[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.
[0034] The embodiment of the present invention discloses a circuit and method for automatic zero point calibration of a sensor, so as to realize that the zero point of the sensor can be automatically calibrated, and then the sensor can detect an accurate gas concentration.
[0035] Such as figure 2 As shown, the embodiment discloses a circuit for automatic zero point calibration of a sensor, including: a detector 21, a compensator 22, a first resistor 23, a second resistor 24, a voltage output circuit 25 and a controller 26; wherein:
[0036] The detector 21, the compensator 22, the first resistor 23 and the second resistor 24 are electrically connected to form a single-arm bridge;
[0037] One end of the controller 26 is connected to the common electrical connection end of the detector 24 and the compensator 22, and the other end is connected to the common electrical connection end of the first resistor 23 and the second resistor 24 for detecting the output voltage of the single-arm bridge , And determine whether the output voltage is normal, and if it is not normal, generate a control signal according to the output voltage, and send the control signal;
[0038] One end of the voltage output circuit 25 is electrically connected to the controller 26, and the other end is connected to the common electrical connection end of the first resistor 23 and the second resistor 24, for receiving the control signal sent by the controller 26, and according to the control signal The output voltage adjusts the output voltage of the single-arm bridge to zero.
[0039] In the above embodiment, when the sensor starts to work, a fixed operating voltage is provided to the sensor through the power input terminal.
[0040] When the sensor is in the initial working phase, the detector (black element) 21 and the compensator (white element) 22 enter the preheating phase. At this time, the voltage at the output of the single-arm bridge will change from high to low. When the detector (black element) ) 21 and the compensator (white element) 22 reach thermal equilibrium after a period of time. At this time, the output voltage of the single-arm bridge should be zero and the zero point of the sensor;
[0041] Therefore, in order to enable the sensor to be in the zero state before detecting the gas concentration, when the detector (black element) 21 and the compensator (white element) 22 enter the preheating phase, the voltage at the output of the single-arm bridge changes from high to low. In this, the controller 26 detects the output voltage of the single-arm bridge, generates a control signal according to the output voltage, and sends the generated control signal to the voltage output circuit 25. The voltage output circuit 25 outputs and regulates the single-arm according to the received control signal. The voltage at which the bridge output voltage is zero.
[0042] After the sensor is initialized, it starts to detect the gas concentration. When the detected gas is present, the detector (black element) 21 will oxidize with the gas, and the generated heat will increase the resistance of the black element, and the compensator (white element) 22 will not Reacts with gas, the resistance of the white element will not change, the bridge loses balance, and the output voltage signal is proportional to the gas concentration;
[0043] If the voltage at the output of the single-arm bridge detected by the controller 26 is a fixed voltage value for a period of time, it indicates that the sensor has zero drift at this time, and the output of the single-arm bridge detected by the controller 26 The voltage at the terminal generates a control signal and sends the control signal to the voltage output circuit 25, and the voltage output circuit 25 outputs a voltage that makes the single-arm bridge output voltage zero according to the received control signal.
[0044] Or, if the voltage at the output of the single-arm bridge detected by the controller 26 is negative at this time, it indicates that the sensor has reverse drift at this time, and it needs to be generated based on the voltage at the output of the single-arm bridge detected by the controller 26. The control signal is sent to the voltage output circuit 25, and the voltage output circuit 25 outputs a voltage such that the output voltage of the single-arm bridge is zero according to the received control signal.
[0045] In the above-mentioned sensor working process, the controller detects the output voltage of the single-arm bridge in real time, and judges whether the detected output voltage is normal at each stage. When the output voltage is abnormal, a control signal is generated to control the voltage output circuit The output adjusts the voltage of the output voltage of the single-arm bridge, which realizes the automatic zero point calibration of the sensor in real-time, convenient, fast and accurate without human involvement when the zero point of the sensor drifts.
