Alternating-current overvoltage protection circuit and studio light

Abstract

The present disclosure provides an alternating-current overvoltage protection circuit and a studio light. The alternating-current overvoltage protection circuit comprises a first rectification module (10), a voltage division module (20), a switch control module (30), and an alternating-current relay module (40). When the voltage outputted from a second end of the voltage division module (20) is greater than a preset threshold, the switch control module (30) is in an off state, causing a third end of the alternating-current relay module (40) to be disconnected from an output end. That is, in an overvoltage state, a studio light can be disconnected from an alternating-current power supply to perform overvoltage protection for the studio light, thereby preventing the studio light from being damaged due to overvoltage. When the voltage outputted from the second end of the voltage division module (20) is less than or equal to the preset threshold, the switch control module (30) is in an on state, causing the third end of the alternating-current relay module (40) to be connected to the output end. That is, in a non-overvoltage state, the alternating-current power supply can provide voltage for the studio light, allowing the studio light to operate normally.

Description

AC overvoltage protection circuit and video lights

[0001] This application claims priority to Chinese Patent Application No. 202520126707.0, filed on January 17, 2025, entitled "AC Overvoltage Protection Circuit and Video Light", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electronic circuit technology, and in particular to an AC overvoltage protection circuit and a video lamp. Background Technology

[0003] In film and television shooting, high-powered film and television lights are needed to create the required lighting effects for the scenes. These lights typically require an external AC power supply. However, due to differences in the standards and stability of power supply systems in different regions, there are instances where the connected AC power voltage is too high, which can damage the film and television lights. Therefore, an AC overvoltage protection circuit is needed to protect these lights.

[0004] Utility Model Content

[0005] The main purpose of this disclosure is to provide an AC overvoltage protection circuit and a video lamp that can control the circuit to disconnect when the voltage of the connected AC power supply is too high, so as to provide overvoltage protection for the video lamp.

[0006] To achieve the above objectives, a first aspect of this application provides an AC overvoltage protection circuit, which has an input terminal and an output terminal. The input terminal is used to connect to an AC power supply, and the output terminal is used to connect to a video lamp. The AC overvoltage protection circuit includes a first rectifier module, a voltage divider module, a switch control module, and an AC relay module.

[0007] The first terminal of the first rectifier module is connected to the input terminal, the second terminal of the first rectifier module is connected to the first terminal of the voltage divider module, the second terminal of the voltage divider module is connected to the first terminal of the switch control module, the second terminal of the switch control module is connected to the first terminal of the AC relay module, the second terminal of the AC relay module is connected to the input terminal, and the third terminal of the AC relay module is connected to the output terminal.

[0008] Specifically, when the voltage output from the second terminal of the voltage divider module is greater than a preset threshold, the switch control module is in an open state, thereby disconnecting the third terminal of the AC relay module from the output terminal.

[0009] When the voltage output from the second terminal of the voltage divider module is less than or equal to the preset threshold, the switch control module is in the on state, so that the third terminal of the AC relay module is connected to the output terminal.

[0010] In one embodiment of this application, the AC overvoltage protection circuit further includes a first voltage regulator and filter module, a first terminal of the first voltage regulator and filter module being connected to a second terminal of the voltage divider module, and a second terminal of the first voltage regulator and filter module being connected to a first terminal of the switch control module.

[0011] In one embodiment of this application, the AC overvoltage protection circuit further includes an optocoupler control module, the second terminal of the switch control module is connected to the first terminal of the optocoupler control module, the second terminal of the optocoupler control module is connected to the first terminal of the AC relay module, and the third terminal of the optocoupler control module is connected to the output terminal;

[0012] Specifically, when the voltage output from the second terminal of the voltage divider module is greater than a preset threshold, the switch control module is in an open state, so that the optocoupler control module and the AC relay module are not connected, thereby disconnecting the third terminal of the AC relay module from the output terminal.

[0013] When the voltage output from the second terminal of the voltage divider module is less than or equal to the preset threshold, the switch control module is in the conducting state, which enables the optocoupler control module to conduct with the AC relay module, thereby enabling the third terminal of the AC relay module to conduct with the output terminal.

[0014] In one embodiment of this application, the switch control module includes a first transistor, a second transistor, a first diode, a first Zener diode, and a first resistor;

[0015] The base of the first transistor is connected to the second terminal of the voltage divider module, the emitter of the first transistor is connected to the emitter of the second transistor, the emitter of the first transistor is also connected to the first terminal of the first resistor, the second terminal of the first resistor is connected to the base of the second transistor, the collector of the first transistor is connected to the cathode of the first diode, the anode of the first diode is connected to the cathode of the first Zener diode, the anode of the first Zener diode is connected between the second terminal of the first resistor and the base of the second transistor, the collector of the second transistor is connected to the first terminal of the optocoupler control module, and the anode of the first diode and the cathode of the first Zener diode are also connected to the fourth terminal of the optocoupler control module.

