Pressure sensor structure

Abstract

To provide a pressure sensor structure suitable for detection of the pressure of a fluid.SOLUTION: A pressure sensor structure includes a first plate-shaped part, a second electrode, and a wall part. The pressure sensor structure detects the pressure of a fluid received by a detection target surface of a detection target object. The first plate-shaped part includes a first support part having a pressure reception surface to receive the pressure of the fluid and a first electrode provided at the first support part, and is flexible. The second electrode is disposed facing the first electrode with a space therebetween. The wall part is provided so as to form a hollow part sealed between the first electrode and the second electrode and surround the hollow part. The pressure sensor structure detects the pressure of the fluid received by the detection target surface by using the deformation of the first plate-shaped part with the reception of the fluid on the pressure reception surface and the change in electrostatic capacitance of a sensor part including a variable capacitance capacitor formed by the first electrode and the second electrode disposed facing each other through the hollow part. The pressure sensor structure detects either pressure of the fluid with the pressure higher than a reference pressure, which is the pressure in the hollow part, and the fluid with the pressure lower than the reference pressure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure sensor structure. [Background technology]

[0002] During product development, a pressure sensor may be installed in a prototype or product to measure the fluid pressure acting on the surface of the prototype or product. For example, to detect the fluid pressure on the surface of an aircraft wing, a minute pressure hole is installed in a specimen simulating the wing, and a pressure pipe is attached through the pressure hole. The pipe is then connected to the pressure sensor to detect the state quantity acting on the specimen. In recent years, a method has been proposed in which pressure pipes are closely packed within a model using additive manufacturing (see Patent Document 1).

[0003] Furthermore, when detecting pressure applied to a prototype or product in a location without a pressure hole, it has been proposed to apply a pressure-sensitive paint, whose luminescence intensity changes depending on the pressure, to a thickness of about 50 μm (see Non-Patent Document 1).In addition, a pressure sensor has been proposed in which pressure-sensitive paint is applied to a porous material with through-holes (see Patent Document 2).

[0004] Furthermore, small MEMS pressure sensors measuring 2.0 mm×2.0 mm×0.8 mm are available on the market (see Non-Patent Document 2).

[0005] In recent years, a method has also been proposed in which a thin film-type pressure sensor is attached to a prototype or product. For example, Patent Document 3 proposes a method in which a wing-shaped movable structure is formed on a resin film, and the movable structure is deformed by pressure, and this movement is detected by a strain sensor. Another proposed film-type pressure sensor is a sensor that is attached to the fingertips of a robot hand to detect the force used when grasping an object (see Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-206987 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-205174 [Patent Document 3] Japanese Patent Application Publication No. 2019-135458 [Patent Document 4] Patent Publication No. 2021-63801 [Non-patent literature]

[0007] [Non-Patent Document 1] Kazunori Mitsuo, Kazuyuki Nakakita, Mitsuru Kurita, and Shigeya Watanabe, "Japan Aerospace Exploration Agency Research and Development Report JAXA-RR-13-005," "JAXA Pressure-Sensitive Paint (PSP) Detection System Research and Development (1) - Overview," February 28, 2014, 47 pages [Non-patent document 2] https: / / www.bosch-sensortec.com / media / boschsensortec / downloads / datasheets / bst-bmp581-ds004.pdf Summary of the Invention [Problem to be solved by the invention]

[0008] The aforementioned method of installing pressure pipes through tiny pressure holes in a test specimen cannot be applied to thin specimens, and the number of pressure holes that can be placed is significantly limited by the cross-sectional area of ​​the specimen. Furthermore, the test specimen must be fabricated after determining the desired pressure and the location of the pressure holes and pressure pipes in advance. This makes it difficult to install additional pressure holes and pressure pipes for additional tests. Furthermore, since the pipes must be routed internally, spatial and strength limitations exist, making expansion difficult. Furthermore, when a test specimen is fabricated using additive manufacturing with a densely packed pressure pipe arrangement, the surface is rough and lacks precision, requiring polishing for finishing in test specimens intended for fluid detection. This creates problems, such as the pressure holes becoming blocked by polishing, which limits the placement of pressure holes.

[0009] The pressure-sensitive paint coating mentioned above cannot detect pressures in areas other than those that are optically accessible, and in order to impart pressure sensitivity, the coating must be applied very thinly and uniformly, at around 50 μm, which requires skilled painting techniques. Furthermore, pressure sensors in which pressure-sensitive paint is applied to porous materials with through-holes are rarely applicable to test specimens that require strength, and optical access is limited in the case of test specimens with complex shapes.

[0010] Although the MEMS pressure sensor described above can acquire positive and negative pressures, existing sensors are at least 0.8 mm thick, excluding the base, and create unevenness when installed on the surface of a test specimen. In particular, when detecting fluids, these unevenness can adversely affect the movement of the fluid. Furthermore, incorporating a MEMS pressure sensor into a test specimen requires processing of the specimen, which, like the creation of a pressure hole described above, poses spatial and strength limitations. Furthermore, the base of existing MEMS pressure sensors lacks flexibility, making it difficult to deform to fit the surface shape of the test specimen.

[0011] In the film sensor with the movable blade structure described above, the front and back of the sensing part are spatially connected, so no reaction is obtained when it comes to fluid pressure such as atmospheric pressure because no pressure difference occurs between the front and back of the sensing part. Therefore, the sensor is limited to applications such as detecting pressure that involves mechanical contact.

[0012] The film-type pressure sensor attached to the fingertips of the robot hand described above has many layers that make up the sensor, and is about 1 mm thick overall, which can have a negative effect on the movement of the fluid when detecting it.

[0013] In view of the above circumstances, an object of the present invention is to provide a pressure sensor structure suitable for detecting the pressure of a fluid. [Means for solving the problem]

[0014] To achieve the above object, a pressure sensor structure according to one embodiment of the present invention includes a first plate-shaped portion, a second electrode, and a wall portion. The pressure sensor structure detects the pressure of a fluid that is applied to the detection target surface of the detection target. The first plate-shaped portion has a first support portion having a pressure-receiving surface that receives the pressure of the fluid, and a first electrode provided on the first support portion, and is flexible. The second electrode is disposed opposite to and spaced apart from the first electrode. The wall portion is provided to surround the hollow portion such that a sealed hollow portion is formed between the first electrode and the second electrode. The pressure sensor structure detects the pressure of the fluid received by the detection target surface by utilizing the change in capacitance of the sensor section, which consists of a variable capacitor formed by the first electrode and the second electrode arranged opposite each other through the hollow section, as the first plate-shaped section deforms when the fluid is received by the pressure-receiving surface. The pressure sensor structure detects the pressure of both a fluid having a higher pressure than the reference pressure, which is the pressure inside the hollow portion, and a fluid having a lower pressure than the reference pressure.

[0015] According to this configuration of the present invention, by making the hollow portion that constitutes part of the sensor unit consisting of the variable capacitor into a sealed space, it is possible to obtain a pressure sensor structure that is suitable for detecting the pressure of a fluid.

[0016] The electrode assembly may be configured by stacking a sheet-like first electrode sheet having the first plate-like portion, a sheet-like second electrode sheet having a second plate-like portion having a second support portion arranged in contact with the surface to be detected and the second electrode provided on the second support portion, and a sheet-like spacer sheet arranged between the first electrode sheet and the second electrode sheet and having an opening with an opening edge portion that forms the wall portion, in the order of the second electrode sheet, the spacer sheet, and the first electrode sheet, and the hollow portion may be an area surrounded by the first electrode sheet, the second electrode sheet, and the opening edge portion.

[0017] The device may further include a second plate-shaped portion having a second support portion arranged in contact with the surface to be detected and the second electrode provided on the second support portion, and the first plate-shaped portion, the second plate-shaped portion and the wall portion may be a flexible sheet-like portion integrally molded based on additive manufacturing.

[0018] The second electrode may be provided on the surface to be detected, and the object to be detected, the first plate-shaped portion, the second electrode, and the wall portion may be integrally formed based on additive manufacturing and integrated with the object to be detected.

[0019] The first plate-shaped portion may have a dimension in the thickness direction of the pressure sensor structure of not less than 2 μm and not more than 131 μm, and the wall portion may have a dimension in the thickness direction of more than 0 and not more than 300 μm.

[0020] A plurality of the sensor units may be provided.

[0021] The pressure sensor structure may further include a signal processing unit. The signal processing unit converts the capacitance value detected by the sensor unit into a pressure value based on the curvature radius information of the surface to be detected, using calibration coefficient information that converts the capacitance value into a pressure value, which is set in advance for each radius of curvature of the surface to be detected.

[0022] The detection object may be an imitation of an aircraft wing. [Effects of the Invention]

[0023] According to the present invention, a pressure sensor structure suitable for detecting the pressure of a fluid can be provided. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is an exploded perspective view for explaining the basic configuration of a pressure sensor sheet (pressure sensor structure) according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the pressure sensor sheet. [Figure 3](A) and (B) are partial cross-sectional views of the pressure sensor sheet taken along line III-III in Figure 2, where (A) shows an example in which the detection target surface is a flat surface, and (B) shows an example in which the detection target surface is a curved surface. [Figure 4] FIG. 2 is a functional configuration diagram of the pressure sensor sheet. [Figure 5] 10A and 10B are diagrams showing an example of how the pressure sensor sheet is used to detect the pressure of a fluid applied to a detection target surface of a test piece (detection target). [Figure 6] FIG. 10 is a partial plan view of a pressure sensor sheet according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a partial cross-sectional view of a pressure sensor sheet according to a third embodiment of the present invention. [Figure 8] FIG. 10 is a partial cross-sectional view of a pressure sensor sheet according to a fourth embodiment of the present invention. [Figure 9] FIG. 10 is a partial cross-sectional view of a pressure sensor structure according to a fifth embodiment of the present invention. [Figure 10] FIG. 10 is a schematic exploded perspective view of a pressure sensor sheet according to a sixth embodiment of the present invention. [Figure 11] FIG. 10 is a functional configuration diagram of a pressure sensor sheet according to a sixth embodiment. [Figure 12] FIG. 13 is a schematic partial cross-sectional view showing a state in which a pressure sensor sheet according to a sixth embodiment is arranged on a specimen; [Figure 13] FIG. 13 is a schematic partial cross-sectional view of a pressure sensor sheet according to a seventh embodiment of the present invention. [Figure 14] 10(A) is a schematic plan view of a pressure sensor sheet according to an eighth embodiment, showing an example of electrode arrangement, and FIG. 10(B) is a schematic plan view of a pressure sensor sheet according to a ninth embodiment, showing an example of electrode arrangement. [Figure 15] FIG. 23 is a schematic exploded perspective view of a pressure sensor sheet according to a tenth embodiment of the present invention. [Figure 16] FIG. 23 is a schematic exploded perspective view of a pressure sensor sheet according to an eleventh embodiment of the present invention. [Figure 17] 10 is a graph showing the measurement results of capacitance when pressure is applied to the pressure sensor sheet of Example 1. [Figure 18] 10 is a graph showing the relationship between capacitance and pressure detected by the pressure sensor sheet of Example 2 in a wind tunnel experiment. [Figure 19] 10 is a graph showing the relationship between capacitance and pressure detected by the pressure sensor sheet of Example 3 in a wind tunnel experiment. [Figure 20] 10 is a graph showing the relationship between the thickness of the spacer sheet and the coefficient of determination (R2) for an approximation curve showing the relationship between pressure and capacitance change. [Figure 21] 10 is a graph showing the relationship between the thickness of a spacer sheet and a sensitivity coefficient. [Figure 22] 10 is a graph showing the relationship between capacitance and pressure for each radius of curvature of the detection target surface. [Figure 23] 10 is a graph showing the relationship between pressure and capacitance for each radius of curvature of the detection target surface. DETAILED DESCRIPTION OF THE INVENTION

[0025] <Outline of pressure sensor structure>

[0026] A pressure sensor structure according to the present invention detects the pressure of a fluid received by a detection target surface of a detection target. The pressure sensor structure is typically in the form of a flexible sheet that can be placed on the detection target surface. Hereinafter, a sheet-like pressure sensor structure may be referred to as a pressure sensor sheet. Although details will be described later using the fifth embodiment as an example, a part of the pressure sensor structure may be configured as the detection target, and the detection target and the sensor unit may be integrated. In the following first to fourth embodiments and sixth to eleventh embodiments, a flexible sheet-like pressure sensor sheet will be described, but the pressure sensor sheet is configured separately from the detection target.

