AD conversion circuit and tension detection control system

Abstract

The invention provides an AD conversion circuit and a tension detection control system. The AD conversion circuit comprises an AD conversion chip U6, a first differential voltage circuit and a second differential voltage circuit, the INN end and the INP end of the AD conversion chip U6 are connected to the negative electrode output end and the positive electrode output end of the tension sensor respectively. The first differential voltage circuit comprises a first three-terminal capacitor; the second differential voltage circuit comprises a second three-terminal capacitor; and the AD conversion chip U6 converts the negative differential voltage filtering signal and the positive differential voltage filtering signal into a negative differential voltage digital signal and a positive differential voltage digital signal respectively and transmits the negative differential voltage digital signal and the positive differential voltage digital signal to the control circuit, so that the control circuit compares the negative differential voltage digital signal with the positive differential voltage digital signal to obtain tension data. According to the invention, the accuracy of the negative differential voltage digital signal and the positive differential voltage digital signal acquired and converted by the tension sensor is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of tension sensors, and in particular to an AD conversion circuit and a tension detection control system. Background Art

[0002] A tension sensor is a sensor used to measure the force applied to an object. It is widely used in packaging, textiles, printing, aerospace and other fields. Taking the textile industry as an example, tension sensors are used to measure the tension of yarns to ensure the uniformity and quality of the yarns. The tension sensor can specifically measure the forces applied to an object in two directions, namely tension and pressure.

[0003] In the textile, weaving and printing and dyeing processes, tension sensors are used to measure the tension of yarns to ensure the quality and production efficiency of yarns. By real-time monitoring and controlling the tension of yarns, the quality and production efficiency of textiles can be improved. Therefore, how to ensure the accuracy of the tension measured by the tension sensor is particularly important. Since the original force signal is a differential voltage signal, it is impossible to directly measure and apply the data, so the differential voltage signal needs to be converted. In the existing tension detection system, during the acquisition of differential voltage signals, due to the influence of noise signals, and the noise signals include the noise generated by the power supply and the power supply voltage of the tension sensor, which will also generate certain noise, and thus the final acquired differential voltage signal will also have noise interference, resulting in a large error problem.

[0004] In view of this, it is necessary to improve the tension detection system in the prior art to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that in the differential voltage signal acquisition process of the existing tension detection system, due to the influence of the clutter signal, the final acquired differential voltage signal has a large error.

[0006] To achieve the above object, the present invention provides an AD conversion circuit connected between a tension sensor and a control circuit, the AD conversion circuit comprising: an AD conversion chip U6 and a first differential voltage circuit and a second differential voltage circuit connected in parallel to the INN terminal and the INP terminal of the AD conversion chip U6;

[0007] The INN terminal and the INP terminal of the AD conversion chip U6 are respectively connected to the negative output terminal and the positive output terminal of the tension sensor, for receiving the negative differential voltage signal and the positive differential voltage signal respectively;

[0008] The first differential voltage circuit includes: a first three-terminal capacitor connected between the INN terminal of the AD conversion chip U6 and the negative output terminal of the tension sensor, used for filtering the negative differential voltage signal to form a negative differential voltage filter signal;

[0009] The second differential voltage circuit includes: a second three-terminal capacitor connected between the INP terminal of the AD conversion chip U6 and the positive output terminal of the tension sensor, used for filtering the positive differential voltage signal to form a positive differential voltage filter signal;

[0010] The ground terminal of the first three-terminal capacitor and the ground terminal of the second three-terminal capacitor are connected to a reference ground, the first three-terminal capacitor is configured to connect a first signal input terminal of the negative output terminal and a first signal output terminal of the INN terminal, and the second three-terminal capacitor is configured to connect a second signal input terminal of the positive output terminal and a second signal output terminal of the INP terminal;

[0011] The AD conversion chip U6 converts the negative differential voltage filter signal and the positive differential voltage filter signal into a negative differential voltage digital signal and a positive differential voltage digital signal respectively and transmits them to the control circuit, so that the control circuit compares the negative differential voltage digital signal with the positive differential voltage digital signal to obtain tension data.

[0012] As a further improvement of the present invention,

[0013] The first differential voltage circuit further includes: a first resistor connected between the first signal input terminal of the first three-terminal capacitor and the negative output terminal of the tension sensor, and a second resistor connected between the first signal output terminal of the first three-terminal capacitor and the INN terminal of the AD conversion chip U6;

[0014] The second differential voltage circuit also includes: a third resistor connected between the second signal input terminal of the second three-terminal capacitor and the positive output terminal of the tension sensor, and a fourth resistor connected between the second signal output terminal of the second three-terminal capacitor and the INP terminal of the buck converter chip U6.

[0015] As a further improvement of the present invention, the AD conversion circuit further includes: a first filtering circuit, the first filtering circuit is composed of a first capacitor, a second capacitor and a third capacitor connected in parallel to the INN terminal and the INP terminal of the buck conversion chip U6;

[0016] One end of the first capacitor is connected between the first signal output end of the first three-terminal capacitor and the second resistor, and the other end is connected to the reference ground. One end of the second capacitor is connected between the second signal output end of the second three-terminal capacitor and the fourth resistor, and the other end is connected to the reference ground.

[0017] Based on the same inventive concept, the present invention also discloses a tension detection control system, comprising:

[0018] A power supply circuit, a control circuit connected to the power supply circuit, an AD conversion circuit arranged in pairs as described in any of the above inventions, and a tension sensor arranged in pairs, and a single AD conversion circuit is connected between a single tension sensor and the control circuit.

