Computer graphics processing and selective visual display system – Data responsive crt display control – Color display
Reexamination Certificate
1996-10-10
2001-12-11
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Data responsive crt display control
Color display
C345S032000
Reexamination Certificate
active
06329966
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a display device that scans a color phosphor screen with a laser beam.
Display devices of this type can display video and other color images similar to those displayed by a conventional cathode-ray tube. The advantage of scanning a color phosphor screen with a laser beam is that a laser beam does not require a large, evacuated glass tube for propagation. Issues must be addressed, however, in these display devices relating to modulating the laser beam and separating of the different colors in the display.
U.S. Pat. No. 5,003,179 describes a display device in which the intensities of three infrared laser beams are independently modulated, the intensity of each beam being selectively blanked to illuminate only phosphors which produce light of the desired color. Such a display device has drawbacks, however, because the need for selectively blanking light beams intensities is inconvenient.
Japanese Patent Kokai Publication No. 323686/1992 describes a display device that modulates the intensity of a single laser beam, which illuminates red, green, and blue phosphors. This system requires that the beam be modulated at three times the normal rate, and is inconsistent with conventional video signal processing.
Japanese Patent Kokai Publication No. 323686/1992 discloses a display device that scans a phosphor screen with a single ultraviolet beam, which is generated by converting the wavelength an infrared laser beam. This system is similarly inconsistent with conventional video signal processing.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to display an image by scanning a screen with ultraviolet beams modulated by conventional red, green, and blue video signals.
Another object of the invention is to improve color separation in the displayed image.
A further object is to improve the brightness of the displayed image.
A still further object is to obviate the need for blanking of the ultraviolet beams.
The invented display device has a transparent screen coated with three types of phosphors. When illuminated by ultraviolet light, each type of phosphor emits visible light of a different color. The display device also has a light source for producing three beams of ultraviolet light, three modulating means for independently modulating the intensity of these three ultraviolet beams, a scanning means for scanning the three ultraviolet beams across the transparent screen in a two-dimensional pattern, and a color separator disposed between the scanning means and transparent screen, for directing the three ultraviolet beams onto phosphors of the respective types on the transparent screen.
The light source comprises, for example, three infrared lasers and a wavelength conversion means. The color separator comprises, for example, an aperture mask, or a lens array. The scanning means comprises, for example, a pair of movable mirrors, or a pair of acousto-optic elements.
A filter that transmits ultraviolet light but reflects visible light may be provided between the color separator and the transparent screen to improve the brightness of the display. A focusing lens may also be provided, to focus the three ultraviolet beams.
Two or more of the invented display devices can be combined to form a display apparatus with a larger screen size.
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Shikama Shinsuke
Someya Jun
Frenel Vanel
Mitsubishi Denki & Kabushiki Kaisha
Shalwala Bipin
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