Sheet-shaped sensing member and its manufacturing method

Abstract

To provide a sheet-type sensing component that offers excellent wear resistance and texture, and allows for easy replacement of parts in the event of a malfunction. [Solution] A sheet-like sensing member characterized in that a linear sensing member is fixed inside a sheet-like cushion material of a predetermined thickness having voids inside, preferably the sheet-like cushion material of a predetermined thickness having voids inside is a three-dimensional knitted fabric of a predetermined thickness composed of a front knit fabric, a back knit fabric and a plurality of connecting yarns connecting them, and the linear sensing member is inserted in any direction between the plurality of connecting yarns and is gripped by contact with the connecting yarns.

Description

[Technical Field]

[0001] The present invention relates to a sheet-like sensing member characterized in that a linear sensing member is fixed inside a sheet-like cushion material of a predetermined thickness having voids inside, in the thickness direction thereof. [Background technology]

[0002] Conventionally, smart textile technologies have been proposed that involve mounting electrical functional elements on flexible and stretchable fiber substrates. These technologies involve mounting functional elements such as sensors, batteries, heaters, and Peltier elements on a flexible fiber substrate, enabling the creation of extremely thin and flexible products, which will be crucial in the coming IoT (Internet of Things) society.

[0003] As pressure sensors using flexible fibers as a base material, techniques for fabricating sensors by weaving or knitting conductive fibers into fabric are known. The main pressure detection methods known are resistive and capacitive types. In the resistive type, the resistance value changes in response to an external force. For example, a knitted fabric is made using conductive fibers, and the change in the overall resistance value when the knitted fabric is stretched or contracted is read to detect the application of tensile force. In the capacitive type, for example, electrodes are formed by sewing conductive fibers to the front and back of a fabric, making them electrically independent to create a capacitance. The detection principle uses the fact that when an external force is applied, the thickness of the fabric changes, and therefore the capacitance changes.

[0004] The following Patent Documents 1 to 4 disclose the construction of automobile seats and the like by combining sensors and three-dimensional woven fabrics. However, in all of these, the sensors are placed only on the outside of the three-dimensional knitted fabric, such as by placing the sensors between the three-dimensional knitted fabric and the cushioning material, or by attaching sensors to both the front and back surfaces of the three-dimensional knitted fabric.

[0005] On the other hand, Patent Document 5 discloses a sensing fiber member having a covering yarn in which a linear conductor as a core material is covered by winding high-resistance fibers as a covering material in one direction. As mentioned above, Patent Document 5 discloses that woven or knitted fabrics made using such a fiber member as a woven or knitted yarn also have sensing properties, but in this case as well, the sensing fiber member is exposed to the outside. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2005-349904 [Patent Document 2] Patent No. 2011-152242 [Patent Document 3] Japanese Patent Publication No. 2012-073150 [Patent Document 4] Japanese Patent Publication No. 2006-014756 [Patent Document 5] International Publication No. 2022 / 138862 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] As mentioned above, in conventional resistive and capacitive sensing elements, the part constituting the sensor is positioned so that it is exposed to the outside of the fabric. This leads to problems such as poor abrasion resistance and texture when external force is applied, and the fact that the fabric fibers form part of the sensor structure, making it difficult to easily replace the sensor if it malfunctions. If a linear sensing element (hereinafter also referred to as a fiber sensor, sensing fiber element, sensing thread, or sensor thread) can be fixed inside a sheet-like cushion material of a predetermined thickness that has internal voids, detection can be performed without the object or living organism to be detected directly touching the linear sensing element, and the implementation of the linear sensing element becomes easier. Therefore, in view of the aforementioned state of technology, the problem that the present invention aims to solve is to provide a sheet-like sensing member that has excellent wear resistance and texture, and that is easy to replace in the event of a malfunction. [Means for solving the problem]

[0008] In order to solve the aforementioned problems, the inventors diligently conducted studies and repeated experiments, and as a result, unexpectedly discovered that the aforementioned problems could be solved by the following configuration, thus completing the present invention.

[0009] In other words, the present invention is as follows: [1] A sheet-like sensing member characterized in that a linear sensing member is fixed inside a sheet-like cushion material of a predetermined thickness having voids inside in the thickness direction. [2] The sheet-like sensing member according to [1], wherein the sheet-like cushioning material having a void inside is a three-dimensional knitted fabric of a predetermined thickness composed of a front knit fabric, a back knit fabric and a plurality of connecting yarns connecting them, and the linear sensing member is inserted in any direction between the plurality of connecting yarns and is gripped by contact with the connecting yarns. [3] The sheet-like sensing member according to [2], wherein, when unloaded, all or part of the connecting thread is curved, and when loaded, the thickness of the sheet-like sensing member decreases and the degree of such curvature increases. [4] The following formula: Cross-sectional area of ​​connected yarn per unit area = (N × D) / (1 × 10) 6 ×ρ) {In the formula, N is the finished product of the three-dimensional diameter knitted fabric, 1 cm} 2 Number of connected threads per unit (threads / cm) 2 ) and D is the fineness of the connecting yarn (dtex: 1×10 6 The mass per cm (g) is given by ρ, and ρ is the specific gravity (g / cm³) of the connecting thread material. 3 The cross-sectional area of ​​the connecting yarn per unit area of ​​the three-dimensional warp knitted fabric, calculated using}, is 0.01 cm². 2 More than 0.10cm 2The sheet-like sensing member according to [2] or [3] below. [5] The sheet-like sensing member according to [2] or [3], wherein the material of the connecting thread is polytrimethylene terephthalate (PTT). [6] The sheet-like sensing member according to [2] or [3], wherein the fineness of the connecting thread is 50 dtex or more and 500 dtex or less. [7] The sheet-like sensing member according to [6], wherein the fineness of the connecting thread is 200 dtex or more and 300 dtex or less. [8] The sheet-like sensing member according to any one of [1] to [3], wherein the thickness of the sheet-like sensing member is 2 mm or more and 20 mm or less. [9] The linear sensing member has at least two covering yarns obtained by winding a high-resistance fiber as a covering material around a linear conductor as a core material in one direction for covering, and two of them are arranged close to each other. The change in resistance between the linear conductors of the two covering yarns arranged close to each other is read. Here, the value of the resistance (sensor resistance) between the linear conductors of the covering yarns arranged close to each other is within the range of 0.5 kΩ to 5 GΩ per 10 cm of the length of the linear conductor, and the sensor resistance value is 20 times to 1 × 10 9 times that of the resistance (wiring resistance) per 10 cm of the length of only the linear conductor. The sheet-like sensing member according to any one of [1] to [3].

