Photoelectric sensor and driving circuit thereof

Abstract

The utility model discloses a photoelectric sensor and a driving circuit thereof, the driving circuit comprises a voltage conversion module, a signal filtering module, a switch module, a first protection module and a second protection module, the voltage conversion module converts a first voltage and then outputs a second voltage; the signal filtering module filters the first control signal and then outputs a second control signal; the switch module is in a conducting state according to the second control signal, so that the light-emitting diode is lightened; the first protection module turns off the switch module when the current flowing through the switch module exceeds a current preset value; and the second protection module turns off the switch module when the temperature exceeds a temperature preset value. According to the technical scheme, through cooperative work of a plurality of modules, stable voltage conversion, signal control and light emitting diode driving functions are realized, safe and reliable operation of the circuit is ensured through an over-current and over-temperature protection mechanism, the anti-interference capability and stability of the circuit are improved, and long-term use safety of equipment is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of photoelectric sensors, in particular to a photoelectric sensor and a driving circuit thereof. Background Art

[0002] Traditional device interface circuits often rely on a single signal conversion method, lacking effective protection against overcurrent and overvoltage. These circuits are susceptible to voltage fluctuations and load variations in complex operating environments, leading to device damage. Furthermore, due to the limited operating voltage range and insufficient load capacity of these devices, many circuits fail to operate stably under high loads, limiting their application and reliability. In high-power or industrial environments, traditional circuits struggle to meet the demands for higher currents and voltages, and lack effective protection mechanisms to prevent failures caused by transient overcurrent or overvoltage. Utility Model Content

[0003] The embodiments of the present invention provide a photoelectric sensor and a driving circuit thereof to solve the above technical problems.

[0004] A first aspect of an embodiment of the present invention provides a driving circuit for a photoelectric sensor, comprising:

[0005] a voltage conversion module, wherein an input terminal of the voltage conversion module receives a first voltage and converts the first voltage to output a second voltage;

[0006] a signal filtering module, wherein a voltage input terminal of the signal filtering module is connected to the output terminal of the voltage conversion module, and the input terminal of the signal filtering module receives a first control signal, filters the first control signal, and then outputs a second control signal;

[0007] a switch module, one end of which is connected to a light-emitting diode, and a control end of which is connected to the output end of the signal filtering module, so as to be in a conducting state according to the second control signal, thereby lighting up the light-emitting diode;

[0008] a first protection module, wherein a first end of the first protection module is connected to the other end of the switch module, a second end of the first protection module is connected to the control end of the switch module, and a third end of the first protection module is grounded, so as to shut down the switch module when the current flowing through the switch module exceeds a preset current value;

[0009] A second protection module, wherein a first end of the second protection module receives the first voltage, a second end of the second protection module is connected to the control end of the switch module, and a third end of the second protection module is grounded to turn off the switch module when the temperature exceeds a preset temperature value.

[0010] Optionally, the voltage conversion module includes a first capacitor, a second capacitor, a tenth resistor, a twelfth resistor, a fifth transistor and a sixth voltage regulator diode;

[0011] One end of the first capacitor, one end of the tenth resistor and the collector of the fifth transistor are commonly connected as the input end of the voltage conversion module, the other end of the tenth resistor is respectively connected to the base of the fifth transistor and the cathode of the sixth voltage-stabilizing diode, the emitter of the fifth transistor, one end of the second capacitor and one end of the twelfth resistor are commonly connected as the output end of the voltage conversion module, the other end of the first capacitor, the anode of the sixth voltage-stabilizing diode, the other end of the second capacitor and the other end of the twelfth resistor are commonly connected to the ground.

