Temperature control circuit and gas detection equipment

Abstract

The invention discloses a temperature control circuit and gas detection equipment. The temperature control circuit is used for a laser of the gas detection equipment, the temperature control temperature of the laser is higher than the working temperature of the gas detection equipment, the temperature control circuit comprises a temperature sensor, a controller, a feedback module, a correction adjusting module and a driving module, and the temperature sensor is used for acquiring the environment temperature; the controller is connected with the temperature sensor and used for generating a temperature control signal according to the set working temperature, the difference between the set working temperature and the environment temperature and the working parameters of the laser. The feedback module is used for generating temperature feedback signals according to the temperature of the laser; the correction adjusting module is connected with the controller and the feedback module and used for generating a driving signal according to the temperature control signal and the temperature feedback signal; the driving module is connected with the correction adjusting module and the laser and used for generating temperature control voltage according to the driving signal to adjust the current temperature of the laser. According to the temperature control circuit, the temperature control of the laser can be accurately realized at low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas detection, and in particular to a temperature control circuit and a gas detection device. BACKGROUND

[0002] Tunable Diode Laser Absorption Spectroscopy (TDLAS) gas detection technology is a gas detection method based on laser spectroscopy technology. The technology uses the characteristics of narrow linewidth and wavelength change with injected current of a tunable semiconductor laser to achieve accurate measurement of single or several closely spaced and difficult to distinguish absorption lines of gas molecules.

[0003] However, on the one hand, the tunable semiconductor laser is very sensitive to temperature changes. Even if the temperature changes by 1℃, it causes a 0.1nm laser wavelength shift, which leads to poor gas detection results. On the other hand, to meet the temperature control scheme of the tunable semiconductor laser, the design of the temperature control circuit is complex and the cost is high. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application needs to provide a temperature control circuit and a gas detection device.

[0005] The temperature control circuit of the present application embodiment is used for a laser of a gas detection device, the temperature control temperature of the laser is greater than the working temperature of the gas detection device, and the temperature control circuit comprises:

[0006] a temperature sensor for acquiring an environment temperature;

[0007] a controller connected to the temperature sensor, configured to generate a temperature control signal according to a set working temperature, a difference between the set working temperature and the environment temperature, and a working parameter of the laser;

[0008] a feedback module configured to generate a temperature feedback signal according to a current temperature of the laser;

[0009] a correction and adjustment module connected to the controller and the feedback module, configured to generate a driving signal according to the temperature control signal and the temperature feedback signal;

[0010] a driving module connected to the correction and adjustment module and the laser, configured to generate a temperature control voltage according to the driving signal to adjust the current temperature of the laser.

[0011] In some embodiments, the correction and adjustment module comprises an input unit, a feedback correction unit, and an output unit.

[0012] The input unit is connected to the controller;

[0013] The feedback correction unit comprises a first input end, a second input end and an output end, the first input end of the feedback correction unit is connected to the feedback module, and the second input end of the feedback correction unit is connected to the input unit;

[0014] The output unit is connected to the output end of the feedback correction unit and the driving module respectively.

[0015] In some embodiments, the feedback correction unit comprises a negative feedback unit, and the driving module comprises a low dropout linear regulator, a first voltage dividing resistor and a second voltage dividing resistor;

[0016] The low dropout linear regulator is connected to a first power supply end, the correction adjustment module and the laser respectively;

[0017] One end of the first voltage dividing resistor is connected to the low dropout linear regulator;

[0018] One end of the second voltage dividing resistor is connected to the output unit and the other end of the first voltage dividing resistor, and the other end of the second voltage dividing resistor is connected to a ground end.

[0019] In some embodiments, the negative feedback unit comprises a first operational amplifier, a first feedback capacitor, a second feedback capacitor and a first feedback resistor;

[0020] The negative input end of the first operational amplifier is connected to the feedback module, the positive input end of the first operational amplifier is connected to the input unit, and the output end of the first operational amplifier is connected to the output unit;

[0021] One end of the first feedback capacitor is connected to the negative input end of the first operational amplifier, and the other end of the first feedback capacitor is connected to the output end of the first operational amplifier;

[0022] The second feedback capacitor and the first feedback resistor are connected in series between the negative input end of the first operational amplifier and the output end of the first operational amplifier.