[0019] As a further improvement of the present invention, the power supply circuit comprises: a first voltage conversion circuit and a second voltage conversion circuit connected to the main circuit;

[0020] The main circuit includes: a voltage regulating chip U2, the first voltage conversion circuit includes: a forward low-dropout voltage regulator U1, a third filter circuit connected in parallel to the VIN terminal and the GND terminal of the forward low-dropout voltage regulator U1, and a fourth filter circuit connected in parallel to the VOUT terminal and the GND terminal of the forward low-dropout voltage regulator U1, the second voltage conversion circuit includes: a linear voltage regulator U3, a fifth filter circuit connected in parallel to the VIN terminal and the GND terminal of the linear voltage regulator U3, and a sixth filter circuit connected in parallel to the VOUT terminal and the GND terminal of the linear voltage regulator U3, the VIN terminal of the forward low-dropout voltage regulator U1 and the VIN terminal of the linear voltage regulator U3 are both connected to the SE terminal of the voltage regulating chip U2, for respectively connecting to the main power supply voltage output by the voltage regulating chip U2, and respectively converting the main power supply voltage into a first output voltage (3.3V) and a second output voltage (5.0V);

[0021] The third filtering circuit includes: a seventh polar capacitor and an eighth capacitor, the positive electrode of the seventh polar capacitor and one end of the eighth capacitor are both connected to the VIN end of the forward low-dropout voltage regulator U1, the fourth filtering circuit includes: a ninth polar capacitor and a tenth capacitor, the positive electrode of the ninth polar capacitor and one end of the tenth capacitor are both connected to the VOUT end of the forward low-dropout voltage regulator U1, the negative electrode of the seventh polar capacitor, the other end of the eighth capacitor, the negative electrode of the ninth polar capacitor, the other end of the tenth capacitor and the GND end of the forward low-dropout voltage regulator U1 are commonly connected to the reference ground;

[0022] The fifth filtering circuit includes: an eleventh polar capacitor and a twelfth capacitor, the positive electrode of the eleventh polar capacitor and one end of the twelfth capacitor are both connected to the VIN terminal of the linear regulator U3, the sixth filtering circuit includes: a thirteenth polar capacitor, a fourteenth capacitor and a fifteenth capacitor, the positive electrode of the thirteenth polar capacitor, one end of the fourteenth capacitor and one end of the fifteenth capacitor are all connected to the VOUT terminal of the linear regulator U3, the negative electrode of the eleventh polar capacitor, the other end of the twelfth capacitor, the negative electrode of the thirteenth polar capacitor, the other end of the fourteenth capacitor, the other end of the fifteenth capacitor and the GND terminal of the linear regulator U3 are commonly connected to the reference ground.

[0023] As a further improvement of the present invention, the tension sensor is connected to the power supply circuit through a connector, the first terminal of the connector is isolated from the ground by a first diode, the second terminal of the connector is connected to the VOUT end of the linear regulator U3, the third terminal of the connector is connected to the reference ground, and the fourth terminal and the fifth terminal of the connector are respectively connected to the positive output end and the negative output end of the tension sensor.

[0024] As a further improvement of the present invention, the AVDD terminal of the AD conversion chip U6 is connected to the VOUT terminal of the linear regulator U3, so as to deliver a second output voltage to the AD conversion chip U6; the DVDD terminal of the AD conversion chip U6 is connected to the VOUT terminal of the forward low-dropout regulator U1, so as to deliver a first output voltage to the AD conversion chip U6; and a second filtering circuit is connected in parallel to the AVDD terminal and the DVDD terminal of the AD conversion chip U6, and the second filtering circuit isolates the first output voltage from the second output voltage.

[0025] As a further improvement of the present invention, the control circuit includes: a microcontroller U7, and the PA2 terminal and the PA3 terminal of the microcontroller U7 are respectively connected to the DOUT terminal and the SCK terminal of the AD conversion chip U6.

[0026] As a further improvement of the present invention, the tension detection control system further comprises: an analog output circuit connected to the control circuit, for converting the tension data into analog data and outputting the analog data;

[0027] The analog output circuit includes: a digital-to-analog converter U8, and the digital-to-analog converter U8 is configured to be respectively connected to the SCLK terminal, SDLN terminal, SDO terminal, CLSE terminal, CLEAR terminal and LATCH terminal of the PB13 terminal, PB15 terminal, PB14 terminal, PB3 terminal, PA15 terminal and PB4 terminal of the microcontroller U7.

[0028] As a further improvement of the present invention, the tension detection control system further comprises: a communication circuit connected to the control circuit, for communicating with an external device;

[0029] The communication circuit includes: a communication chip U4, wherein the communication chip U4 is configured to be connected to the RO terminal and the DI terminal of the PA10 terminal and the PA9 terminal of the microcontroller U7 respectively, and the A terminal and the B terminal of the communication chip U4 are connected to an external device.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] In the present invention, the AD conversion circuit is connected between the tension sensor and the control circuit, and the AD conversion circuit includes: an AD conversion chip U6 and a first differential voltage circuit and a second differential voltage circuit connected in parallel to the INN terminal and the INP terminal of the AD conversion chip U6, and the INN terminal and the INP terminal of the AD conversion chip U6 are respectively connected to the negative output terminal and the positive output terminal of the tension sensor, for receiving the negative differential voltage signal and the positive differential voltage signal respectively. The first differential voltage circuit includes: a first three-terminal capacitor connected between the INN terminal of the AD conversion chip U6 and the negative output terminal of the tension sensor, for filtering the negative differential voltage signal to form a negative differential voltage filter signal. The second differential voltage circuit includes: a second three-terminal capacitor connected between the INP terminal of the AD conversion chip U6 and the positive output terminal of the tension sensor, for filtering the positive differential voltage signal to form a positive differential voltage filter signal. The ground terminal of the first three-terminal capacitor and the ground terminal of the second three-terminal capacitor are connected to the reference ground, the first three-terminal capacitor is configured to connect the first signal input terminal of the negative output terminal and the first signal output terminal of the INN terminal, and the second three-terminal capacitor is configured to connect the second signal input terminal of the positive output terminal and the second signal output terminal of the INP terminal. The AD conversion chip U6 converts the negative differential voltage filter signal and the positive differential voltage filter signal into a negative differential voltage digital signal and a positive differential voltage digital signal respectively and transmits them to the control circuit, so that the control circuit compares the negative differential voltage digital signal with the positive differential voltage digital signal to obtain tension data. The three-terminal capacitor has a lower equivalent series inductance, which makes the acquisition circuit more effective in high-frequency applications. Since the inductance increases the impedance at high frequencies, the use of the three-terminal capacitor can effectively reduce the impedance, and effectively filter out the high-frequency noise, improve the accuracy of the negative differential voltage digital signal and the positive differential voltage digital signal collected and converted by the tension sensor, and can effectively reduce the noise of the power supply. Through the low ESL characteristics, it can quickly respond to the high-frequency noise and transient changes on the tension sensor acquisition line, and effectively improve the accuracy of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A topological diagram of the tension detection control system shown in the present invention;

