Overcurrent protection circuit of pulse laser

Abstract

The utility model discloses an overcurrent protection circuit of a pulse laser. The overcurrent protection circuit comprises an overcurrent comparison circuit, a signal amplification circuit, a pulse capture circuit and a single-chip microcomputer control circuit which are connected in sequence. The output end of the single-chip microcomputer control circuit is connected with the input end of the overcurrent comparison circuit. The overcurrent comparison circuit is used for comparing the acquired voltage signal with a set reference voltage, outputting an analog signal according to a comparison result and transmitting the analog signal to the signal amplification circuit; the signal amplification circuit is used for amplifying an analog signal, and the pulse capture circuit is used for performing level conversion on the amplified analog signal and outputting the converted analog signal to the single chip microcomputer control circuit; the single-chip microcomputer control circuit is used for judging whether the circuit is over-current or not according to the pulse signal, and if it is judged that over-current occurs, signal output is stopped; and the power supply circuit provides stable working voltage for each circuit. The circuit provided by the utility model not only has an adjustable over-current threshold value, but also has an automatic restart function after a fault, and is low in cost and easy to popularize.

Description

Technical Field

[0001] The utility model relates to the technical field of lasers, in particular to an overcurrent protection circuit for a pulsed laser. Background Art

[0002] Overcurrent protection is an essential safety measure in the production and use of lasers and is also an important part of the internal safety protection circuit. At present, the precision of the laser production process is not high, and each link requires fine process control and strict quality inspection to ensure the stable performance and reliability of the laser. If the current is too large, it will cause great damage to the optics, affecting the stable operation of the laser and the safety of personnel.

[0003] The existing laser safety protection circuit stops external output after judging overcurrent through the fed-back high-level signal, but it cannot judge to continue normal output after the circuit is stable. For example, in the patent "An Overcurrent and Overvoltage Protection Circuit and Lamp for a Laser Device" with the publication number CN215499671U, this solution sets up an overcurrent protection circuit connected to the loop of the laser device to limit the maximum current of the laser device, and limits the maximum voltage of the laser device through the overvoltage protection circuit. However, when the current is too large in this circuit, the second triode conducts for overcurrent protection, and the third triode is connected to the power supply and the first MOS tube through a voltage-dividing resistor. When the voltage is too large, the first MOS tube is controlled to turn off to achieve the purpose of overvoltage protection, but it cannot complete the continued normal output after the circuit is stable after turning off.

[0004] Therefore, it is necessary to propose an overcurrent protection circuit for a pulsed laser, which can perform overcurrent protection on the circuit, realize the automatic restart function after troubleshooting, and perform re-comparison through the overcurrent comparison circuit after overcurrent protection so that the circuit can continue to operate after returning to normal, further improving the working stability of the laser. Summary of the Utility Model

[0005] In view of this, it is necessary to provide an overcurrent protection circuit for a pulsed laser, which can solve the technical problem that the existing laser overcurrent protection device cannot restart after self-protection when an abnormality or large current occurs in the pulsed laser.

[0006] To achieve the above technical purpose, the utility model adopts the following technical solutions:

[0007] The utility model provides an overcurrent protection circuit for a pulsed laser, including an overcurrent comparison circuit, a signal amplification circuit, a pulse capture circuit, and a single-chip microcomputer control circuit connected in sequence; the output end of the single-chip microcomputer control circuit is connected to the input end of the overcurrent comparison circuit; the overcurrent comparison circuit, the signal amplification circuit, the pulse capture circuit, and the single-chip microcomputer control circuit are all connected to the power supply circuit;

[0008] The overcurrent comparison circuit is used to compare the collected voltage signal with a set reference voltage, output an analog signal according to the comparison result and transmit it to the signal amplification circuit;

[0009] The signal amplification circuit is used to amplify the analog signal and transmit it to the pulse capture circuit;

[0010] The pulse capture circuit is used to perform level conversion on the amplified analog signal and output it to the single-chip microcomputer control circuit;

[0011] The single-chip microcomputer control circuit is used to judge whether the circuit is overcurrent according to the pulse signal. If it is determined that overcurrent occurs, the signal output is stopped. If it is determined that there is no overcurrent, a voltage signal is output to the overcurrent comparison circuit;

[0012] The power supply circuit provides a stable working voltage for each circuit.