[0012] Optionally, the signal filtering module includes a first transistor, a second resistor, a third resistor, a sixth resistor and a fifth diode;

[0013] One end of the second resistor and the emitter of the first transistor are connected together as the voltage input end of the signal filtering module, the other end of the second resistor is respectively connected to the anode of the fifth diode and one end of the third resistor, the cathode of the fifth diode is the input end of the signal filtering module, the other end of the third resistor is connected to the base of the first transistor, the collector of the first transistor and one end of the sixth resistor are connected together as the output end of the signal filtering module, and the other end of the sixth resistor is grounded.

[0014] Optionally, the switch module is a second transistor, the collector of the second transistor is one end of the switch module, the base of the second transistor is the control end of the switch module, and the emitter of the second transistor is the other end of the switch module.

[0015] Optionally, the first protection module includes a seventh resistor, a ninth resistor and a fourth transistor;

[0016] One end of the seventh resistor and one end of the ninth resistor are connected to the first end of the first protection module, the other end of the seventh resistor is connected to the base of the fourth transistor, the collector of the fourth transistor is the second end of the first protection module, and the emitter of the fourth transistor and the other end of the ninth resistor are connected to the ground.

[0017] Optionally, the second protection module includes a fifth resistor, an eighth resistor and a third transistor;

[0018] One end of the fifth resistor is the first end of the second protection module, the other end of the fifth resistor is respectively connected to the base of the third transistor and one end of the eighth resistor, and the emitter of the third transistor and the other end of the eighth resistor are commonly connected to the ground.

[0019] Optionally, the switch module further includes a fourth resistor, one end of the fourth resistor is the control end of the switch module, and the other end of the fourth resistor is connected to the base of the second transistor.

[0020] Optionally, the collector of the second triode is connected to the cathode of the third diode and the cathode of the fourth voltage regulator tube respectively, the anode of the third diode inputs a control signal, and the anode of the fourth voltage regulator tube is grounded.

[0021] Optionally, the cathode of the light-emitting diode is connected to the collector of the second transistor, the anode of the light-emitting diode is connected to one end of the first resistor, the other end of the first resistor is connected to the cathode of the first diode and receives a first voltage, the anode of the first diode is connected to one end of the fuse, and the other end of the fuse receives a third voltage.

[0022] A second aspect of an embodiment of the present invention provides a photoelectric sensor, comprising: the driving circuit and light-emitting diode described in the first aspect.

[0023] The technical effect of the embodiment of the utility model is: the driving circuit realizes stable voltage conversion, signal control and light-emitting diode driving functions through the coordinated work of multiple modules, expands the voltage range of the driving circuit, and ensures that the driving circuit can operate safely and reliably through overcurrent and overtemperature protection mechanisms, which not only improves the anti-interference ability and stability of the driving circuit, but also ensures the long-term safety of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] Figure 1 This is a schematic structural diagram of a driving circuit of a photoelectric sensor provided in Example 1 of the present utility model;

[0026] Figure 2 This is a circuit diagram of a voltage conversion module in a driving circuit of a photoelectric sensor provided in the first embodiment of the present utility model;

[0027] Figure 3 This is a circuit diagram of a signal filtering module in a driving circuit of a photoelectric sensor provided in the first embodiment of the present utility model;

[0028] Figure 4This is a circuit diagram showing connections between a switch module, a first protection module, a second protection module, and a light-emitting diode in a driving circuit of a photoelectric sensor provided in Example 1 of the present utility model;

[0029] In the figure: 10, driving circuit; 20, light-emitting diode; 101, voltage conversion module; 102, signal filtering module; 103, switch module; 104, first protection module; 105, second protection module. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] It should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0032] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part.

[0033] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein for convenience of description to describe the relationship of one element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the drawings is flipped, then the elements or features described as "under" or "beneath" or "beneath" the other elements will be oriented as "over" the other elements or features. Thus, the exemplary terms "under" and "under" may include both the upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0034] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present invention. When used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0035] In order to fully understand the present invention, the following description will provide detailed structures and steps to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention may also have other implementation methods.

