malyak, Phillip H., Kent, David L., Burroughs, Alan C., Pajdowski, Mark A.
• Granted Patent: US 8,451,195 B2
• Time in Patent Office: Days
• US Class Current: 345/75.100
• 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 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 3/02 by tracing or scanning a light beam on a screen
• 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

Abstract

Scanning beam display systems using fluorescent screens and various servo feedback control mechanisms to control display imaging qualities.

Claims

1. A scanning beam display system, comprising:

an optical module operable to produce a scanning beam of excitation light having optical pulses that are sequential in time and carry image information;

a fluorescent screen which absorbs the excitation light and emits visible fluorescent light to produce images carried by the scanning beam; and

an optical sensor positioned to receive a feedback optical signal generated by the fluorescent screen under illumination of the scanning beam and to produce a monitor signal indicating a spatial alignment of the optical pulses on the fluorescent screen,

wherein the optical module comprises a feedback control unit operable to adjust timing of the optical pulses carried by the scanning beam in response to the monitor signal to control the spatial alignment of spatial positions of the optical pulses on the fluorescent screen.

2. The system as in claim 1, wherein:

the screen comprises parallel fluorescent stripes which produce the images carried by the scanning beam, and servo reference marks respectively located at boundaries of the fluorescent stripes to produce the feedback optical signal under illumination of the scanning beam, wherein the feedback optical signal varies in amplitude with a position of the scanning beam across each fluorescent stripe, and

the optical module is operable to create a temporal variation in timing of the optical pulses in the scanning beam to shift positions of the optical pulses on the screen along a beam scanning direction perpendicular to the fluorescent stripes,

wherein the feedback control unit is operable to adjust timing of the optical pulses in response to information in the monitor signal to direct a position of each optical pulse towards a center of a fluorescent stripe along the beam scanning direction.

3. The system as in claim 2, wherein:

each servo reference mark is optically reflective.

4. The system as in claim 2, wherein:

each servo reference mark is optically fluorescent to emit the feedback light under illumination by the excitation light.

5. The system as in claim 4, wherein:

the feedback light is at a wavelength different from the light emitted by the screen.

6. The system as in claim 4, wherein:

the feedback light is invisible.

7. The system as in claim 2, wherein:

the temporal variation in timing of the optical pulses is a periodic variation in time.

8. The system as in claim 7, wherein:

the temporal variation in timing of the optical pulses is set to correspond to a spatial shift in a position of the scanning beam on the screen less than the width of the fluorescent stripes.

9. The system as in claim 2, wherein:

the screen comprises a start of line servo reference mark outside the fluorescent stripes in a beam scanning path perpendicular to the fluorescent stripes, the start of line servo reference mark producing a start of line servo feedback light when illuminated by the scanning beam to indicate a position of the scanning beam from the fluorescent stripes,

wherein the system further comprising;

a start of line optical detector located to receive the start of line servo feedback light and to produce a start of line signal, and

wherein the optical module is operable to use the start of line signal to control the timing of the optical pulses to be at a time when the scanning beam reaches a beginning position of the fluorescent stripes.

10. The system as in claim 9, wherein:

the start of line servo reference mark is optically reflective.

11. The system as in claim 9, wherein:

the start of line servo reference mark is optically fluorescent.

12. The system as in claim 2, wherein:

the screen comprises a vertical beam position servo reference mark outside the fluorescent stripes in a beam scanning path perpendicular to the fluorescent stripes, the vertical beam position servo reference mark producing a vertical beam position servo feedback light when illuminated by the scanning beam to indicate an offset of a vertical beam position from a predetermined vertical beam position in a vertical direction that is parallel to the fluorescent stripes,

wherein the system further comprising;

an optical detector located to receive the vertical beam position servo feedback light and to produce a vertical beam position servo signal, and

wherein the optical module is operable to use the vertical beam position servo signal to control a direction of the scanning beam to reduce the offset of the vertical beam position on the screen.

13. The system as in claim 12, wherein:

the vertical beam position servo reference mark is optically reflective.

