Pressure distribution measurement system, pressure distribution measurement method, pressure distribution measurement program, and measurement circuit for differential amplification measurement

Abstract

To estimate actual pressure distribution from electrical signals observed at a plurality of measurement locations when using a matrix sensor in which a plurality of voltage measurement locations is arranged for a piezoelectric body and in which an electrode is shared in the plurality of measurement locations.SOLUTION: A pressure distribution measurement device satisfies, for each of identification numbers i, j of measurement locations of a matrix sensor, a constraint expression between a measurement signal yi observed at a plurality of measurement locations, a true signal xi for the measurement signal yi, a true signal xj for a measurement signal yj, and a variable ti indicating an error between the measurement signal yi and the true signals xi, xj, and solves linear programming so that the sum of the variables ti indicating the error is minimized, to remove crosstalk from each of the measurement signals yi, and calculate each of the true signals xi at the plurality of measurement locations.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a pressure distribution measurement system, a pressure distribution measurement method, a pressure distribution measurement program, and a measurement circuit for differential amplification measurement. [Background technology]

[0002] Conventionally, there is known a piezoelectric sensor capable of detecting position and load within the piezoelectric sensor (see, for example, Patent Document 1). This piezoelectric sensor is a piezoelectric sensor in which a piezoelectric layer is sandwiched between an upper electrode and a lower electrode, and the upper electrode is configured to include a plurality of first pattern electrodes extending in one direction, and the lower electrode is configured to include a plurality of second pattern electrodes extending in another direction intersecting the one direction, and measures the load from the amount of generated charge and identifies the position from the electrode in which the charge is generated.

[0003] Also, an acoustic wave concentrator and an acoustic inkjet recording device that can reliably prevent crosstalk are known (see, for example, Patent Document 2). Patent Document 2 discloses that in the acoustic wave concentrator, a piezoelectric body is sandwiched at a location where a plurality of drive electrodes connected in series in the vertical direction and a plurality of counter electrodes connected in series in the horizontal direction intersect on the surface of an insulating member on the opposite side of the fixed substrate from the acoustic Fresnel lens.

[0004] In addition, an occlusal pressure measuring device is known that measures occlusal force by providing electrodes on the top and bottom of a polymeric piezoelectric material and measuring the piezoelectricity between the electrodes generated when the polymeric piezoelectric material is subjected to stress (see, for example, Patent Document 3).

[0005] Also known is a biometric information processing device that includes a noise reduction processing unit that calculates an error signal by subtracting body movement noise contained in an observation signal from a first sensor unit that measures bioemotion as an observation signal, based on a body movement signal from a second sensor unit that measures changes in body movement and / or a pressure signal from a third sensor unit that measures changes in pressure between the skin (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-235133 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-210950 [Patent Document 3] Japanese Patent Application Publication No. 57-168635 [Patent Document 4] Japanese Patent Publication No. 2020-10803 Summary of the Invention [Problem to be solved by the invention]

[0007] Consider a pressure distribution measurement system in which multiple electrodes are placed on a planar piezoelectric body to detect where force is generated on the piezoelectric body. In this case, there are two patterns, as shown in Figure 20, for connecting the multiple electrodes to the multiple measurement points that measure the voltage generated on the planar piezoelectric body.

[0008] In Fig. 20, a circle represents one measurement point, and a line represents an electrode through which an electrical signal propagates. The diagram on the left side of Fig. 20 shows a pattern in which one electrode is connected to one measurement point (hereinafter simply referred to as the island method). The diagram on the right side of Fig. 20 shows a pattern in which an electrode is shared by multiple measurement points (hereinafter simply referred to as the matrix method).

[0009] In the island-type wiring pattern shown in Figure 20, electrodes must be connected to the top and bottom of the planar piezoelectric element at one measurement point. Therefore, if there are n x m measurement points, 2(n x m) wires are required.

[0010] On the other hand, in the matrix wiring pattern of FIG. 20 , for example, the vertical wiring of the piezoelectric element is arranged so as to be shared among multiple measurement points on the top surface of the piezoelectric element, and the horizontal wiring of the piezoelectric element is arranged so as to be shared among multiple measurement points on the bottom surface of the piezoelectric element. In the example shown in FIG. 20 , the vertical wiring ch_y0, ch_y1, ch_y2, and ch_y3 are arranged so as to be shared among multiple measurement points on the top surface of the piezoelectric element, and the horizontal wiring ch_x0, ch_x1, ch_x2, and ch_x3 are arranged so as to be shared among multiple measurement points on the bottom surface of the piezoelectric element. Therefore, with the matrix wiring pattern of FIG. 20 , even if there are n × m measurement points, only n + m wires are required. Because the electrode wiring is simpler in the matrix wiring pattern than in the island wiring pattern, it is expected that its applications will be broader.

[0011] However, when the island method is adopted, for example, when pressure "Press" occurs at the position shown in Fig. 21, not only is a voltage detected at the measurement point at that position, but voltage is also detected at other measurement points that share the electrodes ch_x0 and ch_y1. In this way, when electrodes are shared among multiple measurement points, electrical signals are generated at measurement points other than the position where pressure occurs, which is also called "crosstalk."

[0012] Therefore, in a matrix sensor employing the matrix method shown in FIG. 20, there is a problem in that the position where pressure is generated cannot be detected with high accuracy due to the occurrence of crosstalk as described above.

