Pressure measuring method, information processing device, and program

Abstract

Pressure is applied to a color developing member that develops color with a density corresponding to the applied pressure, and a sensor device that outputs an output value corresponding to the applied pressure, in a state in which the color developing member and the sensor device have been overlaid on one another, after which a color developing member image is acquired. Time-series data of the output value of the sensor device during a pressure application period are acquired. Pressure distribution data indicating the surface distribution of the applied pressure is derived on the basis of the color developing member image. Pressure distribution time series data indicating a transition over time of the surface distribution of the applied pressure is derived on the basis of the time series data of the output value of the sensor device. The pressure value at each position and each time point in the pressure distribution time series data is corrected using the pressure distribution data. The maximum height roughness Rz of the surface of contact of the sensor device with the color developing member when a pressure of 50 MPa is applied to the sensor device is 20 μm or less.

Description

Pressure measurement method, information processing device and program

[0001] The disclosed technology relates to a pressure measurement method, an information processing device, and a program.

[0002] 2. Description of the Related Art Various techniques are known in the art for measuring energy (such as pressure, heat, and ultraviolet light) applied to a surface.

[0003] First, a technique for measuring the amount of energy is known, using a color-developing member that develops a color according to the amount of energy when energy is applied. One example of such a color-developing member is Prescale (registered trademark) (manufactured by Fujifilm Corporation), which provides a color density according to the applied pressure. For example, International Publication No. 2021 / 235364 discloses a method for placing a pressure measurement sheet (e.g., Prescale) on a calibration sheet, photographing the image, correcting the density, size, distortion, and shape of the photographed image based on the calibration sheet included in the photographed image, and converting the density value of the pressure measurement sheet included in the corrected image into a pressure value.

[0004] Secondly, there is known a sensor device that uses a sensor element to detect pressure, etc. and outputs an electrical signal corresponding to the pressure, etc. For example, Japanese Patent Application Laid-Open No. 2020-123119 discloses a sensor device that is disposed on a substrate and includes a sensing unit that includes a sensor element that detects at least one of pressure and temperature, and a memory unit that stores calibration data for the sensor element.

[0005] The disclosed technique aims to perform highly accurate measurement of the time transition of the surface distribution of applied pressure.

[0006] The pressure measurement method according to the disclosed technology includes the steps of: applying pressure to a color-forming member that develops a color at a density corresponding to the applied pressure and a sensor device that outputs an output value corresponding to the applied pressure while the color-forming member and the sensor device are stacked; acquiring a color-forming member image, which is a photographed image of the color-forming member after the pressure is applied; acquiring time series data of the output values ​​of the sensor device during the pressure application period; and having at least one processor provided in an information processing device execute processing based on the color-forming member image and the time series data of the output values ​​of the sensor device; and when a pressure of 50 MPa is applied to the sensor device, the maximum height roughness Rz of the contact surface of the sensor device with the color-forming member is 20 μm or less.

[0007] The above processing may include processing related to the surface distribution of the applied pressure based on time-series data of output values ​​of the sensor device. The above processing may include processing using pressure distribution data indicating the surface distribution of the applied pressure derived based on a color-developing member image, and pressure distribution time-series data indicating a time progression of the surface distribution of the applied pressure derived based on the time-series data of output values ​​of the sensor device. The above processing may include processing for correcting pressure values ​​at each position and each time point in the pressure distribution time-series data using the pressure distribution data.

[0008] The sensor device may be a piezoresistive tactile sensor having a plurality of electrodes arranged on the surface of a substrate and a pressure-sensitive conductive member covering the plurality of electrodes. The thickness of each of the plurality of electrodes may be 20 μm or less. A portion of each of the plurality of electrodes may be embedded in the substrate so that the surface is exposed. The pitch of the plurality of electrodes may be 1000 μm or less. The substrate in contact with the color-developing member may be made of a material having a pencil hardness of 2H or more. The sensor device may be of any of a capacitance type, a pressure-sensitive rubber type, and a TFT type.

[0009] The information processing device according to the disclosed technology includes at least one processor. The processor acquires a color-forming member image, which is a photographed image of the color-forming member after pressure is applied, when pressure is applied to a color-forming member that develops a color density according to the applied pressure and a sensor device that outputs an output value according to the applied pressure while the color-forming member and the sensor device are overlapped, acquires time-series data of the output value of the sensor device during the pressure application period, and performs processing based on the color-forming member image and the time-series data of the output value of the sensor device. When a pressure of 50 MPa is applied to the sensor device, the maximum height roughness Rz of the contact surface between the sensor device and the color-forming member is 20 μm or less.

[0010] The program according to the disclosed technology is a program for causing at least one processor of an information processing device to execute processing based on the color-forming member image and the time-series data of the output values ​​of the sensor device when pressure is applied to a color-forming member that develops a color at a density corresponding to the applied pressure and a sensor device that outputs an output value corresponding to the applied pressure, the program acquiring a color-forming member image that is a captured image of the color-forming member after the pressure is applied, acquiring time-series data of the output values ​​of the sensor device during the pressure application period, and the program causing at least one processor of the information processing device to execute processing based on the color-forming member image and the time-series data of the output values ​​of the sensor device when a pressure of 50 MPa is applied to the sensor device.