14. The system as in claim 12, wherein:

the vertical beam position servo reference mark is optically fluorescent.

15. The system as in claim 12, wherein:

the a vertical beam position servo reference mark comprises first and second servo marks separated from each other along the beam scanning path.

16. The system as in claim 15, wherein:

the optical module is operable to use a difference in reflection from the first and second servo marks to determine the direction of the offset of the vertical beam position on the screen.

17. The system as in claim 15, wherein:

the optical module is operable to use a time different in receiving optical signals from the first and second servo marks to determine the direction of the offset of the vertical beam position on the screen.

18. The system as in claim 2, wherein:

the screen comprises a beam focus sensing reference mark outside the fluorescent stripes in a beam scanning path perpendicular to the fluorescent stripes, the beam focus sensing reference mark producing a beam focusing servo feedback light when illuminated by the scanning beam to indicate a beam spot size of the scanning beam on the screen,

wherein the system further comprising;

an optical detector located to receive the beam focusing servo feedback light and to produce a beam focus servo signal, and

wherein the optical module is operable to use the beam focus servo signal to control a focus of the scanning beam to control the beam spot size of the scanning beam on the screen.

19. The system as in claim 18, wherein:

the beam focus sensing reference mark is optically reflective.

20. The system as in claim 18, wherein:

the beam focus sensing reference mark is optically fluorescent.

21. The system as in claim 18, wherein:

the beam focus sensing reference mark comprises periodic parallel stripe marks that are parallel to the fluorescent stripes and a spacing between two adjacent stripe marks and a width of each stripe mark are equal to a predetermined spot size on the screen along the beam scanning path.

22. The system as in claim 2, wherein:

the screen comprises a power sensing reference mark outside the fluorescent stripes in a beam scanning path perpendicular to the fluorescent stripes, the power sensing reference mark producing a servo feedback light when illuminated by the scanning beam to indicate a power level of the scanning beam on the screen,

wherein the system further comprising;

an optical detector located to receive the servo feedback light and to produce a servo signal, and

wherein the optical module is operable to use the servo signal to control a power of the scanning beam on the screen.

23. The system as in claim 22, wherein:

the power sensing reference mark is optically reflective.

24. The system as in claim 22, wherein:

the power sensing reference mark is optically fluorescent.

25. A method for controlling a scanning beam display system, comprising:

scanning a beam of excitation light modulated with optical pulses on a screen with parallel fluorescent stripes in a beam scanning direction perpendicular to the fluorescent stripes to excite the fluorescent strips to emit visible fluorescent light which forms images;

providing a temporal variation in timing of the optical pulses in the beam of excitation light to advance or delay a spatial position of each optical pulse along the beam scanning direction on the screen;

detecting a reflection of the beam of excitation light from the screen to produce a monitor signal whose amplitude varies with a position of the beam relative to a fluorescent stripe;

processing the monitor signal to obtain information on a spatial offset of a position of an optical pulse on the screen relative to a center of a fluorescent stripe; and

adjusting timing of the optical pulses in the beam of excitation light to reduce the spatial offset.

26. The method as in claim 25, further comprising:

using an amplitude of the monitor signal to indicate the presence of the spatial offset and a sign of the monitor signal to indicate the direction of the spatial offset.

27. The method as in claim 25, wherein:

the temporal variation in timing of the optical pulses is periodic.

28. The method as in claim 25, wherein:

the period of the temporal variation in timing of the optical pulses corresponds to a distance that the scanning beam moves on the screen that is greater than a group of fluorescent stripes.

29. The method as in claim 25, wherein:

the temporal variation in timing of the optical pulses corresponds to a spatial shift in a position of the scanning beam on the screen less than the width of the fluorescent stripes.