[0027] The pressure sensor structure of the present invention is capable of detecting fluid pressure acting on a detection target surface, including flat surfaces as well as curved surfaces, of a detection target. The pressure sensor structure can be used, for example, to detect fluid pressure acting on the surface of a detection target in a wind tunnel experiment. In a wind tunnel experiment, a model (sometimes referred to as a "specimen") simulating an aircraft wing as the detection target is fixed and positioned, and an artificial air flow is generated to flow air around the specimen, simulating an actual flow field. The pressure sensor structure is positioned so that the sensor portion of the pressure sensor structure is located on the detection target surface of the specimen, and the fluid pressure acting on the surface of the specimen in the simulated flow field can be detected.

[0028] FIG. 5 shows a specimen 6, which is a detection target used in a wind tunnel experiment to evaluate pressure sensor sheets according to the embodiments of the present invention described below. As shown in FIG. 5, the specimen 6 is a model of an aircraft wing, which is the detection target. The specimen 6 has a curved surface 60. The cross-sectional shape (airfoil shape) of the specimen 6 typically has a rounded leading edge, which is the edge on the forward side of the aircraft's direction of travel, and a pointed trailing edge, which is the edge on the opposite side of the direction of travel (rear side), with a streamlined shape formed by curves extending from the front to the rear. The specimen 6 is typically made of a hard material. As shown in FIG. 5, when evaluating a pressure sensor sheet in a wind tunnel experiment, a pressure sensor sheet 100 is placed on the surface 60 of the specimen 6 so that a sensor unit 7 (described later) overlaps the detection target surface 60a of the specimen 6. The pressure sensor sheet 100 is fixed to the surface 60 with tape or the like (not shown).

[0029] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Each drawing appropriately shows X, Y, and Z axes, which are mutually orthogonal coordinate axes. For convenience, in this specification, the X and Y axes are set parallel to each of two orthogonal sides of a rectangular pressure sensor sheet, and the Z axis is set perpendicular to the X and Y axes. The Z axis direction corresponds to the thickness direction of the pressure sensor sheet. In FIG. 5, the X axis direction is the front-to-rear direction of the test piece 6, the Y axis direction is the height direction of the test piece 6, and the Z axis direction is the blade thickness direction of the test piece 6. In the following description, the same reference numerals are used for previously mentioned components, and their description may be omitted.

[0030] In this specification, "top" of a pressure sensor sheet refers to the direction away from the detection object (such as the test piece 6) in the thickness direction (Z-axis direction) when the pressure sensor sheet is placed on the detection object, and "bottom" refers to the direction closer to the detection object. Viewing the pressure sensor sheet from above in its thickness direction (Z-axis direction) is called a planar view. "Planar dimensions" refer to the shape dimensions when viewed in a planar view.

[0031] First Embodiment

[0032] [Overall configuration of pressure sensor sheet]

[0033] FIG. 1 is an exploded perspective view illustrating the basic configuration of a pressure sensor sheet 100 according to a first embodiment. FIG. 2 is a plan view of the pressure sensor sheet 100. FIGS. 3(A) and 3(B) are partial cross-sectional views of the pressure sensor sheet 100 taken along line III-III in FIG. 2, showing the pressure sensor sheet 100 placed on a surface 60 of a test piece 6 so that the sensor sections 7 overlap the detection target surface 60a. FIG. 3(A) shows an example in which the detection target surface 60a is a flat surface, and FIG. 3(B) shows an example in which the detection target surface 60a is a curved surface. The pressure sensor sheet 100 is capable of measuring fluid pressure received on both flat and curved surfaces.

[0034] The pressure sensor sheet 100 detects the fluid pressure acting on the surface of the specimen 6. The pressure sensor sheet 100 is in the form of a flexible sheet.

[0035] As shown in FIGS. 1, 2, 3A, and 3B, the pressure sensor sheet 100 of this embodiment includes a first electrode sheet 1 as a first component, a second electrode sheet 2 as a second component, and a spacer sheet 3 as a third component disposed between the first electrode sheet 1 and the second electrode sheet 2. The pressure sensor sheet 100 is configured by stacking the second electrode sheet 2, the spacer sheet 3, and the first electrode sheet 1 in this order. In this embodiment, the first electrode sheet 1, the second electrode sheet 2, and the spacer sheet 3 are all flexible, and the pressure sensor sheet 100 formed by stacking these is also flexible. In this specification, the "first component" includes a first plate-shaped portion (including a first electrode and a first support portion supporting the first electrode), which will be described later; the "second component" includes a second electrode and a second support portion that is provided with and supports the second electrode; and the "third component" includes a wall portion surrounding a hollow portion, which will be described later.

[0036] The first electrode sheet 1 is a sheet that forms the surface that directly receives the fluid and is located on the upper side of the pressure sensor sheet 100. The first electrode sheet 1 includes a first sheet 10, a first electrode 15, a first lead-out wiring 16, and a first pad electrode 17. The first sheet 10 is flexible. The first sheet 10 has an upper surface 10a, which is one surface, and a lower surface 10b, which is the other surface. The first electrode 15, the first lead-out wiring 16, and the first pad electrode 17 are provided on the lower surface 10b. The first lead-out wiring 16 electrically connects the first electrode 15 and the first pad electrode 17. The first electrode 15, the first lead-out wiring 16, and the first pad electrode 17 can be formed on the first sheet 10 by printing, for example, and the same applies to the second electrode sheet 2 and the spacer sheet 3. Note that the method for forming the wiring and electrodes is not limited to printing, and any known forming method can be used.

[0037] The second electrode sheet 2 is the sheet that contacts the surface 60 including the detection target surface 60a of the specimen 6, and is the sheet located below the pressure sensor sheet 100. The second electrode sheet 2 has a second sheet 20, a second electrode 25, and a second lead-out wiring 26. The second sheet 20 is flexible. The second sheet 20 has one surface, an upper surface 20a, and the other surface, a lower surface 20b. The second electrode 25 and the second lead-out wiring are provided on the upper surface 20a. The second lead-out wiring 26 is electrically connected to the second electrode 25.

[0038] The spacer sheet 3 has a third sheet 30 having an opening 34 formed by a rectangular through-hole in a plan view, a third pad electrode 31, and a third lead-out wiring 32. The third sheet 30 is flexible. The third sheet 30 has an upper surface 30a, which is one surface, and a lower surface 30b, which is the other surface. The third pad electrode 31 and the third lead-out wiring 32 are provided on the upper surface 30a. The third pad electrode 31 is electrically connected to the first pad electrode 17 by a conductive material such as a conductive paste (not shown), and the first electrode 15 is electrically connected to the third lead-out wiring 32.

[0039] As shown in FIGS. 1 and 2, the first electrode sheet 1 and the second electrode sheet 2 have rectangular outer shapes. The Y-axis dimension of the first electrode sheet 1 is the same as the Y-axis dimension of the second electrode sheet 2. Meanwhile, the X-axis dimension of the first electrode sheet 1 is shorter than the X-axis dimension of the second electrode sheet 2. The second electrode sheet 2 protrudes in the X-axis direction beyond the first electrode sheet 1 and has a non-overlapping portion 36 that does not overlap with the first electrode sheet 1 in a planar view. A portion of the second lead-out wiring 26 is arranged in the non-overlapping portion 36.

[0040] As shown in FIG. 1, the spacer sheet 3 has a shape in which two rectangles of different dimensions are connected in a plan view. Of these two rectangles, the rectangle with the shorter dimension in the Y-axis direction is referred to as the first rectangle, and the rectangle with the longer dimension is referred to as the second rectangle. The first rectangle protrudes from the short side (the side parallel to the Y-axis direction) of the second rectangle and extends in the X-axis direction. The outer dimensions of the second rectangle are the same as those of the first electrode sheet 1, and the two overlap in a plan view. The overall dimension of the spacer sheet 3 in the X-axis direction is the same as that of the second electrode sheet 2. A third outgoing wiring 32 is arranged on the upper surface of the protruding portion (first rectangle). The protruding portion (first rectangle) is arranged on the non-overlapping portion 36 of the second electrode sheet 2, and the second outgoing wiring 26 and the third outgoing wiring 32 are both arranged on the upper surface side of the non-overlapping portion 36.

[0041] 1 and 2, the first electrode 15, the second electrode 25, and the opening 34 overlap in a plan view. In this embodiment, the first electrode 15, the second electrode 25, and the opening 34 all have a square shape in a plan view, and the planar dimensions of the first electrode 15 and the second electrode 25 are smaller than the planar dimensions of the opening 34. The first electrode 15 and the second electrode 25 are arranged within a region surrounded by an opening edge portion 341 that forms the opening 34 in a plan view.

[0042] 3(A) and 3(B), the portion of the first sheet 10 corresponding to the opening 34 is referred to as the first support portion 11, and the portion of the second sheet 20 corresponding to the opening 34 is referred to as the second support portion 21. The upper surface of the first support portion 11 forms a pressure-receiving surface 18. The pressure-receiving surface 18 is part of the upper surface 10a of the first sheet 10. A first electrode 15 is provided on the lower surface of the first support portion 11 (the surface opposite the pressure-receiving surface). The first support portion 11 and the first electrode 15 form the first plate-shaped portion 12. The lower surface of the second support portion 21 is the surface that contacts the detection target surface 60a. A second electrode 25 is provided on the upper surface of the second support portion 21. The second support portion 21 and the second electrode 25 form the second plate-shaped portion 22.

