Wireless pressure sensor

Abstract

In order to solve the problem that the accuracy of a detection result of an existing wireless pressure sensor is insufficient, the utility model provides a wireless pressure sensor which comprises a button battery, a spring and a PCB (Printed Circuit Board), the button cell is electrically connected with the PCB through the spring, and the first electrode surface of the button cell is arranged opposite to the PCB; the spring is used for supporting the button cell and converting pressure acting on the button cell into expansion and contraction quantity; the PCB is integrated with a wireless communication module and a parallel resonance circuit; the wireless communication module is used for transmitting an excitation signal, receiving a resonance voltage signal and converting the resonance voltage signal into a pressure radio frequency signal; the parallel resonance circuit receives the excitation signal and generates a resonance voltage signal in real time; under the action of an excitation signal, the parallel resonance circuit and the first electrode surface form electromagnetic induction, and when the spring stretches out and draws back, a resonance voltage signal is in negative correlation with the stretching amount. By capturing the change of the resonance voltage signal and converting the resonance voltage signal into a pressure radio frequency signal, the pressure is accurately measured.

Description

TECHNICAL FIELD

[0001] The utility model relates to pressure sensor technical field especially relates to a wireless pressure sensor. BACKGROUND

[0002] In the intelligent house application, most products focus on the automatic control of intelligent household appliances, and the intelligence and comfort of intelligent furniture are relatively lagging behind. In the prior art, wireless pressure sensors are often used to assist intelligent furniture to accurately realize functions such as sensing human posture, adjusting comfort, and monitoring health indicators.

[0003] At present, most existing wireless pressure sensors use piezoelectric film or resistive film. Due to the limitations of these components in circuit applications, it is difficult for wireless pressure sensors to accurately detect pressure, and they cannot meet the comprehensive requirements of intelligent furniture for pressure detection. Therefore, developing wireless pressure sensors that can accurately detect pressure has become a technical problem that needs to be solved. SUMMARY

[0004] The utility model mainly solves the problem of insufficient accuracy of the detection results of the existing wireless pressure sensor.

[0005] To solve the above technical problems, the utility model provides a wireless pressure sensor, which comprises a button cell, a spring and a PCB board. The button cell is electrically connected to the PCB board through the spring, and its first electrode surface is arranged opposite to the PCB board. The spring is used to support the button cell and convert the pressure acting on the button cell into an extension amount, and the pressure and the extension amount are positively correlated. The PCB board is integrated with a wireless communication module and a parallel resonant circuit. The wireless communication module is used to transmit an excitation signal, receive a resonant voltage signal and convert it into a pressure radio frequency signal. The parallel resonant circuit is used to receive the excitation signal and generate the resonant voltage signal in real time. Under the action of the excitation signal, the parallel resonant circuit and the first electrode surface form electromagnetic induction, and when the spring expands and contracts, the resonant voltage signal and the extension amount are negatively correlated.

[0006] As a preferred embodiment, the parallel resonant circuit comprises a coil inductance and a capacitor connected in parallel. The coil inductance is a spiral coil printed on the PCB board. The capacitor is integrated in the PCB board.

[0007] As preferred, the wireless communication module comprises a wireless chip and a radio frequency; a PWM signal output end of the wireless chip transmits the excitation signal; an ADC channel input end of the wireless chip receives the resonance voltage signal, and an ADC channel output end of the wireless chip outputs a sampling voltage signal; wherein the wireless chip is configured to encode and convert the sampling voltage signal into the pressure radio frequency signal by querying an experience table; the radio frequency is integrated at a connection between the spring and the PCB board, and is configured to radiate the pressure radio frequency signal to space and transmit the pressure radio frequency signal through the spring.

[0008] As preferred, the button cell comprises the first electrode surface, the second electrode surface, and an insulating shell arranged at a side surface of the button cell in a circumferential ring; an area of the first electrode surface is greater than an area of the second electrode surface; the first electrode surface forms a positive electrode or a negative electrode of the button cell; the second electrode surface forms a negative electrode or a positive electrode of the button cell and is configured to form a microstrip antenna; the microstrip antenna is configured to receive the pressure radio frequency signal through the spring and communicate with an external terminal; and the insulating shell is configured to fix the spring.

