Control circuit and method of laser tube

Abstract

The invention discloses a control circuit and method of a laser tube. The control circuit comprises a driving circuit and a switching circuit, the driving circuit is connected with the switching circuit; the driving circuit is used for providing working current for the laser tube; and the switching circuit is used for turning off the driving work of the driving circuit under the condition that the power supply voltage of the driving circuit is smaller than the minimum working voltage of the driving circuit.

Description

Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a control circuit and method for a laser tube. Background Art

[0002] Laser tubes are fragile and expensive devices that cannot be repaired once damaged. However, the circuit that drives the laser tube is usually equipped with an error amplifier. The error amplifier has a minimum operating voltage, and it takes time for the power supply voltage to rise to this minimum operating voltage. During this period of time, the error amplifier will have a false output. If this output is not taken into account, it may cause the laser tube operating current to exceed the absolute rated maximum, resulting in damage. In related technologies, current-limiting resistors are added to limit abnormal current. Even if the drive circuit outputs incorrectly, the laser tube will not be damaged by overvoltage or overcurrent. However, the voltage drop of different laser tubes varies greatly. If the current-limiting resistor is too large, it may prevent the laser tube from adjusting to the set current (limited by insufficient compliance voltage). If it is too small, it will not provide protection and the control accuracy will be poor. Summary of the Invention

[0003] The embodiments of the present application aim to provide a control circuit and method for a laser tube.

[0004] The technical solution of the embodiment of the present application is implemented as follows:

[0005] The embodiment of the present application provides a control circuit, a driving circuit and a switching circuit of a laser tube; the driving circuit is connected to the switching circuit;

[0006] Driving circuit, used to provide operating current for the laser tube;

[0007] The switch circuit is used to shut down the driving operation of the driving circuit when the power supply voltage of the driving circuit is lower than the minimum operating voltage of the driving circuit.

[0008] In the above circuit, the switch circuit is connected to the base of the first switch tube in the drive circuit and is also used to turn off the first switch tube when the power supply voltage of the drive circuit is less than the minimum operating voltage of the drive circuit; the first switch tube is connected to the cathode of the laser tube and is used to output the operating current provided by the drive circuit to the laser tube.

[0009] In the above circuit, the switching circuit includes a first Zener tube and a second switching tube; the second switching tube is connected to the anode of the first Zener tube via the collector, and is used to input the ground voltage of the emitter into the anode of the first Zener tube when it is turned on; the first Zener tube is connected to the base of the first switching tube via the cathode, and is used to input the ground voltage of the second switching tube into the first switching tube, enabling the first switching tube to be turned off.

[0010] In the above circuit, the switching circuit includes a first unidirectional tube, a second unidirectional tube, and a second switching tube; the second switching tube is connected to the anode of the first unidirectional tube via the collector, and is used to input the ground voltage of the emitter into the anode of the first unidirectional tube when it is turned on; the first unidirectional tube is connected to the non-inverting terminal of the first operational amplifier in the driving circuit via the cathode, and is used to input the ground voltage of the input second switching tube into the non-inverting terminal of the first operational amplifier; the second unidirectional tube is connected to the first negative power supply via the cathode and the anode is connected to the inverting terminal of the first operational amplifier, and is used to input the voltage provided by the first negative power supply into the inverting terminal of the first operational amplifier; the first operational amplifier has an output terminal connected to the base of the first switching tube, and is used to output the ground voltage input to the non-inverting terminal to the first switching tube, so as to enable the first switching tube to be turned off.

[0011] In the above circuit, the control circuit also includes a switch control circuit, and the switch circuit also includes a third switch tube; the switch control circuit is connected to the base of the third switch tube, and is used to control the base of the third switch tube to be in a high-impedance state when the power supply voltage of the drive circuit is less than the minimum operating voltage of the drive circuit; the third switch tube is connected to the base of the second switch tube through the collector, and is used to turn on the second switch tube in the high-impedance state using the voltage provided by the first negative power supply.

[0012] In the above circuit, the switch control circuit is also used to input the voltage provided by the second negative power supply in the switch control circuit into the base of the third switch tube when the power supply voltage of the drive circuit is greater than or equal to the minimum operating voltage of the drive circuit, so as to turn on the third switch tube and start the driving operation of the drive circuit.

[0013] In the above circuit, the third switching tube is further used to input the ground voltage of the emitter of the third switching tube into the base of the second switching tube and the cathode of the second unidirectional tube respectively when it is turned on, so that the second switching tube and the second unidirectional tube are not turned on; the second switching tube is also used to control the first unidirectional tube and the first voltage-stabilizing tube to not be turned on; the first unidirectional tube and the first voltage-stabilizing tube are reverse-biased tubes to each other.

[0014] In the above circuit, the switch control circuit includes a fourth switching tube, a fifth switching tube, a sixth switching tube, a level input terminal, a positive power supply and a second negative power supply; the fourth switching tube is connected to the level input terminal through the base, the collector is connected to the positive power supply and the base of the fifth switching tube respectively, and the emitter is grounded, and is used to maintain a high-impedance state when a low level is input to the level input terminal; the fifth switching tube is connected to the positive power supply through the base, the emitter is connected to the positive power supply, and the collector is connected to the base of the sixth switching tube, and is used to maintain a high-impedance state when the fourth switch is in a high-impedance state; the sixth switching tube is connected to the second negative power supply through the emitter, and the collector is connected to the base of the third switching tube, and is used to maintain a high-impedance state when the fifth switching tube is in a high-impedance state.