[0016] In one embodiment of this application, the optocoupler control module includes an optocoupler switch, a bidirectional thyristor, a second resistor, a third resistor, a first adjustable resistor, a second adjustable resistor, and a first capacitor;

[0017] The first terminal of the optocoupler switch is connected to the collector of the second transistor, the second terminal of the optocoupler switch is connected to the anode of the first diode and the cathode of the first Zener diode, the third terminal of the optocoupler switch is connected to the control electrode of the bidirectional thyristor, the third terminal of the optocoupler switch is also connected to the first terminal of the second resistor, and the second terminal of the second resistor is connected to the cathode of the bidirectional thyristor and then connected together to the output terminal.

[0018] The fourth terminal of the optocoupler switch is connected to the first terminal of the third resistor, the second terminal of the third resistor is connected to the first terminal of the first adjustable resistor, the second terminal of the first adjustable resistor is connected to the first terminal of the first capacitor, and the second terminal of the first capacitor is connected to the output terminal.

[0019] The anode of the bidirectional thyristor is connected to the first terminal of the second adjustable resistor, the second terminal of the second adjustable resistor is connected to the first terminal of the AC relay module, and the first terminal of the second adjustable resistor is also connected between the second terminal of the third resistor and the first terminal of the first adjustable resistor.

[0020] In one embodiment of this application, the AC overvoltage protection circuit further includes an alarm module and an AC-to-DC power supply module. The first terminal of the AC-to-DC power supply module is connected to the input terminal, the second terminal of the AC-to-DC power supply module is connected to the first terminal of the alarm module, and the second terminal of the alarm module is connected to the third terminal of the switch control module.

[0021] In one embodiment of this application, when the voltage output from the second terminal of the voltage divider module is greater than a preset threshold, the switch control module is turned on, causing the alarm module to turn on and issue an alarm; when the voltage output from the second terminal of the voltage divider module is less than or equal to the preset threshold, the switch control module is turned off, causing the alarm module to turn off and not issue an alarm.

[0022] In one embodiment of this application, the AC overvoltage protection circuit includes a second rectifier module, a first terminal of which is connected to the input terminal, and a second terminal of which is connected to the second terminal of the alarm module.

[0023] In one embodiment of this application, the AC overvoltage protection circuit further includes any one or more of a second filter and voltage regulator module and a step-down module;

[0024] The first terminal of the second filtering and voltage regulating module is connected to the second terminal of the second rectifier module, and the second terminal of the second filtering and voltage regulating module is connected to the second terminal of the alarm module;

[0025] The first end of the step-down module is connected to the input end, and the second end of the step-down module is connected to the first end of the second rectifier module.

[0026] To achieve the above objectives, a second aspect of the present application provides a video lamp that includes the AC overvoltage protection circuit described in any embodiment of the present application.

[0027] In the technical solution provided in this application embodiment, the AC overvoltage protection circuit includes a first rectifier module, a voltage divider module, a switch control module, and an AC relay module. When the voltage output from the second terminal of the voltage divider module exceeds a preset threshold, the switch control module is in an open state, thereby disconnecting the third terminal of the AC relay module from its output terminal. This disconnects the video lamp from the AC power supply under overvoltage conditions, providing overvoltage protection and preventing damage to the video lamp. When the voltage output from the second terminal of the voltage divider module is less than or equal to the preset threshold, the switch control module is in a closed state, connecting the third terminal of the AC relay module to its output terminal. This allows the AC power supply to provide voltage to the video lamp under non-overvoltage conditions, enabling the video lamp to operate normally. Attached Figure Description

[0028] Figure 1 is a first circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0029] Figure 2 is a second circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0030] Figure 3 is a third circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0031] Figure 4 is a fourth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0032] Figure 5 is a fifth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0033] Figure 6 is a sixth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0034] Figure 7 is a seventh circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0035] Figure 8 is an eighth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0036] Figure 9 is a ninth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0037] Figure 10 is a circuit diagram of an AC overvoltage protection circuit provided in an embodiment of this application.

[0038] Explanation of reference numerals in the attached diagram: First rectifier module 10, voltage divider module 20, switch control module 30, optocoupler control module 40, AC relay module 50, filter module 60, first voltage regulator and filter module 70, alarm module 80, AC to DC power supply module 90, second rectifier module 910, second filter and voltage regulator module 920, step-down module 930, fuse 100. Detailed Implementation

[0039] Typical embodiments embodying the features and advantages of this disclosure will be described in detail in the following description. It should be understood that this disclosure can have various variations in different embodiments without departing from the scope of this disclosure, and the descriptions and illustrations therein are for illustrative purposes only and not intended to limit this disclosure.

[0040] In the description of this application, it should be understood that, in the embodiments shown in the accompanying drawings, the indications of direction or positional relationships (such as up, down, left, right, front, and back) are merely for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. These descriptions are appropriate when these elements are in the positions shown in the accompanying drawings. If the description of the positions of these elements changes, these directional indications also change accordingly.

