Oxygen concentration detection circuit and method

Abstract

According to the oxygen concentration detection circuit and method, an optical oxygen sensor is adopted for oxygen concentration detection, a peripheral complex circuit is not needed, the concentration detection range is large, the precision is high, alarm signals correspond to different oxygen-containing states, a worker can know the approximate oxygen-containing condition at the first time according to an alarm, and the detection accuracy is high. Pretreatment can be carried out, further deterioration of the state is prevented, and oxygen deficit and explosion risks are reduced.

Description

Technical Field

[0001] The invention relates to an oxygen concentration detection circuit and method, belonging to the technical field of circuit design. Background Art

[0002] Confined spaces such as mines, oxygen plants, shipbuilding, chemical industry and tunnels all need to detect oxygen concentration to avoid the risk of hypoxia and explosion. The current oxygen concentration detection circuit requires complex peripheral circuits, and the concentration detection range is small (about 10% to 25%), and the alarm method is single. After the alarm, further verification is required before oxygen can be supplemented, and pre-treatment cannot be done in the first place. Summary of the invention

[0003] The present invention provides an oxygen concentration detection circuit and method, which solve the problems disclosed in the background technology.

[0004] According to one aspect of the present disclosure, there is provided an oxygen concentration detection circuit, including an optical oxygen sensor, an alarm circuit, a single chip microcomputer and a power supply circuit; The optical oxygen sensor is used to detect the oxygen concentration and transmit the signal representing the oxygen concentration to the microcontroller; The single chip microcomputer is used to compare the signal representing the oxygen concentration with the reference signal, and send out different alarm signals according to the comparison result; wherein different alarm signals correspond to different oxygen content states; The alarm circuit is used to issue a corresponding alarm after receiving an alarm signal from the single chip microcomputer; The power supply circuit is used to supply power to each electrical component of the oxygen concentration detection circuit.

[0005] In some embodiments of the present disclosure, the power supply circuit includes a battery, a charging circuit and a conversion circuit; the charging circuit charges the battery, and the conversion circuit converts the voltage output by the battery into a first voltage and a second voltage, wherein the first voltage powers the optical oxygen sensor, and the second voltage powers the alarm circuit and the microcontroller.

[0006] In some embodiments of the present disclosure, the charging circuit includes a fifth resistor, a sixth resistor, a seventh resistor, a first capacitor, a second capacitor, a third capacitor, a third light-emitting diode, a fourth light-emitting diode, a voltage-stabilizing diode and a charging chip; the PROG pin of the charging chip is grounded through the fifth resistor, the VCC pin of the charging chip is grounded through the first capacitor, the second capacitor is connected in parallel with the first capacitor, the BAT pin of the charging chip is connected to the charging end of the battery, one end of the third capacitor is grounded, and the other end of the third capacitor is connected to the BAT pin of the charging chip, the CHRG pin of the charging chip is connected to the cathode of the third light-emitting diode through the sixth resistor, the STDBY pin of the charging chip is connected to the cathode of the fourth light-emitting diode through the seventh resistor, the anode of the third light-emitting diode, the anode of the fourth light-emitting diode, the VCC pin of the charging chip and the cathode of the voltage-stabilizing diode are all externally connected to a power supply, and the anode of the voltage-stabilizing diode is grounded.

[0007] In some embodiments of the present disclosure, the conversion circuit includes a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an inductor, a power supply chip, a second rectifier diode and a voltage regulator; the LX pin of the power supply chip is respectively connected to one end of the inductor and the positive electrode of the second rectifier diode, the other end of the inductor is connected to the battery output end, the negative electrode of the second rectifier diode is respectively connected to the OUT pin of the power supply chip and the positive electrode of the fifth capacitor, the OUT pin of the power supply chip serves as the first voltage output end, the negative electrode of the fifth capacitor is respectively connected to the GND pin of the power supply chip, the ground and one end of the fourth capacitor, the other end of the fourth capacitor is connected to the battery output end, the CE pin of the power supply chip is connected to the CE pin of the voltage regulator, the VIN pin of the voltage regulator inputs the first voltage, one end of the sixth capacitor is connected to the VIN pin of the voltage regulator, the other end of the sixth capacitor is respectively connected to the ground and the VSS pin of the voltage regulator, the VOUT pin of the voltage regulator serves as the second voltage output end, one end of the seventh capacitor is connected to the VOUT pin of the voltage regulator, and the other end of the seventh capacitor is grounded.