[10] The sheet-like sensing member according to [9], wherein the high-resistance fiber of the linear sensing member includes either a multifilament high-resistance fiber or a spun yarn made of high-resistance fiber.

[11] The sheet-like sensing member according to [9], wherein the linear sensing member senses the contact or load of an object on the sheet-like sensing member.

[12] The sheet-like sensing member according to [9], wherein the linear sensing member senses the expansion / contraction or bending deformation of the sheet-like sensing member.

[13] The sheet-shaped sensing member according to [9] above, wherein the linear sensing member senses contact with a liquid or a change in humidity.

[14] The following formula for the covering yarn of the linear sensing member: Twist coefficient K = (SS + SC) 1 / 2 ×R {In the formula, SS is the fineness (dtex) of the linear conductor as the core material, SC is the total fineness (dtex) of the coating material, and R is the number of windings (twist number) (turns / m) of the coating material.} The sheet-shaped sensing member according to [9] above, wherein the twist coefficient K represented by is 7,000 or more and 50,000 or less.

[15] The sheet-shaped sensing member according to [9] above, wherein the covering yarn of the linear sensing member is a double covering yarn in which the periphery of the linear conductor as the core material is covered with two coating materials, and the winding directions of the two coating materials are the same.

[16] The sheet-shaped sensing member according to [9] above, wherein two covering yarns of the linear sensing member arranged close to each other have a crossing contact point.

[17] The sheet-shaped sensing member according to [9] above, wherein the linear conductor as the core material of the linear sensing member is a multifilament conductive fiber having 10 to 200 filaments.

[18] The sheet-shaped sensing member according to [9] above, wherein the winding directions of the multifilament high-resistance fibers in two covering yarns arranged close to each other are the same, and the two covering yarns are twisted yarns twisted in a direction opposite to the winding direction of the multifilament high-resistance fibers. [Effect of the Invention]

[0010] The sheet-shaped sensing member according to the present invention preferably provides a technique for easily mounting a sensor by passing a linear sensing member, for example, a fibrous sensor, through a gap between connecting yarns inside a three-dimensional knitted fabric, and has excellent abrasion resistance and texture, and can realize a sensing member that can be easily replaced in case of failure. When a fiber sensor is sandwiched between two types of materials, if the upper material is flexible, it will absorb part of the load, making it difficult to sense the load sensitively. However, as in the present invention, when a fiber sensor is inserted between the connecting threads of a three-dimensional knitted fabric, there is no such absorption of load, and therefore the load can be sensed sensitively. Furthermore, when sandwiched between materials, the sensor position tends to shift when loading and unloading is repeated, requiring some form of fixing. However, when a fiber sensor is inserted between the connecting threads of a three-dimensional knitted fabric, the fiber sensor is held in place by contact with numerous connecting threads, so a special fixing method is not required, the fiber sensor can be fixed in a replaceable state, and it also has a superior texture. Furthermore, when using a linear sensing member as a fiber sensor inserted between connecting yarns in a three-dimensional knitted fabric, which has at least two covering yarns in which a high-resistance fiber as a covering material is wound in one direction around a linear conductor as a core material, and two of these covering yarns are arranged in close proximity to each other, such a linear sensing member can be processed in long lengths, is highly productive in mass production, is flexible and has a superior texture, and is significantly less expensive than conventional contact sensing fiber members (piezoelectric threads) using piezoelectric materials. In other words, such a linear sensing member can sense load and moisture using common fiber materials such as polyester, nylon, synthetic fibers, or natural or regenerated cellulose fibers, resulting in very low costs. Moreover, because it uses covering technology, a fiber processing technology for which know-how has been established, it can be processed in long lengths, is highly productive in mass production, and a processed yarn with a much better texture than piezoelectric thread can be realized, making it easy to process into a sheet-like sensing member. Therefore, the sheet-like sensing member according to the present invention can be widely used in various applications, such as smart textile applications where an electrical functional element is provided on a flexible and stretchable fiber base material, for example, rugs that can be detected when stepped on, security mats for detecting people entering and leaving, mats for counting people, etc., contact sensing woven or knitted fabrics, for example, monitoring sensors in nursing and care settings, sensors that digitize and transmit tactile sensations in production sites such as factories, seat members for various vehicles, members for embedding sensors in vehicle seat belts, etc., for example, embedding contact sensors (biosensors) in vehicle seat belts, steering wheels, dashboards, etc., sensors for detecting the presence or absence of people, sensors for preventing children from being left unattended in the back seat, and monitoring sensors. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view of a three-dimensional knitted fabric illustrating a state in which a linear sensing member is inserted in the course direction between the connecting threads of the three-dimensional knitted fabric. [Figure 2] This is a cross-sectional view of a three-dimensional knitted fabric illustrating a state in which a linear sensing member is inserted in the wale direction between the connecting threads of the three-dimensional knitted fabric. [Figure 3] This is a photograph, instead of a diagram, showing the linear sensing element being inserted between the connecting threads of a three-dimensional knitted fabric (Fusion®). [Figure 4] This is a photograph, serving as a substitute for a diagram, illustrating the procedure for measuring the load sensor sensitivity of a sheet-like sensing element by repeatedly installing and removing 1L and 2L plastic bottles. [Figure 5] This is an R-graph, which shows the change in resistance value and indicates the sensitivity of the load sensor. [Figure 6] This is a graph (R' / R graph) showing the change in R' (resistance when mounted) / R (resistance before mounting). [Figure 7] These are photographs of the front fabric, back fabric, connecting yarn (cross-section viewed in the course direction), and connecting yarn (cross-section viewed in the wale direction) of the three-dimensional knitted fabric (Fusion®) used in Examples 1-8. [Figure 8]These are photographs of the top, bottom, cross-section (viewed in the course direction), and cross-section 2 (viewed in the wale direction) of the sponge and Breathair®, other than the three-dimensional knitted fabric (Fusion®), used in Examples 9 and 10. [Figure 9] This is a schematic diagram of the linear sensing member of this embodiment. [Figure 10] This shows the external appearance and a magnified photograph of the linear sensing member of this embodiment, which is made of twisted yarn. [Figure 11] This is a schematic diagram of an apparatus for measuring the resistance change between two covering yarns, each consisting of a linear conductor as a core material and high-resistance fibers as a covering material, wrapped in one direction. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described in detail below. One embodiment of the present invention is a sheet-like sensing member characterized in that a linear sensing member is fixed inside a sheet-like cushion material of a predetermined thickness having voids inside in the thickness direction. A preferred embodiment of the first embodiment of the present invention is preferably a sheet-like sensing member in which the sheet-like cushion material of a predetermined thickness having voids inside is a three-dimensional knitted fabric of a predetermined thickness composed of a face knit, a back knit and a plurality of connecting yarns connecting them, and the linear sensing member is inserted in any direction between the plurality of connecting yarns and is gripped by contact with the connecting yarns. In this specification, the term "fixed" is not limited to a state in which the object is fixed in a manner that prevents substantial displacement by adhesives, fixing jigs, etc., but also includes, for example, a state in which the object is "held by contact with the connecting yarn in a three-dimensional knitted fabric" as described above, and the contact point moves as the connecting yarn deforms due to the load.

