Laser driving control circuit of mining laser gas sensor

Abstract

A mining laser gas sensor laser drive control circuit comprises an isolation type current modulation circuit, two input ends of the isolation type current modulation circuit input modulation data INa and INb respectively, an output end of the isolation type current modulation circuit is connected with a negative electrode of a laser diode D1, and the isolation type current modulation circuit is used for injecting modulation current into the laser diode D1 to achieve adjustment and control of the central working wavelength of the laser. Isolation is carried out through the feedback control circuit, and switching noise is reduced; the input end of the power control circuit is connected with the positive electrode of the photodiode D2, the output end of the power control circuit is connected with the negative electrode of the laser diode D1, the power control circuit is used for controlling the power of the laser diode D1 to be stable, and the power control circuit is provided with a temperature compensation module used for conducting temperature compensation to prevent the laser output power from increasing. According to the invention, the modulation current Im and isolation switch noise can stably enter the laser, and the fluctuation of the optical power of the laser caused by temperature change is inhibited within a narrow range, so that the shift of the central working wavelength is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of laser drive control, and more specifically, relates to a laser drive control circuit of a mining laser gas sensor. Background Art

[0002] Coal accounts for a large proportion of my country's energy structure. With the development of the coal mining industry and the emphasis on coal mine safety, the demand for detection of underground coal mine environmental gases (such as methane, carbon monoxide, carbon dioxide, oxygen, etc.) has continued to increase, and mining environmental gas detection technology has also been promoted. From traditional catalytic combustion and electrochemical detection technologies, it has gradually developed towards laser gas detection. Traditional detection technologies and means are limited by their detection principles. Sensors have problems such as easy "poisoning" of the probe, poor zero point stability, long response time, short service life, frequent calibration, and susceptibility to cross-interference from other gases, which cannot be fundamentally solved; laser gas detection technology, using TDLAS (tunable semiconductor laser absorption spectroscopy) technology, has greatly improved the reliability, stability and convenience of underground coal mine gas detection by virtue of its high sensitivity, long calibration cycle, fast response speed, intrinsic safety, long life, no chemical pollution and non-invasive measurement.

[0003] The mining laser gas sensor is mainly composed of laser, laser detector, measurement circuit, data processing circuit, communication transmission circuit, gas chamber and other parts. The detection principle is: the laser is responsible for generating a high-power, high-purity spectrum laser beam of a specific wavelength. When the laser passes through the gas being measured, the light intensity will attenuate. The attenuation of the light intensity follows the Lambert-Beer law, that is, the gas being measured can absorb light of a specific wavelength, and the absorption intensity is proportional to the gas concentration. The gas concentration is measured by measuring the attenuation intensity of the laser passing through the gas. It can be seen that the laser is one of the core components of the sensor, and its stable output central working wavelength is the prerequisite for the accurate and reliable operation of the sensor.

[0004] The existing technologies for laser drive control circuits are:

[0005] The patent with application number CN202310154189.9 discloses a laser drive control circuit, chip and control method, which relates to the technical field of optical communication, wherein the laser drive control circuit includes: a bias current source, a modulation current source, a DC signal generating circuit, a bias current control circuit, an AC signal generating circuit, a modulation current control circuit, and a digital control circuit. This application adopts a structure in which the AC signal generating circuit and the DC signal generating circuit are separated, and an AC signal generating circuit is provided for generating an AC current signal with the same phase as the modulation current signal, and a modulation current control circuit structure that processes the AC component in the AC current signal and the monitoring current signal, performs phase detection, and outputs a modulation current control signal.

[0006] The patent with application number CN202311650955.7 discloses a burst mode laser drive control circuit and method, including: a current source for outputting a constant current; a signal generating unit for outputting a high level or a low level to a burst modulation unit, and adjusting the duty ratio of the high level and the low level; a burst modulation unit for transmitting the current output by the current source to the laser when the signal generating unit outputs a high level, and transmitting the current output by the current source to a balanced load when the signal generating unit outputs a low level; a balanced load for receiving the current output by the current source when the laser is in an open circuit state; when the burst modulation unit outputs a low level, the laser is in an open circuit state.

