Fault detection circuit and laser

Abstract

The disclosure provides a fault detection circuit and a laser. The circuit comprises a power supply unit, an input end of the power supply unit being coupled to an external power source; a first conversion unit, an input end of the first conversion unit being coupled to an output end of the power supply unit through a switching element, and an output end of the first conversion unit being coupled to a load; the first conversion unit being configured to convert an output voltage of the power supply unit into a required voltage of the load; a switching state of the switching element enabling or disabling a power supply path between the power supply unit and the first conversion unit; and a first detection unit, the first detection unit being parallel to the output end of the first conversion unit and being configured to form a first indication signal output to the outside in response to an output voltage of the first conversion unit when the power supply path is enabled. The fault detection mechanism of the circuit can output a clear fault indication signal, changing the low-efficiency mode of the previous after-sales personnel who need to disassemble and check electrical devices one by one.

Description

Technical Field

[0001] This disclosure relates to the field of laser technology, and in particular to fault detection circuits and lasers. Background Technology

[0002] Lasers are widely used in numerous fields, including modern industrial processing, medical aesthetics, and scientific research, due to their high energy density and high precision. For example, in industry, laser cutting and welding technologies rely on the stable output of high-energy laser beams to process materials; in the medical field, laser surgery utilizes the precise energy control of lasers for tissue cutting and repair. However, the complex electrical system inside a laser makes it extremely sensitive to power supply stability. It contains power supplies for the pump source and control system, as well as critical electrical components such as AC power relays and push-button switches. Failure in any of these components can lead to unstable laser output power, decreased beam quality, and in severe cases, damage to the laser's core components, causing equipment malfunctions or even safety accidents.

[0003] Currently, the common methods for fault detection in laser power supply systems mainly involve basic protection using simple fuses and overvoltage protection devices. Fuses can only cut off the circuit when excessive current causes them to blow; they cannot provide real-time monitoring and early warning of abnormal voltage conditions, nor can they promptly detect hidden faults in the power supply circuit.

[0004] When internal components of a laser malfunction, after-sales personnel must go to the site to disassemble the machine and check each internal electrical component one by one to identify the damaged part. This troubleshooting method is not only time-consuming and labor-intensive, but even if the faulty component is found, there is often no suitable replacement part available. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this disclosure is to provide a fault detection circuit and a laser to solve the problems in the related art.

[0006] The first aspect of this disclosure provides a fault detection circuit, comprising:

[0007] A power supply unit, wherein the input terminal of the power supply unit is coupled to an external power source;

[0008] A first conversion unit, the input of which is coupled to the output of the power supply unit via a switching element, and the output of which is coupled to a load; the first conversion unit is configured to convert the output voltage of the power supply unit into the voltage required by the load;

[0009] The switching state of the switching element causes the power supply path between the power supply unit and the first conversion unit to be turned on or off.

[0010] The first detection unit, which is connected in parallel with the output of the first conversion unit, is configured to generate a first indication signal output to the outside based on the output voltage of the first conversion unit when the power supply path is turned on.

[0011] In the embodiments of the first aspect, it further includes:

[0012] The second conversion unit has its input terminal coupled to the output terminal of the power supply unit, and its output terminal coupled to a control chip and a switching element via a control switch. The second conversion unit is configured to convert the output voltage of the power supply unit into the voltage required by the control chip; wherein the control chip is used to control the output voltage of the load.

[0013] In an embodiment of the first aspect, the switching element includes a relay, the relay including a coil and a relay switch; a first end of the coil is coupled to the positive output terminal of the second conversion unit via the control switch, and a second end of the coil is coupled to the negative output terminal of the second conversion unit; the coil is configured to generate an output control signal controlling the relay switch to turn on in response to the output voltage of the second conversion unit.

[0014] The relay switch is coupled to the power supply path and is used to turn the power supply path on or off.

[0015] In an embodiment of the first aspect, a second detection unit is further included, which is connected in parallel across the two ends of the coil and configured to generate a second indication signal output to the outside in response to the voltage across the two ends of the coil.

[0016] In an embodiment of the first aspect, a third detection unit is further included, which is connected in parallel to the output of the second conversion unit and is configured to generate a third indication signal output to the outside in response to the output voltage of the second conversion unit.

