Laser drive circuit and laser thereof

Abstract

The utility model relates to the technical field of electronic circuits, in particular to a laser driving circuit and a laser thereof. A laser driving circuit comprises a power supply conversion module connected with a power supply input end; the LDO module is connected with the power supply input end; the power supply conversion module and the LDO module are connected with the driving module; and the laser tube is connected with the driving module. A power conversion module and a driving module are organically combined, the power conversion module is used for providing working voltage and controlling voltage drop of the driving module, an LDO module is used for providing driving current for a driving circuit, and the driving module controls power of an LD branch in a laser, so that normal work of the laser is ensured, and stable output of the power of the laser is achieved. The laser drive circuit is simple in structure, wide in application range and good in reliability.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, in particular to a laser driving circuit and a laser thereof. Background Art

[0002] Semiconductor laser tubes (LDs) and ordinary diodes use different processes, but their voltage and current characteristics are basically the same. At the operating point, a small voltage change will cause a large change in the laser tube current. In addition, excessive current ripple will also make the laser tube output unstable. The laser tube has very strict requirements on its drive circuit.

[0003] Existing drive circuits such as Figure 1 As shown, resistor R1 provides a starting current for the driving circuit, resistor R2 provides a certain amount of negative feedback and stable loop gain, potentiometer W1 adjusts the power sampling value, resistor R3 drives the feedback amount of feedback transistor Q1, and capacitor C2 eliminates the instantaneous overcharge current of the laser. After the circuit is powered on, driven by resistor R1, the current of transistor Q2 begins to rise, and the output power of the laser begins to increase. As the power rises, the conduction degree of the feedback PD in the laser gradually increases, the feedback PD current rises, and the voltage on the adjustable resistor W1 begins to rise. When this voltage rises to 0.5V~0.6V, the feedback transistor Q1 begins to gradually turn on. The feedback transistor Q1 turns on and shunts part of the base current of the transistor Q2, making the conduction state of the transistor Q2 tend to be stable. By adjusting the resistance value of the adjustable resistor W1, the driving current value of the transistor Q2 can be adjusted, thereby stabilizing the output power of the laser. However, the existing driving circuit has the following disadvantages:

[0004] 1. It uses DC drive, and the drive efficiency is relatively low. Laser LDs of different colors must use different working voltages, and the input voltage adaptability range is narrow.

[0005] 2. As the laser terminal voltage changes when the temperature changes, in order to work normally in the entire temperature range, only a relatively high voltage design can be adopted. When the module works in a high temperature environment, the laser terminal voltage decreases. This reduced voltage is all borne by the driving transistor Q2, causing the transistor Q2 to heat up abnormally, thereby reducing the electrical performance of the transistor Q2 and reducing the reliability of the driving circuit. Utility Model Content

[0006] The utility model aims to solve at least one of the technical problems existing in the prior art.

[0007] To this end, the utility model provides a laser driving circuit with simple structure, wide application range and good reliability.

[0008] The laser driving circuit according to the embodiment of the utility model comprises:

[0009] A power conversion module connected to a power input terminal;

[0010] An LDO module is connected to the power input terminal;

[0011] A driving module, the power conversion module and the LDO module are both connected to the driving module;

[0012] The laser tube is connected to the driving module.

[0013] The beneficial effect of the utility model is that, through the organic combination of the power conversion module and the driving module, the power conversion module is used to provide the working voltage and also control the voltage drop of the driving module, the LDO module is used to provide the driving current to the driving circuit, and the driving module controls the power of the LD branch in the laser to ensure the normal operation of the laser and achieve the stable output of the laser power. Controlling the voltage drop of the driving module by the power conversion module can avoid the problem of excessive voltage drop of the driving module, which makes the circuit efficiency low, thereby causing the problem of large temperature rise of the circuit, improves the reliability of the circuit, can adapt to lasers with different end voltage drops, has a simple structure, and has a wide range of applications. In addition, since the driving current of the driving circuit is supplied by the LDO module with a stable voltage, the stability of the power of the LD branch of the laser controlled by the driving module is further improved, and the performance of the laser driving circuit is further improved.

[0014] According to one embodiment of the utility model, it also includes:

[0015] Temperature detection module;

[0016] A processor is connected to the temperature detection module, and the processor is also connected to the driving module through a signal conversion module.

[0017] According to an embodiment of the present invention, the power conversion module is a DC-DC conversion module.

[0018] According to an embodiment of the present utility model, the driving module includes a digitally adjustable resistor, and the processor is connected to the digitally adjustable resistor.

