Inductance type proximity switch

Abstract

The inductance type proximity switch comprises a tube body, a circuit board, a front plug, a current-limiting resistor R2 and a rectification resistor R1, the circuit board is connected with a wire, the wire is led to the outside of the tube body from the other end of the tube body, the wire comprises a power line and an output line, a control circuit on the circuit board internally comprises a signal input end Vin, and the signal input end Vin is connected with the front plug. A current-limiting resistor R2 in the control circuit is distributed on one side of a signal input end Vin, external voltage passes through the signal input end Vin, current limiting is carried out on the external voltage through the current-limiting resistor R2, then rectification is carried out on the external voltage through a rectification resistor R1 in a circuit board, a wire wrong connection stage is formed, and the external voltage is subjected to current limiting and rectification through the current-limiting resistor R2 and the rectification resistor R1, so that a wire wrong connection stage is formed. According to the utility model, the proximity switch product is prevented from being burnt out due to wrong wiring, that is, if wrong wiring occurs, only the product does not work or does not react, so that the use reliability is ensured, and unnecessary loss caused by the fact that the proximity switch product is burnt out by a user due to wiring is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of proximity switches, in particular to an inductive proximity switch. Background Art

[0002] Inductive proximity switches are a low-cost way to detect metal objects without contact. When a metal object moves toward or away from the proximity switch, the signal automatically changes, thereby achieving the purpose of detection.

[0003] The wiring harness of the inductive proximity switch currently on the market generally includes a power line (usually brown or blue) and an output line (usually black). During the wiring process of the existing inductive proximity switch, if the output line is connected to the power supply as one of the power lines, the inductive proximity switch will burn out.

[0004] At the same time, most existing inductive proximity switches do not have corresponding indications when they are wired for use. That is, except for when metal approaches for sensing, they will react. In other cases, they will not react. As a result, it is impossible to tell from the inductive proximity switch whether the inductive proximity switch is connected incorrectly or whether the switch is faulty or damaged before metal approaches. This leads to inconvenience in the use of the inductive proximity switch product.

[0005] In addition, in the existing inductive proximity switch, during the molding process, after the front plug is inserted into one end of the tube body, the synchronous magnetic core, the fixing seat, and the circuit board are installed and limited in the tube body, and then, in order to ensure the stability of the various structures in the tube body, glue is usually poured into the tube body. After the glue pouring is completed, the rear plug is also correspondingly inserted into the other end of the tube body. However, in actual production, it is found that on the end of the tube body for the rear plug to be inserted, a certain margin for the rear plug to be inserted needs to be left on the end of the tube body after glue pouring, that is, after the glue is poured into the tube body, the glue on the tube body will not be very full, which causes water leakage at the position of the rear plug in some actual use cases. Summary of the Invention

[0006] In view of the above-mentioned deficiencies, the present invention provides an inductive proximity switch which can avoid burning out due to wrong wiring during use and can greatly improve the reliability of use.

[0007] To achieve the above objectives, the present invention adopts an inductive proximity switch, comprising a tube body, a circuit board confined within the tube body, and a front plug plugged into one end of the tube body, wherein the circuit board is connected to a wire, the wire leading out from the other end of the tube body and leading to the outside of the tube body, the wire including a power line and an output line, the circuit board including a control circuit, the control circuit including a signal input terminal Vin, the control circuit further including a current limiting resistor R2 and a rectifier resistor R1, the current limiting resistor R2 in the control circuit being distributed on one side of the signal input terminal Vin;

[0008] The inductive proximity switch is connected to the external power supply via a wire. The external voltage enters the circuit board stage through the signal input terminal Vin. It is first current-limited by the current-limiting resistor R2, and then rectified by the rectifier resistor R1 in the circuit board, forming a wrong wiring stage. The external voltage is limited and rectified by the current-limiting resistor R2 and the rectifier resistor R1, forming a protection against wrong wiring and burning of the proximity switch product.