[0023] In some embodiments, the feedback correction unit comprises a positive feedback unit, and the driving module comprises a comparison amplifier, a protection resistor and a driving triode;

[0024] The first input end of the comparison amplifier is connected to the output unit, the second input end of the comparison amplifier is connected to the second pole of the driving triode, and the output end of the comparison amplifier is connected to the protection resistor;

[0025] The first pole of the driving triode is connected with a first power supply end, the second pole of the driving triode is connected with the laser, and the control pole of the driving triode is connected with the protection resistor.

[0026] In some embodiments, the positive feedback unit comprises a second operational amplifier, a third feedback capacitor, a fourth feedback capacitor and a second feedback resistor.

[0027] The negative input end of the second operational amplifier is connected with the input unit, the positive input end of the second operational amplifier is connected with the feedback module, and the output end of the second operational amplifier is connected with the output unit.

[0028] One end of the third feedback capacitor is connected with the negative input end of the second operational amplifier, and the other end of the third feedback capacitor is connected with the output end of the second operational amplifier.

[0029] The fourth feedback capacitor and the second feedback resistor are connected in series between the negative input end of the second operational amplifier and the output end of the second operational amplifier.

[0030] In some embodiments, the input unit comprises a first resistor, a second resistor and a first capacitor, and the output unit module comprises an output resistor.

[0031] One end of the first resistor is connected with the controller, and the other end of the first resistor is connected with the second input end of the feedback correction unit.

[0032] The second resistor and the first capacitor are connected in series and connected with the second input end of the feedback correction unit and the ground end respectively.

[0033] One end of the output resistor is connected with the output end of the feedback correction unit, and the other end of the output resistor is connected with the driving module.

[0034] In some embodiments, the working parameters of the laser comprise at least one of a thermal conductivity coefficient, a heat dissipation compensation coefficient and a thermal power of the laser under a current environmental temperature.

[0035] In some embodiments, the feedback module comprises a third voltage dividing resistor and a thermistor, the third voltage dividing resistor and the thermistor are connected in series, and the third voltage dividing resistor and the thermistor are connected across the second power supply end and the ground end.

[0036] The gas detection device of the embodiments of the present application comprises a laser and a temperature control circuit of any of the above embodiments.

[0037] In the temperature control circuit and gas detection device of this application embodiment, the temperature control circuit sets the temperature higher than the operating temperature of the gas detection device. Therefore, the temperature control circuit only needs to heat the laser, reducing its complexity and saving costs. The controller generates a temperature control signal for the laser based on the set operating temperature, the difference between the temperature control signal and the ambient temperature, and the laser's operating parameters. Since the temperature control signal considers both ambient temperature and the laser's own operating parameters, it can more accurately control the laser's temperature, thereby improving the detection accuracy of the gas detection device. Furthermore, the feedback correction module generates a drive signal based on the temperature control signal and the temperature feedback signal, driving the drive module to output a temperature control voltage to the laser, achieving closed-loop temperature control of the laser and further improving the accuracy of the temperature control, thus enhancing the detection accuracy of the gas detection device.

[0038] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0039] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein:

[0040] Figure 1 This is a schematic diagram of the gas detection device according to an embodiment of this application.

[0041] Figure 2 This is a circuit diagram of the temperature control circuit according to an embodiment of this application.

[0042] Figure 3 This is another circuit diagram of the temperature control circuit according to an embodiment of this application.