[0009] As preferred, one side of the PCB board opposite to the button cell is provided with a height limiting block, a height of the height limiting block does not exceed a length of the spring, and the height limiting block is configured to prevent the button cell from directly contacting the PCB board.

[0010] As preferred, the PCB board further integrates one or more of a direct current bias circuit, a filter circuit, and a voltage dividing circuit; the direct current bias circuit is connected in series with the parallel resonance circuit and configured to provide a direct current bias voltage to the parallel resonance circuit; an input end of the filter circuit receives the resonance voltage, and an output end of the filter circuit outputs a filtered resonance voltage; and the voltage dividing circuit is connected in series with the parallel resonance circuit and configured to isolate the excitation signal.

[0011] As preferred, the direct current bias circuit comprises a first bias resistor, a second bias resistor, a transistor, a voltage dividing resistor, and a power supply; one end of the first bias resistor receives the excitation signal, the other end of the first bias resistor is electrically connected with a base of the transistor, and the first bias resistor is connected with a negative electrode of the power supply through the second bias resistor; an emitter of the transistor is connected with the negative electrode of the power supply through the voltage dividing resistor, and a collector of the transistor is electrically connected with an input end of the parallel resonance circuit and configured to output the isolated excitation signal to the parallel resonance circuit.

[0012] As preferred, the filter circuit comprises a diode and a filter capacitor connected in parallel.

[0013] As preferred, the filter circuit further comprises a first voltage dividing resistor and a second voltage dividing resistor; one end of the first voltage dividing resistor is electrically connected with the cathode of the diode, the other end of the first voltage dividing resistor is electrically connected with the wireless communication module, and grounded through the second voltage dividing resistor.

[0014] The utility model discloses the beneficial effect is as follows:

[0015] First, the utility model discloses a wireless pressure sensor converts pressure into telescopic amount by spring, and through parallel resonance circuit and electromagnetic induction of the electrode surface of button cell, makes the resonance voltage signal negative correlation change with telescopic amount, finally by wireless chip converts pressure radio frequency signal, utilizes the clear stable physical relation conversion, reduces the error of material defect, thereby improves detection accuracy.

[0016] Second, the utility model discloses a wireless pressure sensor adopts the compact integrated structure of button cell, spring and PCB board, wherein, spring has pressure conversion and electrical connection function, simplifies the structure, reduces the error factor of complex structure, thereby improves detection accuracy.

[0017] Third, the utility model discloses a wireless pressure sensor's wireless communication module sets the functions such as excitation signal emission, resonance voltage signal receiving processing and pressure radio frequency signal generation communication in one, reduces the interference of external environmental factor to measurement, thereby improves detection accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a wireless pressure sensor's structural schematic diagram of an embodiment of the utility model;

[0019] Figure 2 It is the schematic diagram of the circuit integrated on the PCB board of a wireless pressure sensor of an embodiment of the utility model.

[0020] In the drawing: 1. button cell;2. PCB board, 2-1. coil inductance, 2-2. height limiting block;3. spring. DETAILED DESCRIPTION

[0021] The utility model will be described in more detail in combination with the drawings. It should be noted that the following description of the utility model with reference to the drawings is only illustrative, but not restrictive.

[0022] In the possible case, each different embodiment described below can be recombined with each other to constitute other embodiments not shown in the following description;Each different technical feature described below can also be recombined with each other to constitute other embodiments not shown in the following description.

[0023] Embodiment 1:

[0024] Please refer to Figure 1 and Figure 2 .

[0025] To solve the problem of insufficient accuracy of detection results of existing wireless pressure sensors, the embodiment provides a wireless pressure sensor. The spring is used to convert pressure into extension and contraction amount. The parallel resonant circuit and the electrode surface of the button cell are electromagnetically induced. The resonant voltage signal changes in negative correlation with the extension and contraction amount. Finally, the wireless communication module converts the pressure radio frequency signal. The clear and stable physical relationship conversion improves the detection accuracy.

