Touch detection circuit and denoising circuit thereof
AssigneePixart Imaging Inc.
InventorsShiue-Shin Liu, Chang-Yuan Liou, Cheng-Chih Chang
Life of this patent
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Abstract
There is provided a denoising circuit connecting to two pins of a chip. The denoising circuit includes a shielding branch, a driving branch and an intermediate capacitor. The shielding branch is connected between a first pin of the chip, a ground voltage and a shielding metal. The driving branch is connected between a second pin of the chip and a load. The intermediate capacitor is connected between the shielding branch and the driving branch. The first pin and the second pin are used to respectively output a sinusoidal signal.
Claims20
A denoising circuit, arranged on a circuit board having a contact configured to be coupled to a load, which is configured to be touched or untouched, the denoising circuit comprising:
- a first resistor, configured to be coupled between a first signal source and a first node;
- a first capacitor, connected between the first node and ground;
- a second resistor, configured to be coupled between a second signal source and a second node;
- a second capacitor, connected between the first node and the second node;
- a third resistor, connected to the second node;
- a third capacitor, connected between the third resistor and a driving trace, wherein the driving trace is configured to be connected to the contact;
- and
- a shielding metal, arranged on the circuit bard surrounding the driving trace, and extending to the contact without extending out of the circuit board.
A touch detection circuit, configured to detect an impedance variation of a load, which is configured to be touched or untouched, the touch detection circuit comprising:
- a chip, arranged on a circuit board having a contact configured to be coupled to the load;
- and
- a denoising circuit, arranged on the circuit board between the chip and the contact, and comprising:
- a first resistor, configured to be coupled between a first signal source of the chip and a first node;
- a first capacitor, connected between the first node and ground;
- a second resistor, configured to be coupled between a second signal source of the chip and a second node;
- a second capacitor, connected between the first node and the second node;
- a third resistor, connected to the second node;
- a third capacitor, connected between the third resistor and a driving trace, wherein the driving trace is configured to be connected to the contact;
- and
- a shielding metal, arranged on the circuit bard surrounding the driving trace, and extending to the contact without extending out of the circuit board.
A touch detection circuit, configured to detect an impedance variation of a load, which is configured to be touched or untouched, the touch detection circuit comprising:
- a chip, arranged on a circuit board having a contact configured to be coupled to the load, and comprising a first pin and a second pin respectively configured to output a sinusoidal signal;
- a shielding metal;
- a shielding branch, connected between the first pin, a ground voltage and the shielding metal, and configured to direct noises to the ground voltage;
- a driving branch, connected between the second pin and the contact, and comprising a driving trace extended on the circuit board and connected to the contact, wherein the shielding metal surrounds the driving trace but does not extend out of the circuit board;
- and
- an intermediate capacitor, connected between the shielding branch and the driving branch.
Dependencies are inferred from the claim text.