POWER MANAGEMENT METHOD AND DEVICE FOR LOW-POWER DISPLAYS
First Claim
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1. An apparatus for driving a display, comprising:
- a power supply for outputting energy at a supply voltage;
a converter for converting the supply voltage of the power supply into a converted voltage;
a controller for controlling an operation of said converter; and
an energy storage device for storing energy outputted by said converter at said converted voltage, said storage device also for providing stored energy to said display;
whereinsaid controller controls said converter such that said converter supplies said converted voltage to said storage device for a first time interval but not for a second time interval, wherein said first time interval has a duration that is less than the duration of said second time interval; and
whereinsaid storage device supplies a driving voltage to said display during said second time interval, said driving voltage sufficient to drive said display.
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Abstract
A device and method for supplying a display, such as a liquid crystal display, for example a bistable ChLCD, with drive voltages for extremely low power operation. The method and the device implementing the method provides an energy storage device and a voltage converter being utilized to store energy in the storage device, such that a display can be driven during an inactive, powered-down phase of the converter by using the stored energy to drive the display.
28 Citations
32 Claims
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1. An apparatus for driving a display, comprising:
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a power supply for outputting energy at a supply voltage; a converter for converting the supply voltage of the power supply into a converted voltage; a controller for controlling an operation of said converter; and an energy storage device for storing energy outputted by said converter at said converted voltage, said storage device also for providing stored energy to said display;
whereinsaid controller controls said converter such that said converter supplies said converted voltage to said storage device for a first time interval but not for a second time interval, wherein said first time interval has a duration that is less than the duration of said second time interval; and
whereinsaid storage device supplies a driving voltage to said display during said second time interval, said driving voltage sufficient to drive said display. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for driving a display, comprising:
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a power supply for outputting energy at a supply voltage; a converter for converting the supply voltage of the power supply into a converted voltage; and an energy storage device for storing energy outputted by said converter at said converted voltage, said storage device also for providing stored energy to said display;
whereinsaid apparatus is adapted such that said converter circuit provides energy at said converted voltage to said storage device to charge said storage device during a converter active phase, and wherein said apparatus is adapted to deactivate said converter during a converter inactive phase where said converter is not providing any substantial energy to said energy storage device, such that a consumption of power by said converter is substantially reduced during said inactive phase, and further wherein said storage device provides stored energy to said display for updating a display image during a driving phase that overlaps at least a substantial portion of said inactive phase. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An apparatus for driving an LCD display, comprising:
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a dc power supply for outputting energy at a supply voltage; a dc-to-dc converter for converting the supply voltage of the power supply into a converted voltage; a driver for driving said display; an energy storage device for storing energy outputted by said converter at said converted voltage, said storage device also for providing stored energy to said display driver; and a controller for controlling a timing of an active phase, an inactive phase, and a driving phase, wherein said controller controls said converter for providing energy at said converted voltage to said storage device to charge said storage device during the active phase, and wherein said controller deactivates said converter during the inactive phase such that said converter is not providing any substantial energy to said energy storage device, wherein a consumption of power by said converter is substantially reduced during said inactive phase, and further wherein said storage device provides stored energy to said display driver for updating a display image on said display during at least a substantial portion of said driving phase that does not overlap with said active phase, and wherein the duration of said driving phase is longer than the duration of said active phase. - View Dependent Claims (25, 26, 27, 28, 29)
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30. A method of using a commercial voltage converter to power a display, said method comprising the steps of:
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storing energy provided by the converter during an active phase; not providing energy from the converter during an inactive phase, wherein power consumption by said converter during said inactive phase is substantially reduced; and updating an image on a display during at least a portion of said inactive phase using stored energy, wherein the duration of said at least a portion of said inactive phase is longer than the duration of said active phase. - View Dependent Claims (31, 32)
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Specification