Circuit for determining gelatinous layer

Abstract

The utility model relates to the field of coal gelatinous layer index measurement. More specifically, the utility model relates to a circuit for determining a gelatinous layer. Comprising a temperature acquisition circuit used for acquiring the temperature in a coal cup in a gelatinous layer measurement process; the heating circuit is used for heating the coal cup in the gelatinous layer measuring process; the displacement measuring circuit is used for measuring the displacement of the upper surface of the coal sample in the coal cup in the gelatinous layer measuring process; and the control chip is connected to the temperature acquisition circuit and the heating circuit so as to control the work of the heating circuit according to the acquired temperature in the coal cup, and is also connected to the displacement measurement circuit so as to obtain the thickness of a gelatinous layer generated by the coal sample. By adopting the circuit for determining the gelatinous layer, the efficiency, the accuracy and the automation degree of determining the gelatinous layer are improved.

Description

Technical Field

[0001] The present utility model generally relates to the field of determination of the coal plastic layer index. More specifically, the present utility model relates to a circuit for plastic layer determination. Background Art

[0002] The determination of the plastic layer is an important method for evaluating the quality of coal. Through the determination of the plastic layer, the plasticity, caking property and other related properties of coal can be obtained, and the coking situation of coal in the coke oven and the quality of the produced coke can be preliminarily predicted. The determination of the plastic layer is of great significance for the industrial utilization of coal, especially in the coking process. By measuring the plastic layer index of coal, the softening, melting and solidification characteristics of coal during heating can be understood, providing an important basis for the optimization of the coking process. In the prior art, workers usually manually determine the plastic layer of coal using experimental instruments such as coal cups, probes, heating furnaces, and thermocouples. During the determination of the plastic layer, on-site workers need to use probes to measure the thickness of the plastic layer, observe the temperature inside the coal cup collected by the thermocouple, and adjust the working state of the heating furnace; this results in a low degree of automation in the determination of the plastic layer, a large labor intensity for workers, and there will be certain errors when manually measuring the thickness of the plastic layer with a probe, thus leading to a low accuracy of the determination result of the plastic layer; in addition, when it is necessary to simultaneously determine the plastic layers of sample coal in multiple coal cups, manually measuring the thickness of the plastic layer requires measuring the plastic layer in each coal cup one by one, with low efficiency and prone to missed inspection situations. Summary of the Utility Model

[0003] To solve the technical problems of low automation degree, low efficiency and low accuracy of the determination result in the prior art during the determination of the plastic layer, the present utility model provides solutions in the following aspects.

[0004] In a first aspect, the present utility model provides a circuit for plastic layer determination, comprising:

[0005] A temperature acquisition circuit for acquiring the temperature inside the coal cup during the determination of the plastic layer;

[0006] A heating circuit for heating the coal cup during the determination of the plastic layer;

[0007] A displacement measurement circuit for measuring the displacement of the upper surface of the coal sample inside the coal cup during the determination of the plastic layer;

[0008] A control chip, connected to the temperature acquisition circuit and the heating circuit to control the operation of the heating circuit according to the acquired temperature inside the coal cup, and also connected to the displacement measurement circuit to obtain the thickness of the plastic layer generated by the coal sample.

[0009] Preferably, the temperature acquisition circuit includes: a first thermocouple interface chip and a platinum resistance temperature detection converter. The input pins of the first thermocouple interface chip are connected to a first thermocouple, and the input pins of the platinum resistance temperature detection converter are connected to a platinum resistance. The serial input pins, serial output pins, and serial clock pins of the first thermocouple interface chip and the platinum resistance temperature detection converter are all connected to the IO pins of the control chip. The first thermocouple is used to collect the temperature inside the coal cup, and the platinum resistance is used to collect the indoor temperature where the coal cup is located.

[0010] Preferably, a first filter capacitor and a second filter capacitor are respectively connected in series between the two input pins of the first thermocouple interface chip and between the two input pins of the platinum resistance temperature detection converter. The two input pins of the first thermocouple interface chip are respectively connected in series with a first current-limiting resistor and a second current-limiting resistor.