[0007] However, the above inventions do not take into account the influence of temperature and noise. Noise can cause laser power fluctuations, and temperature changes can cause the nominal central operating wavelength of the laser diode to shift. Figure 2 As shown in the figure, the increase of ambient temperature will lead to the increase of laser output power, making the working wavelength longer, that is, the central working wavelength changes positively with the ambient temperature. Figure 2 In the experiment, when the ambient temperature changes from -40℃ to 60℃, the central working wavelength shifts from -650nm to 350nm, while the mining laser gas sensor allows the central working wavelength to change within the range of ±100nm. This means that measuring the same concentration of gas at different ambient temperatures will lead to large deviations in the measurement results. Summary of the invention

[0008] In order to solve the deficiencies in the prior art, the present invention provides a laser driving control circuit for a mining laser gas sensor, which performs switching noise isolation through a feedback control circuit and performs temperature compensation by utilizing the negative correlation between the conduction voltage of a diode PN connection and the temperature.

[0009] The present invention adopts the following technical solution.

[0010] The first aspect of the present invention proposes a laser driving control circuit for a mining laser gas sensor. The mining laser includes a laser diode D1 and a photodiode D2. The laser diode D1 is a laser emitting component of the laser. The photodiode D2 is used to convert the optical signal emitted by D1 into a monitoring current I p , detect the optical power of the laser diode; the drive control circuit includes an isolated current modulation circuit and a power control circuit, specifically:

[0011] The isolated current modulation circuit includes a feedback control circuit and a current regulation circuit, wherein the current regulation circuit includes a differential pair structure composed of a first transistor Q1 and a second transistor Q2, and modulation data INa and INb are respectively input to two input ends of the differential pair, and the collector of the second transistor Q2 is connected to the negative electrode of the laser diode D1 as the output end of the current regulation circuit, and the output end injects a modulation current I into the laser diode m ; Feedback control circuit, feedback voltage circuit output and modulation current I m Proportional to the feedback voltage V fb , use the feedback voltage to provide feedback to the current regulation circuit;

[0012] The power control circuit has its input connected to the positive electrode of the photodiode D2, and its output connected to the negative electrode of the laser diode D1. p Related bias current.

[0013] Preferably, the current modulation circuit in the isolated current modulation circuit includes a first transistor Q1, a second transistor Q2, a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a collector resistor R c And the ground resistance R m ;

[0014] The first transistor Q1 and the second transistor Q2 are a differential pair structure. The modulation data INa and INb are respectively coupled to the base of the first transistor Q1 and the second transistor Q2 through the first capacitor C1 and the second capacitor C2, and the modulation current I is output through the collector of the second transistor Q2. m To the cathode of the laser diode D1, the emitters of the first transistor Q1 and the second transistor Q2 are connected and connected to the ground resistor R m One end is connected to the ground resistor R m The other end of the first transistor Q1 is grounded, and the collector of the first transistor Q1 is connected to one end of the collector resistor Rc, R c The other end of the first resistor R1 is connected to VCC, the base of the first transistor Q1 is connected to one end of the first resistor R1, and the base of the second transistor Q2 is connected to one end of the second resistor R2; the other ends of the first resistor R1 and the second resistor R2 are connected to the difference voltage V mcconnected, the difference voltage V mc The feedback voltage V fb and the reference voltage V for setting the modulation current value mref The voltage associated with the difference between

[0015] Preferably, the regulation voltage is generated by a first operational amplifier U1, and a reference voltage V for setting the modulation current value is input to the non-inverting input terminal of the first operational amplifier U1. mref , the feedback voltage V is input to the inverting input terminal of the first operational amplifier U1 fb , the output terminal of the first operational amplifier U1 outputs a difference voltage V mc The output end of the first operational amplifier U1 is connected to the other end of the first resistor R1 and the other end of the second resistor R2.

[0016] Preferably, the feedback control circuit in the isolated current modulation circuit includes a bias circuit and a feedback resistor R fb , the input difference voltage V mc , the output of the bias circuit and the feedback resistor R fb One end of the feedback resistor R fb The other end of the feedback resistor R fb The voltage at one end is the feedback voltage V fb .

