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AssigneeSharp Kabushiki Kaisha
InventorsToshihiro Yanagi, Kouji Kumada, Takashige Ohta
Estimating the term…
Adapting to load currents which differ by more than 100 times between a scanning mode and a hold mode, a frequency of pump operation is decided according to the maximum value of the load currents, and circuit elements of a power supply, for example, such as capacitance of a capacitor for pump operation or a smoothing capacitor, element configurations of switching elements, or capacitance or resistance value of a CR oscillator are set based on this frequency, so that a load current detector lowers the frequency of the pump operation under light load to reduce a self-loss of power in the power supply. This realizes a charge-pump power supply which is installed in a liquid crystal display device of a terminal device of a portable phone, with reduced power consumption under light load and a longer standby time.
An active-matrix image display device which includes a power supply of a charge-pump system, and drivers which come into operation in response to a supply of power from the power supply to drive display cells, said drivers having two operational modes including a scanning mode during which said active matrix display is vertically scanned and in which said power supply operates at a first frequency and a video signal is applied to any of the display cells, and a hold mode in which said power supply operates at a second non-zero frequency smaller than said first frequency and no video signal is applied to any of the display cells, said active-matrix image display device comprising:
Portable electrical equipment with an image display device, said image display device being an active-matrix image display device which includes a power supply of a charge-pump system, and drivers which come into operation in response to a supply of power from the power supply to drive display cells, said drivers having two operational modes including a scanning mode during which said active matrix display is vertically scanned and in which said power supply operates at a first frequency and a video signal is applied to any of the display cells, and a hold mode in which said power supply operates at a second non-zero frequency smaller than said first frequency and no video signal is applied to any of the display cells;
An active-matrix image display device which includes a power supply of a charge-pump system, and drivers which come into operation in response to a supply of power from the power supply to drive display cells, said drivers having two operational modes including a scanning mode during which said active matrix display is vertically scanned and in which a video signal is applied to any of the display cells, and a hold mode in which no video signal is applied to any of the display cells, said power supply maintaining an output voltage value while said drivers are in said hold mode by a smoothing capacitor which is located between an input to said drivers and an output of the power supply, said power supply including:
Portable electrical equipment with an image display device, said image display device being an active-matrix image display device which includes a power supply of a charge-pump system, and drivers which come into operation in response to a supply of power from the power supply to drive display cells, said drivers having two operational modes including a scanning mode during which said active matrix display is vertically scanned and in which a video signal is applied to any of the display cells, and a hold mode in which no video signal is applied to any of the display cells, said power supply maintaining an output voltage value while said drivers are in said hold mode by a smoothing capacitor which is located between an input to said drivers and an output of the power supply while the pump operation is inactive, said image display device comprising:
Dependencies are inferred from the claim text.