Laser working current regulation and control circuit and laser driving system

Abstract

The utility model relates to a laser working current regulation and control circuit and a laser driving system. The circuit comprises a control loop unit, a driving unit and a transistor parallel component unit, wherein the transistor parallel component unit comprises a plurality of first transistor elements which are connected in parallel; wherein the first input end of the control loop unit is used for accessing an external control signal, the second input end of the control loop unit is connected with the third end of the transistor parallel assembly unit, and the output end of the control loop unit is connected with the input end of the driving unit; the output end of the driving unit is connected with the first end of the transistor parallel assembly unit; and the second end of the transistor parallel assembly unit is used for accessing a laser load. The circuit can improve the regulation speed of the working current of the laser and the stability of the power.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a laser operating current control circuit and a laser driving system. Background Art

[0002] With the development of laser technology, solid-state laser technology has emerged. Solid-state lasers have the advantages of short wavelength, high absorption rate, small size, and flexible processing using optical fiber transmission. The power stability of the laser is an important indicator of the performance of solid-state lasers. Moreover, according to the different usage scenarios of solid-state lasers, the operating current of the laser needs to be adjusted to adapt to different uses.

[0003] However, due to the limitations of the internal structure and working mechanism of solid-state lasers, they have high requirements for the working conditions and working performance of the power supply. Slight changes in the drive current may cause changes in the main parameters of the solid-state laser. If the fluctuation is too large, it may even cause damage to the laser. Traditional solid-state lasers have poor power stability, slow response speed of working current regulation, and are prone to current overshoot, which can cause circuit damage. Utility Model Content

[0004] Based on this, it is necessary to provide a laser operating current control circuit and a laser driving system that can improve the laser operating current adjustment speed and thus improve the power stability of the laser in order to address the above technical problems.

[0005] In a first aspect, a laser operating current control circuit is provided, the circuit comprising: a control loop unit, a drive unit and a transistor parallel component unit, the transistor parallel component unit comprising a plurality of first transistor elements connected in parallel; wherein,

[0006] The first input end of the control loop unit is used to access an external control signal, the second input end of the control loop unit is connected to the third end of the transistor parallel component unit, and the output end of the control loop unit is connected to the input end of the driving unit;

[0007] The output end of the driving unit is connected to the first end of the transistor parallel assembly unit; and

[0008] The second end of the transistor parallel assembly unit is used to connect to the laser load.

[0009] In some embodiments, the transistor parallel component unit includes a plurality of parallel N-type transistor elements; wherein the bases of the N-type transistor elements are connected, the collectors of the N-type transistor elements are connected, and the emitters of the N-type transistor elements are connected.

[0010] In some embodiments, the transistor parallel component unit further includes a sampling resistor; wherein a first end of the sampling resistor is connected to the emitter of each N-type triode element and the second input end of the control loop unit, and a second end of the sampling resistor is grounded.

[0011] In some embodiments, the control loop unit includes an operational amplifier, a first resistor, a second resistor, and a capacitor element; wherein,

[0012] The positive input terminal of the operational amplifier is connected to the external control signal, and the negative input terminal of the operational amplifier is connected to the first end of the first resistor, the first end of the second resistor and the first end of the capacitor;

[0013] The output end of the operational amplifier is connected to the second end of the second resistor, the second end of the capacitor and the input end of the driving unit;

[0014] The second end of the first resistor is connected to the first end of the sampling resistor.

[0015] In some embodiments, the control loop unit further includes a third resistor and a fourth resistor;

[0016] The first end of the third resistor is connected to the external control signal, the second end of the third resistor is connected to the positive input end of the operational amplifier and the first end of the fourth resistor, and the second end of the fourth resistor is grounded.

[0017] In some embodiments, the driving unit includes a fifth resistor and a second transistor element; wherein,

[0018] The first end of the fifth resistor is connected to the output end of the control loop unit, the second end of the fifth resistor is connected to the first end of the second transistor element, the second end of the second transistor element is connected to the second end of the transistor parallel component unit, and the third end of the second transistor element is connected to the first end of the transistor parallel component unit.

[0019] In some embodiments, the second transistor element is an N-type triode element.