[0041] Furthermore, the terms "first" and "second" are configured for descriptive 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 one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0042] In film and television shooting, high-powered film and television lights are needed to create the required lighting effects for the scenes. These lights typically require an external AC power supply. However, due to differences in the standards and stability of power supply systems in different regions, there are instances where the connected AC power voltage is too high, which can damage the film and television lights. Therefore, an AC overvoltage protection circuit is needed to protect these lights.

[0043] Based on this, this application provides an AC overvoltage protection circuit that can control the circuit to disconnect when the connected AC power supply voltage is too high, so as to protect the video lamp from overvoltage and prevent the video lamp from being damaged due to overvoltage.

[0044] Referring to Figure 1, which is a first circuit block diagram of an AC overvoltage protection circuit according to an embodiment of this application, the AC overvoltage protection circuit has an input terminal J1 and an output terminal J2. The input terminal J1 is used to connect to an AC power supply, and the output terminal J2 is used to connect to a video lamp. The AC overvoltage protection circuit includes a first rectifier module 10, a voltage divider module 20, a switch control module 30, and an AC relay module 50.

[0045] The first terminal of the first rectifier module 10 is connected to the input terminal J1, the second terminal of the first rectifier module 10 is connected to the first terminal of the voltage divider module 20, the second terminal of the voltage divider module 20 is connected to the first terminal of the switch control module 30, the second terminal of the switch control module 30 is connected to the first terminal of the AC relay module 50, the second terminal of the AC relay module 50 is connected to the input terminal J1, and the third terminal of the AC relay module 50 is connected to the output terminal J2.

[0046] The first rectifier module 10 has its first terminal connected to the input terminal J1, meaning its first terminal is connected to an AC power source to convert AC power into DC power. In an AC system, the directions of voltage and current constantly change. The first rectifier module 10 utilizes the unidirectional conductivity of diodes to ensure that current flows in only one direction, thus converting AC power into unidirectional pulsating DC power. The first rectifier module 10 may include a half-wave rectifier circuit, a full-wave rectifier circuit (such as a bridge full-wave rectifier), etc.

[0047] Voltage divider module 20 is connected to the first rectifier module 10 and is used to divide the voltage output from the first rectifier module 10. Voltage divider module 20 can be a voltage divider circuit. Specifically, it can utilize the voltage division principle of resistors and Ohm's law to achieve voltage distribution through series resistors. In the voltage divider circuit, two resistors are connected in series to form a resistor network, with one resistor connected to the input voltage and the other connected to ground. The output voltage is a portion of the input voltage, and its magnitude depends on the resistance ratio of the two resistors. By adjusting the resistance values, the desired voltage division ratio can be achieved, thereby obtaining the required output voltage.

[0048] The second terminal of the AC relay module 50 is connected to the input terminal J1, that is, the AC relay module 50 is connected to the AC power supply and is powered by the AC power supply.

[0049] In this embodiment, considering that the voltage after voltage division by the voltage divider module 20 may still be too high, potentially causing damage to the video lamp due to overvoltage, a switch control module 30 and an AC relay module 50 are sequentially connected after the voltage divider module 20. This ensures that when the voltage output from the second terminal of the voltage divider module 20 exceeds a preset threshold, the switch control module 30 is in an open state, disconnecting the third terminal of the AC relay module 50 from its output terminal J2. This disconnects the video lamp from the AC power supply during overvoltage conditions, providing overvoltage protection and preventing damage. When the voltage output from the second terminal of the voltage divider module 20 is less than or equal to the preset threshold, the switch control module 30 is in a conducting state, connecting the third terminal of the AC relay module 50 to its output terminal J2. This allows the AC power supply to provide voltage to the video lamp during non-overvoltage conditions, enabling the video lamp to operate normally.

[0050] Referring to Figure 2, which is a second circuit block diagram of an AC overvoltage protection circuit according to an embodiment of this application, the AC overvoltage protection circuit includes a first rectifier module 10, a voltage divider module 20, a switch control module 30, an AC relay module 50, and a filter module 60. The first terminal of the filter module 60 is connected to the second terminal of the first rectifier module 10, and the second terminal of the filter module 60 is connected to the first terminal of the voltage divider module 20. That is, the filter module 60 is connected between the first rectifier module 10 and the voltage divider module 20. The filter module 60 may include a filter capacitor. The filter capacitor smooths the AC signal through the charging and discharging process, removing unwanted AC components and retaining the DC component, thereby providing a stable DC output.