[0008] In some embodiments of the present disclosure, the alarm circuit includes an indicator light alarm circuit; the indicator light alarm circuit includes a first light-emitting diode, a second light-emitting diode, a first resistor and a second resistor; one end of the first resistor and one end of the second resistor are connected to a single-chip microcomputer, the other end of the first resistor is connected to the cathode of the first light-emitting diode, the other end of the second resistor is connected to the cathode of the second light-emitting diode, and the positive electrodes of the first light-emitting diode and the second light-emitting diode are connected to the second voltage output end of the power supply circuit.

[0009] In some embodiments of the present disclosure, the alarm circuit includes a vibration alarm circuit; the vibration alarm circuit includes a third resistor, a fourth resistor, a first rectifier diode, a transistor and a vibration motor; one end of the third resistor is connected to one end of the fourth resistor, and the connecting end is connected to the single-chip microcomputer, the other end of the third resistor is grounded, the other end of the fourth resistor is connected to the base of the transistor, the emitter of the transistor is grounded, the collector of the transistor is respectively connected to the negative input end of the vibration motor and the positive pole of the first rectifier diode, and the negative pole of the first rectifier diode and the positive input end of the vibration motor are connected to the second voltage output end of the power supply circuit.

[0010] According to another aspect of the present disclosure, a method for detecting oxygen concentration is provided, wherein an oxygen concentration detection circuit is used to detect oxygen concentration; the method comprises: receiving a signal representing oxygen concentration output by an optical oxygen sensor; The signal representing the oxygen concentration is compared with the reference signal, and different alarm signals are sent to the alarm circuit according to the comparison result, so as to control the alarm circuit to send out corresponding alarms.

[0011] In some embodiments of the present disclosure, if the signal representing the oxygen concentration is less than the lower limit of the reference range, and the difference between the lower limit and the signal representing the oxygen concentration is not greater than the first threshold, a first hypoxia alarm signal is issued; If the signal representing the oxygen concentration is less than the lower limit of the reference range, and the difference between the lower limit and the signal representing the oxygen concentration is greater than the first threshold, a second hypoxia alarm signal is issued; If the signal representing the oxygen concentration is greater than the upper limit of the reference range, and the difference between the signal representing the oxygen concentration and the upper limit is not greater than the second threshold, a first overoxygen alarm signal is issued; If the signal representing the oxygen concentration is greater than the upper limit of the reference range, and the difference between the signal representing the oxygen concentration and the upper limit is greater than a second threshold, a second overoxygen alarm signal is issued.

[0012] The beneficial effects achieved by the present invention are as follows: the present invention adopts an optical oxygen sensor to detect oxygen concentration, does not require a peripheral complex circuit, has a large concentration detection range and high precision, and the alarm signal of the present invention corresponds to different oxygen conditions. The staff can know the approximate oxygen condition in the first time according to the alarm, and can perform pretreatment to prevent the condition from further deteriorating, thereby reducing the risk of hypoxia and explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the structural block diagram of the oxygen concentration detection circuit; Figure 2 This is the charging circuit diagram; Figure 3 For conversion circuit diagram; Figure 4 is the circuit diagram of the optical oxygen sensor; Figure 5 This is the indicator light alarm circuit diagram; Figure 6 This is the vibration alarm circuit diagram; Figure 7 It is a schematic diagram of a single chip microcomputer; Figure 8 Flow chart of the detection method. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. It is obvious that the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0015] Unless otherwise specified, the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0016] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0017] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0018] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0019] It should be noted that similar symbols and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

[0020] In order to solve the problem that the existing oxygen concentration detection circuit requires complex peripheral circuits and has a small concentration detection range, the present disclosure proposes an oxygen concentration detection circuit and method.