[0019] According to an embodiment of the utility model, the power conversion module includes a Buck step-down unit and a voltage stabilizing unit, and the LDO module, the voltage stabilizing unit and the driving module are all connected to the Buck step-down unit;

[0020] The processor is connected to the voltage stabilizing unit.

[0021] According to an embodiment of the present invention, the processor is also connected to an oscillator.

[0022] According to an embodiment of the utility model, the driving module includes: a first operational amplifier, a second operational amplifier, a first diode, a first MOS tube, a first resistor and an adjustable resistor;

[0023] The drain of the first MOS tube and the LD branch of the laser tube are both connected to the Buck step-down unit, the positive input terminals of the first operational amplifier and the second operational amplifier are respectively connected to the signal conversion module, the reverse input terminal of the second operational amplifier and the PD branch of the laser tube are both connected to the fixed A terminal of the adjustable resistor, the reverse input terminal of the first operational amplifier is connected to the source of the first MOS tube, the output terminal of the first operational amplifier is connected to the cathode of the first diode, the anode of the first diode and the output terminal of the second operational amplifier are both connected to the gate of the first MOS tube, the variable C terminal of the adjustable resistor is connected to the processor, and the source of the first MOS tube is connected in series with the first resistor and the fixed B terminal of the adjustable resistor are both connected to a common ground terminal.

[0024] According to an embodiment of the utility model, the signal conversion module includes a first digital-to-analog conversion unit and a second digital-to-analog conversion unit;

[0025] The input ends of the first digital-to-analog conversion unit and the second digital-to-analog conversion unit are both connected to the processor;

[0026] The output terminal of the first digital-to-analog conversion unit is connected to the positive input terminal of the first operational amplifier;

[0027] The output terminal of the second digital-to-analog conversion unit is connected to the positive input terminal of the second operational amplifier.

[0028] A laser adopts the laser driving circuit as described above.

[0029] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by practicing the utility model. The purpose and other advantages of the utility model are realized and obtained by the structures specifically pointed out in the description, claims and drawings.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0032] Figure 1 It is a structural schematic diagram of the prior art.

[0033] Figure 2 It is a structural schematic diagram of the first embodiment of the utility model.

[0034] Figure 3 It is a circuit diagram of the first embodiment of the utility model.

[0035] Figure 4 It is a structural schematic diagram of the second embodiment of the present utility model.

[0036] Figure 5 This is a partial circuit schematic diagram of the second embodiment of the utility model.

[0037] Figure 6 It is a structural schematic diagram of the third embodiment of the present utility model.

[0038] Figure 7 It is a structural schematic diagram of a power conversion module of the third embodiment of the utility model.

[0039] Figure 8 This is a partial circuit schematic diagram of the third embodiment of the present utility model.

[0040] In the figure: 1. power conversion module; 2. LDO module; 3. drive module; 4. laser tube; 5. temperature detection module; 6. processor; 7. signal conversion module; 8. oscillator; 11. Buck step-down unit; 12. voltage stabilizing unit; 71. digital-to-analog conversion unit; 72. operational amplifier current limiting unit; 73. first signal conversion unit; 74. second signal conversion unit. DETAILED DESCRIPTION

[0041] Now the utility model is further described in detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the utility model in a schematic manner, and therefore only show the components related to the utility model.

[0042] In the description of the present utility model, it is necessary to understand that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more.

[0043] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] Example 1

[0045] like Figure 2 As shown, it is the first embodiment of the utility model, a laser driving circuit, including: a power conversion module 1, an LDO module 2, a driving module 3 and a laser, the power conversion module 1 is connected to the power input terminal; the LDO module 2 is connected to the power input terminal; the power conversion module 1 and the LDO module 2 are both connected to the driving module 3; the laser tube 4 is connected to the driving module 3. Through the organic combination of the power conversion module 1 and the driving module 3, the power conversion module 1 is used to provide the working voltage and also control the voltage drop of the driving module 3, the LDO module 2 is used to provide the driving current to the driving circuit, the driving module 3 controls the power of the LD branch in the laser to ensure the normal operation of the laser and realize the stable output of the laser power, and the voltage drop of the driving module 3 can be controlled by the power conversion module 1 to avoid the excessive voltage drop of the driving module 3, which makes the circuit efficiency low, thereby causing the problem of large temperature rise change of the circuit, improves the reliability of the circuit, can adapt to lasers with different end voltage drops, has a simple structure and a wide range of applications. In addition, since the driving current of the driving circuit is supplied by the LDO module 2 in a regulated manner, the stability of the power of the laser LD branch controlled by the driving module 3 is further improved, and the performance of the laser driving circuit is further improved.

