Laser displays using phosphor screens emitting visible colored light
View Patent ↗Laser display systems using at least one scanning laser beam to excite one or more fluorescent materials on a screen which emit light to form images. The fluorescent materials may include phosphor materials.
1. A display system, comprising:
a screen that comprises a substrate and parallel phosphor stripes formed on the substrate, wherein adjacent phosphor stripes are made of different phosphors that emit colored light of different colors by absorbing light at an excitation wavelength;
a laser module to project and scan a laser beam at the excitation wavelength onto the screen to convert an image carried by the laser beam via an optical modulation into a color image produced by the phosphor stripes on the screen;
an optical sensor module positioned to receive and detect colored light emitted from the phosphor stripes as a result of absorbing light at the excitation wavelength;
a feedback mechanism that directs an electrical output of the optical sensor module to the laser module; and
an alignment control mechanism in the laser module to respond to alignment information contained in the electrical output of the optical sensor module and to control a timing of image data modulated on the laser beam to correct an alignment of the laser beam with respect to the phosphor stripes.
2. The system as in claim 1 , wherein:
the optical sensor module is located off the screen.
3. The system as in claim 1 , wherein:
the optical sensor module is located on the screen.
4. The system as in claim 1 , wherein:
the optical sensor module comprises an optical sensor that detects colored light emitted from the phosphor stripes on the screen in only one color.
5. The system as in claim 4 , wherein:
the optical sensor detects light of one color selected from light of different colors emitted by the phosphor stripes without detecting light in other colors.
6. The system as in claim 1 , wherein:
the optical sensor module comprises different optical sensors that detect colored light in different colors emitted from the phosphor stripes on the screen, respectively.
7. The system as in claim 1 , wherein:
the laser module modulates the laser beam at the excitation wavelength to carry a test pattern that tests the alignment of the laser beam with respect to the phosphor stripes, and the alignment control mechanism corrects the alignment of the laser beam based on the electrical output of the optical sensor module corresponding to the test pattern.
8. The system as in claim 7 , wherein:
the test pattern includes an image frame in one color to test the alignment of the laser beam.
9. The system as in claim 1 , wherein:
the feedback mechanism and the alignment control mechanism in combination dynamically correct an alignment error of the laser beam on the screen during displaying an image on the screen for viewing by a viewer.
10. The system as in claim 1 , wherein:
the laser module projects and scans at least a second laser beam at the excitation wavelength, in addition to the laser beam, onto the screen.
11. A method for displaying images on a screen, comprising:
providing a screen that comprises a substrate on which parallel phosphor stripes are formed and adjacent phosphor stripes are made of different phosphors that emit colored light of different colors by absorbing light at an excitation wavelength;
scanning at least one laser beam at the excitation wavelength onto the screen to convert an image carried by the laser beam via an optical modulation into a color image produced by the phosphor stripes on the screen;
using an optical sensor module to receive and detect colored light emitted from the phosphor stripes to produce an electrical sensor signal containing alignment information of the laser beam on the screen; and
using the alignment information in the electrical sensor signal to control either a timing of image data modulated on the laser beam or a direction of the laser beam projected onto the screen to correct an alignment of the laser beam with respect to the phosphor stripes.
12. The method as in claim 11 , comprising:
modulating the laser beam at the excitation wavelength to carry a test pattern to test the alignment of the laser beam with respect to the phosphor stripes; and
controlling the laser beam to correct the alignment of the laser beam based on the electrical sensor signal of the optical sensor module corresponding to the test pattern.
13. The method as in claim 12 , wherein:
the test pattern includes an image frame in one color to test the alignment of the laser beam.
14. The method as in claim 11 , comprising:
dynamically correcting an alignment error of the laser beam on the screen during displaying an image for viewing by a viewer.
15. A display system, comprising:
a screen comprising a substrate and parallel phosphor stripes on the substrate, wherein two adjacent phosphor stripes are made of different phosphors that emit colored light of different colors by absorbing light at an excitation wavelength; and
a laser module to project and scan a laser beam at the excitation wavelength onto the screen to convert an image carried by the laser beam via an optical modulation into a color image produced by colored light emitted by the phosphor stripes on the screen, the laser module comprising a mechanism to monitor image data bits to be modulated on the laser beam to produce a black pixel monitor signal; a diode laser to produce the laser beam; and a laser control coupled to receive the black pixel monitor signal and to (1) operate the diode laser at a driving current below a laser threshold current without turning off the driving current to produce a low light output representing a virtual black color on the screen when the black pixel monitor signal indicates a display time of a block of contiguous black pixels is less than a response delay time of the diode laser and (2) turn off the driving current to produce a true black color on the screen when the black pixel monitor signal indicates a display time of a block of contiguous black pixels is greater than the response delay time of the diode laser.
16. The system as in claim 15 , wherein:
the laser module is configured such that after turning off the driving current to produce the true black color on the screen when the black pixel monitor signal indicates the display time of the block of contiguous black pixels is greater than the response delay time of the diode laser, the laser module, before the end of displaying the block of the contiguous black pixels, turns on the driving current of the diode laser to a value below the laser threshold current to produce the virtue black color for the remaining part of the block of the contiguous black pixels.
17. The system as in claim 15 , comprising:
an optical sensor module positioned to receive and detect colored light emitted from the phosphor stripes as a result of absorbing light at the excitation wavelength; and
a feedback control that responds to an electrical output of the optical sensor unit to obtain alignment information contained in the electrical output of the optical sensor module and controls at least one of a timing of image data modulated on the laser beam and a direction of the laser beam projected onto the screen to correct an alignment of the laser beam with respect to the phosphor stripes.