Optical designs for scanning beam display systems using fluorescent screens

Abstract

Scanning beam display systems based on scanning light on a fluorescent screen. The screen can include fluorescent materials which emit visible light under excitation of the scanning light to form images with the emitted visible light. Multiple lasers can be used to simultaneously scan multiple laser beams to illuminate the screen for enhanced display brightness. For example, the multiple laser beams can illuminate one screen segment at a time and sequentially scan multiple screen segments to complete a full screen.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example scanning laser display system having a fluorescent screen made of laser-excitable phosphors emitting colored lights under excitation of a scanning laser beam that carries the image information to be displayed.

FIGS. 2A and 2B show one example screen structure and the structure of color pixels on the screen in FIG. 1.

FIG. 2C shows another example for a fluorescent screen with fluorescent stripes formed by placing parallel optical filters over the layer of a uniform fluorescent layer which emits white light under optical excitation.

FIG. 3 shows an example implementation of the laser module in FIG. 1 having multiple lasers that direct multiple laser beams on the screen.

FIG. 4 illustrates one example of simultaneous scanning of multiple screen segments with multiple scanning laser beams.

FIGS. 5A and 5B show an example of a laser module with an array of lasers to produce different scanning beams onto the screen for implementations of the display system in FIG. 3.

FIGS. 6, 7, 8 and 9 show examples of lasers having laser actuators that control the vertical direction of the laser beam.

FIG. 10 shows an optical layout of a laser module for implementing the scanning laser module in FIG. 3.

FIG. 11 shows an example of a two-dimensional f-theta scan lens with three lens elements.

FIG. 12 shows an alternative design of an afocal relay in FIG. 10.

FIG. 13 shows an example of an afocal relay between a galvo mirror and a polygon scanner to image the galvo mirror on to a reflecting facet of the polygon scanner.

FIG. 14 illustrates bow distortions caused by a scan lens in a scanning display system based on the laser module in FIG. 3.

FIGS. 15 shows an example of measured distortions on a screen caused by a scan lens in a scanning system based on the design in FIG. 3.

FIGS. 16A and 16B show two examples of folded optical paths for directing a scanning laser beam to a screen with phosphors in scanning beam rear projection systems.

Claims

1. A display system, comprising: a plurality of lasers forming a laser array to produce a plurality of laser beams, respectively;a scanning module placed in an optical path of the laser beams to scan the laser beams in two orthogonal directions; andan afocal optical relay module placed between the lasers and the scanning module having a plurality of lenses to reduce a spacing between two adjacent laser beams of the laser beam and to overlap the laser beams at the scanning module.

2. The system as in claim 1, wherein the afocal optical relay module comprises: a first lens having a first focal length to receive and focus the laser beams from the lasers;a second lens having a second focal length shorter than the first focal length and spaced from the first lens by the first focal length to focus the laser beams from the first lens; anda third lens having a third focal length longer than the second focal length and spaced from the second lens by the third focal length to focus and direct the laser beams from the second lens to the scanning module.

3. The system as in claim 2, wherein the scanning module comprises: a galvo mirror positioned to receive the laser beams from the third lens and scan the received laser beams along the first scanning direction, anda polygon scanner positioned to receive the laser beams from the galvo mirror and operable to scan the received laser beams along a second scanning direction orthogonal to the first scanning direction; andwherein the system further comprises an optical imaging lens module placed between the galvo mirror and the polygon scanner to image the galvo mirror onto the polygon scanner.

4. The system as in claim 3, wherein the optical imaging lens module comprises a first lens unit and a second lens unit to produce a unity image magnification.

5. The system as in claim 1, wherein the afocal optical relay module comprises: a plurality of first lenses having first focal lengths and respectively placed in optical paths of the laser beams, each first lens receiving only a respective laser beam without receiving another laser beam among the laser beams and focus the respective laser beam;a second lens having a second focal length shorter than the first focal lengths and spaced from the first lenses by the first focal lengths to focus the laser beams from the first lenses; anda third lens having a third focal length longer than the second focal length and spaced from the second lens by the third focal length to focus and direct the laser beams from the second lens to the scanning module.