[0036] Example 1

[0037] The first embodiment of the present invention provides a driving circuit for a photoelectric sensor, such as Figure 1 As shown, including:

[0038] A voltage conversion module 101 , wherein an input terminal of the voltage conversion module 101 receives a first voltage V1 and converts the first voltage to output a second voltage V2 ;

[0039] A signal filtering module 102, wherein a voltage input terminal of the signal filtering module 102 is connected to an output terminal of the voltage conversion module 101, and the input terminal of the signal filtering module 102 receives a first control signal K1, filters the first control signal, and outputs a second control signal K2;

[0040] A switch module 103, one end of the switch module 103 is connected to the light-emitting diode 20, and a control end of the switch module 103 is connected to the output end of the signal filtering module 102, so as to be in a conducting state according to the second control signal, thereby lighting up the light-emitting diode 20;

[0041] a first protection module 104, wherein a first end of the first protection module 104 is connected to the other end of the switch module 103, a second end of the first protection module 104 is connected to the control end of the switch module 103, and a third end of the first protection module 104 is grounded, so as to shut down the switch module 103 when the current flowing through the switch module 103 exceeds a preset current value;

[0042] The second protection module 105 has a first terminal receiving a first voltage, a second terminal connected to a control terminal of the switch module 103, and a third terminal connected to the ground, so as to turn off the switch module 103 when the temperature exceeds a preset temperature value.

[0043] The voltage conversion module 101 converts the input first voltage V1 into a second voltage V2 suitable for use by subsequent circuits. The input of the voltage conversion module 101 receives a higher first voltage V1 (e.g., 24V) and, through a voltage conversion process, converts it into a lower second voltage V2 (e.g., 6V or 12V) to power the subsequent circuits. The signal filtering module 102 receives the first control signal K1, filters it, removes high-frequency noise or other interference, and outputs a more stable second control signal K2, which is supplied to the switch module 103. The switch module 103 controls the on / off of the light-emitting diode (LED) 20 based on the state of the second control signal. When the second control signal K2 output by the signal filtering module 102 is at a high level, the switch module 103 turns on, allowing current to flow through the LED 20, causing it to illuminate. When the second control signal K2 is at a low level, the switch module 103 turns off, turning the LED 20 off. The first protection module 104 provides overcurrent protection when the current exceeds a preset value, preventing damage to the switch module 103. The first protection module 104 monitors the current flowing through the switch module 103. When the current exceeds a set safety threshold, the first protection module 104 triggers the shutoff switch module 103, stopping the flow of current to protect the circuit components. The second protection module 105 provides overtemperature protection when the circuit temperature exceeds a preset value, preventing overheating and damage to the circuit. The second protection module 105 monitors the circuit temperature in real time. When it detects that the temperature exceeds the set safety threshold, it triggers the shutoff switch module 103, stopping the flow of current to prevent overheating.

[0044] The technical effect of the technical solution provided in the first embodiment is that: by introducing an overcurrent protection module and an overtemperature protection module, the drive circuit ensures safety under abnormal current and temperature conditions, effectively prevents equipment damage, and solves the problem of the lack of protection mechanism in the interface circuit of traditional equipment. By filtering the input signal with noise and interference through the signal filtering module, the circuit operates more stably, reduces the risk of misoperation in complex environments, and improves the reliability of the equipment. The voltage conversion module expands the voltage adaptability of the circuit, enhances the applicability of the equipment in different voltage environments, and is suitable for a wider range of industrial and high-power application scenarios, overcoming the shortcomings of the limited operating voltage range of traditional circuits. The drive circuit realizes stable voltage conversion, signal control, and load driving functions through the coordinated operation of multiple modules, and ensures the safe and reliable operation of the circuit through overcurrent and overtemperature protection mechanisms, which not only improves the anti-interference ability and stability of the circuit, but also ensures the long-term safety of the equipment.