[0013] The present disclosure has been made in consideration of the above circumstances, and aims to estimate actual pressure distribution from electrical signals observed at multiple measurement points when using a matrix sensor in which multiple voltage measurement points are arranged on a piezoelectric body and electrodes are shared among the multiple measurement points. [Means for solving the problem]

[0014] A first aspect of the present disclosure is a pressure distribution measurement system comprising: a matrix sensor including a piezoelectric body, a plurality of upper electrodes arranged to extend in a first direction and arranged above the piezoelectric body, and a plurality of lower electrodes arranged to extend in a second direction intersecting the first direction and arranged below the piezoelectric body; and a pressure distribution measurement device, wherein the pressure distribution measurement device acquires measurement signals representing differences between signals output from the upper electrodes and signals output from the lower electrodes at each of measurement locations corresponding to positions where the plurality of upper electrodes and the plurality of lower electrodes intersect, and for each of the target measurement locations, acquires a measurement signal representing a difference between the measurement signal measured at the target measurement location and a measurement signal measured at another measurement location different from the target measurement location and corresponding to the target measurement location. A first value is calculated as the sum of the differences between the measurement signals measured at the target measurement point and at a measurement point where a common upper electrode is arranged; a second value is calculated as the sum of the differences between the measurement signal measured at the target measurement point and a measurement point other than the target measurement point where a common lower electrode is arranged with respect to the target measurement point; if there is one measurement point where the first value is positive and the second value is positive, the measurement point is determined to be a pressure point; if there are two or more measurement points where the first value is positive and the second value is positive, a measurement signal y observed at the plurality of measurement points for each of the measurement point identification numbers i and j is calculated; i and the measurement signal y i True signal x for i and the measurement signal y j True signal x for j and the measurement signal y i and the true signal x i ,x j Variable t representing the error between i The variable t representing the error is set while satisfying the following constraint (1A) between i The measurement signal y is calculated by solving the linear programming problem so that equation (2A) is minimized. i and remove the crosstalk from each of the points to obtain the true signal x i This is a pressure distribution measurement system that calculates each of the above.

[0015]

number

[0016] A second aspect of the present disclosure is a pressure distribution measurement system including a matrix sensor including a first piezoelectric element, a second piezoelectric element, a plurality of first upper electrodes arranged to extend in a first direction and disposed on top of the first piezoelectric element, a plurality of first lower electrodes arranged to extend in the first direction and disposed on bottom of the first piezoelectric element, a plurality of second upper electrodes arranged to extend in a second direction intersecting the first direction and disposed on top of the second piezoelectric element, a plurality of second lower electrodes arranged to extend in the second direction and disposed on bottom of the second piezoelectric element, and an insulating layer disposed between the plurality of first lower electrodes in the first piezoelectric element and the plurality of second upper electrodes in the second piezoelectric element, and a pressure distribution measurement device, in which the pressure distribution measurement device acquires a first measurement signal output from the first upper electrode and a second measurement signal output from the second lower electrode at each of measurement locations corresponding to positions where the plurality of first upper electrodes and the plurality of second lower electrodes intersect, and generates a first measurement signal y for each of the measurement location identification numbers i and j for each of the target measurement locations. i and weights for multiple measurement points w ij and the second measurement signal y j and the first measurement signal y i the second measurement signal x j and weight w ij The variable t represents the error when expressing it as a weighted sum of i While satisfying the following constraint (1B) regarding i By solving the linear programming method so that equation (2B) representing the sum of i This is a pressure distribution measurement system that calculates the pressure distribution.

[0017]

number

[0018] According to the present disclosure, when a matrix sensor is used in which multiple voltage measurement points are arranged on a piezoelectric body and electrodes are shared among the multiple measurement points, it is possible to obtain the effect that the actual pressure distribution can be estimated from the electrical signals observed at the multiple measurement points. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing a schematic configuration of a pressure distribution measurement system according to a first embodiment. [Figure 2] FIG. 2 is a diagram for explaining a matrix sensor according to the first embodiment. [Figure 3] FIG. 1 is a specific schematic diagram of a measurement circuit for single-ended measurement. [Figure 4] FIG. 1 is a specific schematic diagram of a measurement circuit for differential amplification measurement. [Figure 5] FIG. 1 is a schematic diagram of an experimental matrix sensor. [Figure 6] FIG. 10 is a diagram of a measurement signal when using a measurement circuit for single-ended measurement. [Figure 7] FIG. 10 is a diagram of a measurement signal when a measurement circuit for differential amplification measurement is used. [Figure 8] FIG. 1 is a diagram for explaining the principle of differential amplification measurement. [Figure 9] FIG. 10 is a schematic diagram showing a case where two pressure points are applied to a piezoelectric body. [Figure 10] FIG. 10 is a diagram showing a list of measurement signals at each measurement point. [Figure 11] FIG. 1 is a diagram illustrating a hardware configuration of a pressure distribution measuring apparatus according to an embodiment. [Figure 12] 10 is an example of a pressure distribution measurement processing routine according to the embodiment. [Figure 13] FIG. 10 is a diagram showing a schematic configuration of a pressure distribution measurement system according to a second embodiment. [Figure 14] FIG. 10 is a schematic diagram of a matrix sensor according to a second embodiment. [Figure 15] FIG. 10 is a schematic diagram of a matrix sensor according to a second embodiment. [Figure 16] 10A and 10B are diagrams for explaining a measurement signal when the matrix sensor of the second embodiment is used. [Figure 17] 10 is an example of a pressure distribution measurement processing routine according to the second embodiment. [Figure 18] 1 shows a pressure distribution measurement system manufactured in an example. [Figure 19] FIG. 10 is a diagram showing experimental results of an example. [Figure 20] FIG. 1 is a diagram for explaining a matrix sensor system. [Figure 21] FIG. 1 is a diagram for explaining a matrix sensor system. DETAILED DESCRIPTION OF THE INVENTION

[0020] An example of an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals are used throughout the drawings to designate identical or equivalent components and parts. The dimensional proportions of the drawings are exaggerated for illustrative purposes and may differ from the actual proportions.

