LOW-POWER TOUCH SCREEN CONTROLLER
First Claim
1. An integrated circuit comprising:
- a first pair of terminals;
a second pair of terminals;
a control circuit that during a first time period supplies one of a plurality of selectable voltages onto a first of the first pair of terminals and that couples a second of the first pair of terminals to a ground potential, and that during a second time period supplies said one of the plurality of selectable voltages onto a first of the second pair of terminals and that couples a second of the second pair of terminals to the ground potential; and
an analog-to-digital converter (ADC) that measures a first voltage present on one of the terminals of the second pair of terminals during the first time period and generates therefrom a first measurement value, and that measures a second voltage present on one of the terminals of the first pair of terminals during the second time period and generates therefrom a second measurement value.
1 Assignment
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Accused Products
Abstract
While taking X-Y coordinate measurements to determine the location of a point of contact on a touch screen, a controller circuit drives the touch screen with a selectable voltage. Voltages output from the touch screen are converted by an ADC into the X-coordinate and Y-coordinate values. The ADC has a convertible input voltage range. If only a low touch screen detection resolution is required, then the voltage with which the touch screen is driven is made to be substantially less than the convertible input voltage range. Only a portion of the convertible input range is usable, but this is adequate for the application and power consumption is reduced. If a higher touch screen detection resolution is required, then the touch screen is driven with a higher voltage. Power consumption is increased, but more or all of the convertible input voltage range of the ADC is then usable.
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Citations
26 Claims
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1. An integrated circuit comprising:
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a first pair of terminals; a second pair of terminals; a control circuit that during a first time period supplies one of a plurality of selectable voltages onto a first of the first pair of terminals and that couples a second of the first pair of terminals to a ground potential, and that during a second time period supplies said one of the plurality of selectable voltages onto a first of the second pair of terminals and that couples a second of the second pair of terminals to the ground potential; and an analog-to-digital converter (ADC) that measures a first voltage present on one of the terminals of the second pair of terminals during the first time period and generates therefrom a first measurement value, and that measures a second voltage present on one of the terminals of the first pair of terminals during the second time period and generates therefrom a second measurement value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for controlling a touch screen, the system comprising:
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an analog-to-digital converter (ADC) that measures a voltage received from the touch screen during a time period, wherein the ADC has a convertible input voltage range over which it can generate an output measurement corresponding to a voltage on an input of the ADC; and a control circuit that supplies one of a plurality of selectable voltages to the touch screen during the time period, wherein the voltage received by the ADC is due to a current supplied by the control circuit to the touch screen, and wherein said one of the selectable voltages is substantially smaller than the convertible input voltage range. - View Dependent Claims (10)
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11. A system for controlling a touch screen comprising:
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an analog-to-digital converter (ADC) that measures a magnitude of a signal received from the touch screen during a time period; and a control circuit that supplies one of a plurality of selectable currents of different magnitudes to the touch screen during the time period, wherein the signal received by the ADC is due to said one current supplied by the control circuit to the touch screen during the time period. - View Dependent Claims (12)
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13. A method comprising:
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(a) driving a first current into a first terminal of a touch screen, through the touch screen, and out of a second terminal of the touch screen such that a first voltage is present between the first and second terminals; (b) converting a second voltage on a third terminal of the touch screen into a first digital value, wherein the second voltage is present on the third terminal during (a); (c) driving a second current into the first terminal of the touch screen, through the touch screen, and out of the second terminal of the touch screen such that a third voltage is present between the first and second terminals, wherein the third voltage is substantially smaller than the first voltage; and (d) converting a fourth voltage on the third terminal of the touch screen into a second digital value, wherein the fourth voltage is present on the third terminal during (c). - View Dependent Claims (14, 15, 16, 17)
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18. A method comprising:
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(a) providing a control circuit adapted to drive a selectable current into a first terminal of a touch screen, through the touch screen, and out of a second terminal of the touch screen, wherein a first voltage is present between the first and second terminals when the selectable current is flowing; and (b) providing an analog-to-digital converter (ADC) adapted to measure a second voltage present on a third terminal of the touch screen when the selectable current is flowing, wherein the ADC has a convertible input voltage range over which it can generate an output measurement corresponding to a voltage on an input of the ADC, and wherein the convertible input voltage range is substantially larger than the first voltage. - View Dependent Claims (19)
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20. A circuit comprising:
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a first pair of terminals; a second pair of terminals; and means for, during a first measurement time period, driving a first selectable current out of a first terminal of the first pair, through a touch screen, and back into a second terminal of the first pair, and for measuring a first voltage present on a first terminal of the second pair during the flow of the first selectable current, wherein the means is also for, during a second measurement time period, driving a second selectable current out of the first terminal of the first pair, through the touch screen, and back into the second terminal of the first pair, and for measuring a second voltage present on the first terminal of the second pair during the flow of the second selectable current, wherein the second selectable current is substantially smaller than the first selectable current. - View Dependent Claims (21, 22, 23)
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24. A set of instructions stored on a computer-readable medium, wherein execution of the set of instructions is for:
changing a magnitude of a drive current to be driven through a touch screen during a touch screen point of contact location measurement. - View Dependent Claims (25, 26)
Specification