[0043] The spacer sheet 3, together with the first electrode sheet 1 and the second electrode sheet 2, forms a hollow portion 4. Specifically, the opening edge 341 of the opening 34 in the spacer sheet 3 forms a wall, and the area surrounded by the wall, the first plate-shaped portion 12, and the second plate-shaped portion 22 forms the hollow portion 4. The opening edge 341 is a wall provided to surround the hollow portion 4. The first electrode 15 and the second electrode 25 are arranged opposite each other and spaced apart in the Z-axis direction within the hollow portion 4. In other words, the first electrode 15 and the second electrode 25 are spaced apart due to the thickness of the spacer sheet 3. The hollow portion 4 is a sealed space, and the pressure within the hollow portion 4 is referred to as the reference pressure. For example, the reference pressure is 101.325 kPa (standard atmospheric pressure). The hollow portion 4 can be filled with air or an inert gas such as nitrogen gas or argon gas. From the standpoints of ease of fabrication and prevention of condensation, dry air is preferably used.

[0044] The sensor section 7 is a variable capacitance capacitor formed by a first electrode 15 and a second electrode 25 arranged opposite each other across the hollow section 4. The capacitance of the sensor section 7 changes depending on the pressure of the fluid received by the pressure-receiving surface 18 of the first plate-shaped section 12.

[0045] The second plate-shaped portion 22 is flexible and has flexibility. During detection, the pressure sensor sheet 100 is arranged so that the lower surface of the second plate-shaped portion 22 is in contact with the detection target surface 60a, and the second plate-shaped portion 22 can deform to fit the shape of the detection target surface 60a. By arranging the second plate-shaped portion 22 in contact with the detection target surface 60a, the position of the second electrode 25 is fixed.

[0046] The first plate-shaped portion 12 is flexible and has flexibility. During detection, when the pressure-receiving surface 18 of the sensor unit 7 receives a fluid with a pressure higher than the reference pressure, the first plate-shaped portion 12 deforms to move closer to the second plate-shaped portion 22, thereby narrowing the distance between the first electrode 15 and the second electrode 25. On the other hand, when the pressure-receiving surface 18 receives a fluid with a pressure lower than the reference pressure, the first plate-shaped portion 12 deforms to move away from the second plate-shaped portion 22, thereby widening the distance between the first electrode 15 and the second electrode 25. The change in the distance between the first electrode 15 and the second electrode 25 changes the capacitance of the variable capacitor (sensor unit). The pressure sensor sheet 100 detects the pressure received by the pressure-receiving surface 18 based on the change in capacitance. The pressure sensor sheet 100 detects both fluids with a pressure higher than the reference pressure and fluids with a pressure lower than the reference pressure in the hollow portion 4. In this specification, "positive pressure" means a pressure higher than a reference pressure, and "negative pressure" means a pressure lower than a reference pressure.

[0047] In the pressure sensor sheet 100 of this embodiment, by making the hollow portion 4 an enclosed space, when positive or negative pressure is applied to the pressure-receiving surface 18 and then the pressure is released, the distance between the first electrode 15 and the second electrode 25 can be quickly restored to the state it was in before the pressure was applied, and the pressure sensor sheet 100 has excellent restoration response.

[0048] Furthermore, since the pressure sensor sheet 100 is flexible, it can be easily deformed to fit the shape of the detection target surface 60a so as to fit tightly against the detection target surface 60a, and placed on the surface 60 of the specimen 6. This improves the detection accuracy of the fluid pressure received by the detection target surface 60a.

[0049] In this embodiment, an example is given in which the pressure sensor sheet 100 has one sensor unit 7, but it may have multiple sensor units 7 like the pressure sensor sheets shown in the sixth to eleventh embodiments described below, and it is also possible to obtain information on the fluid pressure distribution received by the surface of the test specimen.

[0050] The first electrode sheet 1 and the spacer sheet 3, and the spacer sheet 3 and the second electrode sheet 2, can be bonded together using an adhesive (not shown). While an example of using an adhesive to bond the sheets together has been described, adjacent sheets can also be melted and bonded together without using an adhesive. In this case, the pressure sensor sheet 100 can be made thinner by the thickness of the adhesive, making it easier to deform the pressure sensor sheet to conform to the shape of the detection target surface 60a of the test piece 6. Furthermore, during wind tunnel testing, unevenness on the test piece surface caused by the placement of the pressure sensor sheet can be prevented from adversely affecting the flow of fluid. Known methods, such as heat press lamination, ultrasonic welding, and laser welding, can be used to melt and bond the sheets together. When using an adhesive, the thickness of one layer of adhesive can be approximately 20 μm or less.

[0051] The materials constituting the first sheet 10, the second sheet 20, and the third sheet 30 can be appropriately selected depending on the application of the pressure sensor sheet 100 and the environment in which it is applied. The first sheet 10, the second sheet 20, and the third sheet 30 are preferably made of insulating materials that allow electrodes to be formed on the sheets and can maintain good airtightness within the hollow portion 4. For example, sheet-like sheets made of materials such as polyimide, PET (polyethylene terephthalate), and PDMS (polydimethylsiloxane) can be used. Furthermore, from the viewpoint of ensuring overall flexibility of the pressure sensor sheet 100, it is preferable that the first sheet 10, the second sheet 20, and the third sheet 30 are all made of materials and have thicknesses that allow flexibility. In this embodiment, an example is given in which flat polyimide sheets are used for the first sheet 10, the second sheet 20, and the third sheet 30. The thickness of each sheet will be described later.

[0052] The first electrode 15 and the second electrode 25 can be made of known conductive materials such as copper, copper alloy, aluminum, aluminum alloy, silver, gold, Ag nanowire ink, and carbon-based materials such as carbon and graphene. The first electrode 15 and the second electrode 25 typically have a thickness on the order of several microns, approximately 1 μm to 6 μm, and are flexible. These electrodes can be formed by known methods such as printing or patterning by photoetching. In the pressure sensor sheet of this embodiment, an example is shown in which the electrodes made of copper are formed using a printing method.

[0053] [Functional configuration of pressure sensor sheet]

[0054] 4 is a functional configuration diagram of the pressure sensor sheet 100. As shown in FIG.

[0055] The signal processing unit 8 converts the capacitance value in the sensor unit 7 detected by the capacitance detection unit 5 into a pressure value using calibration coefficient information stored in a calibration coefficient DB (database) 9 based on the curvature radius information of the surface to be detected.

[0056] The signal processing unit 8 is realized by a processor such as a CPU (Central Processing Unit) provided in an arbitrary computer (information processing device) such as a PC (Personal Computer), a working memory, a non-volatile storage device, etc. A control program to be executed by the processor is stored in the storage device, and the processor reads the program into the working memory and executes it, thereby fulfilling the function of the signal processing unit 8.

[0057] The capacitance detection unit 5 detects the capacitance of the sensor unit 7 of the pressure sensor sheet 100. The capacitance detection unit 5 is configured, for example, by a CV converter including a CV conversion circuit. As shown in FIG. 4, a square-wave voltage (e.g., 3.3 V) generated from a power supply in the capacitance detection unit 5 is applied to the second electrode 25 via the second outgoing wiring 26. This square-wave voltage is transmitted to the first electrode 15 via the capacitance between the second electrode 25 and the first electrode 15 arranged opposite the second electrode 25, and further transmitted to the first outgoing wiring 16, the first pad electrode 17, the third pad electrode 31, and the third outgoing wiring 32, and is input to the capacitance detection unit 5 connected to the third outgoing wiring 32. The capacitance detection unit 5 converts the change in capacitance into a change in voltage and outputs a digital value of the capacitance.

[0058] The capacitance detection unit 5 includes a CV (capacitance-voltage) conversion circuit. The CV conversion circuit 50 converts impedance changes due to changes in capacitance into voltage changes. The pressure sensor sheet of this embodiment detects extremely small values, such as approximately 4 pF, by converting capacitance to voltage using the CV conversion circuit, making detection easier. For example, if the voltage emitted from the signal source is 3.3 V, the voltage converted by the CV conversion circuit and output is approximately 0.3 to 3 V. Using a CV conversion circuit in this way enables detection of small capacitances, thereby reducing the volume of the hollow portion and the amount of deformation of the first plate-shaped portion, thereby further improving recovery response and increasing the detection sensitivity of fluid pressure. In the capacitance detection unit 5, for example, the signal output from the CV conversion circuit is rectified by a rectifier circuit and converted into a digital value by an AD conversion circuit, thereby outputting a digital value of the capacitance.

[0059] The calibration coefficient DB9 stores information on calibration coefficients (calibration coefficient information) for converting capacitance values, which are set for each radius of curvature of the detection target surface and acquired in advance, into pressure values. When a pressure sensor sheet is placed on a detection target surface, the distance (inter-electrode distance) between the first electrode 15 and the second electrode 25 in the initial state (when no fluid pressure is applied) changes depending on the curvature of the detection target surface, in other words, the value of the radius of curvature of the detection target surface. The calibration coefficient information is prepared to take into account the difference in inter-electrode distance due to different radii of curvature, so that the same pressure sensor sheet can be used to convert detected capacitance values ​​into accurate pressure values ​​for curved surfaces of any radius of curvature. Alternatively, only calibration coefficient information when the pressure sensor sheet is placed on a flat plate may be used, and the applicable curvature may be limited to a range of curvatures within the allowable accuracy.

[0060] The signal processing unit 8 extracts a calibration coefficient corresponding to the radius of curvature from the calibration coefficient DB 9 based on information about the radius of curvature of the detection target surface to which the sensor units 7 of the pressure sensor sheet 100 are positioned, and converts the capacitance value output from the capacitance detection unit 5 into a pressure value using the calibration coefficient. In this way, the pressure sensor sheet 100 detects the pressure of the fluid received by the detection target surface 60a on which the sensor units 7 are arranged. The information about the radius of curvature of the detection target surface 60a to which the sensor units 7 are positioned may be obtained, for example, using design information of the test piece (detection target) or by measurement using a known curvature measurement device.

[0061] In the pressure sensor sheet 100 of this embodiment, the second lead-out wiring 26 and the third lead-out wiring 32 are both arranged on the upper surface side of the non-overlapping portion 36, which simplifies the wiring structure.

[0062] In this embodiment, a pressure sensor sheet having one sensor unit 7 has been exemplified, but as in the sixth to eleventh embodiments described below, the pressure sensor sheet may have a plurality of sensor units 7. By having a plurality of sensor units 7, it is possible to determine, for example, the fluid pressure distribution applied to the surface of the detection object. When the detection object has a surface with a different radius of curvature depending on the location, the signal processing unit 8 can convert the capacitance value into a pressure value using a calibration coefficient according to the radius of curvature of the detection object surface to which each of the plurality of sensor units is positioned, and an accurate fluid pressure distribution can be obtained.

[0063] [Actions and Effects] In the pressure sensor sheet (pressure sensor structure), the hollow portion 4 constituting the sensor unit 7 is an enclosed space, so that when positive or negative pressure is applied to the pressure-receiving surface 18 and then the pressure is released, the distance between the first electrode 15 and the second electrode 25 (in other words, the position of the first plate-shaped portion) can be quickly restored to the state before the pressure was applied. Thus, the pressure sensor sheet 100 has excellent restoration response and high detection accuracy for both positive and negative pressures, making it suitable for detecting fluid pressure. In particular, in wind tunnel experiments using a test specimen (detection object) simulating an aircraft wing, positive and negative fluid pressures can be applied to the surface (wing surface) of the detection object, and the pressure sensor sheet 100 is suitable for detecting fluid pressures applied to the surface of such a detection object. Similar effects are also achieved in the pressure sensor structures (including pressure sensor sheets) of the various embodiments described below.