[0015] In the above circuit, the fourth switch tube is further used to input the ground voltage of the emitter into the base of the fifth switch tube when a high level is input to the level input terminal, so as to enable the fifth switch tube to be turned on; the fifth switch tube is further used to input the voltage provided by the positive power supply into the base of the sixth switch tube when it is turned on, so as to enable the sixth switch tube to be turned on; the sixth switch tube is further used to input the voltage provided by the second negative power supply into the base of the third switch tube when it is turned on, so as to enable the third switch tube to be turned on.

[0016] An embodiment of the present application provides a control method for a laser tube, which is applied to a control circuit, wherein the control circuit includes: a drive circuit and a switch circuit; the drive circuit is connected to the switch circuit; the drive circuit provides an operating current for the laser tube; and the switch circuit shuts off the driving operation of the drive circuit when the power supply voltage of the drive circuit is less than the minimum operating voltage of the drive circuit.

[0017] The embodiments of the present application provide a control circuit and method for a laser tube. The control circuit includes: a drive circuit and a switch circuit; the drive circuit is connected to the switch circuit; the drive circuit is configured to provide an operating current to the laser tube; and the switch circuit is configured to shut down the drive circuit's driving operation when the drive circuit's power supply voltage is less than the drive circuit's minimum operating voltage. The control circuit for a laser tube provided in the embodiments of the present application adds a switch circuit to an existing laser tube drive circuit. This switch circuit can completely shut down the drive circuit's driving operation when the drive circuit's power supply voltage is less than the drive circuit's minimum operating voltage. This protects the laser tube and improves the accuracy of the control circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagrams of the structures of three types of laser tubes provided in the embodiments of the present application;

[0019] Figure 2 A simulation diagram of driving a laser tube based on an existing driving circuit provided in an embodiment of the present application;

[0020] Figure 3 A schematic diagram of a control circuit for a laser tube based on a constant current drive circuit according to an exemplary embodiment of the present application Figure 1 ;

[0021] Figure 4 A schematic diagram of the structure of a control circuit of a laser tube based on a constant power drive circuit provided in an embodiment of the present application Figure 1 ;

[0022] Figure 5 A schematic diagram of a control circuit for a laser tube based on a constant current drive circuit according to an exemplary embodiment of the present application Figure 2 ;

[0023] Figure 6 A schematic diagram of the structure of a control circuit of a laser tube based on a constant power drive circuit provided in an embodiment of the present application Figure 2 ;

[0024] Figure 7 A schematic diagram of a control circuit for a laser tube based on a constant current drive circuit according to an exemplary embodiment of the present application Figure 3 ;

[0025] Figure 8 A schematic diagram of the structure of a control circuit of a laser tube based on a constant power drive circuit provided in an embodiment of the present application Figure 3 ;

[0026] Figure 9 A schematic diagram of a control circuit for a laser tube based on a constant current drive circuit according to an exemplary embodiment of the present application Figure 4 ;

[0027] Figure 10 A schematic diagram of the structure of a control circuit of a laser tube based on a constant power drive circuit provided in an embodiment of the present application Figure 4 ;

[0028] Figure 11 A schematic diagram of a control circuit for a laser tube based on a constant current drive circuit according to an exemplary embodiment of the present application Figure 5 ;

[0029] Figure 12 A schematic diagram of the structure of a control circuit of a laser tube based on a constant power drive circuit provided in an embodiment of the present application Figure 5 ;

[0030] Figure 13 A schematic flow chart of a laser tube control method provided in an embodiment of the present application;

[0031] Figure 14 A simulation diagram of a laser tube driven by a control circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in this application. It should be understood that the specific embodiments described herein are only used to explain the related application and are not intended to limit the application. It should also be noted that for ease of description, only the parts relevant to the related application are shown in the drawings.

[0033] like Figure 1FIG. 1 shows an exemplary laser tube structure diagram. Laser tube 10 can include a cathode-connected laser tube 11, an anode-connected laser tube 12, and a floating laser tube 13. In existing technologies, driver circuits are typically designed for cathode-connected laser tubes, while fewer driver circuits are typically designed for anode-connected laser tubes. However, anode-connected laser tubes are required for red lasers in flow cytometers.

[0034] An error amplifier is usually installed when driving a laser tube connected to the shell. The error amplifier takes time for the power supply voltage to rise to the minimum operating voltage. During this time, the error amplifier will have a false output. If this output is not taken into consideration, it may cause the laser tube operating current to exceed the absolute maximum rating, resulting in damage. Figure 2 As shown in the figure, if the switching circuit fails during power-on, the laser tube current will reach the maximum current (I(Ld)) even if the setting value is 0, which may exceed the absolute maximum rating of the laser tube and cause damage.