[0011] According to the disclosed technology, it is possible to measure the time transition of the surface distribution of applied pressure with high accuracy.

[0012] 1 is a diagram showing an example of a pressure measurement method according to an embodiment of the disclosed technology; FIG. 2 is a plan perspective view showing an example of the configuration of a sensor device; FIG. 3 is a cross-sectional view showing an example of the configuration of a sensor device; FIG. 4 is a diagram showing an example of the hardware configuration of an information processing device; FIG. 5 is a diagram showing an example of first reference data; FIG. 6 is a diagram showing an example of second reference data; FIG. 7 is a functional block diagram showing an example of the functional configuration of an information processing device; FIG. 8 is a flowchart showing an example of a flow of processing performed by a CPU executing a pressure measurement program; FIG. 9 is a diagram showing irregularities formed on the surface of a sensor device by applying pressure; FIG. 10 is a diagram showing the definition of maximum height roughness Rz; FIG. 11 is a diagram showing an example of a method for measuring maximum height roughness Rz on a contact surface of a sensor device with a color-forming member when pressure is applied; FIG. 12 is a diagram showing an example of a method for measuring maximum height roughness Rz on a contact surface of a sensor device with a color-forming member when pressure is applied; FIG. 13 is a cross-sectional view showing an example of the configuration of a sensor device.

[0013] Hereinafter, an example of an embodiment of the disclosed technology will be described with reference to the drawings. In each drawing, the same or equivalent components and parts are given the same reference numerals, and redundant description will be omitted.

[0014] 1 is a diagram illustrating an example of a pressure measurement method according to an embodiment of the disclosed technology. The pressure measurement method according to this embodiment measures applied pressure using two pressure measurement means, a sensor device 20 and a color-developing member 30.

[0015] FIG. 2A is a planar perspective view showing an example of the configuration of the sensor device 20. FIG. 2B is a cross-sectional view showing an example of the configuration of the sensor device 20. The sensor device 20 is a tactile sensor that detects pressure using a piezo-resistive method. The sensor device 20 includes a plurality of first electrodes 21 arranged on the surface of a substrate 24 and extending in a first direction, a plurality of second electrodes 22 arranged on the surface of a substrate 25 and extending in a second direction intersecting the first direction, and a connector 23. The substrate 24 and the substrate 25 are bonded together so that the first electrodes 21 and the second electrodes 22 intersect. The substrate 24 and the substrate 25 are made of a resin such as PET (polyethylene terephthalate), and the first electrodes 21 and the second electrodes 22 are made of a metal such as Cu or Al. The surfaces of the first electrodes 21 and the second electrodes 22 are covered with a pressure-sensitive conductive member 26. The pressure-sensitive conductive member 26 is a member whose resistance value changes in response to applied pressure.

[0016] Electrical signals corresponding to the resistance values ​​at each intersection of the first electrode 21 and the second electrode 22, which are pressure detection points of the sensor device 20, are sequentially read out from each electrode. These electrical signals are converted into digital values ​​and output from the connector 23. The output values ​​of the sensor device 20 are values ​​proportional to the magnitude of the pressure applied to each intersection of the first electrode 21 and the second electrode 22. The output values ​​of the sensor device 20 are taken into the information processing device 10 connected to the connector 23.

[0017] The accuracy of pressure measurement by the sensor device 20 is lower than that of the color-forming member 30. This is because the application of pressure to the sensor device 20 causes plastic deformation of the substrates 24 and 25, which causes deviations in the output value of the sensor device 20. Furthermore, errors in the output value of the sensor device 20 also occur when noise is mixed into the electrical signals read from each electrode of the sensor device 20. On the other hand, since the output value of the sensor device 20 changes in response to changes in the applied pressure, it is possible to acquire the output value of the sensor device 20 as time-series data. In other words, by measuring pressure using the sensor device 20, it is possible to monitor the time progression of the surface distribution of the applied pressure.

[0018] The color-forming member 30 is a film-like member formed by laminating a color-forming agent layer containing dispersed microcapsules encapsulating a colorless dye and a color-developing agent layer containing a color developer. When pressure is applied to the color-forming member 30, the microcapsules are broken, and the colorless dye is adsorbed to the color developer, resulting in color development through a chemical reaction. The colorless dye is encapsulated in multiple types of microcapsules of different sizes and strengths. The amount of colorless dye that flows out of the broken microcapsules and adsorbs to the color developer varies depending on the pressure applied to the color-forming member 30. Therefore, the color-forming member 30 develops a color at a density corresponding to the applied pressure. By analyzing the color-developing state of the color-forming member 30, the surface distribution of the pressure applied to the color-forming member 30 can be monitored. Note that the amount of penetration of the colorless dye into the color developer is affected by the duration of pressure application. Therefore, the color density of the color-forming member 30 corresponds to the cumulative amount of applied pressure over time. For example, a Prescale (registered trademark) manufactured by Fujifilm Corporation can be used as the color-forming member 30.