[0013] The sheet-like cushioning material in this embodiment is not particularly limited as long as it has a predetermined thickness with voids inside (in the thickness direction) and can be unfolded in two dimensions. Examples include three-dimensional knitted fabrics, foamed resin sponges, and three-dimensional mesh fiber structures made of fibrous resin. From the viewpoint of detection performance, ease of insertion of linear sensing members, and suppression of positional displacement before and after load application, a three-dimensional knitted fabric is preferred. [3D knitting] There are no particular restrictions on three-dimensional knitted fabrics, but they include so-called double raschel warp knitted fabrics, for example, three-dimensional knitted fabrics (Fusion® registered trademark) manufactured by Asahi Kasei Advance Corporation. As a three-dimensional knitted fabric, it is preferable, from the viewpoint of improving load sensing sensitivity, that when there is no load, all or part of the connecting yarn is curved, and when a load is applied, the thickness of the sensing member decreases and the degree of such curvature increases. In this three-dimensional knitted fabric, the arrangement of connecting yarns differs depending on the direction of the knit. As shown in Figure 2, the connecting yarns in a cross-section viewed from the wale direction are basically bent in random directions, but as shown in Figure 1, the connecting yarns in a cross-section viewed from the course direction are bent in a consistent direction. Due to this difference, fiber sensors inserted in the course direction can efficiently sandwich the fiber sensors due to bending under load, and thus, compared to those inserted in the wale direction, a greater load sensing sensitivity can be expected. In a three-dimensional knitted fabric, if there is a cross structure or truss structure in which connecting yarns are intentionally arranged diagonally, as described in Japanese Patent Publication No. 4056885, the structure is not visible in the cross section viewed from the course direction, but an X-shaped cross structure can be observed in the connecting yarns in the cross section viewed from the wale direction (see Figure 2). When inserting a three-dimensional knitted fabric with a cross structure or truss structure in the wale direction, the ease of insertion is reduced due to the crossing of the connecting yarns, but the positional displacement before and after load application is suppressed by being supported at the intersection.

[0014] Polytrimethylene terephthalate (PTT) has a lower Young's modulus compared to PET and PBT, and is similar to that of nylon 6. On the other hand, PTT has a higher elastic recovery rate compared to PET, PBT, and nylon 6. Therefore, from the viewpoint of contacting the sensing fiber member and improving the sensitivity of load sensing, the material of the connecting yarn is preferably PTT. Furthermore, from a similar viewpoint, the fineness of the connecting yarn is preferably 50 dtex or more and 500 dtex or less, more preferably 200 dtex or more and 300 dtex or less. With a more favorable fineness, the force that grips the yarn under load tends to be stronger, preventing the connecting yarn layer from easily collapsing under load, and thus increasing the load sensing sensitivity. If the fineness is smaller than this, there is a possibility that the load applied to the sheet-like sensing member cannot be efficiently detected. In this case, it is necessary to take measures such as using a three-dimensional knitted fabric with a truss structure or cross structure for the connecting yarn to prevent collapse under load, and increasing the number of connecting yarns per unit area to increase the cross-sectional area of ​​the connecting yarn per unit area, as described later.

[0015] For three-dimensional knitted fabrics, the following formula applies: Cross-sectional area of ​​connected yarn per unit area = (N × D) / (1 × 10) 6 ×ρ) {In the formula, N is the finished product of the three-dimensional diameter knitted fabric, 1 cm} 2 Number of connected threads per unit (threads / cm) 2 ) and D is the fineness of the connecting yarn (dtex: 1×10 6 The mass per cm (g) is given by ρ, and ρ is the specific gravity (g / cm³) of the connecting thread material. 3 The cross-sectional area of ​​the connecting yarn per unit area of ​​the three-dimensional warp knitted fabric, calculated as}, is 0.01 (cm²). 2 ) or more 0.10(cm 2 Preferably, the following conditions apply. This is because, since the fiber sensor detects the load by being sandwiched between the bent connecting threads, the sensor sensitivity increases when there are many connecting threads per certain range and the connecting thread fineness is large.

[0016] Furthermore, it is preferable that the thickness of the sheet-like sensing member be between 2 mm and 20 mm. In the sheet-like sensing member of this embodiment, detection is performed by tightening the linear sensing member by the bending of the connecting threads. If the thickness is less than 2 mm, the deformation of the connecting threads is small and the effect is difficult to achieve, and if it exceeds 20 mm, it becomes difficult to detect the bending state of the connecting threads.