[0043] Explanation of key component symbols:

[0044] Gas detection equipment 100;

[0045] Temperature control circuit 10, temperature sensor 11, controller 12, feedback module 13, third voltage divider resistor R7, thermistor RH, correction adjustment module 14, input unit 141, first resistor R1, second resistor R2, first capacitor C1, feedback correction unit 142, first operational amplifier F1, second operational amplifier F2, first feedback capacitor C2, second feedback capacitor C3, third feedback capacitor C4, fourth feedback capacitor C5, first feedback resistor R3, second feedback resistor R8, output unit 143, output resistor R4, drive module 15, low dropout linear regulator 151, first voltage divider resistor R5, second voltage divider resistor R6, comparator amplifier F3, protection resistor R9, drive transistor M1;

[0046] Laser 20, heating resistor R, first power supply terminal VDD, second power supply terminal VCC, ground terminal GND. Detailed Implementation

[0047] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0048] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0049] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0050] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0051] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0052] Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a gas detection technique based on laser spectroscopy. This technique utilizes the narrow linewidth and wavelength of a tunable semiconductor laser that change with the injected current to achieve precise measurement of absorption lines of gas molecules that are very close together and difficult to distinguish.

[0053] However, on the one hand, tunable semiconductor lasers are very sensitive to temperature changes. Even a 1°C temperature change can cause a 0.1nm wavelength drift in the laser, resulting in poor gas detection. On the other hand, in order to ensure the temperature of the laser, the temperature control schemes in related technologies use thermoelectric cooler (TEC) driver chips to control the heating or cooling of the laser. However, TEC driver chips are generally expensive and have complex circuit designs.

[0054] In view of this, please combine Figure 1 This application provides a gas detection device 100. The gas detection device 100 may include a laser 20 and a temperature control circuit 10. The temperature control temperature of the laser 20 is higher than the operating temperature of the gas detection device 100. The temperature control circuit 10 is electrically connected to the laser 20 and is used to control the temperature of the laser heater.

[0055] The temperature control circuit 10 includes a temperature sensor 11, a controller 12, a feedback module 13, a correction and adjustment module 14, and a drive module 15. The temperature sensor 11 acquires the ambient temperature. The controller 12 is connected to the temperature sensor 11 and generates a temperature control signal based on the set operating temperature, the difference between the set operating temperature and the ambient temperature, and the operating parameters of the laser 20. The feedback module 13 generates a temperature feedback signal based on the current temperature of the laser 20. The correction and adjustment module 14 is connected to the controller 12 and the feedback module 13 and generates a drive signal based on the temperature control signal and the temperature feedback signal. The drive module 15 is connected to the correction and adjustment module 14 and the laser 20 and generates a temperature control voltage based on the drive signal to adjust the current temperature of the laser 20.

[0056] In the temperature control circuit 10 and gas detection device 100 of this application embodiment, since the temperature control temperature of the laser 20 is set to be higher than the operating temperature of the gas detection device 100, the temperature control circuit 10 only needs to heat the laser 20, which reduces the complexity of the temperature control circuit 10, saves the cost of the gas detection device 100, and improves the product competitiveness of the gas detection device 100. The controller 12 generates a temperature control signal for the laser 20 based on the set operating temperature, the difference between the temperature control signal and the ambient temperature, and the operating parameters of the laser 20. Since the temperature control signal takes into account the influence of the ambient temperature and the laser 20's own operating parameters, it can more accurately control the temperature of the laser 20, thereby improving the detection accuracy of the gas detection device 100. The feedback correction module generates a drive signal based on the temperature control signal and the temperature feedback signal to drive the drive module 15 to output a temperature control voltage to the laser 20, thereby realizing closed-loop temperature control of the laser 20, ensuring the accuracy of the temperature control, avoiding laser wavelength drift, and thus improving the detection accuracy of the gas detection device 100.

[0057] Specifically, the gas detection device 100 is used to detect gases. The gas detection device 100 employs TDLAS gas detection technology. TDLAS gas detection technology utilizes the wavelength modulation of a semiconductor laser to pass through the characteristic absorption region of the gas being measured. When the semiconductor laser emits a laser beam of a specific wavelength that passes through the gas being measured, the gas absorbs the laser beam, causing the laser intensity to attenuate. The attenuation of the laser intensity is proportional to the concentration of the gas being measured. Therefore, by measuring the laser intensity attenuation, the concentration of the gas being measured can be analyzed and obtained. TDLAS gas detection technology has advantages such as high precision, high sensitivity, and fast response.

