Detection loop and capacitive sensor

Abstract

The embodiment of the invention provides a detection loop and a capacitive sensor, and the detection loop comprises a reference circuit which is connected with a reference capacitor; a micro control unit (MCU) (micro controller unit (MCU)); and the bias circuit is connected with the reference circuit and the MCU, and the bias voltage of the bias circuit is determined by the MCU according to the first signal value, so that the deviation generated in the batch production process of the capacitive sensor can be accurately compensated, and the production efficiency of the capacitive sensor is improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of capacitance sensing, and in particular, to a detection circuit and a capacitive sensor. Background Art

[0002] A capacitive sensor is a conversion device with various types of capacitors as sensing elements. It captures and converts the capacitance generated by an object on the copper foil of the A surface of the detection electrode plate into an electrical signal. In fact, it is a capacitor with variable parameters. Capacitive sensors are widely used in the measurement of displacement, angle, vibration, speed, pressure, component analysis, medium characteristics, etc.

[0003] In some industrial scenarios, it is necessary to mass-produce capacitive sensors. During the mass production process of capacitive sensors, due to the dimensional deviations of different components, the detection accuracy of capacitive sensors may be reduced, resulting in low production efficiency of capacitive sensors. In the prior art, generally, an external voltage regulation (VR) technology is adopted to manually adjust the deviations generated during the production process of capacitive sensors by independently adjusting the output voltage.

[0004] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solutions of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art merely because these solutions are described in the background art part of the present application. Summary of the Invention

[0005] The inventors of the present application found that: due to possible deviations in the head assembly of capacitive sensors, there will be errors in the detection voltage and / or reference voltage of different capacitive sensor products. It is necessary to charge and discharge the detection circuit and the reference circuit and then perform differential processing to obtain the final voltage signal value. In the prior art, a bias voltage is generated by the VR technology to adjust the reference voltage to eliminate the assembly error of the capacitive sensor. However, in the actual production process, it is necessary to manually adjust the VR in real time, resulting in a slow voltage adjustment speed. Moreover, manually adjusting the voltage cannot guarantee the adjustment accuracy of the voltage, resulting in the inability to effectively eliminate the error of the capacitive sensor and the inability to improve the production efficiency of the capacitive sensor.

[0006] To address at least one of the above technical problems or at least similar problems, an embodiment of the present application provides a detection circuit and a capacitive sensor. By providing a bias circuit that connects a reference circuit and a microcontroller unit (MCU) in the detection circuit of the original capacitive sensor to form an additional bias voltage, it is possible to accurately compensate for the deviation generated during the mass production of the capacitive sensor and improve the production efficiency of the capacitive sensor.

[0007] According to an embodiment of the first aspect of the present application, a detection circuit is provided. The detection circuit includes:

[0008] A reference circuit connected to a reference capacitor;

[0009] A microcontroller unit (MCU);

[0010] A bias circuit that connects the reference circuit and the MCU, and the bias voltage of the bias circuit is determined by the MCU according to a first signal value.

[0011] In some embodiments, the detection circuit further includes:

[0012] A detection circuit connected to a detection capacitor;

[0013] A differential amplifier circuit. The detection circuit inputs a detection signal to the differential amplifier circuit, the reference circuit inputs a reference signal to the differential amplifier circuit, and the differential amplifier circuit differentially amplifies the detection signal, the reference signal, and the bias voltage and then outputs the first signal.

[0014] In some embodiments, the first signal is input to the MCU after analog-to-digital conversion (AD).

[0015] In some embodiments, the bias voltage is input to the bias circuit by the MCU through a digital-to-analog converter (DAC).

[0016] In some embodiments, when the first signal value is less than or equal to a first voltage, the bias voltage increases;

[0017] When the first signal value is greater than or equal to a second voltage, the bias voltage decreases.

[0018] In some embodiments, the bias voltage increases or decreases so that the first signal value is always greater than the first voltage and less than the second voltage.

[0019] In some embodiments, the first voltage and the second voltage are determined by the MCU according to the accuracy of the digital-to-analog converter (DAC) of the MCU and the detection deviation of the detection circuit.

[0020] According to an embodiment of the second aspect of the present application, there is also provided a capacitive sensor having the detection circuit described in any of the previous embodiments.