[0017] The linear sensing member, which is inserted in any direction between the plurality of connecting threads of the sheet-like sensing member according to the present invention and grasped by contact with the connecting threads, is not particularly limited as long as it has a linear structure with a predetermined length, but preferably has at least two covering yarns in which high-resistance fibers as a covering material are wound in one direction around a linear conductor as a core material, and two of these covering yarns are arranged in close proximity to each other, and reads the change in resistance between the linear conductors of the two covering yarns arranged in close proximity to each other, wherein the value of the resistance (sensor resistance) between the linear conductors of the covering yarns arranged in close proximity to each other is in the range of 0.5kΩ to 5GΩ per 10cm length of the linear conductor, and the sensor resistance value is 20 to 1 × 10 times the value of the resistance (wiring resistance) per 10cm length of the linear conductor alone. 9 It can be a linear sensing member that is twice as long.

[0018] The linear conductor (core thread) used as the core material is not particularly limited as long as it is conductive, but it may be a linear conductor whose material itself is conductive, such as conductive fibers, carbon fibers, or metal fibers, or a linear conductor in which conductivity has been imparted to a non-conductive fiber. As for the former, carbon fibers, which are made by fibrousizing carbon, are preferred because they have high durability in the moisture sensing described later. Also, if the material is made by fibrousizing SUS material, it is preferred because it can ensure rust prevention and allows for simple termination processing for connection to circuits, etc. As for the latter, it is preferred to use materials such as nylon fibers that have been plated with metal such as silver or copper, or metal foil processed into tape and wound around the fibers, or fibers to which an aerosol-like conductor has been sprayed onto the surface of the fibers, from the viewpoint of improving texture and flexibility. In this case, it is preferable that the conductive fiber is made of multifilaments because it can obtain good conductivity and increase strength. Tensile strength can be further increased by using high-strength fibers such as polyarylate or aramid instead of nylon. Alternatively, a linear conductor may be used in which conductivity is imparted using a stretchable metallic ink around an elastic material such as urethane or silicone. In this case, a stretchable fibrous member can be obtained. Furthermore, a mixture of conductive and insulating materials formed into a linear shape may be used as the linear conductor. For example, if a material is used in which a carbon-based conductive material or metal is mixed with a resin such as nylon or polyester and processed into a linear shape, a linear conductor can be obtained at a significantly lower cost, although its conductivity will be inferior. Also, from the viewpoint of cost reduction, the linear conductor may be one or more metal wires, although the texture will be worse. For example, if a metal wire with a diameter of about 30 μm to 1 mm is used, the strength can be significantly increased.

[0019] The fineness of the linear conductor, for example, conductive fiber, is preferably 10 dtex to 15,000 dtex, and more preferably 20 dtex to 5,000 dtex, from the viewpoint of easily obtaining a good texture. In the case of a multifilament, the fineness of the single filament is preferably 1 dtex to 30 dtex, and more preferably 2 dtex to 10 dtex, from the viewpoint of easily obtaining a good texture and easily obtaining high conductivity. The number of filaments is more preferably 10 to 200. Having 10 or more filaments is preferable because it is easier to obtain a good texture and ensure good conductivity. However, if the number of filaments is too high, the cost will increase and the rigidity will also increase, which may conversely reduce the texture. Considering all of these factors, it is preferable to keep the number of filaments within the above range.

[0020] The conductive material forming the linear conductor may be the same material between the two covering yarns in a pair, or different materials may be used; any combination of materials can be used. For contact, load, and tension sensing applications, using the same conductive material is preferable because it allows for efficient production. When sensing liquids such as water, if different materials are used as the linear conductors of the two covering yarns in a pair, a voltage or current is generated by an electrochemical action called galvanic action when the liquid adheres to these different materials, enabling liquid sensing without a power source. Examples of combinations of different materials include iron and copper, iron and silver, aluminum and copper, silver and copper, and any other combination can be used.

[0021] In this specification, the term "high-resistance fiber" as a covering material (also called cover yarn) is not particularly limited as long as it prevents electrical short circuits between pairs of linear conductors used as core materials. It may be an insulating fiber, a fiber containing semiconductor materials such as carbon-based materials, a piezoelectric material such as polylactic acid (PLA), or a ferroelectric material such as polyvinylidene fluoride (PVDF). However, in order to cover the linear conductors used as core materials without gaps in a stationary state and to prevent electrical short circuits, the cover yarn preferably contains either a multifilament high-resistance fiber or a spun yarn made of high-resistance fibers, which allows for uniform and even covering thickness from the viewpoint of covering properties, sensing performance, and texture. It is most preferably made of a multifilament high-resistance fiber or a spun yarn made of high-resistance fibers. The material of the high-resistance fiber is not particularly limited as long as it does not cause short circuits (electrical short circuits) between the core materials in an idling state without sensing action such as contact, tension, or liquid contact. When sensing external forces, using carbon-containing fibers is preferable because it allows for cost-effective and highly sensitive sensing. From the viewpoint of cost and availability, the main component of high-resistance fibers is preferably synthetic fibers such as polyester (PET), nylon (Ny, polyamide), epoxy, or acrylic, but natural fibers such as cellulose fibers, semi-synthetic fibers, or regenerated fibers may also be used. Furthermore, piezoelectric materials such as polylactic acid (PLA) and polyvinylidene fluoride (PVDF), ferroelectric materials, and biodegradable resins can be used as materials for high-resistance fibers. However, from the viewpoint of cost and texture when woven or knitted, it is preferable to use fibers used for clothing, such as polyester, nylon, or acrylic, as the main component. Furthermore, when sensing is performed by changing the resistance value, a mixed material in which conductivity is imparted to insulating fibers may be used as the high-resistance fiber that forms the cover thread (sheath thread). In this case, the conductivity range of the sheath thread should be within a range in which the change in resistance between the linear conductors of two covering yarns placed in close proximity to each other can be read. Specifically, the resistance value between the linear conductors of covering yarns placed in close proximity to each other (sensor resistance) should be within the range of 0.5kΩ to 5GΩ, and the sensor resistance value should be 20 times to 1 × 10⁻¹⁶ times the resistance value of the linear conductor alone (wiring resistance). 9 It is preferable that it is twice as much. This prevents electrical short circuits when a voltage is applied between two linear conductors constituting two adjacent covering yarns, and because the sensor resistance is sufficiently large compared to the wiring resistance, it is not affected by the wiring resistance and can accurately detect loads, tensile forces, etc. The sensor resistance is even more preferable if it is in the range of 0.5kΩ to 100MΩ, as this simplifies the readout circuit. The range of electrical resistivity of the sheath yarn material is 10 4 Ω·m~5×10 9 The fact that the resistance value is Ω·m is preferable because it can easily satisfy the above range of sensor resistance values. As a material for the sheath thread to which a slight conductivity is imparted, a material can be used that contains a conductive imparting material, such as a carbon-based conductive material, metal particles, metal sulfides such as copper sulfide, or metal oxides such as tin oxide or zinc oxide, in addition to an insulating material such as polyester, nylon, or acrylic. Alternatively, both insulating and conductive fibers may be appropriately mixed and used as the sheath thread. For example, antistatic fibers such as Kuracarbo (manufactured by Kuraray Co., Ltd., registered trademark), Beltron (manufactured by KB Seiren Co., Ltd., registered trademark), and Thunderon (manufactured by Nippon Sanmo Senmon Co., Ltd., registered trademark) can be selected and used to achieve the desired sensor resistance value.