[0058] The temperature control temperature of laser 20 refers to the temperature that laser 20 needs to reach during operation. The operating temperature of gas detection device 100 refers to the ambient temperature that gas detection device 100 can accept for normal operation. The temperature control temperature of laser 20 is higher than the normal operating temperature of gas detection device 100. For example, in some examples, gas detection device 100 can operate in an ambient temperature range of -10 to 55 degrees Celsius, that is, the operating temperature range of gas detection device 100 is -10 to 55 degrees Celsius, then the temperature control temperature of laser 20 can be 60 degrees Celsius, 70 degrees Celsius, or even higher. In this way, the temperature control circuit 10 only needs to meet the heating and temperature rise requirements of laser 20, without the need for cooling, thus reducing the complexity and cost of the temperature control circuit 10.

[0059] Laser 20 can be a tunable diode laser, which is a type of laser capable of continuously changing its output wavelength within a certain range. Please refer to... Figure 2 orFigure 3 A heating resistor R can be installed inside the laser 20. The heating resistor R is electrically connected to the drive module 15 of the temperature control circuit 10. The heating resistor R is used to heat the laser 20 according to the temperature control voltage output by the drive module 15, thereby achieving heating of the laser 20 and ensuring the precise temperature of the laser 20.

[0060] The controller 12 can be a microcontroller, and it can preset the operating temperature and operating parameters of the laser 20. The operating parameters of the laser 20 may include, but are not limited to, its thermal conductivity, heat dissipation compensation coefficient, and the heat power generated during operation. The operating parameters of the laser 20 are related to the ambient temperature; different ambient temperatures will result in different operating parameters for the laser 20.

[0061] The controller 12 is electrically connected to the temperature sensor 11, and can receive the ambient temperature obtained by the temperature sensor 11. It can also calculate the temperature control signal of the laser 20 based on the set operating temperature, the ambient temperature, and the operating parameters of the laser 20. The temperature control signal can be used to regulate the temperature of the laser 20, and can be a voltage signal. In this embodiment, the operating parameters of the laser 20 are illustrated using all of the above examples. The calculation expression for the temperature control signal can be:

[0062]

[0063] Among them, U 1t For temperature control signal, U 1O To set the operating temperature, Diff is the difference between the set operating temperature and the ambient temperature, Co t For heat dissipation compensation coefficient, LP t This generates thermal power for the laser 20 to operate itself.

[0064] Understandably, since the temperature control signal takes into account the ambient temperature of the laser 20 and its own operating parameters, the temperature control signal can accurately control the temperature of the laser 20 and make the laser 20 more smoothly at the temperature control edge, effectively improving the detection accuracy of the gas detection device 100.

[0065] The feedback module 13 can be partially or wholly located within the laser 20. For example, the feedback module 13 can be adjacent to the heating resistor R of the laser 20. The feedback module 13 is used to output a temperature feedback signal based on the temperature of the laser 20. The temperature feedback signal can be a voltage signal. The higher the temperature of the laser 20, the smaller the temperature feedback signal output by the feedback module 13, and vice versa.

[0066] The correction and adjustment module 14 can employ a closed-loop control circuit. Understandably, a closed-loop control circuit is a control circuit that has a feedback relationship with the controlled object. The closed-loop control circuit achieves precise control of the controlled object by continuously comparing the output signal with the reference input signal and adjusting the control signal based on the comparison result. For example, the closed-loop control circuit can be a proportional-integral-derivative (PID) control circuit. The correction and adjustment module 14 can be electrically connected to the feedback module 13 and the controller 12. The correction and adjustment module 14 can receive the temperature feedback signal output by the receiving feedback module 13 and the temperature control signal output by the controller 12, and output a drive signal based on the comparison result of the temperature feedback signal and the temperature control signal.

