A detection circuit

Abstract

The application discloses a detection circuit which is applied to a liquid storage container in which detection medium is stored, and the liquid storage container comprises a first liquid level and a second liquid level with different heights; the detection circuit comprises a signal generating circuit, a detection unit and a signal processing circuit; the signal generating circuit is arranged at the first liquid level in the liquid storage container, the detection unit is arranged at the second liquid level in the liquid storage container, and the signal processing circuit is electrically connected with the detection unit; the signal generating circuit is used for generating a first reference signal, and the first reference signal has specific electrical parameters; the signal processing circuit is used for collecting a first electrical signal through the detection unit and judging the liquid level height of the detection medium according to the first electrical signal and the first reference signal; in the embodiment of the application, the first reference signal of the signal generating circuit is used as a reference, the first electrical signal and the first reference signal are detected to judge the liquid level height of the detection medium, and the stability and reliability of the detection circuit are improved.

Description

Technical Field

[0001] This invention relates to the field of liquid level detection technology, and in particular to a detection circuit. Background Technology

[0002] In industrial automated production processes, in order to achieve efficient and high-quality production, it is often necessary to detect and then control and regulate the liquid level.

[0003] There are various methods for measuring liquid level, and different liquid level detection devices are required for different methods.

[0004] Currently, liquid level detection devices rely on a single detection method and have low reliability. Summary of the Invention

[0005] This invention provides a detection circuit to improve the reliability of detection circuits.

[0006] According to one aspect of the present invention, a detection circuit is provided, applied in a liquid storage container containing a detection medium, the liquid storage container including a first liquid level and a second liquid level at different heights; the detection circuit includes:

[0007] The system includes a signal generation circuit, a detection unit, and a signal processing circuit. The signal generation circuit is located at a first liquid level in the liquid storage container, the detection unit is located at a second liquid level in the liquid storage container, and the signal processing circuit is electrically connected to the detection unit.

[0008] The signal generation circuit is used to generate a first reference signal, which has specific electrical parameters.

[0009] The signal processing circuit is used to acquire a first electrical signal through the detection unit, and to determine the liquid level height of the detection medium based on the first electrical signal and the first reference signal.

[0010] Furthermore, the signal processing circuit is used to determine that the detection medium has reached the target liquid level height when the first electrical parameter of the first electrical signal is the same as the specific electrical parameter.

[0011] If the second liquid level in the storage container is higher than the first liquid level, then the target liquid level height is equal to the second liquid level.

[0012] Alternatively, if the second liquid level in the storage container is lower than the first liquid level, then the target liquid level height is equal to the first liquid level.

[0013] Furthermore, the specific electrical parameters include at least one of a specific waveform, a specific signal amplitude, and a specific frequency.

[0014] Furthermore, the detection unit includes a conductive spring;

[0015] The conductive spring is used to acquire electrical signals in the detection medium and transmit them to the signal processing circuit when it comes into contact with the detection medium.

[0016] Furthermore, the signal generation circuit includes a first operational amplifier, a first voltage divider unit, a first filter unit, a first feedback unit, and a second feedback unit;

[0017] The first voltage divider unit is connected between the first power supply terminal and the ground terminal, and the output terminal of the first voltage divider unit is connected to the first input terminal of the first operational amplifier.

[0018] The first filter unit is connected between the ground terminal and the second input terminal of the first operational amplifier;

[0019] The output terminal of the first operational amplifier is connected to the first input terminal of the first operational amplifier through the first feedback unit, and the output terminal of the first operational amplifier is also connected to the second input terminal of the first operational amplifier through the second feedback unit.

[0020] The output of the first operational amplifier is used to output the first reference signal to the detection medium.

[0021] Furthermore, the first voltage divider unit includes a first resistor and a second resistor connected in series;

[0022] The first filtering unit includes a first capacitor and a second capacitor connected in parallel;

[0023] The first feedback unit includes a third resistor;

[0024] The second feedback unit includes a fourth resistor.

[0025] Furthermore, the signal processing circuit includes: an acquisition module, a second voltage divider unit, and a processing module;

[0026] The acquisition module includes a second operational amplifier, a first acquisition unit, a second filtering unit, and a third feedback unit. The first acquisition unit is connected between the detection unit and the ground terminal. The output terminal of the first acquisition unit is connected to the first input terminal of the second operational amplifier. The second filtering unit is connected between the ground terminal and the second input terminal of the second operational amplifier. The third feedback unit is connected between the output terminal of the second operational amplifier and the positive power supply terminal of the second operational amplifier. The negative power supply terminal of the second operational amplifier is connected to the ground terminal.