[0064] Furthermore, since the pressure sensor sheet of this embodiment can detect pressure simply by placing it on the surface of the object to be detected, the pressure sensor sheet can be easily repositioned and reattached, making it highly convenient. Therefore, unlike conventional methods of installing pressure piping through tiny pressure holes in a test specimen, there is no need to determine the measurement location in advance and determine the placement of pressure holes and pressure piping before manufacturing the test specimen. Furthermore, additional tests can be easily performed simply by changing the placement of the pressure sensor sheet, without having to install additional pressure holes and pressure piping. Similar effects can be achieved with the pressure sensor sheets of the second to fourth and sixth to eleventh embodiments described below.

[0065] In addition, because the pressure sensor sheet of this embodiment has a thin, flexible sheet shape overall, it can be easily deformed to fit the surface shape of the object to be detected, even if the surface is not flat but has a complex shape such as a curved surface, making it possible to accurately detect the pressure of the fluid. Furthermore, because the pressure sensor sheet is thin overall, it is less likely to create unevenness on the surface of the test specimen (object to be detected) due to the presence of the pressure sensor sheet, which reduces the adverse effect of such unevenness on the movement of the fluid during wind tunnel testing, enabling highly accurate detection. Similar effects are also achieved in the pressure sensor sheets of the second to fourth and sixth to eleventh embodiments described below.

[0066] [Example dimensions for each configuration]

[0067] The pressure state experienced by the surface of an aircraft wing (airfoil) varies depending on the speed range. At low speeds (gentle breeze), pressures of several to several tens of Pas are exerted on the wing surface, with the difference between the highest and lowest pressures (differential pressure) being several Pas. On the other hand, at high speeds, such as cruising, pressures of approximately ±100 kPa are exerted on the wing surface, resulting in a large differential pressure of several tens of kPa. Thus, the differential pressure varies considerably depending on the speed range. Furthermore, at aircraft takeoff and landing speeds, pressures of approximately ±15 kPa are exerted on the wing surface. As such, an aircraft wing can be subjected to both negative and positive pressures, and observing the fluid pressure acting on the surface of a test specimen simulating an aircraft wing is important in product development. Here, we present example dimensions for each component of a pressure sensor structure suitable for detecting pressure experienced by the surface of a detection target, which is used in a general wind tunnel (a wind tunnel without particularly large pressure or pressure reduction). Note that the dimensions are not limited to those shown here.

[0068] The pressure sensor structure with the specifications shown below has excellent restoration response to the application of both positive and negative pressure, making it suitable for detecting fluid pressure on the surface of a test specimen, such as an aircraft wing, to which positive and negative pressures are applied. Furthermore, a sheet-type pressure sensor structure (pressure sensor sheet) can stably detect fluid pressure no matter where the pressure sensor sheet is placed on a single detection target (test specimen), even if the surface of the detection target has different radii of curvature depending on the location. This makes the pressure sensor sheet highly convenient, as it can be used repeatedly for detection by repositioning the pressure sensor sheet in different locations.

[0069] To improve the restoring response, the thickness of the first plate-shaped portion 12 having the pressure-receiving surface 18 is 2 μm to 131 μm, more preferably 2 μm to 18.5 μm, and the dimension of the wall portion in the thickness direction of the pressure sensor structure (e.g., corresponding to the thickness dimension of the spacer sheet 3 of the pressure sensor sheet 100; hereinafter, sometimes referred to as the "wall portion thickness") is greater than 0 μm to 300 μm, preferably greater than 0 μm to 200 μm, more preferably 12.5 μm to 100 μm, and even more preferably 12.5 μm to 50 μm. The thickness of the wall portion approximately corresponds to the distance in the thickness direction between the first plate-shaped portion 12 and the second plate-shaped portion 22. In this specification, the thickness of the first plate-shaped portion 12 refers to the thickness of the region where the first support portion 11 and the first electrode 15 overlap.

[0070] The thickness of the first electrode 15 is approximately 1 μm to 6 μm, and in a configuration in which the first electrode 15 is provided on the first support portion 11, such as the pressure sensor sheet 100 of the first embodiment, the thickness of the first support portion 11 (the thickness of the first sheet 10 of the pressure sensor sheet 100) is more than 0 μm and not more than 125 μm, more preferably not less than 10 μm and not more than 50 μm, from the viewpoint of achieving good recovery response.

[0071] The thickness of the spacer sheet 3 is set so that when the pressure sensor sheet is placed on the surface of the detection object, the first plate-shaped portion 12 and the second plate-shaped portion 22 do not come into contact with each other in either the initial state (when no fluid pressure is applied) or the applied state (when fluid pressure is applied). This prevents the first electrode 15 and the second electrode 25, which are arranged opposite each other, from coming into contact and short-circuiting, thereby enabling stable detection of fluid pressure.

[0072] The planar dimensions of the opening 34, which is square in plan view, can be set appropriately depending on the thickness of the first support portion, the thickness of the spacer, the planar dimensions of the first and second electrodes, and the like.

[0073] By reducing the planar dimensions of the first electrode, the second electrode and the opening, it is possible to obtain a pressure structure that is capable of detecting fluid pressure on a detection target surface with a smaller radius of curvature.

[0074] In the case of a pressure sensor sheet such as pressure sensor sheet 100 in which the second support portion on which the second electrode is provided is formed separately from the object to be detected (test specimen), the thickness of the entire pressure sensor sheet is 200 μm or less, more preferably 50 μm or less, in order to suppress interference with fluid movement during wind tunnel experiments.

[0075] When constructing a pressure sensor sheet by stacking multiple sheets, as in the case of pressure sensor sheet 100, it is preferable to use sheets with a thickness of 10 μm or more and 50 μm or less for the first sheet, second sheet, and spacer sheet, from the viewpoints of good processability and making the overall pressure sensor sheet thin and flexible.

[0076] Other embodiments will be described below, but the basic configuration is similar to that of the first embodiment, and differences will be mainly described.

[0077] As with the first embodiment, the pressure sensor structure (including the pressure sensor sheet) of each of the following embodiments includes a first plate-shaped portion having a pressure-receiving surface and a first electrode, a second electrode arranged opposite the first electrode and spaced apart in the thickness direction (Z-axis direction), and a wall portion surrounding the hollow portion to form a sealed hollow portion between the first and second electrodes. The pressure sensor structure includes a sensor portion consisting of a variable capacitor formed by the first and second electrodes arranged opposite each other across the hollow portion. In this sensor portion, the first plate-shaped portion also deforms upon receiving fluids at its pressure-receiving surface, which are higher and lower than the reference pressure within the hollow portion, causing a change in capacitance between the first and second electrodes. The pressure of the fluid received by the detection surface of the detection object can be detected from this change in capacitance. The pressure sensor structure of each of the following embodiments is suitable for detecting fluid pressure.

[0078] Second Embodiment

[0079] In the first embodiment described above, an example was given in which the outer shape of the pressure sensor sheet in a plan view was rectangular, but there are no limitations on the shape of the pressure sensor sheet and it can be changed as appropriate to match the shape of the detection target to which the pressure sensor sheet is applied. Furthermore, in the first embodiment, an example was given in which the outer shapes of the first electrode and the second electrode were rectangular, but there are no limitations on the shape of the electrodes. Furthermore, in the first embodiment, an example was given in which the extension direction of each lead wire is bent at 90 degrees, but the lead wire may be bent at another angle and there are no limitations on the shape of the lead wire.

[0080] FIG. 6 is a schematic plan view of a pressure sensor sheet 100A according to the second embodiment. The pressure sensor sheet 100A has the same basic structure as the pressure sensor sheet 100 according to the first embodiment. The outer shape of the pressure sensor sheet in plan view may be a nonagonal shape, as in the pressure sensor sheet 100A shown in FIG. 6, depending on the shape of the detection target. It may also be a polygonal shape, an elliptical shape, or a ring shape, and may be any other shape. The outer shapes of the first electrode 15, the second electrode 25, and the opening 34 in plan view may also be any other shape, such as a polygonal shape or an elliptical shape. As shown in FIG. 6, the wiring such as the first lead-out wiring 16 and the second lead-out wiring 26 may be bent at an angle other than 90 degrees while extending along the outer shape of the pressure sensor sheet 100A. The wiring may also be straight and not bent.

[0081] In this way, the outer shape of the pressure sensor sheet and the arrangement of the electrodes and wiring may be adjusted according to the shape of the object to be detected. The first electrode sheet, spacer sheet, and second electrode sheet are flexible and thin, making them easy to process, and it is easy to shape the outer shape of the pressure sensor sheet in a desired planar view.

[0082] <Third embodiment>

[0083] In the first embodiment, the electrodes (first electrode, second electrode) and wiring (first outgoing wiring, second outgoing wiring, third outgoing wiring) were all arranged on the surface of the first sheet, second sheet or third sheet, but the electrodes and / or wiring may be embedded inside the sheet, as in the pressure sensor sheet 100B shown in Figure 7.

[0084] The pressure sensor sheet 100B shown in FIG. 7 includes a first electrode sheet 1B and a second electrode sheet 2B arranged opposite each other with a gap therebetween, and a spacer sheet 3B arranged between the first electrode sheet 1B and the second electrode sheet 2B. These sheets are bonded together, for example, with an adhesive or the like. The first electrode sheet 1B has a pressure-receiving surface 18. The second electrode sheet 2B is arranged in contact with the surface 60 of the specimen 6, and the sensor unit 7 is arranged so as to be positioned on the detection target surface 60a. Similar to the pressure sensor sheet 100 according to the first embodiment, the pressure sensor sheet 100B has a hollow portion 4 surrounded by a first plate-shaped portion 12, a second plate-shaped portion 22, and an opening edge portion (wall portion) 341 of the opening 34 of the spacer sheet 3B.

[0085] The first electrode sheet 1B serving as the first component is a flexible sheet. The first electrode sheet 1B includes a polyimide layer 10B, a first electrode 15 embedded in the polyimide layer 10B, a first lead wiring 16 electrically connected to the first electrode 15, and the like. The portion of the polyimide layer 10B corresponding to the opening 34 is referred to as a first support portion 11. The first support portion 11 and the first electrode 15 embedded in the first support portion 11 form a first plate-shaped portion 12.

[0086] The second electrode sheet 2B serving as the second component is a flexible sheet. The second electrode sheet 2B is configured by forming a second electrode 25 on the upper surface 20a of a second sheet 20 made of a polyimide sheet. The portion of the second sheet 20 corresponding to the opening 34 is referred to as a second support portion 21. The second support portion 21 and the second electrode 25 form a second plate-shaped portion 22.

[0087] The spacer sheet 3B as the third component is a flexible sheet and includes a polyimide layer 30B, a third lead-out wiring 32 embedded in the polyimide layer 30B, and a conductive material 33 electrically connecting one end of the third lead-out wiring 32 to the second electrode 25.

[0088] In this way, the lead wiring and / or electrodes may be embedded in the electrode sheet (in the polyimide layer) or the spacer sheet. The electrode sheet and the spacer sheet in which the wiring and / or electrodes are embedded can be manufactured by known methods, and there are no limitations on the manufacturing method. For example, the pressure sensor sheet 100B can be manufactured using known methods for manufacturing multilayer substrates, additive manufacturing methods, etc. Additive manufacturing is a technique for creating a three-dimensional object by stacking layers of material based on 3D data.