[0020] In some embodiments, the circuit further comprises a diode element, a positive terminal of the diode element connected to the second terminal of the transistor parallel assembly unit and the first terminal of the laser load, and a negative terminal of the diode element connected to the second terminal of the laser load and the power supply unit.

[0021] In a second aspect, a laser driving system is also provided, the system comprising a power supply unit, a laser load and the laser operating current control circuit of the first aspect.

[0022] In some embodiments, the system further comprises a pulse generating and level adjusting unit, wherein the output end of the pulse generating and level adjusting unit is connected to the first end of the control loop unit, and the input end of the pulse generating and level adjusting unit is used to connect to the microprocessor.

[0023] The above-mentioned laser operating current control circuit and laser driving system can control the conduction depth of the parallel transistor elements according to the current amplitude of the output end of the control loop unit through the transistor parallel component unit, thereby controlling the operating current of the load laser, and by connecting the feedback voltage signal of the third end of the transistor parallel component unit back to the second input end of the control loop unit, the control loop unit can dynamically adjust the current amplitude output from the output end according to the feedback voltage signal. Therefore, when the external control signal changes or becomes unstable, the control loop unit can timely sense the change of the operating current of the laser load, and quickly adjust the current amplitude output from its output end according to the feedback voltage signal, thereby affecting the conduction number and on-resistance of the parallel transistor elements in the transistor parallel component unit, thereby compensating for the influence of the change of the external control signal on the operating current of the laser load, thereby maintaining the stability of the operating current and power of the laser load. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the laser working current control circuit in some embodiments;

[0025] Figure 2 It is a schematic diagram of the structure of the laser working current control circuit in some other embodiments;

[0026] Figure 3 Schematic diagram of the structure of the laser driving system in some embodiments. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] In some embodiments, reference Figure 1 and Figure 2 As shown, a laser operating current control circuit 100 is provided, the circuit comprising: a control loop unit 10, a drive unit 20 and a transistor parallel component unit 30, the transistor parallel component unit 30 comprising a plurality of first transistor elements (Q101-Q10n, wherein n is a positive integer greater than 2) connected in parallel;

[0029] The first input terminal of the control loop unit 10 is used to access an external control signal, the second input terminal of the control loop unit 10 is connected to the third terminal of the transistor parallel component unit 30, and the output terminal of the control loop unit 10 is connected to the input terminal of the driving unit 20;

[0030] The output end of the driving unit 20 is connected to the first end of the transistor parallel assembly unit 30; and

[0031] The second end of the transistor parallel assembly unit 30 is connected to the laser load 40 .

[0032] The electrical signal interaction between the various units is described as follows:

[0033] The control loop unit 10 is configured to adjust the current amplitude of the output terminal according to the feedback voltage signal fed back from the third terminal of the transistor parallel component unit 30 to its second input terminal and the external control signal connected to its first input terminal;

[0034] The driving unit 20 is configured to provide an operating current to the transistor parallel component unit 30. Specifically, since the transistor parallel component unit 30 requires a certain operating current and voltage when working, which the control circuit unit 10 cannot provide, the driving capability can be enhanced by providing the driving unit 20, so as to realize the rapid shutdown of the transistor elements in the transistor parallel component unit 30, thereby improving the speed of the entire circuit in responding to the current adjustment;

[0035] The transistor parallel component unit 30 is configured to adjust the number of conduction of multiple parallel transistor elements according to the current amplitude of the output end of the control loop unit 10, thereby adjusting the operating current of the laser load 40, and feeding back the feedback voltage signal of its third end to the second input end of the control loop unit 10.

[0036] In the above-mentioned laser operating current control circuit, the transistor parallel component unit 30 can regulate the conduction depth of the parallel transistor elements according to the current amplitude of the output end of the control loop unit 10, thereby controlling the operating current of the load laser 40, and by connecting the feedback voltage signal of the third end of the transistor parallel component unit 30 back to the second input end of the control loop unit 10, the control loop unit 10 can timely adjust the current amplitude output from the output end according to the feedback voltage signal. Therefore, when the external control signal changes or becomes unstable, the control loop unit 10 can quickly and dynamically sense the change in the operating current of the laser load, and timely adjust the current amplitude output from its output end according to the feedback voltage signal, thereby affecting the conduction number and on-resistance of the parallel transistor elements in the transistor parallel component unit 30, thereby compensating for the influence of the change in the external control signal on the operating current of the laser load 40, thereby maintaining the stability of the operating current and power of the laser load 40.