[0017] In an embodiment of the first aspect, a fourth detection unit is further included, one end of which is coupled to the output terminal of the power supply unit, and the other end of which is coupled to the output terminal of the switching element, and is configured to generate a fourth indication signal output to the outside in response to the voltage at the input and output terminals of the switching element.

[0018] In a first aspect embodiment, the power supply unit includes:

[0019] The live wire input terminal is coupled to an external AC power supply and is also coupled to the input terminal of the first conversion unit through the switching element;

[0020] The neutral input terminal is coupled to the external AC power supply and the input terminal of the first conversion unit.

[0021] In an embodiment of the first aspect, the first indication signal includes at least one of: an audio indication signal, a light indication signal, and an information indication signal.

[0022] In an embodiment of the first aspect, the first detection unit includes a light-emitting element for displaying the first indication signal to the outside.

[0023] A second aspect of this disclosure provides a laser, wherein the fault detection circuit described in any one of the foregoing claims is included.

[0024] The beneficial effects of this disclosure are as follows: By connecting the first detection unit in parallel with the output of the first conversion unit, it can respond to changes in output voltage in real time when the power supply path is on. Compared with the limitation of traditional fuses that can only detect current overload, it can promptly capture voltage abnormalities such as overvoltage and undervoltage. The fault detection mechanism of this circuit can output a clear fault indication signal, changing the inefficient mode of after-sales personnel having to disassemble the machine to check electrical components one by one. When the laser malfunctions, after-sales personnel can quickly identify the faulty component based on the first indication signal, without having to conduct a comprehensive check of numerous internal components such as the pump source power supply and the control system power supply, greatly shortening the fault diagnosis time and improving maintenance efficiency. Attached Figure Description

[0025] Figure 1 A schematic diagram of a fault detection circuit according to one embodiment of the present disclosure is shown.

[0026] Figure 2 A circuit connection diagram of a fault detection circuit according to one embodiment of the present disclosure is shown.

[0027] Figure 3 A schematic diagram of a fault detection circuit is shown in yet another embodiment of this disclosure. Detailed Implementation

[0028] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the information disclosed herein. This disclosure can also be implemented or applied through other different specific embodiments, and various details in this disclosure can be modified or changed according to different viewpoints and application units without departing from the spirit of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be combined with each other.

[0029] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings, so that those skilled in the art to which this disclosure pertains can readily implement it. This disclosure may be embodied in many different forms and is not limited to the embodiments described herein.

[0030] In this disclosure, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic represented in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. Furthermore, the specific features, structures, materials, or characteristics represented may be combined in any suitable manner in any one or a group of embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples represented in this disclosure, as well as the features of those different embodiments or examples.

[0031] Furthermore, the terms "first" and "second" are used for illustrative purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the representation of this disclosure, "a set" means two or more, unless otherwise explicitly specified.

[0032] For the purpose of clarity, devices unrelated to the description are omitted, and the same or similar components throughout the specification are given the same reference numerals.

[0033] Throughout this specification, when it is said that a device is "connected" to another device, this includes not only "direct connection" but also "indirect connection" by placing other components in between. Furthermore, when it is said that a device "comprises" a certain constituent element, unless otherwise stated otherwise, this does not exclude other constituent elements, but rather implies that other constituent elements may be included.

[0034] Although the terms first, second, etc., are used in some examples herein to refer to various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, first interface and second interface, etc., are used. Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms unless the context indicates otherwise. It should be further understood that the terms “comprising” or “including” indicate the presence of features, steps, operations, elements, units, items, kinds, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, units, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition will only occur if the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0035] The technical terms used herein are for reference only to specific embodiments and are not intended to limit the scope of this disclosure. The singular form used herein includes the plural form unless the statement explicitly indicates otherwise. The word "comprising" as used in this specification means to specify a particular characteristic, region, integer, step, operation, element, and / or component, and does not exclude the presence or addition of other characteristics, regions, integers, steps, operations, elements, and / or components.

[0036] Although not explicitly defined, all terms, including technical and scientific terms used herein, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries shall be further interpreted as having a meaning consistent with the relevant technical literature and the message of the present disclosure, and shall not be over-interpreted as having an ideal or overly formulaic meaning unless otherwise defined.