[0046] In the embodiment, the power conversion module 1 is a DC-DC conversion module with good voltage control stability, which further improves the reliability of the circuit.

[0047] Specifically, Figure 3As shown, the DC-DC conversion module includes a buck chip U1, a capacitor C1, a capacitor C2, an inductor L1 and a capacitor C3. Pin 5 and pin 4 of the buck chip U1 are connected, and after connection, they are connected to one end of the capacitor C1 and the positive electrode of the power input terminal. The other end of the capacitor C1 and pin 2 of the buck chip are connected to the negative electrode of the power input terminal. The negative electrode of the power input terminal is the common ground terminal. Capacitor C2 is connected between pin 1 and pin 6 of the buck chip U1, and after connection, it is connected to one end of the inductor L1. The other end of the inductor L1 is connected to one end of the capacitor C3, which is the output end of the DC-DC conversion module after connection. The other end of the capacitor C3 is connected to pin 3 of the buck chip U1. The set DC-DC module outputs a fixed working voltage after processing the input power signal. Different lasers are adapted by the fixed working voltage. The requirements for the input power signal are low. The input power signal only needs to be greater than the terminal voltage of the laser and the minimum voltage drop of the buck chip in the DC-DC conversion module.

[0048] The LDO module 2 includes a voltage regulator tube, the C end of the voltage regulator tube is connected to the positive electrode of the power input end, the B end of the voltage regulator tube is connected to the common ground end, and the E end of the voltage regulator tube is the output end of the LDO module 2 and is connected to the driving module 3.

[0049] The driving module 3 includes a resistor R1 , a resistor R2 , a resistor R3 , a transistor Q1 , a transistor Q2 , an adjustable resistor W1 , and a capacitor C4 .

[0050] One end of the resistor R2 is connected to the output end of the LDO module 2, the other end of the resistor R2 and the collector of the transistor Q1 are both connected to the base of the transistor Q2, the collector of the transistor Q2 is connected to pin 3 of the buck chip, and is connected to the LD branch of the laser after the connection, the emitter of the transistor Q2 is connected to one end of the resistor R1, the base of the transistor Q1 is connected to one end of the resistor R3, the fixed A end of the adjustable resistor is connected to the PD branch of the laser, the fixed A end of the adjustable resistor is also connected to the variable C end of the adjustable resistor, and is connected to the other end of the resistor R3 after the connection, one end of the capacitor C4 is connected to the output end of the DC-DC conversion module, and the other end of the capacitor C4, the emitter of the transistor Q1, the other end of the resistor R1 and the fixed B end of the adjustable resistor W1 are all connected to the common ground end. The voltage drop of the collector of transistor Q2 is fixed between 0.25 and 0.3 V through pin 3 of the buck chip in the DC-DC conversion module, which ensures that the drive circuit has a certain control range, and does not reduce the efficiency of the circuit due to excessive voltage drop, thereby causing excessive temperature rise of the drive circuit; and the drive current is provided to the resistor R2 of the drive circuit through the LDO module 2, thereby enhancing the stability of the power control of the LD branch in the laser; the capacitor C4 is used to filter the power signal of the DC-DC conversion module, stabilize the power supply of the LD branch in the laser, and improve the stability of the drive circuit; in addition, the laser drive circuit of this embodiment is constructed by discrete components, which can effectively reduce the implementation cost.

[0051] Example 2

[0052] like Figure 4-5 As shown, it is the second embodiment of the utility model, which is different from the first embodiment in that the laser driving circuit further includes: a temperature detection module 5 and a processor 6; the processor 6 is connected to the temperature detection module 5, and the processor 6 is connected to the driving module 3 through the signal conversion module 7. After the laser driving circuit is powered on, the processor 6 starts the temperature detection module 5, collects the temperature of the circuit through the temperature detection module 5 and transmits it to the processor 6, determines the temperature range according to the temperature, and then determines the output current signal and voltage signal; in addition, the processor 6 also sets a corresponding temperature compensation curve according to different laser types, and based on the collected temperature, the type of the current laser performs power compensation on the laser driving circuit to ensure the stability of the laser output power under high and low temperatures.

