Liquid level detection circuit in glass tube and PCB (Printed Circuit Board)
Through the glass tube level detection circuit with the principle of photoelectric refractive, the problem of traditional liquid level sensors being affected by liquid conditions is solved, and the liquid level detection with higher accuracy and lower cost is achieved.
Patent Information
- Application Number
- CN202422471533.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-12
- Publication Date
- 2025-07-25
- Estimated Expiration
- 2034-10-12
AI Technical Summary
Traditional liquid level sensors are susceptible to liquid conditions, resulting in inaccurate detection results.
The liquid level detection circuit in the glass tube based on the principle of photoelectric refractive is adopted. The photoelectric sensor emits infrared light and receives refracted light from the liquid surface. The liquid level is judged in combination with the comparator circuit to reduce the influence of factors such as liquid turbidity and chromaticity.
Improve the reliability and accuracy of liquid level detection and reduce the detection cost.
Smart Images
Figure CN223154340U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of liquid level detection, and more specifically, to a liquid level detection circuit and a PCB board in a glass tube. Background Technique
[0002] Liquid level detection is to monitor the position of liquid, which has broad application prospects in industrial automation, environmental detection, agricultural automation, etc. By monitoring the change of liquid level, quantitative control of liquid and flow control can be realized, production efficiency and quality can be improved, and data support can be provided for environmental protection.
[0003] Liquid level sensors have experienced great development from traditional measurement methods to electronic sensor methods. Traditional methods such as buoyancy balls and measuring rods have problems such as limited measurement range, difficulty in automatically reading data, and susceptibility to external environmental interference. With the rapid development of electronic technology, new types of sensors such as capacitive, ultrasonic, and pressure sensors have emerged. These sensors have many advantages such as high precision, fast response, and easy integration, but there are still some application limitations. For example, capacitive sensors measure liquids with conductive properties; ultrasonic sensors are relatively large in volume and are not conducive to measuring small-volume liquids. However, the liquid level detection circuits based on the above several sensors are all affected by the liquid conditions and face challenges in terms of accuracy, reliability, sensitivity, etc.
[0004] Therefore, this application provides a liquid level detection circuit and a PCB board in a glass tube to solve the above problems. Content of the Utility Model
[0005] The technical problem to be solved by this application is that traditional liquid level sensors are easily affected by liquid conditions, resulting in inaccurate detection results. The purpose is to provide a liquid level detection circuit and a PCB board in a glass tube. The detection circuit is based on the principle of photoelectric refraction to detect the liquid level in the glass tube, reduce the influence of liquid conditions on liquid level detection, improve the reliability of detection results, improve the quantitative accuracy of liquids, and reduce the detection cost.
[0006] This application first provides a liquid level detection circuit in a glass tube, including: a power input terminal, a reference chip circuit, a current limiting circuit, a photoelectric sensor, a comparator circuit, and a signal output terminal; the power input terminal is connected to the reference chip circuit, the reference chip circuit is connected to the current limiting circuit, the current limiting circuit is connected to the emitting end of the photoelectric sensor, the receiving end of the photoelectric sensor is connected to the comparator circuit, and the comparator circuit is connected to the signal output terminal; wherein, the emitting end of the photoelectric sensor is used to emit infrared light to the liquid surface of the glass tube to be measured, and the receiving end of the photoelectric sensor is used to receive the infrared light refracted and returned by the liquid surface of the glass tube to be measured.
[0007] Adopting the above technical solution, combining with the refraction of infrared light for liquid level detection, improves the reliability of liquid level detection, and is not affected by factors such as liquid turbidity, chromaticity, conductivity, and volume; setting a special detection circuit can cooperate with the sensor position to accurately locate the liquid level height, determine the liquid volume in the pipe, and the quantitative result is more accurate; the detection circuit has a simple structure. Since it only detects whether there is a liquid level at a specific position, the requirements for the optoelectronic sensor are not high, reducing the manufacturing cost.
[0008] In a possible implementation, the signal output terminal is connected to a light-emitting diode.