[0009] The beneficial effect of the above structure is that: by involving the current limiting resistor R2 and the rectifier resistor R1 in the control circuit of the inductive proximity switch, when the inductive proximity switch is in use, if the wire or the output line is mistakenly connected to the power supply as a power line, when the power supply enters the circuit board through the wire, it can first be current-limited by the current limiting resistor, so that the current entering the circuit board will not be too large, thereby avoiding the situation where the inductive proximity switch is burned out. That is, if the inductive proximity switch product involved in the utility model is connected to the wrong wire, the product will only not work or respond, thereby ensuring the reliability of use and avoiding the user's burning of the proximity switch product due to wiring, causing unnecessary losses. In addition, the inductive proximity switch product of the utility model can prepare for the rectification work in the subsequent control circuit through the involvement of the rectifier resistor.

[0010] The utility model is further configured such that the control circuit also includes an overcurrent protection circuit, which includes an output overcurrent sampling resistor R17, a resistor R21, a transistor Q6, a transistor Q7A, a transistor Q7B, a resistor R16, and a capacitor C6. The base of the transistor Q6 is respectively connected to the base of the transistor Q7A and the collector of the transistor Q7B, the emitter of the transistor Q6 is connected to one end of the output overcurrent sampling resistor R17, the emitter of the transistor Q7B is respectively connected to the other end of the output overcurrent sampling resistor R17 and one end of the output overcurrent sampling resistor R21, the collector of the transistor Q7A is connected to air, the emitter of the transistor Q7A is respectively connected to one end of the resistor R16 and one end of the capacitor C6, and the other end of the capacitor C6 is connected to the base of the transistor Q7B.

[0011] Through the above arrangement, when the inductive proximity switch is connected to the load via the output line, if the load current is large, the output overcurrent sampling resistors R17 and R21 operate, and at the same time, their resistances are relatively small, so that when the output overcurrent sampling resistors R17 and R21 operate, a small voltage drop is formed in the control circuit. When the small voltage drop reaches 0.5V, the transistors Q7A and Q7B control the formation of an inhibition voltage in the circuit, and the synchronized transistor Q6 generates a charge and discharge capacitor, thereby raising the base voltage of the transistor Q6. After the increase, there is almost no voltage difference between the base voltage and the emitter of the transistor Q6, and the circuit is not turned on, thereby achieving the circuit shutdown, that is, achieving overcurrent protection for the inductive proximity switch.

[0012] The utility model is further configured such that the proximity switch further comprises a rear plug distributed on the other end of the tube body, wherein the rear plug comprises a tube body inserting portion inserted into the tube body and a transparent exposed portion exposed outside the tube body; the control circuit further comprises an oscillation loop circuit, a voltage stabilizing circuit, a signal light indication circuit, and a light switching circuit; the signal light indication circuit comprises a light emitting diode D6, a diode D7, and a resistor R25; and the light switching circuit comprises a transistor Q2, a transistor Q4, a resistor R12, a light emitting diode D4, and a transistor Q5;

[0013] One end of the light-emitting diode D6 is connected to the voltage stabilizing circuit and to the emitter of the transistor Q2 and the power supply VCC respectively. The other end of the light-emitting diode D6 is connected to one end of the diode D7. The other end of the diode D7 is connected to one end of the resistor R12 and the collector of the transistor Q2 respectively. The other end of the resistor R12 is connected to one end of the light-emitting diode D4. The other end of the light-emitting diode D4 is connected to the base of the transistor Q6. The collector of the transistor Q6 is connected to the base of the transistor Q5. The emitter of the transistor Q5 is connected to the signal output terminal Vout.

[0014] The base of the transistor Q4 is connected to the oscillation loop circuit, so that the induced signal in the oscillation loop circuit is output to the transistor Q4, and the transistor Q4 is turned on. The emitter of the transistor Q2 is connected to the power supply VCC, and the base of the transistor Q2 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the collector of the transistor Q4.

[0015] Through the above arrangement, the tube body plugging portion and the transparent exposed portion are involved on the back plug of the inductive proximity switch. That is, when the back plug is assembled on the tube body through the tube body plugging portion, the transparent exposed portion will be correspondingly exposed outside the tube body. When the inductive proximity switch is in use, the supply voltage is input into the control circuit through the signal input terminal Vin, and is synchronously outputted by the stabilization circuit and input into the light-emitting diode D6, thereby illuminating the light-emitting diode D6, that is, the green light is on.