[0067] The drive module 15 is electrically connected to the first power supply terminal VDD, the correction and adjustment module 14, and the heating resistor R of the laser 20. The drive module 15 outputs the first power supply voltage provided by the first power supply terminal VDD as a temperature control voltage based on the drive signal output by the correction and adjustment module 14. This causes the heating resistor R to heat up according to the temperature control voltage, thereby raising the temperature of the laser 20 to the set temperature control temperature. Thus, since the drive module 15 controls the temperature of the laser 20 by driving it to heat up according to the drive signal, and the drive signal is generated based on the temperature control signal representing the set operating temperature and the temperature feedback signal representing the actual temperature of the laser 20, closed-loop temperature control of the laser 20 is achieved, further improving the accuracy of temperature control and consequently improving the detection accuracy of the gas detection device 100.

[0068] Please combine Figure 2 or Figure 3 In some embodiments, the correction and adjustment module 14 includes an input unit 141, a feedback correction unit 142, and an output unit 143. The input unit 141 is connected to the controller 12. The feedback correction unit 142 includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the feedback correction unit 142 is connected to the feedback module 13, the second input terminal of the feedback correction unit 142 is connected to the input unit 141, and the output unit 143 is connected to the output terminal of the feedback correction unit 142 and the drive module 15.

[0069] Connecting the input unit 141 to the second input terminal of the feedback correction unit 142 improves the stability and reliability of the feedback correction unit 142 and increases its input impedance. Furthermore, the input unit 141 can limit the input current, preventing damage to the circuit components of the feedback correction unit 142 due to overcurrent. The output unit 143 can limit the output current of the feedback correction unit 142. The feedback correction unit 142 can be either a negative feedback unit or a positive feedback unit. The temperature control signal output by the controller 12 is input to the feedback correction unit 142 after passing through the input signal. The feedback correction unit 142 compares the temperature control signal with the temperature feedback signal to generate a drive signal, which is then output to the drive module 15 via the output unit 143. This ensures that the correction and adjustment module 14 can stably output the drive signal.

[0070] Please combine further Figure 2 or Figure 3 The input unit 141 includes a first resistor R1, a second resistor R2, and a first capacitor C1, while the output unit 143 module includes an output resistor R4. One end of the first resistor R1 is connected to the controller 12, and the other end is connected to the second input terminal of the feedback correction unit 142. The second resistor R2 is connected in series with the first capacitor C1 and is also connected to the second input terminal of the feedback correction unit 142 and the ground terminal GND, respectively. One end of the output resistor R4 is connected to the output terminal of the feedback correction unit 142, and the other end is connected to the drive module 15.

[0071] It should be noted that if the feedback correction unit 142 is a negative feedback unit, then the second input terminal of the feedback correction unit 142 is the positive input terminal and the first input terminal is the negative input terminal. If the feedback correction unit 142 is a positive feedback unit, then the second input terminal of the feedback correction unit 142 is the negative input terminal and the first input terminal is the positive input terminal.

[0072] Please see Figure 2 In some embodiments, the feedback correction unit 142 can be a negative feedback unit, and the drive module 15 includes a low dropout regulator (LDO) 151, a first voltage divider resistor R5, and a second voltage divider resistor R6. The low dropout regulator 151 is connected to the first power supply terminal VDD, the correction adjustment module 14, and the laser 20. One end of the first voltage divider resistor R5 is connected to the low dropout regulator 151; one end of the second voltage divider resistor R6 is connected to the output unit 143 and the other end of the first voltage divider resistor R5, and the other end of the second voltage divider resistor R6 is connected to the ground terminal GND.

[0073] It should be noted that the low-dropout linear regulator 151 is a type of linear DC regulator, characterized by its ability to operate stably with a small input-output voltage difference, outputting a stable DC voltage. The low-dropout linear regulator 151 features low dropout voltage, low power consumption, and high precision. Thus, the drive module 15 can precisely heat the laser 20 through the low-dropout linear regulator 151. Furthermore, since the low-dropout linear regulator 151 has no switching frequency, it has low noise, thereby reducing the noise level of the gas detection device 100 during operation and improving the user experience.