[0027] The second voltage divider unit is connected between the first power supply terminal and the ground terminal, and the output terminal of the second voltage divider unit is connected to the second input terminal of the second operational amplifier;

[0028] The output of the second operational amplifier is connected to the processing module.

[0029] Furthermore, the signal processing circuit includes at least two of the acquisition modules;

[0030] The output of the second voltage divider unit is connected to the second input of the second operational amplifier of at least one of the acquisition modules.

[0031] Furthermore, the first acquisition unit includes a fifth resistor, a sixth resistor, and a third capacitor. The fifth resistor is connected in series with the sixth resistor, the other end of the sixth resistor is connected to the ground terminal, and the sixth resistor is connected in parallel with the third capacitor.

[0032] The second filter unit includes a fourth capacitor;

[0033] The third feedback unit includes a seventh resistor;

[0034] The second voltage divider unit includes an eighth resistor and a ninth resistor connected in series;

[0035] The output of the second operational amplifier is connected to the processing module via a tenth resistor.

[0036] Furthermore, the processing module includes a microprocessor.

[0037] In this embodiment of the invention, a signal generation circuit generates a first reference signal, and a signal processing circuit acquires a first electrical signal through a detection unit. Based on the first electrical signal and the first reference signal, the liquid level height of the detection medium is determined. In this embodiment, the first reference signal from the signal generation circuit is used as a reference, and the liquid level height of the detection medium is determined by detecting the first electrical signal and the first reference signal, thus improving the stability and reliability of the detection circuit.

[0038] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of a detection circuit provided in an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of another detection circuit provided in an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the signal generation circuit provided in an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of another detection circuit provided in an embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram of another detection circuit provided in an embodiment of the present invention. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0046] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0047] Figure 1 This is a schematic diagram of a detection circuit provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of another detection circuit provided in an embodiment of the present invention. This embodiment is applicable to the detection of liquid level. Figure 1As shown, the detection circuit 10 is applied in a liquid storage container 11 containing a detection medium. The liquid storage container 11 includes a first liquid level A and a second liquid level B at different heights. The detection circuit 10 includes a signal generation circuit 12, a detection unit 13, and a signal processing circuit 14. The signal generation circuit 12 is located at the first liquid level A in the liquid storage container 11, and the detection unit 13 is located at the second liquid level B in the liquid storage container 11. The signal processing circuit 14 is electrically connected to the detection unit 13. The signal generation circuit 12 is used to generate a first reference signal, which has specific electrical parameters. The signal processing circuit 14 is used to acquire the first electrical signal through the detection unit 13 and determine the liquid level height of the detection medium based on the first electrical signal and the first reference signal. Figure 1 If the second liquid level B in the optional liquid storage container 11 is higher than the first liquid level A, then the target liquid level height is equal to the second liquid level B; Figure 2 If the second liquid level B in the optional liquid storage container 11 is lower than the first liquid level A, then the target liquid level height is equal to the first liquid level A. In this embodiment, Figure 1 The detection circuit shown is used as an example for explanation; subsequent embodiments will use... Figure 2 The detection circuit shown is used as an example for explanation.

[0048] In this embodiment, the storage container 11 stores a detection medium, which is a conductive liquid, such as water or other types of conductive liquid. The storage container 11 includes a first liquid level A and a second liquid level B at different heights. Here, the first liquid level A is a predetermined liquid level height detection point, and the second liquid level B is a predetermined liquid level height detection point. Optionally, the second liquid level B in the storage container 11 is higher than the first liquid level A, then the target liquid level height of the detection medium is equal to the second liquid level B. Specifically, the detection circuit 10 is used to detect whether the detection medium in the storage container 11 has reached the height of the second liquid level B. The structure of the illustrated storage container 11 is only a simple example. In practice, the structure of the storage container 11 also includes other structures. The detection circuit 10 can be applied to any type of storage container 11, and is not limited to this.