[0009] In a possible implementation, the reference chip circuit includes: reference chip U3, MOS transistor Q1, resistor R8, and resistor R9. The C pin of reference chip U3 is connected to the base of MOS transistor Q1, and the C pin is also connected to the current-limiting circuit and the power input terminal through resistor R9. The A pin is connected to the ground terminal, the REF pin is connected to the source of MOS transistor Q1, and the REF pin is also connected to the ground terminal through resistor R8. The drain of MOS transistor Q1 is connected to the negative electrode of the emission end of the optoelectronic sensor.
[0010] In a possible implementation, the current-limiting circuit includes: resistor R10 and resistor R11. After resistor R10 and resistor R11 are connected in series, one end is connected to the power input terminal, and the other end is connected to the positive electrode of the emission end of the optoelectronic sensor.
[0011] In a possible implementation, the emitter of the receiving end of the optoelectronic sensor is connected to the ground terminal through voltage-dividing resistor R7, and the collector of the receiving end is connected to the power input terminal through voltage-dividing resistor R6.
[0012] In a possible implementation, the comparator circuit includes: current-limiting resistor R2, current-limiting resistor R3, comparator U1, reference voltage circuit, and decoupling capacitor circuit. The output terminal of the optoelectronic sensor and the output terminal of the reference voltage circuit are respectively connected to the negative and positive signal input pins of comparator U1 through current-limiting resistor R3 and current-limiting resistor R2. The VCC pin of comparator U1 is connected to the power input terminal, and the VCC pin is also connected to the ground terminal through the decoupling capacitor circuit. The GND pin is connected to the ground terminal, and the output terminal is used as the output of the detection circuit.
[0013] In a possible implementation, the reference voltage circuit includes: resistor R4 and resistor R5. One end of resistor R4 is connected to the power input terminal, the other end is connected to resistor R5, resistor R5 is connected to the ground terminal, and the connection point of resistor R4 and resistor R5 is used as the output terminal of the reference voltage circuit.
[0014] In a possible implementation, the decoupling capacitor circuit includes: decoupling capacitor C1 and decoupling capacitor C2 connected in parallel.
[0015] In a possible implementation, the power input terminal is connected to a 24V power supply.
[0016] The present application also provides a liquid level detection circuit PCB board for a glass tube, including: a substrate, on which the liquid level detection circuit for the glass tube as described above is provided.
[0017] Compared with the prior art, the present application has the following beneficial effects: The liquid level detection circuit and PCB board for the glass tube provided by the present application perform liquid level detection based on the refraction principle, and the turbidity and chromaticity of the liquid have no influence on the recognition of the liquid level, with higher detection accuracy; and the overall structure of this circuit is simple, with low requirements for electrical sensors, greatly reducing the detection cost. Description of the Drawings
[0018] The drawings described herein are used to provide a further understanding of the embodiments of the present utility model, form a part of the present application, and do not constitute a limitation to the embodiments of the present application. In the drawings:
[0019] Figure 1 is the schematic diagram of the liquid level detection circuit for the glass tube provided by the embodiment of the present application;
[0020] Figure 2 is the circuit diagram of the liquid level detection circuit for the glass tube provided by the embodiment of the present application;
[0021] Figure 3 is the schematic diagram of the liquid level detection circuit PCB board for the glass tube provided by the embodiment of the present application. Detailed Embodiments
[0022] To make the objectives, technical solutions, and advantages of the present utility model clearer and more understandable, the present utility model will be described in detail below in conjunction with the embodiments and the drawings. In a possible implementation manner, the illustrative embodiments and descriptions of the present utility model are only used to explain the present utility model and do not constitute a limitation to the present utility model.
