Circuit and method for automatic zero calibration for sensor

Abstract

The invention discloses a circuit and method for automatic zero calibration for a sensor. The circuit comprises a detector, a compensator, two resistors, a voltage output circuit and a controller, wherein the detector, the compensator, the first resistor and the second resistor are electrically connected to form a single-armed bridge; one end of the controller is connected with the public electrical connecting end of the detector and the compensator, and the other end of the controller is connected with the public electrical connecting end of the first resistor and the second resistor; the controller is used for detecting the output voltage of the single-armed bridge and judging whether the output voltage is normal, and if not, the controller generates a control signal according to the output voltage and sends the control signal; one end of the voltage output circuit is electrically connected with the controller, and the other end of the voltage output circuit is connected with the public electrical connecting end of the first resistor and the second resistor; the voltage output circuit is used for receiving the control signal sent by the controller and outputting voltage for regulating the output voltage of the single-armed bridge to be zero according to the control signal. The circuit and the method can calibrate the zero of the sensor so as to realize that the sensor detects accurate gas concentration.

Description

technical field [0001] The invention relates to the technical field of gas sensors, in particular to a circuit and method for automatic zero point calibration of sensors. Background technique [0002] At present, gas sensors are mainly used for the detection of gas concentration. Existing gas concentration detection circuits such as figure 1 As shown, it is mainly composed of a sensor composed of a detector 11 also called a black element, a compensator 12 also called a white element, two external balancing resistors R1 and R2, and an adjustable resistor R3. [0003] In the process of detecting the gas concentration by the gas sensor, due to the imbalance of black and white components, changes in the temperature, humidity and pressure of the gas sensor working environment, the long service time of the gas sensor and the consumption of the catalyst in the gas sensor, etc., it is easy to cause gas The zero point of the sensor drifts. When the zero point of the sensor drifts i...

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Problems solved by technology

[0003] In the process of detecting the gas concentration by the gas sensor, due to the imbalance of black and white components, changes in the temperature, humidity and pressure of the gas sensor working environment, the long service time of the gas sensor and the consumption of the catalyst in the gas sensor, etc., it is easy to cause gas The zero point of the sensor drifts. When the zero point of the sensor drifts in the same direction as the gas reaction, it will cause the output voltage value when there is no gas to be measured around, causing false alarms; when the zero point of the sensor drifts in the opposite direction to the gas reaction, It will cause the output voltage value to be negative, and the output value cannot reflect the gas concentration when there is a gas to be measured around, which will cause the sensor function to fail and cause danger; therefore, in order to avoid false alarms or function failure caused by zero drift of the gas sensor during operation, it is necessary to pass Adjust the adjustable resistor R3 to calibrate the zero point of the sensor

[0004] However, the existing adjustable resistor R3 calibrates the zero point of the sensor, mainly by observing the voltage value at the output terminal to artificially adjust the adjustable resistor R3, which has a low degree of intelligence and cannot calibrate the zero point of the sensor in real time.

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