[0022] In this embodiment, the linear sensing member preferably uses a combination of fibers that dry more quickly as the material of the covering material (cover yarn). In particular, when sensing moisture or ethanol, using quick-drying fibers for the cover yarn allows it to dry quickly after contact with moisture, etc., and thus return to its original state more quickly. As quick-drying fibers, synthetic fibers with a low moisture content can also be used, but in order to achieve both water absorption and quick-drying performance, a combination of synthetic fibers and cellulose fibers is particularly preferable. In this case, as synthetic fibers, polyester, nylon, acrylic, etc. are preferred, and as cellulose fibers, natural cellulose fibers such as cotton and linen, regenerated cellulose fibers such as rayon, polynosic, lyocell, cupro, modal, etc., and semi-synthetic fibers such as acetate are preferred, and multifilament long fibers are particularly preferred. The combination of both fibers can be achieved by mixing both fibers in the cover yarn, or by covering with synthetic fibers and cellulose fibers respectively in the double covering described later.

[0023] The fineness of the high-resistance fibers is preferably 15 dtex to 25,000 dtex, and more preferably 30 dtex to 8,000 dtex, from the viewpoint of easily avoiding electrical short circuits between core materials. In the case of multifilaments, the fineness of the single filament is preferably 1 dtex to 10 dtex, and more preferably 2 dtex to 8 dtex, from the viewpoint of more easily obtaining a good texture.

[0024] There are no particular restrictions on the method for manufacturing the covering yarn, but for example, the method described in Patent Document 5 can be cited.

[0025] Figures 9 and 10 show an example in this embodiment where two covering yarns (7) are twisted together to form a linear sensing member. In this case, it is preferable that the winding direction of the covering material (cover yarn) (6) arranged around the linear conductor (5) as the core material of the two covering yarns (7) which are placed close to each other is the same, and that the two covering yarns are double-twisted yarns (8) which are double-twisted in the opposite direction to the winding direction of the multifilament high-resistance fiber. Double-twisting (twisting in the opposite direction to the winding direction of the covering) reduces the torque of the resulting yarn, making it easier to handle in the manufacturing process. Also, if the yarn is double-twisted, the two covering yarns will naturally be placed close to each other, and the two covering yarns will have intersecting contact points.

[0026] The following formula for the covering yarn: Twist coefficient K = (SS + SC) 1 / 2 ×R The twist coefficient K, expressed in the formula {wherein SS is the fineness (dtex) of the linear conductor as the core material, SC is the total fineness (dtex) of the covering material, and R is the number of turns (twists) (turns / m) of the covering material}, is preferably between 7,000 and 50,000. If the twist coefficient K is 7,000 or more, electrical short circuits between the two linear conductors become less likely, while if it is 50,000 or less, it becomes easier to obtain a larger sensor output. In the case of double covering, the twist coefficients for the first and second layers of covering are calculated and the average value is used. Also,

[0027] Figure 11 is a schematic diagram of an apparatus for measuring the resistance change between two covering yarns, each consisting of a linear conductor as a core material and covered with multifilament high-resistance fibers wound in one direction as a covering material. The conductive fibers are opened at the ends of the two pair of covering yarns, and a source meter (SMU, source measure unit) capable of supplying voltage and current while simultaneously measuring voltage, current, and resistance is connected to measure the resistance between the pair of covering yarns. Alternatively, instead of using such measuring equipment, a readout circuit consisting of an analog / digital conversion circuit, a current-voltage conversion circuit, an amplification circuit, etc., can be fabricated and used to measure the resistance.

[0028] The linear sensing member of this embodiment can detect external forces by causing changes in the resistance or capacitance (impedance) between two linear conductors. Furthermore, if the external force is tensile force or bending stress, a change in impedance occurs, allowing for detection of this external force. Alternatively, if a substance that can cause an impedance change between the two linear conductors is included, the presence or absence of this substance can be detected. For example, if non-ultrapure water such as tap water, saline solution, an ion drink, or a mixture of water and ethanol is dropped between two linear conductors, the resistance between the conductors decreases significantly and the current between them increases, allowing for detection of the presence or absence of these liquids. Similarly, since a change in impedance occurs when humidity changes, it can also be used as a humidity sensor.