[0021] Figure 1 This is a schematic diagram of an embodiment of the oxygen concentration detection circuit disclosed in the present invention, including an optical oxygen sensor, an alarm circuit, a single-chip microcomputer and a power supply circuit; wherein the optical oxygen sensor and the alarm circuit are both connected to the single-chip microcomputer, and the power supply circuit supplies power to all electrical components.

[0022] It should be noted that the power supply circuit mainly includes a battery, a charging circuit and a conversion circuit; wherein the battery can be a common lithium battery, the charging circuit is connected to an external power supply to charge the battery, and the conversion circuit converts the voltage output by the battery into a first voltage and a second voltage, wherein the first voltage powers the optical oxygen sensor, and the second voltage powers the alarm circuit and the single-chip microcomputer. The first voltage can be 5V, and the second voltage can be 3.3V.

[0023] See Figure 2 The charging circuit includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first capacitor C1, a second capacitor C2, a third capacitor C3, a third light emitting diode LED3, a fourth light emitting diode LED4, a voltage stabilizing diode D and a charging chip U1. The PROG pin of the charging chip U1 is grounded through the fifth resistor R5, the VCC pin of the charging chip U1 is grounded through the first capacitor C1, the second capacitor C2 is connected in parallel with the first capacitor C1, the BAT pin of the charging chip U1 is connected to the battery charging end (i.e., the positive electrode of the battery), one end of the third capacitor C3 is grounded, and the other end of the third capacitor C3 is connected to the BAT pin of the charging chip U1, the CHRG pin of the charging chip U1 is connected to the cathode of the third light emitting diode LED3 through the sixth resistor R6, the STDBY pin of the charging chip U1 is connected to the cathode of the fourth light emitting diode LED4 through the seventh resistor R7, the anode of the third light emitting diode LED3, the anode of the fourth light emitting diode LED4, the VCC pin of the charging chip U1 and the cathode of the voltage stabilizing diode D are all externally connected to a power supply, and the anode of the voltage stabilizing diode D is grounded.

[0024] The resistance of the fifth resistor R5 can be 1.2K, the capacitance value of the first capacitor C1 can be 22uF, the capacitance value of the second capacitor C2 can be 0.1uF, the model of the charging chip U1 is BL8573CS8TR, the capacitance value of the third capacitor C3 can be 10uF, the resistance of the sixth resistor R6 and the seventh resistor R7 can be 510R, the model of the Zener diode D can be BZT52C5V6S, and the model of the third light-emitting diode LED3 and the fourth light-emitting diode LED4 can be TJ-S2012SW8TCGLC2R2G-A5.

[0025] The input voltage is stabilized to about 3.6V by the voltage stabilizing diode D, and then filtered by the first capacitor C1 and the second capacitor C2 to power the charging chip U1. The PROG pin of the charging chip U1 is connected to the fifth resistor R5 for current limiting, so that constant current charging can be achieved. The BAT pin of the charging chip U1 is connected to the positive electrode of the lithium battery, and the lithium battery is charged after filtering by the third capacitor C3. The third light-emitting diode LED3 and the fourth light-emitting diode LED4 realize the indicator light display of the charging status, which is red for charging and green for full.