[0016] When a metal object approaches the inductive proximity switch, the control circuit on the circuit board senses the induction signal output by the oscillation loop circuit, and the signal will reach the transistor Q4 accordingly, that is, the internal conduction of the transistor Q4 is formed. At the same time, the transistor Q2 will also be turned on with the power supply VCC. The specific conduction order is that the transistor Q4 is turned on first, and then the transistor Q2 is turned on. After the synchronous conduction of the transistor Q2, the voltage signal will be transmitted to the diode D7, thereby turning off the green light. After the circuit turns off the green light, the signal passes through the resistor R12 and reaches the light-emitting diode D4, lighting it up. After lighting, the transistors Q5 and Q6 are turned on in sequence through the signal, and the induction signal is output to the outside world through the signal output terminal Vout.

[0017] In addition, the inductive proximity switch involved in the present invention has a dual-light indication function, wherein the green light indicates that the product is powered on and the wiring is normal, and also indicates that it is in standby mode. When a metal object approaches, the red light lights up, indicating that the product has sensed the metal - that is, when the signal is output, the green light turns red, and the dual-light indication function is synchronized. When the wiring is correct, if the light does not light up, it means that the product is in a damaged state, and if the power light of the product is always on (that is, the light does not change when metal approaches), it means that the product has a fault.

[0018] The utility model is further configured such that the proximity switch also includes a rear plug cover, the rear plug also includes an external fitting portion extending in a direction away from the tube body, the transparent external exposed portion is distributed between the external fitting portion and the tube body plug-in portion, the rear plug cover is connected to the rear plug via the external fitting portion of the rear plug, and the wires on the circuit board pass through the rear plug and the rear plug cover in sequence and are then led to the outside of the tube body.

[0019] After the position of the tube body is involved in the rear plug as described above, the rear plug cover is also involved. At the same time, the rear plug and the rear plug cover are connected in an external fitting manner, that is, the rear plug is connected to the rear plug cover through the external fitting portion, so that after the corresponding structure of the inductive proximity switch is installed inside the tube body, the glue tank can be relatively full during the glue filling stage, thereby solving the problem that the existing structure of the inductive proximity switch cannot be filled too full due to the consideration of the subsequent (internal fitting) installation of the rear plug, which leads to water leakage during subsequent use, thereby achieving reliability of use, and the structure of the rear plug and the rear plug cover makes the protection of the inductive proximity switch involved in the utility model reach IP67.

[0020] The utility model is further configured such that the proximity switch further comprises a magnetic core limited within the tube body, the magnetic core is sheathed with a coil, the coil has a parameter ratio of turns of 15:50, and the oscillation circuit comprises a resistor R6, a resistor R7, a resistor R10, a resistor R14, a resistor R18, a resistor R24, a varistor RV1, a capacitor C4, a transistor Q3A, and a transistor Q3B;

[0021] The external voltage via the signal input terminal Vin is connected to an oscillation loop circuit within the control circuit via one end of a rectifier resistor R1. The other end of the rectifier resistor R1 is connected to one end of a resistor R6 and one end of a resistor R7, respectively. The other end of the resistor R6 is connected to the base of the transistor Q3A and the base of the transistor Q3B, respectively. The collector of the transistor Q3A is connected to ground. One end of the capacitor C3 is connected to the emitter of the transistor Q3A, and the other end of the capacitor C3 is connected to the interface CON1. The other end of the resistor R7 is connected to the collector of the transistor Q3B, one end of the capacitor C4, and one end of the resistor R10, respectively. The other end of the resistor R10 is connected to the base of the transistor Q4, forming an oscillation loop circuit that outputs the sensing signal to the light switching circuit.

[0022] The emitter of transistor Q3A is connected to one end of resistor R14 and one end of varistor RV1 respectively. The other end of resistor R14 and the other end of varistor RV1 are connected to one end of resistor R24. The other end of resistor R24 is connected to one end of resistor R18. The other end of resistor R18 is connected to interface CON2.

[0023] By setting the parameter ratio of the number of turns of the coil on the magnetic core to 15:50, it can be applied to environments of -30 degrees Celsius, more than -30 degrees Celsius, or even -40 degrees Celsius. At the same time, the oscillation loop circuit is involved, and the oscillation loop circuit is used in conjunction with the rectifier resistor to achieve temperature compensation. At the same time, by adjusting the coil turns ratio, the inductive proximity switch can be used in environments with lower temperatures compared to the existing general turns ratio of 9:45, thereby expanding its scope of use.

