Gas detection sensor based on laser unidirectional temperature control

Abstract

The utility model discloses a gas detection sensor based on laser unidirectional temperature control, the sensor comprises a main control chip, a laser and a detector, the laser comprises a laser chip, and integrates a heating resistor wire for heating the laser chip and a temperature sensing device for sensing the temperature of the laser chip, the sensor also comprises a temperature control circuit, the heating resistor wire is connected between the first output end and the second output end of the temperature control circuit; wherein the output end of the temperature sensing device is connected to the first input end of the main control chip, the control end of the temperature control circuit is connected to the first output end of the main control chip, the control end of the laser chip is connected to the second output end of the main control chip, and the output end of the detector is connected to the second input end of the main control chip. The sensor can realize low-cost temperature control of the laser.

Description

Technical Field

[0001] The utility model relates to the technical field of sensors, in particular to a gas detection sensor based on laser unidirectional temperature control. Background Art

[0002] The laser methane sensor using tunable semiconductor laser absorption spectroscopy technology in the related art usually uses a distributed feedback Bragg grating laser diode, which uses the narrow line width and tunable wavelength of the distributed feedback Bragg grating laser diode to scan the characteristic spectrum of the measured gas, thereby measuring the gas concentration. The above-mentioned laser is easily affected by the operating temperature and the wavelength changes. In order to make the driving current scan and cover the characteristic absorption line of the measured gas, the laser operating temperature must be stabilized to achieve precise control of the excitation wavelength. Moreover, the effect of the operating temperature change of the above-mentioned laser on the wavelength is greater than that of the injection current. Specifically, the typical value of the temperature tuning rate is about 0.1nm / ℃, which is one order of magnitude higher than the injection current tuning rate (0.01nm / mA). Therefore, the method of scanning the gas absorption spectrum in the related art is to fix the laser operating temperature and change the excitation wavelength by tuning the driving current to cover the specific absorption spectrum of the measured gas. However, due to the large laser driving current (tens of milliamperes), the laser generates a lot of heat, and the complex working scene causes a large difference in ambient temperature, making it particularly important to control the temperature of the laser. Utility Model Content

[0003] The utility model aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the utility model aims to provide a gas detection sensor based on laser unidirectional temperature control to control the temperature of the laser at a low cost.

[0004] To achieve the above-mentioned purpose, the utility model proposes a gas detection sensor based on laser unidirectional temperature control, wherein the sensor comprises a main control chip, a laser and a detector, wherein the laser comprises a laser chip, and integrates an RH (Resistance Heater, heating resistor wire) for heating the laser chip and a temperature sensing device for sensing the temperature of the laser chip, wherein the sensor also comprises a temperature control circuit, wherein the heating resistor wire is connected between a first output end and a second output end of the temperature control circuit; wherein the output end of the temperature sensing device is connected to a first input end of the main control chip, the control end of the temperature control circuit is connected to a first output end of the main control chip, the control end of the laser chip is connected to a second output end of the main control chip, and the output end of the detector is connected to a second input end of the main control chip.

[0005] According to the gas detection sensor based on laser unidirectional temperature control of the utility model, the sensor includes a main control chip, a laser and a detector, the laser includes a laser chip, and integrates a heating resistor wire for supplying heat to the laser chip and a temperature sensing device for sensing the temperature of the laser chip; wherein the output end of the temperature sensing device is connected to the first input end of the main control chip, the control end of the temperature control circuit is connected to the first output end of the main control chip, the control end of the laser chip is connected to the second output end of the main control chip, and the output end of the detector is connected to the second input end of the main control chip, thereby integrating the heating resistor wire, the temperature sensing device and the laser chip together, sensing the temperature of the laser chip through the temperature sensing device, and sending the temperature of the laser chip to the main control chip, so that the main control chip controls the heating resistor wire according to the temperature of the laser chip, controls the heating resistor wire to be energized to heat the laser chip when the temperature is low, and controls the heating resistor wire to be stopped from being powered when the temperature is high, thereby realizing temperature control of the laser by unidirectional heating, without the need to use TEC, thereby reducing costs.