[0019] Pressure measurement using the color-changing member 30 makes it possible to monitor the static surface distribution of pressure. However, because the color-changing reaction of the color-changing member 30 is irreversible, it is not possible to monitor the time transition of the surface distribution of pressure. On the other hand, the accuracy of pressure measurement using the color-changing member 30 is higher than that of pressure measurement using the sensor device 20.

[0020] As described above, pressure measurement using the sensor device 20 has the advantage of being able to monitor the time progression of the surface distribution of the applied pressure, but the disadvantage of relatively low pressure measurement accuracy. Pressure measurement using the color-forming member 30 has the advantage of being able to relatively high pressure measurement accuracy, but the disadvantage of being unable to monitor the time progression of the surface distribution of the applied pressure. The pressure measurement method according to this embodiment compensates for the disadvantages of either the sensor device 20 or the color-forming member 30 with the advantages of the other, thereby achieving highly accurate measurement of the time progression of the surface distribution of the applied pressure.

[0021] 1 , the pressure measurement method according to this embodiment involves applying pressure to a color-forming member 30 and a sensor device 20 in a state in which the color-forming member 30 and the sensor device 20 are stacked. Note that in addition to the color-forming member 30 and the sensor device 20, an object 50 to which pressure is to be applied may also be stacked and pressure may be applied. This makes it possible to measure the pressure actually applied to the object 50. The object 50 may be, for example, an industrial product or material thereof, such as a metal plate or a semiconductor wafer, and the pressure measurement method according to this embodiment may be applied to a manufacturing process that involves applying pressure to the industrial product or the like.

[0022] The pressure measurement method according to this embodiment includes acquiring a color-forming member image 40, which is a photographed image of the color-forming member 30 after pressure is applied. The color-forming member image 40 is acquired as a color image. The color-forming member 30 can be photographed using a digital camera or a scanner. If the information processing device 10 includes a digital camera, the color-forming member 30 may be photographed by the digital camera included in the information processing device 10.

[0023] The information processing device 10 may be a mobile terminal device such as a smartphone or a tablet computer, or may be a desktop or laptop personal computer.

[0024] 3 is a diagram showing an example of the hardware configuration of the information processing device 10. The information processing device 10 includes a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102, a non-volatile memory 103, an input device 104 including a keyboard and a mouse, a display 105, and a communication interface 106. These pieces of hardware are connected to a bus 108.

[0025] The display 105 may be a touch panel display. The communication interface 106 is an interface for data communication between the information processing device 10 and the sensor device 20 and a digital camera or scanner that captures the color-forming member image 40. The communication method may be either wired or wireless. For wireless communication, a method conforming to existing wireless communication standards such as Wi-Fi (registered trademark) and Bluetooth (registered trademark) can be applied.

[0026] The nonvolatile memory 103 is a nonvolatile storage medium such as a hard disk or flash memory. A pressure measurement program 110, first reference data 120A, and second reference data 120B are stored in the nonvolatile memory 103. The RAM 102 is a work memory for the CPU 101 to execute processing. The CPU 101 loads the pressure measurement program 110 stored in the nonvolatile memory 103 into the RAM 102 and executes processing in accordance with the pressure measurement program 110. The CPU 101 is an example of a "processor" in the disclosed technology.

[0027] FIG. 4A is a diagram showing an example of first reference data 120A. The first reference data 120A is data in which color density values ​​and pressure values ​​in a color-forming member image 40, which is a photographed image of the color-forming member 30 after pressure application, are associated with each other. The information processing device 10 refers to the first reference data 120A when deriving the pressure value applied to the color-forming member 30 based on the color-forming member image 40. The first reference data 120A may be provided by a manufacturer of the color-forming member 30. The first reference data 120A may be created based on, for example, a representative characteristic that is representative of the color characteristics of the color-forming member 30. The color density values ​​in the reference data 120A may be gradation values ​​when the color density of the color-forming member 30 is expressed in, for example, 256 gradations in the color-forming member image 40. The number of gradations can be determined appropriately.

[0028] 4B is a diagram showing an example of second reference data 120B. The second reference data 120B is data in which the output value of the sensor device 20 is associated with a pressure value. The information processing device 10 refers to the second reference data 120B when deriving the pressure value applied to the sensor device 20 based on the output value of the sensor device 20. The second reference data 120B may be provided by the manufacturer of the sensor device 20. The output value of the sensor device 20 may be an 8-bit digital value that expresses the pressure detected by the sensor device 20 in, for example, 256 stages.

[0029] 5 is a functional block diagram showing an example of the functional configuration of the information processing device 10. The information processing device 10 has an acquisition unit 11, a derivation unit 12, a correction unit 13, and a display processing unit 14. When the CPU 101 executes the pressure measurement program 110, the CPU 101 functions as the acquisition unit 11, the derivation unit 12, the correction unit 13, and the display processing unit 14.

[0030] 1, pressure is applied to the color-producing member 30 and the sensor device 20 in a state where the color-producing member 30 and the sensor device 20 are overlapped. After the pressure application is completed, the color-producing member 30 is removed, and an image of the color-producing surface of the color-producing member 30 is taken using a digital camera or scanner (not shown).

[0031] The acquisition unit 11 acquires a color-forming member image 40, which is a photographed image of the color-forming member 30 after the pressure is applied. The acquisition unit 11 also acquires time-series data of the output value of the sensor device 20 during the pressure application period.

