Touch device and sensing compensation method
A touch device and a sensing compensation method are provided. The touch device may include a touch panel, a sensing compensation circuit and a sensing circuit. The sensing compensation circuit may be coupled to the touch panel for providing a compensation-impedance according to features of the touch panel. The sensing circuit may be coupled to the sensing compensation circuit. The sensing circuit receives touch information compensated by the sensing compensation circuit.
1. A touch device, comprising:
a touch panel;
a sensing compensation circuit, having a sensing terminal coupled to a sense line of the touch panel, and providing a compensation-impedance according to features of the touch panel, wherein the compensation-impedance is a negative input impedance; and
a sensing circuit, having an input terminal coupled to an output terminal of the sensing compensation circuit to sense touch information of a touch unit coupled to the sense line in the touch panel via the sensing compensation circuit, and receiving the touch information compensated by the sensing compensation circuit,
wherein the sensing compensation circuit comprises a negative impedance circuit having an input terminal coupled to the touch panel and an output terminal providing touch information of the touch unit of the touch panel, wherein the input terminal of the negative impedance circuit provides the negative input impedance, wherein an absolute value of the negative input impedance falls within an impedance range defined according to an impedance of the sense line of the touch panel, and the negative impedance circuit comprises:
an amplifier, having an inverted input terminal coupled to the input terminal of the negative impedance circuit and an output terminal coupled to the output terminal of the negative impedance circuit;
a first impedance, having a first terminal and a second terminal respectively coupled to the inverted input terminal and the output terminal of the amplifier;
a second impedance, having a first terminal and a second terminal respectively coupled to a non-inverted input terminal and the output terminal of the amplifier; and
a third impedance, having a first terminal and a second terminal respectively coupled to the non-inverted input terminal of the amplifier and a reference voltage.
2. The touch device according to claim 1 , wherein the sensing circuit comprises an integrator, an analog-to-digital converter and a controller.
3. The touch device according to claim 1 , wherein the absolute value of the negative input impedance is equal to the impedance of the sense line of the touch panel.
4. The touch device according to claim 1 , wherein the sensing compensation circuit further comprises:
a buffer, having an input terminal coupled to the output terminal of the negative impedance circuit.
5. The touch device according to claim 1 , wherein one of the first impedance, the second impedance and the third impedance is a first impedance unit, a second impedance unit, a third impedance unit or a fourth impedance unit, wherein
the first impedance unit comprises:
a resistor, a variable resistor, a capacitor, a variable capacitor, an inductor or a variable inductor;
the second impedance unit comprises:
a plurality of switches, wherein first terminals of the switches are jointly coupled to the first input terminal of the amplifier; and
a plurality of resistors, wherein first terminals of the resistors respectively coupled to second terminals of the switches in a one-to-one manner, and second terminals of the resistors are jointly coupled to the output terminal of the amplifier;
the third impedance unit comprises:
a transistor, having a first terminal coupled to the first input terminal of the amplifier and a second terminal coupled to the output terminal of the amplifier; and
the fourth impedance unit comprises:
a plurality of controllable resistance units, wherein a first terminal of a nth controllable resistance unit in the controllable resistance units is coupled to a second terminal of a n-1th controllable resistance unit in the controllable resistance units, a first terminal of a first controllable resistance unit in the controllable resistance units is coupled to the first input terminal of the amplifier, and third terminals of the controllable resistance units are jointly coupled to the output terminal of the amplifier; and
a first resistor, a first terminal of the first resistor is coupled to a second terminal of the last controllable resistance unit in the controllable resistance units, and a second terminal of the first resistor is coupled to the output terminal of the amplifier.
6. The touch device according to claim 5 , wherein one of the controllable resistance units comprises:
a second resistor, having a first terminal served as the first terminal of the controllable resistance unit;
a first multiplexer, having a common terminal coupled to a second terminal of the second resistor, and a first select terminal served as the third terminal of the controllable resistance unit; and
a second multiplexer, having a first select terminal coupled to the first terminal of the second resistor, a second select terminal coupled to a second select terminal of the first multiplexer, and a common terminal of the second multiplexer served as the second terminal of the controllable resistance unit.