[0037] Modern industrial lasers typically consist of core components such as a pump source, laser resonant cavity, control system, and cooling system. The pump source power supply provides highly stable power to the pump module, while the control system power supply powers precision circuits for laser parameter adjustment and safety interlocks. When a laser experiences output power fluctuations or shutdown, current technologies only allow basic protection devices like fuses to cut off the main circuit, making it difficult to accurately pinpoint the fault. After-sales personnel must travel to the site with multimeters, oscilloscopes, and other tools to sequentially test the voltage and resistance of dozens of electrical components, including AC power relays, push-button switches, and power modules, a time-consuming process. Even more challenging is that even if an abnormal output voltage is detected in the pump source power supply, it's difficult to quickly determine whether the problem stems from a faulty power module or a chain reaction caused by a short circuit in a downstream circuit, often requiring repeated component replacements and testing.

[0038] To address the aforementioned problems, one embodiment of this disclosure provides a fault detection circuit, wherein, in Figure 1 In this embodiment, the fault detection circuit includes a power supply unit 100, a first conversion unit 200, a switching element 300, and a first detection unit 210. The first detection unit 210 is connected in parallel with the output terminal of the first conversion unit 200, continuously monitors the voltage of the first detection unit 210, and outputs an indication signal in a timely manner when an abnormality occurs.

[0039] Specifically, the input terminal of the power supply unit 100 is coupled to an external power source; the input terminal of the first conversion unit 200 is coupled to the output terminal of the power supply unit 100 through a switching element 300, and the output terminal of the first conversion unit 200 is coupled to a load 400; the first conversion unit 200 is configured to convert the output voltage of the power supply unit 100 into the voltage required by the load 400.

[0040] The external power source is an AC power source, such as 220V / 50Hz mains power or other standard AC voltage levels. To ensure the proper functioning of the subsequent load 400, the first conversion unit 200 not only provides voltage adaptation but also converts the AC input into a stable DC output.

[0041] In some embodiments, the first conversion unit 200 is used to power a key component in the laser—the pump source. In fiber lasers, the pump source typically consists of multiple high-power semiconductor laser diodes, which require a stable and precise DC power supply. Abnormal power supply (such as low voltage, interruption, or large fluctuations) may cause the pump source to malfunction, have unstable output, or even be damaged, ultimately affecting the laser output quality.

[0042] The switching state of the switching element 300 causes the power supply path between the power supply unit 100 and the first conversion unit 200 to be connected or disconnected.

[0043] Specifically, pump sources are typically high-power devices that consume significant amounts of electrical energy even when laser output is not required, if they remain continuously operational. By controlling the power supply path through the first switching unit, the power can be cut off when the laser is not in use, significantly reducing energy consumption and preventing frequent and unnecessary power supply from accelerating the aging of electronic components and shortening the lifespan of the pump source and other related components. Optionally, when the main control unit issues a command or detects an abnormality, the first switching unit can be controlled by a first indication signal or by an external signal to cut off or restore the power supply path.

[0044] The first detection unit 210 is connected in parallel with the output terminal of the first conversion unit 200 and is configured to generate a first indication signal output to the outside based on the output voltage of the first conversion unit 200 when the power supply path is turned on.

[0045] This means that the first detection unit 210 can monitor in real time whether the first conversion unit 200 is working normally. When the power supply path is on and the first conversion unit 200 is working normally, a voltage difference is generated between the positive and negative output terminals of the first conversion unit 200, so the first detection unit 210 will generate a first indication signal indicating a "normal" state. If the first conversion unit 200 fails to work normally, so that no voltage difference can be generated between the positive and negative output terminals, or the generated voltage difference is insufficient for the first detection unit 210 to generate the first indication signal, then the first detection unit 210 will generate a second indication signal indicating an "abnormal" state.

[0046] exist Figure 2In this embodiment, the first detection unit 210 includes a light-emitting element for visually displaying whether the first conversion unit 200 is working properly, and indicating the working status of the first conversion unit 200 by turning it on or off. When the first conversion unit 200 is working properly, the light-emitting element will light up due to the voltage difference between its two ends, indicating that the first conversion unit 200 is operating normally. If the first conversion unit 200 fails to work properly, the voltage difference between the two ends of the light-emitting element cannot form for it to emit light normally, so it will not light up, indicating to the operator or maintenance personnel that there is an abnormality.