[0074] Please combine Figure 2 When the feedback correction unit 142 is a negative feedback unit, it includes a first operational amplifier F1, a first feedback capacitor C2, a second feedback capacitor C3, and a first feedback resistor R3. The negative input terminal of the first operational amplifier F1 is connected to the feedback module 13, the positive input terminal of the first operational amplifier F1 is connected to the input unit 141, and the output terminal of the first operational amplifier F1 is connected to the output unit 143. One end of the first feedback capacitor C2 is connected to the negative input terminal of the first operational amplifier F1, and the other end of the first feedback capacitor C2 is connected to the output terminal of the first operational amplifier F1. The second feedback capacitor C3 and the first feedback resistor R3 are connected in series between the negative input terminal and the output terminal of the first operational amplifier F1.

[0075] Please see Figure 3 In some embodiments, the feedback correction unit 142 can be a positive feedback unit, and the driving module 15 includes a comparator amplifier F3, a protection resistor R9, and a driving transistor M1. The first input terminal of the comparator amplifier F3 is connected to the output unit 143, the second input terminal of the comparator amplifier F3 is connected to the second terminal of the driving transistor M1, and the output terminal of the comparator amplifier F3 is connected to the protection resistor R9. The first terminal of the driving transistor M1 is connected to the first power supply terminal VDD, the second terminal of the driving transistor M1 is connected to the laser 20, and the control terminal of the driving transistor M1 is connected to the protection resistor R9.

[0076] Thus, the drive module 15 achieves the heating of the laser 20 by setting the comparison amplifier F3, the protection resistor R9 and the drive transistor M1. Since the drive transistor M1 has no switching frequency, the noise is small, thereby reducing the noise of the gas detection device 100 during operation and improving the user experience.

[0077] like Figure 3As shown, when the feedback correction unit 142 is a positive feedback unit, it includes a second operational amplifier F2, a third feedback capacitor C4, a fourth feedback capacitor C5, and a second feedback resistor R8. The negative input terminal of the second operational amplifier F2 is connected to the input unit 141, the positive input terminal of the second operational amplifier F2 is connected to the feedback module 13, and the output terminal of the second operational amplifier F2 is connected to the output unit 143. One end of the third feedback capacitor C4 is connected to the negative input terminal of the second operational amplifier F2, and the other end of the third feedback capacitor C4 is connected to the output terminal of the second operational amplifier F2. The fourth feedback capacitor C5 and the second feedback resistor R8 are connected in series between the negative input terminal and the output terminal of the second operational amplifier F2.

[0078] Please see Figure 2 or Figure 3 In some embodiments, the feedback module 13 includes a third voltage divider resistor R7 and a thermistor RH. The third voltage divider resistor R7 is connected in series with the thermistor RH. The third voltage divider resistor R7 and the thermistor RH are connected in series across the second power supply terminal VCC and the ground terminal GND. Furthermore, the thermistor RH is also connected to the first input terminal of the feedback correction unit 142. The temperature feedback signal output by the feedback module 13 is the voltage of the thermistor RH.

[0079] When the temperature of the laser 20 increases, the resistance of the thermistor RH decreases. Due to the voltage division effect of the thermistor RH and the third voltage divider resistor R7, the output temperature feedback signal decreases. When the temperature of the laser 20 decreases, the resistance of the thermistor RH increases. Due to the voltage division effect of the thermistor RH and the third voltage divider resistor R7, the output temperature feedback signal increases.

[0080] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with the described embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A temperature control circuit for a laser in a gas detection device, characterized in that... The temperature control temperature of the laser is higher than the operating temperature of the gas detection device, and the temperature control circuit includes: Temperature sensor, used to obtain ambient temperature; The controller, connected to the temperature sensor, is used to generate a temperature control signal based on the set operating temperature, the difference between the set operating temperature and the ambient temperature, and the operating parameters of the laser. The feedback module is used to generate a temperature feedback signal based on the current temperature of the laser; A correction and adjustment module, connected to the controller and the feedback module, is used to generate a drive signal based on the temperature control signal and the temperature feedback signal; A drive module, connected to the correction and adjustment module and the laser, is used to generate a temperature control voltage based on the drive signal to adjust the current temperature of the laser.