[0049] The detection circuit 10 includes a signal generation circuit 12, which is positioned at a first liquid level A within the liquid storage container 11. The signal generation circuit 12 generates a first reference signal. It is understood that if the liquid level of the detection medium in the liquid storage container 11 is equal to or higher than the first liquid level A, causing the signal generation circuit 12 to contact the detection medium, then the first reference signal from the signal generation circuit 12 will be transmitted to the detection medium. Conversely, if the liquid level of the detection medium in the liquid storage container 11 is lower than the first liquid level A, causing the signal generation circuit 12 to not contact the detection medium, then the first reference signal from the signal generation circuit 12 cannot be transmitted to the detection medium. Since the detection medium is conductive, when the signal generation circuit 12 is in contact with the detection medium, the first reference signal generated by the signal generation circuit 12 can propagate within the detection medium.

[0050] The first reference signal has specific electrical parameters, which may include at least one of a specific waveform, a specific signal amplitude, and a specific frequency. If the specific electrical parameter is a specific frequency, then the first reference signal generated by the signal generation circuit 12 has a specific frequency. For example, the first reference signal generated by the signal generation circuit 12 is an electrical signal with a fixed frequency of 370Hz. Alternatively, if the specific electrical parameter is a specific waveform, then the first reference signal generated by the signal generation circuit 12 has a specific waveform. For example, the first reference signal generated by the signal generation circuit 12 is a square wave electrical signal. Or, the specific electrical parameter includes a specific waveform, a specific signal amplitude, and a specific frequency. For example, the first reference signal generated by the signal generation circuit 12 is a 370Hz square wave signal with a signal amplitude of 3.3V.

[0051] The detection circuit 10 includes a detection unit 13, which is positioned at the second liquid level B within the storage container 11. When the detection unit 13 comes into contact with the detection medium, it can collect a first electrical signal from the detection medium. It can be understood that if the liquid level of the detection medium in the storage container 11 is equal to or exceeds the second liquid level B, both the detection unit 13 and the signal generation circuit 12 are in contact with the detection medium. In this case, the signal generation circuit 12, the detection medium, and the detection unit 13 form a transmission path, and the detection unit 13 collects the first electrical signal associated with the first reference signal from the detection medium. Conversely, if the liquid level of the detection medium in the storage container 11 is lower than the second liquid level B, the detection unit 13 is not in contact with the detection medium. Therefore, the transmission path between the signal generation circuit 12 and the detection unit 13 is broken, and the detection unit 13 cannot detect a signal, i.e., there is no signal output.

[0052] When the detection medium is a conductive medium, and the signal generation circuit 12 is in contact with the detection medium, and the detection unit 13 is in contact with the detection medium, the first reference signal generated by the signal generation circuit 12 can propagate in the detection medium, and the detection unit 13 can collect the first electrical signal associated with the first reference signal from the detection medium; when the detection unit 13 is not in contact with the detection medium, the detection unit 13 has no signal output.

[0053] The detection circuit 10 includes a signal processing circuit 14, which is electrically connected to the detection unit 13. The signal processing circuit 14 is used to acquire a first electrical signal through the detection unit 13, process the first electrical signal, and compare the first electrical signal with a first reference signal. Optionally, the signal processing circuit 14 is used to determine that the detection medium has reached the target liquid level height when the first electrical parameter of the detected first electrical signal is the same as a specific electrical parameter; if the second liquid level B in the storage container 11 is higher than the first liquid level A, then the target liquid level height is equal to the second liquid level B.

[0054] If the first electrical signal contains an electrical parameter identical to a specific parameter of the first reference signal, it indicates that the first electrical signal acquired by the detection unit 13 is associated with the first reference signal propagating into the detection medium. This means the detection unit 13 has come into contact with the detection medium, and the liquid level of the detection medium has reached the second liquid level B (i.e., the target liquid level) where the detection unit 13 is located. Conversely, if the detection unit 13 has no signal output, it means the detection unit 13 has not come into contact with the detection medium, and the liquid level of the detection medium has not reached the second liquid level B (i.e., the target liquid level) where the detection unit 13 is located.

[0055] like Figure 2 As shown, the optional signal processing circuit 14 is used to determine that the detection medium has reached the target liquid level height when the first electrical parameter of the detected first electrical signal is the same as a specific electrical parameter; if the second liquid level B in the liquid storage container 11 is lower than the first liquid level A, then the target liquid level height is equal to the first liquid level A.

[0056] In this embodiment, if the second liquid level B in the storage container 11 is lower than the first liquid level A, then the target liquid level height of the detection medium is equal to the first liquid level A. Specifically, the detection circuit 10 is used to detect whether the detection medium in the storage container 11 has reached the height of the first liquid level A.