[0023] Please refer to Figure 1 as shown in Figure 1 is the schematic diagram of the liquid level detection circuit for the glass tube provided by the embodiment of the present application. The circuit includes: a power input terminal, a reference chip circuit, a current limiting circuit, a photoelectric sensor, a comparator circuit, and a signal output terminal; the power input terminal is connected to the reference chip circuit, the reference chip circuit is connected to the current limiting circuit, the current limiting circuit is connected to the transmitting end of the photoelectric sensor, the receiving end of the photoelectric sensor is connected to the comparator circuit, and the comparator circuit is connected to the signal output terminal; wherein, the transmitting end of the photoelectric sensor is used to emit infrared light to the liquid level of the glass tube to be measured, and the receiving end of the photoelectric sensor is used to receive the infrared light refracted and returned by the liquid level of the glass tube to be measured.
[0024] The working principle of the circuit is that the input power supply supplies power to the transmitting end of the photoelectric sensor through the reference chip circuit; the current limiting circuit regulates the current flowing through the transmitting end of the infrared sensor; the transmitting end of the photoelectric sensor emits infrared light, and the infrared light is reflected and refracted at the liquid level of the glass tube to be measured; the refracted infrared light is received by the receiving end of the photoelectric sensor; the photoelectric sensor processes the received signal and sends it to the comparator circuit for comparison and output; whether the liquid level is detected can be judged according to the level of the output signal of the comparator circuit; further, the liquid level height can be determined in combination with the installation position of the red light photoelectric sensor.
[0025] The improvement of this circuit lies in that the liquid level is detected by combining the refraction of infrared light, which improves the reliability of liquid level detection and is not affected by factors such as liquid turbidity, chromaticity, conductivity, and volume; a special detection circuit is set up to accurately locate the liquid level height in cooperation with the sensor position, determine the liquid volume in the tube, and the quantitative result is more accurate; the detection circuit has a simple structure. Since only whether there is a liquid level at a specific position is detected, the requirements for the photoelectric sensor are not high, reducing the manufacturing cost.
[0026] Please refer to Figure 2 as shown in Figure 2 is the circuit diagram of the liquid level detection circuit in the glass tube provided by the embodiment of this application. In combination with Figure 2 each part of the detection circuit will be further described.
[0027] In a possible implementation manner, the signal output end is connected to the light emitting diode. The effect is that the high and low levels output by the signal output end are converted into whether the light emitting diode emits light, which can more intuitively show whether the liquid level is detected.
[0028] In a possible implementation manner, the reference chip circuit includes: a reference chip U3 (such as, TL431 chip), a MOS transistor Q1, a resistor R8, and a resistor R9. The C pin of the reference chip U3 is connected to the base of the MOS transistor Q1. The C pin is also connected to the current limiting circuit and the power input terminal through the resistor R9. The A pin is connected to the ground terminal. The REF pin is connected to the source of the MOS transistor Q1. The REF pin is also connected to the ground terminal through the resistor R8. The drain of the MOS transistor Q1 is connected to the negative pole of the transmitting end of the photoelectric sensor. The effect is that by setting up the reference chip circuit, a stable driving power supply is provided for the transmitting end of the photoelectric sensor.
[0029] In a possible implementation manner, the current limiting circuit includes: a resistor R10 and a resistor R11. After the resistor R10 and the resistor R11 are connected in series, one end is connected to the power input terminal, and the other end is connected to the positive pole of the transmitting end of the photoelectric sensor. The effect is that by setting up the current limiting circuit, the magnitude of the current at the transmitting end is restricted.
[0030] In a possible implementation, the emitter of the receiving end of the optoelectronic sensor is connected to the ground terminal through a voltage-dividing resistor R7, and the collector of the receiving end is connected to the power input terminal through a voltage-dividing resistor R6.
[0031] In a possible implementation, the comparator circuit includes: a current-limiting resistor R2, a current-limiting resistor R3, a comparator U1, a reference voltage circuit, and a decoupling capacitor circuit. The output terminal of the optoelectronic sensor and the output terminal of the reference voltage circuit are respectively connected to the negative and positive signal input pins of the comparator U1 through the current-limiting resistor R3 and the current-limiting resistor R2. The VCC pin of the comparator U1 is connected to the power input terminal, the VCC pin is also connected to the ground terminal through the decoupling capacitor circuit, the GND pin is connected to the ground terminal, and the output terminal serves as the output of the detection circuit.