[0035] Currently, laser tubes are protected by adding current-limiting resistors. This can indeed limit abnormal currents. Even if the driver (including the driver circuit of the error amplifier) outputs an error, the laser tube will not be damaged due to overcurrent or overvoltage. However, the biggest problem with this circuit is its poor compatibility. This is because the voltage drop of laser tubes of the same model may vary greatly. Therefore, if the current-limiting resistor is too large, some laser tubes may not be able to adjust to the set current (due to insufficient compliance voltage). If it is too small, it will not provide protection.

[0036] Based on the above problems, this application provides a control circuit for a laser tube. Figure 3 This is a schematic diagram of the structure of a control circuit of a laser tube provided in an embodiment of the present application.

[0037] like Figure 3 As shown, the control circuit 30 includes: a driving circuit 31 and a switching circuit 32; the driving circuit 31 is connected to the switching circuit 32; the driving circuit 31 is used to provide an operating current to the laser tube 33; the switching circuit 32 is used to shut down the driving operation of the driving circuit 31 when the power supply voltage of the driving circuit 31 is less than the minimum operating voltage of the driving circuit 31.

[0038] In the embodiment of the present application, the driving circuit can be a constant current driving circuit or a constant power driving circuit, and the driving circuit is used to provide the operating current for the laser tube, wherein the laser tube is Figure 1 The anode-connected shell laser tube 12 is shown.

[0039] For example, Figure 3As shown, an exemplary constant current driving circuit 31 is provided, wherein the constant current driving circuit 31 includes a current setter 310 of the laser tube 33, a filter circuit 311, an error amplifier circuit 312, a negative feedback circuit 313, and a protection circuit 314 of the laser tube 33.

[0040] Among them, the laser tube setter 310 is a voltage input for setting the current, which can be replaced by a sliding resistor or a digital-to-analog converter (DAC) and related circuits. The set voltage can be -4V, -2V, or -5V, and the set voltage can affect the operating current of the laser tube.

[0041] The filter circuit 311 includes a first filter resistor 3111, a second filter resistor 3112, and a filter capacitor 3113; one end of the first filter resistor 3111 is connected to the current setter 310, and the other end is connected to the second filter resistor 3112 and the filter capacitor 3113 respectively; the other end of the filter capacitor 3113 is grounded, and the other end of the second filter resistor 3112 is connected to the error amplifier circuit 312.

[0042] The error amplifier circuit 312 includes a first operational amplifier 3121, a loop compensation capacitor 3122, a first current-limiting resistor 3123, a filter bypass capacitor 3124, a first switching transistor 3125, and a second current-limiting resistor 3126. The inverting terminal of the first operational amplifier 3121 is connected to the second filter resistor 3112 and the loop compensation capacitor 3122, respectively. The non-inverting terminal of the first operational amplifier 3121 is connected to the negative feedback circuit 313. The output terminal of the first operational amplifier 3121 is connected to the loop compensation capacitor 3122 and the first current-limiting resistor 3123, respectively. The first current-limiting resistor 3123 is connected to the base of the filter bypass capacitor 3124 and the first switching transistor 3125, respectively. The collector of the first switching transistor 3125 is connected to the power supply via the second current-limiting resistor 3126. The other end of the filter bypass capacitor 3124 is grounded. The first op amp 3121 is powered by a single power supply to reduce the complexity of the protection circuit. The first switch 3125 is a PNP transistor so that the drive circuit can be shut down when the first op amp 3121 outputs 0V. If an NPN transistor is used, the first op amp 3121 can only be shut down when it outputs N5V. The latter will increase the complexity of the switch circuit design because N5V rises slowly during power-on, while the GND level is fixed.

[0043] The negative feedback circuit 313 includes a first resistor 3131, a second resistor 3132, a third resistor 3133, a fourth resistor 3134, a fifth resistor 3135, a sixth resistor 3136, and a second operational amplifier 3137. One end of the first resistor 3131 is connected to the cathode of the laser tube 33 and the second resistor 3132, respectively, and the other end is connected to the emitter of the first switching tube 3125 and the fourth resistor 3134, respectively. The other end of the second resistor 3132 is connected to the non-inverting terminal of the second operational amplifier 3137 and the third resistor 3133, respectively. The other end of the third resistor 3133 is grounded. The other end of the fourth resistor 3134 is connected to the inverting terminal of the second operational amplifier 3137 and the fifth resistor 3135, respectively. The other end of the fifth resistor 3135 is connected to the output terminal of the second operational amplifier 3137 and the sixth resistor 3136, respectively. The other end of the sixth resistor 3136 is connected to the error amplifier circuit 312. Since the constant current source driving circuit 31 uses a PNP transistor, the differential amplifier constructed by the second operational amplifier 3137 converts the current information of the laser tube (LD current information) into a voltage output which is connected to the non-inverting input terminal of the first operational amplifier 3121, forming negative feedback.

[0044] The protection circuit 314 of the laser tube 33 includes the laser tube 33 and a protection voltage-stabilizing tube 331 . The anode of the laser tube 33 is grounded, and the anode of the protection voltage-stabilizing tube 331 is connected to the cathode of the outer shell laser tube 33 , which is grounded.