[0037] In some embodiments, the first transistor element may be a triode element, for example, Figure 2As shown, the transistor parallel component unit 30 may include multiple parallel N-type transistor elements (Q101, Q102, Q103...Q10n, where n is a positive integer greater than 2); wherein the base B of each N-type transistor element is connected to serve as the first end of the transistor parallel component unit 30, the collector C of each N-type transistor element is connected to serve as the second end of the transistor parallel component unit 30, and the emitter E of each N-type transistor element is connected to serve as the third end of the transistor parallel component unit 30.

[0038] In this embodiment, a transistor parallel assembly unit 30 is constructed based on a plurality of N-type triode elements. Since the triode element has a good response characteristic, the smoothness of the rising edge of the working current pulse of the laser can be improved. In other feasible implementations, a plurality of P-type triode elements, or field effect transistors, IGBT tubes (Insulated Gate Bipolar Transistor, insulated gate bipolar transistors) and other elements may also be used. The selection of the type of transistor element and the connection method of each pole can be determined according to actual needs and are not limited here.

[0039] In some embodiments, the transistor parallel component unit 30 may further include a sampling resistor RI1, wherein the emitter E of each N-type transistor element is connected and connected to the first end of the sampling resistor RI1, the first end of the sampling resistor RI1 is also connected to the second input end (negative input end) of the control loop unit, and the second end of the sampling resistor RI1 is grounded.

[0040] In practical applications, it is assumed that the voltage of the transistor parallel assembly unit 30 is set to U Q , the working voltage U of the laser load 40 LED , the input supply voltage is U IN , I B is the current flowing through the laser load 40, so we can get:

[0041] U IN =U Q +U LED +I B RI1,

[0042] Since the laser load 40 can be a semiconductor laser, which is a nonlinear device, in order to facilitate analysis and calculation, U Q +U LED =U IN -I B RI1 is a fixed value, that is, the laser load is 40 U LEDThe resistance of the transistor element in the transistor parallel assembly unit 30 changes only with the change of the resistance generated by the transistor element, and has nothing to do with the output current. Therefore, the stability of the output current can be improved, that is, the working current I of the laser load can be improved. B stability.

[0043] In some embodiments, the control loop unit 10 includes an operational amplifier IC1, a first resistor R1, a second resistor R2, and a capacitor C1; wherein,

[0044] The positive input terminal IC1+ of the operational amplifier IC1 is connected to an external control signal, wherein the external control signal may include a pulse modulation signal of a PWM (Pulse Width Modulation) and / or a level modulation signal of a DAC (Digital to Analog Converter), and the negative input terminal IC1- of the operational amplifier IC1 is connected to a first end of the first resistor R1, a first end of the second resistor R2 and a first end of the capacitor C1;

[0045] The output terminal IC1out of the operational amplifier IC1 is connected to the second end of the second resistor R2, the second end of the capacitor C1 and the input terminal of the driving unit 20;

[0046] The second end of the first resistor R1 is connected to the first end of the sampling resistor RI1.

[0047] In this embodiment, a control loop unit 10 including an operational amplifier IC1, a first resistor R1, a second resistor R2 and a capacitor C1 is used to form a negative feedback control loop. Through the negative feedback control loop, the change of the feedback voltage signal at the first end of the sampling resistor RI1 can be sensed in time. By connecting the feedback voltage signal to the negative input terminal IC1- of the operational amplifier IC1, negative feedback regulation can be achieved to improve the stability of the entire circuit system. That is, when V A becomes larger (that is, the input voltage generated by the external control signal becomes larger), the input of the positive input terminal IC1+ of the operational amplifier IC1 becomes larger, the output voltage of the output terminal out of the operational amplifier IC1 becomes higher, the current flowing into the transistor element Q1 in the driving unit 20 becomes larger, the current flowing out of the transistor element Q1 becomes larger, and then the driving current flowing into the transistor parallel component unit 30 becomes larger, the on-resistance of the transistor parallel component unit 30 becomes smaller, and the voltage U Q becomes smaller, and the U added to both ends of the laser load 40 LED The laser load current I B Get bigger, I BThe feedback voltage signal of RI1 becomes larger, and after being input into the negative input terminal IC1- of the operational amplifier IC1, after being adjusted back by the operational amplifier IC1, the output terminal IC1out of the operational amplifier IC1 outputs the adjusted voltage, thus completing the entire control cycle.

