Gamma variation using illumination intensity
AssigneeCitizen Finetech Miyota Co., Ltd.
InventorsMark A. Handschy, James M. Dallas, Michael Wayne Yee, Per Harold Larsen
Life of this patent
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Abstract
A gamma variation of image intensity is created by varying the illumination intensity during a pulse width modulated display time period. During the pulse width modulated display time period a ramp signal may be compared with the image data to determine when pixel electrodes of the pixel array are switched. The illumination intensity may be varied in concert with ramp signal to produce a quadratic variation of displayed intensity on image data value. The illumination source could be an LED illumination source and intensity of the LED illumination source could be controlled using pulse width modulation.
Claims16
A display device, comprising:
- an illumination source;
- an array of active pixels, the array of active pixels electronically controllable to switch between a first light modulating state that substantially passes incoming light to a user and a second light modulating state that substantially blocks the incoming light from reaching the user;
- and
- a control unit coupled to operate the array of active pixels using digital pulse width modulation to create gray scale image output of the array of active pixels by comparing pixel image data values with a reference signal, the pixel image data values based on input image data values, and wherein the control unit varies an intensity of the illumination source based on the reference signal to produce a gamma characteristic in the image output.
A display device, comprising:
- an illumination source;
- an array of active pixels, the array of active pixels electronically controllable to switch between a first light modulating state that substantially passes incoming light to a user and a second light modulating state that substantially blocks the incoming light from reaching the user;
- and
- control circuitry coupled to control the array of active pixels to generate gray scale image output of the array of active pixels using pulse width modulation waveforms during a display phase, wherein the control circuitry operates the array of active pixels in the first light modulating state at the start of the display phase and switches operation the array of active pixels to the second light modulating state during the display phase after a determined time period based on input image data values, and wherein the control circuitry varies an intensity of the illumination source during the display phase to produce a gamma characteristic in the image output.
A method of producing a gamma characteristic in a display system, the display system comprising an illumination source and a display device having an array of active pixels operable to switch between a plurality of light modulating states, the method comprising:
- modulating the array of active pixels between a first light modulating state and a second light modulating state to produce gray scale image output of the array of active pixels during a display phase, wherein each of the array of active pixels is switched to the first light modulating state at the beginning of the display phase and pixels of the array of pixels switch to the second light modulating state after a determined time period that is proportional to gray scale values of input image data corresponding to the pixels;
- and
- varying an intensity of the illumination source during the display phase to produce a gamma characteristic in the image.
Dependencies are inferred from the claim text.