[0045] As an implementation method, Figure 2 As shown, the voltage conversion module 101 includes a first capacitor C1, a second capacitor C2, a tenth resistor R10, a twelfth resistor R12, a fifth transistor Q5 and a sixth voltage regulator D6;

[0046] One end of the first capacitor C1, one end of the tenth resistor R10, and the collector of the fifth transistor Q5 are commonly connected to the input end of the voltage conversion module 101. The other end of the tenth resistor R10 is respectively connected to the base of the fifth transistor Q5 and the cathode of the sixth voltage-stabilizing diode D6. The emitter of the fifth transistor Q5, one end of the second capacitor C2, and one end of the twelfth resistor R12 are commonly connected to the output end of the voltage conversion module 101. The other end of the first capacitor C1, the anode of the sixth voltage-stabilizing diode D6, the other end of the second capacitor C2, and the other end of the twelfth resistor R12 are commonly connected to ground.

[0047] The voltage conversion module 101 achieves step-down conversion from 24V to 6V through the coordinated operation of various modules. The first capacitor C1 and the second capacitor C2 are used for filtering and voltage stabilization. The first capacitor C1 acts as a filter, filtering high-frequency noise in the input voltage to ensure a stable voltage input. The second capacitor C2 is used to smooth the output voltage and prevent output voltage fluctuations. The tenth resistor R10 and the twelfth resistor R12 control the current to prevent excessive current from damaging the circuit. The tenth resistor R10 limits the current through the sixth voltage regulator D6 and the base of the fifth transistor Q5; the twelfth resistor R12 is located at the output end, limiting the output current and protecting subsequent circuits. The fifth transistor Q5 serves as the main voltage conversion element and provides a conduction function. The base potential of the fifth transistor Q5 is maintained at 6V by the sixth voltage regulator D6. When the fifth transistor Q5 is turned on, the emitter outputs a stable voltage of 6V to power the subsequent circuits. The sixth voltage-stabilizing diode D6 controls the base voltage of the fifth transistor Q5, ensuring a stable output voltage. The sixth voltage-stabilizing diode D6 stabilizes the base potential of the fifth transistor Q5 at 6V. When the input voltage is high, the sixth voltage-stabilizing diode D6 maintains a constant base voltage at the fifth transistor Q5, allowing the fifth transistor Q5 to conduct stably and output a 6V voltage.

[0048] The technical effect of this embodiment is that the power drive circuit converts a 24V input voltage into a 6V output voltage through the conduction of the fifth transistor Q5 and the voltage stabilization of the sixth voltage regulator D6. Furthermore, the circuit is protected by current-limiting resistors such as the tenth resistor R10 and the twelfth resistor R12, ensuring stable and efficient operation. Simultaneously, the use of the first capacitor C1 and the second capacitor C2 achieves input and output voltage stability. This entire design not only reduces the power consumption of the circuit but also replaces the more expensive power supply chip, significantly reducing manufacturing costs and achieving good economic benefits and stability.

[0049] In addition to the above structure, the voltage conversion module 101 includes but is not limited to the following structures:

[0050] Voltage regulator: A three-terminal linear voltage regulator chip is used to replace the combination of Zener diode and transistor.

[0051] Buck switching regulator: A buck switching regulator circuit is formed by combining a switching tube (such as MOSFET), a diode, an inductor and a capacitor, and uses pulse width modulation (PWM) technology to achieve efficient voltage conversion.

[0052] Zener diode and resistor voltage divider structure: Zener diode and resistor voltage divider circuit is used to replace the combination of voltage regulator tube and transistor.

[0053] Adjustable voltage divider circuit: A voltage divider circuit composed of a variable resistor and a fixed resistor, combined with a voltage regulator diode or a transistor to achieve voltage conversion.

[0054] LDO low-dropout linear regulator: LDO voltage regulator chip is used to achieve a small difference conversion between input voltage and output voltage.