[0057] The detection unit 13 is positioned at the second liquid level B within the storage container 11. When the detection unit 13 comes into contact with the detection medium, it can collect a first electrical signal from the detection medium. It can be understood that if the liquid level of the detection medium in the storage container 11 is equal to or greater than the second liquid level B, causing the detection unit 13 to come into contact with the detection medium, then the detection unit 13 will collect the first electrical signal from the detection medium; conversely, if the liquid level of the detection medium in the storage container 11 is lower than the second liquid level B, causing the detection unit 13 to not come into contact with the detection medium, then the detection unit 13 will not output a signal.

[0058] The signal generation circuit 12 is located at the first liquid level A inside the liquid storage container 11. The signal generation circuit 12 is used to generate a first reference signal. It can be understood that when the liquid level of the detection medium in the liquid storage container 11 is equal to or exceeds the first liquid level A, both the detection unit 13 and the signal generation circuit 12 are in contact with the detection medium. In this case, the signal generation circuit 12, the detection medium, and the detection unit 13 form a transmission path, and the first reference signal from the signal generation circuit 12 is transmitted to the detection medium. The detection unit 13 then collects the first electrical signal associated with the first reference signal from the detection medium. Conversely, when the liquid level of the detection medium in the liquid storage container 11 is lower than the first liquid level A, the signal generation circuit 12 is not in contact with the detection medium. Therefore, the transmission path between the signal generation circuit 12 and the detection unit 13 is broken, the first reference signal from the signal generation circuit 12 cannot be transmitted to the detection medium, and the detection unit 13 has no signal output.

[0059] The signal processing circuit 14 is used to acquire a first electrical signal through the detection unit 13. The signal processing circuit 14 processes the first electrical signal and compares it with a first reference signal. If the first electrical signal contains an electrical parameter that is identical to a specific parameter of the first reference signal, it indicates that the first electrical signal acquired by the detection unit 13 is associated with the first reference signal propagating into the detection medium. It can be determined that the signal generating circuit 12 has contacted the detection medium, and the liquid level of the detection medium has reached the first liquid level A, i.e., the target liquid level height, where the signal generating circuit 12 is located. Conversely, if the detection unit 13 has no signal output, it can be determined that the signal generating circuit 12 has not contacted the detection medium, and the liquid level of the detection medium has not reached the first liquid level A, i.e., the target liquid level height, where the signal generating circuit 12 is located.

[0060] Optional detection unit 13 includes a conductive spring; the conductive spring is used to acquire electrical signals in the detection medium and transmit them to the signal processing circuit 14 when it comes into contact with the detection medium. Detection unit 13 is pre-installed at the desired second liquid level. If the conductive spring comes into contact with the detection medium, it can acquire electrical signals in the detection medium and transmit them to the signal processing circuit 14. The conductive spring serves as detection unit 13, offering low cost. Furthermore, detection unit 13 may include one or more conductive springs; the number of conductive springs is not specifically limited.

[0061] In this embodiment of the invention, a signal generation circuit generates a first reference signal, and a signal processing circuit acquires a first electrical signal through a detection unit. Based on the first electrical signal and the first reference signal, the liquid level height of the detection medium is determined. In this embodiment, the first reference signal from the signal generation circuit is used as a reference, and the liquid level height of the detection medium is determined by detecting the first electrical signal and the first reference signal, thus improving the stability and reliability of the detection circuit.

[0062] Figure 3 This is a schematic diagram of the signal generation circuit provided in an embodiment of the present invention. Figure 3As shown, the optional signal generation circuit 12 includes a first operational amplifier U1, a first voltage divider unit 15, a first filter unit 16, a first feedback unit 17, and a second feedback unit 18. The first voltage divider unit 15 is connected between the first power supply terminal VCC and the ground terminal GND, and its output terminal is connected to the first input terminal of the first operational amplifier U1. The first filter unit 16 is connected between the ground terminal GND and the second input terminal of the first operational amplifier U1. The output terminal of the first operational amplifier U1 is connected to its first input terminal via the first feedback unit 17, and its second input terminal is also connected via the second feedback unit 18. The output terminal of the first operational amplifier U1 is used to output a first reference signal to the detection medium. The optional first voltage divider unit 15 includes a first resistor R1 and a second resistor R2 connected in series; the first filter unit 16 includes a first capacitor C1 and a second capacitor C2 connected in parallel; the first feedback unit 17 includes a third resistor R3; and the second feedback unit 18 includes a fourth resistor R4.