[0006] Additional aspects and advantages of the present invention will be given in part in the following description and in part will become apparent from the following description or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a structural block diagram of a gas detection sensor based on laser unidirectional temperature control according to an embodiment of the utility model;

[0008] Figure 2 This is a working schematic diagram of a gas detection sensor based on laser unidirectional temperature control according to an embodiment of the utility model;

[0009] Figure 3 It is a circuit diagram of a temperature control circuit of an example of the utility model;

[0010] Figure 4 The utility model is a schematic diagram of a laser one-way temperature control operation of a gas detection sensor according to an example. DETAILED DESCRIPTION

[0011] The following describes a gas detection sensor based on laser unidirectional temperature control according to an embodiment of the utility model with reference to the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described with reference to the accompanying drawings are exemplary and cannot be construed as limiting the utility model.

[0012] In order to achieve temperature control of the laser, a miniaturized TEC (Thermo Electric Cooler) and a laser chip can be packaged together on a laser heat sink carrier, and the cooling and heating characteristics generated by the bidirectional conduction of the TEC can be used to control and stabilize the operating temperature of the laser diode. However, small TECs are completely imported and expensive, which results in a higher price for lasers with temperature control functions, limiting the market application and promotion of the entire laser gas sensor.

[0013] Therefore, the utility model proposes a gas detection sensor based on laser unidirectional temperature control.

[0014] Figure 1 The utility model is a structural block diagram of a gas detection sensor based on laser unidirectional temperature control according to an embodiment of the utility model.

[0015] like Figure 1 As shown, the laser unidirectional temperature-controlled gas detection sensor 100 includes a main control chip 101, a laser 102 and a detector 103. The laser 102 includes a laser chip 1021, and integrates a heating resistor 1022 for supplying heat to the laser chip 1021 and a temperature sensing device 1023 for sensing the temperature of the laser chip 1021. The laser unidirectional temperature-controlled gas detection sensor 100 also includes a temperature control circuit 104. The heating resistor 1022 is connected between a first output end and a second output end of the temperature control circuit 104; wherein the output end of the temperature sensing device 1023 is connected to a first input end of the main control chip 101, the control end of the temperature control circuit 104 is connected to a first output end of the main control chip 101, the control end of the laser chip 1021 is connected to a second output end of the main control chip 101, and the output end of the detector 103 is connected to a second input end of the main control chip 101.

[0016] Thus, the gas detection sensor 100 with laser unidirectional temperature control includes a main control chip 101, a laser 102 and a detector 103, wherein the laser 102 includes a laser chip 1021, and integrates a heating resistor 1022 for supplying heat to the laser chip 1021 and a temperature sensing device 1023 for sensing the temperature of the laser chip 1021; wherein the output end of the temperature sensing device 1023 is connected to the first input end of the main control chip 101, the control end of the temperature control circuit 104 is connected to the first output end of the main control chip 101, the control end of the laser chip 1021 is connected to the second output end of the main control chip 101, and the output end of the detector 103 is connected to the second input end of the main control chip 101. The input end is connected, thereby integrating the heating resistor 1022, the temperature sensing device 1023 and the laser chip 1021, sensing the temperature of the laser chip 1021 through the temperature sensing device 1023, and sending the temperature of the laser chip 1021 to the main control chip 101, so that the main control chip 101 controls the heating resistor 1022 according to the temperature of the laser chip 1021, controls the heating resistor 1022 to be powered on to heat the laser chip 1021 when the temperature is low, and controls the heating resistor 1022 to stop powering on when the temperature is high, thereby realizing temperature control of the laser 102 by unidirectional heating, without using TEC, thereby reducing costs.