[0011] Preferably, the heating circuit includes a silicon carbide rod. The silicon carbide rod is connected to a power supply through a relay, and the controlled end of the relay is connected to a relay control circuit. The relay control circuit includes an optocoupler. The anode of the light-emitting diode of the optocoupler is connected to a supply voltage, its cathode is grounded through a first grounding resistor and connected to the IO pin of the control chip through a fifth current-limiting resistor. The first end of the phototransistor of the optocoupler is connected to the supply voltage through a thick film resistor, its second end is connected to the controlled end of the relay, and the controlled end of the phototransistor of the optocoupler is grounded through a second grounding resistor.

[0012] Preferably, a third filter capacitor is connected in parallel across both ends of the second grounding resistor, and a sixth current-limiting resistor is connected in series between the first end and the thick film resistor.

[0013] Preferably, the displacement measurement circuit includes: a displacement sensor, a voltage dividing branch, and an operational amplifier. The output end of the displacement sensor is connected to one end of the voltage dividing branch, the other end of the voltage dividing branch is grounded, the voltage dividing point of the voltage dividing branch is connected to the non-inverting input terminal of the operational amplifier, the inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier through a feedback resistor, and the output terminal of the operational amplifier is connected to the IO pin of the control chip.

[0014] Preferably, the output terminal of the operational amplifier is connected to the input terminal of a first filter circuit, and the output terminal of the filter circuit is connected to the IO pin of the control chip.

[0015] Preferably, the output terminal of the first filter circuit is respectively connected to the anode of a first Schottky diode and the cathode of a second Schottky diode. The cathode of the first Schottky diode is connected to the supply voltage, and the anode of the second Schottky diode is grounded.

[0016] Preferably, the control chip is connected to the host computer through an RS232 communication circuit. The RS232 communication circuit includes an RS232 interface chip. The second transmitter input pin and the second receiver output pin of the RS232 interface chip are connected to the host computer. The second transmitter output pin and the second receiver input pin of the RS232 interface chip are respectively connected to the control chip through a second filter circuit and a third filter circuit.

[0017] Preferably, the output ends of the second filter circuit and the third filter circuit are both grounded through bidirectional TVS tubes.

[0018] The technical effect of the present utility model is as follows: By using the circuit for the determination of the plastic layer of the present utility model, it is possible to automatically measure the thickness of the plastic layer during the determination of the plastic layer, thereby improving the efficiency of the determination of the plastic layer, and automatically controlling the heating circuit according to the temperature of the coal cup collected, thereby improving the accuracy and automation degree of the determination of the plastic layer.

[0019] Furthermore, during the temperature measurement by the thermocouple, a temperature difference will be generated between the cold end and the hot end. The temperature difference will cause electrons at the hot junction to diffuse from the high-temperature end to the low-temperature end, thereby generating an electromotive force in the thermocouple circuit. According to the magnitude of this electromotive force, the measured temperature can be determined. However, during the actual measurement process, the temperature of the cold end will change, resulting in an error in the measured temperature. By additionally setting a platinum resistance temperature detection converter and a platinum resistance to measure the room temperature, the temperature of the coal cup measured by the thermocouple can be converted according to the room temperature to obtain a more accurate temperature of the coal cup.

[0020] Furthermore, by connecting the first end of the phototransistor of the optocoupler to the supply voltage through a thick film resistor, current limiting protection can be provided for the phototransistor, thereby protecting the stability of the heating circuit. Secondly, in some cases, the impedance between the input end and the output end of the optocoupler may not match, which will affect the signal transmission quality. By connecting a thick film resistor in series, the impedance of the circuit can be adjusted to a certain extent to make the impedance between the input and output more matched, thereby improving the efficiency and stability of signal transmission. In addition, by adjusting the resistance value of the thick film resistor, the operating point of the phototransistor can be adjusted to make it in the best operating state.

[0021] Furthermore, by connecting a third filter capacitor in parallel at both ends of the second grounding resistor, interference signals can be filtered out to make the operation of the phototransistor more stable. By connecting a sixth current limiting resistor in series between the first end of the phototransistor and the thick film resistor, current limiting protection can be further provided for the phototransistor.

