A system and method for simultaneously processing pressure and capacitive touch signals

Abstract

The application discloses a system and method for simultaneously processing pressure sensing and capacitive touch signal, the system has a SOC pressure touch signal processing engine unit; the SOC pressure touch signal processing engine unit comprises a resistance-capacitance separation unit, a touch algorithm unit, a pressure sensing algorithm unit and a calculation comparison unit, the resistance-capacitance separation unit is used for separating resistance parameters and capacitance parameters of input signals of the sensor, the touch algorithm unit is used for processing the capacitance parameters to obtain touch point values, and the pressure sensing algorithm unit is used for processing the resistance parameters to obtain pressure intensity values; and the calculation comparison unit is used for comparing the touch point values, the pressure intensity values and set reference threshold values. The application is compatible with the advantages of pressure sensing and capacitive touch, overcomes the problems of separately using pressure sensing or capacitive touch, and thus realizes the functions of pressure sensing and touch, which originally need to be realized by collecting two independent sensor signals of different structures through two different digital interfaces in time.

Description

A system and method for simultaneously processing pressure-sensitive and capacitive touch signals. Technical Field

[0001] This invention relates to the field of measurement technology, specifically to a system and method for simultaneously processing pressure-sensitive and capacitive touch signals. Background Technology

[0002] In chip design, when processing capacitive and pressure-sensitive touch signals, capacitive touch signal technology and pressure-sensitive signal technology are generally used. Pure capacitive touch signal technology fails when exposed to water, and pure capacitive touch signals are prone to false triggering.

[0003] Pure pressure-sensitive signal technology determines whether a press has occurred by detecting pressure deformation on the surface of an object. This technology can compensate for the failure of touch technology when exposed to water. However, since a certain amount of force is required to cause pressure deformation on the surface of the object, pure pressure-sensitive signals are greatly affected by the structural tension of the object's surface. It is easy for multiple touch points on the object's surface to be detected as valid presses, resulting in inaccurate detection.

[0004] Existing technologies can no longer meet people's current needs, and based on the current situation, there is an urgent need to reform existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a system and method for simultaneously processing pressure-sensitive and capacitive touch signals, so as to solve the problems mentioned in the background art.

[0006] On one hand, the present invention provides a system for simultaneously processing pressure-sensitive and capacitive touch signals, comprising: a sensor, a SOC (system-on-a-chip) pressure-sensitive signal processing engine unit, an SOC pressure-sensitive channel, an SOC capacitive touch controller, a data bus, and a processor;

[0007] The sensor has a bridge resistor network consisting of resistors R1, R2, R3 and R4;

[0008] Preferably, a precision capacitor C1 is connected in parallel between resistors R1 and R2 in the bridge resistor network;

[0009] Preferably, a precision capacitor C2 is connected in parallel between resistor R3 and resistor R4;

[0010] One end of the precision capacitor C1, Vp1, and one end of the precision capacitor C2, Vn1, are coupled to the SOC pressure-sensitive channel, and the other end of the precision capacitor C1, Vp1_r, and the other end of the precision capacitor C2, Vn1_r, are coupled to the SOC capacitive touch controller.

[0011] The SOC pressure-sensitive signal processing engine unit includes: a resistor-capacitor separation unit, a touch algorithm unit, a pressure-sensitive algorithm unit, and a calculation and comparison unit;

[0012] The resistor-capacitor separation unit is used to separate the resistance and capacitance parameters of the input signal of the sensor;

[0013] The touch algorithm unit is used to perform filtering and baseline tracking algorithms on the capacitance parameters to obtain the touch point value;

[0014] The pressure-sensitive algorithm unit is used to perform pressure-sensitive window sliding filtering on the resistance parameters to obtain the pressure-sensitive force value;

[0015] The calculation and comparison unit compares the touch point value and pressure sensitivity value with a set reference threshold to determine whether the button is valid.

[0016] The SOC is coupled to the processor via a data bus, and the data from the SOC is transmitted to the processor for processing via the data bus.