[0026] The wireless pressure sensor of the embodiment comprises a button cell 1, a spring 3, a PCB board 2 and a wireless chip. The button cell is electrically connected to the PCB board through the spring, and the first electrode surface of the button cell is arranged opposite to the PCB board. The spring is used to support the button cell and convert the pressure acting on the button cell into extension and contraction amount, and the pressure and the extension and contraction amount change in positive correlation. In addition, the spring can provide high elasticity and restoring force, adapt to mechanical stress and vibration, and ensure that the button cell can supply power to the PCB board.

[0027] The wireless communication module and the parallel resonant circuit are integrated on the PCB board. The wireless communication module is used to transmit an excitation signal, receive a resonant voltage signal and convert it into a pressure radio frequency signal. The parallel resonant circuit is used to receive the excitation signal and generate a resonant voltage signal in real time. Under the action of the excitation signal, the parallel resonant circuit and the first electrode surface form electromagnetic induction, and when the spring extends and contracts, the resonant voltage signal changes in negative correlation with the extension and contraction amount.

[0028] According to the above content, the operation process and principle of the wireless pressure sensor of the embodiment are as follows:

[0029] When the spring is not compressed, the parallel resonant circuit is driven by the excitation signal of the wireless communication module to form an eddy current on the first electrode surface (metal surface) of the button cell at a certain distance from the position of the parallel resonant circuit on the PCB board. The magnetic field excited by the eddy current in turn affects the inductance in the parallel resonant circuit, which is equivalent to increasing the parallel inductance in the parallel resonant circuit, so that the total inductance decreases and the resonant frequency increases. Under the drive of the excitation signal frequency, the resonant circuit outputs the maximum resonant voltage signal.

[0030] When external pressure acts on the button cell, the spring produces a compression amount, and when the compression amount increases, the button cell is increasingly close to the parallel resonant circuit on the PCB board, so the inductance in the parallel resonant circuit is continuously reduced, so that the resonant frequency is continuously increased. Under the driving of the excitation signal, the parallel resonant circuit outputs the deviated resonant voltage signal, and the resonant voltage signal at this time is smaller than the maximum resonant voltage signal. The above process reflects the negative correlation between the resonant voltage signal and the extension amount, that is, the larger the extension amount, the smaller the resonant voltage signal.

[0031] The parallel resonant circuit continuously outputs the resonant voltage signal according to the distance between the button cell and the PCB board or the extension amount of the spring, and the wireless communication module continuously receives the resonant voltage signal, and according to the corresponding relationship between the resonant voltage signal and the pressure signal, it is converted into a pressure radio frequency signal, and transmitted to the external terminal through other communication elements of the wireless communication module.

[0032] These changes are related to the change of distance. Within the distance of the total height of 12mm between the PCB and the button cell, the voltage changes linearly. By measuring the resonant voltage, the change of distance can be known, and the corresponding relationship between the voltage and the pressure change can be obtained by calibration.

[0033] According to the content, it can be known that the frequency of the excitation signal can be determined according to the initial height of the button cell and the PCB board and the initial value of the element parameters of the parallel resonant circuit, and the maximum resonant voltage signal under this condition is measured. When the resonant voltage signal received by the wireless chip is the same as the maximum resonant voltage signal, it represents that the pressure is 0. And as the distance between the button cell and the PCB board decreases, that is, the extension amount of the spring increases, the resonant voltage signal generated by the parallel resonant circuit gradually deviates from the maximum resonant voltage signal, so the pressure signal can be obtained by re-measuring the resonant voltage signal and according to the experience value lookup table, so as to realize the accurate detection of the pressure.