[0017] Preferably, the bias circuit includes a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, and a seventh resistor R7;

[0018] The base of the third transistor Q3 is connected to the differential voltage V as the input terminal of the bias circuit. mc The base of the fourth transistor Q4 is connected to the bias voltage V bias The base of the fifth transistor Q5, the emitter of the third transistor Q3 and the collector of the fourth transistor Q4 are connected, and the emitter of the fifth transistor Q5 serves as the output end of the bias circuit and the feedback resistor R fb One end is connected.

[0019] Preferably, the bias voltage V bias , so that the feedback current I fb With the modulation current I m Proportional, I m =I fb *Y, Y represents the feedback current proportional factor. At the same time, after the feedback is stabilized, the modulation current I m The reference voltage V mref Proportional, I m =(V mref *Z) / R m , where Z represents the modulation current scale factor.

[0020] Preferably, the power control circuit includes a second operational amplifier U2, a third resistor R3, a fourth resistor R4, a sixth resistor R6, a fourth capacitor C4 and a bias current source I bias ;

[0021] The inverting input terminal of the second operational amplifier U2, one end of the third resistor R3, one end of the third capacitor C3 and one end of the fourth capacitor C4 are connected as the input terminal of the power control circuit, and the other end of the third resistor R3 and the other end of the third capacitor C3 are grounded;

[0022] The fourth resistor R4 and the sixth resistor R6 are sequentially connected in series between VCC and ground to form a forward voltage dividing network, and the connection point between the fourth resistor R4 and the sixth resistor R6 is connected to the non-inverting input terminal of the second operational amplifier U2;

[0023] The output end of the second operational amplifier U2, the other end of the fourth capacitor C4 and the control end of the bias current source Ibias are connected. The output end of the second operational amplifier U2 outputs a regulation voltage V adj Adjust the bias current source, bias current source I bias Connect between laser diode D1 and ground.

[0024] Preferably, a diode is added to the power control circuit, and the diode is connected between the fourth resistor R4 and the sixth resistor R6, the positive electrode of the diode, one end of the fourth resistor R4 and the in-phase input terminal of the second operational amplifier U2 are connected, and the negative electrode of the diode is connected to one end of the sixth resistor R6.

[0025] Preferably, the conduction threshold voltage of the diode PN junction has a characteristic of being negatively correlated with temperature, and the power control reference voltage V input to the non-inverting input terminal of the second operational amplifier U2 is ref , whose value is:

[0026]

[0027] Among them, V th It is the conduction threshold voltage of the diode PN junction.

[0028] The second aspect of the present invention provides a method for driving and controlling a laser gas sensor for a mine using the control circuit described in the first aspect of the present invention, comprising:

[0029] Adjust the bias voltage V bias , so that the feedback resistor R fb Feedback current I fb With the modulation current I m proportional to the feedback resistor R fb The voltage across the two ends is V fb As the feedback voltage, the feedback voltage Vfb is coupled to the inverting input terminal of the first amplifier U1, which senses the feedback voltage V fb With reference voltage V mref The difference between the output voltage V mc , the difference voltage V mc The bases of the differential pair of transistors Q1 and Q2 are coupled to the modulation current I m To adjust the modulation current I m Adjust to the required value; when the feedback voltage V fb is regulated to the reference voltage V mref When the feedback is stable, the resistance to ground R m The feedback voltage V m It is also regulated to the reference voltage V mref Proportional, that is: I m =(V mref *Z) / R m , where Z represents the scale factor;

[0030] When the ambient temperature rises, the average optical power deviation of the laser diode D1 increases, and the conduction threshold voltage V th Compared with the temperature before the increase, the reference voltage V ref decreases, causing the power control reference voltage V ref With monitoring voltage V p The difference is reduced, and the error amplifier U2 outputs the regulated voltage V adj Reduce, bias current I bias Reduce accordingly.

[0031] The beneficial effect of the present invention is that, compared with the prior art,

[0032] By introducing a feedback control circuit that is independent of the modulation signals INa and INb, the feedback voltage V fb It is isolated from the switching noise generated by the modulation signal, and the base DC bias voltage of the differential pair of transistors Q1 and Q2 is adjusted through the isolated feedback circuit to achieve a stable modulation current I m And the purpose of isolating switching noise from entering the laser.