[0051] Referring to Figure 3, which is a third circuit block diagram of an AC overvoltage protection circuit according to an embodiment of this application, the AC overvoltage protection circuit includes a first rectifier module 10, a filter module 60, a voltage divider module 20, a switch control module 30, and an AC relay module 50, as well as a first voltage stabilizing and filtering module 70. The first terminal of the first voltage stabilizing and filtering module 70 is connected to the second terminal of the voltage divider module 20, and the second terminal of the first voltage stabilizing and filtering module 70 is connected to the first terminal of the switch control module 30. That is, the first voltage stabilizing and filtering module 70 is connected between the voltage divider module 20 and the switch control module 30. The first voltage stabilizing and filtering module 70 may include a voltage stabilizing section and a filtering section. The voltage stabilizing section may include a Zener diode, which is used to control the voltage fluctuations output by the voltage divider module 20 within a certain range, ensuring that the output voltage remains stable and avoiding frequent switching of circuit conduction or disconnection due to voltage fluctuations. The filtering section may include resistors and capacitors. The filtering section is used to further remove AC components and noise components from the output of the voltage divider module 20, making the output voltage more stable. Specifically, the filtering section utilizes the energy storage and release characteristics of capacitors to filter the signal output from the voltage divider module 20. Capacitors can be used to store charge, smooth voltage fluctuations, and especially filter out AC components to reduce output voltage ripple. Resistors can be used to control current or, together with capacitors, form an RC filter, thereby controlling the filter's frequency response.

[0052] Referring to Figure 4, which is a fourth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application, the AC overvoltage protection circuit includes a first rectifier module 10, a filter module 60, a voltage divider module 20, a first voltage regulator and filter module 70, a switch control module 30, an AC relay module 50, and an optocoupler control module 40. The second terminal of the switch control module 30 is connected to the first terminal of the optocoupler control module 40, the second terminal of the optocoupler control module 40 is connected to the first terminal of the AC relay module 50, and the third terminal of the optocoupler control module 40 is connected to the output terminal J2. That is, the optocoupler control module 40 is connected between the switch control module 30 and the AC relay module 50, and the optocoupler control module 40 is also connected to the output terminal J2. Specifically, when the voltage output from the second terminal of the voltage divider module 20 exceeds a preset threshold, the switch control module 30 is in the off state, preventing the optocoupler control module 40 and the AC relay module 50 from conducting. This disconnects the third terminal of the AC relay module 50 from its output terminal J2, thus disconnecting the connection between the video light and the AC power supply under overvoltage conditions to protect the video light from damage. When the voltage output from the second terminal of the voltage divider module 20 is less than or equal to the preset threshold, the switch control module 30 is in the on state, connecting the optocoupler control module 40 and the AC relay module 50. This connects the third terminal of the AC relay module 50 to its output terminal J2, allowing the AC power supply to provide voltage to the video light under non-overvoltage conditions, enabling the video light to operate normally.

[0053] Referring to Figure 5, which is a fifth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application, the AC overvoltage protection circuit includes, in addition to a first rectifier module 10, a filter module 60, a voltage divider module 20, a first voltage regulator and filter module 70, a switch control module 30, an optocoupler control module 40, and an AC relay module 50, an alarm module 80 and an AC-to-DC power supply module 90. The first terminal of the AC-to-DC power supply module 90 is connected to the input terminal J1, used to connect to an external AC power source and convert AC to DC. The second terminal of the AC-to-DC power supply module 90 is connected to the first terminal of the alarm module 80, and the second terminal of the alarm module 80 is connected to the third terminal of the switch control module 30. The AC-to-DC power supply module 90 supplies power to the alarm module 80. When the voltage output from the second terminal of the voltage divider module 20 is greater than a preset threshold, the switch control module 30 can control the alarm module 80 to conduct to issue an alarm. When the voltage output from the second terminal of the voltage divider module 20 is less than or equal to the preset threshold, the switch control module 30 can control the alarm module 80 to not conduct and not issue an alarm. That is, through the settings of alarm module 80, an alarm can be issued in the case of overvoltage to indicate that the voltage connected to the video light is too high.

[0054] The alarm module 80 may include an audible alarm circuit, a visual alarm circuit, or an audible-visual alarm circuit. Specifically, the alarm module 80 may employ an audible alarm circuit, which can emit an audible alarm to alert the user when the voltage output at the second terminal of the voltage divider module 20 is too high. Alternatively, the alarm module 80 may employ an audible-visual alarm circuit, which can simultaneously emit both audible and visual alarms to alert the user when the voltage output at the second terminal of the voltage divider module 20 is too high.

[0055] Referring to Figure 6, which is a sixth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application, the AC overvoltage protection circuit includes, in addition to the first rectifier module 10, filter module 60, voltage divider module 20, first voltage regulator and filter module 70, switch control module 30, alarm module 80, optocoupler control module 40, and AC relay module 50, a second rectifier module 910. That is, the AC-to-DC power supply module 90 includes the second rectifier module 910, wherein the first terminal of the second rectifier module 910 is connected to the input terminal J1, and the second terminal of the second rectifier module 910 is connected to the second terminal of the alarm module 80.

