Single wire interface for LCD calibrator
First Claim
1. A calibration circuit for adjusting a common electrode voltage Vcom for a liquid crystal display (LCD), comprising a controller to receive a first command for changing said common electrode voltage Vcom by way of a single-wire interface, and to cause said common electrode voltage Vcom to change in response to said first command, the controller having a counter to generate a count related to said common electrode voltage Vcom, and a digital-to-analog converter (DAC) to generate an intermediate voltage related to said count.
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Accused Products
Abstract
A calibration circuit and related method for adjusting a common electrode voltage Vcom of a liquid crystal display (LCD) in response to commands received by way of a single-wire interface. The calibration circuit includes a controller to receive and interpret commands in the form of positive and negative pulses for respectively increasing and decreasing Vcom by a predetermined amount per pulse. The calibration circuit also includes a counter for generating a count related to Vcom, wherein the controller causes the count to decrement and increment in response to the positive and negative command pulses. The calibration circuit further includes a non-volatile memory for storing the count, wherein the controller causes the count to be stored into the non-volatile memory in response to another command in the form of a voltage above a predetermined threshold. This voltage is also used for programming the non-volatile memory.
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Citations
48 Claims
- 1. A calibration circuit for adjusting a common electrode voltage Vcom for a liquid crystal display (LCD), comprising a controller to receive a first command for changing said common electrode voltage Vcom by way of a single-wire interface, and to cause said common electrode voltage Vcom to change in response to said first command, the controller having a counter to generate a count related to said common electrode voltage Vcom, and a digital-to-analog converter (DAC) to generate an intermediate voltage related to said count.
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15. A method of adjusting a common electrode voltage Vcom of a liquid crystal display (LCD), comprising:
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generating a count related to said common electrode voltage Vcom; receiving a first command to change said count in a first direction to increase said common electrode voltage Vcom by way of a single-wire interface; increasing said common electrode voltage Vcom in response to said count; receiving a second command to change said count in a second direction to decrease said common electrode voltage Vcom by way of said single-wire interface; and decreasing said common electrode voltage Vcom in response to said count; receiving a third command to store said count in a non-volatile memory by way of said single-wire interface; storing said count in said non-volatile memory in response to said third command. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A calibration circuit for use in adjusting a common electrode voltage Vcom for a liquid crystal display (LCD) comprising:
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a controller to receive commands by way of a single-wire interface; an up/down counter coupled to the controller; electrically reprogrammable nonvolatile storage coupled to the controller and to an output of the up/down counter; a digital to analog converter (DAC) having an input coupled to the output of the up/down counter, an output of the DAC being coupled to provide a calibration circuit output; the up/down counter having a power on reset for resetting the counter to a count stored in the nonvolatile storage on application of power to the calibration circuit; the controller being responsive to a first command from the single wire interface to cause the counter to increase its count; the controller being responsive to a second command from the single wire interface to cause the counter to decrease its count; the controller being responsive to a third command from the single wire interface to cause the nonvolatile storage to store a count from the up/down counter. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A calibration circuit for use in adjusting a common electrode voltage Vcom for a liquid crystal display (LCD) comprising:
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a controller coupled to receive commands by way of a single-wire interface; an up/down counter coupled to the controller; electrically reprogrammable nonvolatile storage coupled to the controller and to an output of the up/down counter; a digital to analog converter (DAC) having an input coupled to the output of the up/down counter, an output of the DAC being coupled to provide an adjustable calibration circuit current sink output; the up/down counter having a power on reset for resetting the counter to a count stored in the nonvolatile storage on application of power to the calibration circuit; the controller being responsive to a first pulse of reduced voltage from the single wire interface relative to a threshold voltage for at least a predetermined time to cause the counter to increase its count; the controller being responsive to a second pulse of increased voltage from the single wire interface relative to a threshold voltage for at least a predetermined time to cause the counter to decrease its count; the controller being responsive to a programming voltage pulse from the single wire interface to cause the nonvolatile storage to store a count from the up/down counter, the controller being configured to distinguish between the programming voltage pulse and the second pulse by sensing the rise in voltage above a voltage exceeding the voltage of a first pulse in less than the predetermined time. - View Dependent Claims (44, 45, 46, 47, 48)
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Specification