[0055] As an implementation method, Figure 3 As shown, the signal filtering module 102 includes a first transistor Q1, a second resistor R2, a third resistor R3, a sixth resistor R6 and a fifth diode Q5; one end of the second resistor R2 and the emitter of the first transistor Q1 are connected together as the voltage input end of the signal filtering module 102, the other end of the second resistor R2 is connected to the anode of the fifth diode Q5 and one end of the third resistor R3 respectively, the cathode of the fifth diode Q5 is the input end of the signal filtering module 102, the other end of the third resistor R3 is connected to the base of the first transistor Q1, the collector of the first transistor Q1 and one end of the sixth resistor R6 are connected together as the output end of the signal filtering module 102, and the other end of the sixth resistor R6 is grounded.

[0056] The first transistor Q1 acts as a switching element, controlling the circuit's on / off state based on the input signal. When the input signal is low, the base voltage of the first transistor Q1 drops, turning on the first transistor Q1. Current flows through the first transistor Q1, generating a high-level signal Vc at the output. Conversely, when the input signal is floating or high, the first transistor Q1 is turned off, and the circuit is in the off state. The second resistor R2 is used to pull the input voltage to a high level when the circuit is not operating, preventing signal instability when the input is floating. When the input IN is floating, the second resistor R2 ensures that the input voltage remains high by connecting it to the power supply voltage, thereby keeping the first transistor Q1 in the off state. The third resistor R3 limits the current flowing into the base of the first transistor Q1, protecting the first transistor Q1 and ensuring proper conduction. When the input signal is low, the third resistor R3 limits the current flowing into the base of the first transistor Q1, ensuring that the base current of the first transistor Q1 is within a safe range, thereby preventing overcurrent damage to the first transistor Q1. The sixth resistor R6 controls the current through the collector of the first transistor Q1, ensuring the stability of the Vc output signal. When the first transistor Q1 is turned on, current flows from the collector of the first transistor Q1 to ground. The sixth resistor R6 acts as a current-limiting resistor, ensuring a moderate current flow and preventing excessive current from damaging the high-level signal at the output.

[0057] The technical benefits of this embodiment are as follows: the signal filtering module ensures reliable circuit operation in complex environments through precise signal transmission and effective filtering. Multiple current-limiting resistors protect circuit components from overcurrent damage, extending the circuit's service life. Furthermore, the circuit achieves high anti-interference capabilities, stability, and reliability through a simple design.

[0058] It should be noted that, in addition to the above-mentioned structure, the signal filtering module 102 includes but is not limited to the following structures: RC low-pass filter, LC filter circuit, active filter composed of operational amplifier, digital filter, capacitor DC blocking circuit, Schottky diode clamping circuit, optocoupler isolation circuit, etc.

[0059] As an implementation method, Figure 4 As shown, the switch module 103 is a second transistor Q2 , the collector of the second transistor Q2 is one end of the switch module 103 , the base of the second transistor Q2 is the control end of the switch module 103 , and the emitter of the second transistor Q2 is the other end of the switch module 103 .

[0060] The second transistor Q2 primarily controls the on / off switching of the light-emitting diode (LED) 20. When the base of the second transistor Q2 receives a second control signal from the signal filtering module 102, the second transistor Q2 enters the on state, allowing current to flow from the collector to the emitter, thereby illuminating the LED 20. When the control signal is inactive or at a low level, the second transistor Q2 turns off, and the LED 20 turns off.

[0061] As an implementation method, Figure 4 As shown, the first protection module 104 includes a seventh resistor R7, a ninth resistor R9, and a fourth transistor Q4; one end of the seventh resistor R7 and one end of the ninth resistor R9 are commonly connected to form a first end of the first protection module 104, the other end of the seventh resistor R7 is connected to the base of the fourth transistor Q4, the collector of the fourth transistor Q4 is the second end of the first protection module 104, and the emitter of the fourth transistor Q4 and the other end of the ninth resistor R9 are commonly connected to ground.