[0063] In this embodiment, the signal generation circuit 12 includes a first operational amplifier U1, which includes a first input terminal (+), a second input terminal (-), a positive power supply terminal, a negative power supply terminal, and an output terminal U1O.

[0064] The signal generation circuit 12 includes a first voltage divider unit 15. The first terminal of the first voltage divider unit 15 is connected to the first power supply terminal VCC, the second terminal of the first voltage divider unit 15 is connected to the ground terminal GND, and the output terminal of the first voltage divider unit 15 is connected to the non-inverting input terminal (+) of the first operational amplifier U1. The first voltage divider unit 15 includes a first resistor R1 and a second resistor R2 connected in series. The first terminal of the first resistor R1 is connected to the first power supply terminal VCC, the first terminal of the second resistor R2 is connected to the ground terminal GND, and the second terminal of the first resistor R1 is connected to the second terminal of the second resistor R2 and serves as the output terminal of the first voltage divider unit 15, connected to the non-inverting input terminal (+) of the first operational amplifier U1. The voltage value at the second terminal of the second resistor R2 is transmitted as the divided voltage value to the non-inverting input terminal (+) of the first operational amplifier U1. It can be understood that if the resistance values ​​of the first resistor R1 and the second resistor R2 change, the divided voltage value output from the second terminal of the second resistor R2 will change. The voltage divider unit 15 provides the reference voltage divider value to the non-inverting input (+) of the first operational amplifier U1.

[0065] The signal generation circuit 12 includes a first filtering unit 16, which is connected between ground (GND) and the second input terminal of the first operational amplifier U1. The first filtering unit 16 includes a first capacitor C1 and a second capacitor C2 connected in parallel. The first terminal of the first capacitor C1 is connected to the first terminal of the second capacitor C2 and both are connected to the inverting input terminal (-) of the first operational amplifier U1. The second terminal of the first capacitor C1 is connected to the second terminal of the second capacitor C2 and both are connected to ground (GND). The first filtering unit 16 filters the signal transmitted to the second input terminal of the first operational amplifier U1, which can improve the accuracy of the detection signal and enhance the reliability of the control circuit.

[0066] The signal generation circuit 12 includes a first feedback unit 17 and a second feedback unit 18. The output terminal U1O of the first operational amplifier U1 is connected to the first input terminal of the first operational amplifier U1 through the first feedback unit 17, and the output terminal U1O of the first operational amplifier U1 is also connected to the second input terminal of the first operational amplifier U1 through the second feedback unit 18. The first feedback unit 17 includes a third resistor R3; the second feedback unit 18 includes a fourth resistor R4. The output terminal U1O of the first operational amplifier U1 is connected to the non-inverting input terminal (+) of the first operational amplifier U1 through the third resistor R3, and the output terminal U1O of the first operational amplifier U1 is also connected to the inverting input terminal (-) of the first operational amplifier U1 through the fourth resistor R4.

[0067] The output terminal U1O of the first operational amplifier U1 outputs a first reference signal to the detection medium through resistor R11. The positive power supply terminal of the first operational amplifier U1 is connected to the first power supply terminal VCC, and the negative power supply terminal of the first operational amplifier U1 is connected to the ground terminal GND.

[0068] In this embodiment, by adjusting the resistance values ​​of resistors and the capacitance values ​​of capacitors, the signals at the two input terminals of the first operational amplifier U1 can be adjusted, thereby forming a first reference signal with specific parameters. For example, the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 can all be 100KΩ, and the resistance value of resistor R11 can be 1KΩ; the capacitance values ​​of the first capacitor C1 and the second capacitor C2 can both be 10nF; the voltage value of the first power supply terminal VCC is 3V; then the output terminal U1O of the first operational amplifier U1 outputs a stable 370Hz square wave signal through resistor R11, and the signal amplitude of this square wave signal is 3.3V.