[0032] The derivation unit 12 derives pressure distribution data indicating the surface distribution of applied pressure values ​​using the color-forming member image 40 and the first reference data 120A acquired by the acquisition unit 11. Specifically, the derivation unit 12 identifies the color density value of each pixel in the color-forming member image 40 and performs a process for each pixel to derive a pressure value corresponding to the color density value by referring to the first reference data 120A. The derivation unit 12 may derive index values ​​such as a pressure effectiveness ratio, a pressure applied area, an average pressure, a maximum pressure, a minimum pressure, a weight, and pressure uniformity in addition to the pressure value by analyzing the color-forming member image 40. The pressure effectiveness ratio is the proportion of the color-forming area of ​​the color-forming member 30 that is included in the recommended pressure range of the color-forming member 30. The pressure applied area is the area of ​​the colored region of the color-forming member 30 (hereinafter referred to as the color-forming region). The average pressure is the average value of the pressure in the color-forming region. The maximum pressure is the maximum value of the pressure in the color-forming region. The minimum pressure is the minimum pressure value in the color-producing area. The weight is the weight value of the color-producing area (pressure area x average pressure). The pressure uniformity is an index of the uniformity of the pressure value in the color-producing area.

[0033] Furthermore, the derivation unit 12 derives pressure distribution time series data indicating the time transition of the surface distribution of the applied pressure, using the time series data of the output value of the sensor device 20 acquired by the acquisition unit 11 and the second reference data 120B. Specifically, the derivation unit 12 performs a process of deriving a pressure value corresponding to the output value of the sensor device 20 at each time point, for each detection point of the sensor device 20, with reference to the second reference data 120B.

[0034] The correction unit 13 calculates the pressure value P at each position and each time point indicated by the pressure distribution time series data based on the output value of the sensor device 20. ｓ（ｘ，ｙ） A correction process is performed to correct (t) using pressure distribution data based on the color-developing member image 40. Details of this correction process will be described below.

[0035] The correction unit 13 derives a time-integrated amount for the pressure value at each detection point indicated by the pressure distribution time-series data. The time-integrated amount for the pressure value at each detection point is hereinafter referred to as an integrated pressure value P ａ（ｘ，ｙ） It is called.

[0036] Next, the correction unit 13 calculates the pressure value P at each position indicated by the pressure distribution data based on the color-producing member image 40. ｃ（ｘ，ｙ）） The integrated pressure value P ａ（ｘ、ｙ） By dividing by , the correction coefficient C at each detection point of the sensor device 20 is obtained. （ｘ，ｙ） That is, the correction coefficient C at each detection point of the sensor device 20 is derived. （ｘ，ｙ） is expressed by the following equation (1). The position of each detection point of the sensor device 20 and the position of each pixel of the color-producing member image 40 are defined by an xy orthogonal coordinate system, and the pressure distribution time-series data based on the output value of the sensor device 20 and the pressure distribution data based on the color-producing member image 40 are aligned with each other using the xy orthogonal coordinate system. C （ｘ，ｙ） =P ｃ（ｘ，ｙ） / P ａ（ｘ，ｙ） ...(1)

[0037] Next, the correction unit 13 calculates the pressure value P at each detection point and each time point of the pressure distribution time series data based on the output value of the sensor device 20. ｓ（ｘ，ｙ） (t) with the correction coefficient C （ｘ，ｙ） This multiplication process is performed for each detection point. As a result, the pressure value P ｓ（ｘ，ｙ） (t) is corrected. That is, the pressure value P （ｘ，ｙ） (t) is expressed by the following equation (2): P （ｘ，ｙ） (t) = P ｓ（ｘ，ｙ） (t) × C （ｘ，ｙ） ... (2)

[0038] Here, it is assumed that the surface resolution of the pressure distribution data based on the color-producing member image 40 and the surface resolution of the pressure distribution time-series data based on the sensor device 20 are different from each other. Typically, the surface resolution of the pressure distribution data based on the color-producing member image 40 is higher than the surface resolution of the pressure distribution time-series data based on the sensor device 20. This is because the number of pixels in the color-producing member image 40 is usually greater than the number of pressure detection points in the sensor device 20. Therefore, for example, a process may be performed to match the surface resolution of the pressure distribution data based on the color-producing member image 40 with the surface resolution of the pressure distribution time-series data based on the sensor device 20. For example, if the surface resolution of the pressure distribution data based on the color-producing member image 40 is four times the surface resolution of the pressure distribution time-series data based on the sensor device 20, resolution conversion may be performed to integrate four adjacent pixels in the color-producing member image 40 into one pixel. In this case, the average value of the pixel values ​​of the four pixels is applied as the pixel value of one pixel to be integrated, and then the correction coefficient C （ｘ，ｙ） may be derived.

[0039] Furthermore, a process may be performed to match the surface resolution of the pressure distribution time series data based on the sensor device 20 with the surface resolution of the pressure distribution data based on the color-producing member image 40. For example, if the surface resolution of the pressure distribution data based on the color-producing member image 40 is four times the surface resolution of the pressure distribution time series data based on the sensor device 20, a resolution conversion may be performed to divide one pressure detection point of the sensor device 20 into four regions. In this case, the output value at one detection point before division is assigned to the four regions, and a correction coefficient C is calculated for each of the four regions. （ｘ，ｙ） may be derived.

