Carbon monoxide concentration detection circuit

Abstract

The utility model relates to a carbon monoxide concentration detection circuit which comprises a carbon monoxide sensor circuit, a voltage following circuit, a comparison circuit, a signal amplification circuit and a main control circuit, a voltage-regulator tube is connected between the voltage following circuit and the signal amplification circuit, and the carbon monoxide sensor circuit is used for detecting carbon monoxide gas. A voltage value is output to the comparison circuit and the voltage following circuit according to the detected carbon monoxide gas concentration, the voltage following circuit outputs the received voltage value to a first AD detection port of the main control circuit, and the comparison circuit outputs a level signal to the main control circuit according to the received voltage value; when the level signal received by the main control circuit is a high level, the main control circuit collects the voltage value of the first AD detection port; and when the level signal received by the main control circuit is a low level, the main control circuit collects the voltage value of the second AD detection port. According to the utility model, the detection sensitivity of carbon monoxide at high concentration is enhanced, and the resolution ratio and the accuracy of carbon monoxide at high concentration are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of carbon monoxide detection, and particularly relates to a carbon monoxide concentration detection circuit. Background Art

[0002] In modern society, carbon monoxide, as a colorless, odorless and toxic gas, poses a serious threat to people's life safety. Therefore, it is of great significance to detect carbon monoxide quickly and accurately.

[0003] Currently, when the environmental carbon monoxide concentration is between 200 ppm and 500 ppm, the sensitivity of the carbon monoxide detection sensor drops significantly, resulting in lower data resolution and poorer accuracy when detecting at higher concentrations, which affects the accurate judgment of the actual carbon monoxide concentration in the environment.

[0004] Therefore, there is an urgent need to provide a carbon monoxide concentration detection circuit to solve the above problems. Summary of the Utility Model

[0005] The purpose of the utility model is to overcome the deficiencies and defects of the prior art, and provide a carbon monoxide concentration detection circuit to enhance the detection sensitivity of carbon monoxide at higher concentrations and improve the resolution and accuracy of carbon monoxide at higher concentrations.

[0006] The purpose of the utility model is achieved by the following technical solutions:

[0007] A carbon monoxide concentration detection circuit includes a carbon monoxide sensor circuit, a voltage follower circuit, a comparison circuit, a signal amplification circuit and a main control circuit. A voltage stabilizing diode is connected between the voltage follower circuit and the signal amplification circuit. The carbon monoxide sensor circuit is used to detect carbon monoxide gas and output a voltage value to the comparison circuit and the voltage follower circuit according to the detected carbon monoxide gas concentration. The voltage follower circuit outputs the received voltage value to the first AD detection port of the main control circuit. The comparison circuit outputs a level signal to the main control circuit according to the received voltage value. When the level signal received by the main control circuit is high, the main control circuit collects the voltage value of the first AD detection port. When the level signal received by the main control circuit is low, the voltage follower circuit outputs the voltage value to the voltage stabilizing diode for attenuation, and the attenuated voltage value is given to the signal amplification circuit. The signal amplification circuit amplifies the received voltage value and then outputs the amplified voltage value to the second AD detection port of the main control circuit. The main control circuit collects the voltage value of the second AD detection port.

[0008] As a preferred technical solution of the present utility model, the detection circuit is further provided with a reference voltage output circuit, the reference voltage output circuit is connected to the comparison circuit, the reference voltage output circuit outputs a reference voltage value to the comparison circuit as a comparison reference voltage, the reference voltage output circuit includes a resistor R37 and a resistor R38, and the resistor R37 and the resistor R38 are connected in series.

[0009] As a preferred technical solution of the present utility model, the reference voltage output circuit further includes an operational amplifier, the reference voltage value is input through the non-inverting input terminal of the operational amplifier, and then given to the comparison circuit through the output terminal of the operational amplifier, and the operational amplifier is used to stabilize the reference voltage value.

[0010] As a preferred technical solution of the present utility model, the detection circuit further includes a power supply switching and protection circuit, the power supply switching and protection circuit includes a diode D3 and a diode D7, and the diode D3 and the diode D7 are connected in parallel.

[0011] As a preferred technical solution of the present utility model, the carbon monoxide sensor circuit uses a semiconductor carbon monoxide sensor.