[0024] The utility model is further configured such that the control circuit also includes a power-on signal misjudgment circuit, which includes a resistor R15, a resistor R22, a capacitor C5, and a transistor Q8, one end of the resistor R15 is connected to the power supply voltage VCC, the other end of the resistor R15 is connected to one end of the capacitor C5, the other end of the capacitor C5 and one end of the resistor R22 are commonly connected to the base of the transistor Q8, and the other end of the resistor R22 and the emitter of the transistor Q8 are commonly grounded.

[0025] Through the above arrangement, the control circuit can be used to form a discharge pulse during use through the supply voltage VCC, resistor R15, capacitor C5 and transistor Q8. For example, when there is a spike pulse voltage during the power-on phase, this pulse can be coupled to the base of transistor Q8 through resistor R15, thereby absorbing the pulse. This avoids misjudgment of the action caused by the pulse generated during power-on, thereby further ensuring the reliability of the inductive proximity switch involved in the utility model.

[0026] The utility model is further configured as follows: the voltage stabilizing circuit includes a diode D1, a transient suppression diode D2, a transient suppression diode D3, a resistor R5, and a transistor Q1; the end of the current limiting resistor R2 farther from the signal input terminal Vin is connected to one end of the diode D1; the other end of the diode D1 is respectively connected to one end of the transient suppression diode D2, one end of the resistor R5, and the collector of the transistor Q1; the base of the transistor Q1 and the other end of the resistor R5 are commonly connected to one end of the transient suppression diode D3; the other end of the transient suppression diode D2 and the other end of the transient suppression diode D3 are commonly grounded GND; the emitter of the transistor Q1 is connected to the power supply voltage VCC and outputs a 7.5V voltage to the control circuit via the emitter of the transistor Q1.

[0027] Through the above, the control circuit can be used more reliably. That is, when the power supply voltage is input into the control circuit through the signal input terminal Vin, it is first limited by the current-limiting resistor R2, and then passes through the diode D1, transient suppression diodes D2 and D3, resistor R5, and transistor Q1 to form a simple voltage-regulated power supply. At the same time, a voltage of 7.5V is output to the control circuit through the emitter of transistor Q1. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a three-dimensional schematic diagram of an inductive proximity switch according to a specific embodiment of the present utility model;

[0029] Figure 2 This is a three-dimensional schematic diagram of the inductive proximity switch of a specific embodiment of the utility model after the tube body and the front plug are removed;

[0030] Figure 3This is an exploded schematic diagram of an inductive proximity switch according to a specific embodiment of the present utility model;

[0031] Figure 4 It is a three-dimensional schematic diagram of the rear plug cover of a specific embodiment of the utility model;

[0032] Figure 5 This is a three-dimensional schematic diagram of a rear plug according to a specific embodiment of the present utility model;

[0033] Figure 6 It is a circuit principle diagram of an inductive proximity switch according to a specific embodiment of the utility model. DETAILED DESCRIPTION

[0034] like Figure 1-6 As shown, a specific embodiment of the present invention is an inductive proximity switch, comprising a tube body 2, a circuit board 6 confined within the tube body 2, and a front plug 1 plugged into one end of the tube body 2. A wire 5 is connected to the circuit board 6, which leads from the other end of the tube body 2 to the outside of the tube body 2. The wire 5 includes a power line and an output line. The circuit board 6 includes a control circuit, which includes a signal input terminal Vin, a current limiting resistor R2, and a rectifier resistor R1. The current limiting resistor R2 in the control circuit is distributed on one side of the signal input terminal Vin.

[0035] The inductive proximity switch is connected to the external power supply via the wire 5. The external voltage enters the circuit board 6 stage through the signal input terminal Vin. It is first current-limited by the current-limiting resistor R2 and then rectified by the rectifier resistor R1 in the circuit board 6, forming the wire 5 misconnection stage. The external voltage is current-limited and rectified by the current-limiting resistor R2 and the rectifier resistor R1, forming a protection against misconnection and burning of the proximity switch product.