[0047] In some embodiments, the first detection unit 210 can also obtain a sampling voltage from the output terminal of the first conversion unit 200 through a voltage divider resistor network. The voltage divider resistor network consists of two or more resistors connected in series, one end of which is connected to the output terminal of the first conversion unit 200, and the other end is grounded. By appropriately selecting the resistance ratio of each resistor, the higher voltage output by the first conversion unit 200 can be proportionally reduced to a safe voltage range suitable for the operation of the light-emitting element. Furthermore, the voltage divider resistor network also serves as a current limiter, preventing excessive current from flowing into the light-emitting element and avoiding damage due to overload.

[0048] Staff can quickly determine the power supply status by observing whether the light-emitting elements are lit. For example, a lit light-emitting element indicates that the system is operating normally, while an off light-emitting element indicates a possible fault, facilitating timely troubleshooting.

[0049] exist Figure 2 In this embodiment, the light-emitting element, like a lamp used in daily life, integrates a voltage conversion circuit, enabling it to function not only as a simple status indicator but also to operate stably over a wide input voltage range. Specifically, the light-emitting element includes transformer, rectifier (optional configuration for AC input), filter, and voltage regulator circuits, capable of converting fluctuating input voltages (whether AC or DC) into a constant voltage suitable for its operation. Because the light-emitting element itself possesses the necessary voltage regulation function, external circuit design is simplified, eliminating the need for complex voltage divider networks or voltage regulator circuits, thus reducing costs and saving space.

[0050] In some embodiments, the first indication signal may include at least one of an audible indication signal, an optical indication signal, and an information indication signal to adapt to user needs and environmental conditions in different application scenarios. For example, an intuitive optical indication signal can be provided by the on / off state or color change of a light-emitting element (such as an LED). The LED lights up when the power supply path is normal and turns off when an abnormality occurs to alert the operator. At the same time, an audible indication signal can be emitted by a buzzer or speaker to issue a continuous or intermittent alarm sound when a fault is detected, so as to draw attention immediately. In addition, an information indication signal can be used to send the detection results in data form to an external control module or human-machine interface through a digital communication interface, displaying them as text, code, or graphical information, making the device status clear at a glance and facilitating the rapid detection and handling of abnormal situations.

[0051] Optionally, in Figure 2 In this embodiment, the switching element 300 includes a relay, which includes a coil 301 and a relay switch 302. A first end of the coil 301 is coupled to the positive output terminal of the second conversion unit 500 via the control switch 600, and a second end of the coil 301 is coupled to the negative output terminal of the second conversion unit 500. The coil 301 is configured to generate a control signal that controls the relay switch 302 to turn on in response to the output voltage of the second conversion unit 500. The relay switch 302 is coupled to the power supply path and is used to turn the power supply path on or off.

[0052] Please refer to Figure 2 In the illustrated embodiment, the second conversion unit 500 not only provides a stable operating voltage to the control chip 700, but also supplies power to the switching element 300 (e.g., a relay), providing the required voltage difference between its two ends. Specifically, the positive output terminal of the second conversion unit 500 is coupled to the first end of the relay coil 301 via a control switch 600, while the negative output terminal is coupled to the second end of the relay coil 301. When the control switch 600 is turned on, current flows from the positive output terminal of the second conversion unit 500 to the relay coil 301, forming a circuit through the negative output terminal. This energizes the relay coil 301 and generates a magnetic field, driving the internal mechanical contacts (i.e., the relay switch 302) to operate, thereby controlling the power supply path to be turned on or off.

[0053] In addition, the voltage provided by the second conversion unit 500 must meet the operating requirements of the relay coil 301 to ensure that the relay can operate reliably.

[0054] Optionally, the fault detection circuit further includes a second conversion unit 500.

[0055] exist Figure 3In this embodiment, the input terminal of the second conversion unit 500 is coupled to the output terminal of the power supply unit 100, the output terminal of the second conversion unit 500 is coupled to a control chip 700 and coupled to the switching element 300 through a control switch 600, and the second conversion unit 500 is configured to convert the output voltage of the power supply unit 100 into the voltage required by the control chip 700; wherein, the control chip 700 is used to control the output voltage of the load 400.