[0045] For example, Figure 4 As shown, a control circuit 30 based on a constant power driving circuit is provided. The constant power driving circuit 31 is connected to Figure 3 Compared to the constant current drive circuit 31 shown, the second resistor 3132, the third resistor 3133, the fourth resistor 3134, the fifth resistor 3135, the sixth resistor 3136, and the second operational amplifier 3137 in the negative feedback circuit 313 are omitted. The first resistor 3131 is retained, and a feedback diode 3137 for optical feedback with the laser tube 33 and a voltage conversion resistor 3138 are added. The anode of the feedback diode 3137 is grounded, and the cathode is connected to the first operational amplifier 3121 and the voltage conversion resistor 3138 respectively. Here, the current of the voltage conversion resistor 3138 is converted into a voltage and fed back to the non-inverting terminal of the first operational amplifier 3121.

[0046] In the embodiment of the present application, if a switch circuit is not provided, the laser tube cannot be accurately protected by only the second current-limiting resistor. The present application provides a switch circuit that can completely shut down the driving circuit. When the power supply voltage of the driving circuit is less than the minimum operating voltage of the driving circuit, the driving operation of the driving circuit is shut down. In this way, it can be ensured that no current passes through the laser tube, thereby protecting the laser tube.

[0047] In some embodiments, the switching circuit is connected to the base of the first switching tube in the driving circuit and is further used to turn off the first switching tube when the power supply voltage of the driving circuit is less than the minimum operating voltage of the driving circuit; the first switching tube is connected to the cathode of the laser tube and is used to output the operating current provided by the driving circuit to the laser tube.

[0048] The driving circuit is a constant current driving circuit ( Figure 3 ) and constant power drive circuit ( Figure 4 ) as an example: Figure 3 and Figure 4 As shown, the switch circuit 32 is connected to the base of the first switch tube 3125 in the drive circuit 31 and is further used to turn off the first switch tube 3125 when the power supply voltage of the drive circuit is lower than the minimum operating voltage of the drive circuit. Since the first switch tube 3125 is connected to the cathode of the laser tube 33 and is used to output the operating current provided by the drive circuit 31 to the laser tube 33, after the first switch tube 3125 is turned off, the operating current provided by the drive circuit 31 cannot reach the laser tube 33. In this way, the operation of the drive circuit 31 can be directly shut down, and the drive circuit 31 can be completely shut down.

[0049] In some embodiments, the switching circuit includes a first Zener tube and a second switching tube; the second switching tube is connected to the anode of the first Zener tube through the collector, and is used to input the ground voltage of the emitter into the anode of the first Zener tube when it is turned on; the first Zener tube is connected to the base of the first switching tube through the cathode, and is used to input the ground voltage of the second switching tube into the first switching tube, enabling the first switching tube to be turned off.

[0050] The driving circuit is a constant current driving circuit ( Figure 5 ) and constant power drive circuit ( Figure 6 ) as an example: Figure 5 and Figure 6 As shown, the switching circuit 32 includes a first voltage-stabilizing transistor 321 and a second switching transistor 322. The second switching transistor 322 is connected to the anode of the first voltage-stabilizing transistor 321 via its collector. When the second switching transistor 322 is on, the ground voltage at the emitter of the second switching transistor 322 is input to the anode of the first voltage-stabilizing transistor 321. At this time, the anode of the first voltage-stabilizing transistor 321 is 0V. The first voltage-stabilizing transistor 321 is connected to the base of the first switching transistor 3125 via its cathode. The ground voltage input from the second switching transistor 322 is input to the first switching transistor 3125, enabling the first switching transistor 3125 to be turned off. The first switching transistor 3125 is a PNP transistor. When the voltage input to the base is 0V, it can be directly turned off, thereby shutting down the operation of the entire drive circuit. The voltage drop of the first voltage-stabilizing transistor 321 is relatively small.

[0051] In some embodiments, the switching circuit includes a first unidirectional tube, a second unidirectional tube, and a second switching tube; the second switching tube is connected to the anode of the first unidirectional tube through the collector, and is used to input the ground voltage of the emitter into the anode of the first unidirectional tube when it is turned on; the first unidirectional tube is connected to the non-inverting terminal of the first operational amplifier in the driving circuit through the cathode, and is used to input the ground voltage of the input second switching tube into the non-inverting terminal of the first operational amplifier; the second unidirectional tube is connected to the first negative power supply through the cathode and the anode is connected to the inverting terminal of the first operational amplifier, and is used to input the voltage provided by the first negative power supply into the inverting terminal of the first operational amplifier; the first operational amplifier connects the output terminal to the base of the first switching tube, and is used to output the ground voltage of the input non-inverting terminal to the first switching tube, enabling the first switching tube to be turned off.