[0033] The forward voltage of the diode PN junction changes linearly with the temperature in a certain temperature range, which is negatively correlated with the temperature. That is, the forward voltage drop of the PN junction decreases by 2mV to 2.5mV for every 1°C increase in temperature. Using this temperature characteristic of the diode, a temperature compensation circuit is constructed to generate a temperature-related reference voltage V at the non-inverting input of the error amplifier U2. ref , the fluctuation of laser optical power caused by temperature change is suppressed within a narrow range, thereby effectively reducing the shift of the central working wavelength. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the laser drive control schematic diagram of a mining laser gas sensor with isolation and temperature compensation functions;

[0035] Figure 2 This is the temperature characteristic curve of the laser gas sensor currently used in mining;

[0036] Figure 3 This is a temperature characteristic curve of the laser gas sensor for mining with temperature compensation. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0038] like Figure 1 As shown, Embodiment 1 of the present invention provides a laser driving control circuit for a mining laser gas sensor. The mining laser includes a laser diode D1 and a photodiode D2. The laser diode D1 is a laser emitting component of the laser. The photodiode D2 is used to convert the optical signal emitted by D1 into a monitoring current I p , detect the optical power of the laser diode; the drive control circuit includes an isolated current modulation circuit and a power control circuit, specifically:

[0039] The isolated current modulation circuit includes a feedback control circuit and a current regulation circuit, wherein the current regulation circuit includes a differential pair structure composed of a first transistor Q1 and a second transistor Q2, and modulation data INa and INb are respectively input to two input ends of the differential pair, and the collector of the second transistor Q2 is connected to the negative electrode of the laser diode D1 as the output end of the current regulation circuit, and the output end injects a modulation current I into the laser diode m ; Feedback control circuit, feedback voltage circuit output and modulation current I m Proportional to the feedback voltage V fb , use the feedback voltage to provide feedback to the current regulation circuit;

[0040] The input end of the power control circuit is connected to the positive electrode of the photodiode D2, and the output end is connected to the negative electrode of the laser diode D1. p Related bias current.

[0041] Preferably, the current modulation circuit in the isolated current modulation circuit includes a first transistor Q1, a second transistor Q2, a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a collector resistor R c And the ground resistance R m ;

[0042] The first transistor Q1 and the second transistor Q2 are a differential pair structure. The modulation data INa and INb are respectively coupled to the base of the first transistor Q1 and the second transistor Q2 through the first capacitor C1 and the second capacitor C2, and the modulation current I is output through the collector of the second transistor Q2. m To the cathode of the laser diode D1, the emitters of the first transistor Q1 and the second transistor Q2 are connected, and connected to the ground resistor R m One end is connected to the ground resistor R m The other end of the first transistor Q1 is grounded, and the collector of the first transistor Q1 is connected to one end of the collector resistor Rc, R c The other end of the first resistor R1 is connected to VCC, the base of the first transistor Q1 is connected to one end of the first resistor R1, and the base of the second transistor Q2 is connected to one end of the second resistor R2; the other ends of the first resistor R1 and the second resistor R2 are connected to the difference voltage V mc connected, the difference voltage V mc The feedback voltage V fb and the reference voltage V for setting the modulation current value mref The voltage associated with the difference between

[0043] Preferably, the regulation voltage is generated by a first operational amplifier U1, and a reference voltage V for setting the modulation current value is input to the non-inverting input terminal of the first operational amplifier U1. mref , the feedback voltage V is input to the inverting input terminal of the first operational amplifier U1 fb , the output terminal of the first operational amplifier U1 outputs a difference voltage V mc The output end of the first operational amplifier U1 is connected to the other end of the first resistor R1 and the other end of the second resistor R2.

[0044] Preferably, the feedback control circuit in the isolated current modulation circuit includes a bias circuit and a feedback resistor R fb , the input difference voltage V mc , the output of the bias circuit and the feedback resistor R fb One end of the feedback resistor R fb The other end of the feedback resistor R fb The voltage at one end is the feedback voltage V fb .

[0045] The bias circuit includes a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, and a seventh resistor R7;

[0046] The base of the third transistor Q3 is connected to the differential voltage V as the input terminal of the bias circuit. mc The base of the fourth transistor Q4 is connected to the bias voltage V bias The base of the fifth transistor Q5, the emitter of the third transistor Q3 and the collector of the fourth transistor Q4 are connected, and the emitter of the fifth transistor Q5 serves as the output end of the bias circuit and the feedback resistor R fb One end is connected.