[0021] One of the beneficial effects of the embodiments of the present application is that by providing a bias circuit connecting a reference circuit and a microcontroller unit (MCU) in the detection circuit of the original capacitive sensor to form an additional bias voltage, thereby, the deviation generated during the mass production of the capacitive sensor can be accurately compensated, the production efficiency of the capacitive sensor can be improved, and the structure is simple and easy to implement.

[0022] Referring to the following description and the accompanying drawings, specific embodiments of the embodiments of the present application are disclosed in detail, indicating the ways in which the principles of the embodiments of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope thereby. Within the spirit and terms of the appended claims, the embodiments of the present application include many changes, modifications, and equivalents. Description of the Drawings

[0023] The accompanying drawings included are used to provide a further understanding of the embodiments of the present application, which form a part of the specification, are used to illustrate the embodiments of the present application, and together with the written description are used to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and those of ordinary skill in the art can obtain other embodiments based on these drawings without creative efforts. In the drawings:

[0024] Figure 1 is a schematic diagram of the detection circuit of the embodiment of the present application;

[0025] Figure 2 is a flowchart of the operation of the detection circuit of the embodiment of the present application;

[0026] Figure 3 is a schematic diagram of some effects of the embodiment of the present application. Detailed Embodiments

[0027] Referring to the accompanying drawings, the foregoing and other features of the embodiments of the present application will become apparent through the following description. In the description and drawings, specific embodiments of the present application are specifically disclosed, which show some embodiments in which the principles of the embodiments of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the embodiments of the present application include all modifications, variations, and equivalents falling within the scope of the appended claims.

[0028] In the embodiments of the present application, terms such as "first" and "second" are used to distinguish different elements in terms of name, but do not indicate the spatial arrangement or time sequence of these elements, and these elements should not be limited by these terms. The term "and / or" includes any one and all combinations of one or more of the associated listed terms. Terms such as "comprising", "including", "having", etc. mean the presence of the stated features, elements, components, or assemblies, but do not exclude the presence or addition of one or more other features, elements, components, or assemblies.

[0029] In the embodiments of the present application, the singular forms "a", "the", etc. include the plural forms and should be broadly understood as "a kind of" or "a class of" rather than being limited to the meaning of "one"; in addition, the term "the" should be understood to include both the singular form and the plural form unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least partially according to...", and the term "based on" should be understood as "at least partially based on...", unless the context clearly indicates otherwise.

[0030] Features described and / or illustrated for one embodiment can be used in the same or similar manner in one or more other embodiments, combined with the features in other embodiments, or replace the features in other embodiments. The term "including / comprising" as used herein means the presence of features, whole things, steps, or components, but does not exclude the presence or addition of one or more other features, whole things, steps, or components.

[0031] The embodiments of the present application provide a detection circuit for compensating for the deviation generated during the mass production of capacitive sensors.

[0032] Figure 1 is a schematic diagram of the detection circuit of the embodiments of the present application.

[0033] As Figure 1 shown, the detection circuit 100 includes:

[0034] A reference circuit 101, and a reference capacitor 102 is connected to the reference circuit 101;

[0035] A microcontroller unit (MCU) 103;

[0036] The bias circuit 104 is connected to the reference capacitor 102 and the microcontroller unit 103, and the bias voltage of the bias circuit 104 is determined by the microcontroller unit 103 according to the first signal value.

[0037] According to the above embodiments, by providing a bias circuit connecting a reference circuit and a microcontroller unit (MCU) in the detection loop of the original capacitive sensor to form an additional bias voltage, it is possible to accurately compensate for the deviation generated during the mass production of the capacitive sensor, improve the production efficiency of the capacitive sensor, and has a simple structure and is easy to implement.

[0038] In some embodiments, as Figure 1 shown, the detection loop 100 further includes:

[0039] A detection circuit 107, which is connected to a detection capacitor 106;

[0040] A differential amplifier circuit 105, the detection circuit 107 inputs a detection signal to the differential amplifier circuit 105, the reference circuit 101 inputs a reference signal to the differential amplifier circuit 105, and the differential amplifier circuit 105 differentially amplifies the detection signal, the reference signal, and the bias voltage and then outputs a first signal.