[0012] Compared with the prior art, the present utility model has the following beneficial effects:

[0013] By adding a voltage stabilizing diode and a signal amplification circuit to the present utility model, when the detected carbon monoxide concentration is relatively high, the voltage value corresponding to the high concentration is attenuated and then amplified to improve its detection sensitivity and detection resolution. The present utility model performs segmented compensation on the sensitivity change curve through a hardware circuit to enhance its detection sensitivity at relatively high concentrations, effectively reducing the production cost while ensuring the detection accuracy and improving the market competitiveness of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a flow block diagram of the present utility model.

[0015] Figure 2 is a schematic diagram of the detection circuit of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The following further describes the present utility model in detail in conjunction with the embodiments and the drawings, but the embodiments of the present utility model are not limited thereto.

[0017] The specific implementation process of the present utility model is as follows:

[0018] Such as Figures 1 to 2As shown in the figure, a carbon monoxide concentration detection circuit includes a carbon monoxide sensor circuit U1, a comparison circuit U2B, a voltage follower circuit U2A, a signal amplification circuit U2C, and a main control circuit. A zener diode is connected between the voltage follower circuit U2A and the signal amplification circuit U2C. The carbon monoxide sensor circuit U1 is used to detect carbon monoxide gas and output a voltage value to the comparison circuit U2B and the voltage follower circuit U2A according to the detected carbon monoxide gas concentration. The voltage follower circuit U2A outputs the received voltage value to the first AD detection port of the main control circuit. The comparison circuit U2B outputs a level signal to the main control circuit according to the received voltage value. When the level signal received by the main control circuit is high, the main control circuit samples the voltage value of the first AD detection port. When the level signal received by the main control circuit is low, the voltage follower circuit U2A outputs the voltage value to the zener diode for attenuation, and the attenuated voltage value is given to the signal amplification circuit U2C. The signal amplification circuit U2C amplifies the received voltage value and then outputs the amplified voltage value to the second AD detection port of the main control circuit. The main control circuit samples the voltage value of the second AD detection port.

[0019] Specifically, pin 1 of the carbon monoxide sensor circuit U1 is connected to the inverting output terminal of the comparison circuit U2B, and pin 3 of the carbon monoxide sensor is connected to the non-inverting output terminal of the voltage follower circuit U2A. After the carbon monoxide sensor circuit U1 detects a certain concentration of carbon monoxide gas, it outputs corresponding voltage values to the comparison circuit U2B and the voltage follower circuit U2A through pin 1 and pin 3. The higher the carbon monoxide concentration, the higher the output voltage value. By performing multi-point sampling and individual calibration on the carbon monoxide sensor, the detection accuracy is ensured. Specifically: collect a set of data every 100 ppm, record its average voltage value and store it, calculate the slope between every two adjacent sets of data, obtain the voltage value corresponding to 1 ppm of carbon monoxide concentration value, form a data table with a one-to-one correspondence between carbon monoxide concentration and voltage value, store it as the standard database of this machine, and then compare the real-time detected data with the standard database to obtain the actual carbon monoxide concentration value. Each machine obtains a data table with a one-to-one correspondence between its own concentration value and voltage value through the calibration method to ensure the detection accuracy of each device.

[0020] When the detected carbon monoxide concentration is low, the voltage value output by the carbon monoxide sensor circuit U1 is lower than the reference voltage value. The comparison circuit U2B outputs a high level. When the main control circuit detects that the output signal of the comparison circuit U2B is high level, it collects the voltage value output by the voltage follower circuit U2A through the first AD detection port, and records and stores the carbon monoxide concentration and the corresponding voltage value at this time. When the detected carbon monoxide concentration is high, the voltage value output by the carbon monoxide sensor circuit U1 is higher than the reference voltage value. The voltage value output by the carbon monoxide sensor circuit U1 passes through the voltage follower circuit U2A and then is attenuated by a voltage stabilizing diode to obtain a voltage value corresponding to the voltage value output by the carbon monoxide sensor circuit U1. The attenuated voltage value is amplified by the signal amplification circuit U2C to obtain a larger voltage value, increasing the sensitivity when the carbon monoxide concentration is high. At the same time, the comparison circuit U2B outputs a low level. The main control circuit receives a low-level signal, and the main control circuit then collects the voltage value output by the signal amplification circuit U2C through the second AD detection port, and records and stores the carbon monoxide concentration and the voltage value at this time.