[0062] As the output branch current increases, the voltage across the ninth resistor R9 increases, and part of this voltage is applied to the base of the fourth transistor Q4 through the seventh resistor R7. When the base voltage of the fourth transistor Q4 reaches its conduction threshold, the fourth transistor Q4 turns on, triggering the overcurrent protection circuit. The ninth resistor R9 detects the current in the output branch and provides a feedback signal for the overcurrent protection circuit through the voltage drop across it. As the output branch current increases, the current flowing through the ninth resistor R9 increases, and according to Ohm's law, the voltage across the ninth resistor R9 also increases. This gradually increasing voltage affects the voltage across the seventh resistor R7, causing the fourth transistor Q4 to turn on. The fourth transistor Q4 is the core component of the overcurrent protection circuit. When the current exceeds the set threshold, the negative feedback loop reduces the base potential of the second transistor Q2, causing it to gradually turn off, thereby limiting the excessive current. The second transistor Q2 controls the on / off state of the light-emitting diode D2. When the high-level Vc signal from the front stage triggers the second transistor Q2 to turn on, the second transistor Q2 allows current to pass through, lighting up the light-emitting diode D2.

[0063] The technical effect of this embodiment is that: through the ninth resistor R9 detecting the current, the seventh resistor R7 adjusting the base voltage, and the negative feedback loop of the fourth transistor Q4, the first protection module can respond to the increase in current in a timely manner, triggering the base potential of the second transistor Q2 to drop, thereby limiting the output current and achieving the effect of overcurrent protection.

[0064] It should be noted that, in addition to the above structures, the first protection module 104 includes but is not limited to the following structures: a MOSFET protection circuit, a current detection amplifier protection circuit, a Zener diode and current limiting circuit, a Hall effect sensor protection circuit, and the like.

[0065] As an implementation method, Figure 4 As shown, the second protection module 105 includes a fifth resistor R5, an eighth resistor R8 and a third transistor Q3; one end of the fifth resistor R5 is the first end of the second protection module 105, and the other end of the fifth resistor R5 is respectively connected to the base of the third transistor Q3 and one end of the eighth resistor R8, and the emitter of the third transistor Q3 and the other end of the eighth resistor R8 are commonly connected to the ground.

[0066] Among them, the fifth resistor R5 is usually a thermistor, which is used to detect temperature changes in the circuit. When the current increases, causing the heat generated by the second transistor Q2 to rise, the resistance of the thermistor R5 changes, thereby affecting the base voltage of the third transistor Q3. As the temperature rises, the resistance of the thermistor R5 decreases (a characteristic of NTC thermistors), and the base voltage gradually increases. When the temperature exceeds the set threshold, the thermistor R5 will provide sufficient voltage to the base of the third transistor Q3, causing it to turn on. The eighth resistor R8 acts as a current-limiting resistor, limiting the current flowing to the base of the third transistor Q3 to ensure that the third transistor Q3 will not be damaged by overcurrent when it is turned on and to maintain a stable control current. When the thermistor R5 detects a temperature increase and provides voltage, the eighth resistor R8 will limit the current flowing to the base of the third transistor Q3, ensuring that the current of the third transistor Q3 is stable when it is turned on, thereby smoothly performing the temperature protection function. The third transistor Q3 is the core component of the temperature protection circuit. Its main function is to turn on when the temperature is too high, reducing the base voltage of the second transistor Q2 through a feedback loop, thus providing protection. When thermistor R5 senses that the temperature is too high, the base voltage rises to the threshold that causes the third transistor Q3 to turn on. Once the third transistor Q3 turns on, it lowers the base potential of the second transistor Q2, gradually lowering it to the point where the second transistor Q2 turns off, thereby reducing the current flowing through the second transistor Q2 and preventing damage due to excessive temperature.