[0041] Taking Figure 1 as an example, when a detected object is detected, the capacitance value of the detection capacitor 106 changes and a detection signal is generated. The detection circuit 107 inputs the detection signal to the differential amplifier circuit 105, that is, the detection capacitor 106 generates a detection voltage and inputs it to the differential amplifier circuit 105; the reference capacitor 102 continuously generates a stable reference signal, and the reference circuit 101 inputs the reference signal to the differential amplifier circuit 105, that is, the reference capacitor 102 generates a reference voltage and inputs it to the differential amplifier circuit 105; the bias voltage is generated by the microcontroller unit 103 and the reference signal is input to the differential amplifier circuit 105 through the detection loop 104.

[0042] In some embodiments, the bias voltage is input to the bias circuit 104 by the microcontroller unit 103 through a digital-to-analog converter (DAC).

[0043] That is, the microcontroller unit 103 outputs a digital signal corresponding to the bias voltage, and this digital signal is converted into an analog signal through the digital-to-analog converter, and this analog signal is input to the bias circuit 104, that is, a bias voltage is formed.

[0044] In the above embodiments, as Figure 1As shown, the detection signal is input to the negative electrode (inverting input terminal) of the differential amplifier circuit 105, and the reference signal and the bias voltage are input to the positive electrode (non-inverting input terminal) of the differential amplifier circuit 105. That is, the differential amplifier circuit 105 performs the following calculation on the above signals:

[0045] V c = V 参 + ΔV - V 探

[0046] where, V c represents the first signal output by the differential amplifier circuit 105, V 参 represents the reference signal (i.e., reference voltage), ΔV represents the bias voltage, and V 探 represents the detection signal (i.e., detection voltage). It can be seen that, as Figure 1 shown, the microcontroller unit 103 uses the bias voltage ΔV to adjust the reference voltage V 参 . After the adjusted reference voltage and the detection voltage are subjected to the above calculation and differential amplification by the differential amplifier circuit 105, the first signal is output.

[0047] In some embodiments, the first signal is input to the microcontroller unit 103 after passing through an analog-to-digital converter (ADC).

[0048] That is, the differential amplifier circuit 105 obtains the first signal after differential amplification of the reference voltage, the detection voltage, and the bias voltage. The first signal passes through an analog-to-digital converter. That is, the analog-to-digital converter samples the first signal and converts it into a first signal value, and this first signal value is input to the microcontroller unit 103.

[0049] In the above embodiment, the microcontroller unit 103 further determines the bias voltage of the bias circuit 104 according to the first signal value. That is to say, the microcontroller unit 103 generates a digital signal, and forms a bias voltage through a digital-to-analog converter and inputs it to the bias circuit. This bias voltage adjusts the reference voltage. After the adjusted reference voltage and the detection voltage are processed by the differential amplifier circuit, the first signal is obtained. The microcontroller unit 103 adjusts the output bias voltage according to the first signal value obtained after analog-to-digital conversion of the first signal. Thus, the microcontroller unit 103 can form a bias voltage to adjust the reference voltage, and further adjust the bias voltage directly according to the first signal obtained after adjustment until the deviation is compensated.

[0050] Hereinafter, the adjustment of the bias voltage by the microcontroller unit 103 in the embodiments of the present application will be described.

[0051] In some embodiments, when the first signal value is less than or equal to the first voltage, the bias voltage increases; when the first signal value is greater than or equal to the second voltage, the bias voltage decreases.

[0052] For example, when the first signal is less than or equal to the first voltage, the microcontroller unit 103 controls the bias voltage to increase, that is, by increasing the bias voltage, the reference voltage becomes larger, thereby increasing the first signal output by the differential amplifier circuit 105; when the first signal is greater than or equal to the second voltage, the microcontroller unit 103 controls the bias voltage to decrease, that is, by decreasing the bias voltage, the reference voltage decreases, thereby decreasing the first signal output by the differential amplifier circuit 105.

[0053] In some embodiments, the bias voltage increases or decreases so that the first signal value is always greater than the first voltage and less than the second voltage.

[0054] That is, the microcontroller unit 103 controls the bias voltage according to the first signal value so that the first signal value is always within a preset voltage range. Thus, the accuracy of the capacitive sensor can be guaranteed.

[0055] In some embodiments, the first voltage and the second voltage are determined by the microcontroller unit 103 according to the accuracy of the digital-to-analog converter (DAC) of the microcontroller unit 103 and the detection deviation of the detection circuit.

