Sensor capable of resisting temperature change and ensuring stable detection precision of turbidity of liquid

Abstract

The technical scheme of the utility model discloses a sensor capable of resisting temperature change and ensuring stable liquid turbidity detection precision. The sensor comprises a current-limiting resistor, a negative temperature coefficient thermistor, a transmitting end, a receiving end, a connector and a PCB (Printed Circuit Board) substrate, the current-limiting resistor is connected in series with the transmitting terminal, and the negative temperature coefficient thermistor is connected in parallel with the current-limiting resistor to form a transmitting terminal current loop; the transmitting end transmits a light source, and the receiving end induces the light source transmitted by the transmitting end to generate similar resistance to form a complete circuit loop with an external test circuit connected with the receiving end; the transmitting end and the receiving end are connected with an external voltage-stabilized power supply through a connector, and the current-limiting resistor, the negative temperature coefficient thermistor, the transmitting end, the receiving end and the connector are mounted on the PCB substrate. The current-limiting resistor and the negative temperature coefficient thermistor are arranged in parallel, so that the resistance influence of the temperature on the transmitting end loop is counteracted, the stability of the overall photoelectric conversion efficiency is ensured, and the working stability of the sensor is improved.

Description

Technical Field

[0001] This invention belongs to the field of turbidity detection technology, specifically relating to a sensor that resists temperature changes and ensures stable accuracy in liquid turbidity detection. Background Technology

[0002] Liquid turbidity detection is typically achieved using turbidity sensors, which are widely used in household washing appliances such as washing machines and dishwashers. With rising living standards, the market for liquid turbidity detection continues to grow, and the quality and functionality requirements for household washing appliances are also increasing, leading to higher demands on their components. Existing turbidity sensors are prone to instability in photoelectric conversion efficiency when the ambient temperature changes during washing, especially when the liquid needs to be heated. This can cause overall circuit instability, unstable current and output voltage, resulting in inaccurate data transmission and an inability to accurately determine the turbidity state of the liquid under the given conditions, thus affecting the washing results.

[0003] Patent CN 115406867 A discloses a turbidity sensor with integrated temperature detection, including a transparent housing assembly comprising a transparent outer shell, a transparent inner shell, and an O-ring seal A; a PCB board assembly inserted into the transparent housing assembly, comprising a PCB board, a light tube support, an infrared emitting tube, an infrared receiving tube, and a thermistor NTC; the O-ring seal B is assembled on the outside of the transparent housing assembly, and a base covers the upper end of the transparent housing assembly; the turbidity of the liquid to be tested is detected by setting a transparent inner shell with lenses and prisms, an infrared emitting tube, and an infrared receiving tube. The thermistor NTC only detects temperature changes in the water; when the temperature of the liquid to be tested changes, its influence on the PCB board cannot be eliminated, affecting the accuracy of the turbidity detection. Therefore, there is a need to develop a sensor that can resist the instability of photoelectric conversion efficiency caused by changes in ambient temperature and can accurately determine the turbidity state of the liquid to be tested. Utility Model Content

[0004] To address the existing technical problems, this utility model provides a sensor that resists temperature changes and ensures stable accuracy in liquid turbidity detection. By using a current-limiting resistor and a negative temperature coefficient thermistor in parallel, the influence of temperature on the resistance of the transmitting circuit is offset, ensuring stable overall photoelectric conversion efficiency and improving the sensor's operational stability.

[0005] The technical solution of this utility model is: a sensor that resists temperature changes and ensures stable accuracy in liquid turbidity detection, comprising a current-limiting resistor, a negative temperature coefficient thermistor, a transmitter, a receiver, a connector, and a PCB substrate; the current-limiting resistor is connected in series with the transmitter, and the negative temperature coefficient thermistor is connected in parallel with the current-limiting resistor to form a current loop for the transmitter; the transmitter emits a light source, and the receiver senses the infrared light source emitted by the transmitter, generating a resistor-like structure that forms a complete circuit loop with the connected external test circuit; the transmitter and receiver are connected to an external regulated power supply through the connector, and the current-limiting resistor, negative temperature coefficient thermistor, transmitter, receiver, and connector are mounted on the PCB substrate.