[0026] See Figure 3 The conversion circuit includes a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an inductor L1, a power chip U2, a second rectifier diode D2 and a voltage regulator LD01. The LX pin of the power chip U2 is respectively connected to one end of the inductor L1 and the positive electrode of the second rectifier diode D2, the other end of the inductor L1 is connected to the battery output end, the negative electrode of the second rectifier diode D2 is respectively connected to the OUT pin of the power chip U2 and the positive electrode of the fifth capacitor C5, the OUT pin of the power chip U2 serves as the first voltage output end, the negative electrode of the fifth capacitor C5 is respectively connected to the GND pin of the power chip U2, the ground and one end of the fourth capacitor C4, the other end of the fourth capacitor C4 is connected to the battery output end, the CE pin of the power chip U2 is connected to the CE pin of the voltage regulator LD01, the VIN pin of the voltage regulator LD01 inputs the first voltage, one end of the sixth capacitor C6 is connected to the VIN pin of the voltage regulator LD01, the other end of the sixth capacitor C6 is respectively connected to the ground and the VSS pin of the voltage regulator LD01, the VOUT pin of the voltage regulator LD01 serves as the second voltage output end, one end of the seventh capacitor C7 is connected to the VOUT pin of the voltage regulator LD01, and the other end of the seventh capacitor C7 is grounded.

[0027] The inductance value of the inductor L1 can be 27uH, the model of the second rectifier diode D2 can be 1N5819WS, the model of the power chip U2 can be BL8531CB5TR50, the capacitance value of the fifth capacitor C5 can be 100uF, the capacitance value of the fourth capacitor C4 can be 47 uF, the model of the voltage regulator LD01 can be ME6211C33M5G-N, and the capacitance values ​​of the sixth capacitor C6 and the seventh capacitor C7 can be 1uF.

[0028] The input voltage is filtered by the fourth capacitor C4 and acts on the power chip U2. The CE enable terminal is pulled up, and the input voltage charges the fifth capacitor C5 through the inductor L1. At the same time, the second rectifier diode D21 can prevent the fifth capacitor C5 from discharging to the ground. The current in the inductor L1 increases linearly. When the internal switch of the power chip U2 is disconnected, the current of the inductor L1 cannot change instantaneously, and the output fifth capacitor C5 can be charged to achieve a boost to 5V output. The sixth capacitor C6 is the input capacitor, and the seventh capacitor C7 is the output filter capacitor, which is used to suppress self-excited oscillation. The sixth capacitor C6 and the seventh capacitor C7 can prevent the voltage regulator LD01 from outputting an oscillating waveform. The 5V DC voltage is input to the input end of the voltage regulator LD01, and is filtered by the sixth capacitor C6 and the seventh capacitor C7 to prevent the power from being reversed and outputting a 3.3V voltage.

[0029] In the embodiment, see Figure 4The optical oxygen sensor model may be SST_LOX02. The sensor is used to detect the oxygen concentration and transmit the detected oxygen concentration to the microcontroller. It is directly powered by a 5V voltage and directly outputs a TTL level to the RX pin of the microcontroller.

[0030] It should be noted that the optical oxygen sensor can be based on luminescent optical technology rather than traditional electrochemical methods. There is no need to install an airtight base to ensure airtightness, so the surrounding area and directly below can be in the sample detection environment, and the internal sensors for temperature and atmospheric compensation are integrated internally, so there is no need for complex peripheral circuits. In addition, the optical oxygen sensor does not need lead-containing liquid electrolytes, so there is no problem of volatile gases affecting sensitivity, which can make the detection range more accurate.

[0031] In the embodiment, the alarm circuit is used to issue a corresponding alarm after receiving an alarm signal issued by the single chip microcomputer.

[0032] It should be noted that the alarm circuit may include an indicator light alarm circuit and / or a vibration alarm circuit; wherein the indicator light alarm circuit alarms through light, and the vibration alarm circuit alarms through vibration.

[0033] See Figure 5 The indicator light alarm circuit includes a first light emitting diode LED1, a second light emitting diode LED2, a first resistor R1 and a second resistor R2. One end of the first resistor R1 and one end of the second resistor R2 are connected to the single chip computer, which are the PA6 pin and the PA7 pin respectively, the other end of the first resistor R1 is connected to the cathode of the first light emitting diode LED1, the other end of the second resistor R2 is connected to the cathode of the second light emitting diode LED2, and the anodes of the first light emitting diode LED1 and the second light emitting diode LED2 are connected to the second voltage output end of the power supply circuit, that is, the 3.3V power supply.