[0017] In one embodiment of the present invention, see Figure 2 The laser unidirectional temperature-controlled gas detection sensor 100 further includes: a driving circuit 105, wherein the control end of the driving circuit 105 is connected to the second output end of the main control chip 101, and the output end of the driving circuit 105 is connected to the control end of the laser chip 1021. A photoelectric conversion circuit 106, wherein the input end of the photoelectric conversion circuit 106 is connected to the output end of the detector 103, and the output end of the photoelectric conversion circuit 106 is connected to the second input end of the main control chip 101. An ambient temperature detection module 107, wherein the output end of the ambient temperature detection module 107 is connected to the third input end of the main control chip 101.

[0018] The laser unidirectional temperature-controlled gas detection sensor 100 further includes a power supply and data interaction module 108 , which is used to supply power to the main control chip 101 and provide data interaction between the main control chip 101 and a host computer.

[0019] Specifically, the principle of tunable semiconductor laser absorption spectroscopy technology is to use current tuning or temperature tuning to make the laser 102 scan within a small range of a single absorption frequency. When there is gas absorption, the light intensity changes, and the concentration of the gas is inverted by analyzing the light intensity change detected by the detector 103. In the laser unidirectional temperature-controlled gas detection sensor 100, the internal temperature of the laser 102 is controlled to be stable, and the current is scanned to invert the methane gas concentration.

[0020] exist Figure 2 In the embodiment, the main control chip 101 obtains the temperature of the laser chip 1021 in the laser 102, and adjusts the pulse width of the output PWM (Pulse Width Modulation) wave through the PID (Proportion Integration Differentiation) algorithm based on the temperature of the laser chip 1021. The main control chip 101 outputs the PWM wave to the temperature control circuit 104, so that the temperature control circuit 104 supplies power to the heating resistor 1022 integrated in the laser 102 according to the PWM wave, so that the temperature of the laser chip 1021 can be maintained at a specific temperature.

[0021] Taking methane detection as an example, the main control chip 101 also outputs a scanning voltage signal, and outputs the scanning voltage signal to the driving circuit 105. The driving circuit 105 performs voltage-current conversion on the scanning voltage signal, thereby driving the laser 102 to emit a scanning laser signal.

[0022] After the laser 102 sends out a scanning laser signal, the laser signal is received by the detector 103. The detector 103 obtains an output signal based on the received laser signal, and outputs the output signal to the photoelectric conversion circuit 106. The photoelectric conversion circuit 106 converts the received signal into a voltage signal, and sends the voltage signal to the main control chip 101. The main control signal obtains the methane concentration value based on the voltage signal.

[0023] Moreover, the main control chip 101 also collects the ambient temperature according to the ambient temperature detection module 107 and compensates the methane concentration value according to the ambient temperature.

[0024] The ADC1 of the main control chip 101 collects the internal temperature of the laser 102 in real time, and adjusts the pulse width of the PWM wave through the PID algorithm to achieve temperature control of the laser 102 to a specific temperature.

[0025] The DAC1 of the main control chip 101 outputs a scanning voltage signal, which drives the DFB laser 102 to emit a scanning laser signal through the voltage-current conversion driving circuit 105. The laser signal is received by the detector 103, and the signal output by the detector 103 is converted into a voltage signal by the photoelectric conversion circuit 106 and collected by the ADC2 of the main control chip 101 for signal processing.

[0026] The ADC3 of the main control chip 101 collects the ambient temperature in real time and performs temperature compensation on the inverted methane concentration value. The final measured methane concentration is transmitted to the terminal device through the data interaction interface.

[0027] It should be noted that since the laser 102 needs to have a wider operating temperature range, such as -10°C to 55°C, in order to enable the laser 102 to operate in such a wide range of ambient temperature of -10°C to 55°C, it is necessary to conduct a large number of tests and observations in advance to select the appropriate PWM frequency, heating and temperature acquisition time interval and PID parameters, so as to achieve a wide range of unidirectional heating temperature control with very high stability.