[0033] Figure 2 A schematic circuit diagram of the main circuit;

[0034] Figure 3 is a schematic circuit structure diagram of a first voltage conversion circuit;

[0035] Figure 4 is a schematic circuit structure diagram of a second voltage conversion circuit;

[0036] Figure 5 is a schematic circuit structure diagram of a control circuit;

[0037] Figure 6 is a schematic circuit structure diagram of an AD conversion circuit;

[0038] Figure 7 is a schematic circuit structure diagram of the connector P5;

[0039] Figure 8 It is a schematic circuit structure diagram of the analog output circuit;

[0040] Fig. 9 is a schematic circuit structure diagram of a communication circuit;

[0041] Fig.10 is a schematic circuit structure diagram of the connector P5;

[0042] Fig.11 is a schematic circuit structure diagram of a key circuit;

[0043] Fig.12 It is a schematic circuit structure diagram of a DIP switch circuit;

[0044] Fig.13 The waveform diagram is a waveform diagram corresponding to the difference between the positive differential voltage filter signal and the negative differential voltage filter signal of the existing AD conversion circuit and the AD conversion circuit disclosed in the present invention under the same input signal. DETAILED DESCRIPTION

[0045] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0046] Please refer to Figures 1 to 13As shown, the present invention shows a specific implementation of an AD conversion circuit 30, which is connected between a tension sensor 40 and a control circuit 20, and is used for filtering the negative differential voltage signal and the positive differential voltage signal collected by the tension sensor 40 to obtain a negative differential voltage filter signal and a positive differential voltage filter signal, respectively, and converting the negative differential voltage filter signal and the positive differential voltage filter signal to obtain a negative differential voltage digital signal and a positive differential voltage digital signal, respectively, and transmitting them to the control circuit 20, so that the control circuit 20 compares the negative differential voltage digital signal with the positive differential voltage digital signal to obtain tension data.

[0047] Based on this, the present invention also shows a tension detection control system 100. Specifically, Figure 1 As shown, the tension detection control system 100 includes: a power supply circuit 10, a control circuit 20 connected to the power supply circuit 10, an AD conversion circuit 30 and a tension sensor 40, and the AD conversion circuit 30 is connected between the tension sensor 40 and the control circuit 20, that is, the AD conversion circuit 30 is connected to the tension sensor 40 and the control circuit 20 respectively, so as to filter and convert the negative differential voltage signal and the positive differential voltage signal collected by the tension sensor 40 and transmit them to the control circuit 20, and then the control circuit 20 compares them to obtain the tension data.

[0048] Ginseng Figures 2 to 4 As shown, the power supply circuit 10 includes: a main circuit 11 and a first voltage conversion circuit 12 and a second voltage conversion circuit 13 connected to the main circuit 11. The main circuit 11 includes: a voltage regulating chip U2, the first voltage conversion circuit 12 includes: a forward low-dropout voltage regulator U1, a third filter circuit 121 connected in parallel to the VIN terminal and the GND terminal of the forward low-dropout voltage regulator U1, and a fourth filter circuit 122 connected in parallel to the VOUT terminal and the GND terminal of the forward low-dropout voltage regulator U1, and the second voltage conversion circuit 13 includes: a linear voltage regulator U3, a fifth filter circuit 131 connected in parallel to the VIN terminal and the GND terminal of the linear voltage regulator U3, and a sixth filter circuit 132 connected in parallel to the VOUT terminal and the GND terminal of the linear voltage regulator U3. The VIN terminal of the forward low dropout regulator U1 and the VIN terminal of the linear regulator U3 are both connected to the SE terminal of the voltage regulating chip U2, and are used to respectively access the main power supply voltage output by the voltage regulating chip U2, and convert the main power supply voltage into the first output voltage and the second output voltage through the first voltage conversion circuit 12 and the second voltage conversion circuit 13 respectively.