[0022] Further, by setting a voltage dividing branch at the output end of the displacement sensor, the amplitude of the voltage signal output by the displacement sensor can be converted into a voltage range acceptable to the control chip, thereby preventing the control chip from being burned out. The provided operational amplifier can form a follower for impedance matching, making the voltage output at the voltage dividing point of the voltage dividing branch not easily attenuated, thereby improving the reliability of the displacement measurement circuit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become readily understandable. In the drawings, several embodiments of the present invention are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0024] Figure 1 is a schematic circuit diagram of the circuit for determining the plastic layer in the embodiment of the present invention;

[0025] Figure 2 is a schematic circuit diagram of the temperature acquisition circuit in the embodiment of the present invention;

[0026] Figure 3 is a schematic circuit diagram of the relay control circuit in the embodiment of the present invention;

[0027] Figure 4 is a schematic circuit diagram of the displacement measurement circuit in the embodiment of the present invention;

[0028] Figure 5 is a schematic circuit diagram of the RS232 communication circuit in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0030] Next, the specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0031] Embodiment:

[0032] As Figure 1As shown in the figure, the circuit for determining the plastic layer of the present utility model is characterized by comprising: a temperature acquisition circuit for acquiring the temperature inside the coal cup during the determination of the plastic layer; a heating circuit for heating the coal cup during the determination of the plastic layer; a displacement measurement circuit for measuring the displacement of the upper surface of the coal sample inside the coal cup during the determination of the plastic layer; and a control chip connected to the temperature acquisition circuit and the heating circuit to control the operation of the heating circuit according to the acquired temperature inside the coal cup, and also connected to the displacement measurement circuit to obtain the thickness of the plastic layer generated by the coal sample.

[0033] The circuit for determining the plastic layer of the present utility model can acquire the temperature and heat the coal cup during the determination of the plastic layer, and automatically measure the displacement of the upper surface of the coal sample inside the coal cup, so as to obtain the thickness of the plastic layer generated by the coal sample. Specific methods for determining the plastic layer, such as heating the coal cup to a certain temperature, how to obtain the thickness of the plastic layer according to the displacement of the upper surface of the coal sample, and how to determine the plastic layer according to the thickness of the plastic layer, all belong to the prior art. The innovation of the present utility model lies in the connection relationship of the hardware circuit.

[0034] By using the circuit for determining the plastic layer of the present utility model, it is possible to automatically measure the thickness of the plastic layer during the determination of the plastic layer, thereby improving the efficiency of determining the plastic layer, and automatically controlling the heating circuit according to the acquired temperature of the coal cup, thereby improving the accuracy and automation degree of determining the plastic layer.

[0035] In one embodiment, as Figure 2 shown, the temperature acquisition circuit includes: a first thermocouple interface chip U5 and a platinum resistance temperature detection converter U9. The input pin of the first thermocouple interface chip is connected to a first thermocouple (not shown in the figure), and the input pin of the platinum resistance temperature detection converter is connected to a platinum resistance (not shown in the figure). The serial input pin SDI, serial output pin SDO, and serial clock pin SCK of the first thermocouple interface chip and the platinum resistance temperature detection converter are all connected to the IO pins of the control chip (not shown in the figure); wherein the first thermocouple is used to acquire the temperature inside the coal cup, and the platinum resistance is used to acquire the indoor temperature where the coal cup is located. In the figure, the end point K1- is connected to the first thermocouple, the end point N+ is connected to the platinum resistance, and the end points A, B, and C are all connected to the IO pins of the control chip. The power supply pins AVDD of the first thermocouple interface chip are both connected to a 3.3V voltage.

[0036] During the temperature measurement process of the thermocouple, a temperature difference will be generated between the cold end and the hot end. This temperature difference will cause electrons at the hot junction to diffuse from the high-temperature end to the low-temperature end, thereby generating an electromotive force in the thermocouple circuit. Based on the magnitude of this electromotive force, the measured temperature can be determined. However, during the actual measurement process, the temperature of the cold end will change, resulting in an error in the measured temperature. By additionally setting a platinum resistance temperature detection converter and a platinum resistance to measure the room temperature, the temperature of the coal cup measured by the thermocouple can be converted based on the room temperature to obtain a more accurate temperature of the coal cup.