[0028] In one embodiment of the present invention, see Figure 3 The temperature control circuit 104 includes: a first switch tube Q4, a first end of the first switch tube Q4 is connected to the power supply VDD, and a second end of the first switch tube Q4 serves as a first output end RH+ of the temperature control circuit 104; a second switch tube Q5, a first end of the second switch tube Q5 is connected to a control end PWM_CONTR of the first switch tube Q4, a second end of the second switch tube Q5 is grounded, and the control end PWM_CONTR of the second switch tube Q5 serves as a control end PWM_CONTR of the temperature control circuit 104.

[0029] The device also includes: a first capacitor C25, a first end of the first capacitor C25 is connected to the power supply, and a second end of the first capacitor C25 is grounded; a second capacitor C26, a first end of the second capacitor C26 is connected to the power supply, and a second end of the second capacitor C26 is grounded; a third capacitor C28, a third end of the third capacitor C28 is connected to the power supply, and a second end of the third capacitor C28 is grounded; a first resistor R25, a first end of the first resistor R25 is connected to the first end of the first switch tube Q4, and a second end of the first resistor R25 is connected to the control end PWM_CONTR of the first switch tube Q4; a second resistor R30, a first end of the second resistor R30 is connected to the second end of the second switch tube Q5, and a second end of the second resistor R30 is connected to the control end PWM_CONTR of the second switch tube Q5; a third resistor R29, a first end of the third resistor R29 is connected to the control end PWM_CONTR of the second switch tube Q5, and a second end of the third resistor R29 is used as the control end PWM_CONTR of the temperature control circuit 104. RH- is the second output end of the temperature control circuit 104. The second switch tube Q5 receives the PWM wave output by the temperature control circuit 104 through PWM_CONTR. The heating resistor 1022 is connected between RH+ and RH-.

[0030] In one embodiment of the present invention, the main control chip 101 further includes a first data interaction interface, and the first data interaction interface of the main control chip 101 is used to connect to a second data interaction interface of an external terminal device. The temperature sensing device 1023 includes a thermistor.

[0031] See also Figure 4, the temperature of the laser chip 1021 is sensed by the thermistor. The temperature sensing signal is output to the operational amplifier, and the output signal of the operational amplifier is collected to obtain the current temperature of the laser chip 1021. The fuzzy PID control system outputs a PWM wave according to the current temperature of the laser chip 1021 and the temperature control target. The temperature control circuit 104 generates a driving signal according to the PWM wave to drive the heating resistor 1022 to work.

[0032] In summary, the gas detection sensor based on laser unidirectional temperature control in the embodiment of the utility model is provided with a sensor including a main control chip, a laser and a detector, the laser including a laser chip, and integrating a heating resistor wire for supplying heat to the laser chip and a temperature sensing device for sensing the temperature of the laser chip; wherein the output end of the temperature sensing device is connected to the first input end of the main control chip, the control end of the temperature control circuit is connected to the first output end of the main control chip, the control end of the laser chip is connected to the second output end of the main control chip, and the output end of the detector is connected to the second input end of the main control chip, thereby integrating the heating resistor wire, the temperature sensing device and the laser chip together, sensing the temperature of the laser chip through the temperature sensing device, and sending the temperature of the laser chip to the main control chip, so that the main control chip controls the heating resistor wire according to the temperature of the laser chip, controls the heating resistor wire to be energized to heat the laser chip when the temperature is low, and controls the heating resistor wire to be stopped from being powered when the temperature is high, thereby realizing temperature control of the laser by unidirectional heating, without the need to use TEC, thereby reducing costs. Moreover, the laser is heated and controlled by using a dual MOS tube circuit controlled by PWM wave and a PID non-overshoot algorithm, so that the laser temperature works at a constant temperature higher than the environment, and the stability accuracy reaches ±0.1°C. That is to say, in view of the problem that the laser price is high due to the need to package TEC when using bidirectional temperature control, the present invention adopts a unidirectional temperature-controlled laser, which uses a heating resistor wire to replace TEC and is packaged in the laser, and uses a single-chip microcomputer to emit a PWM wave with a specific duty cycle to control the opening and closing of the MOS tube to heat the heating resistor wire. At the same time, the internal thermistor of the laser collects the working temperature of the laser chip in real time, and the PID algorithm adjusts the output PWM wave duty cycle, so that the laser can stably work at a specific working temperature higher than the ambient temperature. This method uses a low-priced heating resistor wire to package the laser, which can achieve the same effect as TEC temperature control, and can also realize gas concentration measurement at different ambient temperatures from -10°C to 55°C, creating favorable conditions for the large-scale application of low-cost laser sensors.