[0040] The display processing unit 14 displays the corrected pressure value P （ｘ，ｙ） The display processing unit 14 performs processing to display the pressure values ​​(t) at each position after correction on the display 105. For example, the display processing unit 14 may display the pressure values ​​at each position after correction as a plurality of three-dimensional graphs for each time. The display processing unit 14 may also display the three-dimensional graphs showing the pressure values ​​at each position after correction as a moving image that changes over time. The display processing unit 14 may also display a two-dimensional graph showing the time progression of the pressure value at a specified position.

[0041] 6 is a flowchart showing an example of the flow of processing performed by the CPU 101 when the CPU 101 executes the pressure measurement program 110. It is assumed that, prior to execution of the pressure measurement program 110, pressure is applied to the color-forming member 30 and the sensor device 20 while they are superimposed on each other. It is also assumed that a color-forming member image 40 is obtained for the color-forming member 30 after the pressure is applied.

[0042] In step S1, the acquisition unit 11 acquires a color-forming member image 40, which is a captured image of the color-forming member 30 after pressure has been applied.

[0043] In step S2, the acquisition unit 11 acquires time-series data of the output value of the sensor device 20 during the pressure application period.

[0044] In step S3, the derivation unit 12 derives pressure distribution data indicating the surface distribution of the applied pressure values ​​using the color-producing member image 40 acquired in step S1 and the first reference data 120A. Specifically, the derivation unit 12 identifies the color density value of each pixel of the color-producing member image 40, and performs a process of deriving a pressure value corresponding to the color density value for each pixel by referring to the first reference data 120A.

[0045] In step S4, the derivation unit 12 derives pressure distribution time-series data indicating the time transition of the surface distribution of the applied pressure, using the time-series data of the output value of the sensor device 20 acquired in step S2 and the second reference data 120B. Specifically, the derivation unit 12 performs a process of deriving a pressure value corresponding to the output value of the sensor device 20 at each time point, for each detection point of the sensor device 20, with reference to the second reference data 120B.

[0046] In step S5, the correction unit 13 calculates the pressure value P at each position and each time point indicated by the pressure distribution time series data derived in step S4. ｓ（ｘ，ｙ） (t) is corrected using the pressure distribution data derived in step S3. The corrected pressure value P （ｘ，ｙ） (t) is expressed by equation (2).

[0047] In step S6, the display processing unit 14 displays the corrected pressure values ​​P （ｘ，ｙ） (t) is displayed on the display 105.

[0048] As described above, the pressure measurement method according to an embodiment of the disclosed technology includes the steps of: when an information processing device 10 applies pressure to a color-forming member 30 that develops color at a density corresponding to the applied pressure and a sensor device 20 that outputs an output value corresponding to the applied pressure while the color-forming member 30 and the sensor device 20 are stacked on top of each other; acquiring a color-forming member image 40, which is a captured image of the color-forming member 30 after the pressure is applied; acquiring time series data of the output values ​​of the sensor device 20 during the pressure application period; deriving pressure distribution data showing the surface distribution of the applied pressure based on the color-forming member image 40; deriving pressure distribution time series data showing the time progression of the surface distribution of the applied pressure based on the time series data of the output values ​​of the sensor device 20; and correcting the pressure values ​​at each position and each time point in the pressure distribution time series data using the pressure distribution data.

[0049] Pressure measurement using the sensor device 20 has the advantage of being able to monitor the time progression of the surface distribution of the applied pressure, but the disadvantage of relatively low pressure measurement accuracy. Pressure measurement using the color-forming member 30 has the advantage of being able to relatively high pressure measurement accuracy, but the disadvantage of being unable to monitor the time progression of the surface distribution of the applied pressure. According to the pressure measurement method of this embodiment, the disadvantage of either the pressure measurement using the sensor device 20 or the pressure measurement using the color-forming member 30 is compensated for by the advantage of the other, thereby enabling highly accurate measurement of the time progression of the surface distribution of the applied pressure.

[0050] Here, if pressure is applied while the color-forming member 30 and the sensor device 20 are stacked, the following problem may arise. Specifically, as shown in FIG. 2A , the sensor device 20 has first electrodes 21 and second electrodes 22 arranged in a grid pattern. The first electrodes 21 and second electrodes 22 are formed on the surfaces of substrates 24 and 25, respectively, by a film-forming method such as printing. If the thicknesses of the first electrodes 21 and second electrodes 22 are increased, as shown in FIG. 7 , application of pressure may cause unevenness corresponding to the arrangement of the first electrodes 21 and second electrodes 22 on the surface of the sensor device 20 (the surface in contact with the color-forming member 30), affecting the color development state of the color-forming member 30. Specifically, a grid-like color-forming portion corresponding to the arrangement of the first electrodes 21 and second electrodes 22 may be generated in the color-forming member 30. The generation of color-forming portions in the color-forming member 30 due to the structure of the sensor device 20 may hinder high-precision pressure measurement.