[0037] In one embodiment, in order to filter out interference signals and make the operation of the first thermocouple interface chip and the platinum resistance temperature detection converter more stable, a first filter capacitor C1 and a second filter capacitor C2 are respectively connected in series between the two input pins of the first thermocouple interface chip and between the two input pins of the platinum resistance temperature detection converter. In order to prevent the input pin current of the first thermocouple interface chip from being too large and burning out the first thermocouple interface chip, a first current-limiting resistor R1 and a second current-limiting resistor R2 are respectively connected in series to the two input pins of the first thermocouple interface chip.

[0038] In another embodiment, the temperature acquisition circuit further includes: a second thermocouple interface chip U8, wherein the input pins of the second thermocouple interface chip are connected to a second thermocouple (not shown in the figure), and the serial input pin SDI, serial output pin SDO, and serial clock pin SCK of the second thermocouple interface chip are all connected to the IO pins of the control chip.

[0039] Since some plastic layer determination devices have two coal cups, by setting two thermocouple interface chips and two thermocouples, the temperatures in the two coal cups can be measured respectively.

[0040] In one embodiment, the heating circuit includes a silicon carbide rod, and the silicon carbide rod is connected to the power supply through a relay. The controlled end of the relay is connected to a relay control circuit, as Figure 3 shown. The relay control circuit includes an optocoupler D5. The anode of the light-emitting diode of the optocoupler D5 is connected to a 3.3V power supply voltage. Its cathode is grounded to GND through a first grounding resistor R65 and connected to the IO pin of the control chip through a fifth current-limiting resistor R60. The first end of the phototransistor of the optocoupler is connected to a 12V power supply voltage through a thick film resistor RF5. Its second end SSR+ is connected to the controlled end of the relay. The controlled end of the phototransistor of the optocoupler is grounded to GND1 through a second grounding resistor R70. The endpoint TP25 in the figure is connected to the IO pin of the control chip.

[0041] By connecting the first end of the optoelectronic transistor of the optocoupler to the supply voltage through a thick film resistor, current limiting protection can be provided for the optoelectronic transistor, thereby protecting the stability of the heating circuit. Secondly, in some cases, the impedance between the input and output ends of the optocoupler may not match, which will affect the signal transmission quality. By connecting a thick film resistor in series, the impedance of the circuit can be adjusted to a certain extent to make the impedance between the input and output more matched, thereby improving the efficiency and stability of signal transmission. In addition, by adjusting the resistance value of the thick film resistor, the operating point of the optoelectronic transistor can be adjusted to make it in the best operating state.

[0042] In one embodiment, a third filter capacitor C81 is connected in parallel across both ends of the second grounding resistor R70, and a sixth current limiting resistor R59 is connected in series between the first end and the thick film resistor.

[0043] By connecting a third filter capacitor in parallel across both ends of the second grounding resistor, interference signals can be filtered out to make the operation of the optoelectronic transistor more stable. By connecting a sixth current limiting resistor in series between the first end of the optoelectronic transistor and the thick film resistor, current limiting protection for the optoelectronic transistor can be further provided.

[0044] In one embodiment, as Figure 4 shown, the displacement measurement circuit includes: a displacement sensor, a voltage dividing branch, and an operational amplifier OP. The output end of the displacement sensor is connected to one end of the voltage dividing branch, the other end of the voltage dividing branch is grounded to GND1, the voltage dividing point of the voltage dividing branch is connected to the non-inverting input end of the operational amplifier OP, the inverting input end of the operational amplifier is connected to the output end of the operational amplifier through a feedback resistor R3, and the output end of the operational amplifier is connected to the IO pin of the control chip. The grounding end of the operational amplifier is grounded to GND1, and the power supply end is connected to the +5V power supply. In the figure, the endpoint TP1 is connected to the IO pin of the control chip, and the endpoint D is connected to the output end of the displacement sensor. The voltage dividing branch includes a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6 connected in series, and the connection point of the fifth resistor R5 and the sixth resistor R6 is the voltage dividing point.

[0045] By providing a voltage dividing branch at the output end of the displacement sensor, the amplitude of the voltage signal output by the displacement sensor can be converted into a voltage range acceptable to the control chip, thereby preventing the control chip from being burned out. The provided operational amplifier can form a follower for impedance matching, so that the voltage output at the voltage dividing point of the voltage dividing branch is not easily attenuated, thereby improving the reliability of the displacement measurement circuit.