[0036] By involving the current-limiting resistor R2 and the rectifier resistor R1 in the control circuit of the inductive proximity switch, when the inductive proximity switch is in use, if the wire 5 or the output wire is mistakenly connected to the power supply as a power line, when the power supply enters the circuit board 6 through the wire 5, it can first be current-limited by the current-limiting resistor, so that the current entering the circuit board 6 will not be too large, thereby avoiding the situation where the inductive proximity switch is burned out. That is, if the inductive proximity switch product involved in the utility model is connected to the wrong wire, the product will only fail to work or respond. In addition, the inductive proximity switch product of the utility model can prepare for the rectification work in the subsequent control circuit through the involvement of the rectifier resistor.

[0037] like Figure 6As shown, the control circuit also includes an overcurrent protection circuit C, which includes an output overcurrent sampling resistor R17, a resistor R21, a transistor Q6, a transistor Q7A, a transistor Q7B, a resistor R16, and a capacitor C6. The base of the transistor Q6 is connected to the base of the transistor Q7A and the collector of the transistor Q7B, respectively. The emitter of the transistor Q6 is connected to one end of the output overcurrent sampling resistor R17, the emitter of the transistor Q7B is connected to the other end of the output overcurrent sampling resistor R17 and one end of the output overcurrent sampling resistor R21, respectively. The collector of the transistor Q7A is connected to air, the emitter of the transistor Q7A is connected to one end of the resistor R16 and one end of the capacitor C6, respectively, and the other end of the capacitor C6 is connected to the base of the transistor Q7B.

[0038] like Figure 1-3 As shown in Figures 5-6, the proximity switch further includes a rear plug 3 distributed on the other end of the tube body 2, and the rear plug 3 includes a tube body plugging portion 31 plugged into the tube body 2 and a transparent outer exposed portion 32 exposed outside the tube body 2. The control circuit further includes an oscillation loop circuit a, a voltage stabilizing circuit d, a signal light indication circuit e, and a light switching circuit f. The signal light indication circuit e includes a light-emitting diode D6, a diode D7, and a resistor R25. The light switching circuit f includes a transistor Q2, a transistor Q4, a resistor R12, a light-emitting diode D4, and a transistor Q5.

[0039] One end of a light-emitting diode D6 is connected to a voltage stabilizing circuit d, and is connected to the emitter of the transistor Q2 and the power supply VCC, respectively. The other end of the light-emitting diode D6 is connected to one end of a diode D7, the other end of the diode D7 is connected to one end of a resistor R12 and the collector of the transistor Q2, respectively. The other end of the resistor R12 is connected to one end of a light-emitting diode D4, the other end of the light-emitting diode D4 is connected to the base of the transistor Q6, the collector of the transistor Q6 is connected to the base of the transistor Q5, and the emitter of the transistor Q5 is connected to the signal output terminal Vout.

[0040] The base of transistor Q4 is connected to the oscillation loop circuit a, so that the induced signal in the oscillation loop circuit a is output to the transistor Q4 and the transistor Q4 is turned on. The emitter of transistor Q2 is connected to the power supply VCC, and the base of transistor Q2 is connected to one end of resistor R8, and the other end of resistor R8 is connected to the collector of transistor Q4.

[0041] like Figure 1-5 As shown, the proximity switch also includes a rear plug cover 4, and the rear plug 3 also includes an outer fitting portion 33 extending away from the tube body 2. The transparent outer exposed portion 32 is distributed between the outer fitting portion 33 and the tube body plug-in portion 31. The rear plug cover 4 is connected to the rear plug 3 via the outer fitting portion 33 of the rear plug 3. The wires 5 on the circuit board 6 pass through the rear plug 3 and the rear plug cover 4 in sequence, and are then led to the outside of the tube body 2.

[0042] like Figure 1-6 As shown, the proximity switch also includes a magnetic core 7 limited in the tube body 2, the magnetic core 7 is sheathed with a coil 8, the parameter ratio of the number of turns of the coil 8 is 15:50, and the oscillation circuit a includes a resistor R6, a resistor R7, a resistor R10, a resistor R14, a resistor R18, a resistor R24, a varistor RV1, a capacitor C4, a transistor Q3A, and a transistor Q3B;

[0043] The external voltage via the signal input terminal Vin is connected to an oscillation loop circuit a within the control circuit via one end of a rectifier resistor R1. The other end of the rectifier resistor R1 is connected to one end of a resistor R6 and one end of a resistor R7, respectively. The other end of the resistor R6 is connected to the base of transistor Q3A and the base of transistor Q3B, respectively. The collector of transistor Q3A is connected to ground. One end of capacitor C3 is connected to the emitter of transistor Q3A, and the other end of capacitor C3 is connected to interface CON1. The other end of resistor R7 is connected to the collector of transistor Q3B, one end of capacitor C4, and one end of resistor R10, respectively. The other end of resistor R10 is connected to the base of transistor Q4, forming an oscillation loop circuit a, which outputs the induced signal to the light switching circuit f.