[0051] Therefore, in the pressure measurement method according to the embodiment of the disclosed technique, a sensor device 20 is used that has small unevenness on the contact surface with the color-forming member 30 when pressure is applied. Specifically, a sensor device 20 is used that has a maximum height roughness Rz of 20 μm or less on the contact surface with the color-forming member 30 when a pressure of 50 MPa is applied. By making the maximum height roughness Rz of the sensor device 20 on the contact surface with the color-forming member 30 20 μm or less, it is possible to suppress the influence on the color-forming state of the color-forming member 30.

[0052] The maximum height roughness Rz is defined in JIS B 0601 and is the sum of the maximum peak height Zp and the maximum valley depth Zv of the roughness curve at the reference length lr, as shown in Fig. 8. The maximum height roughness Rz of the contact surface with the color-developing member 30 when pressure is applied from the sensor device 20 can be measured, for example, as follows.

[0053] As shown in FIG. 9A , a transfer target member 60 is formed on the surface of the sensor device 20. The transfer target member 60 can be, for example, a UV-curable resin, a thermosetting resin, or a two-component curing resin. Examples of UV-curable resins include, but are not limited to, epoxy-based resins (NICT series, NIAC series, manufactured by Daicel Chemical Industries, Ltd.), urethane-based resins (Shikoh, manufactured by Mitsubishi Chemical Corporation), silicone-based resins (KER series, manufactured by Shin-Etsu Silicones Co., Ltd.), and fluorine-based resins (NIF series, manufactured by Asahi Glass Co., Ltd.). Examples of thermosetting resins include, but are not limited to, phenol-based resins (SK Resin series, manufactured by Air Water Corporation). Examples of two-component curing resins include, but are not limited to, epoxy-based resins (RC series, RH series, manufactured by Sanyu Rec Co., Ltd.) and urethane-based resins (Rubylon, manufactured by Toyo Polymer Co., Ltd.). From the perspective of workability during curing, two-component curing resins that do not require UV light or heat and can be cured by mixing are more preferable. A release agent may also be used in combination with these resins. With the transferred member 60 placed on the surface of the sensor device 20, a specified pressure is applied to both. As a result, the irregularities formed on the surface of the sensor device 20 are transferred to the transferred member 60. Next, the transferred member 60 is hardened, and then the transferred member 60 is peeled off from the sensor device 20.

[0054] 9B, the uneven shape transferred to the transferred member 60 is measured using a surface roughness measuring instrument. Specifically, the tip of a stylus 70 of the surface roughness measuring instrument is moved in one direction while being in contact with the surface of the transferred member 60 onto which the uneven shape has been transferred, and the vertical displacement of the stylus 70 is recorded. This allows a roughness curve indicating the uneven shape transferred to the transferred member 60 to be obtained.

[0055] In the piezoresistivity sensor device 20, in order to set the maximum height roughness Rz of the contact surface with the color-producing member 30 to 20 μm or less, the sensor device 20 may have the following configuration. For example, the thickness of each of the first electrode 21 and the second electrode 22 may be 20 μm or less. For example, the thickness of the first electrode 21 and the second electrode 22 can be reduced by reducing the supply amount of the conductive material constituting the first electrode 21 and the second electrode 22 or by lowering the viscosity. Furthermore, as shown in FIG. 10 , the first electrode 21 and the second electrode 22 may be partially embedded in the substrates 24 and 25 so that the surfaces are exposed.

[0056] Furthermore, the pitch (arrangement interval) of each of the first electrodes 21 and the second electrodes 22 may be reduced. By reducing the pitch of each of the first electrodes 21 and the second electrodes 22, unevenness on the substrate surface when pressure is applied is reduced. By setting the pitches L1 and L2 (see FIG. 2A ) of each of the first electrodes 21 and the second electrodes 22 to, for example, 1000 μm or less, the maximum height roughness Rz of the contact surface with the color-producing member 30 can be set to 20 μm or less.

[0057] The substrates 24 and 25 of the sensor device 20 may be made of a material having a pencil hardness of 2H or more. This makes it possible to reduce or eliminate unevenness formed on the surface of the sensor device 20 (the surface in contact with the color-producing member 30) due to pressure application, thereby suppressing the influence on the color-producing state of the color-producing member 30. Examples of materials that can be used for the substrates 24 and 25 include epoxy resin (hardness equivalent to 2H), PEEK (Poly Ether Ether Ketone, hardness equivalent to 3H), and glass (hardness equivalent to 9H).

[0058] Furthermore, a sensor device may be used that is structurally such that unevenness corresponding to the electrode arrangement does not appear on the surface of the sensor device. For example, by using a sensor device of any of the following types: capacitance type, pressure-sensitive rubber type, and TFT type, the maximum height roughness Rz of the contact surface with the color-producing member 30 can be set to 20 μm or less. In all of the capacitance type, pressure-sensitive rubber type, and TFT type, the electrodes are embedded in a layer or are composed of a thin film of about several microns, so unevenness corresponding to the electrode arrangement does not appear on the surface of the sensor device, and even if it does appear, it does not affect the color-producing state of the color-producing member 30.