[0048] In some embodiments, the control loop unit 10 also includes a third resistor R3 and a fourth resistor R4, the first end of the third resistor R3 is connected to the external control signal, the second end of the third resistor R3 is connected to the positive input terminal IC1+ of the operational amplifier IC1 and the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is grounded.

[0049] In this embodiment, the third resistor R3 and the fourth resistor R4 may be set as voltage divider resistors of the positive input terminal IC1+ of the operational amplifier IC1, wherein the third resistor R3, the fourth resistor R4 and the sampling resistor RI1 satisfy the following relationship:

[0050]

[0051] In the above formula, V A The voltage value of the input external control signal, I B is the operating current of the laser load 40, R3, R4 and RI1 are the resistance values ​​of the corresponding resistors. Since R3, R4 and RI1 can determine their setting values, V A with I B There is a linear relationship between them. By setting V A The value can be used to infer the operating current I driving the laser load. B Therefore, by setting the voltage divider resistor, V A with I B The linear relationship between them can improve the stability of the entire circuit.

[0052] In some embodiments, the driving unit 20 includes a fifth resistor R2 and a second transistor element Q2; wherein,

[0053] A first end of the fifth resistor R5 is connected to the output end of the control loop unit 10, a second end of the fifth resistor R5 is connected to a first end of the second transistor element Q2, a second end of the second transistor element Q2 is connected to a second end of the transistor parallel component unit 30, and a third end of the second transistor element Q2 is connected to a first end of the transistor parallel component unit 30.

[0054] In this embodiment, the driving stage of the transistor parallel component unit 30 is composed of the resistor element R5 and the second transistor element Q2. The output of the operational amplifier IC1 drives the second transistor element Q2 through the resistor element R5. Since the transistor parallel component unit 30 requires a certain working current and voltage when working, the control loop unit 10 cannot provide them. Therefore, by setting the driving unit 20, the driving capability can be enhanced to achieve rapid shutdown of the transistor elements in the transistor parallel component unit 30, thereby improving the speed of the entire circuit responding to current adjustment.

[0055] In some embodiments, the second transistor element Q2 can also be implemented using an N-type transistor element. When an N-type transistor element is used as Q2, the emitter E of the N-type transistor element Q2 is connected to the base B of each N-type transistor element (Q101 to Q10n) in the transistor parallel component unit 30, and the collector C of the N-type transistor element Q2 is connected to the collector C of each N-type transistor element (Q101 to Q10n).

[0056] In some embodiments, the circuit 100 further includes a diode element D1, a positive terminal D1+ of the diode element D1 connected to the second end of the transistor parallel component unit 30 and the first end of the laser load 40, and a negative terminal D1- of the diode element D1 connected to the second end of the laser load 40 and the power supply element V.

[0057] In this embodiment, by setting the diode element D1, since the diode element D1 has a unidirectional conduction function, it can eliminate the overvoltage caused when the laser load 60 is started and shut down, that is, it plays a role in absorbing the reverse electromotive force, thereby protecting various components in the circuit.

[0058] In some embodiments, a laser driving system 200 is also provided, which can be referred to as Figure 3 As shown, the system 200 includes a power supply unit 50, a laser load 40, and a laser operating current control circuit 100. Among them, a first end of the power supply unit 60 is connected to the laser load 40 and the laser operating current control circuit 100, and a second end of the power supply unit 60 is grounded. For the description of the laser operating current control circuit 100 in the system 200, reference can be made to the above embodiments, which will not be repeated here.

[0059] In some embodiments, the system 200 also includes a pulse generation and level adjustment unit 50; wherein the output end of the pulse generation and level adjustment unit 50 is connected to the first end of the control loop unit 10 of the laser working current control circuit 100, and the input end of the pulse generation and level adjustment unit 50 can be used to connect to a microcontroller unit (MCU).

