Servo-assisted scanning beam display systems using fluorescent screens
View Patent ↗Methods and systems for improving imaging quality and power efficiency of scanning beam display systems using fluorescent screens are disclosed. In various embodiments, beam shaping mechanisms for maximizing overlap between the beam cross-section and the florescent element corresponding to each color sub-pixel of the screen, as well as pulse width and timing adjustments, are introduced to reduce imaging noise and improve power efficiency of the display system.
1. A scanning beam display system, comprising:
a fluorescent screen comprising a plurality of elongated fluorescent stripes, each elongated fluorescent stripe operable to emit visible fluorescent light in response to receiving excitation light;
an optical module operable to produce an excitation light beam and scan the excitation light beam across a series of positions on the screen in a scanning direction, wherein the excitation light beam comprise a series of optical pulses, each optical pulse targeting a respective one of the series of positions on the screen, and wherein the optical module is operable to shape a beam cross-section of each optical pulse such that the cross-section is elongated along a respective fluorescent stripe, the respective fluorescent stripe being located at a screen position that is targeted by the optical pulse; and
a signal modulation controller, the signal modulation controller configured to adjust a timing of each optical pulse such that the optical pulse targeting the screen position at which the respective fluorescent stripe is located is turned on when a footprint of the optical pulse overlaps with a center portion of the respective fluorescent stripe in the scanning direction and turned off when the footprint of the optical pulse is offset from the center portion of the respective fluorescent stripe in the scanning direction.
2. The system of claim 1 , wherein the optical module includes a beam shaping element that elongates the beam cross-section of the each optical pulse.
3. The system of claim 1 , wherein the optical module includes at least one multi-mode laser diode, the multi-mode laser diode generates the excitation light beam, and the beam cross-section of each optical pulse in the excitation light beam is single-mode along the scanning direction, and is multi-mode in a direction perpendicular to the scanning direction.
4. The system of claim 3 , wherein the optical module adjusts a power of at least one of the series of optical pulses by adjusting a power of one or more multi-mode components of the optical pulse.
5. The system of claim 1 , wherein the plurality of fluorescent stripes include repeated patterns of colored fluorescent stripes, each repetition of the pattern in the scanning direction corresponds to a respective pixel of the screen, and each colored fluorescent stripe within the repetition of the pattern corresponds to a colored sub-pixel of the pixel.
6. The system of claim 5 , wherein the scanning direction is perpendicular to an elongation direction of the fluorescent stripes, and wherein a width of the elongated cross-section of each optical pulse is less than a width of each of the colored fluorescent stripes in the scanning direction.
7. The system of claim 1 , wherein each of the optical pulses has an energy sufficient to cause a respective one of the fluorescent stripes to emit visible light.
8. The system of claim 1 , wherein the optical pulse targeting the respective fluorescent stripe is turned on when a center of the footprint reaches a center of the respective fluorescent stripe in the scanning direction.
9. A scanning beam display system, comprising:
a fluorescent screen comprising a plurality of elongated fluorescent stripes, each elongated fluorescent stripe operable to emit visible fluorescent light in response to receiving excitation light;
an optical module operable to produce an excitation light beam and scan the excitation light beam across a series of positions on the screen in a scanning direction, wherein the excitation light beam comprise a series of optical pulses, each optical pulse targeting a respective one of the series of positions on the screen, and wherein the optical module is operable to shape a beam cross-section of each optical pulse such that the cross-section is elongated along a respective fluorescent stripe, the respective fluorescent stripe being located at a screen position that is targeted by the optical pulse; and
a signal modulation controller, the signal modulation controller adjust a timing of each optical pulse such that the optical pulse targeting a first colored fluorescent stripe is turned on when a footprint of the optical pulse overlaps with a center portion of the first colored fluorescent stripe in the scanning direction and turned off when the footprint of the optical pulse is offset from the center portion of the first colored fluorescent stripe in the scanning direction,
wherein the plurality of fluorescent stripes include repeated patterns of colored fluorescent stripes, each repetition of the pattern in the scanning direction corresponds to a respective pixel of the screen, and each colored fluorescent stripe within the repetition of the pattern corresponds to a colored sub-pixel of the pixel.
10. A method for controlling a scanning beam display system, comprising:
scanning an excitation light beam across a series of positions on a screen in a scanning direction, the screen comprising a plurality of elongated fluorescent stripes, each elongated fluorescent stripe operable to emit visible fluorescent light in response to receiving excitation light, the excitation light beam comprising a series of optical pulses, each optical pulse targeting a respective one of the series of positions on the screen;
shaping a beam cross-section of each of the optical pulses such that the cross-section is elongated along a respective fluorescent stripe, the respective fluorescent stripe being located at a screen position that is targeted by the optical pulse; and
adjusting a timing of each optical pulse such that the optical pulse targeting the screen position at which the respective fluorescent stripe is located is turned on when a footprint of the optical pulse overlaps with a center portion of the respective fluorescent stripe in the scanning direction, and turned off when the footprint of the optical pulse is offset from the center portion of the respective fluorescent stripe in the scanning direction.