[0059] The capacitance method sandwiches an elastic body between upper and lower electrodes, and estimates the applied pressure from the change in capacitance due to deformation of the elastic body. The pressure-sensitive rubber method uses conductive rubber containing conductive powder such as carbon. When pressure is applied to the conductive rubber, the density of the conductive powder increases in that area, and the resistance value decreases. Therefore, it is possible to estimate the applied pressure from the change in resistance value due to deformation of the conductive rubber. The TFT method combines a TFT (Thin Film Transistor) array sheet with a pressure-sensitive rubber sheet.

[0060] The following various processors can be used as hardware structures for realizing the various processes executed by the above-mentioned functional units of the information processing device 10. As described above, the above-mentioned various processors include a CPU, which is a general-purpose processor that executes software (programs) and functions as various processing units, as well as dedicated electrical circuits, such as a programmable logic device (PLD), which is a processor whose circuit configuration can be changed after manufacture, such as an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit), which is a processor having a circuit configuration designed specifically for executing specific processes.

[0061] A single processing unit may be configured with one of these various processors, or may be configured with a combination of two or more processors of the same or different types (for example, a combination of multiple FPGAs, or a combination of a CPU and an FPGA). Also, multiple processing units may be configured with a single processor.

[0062] Examples of configuring multiple processing units with a single processor include: first, a form in which one processor is configured with a combination of one or more CPUs and software, as typified by computers such as client and server computers, and this processor functions as multiple processing units; second, a form in which a processor is used to realize the functions of an entire system including multiple processing units with a single IC (Integrated Circuit) chip, as typified by systems on chips (SoCs); thus, various processing units are configured as hardware structures using one or more of the above-mentioned various processors; furthermore, the hardware structures of these various processors can be, more specifically, electrical circuits combining circuit elements such as semiconductor elements.

[0063] In the above embodiment, the pressure measurement program 110 is pre-stored (installed) in the non-volatile memory 103, but the present invention is not limited to this. The pressure measurement program 110 may be provided in a form recorded on a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a USB (Universal Serial Bus) memory. The pressure measurement program 110 may also be downloaded from an external device via a network.

[0064] The following supplementary notes are further disclosed with respect to the above-described embodiments: (Supplementary Note 1) A pressure measurement method comprising the steps of: applying pressure to a color-forming member that develops a color with a density corresponding to the applied pressure and a sensor device that outputs an output value corresponding to the applied pressure while the color-forming member and the sensor device are overlapped; acquiring a color-forming member image that is a captured image of the color-forming member after the pressure is applied; acquiring time-series data of the output values ​​of the sensor device during the pressure application period; and having at least one processor included in an information processing device execute processing based on the color-forming member image and the time-series data of the output values ​​of the sensor device; and wherein when a pressure of 50 MPa is applied to the sensor device, the maximum height roughness Rz of the contact surface of the sensor device with the color-forming member is 20 μm or less.

[0065] (Supplementary Note 2) The pressure measurement method according to Supplementary Note 1, wherein the processing includes processing relating to a surface distribution of the applied pressure based on time-series data of the output value of the sensor device.

[0066] (Supplementary Note 3) The pressure measurement method described in Supplementary Note 2, wherein the processing includes processing using pressure distribution data indicating the surface distribution of the applied pressure, derived based on the color-forming member image, and pressure distribution time series data indicating the time progression of the surface distribution of the applied pressure, derived based on time series data of the output value of the sensor device.

[0067] (Supplementary Note 4) The pressure measurement method according to Supplementary Note 3, wherein the processing includes a process of correcting a pressure value at each position and each time point in the pressure distribution time-series data using the pressure distribution data.

[0068] (Supplementary Note 5) The pressure measurement method according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the sensor device is a piezo-resistive tactile sensor having a plurality of electrodes arranged on a surface of a substrate and a pressure-sensitive conductive member covering the plurality of electrodes.

[0069] (Supplementary Note 6) The pressure measurement method according to Supplementary Note 5, wherein each of the plurality of electrodes has a thickness of 20 μm or less.

[0070] (Supplementary Note 7) The pressure measurement method according to Supplementary Note 5 or Supplementary Note 6, wherein each of the plurality of electrodes is partially embedded in the substrate so as to expose a surface thereof.

[0071] (Supplementary Note 8) The pressure measurement method according to any one of Supplementary Note 5 to Supplementary Note 7, wherein the pitch of the plurality of electrodes is 1000 μm or less.

[0072] (Supplementary Note 9) The pressure measurement method according to any one of Supplementary Note 5 to Supplementary Note 8, wherein the base material in contact with the color-developing member is made of a material having a pencil hardness of 2H or more.

[0073] (Supplementary Note 10) The pressure measuring device according to Supplementary Note 1, wherein the sensor device is of any one of a capacitance type, a pressure-sensitive rubber type, and a TFT type.

[0074] (Appendix 11) An information processing device having at least one processor, wherein the processor: acquires a color-forming member image, which is a photographed image of the color-forming member after pressure is applied, when pressure is applied to a color-forming member that develops a color at a density according to the applied pressure and a sensor device that outputs an output value according to the applied pressure while the color-forming member and the sensor device are stacked; acquires time series data of the output values ​​of the sensor device during the pressure application period; performs processing based on the color-forming member image and the time series data of the output values ​​of the sensor device; and when a pressure of 50 MPa is applied to the sensor device, the maximum height roughness Rz of the contact surface of the sensor device with the color-forming member is 20 μm or less.

