Capacitive sensor with adjustable knob

Abstract

The utility model discloses a knob-adjustable capacitive sensor, which belongs to the technical field of instruments and meters and comprises a front cover, a shell and a circuit unit. The front cover is inserted into the shell, a containing groove is formed in the right side of the front cover, and a mounting groove is formed in the left side of the shell; the circuit unit is mounted in the accommodating groove and the mounting groove; the circuit unit comprises an indicating lamp, an adjustable potentiometer, a PCB (Printed Circuit Board) and an induction surface, the adjustable potentiometer and the adjustable potentiometer used for indicating states are fixedly mounted at the end part of the PCB, and the indicating lamp and the adjustable potentiometer are positioned in the accommodating groove. By means of the mode, the sealing performance of the installation groove is improved, and therefore protection on the PCB is improved; the output state is indicated by controlling the change of the color through the indicator lamp, so that an operator can observe more intuitively; the sensitivity is controlled by adjusting a knob on the adjustable potentiometer, so that the sensor can detect various detected objects.

Description

Technical Field

[0001] The utility model relates to the technical field of instruments and meters, in particular to a knob-adjustable capacitance sensor. Background Art

[0002] Generally, capacitive proximity switches can only operate within the industrial temperature range of -25°C to 70°C. When the temperature rises above 70°C, the amplitude of the RC oscillation changes, and the sensing distance decreases accordingly. In some cases, when using a capacitive sensor (switch) in learning mode, the response is more complicated. When it is limited to a single object, setting a corresponding distance for monitoring is simpler and faster. At the same time, existing capacitive sensors (switches) mostly work in the container to detect the internal environment. When the warehouse is full during production, or the object overflows or flows through the sensing surface, the alarm cannot be triggered in time, and the observation is not intuitive enough, which can cause losses and accidents in the production process.

[0003] For example, Chinese patent 202123011832.8 discloses a leakage type liquid level sensor, which is equipped with an inductive capacitor, an oscillation circuit, an F / V conversion circuit, a signal processing unit, an output unit, a potentiometer, an indication unit, and a power supply circuit, so that it can work stably in a high temperature environment and has a wide operating temperature range, thereby greatly improving the detection stability; at the same time, when the leakage type liquid level sensor is set on the top of the silo or the side wall of the silo, a support base is provided at the bottom of its lower cover, so that a certain distance is maintained between the sensing surface and the silo to be measured; when the material to be measured flows through the distance, an output signal will be generated in time; thus, when the silo is full or the material overflows, the material level or liquid level can be accurately monitored to enable timely alarm.

[0004] However, the circuit unit, indicating unit and potentiometer of the sensor are located in the cavity formed by the upper cover and the lower cover, and the potentiometer needs to pass through the upper cover, thereby reducing the sealing protection of the circuit unit.

[0005] Based on this, the present invention designs a knob-adjustable capacitance sensor to solve the above problems. Utility Model Content

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a knob-adjustable capacitance sensor.

[0007] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A knob-adjustable capacitance sensor comprising a front cover, a housing, and a circuit unit;

[0009] The front cover and the outer shell are plugged together, a receiving slot is provided on the right side of the front cover, and a mounting slot is provided on the left side of the outer shell; the circuit unit is installed in the receiving slot and the mounting slot; the circuit unit includes an indicator light, an adjustable potentiometer, a PCB board, and a sensing surface, the sensing surface is fixedly mounted on the lower side of the PCB board, and the PCB board is fixedly mounted in the mounting slot; an adjustable potentiometer is fixedly mounted on the end of the PCB board, and the indicator light and the adjustable potentiometer are located in the receiving slot;

[0010] The PCB board is provided with an inductive capacitor, an oscillation circuit, an F / V conversion circuit, a signal processing unit, an output unit, a potentiometer, an indicating unit, and a power supply circuit; the inductive capacitor, the oscillation circuit, the F / V conversion circuit, the signal processing unit, and the output unit are electrically connected in sequence; the output end of the potentiometer is electrically connected to the signal processing unit, and the input end of the indicating unit is electrically connected to the signal processing unit.

