US-12619331-B2 - Touch circuit, touch detection amplifying circuit and touch apparatus

US12619331B2US 12619331 B2US12619331 B2US 12619331B2US-12619331-B2

Abstract

A touch circuit, a touch detection amplifying circuit, and a touch apparatus are provided, which include a charge generating circuit, a charging circuit, a controlling circuit, a touch detection amplifying circuit, and a data processing circuit. The charge generating circuit detects sensing capacitances. The controlling circuit controls the charging circuit to charge the charge generating circuit for decreasing an effect of a self-capacitor in the charge generating circuit in related to a sensing voltage outputted by the touch detection amplifying circuit. The touch detection amplifying circuit converts the sensing capacitance into the sensing voltage. The data processing circuit outputs a control signal based on the sensing voltage outputted by the touch detection amplifying circuit for adjusting a capacitance of the charging capacitor in the charging circuit or the common-mode capacitor in the touch detection amplifying circuit, thus the sensing voltage is in a valid signal range of a common-mode voltage.

Inventors

AIHUAN SHI
Jiannan Huang
Junqiao Liu

Assignees

FOCALTECH SYSTEMS (SHENZHEN) CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20230208
Priority Date: 20220527

Claims (20)

1 . A touch circuit, wherein the touch circuit comprises a charge generating circuit, a charging circuit, a controlling circuit, a touch detection amplifying circuit, and a data processing circuit; the charge generating circuit is configured to implement scan under a control of a specified timing for detecting sensing capacitances generated by sensing electrodes after being touched by a user; the controlling circuit is configured to control the charging circuit to charge or discharge the charge generating circuit; the touch detection amplifying circuit is electrically connected with the charging circuit and the controlling circuit; the charging circuit comprises a charging capacitor; the charging capacitor is electrically connected with the controlling circuit and the touch detection amplifying circuit through a node; the touch detection amplifying circuit is configured to convert the sensing capacitance outputted by the charge generating circuit into a sensing voltage for identifying a touch operation and a touch position; the data processing circuit is configured to output a control signal based on the sensing voltage outputted by the touch detection amplifying circuit for adjusting a capacitance of the charging capacitor, which causes the sensing voltage outputted by the touch detection amplifying circuit in a valid signal range of a common-mode voltage.
2 . The touch circuit of claim 1 , wherein the data processing circuit determines whether a difference between the sensing voltage and a predefined common-mode voltage is located in a predefined difference range; while the difference is besides the predefined difference range, it is determined that the capacitance of the charging capacitor needs to be corrected, the data processing circuit adjusts the capacitance of the charging capacitor according to the difference between the sensing voltage and the predefined common-mode voltage; while the difference is located in the predefined difference range, it determines that the capacitance of the charging capacitor does not need to be corrected, and the capacitance of the charging capacitor is stored.
3 . The touch circuit of claim 2 , wherein the capacitance of the charging capacitor changes with the sensing voltage detected by the data processing circuit in a direct proportional manner; while the difference is a positive value, the data processing circuit outputs the controlling signal for decreasing the capacitance of the charging capacitor; while the difference is a negative value, the data processing circuit outputs the controlling signal for increasing the capacitance of the charging capacitor.
4 . The touch circuit of claim 1 , wherein the controlling circuit comprises a first control switch, a second control switch, and a third control switch; a terminal of the first control switch receives a power source voltage, and another terminal of the first control switch is electrically connected with the sensing electrodes; a terminal of the second control switch is grounded, and another terminal of the second control switch is electrically connected with the sensing electrodes; a terminal of the third control switch electrically connected with the sensing electrodes, and another terminal of the third control switch is electrically connected with the touch detection amplifying circuit through a node of the charging circuit.
5 . The touch circuit of claim 1 , wherein the touch detection amplifying circuit comprises: an amplifier, configured to convert a sensing capacitance outputted by the charge generating circuit into a sensing voltage; a first input terminal of the amplifier is electrically connected with the charge generating circuit; a reset switch, a terminal of the reset switch is electrically connected with the first input terminal of the amplifier, and another terminal of the reset switch is electrically connected with the output terminal of the amplifier; and a main capacitor, being connected between the first input terminal and the output terminal of the amplifier in series.