[0052] The driving circuit is a constant current driving circuit ( Figure 7 ) and constant power drive circuit ( Figure 8 ) as an example: Figure 7 and Figure 8 As shown, the switch circuit 32 may further include a first unidirectional tube 323, a second unidirectional tube 324, and a second switching tube 322; the second switching tube 322 is connected to the anode of the first unidirectional tube 323 via the collector, and is used to input the ground voltage of the emitter of the second switching tube 322 to the anode of the first unidirectional tube 323 when the second switching tube 322 is turned on. At this time, the anode voltage of the first unidirectional tube 323 is 0V; the first unidirectional tube 323 is connected to the non-inverting terminal of the first operational amplifier 3121 in the driving circuit 31 via the cathode, and is used to input the input ground voltage of the second switching tube 322 to the non-inverting terminal of the first operational amplifier 3121. At this time, the voltage input to the non-inverting terminal of the first operational amplifier 3121 is 0V; the second unidirectional tube 324 is connected to the anode of the first unidirectional tube 323 via the cathode. The first transistor 3121 is connected to the first negative power supply 325 via the seventh resistor 326, and its anode is connected to the inverting terminal of the first op amp 3121, for inputting the voltage provided by the first negative power supply 325 into the inverting terminal of the first op amp 3121. At this time, the voltage input to the inverting terminal of the first op amp 3121 is a negative value. Thus, the output of the first op amp 3121 is the voltage 0V input to the non-inverting terminal. The first op amp 3121 has its output terminal connected to the base of the first switching tube 3125, for outputting the ground voltage input to the non-inverting terminal to the base of the first switching tube 3125, thereby enabling the first switching tube 3125 to be turned off. In this way, on the basis of realizing the operation of shutting down the driving circuit, since the output of the first op amp 3121 is 0V, the power consumption of the first op amp 3121 can also be reduced.

[0053] like Figure 7 and Figure 8 As shown, in order to protect the second switch tube 322 , an eighth resistor 327 is connected to the base of the second switch tube 322 .

[0054] In some embodiments, the control circuit also includes a switch control circuit, and the switch circuit also includes a third switch tube; the switch control circuit is connected to the base of the third switch tube, and is used to control the base of the third switch tube to be in a high-resistance state when the power supply voltage of the driving circuit is less than the minimum operating voltage of the driving circuit; the third switch tube is connected to the base of the second switch tube through the collector, and is used to turn on the second switch tube in the high-resistance state using the voltage provided by the first negative power supply.

[0055] The driving circuit is a constant current driving circuit ( Figure 9 ) and constant power drive circuit ( Figure 10 ) as an example: Figure 9 and Figure 10 As shown, the control circuit 30 further includes a switch control circuit 34, and the switch circuit 32 further includes a third switch 328. The switch control circuit 34 is connected to the base of the third switch 328 and is configured to control the base of the third switch 328 to be in a high-impedance state when the power supply of the drive circuit 31 is less than the minimum operating voltage of the drive circuit 31. The third switch 328 is connected to the base of the second switch 322 via its collector. When the third switch 328 is in the high-impedance state, the voltage provided by the first negative power supply 325 is used to turn on the second switch 322. When the base of the third switch 328 is in the high-impedance state, it is equivalent to being turned off. At this time, the negative voltage provided by the first negative power supply 325 flows into the base of the second switch 322 via the seventh resistor 326 and the eighth resistor 327, turning on the second switch 322.

[0056] In the embodiments of the present application, Figure 9 and Figure 10 As shown, the second switch tube 322 is turned on, and the ground voltage of the emitter of the second switch tube 322 will reach the base of the first switch tube 3125, turning it off. In addition, the negative voltage provided by the first negative power supply 325 enables the second unidirectional tube 324 to be turned on, inputting a negative voltage to the inverting terminal of the first operational amplifier 3121. At the same time, the ground voltage of the emitter of the second switch tube 322 will also reach the non-inverting terminal of the first operational amplifier 3121. In this way, the voltage at the output terminal of the first operational amplifier 3121 is also 0V. In this way, while reducing power consumption, double assurance can be achieved to ensure that the base input of the first switch tube 3125 is 0V.

[0057] In the embodiment of the present application, if the power supply voltage of the driving circuit is greater than or equal to the minimum operating voltage of the driving circuit, it indicates that the driving circuit has started to work stably. At this time, the driving circuit needs to be turned on to enable the laser tube to start working.

[0058] In some embodiments, the switch control circuit is also used to input the voltage provided by the second negative power supply in the switch control circuit into the base of the third switch tube when the power supply voltage of the drive circuit is greater than or equal to the minimum operating voltage of the drive circuit, so as to turn on the third switch tube and start the driving operation of the drive circuit.

[0059] The driving circuit is a constant current driving circuit ( Figure 9 ) and constant power drive circuit ( Figure 10 ) as an example: Figure 9 and Figure 10 As shown, the switch control circuit 34 is used to input the voltage provided by the second negative power supply 340 into the base of the third switch tube 328, so as to turn on the third switch tube 328. In this way, the switch circuit 32 is in a non-working state, which is equivalent to cutting off the connection with the drive circuit 31, thereby ensuring the normal operation of the drive circuit 31.

[0060] In some embodiments, the third switching tube is further used to input the ground voltage of the emitter of the third switching tube into the base of the second switching tube and the cathode of the second unidirectional tube respectively when it is turned on, so that the second switching tube and the second unidirectional tube are not turned on; the second switching tube is also used to control the first unidirectional tube and the first voltage-stabilizing tube to not be turned on; the first unidirectional tube and the first voltage-stabilizing tube are reverse-biased tubes to each other.