[0067] The technical effect of this embodiment is that thermistor R5 detects temperature changes and the third transistor Q3 regulates the base voltage of the second transistor Q2, forming an overtemperature protection mechanism. When the temperature exceeds a set threshold, the circuit automatically reduces the base voltage of the second transistor Q2, limiting the flow of current and ensuring that the second transistor Q2 is not damaged by overheating.

[0068] This circuit provides dual protection: both overcurrent protection and overtemperature protection, significantly enhancing circuit safety and reliability. This design prevents malfunctions or damage caused by excessive current or temperature when operating in complex environments, extending the life of circuit components.

[0069] It should be noted that, in addition to the above-mentioned structure, the second protection module 105 includes but is not limited to the following structures: a thermal relay protection circuit, an NTC / PTC thermistor and op amp circuit combination circuit, a Hall effect temperature sensor, an integrated thermal shutdown power management IC, a temperature control circuit and a PWM modulation circuit, etc.

[0070] Furthermore, the switch module 103 further includes a fourth resistor R4 , one end of the fourth resistor R4 is a control end of the switch module 103 , and the other end of the fourth resistor R4 is connected to the base of the second transistor Q2 .

[0071] The fourth resistor R4 is used to limit the current transmitted from the control terminal to the base of the second transistor Q2, ensuring that the base current of the second transistor Q2 is not too large, thereby avoiding damaging the transistor or causing excessive power consumption.

[0072] Furthermore, the collector of the second triode Q2 is connected to the cathode of the third diode D3 and the cathode of the fourth voltage-stabilizing tube D4 respectively, the anode of the third diode D3 inputs the control signal, and the anode of the fourth voltage-stabilizing tube D4 is grounded.

[0073] The third diode D3 processes the input control signal, preventing it from flowing in the opposite direction or backflow, ensuring unidirectional signal conduction. The fourth voltage regulator D4 provides voltage protection and regulation for the circuit. Its primary function is to clamp the circuit voltage to prevent excessive voltage from damaging components. This ensures safe operation even with large input voltage fluctuations, effectively improving the circuit's reliability and durability.

[0074] Furthermore, the cathode of the light-emitting diode D2 is connected to the collector of the second transistor Q2, the anode of the light-emitting diode D2 is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the cathode of the first diode D1 and receives the first voltage, the anode of the first diode D1 is connected to one end of the fuse F1, and the other end of the fuse F1 is connected to the third voltage.

[0075] The second transistor Q2 acts as a switch, controlling the current flowing through the LED D2. When the second transistor Q2 is on, the LED D2 emits light; when the second transistor Q2 is off, the LED D2 turns off. The first resistor R1 acts as a current limiter, limiting the current flowing through the LED D2 and protecting the LED D2 from damage caused by excessive current. The first diode D1 is used to prevent the generation of reverse current, ensuring that current can only flow from the voltage terminal to the load, preventing backflow of current. The function of the fuse F1 is to protect the circuit from overcurrent damage. When the current in the circuit exceeds the rated value, the fuse will melt, cutting off the power supply and preventing excessive current from causing component damage or circuit failure. This circuit design ensures the stable operation of the LED D2 through current limiting, unidirectional conduction, and overcurrent protection. It also provides a circuit safety protection mechanism, improving the circuit's reliability and safety.

[0076] Example 2

[0077] The second embodiment provides a photoelectric sensor, including the driving circuit and light-emitting diode provided in the first embodiment.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A photoelectric sensor driving circuit, characterized in that: include: a voltage conversion module, wherein an input terminal of the voltage conversion module receives a first voltage and converts the first voltage to output a second voltage; a signal filtering module, wherein a voltage input terminal of the signal filtering module is connected to the output terminal of the voltage conversion module, and the input terminal of the signal filtering module receives a first control signal, filters the first control signal, and then outputs a second control signal; a switch module, one end of which is connected to a light-emitting diode, and a control end of which is connected to the output end of the signal filtering module, so as to be in a conducting state according to the second control signal, thereby lighting up the light-emitting diode; a first protection module, wherein a first end of the first protection module is connected to the other end of the switch module, a second end of the first protection module is connected to the control end of the switch module, and a third end of the first protection module is grounded, so as to shut down the switch module when the current flowing through the switch module exceeds a preset current value; A second protection module, wherein a first end of the second protection module receives the first voltage, a second end of the second protection module is connected to the control end of the switch module, and a third end of the second protection module is grounded to turn off the switch module when the temperature exceeds a preset temperature value.