6 . The touch circuit of claim 5 , wherein the touch detection amplifying circuit further comprises: a sampling module, configured to sample the voltage outputted by the amplifier and output a sampling voltage; a plurality of assistance capacitors, a terminal of each of the plurality of the assistance capacitors is electrically connected with the first input terminal of the amplifier through a first switch component, and another terminal of each of the plurality of the assistance capacitors is electrically connected with the output terminal of the amplifier through a second switch component; while the reset switch is turned on, and there is a difference between the sampling voltage and a target voltage, at least one of the plurality of the assistance capacitors is time multiplexed as a common-mode capacitor for storing charges, while the reset switch is turned off, at least one of the plurality of the assistance capacitors adjusts the voltage of the output terminal of the amplifier; while the reset switch is turned off, the first switch component and the second switch component of the assistance capacitors are turned on, the plurality of the assistance capacitors are served as access capacitors being connected with the main capacitor in series; a common-mode parameter adjusting module, electrically connected with the sampling module; the common-mode parameter adjusting module sets at least one of the plurality of the assistance capacitors to be time multiplexed as the common-mode capacitor by controlling at least one of the plurality of the first switch components to be turned on while there is a difference between the sampling voltage and the target voltage, and outputs a shift control signal; and a shift driving module, electrically connected with the common-mode parameter adjusting module, and electrically connected with each of the plurality of the assistance capacitors through the plurality of three switch components respectively; while the reset switch is turned on, the shift driving module is configured to control the plurality of the third switch components corresponding to the common-mode capacitors to be turned on, and charge the common-mode capacitors according to the shift control signal.
7 . The touch circuit of claim 6 , wherein the plurality of the assistance capacitors are coded in binary format according to an arrangement order; the capacitances of each of the plurality of the assistance capacitors are different from each other, and are arranged in geometric progression with a geometric ratio; at least one of the plurality of the assistance capacitors serves as the common-mode capacitor by setting a bit, the common-mode capacitors are selected in a manner of binary.
8 . The touch circuit of claim 6 , wherein the common-mode parameter adjusting module stores a look-up table; the look-up table records a relationship between different capacitances of the common-mode capacitor and different bits; the common-mode parameter adjusting module uses a difference between the sampled voltage and the target voltage as a shifted value, calculates a capacitance of the common-mode capacitor based on the shifted value and the capacitance of the access capacitors, and obtains a value of the bit corresponding to the capacitance of the common-mode capacitor by table look-up, for adjusting the number of the assistance capacitor serving as the common-mode capacitors.
9 . The touch circuit of claim 1 , wherein the charging capacitor comprises a plurality of charging sub-capacitors, a plurality of first switch components, and a plurality of second switch components; a terminal of each of the plurality of the charging sub-capacitors is electrically connected with the node through one of the plurality of the first switch components, another terminal of each of the plurality of the charging sub-capacitors receives a pulse voltage through one of the plurality of the second switch components; the charging sub-capacitors are coded in binary format according to an arrangement order; capacitances of the charging sub-capacitors are different from each other, and are arranged in geometric progression with a geometric ratio; at least one of the plurality of the charging sub-capacitors is selected as the charging capacitor by setting a bit, for adjusting the capacitance of the charging capacitor in a manner of binary format.
10 . The touch circuit of claim 1 , wherein charging capacitor comprises a plurality of charging sub-capacitors, a plurality of first switch components, and a plurality of second switch components; a terminal of each of the plurality of the charging sub-capacitors is electrically connected with the node through one of the plurality of the first switch components, another terminal of each of the plurality of the charging sub-capacitors receives a pulse voltage through one of the plurality of the second switch components; the charging sub-capacitors are coded in one-hot code format; capacitances of the charging sub-capacitors are the same.
11 . The touch circuit of claim 1 , wherein in each operation period, the touch apparatus operates in a positive half-period and a negative half-period in that order; in the positive half-period, the data processing circuit controls the capacitance of the charging capacitor to be maintained at a predefined capacitance; in the negative half-period, the data processing circuit controls the capacitance of the charging capacitor to be adjusted according to the sensing voltage.
12 . The touch circuit of claim 11 , wherein the positive half-period comprises a first period and a second period; in the first period, the controlling circuit controls the charge generating circuit and the touch detection amplifying circuit to be reset; in the second period, the controlling circuit controls the charging circuit to discharge for charging a self-capacitor in the charge generating circuit; the negative half-period comprise a third period and a fourth period; in the third period, the controlling circuit provides a power source voltage to charge the charge generating circuit, and controls the touch detection amplifying circuit to discharge; in the fourth period, the controlling circuit controls the charge generating circuit to discharge, for transferring the charge stored in a body capacitor of the charge generating circuit to the touch detection amplifying circuit.