2. The temperature control circuit according to claim 1, characterized in that, The correction and adjustment module includes an input unit, a feedback correction unit, and an output unit; The input unit is connected to the controller; The feedback correction unit includes a first input terminal, a second input terminal, and an output terminal. The first input terminal of the feedback correction unit is connected to the feedback module, and the second input terminal of the feedback correction unit is connected to the input unit. The output unit is connected to the output terminal of the feedback correction unit and the drive module, respectively.

3. The temperature control circuit according to claim 2, characterized in that, The feedback correction unit includes a negative feedback unit, and the drive module includes a low-dropout linear regulator, a first voltage divider resistor, and a second voltage divider resistor. The low-dropout linear regulator is connected to the first power supply terminal, the correction and adjustment module, and the laser, respectively. One end of the first voltage divider resistor is connected to the low-dropout linear regulator; One end of the second voltage divider resistor is connected to the output unit and the other end of the first voltage divider resistor, and the other end of the second voltage divider resistor is connected to the ground terminal.

4. The temperature control circuit according to claim 3, characterized in that, The negative feedback unit includes a first operational amplifier, a first feedback capacitor, a second feedback capacitor, and a first feedback resistor; The negative input terminal of the first operational amplifier is connected to the feedback module, the positive input terminal of the first operational amplifier is connected to the input unit, and the output terminal of the first operational amplifier is connected to the output unit. One end of the first feedback capacitor is connected to the negative input terminal of the first operational amplifier, and the other end of the first feedback capacitor is connected to the output terminal of the first operational amplifier. The second feedback capacitor and the first feedback resistor are connected in series at the negative input terminal and the output terminal of the first operational amplifier.

5. The temperature control circuit according to claim 2, characterized in that, The feedback correction unit includes a positive feedback unit, and the driving module includes a comparator amplifier, a protection resistor, and a driving transistor. The first input terminal of the comparator amplifier is connected to the output unit, the second input terminal of the comparator amplifier is connected to the second terminal of the driving transistor, and the output terminal of the comparator amplifier is connected to the protection resistor. The first terminal of the driving transistor is connected to the first power supply terminal, the second terminal of the driving transistor is connected to the laser, and the control terminal of the driving transistor is connected to the protection resistor.

6. The temperature control circuit according to claim 5, characterized in that, The positive feedback unit includes a second operational amplifier, a third feedback capacitor, a fourth feedback capacitor, and a second feedback resistor; The negative input terminal of the second operational amplifier is connected to the input unit, the positive input terminal of the second operational amplifier is connected to the feedback module, and the output terminal of the second operational amplifier is connected to the output unit. One end of the third feedback capacitor is connected to the negative input terminal of the second operational amplifier, and the other end of the third feedback capacitor is connected to the output terminal of the second operational amplifier. The fourth feedback capacitor and the second feedback resistor are connected in series at the negative input terminal and the output terminal of the second operational amplifier.

7. The temperature control circuit according to claim 2, characterized in that, The input unit includes a first resistor, a second resistor, and a first capacitor, and the output unit module includes an output resistor; One end of the first resistor is connected to the controller, and the other end of the first resistor is connected to the second input terminal of the feedback correction unit; The second resistor is connected in series with the first capacitor, and is also connected to the second input terminal and the ground terminal of the feedback correction unit, respectively. One end of the output resistor is connected to the output terminal of the feedback correction unit, and the other end of the output resistor is connected to the drive module.

8. The temperature control circuit according to claim 1, characterized in that, The operating parameters of the laser include at least one of the following: thermal conductivity coefficient, heat dissipation compensation coefficient, and thermal power at the current ambient temperature.

9. The temperature control circuit according to claim 1, characterized in that, The feedback module includes a third voltage divider resistor and a thermistor, with the third voltage divider resistor and the thermistor connected in series across the second power supply terminal and the ground terminal.

10. A gas detection device, characterized in that, The gas detection device includes a laser and a temperature control circuit as described in any one of claims 1-9.

Images