[0060] In this embodiment, the external control signal can be generated by the pulse generation and level adjustment unit 50, and the pulse generation and level adjustment unit 50 can include a pulse generator PWM and a level adjuster DAC, and the two generate a two-in-one signal input to the positive input terminal CI1+ of the operational amplifier CI1 of the control loop unit 10. The control loop unit 10 can control the opening and closing of the laser load 40 according to the level of the PWM signal, and the duration of the high level of the PWM signal can realize the setting of the light-emitting time of the laser load 40. The amplitude of the high level of the PWM signal controls the on-resistance of the N-type triode element (Q101-Q10n) through the control loop unit 10, thereby controlling the working current. That is, the larger the amplitude of the high level of the PWM signal, the larger the amplitude of the input voltage or current, the deeper the conduction of the N-type triode element (Q101-Q10n), and the working current I of the laser load 40. B The bigger.

[0061] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0062] In addition, the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the characters in this article generally indicate that the associated objects before and after are in an "or" relationship.

[0063] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A laser operating current control circuit, the circuit comprising: A control loop unit, a drive unit and a transistor parallel assembly unit, wherein the transistor parallel assembly unit includes a plurality of first transistor elements connected in parallel; wherein, The first input end of the control loop unit is used to access an external control signal, the second input end of the control loop unit is connected to the third end of the transistor parallel component unit, and the output end of the control loop unit is connected to the input end of the driving unit; The output end of the driving unit is connected to the first end of the transistor parallel assembly unit; and The second end of the transistor parallel assembly unit is used to access a laser load.

2. The circuit according to claim 1, characterized in that The transistor parallel assembly unit comprises a plurality of parallel-connected N-type triode elements; wherein, The bases of the N-type transistor elements are connected, the collectors of the N-type transistor elements are connected, and the emitters of the N-type transistor elements are connected.

3. The circuit according to claim 2, characterized in that The transistor parallel component unit also includes a sampling resistor; wherein, The first end of the sampling resistor is connected to the emitter of each of the N-type triode elements and the second input end of the control loop unit, and the second end of the sampling resistor is grounded.

4. The circuit according to claim 3, characterized in that The control loop unit includes an operational amplifier, a first resistor, a second resistor and a capacitor element; wherein, The positive input terminal of the operational amplifier is connected to an external control signal, and the negative input terminal of the operational amplifier is connected to the first end of the first resistor, the first end of the second resistor and the first end of the capacitor; The output end of the operational amplifier is connected to the second end of the second resistor, the second end of the capacitor and the input end of the driving unit; The second end of the first resistor is connected to the first end of the sampling resistor.

5. The circuit according to claim 4, characterized in that The control loop unit also includes a third resistor and a fourth resistor; The first end of the third resistor is connected to the external control signal, the second end of the third resistor is connected to the positive input end of the operational amplifier and the first end of the fourth resistor, and the second end of the fourth resistor is grounded.

6. The circuit according to claim 1, characterized in that The driving unit includes a fifth resistor and a second transistor element; wherein, The first end of the fifth resistor is connected to the output end of the control loop unit, the second end of the fifth resistor is connected to the first end of the second transistor element, the second end of the second transistor element is connected to the second end of the transistor parallel component unit, and the third end of the second transistor element is connected to the first end of the transistor parallel component unit.

7. The circuit according to claim 6, characterized in that The second transistor element is an N-type triode element.

8. The circuit according to claim 1, characterized in that The circuit further comprises a diode element, wherein a positive terminal of the diode element is connected to the second terminal of the transistor parallel assembly unit and the first terminal of the laser load, and a negative terminal of the diode element is connected to the second terminal of the laser load and a power supply unit.

9. A laser driving system, characterized in that: The system comprises a power supply unit, a laser load and a laser operating current control circuit according to any one of claims 1 to 8.

10. The system according to claim 9, characterized in that The system also includes a pulse generation and level adjustment unit; wherein, The output end of the pulse generation and level adjustment unit is connected to the first end of the control loop unit, and the input end of the pulse generation and level adjustment unit is used to connect to the microprocessor.

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