11. The method of claim 10 , wherein shaping the cross-section of each of the optical pulses along a respective fluorescent stripe further comprises:
placing a beam shaping optical element in stream of the excitation light beam, such that the beam cross-section of the optical pulse in the excitation light beam is elongated along the respective fluorescent stripe in a direction perpendicular to the scanning direction and narrowed along the scanning direction.
12. The method of claim 11 , wherein shaping the beam cross-section of each of the optical pulses along a respective fluorescent stripe further comprises:
generating the excitation light beam using a multi-mode laser diode, wherein the beam cross-section of the optical pulse is single-mode along the scanning direction, and multi-mode in a direction perpendicular to the scanning direction.
13. The method of claim 12 , further comprising:
adjusting a power of at least one of the series of optical pulses by adjusting a power of one or more multi-mode components of the optical pulse.
14. The method of claim 10 , wherein the plurality of fluorescent stripes include repeated patterns of colored fluorescent stripes, each repetition of the pattern in the scanning direction corresponds to a respective pixel of the screen, and each colored fluorescent stripe within the repetition of the pattern corresponds to a colored sub-pixel of the pixel.
15. The method of claim 14 , wherein the scanning direction is perpendicular to an elongation direction of the fluorescent stripes, and wherein a width of the elongated beam cross-section of each optical pulse is less than a width of each of the colored fluorescent stripes in the scanning direction.
16. The method of claim 10 , wherein each of the optical pulses has an energy sufficient to cause a respective one of the fluorescent stripes to emit visible light.
17. The system of claim 10 , wherein the optical pulse targeting the respective fluorescent stripe is turned on when a center of the footprint reaches a center of the respective fluorescent stripe in the scanning direction.
18. A method of controlling a scanning beam display system, comprising:
scanning an excitation light beam across a series of positions on a screen in a scanning direction, the screen comprising a plurality of elongated fluorescent stripes, each elongated fluorescent stripe operable to emit visible fluorescent light in response to receiving excitation light, the excitation light beam comprising a series of optical pulses, each optical pulse targeting a respective one of the series of positions on the screen;
shaping a beam cross-section of each of the optical pulses such that the cross-section is elongated along a respective fluorescent stripe, the respective fluorescent stripe being located at a screen position that is targeted by the optical pulse; and
adjusting a timing of each optical pulse such that the optical pulse targeting a first colored fluorescent stripe is turned on when a footprint of the optical pulse overlaps with a center portion of the first colored fluorescent stripe in the scanning direction, and turned off when the footprint of the optical pulse is offset from the center portion of the first colored fluorescent stripe in the scanning direction,
wherein the plurality of fluorescent stripes include repeated patterns of colored fluorescent stripes, each repetition of the pattern in the scanning direction corresponds to a respective pixel of the screen, and each colored fluorescent stripe within the repetition of the pattern corresponds to a colored sub-pixel of the pixel.
19. A scanning beam display system, comprising:
a fluorescent screen comprising repeated patterns of colored fluorescent stripes, each repetition of the pattern includes a fixed number of fluorescent stripes of different colors arranged in a predetermined sequence, each colored fluorescent stripe being elongated in shape and emitting visible fluorescent light of a respective color in response to receiving excitation light;
an optical module operable to produce an excitation light beam and scan the excitation light beam across a series of positions on the screen in a scanning direction, wherein the excitation light beam comprises a series of optical pulses, each optical pulse targeting a respective one of the colored fluorescent stripes on the screen, wherein the optical module is operable to shape a beam cross-section of the optical pulse such that the beam cross-section is elongated along the respective fluorescent stripe, and wherein the optical module shapes the cross-section of the optical pulse by generating a pulse that is single-mode along the scanning direction and multi-mode in a direction perpendicular to the scanning direction; and
a signal modulation controller operable to adjust a timing of each of the optical pulses such that the optical pulse targeting a first colored fluorescent stripe is turned on when a footprint of the optical pulse overlaps with a center portion of the first colored fluorescent stripe in the scanning direction and turned off when the footprint of the optical pulse is offset from the center portion of the first colored fluorescent stripe in the scanning direction.
20. The system of claim 19 , wherein the optical module adjusts a power of at least one of the series of optical pulses by adjusting a power of one or more multi-mode components of the optical pulse.
21. The system of claim 19 , wherein the scanning direction is perpendicular to an elongation direction of the fluorescent stripes, and a width of the cross-section of each optical pulse is less than a width of each colored fluorescent stripe in the scanning direction.
22. The system of claim 19 , wherein a time-domain pulse width of each optical pulse is no more than a duration that the footprint of the optical pulse overlaps with a respective colored fluorescent stripe targeted by the optical pulse.
23. The system of claim 19 , wherein the optical pulse targeting the first colored fluorescent stripe is turned on when a center of the footprint reaches a center of the first colored fluorescent stripe in the scanning direction.