[0089] In each embodiment, a layer other than the hollow portion 4, for example, an insulating layer such as a polyimide layer, may be present between the first electrode 15 and the second electrode 25. For example, the electrodes may be embedded in the electrode sheet (in the insulating layer), or the first electrode 15 may be disposed on the upper surface of the first electrode sheet. Such a configuration allows wiring to be routed in accordance with the object to be detected and the detection environment, thereby expanding the design range.

[0090] <Fourth embodiment>

[0091] FIG. 8 is a partial cross-sectional view of a pressure sensor sheet 100C according to a fourth embodiment. In the above-described embodiments, a pressure sensor sheet is manufactured by laminating and bonding a first electrode sheet, a spacer sheet, and a second electrode sheet. In contrast, the pressure sensor sheet 100C of this embodiment is manufactured by integrally molding a first component 1C including a first plate-shaped portion 12, a second component 2C including a second plate-shaped portion 22, and a third component 3C including a wall portion 117 through additive manufacturing. Referring to FIG. 8, the pressure sensor sheet 100C includes an insulating layer portion (indicated by alternating diagonal lines of two different thicknesses) corresponding to the polyimide sheet in the first embodiment and the polyimide layer in the third embodiment, as well as electrodes and wiring. The insulating layer portion can be manufactured using a material (material with a low elastic modulus) that remains soft after additive manufacturing to ensure flexibility of the pressure sensor sheet 100C. The electrodes and wiring can be manufactured using metal powder for additive manufacturing or resin containing metal powder.

[0092] As shown in FIG. 8, the pressure sensor sheet 100C is formed by integrating a first component part 1C, a third component part 3C, and a second component part 2C. The first to third component parts indicate regions when the pressure sensor sheet is virtually divided into layers stacked in the thickness direction (Z-axis direction). In the pressure sensor sheet 100C, the second component part 2C, the third component part 3C, and the first component part 1C are positioned in this order in the thickness direction (Z-axis direction). In the pressure sensor sheet 100C, the surface on the side of the first component part 1C includes a pressure-receiving surface 18 that receives a fluid, and the surface on the side of the second component part 2C is the surface that is placed in contact with the surface 60 of the specimen 6.

[0093] The first component 1C corresponds to the first electrode sheet 1 of the pressure sensor sheet 100 of the first embodiment, and includes a first plate-shaped portion 12 (first electrodes 15 and first support portions 11 that support the first electrodes 15). The first plate-shaped portion 12 has a pressure-receiving surface 18.

[0094] The second constituent part 2C corresponds to the second electrode sheet 2 of the pressure sensor sheet 100 of the first embodiment, and includes a second plate-shaped part 22 (a second electrode 25 and a second support part 21 that supports the second electrode 25).

[0095] The third component 3C corresponds to the spacer sheet 3 of the first embodiment, and includes a wall 117 that defines the area of ​​the hollow portion 4 in the XY plane. The wall 117 surrounds the hollow portion 4. The third component 3C, which includes the wall 117, is located between the first component 1C and the second component 2C.

[0096] The portion of first component 1C corresponding to hollow portion 4 constitutes first plate-shaped portion 12, and the portion of second component 2C corresponding to hollow portion 4 constitutes second plate-shaped portion 22. In other words, hollow portion 4 is an area surrounded by first plate-shaped portion 12, second plate-shaped portion 22, and wall portion 117. First electrode 15 and second electrode 25, which are arranged opposite each other with hollow portion 4 interposed therebetween, constitute sensor portion 7, which is made up of a variable capacitor.

[0097] In this way, the pressure sensor sheet may be manufactured by the additive manufacturing method, and in this pressure sensor sheet, an adhesive for bonding the electrode sheet and the spacer sheet is not required, allowing the overall thickness of the pressure sensor sheet to be thin, and interference with fluid movement during wind tunnel testing can be suppressed. Furthermore, by molding the pressure sensor sheet as a single unit using the additive manufacturing method, it becomes easier to ensure good sealing of the hollow portion 4, making it easier to maintain stable detection accuracy.

[0098] Fifth Embodiment

[0099] 9 is a partial cross-sectional view of a pressure sensor structure 110 according to the fifth embodiment. The pressure sensor structure 110 is manufactured by integrally molding the first plate-shaped portion 12, the second electrode 25, the detection object 116, and the wall portion 117 using additive manufacturing. Referring to FIG. 9, in the pressure sensor structure 110, the insulating layer portion, which corresponds to the polyimide sheet of the first embodiment or the polyimide layer of the third embodiment, the electrodes, the wiring, and the detection object are integrally molded.

[0100] 9, the pressure sensor structure 110 is formed by integrating a first component part 111, a third component part 113, and a second component part 112. The first to third component parts indicate regions when the pressure sensor structure 110 is virtually divided into layers stacked in the thickness direction (Z-axis direction).

[0101] The first constituent part 111 corresponds to the first electrode sheet 1 of the pressure sensor sheet 100 of the first embodiment, and includes a first plate-shaped part 12 (a first electrode 15 and a first support part 11 that supports the first electrode 15).

[0102] The second component part 112 is a region where the second electrode 25 and the detection object 116 on which the second electrode 25 is provided are integrated. Unlike the second electrode sheet 2 of the pressure sensor sheet 100 of the first embodiment, the pressure sensor structure 110 does not have a second support part 21 that is separate from the detection object and on which the second electrode 25 is provided. In the pressure sensor structure 110, the second electrode 25 is disposed on the detection object surface 116a of the detection object 116, and the detection object 116 also serves as the second support part.

[0103] The third component 113 corresponds to the spacer sheet 3 of the first embodiment, and includes a wall 117 that defines the area of ​​the hollow portion 4 in the XY plane. The wall 117 surrounds the hollow portion 4. The third component 113, which includes the wall 117, is located between the first component 111 and the detection target object 116.

[0104] The portion of the first component 111 that corresponds to the hollow portion 4 constitutes the first plate-shaped portion 12. The first plate-shaped portion 12 is constituted by the first support portion 11 and the first electrode 15. The hollow portion 4 is an area surrounded by the first plate-shaped portion 12, the detection object 6, and the wall portion 117 of the third component 113. The first electrode 15 and the second electrode 25, which are arranged opposite each other with the hollow portion 4 interposed therebetween, constitute the sensor portion 7, which is made up of a variable capacitor.

[0105] In the pressure sensor structure 110, at least the first plate-shaped portion 12 needs to be flexible, and the first support portion 11 can be manufactured using an insulating material that remains soft after molding for additive manufacturing. The electrodes and wiring can be manufactured using metal powder or resin containing metal powder for additive manufacturing, and the first electrode 15 can be made thick enough to ensure that the first plate-shaped portion 12 is flexible. The material used to mold the portion corresponding to the detection object 116 can be selected appropriately depending on the type of detection object. For example, if the detection object is a model of an aircraft wing, it may be molded using metal powder or resin containing metal powder for additive manufacturing. Note that in the pressure sensor structure 110 shown in FIG. 9, components other than the electrodes and wiring are indicated by hatched lines in the same pattern, indicating that the insulating layer constituting the sensor unit and the detection object are integrally molded.

[0106] In this way, the pressure sensor structure 110 may be configured such that the detection object and the sensor unit are integrated, eliminating the need for attaching a pressure sensor sheet to the detection object and improving workability. Furthermore, integral molding using additive manufacturing facilitates ensuring good sealing of the hollow portion 4, making it easier to maintain stable detection accuracy. Furthermore, an adhesive for bonding the electrode sheet and the spacer sheet is no longer necessary. Furthermore, since the detection object 116 also serves as the second support portion on which the second electrode 25 is provided, the thickness of the sensor unit 7 can be reduced by the thickness of the second sheet in the pressure sensor sheet of the first embodiment, allowing for more accurate detection of the pressure of the fluid received by the detection object surface.

[0107] Sixth Embodiment

[0108] Fig. 10 is a schematic exploded perspective view of a pressure sensor sheet 100D according to a sixth embodiment. Fig. 11 is a functional configuration diagram of the pressure sensor sheet 100D. Fig. 12 is a schematic partial cross-sectional view showing the pressure sensor sheet 100D placed on a specimen 6 having a curved surface 60. In Fig. 12, the drawing wiring is omitted for simplification.

[0109] In the above-described embodiments, examples have been given in which the pressure sensor structure (including the pressure sensor sheet) has one sensor unit 7. However, as in the pressure sensor sheet 100D, multiple sensor units 7 (nine in the example shown in the figure) may be provided on one pressure sensor sheet. This makes it possible to obtain data related to the pressure distribution received by the surface 60 of the detection target 6. When multiple sensor units are provided on one pressure sensor sheet, the number of lead wires connecting to the electrodes constituting each sensor unit increases. However, as shown in FIG. 10, by using multilayer wiring, multiple electrodes and wires can be provided in a limited space. The basic configuration of each sensor unit 7 provided on the pressure sensor sheet 100D is the same as in the first embodiment. Here, the differences will mainly be described.

[0110] The pressure sensor sheet 100D is flexible. As shown in FIGS. 10 and 12, the pressure sensor sheet 100D includes a first electrode sheet 1D as a first component, a second electrode sheet 2D as a second component, and a spacer sheet 3D as a third component disposed between the first electrode sheet 1D and the second electrode sheet 2D. The pressure sensor sheet 100D with multilayer wiring can be manufactured, for example, by hot-pressing the stacked second electrode sheet 2D, spacer sheet 3D, and first electrode sheet 1D. The first electrode sheet 1D and the second electrode sheet 2D are each formed by stacking polyimide sheets on which electrodes and / or lead wiring are formed. In the pressure sensor sheet 100D, the surface facing the first electrode sheet 1D includes a pressure-receiving surface 18 that receives a fluid, and the surface facing the second electrode sheet 2D is the surface that is placed in contact with the surface 60 of the test piece 6 during detection.

[0111] The first electrode sheet 1D is formed by laminating three polyimide sheets 101 to 103 (hereinafter referred to as sheets 101 to 103). First lead-out wires 16 and first electrodes 15 are formed on the sheets 101 to 103, respectively. Three first lead-out wires 16 (referred to as first lead-out wires 161) are provided on the lower surface of the sheet 101. Three first lead-out wires 16 (referred to as first lead-out wires 162) are provided on the lower surface of the sheet 102. Nine first electrodes 15 and three first lead-out wires 16 (referred to as first lead-out wires 163) are provided on the lower surface of the sheet 103. Three electrode groups, each consisting of three first electrodes 15 arranged at equal intervals in the Y-axis direction, are arranged at equal intervals along the X-axis direction. Of the electrode groups, three first electrodes 15 (referred to as first electrodes 151) constituting the electrode group on the far right in the drawing are electrically connected to a first lead-out wiring 161 on the sheet 101 by a conductive material filled in via holes (not shown) formed in the sheets 102 and 103. Of the three electrode groups, three first electrodes 15 (referred to as first electrodes 152) constituting the electrode group at the center in the drawing are electrically connected to a first lead-out wiring 162 on the sheet 102 by a conductive material filled in via holes (not shown) formed in the sheet 103. Three first electrodes 15 (referred to as first electrodes 153) constituting the electrode group on the far left in the drawing are electrically connected to a first lead-out wiring 163. When it is not necessary to distinguish between the first lead-out wirings 161, 162, and 163, they will be referred to as first lead-out wiring 16, and similarly, the first electrodes 151, 152, and 153 will be referred to as first electrodes 15.