[0017] On the other hand, the present invention provides another technical solution, a method for simultaneously processing pressure-sensitive and capacitive touch signals, to improve the processing efficiency of the system, the steps of which are as follows:

[0018] S1, a sensor designed to have both capacitive and resistive characteristics;

[0019] S2, the sensors are used together as signal inputs for pressure sensing and touch control;

[0020] S3 separates the capacitance and resistance parameters of the sensor input signal through the SOC pressure-touch signal processing engine unit;

[0021] S4, by analyzing the capacitance parameters of the input signal and performing filtering and baseline tracking algorithm processing by the touch algorithm unit of the processing engine unit, the touch point value of the touch signal acting on the sensor is obtained;

[0022] S5, the pressure-sensitive algorithm unit of the processing engine unit analyzes the resistance parameters of the input signal and performs pressure-sensitive window sliding filtering to obtain the pressure-sensitive force value;

[0023] S6, by comparing the touch point value or pressure sensitivity value with the set reference threshold through the calculation and comparison unit, it is determined whether the button touch is effective.

[0024] The present invention has the following beneficial effects:

[0025] This invention combines the advantages of pressure-sensitive and capacitive touch, overcoming the problems of using pressure-sensitive or capacitive touch alone. It realizes the functions of pressure-sensitive and touch, which were originally required to acquire two independent sensor signals with different structures through two different digital interfaces in a time-division manner. It can effectively solve the application drawbacks of serial processing of single pressure-sensitive signals or single capacitive touch signals, and realize the concurrent processing of the two signals, thereby improving the real-time performance and accuracy of the overall system signal processing. Attached Figure Description

[0026] Figure 1 is a schematic diagram of the existing technical solutions in this technical field;

[0027] Figure 2 is a schematic diagram of a system that simultaneously processes pressure-sensitive and capacitive touch signals;

[0028] Figure 3 is an internal circuit diagram of the sensor of the present invention;

[0029] Figure 4 is a schematic diagram of the method for simultaneously processing pressure-sensitive and capacitive touch signals. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the present invention without creative effort are within the scope of protection of the present invention.

[0031] Referring to Figure 1, the present invention provides an optional embodiment to illustrate the current method for processing pressure-sensitive and capacitive touch signals. Currently, low power consumption, low cost, and high integration are development directions for low-power SOC chip design. At present, end users design such chips by using an MCU to interface with the pressure sensor and the capacitive touch PAD respectively, and using software solutions to collect different signals in a time-division manner for processing. For example, the pressure sensor signal is first collected by an ADC module to obtain the raw pressure signal, and then a baseline tracking is performed by a pressure-sensitive algorithm. The presence of a press is determined by comparing the magnitude of the real-time signal and the baseline signal to see if they exceed a specific threshold.

[0032] After processing the pressure-sensitive signal, the signal of the capacitive PAD is analyzed through the capacitive touch interface to obtain the changes in the capacitive signal. If someone touches it, the signal can be obtained.

[0033] Therefore, software involvement is required throughout the entire process of processing pressure-sensitive and capacitive touch signals. The CPU is woken up every 100 milliseconds to process a task. The drawback of this approach is that the CPU's serial processing time is too long, resulting in poor real-time performance. The accuracy also varies depending on the software algorithm. Although some algorithms can reduce the serial processing time by increasing the CPU's operating frequency, the reduction is limited and it also increases the overall power consumption of the solution. Furthermore, two different types of sensors, a pressure sensor and a touch sensor, need to be connected externally. These two different signals are then processed serially by time-division multiplexing through the MCU's ADC module and touch processing module, respectively, in order to finally achieve pressure and touch detection.

[0034] Referring to Figure 2, in order to overcome the shortcomings of the above-mentioned solution, the present invention provides another optional implementation scheme, a system for simultaneously processing pressure-sensitive and capacitive touch signals, which optimizes CPU processing time and changes the serial processing of pressure-sensitive signals and capacitive touch signals to parallel processing by the SOC, thereby improving detection efficiency and accuracy.

[0035] The system includes: a sensor, a SOC (System-on-a-Chip) pressure-sensitive signal processing engine unit, an SOC pressure-sensitive channel, an SOC capacitive touch controller, a data bus, and a processor;

[0036] The sensor has a bridge resistor network composed of resistors R1, R2, R3 and R4. Resistors R1 and R2 in the bridge resistor network are coupled in parallel to a precision capacitor C1, and resistors R3 and R4 are coupled in parallel to a precision capacitor C2. One end Vp1 of precision capacitor C1 and one end Vn1 of precision capacitor C2 are coupled to the SOC pressure-sensitive channel, and the other end Vp1_r of precision capacitor C1 and the other end Vn1_r of precision capacitor C2 are coupled to the SOC capacitive touch controller.