[0061] like Figure 9 and Figure 10 As shown, the third switch 328, when conducting, is further configured to input the ground voltage of the emitter of the third switch 328 into the base of the second switch 322 and the cathode of the second unidirectional transistor 324, respectively, rendering the second switch 322 and the second unidirectional transistor 324 non-conductive. The second switch 322 is also configured to control the first unidirectional transistor 323 and the first voltage-stabilizing transistor 321 to be non-conductive. The first unidirectional transistor and the first voltage-stabilizing transistor are mutually reverse-biased. This disables the first unidirectional transistor 323, the second switch 322, the second unidirectional transistor 324, and the first voltage-stabilizing transistor 321 in the switch circuit 32. This disables the switch circuit 32, thereby preventing the operation of the drive circuit 31 from being affected.

[0062] In an embodiment of the present application, the third switch tube is a PNP transistor, which needs to start the driving work of the switch circuit when it is turned on, and turn off the work of the switch circuit when it is in a high-resistance state. The third switch tube requires a negative voltage to be turned on. Considering that the level output chip (for example, a single-chip microcomputer) can output a voltage of 0 to 3.3V, if the voltage of the level output chip (for example, a single-chip microcomputer) is directly output, it is impossible to provide a negative voltage. Therefore, the present application involves a switch control circuit that provides 0V and a negative voltage to the base of the third switch tube, so that the third switch tube can be controlled to be in a high-resistance state and a conduction state. Then, in the high-resistance state, the switch circuit can turn off the work of the drive circuit, and in the conduction state, it has no effect on the drive circuit, that is, it turns off the work of the circuit.

[0063] In some embodiments, the switch control circuit includes a fourth switch tube, a fifth switch tube, a sixth switch tube, a level input terminal, a positive power supply and a second negative power supply; the fourth switch tube is connected to the level input terminal through the base, the collector is connected to the positive power supply and the base of the fifth switch tube respectively, and the emitter is grounded, and is used to maintain a high-impedance state when a low level is input to the level input terminal; the fifth switch tube is connected to the positive power supply through the base, the emitter is connected to the positive power supply, and the collector is connected to the base of the sixth switch tube, and is used to maintain a high-impedance state when the fourth switch is in a high-impedance state; the sixth switch tube is connected to the second negative power supply through the emitter, and the collector is connected to the base of the third switch tube, and is used to maintain a high-impedance state when the fifth switch is in a high-impedance state.

[0064] The driving circuit is a constant current driving circuit ( Figure 11 ) and constant power drive circuit ( Figure 12 ) as an example: Figure 11 and Figure 12As shown, the switch control circuit 34 includes a fourth switch tube 341, a fifth switch tube 342, a sixth switch tube 343, a level input terminal 344, a positive power supply 345 and a second negative power supply 340; the fourth switch tube 341 is connected to the level input terminal 344 via a ninth resistor 347 through its base, and the fourth switch tube 341 is connected to the positive power supply 345 via a tenth resistor 348 and to the base of the fifth switch tube via an eleventh resistor 349 through its collector. The emitter of the fourth switch tube 341 is grounded, and is used to maintain a high-impedance state when a low level (e.g., 0V) is input to the level input terminal 344; the fifth switch tube 341 is connected to the positive power supply 345 via a tenth resistor 348 and to the base of the fifth switch tube via an eleventh resistor 349. 42, connected to the positive power supply 345 through the base via the eleventh resistor 349 and the tenth resistor 348, connected to the positive power supply 345 through the emitter, and connected to the base of the sixth switch tube 343 through the collector, so as to maintain the high-impedance state of the fifth switch tube 342 when the fourth switch 341 is in the high-impedance state; the sixth switch tube 343 is connected to the second negative power supply 340 through the emitter, and connected to the base of the third switch tube 328 through the collector, so as to maintain the high-impedance state of the sixth switch tube 343 when the fifth switch tube 343 is in the high-impedance state, wherein a twelfth resistor 3410 is connected in parallel between the base and the emitter of the sixth switch tube 343.

[0065] In this way, 0V can be provided to the base of the third switch tube, so that the third switch tube 328 can be controlled to be in a high-resistance state, and the switch circuit 32 can turn off the operation of the driving circuit 31.

[0066] In some embodiments, the fourth switch tube is further used to input the ground voltage of the emitter into the base of the fifth switch tube when a high level is input to the level input terminal, so as to enable the fifth switch tube to be turned on; the fifth switch tube is further used to input the voltage provided by the positive power supply into the base of the sixth switch tube when it is turned on, so as to enable the sixth switch tube to be turned on; the sixth switch tube is further used to input the voltage provided by the second negative power supply into the base of the third switch tube when it is turned on, so as to enable the third switch tube to be turned on.

[0067] like Figure 11 and Figure 12 As shown, the fourth switch tube 341 is also used to be in the on state when a high level (for example, 3.3V) is input to the level input terminal 344; the fifth switch tube 342 is also used to be in the on state when the fourth switch 341 is in the on state; the sixth switch tube 343 is also used to keep the sixth switch tube 343 in the on state when the fifth switch tube 343 is in the on state.

