Photoelectric zero contact type liquid level detection circuit

Abstract

The utility model discloses a photoelectric zero contact type liquid level detection circuit, and belongs to the field of liquid level detection circuits. The liquid level detection circuit is composed of an infrared transmitting and receiving circuit and a comparison circuit, the infrared transmitting and receiving circuit is linearly connected with the comparison circuit, and the infrared transmitting and receiving circuit is divided into a high-level circuit and a low-level circuit; the level of the output end of the chip U1 is obtained by comparing the voltage value at the joint between the infrared transmitting and receiving circuit and the comparison circuit with a reference voltage value, and then the liquid level condition is judged; according to the non-contact liquid level detection circuit, liquid level detection is achieved in a non-contact photoelectric mode, the liquid level condition can be detected without making contact with liquid, and therefore the problems that due to a contact mode, a metal probe is prone to being corroded due to polarization, the liquid is deteriorated due to electrolysis, the structural space requirement is large, and sanitation is not achieved are solved. The device has the characteristics of low cost, high precision, small size and high reliability.

Description

Technical Field

[0001] The utility model relates to the field of liquid level detection circuits, in particular to a photoelectric zero-contact liquid level detection circuit. Background Art

[0002] Many industry products use various liquids, such as water tanks for water purifiers and test kits for medical equipment. They all need to detect the liquid level for alarm prompts and automatic liquid replenishment. At present, the mainstream liquid level sensors still use contact methods, such as using liquid level metal probes and floats. However, the liquid level metal probe method requires power to be supplied to the metal probe. Long-term charge accumulation is prone to problems such as metal needle polarization rust and liquid electrolysis, leading to misjudgment. The float is large in size and is not suitable when there are space requirements. Utility Model Content

[0003] The purpose of the utility model is to provide a photoelectric zero-contact liquid level detection circuit to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the utility model provides the following technical solutions:

[0005] A photoelectric zero-contact liquid level detection circuit is composed of an infrared transmitting and receiving circuit and a comparison circuit. The infrared transmitting and receiving circuit and the comparison circuit are electrically connected, and the infrared transmitting and receiving circuit is divided into a high-position circuit and a low-position circuit.

[0006] Further, the comparison circuit includes: a resistor R3, a capacitor C3, a capacitor C2, a resistor R4, a resistor R5, a chip U1, a resistor R6, a resistor R7, and a resistor R10;

[0007] Wherein, the first end of the chip U1 is connected to the second end of the resistor R3 and the first end of the resistor R5;

[0008] The second terminal of the chip U1 is connected to the reference voltage terminal;

[0009] The third terminal of the chip U1 is connected to the second terminal of the resistor R5 and the second terminal of the resistor R6;

[0010] The fourth terminal of the chip U1 is grounded;

[0011] The fifth terminal of the chip U1 is connected to the second terminal of the resistor R7 and the second terminal of the resistor R10;

[0012] The sixth terminal of the chip U1 is connected to the reference voltage terminal;

[0013] The seventh terminal of the chip U1 is connected to the second terminal of the resistor R4 and the first terminal of the resistor R7;

[0014] The eighth terminal of the chip U1 is connected to the first terminal of the resistor R3, the positive electrode of the power supply, the first terminal of the capacitor C3, the first terminal of the capacitor C2 and the first terminal of the resistor R4;

[0015] The second end of the capacitor C3 is connected to the second end of the capacitor C2 and both are grounded.

[0016] Furthermore, the model of chip U1 is LM393.

[0017] Furthermore, the high-order circuit includes: a resistor R1, a resistor R2, a diode D1, a transistor PT1, and a capacitor C1;

[0018] Wherein, the first end of the resistor R1 is connected to the positive electrode of the power supply and the first end of the resistor R2;

[0019] The second end of the resistor R2 is connected to the anode of the diode D1;

[0020] The cathode of the diode D1 is connected to the second end of the transistor PT1, and both are grounded;

[0021] A first end of the transistor PT1 is connected to a second end of the resistor R1, a first end of the capacitor C1 and a first end of the resistor R6;

[0022] The second terminal of the capacitor C1 is grounded.

[0023] Furthermore, the diode D1 and the transistor PT1 are installed in a facing type according to the water tank or pipeline structure.