[0034] In the preferred embodiment, the wireless pressure sensor composed of the button cell, the spring and the PCB board has a width of 20-25mm and a height of 10-20mm. For example, the width of the wireless pressure sensor can be set to 20mm, and the height can be set to 10mm; or the width can be set to 22.5mm, and the height can be set to 15mm; or the width can be set to 25mm, and the height can be set to 20mm. The above settings can be arranged and combined arbitrarily as long as they are within the range.

[0035] Controlling the size of the wireless pressure sensor within the range of width 20-25mm and height 10-20mm can ensure that it is small and light, easy to integrate and comfortable to wear, while exceeding this range may result in bulkiness, weight increase, cost increase and performance decline.

[0036] In the preferred embodiment, the parallel resonant circuit includes a coil inductance 2-1 and a capacitor in parallel with each other, the coil inductance is a spiral coil printed on the PCB board, and the capacitor is integrated in the PCB board. Figure 2 In the circuit diagram of the preferred embodiment, the coil inductance is represented by J5, and the capacitor is represented by C38.

[0037] Therefore, the frequency of the excitation signal can be determined according to the initial distance between the button cell and the coil inductance, the inductance of the coil inductance, and the fine-tuned coil capacitor. The excitation signal is usually set to 500 kHz with a duty cycle of 50%. This setting is to match the resonant frequency of the parallel resonant circuit, ensure efficient energy transmission, avoid electromagnetic interference, and maintain low power consumption. A 50% duty cycle provides uniform energy distribution, simplifies circuit design, and ensures system stability and reliability. This configuration optimizes the overall performance of the wireless pressure sensor, but in practical application scenarios, the frequency and duty cycle of the excitation signal can be set according to the actual resonant frequency component parameters.

[0038] The coil inductance is usually set as follows: wire width 0.1mm-0.3mm, spacing 0.1mm-0.5mm, outer diameter 10mm-20mm, and inner diameter 0mm-10mm. For example, a coil inductance with a wire width of 0.1mm, a spacing of 0.1mm, an outer diameter of 10mm, and an inner diameter of 0mm can be selected; a coil inductance with a wire width of 0.2mm, a spacing of 0.3mm, an outer diameter of 15mm, and an inner diameter of 5mm can be selected; a coil inductance with a wire width of 0.25mm, a spacing of 0.36mm, an outer diameter of 17mm, and an inner diameter of 8mm can be selected; a coil inductance with a wire width of 0.3mm, a spacing of 0.5mm, an outer diameter of 20mm, and an inner diameter of 10mm can be selected. The above-mentioned specifications and models of coil inductance can be arbitrarily arranged and combined, and all can be realized.

[0039] The reason for the wire width of 0.1mm-0.3mm is that too narrow wire width will result in too large resistance, affecting the performance of the inductance, so the lower limit of the wire width is set to 0.1mm to prevent wire breakage or excessive line resistance when the wire width is less than this value. Too wide wire width will occupy too much PCB area, increasing the cost, so considering the actual PCB layout space and cost factors, the upper limit of the wire width is set to 0.3mm, which can ensure the performance of the inductance without making the PCB area too large.

[0040] The reason for the spacing of 0.1mm-0.5mm is that too small spacing will result in enhanced capacitive coupling between adjacent lines, interfering with the normal operation of the inductance. The lower limit is set to 0.1mm to prevent excessive parasitic capacitance between adjacent lines, affecting the self-inductance of the inductance and preventing the resonant frequency from changing. Too large spacing will waste PCB space, so the upper limit is set to 0.5mm, which can effectively avoid interference between adjacent lines without making the PCB layout too loose.

[0041] The reason for the outer diameter of 10mm - 20mm is that too small outer diameter makes the inductance too small, which cannot meet the requirement of the inductance of the resonant circuit, so the lower limit is set to 10mm. While too large outer diameter makes the overall size of the sensor too large, considering the actual application scenario and size limit of the sensor, the upper limit of the coil outer diameter is set to 20mm.