6. The system as in claim 5, wherein the scanning module comprises: a galvo mirror positioned to receive the laser beams from the third lens and scan the received laser beams along the first scanning direction,a polygon scanner positioned to receive the laser beams from the galvo mirror and operable to scan the received laser beams along a second scanning direction orthogonal to the first scanning direction; andwherein the system further comprises an imaging optical device placed between the galvo mirror and the polygon scanner to image the galvo mirror onto the polygon scanner.

7. The system as in claim 5, further comprising a plurality of lens actuators that are engaged to the first lenses, respectively, each lens actuator operable to adjust a respective first lens.

8. The system as in claim 1, further comprising: a screen; anda scan lens positioned to receive the laser beams from the scanning module and to project the laser beams onto the screen by imaging the lasers onto the screen.

9. The system as in claim 8, wherein the scan lens is a two-dimensional f-theta lens.

10. The system as in claim 8, further comprising a Fresnel lens placed in front of the screen to direct light from the scan lens into the screen at a normal incidence.

11. The system as in claim 8, wherein the screen comprises fluorescent materials that emit visible light to form images with the emitted light when illuminated by the laser beams.

12. The system as in claim 8, further comprising: a signal modulation controller in communication with the lasers to supply image data to control the lasers which modulate the laser beams, respectively, to carry an image to be displayed on the screen,wherein the signal modulation controller has image data that contains image distortions which negate optical distortions of the scan lens when displayed on the screen.

13. The system as in claim 8, further comprising: first and second optical reflectors that reflect the laser beams, wherein the first optical reflector is positioned to reflect scanning laser beams from the scan lens to the second optical reflector which is positioned to reflect the scanning laser beams from the first optical reflector to the screen,wherein the first and second optical reflectors are positioned to fold an optical path from the scan lens to the screen to reduce a distance between the scan lens and the screen.

14. The system as in claim 1, further comprising a plurality of laser actuators, each engaged to a respective laser and operable to adjust a direction of a respective laser beam produced by the laser.

15. The system as in claim 14, wherein each laser actuator rotates the direction of the respective layer beam produced by the laser around a pivot point on the scanning module.

16. The system as in claim 1, further comprising: a laser array mounting rack to hold the lasers in a three dimensional array.

17. The system as in claim 1, further comprising: a laser array mounting rack to hold the lasers in a plurality of sub laser arrays, where different sub laser arrays are spatially shifted from one another to have different distances to the scanning module.

18. The system as in claim 16, wherein lasers in each sub laser array are oriented to direct respective laser beams in a fan configuration converging towards the scanning module.

19. A display system, comprising: a plurality of lasers forming a laser array to produce a plurality of laser beams, respectively;a scanning module placed in an optical path of the laser beams to scan the laser beams in two orthogonal directions;a screen comprising fluorescent materials that emit visible light to form images with the emitted light when illuminated by the laser beams;a scan lens positioned to receive the laser beams from the scanning module and to project the laser beams onto the screen; andfirst and second optical reflectors that reflect the laser beams, wherein the first optical reflector is positioned to reflect scanning laser beams from the scan lens to the second optical reflector which is positioned to reflect the scanning laser beams from the first optical reflector to the screen,wherein the first and second optical reflectors are positioned to fold an optical path from the scan lens to the screen to reduce a distance between the scan lens and the screen.

20. The system as in claim 19, further comprising: an afocal optical relay module placed between the lasers and the scanning module having a plurality of lenses to reduce a spacing between two adjacent laser beams of the laser beam and to overlap the laser beams at the scanning module.