[0032] Further, the reference voltage circuit includes: a resistor R4 and a resistor R5. One end of the resistor R4 is connected to the power input terminal, the other end is connected to the resistor R5, the resistor R5 is connected to the ground terminal, and the connection point of the resistor R4 and the resistor R5 serves as the output terminal of the reference voltage circuit.
[0033] Further, the decoupling capacitor circuit includes: a decoupling capacitor C1 and a decoupling capacitor C2 connected in parallel.
[0034] In a possible implementation, the power input terminal is connected to a 24V power supply.
[0035] As Figure 2 When the circuit shown works, the power input terminal provides a 24V power supply, and the ground terminal provides a GND connection. The reference chip U3 generates a constant current source to supply power to the emitter of the optoelectronic sensor U2. The current-limiting resistors R10 and R11 adjust the magnitude of the current flowing through the emitter of the optoelectronic sensor U2. The receiving end of the optoelectronic sensor U2 acts as a triode and generates a current according to the received light brightness. When the current is sufficient, the triode at the receiving end conducts; when the current is insufficient, the triode at the receiving end cuts off, making the signal magnitude at the receiving end of the optoelectronic sensor U2 different. The output signal of the optoelectronic sensor U2 is adjusted through the voltage-dividing resistors R6 and R7. The comparator U1 accesses the output signal of the optoelectronic sensor U2 and the reference signal output by the reference voltage circuit through the current-limiting resistors R2 and R3 respectively and compares them, and outputs a high-level signal or a low-level signal according to the comparison result.
[0036] When the liquid level is detected to exist, the output signal of the optoelectronic sensor U2 is relatively large, the OUT1 pin of the comparator U1 outputs a low-level signal, and the light-emitting diode D1 lights up. When the liquid level is detected to not exist, the output signal of the optoelectronic sensor U2 is relatively small, the OUT1 pin of the comparator outputs a high-level signal, and the light-emitting diode D1 goes out.
[0037] It should be noted that Figure 2 the circuit shown is only an example, Figure 2In the circuit, when the photoelectric sensor U2 detects the presence of the liquid level, the comparator U1 outputs a low-level signal, and at this time, the light-emitting diode D1 conducts and emits light. In actual production, the connection lines of the positive signal input terminal IN1+ and the negative signal input terminal IN1- of the comparator U1 can also be exchanged, the positive and negative poles of the light-emitting diode D1 can be exchanged, the negative terminal is connected to the resistor R1, and the other end of R1 is grounded. At this time, when the photoelectric sensor U2 detects the presence of the liquid level, the comparator U1 outputs a high-level signal, and the light-emitting diode D1 conducts and emits light, which can also indicate whether the liquid level is detected at this place.
[0038] To verify the effect of this circuit, turbidity experiments with gradients of 100, 200, 500, 800, 1000, 2000, 5000, etc. and chromaticity experiments of various colors were also carried out during the R & D work. The results show that this circuit can identify the state of the liquid level correctly; it can be seen that this circuit improves the reliability of liquid level detection and is not affected by the turbidity and chromaticity of the liquid. In addition, during the R & D work, quantitative experiments were carried out on 1 ml and 2.5 ml respectively in combination with the position of the photoelectric sensor U2. The results show that the quantitative accuracy and repeatability of this circuit can reach ±1%; it can be seen that this circuit improves the accuracy of quantification.
[0039] In summary, this circuit performs liquid level detection based on the refraction principle. The turbidity and chromaticity of the liquid have no influence on the identification of the liquid level, and the detection accuracy is higher; moreover, the overall structure of this circuit is simple, and a photoelectric sensor with a total cost of less than 5 yuan can replace a high-precision liquid level sensor costing nearly 100 yuan, greatly reducing the detection cost.
[0040] Please refer to Figure 3 as shown in Figure 3 This is a schematic diagram of the PCB board of the liquid level detection circuit in the glass tube provided by the embodiment of the present application. The PCB board of the liquid level detection circuit in the glass tube includes: a substrate, and the above-mentioned liquid level detection circuit in the glass tube is arranged on the substrate.