[0006] Furthermore, the external test circuit connected to the receiver is used to detect and output the voltage divider across the test resistor connected in series with the receiver, thereby realizing the conversion from light energy to electrical energy.

[0007] Furthermore, the connector includes terminals A-1, A-2, and A-3. Terminal A-1 is connected to an external regulated power supply, terminal A-2 is grounded, and terminal A-3 is connected to the output of an external test circuit.

[0008] Furthermore, the transmitting end is provided with terminals B-1 and B-2, the current-limiting resistor is provided with terminals C-1 and C-2, and the negative temperature coefficient thermistor is provided with terminals D-1 and D-2; terminal B-2 of the transmitting end is connected to terminal C-1 of the current-limiting resistor, terminal B-1 of the transmitting end is connected to terminal A-1 of the connector, terminal C-2 of the current-limiting resistor is connected to terminal A-2 of the connector, terminal C-1 of the current-limiting resistor is connected to terminal D-1 of the negative temperature coefficient thermistor, and terminal D-2 of the negative temperature coefficient thermistor is connected to terminal C-2 of the current-limiting resistor.

[0009] Furthermore, the receiving end is provided with E-1 terminal and E-2 terminal, the E-1 terminal of the receiving end is connected to the A-1 terminal of the connector, and the E-2 terminal of the receiving end is connected to the A-3 terminal of the connector.

[0010] Furthermore, the sensor that resists temperature changes and ensures stable accuracy in liquid turbidity detection also includes a housing and a base. The housing has an internal hollow structure, and the opening of the housing is mounted on the base. The PCB substrate is mounted inside the housing.

[0011] By adopting the above technical solution, this utility model solves the problem of unstable transmitter circuit resistance caused by the drift of the transmitter current-limiting resistor due to temperature changes. By using the negative temperature coefficient thermistor to offset the positive change of current in the current-limiting resistor with temperature changes, the influence of temperature on the resistance of the entire current-limiting circuit is eliminated, ensuring that the intensity of the emitted light source at the transmitter is not affected by temperature. This ensures that the intensity of the received light source at the receiver is not affected by temperature, maintains photoelectric conversion efficiency, keeps the circuit board performance stable, ensures stable circuit voltage output, and thus can accurately determine the turbidity of the liquid, improves the accuracy of the sensor, and ensures the stability of the sensor when the ambient temperature changes. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model;

[0013] Figure 2 This is a schematic diagram of the PCB substrate of this utility model;

[0014] Figure 3 This is the circuit diagram of this utility model;

[0015] Figure 4 This is a schematic diagram of the structure of the shell and base of this utility model.

[0016] In the diagram, 1 is the connector; 2 is the transmitter; 3 is the current-limiting resistor; 4 is the negative temperature coefficient thermistor; 5 is the receiver; 6 is the PCB substrate; 7 is the housing; 8 is the base; 11 is the A-1 terminal; 12 is the A-2 terminal; 13 is the A-3 terminal; 21 is the B-1 terminal; 22 is the B-2 terminal; 31 is the C-1 terminal; 32 is the C-2 terminal; 41 is the D-1 terminal; 42 is the D-2 terminal; 51 is the E-1 terminal; and 52 is the E-2 terminal. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Example

[0018] Reference Figure 1-4A sensor that resists temperature changes and ensures stable accuracy in liquid turbidity detection includes a current-limiting resistor 3, a negative temperature coefficient thermistor 4, a transmitter 2, a receiver 5, a connector 1, and a PCB substrate 6. The current-limiting resistor 3 is connected in series with the transmitter 2, and the negative temperature coefficient thermistor 4 is connected in parallel with the current-limiting resistor 3, forming a current loop for the transmitter. The transmitter 2 emits a light source, and the receiver 5 senses the infrared light source emitted by the transmitter 2, generating a resistor-like structure that forms a complete circuit loop with the connected external test circuit. The transmitter 2 and the receiver 5 are connected to an external regulated power supply through the connector 1. The current-limiting resistor 3, the negative temperature coefficient thermistor 4, the transmitter 2, the receiver 5, and the connector 1 are mounted on the PCB substrate 6.