13 . The touch circuit of claim 12 , wherein charging circuit comprise a buffer; the buffer provides a received pulse voltage to the charging capacitor; in the second period and the third period, the buffer provides the power source voltage to the charging capacitor; in the first period and the fourth period, the buffer provides a ground voltage to the charging capacitor.
14 . A touch detection amplifying circuit, electrically connected with a charge generating circuit; wherein the touch detection amplifying circuit comprises: an amplifier, configured to convert a sensing capacitance outputted by the charge generating circuit into a sensing voltage; a first input terminal of the amplifier is electrically connected with the charge generating circuit; a sampling module, configured to sample the voltage outputted by the amplifier and output a sampling voltage; a reset switch, a terminal of the reset switch is electrically connected with the first input terminal of the amplifier, and another terminal of the reset switch is electrically connected with the output terminal of the amplifier; a main capacitor, being connected between the first input terminal and the output terminal of the amplifier in series; a plurality of assistance capacitors, a terminal of each of the plurality of the assistance capacitors is electrically connected with the first input terminal of the amplifier through a first switch component, and another terminal of each of the plurality of the assistance capacitors is electrically connected with the output terminal of the amplifier through a second switch component; while the reset switch is turned on, and there is a difference between the sampling voltage and a target voltage, at least one of the plurality of the assistance capacitors is time multiplexed as a common-mode capacitor for storing charges, while the reset switch is turned off, at least one of the plurality of the assistance capacitors adjusts the voltage of the output terminal of the amplifier; while the reset switch is turned off, the first switch component and the second switch component of the assistance capacitors are turned on, the plurality of the assistance capacitors are served as access capacitors being connected with the main capacitor in series; a common-mode parameter adjusting module, electrically connected with the sampling module; the common-mode parameter adjusting module sets at least one of the plurality of the assistance capacitors to be time multiplexed as the common-mode capacitor by controlling at least one of the plurality of the first switch components to be turned on while there is a difference between the sampling voltage and the target voltage, and outputs a shift control signal; and a shift driving module, electrically connected with the common-mode parameter adjusting module, and electrically connected with each of the plurality of the assistance capacitors through the plurality of three switch components respectively; while the reset switch is turned on, the shift driving module is configured to control the plurality of the third switch components corresponding to the common-mode capacitors to be turned on, and charge the common-mode capacitors according to the shift control signal.
15 . The touch detection amplifying circuit of claim 14 , wherein the plurality of the assistance capacitors are coded in binary format according to an arrangement order; the capacitances of each of the plurality of the assistance capacitors are different from each other, and are arranged in geometric progression with a geometric ratio; at least one of the plurality of the assistance capacitors serves as the common-mode capacitor by setting a bit, the common-mode capacitors are selected in a manner of binary.
16 . The touch detection amplifying circuit of claim 15 , wherein the common-mode parameter adjusting module stores a look-up table; the look-up table records a relationship between different capacitances of the common-mode capacitor and different bits; the common-mode parameter adjusting module uses a difference between the sampled voltage and the target voltage as a shifted value, calculates a capacitance of the common-mode capacitor based on the shifted value and the capacitance of the access capacitors, and obtains a value of the bit corresponding to the capacitance of the common-mode capacitor by table look-up, for adjusting the number of the assistance capacitor serving as the common-mode capacitors.
17 . The touch detection amplifying circuit of claim 16 , wherein the capacitance of the common-mode voltage is calculated by a formular, which is Cp=Vdiff/Vt*Cfb; wherein Cp represents the capacitance of the common-mode capacitor, Vdiff represents the difference between the sampled voltage and the target voltage, Cfb represents a sum of the capacitance of the access capacitors.
18 . The touch detection amplifying circuit of claim 14 , wherein the common-mode parameter adjusting module further compares the sampled voltage and the target voltage and outputs a shift control signal based on a comparison result, for confirming a shifting direction; while the sampled voltage is larger than the target voltage, the common-mode parameter adjusting module outputs a first shift control signal, for adjusting the voltage of the amplifier downwardly; while the sampled voltage is less than the target voltage, the common-mode parameter adjusting module outputs a second shift control signal, for shifting the voltage of the output terminal of the amplifier upwardly.
19 . The touch detection amplifying circuit of claim 18 , wherein the first shift control signal is a ground voltage, the second shift control signal is the power source voltage.
20 . The touch detection amplifying circuit of claim 18 , wherein the first shift control signal and the second shift control signal are pulse signals of same frequency and opposite in phase; the first shift control signal and the controlling signal of the reset switch are pulse signals of same frequency and same phase; the second controlling signal and the controlling signal of the reset switch are pulse signals of same frequency and opposite in phase.