[0075] (Appendix 12) A program for causing at least one processor of an information processing device to execute processing based on the color-forming member image and the time series data of the output values ​​of the sensor device during the pressure application period, when pressure is applied to a color-forming member that develops color at a density according to the applied pressure and a sensor device that outputs an output value according to the applied pressure, the program comprising: a color-forming member image that is a photographed image of the color-forming member after the pressure is applied when the color-forming member and the sensor device are stacked on top of each other; and time series data of the output values ​​of the sensor device, the maximum height roughness Rz of the contact surface of the sensor device with the color-forming member being 20 μm or less when a pressure of 50 MPa is applied to the sensor device.

[0076] (Supplementary Note 13) A pressure measurement method comprising: acquiring a color-forming member image, which is a photographed image of the color-forming member after application of pressure, when pressure is applied to a color-forming member that develops color with a density according to the applied pressure and a sensor device that outputs an output value according to the applied pressure, with the color-forming member and the sensor device overlapping; acquiring time series data of output values ​​of the sensor device during the pressure application period; deriving pressure distribution data showing a surface distribution of the applied pressure based on the color-forming member image; deriving pressure distribution time series data showing a time transition of the surface distribution of the applied pressure based on the time series data of output values ​​of the sensor device; and correcting pressure values ​​at each position and each time point in the pressure distribution time series data using the pressure distribution data; and wherein when a pressure of 50 MPa is applied to the sensor device, the maximum height roughness Rz of the contact surface of the sensor device with the color-forming member is 20 μm or less.

[0077] The disclosure of Japanese Patent Application No. 2023-140447, filed on August 30, 2023, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference.

Claims

1. A pressure measurement method comprising the steps of: applying pressure to a color-forming member that develops a color with a density corresponding to the applied pressure and a sensor device that outputs an output value corresponding to the applied pressure, while the color-forming member and the sensor device are stacked; acquiring a color-forming member image, which is a photographed image of the color-forming member after pressure is applied; acquiring time series data of the output value of the sensor device during the pressure application period; and executing processing based on the color-forming member image and the time series data of the output value of the sensor device by at least one processor provided in an information processing device; and when a pressure of 50 MPa is applied to the sensor device, the maximum height roughness Rz of the contact surface of the sensor device with the color-forming member is 20 μm or less.

2. The pressure measurement method according to claim 1, wherein the processing includes processing relating to a surface distribution of the applied pressure based on time-series data of the output value of the sensor device.

3. A pressure measurement method as described in claim 2, wherein the processing includes processing using pressure distribution data indicating the surface distribution of the applied pressure derived based on the color-forming member image, and pressure distribution time series data indicating the time progression of the surface distribution of the applied pressure derived based on time series data of the output value of the sensor device.

4. The pressure measurement method according to claim 3, wherein the processing includes a process of correcting pressure values ​​at each position and each time point of the pressure distribution time series data using the pressure distribution data.

5. A pressure measurement method according to any one of claims 1 to 4, wherein the sensor device is a piezo-resistive tactile sensor having a plurality of electrodes arranged on the surface of a substrate and a pressure-sensitive conductive member covering the plurality of electrodes.

6. The pressure measurement method according to claim 5, wherein the thickness of each of the plurality of electrodes is 20 μm or less.

7. The pressure measurement method according to claim 5, wherein each of the plurality of electrodes is partially embedded in the substrate so as to expose a surface thereof.

8. The pressure measurement method according to claim 5, wherein the pitch of the plurality of electrodes is 1000 μm or less.

9. The pressure measuring method according to claim 5, wherein the base material in contact with the color-developing member is made of a material having a pencil hardness of 2H or more.

10. A pressure measuring method according to any one of claims 1 to 4, wherein the sensor device is of a capacitance type, a pressure-sensitive rubber type or a TFT type.

11. An information processing device having at least one processor, wherein the processor: acquires a color-forming member image, which is a photographed image of the color-forming member after application of pressure when pressure is applied to a color-forming member that develops a color with a density according to the applied pressure and a sensor device that outputs an output value according to the applied pressure while the color-forming member and the sensor device are stacked; acquires time series data of the output value of the sensor device during the period of pressure application; performs processing based on the color-forming member image and the time series data of the output value of the sensor device; and when a pressure of 50 MPa is applied to the sensor device, the maximum height roughness Rz of the contact surface of the sensor device with the color-forming member is 20 μm or less.

12. A program for obtaining a color-forming member image, which is a photographed image of the color-forming member after pressure is applied, when pressure is applied to a color-forming member that develops a color with a density according to the applied pressure and a sensor device that outputs an output value according to the applied pressure, while the color-forming member and the sensor device are stacked together; obtaining time series data of the output value of the sensor device during the pressure application period; and having at least one processor provided in an information processing device execute processing based on the color-forming member image and the time series data of the output value of the sensor device, wherein the maximum height roughness Rz of the contact surface of the sensor device with the color-forming member is 20 μm or less when a pressure of 50 MPa is applied to the sensor device.

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