[0042] The reason for the inner diameter of 0mm - 10mm is that the inner diameter can be 0mm in theory, which is a limit case, indicating that the coil is a solid spiral starting from the center. In practice, as long as the feasibility of winding can be guaranteed, this value can remain 0mm. The inner diameter cannot be too large, otherwise it will reduce the effective number of turns of the coil, resulting in a decrease in inductance, so the upper limit of the inner diameter can be set to half of the outer diameter of the coil, i.e. 10mm.

[0043] In another preferred embodiment, the wireless communication module includes a wireless chip and a radio frequency; the PWM signal output end of the wireless chip transmits an excitation signal; the ADC channel input end of the wireless chip receives a resonant voltage signal, and the ADC channel output end of the wireless chip outputs a sampled voltage signal. Wherein, the wireless chip is used to encode and convert the sampled voltage signal into a pressure radio frequency signal by querying an experience table; the radio frequency is integrated at the connection between the spring and the PCB board, used to radiate the pressure radio frequency signal to the space and transmit the pressure radio frequency signal through the spring.

[0044] The positive and negative poles of the button cell are respectively electrically connected with two springs, and the inductance of the spring itself is very small, mainly playing a role in transmitting radio frequency signals and supporting the button cell. The spring connected to the negative pole is connected to the GND of the PCB board through a 270nH 0603 inductor with concentrated parameters, and the radio frequency signal is coupled to the solder joint between the spring and the PCB board through a 0402 capacitor with concentrated parameters, so the pressure radio frequency signal can also be transmitted through the spring. The spring connected to the positive pole supplies power to the integrated circuit on the PCB board through a series inductor.

[0045] This setting integrates the PWM signal output and ADC sampling functions through the wireless chip, achieving an efficient and compact circuit design, reducing the number of components and lowering the cost. The wireless chip directly processes the resonant voltage signal and converts it into a pressure radio frequency signal, ensuring high accuracy and fast response of the measurement. The radio frequency is integrated at the connection between the spring and the PCB board, using the spring as part of the antenna, enhancing the signal transmission efficiency and directivity, while saving space. The overall design not only improves the reliability of the system and the accuracy of data transmission, but is also particularly suitable for small and portable applications, such as embedding in smart furniture.

[0046] In another preferred embodiment, the wireless communication module further includes a timer that sends a trigger signal to the terminal device when the minimum compression amount of the spring is maintained for more than 30 minutes, thereby initiating a voice reminder to the person on the smart furniture through the terminal device. In the field of smart home, the wireless pressure sensor with the above structure can be integrated inside the furniture to detect whether a person is on the seat and the duration of stay, thereby initiating a movement reminder.

[0047] In another preferred embodiment, the button cell includes a first electrode surface, a second electrode surface, and an insulating shell circumferentially arranged on the side of the button cell; the area of the first electrode surface is larger than that of the second electrode surface; the first electrode surface forms the positive or negative electrode of the button cell; the second electrode surface forms the negative or positive electrode of the button cell and is used to form a microstrip antenna; the microstrip antenna is used to receive pressure radio frequency signals through the spring and communicate with external terminals; and the insulating shell is used to fix the spring.

[0048] For example, if the area of the positive electrode surface of the button cell is larger than that of the negative electrode surface, the negative electrode surface can be used as a microstrip antenna, and the positive electrode surface as a reference GND, or vice versa. Therefore, the second electrode surface can be either positive or negative. The second electrode surface as a microstrip antenna can be circular, quadrilateral, or even other irregular shapes, as long as it meets the area limit condition and the actual application scenario. The advantage of using a button cell as a microstrip antenna is to reduce the PCB area and save space, thereby reducing the size of the sensor. Although the efficiency of the microstrip antenna is not high, it is very beneficial for space saving.

[0049] This design of button cell realizes the integration of power supply and communication module, reduces the number of components and optimizes the space utilization. The insulating shell not only protects the battery, but also fixes the spring to ensure stable connection. The microstrip antenna receives pressure radio frequency signals through the spring and communicates with external terminals, enhancing the signal transmission efficiency. The overall design is compact and multifunctional, improving the reliability and communication performance of the system.