[0046] In one embodiment, the output terminal of the operational amplifier is connected to the input terminal of the first filter circuit, and the output terminal of the filter circuit is connected to the IO pin of the control chip. The first filter circuit is an RC filter circuit, including a seventh resistor R7 and a fourth filter capacitor C4. Wherein, one end of the seventh resistor R7 is connected to the output terminal of the operational amplifier, and the other end thereof is the output terminal of the first filter circuit, which is connected to one end of the fourth filter capacitor C4, and the other end of the fourth filter capacitor C4 is grounded to GND.

[0047] By arranging a filter circuit between the output terminal of the operational amplifier and the IO pin of the control chip, interference signals can be filtered out, making the operation of the displacement measurement circuit more stable and reliable.

[0048] In one embodiment, the output terminal of the first filter circuit is respectively connected to the anode of the first Schottky diode D1 and the cathode of the second Schottky diode D2. The cathode of the first Schottky diode is connected to the 3.3V supply voltage, and the anode of the second Schottky diode is grounded to GND.

[0049] By arranging the first Schottky diode and the second Schottky diode at the output terminal of the first filter circuit, voltage protection can be provided for the control chip to prevent the voltage from being too high and burning out the pins of the control chip.

[0050] In one embodiment, the control chip is connected to the host computer through an RS232 communication circuit. The RS232 communication circuit includes an RS232 interface chip. As Figure 5 shown, the second transmitter input pin T2IN and the second receiver output pin R2OUT of the RS232 interface chip U1 are connected to the host computer. The second transmitter output pin T2OUT and the second receiver input pin R2IN of the RS232 interface chip are respectively connected to the control chip through a second filter circuit and a third filter circuit. In this embodiment, the second filter circuit and the third filter circuit have the same structure. The second filter circuit includes an eighth resistor R8 and a fifth filter capacitor C5. Wherein, one end of the eighth resistor R8 is connected to the second transmitter output pin T2OUT of the RS232 interface chip, and the other end of the eighth resistor R8 is the output terminal of the second filter circuit and is connected to one end of the fifth filter capacitor C5. The other end of the fifth filter capacitor C5 is grounded to GND. In the figure, the end point TP8 and the end point TP10 are connected to the IO pin of the control chip, and the end point TP9 and the end point TP7 are connected to the host computer.

[0051] By connecting the control chip to the host computer, the temperature in the coal cup, the measured thickness of the plastic layer, and the measurement result of the plastic layer can be displayed during the determination of the plastic layer, and it is convenient for human-computer interaction.

[0052] By setting a filter circuit between the RS232 interface chip and the control chip, the signal transmitted between the RS232 communication circuit and the control chip can be made more stable.

[0053] In one embodiment, the output ends of the second filter circuit and the third filter circuit are both grounded through bidirectional TVS diodes. Among them, the output end of the first filter circuit is grounded to GND through the first bidirectional TVS diode DR4, and the output end of the first filter circuit is grounded to GND through the second bidirectional TVS diode DR5.

[0054] By setting bidirectional TVS diodes between the filter circuit and the control chip, the functions of static electricity filtering and loop protection can be achieved, thereby improving the reliability and stability of the RS232 communication circuit.

[0055] In the above description of this specification, unless otherwise clearly specified and limited, terms such as "fixed", "installed", "connected" or "coupled" should be understood in a broad sense. For example, regarding the term "connected", it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two components or the interaction relationship between two components. Therefore, unless clearly limited otherwise in this specification, those skilled in the art can understand the specific meaning of the above terms in this utility model according to specific circumstances.

[0056] The terms "first" or "second" etc. used in this specification to refer to numbers or ordinals are only for descriptive purposes and cannot be understood as explicitly or implicitly indicating relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this specification, the meaning of "a plurality" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically limited.

[0057] Although this specification has shown and described multiple embodiments of the present utility model, it is obvious to those skilled in the art that such embodiments are provided only by way of example. Those skilled in the art will think of many changes, alterations and alternative ways without departing from the idea and spirit of the present utility model. It should be understood that various alternative solutions to the embodiments of the present utility model described herein can be adopted in the process of practicing the present utility model.