[0056] In this embodiment, a second rectifier module 910 can be provided to connect to the input terminal J1, i.e., to connect to an AC power source, to convert AC power into DC power. The converted voltage is then supplied to the alarm module 80 to provide power to the alarm module 80. Similarly, in an AC system, the directions of voltage and current constantly change. The second rectifier module 910 utilizes the unidirectional conductivity of diodes to ensure that current flows in only one direction, thereby converting AC power into unidirectional pulsating DC power. The second rectifier module 910 may include a half-wave rectifier circuit, a full-wave rectifier circuit (such as a bridge full-wave rectifier), etc. By using the second rectifier module 910 to convert AC power into DC power before providing power to the alarm module 80, an additional power supply module is unnecessary to provide operating voltage to the alarm module 80, thus saving costs.

[0057] Referring to Figure 7, which is a seventh circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application, the AC overvoltage protection circuit includes, in addition to the first rectifier module 10, filter module 60, voltage divider module 20, first voltage regulator and filter module 70, switch control module 30, second rectifier module 910, alarm module 80, optocoupler control module 40, and AC relay module 50, a second filter and voltage regulator module 920. That is, the AC-to-DC power supply module 90 may also include the second filter and voltage regulator module 920. The first end of the second filter and voltage regulator module 920 is connected to the second end of the second rectifier module 910, and the second end of the second filter and voltage regulator module 920 is connected to the second end of the alarm module 80. In other words, the second filter and voltage regulator module 920 is connected between the second rectifier module 910 and the alarm module 80. By setting the second filter and voltage regulator module 920, a stable voltage can be provided to the alarm module 80. Similarly, the second voltage regulator module 100 may include a voltage regulator section and a filter section. The voltage regulation section may include a Zener diode. This section controls voltage fluctuations at the output of the second rectifier module 910 within a certain range, ensuring stable output voltage. The filtering section may include resistors and capacitors. This section further removes AC and noise components from the output of the second rectifier module 910, resulting in a smoother output voltage. Specifically, the filtering section utilizes the energy storage and release characteristics of capacitors to filter the signal output from the second rectifier module 910. Capacitors can store charge, smooth voltage fluctuations, and are particularly effective at filtering AC components and reducing output voltage ripple. Resistors can be used to control current or, together with capacitors, form an RC filter to control the filter's frequency response.

[0058] Referring to Figure 8, which is an eighth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application, the AC overvoltage protection circuit includes, in addition to a first rectifier module 10, a filter module 60, a voltage divider module 20, a first voltage regulator and filter module 70, a switch control module 30, a second rectifier module 910, a second filter and voltage regulator module 920, an alarm module 80, an optocoupler control module 40, and an AC relay module 50, a step-down module 930. That is, the AC-to-DC power supply module 90 may further include a step-down module 930, wherein the first terminal of the step-down module 930 is connected to the input terminal J1, and the second terminal of the step-down module 930 is connected to the first terminal of the second rectifier module 910. The first terminal of the step-down module 930 is connected to the input terminal J1, meaning the step-down module 930 is used to connect to an AC power supply and to reduce the voltage of the AC power supply to a voltage range suitable for the specific circuit. In this embodiment, the voltage of the external AC power supply may be high, while the alarm module 80 operates within a certain voltage range. Therefore, a step-down module 930 is required to reduce the AC power supply to a preset range before supplying it to the alarm module 80, ensuring its normal operation. The step-down module 930 may include a RC step-down circuit, a DC-DC step-down circuit, etc. The RC step-down circuit consists of a capacitor and a resistor connected in series, with the capacitive reactance of the capacitor limiting the maximum operating current. The RC step-down circuit utilizes the capacitive reactance generated by the capacitor under AC signals to limit the maximum operating current, thereby achieving voltage reduction. Specifically, when the input voltage is applied to the step-down module 930, the capacitor begins to charge, and the current flowing through the resistor generates a voltage drop, thus reducing the output voltage. When the input voltage decreases, the capacitor begins to discharge, and the current flowing through the resistor generates a reverse voltage drop, further reducing the output voltage.

[0059] Referring to Figure 9, which is a ninth circuit block diagram of an AC overvoltage protection circuit provided in an embodiment of this application, the AC overvoltage protection circuit includes, in addition to a first rectifier module 10, a filter module 60, a voltage divider module 20, a first voltage regulator and filter module 70, a switch control module 30, a step-down module 930, a second rectifier module 910, a second filter and voltage regulator module 920, an alarm module 80, an optocoupler control module 40, and an AC relay module 50, a fuse 100. The first terminal of the fuse 100 is connected to the input terminal J1, the second terminal of the fuse 100 is connected to the first terminal of the first rectifier module 10, the second terminal of the fuse 100 is also connected to the first terminal of the step-down module 930, and the second terminal of the fuse 100 is also connected to the second terminal of the AC relay module 50.