[0021] (Pressure distribution measurement system 10 of the first embodiment) Fig. 1 is a diagram showing a schematic configuration of a pressure distribution measurement system 10 according to the first embodiment. As shown in Fig. 1, the pressure distribution measurement system 10 of this embodiment includes a matrix sensor 12, a measurement circuit 14, and a pressure distribution measurement device 16.

[0022] The pressure distribution measuring system 10 of the first embodiment uses a single-layer matrix sensor as the matrix sensor 12. This will be explained in detail below.

[0023] FIG. 2 is a diagram illustrating the matrix sensor 12 of the first embodiment. Note that FIG. 2 shows only a portion of the matrix sensor 12. As shown in FIG. 2, the matrix sensor 12 includes a piezoelectric body 18, a plurality of upper electrodes 20A, 20B, and 20C, and a plurality of lower electrodes 22A and 22B. Note that hereinafter, unless a specific electrode is being indicated, they will be simply referred to as "upper electrode 20" and "lower electrode 22."

[0024] The piezoelectric body 18 is an organic piezoelectric body such as PVDF (polyvinylidene fluoride). When a force is applied to the piezoelectric body 18, an electric charge corresponding to the force is generated on the surface of the piezoelectric body 18, and a voltage is generated at the point where the force is applied.

[0025] 2, the plurality of upper electrodes 20A, 20B, and 20C are arranged to extend in a first direction and are disposed above the piezoelectric body 18. Also, as shown in FIG. 2, the plurality of lower electrodes 22A and 22B are arranged to extend in a second direction intersecting the first direction and are disposed below the piezoelectric body 18.

[0026] Voltage measurement points S correspond to positions where the plurality of upper electrodes 20A, 20B, and 20C intersect with the plurality of lower electrodes 22A and 22B. 0,0 ,S 0,1 ,S 1,0 ,S 1,1 ,S 2,0 ,S 2,1 Each of them functions as one sensor element. In the following, the locations where the plurality of upper electrodes 20A, 20B, 20C and the plurality of lower electrodes 22A, 22B intersect will be simply referred to as "measurement locations."

[0027] In the matrix sensor 12 shown in FIG. 2, the upper electrode 20 and the lower electrode 22 are common, and there is only one piezoelectric body 18, so crosstalk occurs.

[0028] Therefore, the pressure distribution measurement system 10 of the first embodiment removes crosstalk from each measurement signal measured by a single-layer matrix sensor 12 as shown in Fig. 2, and calculates true signals at multiple measurement points. This makes it possible to estimate the actual pressure distribution from which crosstalk has been removed, even when using a matrix sensor in which crosstalk occurs.

[0029] The measurement circuit 14 outputs a measurement signal representing the difference between the signal output from the upper electrode 20 and the signal output from the lower electrode 22 .

[0030] FIG. 3 shows a specific schematic diagram of the measurement circuit 14A for single-ended measurement.

[0031] As shown in FIG. 3, the measurement circuit 14 for single-ended measurement includes a multiplexer 26, a charge amplifier circuit 28, a Twin-T circuit 30, and an A / D converter 32, which is an analog-to-digital converter.

[0032] The multiplexer 26 detects by switching between the signals output from the plurality of lower electrodes 22 A and 22 B. Specifically, the multiplexer 26 performs a switching operation to switch between the output terminals ch_y0, ch_y1, and ch_y2.

[0033] The charge amplifier circuit 28 includes a resistor R, a capacitor C, and an operational amplifier OP. The charge amplifier circuit 28 converts the charge response into a voltage response.

[0034] The Twin-T circuit 30 is a type of notch filter circuit that removes signals of a specific frequency.

[0035] The A / D converter 32 converts the input analog signal into a digital signal. The digital signal output from the A / D converter 32 is input to the pressure distribution measuring device 16.

[0036] Note that the measurement circuit 14 may be not only a single-ended measurement type as shown in FIG. 3, but also a differential amplification measurement type. FIG. 4 shows a specific schematic diagram of the measurement circuit 14 for differential amplification measurement. As shown in FIG. 4, the measurement circuit 14B for differential amplification measurement further includes a charge amplifier circuit 28A that receives signals output from the plurality of upper electrodes 20A, 20B, and 20C, and a charge amplifier circuit 28B that receives signals output from the plurality of lower electrodes 22A and 22B. Furthermore, as shown in FIG. 4, the measurement circuit 14B for differential amplification measurement further includes a differential amplifier circuit 28C that amplifies the difference between the signal output from the upper electrode 20 and the signal output from the lower electrode 22.

[0037] Here, the difference between the measurement circuit 14A for single-ended measurement and the measurement circuit 14B for differential amplification measurement will be described.

[0038] Consider the case where a pressure "Press" is applied to the measurement point shown in the schematic diagram of the experimental matrix sensor shown in Fig. 5. In this case, as shown in Fig. 5, the signal output from the lower electrode of ch_y0 is either grounded ("Grand" in Fig. 5) or input to a differential amplifier circuit ("Differential" in Fig. 5).

[0039] Grounding the signal output from the lower electrode of ch_y0 in Fig. 5 ("Grand" in Fig. 5) corresponds to using measurement circuit 14A for single-ended measurement. On the other hand, inputting the signal output from the lower electrode of ch_y0 in Fig. 5 to a differential amplifier circuit ("Differential" in Fig. 5) corresponds to using measurement circuit 14B for differential amplifier measurement.

[0040] FIG. 6 shows the measurement signals of ch_x0 and ch_x1 when using the measurement circuit 14A for single-ended measurement. The vertical axis of FIG. 6 represents the amount of charge, and the horizontal axis represents time. As shown in FIG. 6, a measurement signal is detected at ch_x0, which is the pressure point, and a measurement signal is also detected at ch_x1, which is not the pressure point. It is presumed that the measurement signal detected at ch_x1, which is not the pressure point, is detected due to the deflection of the piezoelectric element 18, etc.

[0041] FIG. 7 shows the measurement signals of ch_x0 and ch_x1 when using the measurement circuit 14B for differential amplification measurement. The measurement signal when using the measurement circuit 14B for differential amplification measurement is a signal obtained by amplifying the difference between the signal output from the upper electrode 20 and the signal output from the lower electrode 22. Therefore, as shown in the upper diagram of FIG. 7, a positive measurement signal is also detected in ch_x1. The lower diagram of FIG. 7 shows the signal ratio between the measurement signals of ch_x0 and ch_x1. As shown in the lower diagram of FIG. 7, a comparison of the measurement signals of ch_x0 and ch_x1 reveals that the ratio is approximately 1:2.

[0042] A diagram for explaining this principle is shown in Figure 8. As shown in Figure 8, when pressure is applied at the location indicated by the arrow, a +Q charge is generated on the upper surface of piezoelectric body 18 corresponding to that measurement location, and a -Q charge is generated on the lower surface of piezoelectric body 18. Furthermore, this +Q charge becomes a signal output from the upper electrode ch_x0, and the -Q charge becomes a signal output from the lower electrode ch_y0.

[0043] Here, the measurement point S corresponding to the pressure point 0,0 , a charge of +Q is generated on the upper surface of the piezoelectric body 18, and a charge of −Q is generated on the lower surface of the piezoelectric body 18. Therefore, the measurement signal representing the difference between the signal output from the upper electrode ch_x0 and the signal output from the lower electrode ch_y0 corresponds to a charge of 2Q.

[0044] On the other hand, for example, other measurement points S 1,0 In FIG. 1, the measurement signal representing the difference between the signal (charge 0) output from the upper electrode ch_x1 and the signal (charge −Q) output from the lower electrode ch_y0 corresponds to a charge of Q.

[0045] Also, for example, at measurement point S 0,1 In FIG. 1, the measurement signal representing the difference between the signal (charge +Q) output from the upper electrode ch_x1 and the signal (charge 0) output from the lower electrode ch_y0 corresponds to a charge of Q.

[0046] Therefore, it can be said that the ratio of the measurement signal at the measurement point at the pressure point to the measurement signal at the measurement point other than the pressure point is 2:1 in principle.

[0047] Next, we will explain the case where there are two pressure points on the piezoelectric body 18. Fig. 9 shows a schematic diagram of the case where there are two pressure points F1 and F2 on the piezoelectric body 18. Fig. 10 shows a list of measurement signals at each measurement location when there are two pressure points F1 and F2 as shown in Fig. 9.

[0048] The top graph in Figure 10 is the measurement point S 0,0 The second graph shows the measurement signal at measurement point S 0,1 The third graph shows the measurement signal at measurement point S 0,2 The graph in the fourth row shows the measurement signal at measurement point S 0,3 represents the measured signal at

[0049] As shown in Figure 10, the measurement point S 0,0 ,S 0,3 In other measurement points S 0,1 ,S 0,2 It can be seen that a higher measurement signal is obtained than that obtained with the conventional method.

[0050] Considering the relationship between a measurement signal measured at a measurement point corresponding to the pressure point and a measurement signal measured at a measurement point other than the pressure point, the following formula (A) holds.

[0051]

number

[0052] In addition, y in the above formula (A) i represents the measurement signal observed at measurement point i, and x i represents the true signal at measurement point i, and x j represents the true signal at measurement point j.

[0053] The above formula (A) expresses the measurement signal y observed at the measurement point i. i is the true signal x at the measurement point i i and the true signal x at multiple measurement points j different from the measurement point i j This is derived from the fact that, as mentioned above, the ratio of the measurement signal at the measurement point of the pressure point to the measurement signal at the measurement point other than the pressure point is 2:1.

[0054] Specifically, the measurement signal actually measured at the measurement point i is expressed as y i , the true signal x with crosstalk removed i In this case, the measurement signal y at each measurement point can be considered to be a composite wave of the true signal x at that measurement point and crosstalk due to other signals.

[0055] Furthermore, as described above, by using the measurement circuit 14B for differential amplification measurement, the ratio of the measurement signal at the measurement point at the pressure point to the measurement signal at the measurement point other than the pressure point becomes 2:1, which can be utilized, and the above formula (A) can be used. Therefore, it is considered that differential amplification measurement is an effective measurement method for measuring the voltage generated in the single-layer matrix sensor 12. Therefore, in the first embodiment, an example will be described in which the measurement circuit 14B for differential amplification measurement is used as the measurement circuit 14.

[0056] As mentioned above, the measurement point without pressure outputs a measurement signal as crosstalk that is about half the size of the measurement point with pressure. Also, as shown in Figure 10, the measurement signals corresponding to crosstalk are similar between the measurement points.

[0057] Therefore, in this embodiment, a true signal at a measurement point corresponding to a pressure point is extracted based on the similarity between measurement signals measured at the measurement point.

[0058] Specifically, first, the target measurement location is set.

[0059] Next, a first value is calculated, which is the sum of the differences between the measurement signal measured at the target measurement point and the measurement signal measured at another measurement point different from the target measurement point and having a common upper electrode with the target measurement point. Note that when calculating the difference between the measurement signals, the values ​​of the measurement signals at each time may be used, or a representative value may be used.

[0060] For example, in the example shown in FIG. 9, first, the target measurement point S 0,0 The measurement signal measured at the target measurement point S 0,0 The measurement point S where the common upper electrode (ch_x0) is located 0,1 ,S 0,2 ,S 0,3 Specifically, the difference between the measurement signal measured at measurement point S 0,0 The measurement signal measured at the measurement point S 0,1 Then, calculate the difference between the measurement signal measured at measurement point S 0,0 The measurement signal measured at the measurement point S 0,2 Then, calculate the difference between the measurement signal measured at measurement point S 0,0 The measurement signal measured at the measurement point S 0,3 Then, a first value is calculated, which is the sum of the differences.

[0061] Next, a second value is calculated, which is the sum of the differences between the measurement signal measured at the target measurement point and the measurement signal measured at another measurement point different from the target measurement point and at which a lower electrode common to the target measurement point is located.

[0062] For example, in the example shown in FIG. 9, first, the target measurement point S 0,0 The measurement signal measured at the target measurement point S 0,0 The measurement point S where the common lower electrode (ch_y0) is located 1,0 ,S 2,0 Calculate the difference between the measurement signal measured at

[0063] Specifically, measurement point S 0,0 The measurement signal measured at the measurement point S 1,0 Then, calculate the difference between the measurement signal measured at measurement point S 0,0 The measurement signal measured at the measurement point S 2,0 The difference between the measured signal measured at step 1 and step 2 is calculated, and a second value is calculated, which is the sum of these differences.

[0064] The above process is repeated by repeatedly setting all measurement points of the matrix sensor 12 as target measurement points.

[0065] If there is one measurement point where the first value is positive and the second value is positive, the measurement point is determined to be a pressure point. If there is one measurement point where the first value is positive and the second value is positive, the measurement signal obtained at that measurement point is larger than any measurement signals obtained in the vicinity, and it can be assumed that pressure is being applied only to that measurement point.

[0066] On the other hand, if there are two or more measurement points where the first value is positive and the second value is positive, an optimization process using linear programming is performed to estimate the true signal with crosstalk removed.

[0067] Specifically, for each of the measurement point identification numbers i and j, the measurement signal y observed at a plurality of measurement points is i and the measurement signal y i True signal x for i and the measurement signal y j True signal x for j and the measurement signal y i and the true signal x i ,x j Variable t representing the error between i The following constraint (1A) is satisfied between i The linear programming is solved to minimize the sum of the measured signal y i and remove the crosstalk from each of the points to obtain the true signal x i Calculate each of the following.

[0068]

number

[0069] By performing the above-described processing, the pressure distribution measuring device 16 removes crosstalk that occurs in the matrix sensor 12 and estimates the actual pressure distribution that occurs in the matrix sensor 12. Note that the true signals at multiple measurement points correspond to the actual pressure distribution.

[0070] Fig. 11 is a block diagram showing the hardware configuration of a computer that constitutes the pressure distribution measuring device 16. As shown in Fig. 11, the computer has a CPU (Central Processing Unit) 81, a ROM (Read Only Memory) 82, a RAM (Random Access Memory) 83, a storage 84, an input unit 85, a display unit 86, and a communication interface (I / F) 87. Each component is connected to each other via a bus 89 so that they can communicate with each other.

[0071] The CPU 81 is a central processing unit that executes various programs and controls each part. That is, the CPU 81 reads programs from the ROM 82 or the storage 84 and executes the programs using the RAM 83 as a work area. The CPU 81 controls the above-mentioned components and performs various arithmetic processing in accordance with the programs stored in the ROM 82 or the storage 84. In this embodiment, the ROM 82 or the storage 84 stores various programs that process information input from an input device.

[0072] The ROM 82 stores various programs and various data. The RAM 83 temporarily stores programs or data as a working area. The storage 84 is configured with an HDD (Hard Disk Drive) or an SSD (Solid State Drive) or the like, and stores various programs including the operating system and various data.

[0073] The input unit 85 includes a pointing device such as a mouse and a keyboard, and is used to perform various inputs.

[0074] The display unit 86 is, for example, a liquid crystal display, and displays various information. The display unit 86 may be a touch panel type and function as the input unit 85.

[0075] The communication I / F 87 is an interface for communicating with other devices such as an input device, and uses standards such as Ethernet (registered trademark), FDDI, and Wi-Fi (registered trademark).

[0076] Next, the operation of the pressure distribution measuring system 10 of the first embodiment will be described.

[0077] When pressure is applied to the matrix sensor 12, the differential amplifier circuit 28C of the measurement circuit 14 outputs a measurement signal representing the difference between the signal output from the upper electrode 20 and the signal output from the lower electrode 22 at each of the measurement points corresponding to the positions where the plurality of upper electrodes 20A, 20B, 20C intersect with the plurality of lower electrodes 22A, 22B. Then, when the pressure distribution measurement device 16 receives the measurement signal, it executes the pressure distribution measurement processing routine shown in FIG.

[0078] Specifically, the CPU 81 of the pressure distribution measuring device 16 reads out a program from the ROM 82 or storage 84, loads it into the RAM 83, and executes it, thereby performing the pressure distribution measurement process.

[0079] In step S50, the CPU 81 of the pressure distribution measuring device 16 acquires each of the measurement signals at each of the plurality of measurement points.

[0080] In step S52, the CPU 81 of the pressure distribution measuring device 16 calculates a first value for each of the target measurement points.

[0081] In step S54, the CPU 81 of the pressure distribution measuring device 16 calculates a second value for each of the target measurement points.

[0082] In step S56, the CPU 81 of the pressure distribution measuring device 16 determines whether there are two or more measurement locations where the first value calculated in step S52 is positive and the second value calculated in step S54 is positive. If there are two or more measurement locations where the first value is positive and the second value is positive, the process proceeds to step S58. If there is one measurement location where the first value is positive and the second value is positive, the process proceeds to step S59.

[0083] In step S58, the CPU 81 of the pressure distribution measuring device 16 calculates a variable t i The measurement signal y is calculated by solving the linear programming problem so that equation (2A) is minimized.i and remove the crosstalk from each of the points to obtain the true signal x i This calculation process is performed for the measurement signal at each time.

[0084] In step S59, the CPU 81 of the pressure distribution measuring device 16 identifies the measurement point where the first value is positive and the second value is positive as the pressure point, and sets the measurement signal measured at that pressure point as a true signal. Also, it sets the measurement signals at other measurement points as zero.

[0085] In step S60, the CPU 81 of the pressure distribution measuring device 16 outputs the true signal calculated in step S58 or the true signal identified in step S59 as a result.

[0086] As described above, the pressure distribution measurement system of this embodiment includes a piezoelectric element, a matrix sensor including a plurality of upper electrodes arranged to extend in a first direction and disposed above the piezoelectric element, and a plurality of lower electrodes arranged to extend in a second direction intersecting the first direction and disposed below the piezoelectric element, and a pressure distribution measurement device. The pressure distribution measurement device acquires measurement signals representing differences between signals output from the upper electrodes and the lower electrodes at measurement locations corresponding to positions where the plurality of upper electrodes and the plurality of lower electrodes intersect. The pressure distribution measurement device then calculates, for each of the target measurement locations, a first value that is the sum of differences between the measurement signals measured at the target measurement location and measurement signals measured at measurement locations other than the target measurement location but where a common upper electrode is disposed with the target measurement location. The pressure distribution measurement device calculates, for each of the target measurement locations, a second value that is the sum of differences between the measurement signals measured at the target measurement location and measurement signals measured at measurement locations other than the target measurement location but where a common lower electrode is disposed with the target measurement location. If there is one measurement point where the first value is positive and the second value is positive, the pressure distribution measurement device determines that measurement point as a pressurized point. If there are two or more measurement points where the first value is positive and the second value is positive, the pressure distribution measurement device determines that the variable t representing the error is a pressurized point while satisfying the constraint formula (1A). i The measurement signal y is calculated by solving the linear programming problem so that equation (2A) is minimized. i and remove the crosstalk from each of the points to obtain the true signal x i In this way, when a matrix sensor is used in which a plurality of voltage measurement points are arranged on a piezoelectric body and electrodes are shared among the plurality of measurement points, it is possible to estimate the actual pressure distribution from the electrical signals observed at the plurality of measurement points.

[0087] (Pressure distribution measurement system 210 of the second embodiment) Next, a second embodiment will be described. The pressure distribution measurement system of the second embodiment differs from the first embodiment in that the matrix sensor is a laminated matrix sensor. Note that the same components as those of the first embodiment are denoted by the same reference numerals and their description will be omitted.

[0088] Fig. 13 is a diagram showing a schematic configuration of a pressure distribution measurement system 210 according to the second embodiment. As shown in Fig. 13, the pressure distribution measurement system 210 of this embodiment includes a matrix sensor 212, a measurement circuit 14, and a pressure distribution measurement device 216.

[0089] 14 and 15 are schematic diagrams of a matrix sensor 212. As shown in Fig. 14 and 15, the matrix sensor 212 of the second embodiment includes a first piezoelectric body 18A, a second piezoelectric body 18B, a plurality of first upper electrodes 20A-1, 20B-1, and 20C-1, a plurality of first lower electrodes 22A-1, 22B-1, and 22C-1, a plurality of second upper electrodes 20A-2 and 20B-2, a plurality of second lower electrodes 22A-2 and 22B-2, and an insulating layer 21.

[0090] 14, the plurality of first upper electrodes 20A-1, 20B-1, and 20C-1 are arranged to extend in a first direction and are disposed above the first piezoelectric body 18A. The plurality of second lower electrodes 22A-2 and 22B-2 are arranged to extend in the first direction and are disposed below the first piezoelectric body 18A.

[0091] Additionally, the plurality of second upper electrodes 20A-2, 20B-2 are arranged to extend in a second direction intersecting the first direction and are arranged above the second piezoelectric body 18B. The plurality of second lower electrodes 22A-2, 22B-2 are arranged to extend in the second direction and are arranged below the second piezoelectric body 18B.

[0092] The insulating layer 21 is disposed between the plurality of first lower electrodes 22A-1, 22B-1, and 22C-1 of the first piezoelectric body 18A and the plurality of second upper electrodes 20A-2 and 20B-2 of the second piezoelectric body 18B.

[0093] The matrix sensor 212 is formed by laminating two piezoelectric bodies, a first piezoelectric body 18A and a second piezoelectric body 18B, and an insulating layer 21 is disposed between the first piezoelectric body 18A and the second piezoelectric body 18B. As shown in Figures 14 and 15, by laminating the first piezoelectric body 18A and the second piezoelectric body 18B with the insulating layer 21 sandwiched between them, the common use of piezoelectric bodies and electrodes, which are the cause of crosstalk, is completely eliminated, and therefore no crosstalk occurs in the matrix sensor 12.

[0094] Fig. 16 is a diagram illustrating a measurement signal when matrix sensor 212 is used. As shown in Fig. 16, since no crosstalk occurs in matrix sensor 212, even when two pressure points exist, the pressure point is estimated from the measurement signals of ch_x2 and ch_y0, and the pressure point is estimated from the measurement signals of ch_x0 and ch_y2. In this case, for example, the larger of the average of the measurement signals of ch_x2 and ch_y0 or the measurement signals of ch_x2 and ch_y0 is estimated as the pressure value at the pressure point.

[0095] However, there are cases where it is desired to estimate the stress distribution with higher accuracy.

[0096] Therefore, in the second embodiment, the stress distribution is estimated more accurately using linear programming. Specifically, for the first measurement signal output from the first upper electrode 20-1 and the second measurement signal output from the second lower electrode 22-2, the first measurement signal y is calculated for each of the identification numbers i and j of the measurement points. i the second measurement signal x j and weight w ij The variable t represents the error when expressing it as a weighted sum of i The true signal x for each of the measurement point identification numbers i, j is calculated so as to minimize the sum of i Calculate.

[0097] More specifically, the pressure distribution measuring device 216 of the second embodiment calculates a variable t representing an error for each of the identification numbers i and j of the measurement points. i While satisfying the following constraint (1B) regarding i By solving the linear programming method so that equation (2B) representing the sum of i Calculate.

[0098]

number

[0099] Since it is considered to be expressed by a weighted average of the first measurement signal output from the first upper electrode 20-1 and the second measurement signal output from the second lower electrode 22-2, the weight w corresponding to the measurement point, which is the intersection of the electrodes, is ij By solving the above linear programming method after appropriately setting in advance, the true signal x for each of the measurement point identification numbers i and j can be obtained. i is calculated with high accuracy.

[0100] Next, the operation of the pressure distribution measuring system 210 of the second embodiment will be described.

[0101] When pressure is applied to the matrix sensor 212, the measurement circuit 14 outputs a first measurement signal output from the first upper electrode 20-1 and a second measurement signal output from the second lower electrode 22-2. Then, when the pressure distribution measurement device 216 receives the measurement signals, it executes a pressure distribution measurement processing routine shown in FIG.

[0102] Specifically, the CPU 81 of the pressure distribution measuring device 216 reads out a program from the ROM 82 or storage 84, loads it into the RAM 83, and executes it, thereby performing the pressure distribution measurement process.

[0103] In step S70, the CPU 81 of the pressure distribution measuring device 216 acquires a plurality of first measurement signals and a plurality of second measurement signals.

[0104] In step S72, the CPU 81 of the pressure distribution measuring device 216 corrects each of the plurality of first measurement signals and the plurality of second measurement signals so that the ratio between the first measurement signal and the second measurement signal becomes 1:1.

[0105] In step S74, the CPU 81 of the pressure distribution measuring device 216 calculates the error variable t i By solving the linear programming method to minimize equation (2B), which represents the sum of i This calculation process is performed for the measurement signal at each time.

[0106] In step S76, the CPU 81 of the pressure distribution measuring device 216 outputs the true signal calculated in step S74 as a result.

[0107] As described above, the pressure distribution measurement system of the second embodiment includes a matrix sensor including a first piezoelectric element, a second piezoelectric element, a plurality of first upper electrodes arranged to extend in a first direction and disposed above the first piezoelectric element, a plurality of first lower electrodes arranged to extend in the first direction and disposed below the first piezoelectric element, a plurality of second upper electrodes arranged to extend in a second direction intersecting the first direction and disposed above the second piezoelectric element, a plurality of second lower electrodes arranged to extend in the second direction and disposed below the second piezoelectric element, and an insulating layer disposed between the plurality of first lower electrodes in the first piezoelectric element and the plurality of second upper electrodes in the second piezoelectric element, and a pressure distribution measurement device. The pressure distribution measurement device acquires a first measurement signal output from the first upper electrode and a second measurement signal output from the second lower electrode at each of measurement locations corresponding to positions where the plurality of first upper electrodes and the plurality of second lower electrodes intersect. The pressure distribution measuring device generates a first measurement signal y for each of the measurement point identification numbers i and j. iand weights for multiple measurement points w ij and the second measurement signal y j and the first measurement signal y i the second measurement signal x j and weight w ij The variable t represents the error when expressing it as a weighted sum of i While satisfying the following constraint (1B) regarding i By solving the linear programming method so that equation (2B) representing the sum of i This allows the actual pressure distribution to be estimated from the electrical signals observed at the multiple measurement points when using a matrix sensor in which multiple voltage measurement points are arranged on the piezoelectric body and the electrodes are shared among the multiple measurement points. [Example]

[0108] Next, an example of the pressure distribution measurement system according to this embodiment will be described. In this example, a pressure distribution measurement system similar to that of the first embodiment was manufactured, and this pressure distribution measurement system was used to measure the bite force distribution of teeth.

[0109] Figure 18 shows the pressure distribution measurement system that was actually manufactured. As shown in Figure 18, the pressure distribution measurement system is composed of an upper electrode 20, a lower electrode 22, and a piezoelectric element 18 (PVDF). Also, as shown in Figure 18, the pressure distribution measurement system is sealed with a laminate film. Also, Figure 19 shows the estimated results of the bite force distribution. In each graph in Figure 19, the "Measurement channel" represents the channel corresponding to the upper electrode, and the "Switching channel" represents the channel corresponding to the lower electrode. The results in the upper row shown in Figure 19 are the bite force distribution before optimization (before crosstalk removal), and the results in the lower row shown in Figure 19 are the bite force distribution after optimization (after crosstalk removal). As shown in Figure 19, crosstalk occurs in the bite force distribution before optimization, while crosstalk is removed in the bite force distribution after optimization, indicating that the bite force distribution is accurately estimated.

[0110] The present invention is not limited to the above-described embodiment, and various modifications and applications are possible without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0111] 10 Pressure distribution measurement system 12 Matrix Sensor 14 Measurement circuit 16 Pressure distribution measuring device 18 Piezoelectric 20 Upper electrode 22 Lower electrode 28C Differential amplifier circuit 210 Pressure Distribution Measurement System 212 Matrix Sensor 216 Pressure distribution measuring device

Claims

1. A piezoelectric body; a plurality of upper electrodes arranged to extend in a first direction and disposed on top of the piezoelectric body; a plurality of lower electrodes disposed below the piezoelectric body and extending in a second direction intersecting the first direction; a matrix sensor including: a pressure distribution measuring device; A pressure distribution measurement system comprising: The pressure distribution measuring device is acquiring measurement signals representing differences between signals output from the upper electrodes and signals output from the lower electrodes at measurement points corresponding to positions where the plurality of upper electrodes and the plurality of lower electrodes intersect; For each of the measurement points of interest, calculating a first value which is the sum of the differences between the measurement signal measured at the target measurement point and the measurement signal measured at another measurement point different from the target measurement point and having a common upper electrode disposed thereon; calculating a second value which is the sum of the differences between the measurement signal measured at the target measurement point and the measurement signal measured at another measurement point different from the target measurement point and having a common lower electrode disposed thereon; If there is one measurement point where the first value is positive and the second value is positive, the measurement point is determined to be a pressure point; When there are two or more measurement points where the first value is positive and the second value is positive, For each of the measurement point identification numbers i and j, the measurement signal y observed at the plurality of measurement points is ｉ and the measurement signal y ｉ The true signal x for ｉ and the measurement signal y ｊ The true signal x for ｊ and the measurement signal y ｉ and the true signal x ｉ , x ｊ The variable t represents the error between ｉ The variable t representing the error is set while satisfying the following constraint (1A) between ｉ The measurement signal y is calculated by solving the linear programming method so that the equation (2A) is minimized. ｉ and remove crosstalk from each of the true signals x at the multiple measurement points. ｉ Calculate each of Pressure distribution measurement system. [Equation 1] (1A) 【number】 (2A)

2. A first piezoelectric body; A second piezoelectric element; a plurality of first upper electrodes arranged to extend in a first direction and disposed above the first piezoelectric body; and a plurality of first lower electrodes arranged to extend in the first direction and disposed below the first piezoelectric body. a plurality of second upper electrodes disposed on the second piezoelectric body so as to extend in a second direction intersecting the first direction; a plurality of second lower electrodes disposed so as to extend in the second direction and disposed below the second piezoelectric element; an insulating layer disposed between the plurality of first lower electrodes of the first piezoelectric body and the plurality of second upper electrodes of the second piezoelectric body; a matrix sensor including: a pressure distribution measuring device; A pressure distribution measurement system comprising: The pressure distribution measuring device is acquiring a first measurement signal output from the first upper electrode and a second measurement signal output from the second lower electrode at each of measurement points corresponding to positions where the plurality of first upper electrodes and the plurality of second lower electrodes intersect; For each of the measurement points of interest, For each of the measurement point identification numbers i and j, the first measurement signal y ｉ and weights for multiple measurement points w ｉｊ and the second measurement signal y ｊ and the first measurement signal y ｉ the second measurement signal x ｊ And weight lol ｉｊ A variable t that represents the error when expressing the weighted sum of ｉ While satisfying the following constraint (1B) regarding ｉ By solving the linear programming method so as to minimize the equation (2B) representing the sum of ｉ Calculate Pressure distribution measurement system. [Equation 2] (1B) 【number】 (2B)

3. The lower electrode is grounded. The pressure distribution measurement system according to claim 1 .

4. the first lower electrode and the second upper electrode are grounded; The pressure distribution measurement system according to claim 2 .

5. The piezoelectric material is an organic piezoelectric material. The pressure distribution measurement system according to claim 1 .

6. the first piezoelectric body and the second piezoelectric body are organic piezoelectric bodies; The pressure distribution measurement system according to claim 2 .

7. The pressure distribution measurement system is used to measure the bite force distribution of teeth.

7. The pressure distribution measuring system according to claim 5 or 6.

8. 2. A measurement circuit for differential amplification measurement used in the pressure distribution measurement system according to claim 1, comprising: outputting a measurement signal representing a difference between the upper electrode and the lower electrode in the matrix sensor; Measurement circuit for differential amplification measurement.

9. A pressure distribution measurement program for causing a computer to function as the pressure distribution measurement device according to claim 1 or 2.

10. A pressure distribution measuring method in which each process executed by the pressure distribution measuring device according to claim 1 or 2 is executed by a computer.

Images