[0047] Preferably, the bias voltage V bias , so that the feedback current I fb With the modulation current I m Proportional, I m =I fb *Y, Y represents the feedback current proportional factor. At the same time, after the feedback is stabilized, the modulation current I m The reference voltage V mref Proportional, I m =(V mref *Z) / R m , where Z represents the modulation current scale factor.

[0048] Preferably, the power control circuit includes a second operational amplifier U2, a third resistor R3, a fourth resistor R4, a sixth resistor R6, a fourth capacitor C4 and a bias current source I bias ;

[0049] The inverting input terminal of the second operational amplifier U2, one end of the third resistor R3, one end of the third capacitor C3 and one end of the fourth capacitor C4 are connected as the input terminal of the power control circuit, and the other end of the third resistor R3 and the other end of the third capacitor C3 are grounded;

[0050] The fourth resistor R4 and the sixth resistor R6 are sequentially connected in series between VCC and ground to form a forward voltage dividing network, and the connection point between the fourth resistor R4 and the sixth resistor R6 is connected to the non-inverting input terminal of the second operational amplifier U2;

[0051] The output end of the second operational amplifier U2, the other end of the fourth capacitor C4 and the control end of the bias current source Ibias are connected. The output end of the second operational amplifier U2 outputs a regulation voltage V adj Adjust the bias current source, bias current source I bias Connect between laser diode D1 and ground.

[0052] Preferably, a diode is added to the power control circuit, and the diode is connected between the fourth resistor R4 and the sixth resistor R6, the positive electrode of the diode, one end of the fourth resistor R4 and the in-phase input terminal of the second operational amplifier U2 are connected, and the negative electrode of the diode is connected to one end of the sixth resistor R6.

[0053] It should be noted that the photodiode D2 converts the light emitted by the laser diode D1 into a monitoring current I p , and then the monitoring current I p Converted into monitoring voltage V p , applied to the inverting input terminal of the error amplifier U2, and the third capacitor C3 is used to filter the monitoring current I p The AC component in the laser diode D1 is retained, and the DC component is retained, that is, the average optical power of the laser diode D1. The fourth resistor R4 and the fifth resistor R5 form a voltage divider resistor network to generate a reference voltage V for power control at the node T. ref , applied to the non-inverting input of the error amplifier U2, the error amplifier U2 will monitor the voltage V p The power control reference voltage V ref For comparison, the output regulation voltage V adj , to adjust the bias current I of the laser diode D1 bias , so that the average optical power meets the requirements. For example, when the monitoring voltage V p After the power control reference voltage V ref With monitoring V p The difference increases, and the error amplifier U2 amplifies the difference, and the output regulation voltage V adj becomes larger, the bias current I bias The power of the laser diode D1 increases accordingly, thereby achieving the purpose of stabilizing the DC power.

[0054] Preferably, the conduction threshold voltage of the diode PN junction has a characteristic of being negatively correlated with temperature, and the power control reference voltage V input to the non-inverting input terminal of the second operational amplifier U2 is ref , whose value is:

[0055]

[0056] Among them, Vt h It is the conduction threshold voltage of the diode PN junction.

[0057] It should be noted that the reference voltage V ref The conduction threshold voltage V of the diode PN junction th Positive correlation. From the temperature characteristics of the diode PN junction, it can be seen that within a certain temperature range, the conduction threshold voltage V thIt changes linearly with negative correlation with temperature. In the range of -40℃~60℃, the conduction threshold voltage V of the diode PN junction increases with each 1℃ increase in temperature. th Reduce by 2mV~2.5mV.

[0058] After temperature compensation, the shift effect of the laser center working wavelength is well suppressed, such as Figure 3 When the ambient temperature changes within the range of -40℃~60℃, the shift of the central working wavelength is limited to a narrow range of -40nm~20nm, which fully meets the error accuracy requirement of the mining laser gas sensor for the central working wavelength of ±100nm.