[0011] Furthermore, the sensing surface is in close contact with the bottom of the installation groove.

[0012] Furthermore, the indicator light is configured as an LED indicator light.

[0013] Furthermore, a step is provided on the right outer wall of the front cover, and the step is plugged into the installation groove.

[0014] Furthermore, the inductive capacitor is configured as a double-sided special-shaped shielded circuit board; the double-sided shielded circuit board is trapezoidal in shape, and is more closely connected to the front cover and the housing.

[0015] Furthermore, the adjustable potentiometer is configured as a knob-type adjustable capacitor, and the resistance of the adjustable potentiometer is configured as a multi-turn potentiometer parallel resistor.

[0016] Furthermore, a through hole is provided on the left side of the front cover, and the knob of the adjustable potentiometer passes through the through hole and out of the front cover.

[0017] Furthermore, an observation window is provided on the upper side of the front cover for convenient observation of the status of the indicator light.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. The arrangement of the step and the mounting groove facilitates the insertion of the front cover into the through hole. A potting compound for increasing the sealing performance is arranged between the step and the mounting groove, thereby increasing the overall sealing performance. A mounting groove is provided in the housing, the PCB board is located in the mounting groove, the only opening of the mounting groove is plugged into the step, and potting compound is arranged between the only opening of the mounting groove and the step, thereby increasing the sealing performance of the mounting groove and enhancing the protection of the PCB board.

[0019] 2. By adding a support frame or support block, a certain distance can be created between the sensing surface and the measured bin. When the measured material flows through the distance, an output signal will be generated in time. When the bin is full or the material overflows, the material level or liquid level can be accurately monitored so that an alarm can be issued in time, thereby effectively reducing losses in the production process. The output status is indicated by the color change of the indicator light, allowing the operator to observe more intuitively.

[0020] 3. By adjusting the knob on the adjustable potentiometer, the voltage signal size of the in-phase terminal is changed and the sensitivity is controlled, so that the product can detect a variety of objects to be detected;

[0021] 4. The double-sided special-shaped shielded circuit board has good anti-interference ability and excellent sensing ability, which enables the capacitive sensor to operate at high temperature;

[0022] 5. This sensor has strong anti-interference ability, simple structure, low cost, easy maintenance, small size and beautiful appearance, and can measure objects with various dielectric constants. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0024] Figure 1 This is a schematic diagram of the structure of the knob-adjustable capacitance sensor of the utility model;

[0025] Figure 2 Schematic diagram of PCB board and its connection structure;

[0026] Figure 3 This is a circuit block diagram of the knob-adjustable capacitance sensor of the present utility model.

[0027] The numbers in the figure represent:

[0028] 1. Front cover; 12. Through hole; 13. Observation window; 14. Step; 2. Housing; 3. Circuit unit; 31. Indicator light; 32. Adjustable potentiometer; 33. PCB board; 34. Sensing surface. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] Example 1: In some embodiments, please refer to the accompanying drawings of the specification. Figure 1 and Figure 2 , a knob-adjustable capacitance sensor, comprising a front cover 1, a housing 2 and a circuit unit 3;

[0031] The front cover 1 and the housing 2 are plugged together. A receiving slot is defined on the right side of the front cover 1, and a mounting slot is defined on the left side of the housing 2. The circuit unit 3 is mounted in the receiving slot and the mounting slot. The circuit unit 3 includes an indicator light 31, an adjustable potentiometer 32, a PCB board 33, and a sensing surface 34. The sensing surface 34 is fixedly mounted on the lower side of the PCB board 33, which is fixedly mounted in the mounting slot. An adjustable potentiometer 32 is fixedly mounted at the end of the PCB board 33. The indicator light 31 and the adjustable potentiometer 32 are located in the receiving slot.