[0069] Figure 4 This is a schematic diagram of another detection circuit provided in an embodiment of the present invention. Figure 4As shown, the optional signal processing circuit 14 includes: an acquisition module 19, a second voltage divider unit 20, and a processing module 21; the acquisition module 19 includes a second operational amplifier U2, a first acquisition unit 22, a second filtering unit 23, and a third feedback unit 24. The first acquisition unit 22 is connected between the detection unit 13 and the ground terminal GND, and the output terminal of the first acquisition unit 22 is connected to the first input terminal of the second operational amplifier U2. The second filtering unit 23 is connected between the ground terminal GND and the second input terminal of the second operational amplifier U2. The third feedback unit 24 is connected between the output terminal U2O of the second operational amplifier U2 and the positive power supply terminal of the second operational amplifier U2. The negative power supply terminal of the second operational amplifier U2 is connected to the ground terminal GND; the second voltage divider unit 20 is connected between the first power supply terminal VCC and the ground terminal GND, and the output terminal of the second voltage divider unit 20 is connected to the second input terminal of the second operational amplifier U2; the output terminal of the second operational amplifier U2 is connected to the processing module 21. The optional first acquisition unit 22 includes a fifth resistor R5, a sixth resistor R6, and a third capacitor C3. The fifth resistor R5 is connected in series with the sixth resistor R6, and the other end of the sixth resistor R6 is connected to ground GND. The sixth resistor R6 is connected in parallel with the third capacitor C3. The second filtering unit 23 includes a fourth capacitor C4. The third feedback unit 24 includes a seventh resistor R7. The second voltage divider unit 20 includes an eighth resistor R8 and a ninth resistor R9 connected in series. The output terminal U2O of the second operational amplifier U2 is connected to the processing module 21 through a tenth resistor R10. The optional processing module 21 includes a microprocessor.

[0070] In this embodiment, the signal processing circuit 14 includes an acquisition module 19, a second voltage divider unit 20, and a processing module 21.

[0071] The acquisition module 19 includes a second operational amplifier U2, which includes a first input terminal (non-inverting input, +), a second input terminal (inverting input, -), a positive power supply terminal, a negative power supply terminal, and an output terminal U2O. The positive power supply terminal of the second operational amplifier U2 is connected to the first power supply terminal VCC, and the negative power supply terminal of the second operational amplifier U2 is connected to the ground terminal GND.

[0072] The acquisition module 19 includes a first acquisition unit 22. The first end of the first acquisition unit 22 is connected to the detection unit 13, and the second end of the first acquisition unit 22 is connected to ground (GND). The output end of the first acquisition unit 22 is connected to the non-inverting input (+) of the second operational amplifier U2. The first acquisition unit 22 acquires a first electrical signal from the detection unit 13 and transmits the first electrical signal to the non-inverting input (+) of the second operational amplifier U2. The first acquisition unit 22 includes a fifth resistor R5 and a sixth resistor R6 connected in series. The first end of the fifth resistor R5 is connected to the detection unit 13, and the first end of the sixth resistor R6 is connected to ground (GND). The second end of the fifth resistor R5 is connected to the second end of the sixth resistor R6 and serves as the output end of the first acquisition unit 22, connected to the non-inverting input (+) of the second operational amplifier U2. The first acquisition unit 22 includes a third capacitor C3, which is connected between the second end of the fifth resistor R5 and ground (GND). It can be understood that if the first electrical signal received by the detection unit 13 changes, the voltage value output from the second end of the sixth resistor R6 will change.

[0073] The acquisition module 19 includes a second filtering unit 23, which is connected between ground (GND) and the second input terminal of the second operational amplifier U2. The second filtering unit 23 includes a fourth capacitor C4, which is connected between ground (GND) and the inverting input terminal (-) of the second operational amplifier U2, filtering the acquired first electrical signal. The second filtering unit 23 filters the signal transmitted to the second input terminal of the second operational amplifier U2, improving the accuracy of the detection signal and the reliability of the control circuit.

[0074] The acquisition module 19 includes a third feedback unit 24, which is connected between the output terminal U2O of the second operational amplifier U2 and the positive power supply terminal of the second operational amplifier U2. The third feedback unit 24 includes a seventh resistor R7, which is also connected between the output terminal U2O of the second operational amplifier U2 and the positive power supply terminal of the second operational amplifier U2. The seventh resistor R7 is a pull-up resistor, ensuring that the second operational amplifier U2 stably outputs an initial level when the detection unit 13 has no signal output.