[0046] A schematic diagram of the controller structure disclosed in another embodiment of the present invention, such as image 3 Shown, including:
[0047] The detection unit 31, the judgment unit 32, the control signal generation unit 33 and the sending unit 34; among them:
[0048] The detection unit 31 is connected to the judgment unit 32 and is used to detect the output voltage of the single-arm bridge;
[0049] The judging unit 32 is connected to the control signal generating unit 33, and is used to judge whether the output voltage is a fixed value or a negative value within a certain period of time;
[0050] The control signal generating unit 33 is connected to the sending unit 34, and is configured to generate a control signal when the determining unit 32 determines that the output voltage is a fixed value or a negative value within a certain period of time;
[0051] The sending unit 34 is connected to the voltage output circuit, and is used to send the control signal to the voltage output circuit.
[0052] Specifically, in the initialization phase of the sensor, when the judgment unit 32 judges that the voltage at the output of the single-arm bridge detected by the detection unit 31 changes from high to low, the control signal generation unit 33 generates a control signal according to the output voltage detected by the detection unit 31 , The sending unit 34 sends the generated control signal to the voltage output circuit 25, and the voltage output circuit 25 outputs a voltage that regulates the output voltage of the single-arm bridge to zero according to the received control signal;
[0053] When the sensor is initialized and starts to detect the gas concentration, if the judgment unit 32 determines that the voltage at the output of the single-arm bridge detected by the detection unit 31 is a fixed voltage value for a period of time, it indicates that the sensor is at this time There is a zero point shift, the control signal generation unit 33 generates a control signal according to the output voltage detected by the detection unit 31, the sending unit 34 sends the generated control signal to the voltage output circuit 25, and the voltage output circuit 25 outputs the adjustment unit according to the received control signal. The voltage at which the output voltage of the arm bridge is zero;
[0054] Or, if the judgment unit 32 determines that the voltage at the output of the single-arm bridge detected by the detection unit 31 is negative at this time, it indicates that the sensor has reverse drift at this time, and the control signal generation unit 33 detects according to the detection unit 31 The output voltage of the output voltage generates a control signal, and the sending unit 34 sends the generated control signal to the voltage output circuit 25, and the voltage output circuit 25 outputs a voltage that regulates the output voltage of the single-arm bridge to zero according to the received control signal.
[0055] Another embodiment of the present invention discloses a method for automatic zero point calibration of a sensor, such as Figure 4 Shown, including:
[0056] S101. Detect the output voltage of the single-arm bridge;
[0057] S102, it is determined whether the output voltage is normal, and if it is not normal, it proceeds to step S103;
[0058] S103: Generate a control signal according to the output voltage;
[0059] S104. Adjust the output voltage of the single-arm bridge to zero according to the control signal.
[0060] In the above embodiment, when the detector (black element) and compensator (white element) in the sensor enter the preheating stage, the voltage at the output of the single-arm bridge changes from high to low, and the controller detects the single-arm electric The output terminal voltage of the bridge generates a control signal according to the output voltage, and sends the generated control signal to the voltage output circuit. The voltage output circuit outputs a voltage that makes the single-arm bridge output voltage zero according to the received control signal.
[0061] After the sensor is initialized, it starts to detect the gas concentration. When there is a detected gas, if the voltage at the output of the single-arm bridge detected by the controller is a fixed voltage value for a period of time, it indicates that the sensor is here. When there is zero drift, it is necessary to generate a control signal according to the voltage at the output of the single-arm bridge detected by the controller, and send the control signal to the voltage output circuit, and the voltage output circuit outputs the single-arm bridge according to the received control signal output The voltage at which the voltage is zero.
[0062] Or, if the voltage at the output of the single-arm bridge detected by the controller is negative at this time, it indicates that the sensor has reverse drift at this time, and the control signal needs to be generated according to the voltage at the output of the single-arm bridge detected by the controller , And send the control signal to the voltage output circuit, and the voltage output circuit outputs a voltage that makes the single-arm bridge output voltage zero according to the received control signal.
[0063] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.
[0064] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown in this document, but should conform to the widest scope consistent with the principles and novel features disclosed in this document.