[0059] The second aspect of the present invention provides a method for driving and controlling a laser gas sensor for a mine using the control circuit described in the first aspect of the present invention, comprising:

[0060] Adjust the bias voltage V bias , so that the feedback resistor R fb Feedback current I fb With the modulation current I m proportional to the feedback resistor R fb The voltage across the two ends is V fb As the feedback voltage, the feedback voltage V fb is coupled to the inverting input terminal of the first amplifier U1, which senses the feedback voltage V fb With reference voltage V mref The difference between the output voltage V mc , the difference voltage V mc The bases of the differential pair of transistors Q1 and Q2 are coupled to the modulation current I m To adjust the modulation current I m Adjust to the required value; when the feedback voltage V fb is regulated to the reference voltage V mref When the feedback is stable, the resistance to ground R m The feedback voltage V m is also regulated to the reference voltage V mref Proportional, that is: I m =(V mref *Z) / R m , where Z represents the proportional factor; thereby achieving the purpose of isolating the feedback voltage from the switching noise output to the laser diode D1.

[0061] When the ambient temperature rises, the average optical power deviation of the laser diode D1 increases, and the conduction threshold voltage V th Compared with the temperature before the increase, the reference voltage V ref decreases, causing the power control reference voltage Vref With monitoring voltage V p The difference is reduced, and the error amplifier U2 outputs the regulated voltage V adj Reduce, bias current I bias The output power of the laser diode D1 is reduced accordingly, completing the closed-loop feedback and compensation of temperature regulation.

[0062] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0063] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0064] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0065] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A laser driving control circuit for a mining laser gas sensor. The mining laser includes a laser diode D1 and a photodiode D2. The laser diode D1 is the laser emitting component of the laser. The photodiode D2 is used to convert the optical signal emitted by D1 into a monitoring current I p , detecting the optical power of the laser diode; the drive control circuit includes an isolated current modulation circuit and a power control circuit, characterized in that: The isolated current modulation circuit includes a feedback control circuit and a current regulation circuit, wherein the current regulation circuit includes a differential pair structure composed of a first transistor Q1 and a second transistor Q2, and modulation data INa and INb are respectively input to two input ends of the differential pair, and the collector of the second transistor Q2 is connected to the negative electrode of the laser diode D1 as the output end of the current regulation circuit, and the output end injects a modulation current I into the laser diode m ; Feedback control circuit, feedback voltage circuit output and modulation current I m Proportional to the feedback voltage V fb , use the feedback voltage to provide feedback to the current regulation circuit; The input end of the power control circuit is connected to the positive electrode of the photodiode D2, and the output end is connected to the negative electrode of the laser diode D1. p Related bias current.

2. The laser driving control circuit of a mining laser gas sensor according to claim 1, characterized in that: The current modulation circuit in the isolated current modulation circuit includes a first transistor Q1, a second transistor Q2, a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a collector resistor R c And the ground resistance R m ; The first transistor Q1 and the second transistor Q2 are a differential pair structure. The modulation data INa and INb are respectively coupled to the base of the first transistor Q1 and the second transistor Q2 through the first capacitor C1 and the second capacitor C2, and the modulation current I is output through the collector of the second transistor Q2. m To the cathode of the laser diode D1, the emitters of the first transistor Q1 and the second transistor Q2 are connected and connected to the ground resistor R m One end is connected to the ground resistor R m The other end of the first transistor Q1 is grounded, and the collector of the first transistor Q1 is connected to one end of the collector resistor Rc, R c The other end of the first resistor R1 is connected to VCC, the base of the first transistor Q1 is connected to one end of the first resistor R1, and the base of the second transistor Q2 is connected to one end of the second resistor R2; the other ends of the first resistor R1 and the second resistor R2 are connected to the difference voltage V mc connected, the difference voltage V mc The feedback voltage V fb and the reference voltage V for setting the modulation current value mref The voltage associated with the difference between 3. A mining laser gas sensor laser drive control circuit according to claim 2, characterized in that: The regulation voltage is generated by the first operational amplifier U1, and the reference voltage V for setting the modulation current value is input into the non-inverting input terminal of the first operational amplifier U1. mref , the feedback voltage V is input to the inverting input terminal of the first operational amplifier U1 fb , the output terminal of the first operational amplifier U1 outputs a difference voltage V mc The output end of the first operational amplifier U1 is connected to the other end of the first resistor R1 and the other end of the second resistor R2.