30. The method as in claim 25, further comprising:

providing a peripheral servo reference mark outside the fluorescent stripes in the beam scanning direction to produce a feedback light when illuminated by the scanning beam;

controlling the scanning beam to scan over the peripheral servo reference mark during a scan over the fluorescent area;

controlling the scanning beam to be in a CW mode when the scanning beam is scanning over the peripheral servo reference mark and to be in a pulsed mode to carry the optical pulses when the scanning beam is scanning over the fluorescent stripes;

using the feedback light form the peripheral servo reference mark to detect a beam parameter of the scanning beam; and

using the detected beam parameter to adjust the scanning beam.

31. The method as in claim 30, wherein:

the peripheral servo reference mark has a structure to produce a vertical beam position servo feedback light when illuminated by the scanning beam to indicate an offset of a vertical beam position from a predetermined vertical beam position in a vertical direction that is parallel to the fluorescent stripes.

32. The method as in claim 30, wherein:

the peripheral servo reference mark has a structure to produce a beam focusing servo feedback light when illuminated by the scanning beam to indicate a beam spot size of the scanning beam on the screen.

33. The method as in claim 30, wherein:

the peripheral servo reference mark produces a start of line servo feedback light when illuminated by the scanning beam to indicate a position of the scanning beam from the fluorescent stripes.

34. The method as in claim 30, wherein:

the peripheral servo reference mark has a structure to produce a servo feedback light when illuminated by the scanning beam to indicate a power level of the scanning beam on the screen.

35. A scanning beam display system, comprising:

an optical module operable to produce a scanning beam of excitation light having optical pulses that are sequential in time and carry image information;

a fluorescent screen comprising a fluorescent area and a peripheral servo reference mark area outside the fluorescent area,

wherein the fluorescent area absorbs the excitation light and emits visible fluorescent light to produce images carried by the scanning beam, and the fluorescent area comprises a plurality of first servo reference marks producing a first feedback optical signal under illumination of the scanning beam,

wherein the peripheral servo reference mark area comprises at least one second servo reference mark producing a second feedback optical signal underillumination of the scanning beam;

a first optical sensor positioned to receive the first feedback optical signal and to produce a first monitor signal indicating a spatial alignment of the optical pulses on the fluorescent screen; and

a second optical sensor positioned to receive the second feedback optical signal and to produce a second monitor signal indicating an optical property of the scanning beam on the fluorescent screen,

wherein the optical module comprises a feedback control unit operable to adjust the scanning beam in response to the first and second monitor signals to control at least the spatial alignment of spatial positions of the optical pulses on the fluorescent screen.

36. The system as in claim 35, wherein:

the second peripheral servo reference mark includes a start of line servo reference mark having a fixed spacing from the fluorescent area and producing the second feedback optical signal indicating a position of the scanning beam from the fluorescent area.

37. The system as in claim 35, wherein:

the fluorescent area comprises parallel fluorescent stripes,

the optical module scans the scanning beam to cover the fluorescent area by a plurality of horizontal scans each along a horizontal direction perpendicular to the parallel fluorescent stripes, and

the second peripheral servo reference mark includes a vertical beam position servo reference mark which produces the second feedback optical signal indicating an offset of a vertical beam position from a predetermined vertical beam position in a vertical direction that is parallel to the fluorescent stripes.

38. The system as in claim 35, wherein:

the second peripheral servo reference mark includes a beam focus sensing reference mark producing the second feedback optical signal to indicate a beam spot size of the scanning beam on the screen.

39. The system as in claim 35, wherein:

the second peripheral servo reference mark includes a beam power sensing reference mark producing the second feedback optical signal to indicate a power level of the scanning beam on the screen.

40. The system as in claim 35, wherein:

the fluorescent area comprises parallel fluorescent stripes, and

the first servo reference marks respectively located at boundaries of the fluorescent stripes.

41. The system as in claim 35, further comprising:

a light pipe formed in the peripheral servo reference mark area of the screen having an input portion that is coupled to receive the second feedback optical signal generated by the second servo reference mark and an output portion that is coupled to the second optical sensor to direct the received second feedback optical signal to the second optical sensor.

42. The system as in claim 41, wherein:

the second servo reference mark is optically transmissive to direct a transmitted portion of the scanning beam to the light pipe as the second feedback optical signal.