[0037] The SOC pressure-sensitive signal processing engine unit includes: a resistance-capacitance separation unit, a touch algorithm unit, a pressure-sensitive algorithm unit, and a calculation and comparison unit; the resistance-capacitance separation unit is used to separate the resistance parameters and capacitance parameters of the sensor's input signal;

[0038] Preferably, the touch algorithm unit is used to perform filtering and baseline tracking algorithm processing on the capacitance parameters to obtain the touch point value;

[0039] Preferably, the pressure-sensitive algorithm unit is used to perform pressure-sensitive window sliding filtering on the resistance parameters to obtain the pressure-sensitive force value;

[0040] Preferably, the calculation and comparison unit compares the touch point value, the pressure sensitivity value, and a set reference threshold to determine whether the button is valid.

[0041] The pressure-sensitive signal processing engine unit, the SOC pressure-sensitive channel, and the SOC capacitive touch controller are all designed on the same SOC. The SOC is coupled to the processor via a data bus, and the data from the SOC is transmitted to the processor for processing via the data bus. The processor can be an ARM series Cortex processor or other processors, such as a microcontroller or FPGA, which can receive and process data from the SOC.

[0042] Referring to Figure 3, the present invention also provides another embodiment, illustrating the process of the system simultaneously processing pressure-sensitive and capacitive touch signals; the resistance values ​​of R1, R2, R3, and R4 on the sensor are between 2 and 10K ohms, and the capacitance values ​​of precision capacitors C1 and C2 are between 20pF and 50pF, so the differential voltage value (between Vp1 and Vn1) presented by the entire sensor is within ±400mV, i.e., the bias voltage value;

[0043] For the pressure-sensitive parameter signal of the sensor, the ADC inside the SOC in this embodiment can perform bias voltage compensation calibration, automatically adjusting the range of the differential voltage value presented by the sensor to within the working range of the ADC, i.e., within ±100mV. The data collected by the ADC will enter the pressure-sensitive algorithm unit, which will perform pressure-sensitive window sliding filtering and dynamic temperature compensation processing, and perform baseline automatic tracking. The signal after processing by the pressure-sensitive algorithm unit of the SOC is a force signal, which is a value of the pressure intensity obtained by algorithm processing the difference between the real-time data and the baseline data, i.e., the pressure intensity value. The entire intensity value ranges from 2 N to 10 N.

[0044] Regarding the capacitance parameter signal of the sensor, when a finger touches the sensor, the touch algorithm unit detects the change in external capacitance. The chip internally generates an oscillation clock f_osc with a frequency of about 2MHz based on this capacitance change. Using a reference clock f_ref (16MHz) with a fixed frequency within the chip, the cycle count (Nx) of f_ref is measured over M f_osc cycles. When there is external touch, f_osc slows down, and the cycle count of f_ref becomes Ny. When (Ny-Nx) is greater than the set reference threshold, a touch event is considered to have occurred, thereby triggering a SOC system interrupt and notifying the processor to perform corresponding processing. Therefore, by simultaneously detecting capacitive touch interrupts and pressure-sensitive press interrupts, the accuracy of effective presses can be improved, false judgments can be reduced, and detection can be made more accurate.

[0045] Referring to Figure 4, the present invention provides another optional embodiment, a method for simultaneously processing pressure-sensitive and capacitive touch signals to improve the processing efficiency of the system, the steps of which are as follows:

[0046] S1. Design a sensor with both capacitive and resistive characteristics. The specific steps are as follows: Based on the bridge resistor network composed of resistors R1, R2, R3 and R4, connect precision capacitors C1 and C2 in parallel. Couple one end Vp1 of precision capacitor C1 and one end Vn1 of precision capacitor C2 to the pressure sensing channel of the SOC chip. Couple the other end Vp1_r of precision capacitor C1 and the other end Vn1_r of precision capacitor C2 to the capacitive touch controller of the SOC chip. In this way, a sensor with both capacitive and resistive characteristics is designed.

[0047] S2, the sensors are used together as signal inputs for pressure sensing and touch control;

[0048] S3 separates the capacitance and resistance parameters of the sensor input signal through the SOC pressure-touch signal processing engine unit;

[0049] S4, by analyzing the capacitance parameters of the input signal and performing filtering and baseline tracking algorithm processing by the touch algorithm unit of the processing engine unit, the touch point value of the touch signal acting on the sensor is obtained;

[0050] S5, the pressure-sensitive algorithm unit of the processing engine unit analyzes the resistance parameters of the input signal and performs pressure-sensitive window sliding filtering to obtain the pressure-sensitive force value;

[0051] S6, by comparing the touch point value or pressure sensitivity value with the set reference threshold through the calculation and comparison unit, it is determined whether the button touch is effective;

[0052] A touch event occurs when the touch point value or pressure sensitivity value is greater than the set reference threshold, that is, the touch button is pressed.