[0013] Further, the overcurrent comparison circuit includes an operational amplifier N5;

[0014] The negative input terminal of the operational amplifier N5 is connected to one end of a resistor R44, a resistor R2 and a resistor R47. The other end of the resistor R2 is connected to the digital ground through a resistor R49, and the other end of the resistor R47 is connected to the power supply voltage. The positive input terminal of the operational amplifier N5 is connected to the single-chip microcomputer control circuit through a resistor R42, and the output terminal is connected to the signal amplification circuit through a resistor R39.

[0015] Further, the model of the operational amplifier is LM741 or OPA2134.

[0016] Further, the signal amplification circuit includes an NPN transistor Q1;

[0017] The base of the transistor Q1 is connected to the output terminal of the overcurrent comparison circuit through a resistor R43 and a resistor R39. The emitter of the transistor Q1 is connected to the digital ground, and the collector outputs the amplified analog signal to the pulse capture circuit.

[0018] Further, the pulse capture circuit includes a signal comparator;

[0019] The positive input terminal of the signal comparator is connected to the output terminal of the signal amplification circuit. The negative input terminal of the signal comparator is connected to the first end of a voltage-dividing resistor, and the second end of the voltage-dividing resistor is connected to the power supply voltage. The output terminal of the signal comparator is connected to the input terminal of the single-chip microcomputer control circuit;

[0020] When the voltage of the signal output by the signal amplification circuit is higher than the voltage of the first end of the voltage-dividing resistor, the output terminal of the signal comparator outputs a TTL high level to the single-chip microcomputer control circuit.

[0021] Further, the model of the signal comparator is LM339.

[0022] Further, the single-chip microcomputer control circuit includes a pulse recognition module connected to the output end of the pulse capture circuit;

[0023] The pulse recognition module is used to recognize the TTL high-level signal to judge whether the laser is in a normal working state; if the TTL high-level signal is not recognized, it is determined that the laser is in a normal working state; if the TTL high-level signal is recognized, it is determined that the laser is in an abnormal state and the signal output is stopped.

[0024] Further, the single-chip microcomputer control circuit includes a single-chip microcomputer chip of the STM32F series.

[0025] Further, the first fiber grating and the third fiber grating are high-reflection gratings; the second fiber grating and the fourth fiber grating are low-reflection gratings.

[0026] Further, the external voltage input of the power supply circuit is 24V, and the output voltages after circuit conversion are 12V, 5V, and 3.3V.

[0027] Compared with the prior art, the beneficial effects of the present invention include: the circuit provided by the present invention compares the collected voltage signal with the set reference voltage through an overcurrent comparison circuit and outputs an analog voltage signal; the signal amplification circuit amplifies the weak low-amplitude analog signal, the pulse capture circuit captures the electrical signal amplified by the signal amplification circuit, and converts the signal into a high-level or low-level signal and outputs it to the single-chip microcomputer control circuit; the single-chip microcomputer control circuit judges whether the laser is faulty by identifying the high-level pulse signal, and stops the signal output to protect the circuit if overcurrent occurs. This circuit only feeds back the correct detection value when the single-chip microcomputer detects that the pulse signal is at a low level; otherwise, it is determined that the laser output is abnormal, which has the advantages of high detection accuracy and low false alarm rate, greatly improving the stability of the laser working state; at the same time, this circuit also has an adjustable overcurrent threshold and an automatic restart function after a fault, and has low cost and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of the overcurrent protection circuit of the pulse laser provided by the present invention;

[0029] Figure 2 is a schematic circuit diagram of an embodiment of the overcurrent comparison circuit, amplification circuit and pulse capture circuit provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The preferred embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention.

[0031] In the description of this application, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0032] Referring to "embodiment" herein means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of the present invention. The phrase appears in various positions in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein may be combined with other embodiments.

