Device and method for detecting multiple touch points
First Claim
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1. A method for detecting a touch screen, the touch screen including a first conductive layer and a second conductive layer, each conductive layer having a positive terminal and a negative terminal, the method comprising:
- coupling the positive terminal of the second conductive layer to a positive reference voltage, coupling the negative terminal of the second conductive layer to a negative reference voltage, sampling the positive terminal of the first conductive layer to obtain a series of first voltage samples V1(i), sampling the negative terminal of the first conductive layer to obtain a series of second voltage samples V2(i);
coupling the positive terminal of the first conductive layer to the positive reference voltage, coupling the negative terminal of the first conductive layer to the negative reference voltage, sampling the positive terminal of the second conductive layer to obtain a series of third voltage samples V3(i), sampling the negative terminal of the second conductive layer to obtain a series of fourth voltage samples V4(i), wherein i is a sampling number;
calculating a rotating parameter X(i) according to the first voltage samples V1(i), the second voltage samples V2(i), the third voltage samples V3(i) and the fourth voltage samples V4(i); and
determining a rotating direction of two touch points in the touch screen according to the rotating parameter X(i), whereinthe rotating parameter X(i) is a function of
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Abstract
Techniques for detecting multiple touch points for touch screens are disclosed. A touch screen includes a first conductive layer and a second conductive layer, each conductive layer having a positive terminal and a negative terminal. Efficient operations of detecting multiple points on the touch screen are described using various voltage/currents differences from the positive and negative terminals of the first and second conductive layers.
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Citations
11 Claims
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1. A method for detecting a touch screen, the touch screen including a first conductive layer and a second conductive layer, each conductive layer having a positive terminal and a negative terminal, the method comprising:
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coupling the positive terminal of the second conductive layer to a positive reference voltage, coupling the negative terminal of the second conductive layer to a negative reference voltage, sampling the positive terminal of the first conductive layer to obtain a series of first voltage samples V1(i), sampling the negative terminal of the first conductive layer to obtain a series of second voltage samples V2(i); coupling the positive terminal of the first conductive layer to the positive reference voltage, coupling the negative terminal of the first conductive layer to the negative reference voltage, sampling the positive terminal of the second conductive layer to obtain a series of third voltage samples V3(i), sampling the negative terminal of the second conductive layer to obtain a series of fourth voltage samples V4(i), wherein i is a sampling number; calculating a rotating parameter X(i) according to the first voltage samples V1(i), the second voltage samples V2(i), the third voltage samples V3(i) and the fourth voltage samples V4(i); and determining a rotating direction of two touch points in the touch screen according to the rotating parameter X(i), wherein the rotating parameter X(i) is a function of - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A device for detecting touch screen, comprising:
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a touch screen having a first conductive layer and a second conductive layer, each of the first and second conductive layers having a positive terminal and a negative terminal; a selector configured to couple the positive terminal of the second conductive layer to a positive reference voltage, couple the negative terminal of the second conductive layer to a negative reference voltage, couple the positive terminal of the first conductive layer to the positive reference voltage, and couple the negative terminal of the first conductive layer to the negative reference voltage; an analog-to-digital converter configured to sample the positive terminal of the first conductive layer to obtain a series of first voltage samples V1(i), sample the negative terminal of the first conductive layer to obtain a series of second voltage samples V2(i), sample the positive terminal of the second conductive layer to obtain a series of third voltage samples V3(i), and sample the negative terminal of the second conductive layer to obtain a series of fourth voltage samples V4(i), wherein i is a sampling sequence number; a micro-processor configured to calculate a rotating parameter X(i) according to the first voltage samples V1(i), the second voltage samples V2(i), the third voltage samples V3(i) and the fourth voltage samples V4(i) and determine a rotating direction of two touch points on the touch screen according to the rotating parameter X(i); and
whereinthe rotating parameter X(i) is a function of and
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Specification