[0049] It should be noted that the model of the aforementioned voltage regulator chip U2 is MC34063. MC34063 is a voltage regulator chip that can be used as a boost converter, a buck converter, and an inverter. In this embodiment, it is used as a buck converter. In this embodiment, the power supply circuit 20 is powered by a wide voltage of 9-36VDC. After voltage regulation by the voltage regulator chip MC34063, a stable 8V voltage is obtained, that is, the aforementioned main power supply voltage is 8V. The SC end of pin 1, the DC end of pin 8, and the IPK end of pin 7 of the voltage regulator chip U2 are connected, the SE end of pin 2 outputs the main power supply voltage of 8V, the CT end of pin 3 is isolated from the ground through a capacitor C1 with a capacity of 1μF, so as to adjust the operating frequency of MC34063 through capacitor C1, the GND end of pin 4 is connected to the reference ground, the FB end of pin 5 is connected to the reference ground through a resistor R2, and the VCC end of pin 6 is connected to the power supply voltage. A fuse F1 with a rated current of 1.5A and a rated voltage of 30V, a SS14 diode D1 and an inductor L1 are connected in sequence between the power supply voltage and the VCC terminal of pin 6, and the positive electrode of the SS14 diode D1 is connected to the inductor L1, and the negative electrode is connected to the fuse F1. When the current is too large, the fuse F1 will automatically switch the subsequent circuit, and the SS14 diode D1 plays the role of unidirectional current conduction. A diode D2 is connected between the power supply voltage and the fuse F1, and the other end of the diode D2 is connected to the reference ground. A DC power supply input terminal and a capacitor C8 with a size code of 206 and a capacity of 10μF are connected between the fuse F1 and the inductor L1, and the other end of the capacitor C8 is connected to the reference ground. A resistor, a polarized capacitor C4, a capacitor C10 and a capacitor C9 are connected between the inductor L1 and the VCC end of pin 6, respectively. The other end of the resistor R3 is connected to the SC end of pin 1, the DC end of pin 8 and the IPK end of pin 7. The positive electrode of the polarized capacitor C4 is connected between the inductor L1 and the VCC end of pin 6, and the negative electrode is connected to the reference ground. The resistor R3 is a current limiting resistor, and the working current limiting function of the voltage regulating chip MC34063 can be achieved by adjusting the resistance value of the resistor R3. One end of the inductor L4 and the other end of the capacitor C8 are connected to the reference ground together, and the other end of the inductor L4 is connected to one end of the capacitor C13. The other end of the capacitor C13, the other end of the capacitor C9 and the other end of the capacitor C10 are connected to the reference ground together. The SE end of pin 2 is connected to the energy storage inductor L2 and the energy storage inductor L3 in sequence before the output end of the main power supply voltage. The energy storage inductor L3 is used to prevent the voltage from being pulled down. The positive electrode of the SS14 diode D3 is connected between the SE end of the pin 2 and the energy storage inductor L2, and the negative electrode is connected to the reference ground. The energy storage inductor L2 and the energy storage inductor L3 are connected in parallel to the seventh filter circuit 111, and the seventh filter circuit 111 consists of a capacitor C11, a capacitor C12 and a polar capacitor C7. The positive electrode of the polar capacitor C7, one end of the capacitor C11 and one end of the capacitor C12 are all connected between the energy storage inductor L2 and the energy storage inductor L3, the negative electrode of the polar capacitor C7, the other end of the capacitor C11 and the other end of the capacitor C12 are connected to the reference ground.One end of the resistor R1 is connected between the FB end of the pin 5 and the resistor R2 , and the other end is connected between the energy storage inductor L2 and the energy storage inductor L3 .

[0050] The model of the forward low-dropout voltage regulator U1 is an AMS1117-3.3V chip, and the third filter circuit 121 and the fourth filter circuit 122 are respectively configured at the VIN end and the VOUT end of the forward low-dropout voltage regulator U1 to ensure the stability of the first output voltage output by the forward low-dropout voltage regulator U1. The model of the linear voltage regulator U3 is a 7805 voltage regulating module, and the fifth filter circuit 131 and the sixth filter circuit 132 are respectively configured at the VIN end and the VOUT end of the linear voltage regulator U3 to ensure the stability of the second output voltage output by the linear voltage regulator U3.

[0051] In the present invention, the 8V main power supply voltage is converted into a first output voltage of 3.3V and a second output voltage of 5V by the first voltage conversion circuit 12 and the second voltage conversion circuit 13 respectively. Figure 3 and Figure 4As shown, the third filtering circuit 121 includes: a seventh polar capacitor (i.e., a polar capacitor C2 with a capacity of 47 μF) and an eighth capacitor (i.e., a capacitor C3 with a capacity of 0.1 μF), the positive electrode of the seventh polar capacitor and one end of the eighth capacitor are both connected to the VIN end of the forward low-dropout regulator U1, the fourth filtering circuit 122 includes: a ninth polar capacitor (i.e., a polar capacitor C5 with a capacity of 47 μF) and a tenth capacitor (i.e., a capacitor C6 with a capacity of 0.1 μF), The positive electrode of the ninth polar capacitor and one end of the tenth capacitor are both connected to the VOUT terminal of the forward low voltage dropout regulator U1, and the negative electrode of the seventh polar capacitor, the other end of the eighth capacitor, the negative electrode of the ninth polar capacitor, the other end of the tenth capacitor and the GND terminal of the forward low voltage dropout regulator U1 are commonly connected to the reference ground, thereby the 8V main power supply voltage is input from the VIN terminal of the forward low voltage dropout regulator U1, and the 3.3V first output voltage is output from the VOUT terminal of the forward low voltage dropout regulator U1. The fifth filtering circuit 131 includes: an eleventh polarized capacitor (i.e., a polarized capacitor C17 with a capacity of 100 μF and a rated voltage of 35 V) and a twelfth capacitor (i.e., a capacitor C18 with a capacity of 10 μF), the positive electrode of the eleventh polarized capacitor and one end of the twelfth capacitor are both connected to the VIN terminal of the linear regulator U3, and the sixth filtering circuit 132 includes: a thirteenth polarized capacitor (i.e., a polarized capacitor C16 with a capacity of 100 μF and a rated voltage of 16 V), a fourteenth capacitor (i.e., a capacitor C19 with a capacity of 1 μF) and a fifteenth capacitor (i.e., , capacitor C20 with a capacity of 0.1μF), the positive electrode of the thirteenth polar capacitor, one end of the fourteenth capacitor and one end of the fifteenth capacitor are all connected to the VOUT terminal of the linear regulator U3, the negative electrode of the eleventh polar capacitor, the other end of the twelfth capacitor, the negative electrode of the thirteenth polar capacitor, the other end of the fourteenth capacitor, the other end of the fifteenth capacitor and the GND terminal of the linear regulator U3 are commonly connected to the reference ground, thereby the main power supply voltage of 8V is input from the VIN terminal of the linear regulator U3, and the second output voltage of 5V is output from the VOUT terminal of the linear regulator U3.

