Timing circuit for video display having a spatial light modulator
First Claim
1. A method of synchronizing display timing to pixel data representing a video signal comprising the steps of:
- receiving a wheel index signal identifying the position of a color wheel;
receiving a frame synchronization signal indicating that a complete video frame of said pixel data is ready to be displayed;
comparing the phase of said wheel index signal with the phase of said frame synchronization signal;
generating a color wheel synchronization signal in response to said comparing step for increasing or decreasing the speed of said color wheel to achieve a known phase relation with said frame synchronization signal;
generating a display master clock signal that controls the transfer of said pixel data to a pixel addressable display, said display master clock signal having a known frequency relation to said wheel index signal; and
generating a frame start synchronization signal indicating that the pixel addressable display should start displaying a next video frame, such that said synchronization signal is also used to generate a series of address and timing signals to cause a specific portion of said next video frame to be transferred to said pixel addressable display.
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Accused Products
Abstract
A method and apparatus for synchronizing display timing in a digital television system with a pixel addressable display having a color wheel is disclosed. The display timing circuit 22 includes phase comparator 40, for comparing the phase of a wheel index signal generated by a color wheel 20 with the phase of a frame synchronization signal indicating that a complete frame is ready to be displayed. Display timing circuit 22 further comprises a color wheel synchronization generator 42 which generates a color wheel synchronization signal in response to a phase difference value produced by phase comparator 40. The color wheel synchronization signal is used to increase, decrease, or maintain the speed of color wheel 20 to achieve a known phase relationship between the frame synchronization signal and the wheel index signal. Display timing circuit 22 further comprises a clock generator applicable to generate a display master clock signal having a known frequency relation to the wheel index signal.
58 Citations
15 Claims
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1. A method of synchronizing display timing to pixel data representing a video signal comprising the steps of:
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receiving a wheel index signal identifying the position of a color wheel; receiving a frame synchronization signal indicating that a complete video frame of said pixel data is ready to be displayed; comparing the phase of said wheel index signal with the phase of said frame synchronization signal; generating a color wheel synchronization signal in response to said comparing step for increasing or decreasing the speed of said color wheel to achieve a known phase relation with said frame synchronization signal; generating a display master clock signal that controls the transfer of said pixel data to a pixel addressable display, said display master clock signal having a known frequency relation to said wheel index signal; and generating a frame start synchronization signal indicating that the pixel addressable display should start displaying a next video frame, such that said synchronization signal is also used to generate a series of address and timing signals to cause a specific portion of said next video frame to be transferred to said pixel addressable display. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A display timing circuit for synchronizing display timing to a video signal in a digital television system having a pixel addressable display and a color wheel wherein the color wheel generates a wheel index signal identifying the position of the color wheel, comprising:
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a phase comparator for comparing the phase of said wheel index signal with the phase of a frame synchronization signal indicating that a complete video frame in the video signal is ready to be displayed, thereby generating a phase difference value; a color wheel synchronization signal generator for generating a color wheel synchronization signal in response to said phase difference value for increasing or decreasing the speed of the color wheel to achieve a known phase relation between said frame synchronization signal and said wheel index signal; a dock generator for generating a display master clock signal having a known frequency relation with said wheel index signal; a frame start signal generator operable to generate a frame start synchronization signal indicating that said display should start displaying the next video frame; and a clock frequency generator circuit for generating an intermediate clock signal with the same frequency as said display master clock signal, and wherein said clock generator comprises a phase locked loop operable to generate said display master dock signal by locking the phase of said intermediate clock signal to the phase of said wheel index signal. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A digital television system having a color wheel to provide colored light to a spatial light modulator and operable to generate a wheel index signal identifying the position of the color wheel, comprising:
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a display memory operable to store output video frame pixel data; a spatial light modulator display; and a display timing circuit comprising; a phase comparator for comparing the phase of said wheel index signal with the phase of a frame synchronization signal indicating that a complete video frame in said video signal is ready to be displayed thereby generating a phase difference value; a color wheel synchronization signal generator for generating a color wheel synchronization signal in response to said phase difference value for increasing or decreasing the speed of said color wheel to achieve a known phase relation between said frame synchronization signal and said wheel index signal; a clock generator for generating a display master dock signal having a known frequency relation with said wheel index signal and used to control the transfer of output video frame pixel data to said spatial light modulator; a frame start signal generator operable to generate a frame start synchronization signal indicating that said spatial light modulator should begin displaying the next video frame; and a sequence controller for executing display sequence instructions in response to said frame start synchronization signal thereby generating a series of address and timing signals, said series of address and timing signals capable of causing a specific portion of an output video frame stored in a display memory to be transferred to the pixel addressable display. - View Dependent Claims (15)
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Specification