[0112] The second electrode sheet 2D is formed by laminating three polyimide sheets 201 to 203 and bonding them together. Second lead-out wirings 26 and second electrodes 25 are formed on the sheets 201 to 203, respectively. Nine second electrodes 25 and three second lead-out wirings 26 (referred to as second lead-out wirings 263) are provided on the upper surface of the sheet 203. Three second lead-out wirings 26 (referred to as second lead-out wirings 262) are provided on the upper surface of the sheet 202. Three second lead-out wirings 26 (referred to as second lead-out wirings 261) are provided on the upper surface of the sheet 201. Three electrode groups, each consisting of three second electrodes 25 arranged at equal intervals in the Y-axis direction, are arranged at equal intervals along the X-axis direction. Of the electrode groups, three second electrodes 25 (referred to as second electrodes 251) constituting the electrode group on the far right in the drawing are electrically connected to second lead-out wiring 261 on sheet 201 by a conductive material filled in via holes (not shown) formed in sheets 203 and 202. Of the three electrode groups, three second electrodes 25 (referred to as second electrodes 252) constituting the electrode group at the center in the drawing are electrically connected to second lead-out wiring 262 on sheet 202 by a conductive material filled in via holes (not shown) formed in sheet 203. Three second electrodes 25 (referred to as second electrodes 253) constituting the electrode group on the far left in the drawing are electrically connected to second lead-out wiring 263. When there is no need to distinguish between the second lead-out wirings 261, 262, and 263, they will be referred to as second lead-out wiring 26, and similarly, second electrodes 251, 252, and 253 will be referred to as second electrodes 25.

[0113] The spacer sheet 3D is configured by providing a plurality of (here, nine) rectangular openings 34 in a third sheet 30 made of polyimide. Opening edge portions 341 of the openings 34 function as walls surrounding the hollow portion 4, and together with the first electrode sheet 1D and the second electrode sheet 2D, form the sealed hollow portion 4. The first electrode 15 and the second electrode 25 are disposed opposite each other with a space between them within the hollow portion 4.

[0114] In Figure 10, each sheet is shown schematically with lead-out wiring provided thereon, but as in the first embodiment, the lead-out wiring electrically connected to each electrode may be configured to be concentrated within the same plane.

[0115] As shown in FIG. 11 , each first electrode 15 serving as a detection electrode is electrically connected to a capacitance detection unit 5. Although not shown, each second electrode 25 serving as a reference electrode is electrically connected to a capacitance detection unit 5 to which the opposing first electrode 15 is connected. The capacitance detection unit 5 detects the capacitance of the sensor unit 7 of the pressure sensor sheet 100D. Multiple capacitance detection units 5 are arranged in parallel, converting capacitance changes into voltage changes and outputting a digital capacitance value. The signal processing unit 8 converts the capacitance value output from the capacitance detection unit 5 into a pressure value using calibration coefficient information stored in a calibration coefficient database 9 based on information about the radius of curvature of the detection target surface. Furthermore, the signal processing unit 8 generates image information of the pressure distribution to be displayed on a display device based on the discrete data (fluid pressure data) of the points detected by each sensor unit 7.

[0116] In this way, the pressure sensor sheet 100D having a plurality of sensor units 7 can obtain the pressure distribution received by the surface 60 of the detection target 6. Furthermore, the pressure sensor sheet 100D of this embodiment obtains corrected pressure values ​​using a calibration coefficient according to the radius of curvature of the detection target surface, so that an accurate pressure distribution can be obtained even if the radius of curvature of the detection target surface corresponding to each sensor unit 7 is different. The same applies to pressure sensor sheets having a plurality of sensor units 7 described in other embodiments below.

[0117] In the example shown in Figure 11, each of the multiple first electrodes 15 is individually connected to the capacitance detection unit 5, but the multiple first electrodes 15 and the multiple second electrodes 25 may be switched by an analog switch and connected to a single capacitance detection circuit.

[0118] Seventh Embodiment

[0119] FIG. 13 is a schematic partial cross-sectional view of a pressure sensor sheet 100E according to a seventh embodiment. In the pressure sensor sheet 100D of the sixth embodiment, the first support portion 11 of each of the multiple sensor units 7 is formed from a single, common polyimide sheet, and the first plate-shaped portions 12 are connected to one another. In contrast, as in the pressure sensor sheet 100E of FIG. 13, the first plate-shaped portions 12 of the sensor units 7 may not be connected to one another but may be separated from one another. In the pressure sensor sheet 100E, each sensor unit 7 includes a first component portion 1E including a first plate-shaped portion 12 composed of a first electrode 15 and a first support portion 11, a second component portion 2E including a second plate-shaped portion 22 composed of a second electrode 25 and a second support portion 21, and a third component portion 3E located between the first component portion 1E and the second component portion 2E. The third component portion 3E has a wall portion 117. Each of the components 1E, 2E, and 3E forms a sealed hollow portion 4. A wall portion 117 surrounds the hollow portion 4. The second support portion 21 of the second component 2E of each sensor unit 7 is made of the same single polyimide sheet, but the first component 1E and the third component 3E of each sensor unit 7 do not share any parts and are provided for each sensor unit 7.

[0120] In the pressure sensor sheet 100E, a soft insulating material is used for the insulating layer portion constituting the first support portion 11 so that the first plate-shaped portion 12 is flexible. The second constituent portion 2E is preferably flexible, which makes it easy to place the pressure sensor sheet 100E on the detection object 6 having a curved surface 60 along the surface 60 without any gaps. For example, the second constituent portion 2E may be configured as a second electrode sheet in which a plurality of second electrodes 25 are arranged on a flexible polyimide sheet.

[0121] In the pressure sensor sheet 100E of this embodiment, when placed on a detection object having a curved surface, the first plate-shaped portion 12 of each sensor unit 7 is not interfered with by the deformation caused by the first plate-shaped portion 12 of the adjacent sensor unit 7 conforming to the shape of the curved surface of the detection object, thereby improving detection accuracy and pressure distribution accuracy.

[0122] Furthermore, when obtaining pressure distribution using a pressure sensor sheet having multiple sensor portions, the pressure sensor sheet can be placed on the surface of the object to be detected, and the capacitance of each pressure sensor can be detected in the initial state (when no fluid pressure is applied), and the change in capacitance due to receiving fluid can be detected based on this capacitance.

[0123] Eighth Embodiment

[0124] FIG. 14(A) is a plan view of a pressure sensor sheet 100F according to an eighth embodiment, and is a schematic plan view showing an example of the arrangement of the first electrodes 15 and the second electrodes 25. The pressure sensor sheet 100F has multiple sensor units 7. When the detection object is a specimen simulating an aircraft wing, the front side of the aircraft wing (the side facing the aircraft's direction of travel) experiences more drastic pressure changes than the rear side, and detailed pressure distribution information is therefore required. In such a case, as shown in FIG. 14(A), the pressure sensor sheet 100F may be configured such that the sensor units 7 located on the front side of the wing are densely arranged, and the sensor units 7 located on the rear side are sparsely arranged. In this way, the arrangement of the sensor units 7 may be adjusted depending on the detection object.

[0125] Ninth Embodiment

[0126] 14(B) is a plan view of a pressure sensor sheet 100G according to the ninth embodiment, and is a schematic plan view showing an example of the arrangement of the first electrodes 15 and the second electrodes 25. In the sixth and eighth embodiments, examples were given in which a plurality of sensor units 7 were arranged in a matrix, but they may also be arranged in a staggered pattern as in the pressure sensor sheet 100G. Alternatively, they may be arranged in any arbitrary arrangement.

[0127] Tenth Embodiment

[0128] Fig. 15 is a schematic exploded perspective view of a pressure sensor sheet 100H according to a tenth embodiment. In the sixth, eighth, and ninth embodiments described above, examples have been given in which the first electrodes 15 and the second electrodes 25 of each sensor unit 7 are individually provided so as to be electrically independent from each other, but the present invention is not limited to such a configuration. For example, as in the pressure sensor sheet 100H of this embodiment shown in Fig. 15, a configuration may be adopted in which strip-shaped first electrodes 15H and strip-shaped second electrodes 25H are arranged to intersect in a plan view, and the intersecting points function as sensor units 7.

[0129] The pressure sensor sheet 100H is flexible. As shown in Fig. 15, the pressure sensor sheet 100H is composed of a first electrode sheet 1H, a second electrode sheet 2H, and a spacer sheet 3H disposed between the first electrode sheet 1H and the second electrode sheet 2H, which are stacked together. Adjacent sheets are bonded together with an adhesive or the like.

[0130] The first electrode sheet 1H as the first component includes a first sheet 10 made of polyimide, a plurality of (three in this example) strip-shaped first electrodes 15H provided on the lower surface of the first sheet 10, and a plurality of first lead-out wirings 16H electrically connected to the first electrodes 15H, respectively. Each of the first electrodes 15H is electrically connected to the capacitance detection unit 5 via the first lead-out wirings 16H.

[0131] The second electrode sheet 2H as the second component includes a second sheet 20 made of polyimide, a plurality of (three in this example) second electrodes 25H provided on the upper surface of the second sheet 20, and a plurality of second lead-out wirings 26H electrically connected to the second electrodes 25H, respectively. Although not shown in the figure, each second electrode 25H is electrically connected to a corresponding capacitance detection unit 5 via the second lead-out wirings 26H.

[0132] The spacer sheet 3H as the third component is configured by providing a third sheet 30 made of polyimide with a plurality of (here, nine) openings 34 each consisting of a rectangular through-hole. The first electrode sheet 1H, the second electrode sheet 2H, and the spacer sheet 3H form a sealed hollow. An opening edge 341 of the opening 34 functions as a wall surrounding the hollow. In plan view, the intersection of the first electrode 15H and the second electrode 25H is located within the area surrounded by the opening edge 341. In other words, the intersection of the first electrode 15H and the second electrode 25H is arranged so as to be spaced apart in the thickness direction within the hollow.

[0133] In the pressure sensor sheet 10H having such an electrode configuration, the fluid pressure distribution acting on the surface of the detection object can be obtained, similarly to the sixth embodiment.

[0134] Eleventh Embodiment

[0135] FIG. 16 is a schematic exploded perspective view of a pressure sensor sheet 100J according to an eleventh embodiment. In the sixth, eighth, and ninth embodiments described above, examples were given in which the first electrodes 15 and the second electrodes 25 of each sensor unit 7 were individually provided so as to be electrically independent from each other. However, the present invention is not limited to such a configuration. For example, as in the pressure sensor sheet 100J of this embodiment shown in FIG. 16, the first electrodes 15J serving as detection electrodes provided on the first electrode sheet 1J may be individually provided for each sensor unit 7, and the second electrodes 25J serving as reference electrodes provided on the second electrode sheet 2J may be a common electrode shared by all the sensor units 7. The area where the first electrodes 15J and the second electrodes 25J overlap in a plan view may function as the sensor unit 7.