4. A laser driving control circuit for a mining laser gas sensor according to claim 2 or 3, characterized in that: The feedback control circuit in the isolated current modulation circuit includes a bias circuit and a feedback resistor R fb , the input difference voltage V mc , the output of the bias circuit and the feedback resistor R fb One end of the feedback resistor R fb The other end of the feedback resistor R fb The voltage at one end is the feedback voltage V fb .

5. A laser driving control circuit for a mining laser gas sensor according to claim 4, characterized in that: The bias circuit includes a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, and a seventh resistor R7; The base of the third transistor Q3 is connected to the differential voltage V as the input terminal of the bias circuit. mc The base of the fourth transistor Q4 is connected to the bias voltage V bias The base of the fifth transistor Q5, the emitter of the third transistor Q3 and the collector of the fourth transistor Q4 are connected, and the emitter of the fifth transistor Q5 serves as the output end of the bias circuit and the feedback resistor R fb One end is connected.

6. A laser driving control circuit for a mining laser gas sensor according to claim 5, characterized in that: Adjust the bias voltage V bias , so that the feedback current I fb With the modulation current I m Proportional, I m =I fb *Y, Y represents the feedback current proportional factor. At the same time, after the feedback is stabilized, the modulation current I m The reference voltage V mref Proportional, I m =(V mref *Z) / R m , where Z represents the modulation current scale factor.

7. The laser driving control circuit of a mining laser gas sensor according to claim 1, characterized in that: The power control circuit includes a second operational amplifier U2, a third resistor R3, a fourth resistor R4, a sixth resistor R6, a fourth capacitor C4 and a bias current source I bias ; The inverting input terminal of the second operational amplifier U2, one end of the third resistor R3, one end of the third capacitor C3 and one end of the fourth capacitor C4 are connected as the input terminal of the power control circuit, and the other end of the third resistor R3 and the other end of the third capacitor C3 are grounded; The fourth resistor R4 and the sixth resistor R6 are sequentially connected in series between VCC and ground to form a forward voltage dividing network, and the connection point between the fourth resistor R4 and the sixth resistor R6 is connected to the non-inverting input terminal of the second operational amplifier U2; The output end of the second operational amplifier U2, the other end of the fourth capacitor C4 and the control end of the bias current source Ibias are connected. The output end of the second operational amplifier U2 outputs a regulation voltage V adj Adjust the bias current source, bias current source I bias Connect between laser diode D1 and ground.

8. The laser driving control circuit of a mining laser gas sensor according to claim 7, characterized in that: The power control circuit is added with a diode, which is connected between the fourth resistor R4 and the sixth resistor R6. The anode of the diode and one end of the fourth resistor R4 are connected to the in-phase input terminal of the second operational amplifier U2, and the cathode of the diode is connected to one end of the sixth resistor R6.

9. A laser driving control circuit for a mining laser gas sensor according to claim 8, characterized in that: The conduction threshold voltage of the diode PN junction has a characteristic of being negatively correlated with temperature. The power control reference voltage V input to the non-inverting input terminal of the second operational amplifier U2 is ref , whose value is: Among them, V th It is the conduction threshold voltage of the diode PN junction.

10. A method for driving and controlling a laser gas sensor for mining using the control circuit of claims 1-9, characterized in that: include: Adjust the bias voltage V bias , so that the feedback resistor R fb Feedback current I fb With the modulation current I m proportional to the feedback resistor R fb The voltage across the two ends is V fb As the feedback voltage, the feedback voltage V fb is coupled to the inverting input terminal of the first amplifier U1, which senses the feedback voltage V fb With reference voltage V mref The difference between the output voltage V mc , the difference voltage V mc The bases of the differential pair of transistors Q1 and Q2 are coupled to the modulation current I m To adjust the modulation current I m Adjust to the required value; when the feedback voltage V fb is regulated to the reference voltage V mref When the feedback is stable, the resistance to ground R m The feedback voltage V m It is also regulated to the reference voltage V mref Proportional, that is: I m =(V mref *Z) / R m , where Z represents the scale factor; When the ambient temperature rises, the average optical power deviation of the laser diode D1 increases, and the conduction threshold voltage V th Compared with the temperature before the increase, the reference voltage V ref decreases, causing the power control reference voltage V ref With monitoring voltage V p The difference is reduced, and the error amplifier U2 outputs the regulated voltage V adj Reduce, bias current I bias Reduce accordingly.

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