[0032] The PCB board 33 is provided with an inductive capacitor, an oscillation circuit, an F / V conversion circuit, a signal processing unit, an output unit, a potentiometer, an indicating unit, and a power supply circuit; the inductive capacitor, the oscillation circuit, the F / V conversion circuit, the signal processing unit, and the output unit are electrically connected in sequence; the output end of the potentiometer is electrically connected to the signal processing unit, and the input end of the indicating unit is electrically connected to the signal processing unit; the oscillation circuit uses a crystal oscillator.

[0033] The sensing surface 34 is in close contact with the bottom of the installation groove.

[0034] The indicator light 31 is configured as an LED indicator light.

[0035] The right outer wall of the front cover 1 is provided with a step 14 , which is plugged into the mounting groove.

[0036] A potting compound is provided between the step 14 and the mounting groove to increase the sealing performance.

[0037] The inductive capacitor is configured as a double-sided shielded circuit board, which is trapezoidal in shape and is more closely connected to the front cover 1 and the housing 2 .

[0038] A gap is provided between the double-sided tape shielding circuit board and the housing 2 for potting glue to increase the sealing performance.

[0039] The adjustable potentiometer 32 is configured as a knob-type adjustable capacitor, and the resistance of the adjustable potentiometer 32 is configured as a multi-turn potentiometer parallel resistor.

[0040] A through hole 12 is provided on the left side of the front cover 1 , and the knob of the adjustable potentiometer 32 passes through the through hole 12 and out of the front cover 1 .

[0041] An observation window 13 is provided on the upper side of the front cover 1 for conveniently observing the status of the indicator light 31 .

[0042] Among them, the oscillation circuit adopts a crystal oscillator with high precision, low temperature drift and good temperature stability. It can work stably in a high temperature environment and has a wide operating temperature range, which can greatly improve the detection stability.

[0043] In this embodiment, when the knob-adjustable capacitive sensor is operating normally, the provision of the step 14 and the mounting groove facilitates the insertion of the front cover 1 into the through-hole 12. A potting compound is provided between the step 14 and the mounting groove to enhance sealing, thereby enhancing overall sealing. Furthermore, a mounting groove is defined within the housing 2, and the PCB board 33 is positioned within the mounting groove. The only opening of the mounting groove is plugged into the step 14, and potting compound is provided between the only opening of the mounting groove and the step 14, thereby enhancing sealing of the mounting groove and thus providing enhanced protection for the PCB board 33.

[0044] By adding a support frame or support block, a certain distance can be created between the sensing surface 34 and the measured bin body; when the measured material flows through the distance, an output signal will be generated in a timely manner; when the bin is full or the material overflows, the material level or liquid level can be accurately monitored so that an alarm can be issued in time, thereby effectively reducing losses in the production process; at the same time, the output status can be indicated by controlling the color change of the indicator light 31, so that the operator can observe more intuitively.

[0045] By adjusting the knob on the adjustable potentiometer 32, the voltage signal at the in-phase end is changed and the sensitivity is controlled, so that the product can detect objects with various dielectric constants.

[0046] The double-sided special-shaped shielded circuit board has good anti-interference ability and excellent sensing ability, which enables the capacitive sensor to operate at high temperature;

[0047] This sensor has strong anti-interference ability, simple structure, low cost, easy maintenance, small size and beautiful appearance, and can measure objects with various dielectric constants.

[0048] Embodiment 2: In some embodiments, as Figure 1-Figure 3 As shown in FIG. 1 , as a preferred embodiment of the present invention, the voltage-stabilized power supply portion includes an 18V voltage-stabilizing tube and a triode electrically connected to each other, and electrically connected to the power chip;

[0049] A high-capacity tantalum capacitor is connected in parallel to the output pin of the power chip to provide voltage stabilization and filtering, ensuring a stable +5V power supply. In actual applications, the anti-reverse polarity design effectively prevents short circuits caused by reverse polarity, protecting the circuit and making the power supply more stable and reliable.

[0050] The power supply part adopts a voltage stabilizing circuit design that combines an 18V voltage regulator tube and a triode.

[0051] The F / V conversion circuit uses a multiplexer chip with a crystal oscillator as the signal source.