[0053] When the touch point value or pressure sensitivity value is less than the set reference threshold, no touch event occurs, meaning the touch button is not pressed.

[0054] This embodiment combines the advantages of pressure-sensitive and capacitive touch, while overcoming the problems of using pressure-sensitive or capacitive touch alone. It realizes the functions of pressure-sensitive and touch, which were originally required to acquire signals from two independent sensor structures with different structures through two different digital interfaces in a time-division manner.

[0055] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for simultaneously processing pressure-sensitive and capacitive touch signals, comprising: The system comprises a sensor, an ADC module, a touch processing module, a data bus, and a processor. The ADC module and the touch processing module are coupled to the processor via the data bus, and data is transmitted to the processor for processing via the data bus. Its key feature is the parallel processing of pressure-sensitive signals and capacitive touch signals. The sensor includes a bridge resistor network, a precision capacitor C1, and a precision capacitor C2. The bridge resistor network consists of resistors R1, R2, R3, and R4. Resistors R1 and R2 are connected in parallel with the precision capacitor C1, and resistors R3 and R4... A precision capacitor C2 is connected in parallel between the two. The system also includes a SOC pressure-sensitive signal processing engine unit. The SOC pressure-sensitive signal processing engine unit includes a resistance-capacitance separation unit, a touch algorithm unit, a pressure-sensitive algorithm unit, and a calculation and comparison unit. The resistance-capacitance separation unit is used to separate the resistance and capacitance parameters of the sensor's input signal. The touch algorithm unit is used to process the capacitance parameters to obtain the touch point value. The pressure-sensitive algorithm unit is used to process the resistance parameters to obtain the pressure sensitivity value. The calculation and comparison unit is used to compare the touch point value and the pressure sensitivity value with a set reference threshold.

2. The system for simultaneously processing pressure-sensitive and capacitive touch signals according to claim 1, characterized in that: The system also includes a SOC pressure-sensitive channel, wherein one end Vp1 of the precision capacitor C1 and one end Vn1 of the precision capacitor C2 are coupled to the SOC pressure-sensitive channel.

3. The system for simultaneously processing pressure-sensitive and capacitive touch signals according to claim 1, characterized in that: The system also includes a SOC capacitive touch controller, wherein the other end of the precision capacitor C1, Vp1_r, and the other end of the precision capacitor C2, Vn1_r, are coupled to the SOC capacitive touch controller.

4. A method for simultaneously processing pressure-sensitive and capacitive touch signals based on the system described in any one of claims 1-3, characterized in that: To improve system processing efficiency, the steps include: designing a sensor with both capacitive and resistive characteristics, including: connecting precision capacitors C1 and C2 in parallel to a bridge resistor network composed of resistors R1, R2, R3, and R4; coupling one end Vp1 of precision capacitor C1 and one end Vn1 of precision capacitor C2 to the pressure-sensitive channel of the SOC chip; coupling the other end Vp1_r of precision capacitor C1 and the other end Vn1_r of precision capacitor C2 to the capacitive touch controller of the SOC chip; using the sensors together as the signal input for pressure sensing and touch control; and processing the signal through the SOC pressure-touch signal processing engine. The capacitor-resistance separation unit of the component separates the capacitance and resistance parameters of the sensor input signal; the touch algorithm unit of the SOC pressure-touch signal processing engine analyzes the capacitance parameters of the input signal and performs filtering and baseline tracking algorithms to obtain the touch point value of the touch signal applied to the sensor; the pressure-sensitive algorithm unit of the SOC pressure-touch signal processing engine analyzes the resistance parameters of the input signal and performs pressure-sensitive window sliding filtering to obtain the pressure-sensitive force value; the calculation and comparison unit compares the touch point value or pressure-sensitive force value with a set reference threshold to determine whether the button touch is effective.

5. The method for simultaneously processing pressure-sensitive and capacitive touch signals according to claim 4, characterized in that: A touch event occurs when the touch point value or pressure sensitivity value is greater than the set reference threshold.

6. The method for simultaneously processing pressure-sensitive and capacitive touch signals according to claim 4, characterized in that: No touch event occurs when the touch point value or pressure sensitivity value is less than the set reference threshold.

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