[0044] The emitter of transistor Q3A is connected to one end of resistor R14 and one end of varistor RV1 respectively. The other end of resistor R14 and the other end of varistor RV1 are connected to one end of resistor R24. The other end of resistor R24 is connected to one end of resistor R18. The other end of resistor R18 is connected to interface CON2.

[0045] like Figure 6 As shown, the control circuit also includes a power-on signal misjudgment circuit b, which includes a resistor R15, a resistor R22, a capacitor C5, and a transistor Q8. One end of the resistor R15 is connected to the power supply voltage VCC, the other end of the resistor R15 is connected to one end of the capacitor C5, the other end of the capacitor C5 and one end of the resistor R22 are commonly connected to the base of the transistor Q8, and the other end of the resistor R22 and the emitter of the transistor Q8 are commonly grounded.

[0046] like Figure 6As shown, the voltage stabilizing circuit d includes a diode D1, a transient suppressor diode D2, a transient suppressor diode D3, a resistor R5, and a transistor Q1. The end of the current-limiting resistor R2 farther from the signal input terminal Vin is connected to one end of the diode D1. The other end of the diode D1 is connected to one end of the transient suppressor diode D2, one end of the resistor R5, and the collector of the transistor Q1, respectively. The base of the transistor Q1 and the other end of the resistor R5 are commonly connected to one end of the transient suppressor diode D3. The other end of the transient suppressor diode D2 and the other end of the transient suppressor diode D3 are commonly grounded GND. The emitter of the transistor Q1 is connected to the power supply voltage VCC and outputs a 7.5V voltage to the control circuit via the emitter of the transistor Q1.

Claims

1. An inductive proximity switch comprising a tube, a circuit board confined within the tube, and a front plug inserted into one end of the tube. The circuit board is connected to wires extending from the other end of the tube and extending to the outside of the tube. The wires include power lines and output lines. The circuit board includes a control circuit, which includes a signal input terminal Vin. The switch is characterized by: The control circuit further includes a current limiting resistor R2 and a rectifier resistor R1. The current limiting resistor R2 in the control circuit is distributed on one side of the signal input terminal Vin; The inductive proximity switch is connected to the external power supply via a wire. The external voltage enters the circuit board stage through the signal input terminal Vin. It is first current-limited by the current-limiting resistor R2, and then rectified by the rectifier resistor R1 in the circuit board, forming a wrong wiring stage. The external voltage is limited and rectified by the current-limiting resistor R2 and the rectifier resistor R1, forming a protection against wrong wiring and burning of the proximity switch product.

2. The inductive proximity switch according to claim 1, characterized in that: The control circuit also includes an overcurrent protection circuit, which includes an output overcurrent sampling resistor R17, a resistor R21, a transistor Q6, a transistor Q7A, a transistor Q7B, a resistor R16, and a capacitor C6. The base of the transistor Q6 is connected to the base of the transistor Q7A and the collector of the transistor Q7B, respectively. The emitter of the transistor Q6 is connected to one end of the output overcurrent sampling resistor R17, the emitter of the transistor Q7B is connected to the other end of the output overcurrent sampling resistor R17 and one end of the output overcurrent sampling resistor R21, respectively. The collector of the transistor Q7A is connected to air, the emitter of the transistor Q7A is connected to one end of the resistor R16 and one end of the capacitor C6, respectively, and the other end of the capacitor C6 is connected to the base of the transistor Q7B.