[0029] Alternatively, it is possible to simultaneously detect contact or the application of load and contact with liquids such as moisture. The change in resistance when a load is applied and when moisture is dripped differs by more than five times, and the output changes moment by moment as the moisture dries, so it is possible to distinguish between these detections from the behavior of the output value. In such an embodiment, for example, by constructing a fabric in which multiple strands of the aforementioned twisted yarns are woven into a bed sheet pad, it becomes possible to simultaneously detect the movement of bed users such as those requiring care, as well as water leakage, urinary incontinence, etc. The sheet-like sensing member of the present invention is obtained by inserting the aforementioned linear sensing member into the interior (preferably near the middle) of the sheet-like cushion material in the thickness direction. The sensing member must not substantially hinder the two-dimensional unfolding of the sheet-like cushion material. Here, "not substantially hindering" means that when the sheet-like sensing member deforms due to a load, the deformation is not hindered by unwanted constraints caused by the inserted linear sensing member. The term "fixed" has the meaning described above. As described above, by inserting the linear sensing member into the interior in the thickness direction, it is possible to position the sheet-like cushion material without substantially hindering its two-dimensional unfolding. If there are continuous voids in the middle of the thickness direction, such as in a three-dimensional knitted fabric, linear sensing members can be inserted without the need for drilling. Even in structures with discontinuous voids, or continuous but non-linear voids, such as foamed sponges or three-dimensional mesh fiber structures, insertion is possible if holes for inserting the linear sensing member are made in advance. However, this process is time-consuming, and there is a concern that the load detection performance may decrease if the holes are too large for the linear sensing member. [Examples]

[0030] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic value used in the following examples were as follows.

[0031] (1) Measurement of load sensor sensitivity As shown in Figure 3, a solder thread folded in half was pre-inserted between the connecting threads of a three-dimensional knitted fabric (Fusion®) approximately 30 cm square. The linear sensing member was then guided by this solder thread and inserted into the connecting threads between the front and back surfaces of the three-dimensional knitted fabric approximately 30 cm square. The length of the linear sensing member was set to 10 cm to ensure effective sensing. Next, as shown in Figure 4, a 9.5 x 9.5 cm bakelite plate was placed on top of the linear sensing member insertion section. 1L and 2L PET bottles were placed on the bakelite plate and then removed five times to verify whether the inserted linear sensing member could detect the load of the PET bottles. The process of "placing for 10 seconds, then removing for 20 seconds" was repeated. A Keithley 2450 source meter was applied to measure the current between the two core threads of the linear sensing member, and the change in resistance was calculated based on these test results.

[0032] (i) R graph determination An example of the test results is shown in Figure 5 (R graph). If the difference between the resistance value before and after loading was clearly visible as a peak in all five load applications, it was judged as "○"; if the peak was clearly visible in at least one of the five repetitions, it was judged as "△"; and if none of the five repetitions showed a clearly visible peak, it was judged as "×". (ii) R' / R graph determination An example of the test results is shown in Figure 6 (R' / R graph). Here, the horizontal axis represents the experiment number for each test (arranged in the order of the examples). The resistance value R was calculated before placing the PET bottle, and the resistance value R' was calculated after placing the bottle. If R' / R (average value after 5 repetitions) was 0.95 or less, it was judged as "○", and if it was greater than 0.95, it was judged as "×".

[0033] (iii) Overall assessment As shown in Table 1 below, the R graph judgment and R' / R graph judgment described above were performed for both the 1L PET bottle test and the 2L PET bottle test. Each item was assigned points: 2 points for "〇", 1 point for "△", and 0 points for "×". A total score of 8 points for the four items was rated "◎", 7-5 points was rated "〇", 4-1 points was rated "△", and 0 points was rated "×". The overall evaluation was then performed as shown in Table 3 below. For example, in Example 1, the result was "R〇〇;R' / R〇〇" with a total of 8 points, so the overall evaluation was "◎". In Example 3, the result was "R△〇;R' / R××" with a total of 3 points, so the overall evaluation was "△".

[0034] (2) Misalignment of twisted yarns due to loading and unloading The results were determined as follows: if the inserted linear sensing element moved almost from its initial position due to loading and unloading, it was judged as "◎"; if it moved to the center of the connecting thread (center in the thickness direction) but did not move beyond the center to the opposite side, it was judged as "〇"; if it moved beyond the center of the connecting thread, it was judged as "△"; and if it deviated significantly from the insertion position and the sensor could not be fixed, it was judged as "×".

[0035] (3) Easy insertion of sensor thread: If the sensor thread could be inserted using the method described in the example without requiring additional processing, it was judged as "○"; if additional processing was required, it was judged as "△"; and if insertion was not possible, it was judged as "×".

[0036] (4) Cross-sectional area of ​​connected yarn per unit area = (N × D) / (1 × 10) 6 Method for measuring ×ρ N is the finished product of a three-dimensional knitted fabric, 1 cm 2 Number of connected threads per unit (threads / cm) 2 This can be calculated from the number of stitches per unit length in the course direction (for example, per inch (2.54 cm)). Since the connecting yarn goes back and forth, twice the number of stitches is used as the basis. The same applies to the course direction. D is the fineness (dtex) of the connecting yarn, and ρ is the specific gravity (g / cm³) of the connecting yarn material. 3 ) and the materials used in the examples were those with known values: PTT: 1.33, PET: 1.38, and nylon: 1.14.

[0037] [Example 1 (Connecting yarn: thick fine PTT, inserted in the wale direction, connecting yarn structure: 2 strands crossed)] Using an 18-gauge, 14mm bobbin-to-bobbin double raschel knitting machine equipped with six reeds, 280 ds / 48 filament polyester fibers were supplied in a 1-in, 1-out arrangement from two reeds (L1, L2) that formed the front fabric, 200 ds / 48 monofilament polytrimethylene terephthalate fibers were supplied in a 1-in, 1-out arrangement from two reeds (L3, L4) that formed the connecting section, and furthermore, 280 ds / 48 filament polyester fibers were supplied in a 1-in, 1-out arrangement from two reeds (L5, L6) that formed the back fabric. Both the front and back featured a 10-course tortoiseshell pattern, and the connecting yarn was used to link the front and back in a cross direction. A three-dimensional knitted fabric was knitted at a density of 25 courses / 2.54 cm. The resulting fabric was scoured at 90°C for 20 minutes, stretched while heating in the width direction, and then dry-heat-set at 180°C for 90 seconds to obtain a three-dimensional knitted fabric. The finished product had a knit count of 31.0 / 2.54 cm in the course direction and 10.2 / 2.54 cm in the wale direction. Figure 7 shows a photograph of the three-dimensional knitted fabric that was created.