[0033] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0034] It should be understood that the various parts of the utility model can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", 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.

[0036] In the description of this specification, 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 orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as a limitation on the present utility model.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] In the description of this specification, unless otherwise specified, the terms "install", "connect", "connect", "fix" and the like 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 an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0039] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0040] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A gas detection sensor based on laser unidirectional temperature control, characterized in that: The sensor includes a main control chip, a laser and a detector. The laser includes a laser chip and integrates a heating resistor wire for supplying heat to the laser chip and a temperature sensing device for sensing the temperature of the laser chip. The sensor also includes a temperature control circuit. The heating resistor wire is connected between a first output terminal and a second output terminal of the temperature control circuit. Among them, the output end of the temperature sensing device is connected to the first input end of the main control chip, the control end of the temperature control circuit is connected to the first output end of the main control chip, the control end of the laser chip is connected to the second output end of the main control chip, and the output end of the detector is connected to the second input end of the main control chip.

2. The gas detection sensor based on laser unidirectional temperature control according to claim 1 is characterized in that: The sensor also includes: A driving circuit, wherein the control end of the driving circuit is connected to the second output end of the main control chip, and the output end of the driving circuit is connected to the control end of the laser chip.

3. The gas detection sensor based on laser unidirectional temperature control according to claim 1 is characterized in that: The temperature control circuit comprises: a first switch tube, wherein a first end of the first switch tube is connected to a power supply, and a second end of the first switch tube serves as a first output end of the temperature control circuit; A second switch tube, wherein a first end of the second switch tube is connected to a control end of the first switch tube, a second end of the second switch tube is grounded, and the control end of the second switch tube serves as a control end of the temperature control circuit.

4. The gas detection sensor based on laser unidirectional temperature control according to claim 3 is characterized in that: The temperature control circuit further includes: A first capacitor, a first end of the first capacitor is connected to the power supply, and a second end of the first capacitor is grounded; a second capacitor, a first end of the second capacitor being connected to the power supply, and a second end of the second capacitor being grounded; a third capacitor, wherein a third end of the third capacitor is connected to the power supply, and a second end of the third capacitor is grounded; A first resistor, wherein a first end of the first resistor is connected to a first end of the first switch tube, and a second end of the first resistor is connected to a control end of the first switch tube; A second resistor, wherein a first end of the second resistor is connected to a second end of the second switch tube, and a second end of the second resistor is connected to a control end of the second switch tube; A third resistor, wherein a first end of the third resistor is connected to the control end of the second switch tube, and a second end of the third resistor serves as the control end of the temperature control circuit.

5. The gas detection sensor based on laser unidirectional temperature control according to claim 1 is characterized in that: The sensor also includes: A photoelectric conversion circuit, wherein the input end of the photoelectric conversion circuit is connected to the output end of the detector, and the output end of the photoelectric conversion circuit is connected to the second input end of the main control chip.

6. The gas detection sensor based on laser unidirectional temperature control according to claim 1 is characterized in that: The sensor also includes: An ambient temperature detection module, wherein the output end of the ambient temperature detection module is connected to the third input end of the main control chip.

7. The gas detection sensor based on laser unidirectional temperature control according to claim 1 is characterized in that: The main control chip also includes a first data interaction interface, and the first data interaction interface of the main control chip is used to connect to a second data interaction interface of an external terminal device.

8. The gas detection sensor based on laser unidirectional temperature control according to claim 1 is characterized in that: The temperature sensing device includes a thermistor.

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