Control chip for touch panel with high sensitivity
AssigneePixart Imaging Inc.
InventorSung-Han Wu
Life of this patent
Estimating the term…
Abstract
There is provided a capacitive touch device including a touch panel and a control chip. The touch panel includes a detection electrode configured to form a self-capacitor. The control chip includes an emulation circuit and a subtraction circuit. The emulation circuit is configured to output a reference signal. The subtraction circuit is coupled to the emulation circuit and the detection electrode, subtracts the reference signal outputted by the emulation circuit from a detected signal outputted by the detection electrode to output a differential detected signal, and identifies a touch event according to an amplified differential detected signal so as to improve the touch sensitivity.
Claims16
A control chip for a touch panel, the touch panel comprising a detection electrode configured to form a self-capacitor, the control chip comprising:
- an input resistor coupled to an output end of the detection electrode;
- an amplifying circuit connected with the input resistor;
- a subtraction circuit;
- a switch connected between the amplifying circuit and the subtraction circuit, the switch being located downstream of the amplifying circuit;
- and
- an emulation circuit configured to output a reference signal to the subtraction circuit;
- wherein the input resistor and the amplifying circuit form a first filter circuit with the self-capacitor for outputting a detection signal from the amplifying circuit, and the emulation circuit forms a second filter circuit;
- wherein the subtraction circuit performs a differential operation between the reference signal and the detection signal outputted from the amplifying circuit in a self-capacitive mode to improve touch sensitivity, and the differential operation in the self-capacitive mode is performed by coupling the subtraction circuit to the amplifying circuit using the switch;
- and
- wherein a detection operation is performed in a mutual-capacitive mode by bypassing the subtraction circuit, and the subtraction circuit is bypassed by decoupling the subtraction circuit from the amplifying circuit using the switch.
A control chip for a touch panel, the touch panel comprising a plurality of detection electrodes respectively configured to form a self-capacitor, the control chip comprising:
- an emulation circuit configured to output a reference signal;
- a plurality of programmable filters respectively coupled to signal outputs of the detection electrodes;
- a plurality of switches respectively located downstream of the programmable filters and connected to the programmable filters;
- and
- a subtraction circuit, connected to the emulation circuit and located downstream of the plurality of switches;
- wherein the subtraction circuit performs a differential operation in a self-capacitive mode for outputting a differential detected signal according to the reference signal outputted by the emulation circuit and a detection signal outputted by the coupled programmable filter, and the differential operation in the self-capacitive mode is performed by coupling the subtraction circuit to the programmable filters sequentially using the plurality of switches;
- and
- wherein a detection operation is performed in a mutual-capacitive mode by bypassing the subtraction circuit, and the subtraction circuit is bypassed by decoupling the subtraction circuit from the plurality of programmable filters using the plurality of switches.
A control chip for a touch panel, the touch panel comprising a detection electrode configured to form a capacitor, the control chip comprising:
- an input resistor coupled to an output end of the detection electrode;
- an amplifying circuit connected with the input resistor;
- a subtraction circuit;
- a switch connected between the amplifying circuit and the subtraction circuit, the switch being located downstream of the amplifying circuit;
- and
- an emulation circuit configured to output a reference signal to the subtraction circuit;
- wherein the capacitor, the input resistor and the amplifying circuit form a first filter circuit for outputting a detection signal from the amplifying circuit, and the emulation circuit forms a second filter circuit;
- wherein in identifying a rough position of an approaching object, the subtraction circuit performs a differential operation between the reference signal and the detection signal, and the differential operation is performed by coupling the subtraction circuit to the amplifying circuit using the switch;
- and
- wherein in identifying a fine position of the approaching object after the rough position is identified, a detection operation is performed by bypassing the subtraction circuit, and the subtraction circuit is bypassed by decoupling the subtraction circuit from the amplifying circuit using the switch.
Dependencies are inferred from the claim text.