7. The touch device according to claim 1 , wherein the sensing compensation circuit further comprises
a controller,
the input terminal of the negative impedance circuit is coupled to the sense line of the touch panel to provide the compensation-impedance, the controller controls the negative impedance circuit to correspondingly adjust the compensation-impedance according to the touch information of the sensing circuit or a physical feature of the touch panel.
8. The touch device according to claim 7 , wherein the touch information of the sensing circuit is a coordinate axis, a digital signal or an analog signal.
9. The touch device according to claim 7 , wherein the physical feature comprises electrical features of the touch panel or change in the electrical features of the touch panel resulted from change of panel type, temperature or humidity change of an environment where the touch panel is located.
10. The touch device according to claim 1 , wherein the sensing compensation circuit further comprises:
a multiplex circuit, having a plurality of select terminals respectively coupled to a plurality of sense lines of the touch panel in a one-to-one manner;
wherein the input terminal of the negative impedance circuit is coupled to a common terminal of the multiplex circuit to provide the compensation-impedance.
11. A sensing compensation method for a touch device, comprising:
providing a touch panel;
providing a compensation-impedance by a sensing compensation circuit according to features of the touch panel, wherein the compensation-impedance is a negative input impedance, to compensate an impedance of a sense line of the touch panel; and
sensing, by a sensing circuit, touch information of a touch unit coupled to the sense line in the touch panel via the sensing compensation circuit, wherein the touch information is compensated by the sensing compensation circuit,
wherein the sensing compensation circuit comprises a negative impedance circuit having an input terminal coupled to the touch panel and an output terminal providing touch information of the touch unit of the touch panel, wherein the input terminal of the negative impedance circuit provides the negative input impedance, an absolute value of the negative input impedance falls within an impedance range defined according to an impedance of the sense line, and the negative impedance circuit comprises:
an amplifier, having an inverted input terminal coupled to the input terminal of the negative impedance circuit and an output terminal coupled to the output terminal of the negative impedance circuit;
a first impedance, having a first terminal and a second terminal respectively coupled to the inverted input terminal and the output terminal of the amplifier;
a second impedance, having a first terminal and a second terminal respectively coupled to a non-inverted input terminal and the output terminal of the amplifier; and
a third impedance, having a first terminal and a second terminal respectively coupled to the non-inverted input terminal of the amplifier and a reference voltage, and
wherein a sensing terminal of the sensing compensation circuit is coupled to the sense line of the touch panel, and a output terminal of the sensing compensation circuit is coupled to an input terminal of the sensing circuit.
12. The method according to claim 11 , wherein the absolute value of the negative input impedance is equal to the impedance of the sense line.
13. The method according to claim 11 , wherein the step of providing the compensation-impedance comprises:
correspondingly adjusting the compensation-impedance by the sensing compensation circuit according to the touch information of the sensing circuit or a physical feature of the touch panel.
14. The method according to claim 13 , wherein the touch information of the sensing circuit is a coordinate axis, a digital signal or an analog signal.
15. The method according to claim 13 , wherein the physical feature comprises electrical features of the touch panel or change in the electrical features of the touch panel resulted from change of panel type, temperature or humidity change of an environment where the touch panel is located.
16. The method according to claim 11 , further comprising:
checking whether the impedance of the sense line of the touch panel is changed;
if the impedance of the sense line is changed, correspondingly adjusting the compensation-impedance.