[0052] Ginseng Figure 6 As shown, the AD conversion circuit 30 includes: an AD conversion chip U6 and a first differential voltage circuit 31 and a second differential voltage circuit 32 connected in parallel to the INN end of pin 3 and the INP end of pin 4 of the AD conversion chip U6. The tension sensor 40 includes four terminals, two of which are used to connect the power supply, and specifically include the positive pole of the power supply and the negative pole of the power supply, and the other two terminals are used to connect the signal output, and specifically include the negative output end and the positive output end. The INN end of pin 3 and the INP end of pin 4 of the AD conversion chip U6 are respectively connected to the negative output end of the tension sensor 40 (that is, Figure 6 S1-) and the positive output terminal (ie, Figure 6S1+ shown in ), which is used to receive the negative differential voltage signal and the positive differential voltage signal collected by the tension sensor 40 respectively. Among them, the first differential voltage circuit 31 includes: a first three-terminal capacitor (i.e., three-terminal capacitor C34) connected between the INN terminal of pin 3 of the AD conversion chip U6 and the negative output terminal of the tension sensor 40, which is used to filter the negative differential voltage signal. The second differential voltage circuit 32 includes: a second three-terminal capacitor (i.e., three-terminal capacitor C36) connected between the INP terminal of pin 4 of the AD conversion chip U6 and the positive output terminal of the tension sensor 40, which is used to filter the positive differential voltage signal to form a positive differential voltage filter signal. Specifically, the ground terminal of the first three-terminal capacitor and the ground terminal of the second three-terminal capacitor are connected to the reference ground, that is, Figure 6 One ground terminal of the first three-terminal capacitor and one ground terminal of the second three-terminal capacitor shown in the figure are connected to the reference ground together, and the other ground terminal of the first three-terminal capacitor and the other ground terminal of the second three-terminal capacitor are connected to the reference ground respectively. The first three-terminal capacitor is configured to connect the first signal input terminal 341 of the negative output terminal and the first signal output terminal 342 of the INN terminal connected to the pin 3, and the second three-terminal capacitor is configured to connect the second signal input terminal 361 of the positive output terminal and the second signal output terminal 362 of the INP terminal connected to the pin 4. The AD conversion chip U6 converts the negative differential voltage filter signal and the positive differential voltage filter signal into a negative differential voltage digital signal and a positive differential voltage digital signal respectively and transmits them to the control circuit 20, so that the control circuit 20 compares the negative differential voltage digital signal with the positive differential voltage digital signal to obtain tension data, and specifically, the microcontroller U7 compares the negative differential voltage digital signal and the positive differential voltage digital signal input through the PA2 terminal and the PA3 terminal to obtain tension data. The aforementioned comparison structure is not the invention point of the present application, and is completed by itself based on the internal logic circuit of the microcontroller U7. Please refer to the user manual of the microcontroller U7 for details. The comparison process performed by the microcontroller U7 is the prior art, so it is omitted in the present application. Those skilled in the art are aware of the above comparison process.

[0053] It should be noted that the three-terminal capacitor includes two ground terminals and two signal terminals, wherein the two ground terminals can be connected to the same point. The existing AD conversion circuit only adds a capacitor with a capacity of 0.1μF between the INN terminal and the INP terminal, and in actual application scenarios, due to the input signal of the INN terminal and the input signal of the INP terminal, there will be various clutter signals, and mainly include clutter signals generated by the power supply, the power supply voltage itself has certain clutter, and then through the voltage stabilization process of the circuit board, the DC5V voltage finally transmitted to the tension sensor will also have certain clutter, and thus the negative output terminal and the positive output terminal of the tension sensor will have corresponding clutter interference, and thus the final tension data has a large error. The three-terminal capacitor used in the present invention has a lower equivalent series inductance than the traditional capacitor, so that the acquisition circuit is better in high-frequency applications.

[0054] Ginseng Fig.13 As shown, under the same input signal, the waveform corresponding to the difference between the positive differential voltage filter signal and the negative differential voltage filter signal of the AD conversion circuit 30 disclosed in the present invention using the existing AD conversion circuit (i.e., connecting a 0.1μF capacitor between the INN terminal and the INP terminal) and the AD conversion circuit 30 disclosed in the present invention. Among them, when the difference between S1+ and S1- is a negative value, it means that the tension sensor is subjected to tension; when the difference between S1+ and S1- is a positive value, it means that the tension sensor is subjected to pressure; when the difference between S1+ and S1- is 0, it means that there is no force (i.e., the tension and pressure cancel each other out due to the balance of forces). Fig.13 It can be seen that the AD conversion circuit 30 disclosed in the present invention, whether it is subjected to tension or pressure or not subjected to force, has smaller differences in the pressure measurement range (0 to +20mV) and the tension measurement range (-20 to 0mV) than the differences formed by the existing AD conversion circuit.

[0055] It can be seen that the AD conversion circuit 30 disclosed by the present invention is more accurate than the differential voltage filter signal obtained by filtering the input signal by the AD conversion circuit of the prior art. Since the inductor increases the impedance at high frequency, the use of a three-terminal capacitor in the AD conversion module 30 disclosed by the present invention can effectively reduce the impedance, effectively filter out the high-frequency noise, and simultaneously suppress the power supply interference of 50Hz and 60Hz, improve the accuracy of the negative differential voltage digital signal and the positive differential voltage digital signal collected and converted by the tension sensor, and can effectively reduce the noise of the power supply. Through the low ESL characteristics, it can quickly respond to the high-frequency noise and transient changes on the tension sensor acquisition line, effectively improving the accuracy of the measurement. The model of the AD conversion chip U6 is the HX71708 chip, which is a high-precision 24-bit analog-to-digital conversion chip, which receives the ±20mV analog quantity provided by the tension sensor, converts it into digital form, and then transmits it to the control circuit 20. In one embodiment, the first differential voltage circuit 31 also includes: a first resistor connected between the first signal input terminal 341 of the first three-terminal capacitor and the negative output terminal of the tension sensor 40 (i.e., the resistor R22 with a maximum resistance value of 10Ω connected to the circuit) and a second resistor connected between the first signal output terminal 342 of the first three-terminal capacitor and the INN terminal of pin 3 of the AD conversion chip U6 (the resistor R23 with a maximum resistance value of 200Ω connected to the circuit), and the second differential voltage circuit 32 also includes: a third resistor connected between the second signal input terminal 361 of the second three-terminal capacitor and the positive output terminal of the tension sensor 40 (i.e., the resistor R26 with a maximum resistance value of 10Ω connected to the circuit) and a fourth resistor connected between the second signal output terminal 362 of the second three-terminal capacitor and the INP terminal of pin 4 of the buck conversion chip U6 (i.e., the resistor R27 with a maximum resistance value of 200Ω connected to the circuit).