[0024] Further, the low-order circuit includes: a resistor R8, a resistor R9, a diode D2, a transistor PT2, and a capacitor C4;

[0025] Wherein, the first end of the resistor R8 is connected to the positive electrode of the power supply and the first end of the resistor R9;

[0026] The second end of the resistor R9 is connected to the anode of the diode D2;

[0027] The cathode of the diode D2 is connected to the second end of the transistor PT2, and both are grounded;

[0028] A first end of the transistor PT2 is connected to a second end of the resistor R8, a first end of the capacitor C4 and a first end of the resistor R10;

[0029] A second terminal of the capacitor C4 is grounded.

[0030] Furthermore, the diode D2 and the transistor PT2 are installed in a facing type according to the water tank or pipeline structure.

[0031] Compared with the prior art, the beneficial effects achieved by the utility model are as follows: the utility model discloses a photoelectric zero-contact liquid level detection circuit, the liquid level detection circuit consists of an infrared transmitting and receiving circuit and a comparison circuit, the infrared transmitting and receiving circuit and the comparison circuit are linearly connected, and the infrared transmitting and receiving circuit is divided into a high-order circuit and a low-order circuit; by comparing the voltage value at the connection between the infrared transmitting and receiving circuit and the comparison circuit with the reference voltage value, the level of the output end of the chip U1 is obtained, and then the liquid level is judged; the utility model adopts a non-contact photoelectric method to realize liquid level detection, and the liquid level can be detected without contacting the liquid, thereby avoiding the problems of metal probe polarization corrosion, liquid electrolytic deterioration, large structural space requirements, unsanitary, etc. generated by the contact type. The liquid level sensor made of the non-contact liquid level detection circuit has the characteristics of low cost, high precision, small size, and strong reliability, and can be applied to home appliances, medical treatment, industry and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0033] Figure 1 The utility model is a schematic diagram of the structure of a photoelectric zero-contact liquid level detection circuit. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] See also Figure 1 The utility model provides a technical solution: a photoelectric zero-contact liquid level detection circuit, and a corresponding photoelectric zero-contact liquid level detection circuit has a structural schematic diagram as shown in FIG. Figure 1 shown.

[0036] The liquid level detection circuit of the utility model is composed of an infrared transmitting and receiving circuit and a comparison circuit. The infrared transmitting and receiving circuit and the comparison circuit are electrically connected, and the infrared transmitting and receiving circuit is divided into a high-level circuit and a low-level circuit. The high-level circuit and the low-level circuit are divided according to the height of the liquid water level, and the high-level circuit is placed at the highest position that the liquid can accommodate, and the low-level circuit is placed at the lowest position that the liquid can accommodate.

[0037] Please see attached Figure 1The high-order circuit includes the following components: resistor R1, resistor R2, diode D1, transistor PT1, capacitor C1, the resistance of resistor R1 is 1KΩ, the resistance of resistor R2 is 200Ω, and the capacity of capacitor C1 is 1uF; the low-order circuit includes the following components: resistor R8, resistor R9, diode D2, transistor PT2, capacitor C4, the resistance of resistor R8 is 1KΩ, the resistance of resistor R9 is 200Ω, and the capacity of capacitor C4 is 1uF; the comparison circuit includes the following components Parts: resistor R3, capacitor C3, capacitor C2, resistor R4, resistor R5, chip U1, resistor R6, resistor R7, resistor R10, the resistance of resistor R3 is 10KΩ, the capacity of capacitor C3 is 10uF, the capacity of capacitor C2 is 100nF, the resistance of resistor R4 is 10KΩ, the resistance of resistor R5 is 100KΩ, the chip U1 model is LM393, the resistance of resistor R6 is 1KΩ, the resistance of resistor R7 is 100KΩ, the resistance of resistor R10 is 1KΩ.

[0038] Taking the high-level circuit as an example, the high-level circuit includes an infrared light-emitting tube and an infrared receiving tube. The infrared light-emitting tube is a diode D1, and the infrared receiving tube is a transistor PT1. The infrared light-emitting tube and the infrared receiving tube are installed in a counter-radiation type according to the water tank or pipeline structure. The working principle of the liquid level sensor composed of the high-level circuit and the comparison circuit is:

[0039] After the high-order circuit and the comparison circuit are powered on, the diode D1 emits infrared light with a wavelength of 940nm to the transistor PT1. The presence or absence of liquid between the diode D1 and the transistor PT1 will cause the infrared light intensity received by the transistor PT1 to be different. The different infrared light intensity received by the transistor PT1 will cause different currents to be generated at the connection between the high-order circuit and the comparison circuit, thereby causing the voltage value V1_HIGH between the resistor R1 and the transistor PT1 to be different.