[0050] In another preferred embodiment, the spring coefficient determines the relationship between pressure size and distance. The spring coefficient determines the degree of deformation when it is under stress, which in turn affects the relationship between pressure size and distance.

[0051] Different spring coefficients will result in different response characteristics. The following are specific examples and explanations: Suppose a wireless pressure sensor is designed with a size of 22.5mm in width and 15mm in height. The initial distance between the button cell and the PCB board is set to 12mm, which is the distance when there is no external pressure. The specifications of the coil inductance are selected as follows: wire width 0.2mm, pitch 0.3mm, outer diameter 15mm, and inner diameter 5mm. The selection of coil inductance is based on its ability to maintain sufficient inductance while occupying relatively less PCB area.

[0052] The parameter settings of the wireless pressure sensor in the above example include: excitation signal frequency: 500 kHz (to match the resonance frequency of the parallel resonance circuit); duty cycle: 50%; spring: a spring with a spring constant of 500 N / m is used; initial distance between the coin cell and the PCB board: 12 mm; maximum resonance voltage signal: V_max, measured under no pressure; height of the height-limiting block: no more than 1 / 6 of the length of the spring, to ensure electrical isolation and mechanical stability.

[0053] The operation process is as follows: when the sensor is in the unpressurized state, the coin cell maintains a distance of 12 mm from the PCB board through the spring. At this time, the wireless communication module sends an excitation signal of 500 kHz, which is received by the parallel resonance circuit and forms an eddy current on the first electrode surface of the coin cell, resulting in an enhanced magnetic field, affecting the inductance value in the parallel resonance circuit, causing the total inductance to decrease and the resonance frequency to increase. In this state, the resonance circuit outputs the maximum resonance voltage signal V_max.

[0054] Now, if a pressure of 5 N is applied to the coin cell, according to Hooke's Law F=kx, the compression amount x =F / k = 5N / 500 N / m = 0.01m = 10mm can be calculated. This means that the distance between the coin cell and the PCB board decreases from 12 mm to 2 mm. Since the coin cell is close to the parallel resonance circuit on the PCB board, the inductance increases, causing the resonance frequency to rise, and the resonance voltage signal output by the parallel resonance circuit deviates from V_max and becomes smaller. This reflects the negative correlation between the resonance voltage signal and the extension amount.

[0055] For simplicity, assume that the resonance voltage V is linearly related to the distance d between the coin cell and the PCB board. Therefore, this relationship can be represented by the following formula: V(d) = Vmax k (d0 d); where V(d) is the resonance voltage when the distance is d, Vmax is the maximum resonance voltage under no pressure, d0 is the initial distance under no pressure, and k is the proportionality constant, which can be calibrated through experiments.

[0056] If the measured relationship between pressure and resonance voltage is: when the distance is 12 mm, Vmax = 3.3 V, and when the distance is shortened to 2 mm, the resonance voltage decreases to 2.2 V. Then, when the sensor detects a resonance voltage of 2.75 V, it can be inferred that the distance between the coin cell and the PCB board is approximately 7 mm, and the corresponding pressure value can be calculated.

[0057] In another preferred embodiment, the side of the PCB board opposite to the arrangement of the button cell is provided with a height-limiting block 2-2, and the height of the height-limiting block in the actual application scenario is often not more than 1 / 6 of the length of the spring, for preventing the button cell from directly contacting the PCB board. This design is to ensure electrical isolation, maintain the effective working range of the spring, and minimize the impact on the thickness and mechanical performance of the device. Exceeding this proportion may compress the working range of the spring, increase the thickness of the device, and cause mechanical problems.

[0058] The height-limiting block can be provided as a plurality of dispersed height-limiting blocks, as two strip-shaped height-limiting blocks, or as two arc-shaped height-limiting blocks, as long as it can prevent the button cell from directly contacting the PCB board.

[0059] Embodiment 2:

[0060] Please refer to Figure 2 .