Claims

1. A circuit for determining the plastic layer, characterized in that, Comprising: A temperature acquisition circuit, configured to acquire the temperature inside the coal cup during the determination of the plastic layer; A heating circuit, configured to heat the coal cup during the determination of the plastic layer; A displacement measurement circuit, configured to measure the displacement of the upper surface of the coal sample inside the coal cup during the determination of the plastic layer; A control chip, connected to the temperature acquisition circuit and the heating circuit to control the operation of the heating circuit according to the acquired temperature inside the coal cup, and also connected to the displacement measurement circuit to obtain the thickness of the plastic layer generated by the coal sample.

2. The circuit for plastometer determination according to claim 1, characterized in that, The temperature acquisition circuit includes: a first thermocouple interface chip and a platinum resistance temperature detection converter. The input pins of the first thermocouple interface chip are connected to the first thermocouple, and the input pins of the platinum resistance temperature detection converter are connected to the platinum resistance. The serial input pins, serial output pins, and serial clock pins of the first thermocouple interface chip and the platinum resistance temperature detection converter are all connected to the IO pins of the control chip; wherein the first thermocouple is used to acquire the temperature inside the coal cup, and the platinum resistance is used to acquire the indoor temperature where the coal cup is located.

3. The circuit for determining the plastic layer as described in claim 2, wherein A first filter capacitor and a second filter capacitor are respectively connected in series between the two input pins of the first thermocouple interface chip and between the two input pins of the platinum resistance temperature detection converter. The two input pins of the first thermocouple interface chip are respectively connected in series with a first current limiting resistor and a second current limiting resistor.

4. The circuit for plasticity layer measurement according to claim 1, wherein The heating circuit includes a silicon carbide rod. The silicon carbide rod is connected to the power supply through a relay. The controlled end of the relay is connected to a relay control circuit. The relay control circuit includes an optocoupler. The anode of the light-emitting diode of the optocoupler is connected to the supply voltage, its cathode is grounded through a first grounding resistor and connected to the IO pin of the control chip through a fifth current limiting resistor. The first end of the phototransistor of the optocoupler is connected to the supply voltage through a thick film resistor, its second end is connected to the controlled end of the relay, and the controlled end of the phototransistor of the optocoupler is grounded through a second grounding resistor.

5. The circuit for plastometer determination according to claim 4, characterized in that, A third filter capacitor is connected in parallel at both ends of the second grounding resistor, and a sixth current limiting resistor is connected in series between the first end and the thick film resistor.

6. The circuit for determining the plastic layer as described in claim 1, characterized in that The displacement measurement circuit includes: a displacement sensor, a voltage dividing branch, and an operational amplifier. The output end of the displacement sensor is connected to one end of the voltage dividing branch. The other end of the voltage dividing branch is grounded. The voltage dividing point of the voltage dividing branch is connected to the non-inverting input terminal of the operational amplifier. The inverting input terminal of the operational amplifier is connected to the output terminal of the operational amplifier through a feedback resistor. The output terminal of the operational amplifier is connected to the IO pin of the control chip.

7. The circuit for determining the plastic layer as described in claim 6, characterized in that, The output end of the operational amplifier is connected to the input end of a first filter circuit, and the output end of the filter circuit is connected to the IO pin of the control chip.

8. The circuit for plasticity layer determination according to claim 7, characterized in that, The output end of the first filter circuit is respectively connected to the anode of a first Schottky diode and the cathode of a second Schottky diode. The cathode of the first Schottky diode is connected to the supply voltage, and the anode of the second Schottky diode is grounded.

9. The circuit for determining the plastic layer as described in any one of claims 1 to 8, characterized in that, The control chip is connected to the host computer through an RS232 communication circuit. The RS232 communication circuit includes an RS232 interface chip. The second transmitter input pin and the second receiver output pin of the RS232 interface chip are connected to the host computer. The second transmitter output pin and the second receiver input pin of the RS232 interface chip are respectively connected to the control chip through a second filter circuit and a third filter circuit.

10. The circuit for plasticity layer measurement according to claim 9, characterized in that, The output ends of the second filter circuit and the third filter circuit are both grounded through bidirectional TVS tubes.

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