[0056] The AD conversion circuit 30 also includes: a first filter circuit 33, which is composed of a first capacitor (i.e., a capacitor C35 with a capacity of 0.1 μF), a second capacitor (i.e., a capacitor C41 with a capacity of 0.1 μF), and a third capacitor (i.e., a capacitor C40 with a capacity of 0.1 μF) connected in parallel to the INN terminal of pin 3 and the INP terminal of pin 4 of the buck conversion chip U6. One end of the first capacitor is connected between the first signal output terminal 342 of the first three-terminal capacitor and the second resistor, and the other end is connected to the reference ground, and one end of the second capacitor is connected between the second signal output terminal 362 of the second three-terminal capacitor and the fourth resistor, and the other end is connected to the reference ground. The AD conversion circuit 30 also includes: a capacitor C33 with a capacity of 0.1 μF connected in parallel to the VREF end of pin 1 and the AGND end of pin 2 of the AD conversion chip U6, and the VOUT end of the linear regulator U3 is connected between the VREF end of pin 1 of the AD conversion chip U6 and the capacitor C33, and the AGND end of pin 2 of the AD conversion chip U6 is connected to the reference ground.

[0057] At the same time, the AVDD end of pin 8 of the AD conversion chip U6 is connected to the VOUT end of the linear regulator U3, which is used to deliver the second output voltage to the AD conversion chip U6, and the DVDD end of pin 7 of the AD conversion chip U6 is connected to the VOUT end of the forward low-dropout regulator U1, which is used to deliver the first output voltage to the AD conversion chip U6, and the AVDD end of pin 8 and the DVDD end of pin 7 of the AD conversion chip U6 are connected in parallel to the second filter circuit 34, and the first output voltage and the second output voltage are isolated by the second filter circuit 34. Specifically, the second filter circuit 34 includes: a capacitor C22 with a capacity of 1 μF and a capacitor C26 with a capacity of 0.1 μF connected between the VOUT terminal of the linear regulator U3 and the ground terminal to isolate the VOUT terminal of the linear regulator U3 from the ground terminal; the second filter circuit 34 also includes: a capacitor C32 with a capacity of 0.1 μF and a capacitor C28 with a capacity of 1 μF connected between the VOUT terminal of the forward low-dropout regulator U1 and the ground terminal to isolate the VOUT terminal of the forward low-dropout regulator U1 from the ground terminal. Thus, the second output voltage input to the AVDD terminal of pin 8 and the first output voltage input to the DVDD terminal of pin 7 are isolated by the aforementioned four capacitors (i.e., capacitor C22, capacitor C26, capacitor C32 and capacitor C28) to meet the power supply requirements of the DC voltage required by the AD conversion chip U6 and the pressure sensor 40, and ensure that they operate normally under the correct voltage and potential conditions.

[0058] In order to ensure the accuracy of the negative differential voltage signal and the positive differential voltage signal collected by the tension sensor 40, the tension sensor 40 is arranged in pairs, and accordingly, the AD conversion circuit 30 is also arranged in pairs. Since the two tension sensors 40 are arranged in a similar manner, in the following description, only one of the tension sensors 40 is taken as an example for exemplary description.

[0059] Ginseng Figure 7 As shown, the tension sensor 40 is connected to the power supply circuit 10 through the connector P5, the first terminal (i.e., terminal 1) of the connector P5 is isolated from the ground through the first diode (i.e., diode D21), the second terminal (i.e., terminal 2) of the connector P5 is connected to the VOUT terminal of the linear regulator U3, the third terminal (i.e., terminal 3) of the connector P5 is connected to the reference ground, and the fourth terminal (i.e., terminal 4) and the fifth terminal (i.e., terminal 5) of the connector P5 are respectively connected to the positive output terminal and the negative output terminal of the tension sensor 40. The positive electrode of the first diode is connected to the first terminal of the connector P5, and the negative electrode is connected to the reference ground. The resistor R33 with a maximum resistance value of 10Ω and the capacitor C44 with a capacity of 10μF are connected in sequence between the second terminal of the connector P5 and the VOUT terminal of the linear regulator U3, and the capacitor C47 with a capacity of 0.1μF and the capacitor C49 with a capacity of 0.1μF are connected in parallel between the capacitor C44 and the VOUT terminal of the linear regulator U3. One end of the resistor R35 with a maximum resistance value of 10Ω connected to the circuit is connected between the first terminal of the connector P5 and the first diode, and the other end of the resistor R35, one end of the capacitor C47 and one end of the capacitor C49 are connected to the reference ground. The positive pole of the diode D17 is connected to the second terminal of the connector P5, and the negative pole and the third terminal of the connector P5 are connected to the reference ground. At the same time, the GND end of the microcontroller U7 described below is connected to the shielding layer of the tension sensor 40 to effectively prevent electrostatic interference, and the diode D17 is added to prevent recoil.

[0060] Ginseng Figure 5 As shown, the control circuit 20 includes: a microcontroller U7, the PA2 end of the pin 12 and the PA3 end of the pin 13 of the microcontroller U7 are respectively connected to the DOUT end of the pin 6 and the SCK end of the pin 5 of the AD conversion chip U6, so as to realize the data transmission between the microcontroller U7 and the buck conversion chip U6. It should be noted that the model of the microcontroller U7 is STM32F103C8T6, which is a 32-bit chip.

