SENSING CIRCUIT FOR USE WITH CAPACITIVE TOUCH PANEL
First Claim
1. A sensing circuit for use with a receiving electrode of a capacitive touch panel, a mutual capacitance existing between a driving electrode of the capacitive touch panel and the receiving electrode, the driving electrode receiving a driving signal, the sensing circuit comprising:
- an operation amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein a reference voltage is inputted into the positive input terminal of the operation amplifier;
a first switch connected between the receiving electrode and the negative input terminal of the operation amplifier;
a second switch connected between the negative input terminal and the output terminal of the operation amplifier;
a first feedback capacitor;
a second feedback capacitor;
a third switch having a first terminal connected to the negative input terminal of the operation amplifier and a second terminal connected to a first terminal of the first feedback capacitor;
a fourth switch having a first terminal connected to a second terminal of the first feedback capacitor and a second terminal connected to the output terminal of the operation amplifier;
a fifth switch having a first terminal connected to the negative input terminal of the operation amplifier and a second terminal connected to a first terminal of the second feedback capacitor; and
a sixth switch having a first terminal connected to a second terminal of the second feedback capacitor and a second terminal connected to the output terminal of the operation amplifier,wherein the driving signal generates at least one pulse during a driving cycle, wherein in response to a rising edge of the pulse, the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch are controlled, so that the first feedback capacitor is charged in a first charging direction, wherein in response to a falling edge of the pulse, the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch are controlled, so that the second feedback capacitor is charged in a second charging direction.
1 Assignment
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Accused Products
Abstract
A sensing circuit of a capacitive touch panel includes an operation amplifier, a first switch, a second switch, first and second feedback capacitors, a third switch, a fourth switch, a fifth switch and a sixth switch. The operation amplifier includes a positive input terminal, a negative input terminal and an output terminal. A reference voltage is inputted into the positive input terminal. The first switch is connected between a receiving electrode and the negative input terminal. The second switch is connected between the negative input terminal and the output terminal. The third switch is connected to the negative input terminal and the first feedback capacitor. The fourth switch is connected to the first feedback capacitor and the output terminal. The fifth switch is connected to the negative input terminal and the second feedback capacitor. The sixth switch is connected to the second feedback capacitor and the output terminal.
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Citations
19 Claims
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1. A sensing circuit for use with a receiving electrode of a capacitive touch panel, a mutual capacitance existing between a driving electrode of the capacitive touch panel and the receiving electrode, the driving electrode receiving a driving signal, the sensing circuit comprising:
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an operation amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein a reference voltage is inputted into the positive input terminal of the operation amplifier; a first switch connected between the receiving electrode and the negative input terminal of the operation amplifier; a second switch connected between the negative input terminal and the output terminal of the operation amplifier; a first feedback capacitor; a second feedback capacitor; a third switch having a first terminal connected to the negative input terminal of the operation amplifier and a second terminal connected to a first terminal of the first feedback capacitor; a fourth switch having a first terminal connected to a second terminal of the first feedback capacitor and a second terminal connected to the output terminal of the operation amplifier; a fifth switch having a first terminal connected to the negative input terminal of the operation amplifier and a second terminal connected to a first terminal of the second feedback capacitor; and a sixth switch having a first terminal connected to a second terminal of the second feedback capacitor and a second terminal connected to the output terminal of the operation amplifier, wherein the driving signal generates at least one pulse during a driving cycle, wherein in response to a rising edge of the pulse, the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch are controlled, so that the first feedback capacitor is charged in a first charging direction, wherein in response to a falling edge of the pulse, the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch are controlled, so that the second feedback capacitor is charged in a second charging direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A sensing circuit for use with a receiving electrode of a capacitive touch panel, a mutual capacitance generating between a driving electrode of the capacitive touch panel and the receiving electrode, the driving electrode receiving a driving signal, the sensing circuit comprising:
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an operation amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein a reference voltage is inputted into the positive input terminal of the operation amplifier; a first switch connected between the receiving electrode and the negative input terminal of the operation amplifier; a second switch connected between the negative input terminal and the output terminal of the operation amplifier; a feedback capacitor; a third switch having a first terminal connected to the negative input terminal of the operation amplifier and a second terminal connected to a first terminal of the feedback capacitor; a fourth switch having a first terminal connected to a second terminal of the feedback capacitor and a second terminal connected to the output terminal of the operation amplifier; a fifth switch connected between the second terminal of the feedback capacitor and the negative input terminal of the operation amplifier; and a sixth switch connected between the first terminal of the feedback capacitor and the output terminal of the operation amplifier, wherein the driving signal generates at least one pulse during a driving cycle, in response to a rising edge and a falling edge of the pulse, the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch are controlled, so that the feedback capacitor is charged in a first charging direction. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification