JP2021032717A - Pressure sensing system and method for sensing pressure - Google Patents

Abstract

To provide a pressure sensing system that can improve the accuracy of measuring a pressure.SOLUTION: A pressure sensing system 100 includes: a voltage waveform output unit 10 for outputting a first voltage waveform; a pressure sensing unit 20 connected to the voltage waveform output unit 10 for receiving the first voltage waveform and outputting a second voltage waveform formed by changing the phase of the first voltage waveform according to an applied voltage; and a detection unit 40 connected to the voltage waveform output unit 10 and to the pressure sensing unit 20 for receiving the first voltage waveform and the second voltage waveform, the detection unit 40 detecting a pressure on the basis of the phase of the first voltage waveform and the phase of the second voltage waveform.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressure sensitive system and a pressure sensitive method.

Patent Document 1 discloses a load sensor made of pressure-sensitive conductive rubber in which conductive particles such as carbon are dispersed and contained and the electric resistance value changes according to the load. This load sensor detects the load by sandwiching the pressure-sensitive conductive rubber between a pair of electrodes and measuring the fluctuation of the resistance value that changes depending on the received load with the voltage value.

Japanese Unexamined Patent Publication No. 1-150825

However, in a pressure-sensitive sensor that detects pressure based on a resistance value as in the prior art, it is difficult to accurately obtain the pressure because the temperature characteristic of the resistance value with respect to the temperature due to the ambient environment is large.

The pressure-sensitive system is connected to a voltage waveform output unit that outputs a first voltage waveform and the voltage waveform output unit to receive the first voltage waveform, and the phase of the first voltage waveform is adjusted according to the applied pressure. A pressure-sensitive unit that outputs a fluctuating second voltage waveform, and a detection unit that is connected to the voltage waveform output unit and the pressure-sensitive unit and receives the first voltage waveform and the second voltage waveform. The detection unit is characterized in that the pressure is detected based on the phase of the first voltage waveform and the phase of the second voltage waveform.

In the pressure-sensitive system, the frequency of the first voltage waveform is preferably a resonance frequency in the pressure-sensitive portion.

In the pressure-sensitive system, the detection unit preferably detects the pressure based on the phase difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

In the pressure-sensitive system, the detection unit preferably detects the pressure based on the time difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

In the pressure-sensitive system, the pressure-sensitive portion has a first electrode and a second electrode, and the first electrode and the second electrode are comb-teeth-like electrodes in which comb teeth are arranged so as to mesh with each other. Is preferable.

In the pressure-sensitive system, the pressure-sensitive portion is preferably a silicon substrate.

In the pressure-sensitive system, the pressure-sensitive portion preferably has a pair of electrodes and a conductive resin sandwiched between the pair of electrodes.

In the pressure-sensitive system, the detection unit preferably has a frequency conversion circuit that converts the frequencies of the received first voltage waveform and the second voltage waveform into lower frequencies.

The pressure-sensitive method includes a voltage waveform output unit that outputs a predetermined voltage waveform, a pressure-sensitive unit that detects pressure, and a detection unit that detects pressure based on the voltage waveform output unit and the output signals from the pressure-sensitive unit. A pressure-sensitive method using a pressure-sensitive system, wherein the voltage waveform output unit outputs a first voltage waveform, and the pressure-sensitive unit receives the first voltage waveform and is applied. The second output step of outputting the second voltage waveform in which the phase of the first voltage waveform fluctuates according to the pressure, and the detection unit receives the first voltage waveform and the second voltage waveform, and the first voltage It is characterized by including a detection step of detecting the pressure based on the phase of the waveform and the phase of the second voltage waveform.

In the above pressure-sensitive method, the frequency of the first voltage waveform is preferably a resonance frequency in the pressure-sensitive portion.

In the above pressure-sensitive method, it is preferable that the detection step detects the pressure based on the phase difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

In the above pressure-sensitive method, it is preferable that the detection step detects the pressure by the time difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

In the above pressure-sensitive method, the detection step preferably includes a frequency conversion step of converting the frequencies of the received first voltage waveform and the second voltage waveform into lower frequencies.

The block diagram which shows the structure of the pressure sensitive system which concerns on Embodiment 1. FIG. The plan view which shows the structure of the pressure sensitive part. FIG. 2 is a cross-sectional view taken along the line AA in FIG. A cross-sectional view for explaining the first electrode finger in an enlarged manner. A cross-sectional view for explaining the first electrode finger in an enlarged manner. The flowchart explaining the pressure-sensing method by a pressure-sensitive system. The figure explaining the signal waveform output from each part. A graph showing the relationship between load and voltage. A graph showing the temperature dependence of a pressure sensitive system. The block diagram which shows the structure of the pressure sensitive system which concerns on Embodiment 2. The block diagram which shows the structure of the pressure sensitive system which concerns on Embodiment 3. The cross-sectional view which shows the structure of the pressure sensitive part which concerns on Embodiment 4.

1. 1. Embodiment 1
1-1. Configuration of Pressure Sensitive System FIG. 1 is a block diagram showing a configuration of a pressure sensitive system according to the first embodiment.
The pressure-sensitive system 100 includes a voltage waveform output unit 10, a pressure-sensitive unit 20, and a detection unit 40.

The detection unit 40 has a frequency conversion circuit 30, and includes a first limiter 41, a second limiter 42, a logic circuit 43, a low frequency pass filter 44, and a measurement unit 45. The frequency conversion circuit 30 includes a local oscillator 31, a first mixer 32, a first amplifier 33, a first filter 34, and a second mixer 35, a second amplifier 36, and a second filter 37.

The voltage waveform output unit 10 is a reference signal generator that outputs a signal of a first voltage waveform having a predetermined frequency. The voltage waveform output unit 10 is connected to the first mixer 32 of the frequency conversion circuit 30 included in the detection unit 40 and the pressure sensitive unit 20.
The pressure-sensitive unit 20 receives the first voltage waveform from the voltage waveform output unit 10 and outputs a second voltage waveform in which the phase of the first voltage waveform fluctuates according to the pressure applied to the pressure-sensitive unit 20. The pressure sensitive unit 20 is connected to the second mixer 35 of the frequency conversion circuit 30 included in the detection unit 40.
The first mixer 32 and the second mixer 35 are connected to the local oscillator 31, and the oscillation output is input from the local oscillator 31.

The first mixer 32 outputs a signal including a plurality of frequency components obtained by synthesizing a signal having a predetermined frequency having a first voltage waveform received from the voltage waveform output unit 10 and a signal having a frequency oscillated by the local oscillator 31. To do. The first mixer 32 is connected to the first filter 34 via the first amplifier 33. The first filter 34 is a passband filter that allows a desired frequency component to pass through, and is a desired frequency within the passband that is lower than a predetermined frequency from a signal containing a plurality of frequency components amplified by the first amplifier 33. A signal is output in which a component is passed and a frequency component outside the pass band is suppressed.

The second mixer 35 outputs a signal including a plurality of frequency components obtained by synthesizing a signal having a predetermined frequency having a second voltage waveform received from the pressure sensitive unit 20 and a signal having a frequency oscillated by the local oscillator 31. .. The second mixer 35 is connected to the second filter 37 via the second amplifier 36. The second filter 37 is a band-passing type filter that passes a desired frequency component, and is a desired frequency in the pass band lower than a predetermined frequency from a signal containing a plurality of frequency components amplified by the second amplifier 36. A signal is output in which the frequency component is passed and the frequency component outside the pass band is suppressed. That is, the frequency conversion circuit 30 converts a signal having a predetermined frequency into a signal having a frequency lower than the predetermined frequency. The first and second filters 34 and 37 may be low frequency passing type filters that pass a desired frequency component lower than a predetermined frequency and suppress a frequency component higher than a predetermined frequency.

The first filter 34 is connected to the first limiter 41 of the detection unit 40. The first limiter 41 is a waveform shaping circuit, and outputs a signal obtained by shaping the waveform of a signal having a desired frequency that has passed through the first filter 34. The first limiter 41 is connected to the logic circuit 43.
The second filter 37 is connected to the second limiter 42 of the detection unit 40. The second limiter 42 is a waveform shaping circuit, and outputs a signal obtained by shaping the waveform of a signal having a desired frequency that has passed through the second filter 37. The second limiter 42 is connected to the logic circuit 43.

The logic circuit 43 outputs a signal obtained by exclusive-ORing the signals input from both the first limiter 41 and the second limiter 42. The logic circuit 43 is connected to the measurement unit 45 via the low frequency pass filter 44. The signal output from the logic circuit 43 is a signal based on the phase difference between the first voltage waveform and the second voltage waveform. The measuring unit 45 measures the signal integrated by the low frequency pass filter 44. As described above, the detection unit 40 detects the pressure applied to the pressure sensitive unit 20 based on the phase difference between the phases of the first voltage waveform and the second voltage waveform.

In the present embodiment, a block diagram in which each part of the pressure-sensitive system 100 is connected by one transmission line and driven in an unbalanced manner is shown, but at least a part of the pressure-sensitive system is connected by two transmission lines. , It may be a pressure sensitive system driven in equilibrium. As a result, a pressure sensitive system with high noise resistance can be obtained.

1-2. Configuration of Pressure Sensitive Unit FIG. 2 is a plan view showing the configuration of the pressure sensitive unit. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 4 and 5 are cross-sectional views for explaining the first electrode finger in an enlarged manner. In FIG. 2, for convenience of explanation, the support substrate 25 shown in FIG. 3 is shown through. Further, FIG. 4 shows a state before a load is applied to the pressure sensitive unit 20, and FIG. 5 shows a state after a load is applied to the pressure sensitive unit 20. Further, in the coordinates added to the drawings, the direction along the Z-axis is the thickness direction of the semiconductor substrate 23 described later, and the arrow direction of the Z-axis is "up".

As shown in FIGS. 2 and 3, the pressure-sensitive unit 20 includes the semiconductor substrate 23 and the first and second electrodes 21 and 22 arranged in contact with the upper surface 23a which is one surface of the semiconductor substrate 23. It has a support substrate 25 that supports the first and second electrodes 21 and 22, an insulating film 24 that is arranged on the lower surface 23b that is the other surface of the semiconductor substrate 23, and a third electrode 28 that covers the insulating film 24. The first electrode 21 is a comb-toothed electrode having a plurality of first electrode fingers 21a extending along the X axis from a bus bar 21b extending along the Y axis. The second electrode 22 is a comb-toothed electrode having a plurality of second electrode fingers 22a extending along the X axis from a bus bar 22b extending along the Y axis. The first electrode finger 21a and the second electrode finger 22a are arranged so as to be separated from each other so that the comb teeth mesh with each other. The bus bar 21b is connected to the lead wire 26 connected to the voltage waveform output unit 10, and the bus bar 22b is connected to the lead wire 27 connected to the second mixer 35. Further, the semiconductor substrate 23 has conductivity, and the first electrode 21 and the second electrode 22 are electrically connected via the semiconductor substrate 23.

When a load N as a pressure is applied to the pressure-sensitive portion 20 in the thickness direction of the pressure-sensitive portion 20, the contact area between the first electrode 21 and the upper surface 23a of the semiconductor substrate 23 is not subjected to the load N shown in FIG. The contact area in the state where the load N shown in FIG. 5 is applied is larger than the contact area in the state. Further, the contact area between the second electrode 22 and the upper surface 23a of the semiconductor substrate 23 also increases in the same manner. The first electrode 21 and the second electrode 22 are in contact with the upper surface 23a of the semiconductor substrate 23 without being bonded by a binding force, respectively. In this way, the first electrode 21 and the second electrode 22 are in contact with the upper surface 23a of the semiconductor substrate 23 without having a coupling force, so that the first and second electrodes 21 The contact area between the 22 and the upper surface 23a of the semiconductor substrate 23 is likely to change.

The constituent materials of the first electrode 21, the second electrode 22, and the third electrode 28 are not particularly limited, and are, for example, gold (Au), platinum (Pt), silver (Ag), copper (Cu), and nickel (Ni). ), Various metals such as aluminum (Al), alloys containing at least one of them, and the like, and one or more of these may be used in combination. In the present embodiment, the first electrode 21 and the second electrode 22 are each made of copper (Cu), and among them, a flexible copper foil. The Young's modulus of silicon (Si) constituting the semiconductor substrate 23 is about 185 Gpa, whereas the Young's modulus of copper (Cu) is about 130 Gpa. That is, the first electrode 21 and the second electrode 22 are softer and more easily deformed than the semiconductor substrate 23. Therefore, when a load N is applied, the first electrode 21 and the second electrode 22 are deformed more than the semiconductor substrate 23, and the first and second electrodes 21 and 22 come into contact with the upper surface 23a of the semiconductor substrate 23. The area is more variable.

A silicon substrate is used for the semiconductor substrate 23 of this embodiment. As a result, the mechanical strength of the pressure sensitive portion 20 is increased. Moreover, as a silicon substrate, a single crystal silicon substrate is used. As a result, the above-mentioned effect becomes more remarkable. As long as it is a single crystal silicon substrate, the crystal orientation is not limited, and (110) single crystal silicon substrate, (100) single crystal silicon substrate, and the like can be used.

As the semiconductor substrate 23, a silicon substrate other than the single crystal silicon substrate, such as a polycrystalline silicon substrate and an amorphous silicon substrate, may be used. Since the polycrystalline silicon substrate and the amorphous silicon substrate are cheaper than the single crystal silicon substrate, the pressure sensitive portion 20 can be manufactured at a lower cost by using them as the semiconductor substrate 23. Further, as the semiconductor substrate 23, a semiconductor substrate other than the silicon substrate, for example, a compound semiconductor substrate such as Ge substrate, GaP, GaAs, InP or the like may be used.

The surface roughness of the upper surface 23a of the semiconductor substrate 23, which is the contact surface between the first electrode 21 and the second electrode 22, is not particularly limited, and is, for example, the arithmetic average roughness Ra within the range of 1 nm or more and 400 nm or less. Is preferable, and the maximum height roughness Rz is preferably in the range of 10 nm or more and 4500 nm or less. As a result, the contact area between the upper surface 23a and the first and second electrodes 21 and 22 is likely to change when the load N is received. The surface roughness Ra and Rz can be measured by an optical interferometry according to JIS B 0681-6.

The thickness of the semiconductor substrate 23 is not particularly limited, but can be, for example, about 400 μm or more and 600 μm or less. As a result, the pressure-sensitive portion 20 having sufficiently high mechanical strength can be obtained while preventing the pressure-sensitive portion 20 from becoming excessively large.

As shown in FIG. 3, the lower surface 23b of the semiconductor substrate 23 is covered with the third electrode 38 via the insulating film 24. The insulating film 24 is made of, for example, a resin insulating sheet, and in the present embodiment, an insulating sheet made of polyimide is used. The third electrode 38 is a ground electrode and is grounded. By providing the insulating film 24, it is possible to prevent the semiconductor substrate 23 from conducting with the third electrode 38. The pressure-sensitive portion 20 may have a configuration in which the third electrode 38 is not formed or a configuration in which the insulating film 24 and the third electrode 38 are not formed, depending on the object on which the pressure-sensitive portion 20 is installed.

The support substrate 25 is provided above the first and second electrodes 21 and 22. In other words, the first and second electrodes 21 and 22 are formed between the semiconductor substrate 23 and the support substrate 25, and the support substrate 25 has the first electrode 21 and the second electrode 22 with respect to the semiconductor substrate 23. I support it. Similarly, the lead wires 26 and 27 to which the first and second electrodes 21 and 22 are connected are also formed between the semiconductor substrate 23 and the support substrate 25. As a result, the electrical connection between the first and second electrodes 21 and 22 can be easily pulled out via the lead wires 26 and 27.

Further, the support substrate 25 is joined to the upper surface 23a of the semiconductor substrate 23 at its outer edge portion via a joining member (not shown). As a result, it is possible to prevent the first and second electrodes 21 and 22 from being displaced or detached from the semiconductor substrate 23. The support substrate 25 may be hard or soft, but in the present embodiment, a flexible printed wiring board having flexibility is used. This simplifies the configuration of the support substrate 25. However, the support substrate 25 may be omitted.

In the present embodiment, the pressure-sensitive portion 20 in which the first and second electrodes 21 and 22 are in contact with the upper surface 23a of the semiconductor substrate 23 is illustrated in a state where no load N is applied, but the present invention is limited to this. It's not a thing. In the pressure sensitive portion, for example, in a state where the load N is not applied, the first and second electrodes 21 and 22 are separated from the upper surface 23a of the semiconductor substrate 23, and when the load N is applied, the first and second electrodes 21 , 22 may be in contact with the upper surface 23a of the semiconductor substrate 23.
Further, in the present embodiment, the pressure-sensitive portion 20 in which the contact area between the first and second electrodes 21 and 22 and the semiconductor substrate 23 increases as the received load N increases is illustrated, but the present invention is limited to this. is not it. The pressure-sensitive portion may have a configuration in which the contact area between the first and second electrodes 21 and 22 and the semiconductor substrate 23 decreases as the received load N increases. Further, the pressure-sensitive portion has a configuration in which the contact area between the first electrode 21 and the semiconductor substrate 23 and the contact area between the second electrode 22 and the semiconductor substrate 23 change when a load N is applied. It may be.

The pressure-sensitive unit 20 configured in this way receives the first voltage waveform and outputs the second voltage waveform corresponding to the applied load N. Specifically, the first and second electrodes 21 and 22 configured in the pressure sensitive portion 20 form various parasitic capacitances. For example, the first and second electrodes 21 and 22 generate a parallel capacitance between the semiconductor substrate 23 and the third electrode 28 via the insulating film 24. The relative permittivity of the semiconductor substrate 23 is much larger than the relative permittivity of air. Therefore, when a load N is applied in the thickness direction of the pressure sensitive portion 20, the relative permittivity also increases as the contact area between the first and second electrodes 21 and 22 and the semiconductor substrate 23 increases, and the parallel capacitance becomes large. Become. The fluctuation of the parallel capacitance changes the phase of the first voltage waveform input to the pressure sensitive unit 20. That is, the pressure sensitive unit 20 outputs a second voltage waveform in which the phase of the input first voltage waveform is changed according to the applied load N. Since the pressure-sensitive unit 20 having the configuration provided with the third electrode 28 forms a stable parallel capacitance without being affected by the object on which the pressure-sensitive unit 20 is installed, the detection accuracy of the load N is improved.

1-3. Pressure Sensitive Method FIG. 6 is a flowchart illustrating a pressure sensitive method by a pressure sensitive system. The frequency conversion step of step S103 and the detection step of step S104 in FIG. 6 correspond to the detection step. In other words, the detection step includes a frequency conversion step.

Step S101 is a first voltage waveform output step as a first output step for outputting the first voltage waveform. The voltage waveform output unit 10 outputs a first voltage waveform having a predetermined frequency. The predetermined frequency is preferably the resonance frequency in the pressure sensitive unit 20. The resonance frequency is the frequency at which the impedance of the pressure sensitive unit 20 becomes the lowest. The resonance frequency of the pressure-sensitive unit 20 of the present embodiment is 50 MHz, and the voltage waveform output unit 10 outputs, for example, a sine wave having a frequency of 50 MHz and an amplitude of 3 V to the first mixer 32 and the pressure-sensitive unit 20.

Step S102 is a second voltage waveform output step as a second output step for outputting the second voltage waveform. The pressure-sensitive unit 20 receives the first voltage waveform from the voltage waveform output unit 10 and outputs the second voltage waveform whose phase is changed according to the load N applied to the pressure-sensitive unit 20 to the second mixer 35.

Step S103 is a frequency conversion step of converting a predetermined frequency into a frequency lower than a predetermined frequency. The local oscillator 31 outputs, for example, an oscillation output of 47 MHz to the first mixer 32 and the second mixer 35. The frequency conversion circuit 30 has a first system that converts the frequency of the first voltage waveform via the first mixer 32, the first amplifier 33, and the first filter 34, and the second voltage waveform of the second mixer 35 and the second amplifier 36. And a second system for frequency conversion via the second filter 37. Since the frequency conversion method is the same for both systems, the frequency conversion in the first system will be described below, and the description of the frequency conversion in the second system will be omitted.

The first mixer 32 outputs a signal including a 97 MHz frequency component added and a 3 MHz frequency component subtracted from the first voltage waveform having a frequency of 50 MHz and the oscillation output of 47 MHz to the first amplifier 33. To do. The first amplifier 33 amplifies the input signal to a predetermined gain and outputs it to the first filter 34. The first filter 34 is a band-passing type filter that passes a frequency component of 3 MHz, suppresses a frequency component of 97 MHz and a frequency component outside the pass band including unnecessary harmonics from the input signal, and has a frequency of 3 MHz. Outputs a signal that has passed the frequency component. The signal output from the first filter 34 is a sine wave signal whose frequency has been converted to 3 MHz while maintaining the phase of the first voltage waveform. Similarly, the signal output from the second filter 37 is a sine wave signal whose frequency has been converted to 3 MHz while maintaining the phase of the second voltage waveform. In this way, the frequency conversion circuit 30 frequency-converts the received signals of the first voltage waveform and the second voltage waveform having a frequency of 50 MHz to a frequency of 3 MHz.

Step S104 is a detection step of generating and detecting a signal based on the phase difference. FIG. 7 is a diagram illustrating signals output from each unit. The horizontal axis of FIG. 7 indicates the time T, and the vertical axis of FIG. 7 indicates the voltage V. In FIG. 7, from the first stage of the uppermost stage to the fourth stage of the lowermost stage, the output signal of the first limiter 41, the output signal of the second limiter 42, the output signal of the logic circuit 43, and the low frequency range are shown. The output signal of the pass filter 44 is shown on the same time axis.

The output signal shown in the first stage of FIG. 7 is a signal output from the first limiter 41 and input to the logic circuit 43. Hereinafter, this signal is referred to as a “first output signal”. The output signal shown in the second stage of FIG. 7 is a signal output from the second limiter 42 and input to the logic circuit 43. Hereinafter, this signal is referred to as a “second output signal”.
The first limiter 41 converts the sine wave signal output from the first filter 34 into a binarized square wave first output signal. The phase of the first output signal is in phase with the phase of the first voltage waveform input to the pressure sensitive unit 20.
The second limiter 42 converts the output of the sine wave output from the second filter 37 into the second output signal of the binarized rectangular wave. The phase of the second output signal is in phase with the phase of the second voltage waveform output from the pressure sensitive unit 20. The second output signal is a signal that is phase-lagging or phase-advanced with respect to the phase of the first output signal according to the load N applied to the pressure-sensitive unit 20.

The output signal shown in the third stage of FIG. 7 is a signal output from the logic circuit 43 and input to the low frequency pass filter 44. Hereinafter, this signal is referred to as a “third output signal”.
The logic circuit 43 outputs a third output signal that is exclusively logically operated from the input first output signal and second output signal. The third output signal is a rectangular wave having a different time axis width depending on the phase difference between the first output signal and the second output signal.

The output signal shown in the fourth stage of FIG. 7 is a signal output from the low frequency pass filter 44 and input to the measurement unit 45. Hereinafter, this signal is referred to as a “fourth output signal”.
The low frequency pass filter 44 outputs a fourth output signal obtained by integrating the input third output signal. The fourth output signal represents a DC voltage having a different voltage value depending on the phase difference between the first output signal and the second output signal.

The measuring unit 45 measures the voltage of the input fourth output signal. That is, the measuring unit 45 measures a voltage that changes according to the phase difference between the first voltage waveform input to the pressure sensitive unit 20 and the second voltage waveform output from the pressure sensitive unit 20, and from that voltage. The load N applied to the pressure sensitive unit 20 can be obtained. Therefore, the detection step and the detection unit 40 detect the pressure of the pressure sensitive unit 20 based on the phase difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

FIG. 8 is a graph showing the relationship between the load and the voltage. The horizontal axis of FIG. 8 represents the load N applied to the pressure sensitive portion 20. The vertical axis of FIG. 8 represents the voltage value V of the fourth output signal. As shown in FIG. 8, the load N and the voltage value V have a proportional relationship, and the load N applied to the pressure sensitive unit 20 can be obtained from the voltage value V measured by the measuring unit 45.

FIG. 9 is a graph showing the temperature dependence of the pressure sensitive system. The horizontal axis of FIG. 9 represents the elapsed time in seconds. The vertical axis of FIG. 9 represents the fluctuation of the voltage value of the fourth output signal by the volatility. The broken line P indicates the volatility of the voltage value measured based on the phase of the pressure sensitive system 100 of the present embodiment, and the solid line R is the voltage value measured based on the resistance value of the pressure sensitive system of the prior art. It shows the volatility. The elapsed time T1 shown on the horizontal axis indicates that heating was started while maintaining a state in which a predetermined load N was applied to the pressure sensitive system 100 and the pressure sensitive system of the prior art, and the elapsed time T2 stopped heating. It shows the point that was done.

The elapsed time 0 to T1 is a constant temperature section at room temperature, the elapsed time T1 to T2 is a heating section from room temperature to about 200 ° C., and after the elapsed time T2 is about 200 ° C. It is a section of natural heat dissipation. As can be seen from the comparison between the broken line P and the solid line R, the voltage value measured by the pressure-sensitive system of the prior art fluctuates by up to 25% due to the temperature change of the surrounding environment. On the other hand, the volatility of the voltage value measured by the pressure sensitive system 100 is within 1%, and it can be seen that the temperature characteristics of the pressure sensitive system 100 are extremely excellent.

According to this embodiment, the following effects can be obtained.
The pressure-sensitive system 100 includes a voltage waveform output unit 10 that outputs a first voltage waveform, a pressure-sensitive unit 20 that outputs a second voltage waveform corresponding to an applied load N, and a first voltage waveform and a second voltage waveform. It is provided with a detection unit 40 that detects the load N based on the phase with and. The detection unit 40 detects the load N applied to the pressure sensitive unit 20 according to the phase of the first voltage waveform and the second voltage waveform. The inventors have found that the signal output according to the phase has extremely small fluctuation with respect to the temperature change of the ambient temperature. As a result, it is possible to provide the pressure sensitive system 100 which is excellent in temperature characteristics and has improved measurement accuracy of the load N as a pressure.

The voltage waveform output unit 10 outputs a first voltage waveform at the resonance frequency of the pressure sensitive unit 20. The resonance frequency is the frequency at which the impedance is the smallest, and the noise component of the second voltage waveform output from the pressure sensitive unit 20 becomes small, so that the measurement accuracy of the load N is improved.

The detection unit 40 generates DC voltages having different voltage values according to the phase difference between the phases of the first voltage waveform and the second voltage waveform. Thereby, the phase change of the second voltage waveform, that is, the load N applied to the pressure sensitive unit 20, can be easily detected.

The pressure sensitive portion 20 has a comb-shaped first electrode 21 and a second electrode 22. By separating the first electrode 21 and the second electrode 22 so that the comb teeth mesh with each other, the first electrode 21 and the second electrode 22 are prevented from coming into contact with each other. Can be efficiently arranged on the upper surface 23a side of the semiconductor substrate 23.

The pressure sensitive unit 20 has a semiconductor substrate 23 made of a silicon substrate. Since the silicon substrate is excellent in mechanical strength, the reliability of the pressure sensitive portion 20 is improved.

The detection unit 40 includes a frequency conversion circuit 30 that converts a predetermined frequency into a frequency lower than the predetermined frequency. Since the frequencies of the first and second voltage waveforms are converted to lower frequencies by the frequency conversion circuit 30, the accuracy of detecting the phase change is improved.

The pressure-sensitive method includes a first output step of outputting a first voltage waveform from the voltage waveform output unit 10, a second output step of outputting a second voltage waveform corresponding to a load N applied to the pressure-sensitive unit 20, and a second output step. It has a detection step of detecting a load N based on the phase of the first voltage waveform and the second voltage waveform. In the detection step, the load N applied to the pressure sensitive unit 20 is detected according to the phases of the first voltage waveform and the second voltage waveform. The inventors have found that the signal output according to the phase has extremely small fluctuation with respect to the temperature change of the ambient temperature. This makes it possible to provide a pressure-sensitive method having excellent temperature characteristics and improved measurement accuracy of the load N as pressure.

In the first output step, the first voltage waveform is output from the voltage waveform output unit 10 at the resonance frequency of the pressure sensitive unit 20. The resonance frequency is the frequency at which the impedance is the smallest, and the noise component of the second voltage waveform output from the pressure sensitive unit 20 becomes small, so that the measurement accuracy of the load N is improved.

In the detection step, DC voltages having different voltage values are generated according to the phase difference between the phases of the first voltage waveform and the second voltage waveform. Thereby, the phase change of the second voltage waveform, that is, the load N applied to the pressure sensitive unit 20, can be easily detected.

In the frequency conversion step in the detection step, the frequencies of the first and second voltage waveforms are converted from a predetermined frequency to a frequency lower than a predetermined frequency. Since the frequencies of the first and second voltage waveforms are converted to lower frequencies by the frequency conversion circuit 30, the accuracy of detecting the phase change is improved.

2. Embodiment 2
FIG. 10 is a block diagram showing the configuration of the pressure sensitive system according to the second embodiment. The pressure-sensitive system 200 of the present embodiment has a different configuration of the detection unit 40 of the first embodiment. For the same constituent parts as in the first embodiment, the same numbers will be used, and duplicate description will be omitted.

The pressure-sensitive system 200 includes a voltage waveform output unit 10, a pressure-sensitive unit 20, and a detection unit 240. The detection unit 240 includes a frequency conversion circuit 30, a first limiter 41, a second limiter 42, and a measurement unit 245.

In the detection step, the detection unit 240 detects the load N applied to the pressure sensitive unit 20 based on the time difference between the phases of the first voltage waveform and the second voltage waveform. The measuring unit 245 measures the time difference between the time at a predetermined phase angle of the first output signal output from the first limiter 41 and the time at a predetermined phase angle of the second output signal output from the second limiter 42. To do. Thereby, the phase change of the second voltage waveform, that is, the load N applied to the pressure sensitive unit 20, can be easily detected. Since the signal output according to the phase has extremely small fluctuation with respect to the temperature change of the ambient temperature, it is possible to provide the pressure sensitive system 200 having excellent temperature characteristics and improved measurement accuracy of the load N as the pressure.

3. 3. Embodiment 3
FIG. 11 is a block diagram showing the configuration of the pressure sensitive system according to the third embodiment. The pressure-sensitive system 300 of the present embodiment has a different configuration of the detection unit 40 of the first embodiment. For the same constituent parts as in the first embodiment, the same numbers will be used, and duplicate description will be omitted.

The pressure-sensitive system 300 includes a voltage waveform output unit 10, a pressure-sensitive unit 20, and a detection unit 340. The detection unit 340 includes a frequency conversion circuit 330 and a measurement unit 45, and the frequency conversion circuit 330 includes a mixer 332 and a low frequency pass filter 334.

The first voltage waveform output from the voltage waveform output unit 10 and the second voltage waveform output from the pressure sensitive unit 20 are input to the mixer 332. For example, the mixer 332 has a frequency component of 100 MHz added and a frequency component of 0 MHz subtracted from the first voltage waveform having a frequency of 50 MHz and a second voltage waveform having a frequency equal to the frequency of the first voltage waveform, that is, 0 MHz. A signal including a DC component is output to the low frequency pass filter 334.

The low frequency pass filter 334 suppresses a frequency component of 100 MHz and a frequency component having a predetermined frequency or higher including unnecessary harmonics from the input signal, and outputs a signal that has passed the DC component. As a result, the frequency conversion circuit 330 converts a voltage waveform signal having a frequency of 50 MHz into a DC signal. The signal output from the low-pass filter 334 is a DC voltage having a different voltage value according to the phase fluctuation of the second voltage waveform, and is applied to the pressure-sensitive unit 20 by measuring this with the measuring unit 45. The load N can be obtained. Since the signal output according to the phase has extremely small fluctuation with respect to the temperature change of the ambient temperature, it is possible to provide the pressure sensitive system 300 which is excellent in temperature characteristics and has improved the measurement accuracy of the load N as the pressure.

4. Embodiment 4
FIG. 12 is a cross-sectional view showing the configuration of the pressure sensitive portion according to the fourth embodiment. The pressure-sensitive system 400 of the present embodiment has a different configuration of the pressure-sensitive unit 20 described in the first embodiment. For the same constituent parts as in the first embodiment, the same numbers will be used, and duplicate description will be omitted.

The pressure-sensitive unit 420 has a first electrode 421 and a second electrode 422 as a pair of electrodes, and a conductive resin 423 sandwiched between the first electrode 421 and the second electrode 422. Specifically, the pressure-sensitive portion 420 is a second electrode arranged in contact with the conductive resin 423, the first electrode 421 arranged in contact with the upper surface 423a of the conductive resin 423, and the lower surface 423b of the conductive resin 423. It has a 422, a first support substrate 424 that supports the first electrode 421, and a second support substrate 425 that supports the second electrode 422. The first and second electrodes 421 and 422 are parallel plate electrodes facing each other via the conductive resin 423. The shapes of the first and second electrodes 421 and 422 are not particularly limited, and can be formed of a circle, a rectangle, or the like in a plan view.

The first support substrate 424 is provided above the first electrode 421 and supports the first electrode 421 with respect to the conductive resin 423. The second support substrate 425 is provided above the second electrode 422 and supports the second electrode 422 with respect to the conductive resin 423. The first and second support substrates 424 and 425 may be hard or soft, but in the present embodiment, a flexible printed wiring board having flexibility is used.

The first electrode 421 is connected to the lead wire connected to the voltage waveform output unit 10, and the second electrode 422 is connected to the lead wire connected to the second mixer 35. Note that, in FIG. 12, the drawing of the lead-out wiring is omitted.
The conductive resin 423 is formed in the form of a sheet by dispersing and containing conductive particles such as carbon in silicone. The resin material of the conductive resin 423 is not limited to silicone, and urethane, epoxy and the like can be used.

The pressure-sensitive unit 420 configured in this way receives the first voltage waveform and outputs the second voltage waveform corresponding to the applied load N. Specifically, the first electrode 421 and the second electrode 422 configured in the pressure sensitive portion 420 generate a series capacitance via the conductive resin 423. Since the conductive resin 423 has flexibility, when a load N is applied in the thickness direction of the pressure sensitive portion 420, the conductive resin 423 is compressed and the distance between the first electrode 421 and the second electrode 422 becomes narrower. , The series capacity becomes large. The fluctuation of the series capacitance changes the phase of the first voltage waveform input to the pressure sensitive unit 420. That is, the pressure sensitive unit 420 outputs a second voltage waveform in which the phase of the input first voltage waveform is changed according to the applied load N. By using such a pressure sensitive unit 420, a pressure sensitive system 400 capable of obtaining the load N applied to the pressure sensitive unit 420 based on the phase of the first voltage waveform and the second voltage waveform can be configured. .. Since the signal output according to the phase has extremely small fluctuation with respect to the temperature change of the ambient temperature, it is possible to provide the pressure sensitive system 400 which is excellent in temperature characteristics and has improved the measurement accuracy of the load N as the pressure.

The contents derived from the embodiment are described below.

The pressure-sensitive system is connected to a voltage waveform output unit that outputs a first voltage waveform and the voltage waveform output unit to receive the first voltage waveform, and the phase of the first voltage waveform is adjusted according to the applied pressure. A pressure-sensitive unit that outputs a fluctuating second voltage waveform, and a detection unit that is connected to the voltage waveform output unit and the pressure-sensitive unit and receives the first voltage waveform and the second voltage waveform. The detection unit is characterized in that the pressure is detected based on the phase of the first voltage waveform and the phase of the second voltage waveform.

According to this configuration, the detection unit detects the pressure using the phase of the first voltage waveform input to the pressure sensitive unit and the second voltage waveform output from the pressure sensitive unit as an index. When an AC voltage is applied to the pressure-sensitive part, the inventors change the phase according to the pressure applied to the pressure-sensitive part, and the phase is stable with respect to the temperature change due to the ambient environment, that is, the temperature. It was found that the characteristics were good. This makes it possible to provide a pressure-sensitive system that improves the accuracy of pressure measurement.

In the pressure-sensitive system, the frequency of the first voltage waveform is preferably a resonance frequency in the pressure-sensitive portion.

According to this configuration, a first voltage waveform, which is the resonance frequency of the pressure-sensitive unit, is input to the pressure-sensitive unit. Since the impedance of the resonance frequency is the smallest, the noise component of the second voltage waveform output from the pressure-sensitive unit is reduced, and the pressure measurement accuracy is improved.

In the pressure-sensitive system, the detection unit preferably detects the pressure based on the phase difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

According to this configuration, the detection unit obtains the phase change of the second voltage waveform output from the pressure sensitive unit by the phase difference between the first voltage waveform and the second voltage waveform. As a result, the phase change of the second voltage waveform can be easily detected.

In the pressure-sensitive system, the detection unit preferably detects the pressure based on the time difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

According to this configuration, the detection unit obtains the phase change of the second voltage waveform output from the pressure sensitive unit by the time difference between the first voltage waveform and the second voltage waveform at a predetermined phase angle. As a result, the phase change of the second voltage waveform can be easily detected.

In the pressure-sensitive system, the pressure-sensitive portion has a first electrode and a second electrode, and the first electrode and the second electrode are comb-teeth-like electrodes in which comb teeth are arranged so as to mesh with each other. Is preferable.

According to this configuration, by using the first electrode and the second electrode as comb-shaped electrodes, the first electrode and the second electrode are arranged on the same plane while preventing the contact between the first electrode and the second electrode. can do.

In the pressure-sensitive system, the pressure-sensitive portion is preferably a silicon substrate.

According to this configuration, the silicon substrate is excellent in mechanical strength, so that the reliability of the pressure sensitive portion is improved.

In the pressure-sensitive system, the pressure-sensitive portion preferably has a pair of electrodes and a conductive resin sandwiched between the pair of electrodes.

According to this configuration, even in a pressure-sensitive part made of a conductive resin sandwiched between a pair of electrodes, a phenomenon in which the phase changes according to the applied pressure can be obtained, so that the pressure-sensitive system improves the pressure measurement accuracy. Can be provided.

In the pressure-sensitive system, it is preferable to have a frequency conversion circuit that converts the frequencies of the received first voltage waveform and the second voltage waveform into lower frequencies.

According to this configuration, the first and second voltage waveforms are converted to low frequencies, so that the accuracy of detecting the phase change is improved.

The pressure-sensitive method includes a voltage waveform output unit that outputs a predetermined voltage waveform, a pressure-sensitive unit that detects pressure, and a detection unit that detects pressure based on the voltage waveform output unit and the output signals from the pressure-sensitive unit. A pressure-sensitive method using a pressure-sensitive system, wherein the voltage waveform output unit outputs a first voltage waveform, and the pressure-sensitive unit receives the first voltage waveform and is applied. The second output step of outputting the second voltage waveform in which the phase of the first voltage waveform fluctuates according to the pressure, and the detection unit receives the first voltage waveform and the second voltage waveform, and the first voltage It is characterized by including a detection step of detecting the pressure based on the phase of the waveform and the phase of the second voltage waveform.

According to this method, in the detection step, the detection unit detects the pressure using the phase of the first voltage waveform input to the pressure sensitive unit and the second voltage waveform output from the pressure sensitive unit as an index. When an AC voltage is applied to the pressure-sensitive part, the inventors change the phase according to the pressure applied to the pressure-sensitive part, and the phase is stable with respect to the temperature change due to the ambient environment, that is, the temperature. It was found that the characteristics were good. This makes it possible to provide a pressure-sensitive method for improving the accuracy of pressure measurement.

In the above pressure-sensitive method, the frequency of the first voltage waveform is preferably a resonance frequency in the pressure-sensitive portion.

According to this method, in the first output step, the voltage waveform output unit outputs the first voltage waveform which is the resonance frequency of the pressure sensitive unit. Since the impedance of the resonance frequency is the smallest, the noise component of the second voltage waveform output from the pressure-sensitive unit is reduced, and the pressure measurement accuracy is improved.

In the above pressure-sensitive method, it is preferable that the detection step detects the pressure based on the phase difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

According to this method, in the detection step, the detection unit obtains the phase change of the second voltage waveform by the phase difference between the first voltage waveform and the second voltage waveform. As a result, the phase change of the second voltage waveform can be easily detected.

In the above pressure-sensitive method, it is preferable that the detection step detects the pressure by the time difference between the phase of the first voltage waveform and the phase of the second voltage waveform.

According to this method, in the detection step, the phase change of the second voltage waveform output from the pressure sensitive unit is obtained by the time difference between the first voltage waveform and the second voltage waveform at a predetermined phase angle. As a result, the phase change of the second voltage waveform can be easily detected.

In the above pressure-sensitive method, the detection step preferably includes a frequency conversion step of converting the frequencies of the received first voltage waveform and the second voltage waveform into lower frequencies.

According to this method, in the frequency conversion step, the frequencies of the first and second voltage waveforms are converted to low frequencies, so that the accuracy of detecting the phase change is improved.

10 ... Voltage waveform output unit, 20,420 ... Pressure sensitive unit, 21,421 ... First electrode, 22,422 ... Second electrode, 23 ... Semiconductor substrate, 30,330 ... Frequency conversion circuit, 40, 240, 340 ... Detection unit, 100, 200, 300, 400 ... Pressure sensitive system, 423 ... Conductive resin.

Claims (13)

A voltage waveform output unit that outputs the first voltage waveform and
A pressure-sensitive unit that is connected to the voltage waveform output unit to receive the first voltage waveform and outputs a second voltage waveform in which the phase of the first voltage waveform fluctuates according to the applied pressure.
It is provided with a voltage waveform output unit and a detection unit connected to the pressure sensitive unit and receiving the first voltage waveform and the second voltage waveform.
The detection unit detects the pressure based on the phase of the first voltage waveform and the phase of the second voltage waveform.
A pressure sensitive system featuring. The frequency of the first voltage waveform is the resonance frequency in the pressure sensitive portion.
The pressure-sensitive system according to claim 1. The detection unit detects the pressure based on the phase difference between the phase of the first voltage waveform and the phase of the second voltage waveform.
The pressure-sensitive system according to claim 1 or 2. The detection unit detects the pressure based on the time difference between the phase of the first voltage waveform and the phase of the second voltage waveform.
The pressure-sensitive system according to claim 1 or 2. The pressure sensitive portion has a first electrode and a second electrode, and has a first electrode and a second electrode.
The first electrode and the second electrode are comb-teeth-like electrodes in which comb teeth are arranged so as to mesh with each other.
The pressure-sensitive system according to any one of claims 1 to 4. The pressure-sensitive part is a silicon substrate.
The pressure-sensitive system according to any one of claims 1 to 5. The pressure-sensitive portion has a pair of electrodes and a conductive resin sandwiched between the pair of electrodes.
The pressure-sensitive system according to any one of claims 1 to 4. The detection unit has a frequency conversion circuit that converts the frequencies of the received first voltage waveform and the second voltage waveform into lower frequencies.
The pressure-sensitive system according to any one of claims 1 to 6, wherein the pressure-sensitive system is characterized. A pressure-sensitive system having a voltage waveform output unit that outputs a predetermined voltage waveform, a pressure-sensitive unit that detects pressure, and a pressure-sensitive unit that detects pressure based on the voltage waveform output unit and output signals from the pressure-sensitive unit. It is a pressure-sensitive method by
The first output step in which the voltage waveform output unit outputs the first voltage waveform, and
A second output step in which the pressure-sensitive unit receives the first voltage waveform and outputs a second voltage waveform in which the phase of the first voltage waveform fluctuates according to the applied pressure.
The detection unit includes a detection step of receiving the first voltage waveform and the second voltage waveform and detecting the pressure based on the phase of the first voltage waveform and the phase of the second voltage waveform. ,
A pressure-sensitive method characterized by. The frequency of the first voltage waveform is the resonance frequency in the pressure sensitive portion.
9. The pressure-sensitive method according to claim 9. In the detection step, the pressure is detected based on the phase difference between the phase of the first voltage waveform and the phase of the second voltage waveform.
The pressure-sensitive method according to claim 9 or 10. In the detection step, the pressure is detected by the time difference between the phase of the first voltage waveform and the phase of the second voltage waveform.
The pressure-sensitive method according to claim 9 or 10. The detection step includes a frequency conversion step of converting the frequencies of the received first voltage waveform and the second voltage waveform into lower frequencies.
The pressure-sensitive method according to any one of claims 9 to 12, wherein the pressure-sensitive method is characterized.

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