[0033] The present invention provides an overcurrent protection circuit for a pulsed laser. Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of the overcurrent protection circuit for the pulsed laser provided in this embodiment, including an overcurrent comparison circuit 101, a signal amplification circuit 102, a pulse capture circuit 103, and a single-chip microcomputer control circuit 104 connected in sequence; the output end of the single-chip microcomputer control circuit 104 is connected to the input end of the overcurrent comparison circuit 101; the overcurrent comparison circuit 101, the signal amplification circuit 102, the pulse capture circuit 103, and the single-chip microcomputer control circuit 104 are all connected to a power supply circuit 105;

[0034] The overcurrent comparison circuit 101 is used to compare the collected voltage signal with a set reference voltage, and output an analog signal according to the comparison result and transmit it to the signal amplification circuit 102;

[0035] The signal amplification circuit 102 is used to amplify the analog signal and transmit it to the pulse capture circuit 103;

[0036] The pulse capture circuit 103 is used to perform level conversion on the amplified analog signal and output it to the single-chip microcomputer control circuit 104;

[0037] The single-chip microcomputer control circuit 104 is used to judge whether the circuit is overcurrent according to the pulse signal. If it is determined that overcurrent occurs, the signal output is stopped. If it is determined that there is no overcurrent, a voltage signal is output to the overcurrent comparison circuit 101;

[0038] The power supply circuit 105 provides a stable working voltage for each circuit.

[0039] The overcurrent protection circuit of the pulsed laser provided in this embodiment compares the collected voltage signal with the set reference voltage through an overcurrent comparison circuit and outputs an analog voltage signal; the signal amplification circuit amplifies the weak and low-amplitude analog signal, and the pulse capture circuit captures the electrical signal amplified by the signal amplification circuit and converts the signal into a high-level or low-level signal, which is output to the single-chip microcomputer control circuit; the single-chip microcomputer control circuit determines whether the laser is faulty by identifying the high-level pulse signal. If an overcurrent occurs, the signal output is stopped to protect the circuit. The circuit provided in this embodiment only feeds back the correct detection value when the single-chip microcomputer detects that the pulse signal is at a low level; otherwise, it is determined that the laser output is abnormal, which has the advantages of high detection accuracy and low false alarm rate, greatly improving the stability of the laser working state; at the same time, this circuit also has an adjustable overcurrent threshold and an automatic restart function after a fault, and has a low cost and is easy to promote.

[0040] As a preferred embodiment, as Figure 2 shown, the overcurrent comparison circuit includes an operational amplifier N5;

[0041] The negative input terminal of the operational amplifier N5 is connected to one end of a resistor R44, a resistor R2, and a resistor R47. The other end of the resistor R2 is connected to the digital ground through a resistor R49, and the other end of the resistor R47 is connected to the power supply voltage; the positive input terminal of the operational amplifier N5 is connected to the single-chip microcomputer control circuit through a resistor R42, and the output terminal is connected to the signal amplification circuit through a resistor R39.

[0042] Through the setting of the above overcurrent comparison circuit, the reference voltage value that cannot be exceeded is jointly set by R47, R2, and R49. The overcurrent threshold can be adjusted as needed and input to the negative input terminal of the operational amplifier N5. At the same time, the voltage value output by the single-chip microcomputer control circuit collected is input to the positive input terminal of N5. The set voltage is compared with the actual voltage through this operational amplifier N5, and the HL OUTM signal is output. Specifically, when the actual voltage is higher than the set voltage, the operational amplifier N5 will generate a positive voltage close to the comparator VCC at the output terminal. However, if the collected voltage is greater than the reference voltage, the operational amplifier N5 will generate a negative power supply voltage at both ends of the output (the negative power supply is connected to GND, so it is 0V in this case).

[0043] In some embodiments, the model of the operational amplifier is LM741 or OPA2134.

[0044] In practice, the operational amplifier can be selected according to needs. LM741 has a lower cost and is suitable for applications in general scenarios. OPA2134 performs well in terms of low-noise performance and is suitable for application scenarios with higher requirements for signal quality.