[0034] The resistance value of the first resistor R1 and the second resistor R2 can be 330R, and the model of the first light emitting diode LED1 and the second light emitting diode LED2 can be TJ-S2012SW8TCGLC2R2G-A5. The first light emitting diode LED1 and the second light emitting diode LED2 can display the operating status of the product, which is green when normal and red when alarming.

[0035] See Figure 6The vibration alarm circuit includes a third resistor R3, a fourth resistor R4, a first rectifier diode D1, a transistor Q1 and a vibration motor M1; one end of the third resistor R3 is connected to one end of the fourth resistor R4, and the connection end is connected to the single-chip microcomputer, specifically the PA4 pin, the other end of the third resistor R3 is grounded, the other end of the fourth resistor R4 is connected to the base of the transistor Q1, the emitter of the transistor Q1 is grounded, the collector of the transistor Q1 is respectively connected to the negative input end of the vibration motor M1 and the positive electrode of the first rectifier diode D1, and the negative electrode of the first rectifier diode D1 and the positive input end of the vibration motor M1 are connected to the second voltage output end of the power supply circuit.

[0036] The resistance value of the third resistor R3 can be 4.7R, the resistance value of the fourth resistor R4 can be 2K, the transistor Q1 is an NPN transistor, the model can be MMBT5551, the model of the first rectifier diode D1 can be 1N5819WS, and the model of the vibration motor M1 can be Z30C1T8219731. After the vibration alarm circuit is powered on, the motor is pulled down to the ground by the third resistor R3, and the transistor Q1 is cut off and does not conduct. When the oxygen index is abnormal, the single chip microcomputer outputs a high level to the motor, so that the transistor Q1 is turned on, and the negative pole of the vibration motor M1 is pulled to the ground to form a conduction loop, and vibration begins.

[0037] In the embodiment, the single chip microcomputer is used to compare the signal representing the oxygen concentration with the reference signal, and send out different alarm signals according to the comparison result; wherein different alarm signals correspond to different oxygen conditions.

[0038] It should be noted that the signal representing the oxygen concentration and the reference signal are generally voltage, but they can also be other signals such as current. Since both hypoxia and overoxygen need to be dealt with immediately, once delayed, sometimes irreversible consequences may occur. Therefore, different forms of alarms are required according to different oxygen conditions, so that the staff can know the approximate oxygen conditions from the alarm, so that pre-treatment can be carried out to prevent further deterioration of the condition and reduce the risk of hypoxia and explosion.

[0039] Taking the above two alarm circuits as an example, combined alarms can be performed under different oxygen conditions. For example, in case of slight hypoxia, the alarm mode may be that the indicator light flashes, in case of non-slight hypoxia, the alarm mode may be that the indicator light is always on and vibrates intermittently, in case of slight overoxygenation, the alarm mode may be that the indicator light flashes and vibrates intermittently, in case of non-slight overoxygenation, the alarm mode may be that the indicator light is always on and vibrates continuously. Since the alarm signal corresponds to different oxygen conditions, the staff can know the approximate oxygen condition in the first time according to the alarm, and can perform pretreatment to prevent the condition from further deteriorating and reduce the risk of hypoxia and explosion.

[0040] See Figure 7The model of the microcontroller may be GD32F103CBT6. In addition to the above circuit, the microcontroller is also connected to some peripheral components, such as connecting the eighth capacitor C8 of 0.1uF between the microcontroller VBAT pin and the ground, connecting the ninth capacitor C9 of 0.1uF between the microcontroller VDD_3 pin and the ground, connecting the tenth capacitor C10 of 0.1uF between the microcontroller VSSA pin and the VDDA pin, connecting the eighth resistor R8 of 1K between the microcontroller B00T0 pin and the ground, connecting the eleventh capacitor C11 of 0.1uF between the microcontroller VDD_1 pin and the ground, and connecting the twelfth capacitor C12 of 0.1uF between the microcontroller VDD_2 pin and the VSS_2 pin. The microcontroller is the main control unit of the entire circuit, which realizes the control of the entire circuit.