[0053] In the prior art, the power adjustment steps are cumbersome. When using adjustable resistors for adjustment, it is easy to cause overcurrent damage to the laser due to excessive adjustment. If fixed resistors are used for adjustment, it is necessary to test first and then select suitable resistors for replacement. Welding is required at the debugging site, which has the risk of damage. Moreover, the adjustment process relies entirely on manual labor and has a low degree of automation. The drive module 3 of this embodiment includes a digital adjustable resistor, and the processor 6 is connected to the digital adjustable resistor. The processor 6 automatically controls the digital adjustable resistor and automatically adjusts the resistance value of the digital adjustable resistor, thereby adjusting the driving current value on the transistor Q2 to stabilize the output power of the laser.

[0054] In this embodiment, if Figure 5 As shown, the signal conversion module 7 includes: a digital-to-analog conversion unit 71 and an operational amplifier current limiting unit 72. The processor 6 and the operational amplifier current limiting unit 72 are both connected to the data conversion unit 71, and after being connected, they are connected to the base of the transistor Q2 in the driving circuit. The digital-to-analog conversion unit 71 determines the temperature range according to the temperature, converts the output current signal and voltage signal into a digital signal, and transmits it to the operational amplifier current limiting unit 72. The operational amplifier current limiting unit 72 adjusts the digital signal to keep the output current stable within a certain range, so as to improve the reliability and stability of the circuit.

[0055] In this embodiment, the processor 6 includes at least 4 temperature comparison units, each temperature comparison unit is an independent temperature interval, and the temperature collected by the temperature detection unit is compared with each temperature comparison unit to determine the temperature interval in which the collected temperature is located, so that the processor 6 can accurately perform power compensation on the laser driving circuit according to the determined temperature interval and several temperature compensation curves.

[0056] Example 3

[0057] like Figure 6-8 As shown, it is the third embodiment of the utility model, which is different from the second embodiment in that the power conversion module 1 includes a Buck buck unit 11 and a voltage stabilizing unit 12, the LDO module 2, the voltage stabilizing unit 12 and the driving module 3 are all connected to the Buck buck unit 11; the processor 6 is connected to the voltage stabilizing unit 12.

[0058] In this embodiment, since the current of the inductor L3 in the circuit cannot change suddenly, the startup speed is slow. After the 5V circuit part is powered on successfully, the set LDO module 2 turns on the second MOS tube within the preset time T1 to quickly charge the laser energy storage capacitor, wherein the preset time T1 = 30us. When the output voltage reaches the threshold, the PMOS is turned off within the T2 time, and the laser is powered by the previous LDO module 2 and switched to the Buck step-down unit 11 to avoid current spikes when powered on, resulting in low performance of the laser, that is, the larger current that can be modulated by the set LDO module 2 can pull the output to near the target voltage in a short time, thereby improving the performance of the laser drive circuit.

[0059] It should be noted that when the output voltage reaches the threshold, the PMOS is turned off within T2, and the operating voltage of the laser is switched from the previous LDO module 2 to the Buck step-down unit 11. During the switching, the laser driving circuit has good stability and no instantaneous peak current, which further improves the performance of the laser driving circuit.

[0060] In this embodiment, the processor 6 is also connected to an oscillator 8, which is used to provide a clock signal to the processor 6. The oscillator 8 preferably has a frequency of 2 MHZ, a power consumption of less than 1 mA, and has the advantages of small resonance misalignment and small output temperature drift.

[0061] In this embodiment, if Figure 8 As shown, the driving module 3 includes: a first operational amplifier, a second operational amplifier, a first diode, a first MOS tube, a first resistor and an adjustable resistor; the drain of the first MOS tube and the LD branch of the laser tube 4 are both connected to the Buck step-down unit 11, the positive input ends of the first operational amplifier and the second operational amplifier are respectively connected to the signal conversion module 7, the reverse input end of the second operational amplifier and the PD branch of the laser tube 4 are both connected to the fixed A end of the adjustable resistor, the reverse input end of the first operational amplifier is connected to the source of the first MOS tube, the output end of the first operational amplifier is connected to the cathode of the first diode, the anode of the first diode and the output end of the second operational amplifier are both connected to the gate of the first MOS tube, the variable C end of the adjustable resistor is connected to the processor 6, and the source of the first MOS tube is connected in series with the first resistor and the fixed B end of the adjustable resistor are both connected to the common ground end.