[0068] In this way, a negative voltage can be provided for the base of the third switch tube, so that the third switch tube can be controlled to be in the on state, and then in the on state, it has no effect on the driving circuit, that is, the operation of the off circuit is turned off.

[0069] In the embodiments of the present application, Figures 3 to 12 The part number next to each part number is the part model.

[0070] The embodiments of the present application disclose a control circuit for a laser tube. The control circuit includes: a drive circuit and a switch circuit; the drive circuit is connected to the switch circuit; the drive circuit is used to provide an operating current for the laser tube; and the switch circuit is used to shut down the drive circuit's driving operation when the power supply voltage of the drive circuit is less than the minimum operating voltage of the drive circuit. The control circuit of the laser tube provided in the present application is provided with a switch circuit capable of completely shutting down the drive circuit. When the power supply voltage of the drive circuit is less than the minimum operating voltage of the drive circuit, the drive circuit's driving operation is shut down. In this way, it is possible to ensure that no current flows through the laser tube, thereby protecting the laser tube.

[0071] The embodiment of the present application further provides a laser tube control method, which is applied to the control circuit of the laser tube including the above-mentioned driving circuit and the switching circuit, wherein the driving circuit is connected to the switching circuit; Figure 13 This is a flow chart of a laser tube control method provided in an embodiment of the present application. Figure 13 As shown, the laser tube control method mainly includes the following steps S1301 and S1302:

[0072] Step S1301: The driving circuit provides operating current to the laser tube.

[0073] In the embodiment of the present application, the driving circuit may be a constant current source driving circuit (see Figure 11 ) and constant power drive circuit (see Figure 12 ), the driving circuit can provide operating current for the laser tube.

[0074] Step S1302 : When the power supply voltage of the driving circuit is lower than the minimum operating voltage of the driving circuit, the switch circuit turns off the driving operation of the driving circuit.

[0075] In an embodiment of the present application, the switching circuit can shut off the driving operation of the driving circuit when the power supply voltage of the driving circuit is less than the minimum operating voltage of the driving circuit, and start the driving operation of the driving circuit when the power supply voltage of the driving circuit is greater than or equal to the minimum operating voltage of the driving circuit.

[0076] For example, Figure 11 and Figure 12As shown, the switch circuit 32 is mainly implemented by the second switch tube 322, the third switch tube 328, the first voltage regulator tube 321, the first unidirectional tube 323, and the second unidirectional tube 324. When the base voltage of the third switch tube 328 is 0V, the switch is turned off, and when the voltage is negative, the switch is turned on. (1) When the switch is turned off (the switch control circuit inputs 0V to the third switch tube 328), the third switch tube 328 is turned off, the second switch tube 322 is turned on, the voltage on the left side of the eighth resistor 327 is -5V (the voltage provided by the first negative power supply is -5V), the voltage at the non-inverting input terminal of the first op amp 3121 is approximately 0V, and the voltage at the inverting input terminal is approximately -5V. The first op amp 3121 outputs the maximum value, that is, 0V. At the same time, the second switch tube 322 and the first voltage regulator tube 321 will also make the base voltage of the first switch tube 3125 approximately 0V. The laser tube is completely turned off. (2) When the switch is turned on (the switch control circuit inputs a negative voltage to the third switch 328), the third switch 328 is turned on, and the second unidirectional transistor 324 (diode) is reverse biased and does not conduct, which does not affect the set voltage of the inverting input terminal of the first op amp 3121. After the second switch 322 is turned off, its collector is in a high-impedance state. The two diodes of the first voltage regulator 321 and the first unidirectional transistor 323 are "back-to-back" and do not affect the feedback voltage and output voltage of the first op amp 3121.

[0077] like Figure 14 As shown, the laser tube driving circuit with the anode connected to the shell can ensure that when the switch is not turned on, the laser tube will never have any abnormal output due to the power supply voltage of the error amplifier (first op amp) not reaching the operating voltage, and can be completely shut down. After the switch is turned on, the circuit works normally. Therefore, the control circuit can monitor the power supply voltage (see the power supply connected to the second current limiting resistor in the driving circuit, which is the power supply). The laser tube (LD) can only be turned on through the circuit after the minimum operating voltage of the first op amp is met, so as to avoid possible damage to the LD caused by abnormal current and achieve the protection purpose. Figure 10 Although the simulation results show currents of several hundred uA, there is no harm. Therefore, the LD will not cause any erroneous current due to the erroneous output of the error amplifier during the power supply establishment process.

[0078] An embodiment of the present application provides a laser tube control method, which is applied to a control circuit of the laser tube. The control circuit of the laser tube includes: a drive circuit and a switch circuit, wherein the drive circuit is connected to the switch circuit. The method includes: the drive circuit provides an operating current to the laser tube; and the switch circuit shuts off the drive circuit's driving operation when the power supply voltage of the drive circuit is less than the minimum operating voltage of the drive circuit. The laser tube control method provided by the present application provides a switch circuit capable of completely shutting off the drive circuit. When the power supply voltage of the drive circuit is less than the minimum operating voltage of the drive circuit, the drive circuit's driving operation is shut off. In this way, no current can be ensured to flow through the laser tube, thereby protecting the laser tube.