[0056] Specifically, the control unit precisely controls the input of pump energy by adjusting the supply voltage or current of the pump source. The control unit is coupled to various sensors for real-time monitoring of key laser parameters, such as temperature, humidity, pump current, and laser output power. The input of the second conversion unit 500 is coupled to the output of the power supply unit 100, receiving AC voltage from the power supply unit 100.

[0057] As an example, in the second conversion unit 500, transformation, rectification, and filtering are key steps in converting the AC power supplied by the power supply unit 100 into a stable DC voltage suitable for the control chip 700. First, the external AC power is converted to a suitable voltage amplitude by a transformer. During rectification, the input AC power is converted into pulsating DC power by a rectifier. Optionally, the rectifier consists of four diodes, outputting unidirectional DC power. The filtering process uses a large-capacity capacitor to smooth the DC power and reduce voltage ripple. After rectification and filtering, the originally fluctuating AC power is converted into relatively stable DC power. The voltage is further reduced to the required low voltage level by a transformer, and a linear regulator or low-dropout linear regulator (LDO) is used to ensure the constant output voltage, unaffected by input voltage fluctuations. Ultimately, the second conversion unit 500 can provide a reliable operating voltage to the control chip 700, and the control switch 600 enables precise management of the entire system's power supply path.

[0058] As an example, regarding the implementation of the transformer, the second conversion unit 500 includes a voltage conversion chip that converts the AC power supplied by the power supply unit 100 into the operating voltage required by the control chip 700. Specifically, the conversion chip integrates a rectifier bridge and filter circuit to convert the input AC power into DC voltage; then, it reduces the high-voltage DC power to a low voltage suitable for use by the control chip 700, and ensures the stability and purity of the output voltage. The conversion chip not only provides a stable power supply to the control chip 700, but also enhances the safety and reliability of the system through its built-in multiple protection mechanisms (such as overheat protection, overcurrent protection, and short-circuit protection).

[0059] Optionally, in Figure 3In this embodiment, the fault detection circuit further includes a second detection unit 610, which is connected in parallel across the coil 301 and configured to generate a second indication signal output to the outside in response to the voltage across the coil 301.

[0060] In some embodiments, the second detection unit 610 is the same as the first detection unit 210, both implemented using a light-emitting element (e.g., an LED). The first detection unit 210 is connected in parallel to the output of the first conversion unit 200 to detect whether its output voltage is formed normally, and outputs a first indication signal by the on / off state of the light-emitting element. One end of the second detection unit 610 is coupled to one end of the control switch 600, and the other end is coupled to the negative output of the second conversion unit 500, to detect whether the control switch 600 is conducting. When the control switch 600 is working normally, current flows through the light-emitting element, illuminating it and outputting a second indication signal. By unifying the two detection units into a light-emitting element, not only is structural consistency achieved, but circuit design and production processes are simplified, enabling operators to quickly determine the working status of the power supply path and control path through light indication, resulting in good practicality and maintainability.

[0061] Optionally, in Figure 2 In this embodiment, the fault detection circuit further includes a third detection unit 510, wherein the second detection unit 610 is connected in parallel with the output terminal of the second conversion unit 500 and is configured to generate a third indication signal output to the outside in response to the output voltage of the second conversion unit 500.

[0062] In some embodiments, the fault detection circuit further includes a third detection unit 510, which is connected in parallel with the output of the second conversion unit 500. The third detection unit 510 monitors whether the second conversion unit 500 is outputting a normal operating voltage, and generates and outputs a third indication signal to the outside when a valid voltage is detected. Similar to the first detection unit 210, the third detection unit 510 is also implemented using a light-emitting element (such as an LED). One end of the LED is connected to the positive output of the second conversion unit 500, and the other end is connected to the negative output of the second conversion unit 500. When the second conversion unit 500 is operating normally, current flows through the light-emitting element to illuminate it, thereby providing an intuitive light indication signal.

[0063] Optionally, in Figure 2 In this embodiment, the fault detection circuit further includes a fourth detection unit 310, one end of which is coupled to the output terminal of the power supply unit 100, and the other end of which is coupled to the output terminal of the switching element 300. It is configured to generate a fourth indication signal output to the outside in response to the voltage at the input and output terminals of the switching element 300.