[0062] The DC bias point of the LD branch in the laser is configured through the digital-to-analog conversion module. The LD branch in the laser is quickly switched to current limiting through the second operational amplifier, so that the voltage difference is within 100mV to adjust the first MOS tube of the LD branch. Since the built-in NPN gain of the processor 6 is low, the first MOS tube is controlled by the first and second operational amplifiers to adjust the drive module 3. The PD branch in the laser can be adjusted by changing the resistance value of the adjustable resistor, where the adjustable resistor is roughly adjusted by 1K and finely adjusted by 0.1k; the drive module 3 realizes the current control of the LED branch in the laser through the sampling voltage of the feedback resistor of the PD branch in the laser.

[0063] In this embodiment, the signal conversion module 7 includes a first digital-to-analog conversion unit 73 and a second digital-to-analog conversion unit 74; the input ends of the first digital-to-analog conversion unit 73 and the second digital-to-analog conversion unit 74 are both connected to the processor 6; the output end of the first digital-to-analog conversion unit 73 is connected to the positive input end of the first operational amplifier; the output end of the second digital-to-analog conversion unit 74 is connected to the positive input end of the second operational amplifier. Further, the first digital-to-analog conversion unit 73 and the second digital-to-analog conversion unit 74 both adopt an r2r DAC architecture, which occupies a small size when setting the PCB circuit board and has high precision. Among them, the second digital-to-analog conversion unit 74, the second operational amplifier and the first MOS tube form a maximum current limiting control loop, and the control capability of the maximum current limiting control loop is greater than the control capability of the PD branch.

[0064] Example 4

[0065] A laser adopts the above laser driving circuit.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0067] Based on the above ideal embodiments of the utility model, the relevant staff can make various changes and modifications without departing from the technical concept of the utility model through the above description. The technical scope of the utility model is not limited to the content of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A laser driving circuit, characterized in that: include: A power conversion module (1), connected to a power input terminal; An LDO module (2) connected to a power input terminal; A driving module (3), the power conversion module (1) and the LDO module (2) are both connected to the driving module (3); The laser tube (4) is connected to the driving module (3).

2. The laser driving circuit according to claim 1, characterized in that: Also includes: Temperature detection module (5); A processor (6) is connected to the temperature detection module (5), and the processor (6) is also connected to the driving module (3) via a signal conversion module (7).

3. The laser driving circuit according to claim 1 or 2, characterized in that: The power conversion module (1) is a DC-DC conversion module.

4. The laser driving circuit according to claim 2, characterized in that: The driving module (3) comprises a digitally adjustable resistor, and the processor (6) is connected to the digitally adjustable resistor.

5. The laser driving circuit according to claim 2, characterized in that: The power conversion module (1) comprises a Buck step-down unit (11) and a voltage stabilizing unit (12); the LDO module (2), the voltage stabilizing unit (12) and the driving module (3) are all connected to the Buck step-down unit (11); The processor (6) is connected to the voltage stabilizing unit (12).

6. The laser driving circuit according to claim 5, characterized in that: The processor (6) is also connected to an oscillator (8).

7. The laser driving circuit according to claim 5, characterized in that: The driving module (3) comprises: a first operational amplifier, a second operational amplifier, a first diode, a first MOS tube, a first resistor and an adjustable resistor; The drain of the first MOS tube and the LD branch of the laser tube (4) are both connected to the Buck step-down unit (11); the positive input ends of the first operational amplifier and the second operational amplifier are respectively connected to the signal conversion module (7); the reverse input end of the second operational amplifier and the PD branch of the laser tube (4) are both connected to the fixed A end of the adjustable resistor; the reverse input end of the first operational amplifier is connected to the source of the first MOS tube; the output end of the first operational amplifier is connected to the cathode of the first diode; the anode of the first diode and the output end of the second operational amplifier are both connected to the gate of the first MOS tube; the variable C end of the adjustable resistor is connected to the processor (6); the source of the first MOS tube is connected in series with the first resistor and is connected to the fixed B end of the adjustable resistor to a common ground end.

8. The laser driving circuit according to claim 7, characterized in that: The signal conversion module (7) comprises a first digital-to-analog conversion unit (73) and a second digital-to-analog conversion unit (74); The input ends of the first digital-to-analog conversion unit (73) and the second digital-to-analog conversion unit (74) are both connected to the processor (6); The output terminal of the first digital-to-analog conversion unit (73) is connected to the positive input terminal of the first operational amplifier; The output terminal of the second digital-to-analog conversion unit (74) is connected to the positive input terminal of the second operational amplifier.

9. A laser, characterized in that: The laser uses the laser driving circuit according to any one of claims 1 to 8.

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