Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1995-03-31
2001-05-15
Mengistu, Amare (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C340S815840, C359S317000
Reexamination Certificate
active
06232936
ABSTRACT:
This application is related to U.S. Pat. No. 4,956,619, issued Sep. 11, 1990 and U.S. Pat. No. 5,061,049, issued Oct. 29, 1991.
1. Field of the Invention
This invention relates to the field of projection display systems, more particularly to digital spatial light modulator projection display systems.
2. Background of the Invention
Spatial light modulators (SLM) may be used in projection display systems to create images. One of the primary display system performance metrics is resolution. Resolution is measured in lines per inch both vertically and horizontally. Because of the signal format of television and other video signals, vertical resolution is equal to the number of lines transmitted by the video source. Horizontal resolution is a more subjective measurement. If the video signal is digitized for display, the horizontal resolution is determined by the number of digitized video samples that can be displayed on each line of the video image.
Horizontal resolution specification is further complicated by the issue of effective or useful resolution. Visually disturbing effects can result when an image is displayed that uses the maximum horizontal resolution of the display system. If an image with vertical stripes that require the maximum horizontal resolution of the display moves horizontally and changes alignment with the pixels, the displayed image will appear to change very rapidly. This is caused by the phase shift between the video signal and the video sampling.
For example, as shown in
FIGS. 1 and 2
, if the triangle wave video signal represents an image of vertical black and white stripes at the horizontal resolution capability of the display, and the image is sampled at the points indicated by tick marks on the x-axis, each row of the displayed image will consist of alternating black and white pixels, as shown in FIG.
2
. If, as shown in
FIG. 3
, the phase of the input video signal changes, representing the image moving horizontally one-half pixel, the resulting image will be an entire row of gray pixels, as shown in FIG.
4
. As this image continues to move, the viewer will not see a moving field of stripes but a screen that alternates between high contrast stripes and gray. To eliminate this problem, video signals may be filtered to eliminate the high frequency components. The filter is usually designed to pass signals with horizontal resolution up to seventy percent of the maximum capability of the display screen. While this method eliminates the problems associated with displaying an image with high horizontal resolution, it does so by eliminating the high horizontal resolution signal components thereby lowering the resolution of the image.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an efficient SLM array architecture that increases the effective resolution of the display without reducing modulator efficiency. One embodiment of this invention staggers the rows of an SLM array to form a cardinal array. Another embodiment of this invention groups SLM elements from an ordinal array to form picture elements in cardinal format. Grouping may be accomplished by either physically connecting the control signals of the SLM elements, or by operating SLM elements in unison using independent control means for each element. Cardinal grouping of ordinal pixels avoids the efficiency problems that occur with some SLM technologies when using cardinal arrays.
It is a further advantage of the present invention to allow for redundancy in pixel addressing. It is still a further advantage of the present invention that it allows for increased display brightness.
REFERENCES:
patent: 5028939 (1991-07-01), Hornbeck et al.
patent: 5061049 (1991-10-01), Hornbeck
patent: 5146356 (1992-09-01), Carlson
patent: 5240818 (1993-08-01), Mignardi et al.
patent: 5280277 (1994-01-01), Hornbeck
Gove Robert J.
Sampsell Jeffrey B.
Brady III Wade James
Brill Charles A.
Mengistu Amare
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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