[0079] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A control circuit for a laser tube, characterized in that: The control circuit includes: a driving circuit and a switching circuit; the driving circuit is connected to the switching circuit; The driving circuit is used to provide operating current to the laser tube; The switch circuit is used to shut down the driving operation of the driving circuit when the power supply voltage of the driving circuit is lower than the minimum operating voltage of the driving circuit.

2. The control circuit according to claim 1, wherein: The switch circuit is connected to the base of the first switch tube in the drive circuit and is further configured to turn off the first switch tube when the power supply voltage of the drive circuit is lower than the minimum operating voltage of the drive circuit; The first switching tube is connected to the cathode of the laser tube and is used to output the operating current provided by the driving circuit to the laser tube.

3. The control circuit according to claim 2, characterized in that: The switch circuit includes a first voltage-stabilizing tube and a second switch tube; The second switching tube is connected to the anode of the first voltage regulator tube via the collector, and is used to input the ground voltage of the emitter into the anode of the first voltage regulator tube when it is turned on; The first voltage regulator tube is connected to the base of the first switch tube via a cathode, and is used to input the ground voltage of the second switch tube into the first switch tube to enable the first switch tube to be turned off.

4. The control circuit according to claim 2 or 3, characterized in that: The switch circuit includes a first unidirectional tube, a second unidirectional tube, and a second switch tube; The second switching tube is connected to the anode of the first unidirectional tube via the collector, and is used to input the ground voltage of the emitter into the anode of the first unidirectional tube when it is turned on; The first unidirectional transistor is connected to the non-inverting terminal of the first operational amplifier in the driving circuit via the cathode, and is used to input the input ground voltage of the second switching transistor into the non-inverting terminal of the first operational amplifier; The second unidirectional transistor is connected to the first negative power supply via a cathode and connected to the inverting terminal of the first operational amplifier via an anode, and is used to input the voltage provided by the first negative power supply into the inverting terminal of the first operational amplifier; The first operational amplifier has its output terminal connected to the base of the first switching tube, and is used to output the ground voltage of the input non-inverting terminal to the first switching tube, so as to enable the first switching tube to be turned off.

5. The control circuit according to claim 4, characterized in that: The control circuit further includes a switch control circuit, and the switch circuit further includes a third switch tube; The switch control circuit is connected to the base of the third switch tube and is used to control the base of the third switch tube to be in a high-impedance state when the power supply voltage of the drive circuit is lower than the minimum operating voltage of the drive circuit; The third switching tube is connected to the base of the second switching tube via the collector, and is used to turn on the second switching tube using the voltage provided by the first negative power supply in a high-resistance state.

6. The control circuit according to claim 5, characterized in that: The switch control circuit is further configured to input the voltage provided by the second negative power supply in the switch control circuit into the base of the third switch tube when the power supply voltage of the drive circuit is greater than or equal to the minimum operating voltage of the drive circuit, thereby turning on the third switch tube and starting the drive operation of the drive circuit.

7. The control circuit according to claim 6, characterized in that: The third switching tube is further configured to input the ground voltage of the emitter of the third switching tube into the base of the second switching tube and the cathode of the second unidirectional tube respectively when the third switching tube is turned on, so that the second switching tube and the second unidirectional tube are not turned on; The second switch tube is further used to control the first unidirectional tube and the first voltage-stabilizing tube to be non-conductive; the first unidirectional tube and the first voltage-stabilizing tube are mutually reverse-biased tubes.

8. The control circuit according to claim 6, wherein: The switch control circuit includes a fourth switch tube, a fifth switch tube, a sixth switch tube, a level input terminal, a positive power supply and a second negative power supply; The fourth switch tube is connected to the level input terminal via a base, the collector is connected to the positive power supply and the base of the fifth switch tube respectively, and the emitter is grounded, and is used to maintain a high-impedance state when a low level is input to the level input terminal; The fifth switch tube is connected to the positive power supply via a base, an emitter is connected to the positive power supply, and a collector is connected to the base of the sixth switch tube, and is used to maintain a high-impedance state when the fourth switch is in a high-impedance state; The sixth switch tube is connected to the second negative power supply via an emitter and a collector to the base of the third switch tube, and is used to maintain a high-resistance state when the fifth switch tube is in a high-resistance state.

9. The control circuit according to claim 8, characterized in that: The fourth switch tube is further configured to input the ground voltage of the emitter into the base of the fifth switch tube when a high level is input to the level input terminal, so as to enable the fifth switch tube to be turned on; The fifth switch tube is further configured to input the voltage provided by the positive power supply into the base of the sixth switch tube when the fifth switch tube is turned on, so as to enable the sixth switch tube to be turned on; The sixth switch tube is further configured to input the voltage provided by the second negative power supply into the base of the third switch tube when the sixth switch tube is turned on, so as to turn on the third switch tube.

10. A method for controlling a laser tube, characterized in that: Applied to a control circuit, the control circuit comprises: a driving circuit and a switching circuit; the driving circuit is connected to the switching circuit; The driving circuit provides the laser tube with an operating current; The switch circuit turns off the driving operation of the driving circuit when the power supply voltage of the driving circuit is lower than the minimum operating voltage of the driving circuit.

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