[0060] In an AC circuit, a fuse 100 connected to the live wire can disconnect the circuit in case of overload or short circuit, protecting electrical equipment (such as video lights) and the circuit itself. The live wire is the active conductor in the circuit, providing power so that electrical equipment (such as video lights) can operate normally. When an overload or short circuit occurs in the circuit, the current in the live wire increases dramatically, which can cause significant damage to electrical equipment (such as video lights) and wiring, and may even cause a fire. Therefore, connecting a fuse 100 can disconnect the circuit in case of a fault, preventing overheating of the wiring, fire, or damage to the video lights. Furthermore, the working principle of the fuse 100 is that when the current in the circuit is too high, the fuse in the fuse 100 generates heat and burns, thus disconnecting the circuit. This design allows the fuse 100 to connect only one fuse to the live wire. When the fuse blows, it is disconnected from the live wire, preventing electric shock upon contact with the circuit and ensuring safety.

[0061] Referring to Figure 10, which is a circuit diagram of an AC overvoltage protection circuit provided in an embodiment of this application, the switch control module 30 includes a first transistor Q6, a second transistor Q7, a first diode D19, a first Zener diode D24, and a first resistor R37. In this configuration, the base of the first transistor Q6 is connected to the second terminal of the first voltage regulator and filter module 70, the emitter of the first transistor Q6 is connected to the emitter of the second transistor Q7, the emitter of the first transistor Q6 is also connected to the first terminal of the first resistor R37, the second terminal of the first resistor R37 is connected to the base of the second transistor Q7, the collector of the first transistor Q6 is connected to the cathode of the first diode D19, the anode of the first diode D19 is connected to the cathode of the first Zener diode D24, the anode of the first Zener diode D24 is connected between the second terminal of the first resistor R37 and the base of the second transistor Q7, the collector of the second transistor Q7 is connected to the first terminal of the optocoupler control module 40, and the anodes of the first diode D19 and the cathode of the first Zener diode D24 are also connected to the fourth terminal of the optocoupler control module 40.

[0062] In this embodiment, when the voltage output from the second terminal of the voltage divider module 20 exceeds a preset threshold, a high potential is output to the base of the first transistor Q6, causing Q6 to conduct. This activates the alarm module 80, issuing an alarm to indicate overvoltage. Simultaneously, after Q6 conducts, the first diode D19 also conducts, pulling down the reverse voltage of the first Zener diode D24. This prevents D24 from reaching its reverse breakdown voltage and keeps it open, resulting in a low potential at the base of the second transistor Q7. Q7 is then in an open state, preventing the optocoupler control module 40 and the AC relay module 50 from conducting. This disconnects the third terminal of the AC relay module 50 from its output terminal J2, thus disconnecting the connection between the video lamp and the AC power supply under overvoltage conditions. This provides overvoltage protection for the video lamp, preventing damage due to overvoltage. When the voltage output from the second terminal of the voltage divider module 20 is less than or equal to a preset threshold, the base of the first transistor Q6 remains open at a low potential, thus preventing the alarm module 80 from conducting. Simultaneously, when the first transistor Q6 is open, the first diode D19 is cut off, and the first Zener diode D24 conducts in reverse, causing the base of the second transistor Q7 to reach a high potential. This turns on the second transistor Q7, connecting the optocoupler control module 40 and the AC relay module 50, thereby establishing a connection between the third terminal of the AC relay module 50 and its output terminal J2. This allows the AC power supply to provide voltage to the video lamp under non-overvoltage conditions, enabling the video lamp to operate normally.

[0063] Referring to Figure 10, the optocoupler control module 40 includes an optocoupler switch U2, a bidirectional thyristor Q5, a second resistor R46, a third resistor R41, a first adjustable resistor R43, a second adjustable resistor R42, and a first capacitor C10. The first terminal of the optocoupler switch U2 is connected to the collector of the second transistor Q7. The second terminal of the optocoupler switch U2 is connected to the anode of the first diode D19 and the cathode of the first Zener diode D24. The third terminal of the optocoupler switch U2 is connected to the control electrode of the bidirectional thyristor Q5. The third terminal of the optocoupler switch U2 is also connected to the first terminal of the second resistor R46. The second terminal of the second resistor R46 is connected to the cathode of the bidirectional thyristor Q5 and then together they are connected to the output terminal J2. The fourth terminal of the optocoupler switch U2 is connected to the first terminal of the third resistor R41. The second terminal of the third resistor R41 is connected to the first terminal of the first adjustable resistor R43. The second terminal of the first adjustable resistor R43 is connected to the first terminal of the first capacitor C10. The second terminal of the first capacitor C10 is connected to the output terminal J2. The anode of the bidirectional thyristor Q5 is connected to the first terminal of the second adjustable resistor R42, the second terminal of the second adjustable resistor R42 is connected to the first terminal of the AC relay module, and the first terminal of the second adjustable resistor R42 is also connected between the second terminal of the third resistor R41 and the first terminal of the first adjustable resistor R43.