[0019] In this embodiment 1, transmitter 2 is an IR transmitter, receiver 5 is a PT receiver, and the external regulated power supply is a DC 5V regulated power supply. Connector 1, current-limiting resistor 3, negative temperature coefficient thermistor 4, transmitter 2, and receiver 5 are soldered onto PCB substrate 6. The external test circuit is existing technology.

[0020] Furthermore, the external test circuit connected to the receiver 5 is used to detect and output the voltage divider across the test resistor connected in series with the receiver, thereby realizing the conversion from light energy to electrical energy.

[0021] In this embodiment 1, the external test circuit (such as...) Figure 3 The left side of the middle section (pins 1, 2, and 3) detects and outputs the voltage divider across the test resistor RA connected in series with the receiver 5, thus realizing the conversion from light energy to electrical energy.

[0022] Furthermore, the connector 1 includes an A-1 terminal 11, an A-2 terminal 12, and an A-3 terminal 13. The A-1 terminal 11 is connected to an external regulated power supply (in this embodiment 1, a DC 5V regulated power supply), the A-2 terminal 12 is grounded, and the A-3 terminal 13 is connected to the output terminal of an external test circuit (such as...). Figure 3 As shown, pin 3 on the left and its output are the same as the output of the test resistor RA circuit.

[0023] Furthermore, the transmitter 2 is provided with terminals B-1 21 and B-2 22, the current-limiting resistor 3 is provided with terminals C-1 31 and C-2 32, and the negative temperature coefficient thermistor 4 is provided with terminals D-1 41 and D-2 42; terminal B-2 22 of the transmitter 2 is connected to terminal C-1 31 of the current-limiting resistor 3, terminal B-1 21 of the transmitter 2 is connected to terminal A-1 11 of the connector 1, terminal C-2 32 of the current-limiting resistor 3 is connected to terminal A-2 12 of the connector 1, terminal C-1 31 of the current-limiting resistor 3 is connected to terminal D-1 41 of the negative temperature coefficient thermistor 4, and terminal D-2 42 of the negative temperature coefficient thermistor 4 is connected to terminal C-2 32 of the current-limiting resistor 3.

[0024] Terminal 21 (B-1) of transmitter 2 is connected to terminal 11 (A-1) of connector 1, enabling an external DC 5V regulated power supply to be connected to terminal 21 (B-1) of transmitter 2. Terminal 32 (C-2) of current-limiting resistor 3 is connected to terminal 12 (A-2) of connector 1, enabling terminal 32 (C-2) of current-limiting resistor 3 to be grounded. Terminal 31 (C-1) of current-limiting resistor 3 is connected to terminal 41 (D-1) of negative temperature coefficient thermistor 4, and terminal 42 (D-2) of negative temperature coefficient thermistor 4 is connected to terminal 32 (C-2) of current-limiting resistor 3, thus completing the parallel circuit of negative temperature coefficient thermistor 4 and current-limiting resistor 3, ultimately completing the transmitter circuit.

[0025] Furthermore, the receiving end 5 is provided with an E-1 terminal 51 and an E-2 terminal 52. The E-1 terminal 51 of the receiving end 5 is connected to the A-1 terminal 11 of the connector 1, and the E-2 terminal 52 of the receiving end 5 is connected to the A-3 terminal 13 of the connector 1.

[0026] The E-1 terminal 51 of receiver 5 is connected to the A-1 terminal 11 of connector 1, so that the E-1 terminal of receiver 5 can be connected to an external DC 5V regulated power supply; the E-2 terminal of receiver 5 is connected to the A-3 terminal of connector, and the A-3 terminal of connector is connected to the output terminal of external test circuit, so that receiver 5 generates a resistor-like structure after sensing the light source emitted by transmitter 2, and forms a complete circuit loop with the connected external test circuit.

[0027] Furthermore, the sensor that resists temperature changes and ensures stable accuracy in liquid turbidity detection also includes a housing 7 and a base 8. The housing 7 has an internal hollow structure, and the opening of the housing 7 is mounted on the base 8. The PCB substrate 6 is mounted inside the housing 7.