[0056] Thus, while adjusting the deviation generated in the production of the capacitive sensor, the errors that may be generated by the detection circuit itself and the digital-to-analog converter itself are further considered, avoiding the situation where the first signal cannot be adjusted to the preset voltage range due to the errors of the detection circuit and the digital-to-analog converter itself, and avoiding the adjustment time of the microcontroller unit 103 from being too long, thereby further improving the work efficiency.

[0057] In some examples, the smaller the voltage range formed by the first voltage and the second voltage, the more accurate the adjusted capacitive sensor. The values of the first voltage and the second voltage can be set according to specific requirements. This application is not limited thereto. The adjustment of the first voltage and the second voltage can also consider other components in the detection circuit. For example, it can be set according to the deviation generated by the analog-to-digital converter or according to the requirements of different capacitive sensors. This application does not make any restrictions.

[0058] Hereinafter, the working process of the detection circuit of the embodiments of the present application will be described.

[0059] Figure 2 is a working flowchart of the detection circuit of the embodiments of the present application.

[0060] As Figure 2As shown, the detection circuit enters the factory mode. Here, the factory mode means that before the capacitive sensor is officially put into use, the micro control unit 103 outputs a bias voltage to adjust the deviation generated during the production process of the capacitive sensor. At this time, the detection circuit adjusts the bias voltage under a fixed scenario. For example, there is a standard detection object at a detection distance of 8 millimeters in the detection circuit, and the capacitive sensor is adjusted under this condition. Correspondingly, exiting the factory mode means that the bias voltage setting is completed, and the deviation generated during the production process of this capacitive sensor has been eliminated and it can be put into use.

[0061] In some examples, such as Figure 2 As shown, after the detection circuit enters the factory mode, a first signal value is obtained according to the first signal output by the differential amplification circuit 105. When the first signal value is greater than or equal to V2 (the second voltage), the micro control unit 103 controls the bias voltage to decrease until the first signal value is less than the second voltage. At this time, it is further determined whether the first signal value is greater than V1 (the first voltage). When the first signal value is less than or equal to the first voltage, the micro control unit 103 controls the bias voltage to increase until the first signal value is greater than the first voltage. At this time, the first signal value is within the voltage range between the preset first voltage and the second voltage, and this bias voltage can eliminate the deviation generated during the production process of this capacitive sensor. After exiting the factory mode, the value of this bias voltage can be stored in this capacitive sensor and used for subsequent use of the capacitive sensor.

[0062] The above examples illustrate some embodiments of the present application. Figure 3 It is a schematic diagram of some effects of the embodiments of the present application, showing the situation of using the detection circuit of the embodiments of the present application in different capacitive sensor products.

[0063] Such as Figure 3 As shown, where the white bars represent the first signal values output by the differential amplification circuit after different capacitive sensor products adjust the reference voltage using the existing method (for example, VR), and the gray bars + white bars represent the first signal values output by the differential amplification circuit after different capacitive sensor products adjust the reference voltage using the detection circuit of the embodiments of the present application. It can be seen that Figure 3 through the adjustment of the detection circuit of the embodiments of the present application, the deviation between the first signal values output by the differential amplification circuits 105 of different products has been significantly reduced.

[0064] In addition, in some embodiments, since the main frequency of the micro control unit 103 is 32 MHz, its operating efficiency is higher than the efficiency of adjusting the bias voltage using VR, and, in the micro control unit 103, ADC sampling is used to process the first signal, and DAC is used for processing when outputting the bias voltage. Therefore, the accuracy of the bias voltage output by the micro control unit 103 is much higher than the accuracy of adjustment using VR or other existing technologies.

[0065] In addition, in the above embodiment, the digital-to-analog converter and the analog-to-digital converter can be arranged inside the microcontroller unit 103, but the present application is not limited thereto. The digital-to-analog converter and the analog-to-digital converter can also be arranged outside the microcontroller unit 103, so that the first signal can be input to the microcontroller unit 103 through analog-to-digital conversion and the output of the microcontroller unit 103 can be converted into a bias voltage through digital-to-analog conversion and output to the bias circuit 104.

[0066] It should be noted that the above embodiments are only described using capacitive sensors as an example, but the present application is not limited to this. The detection circuit in the embodiments of the present application can also be used to adjust the accuracy of other products, such as other capacitive products or other sensor products, and the present application is not limited thereto.