[0038] The organizational structure was as follows: (edited organization) L 1: 1011 / 1211 / 1011 / 1222 / 2122 / 2322 / 2122 / 2322 / 2111 / 1211 / / (1 in 1 out) L 2: 2322 / 2122 / 2322 / 2111 / 1211 / 1011 / 1211 / 1011 / 1222 / 2122 / / (1 in 1 out) L 3: 1010 / 3434 / 1010 / 1212 / 2122 / 4545 / 2121 / 2323 / 2121 / 1212 / / (1 in 1 out) L 4: 4545 / 2121 / 4545 / 4343 / 3434 / 1010 / 3434 / 3232 / 3434 / 4343 / / (1 in 1 out) L 5: 1110 / 1112 / 1110 / 1112 / 2221 / 2223 / 2221 / 2223 / 2221 / 1112 / / (1 in 1 out) L 6: 2223 / 2221 / 2223 / 2221 / 1112 / 1110 / 1112 / 1110 / 1112 / 2221 / / (1 in 1 out)

[0039] A linear conductor was made from SUS304 fiber with a fineness of 900 dtex and 100 filaments. A spliced ​​Kuracarbo 480 dtex was used as the sheath thread. Using the above core and sheath threads, a double covering process of 900 T / m on both the top and bottom was performed using a double covering machine with a Z twist. Two strands of the obtained double covering yarn were combined and twisted together to produce a multi-ply yarn with a twist count of 250 T / m. The fineness of this multi-ply yarn was 4470 dtex. This twisted yarn electrically opened up two linear conductors at one end and supplied voltage and current between two linear conductors at the other end. Simultaneously, by measuring voltage, current, and resistance, it functioned as a linear sensing element (load sensor) in which voltage, current, and resistance changed when a load was applied. The obtained 15 cm of twisted yarn was cut, and each end was divided into two 2.5 cm strands so that the twisted portion was 10 cm long. One end was insulated and secured with tape while it was still divided into two strands, and one of the two core threads was connected to the source meter terminal (see Figures 9-11).

[0040] The twisted yarn was inserted from the front of the knitted fabric in the wale direction (parallel to the warp threads (longitudinal direction) of the knitted fabric). The insertion method involved inserting a jig such as a wire or threader from the front of the exit point, passing the entire 10cm of the twisted section between the connecting threads, and bringing it out again from the front. The twisted thread was then fixed to this jig and pulled to the exit to insert it (see Figure 3). The twisted yarn was inserted straight into the gaps between the connecting yarns, ensuring it did not bend. The twisted yarn was then inserted into the three-dimensional knitted fabric until the entire twisted yarn, which would serve as the sensor, was positioned between the connecting yarns, thereby obtaining a sheet-like sensing member. Voltage was supplied from a source meter connected between the two core threads of one of the obtained sensing members, and the aforementioned test was performed. The change in resistance was measured, and the results were evaluated using the evaluation method described later. As a result, the load from the sensing member to the area in which the sensing thread was inserted was quickly detected. Even when repeated loads were applied, the sensor threads remained positioned on the intersections of the cross-linked knitted structure, preventing them from moving significantly.

[0041] [Example 2 (Inserted in the direction of the course)] A sheet-like sensing member was obtained in the same manner as in Example 1, except that it was inserted into the knitted fabric in the course direction (a direction perpendicular to the warp threads (longitudinal direction) of the knitted fabric). The resulting sensing element quickly detected the load and unloading from the sensing element to the area in which the sensing thread was inserted. The sensing thread was sandwiched between the connecting threads, which were bent in a certain direction by the load, and was able to detect even small loads with high sensitivity. Even when repeated loads were applied, the sensing thread inserted beyond the central point where the bending angle of the bent connecting threads was maximum did not move significantly up or down.

[0042] [Example 3 (Connecting thread: PET, inserted in the wale direction, connecting thread structure: 2 strands crossed)] A sensing member was obtained in the same manner as in Example 1, except that the connecting thread was replaced with polyethylene terephthalate (PET) fiber of the same fineness. The resulting sensing element quickly detected the load applied from the element to the area where the sensing thread was inserted. Even with repeated load application, the interwoven structure prevented the inserted sensing thread from moving significantly up and down. However, the sensor sensitivity was worse than that of Example 1.

[0043] [Example 4 (Inserted in the direction of the course)] A sensing member was obtained in the same manner as in Example 3, except that the twisted yarn was inserted in the direction of the course. The resulting sensing element quickly detected the load and unload from the upper and lower surfaces of the sensing element in the area where the sensing thread was inserted. Sandwiched between connecting threads bent in a specific direction, it was able to detect even small loads with high sensitivity. Even with repeated load application, it did not move significantly up or down beyond the central point where the bending angle of the connected threads was maximum.

[0044] [Example 5 (Connecting thread: nylon, inserted in the wale direction, connecting thread structure: no cross, straight)] Using a 22-gauge, 3.4mm bobbin-to-bobbin double raschel knitting machine equipped with six reeds, polyethylene terephthalate fibers with 55 decitex 18 filaments were supplied in a 1-in-1-out arrangement from two reeds (L1, L2) that form the front fabric, monofilament of nylon 6 fibers with 104 decitex were supplied in a 1-in-1-out arrangement from two reeds (L3, L4) that form the connecting section, and furthermore, polyethylene terephthalate fibers with 55 decitex 18 filaments were supplied in a 1-in-1-out arrangement from two reeds (L5, L6) that form the back fabric. Both the front and back feature a 4-course diamond mesh, and the connecting yarn is used to create a straight-line connection between the front and back. A three-dimensional knitted fabric was then knitted at a density of 24.2 courses / 2.54 cm. The obtained raw fabric was scouring at 90°C for 20 minutes, then widened by 15%, and dry-heat-set at 180°C for 90 seconds to obtain a three-dimensional knitted fabric. The finished product had a knit count of 27.7 / 2.54cm in the course direction and 17.3 / 2.54cm in the wale direction. Figure 7 shows a photograph of the three-dimensional knitted fabric that was created. The organizational structure was as follows: (edited organization) L 1: 1011 / 1222 / 2322 / 2111 / / (1 in, 1 out) L 2: 2322 / 2111 / 1011 / 1222 / / (1 in, 1 out) L 3: 1010 / 1212 / 2323 / 2121 / / (1 in, 1 out) L 4: 2323 / 2121 / 1010 / 1212 / / (1 in, 1 out) L 5: 1110 / 1112 / 2223 / 2221 / / (1 in, 1 out) L 6: 2223 / 2221 / 1110 / 1112 / / (1 in, 1 out)