[0041] Figure 8 This is a schematic diagram of an embodiment of the oxygen concentration detection method disclosed in the present invention. The method is executed by a single chip microcomputer, and the steps include: In the embodiment, step 1 is receiving a signal representing oxygen concentration output by an optical oxygen sensor.

[0042] In the embodiment, in step 2, the signal representing the oxygen concentration is compared with the reference range, and different alarm signals are sent to the alarm circuit according to the comparison result, so as to control the alarm circuit to send out a corresponding alarm.

[0043] It should be noted that the following four alarm modes can be used: if the signal representing the oxygen concentration is less than the lower limit of the reference range, and the difference between the lower limit and the signal representing the oxygen concentration is not greater than the first threshold, a first hypoxia alarm signal is issued; if the signal representing the oxygen concentration is less than the lower limit of the reference range, and the difference between the lower limit and the signal representing the oxygen concentration is greater than the first threshold, a second hypoxia alarm signal is issued; if the signal representing the oxygen concentration is greater than the upper limit of the reference range, and the difference between the signal representing the oxygen concentration and the upper limit is not greater than the second threshold, a first overoxygen alarm signal is issued; if the signal representing the oxygen concentration is greater than the upper limit of the reference range, and the difference between the signal representing the oxygen concentration and the upper limit is greater than the second threshold, a second overoxygen alarm signal is issued; wherein the reference range corresponds to an oxygen concentration of 19.5% to 23.5%, the first threshold corresponds to an oxygen concentration of 1.5%, and the second threshold corresponds to an oxygen concentration of 2%.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An oxygen concentration detection circuit, characterized in that: It includes an optical oxygen sensor, an alarm circuit, a single chip microcomputer and a power supply circuit; The optical oxygen sensor is used to detect the oxygen concentration and transmit the signal representing the oxygen concentration to the microcontroller; The single chip microcomputer is used to compare the signal representing the oxygen concentration with the reference range, and send out different alarm signals according to the comparison result; wherein different alarm signals correspond to different oxygen content states; The alarm circuit is used to issue a corresponding alarm after receiving an alarm signal from the single chip microcomputer; The power supply circuit is used to supply power to each electrical component of the oxygen concentration detection circuit.

2. The oxygen concentration detection circuit according to claim 1, characterized in that: The power supply circuit includes a battery, a charging circuit and a conversion circuit; the charging circuit charges the battery, and the conversion circuit converts the voltage output by the battery into a first voltage and a second voltage, wherein the first voltage powers the optical oxygen sensor, and the second voltage powers the alarm circuit and the single-chip microcomputer.

3. The oxygen concentration detection circuit according to claim 2, characterized in that: The charging circuit includes a fifth resistor, a sixth resistor, a seventh resistor, a first capacitor, a second capacitor, a third capacitor, a third light-emitting diode, a fourth light-emitting diode, a voltage-stabilizing diode and a charging chip; a PROG pin of the charging chip is grounded through the fifth resistor, a VCC pin of the charging chip is grounded through the first capacitor, the second capacitor is connected in parallel with the first capacitor, a BAT pin of the charging chip is connected to the charging end of the battery, one end of the third capacitor is grounded, the other end of the third capacitor is connected to the BAT pin of the charging chip, a CHRG pin of the charging chip is connected to the cathode of the third light-emitting diode through the sixth resistor, a STDBY pin of the charging chip is connected to the cathode of the fourth light-emitting diode through the seventh resistor, the anode of the third light-emitting diode, the anode of the fourth light-emitting diode, the VCC pin of the charging chip and the cathode of the voltage-stabilizing diode are all externally connected to a power supply, and the anode of the voltage-stabilizing diode is grounded.