21. The system as in claim 20, wherein the afocal optical relay module comprises: a first lens having a first focal length to receive and focus all of the laser beams from the lasers;a second lens having a second focal length shorter than the first focal length and spaced from the first lens by the first focal length to focus the laser beams from the first lens; anda third lens having a third focal length longer than the second focal length and spaced from the second lens by the third focal length to focus and direct the laser beams from the second lens to the scanning module.

22. The system as in claim 21, wherein the scanning module comprises: a galvo mirror positioned to receive the laser beams from the third lens and scan the received laser beams along the first scanning direction, anda polygon scanner positioned to receive the laser beams from the galvo mirror and operable to scan the received laser beams along a second scanning direction orthogonal to the first scanning direction; andwherein the system further comprises an imaging optical device placed between the galvo mirror and the polygon scanner to image the galvo mirror onto the polygon scanner.

23. The system as in claim 20, wherein the afocal optical relay module comprises: a plurality of first lenses having first focal lengths and respectively placed in optical paths of the laser beams, each first lens receiving only a respective laser beam without receiving another laser beam among the laser beams and focus the respective laser beam;a second lens having a second focal length shorter than the first focal lengths and spaced from the first lenses by the first focal lengths to focus the laser beams from the first lenses; anda third lens having a third focal length longer than the second focal length and spaced from the second lens by the third focal length to focus and direct the laser beams from the second lens to the scanning module.

24. The system as in claim 23, wherein the scanning module comprises: a galvo mirror positioned to receive the laser beams from the third lens and scan the received laser beams along the first scanning direction,a polygon scanner positioned to receive the laser beams from the galvo mirror and operable to scan the received laser beams along a second scanning direction orthogonal to the first scanning direction; andwherein the system further comprising an imaging optical device placed between the galvo mirror and the polygon scanner to image the galvo mirror onto the polygon scanner.

25. The system as in claim 19, wherein the scan lens is a two-dimensional f-theta lens.

26. The system as in claim 19, further comprising: a laser array mounting rack to hold the lasers in a three dimensional array.

27. The system as in claim 19, further comprising: a laser array mounting rack to hold the lasers in a plurality of sub laser arrays, where different sub laser arrays are spatially shifted from one another to have different distances to the scanning module.

28. The system as in claim 27, wherein lasers in each sub laser array are oriented to direct respective laser beams in a fan configuration converging towards the scanning module.

29. A method for scanning light onto a screen to display an image, comprising: modulating light to include optical pulses that carry images to be displayed;scanning the light in two orthogonal scanning directions; andusing a scan lens to project the scanned light on a screen to show the images,wherein the light is modulated to carry distorted versions of the images to include image distortions that negate distortions caused by the scan lens when displayed on the screen.

30. The method as in claim 29, further comprising: controlling timing of the optical pulses in the first scanning direction to negate a portion of distortions caused by the scan lens when displayed on the screen.

31. The method as in claim 29, further comprising: introducing distortions into image data to be displayed on the screen based on an image distortion map on the screen caused by the scan lens to produce distorted image data; andmodulating the light to carry the distorted image data which includes the image distortions that negate distortions caused by the scan lens when displayed on the screen.

32. The method as in claim 29, wherein the screen is a fluorescent screen that emits visible light to display images when illuminated by the scanned light.

33. A display system, comprising: a light source to produce at least one excitation beam modulated to carry images;a scanning module to scan the excitation beam in two orthogonal directions;a fluorescent screen to receive the scanning excitation beam, the fluorescent screen emitting visible light to form the images with the emitted visible light when illuminated by the scanning excitation beam; anda two-dimensional f-theta scan lens positioned to receive the scanning excitation beam from the scanning module and to project the scanning excitation beam onto the screen.

34. The system as in claim 33, further comprising: a signal modulation controller in communication with the light source to supply image data for the images to control the light source which modulates the excitation beam, wherein the signal modulation controller provides image data with image distortions which negate optical distortions of the two-dimensional f-theta scan lens when displayed on the screen.