[0041] It should be noted that the above-mentioned detection circuit is arranged on this PCB board and has the same technical effects as the above-mentioned detection circuit, so it will not be elaborated here.
[0042] The above specific implementation manners further elaborate the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above are only the specific implementation manners of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A liquid level detection circuit inside a glass tube, characterized in that, Comprising: A power input terminal, a reference chip circuit, a current limiting circuit, a photoelectric sensor, a comparator circuit, and a signal output terminal; The power input terminal is connected to the reference chip circuit, the reference chip circuit is connected to the current limiting circuit, the current limiting circuit is connected to the emitting end of the photoelectric sensor, the receiving end of the photoelectric sensor is connected to the comparator circuit, and the comparator circuit is connected to the signal output terminal; Wherein, the emitting end of the photoelectric sensor is used to emit infrared light towards the liquid level of the glass tube to be measured, and the receiving end of the photoelectric sensor is used to receive the infrared light refracted and returned by the liquid level of the glass tube to be measured.
2. The liquid level detection circuit in a glass tube according to claim 1, wherein The signal output terminal is connected to a light emitting diode.
3. The liquid level detection circuit in a glass tube according to claim 1, characterized in that, The reference chip circuit includes: a reference chip U3, a MOS transistor Q1, a resistor R8, and a resistor R9. The C pin of the reference chip U3 is connected to the base of the MOS transistor Q1, the C pin is also connected to the current limiting circuit and the power input terminal through the resistor R9, the A pin is connected to the ground terminal, the REF pin is connected to the source of the MOS transistor Q1, the REF pin is also connected to the ground terminal through the resistor R8, and the drain of the MOS transistor Q1 is connected to the negative pole of the emitting end of the photoelectric sensor.
4. The liquid level detection circuit in a glass tube according to claim 1, characterized in that The current limiting circuit includes: a resistor R10 and a resistor R11. After the resistor R10 and the resistor R11 are connected in series, one end is connected to the power input terminal, and the other end is connected to the positive pole of the emitting end of the photoelectric sensor.
5. A liquid level detection circuit in a glass tube according to claim 1, characterized in that The emitter of the receiving end of the photoelectric sensor is connected to the ground terminal through a voltage dividing resistor R7, and the collector of the receiving end is connected to the power input terminal through a voltage dividing resistor R6.
6. The liquid level detection circuit in a glass tube according to claim 1, characterized in that, The comparator circuit includes: a current limiting resistor R2, a current limiting resistor R3, a comparator U1, a reference voltage circuit, and a decoupling capacitor circuit. The output terminals of the photoelectric sensor and the reference voltage circuit are respectively connected to the negative and positive signal input pins of the comparator U1 through the current limiting resistor R3 and the current limiting resistor R2. The VCC pin of the comparator U1 is connected to the power input terminal, the VCC pin is also connected to the ground terminal through the decoupling capacitor circuit, the GND pin is connected to the ground terminal, and the output terminal is used as the output of the detection circuit.
7. A liquid level detection circuit in a glass tube according to claim 6, characterized in that, The reference voltage circuit includes: a resistor R4 and a resistor R5. One end of the resistor R4 is connected to the power input terminal, the other end is connected to the resistor R5, the resistor R5 is connected to the ground terminal, and the connection point of the resistor R4 and the resistor R5 is used as the output terminal of the reference voltage circuit.
8. A liquid level detection circuit in a glass tube according to claim 6, characterized in that, The decoupling capacitor circuit includes: a decoupling capacitor C1 and a decoupling capacitor C2 connected in parallel.
9. A liquid level detection circuit in a glass tube according to claim 1, characterized in that, The power input terminal is connected to a 24V power supply.
10. A liquid level detection circuit PCB board inside a glass tube, characterized in that, Comprising: A substrate, on which a liquid level detection circuit inside a glass tube as described in any one of claims 1 - 9 is provided.