[0075] The signal processing circuit 14 includes a second voltage divider unit 20, which is connected between the first power supply terminal VCC and the ground terminal GND. The output terminal of the second voltage divider unit 20 is connected to the second input terminal of the second operational amplifier U2. The first terminal of the second voltage divider unit 20 is connected to the first power supply terminal VCC, the second terminal of the second voltage divider unit 20 is connected to the ground terminal GND, and the output terminal of the second voltage divider unit 20 is connected to the inverting input terminal (-) of the second operational amplifier U2. The second voltage divider unit 20 includes an eighth resistor R8 and a ninth resistor R9 connected in series. The first terminal of the eighth resistor R8 is connected to the first power supply terminal VCC, the first terminal of the ninth resistor R9 is connected to the ground terminal GND, the second terminal of the eighth resistor R8 is connected to the second terminal of the ninth resistor R9 and serves as the output terminal of the second voltage divider unit 20, which is connected to the inverting input terminal (-) of the second operational amplifier U2. The voltage value at the second terminal of the ninth resistor R9 is transmitted as the divided voltage value to the inverting input terminal (-) of the second operational amplifier U2. It is understandable that if the resistance values ​​of the eighth resistor R8 and the ninth resistor R9 change, then the voltage division value output from the second terminal of the ninth resistor R9 will change. The voltage division value provided by the second voltage divider unit 20 to the inverting input terminal (-) of the second operational amplifier U2 is the reference voltage division value.

[0076] The output terminal U2O of the second operational amplifier U2 is connected to the processing module 21 through the tenth resistor R10. The optional processing module 21 includes a microprocessor. The tenth resistor R10 is the signal output resistor and also serves a current limiting function.

[0077] In this embodiment, the first electrical signal in the detection medium acquired by the detection unit 13 has a relatively small amplitude and severely distorted waveform, which is then shaped by the signal processing circuit 14. If the first electrical signal acquired by the detection unit 13 is associated with the first reference signal, then after being shaped by the signal processing circuit 14, the electrical parameters of the first electrical signal are the same as the specific electrical parameters of the first reference signal, thereby determining that the detection medium has reached the target liquid level height. If the detection unit 13 has no signal output, then after being shaped by the signal processing circuit 14, the electrical parameters of the first electrical signal are different from the specific electrical parameters of the first reference signal, thereby determining that the detection medium has not reached the target liquid level height.

[0078] For example, the first reference signal is a 370Hz square wave signal with a 3.3V level. If the first electrical signal acquired by the detection unit 13 is associated with the first reference signal, then the first electrical signal output after being shaped by the second operational amplifier U2 is a standard 370Hz square wave signal with a 3.3V level, indicating that the detected medium has reached the target liquid level. If the detection unit 13 has no signal output, then the resistor in the first acquisition unit 22 is grounded, and the first electrical signal transmitted to the non-inverting input (+) of the second operational amplifier U2 is a stable low level. If the processing module 21 detects that the signal output by the second operational amplifier U2 is a continuous square wave signal of approximately 370Hz, it can determine that the detected medium has reached the target liquid level; conversely, if the processing module 21 detects that the signal output by the second operational amplifier U2 is a stable low level, it can determine that the detected medium has not reached the target liquid level.

[0079] Figure 5 This is a schematic diagram of another detection circuit provided in an embodiment of the present invention. Figure 5 As shown, the optional signal processing circuit 14 includes: at least two acquisition modules 19a and 19b; the output terminal JZ of the second voltage divider unit 20 is connected to the second input terminal of the second operational amplifier of at least one acquisition module.

[0080] In this embodiment, the signal processing circuit 14 includes an acquisition module 19a, which includes a second operational amplifier U2a, a first acquisition unit 22a, a second filtering unit 23a, and a third feedback unit 24a. The signal processing circuit 14 also includes an acquisition module 19b, which includes a second operational amplifier U2b, a first acquisition unit 22b, a second filtering unit 23b, and a third feedback unit 24b.

[0081] The detection unit 13 is connected to the first end of the first acquisition unit 22a, and the detection unit 13 is also connected to the first end of the first acquisition unit 22b. Figure 5 The output terminal JZ of the second voltage divider unit 20 is connected to the second input terminal (-) of the second operational amplifier U2a of the acquisition module 19a, and the output terminal JZ of the second voltage divider unit 20 is also connected to the second input terminal (-) of the second operational amplifier U2b of the acquisition module 19b.

[0082] In the acquisition module 19a, the output terminal U2aO of the second operational amplifier U2a is connected to the processing module 21 through the tenth resistor R10a, and the output terminal U2bO of the second operational amplifier U2b in the acquisition module 19b is connected to the processing module 21 through the tenth resistor R10b.