[0061] Ginseng Figure 8As shown, the tension detection control system 100 also includes: an analog output circuit 50 connected to the control circuit 20, which is used to convert the above tension data into analog data and output it, so that the PLC device can perform related control. The analog output circuit 50 includes: a digital-to-analog converter U8, and the digital-to-analog converter U8 is configured to connect the SCLK terminal, SDLN terminal, SDO terminal, CLSN terminal, SLEAR terminal and LATCH terminal of the PB13 terminal, PB15 terminal, PB14 terminal, PB3 terminal, PA15 terminal and PB4 terminal of the microcontroller U7 respectively. Specifically, the PB13 terminal of pin 26 of the microcontroller U7 is connected to the SCLK terminal of pin 8 of the digital-to-analog converter U8, the PB15 terminal of pin 28 of the microcontroller U7 is connected to the SDLN terminal of pin 9 of the digital-to-analog converter U8, the PB14 terminal of pin 27 of the microcontroller U7 is connected to the SDO terminal of pin 10 of the digital-to-analog converter U8, the PB3 terminal of pin 39 of the microcontroller U7 is connected to the CLSE terminal of pin 5 of the digital-to-analog converter U8, the PA15 terminal of pin 38 of the microcontroller U7 is connected to the CLEAR terminal of pin 6 of the digital-to-analog converter U8, and the PB4 terminal of pin 40 of the microcontroller U7 is connected to the LATCH terminal of pin 7 of the digital-to-analog converter U8. The model of the digital-to-analog converter U8 is AD5412, which is a 12-bit digital-to-analog converter with built-in programmable power flow and programmable voltage output. The output of 4-20mA, 0-5V, and 0-10V analog data can be selected through the dip switch setting. The AD5412 uses SPI communication, and the communication pins are the SCLK end of the aforementioned pin 8, the SDLN end of pin 9, and the SDO end of pin 10. The output type is determined by the CLSE end of the aforementioned pin 5, the CLEAR end of pin 6, and the LATCH end of pin 7.

[0062] Ginseng Fig. 9 As shown, the tension detection control system 100 also includes: a communication circuit 60 connected to the control circuit 20, which is used to communicate with an external device. The communication circuit 60 includes: a communication chip U4, and the communication chip U4 is configured to connect the RO end and the DI end of the PA10 end and the PA9 end of the microcontroller U7 respectively, and the A end and the B end of the communication chip U4 are connected to the external device. Specifically, the PA10 end of the pin 31 of the microcontroller U7 is connected to the RO end of the pin 1 of the communication chip U4, and the PA9 end of the pin 30 of the microcontroller U7 is connected to the DI end of the pin 4 of the communication chip U4. The model of the communication chip U4 is the SP3485EN communication chip, which can communicate externally through the RS485 circuit, and realize the RD485 serial port output through the A end of the pin 6 and the B end of the pin 7 of the communication chip U4.

[0063] Ginseng Fig.10As shown, the tension detection control system 100 also includes: a display screen 70, which is connected to the control circuit 20 through a connector P4. The model of the display screen 70 is a st7789 serial port screen, and the display content is a negative differential voltage filter signal and a corresponding converted negative differential voltage digital signal, a positive differential voltage filter signal and a corresponding converted positive differential voltage digital signal, and SPI communication is adopted. Terminal 7 of the connector P4 is connected to the PA7 end of pin 17 of the microcontroller U7, terminal 8 of the connector P4 is connected to the PA6 end of pin 16 of the microcontroller U7, terminal 9 of the connector P4 is connected to the PA5 end of pin 15 of the microcontroller U7, terminal 3 of the connector P4 is connected to the PB1 end of pin 19 of the microcontroller U7 through a transistor 9013, and other pins can be connected according to the default configuration of the serial port screen.

[0064] Ginseng Fig.11 and Fig.12 As shown, the tension detection control system 100 also includes: a key circuit 80 and a dial switch circuit 90. The key circuit 80 includes three independent keys, namely, key K1, key K3 and key K4, and key K1 is connected to the PB5 end of pin 41 of the microcontroller U7, key K3 is connected to the PB6 end of pin 42 of the microcontroller U7, and key K4 is connected to the PB7 end of pin 43 of the microcontroller U7. Through key operation, key K1 is rounded down, and the displayed value is rounded down for the convenience of reading. Key K3 is used to round up the displayed value for the convenience of reading. Key K4 is a reset key. The dial switch circuit 90 includes a 3-bit dial switch K2. Before starting up, the control board can realize the selection of 4-20mA, 0-5V, and 0-10V analog data through different selections of the dial switch. The dial switch K2 is respectively connected to the PB10 end of pin 21 of the microcontroller U7, the PB11 end of pin 22, and the PA11 end of pin 32.

[0065] The specific meanings of the pins contained in each processor unit in this application, such as (forward low dropout regulator U1, voltage regulating chip U2, linear regulator U3, communication chip U4, AD conversion chip U6, microcontroller U7 and digital-to-analog converter U8) are described in the product manual of the corresponding model and will not be repeated in this application.

[0066] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0067] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0068] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An AD conversion circuit connected between a tension sensor and a control circuit, characterized in that: The AD conversion circuit includes: an AD conversion chip U6 and a first differential voltage circuit and a second differential voltage circuit connected in parallel to the INN terminal and the INP terminal of the AD conversion chip U6; The INN terminal and the INP terminal of the AD conversion chip U6 are respectively connected to the negative output terminal and the positive output terminal of the tension sensor, for receiving the negative differential voltage signal and the positive differential voltage signal respectively; The first differential voltage circuit includes: a first three-terminal capacitor connected between the INN terminal of the AD conversion chip U6 and the negative output terminal of the tension sensor, used for filtering the negative differential voltage signal to form a negative differential voltage filter signal; The second differential voltage circuit includes: a second three-terminal capacitor connected between the INP terminal of the AD conversion chip U6 and the positive output terminal of the tension sensor, used for filtering the positive differential voltage signal to form a positive differential voltage filter signal; The ground terminal of the first three-terminal capacitor and the ground terminal of the second three-terminal capacitor are connected to a reference ground, the first three-terminal capacitor is configured to connect a first signal input terminal of the negative output terminal and a first signal output terminal of the INN terminal, and the second three-terminal capacitor is configured to connect a second signal input terminal of the positive output terminal and a second signal output terminal of the INP terminal; The AD conversion chip U6 converts the negative differential voltage filter signal and the positive differential voltage filter signal into a negative differential voltage digital signal and a positive differential voltage digital signal respectively and transmits them to the control circuit, so that the control circuit compares the negative differential voltage digital signal with the positive differential voltage digital signal to obtain tension data.