[0052] The signal processing unit includes a hysteresis comparator circuit that uses a single-supply, high-bandwidth, rail-to-rail operational amplifier.

[0053] The signal processing unit is configured as a single-supply, high-bandwidth, rail-to-rail operational amplifier.

[0054] The output unit includes an output control element and a resettable fuse; the output control element adopts a triode; and the resettable fuse is arranged at the output end of the output unit.

[0055] The front cover 1 and the outer shell 2 are made of one of polybutylene terephthalate, polyetheretherketone, polyimide, polyphenylene sulfide, polyetherimide, polyethersulfone and polycarbonate to improve their mechanical properties.

[0056] In practical applications, the signal processing unit is configured as a single-supply, high-bandwidth, rail-to-rail operational amplifier. Its working principle is as follows:

[0057] Signal input and amplification: The F / V conversion circuit sends the signal to the non-inverting terminal of the operational amplifier, and the inverting terminal is connected to the fixed reference voltage pin to form a hysteresis comparator circuit;

[0058] Potentiometer control: The voltage signal at the in-phase end of the F / V signal processing unit is controlled by the potentiometer. Adjusting the potentiometer knob can change the size of the voltage signal at the in-phase end, thereby controlling the sensitivity.

[0059] Comparison and output: Compare the voltage at the in-phase terminal with the voltage at the inverting terminal, and output a switching signal to the output unit based on the comparison result.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A knob-adjustable capacitance sensor comprising a front cover (1), a housing (2), and a circuit unit (3), characterized in that: The front cover (1) and the housing (2) are plugged together, a receiving slot is provided on the right side of the front cover (1), and a mounting slot is provided on the left side of the housing (2); the circuit unit (3) is installed in the receiving slot and the mounting slot; the circuit unit (3) comprises an indicator light (31), an adjustable potentiometer (32), a PCB board (33) and a sensing surface (34); the sensing surface (34) is fixedly installed on the lower side of the PCB board (33), and the PCB board (33) is fixedly installed in the mounting slot; an adjustable potentiometer (32) is fixedly installed at the end of the PCB board (33), and the indicator light (31) and the adjustable potentiometer (32) are located in the receiving slot; The PCB board (33) is provided with an inductive capacitor, an oscillating circuit, an F / V conversion circuit, a signal processing unit, an output unit, a potentiometer, an indicating unit, and a power supply circuit; the inductive capacitor, the oscillating circuit, the F / V conversion circuit, the signal processing unit, and the output unit are electrically connected in sequence; the output end of the potentiometer is electrically connected to the signal processing unit, and the input end of the indicating unit is electrically connected to the signal processing unit.

2. The knob-adjustable capacitance sensor according to claim 1, characterized in that: The sensing surface (34) is in close contact with the bottom of the installation groove.

3. The knob-adjustable capacitance sensor according to claim 2, characterized in that: The indicator light (31) is configured as an LED indicator light.

4. The knob-adjustable capacitance sensor according to claim 3, characterized in that: The right outer wall of the front cover (1) is provided with a step (14), and the step (14) is plugged into the installation slot.

5. The knob-adjustable capacitance sensor according to claim 4, characterized in that: The inductive capacitor is configured as a double-sided shielded circuit board; the shape of the double-sided shielded circuit board is configured as a trapezoid that is more closely fitted to the front cover (1) and the housing (2).

6. The knob-adjustable capacitance sensor according to claim 5, characterized in that: The adjustable potentiometer (32) is configured as a knob-type adjustable capacitor, and the resistance of the adjustable potentiometer (32) is configured as a multi-turn potentiometer parallel resistor.

7. The knob-adjustable capacitance sensor according to claim 6, characterized in that: A through hole (12) is provided on the left side of the front cover (1), and the knob of the adjustable potentiometer (32) passes through the through hole (12) and out of the front cover (1).

8. The knob-adjustable capacitance sensor according to claim 7, characterized in that: An observation window (13) is provided on the upper side of the front cover (1) for conveniently observing the status of the indicator light (31).

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