[0061] The wireless pressure sensor provided in this embodiment further describes the circuit integrated on the PCB board on the basis of Embodiment 1. The PCB board is further integrated with one or more of a direct current bias circuit, a filter circuit, and a voltage division circuit. The above-mentioned circuits, whether single or combined, can reduce the need for external connectors and wiring, making the entire system more compact and easy to manufacture.

[0062] The direct current bias circuit is connected in series with the parallel resonance circuit, for providing a direct current bias voltage to the parallel resonance circuit. An appropriate direct current bias voltage can improve the response sensitivity of the parallel resonance circuit to small pressure changes.

[0063] The input end of the filter circuit receives a resonance voltage, and the output end outputs a filtered resonance voltage. The filter circuit can effectively remove high-frequency noise and other interference, improve the signal-to-noise ratio, and ensure that the collected signal is purer and more accurate.

[0064] The voltage division circuit is connected in series with the resonance circuit, for isolating the excitation signal and preventing high-frequency or high-intensity excitation signals from causing interference or damage to other circuit parts. The isolation measures enhance the overall stability of the system, reduce the mutual influence between different modules, and ensure the independence and reliability of each component.

[0065] In a preferred embodiment, the DC biasing circuit includes a first biasing resistor R47, a second biasing resistor R48, a transistor Q5, a voltage dividing resistor R8, and a power supply DVDD. One end of the first biasing resistor R47 receives the excitation signal, the other end is electrically connected to the base of the transistor Q5, and is electrically connected to the power supply DVDD through the second biasing resistor R48. The emitter of the transistor Q5 is electrically connected to the power supply DVDD through the voltage dividing resistor R8, and its collector is electrically connected to the input of the parallel resonance circuit, for outputting the isolated excitation signal to the parallel resonance circuit.

[0066] The above embodiment ensures the stability of the base voltage of the transistor Q5 through the voltage dividing effect of the first biasing resistor R47 and the second biasing resistor R48, thereby providing a stable DC biasing voltage for the parallel resonance circuit. Appropriate resistance value selection can reduce the impact of temperature changes on the biasing voltage, ensuring the stability of the circuit in different environments.

[0067] The transistor Q5, as a switch or amplifier, can effectively isolate the excitation signal, preventing high-frequency or high-intensity signals from directly entering the parallel resonance circuit and avoiding damage to it. This isolation mechanism also protects other circuit parts from possible overvoltage or current surges, improving the reliability of the entire system.

[0068] In another preferred embodiment, the filter circuit includes a diode D8 and a filter capacitor C38 in parallel. The filter capacitor C38 can effectively remove high-frequency noise in the resonance voltage, ensuring that the output resonance voltage is more pure and smooth, and can also stabilize the DC component in the signal, reducing fluctuations and improving the accuracy of subsequent circuit processing. The diode D8 can prevent possible reverse voltage from damaging the circuit, providing an additional protection layer. In particular, in the case of unstable power supply or signal source, it also has a clamping function, which can limit the voltage within a certain range to avoid damage to sensitive components (such as IC) caused by excessive voltage surges.

[0069] In a further preferred embodiment, the filter circuit further includes a first voltage dividing resistor R51 and a second voltage dividing resistor R50. One end of the first voltage dividing resistor R51 is electrically connected to the cathode of the diode D8, the other end of the first voltage dividing resistor R51 is electrically connected to the wireless communication module, and is grounded through the second voltage dividing resistor R50.

[0070] The first voltage dividing resistor R51 and the second voltage dividing resistor R50 form a voltage dividing network, which can accurately adjust and stabilize the filtered resonance voltage, ensuring that the voltage output to the wireless communication module is within a predetermined range, improving the reliability and stability of the system. By adjusting the resistance values of the first voltage dividing resistor R51 and the second voltage dividing resistor R50, the output voltage can be flexibly adjusted according to different load requirements or application scenarios, making the system more adaptable.