[0064] In this embodiment, when the voltage output from the second terminal of the voltage divider module 20 exceeds a preset threshold, a high potential is output to the base of the first transistor Q6, causing the first transistor Q6 to conduct. This activates the alarm module 80, which then issues an alarm to indicate that the voltage is too high. Simultaneously, after the first transistor Q6 conducts, the first diode D19 also conducts, pulling down the reverse voltage of the first Zener diode D24. This prevents the first Zener diode D24 from reaching its reverse breakdown voltage and keeps it open, thus causing the base of the second transistor Q7 to be at a low potential. The second transistor Q7 is in an open state, causing the optocoupler switch U2 to open, the optocoupler control module 30 to have no loop current, and the bidirectional thyristor Q5 to open. This de-energizes the coil inside the AC relay module 50, disconnecting the third terminal of the AC relay module 50 from the output terminal J2 (moving contact 3 and stationary contact 2 are closed), resulting in no voltage supply to the video lamp. This allows the connection between the video light and the AC power supply to be disconnected under overvoltage conditions, providing overvoltage protection and preventing damage to the video light due to overvoltage. When the voltage output from the second terminal of the voltage divider module 20 is less than or equal to a preset threshold, the base of the first transistor Q6 remains at a low potential and is disconnected, thus preventing the alarm module 80 from conducting. Simultaneously, when the first transistor Q6 is disconnected, the first diode D19 is cut off, and the first Zener diode D24 conducts in reverse, causing the base of the second transistor Q7 to reach a high potential. This turns on the second transistor Q7, causing the optocoupler switch U2 to conduct. The optocoupler control module 30 generates a loop current, triggering the bidirectional thyristor Q5 to conduct, thereby energizing the coil inside the AC relay module 50. This makes the third terminal of the AC relay module 50 connected to the output terminal J2 (moving contact 3 and stationary contact 1 are closed), allowing the video light to operate normally. Therefore, the video light can be supplied with voltage by the AC power supply under non-overvoltage conditions, and the video light can operate normally.

[0065] It should be noted that the specific circuit structures corresponding to each module shown in the circuit diagram of Figure 10 are only one example of the circuit structure of each module. The circuit structures of each module in this application are not limited to those shown in Figure 10, and may include other variations. For example, in addition to the three-contact relay shown in Figure 10, the AC relay module 50 may also include normally open contact relays and normally closed contact relays.

[0066] This application also proposes a video lamp, including the AC overvoltage protection circuit provided in any embodiment of this application. The power interface of the video lamp is connected to the output terminal J2 of the AC overvoltage protection circuit, and the input terminal J1 of the AC overvoltage protection circuit is connected to an external AC power source, thus allowing the video lamp to be powered by an external AC power source. Furthermore, the external AC power source passes through the AC overvoltage protection circuit before being connected to the video lamp, enabling the control circuit to disconnect when the voltage of the connected AC power source is too high, thereby protecting the video lamp from overvoltage damage.

[0067] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0068] Although this disclosure has been described with reference to several typical embodiments, it should be understood that the terminology used is descriptive and exemplary, and not restrictive. Because this disclosure can be embodied in many forms without departing from the spirit or substance of the disclosure, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An AC overvoltage protection circuit, the AC overvoltage protection circuit having an input terminal and an output terminal, the input terminal being used to connect to an AC power supply, the output terminal being used to connect to a video lamp, the AC overvoltage protection circuit comprising a first rectifier module, a voltage divider module, a switch control module, and an AC relay module; The first terminal of the first rectifier module is connected to the input terminal, the second terminal of the first rectifier module is connected to the first terminal of the voltage divider module, the second terminal of the voltage divider module is connected to the first terminal of the switch control module, the second terminal of the switch control module is connected to the first terminal of the AC relay module, the second terminal of the AC relay module is connected to the input terminal, and the third terminal of the AC relay module is connected to the output terminal. wherein When the voltage output from the second terminal of the voltage divider module is greater than a preset threshold, the switch control module is in an open state, thereby disconnecting the third terminal of the AC relay module from the output terminal. When the voltage output from the second terminal of the voltage divider module is less than or equal to the preset threshold, the switch control module is in the on state, so that the third terminal of the AC relay module is connected to the output terminal.

2. The AC overvoltage protection circuit of claim 1, wherein, The AC overvoltage protection circuit further includes a first voltage regulator and filter module, the first end of which is connected to the second end of the voltage divider module, and the second end of which is connected to the first end of the switch control module.