[0067] It is worth noting that the above only describes the components or modules related to the present application, but the present application is not limited thereto. The above device may also include other components or modules, and the specific contents of these components or modules may refer to the relevant technology.

[0068] To keep it simple, Figure 1 The connection relationship or signal direction between various components or modules is only exemplified, but it should be clear to those skilled in the art that various related technologies such as bus connection can be used. The above-mentioned components or modules can be implemented by hardware facilities such as processors and memories; the embodiments of the present application are not limited to this.

[0069] The present application also provides a capacitive sensor, which includes the detection circuit described in the above embodiment. Since the structure of the detection circuit has been described in the above embodiment, its content is incorporated here and will not be repeated here. In addition, the capacitive sensor also includes other components and functions, which can be specifically referred to in the relevant technology and will not be repeated here.

[0070] The above embodiments are merely exemplary of the embodiments of the present application, but the present application is not limited thereto, and appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

[0071] The method / apparatus described in combination with the embodiments of the present application can be directly embodied as hardware, a software module executed by a processor, or a combination of both. For example, one or more of the functional block diagrams shown in the figure and / or a combination of one or more of the functional block diagrams can correspond to each software module of the computer program flow, and can also correspond to each hardware module. These software modules can respectively correspond to the respective steps shown in the figure. These hardware modules can be implemented by solidifying these software modules using a field-programmable gate array (FPGA).

[0072] The software module can be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. A storage medium can be coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium; or the storage medium can be a component of the processor. The processor and the storage medium can be located in an ASIC. The software module can be stored in the memory of the mobile terminal or in a memory card insertable into the mobile terminal. For example, if the device (such as a mobile terminal) uses a larger-capacity MEGA-SIM card or a large-capacity flash device, the software module can be stored in the MEGA-SIM card or the large-capacity flash device.

[0073] One or more of the functional block diagrams described in the accompanying drawings and / or a combination of one or more of the functional block diagrams can be implemented as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any suitable combination thereof for performing the functions described in the present application. One or more of the functional block diagrams described in the accompanying drawings and / or a combination of one or more of the functional block diagrams can also be implemented as a combination of computing devices. For example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in communication combination with a DSP, or any other such configuration.

[0074] The present application has been described in combination with specific embodiments, but those skilled in the art should understand that these descriptions are exemplary and not a limitation on the protection scope of the present application. Those skilled in the art can make various variations and modifications to the present application according to the principles of the present application, and these variations and modifications are also within the scope of the present application.

Claims

1. A detection circuit, characterized in that: The detection circuit comprises: A reference circuit, wherein the reference circuit is connected to a reference capacitor; A micro control unit, wherein the micro control unit controls the detection circuit; A bias circuit is connected to the reference circuit and the micro control unit, and a bias voltage of the bias circuit is determined by the micro control unit according to a first signal value.

2. The detection circuit according to claim 1, wherein: The detection circuit also includes: A detection circuit, wherein the detection circuit is connected to a detection capacitor; A differential amplifier circuit, wherein the detection circuit inputs a detection signal to the differential amplifier circuit, the reference circuit inputs a reference signal to the differential amplifier circuit, and the differential amplifier circuit differentially amplifies the detection signal, the reference signal and the bias voltage and then outputs the first signal.

3. The detection circuit according to claim 2, wherein: The first signal is input into the micro control unit after analog-to-digital conversion.

4. The detection circuit according to claim 1, wherein: The bias voltage is input to the bias circuit after being converted from digital to analog by the micro control unit.

5. The detection circuit according to claim 1, wherein: When the first signal value is less than or equal to the first voltage, the bias voltage increases; When the first signal value is greater than or equal to a second voltage, the bias voltage decreases.

6. The detection circuit according to claim 5, wherein: The bias voltage increases or decreases so that the first signal value is always greater than the first voltage and less than the second voltage.

7. The detection circuit according to claim 6, wherein: The first voltage and the second voltage are determined by the micro control unit according to the accuracy of a digital-to-analog converter of the micro control unit and the detection deviation of the detection circuit.

8. A capacitive sensor, wherein: The capacitive sensor comprises the detection circuit according to any one of claims 1 to 7.

Images