[0071] It should be understood that the embodiments are only used for illustrating the present application and are not used for limiting the scope of the present application. In addition, it should be understood that after reading the content taught by the present application, those skilled in the art can make various changes or modifications to the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims

1. A wireless pressure sensor, characterized in that, include: Button batteries, springs, and PCB boards; The button battery is electrically connected to the PCB board via the spring, and its first electrode surface is arranged opposite to the PCB board. The spring is used to support the button battery and convert the pressure acting on the button battery into a stretching amount, and the pressure and the stretching amount change in a positive correlation. The PCB board integrates a wireless communication module and a parallel resonant circuit. The wireless communication module is used to transmit excitation signals, receive resonant voltage signals, and convert them into pressure radio frequency signals. The parallel resonant circuit is used to receive the excitation signal and generate the resonant voltage signal in real time. Under the action of the excitation signal, the parallel resonant circuit forms an electromagnetic induction with the first electrode surface, and when the spring extends or retracts, the resonant voltage signal changes in a negative correlation with the amount of extension or retraction.

2. The wireless pressure sensor according to claim 1, characterized in that, The parallel resonant circuit includes coil inductors and capacitors connected in parallel. The coil inductance is a spiral coil printed on the PCB board; The capacitor is integrated on the PCB board.

3. The wireless pressure sensor according to claim 1, characterized in that, The wireless communication module includes a wireless chip and radio frequency; The PWM signal output terminal of the wireless chip transmits the excitation signal; the ADC channel input terminal of the wireless chip receives the resonant voltage signal, and its ADC channel output terminal outputs the sampled voltage signal. The wireless chip is used to encode the sampled voltage signal and convert it into the pressure radio frequency signal by consulting an experience table; The radio frequency is integrated at the connection between the spring and the PCB board, and is used to radiate the pressure radio frequency signal into space and transmit the pressure radio frequency signal through the spring.

4. The wireless pressure sensor according to claim 1, characterized in that, The button battery includes a first electrode surface, a second electrode surface, and an insulating shell circumferentially disposed on the side of the button battery. The area of ​​the first electrode surface is larger than the area of ​​the second electrode surface; The first electrode surface forms the positive or negative electrode of the button cell; The second electrode surface forms the negative or positive electrode of the button cell and is used to form a microstrip antenna; The microstrip antenna is used to receive the pressure radio frequency signal through the spring and to communicate with an external terminal. The insulating shell is used to fix the spring.

5. The wireless pressure sensor according to claim 1, characterized in that, A height limiting block is provided on the side of the PCB board opposite to the button battery. The height of the height limiting block does not exceed the length of the spring, which is used to prevent the button battery from directly contacting the PCB board.

6. The wireless pressure sensor according to any one of claims 1 to 5, characterized in that, The PCB board also integrates one or more of the following: DC bias circuit, filter circuit, and voltage divider circuit. The DC bias circuit is connected in series with the parallel resonant circuit and is used to provide a DC bias voltage to the parallel resonant circuit; The input terminal of the filter circuit receives the resonant voltage, and its output terminal outputs the filtered resonant voltage. The voltage divider circuit is connected in series with the parallel resonant circuit to isolate the excitation signal.

7. The wireless pressure sensor according to claim 6, characterized in that, The DC bias circuit includes: a first bias resistor, a second bias resistor, a transistor, a voltage divider resistor, and a power supply; One end of the first bias resistor receives the excitation signal, and the other end is electrically connected to the base of the transistor, and is connected to the negative terminal of the power supply through the second bias resistor; The emitter of the transistor is connected to the negative terminal of the power supply through the voltage divider resistor, and its collector is electrically connected to the input terminal of the parallel resonant circuit, for outputting the isolated excitation signal to the parallel resonant circuit.

8. The wireless pressure sensor according to claim 6, characterized in that, The filter circuit includes diodes and filter capacitors connected in parallel.

9. The wireless pressure sensor according to claim 8, characterized in that, The filter circuit also includes a first voltage divider resistor and a second voltage divider resistor; One end of the first voltage divider resistor is electrically connected to the cathode of the diode, and the other end of the first voltage divider resistor is electrically connected to the wireless communication module and grounded through the second voltage divider resistor.

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