[0045] As a preferred embodiment, please refer to Figure 2 , the signal amplification circuit includes an NPN transistor Q1;

[0046] The base of the transistor Q1 is connected to the output terminal of the overcurrent comparison circuit through a resistor R43 and a resistor R39; the emitter of the transistor Q1 is connected to the digital ground, and the collector outputs the amplified analog signal to the pulse capture circuit.

[0047] As a preferred embodiment, the NPN transistor Q1 is an 8050 transistor.

[0048] Using an 8050 NPN transistor as the signal amplification device can provide good performance and reliability, while keeping the cost within an acceptable range, which is suitable for analog signal processing and applications in this scenario.

[0049] As a preferred embodiment, the pulse capture circuit includes a signal comparator;

[0050] The positive input terminal of the signal comparator is connected to the output terminal of the signal amplification circuit, the negative input terminal of the signal comparator is connected to the first end of the voltage dividing resistor, and the second end of the voltage dividing resistor is connected to the power supply voltage; the output terminal of the signal comparator is connected to the input terminal of the single-chip microcomputer control circuit;

[0051] When the voltage of the signal output by the signal amplification circuit is higher than the voltage of the first end of the voltage dividing resistor, the output terminal of the signal comparator outputs a TTL high level to the single-chip microcomputer control circuit.

[0052] Figure 2 In Figure 2 , the signal comparator is comparator N7. The negative input terminal of comparator N7 is connected to one end of resistor R49. The other end of resistor R49 is connected to the power supply voltage through resistor R2 and resistor R47. The positive input terminal is connected to the output terminal of the signal amplification circuit through resistor R1. By comparing the output voltage of the signal amplification circuit with the voltage of resistor R49 at the negative input terminal, the amplified analog signal is shaped to output a TTL signal WORK OUTM that can be recognized by the single-chip microcomputer.

[0053] Specifically, when the output voltage value at the positive terminal is greater than the output voltage value at the negative terminal, a TTL high-level signal will be generated; otherwise, a TTL low-level signal is output and transmitted to the single-chip microcomputer control circuit. When the single-chip microcomputer recognizes the high-level TTL pulse signal, it determines that the laser has a fault and stops the signal output to protect the circuit. At this time, there is no input at the positive terminal of the overcurrent comparison circuit, and the overcurrent comparison circuit feeds back a low-level signal to the single-chip microcomputer control circuit to make it output normally, thus completing the automatic restart function after the fault.

[0054] As a preferred embodiment, the single-chip microcomputer control circuit includes a pulse recognition module connected to the output end of the pulse capture circuit;

[0055] The pulse recognition module is used to recognize the TTL high-level signal and determine whether the laser is in a normal working state; if the TTL high-level signal is not recognized, it is determined that the laser is in a normal working state; if the TTL high-level signal is recognized, it is determined that the laser is in an abnormal state and the signal output is stopped.

[0056] As a preferred embodiment, the single-chip microcomputer control circuit includes a single-chip microcomputer chip of the STM32F series.

[0057] The single-chip microcomputer chip of the STM32F series has high processing capabilities and performance, is suitable for processing complex control tasks, and also has the advantages of rich peripherals and low power consumption. It is widely used in scenarios such as industrial control and Internet of Things devices, simplifying the software and hardware development process.

[0058] As a preferred embodiment, the external voltage input of the power supply circuit is 24V, and the output voltages after circuit conversion are 12V, 5V, and 3.3V, converting the externally input 24V power supply into different levels of voltage to meet the working needs of the entire circuit.

[0059] The overcurrent protection circuit of the pulsed laser provided in this embodiment compares the collected voltage signal with the set reference voltage through the overcurrent comparison circuit and outputs an analog voltage signal; the signal amplification circuit amplifies the weak and low-amplitude analog signal, the pulse capture circuit captures the electrical signal amplified by the signal amplification circuit, and converts this signal into a high-level or low-level signal and outputs it to the single-chip microcomputer control circuit; the single-chip microcomputer control circuit determines whether the laser is faulty by recognizing the high-level pulse signal, and stops the signal output to protect the circuit if overcurrent occurs. This circuit only feeds back the correct detection value when the single-chip microcomputer detects that the pulse signal is at a low level; otherwise, it is determined that the laser output is abnormal. It has the advantages of high detection accuracy and low false alarm rate, greatly improving the stability of the laser working state; at the same time, this circuit also has an adjustable overcurrent threshold and a function of automatic restart in case of failure, and has low cost and is easy to promote.