[0028] This invention, a sensor designed to resist temperature changes and ensure stable accuracy in liquid turbidity detection, operates by changing the ambient temperature of the sensor. The current-limiting resistor 3 generates a positive change in current with temperature change, while the negative temperature coefficient thermistor 4 generates a negative change in resistance with temperature change. This counteracts the positive change in current of the current-limiting resistor 3, ensuring that the total current-limiting resistance connected in series with the transmitter 2 remains constant under different temperatures. This eliminates the influence of temperature on the resistance of the entire current-limiting circuit, ensuring that the transmitter circuit resistance remains stable under different temperatures. The transmitter 2 stably emits the light source, and the receiver 5 stably receives the light source, generating a resistor-like structure that connects to an external DC 5V regulated power supply and is connected in series with an external test circuit to form a loop. This ultimately achieves a stable output of the voltage across the test resistor RA in the external test circuit, ensuring that the voltage across the test resistor RA does not fluctuate or become irregular due to temperature changes, thus enabling accurate measurement of the current liquid turbidity state.

Claims

1. A sensor that resists temperature changes and ensures stable accuracy in liquid turbidity detection, characterized in that: It includes a current-limiting resistor (3), a negative temperature coefficient thermistor (4), a transmitter (2), a receiver (5), a connector (1), and a PCB substrate (6); the current-limiting resistor (3) is connected in series with the transmitter (2), and the negative temperature coefficient thermistor (4) is connected in parallel with the current-limiting resistor (3) to form a transmitter current loop; the transmitter (2) emits a light source, and the receiver (5) senses the infrared light source emitted by the transmitter (2) to generate a resistor-like circuit that forms a complete circuit loop with the connected external test circuit; the transmitter (2) and the receiver (5) are connected to an external regulated power supply through the connector (1), and the current-limiting resistor (3), the negative temperature coefficient thermistor (4), the transmitter (2), the receiver (5), and the connector (1) are mounted on the PCB substrate (6).

2. The sensor according to claim 1, which resists temperature changes and ensures stable accuracy in liquid turbidity detection, is characterized in that: The external test circuit connected to the receiver (5) detects and outputs the voltage divider across the test resistor connected in series with the receiver, thereby realizing the conversion from light energy to electrical energy.

3. The sensor according to claim 1, which resists temperature changes and ensures stable accuracy in liquid turbidity detection, is characterized in that: The connector (1) includes an A-1 terminal (11), an A-2 terminal (12) and an A-3 terminal (13). The A-1 terminal (11) is connected to an external regulated power supply, the A-2 terminal (12) is connected to ground, and the A-3 terminal (13) is connected to the output of an external test circuit.

4. The sensor according to claim 3, which resists temperature changes and ensures stable accuracy in liquid turbidity detection, is characterized in that: The transmitter (2) is provided with terminals B-1 (21) and B-2 (22), the current limiting resistor (3) is provided with terminals C-1 (31) and C-2 (32), and the negative temperature coefficient thermistor (4) is provided with terminals D-1 (41) and D-2 (42). The B-2 terminal (22) of the transmitter (2) is connected to the C-1 terminal (31) of the current limiting resistor (3), the B-1 terminal (21) of the transmitter (2) is connected to the A-1 terminal (11) of the connector (1), the C-2 terminal (32) of the current limiting resistor (3) is connected to the A-2 terminal (12) of the connector (1), the C-1 terminal (31) of the current limiting resistor (3) is connected to the D-1 terminal (41) of the negative temperature coefficient thermistor (4), and the D-2 terminal (42) of the negative temperature coefficient thermistor (4) is connected to the C-2 terminal (32) of the current limiting resistor (3).

5. The sensor according to claim 3, which resists temperature changes and ensures stable accuracy in liquid turbidity detection, is characterized in that: The receiver (5) is provided with an E-1 terminal (51) and an E-2 terminal (52). The E-1 terminal (51) of the receiver (5) is connected to the A-1 terminal (11) of the connector (1), and the E-2 terminal (52) of the receiver (5) is connected to the A-3 terminal (13) of the connector (1).

6. The sensor according to claim 1, which resists temperature changes and ensures stable accuracy in liquid turbidity detection, is characterized in that: The sensor that resists temperature changes and ensures stable accuracy in liquid turbidity detection also includes a housing (7) and a base (8). The housing (7) has an internal hollow structure, and the opening of the housing (7) is mounted on the base (8). The PCB substrate (6) is mounted inside the housing (7).

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