3. The AC overvoltage protection circuit of claim 1, wherein, The AC overvoltage protection circuit also includes an optocoupler control module. The second terminal of the switch control module is connected to the first terminal of the optocoupler control module, the second terminal of the optocoupler control module is connected to the first terminal of the AC relay module, and the third terminal of the optocoupler control module is connected to the output terminal. When the voltage output from the second terminal of the voltage divider module is greater than a preset threshold, the switch control module is in an open state, so that the optocoupler control module and the AC relay module are not connected, thereby disconnecting the third terminal of the AC relay module from the output terminal. When the voltage output from the second terminal of the voltage divider module is less than or equal to the preset threshold, the switch control module is in the conducting state, which enables the optocoupler control module to conduct with the AC relay module, thereby enabling the third terminal of the AC relay module to conduct with the output terminal.

4. The AC overvoltage protection circuit of claim 3, wherein, The switch control module includes a first transistor, a second transistor, a first diode, a first Zener diode, and a first resistor; The base of the first transistor is connected to the second terminal of the voltage divider module, the emitter of the first transistor is connected to the emitter of the second transistor, the emitter of the first transistor is also connected to the first terminal of the first resistor, the second terminal of the first resistor is connected to the base of the second transistor, the collector of the first transistor is connected to the cathode of the first diode, the anode of the first diode is connected to the cathode of the first Zener diode, the anode of the first Zener diode is connected between the second terminal of the first resistor and the base of the second transistor, the collector of the second transistor is connected to the first terminal of the optocoupler control module, and the anode of the first diode and the cathode of the first Zener diode are also connected to the fourth terminal of the optocoupler control module.

5. The AC overvoltage protection circuit of claim 4, wherein, The optocoupler control module includes an optocoupler switch, a bidirectional thyristor, a second resistor, a third resistor, a first adjustable resistor, a second adjustable resistor, and a first capacitor; The first terminal of the optocoupler switch is connected to the collector of the second transistor, the second terminal of the optocoupler switch is connected to the anode of the first diode and the cathode of the first Zener diode, the third terminal of the optocoupler switch is connected to the control electrode of the bidirectional thyristor, the third terminal of the optocoupler switch is also connected to the first terminal of the second resistor, and the second terminal of the second resistor is connected to the cathode of the bidirectional thyristor and then connected together to the output terminal. The fourth terminal of the optocoupler switch is connected to the first terminal of the third resistor, the second terminal of the third resistor is connected to the first terminal of the first adjustable resistor, the second terminal of the first adjustable resistor is connected to the first terminal of the first capacitor, and the second terminal of the first capacitor is connected to the output terminal. The anode of the bidirectional thyristor is connected to the first terminal of the second adjustable resistor, the second terminal of the second adjustable resistor is connected to the first terminal of the AC relay module, and the first terminal of the second adjustable resistor is also connected between the second terminal of the third resistor and the first terminal of the first adjustable resistor.

6. The AC overvoltage protection circuit of claim 1, wherein, The AC overvoltage protection circuit also includes an alarm module and an AC-to-DC power supply module. The first end of the AC-to-DC power supply module is connected to the input terminal, the second end of the AC-to-DC power supply module is connected to the first end of the alarm module, and the second end of the alarm module is connected to the third end of the switch control module.

7. The AC overvoltage protection circuit of claim 6, wherein, When the voltage output from the second terminal of the voltage divider module is greater than a preset threshold, the switch control module is turned on, causing the alarm module to turn on and issue an alarm; when the voltage output from the second terminal of the voltage divider module is less than or equal to the preset threshold, the switch control module is turned off, causing the alarm module to turn off and not issue an alarm.

8. The AC overvoltage protection circuit of claim 6, wherein, The alarm module includes any one of the following: an audible alarm circuit, a visual alarm circuit, and an audible and visual alarm circuit.

9. The AC overvoltage protection circuit of claim 6, wherein, The AC-to-DC power supply module includes a second rectifier module, the first end of which is connected to the input terminal, and the second end of which is connected to the second end of the alarm module.

10. The AC overvoltage protection circuit of claim 9, wherein, The AC-to-DC power supply module also includes a second filter and voltage regulator module. The first end of the second filter and voltage regulator module is connected to the second end of the second rectifier module, and the second end of the second filter and voltage regulator module is connected to the second end of the alarm module.

11. The AC overvoltage protection circuit according to claim 9 or 10, wherein The AC-to-DC power supply module also includes a step-down module, with the first end of the step-down module connected to the input end and the second end of the step-down module connected to the first end of the second rectifier module.

12. The AC overvoltage protection circuit of claim 11, wherein, The AC overvoltage protection circuit also includes a fuse. The first end of the fuse is connected to the input terminal, the second end of the fuse is connected to the first end of the first rectifier module, the second end of the fuse is also connected to the first end of the step-down module, and the second end of the fuse is also connected to the second end of the AC relay module.

13. The AC overvoltage protection circuit of claim 1, wherein, The AC overvoltage protection circuit also includes a filter module, the first end of which is connected to the second end of the first rectifier module, and the second end of which is connected to the first end of the voltage divider module.

14. A video lighting fixture, comprising the AC overvoltage protection circuit as described in any one of claims 1-13.

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