Method and apparatus for power level control of a display device
First Claim
1. Method for power level control in a display device having a plurality of luminous elements corresponding to the pixels of a picture, wherein the time duration of a video frame is divided into a plurality of subfields during which each luminous element can be activated for light emission in small pulses, called hereinafter sustain pulses, corresponding to a subfield code word representative of the video level of the corresponding pixel, wherein a set of power level modes is provided for subfield coding wherein to each power level mode a characteristic subfield organization belongs, the subfield organizations being variable in respect to the number of sustain pulses during a frame, said method comprising a step for determining a power value which is characteristic for the power level of the picture to be displayed and a maximum video value which is characteristic for the maximum video level of said picture, and a step for increasing said maximum video value to substantially the nominal value and a step for selecting a power level mode based on said power value and said maximum video value, said power level mode having a reduced number of sustain pulses such that the light emission of each pixel is kept.
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Abstract
The invention concerns a video processing for improving the picture quality of picture which are displayed on display devices like plasma display panels and all kind of display devices based on the principle of duty cycle modulation of light emission and for reducing the average power dissipation. The basic idea behind the invention is to generate only the required amount of sustain pulses that effectively produce light and to avoid generating unnecessary sustain pulses. To this end, the video range of the input video is increased in order to be equal to a nominal range, 255 in the case of a 8-bit coding, and a power level mode with a reduced number of sustain pulses is selected to keep constant the brightness of the image. The number of sustain pulses that do not produce light is reduced.
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Citations
10 Claims
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1. Method for power level control in a display device having a plurality of luminous elements corresponding to the pixels of a picture, wherein the time duration of a video frame is divided into a plurality of subfields during which each luminous element can be activated for light emission in small pulses, called hereinafter sustain pulses, corresponding to a subfield code word representative of the video level of the corresponding pixel, wherein a set of power level modes is provided for subfield coding wherein to each power level mode a characteristic subfield organization belongs, the subfield organizations being variable in respect to the number of sustain pulses during a frame, said method comprising
a step for determining a power value which is characteristic for the power level of the picture to be displayed and a maximum video value which is characteristic for the maximum video level of said picture, and a step for increasing said maximum video value to substantially the nominal value and a step for selecting a power level mode based on said power value and said maximum video value, said power level mode having a reduced number of sustain pulses such that the light emission of each pixel is kept.
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5. Apparatus for power level control in a display device having a plurality of luminous elements corresponding to the pixels of a picture, wherein the time duration of a video frame is divided into a plurality of subfields during which each luminous element can be activated for light emission in small pulses, called hereinafter sustain pulses, corresponding to a subfield code word representative of the video level of the corresponding pixel, wherein a set of power level modes is provided for subfield coding wherein to each power level mode a characteristic subfield organization belongs, the subfield organizations being variable in respect to the number of sustain pulses during a frame, said apparatus comprising
an average picture power circuit for determining a power value which is characteristic for the power level of the picture to be displayed, a maximum video value circuit for determining a maximum video value which is characteristic of the maximum video level of the picture to be displayed, a power level control circuit for increasing said maximum video value to a nominal value and for selecting a power level mode based on said power value and said maximum video value, said power level mode having a reduced number of sustain pulses such that that the light emission of each pixel is kept.
Specification