[0064] Specifically, similar to the first detection unit 210, the fourth detection unit 310 also uses a light-emitting element (e.g., an LED). When the switching element 300 is turned on, current flows through the light-emitting element of the fourth detection unit 310, causing it to light up and visually indicate that the switching element 300 is in normal working condition; when the switching element 300 is turned off or malfunctions, since no current flows, the light-emitting element goes out, indicating to the operator that there is an abnormality.

[0065] Optionally, the power supply unit 100 includes: a live wire input terminal L, a neutral wire input terminal N, and a grounding terminal PE;

[0066] The live wire input terminal L is coupled to an external AC power source and is coupled to the input terminal of the first conversion unit 200 through the switching element 300;

[0067] The neutral input terminal N is coupled to the external AC power and the input terminal of the first conversion unit 200.

[0068] Specifically, the live wire input terminal L is coupled to external AC power and connected to the input terminal of the first conversion unit 200 via a switching element 300, used to transfer the live wire voltage of the AC power to the first conversion unit 200 when the switching element 300 is turned on; one end of the neutral wire input terminal N is coupled to the neutral wire of the external AC power, and the other end is connected to the input terminal of the first conversion unit 200 to form a complete AC current loop.

[0069] A second aspect of this disclosure provides a laser, wherein the fault detection circuit described in any one of the foregoing claims is included.

[0070] The above embodiments are merely illustrative of the principles and effects of this disclosure and are not intended to limit this disclosure. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this disclosure. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this disclosure should still be covered by the protection scope of this disclosure.

Claims

1. A fault detection circuit, characterized in that, include: A power supply unit, wherein the input terminal of the power supply unit is coupled to an external power source; A first conversion unit, the input of which is coupled to the output of the power supply unit via a switching element, and the output of which is coupled to a load; the first conversion unit is configured to convert the output voltage of the power supply unit into the voltage required by the load; The switching state of the switching element causes the power supply path between the power supply unit and the first conversion unit to be turned on or off. The first detection unit, which is connected in parallel with the output of the first conversion unit, is configured to generate a first indication signal output to the outside based on the output voltage of the first conversion unit when the power supply path is turned on.

2. The fault detection circuit according to claim 1, characterized in that, Also includes: The second conversion unit has its input terminal coupled to the output terminal of the power supply unit, and its output terminal coupled to a control chip and a switching element via a control switch. The second conversion unit is configured to convert the output voltage of the power supply unit into the voltage required by the control chip; wherein the control chip is used to control the output voltage of the load.

3. The fault detection circuit according to claim 2, characterized in that, The switching element includes a relay, the relay including a coil and a relay switch; a first end of the coil is coupled to the positive output terminal of the second conversion unit through the control switch, and a second end of the coil is coupled to the negative output terminal of the second conversion unit; the coil is configured to generate a control signal to control the relay switch to turn on in response to the output voltage of the second conversion unit. The relay switch is coupled to the power supply path and is used to turn the power supply path on or off.

4. The fault detection circuit according to claim 3, characterized in that, It also includes a second detection unit, which is connected in parallel across the coil and configured to generate a second indication signal output to the outside in response to the voltage across the coil.

5. The fault detection circuit according to claim 2, characterized in that, It also includes a third detection unit, which is connected in parallel to the output of the second conversion unit and is configured to generate a third indication signal to be output to the outside in response to the output voltage of the second conversion unit.

6. The fault detection circuit according to claim 1, characterized in that, It also includes a fourth detection unit, one end of which is coupled to the output terminal of the power supply unit, and the other end of which is coupled to the output terminal of the switching element. It is configured to generate a fourth indication signal output to the outside in response to the voltage at the input and output terminals of the switching element.

7. The fault detection circuit according to claim 1, characterized in that, The power supply unit includes: The live wire input terminal is coupled to an external AC power supply and is also coupled to the input terminal of the first conversion unit through the switching element; The neutral input terminal is coupled to the external AC power supply and the input terminal of the first conversion unit.

8. The fault detection circuit according to claim 1, characterized in that, The first indication signal includes at least one of the following: sound indication signal, light indication signal, and information indication signal.

9. The fault detection circuit according to claim 1, characterized in that, The first detection unit includes a light-emitting element for displaying the first indication signal to the outside.

10. A laser, characterized in that, Includes the fault detection circuit described in any one of claims 1-9.

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