Television – Video display – Color sequential
Reexamination Certificate
1998-11-23
2001-07-03
Eisenzopf, Reinhard J. (Department: 2614)
Television
Video display
Color sequential
C348S750000, C348S742000
Reexamination Certificate
active
06256073
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of image display systems, more particularly to methods and systems for selecting image display system color sources to increase system brightness.
BACKGROUND OF THE INVENTION
Image display systems create images by emitting, or modulating, light. The light forms an array of picture elements, or pixels, which together form a viewable image. Full-color images are created by either simultaneously or serially creating three independent single-color images. Cathode ray tube (CRT) based display systems use three electron guns to simultaneously stimulate three color generating regions for each pixel on the CRT screen. These three colors must be selected carefully in order to ensure that combinations of the colors are able to accurately recreate the full-color image source.
Intensity, or image brightness, is only one of many metrics, including horizontal and vertical resolution, color purity, display size, frame rate, and immunity from device created image artifacts, by which display systems are judged. Some of these characteristics are more important to consumers, either because they create a noticeably superior image, or simply because they differentiate between the systems on display in a store. Brightness is one metric that is extremely important to purchasers of display systems. Therefore, system designers must attempt to increase brightness in order to satisfy consumers and increase sales.
One factor that contributes directly to image brightness, is the available brightness of the light sources used to generate an image. Some systems may use colored light sources, others will use white light sources that are filtered to obtain the desired component colors. Filtering light necessarily reduces the useable brightness of the light source. The efficiency of the filters is a function of the wavelengths selected by the filter. Furthermore, the wavelengths selected by the filter impact the purity of the image produced by the display system. Therefore, an improved filter selection process will improve both the image brightness and color purity of a display system
SUMMARY OF THE INVENTION
Objects and advantages will be obvious, and will in part appear hereinafter and will be accomplished by the present invention which provides a method and system for an image display system having increased brightness and color purity. One embodiment of the claimed invention provides a method of selecting a set of color sources for an image display system wherein the image display system creates a color image from at least three single-color color sources. The method comprises providing multiple first and second color sources, the multiple first and second color sources each divided into a high-efficiency group and a low-efficiency group based on the color source's efficiency, and providing multiple third color sources. The method further comprising the step of selecting a first, second, and third color source from the multiple first, second, and third color sources such that either the first color source or the second color source, but not both, may be selected from the low-efficiency group. Alternative embodiments measure surrogate parameters to indirectly determine the efficiency of the color sources selected.
According to a second embodiment of the claimed invention, a method of selecting a set of color sources for an image display system is provided. The method comprising providing multiple first, second, and third color sources, testing the first and said second color sources, and selecting a first, second, and third color source. Each first color source for transmitting light over a first range of wavelengths. The first range of wavelengths comprised of a first sub-range and a second sub-range with the first sub-range comprising longer wavelengths than the second sub-range and having a higher optical efficiency than the second sub-range. Each second color source for transmitting light over a second range of wavelengths, the second range of wavelengths comprised of a first sub-range of the second range and a second sub-range of the second range, with the second sub-range of the second range comprising shorter wavelengths than the second sub-range of the second sub-range and having a higher optical efficiency. The selection of a first and second color source ensuring that a first color source from the second sub-range is never paired with a second color source from the first sub-range.
According to yet another embodiment of the present invention, a display system is provided. The display system comprises a first, second, and third color source, and at least one spatial light modulator for receiving light from the first, second, and third color sources, modulating the received light, and transmitting the modulated light to an image plane. The first and second color sources are chosen from a selection of first and second color sources, each selection divided into a high-efficiency group and a low-efficiently group, wherein not more than one of the first and second color sources are chosen from a low-efficiency group. Alternative embodiments measure surrogate parameters, such as the cut-off wavelength of the color source, to indirectly determine the efficiency of the color sources selected.
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Brady III Wade James
Brill Charles A.
Eisenzopf Reinhard J.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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