[0040] The voltage value V1_HIGH obtained above is input into the comparison circuit, and the voltage value V1_HIGH is compared with the reference voltage value VREF, and the reference voltage value is adjusted between 0.5V-2V according to the actual situation. The chip LM393 is a dual voltage comparator, which compares the voltage at the same direction end (pin 3 or pin 5) with the voltage at the reverse end (pin 2 or pin 6) to determine whether the output end is high or low. In this embodiment, if the voltage value V1_HIGH is higher than the reference voltage value, the output pin OUT1 is high; if the voltage value V1_HIGH is lower than the reference voltage value, the output pin OUT1 is low.

[0041] The liquid level is determined based on the output level, and further whether automatic liquid replenishment or early warning is required.

[0042] The low-order circuit is the same as the high-order circuit mentioned above. It should be noted that if the product MCU has an ADC analog-to-digital conversion function, the dual voltage comparator LM393 can be omitted, and the reference voltage VREF can be connected to the analog-to-digital converter ADC input to save hardware costs through software judgment.

[0043] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0044] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A photoelectric zero-contact liquid level detection circuit, characterized in that: The liquid level detection circuit is composed of an infrared transmitting and receiving circuit and a comparison circuit. The infrared transmitting and receiving circuit and the comparison circuit are electrically connected. The infrared transmitting and receiving circuit is divided into a high-order circuit and a low-order circuit.

2. The photoelectric zero-contact liquid level detection circuit according to claim 1, characterized in that: The comparison circuit includes: a resistor R3, a capacitor C3, a capacitor C2, a resistor R4, a resistor R5, a chip U1, a resistor R6, a resistor R7, and a resistor R10; Wherein, the first end of the chip U1 is connected to the second end of the resistor R3 and the first end of the resistor R5; The second terminal of the chip U1 is connected to the reference voltage terminal; The third end of the chip U1 is connected to the second end of the resistor R5 and the second end of the resistor R6; The fourth terminal of the chip U1 is grounded; The fifth end of the chip U1 is connected to the second end of the resistor R7 and the second end of the resistor R10; The sixth terminal of the chip U1 is connected to the reference voltage terminal; The seventh terminal of the chip U1 is connected to the second terminal of the resistor R4 and the first terminal of the resistor R7; The eighth end of the chip U1 is connected to the first end of the resistor R3, the positive electrode of the power supply, the first end of the capacitor C3, the first end of the capacitor C2 and the first end of the resistor R4; The second end of the capacitor C3 is connected to the second end of the capacitor C2 and both are grounded.

3. The photoelectric zero-contact liquid level detection circuit according to claim 2, characterized in that: The model of the chip U1 is LM393.

4. The photoelectric zero-contact liquid level detection circuit according to claim 2, characterized in that: The high-order circuit includes: a resistor R1, a resistor R2, a diode D1, a transistor PT1, and a capacitor C1; Wherein, the first end of the resistor R1 is connected to the positive electrode of the power supply and the first end of the resistor R2; The second end of the resistor R2 is connected to the anode of the diode D1; The cathode of the diode D1 is connected to the second end of the transistor PT1, and both are grounded; The first end of the transistor PT1 is connected to the second end of the resistor R1, the first end of the capacitor C1 and the first end of the resistor R6; The second end of the capacitor C1 is grounded.

5. The photoelectric zero-contact liquid level detection circuit according to claim 4, characterized in that: The diode D1 and the transistor PT1 are installed in a facing type according to the water tank or pipeline structure.

6. The photoelectric zero-contact liquid level detection circuit according to claim 2, characterized in that: The low-order circuit includes: a resistor R8, a resistor R9, a diode D2, a transistor PT2, and a capacitor C4; Wherein, the first end of the resistor R8 is connected to the positive electrode of the power supply and the first end of the resistor R9; The second end of the resistor R9 is connected to the anode of the diode D2; The cathode of the diode D2 is connected to the second end of the transistor PT2, and both are grounded; The first end of the transistor PT2 is connected to the second end of the resistor R8, the first end of the capacitor C4 and the first end of the resistor R10; The second terminal of the capacitor C4 is grounded.

7. The photoelectric zero-contact liquid level detection circuit according to claim 6, characterized in that: The diode D2 and the transistor PT2 are installed in a facing type according to the water tank or pipeline structure.

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