[0136] The pressure sensor sheet 100J is flexible. As shown in Fig. 16, the pressure sensor sheet 100J includes a first electrode sheet 1J, a second electrode sheet 2J, and a spacer sheet 3J disposed between the first electrode sheet 1J and the second electrode sheet 2J, which are stacked together.

[0137] The first electrode sheet 1J as the first component includes a first sheet 10 made of polyimide, a plurality of first electrodes 15J provided on the lower surface of the first sheet 10, and a plurality of first lead-out wires 16J electrically connected to the first electrodes 15J, respectively. Each of the first electrodes 15J is electrically connected to the capacitance detection unit 5 via the first lead-out wires 16J.

[0138] The second electrode sheet 2J has a second sheet 20 made of polyimide, a second electrode 25J provided on the upper surface of the second sheet 20, and a second lead-out wiring 26J electrically connected to the second electrode 25J. The second electrode 25J is electrically connected to each capacitance detection unit 5 via the second lead-out wiring 26J. The second electrode 25J is a common electrode that faces each of the multiple first electrodes 15J.

[0139] The spacer sheet 3J, which serves as the third component, has a third sheet 30 made of polyimide and a plurality of (here, nine) openings 34 each consisting of a rectangular through-hole. The first electrode sheet 1J, the second electrode sheet 2J, and the spacer sheet 3J form a sealed hollow. An opening edge 341 of the opening 34 functions as a wall surrounding the hollow. In plan view, the overlapping portions of the first electrode 15J and the second electrode 25J are located within the area surrounded by the opening edge 341. In other words, the overlapping portions of the first electrode 15J and the second electrode 25J in plan view are spaced apart in the thickness direction within the hollow.

[0140] In the pressure sensor sheet 10H having such an electrode configuration, the fluid pressure distribution acting on the surface of the detection object can be obtained, similarly to the sixth embodiment.

[0141] Although various embodiments of the present invention have been described above, these embodiments are merely examples, and the present invention is not limited to the specific embodiments disclosed herein. Furthermore, it goes without saying that the scope of the present invention is not limited to these embodiments.

[0142] <Example>

[0143] [Creating a pressure sensor sheet]

[0144] A pressure sensor sheet with a shape similar to that of the first embodiment described above was created. Pressure sensor sheets of Examples 1 to 8 were created by varying the thickness of the first sheet, the thickness of the spacer sheet, the size of the electrodes in plan view, and the size of the hollow portion in plan view. The pressure sensor sheets had a Y-axis dimension of 40 mm and an X-axis dimension of 150 mm. In each pressure sensor sheet, a polyimide sheet (Kapton (registered trademark) manufactured by DuPont-Toray Co., Ltd.) was used for the first sheet, second sheet, and spacer sheet. The thickness of the spacer sheet was adjusted by using a single (single) or multiple existing polyimide sheets stacked together. The first electrode, second electrode, each lead wire, and each pad electrode were formed by printing using copper and had a thickness of 1 to 6 μm. The first electrode sheet was created by forming the first electrode, first lead wire, and first pad electrode on the first sheet, and the second electrode and second lead wire were formed on the second sheet to create the second electrode sheet. A spacer sheet was also created by forming an opening penetrating the thickness direction in the third sheet. The first electrode sheet, spacer sheet, and second electrode sheet were stacked and bonded together with adhesive to create a pressure sensor sheet. The sensor specifications, such as the dimensions of each component of each pressure sensor sheet, are as follows:

[0145] Example 1

[0146] -Thickness of the first sheet: 50μm Second sheet thickness: 50 μm Spacer sheet thickness: 450 μm. Nine 50 μm thick polyimide sheets were stacked, and through-holes were drilled in the stacking direction (thickness direction) to form openings in the laminate (third sheet), to form the spacer sheet. Thickness of the first plate-shaped portion (sum of the thickness of the first sheet and the thickness of the first electrode): 51 μm The first and second electrodes are rectangular with plane dimensions of 10mm x 10mm. - Planar dimensions of the opening: 12.5mm x 12.5mm rectangular · Overall thickness of pressure sensor sheet: 550μm

[0147] Example 2

[0148] -Thickness of the first sheet: 50μm Second sheet thickness: 50 μm Spacer sheet thickness: 100 μm Thickness of the first plate-shaped portion (sum of the thickness of the first sheet and the thickness of the first electrode): 56 μm The first and second electrodes are rectangular with plane dimensions of 10mm x 10mm. - Planar dimensions of the opening: 15mm x 15mm rectangular · Overall thickness of pressure sensor sheet: 200μm

[0149] Example 3

[0150] - Thickness of the first sheet: 125 μm - Second sheet thickness: 125μm Spacer sheet thickness: 100 μm Thickness of the first plate-shaped portion (sum of the thickness of the first sheet and the thickness of the first electrode) 131 μm The first and second electrodes are rectangular with plane dimensions of 10mm x 10mm. - Planar dimensions of the opening: 15mm x 15mm rectangular · Overall thickness of pressure sensor sheet: 350μm

[0151] Example 4

[0152] -Thickness of the first sheet: 50μm Second sheet thickness: 50 μm Spacer sheet thickness: 500 μm Thickness of the first plate-shaped portion (sum of the thickness of the first sheet and the thickness of the first electrode): 56 μm The first and second electrodes are rectangular with plane dimensions of 10mm x 10mm. - Planar dimensions of the opening: 15mm x 15mm rectangular · Overall thickness of pressure sensor sheet: 600μm

[0153] Example 5

[0154] - Thickness of the first sheet: 125 μm - Second sheet thickness: 125μm Spacer sheet thickness: 300 μm Thickness of the first plate-shaped portion (sum of the thickness of the first sheet and the thickness of the first electrode) 131 μm The first and second electrodes are rectangular with plane dimensions of 10mm x 10mm. -Opening plane dimensions: 15mm x 15mm rectangular · Overall thickness of pressure sensor sheet: 550μm

[0155] Example 6

[0156] - Thickness of the first sheet: 125 μm - Second sheet thickness: 125μm Spacer sheet thickness: 500 μm Thickness of the first plate-shaped portion (sum of the thickness of the first sheet and the thickness of the first electrode) 131 μm The first and second electrodes are rectangular with plane dimensions of 10mm x 10mm. - Planar dimensions of the opening: 15mm x 15mm rectangular · Overall thickness of pressure sensor sheet: 750μm

[0157] Example 7

[0158] -Thickness of the first sheet: 50μm Second sheet thickness: 50 μm Spacer sheet thickness: 300 μm Thickness of the first plate-shaped portion (sum of the thickness of the first sheet and the thickness of the first electrode): 56 μm The first and second electrodes are rectangular with plane dimensions of 5mm x 5mm. - Planar dimensions of the opening: 15mm x 15mm rectangular · Overall thickness of pressure sensor sheet: 400μm

[0159] Example 8

[0160] -Thickness of the first sheet: 50μm Second sheet thickness: 50 μm Spacer sheet thickness: 500 μm Thickness of the first plate-shaped portion (sum of the thickness of the first sheet and the thickness of the first electrode): 56 μm The first and second electrodes are rectangular with plane dimensions of 5mm x 5mm. - Planar dimensions of the opening: 15mm x 15mm rectangular · Overall thickness of pressure sensor sheet: 600μm

[0161] [Overall rating]

[0162] The pressure sensor sheets of Examples 1 to 8 were all flexible and ultra-thin sheets. These pressure sensor sheets could be placed on curved or flat detection target surfaces so as to fit the shape of the detection target surface, and it was confirmed that they could perform stable and accurate detection.

[0163] [Evaluation of capacitance change]

[0164] The pressure sensor sheet of Example 1 was placed in a pressure vessel, and positive and negative pressures were applied to measure the change in capacitance. The results are shown in Figure 17. In Figure 17, the dashed line indicates the pressure inside the pressure vessel, and the solid line indicates the detected capacitance. As shown in Figure 17, the capacitance changed favorably in response to pressure when both positive and negative pressures were applied, confirming that the pressure sensor sheet was favorable in both responsiveness (responsiveness to deformation of the pressure-receiving surface in response to pressure) and zero-point return (response to rapid recovery after pressure is released).

[0165] [Evaluation method]

[0166] In the evaluation of the pressure sensor sheets described below, as shown in Figure 5, a pressure sensor sheet to be evaluated was placed on a specimen 6, which resembled an aircraft wing as the detection target, and secured with tape (not shown). A wind tunnel experiment was then conducted to evaluate the pressure sensor sheet. The specimen 6 had a height (dimension in the Y-axis direction, i.e., the longitudinal direction of the wing) of 1000 mm, a length from the leading edge to the trailing edge (dimension in the X-axis direction) of 400 mm, and a wing thickness (maximum dimension in the Z-axis direction) of 48 mm. The pressure sensor sheet to be evaluated was placed on the surface 60 so that the center of the sensor unit 7 (the center of the rectangular pressure-receiving surface in a plan view) was located 40 mm in the X-axis direction from the forward end of the specimen 6. The portion of the surface 60 corresponding to the sensor unit 7 constituted the detection target surface 60a. An artificial air flow was then generated to flow around the specimen 6, simulating an actual flow field. The capacitance of the detection target surface 60a receiving fluid in the simulated flow field was measured (wind tunnel experiment). The fluid pressure received by the detection target surface 60a was changed by changing the flow velocity of the air and the amount of fluid per unit time. The fluid pressure actually received by the detection target surface 60a was measured by connecting a pipe to a pressure hole with a diameter of 0.5 mm machined on the surface of the test piece 6, and then connecting the pipe to a commercially available multi-point pressure sensor (ZOC33 manufactured by Scani-Valve, USA). Note that the evaluation using the results of numerical analysis was performed in the section "Evaluation of sensor specifications taking into account the radius of curvature of the detection target surface" described below.

[0167] In the following wind tunnel experiments to evaluate the pressure sensor sheet, the test specimen 6 was placed on a horizontal plane with the longitudinal direction of the wing perpendicular to the horizontal plane, as shown in Figure 5. Typically, in wind tunnel experiments to detect fluid pressure acting on the surface of the test specimen, the wing is positioned so that its longitudinal direction is approximately parallel to the horizontal plane, which is the same as the attitude of an aircraft when flying.

[0168] [Evaluation of the thickness of the first sheet]

[0169] The pressure sensor sheets of Example 2 and Example 3, which differ in the thickness of the first sheet constituting the pressure-receiving surface, were prepared as evaluation targets, and the above-mentioned wind tunnel experiment was conducted to evaluate the thickness of the first sheet. Figures 18 and 19 show plots of the change in capacitance detected by the pressure sensor sheets under evaluation. In Figures 18 and 19, the horizontal axis indicates the actual pressure value received by the detection target surface. Figure 18 relates to the pressure sensor sheet of Example 2, in which the first sheet is 50 μm thick, and Figure 19 relates to the pressure sensor sheet of Example 3, in which the first sheet is 125 μm thick. In Figures 18 and 19, an approximation curve was created for the plotted data, showing the 95% prediction interval (the interval in which 95% of the next observed data is expected to fall). As shown in Figures 18 and 19, it was confirmed that the capacitance changed favorably in response to pressure in both the pressure sensor sheets of Example 2 and Example 3.

