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US 2009/0015542 A1Published application
Method and device for controlling the backlighting of a flat screen
AssigneeSemtech Neuchatel SA
InventorMichel Chevroulet
Life of this patent
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Abstract
Electronic circuit designed to control the level of lighting produced by light diodes in a flat screen. The circuit uses a PDM modulator in order to generate a control signal (Vc) with a number of pulses by period that depends on the desired level of lighting. The advantage is to reduce the energy in the low frequencies.
Claims19
A method for controlling the lighting level produced by light diodes in a device for backlighting a flat screen,
- wherein the current passing through said light diodes is modulated in PDM (pulse density modulation),
- wherein the number of emitted pulses depends on the desired lighting level.
An electronic circuit designed to control the level of backlighting produced by light diodes in a flat screen,
- comprising a PDM modulator in order to generate a control signal with a number of pulses (P) per period that depends on the desired level of backlighting,
- said control signal being applied to said light diodes.
A System comprising:
- a liquid crystal display
- backlighting device with light diodes controlled by a control signal,
- a PDM modulator for generating said control signal with a number of pulses (P) per period that depends on the desired level of backlighting.
Dependencies are inferred from the claim text.