4. The oxygen concentration detection circuit according to claim 2, characterized in that: The conversion circuit includes a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an inductor, a power chip, a second rectifier diode and a voltage regulator; the LX pin of the power chip is respectively connected to one end of the inductor and the positive electrode of the second rectifier diode, the other end of the inductor is connected to the battery output end, the negative electrode of the second rectifier diode is respectively connected to the OUT pin of the power chip and the positive electrode of the fifth capacitor, the OUT pin of the power chip serves as the first voltage output end, the negative electrode of the fifth capacitor is respectively connected to the GND pin of the power chip, the ground and one end of the fourth capacitor, the other end of the fourth capacitor is connected to the battery output end, the CE pin of the power chip is connected to the CE pin of the voltage regulator, the VIN pin of the voltage regulator inputs the first voltage, one end of the sixth capacitor is connected to the VIN pin of the voltage regulator, the other end of the sixth capacitor is respectively connected to the ground and the VSS pin of the voltage regulator, the VOUT pin of the voltage regulator serves as the second voltage output end, one end of the seventh capacitor is connected to the VOUT pin of the voltage regulator, and the other end of the seventh capacitor is grounded.

5. The oxygen concentration detection circuit according to claim 1, characterized in that: The alarm circuit includes an indicator light alarm circuit; the indicator light alarm circuit includes a first light-emitting diode, a second light-emitting diode, a first resistor and a second resistor; one end of the first resistor and one end of the second resistor are connected to the single-chip microcomputer, the other end of the first resistor is connected to the cathode of the first light-emitting diode, the other end of the second resistor is connected to the cathode of the second light-emitting diode, and the positive poles of the first light-emitting diode and the second light-emitting diode are connected to the second voltage output end of the power supply circuit.

6. The oxygen concentration detection circuit according to claim 1 or 5, characterized in that: The alarm circuit includes a vibration alarm circuit; the vibration alarm circuit includes a third resistor, a fourth resistor, a first rectifier diode, a transistor and a vibration motor; one end of the third resistor is connected to one end of the fourth resistor, and the connecting end is connected to the single-chip microcomputer, the other end of the third resistor is grounded, the other end of the fourth resistor is connected to the base of the transistor, the emitter of the transistor is grounded, the collector of the transistor is respectively connected to the negative input end of the vibration motor and the positive electrode of the first rectifier diode, and the negative electrode of the first rectifier diode and the positive input end of the vibration motor are connected to the second voltage output end of the power supply circuit.

7. A method for detecting oxygen concentration, characterized in that: The oxygen concentration detection circuit according to any one of claims 1 to 6 is used to detect oxygen concentration; the method comprises: receiving a signal representing oxygen concentration output by an optical oxygen sensor; The signal representing the oxygen concentration is compared with the reference range, and different alarm signals are sent to the alarm circuit according to the comparison result, so as to control the alarm circuit to send out the corresponding alarm.

8. The oxygen concentration detection method according to claim 7, characterized in that: If the signal representing the oxygen concentration is less than the lower limit of the reference range, and the difference between the lower limit and the signal representing the oxygen concentration is not greater than the first threshold, a first hypoxia alarm signal is issued; If the signal representing the oxygen concentration is less than the lower limit of the reference range, and the difference between the lower limit and the signal representing the oxygen concentration is greater than the first threshold, a second hypoxia alarm signal is issued; If the signal representing the oxygen concentration is greater than the upper limit of the reference range, and the difference between the signal representing the oxygen concentration and the upper limit is not greater than the second threshold, a first overoxygen alarm signal is issued; If the signal representing the oxygen concentration is greater than the upper limit of the reference range, and the difference between the signal representing the oxygen concentration and the upper limit is greater than a second threshold, a second overoxygen alarm signal is issued.

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