Description

TECHNICAL FIELD The present application generally relates to touch technology, and particular to a touch circuit, a touch detection amplifying circuit, and a touch apparatus. BACKGROUND According to the development of the smart phone, a capacitive touch detection is finding increasing. There are two directions of the capacitive touch detection solution, which are a self-capacitor detection and a mutual capacitance detection. The self-capacitor detection is by far more widely used. In a detection chip integrated with the touch and display together, the touch detection solution simply uses a self-capacitor solution, and in some detection solutions with mutual capacitance in major, an assistance detection with self-capacitor is also needed. In the detection with self-capacitor, magnitude of charge is needed to be measured. In a circuit, the charge signal needs to be converted into voltage signal, thus, a charge amplifier (CA) circuit is needed for converting. However, during a process of manufacturing an integrated circuit, due to uncertainty of each process in a manufacture process, there is a mismatch between components with a same label. The mismatch of the components will change a valid signal range of the CA conversion, an accuracy of the CA is affected, and an apply environment is limited. A related technology mostly uses a method of increasing a size of the component, which will cause a waste in area, and an increase of capacitance of the circuit. Thus, a rate of the circuit is decreased and a dissipation of the circuit is increased. SUMMARY Based on above, it is necessary to provide a touch circuit, a touch detection amplifying circuit, and a touch apparatus, in order to solve the technology problems in a prior art of the valid signal range outputted by a touch detection amplifying circuit being affected by the difference of the component while manufacturing. A touch circuit includes a charge generating circuit, a charging circuit, a controlling circuit, a touch detection amplifying circuit, and a data processing circuit. The charge generating circuit is configured to implement scan under a control of a specified timing for detecting sensing capacitances generated by sensing electrodes after being touched by a user. The controlling circuit is configured to control the charging circuit to charge or discharge the charge generating circuit. The touch detection amplifying circuit is electrically connected with the charging circuit and the controlling circuit. The charging circuit includes a charging capacitor. The charging capacitor is electrically connected with the controlling circuit and the touch detection amplifying circuit through a node. The touch detection amplifying circuit is configured to convert the sensing capacitance outputted by the charge generating circuit into a sensing voltage for identifying a touch operation and a touch position. The data processing circuit is configured to output a control signal based on the sensing voltage outputted by the touch detection amplifying circuit for adjusting a capacitance of the charging capacitor, which causes the sensing voltage outputted by the touch detection amplifying circuit in a valid signal range of a common-mode voltage. A touch detection amplifying circuit, connected with a charge generating circuit. The touch detection amplifying circuit includes: An amplifier, configured to convert a sensing capacitance outputted by the charge generating circuit into a sensing voltage; a first input terminal of the amplifier is electrically connected with the charge generating circuit;A sampling module, configured to sample the voltage outputted by the amplifier and output a sampling voltage;A reset switch, a terminal of the reset switch is electrically connected with the first input terminal of the amplifier, and another terminal of the reset switch is electrically connected with the output terminal of the amplifier;A main capacitor, being connected between the first input terminal and the output terminal of the amplifier in series;A plurality of assistance capacitors, a terminal of each assistance capacitor is electrically connected with the first input terminal of the amplifier through a first switch component, and another terminal of each of the plurality of the assistance capacitors is electrically connected with the output terminal of the amplifier through a second switch component; while the reset switch is turned on, and there is a difference between the sampling voltage and a target voltage, at least one of the plurality of the assistance capacitors is time multiplexed as a common-mode capacitor for storing charges, while the reset switch is turned off, at least one of the plurality of the assistance capacitors adjusts the voltage of the output terminal of the amplifier; while the reset switch is turned off, the first switch component and the second switch component of the assistance capacitors are turned on, the plurality of the assistance capacit