[0021] In the embodiment of the present invention, the detection circuit further includes a reference voltage output circuit U2D. The reference voltage output circuit U2D is connected to the comparison circuit U2B. The reference voltage output circuit U2D outputs a reference voltage value to the comparison circuit U2B as a comparison reference voltage. The reference voltage output circuit U2D includes a resistor R37 and a resistor R38, and the resistor R37 and the resistor R38 are connected in series. Specifically, the voltage reference value is obtained by voltage division through the resistor R37 and the resistor R38. After receiving the voltage signal, the comparison circuit U2B compares the voltage signal with the voltage reference value. When the voltage signal is lower than the voltage reference value, the comparison circuit U2B outputs a high level. When the voltage signal is higher than the voltage reference value, the comparison circuit U2B outputs a low level.

[0022] In the embodiment of the present invention, the reference voltage output circuit U2D further includes an operational amplifier. The reference voltage value is input through the non-inverting input terminal of the operational amplifier and then given to the comparison circuit U2B through the output terminal of the operational amplifier. The operational amplifier is used to stabilize the reference voltage value.

[0023] In the embodiment of the present invention, the detection circuit further includes a power supply switching and protection circuit. The power supply switching and protection circuit includes a diode D3 and a diode D7, and the diode D3 and the diode D7 are connected in parallel. When detecting carbon monoxide, the carbon monoxide sensor operates at a low temperature of 1.5V. When cleaning the gas adsorbed at low temperature, the carbon monoxide sensor operates at a high temperature of 5V. At the same time, the diode D3 and the diode D7 protect the power supply to prevent power supply crosstalk and reverse connection.

[0024] In the embodiment of the present utility model, the carbon monoxide sensor circuit U1 uses a semiconductor carbon monoxide sensor, which has low cost, long service life and high sensitivity. While ensuring the detection accuracy, it effectively reduces the production cost and improves the market competitiveness of the product.

[0025] The above embodiments only express the implementation modes of the present utility model, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model. Therefore, the protection scope of the patent of the present utility model shall be subject to the appended claims.

Claims

1. A carbon monoxide concentration detection circuit, characterized in that, It includes a carbon monoxide sensor circuit, a voltage follower circuit, a comparison circuit, a signal amplification circuit and a main control circuit. A voltage stabilizing diode is connected between the voltage follower circuit and the signal amplification circuit. The carbon monoxide sensor circuit is used to detect carbon monoxide gas and output a voltage value to the comparison circuit and the voltage follower circuit according to the detected concentration of carbon monoxide gas. The voltage follower circuit outputs the received voltage value to the first AD detection port of the main control circuit. The comparison circuit outputs a level signal to the main control circuit according to the received voltage value. When the level signal received by the main control circuit is high, the main control circuit collects the voltage value of the first AD detection port; When the level signal received by the main control circuit is low, the voltage follower circuit outputs the voltage value to the voltage stabilizing diode for attenuation. The attenuated voltage value is given to the signal amplification circuit. The signal amplification circuit amplifies the received voltage value and then outputs the amplified voltage value to the second AD detection port of the main control circuit. The main control circuit collects the voltage value of the second AD detection port.

2. The carbon monoxide concentration detection circuit according to claim 1, wherein The detection circuit is also provided with a reference voltage output circuit. The reference voltage output circuit is connected to the comparison circuit. The reference voltage output circuit outputs a reference voltage value to the comparison circuit as a comparison reference voltage. The reference voltage output circuit includes a resistor R37 and a resistor R38. The resistor R37 and the resistor R38 are connected in series.

3. The carbon monoxide concentration detection circuit according to claim 2, characterized in that, The reference voltage output circuit also includes an operational amplifier. The reference voltage value is input through the non-inverting input terminal of the operational amplifier and then given to the comparison circuit through the output terminal of the operational amplifier. The operational amplifier is used to stabilize the reference voltage value.

4. The carbon monoxide concentration detection circuit according to claim 1, wherein, The detection circuit also includes a power supply switching and protection circuit. The power supply switching and protection circuit includes a diode D3 and a diode D7. The diode D3 and the diode D7 are connected in parallel.

5. The carbon monoxide concentration detection circuit according to claim 1, characterized in that The carbon monoxide sensor circuit uses a semiconductor carbon monoxide sensor.

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