[0060] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An overcurrent protection circuit for a pulsed laser, characterized in that: It includes an overcurrent comparison circuit, a signal amplification circuit, a pulse capture circuit and a single-chip control circuit connected in sequence; the output end of the single-chip control circuit is connected to the input end of the overcurrent comparison circuit; the overcurrent comparison circuit, the signal amplification circuit, the pulse capture circuit and the single-chip control circuit are all connected to the power supply circuit; The overcurrent comparison circuit is used to compare the collected voltage signal with the set reference voltage, output an analog signal according to the comparison result and transmit it to the signal amplification circuit; The signal amplification circuit is used to amplify the analog signal and transmit it to the pulse capture circuit; The pulse capture circuit is used to perform level conversion on the amplified analog signal and output it to the single chip control circuit; The single chip control circuit is used to determine whether the circuit is overcurrent based on the pulse signal, and if it is determined that overcurrent occurs, the signal output is stopped; if it is determined that there is no overcurrent, the voltage signal is output to the overcurrent comparison circuit; The power supply circuit provides a stable operating voltage for each circuit.

2. The overcurrent protection circuit of the pulse laser according to claim 1, characterized in that: The overcurrent comparison circuit includes an operational amplifier N5; The negative input end of the operational amplifier N5 is connected to the resistor R2 and one end of the resistor R47 through the resistor R44, the other end of the resistor R2 is connected to the digital ground through the resistor R49, and the other end of the resistor R47 is connected to the power supply voltage; the positive input end of the operational amplifier N5 is connected to the single-chip microcomputer control circuit through the resistor R42, and the output end is connected to the signal amplification circuit through the resistor R39.

3. The overcurrent protection circuit of the pulse laser according to claim 2, characterized in that: The operational amplifier is LM741 or OPA2134.

4. The overcurrent protection circuit for pulsed laser according to claim 1, characterized in that: The signal amplifying circuit includes an NPN transistor Q1; The base of the transistor Q1 is connected to the output end of the overcurrent comparison circuit through the resistor R43 and the resistor R39; the emitter of the transistor Q1 is connected to the digital ground, and the collector outputs the amplified analog signal to the pulse capture circuit.

5. The overcurrent protection circuit for pulsed laser according to claim 4, characterized in that: The NPN transistor Q1 is a 8050 transistor.

6. The overcurrent protection circuit for pulsed laser according to claim 1, characterized in that: The pulse capture circuit includes a signal comparator; The positive input terminal of the signal comparator is connected to the output terminal of the signal amplifying circuit, the negative input terminal of the signal comparator is connected to the first terminal of the voltage dividing resistor, and the second terminal of the voltage dividing resistor is connected to the power supply voltage; the output terminal of the signal comparator is connected to the input terminal of the single chip control circuit; When the voltage of the signal output by the signal amplifying circuit is higher than the voltage of the first end of the voltage dividing resistor, the output end of the signal comparator outputs a TTL high level to the single chip control circuit.

7. The overcurrent protection circuit for pulsed laser according to claim 6, characterized in that: The model of the signal comparator is LM339.

8. The overcurrent protection circuit for pulsed laser according to claim 1, characterized in that: The single chip control circuit includes a pulse identification module connected to the output end of the pulse capture circuit; The pulse recognition module is used to recognize the TTL high-level signal and determine whether the laser is in a normal working state; if the TTL high-level signal is not recognized, it is determined that the laser is in a normal working state; if the TTL high-level signal is recognized, it is determined that the laser is in an abnormal state and the signal output is stopped.

9. The overcurrent protection circuit for pulsed laser according to claim 1, characterized in that: The single-chip microcomputer control circuit includes a single-chip microcomputer chip of the STM32F series.

10. The overcurrent protection circuit for pulsed laser according to claim 1, characterized in that: The external voltage input of the power supply circuit is 24V, and the output voltage after circuit conversion is 12V, 5V and 3.3V.

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