3. The inductive proximity switch according to claim 2, wherein: The proximity switch further includes a rear plug disposed on the other end of the tube body, wherein the rear plug includes a tube body insertion portion inserted into the tube body and a transparent exposed portion exposed outside the tube body. The control circuit further includes an oscillation circuit, a voltage stabilization circuit, a signal light indication circuit, and a light switching circuit. The signal light indication circuit includes a light-emitting diode D6, a diode D7, and a resistor R25. The light switching circuit includes a transistor Q2, a transistor Q4, a resistor R12, a light-emitting diode D4, and a transistor Q5. One end of the light-emitting diode D6 is connected to the voltage stabilizing circuit and to the emitter of the transistor Q2 and the power supply VCC respectively. The other end of the light-emitting diode D6 is connected to one end of the diode D7. The other end of the diode D7 is connected to one end of the resistor R12 and the collector of the transistor Q2 respectively. The other end of the resistor R12 is connected to one end of the light-emitting diode D4. The other end of the light-emitting diode D4 is connected to the base of the transistor Q6. The collector of the transistor Q6 is connected to the base of the transistor Q5. The emitter of the transistor Q5 is connected to the signal output terminal Vout. The base of the transistor Q4 is connected to the oscillation loop circuit, so that the induced signal in the oscillation loop circuit is output to the transistor Q4, and the transistor Q4 is turned on. The emitter of the transistor Q2 is connected to the power supply VCC, and the base of the transistor Q2 is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the collector of the transistor Q4.

4. The inductive proximity switch according to claim 3, wherein: The proximity switch also includes a rear plug cover, and the rear plug also includes an external fitting portion extending away from the tube body. The transparent external exposed portion is distributed between the external fitting portion and the tube body insertion portion. The rear plug cover is connected to the rear plug via the external fitting portion of the rear plug. The wires on the circuit board pass through the rear plug and the rear plug cover in sequence and are then led to the outside of the tube body.

5. The inductive proximity switch according to claim 3 or 4, characterized in that: The proximity switch also includes a magnetic core limited in the tube body, the magnetic core is provided with a coil, the coil has a parameter ratio of turns of 15:50, and the oscillation circuit includes resistors R6, R7, R10, R14, R18, R24, varistor RV1, capacitor C4, transistor Q3A, and transistor Q3B; The external voltage via the signal input terminal Vin is connected to an oscillation loop circuit within the control circuit via one end of a rectifier resistor R1. The other end of the rectifier resistor R1 is connected to one end of a resistor R6 and one end of a resistor R7, respectively. The other end of the resistor R6 is connected to the base of the transistor Q3A and the base of the transistor Q3B, respectively. The collector of the transistor Q3A is connected to ground. One end of the capacitor C3 is connected to the emitter of the transistor Q3A, and the other end of the capacitor C3 is connected to the interface CON1. The other end of the resistor R7 is connected to the collector of the transistor Q3B, one end of the capacitor C4, and one end of the resistor R10, respectively. The other end of the resistor R10 is connected to the base of the transistor Q4, forming an oscillation loop circuit that outputs the sensing signal to the light switching circuit. The emitter of transistor Q3A is connected to one end of resistor R14 and one end of varistor RV1 respectively. The other end of resistor R14 and the other end of varistor RV1 are connected to one end of resistor R24. The other end of resistor R24 is connected to one end of resistor R18. The other end of resistor R18 is connected to interface CON2.

6. The inductive proximity switch according to claim 2, 3 or 4, characterized in that: The control circuit also includes a power-on signal misjudgment circuit, which includes a resistor R15, a resistor R22, a capacitor C5, and a transistor Q8. One end of the resistor R15 is connected to the power supply voltage VCC, the other end of the resistor R15 is connected to one end of the capacitor C5, the other end of the capacitor C5 and one end of the resistor R22 are connected to the base of the transistor Q8, and the other end of the resistor R22 and the emitter of the transistor Q8 are grounded together.

7. The inductive proximity switch according to claim 3 or 4, characterized in that: The voltage stabilizing circuit includes a diode D1, a transient suppression diode D2, a transient suppression diode D3, a resistor R5, and a transistor Q1. The end of the current-limiting resistor R2 farther from the signal input terminal Vin is connected to one end of the diode D1. The other end of the diode D1 is respectively connected to one end of the transient suppression diode D2, one end of the resistor R5, and the collector of the transistor Q1. The base of the transistor Q1 and the other end of the resistor R5 are commonly connected to one end of the transient suppression diode D3. The other ends of the transient suppression diode D2 and the other ends of the transient suppression diode D3 are commonly grounded to GND. The emitter of the transistor Q1 is connected to the power supply voltage VCC and outputs a 7.5V voltage to the control circuit via the emitter of the transistor Q1.

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