2. The AD conversion circuit according to claim 1, characterized in that: The first differential voltage circuit further includes: a first resistor connected between the first signal input terminal of the first three-terminal capacitor and the negative output terminal of the tension sensor, and a second resistor connected between the first signal output terminal of the first three-terminal capacitor and the INN terminal of the AD conversion chip U6; The second differential voltage circuit also includes: a third resistor connected between the second signal input terminal of the second three-terminal capacitor and the positive output terminal of the tension sensor, and a fourth resistor connected between the second signal output terminal of the second three-terminal capacitor and the INP terminal of the buck converter chip U6.

3. The AD conversion circuit according to claim 2, characterized in that: The AD conversion circuit further includes: a first filter circuit, the first filter circuit is composed of a first capacitor, a second capacitor and a third capacitor connected in parallel to the INN terminal and the INP terminal of the buck conversion chip U6; One end of the first capacitor is connected between the first signal output end of the first three-terminal capacitor and the second resistor, and the other end is connected to the reference ground. One end of the second capacitor is connected between the second signal output end of the second three-terminal capacitor and the fourth resistor, and the other end is connected to the reference ground.

4. A tension detection control system, characterized in that: include: A power supply circuit, a control circuit connected to the power supply circuit, an AD conversion circuit as described in any one of claims 1 to 3 arranged in pairs, and a tension sensor arranged in pairs, and a single AD conversion circuit is connected between a single tension sensor and the control circuit.

5. The tension detection control system according to claim 4, characterized in that: The power supply circuit comprises: a first voltage conversion circuit and a second voltage conversion circuit connected to the main circuit; The main circuit includes: a voltage regulating chip U2, the first voltage conversion circuit includes: a forward low-dropout voltage regulator U1, a third filter circuit connected in parallel to the VIN terminal and the GND terminal of the forward low-dropout voltage regulator U1, and a fourth filter circuit connected in parallel to the VOUT terminal and the GND terminal of the forward low-dropout voltage regulator U1, the second voltage conversion circuit includes: a linear voltage regulator U3, a fifth filter circuit connected in parallel to the VIN terminal and the GND terminal of the linear voltage regulator U3, and a sixth filter circuit connected in parallel to the VOUT terminal and the GND terminal of the linear voltage regulator U3, the VIN terminal of the forward low-dropout voltage regulator U1 and the VIN terminal of the linear voltage regulator U3 are both connected to the SE terminal of the voltage regulating chip U2, for respectively connecting to the main power supply voltage output by the voltage regulating chip U2, and respectively converting the main power supply voltage into a first output voltage (3.3V) and a second output voltage (5.0V); The third filtering circuit includes: a seventh polar capacitor and an eighth capacitor, the positive electrode of the seventh polar capacitor and one end of the eighth capacitor are both connected to the VIN end of the forward low-dropout voltage regulator U1, the fourth filtering circuit includes: a ninth polar capacitor and a tenth capacitor, the positive electrode of the ninth polar capacitor and one end of the tenth capacitor are both connected to the VOUT end of the forward low-dropout voltage regulator U1, the negative electrode of the seventh polar capacitor, the other end of the eighth capacitor, the negative electrode of the ninth polar capacitor, the other end of the tenth capacitor and the GND end of the forward low-dropout voltage regulator U1 are commonly connected to the reference ground; The fifth filtering circuit includes: an eleventh polar capacitor and a twelfth capacitor, the positive electrode of the eleventh polar capacitor and one end of the twelfth capacitor are both connected to the VIN terminal of the linear regulator U3, the sixth filtering circuit includes: a thirteenth polar capacitor, a fourteenth capacitor and a fifteenth capacitor, the positive electrode of the thirteenth polar capacitor, one end of the fourteenth capacitor and one end of the fifteenth capacitor are all connected to the VOUT terminal of the linear regulator U3, the negative electrode of the eleventh polar capacitor, the other end of the twelfth capacitor, the negative electrode of the thirteenth polar capacitor, the other end of the fourteenth capacitor, the other end of the fifteenth capacitor and the GND terminal of the linear regulator U3 are commonly connected to the reference ground.

6. The tension detection control system according to claim 5, characterized in that: The tension sensor is connected to the power supply circuit through a connector, the first terminal of the connector is isolated from the ground by a first diode, the second terminal of the connector is connected to the VOUT end of the linear regulator U3, the third terminal of the connector is connected to the reference ground, and the fourth terminal and the fifth terminal of the connector are respectively connected to the positive output end and the negative output end of the tension sensor.

7. The tension detection control system according to claim 5, characterized in that: The AVDD terminal of the AD conversion chip U6 is connected to the VOUT terminal of the linear regulator U3, so as to deliver a second output voltage to the AD conversion chip U6. The DVDD terminal of the AD conversion chip U6 is connected to the VOUT terminal of the forward low-dropout regulator U1, so as to deliver a first output voltage to the AD conversion chip U6. A second filtering circuit is connected in parallel to the AVDD terminal and the DVDD terminal of the AD conversion chip U6, and the second filtering circuit isolates the first output voltage from the second output voltage.

8. The tension detection control system according to claim 5, characterized in that: The control circuit includes: a microcontroller U7, and a PA2 terminal and a PA3 terminal of the microcontroller U7 are respectively connected to a DOUT terminal and an SCK terminal of the AD conversion chip U6.

9. The tension detection control system according to claim 8, characterized in that: The tension detection control system further comprises: an analog output circuit connected to the control circuit, for converting the tension data into analog data and outputting the analog data; The analog output circuit includes: a digital-to-analog converter U8, and the digital-to-analog converter U8 is configured to be respectively connected to the SCLK terminal, SDLN terminal, SDO terminal, CLSE terminal, CLEAR terminal and LATCH terminal of the PB13 terminal, PB15 terminal, PB14 terminal, PB3 terminal, PA15 terminal and PB4 terminal of the microcontroller U7.

10. The tension detection control system according to claim 8, characterized in that: The tension detection control system further includes: a communication circuit connected to the control circuit, for communicating with an external device; The communication circuit includes: a communication chip U4, wherein the communication chip U4 is configured to be connected to the RO terminal and the DI terminal of the PA10 terminal and the PA9 terminal of the microcontroller U7 respectively, and the A terminal and the B terminal of the communication chip U4 are connected to an external device.

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