[0083] In this embodiment, at least two sets of acquisition modules are used to detect the electrical signal output by the detection unit, which can improve the stability and reliability of the detection circuit. That is, as long as one of the two sets detects a valid signal, it can be determined whether the detection medium has reached the target height, thus improving the reliability of the detection circuit.

[0084] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A detection circuit, characterized in that, Applied in a liquid storage container containing a detection medium, the liquid storage container includes a first liquid level and a second liquid level at different heights; the detection circuit includes: The system includes a signal generation circuit, a detection unit, and a signal processing circuit. The signal generation circuit is located at a first liquid level in the liquid storage container, the detection unit is located at a second liquid level in the liquid storage container, and the signal processing circuit is electrically connected to the detection unit. The signal generation circuit is used to generate a first reference signal, the first reference signal having specific electrical parameters, the specific electrical parameters including a specific waveform and a specific frequency; The signal processing circuit is used to acquire a first electrical signal through the detection unit, and determine the liquid level height of the detection medium based on the first electrical signal and the first reference signal; The signal processing circuit is used to determine that the detection medium has reached the target liquid level height when the first electrical parameter of the first electrical signal is the same as the specific electrical parameter; if the second liquid level in the storage container is higher than the first liquid level, then the target liquid level height is equal to the second liquid level; or, if the second liquid level in the storage container is lower than the first liquid level, then the target liquid level height is equal to the first liquid level. The signal generation circuit includes a first operational amplifier, a first voltage divider unit, a first filter unit, a first feedback unit, and a second feedback unit; The first voltage divider unit is connected between the first power supply terminal and the ground terminal, and the output terminal of the first voltage divider unit is connected to the first input terminal of the first operational amplifier. The first filter unit is connected between the ground terminal and the second input terminal of the first operational amplifier; The output terminal of the first operational amplifier is connected to the first input terminal of the first operational amplifier through the first feedback unit, and the output terminal of the first operational amplifier is also connected to the second input terminal of the first operational amplifier through the second feedback unit. The output of the first operational amplifier is used to output the first reference signal to the detection medium.

2. The detection circuit according to claim 1, characterized in that, The detection unit includes a conductive spring; The conductive spring is used to acquire electrical signals in the detection medium and transmit them to the signal processing circuit when it comes into contact with the detection medium.

3. The detection circuit according to claim 1, characterized in that, The first voltage divider unit includes a first resistor and a second resistor connected in series; The first filtering unit includes a first capacitor and a second capacitor connected in parallel; The first feedback unit includes a third resistor; The second feedback unit includes a fourth resistor.

4. The detection circuit according to claim 1, characterized in that, The signal processing circuit includes: an acquisition module, a second voltage divider unit, and a processing module; The acquisition module includes a second operational amplifier, a first acquisition unit, a second filtering unit, and a third feedback unit. The first acquisition unit is connected between the detection unit and the ground terminal. The output terminal of the first acquisition unit is connected to the first input terminal of the second operational amplifier. The second filtering unit is connected between the ground terminal and the second input terminal of the second operational amplifier. The third feedback unit is connected between the output terminal of the second operational amplifier and the positive power supply terminal of the second operational amplifier. The negative power supply terminal of the second operational amplifier is connected to the ground terminal. The second voltage divider unit is connected between the first power supply terminal and the ground terminal, and the output terminal of the second voltage divider unit is connected to the second input terminal of the second operational amplifier; The output of the second operational amplifier is connected to the processing module.

5. The detection circuit according to claim 4, characterized in that, The signal processing circuit includes at least two of the acquisition modules; The output of the second voltage divider unit is connected to the second input of the second operational amplifier of at least one of the acquisition modules.

6. The detection circuit according to claim 4, characterized in that, The first acquisition unit includes a fifth resistor, a sixth resistor, and a third capacitor. The fifth resistor is connected in series with the sixth resistor, the other end of the sixth resistor is connected to the ground terminal, and the sixth resistor is connected in parallel with the third capacitor. The second filter unit includes a fourth capacitor; The third feedback unit includes a seventh resistor; The second voltage divider unit includes an eighth resistor and a ninth resistor connected in series; The output of the second operational amplifier is connected to the processing module via a tenth resistor.

7. The detection circuit according to claim 4, characterized in that, The processing module includes a microprocessor.

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