2. The driving circuit according to claim 1, wherein: The voltage conversion module includes a first capacitor, a second capacitor, a tenth resistor, a twelfth resistor, a fifth transistor and a sixth voltage regulator; One end of the first capacitor, one end of the tenth resistor and the collector of the fifth transistor are commonly connected as the input end of the voltage conversion module, the other end of the tenth resistor is respectively connected to the base of the fifth transistor and the cathode of the sixth voltage-stabilizing diode, the emitter of the fifth transistor, one end of the second capacitor and one end of the twelfth resistor are commonly connected as the output end of the voltage conversion module, the other end of the first capacitor, the anode of the sixth voltage-stabilizing diode, the other end of the second capacitor and the other end of the twelfth resistor are commonly connected to the ground.

3. The driving circuit according to claim 1, wherein: The signal filtering module includes a first transistor, a second resistor, a third resistor, a sixth resistor and a fifth diode; One end of the second resistor and the emitter of the first transistor are connected together as the voltage input end of the signal filtering module, the other end of the second resistor is respectively connected to the anode of the fifth diode and one end of the third resistor, the cathode of the fifth diode is the input end of the signal filtering module, the other end of the third resistor is connected to the base of the first transistor, the collector of the first transistor and one end of the sixth resistor are connected together as the output end of the signal filtering module, and the other end of the sixth resistor is grounded.

4. The driving circuit according to claim 1, wherein: The switch module is a second transistor, the collector of the second transistor is one end of the switch module, the base of the second transistor is the control end of the switch module, and the emitter of the second transistor is the other end of the switch module.

5. The driving circuit according to claim 4, wherein: The first protection module includes a seventh resistor, a ninth resistor and a fourth transistor; One end of the seventh resistor and one end of the ninth resistor are connected to the first end of the first protection module, the other end of the seventh resistor is connected to the base of the fourth transistor, the collector of the fourth transistor is the second end of the first protection module, and the emitter of the fourth transistor and the other end of the ninth resistor are connected to the ground.

6. The driving circuit according to claim 4, wherein: The second protection module includes a fifth resistor, an eighth resistor and a third transistor; One end of the fifth resistor is the first end of the second protection module, the other end of the fifth resistor is respectively connected to the base of the third transistor and one end of the eighth resistor, and the emitter of the third transistor and the other end of the eighth resistor are commonly connected to the ground.

7. The driving circuit according to claim 4, wherein: The switch module further includes a fourth resistor, one end of the fourth resistor is the control end of the switch module, and the other end of the fourth resistor is connected to the base of the second transistor.

8. The driving circuit according to claim 4, wherein: The collector of the second triode is connected to the cathode of the third diode and the cathode of the fourth voltage-stabilizing tube respectively, the anode of the third diode is input with a control signal, and the anode of the fourth voltage-stabilizing tube is grounded.

9. The driving circuit according to claim 4, wherein: The cathode of the light-emitting diode is connected to the collector of the second transistor, the anode of the light-emitting diode is connected to one end of the first resistor, the other end of the first resistor is connected to the cathode of the first diode and receives a first voltage, the anode of the first diode is connected to one end of the fuse, and the other end of the fuse receives a third voltage.

10. A photoelectric sensor, characterized in that: The photosensor comprises the driving circuit and the light emitting diode according to any one of claims 1 to 9.

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