Active matrix display drive control systems
First Claim
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1. A method of reducing the power consumption of an active matrix electroluminescent display, the method comprising:
- controlling a power supply voltage to at least one pixel of the display, said power supply voltage being output from a power supply;
monitoring, via a current sensing device, a power supply current based on said power supply voltage, said current sensing device disposed between the power supply and the display;
wherein said current sensing device comprises an analogue-to-digital converter configured to sense voltage drop across a resistor,wherein said current sensing device directly provides input to a current sense input of a display drive logic for controlling said power supply voltage,wherein said controlling further comprises progressively reducing said power supply voltage until said power supply current reduces by greater than a threshold,wherein said active matrix electroluminescent display comprises a plurality of pixels each having a driver transistor, andwherein said monitoring and controlling comprises at least periodically monitoring said power supply current and controlling said power supply voltage to maintain said active matrix display in an operating region in which the driver transistor of the plurality of driver transistors having the highest drive level is just within saturation.
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Abstract
This invention relates to methods, apparatus, and computer program code for driving an active matrix display, in particular an organic light emitting diode (OLED) display, with reduced power consumption.
9 Citations
23 Claims
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1. A method of reducing the power consumption of an active matrix electroluminescent display, the method comprising:
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controlling a power supply voltage to at least one pixel of the display, said power supply voltage being output from a power supply; monitoring, via a current sensing device, a power supply current based on said power supply voltage, said current sensing device disposed between the power supply and the display; wherein said current sensing device comprises an analogue-to-digital converter configured to sense voltage drop across a resistor, wherein said current sensing device directly provides input to a current sense input of a display drive logic for controlling said power supply voltage, wherein said controlling further comprises progressively reducing said power supply voltage until said power supply current reduces by greater than a threshold, wherein said active matrix electroluminescent display comprises a plurality of pixels each having a driver transistor, and wherein said monitoring and controlling comprises at least periodically monitoring said power supply current and controlling said power supply voltage to maintain said active matrix display in an operating region in which the driver transistor of the plurality of driver transistors having the highest drive level is just within saturation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An active matrix display driver, comprising a plurality of pixels, each pixel having a driver transistor, for driving an active matrix electroluminescent display, the driver comprising:
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a controller for controlling a power supply voltage to at least one pixel of the display, said power supply voltage being output from a power supply; a monitor for monitoring, via a current sensing device, a power supply current based on said power supply voltage, said current sensing device disposed between the power supply and the display; wherein said current sensing device comprises an analogue-to-digital converter configured to sense voltage drop across a resistor, wherein said current sensing device directly provides input to a current sense input of a display drive logic for controlling said power supply voltage, wherein said controller progressively reduces said power supply voltage until said power supply current reduces by greater than a threshold, and wherein the monitor is operable to at least periodically monitor the power supply current and the controller is operable to control the power supply voltage to maintain the display in an operating region in which the driver transistor of the plurality of driver transistors having the highest drive level is just within saturation. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A controller for a driver of an active matrix electroluminescent display, the display having a plurality of pixels each having an electroluminescent display element and an associated drive transistor, the display having a power supply line for providing power to the driver transistors of said pixels;
- the driver comprising a pixel data driver to drive said display pixels with data for display, a controllable voltage power supply to provide a power supply voltage to said power supply line, and a current sensing device to sense a current in said power supply line;
the controller comprising;a current sense input for said current sensing device, said current sense input being determined by the sensed current which is based on said power supply voltage, said current sensing device disposed between the power supply and the display; a voltage control output for said controllable voltage power supply to provide power to at least one pixel of said display; and a voltage controller to provide a voltage control signal for said voltage control output responsive to a current sense signal from said current sense input, wherein said current sensing device comprising an analogue-to-digital converter configured to sense voltage drop across a resistor; wherein said current sensing device directly provides input to said current sense input of a display drive logic for controlling said power supply voltage, wherein the voltage controller is operable to at least periodically monitor the current sense signal from the current sense input and the controller is operable to control the voltage control output for the controllable supply voltage to maintain the electroluminescent display in an operating region in which the driver transistor of the plurality of driver transistors having the highest drive level is just within saturation. - View Dependent Claims (21, 22, 23)
- the driver comprising a pixel data driver to drive said display pixels with data for display, a controllable voltage power supply to provide a power supply voltage to said power supply line, and a current sensing device to sense a current in said power supply line;
Specification