[0170] 18 and 19, the pressure sensor sheet of Example 2, in which the thickness of the first sheet is smaller, has a smaller prediction interval and less variation from the approximation line than the pressure sensor sheet of Example 3. Also, R 2 The values ​​were 0.990 in Example 2 and 0.968 in Example 3. These results confirmed that the thinner the first sheet constituting the pressure-receiving surface, in other words, the thinner the first plate-shaped portion, the better the restoration response. Note that in Examples 1 to 8, the thinnest first sheet was 50 μm thick, but even for sheets thinner than this, it is believed that the thinner the first sheet, the better the restoration response. Furthermore, from the viewpoint of good restoration response, it is preferable that the thickness of the first sheet be 125 μm or less.

[0171] [Evaluation of spacer sheet thickness]

[0172] Seven types of pressure sensor sheets from Examples 2 to 8, which differ in the planar dimensions of the first and second electrodes, the thickness of the first sheet, and the thickness of the third sheet (spacer sheet), were prepared as evaluation targets, and the above-mentioned wind tunnel experiment was carried out. For each pressure sensor sheet from Examples 2 to 8 placed on the surface 60 of the detection target 6, the change in capacitance detected by the pressure sensor sheet was plotted, and an approximation curve was created for the plotted data (capacitance). Then, the coefficient of determination R, which represents the degree of fit to the approximation curve, was calculated. 2 The results are shown in Figure 20. Figure 20 shows the relationship between the R 2 The values ​​are shown. For each pressure sensor sheet in Examples 2 to 8, the change in capacitance detected by the pressure sensor sheet was detected, and the sensitivity coefficient (the magnitude of the change in capacitance relative to a certain change in pressure) was calculated. The results are shown in Figure 21. Figure 21 shows the sensitivity coefficient relative to the thickness of the third sheet (spacer sheet).

[0173] As shown in Figure 20, it was confirmed that the thinner the third sheet (spacer sheet), in other words, the smaller the volume of the hollow portion, the higher the data accuracy tends to be. Also, as shown in Figure 21, it was confirmed that the thinner the third sheet (spacer sheet), in other words, the smaller the volume of the hollow portion, the higher the sensitivity coefficient and the better the restoration response.

[0174] [Evaluation of sensor specifications taking into account the curvature radius of the detection target surface]

[0175] Figure 22 shows the relationship between capacitance and pressure, based on the results of numerical analysis for a pressure sensor sheet with a thickness of 50 μm for the first sheet, 50 μm for the second sheet, 170 μm for the spacer sheet, 10 mm × 10 mm for the rectangular first and second electrodes, 12.5 mm × 12.5 mm for the opening, and 270 μm for the overall thickness (hereinafter referred to as "first specification" for convenience). Figure 23 shows the relationship between capacitance and pressure, based on the results of numerical analysis for a pressure sensor sheet with a thickness of 50 μm for the first sheet, 50 μm for the second sheet, 170 μm for the spacer sheet, 5 mm × 5 mm for the rectangular first and second electrodes, 7.5 mm × 7.5 mm for the opening, and 270 μm for the overall thickness (hereinafter referred to as "second specification" for convenience). 22 and 23, the horizontal axis indicates the pressure value actually applied to the detection target surface. The second specification has smaller electrode sizes (planar dimensions) of the first and second electrodes and planar dimensions of the opening than the first specification. Note that the electrode film thickness is not defined in the numerical analysis.

[0176] As a premise, the sensor cannot be used as a pressure sensor under conditions where the first and second electrodes come into contact, so the usable radius of curvature of the detection target surface is limited. For example, in the case of a first specification pressure sensor, when a pressure of 111.325 kPa or more is applied, analytically, the first and second electrodes come into contact when the radius of curvature of the detection target surface is 50 mm, but do not come into contact when the radius of curvature is 75 mm. Therefore, from the perspective of preventing the first and second electrodes from coming into contact and causing a short circuit, the limit value of the detectable radius of curvature of the detection target surface is considered to be in the range of 50 mm to 75 mm. Note that if the applied pressure value is slightly smaller, the occurrence of a short circuit between the electrodes can be prevented even if the radius of curvature of the detection target surface is set to 50 mm.

[0177] On the other hand, as shown in Figures 22 and 23, when the radius of curvature of the detection target surface is less than 200 mm, the capacitance changes significantly with the change in radius of curvature, confirming that the capacitance characteristics of the sensor unit change significantly with respect to pressure. Therefore, when the radius of curvature of the detection target surface is less than 200 mm, different capacitances are obtained under the same pressure under conditions where the characteristics change rapidly, making it difficult to use as a pressure sensor. While it is possible to obtain characteristic data (calibration data) for each radius of curvature in the range where the capacitance value increases (in the first specification, the range where the detection target surface has a radius of curvature of less than 200 mm), this is not practical because the number of conditions for obtaining this calibration data would be enormous. Therefore, for example, when using the first specification, it is practically preferable to use a pressure sensor for a detection target surface with a radius of curvature of 200 mm or more.

[0178] Furthermore, analytical results confirmed that by reducing the planar dimensions of the opening and the first and second electrodes, capacitance can be detected even on detection target surfaces with even smaller radii of curvature. Therefore, for fluid pressure detection on detection target surfaces with a curvature radius of less than 200 mm, reducing the planar dimensions of the opening and the first and second electrodes makes it practical to use the sensor. As shown in Figures 22 and 23, comparing the analysis results for the first and second specifications, we confirmed that changing the sensor specifications (the size of the opening, first and second electrodes) alters the capacitance detection curve. With the second specification, it is estimated that capacitance can be detected without contact between the first and second electrodes for detection target surfaces with a curvature radius of up to 30 mm. Therefore, it can be said that detection is possible on detection target surfaces with a smaller curvature radius by reducing the planar dimensions of the opening and the first and second electrodes.

[0179] From the above, it was confirmed that a realistic pressure sensor sheet (pressure sensor structure) can be created by setting the sensor specifications according to the radius of curvature of the surface of the detection target. In other words, one pressure sensor sheet can detect the fluid pressure applied to detection target surfaces with different radii of curvature.

[0180] 22 also shows that, in the first specification, when the radius of curvature of the detection target surface changes, the capacitance of the sensor unit and the response of the capacitance to pressure changes (pressure sensitivity) change. As described above, it is difficult to use the sensor in practical use under conditions where the sensitivity characteristics change significantly depending on the radius of curvature. Therefore, it is more realistic to use the sensor under conditions where changes in the sensitivity characteristics are tolerable. Under conditions where such changes in the sensitivity characteristics are tolerable (for example, in the first specification, detection of a detection target surface with a radius of curvature of 200 mm or more is assumed), a capacitance characteristic curve (calibration curve) can be obtained in advance, similar to the calibration curve of a general sensor. A calibration coefficient can be determined using the calibration curve, and the detected capacitance value can be converted to a pressure value using the calibration coefficient information, as described above.

[0181] Furthermore, short circuits caused by contact between the opposing first and second electrodes when the pressure sensor sheet is bent can be prevented by increasing the thickness of the third sheet (spacer sheet) or limiting the flexibility of the first sheet. Furthermore, contact between the electrodes can be prevented by limiting the amount of displacement of the first plate-shaped portion, in which case reducing the opening size can be considered as a countermeasure. Furthermore, from the perspective of preventing short circuits between electrodes, an insulating film such as an oxide film may be provided on the first and second electrodes to prevent short circuits. [Explanation of symbols]

[0182] 1, 1B, 1D, 1H, 1J...First electrode sheet 2, 2B, 2D, 2H, 2J...Second electrode sheet 3, 3B, 3D, 3H, 3J...Spacer sheet 4...Hollow part 6, 116...Test specimen, detection object 7...Sensor section 8...Signal processing section 11...First support part 12...First plate-shaped portion 15, 15H, 15J…1st electrode 18...Pressure surface 21...Second support part 22...Second plate-shaped portion 25, 25H, 25J…2nd electrode 34…Aperture 341...Opening edge (wall) 60...Surface of object to be detected 60a, 116a...detection target surface 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H, 100J...Pressure sensor sheet (pressure sensor structure) 110...Pressure sensor structure 116a...detection target surface 117...Wall part

Claims

1. A pressure sensor structure for detecting a pressure of a fluid received by a detection target surface of a detection target, a flexible first plate-shaped portion including a first support portion having a pressure-receiving surface that receives the pressure of the fluid and a first electrode provided on the first support portion; a second electrode disposed opposite to and spaced apart from the first electrode; a wall portion provided to surround a hollow portion such that a sealed hollow portion is formed between the first electrode and the second electrode; and Equipped with the first plate-shaped portion is deformed when the fluid is received on the pressure-receiving surface, and a change in capacitance of a sensor portion formed by a variable capacitance capacitor formed by the first electrode and the second electrode arranged opposite each other via the hollow portion is utilized to detect the pressure of the fluid received by the detection target surface; The pressure of both the fluid having a higher pressure than the reference pressure, which is the pressure inside the hollow portion, and the fluid having a lower pressure than the reference pressure, is detected. Pressure sensor structure.

2. 2. The pressure sensor structure according to claim 1, a sheet-like first electrode sheet having the first plate-like portion; a sheet-like second electrode sheet having a second plate-like portion having a second support portion arranged in contact with the detection target surface and the second electrode provided on the second support portion; and a sheet-like spacer sheet arranged between the first electrode sheet and the second electrode sheet, the spacer sheet having an opening with an opening edge portion that constitutes the wall portion, stacked in the order of the second electrode sheet, the spacer sheet, and the first electrode sheet; The hollow portion is a region surrounded by the first electrode sheet, the second electrode sheet, and the opening edge portion. Pressure sensor structure.

3. 2. The pressure sensor structure according to claim 1, a second plate-shaped portion including a second support portion disposed in contact with the detection target surface and the second electrode provided on the second support portion; The first plate-shaped portion, the second plate-shaped portion, and the wall portion are formed integrally based on additive manufacturing and are flexible sheets. Pressure sensor structure.

4. 2. The pressure sensor structure according to claim 1, the second electrode is provided on the detection target surface, The detection object, the first plate-shaped portion, the second electrode, and the wall portion are integrally formed by additive manufacturing, and are integrated with the detection object. Pressure sensor structure.

5. 3. The pressure sensor structure according to claim 1, The dimension of the first plate-shaped portion in the thickness direction of the pressure sensor structure is 2 μm or more and 131 μm or less, and the dimension of the wall portion in the thickness direction is more than 0 μm and 300 μm or less. Pressure sensor structure.

6. 3. The pressure sensor structure according to claim 1, The sensor unit includes a plurality of sensors. Pressure sensor structure.

7. 3. The pressure sensor structure according to claim 1, a signal processing unit that converts the capacitance value detected by the sensor unit into a pressure value using calibration coefficient information that is set in advance for each radius of curvature of the detection target surface based on the curvature radius information of the detection target surface. The pressure sensor structure further comprises:

8. 3. The pressure sensor structure according to claim 1, The detection object is a replica of an aircraft wing. Pressure sensor structure.

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