17. A touch device, comprising:
a touch panel;
a sensing compensation circuit, having a sensing terminal coupled to a sense line of the touch panel, and providing a compensation-impedance according to features of the touch panel, wherein the compensation-impedance is a negative input impedance; and
a sensing circuit, having an input terminal coupled to an output terminal of the sensing compensation circuit to sense touch information of a touch unit coupled to the sense line in the touch panel via the sensing compensation circuit, and receiving the touch information compensated by the sensing compensation circuit,
wherein the sensing compensation circuit comprises a negative impedance circuit, having an input terminal coupled to the touch panel and an output terminal providing touch information of the touch unit of the touch panel, wherein the input terminal of the negative impedance circuit provides the negative input impedance, an absolute value of the negative input impedance falls within an impedance range defined according to an impedance of a sense line of the touch panel, and the negative impedance circuit is a first negative impedance circuit, a second negative impedance circuit or a third negative impedance circuit, wherein
the first negative impedance circuit comprises:
an amplifier, having an inverted input terminal coupled to the input terminal of the negative impedance circuit, and an output ten iinal coupled to the output terminal of the negative impedance circuit ;
a first transistor, having a first terminal and a second terminal respectively coupled to the inverted input terminal and the output terminal of the amplifier;
a second transistor, having a first terminal and a second terminal respectively coupled to a non-inverted input terminal and the output terminal of the amplifier; and
a third transistor, having a first terminal and a second terminal respectively coupled to the non-inverted input terminal of the amplifier and a reference voltage;
the second negative impedance circuit comprises:
an amplifier, having an inverted input terminal coupled to the input terminal of the negative impedance circuit and an output terminal coupled to the output terminal of the negative impedance circuit;
a first variable inductor, having a first terminal and a second terminal respectively coupled to the inverted input terminal and the output terminal of the amplifier;
a second variable inductor, having a first terminal and a second terminal respectively coupled to a non-inverted input terminal and the output terminal of the amplifier; and
a third variable inductor, having a first terminal and a second terminal respectively coupled to the non-inverted input terminal of the amplifier and a reference voltage; and
the third negative impedance circuit comprises:
an amplifier, having an inverted input terminal coupled to the input terminal of the negative impedance circuit and an output terminal coupled to the output terminal of the negative impedance circuit;
a first variable capacitor, having a first terminal and a second terminal respectively coupled to the inverted input terminal and the output terminal of the amplifier;
a second variable capacitor, having a first terminal and a second terminal respectively coupled to a non-inverted input terminal and the output terminal of the amplifier; and
a third variable capacitor, having a first terminal and a second terminal respectively coupled to the non-inverted input terminal of the amplifier and a reference voltage.
18. The touch device according to claim 17 , wherein the sensing circuit comprises an integrator, an analog-to-digital converter and a controller.
19. The touch device according to claim 17 , wherein the absolute value of the negative input impedance is equal to the impedance of the sense line of the touch panel.
20. The touch device according to claim 17 , wherein the sensing compensation circuit further comprises:
a buffer, having an input terminal coupled to the output terminal of the negative impedance circuit.
21. The touch device according to claim 17 , wherein the first negative impedance circuit further comprises:
a first resistor, having a first terminal and a second terminal respectively coupled to the first terminal and a control terminal of the third transistor; and
a second resistor, having a first terminal and a second terminal respectively coupled to a control voltage and the control terminal of the third transistor.
22. The touch device according to claim 17 , wherein the sensing compensation circuit further comprises a controller, the input terminal of the negative impedance circuit is coupled to a sense line of the touch panel to provide the compensation-impedance, wherein the controller controls the negative impedance circuit to correspondingly adjust the compensation-impedance according to the touch information of the sensing circuit or a physical feature of the touch panel.
23. The touch device according to claim 22 , wherein the touch information of the sensing circuit is a coordinate axis, a digital signal or an analog signal.
24. The touch device according to claim 22 , wherein the physical feature comprises electrical features of the touch panel or change in the electrical features of the touch panel resulted from change of panel type, temperature or humidity change of an environment where the touch panel is located.
25. The touch device according to claim 17 , wherein the sensing compensation circuit further comprises:
a multiplex circuit, having a plurality of select terminals respectively coupled to a plurality of sense lines of the touch panel in a one-to-one manner;
wherein the input terminal of the negative impedance circuit is coupled to a common terminal of the multiplex circuit to provide the compensation-impedance.