[0045] Using the obtained three-dimensional knitted fabric, a sensing member was obtained in the same manner as in Example 1. The resulting sensing element quickly detected the load and unloading from the upper and lower surfaces of the sensing element in the area where the sensing thread was inserted. Even with repeated loading, it did not move significantly up or down beyond the central point where the bending angle of the bent connecting thread was maximum. However, the sensor sensitivity was worse than that of Example 1.

[0046] [Example 6 (Insertion in the course direction)] A sensing member was obtained in the same manner as in Example 5, except that the twisted yarn was inserted in the direction of the course. The resulting sensing element quickly detected the load applied from above to the area where the sensing thread was inserted. Sandwiched between connecting threads bent in a specific direction, it was able to detect even small loads with high sensitivity. Even with repeated load application, it did not move significantly up or down beyond the central point where the bending angle of the connected threads was maximum. However, the sensor sensitivity was worse than that of Example 1.

[0047] [Example 7 (Connecting yarn: fine fineness PTT, inserted in the wale direction, connecting yarn structure: 2 strands crossed)] A sensing member was obtained in the same manner as in Example 1, except that the fineness of the polytrimethylene terephthalate fibers forming the connecting portion was set to 110 decitex. The resulting sensing element quickly detected the load applied from the element to the area where the sensing thread was inserted. Even with repeated load application, the knitted structure, which was connected diagonally in a cross-like manner, prevented the inserted sensing thread from moving significantly up or down.

[0048] [Example 8 (Inserted in the direction of the course)] A sensing member was obtained in the same manner as in Example 7, except that the twisted yarn was inserted in the direction of the course. The resulting sensing element quickly detected the load applied from the element to the area where the sensing thread was inserted. Even with repeated load application, it did not move significantly up or down beyond the central point where the bending angle of the connecting thread was maximum. However, the sensor sensitivity was worse than that of Example 1.

[0049] [Example 9 (Sponge)] I purchased a kitchen sponge (non-membrane sponge, polyurethane foam) from the official Daiso Set Store (daisonet.com). Because it was difficult to insert the fiber sensor, a hole was drilled through the side of a cubic polyurethane foam cut to approximately 30 cm on each side (because the hole drilled with the drill was filled by the surrounding polyurethane foam expanding, making it difficult to insert the thread). With the sensor thread fixed to the thread threader, the thread was inserted while digging through the hole, and the twisted thread from Example 1 was passed through the hole to obtain the sensing member. The resulting sensing element detected loads from both the upper and lower surfaces of the sensing element in the area where the sensing yarn was inserted. Unlike three-dimensional knitted fabrics, the load spread in all directions. In the 2L PET bottle test, the element could not support the load and the PET bottle tipped over, so detection was deemed impossible. Figure 8 shows a photograph of a sponge.

[0050] [Example 10 (BreathAir®)] A commercially available 40mm thick Breathair® (a three-dimensional mesh fiber structure formed from polyether ester elastomer fibers) was used. Because it was difficult to insert the fiber sensor using the method of Example 1, a hole was drilled through the side of a piece of Breathair cut to approximately 30 cm square, and the twisted yarn from Example 1 was passed through the hole to obtain a sensing member. It was difficult to drill long holes, and it was not possible to insert a 10cm section of the twisted material, so the test was conducted with a 5cm section. The obtained sensing member detected the load from the upper surface of the sensing member to the area in which the sensing thread was inserted. Figure 8 shows a photograph of Breathair®. The load sensor sensitivity and performance evaluation results for Examples 1 to 10 are shown in Table 1 below.

[0051] [Table 1]

[0052] Examples 1 to 8, in which a multi-twist yarn structure sensor was inserted into the inner layer of a three-dimensional knitted fabric as a sheet-like sensing member, exhibited excellent performance in terms of load detection performance, ease of insertion of linear sensing members, and suppression of positional displacement before and after load application. In particular, it was found that sensitivity could be increased by using a three-dimensional knitted fabric with relatively thick PTT fibers for the connecting yarn, and that sensor sensitivity and ease of insertion / suppression of positional displacement tended to be inversely related depending on the direction in which the sensor was inserted. Furthermore, load detection was also possible in Examples 9 and 10, which used sheet-like cushioning materials other than three-dimensional knitted fabrics. [Industrial applicability]

[0053] The sheet-like sensing member according to the present invention preferably provides a technology for easily mounting a sensor by passing a linear sensing member through the gaps in the connecting threads inside a three-dimensional knitted fabric. This has the effect of realizing a sensing member that is excellent in wear resistance and texture, and can be easily replaced in the event of a malfunction. When a fiber sensor is sandwiched between two types of materials, if the upper material is flexible, it will absorb part of the load, making it difficult to sense the load sensitively. However, as in the present invention, when a fiber sensor is inserted between the connecting threads of a three-dimensional knitted fabric, there is no such absorption of load, and therefore the load can be sensed sensitively. Furthermore, when sandwiched between materials, the sensor position tends to shift when loading and unloading is repeated, requiring some form of fixing. However, when a fiber sensor is inserted between the connecting threads of a three-dimensional knitted fabric, the fiber sensor is held in place by contact with numerous connecting threads, so a special fixing method is not required, the fiber sensor can be fixed in a replaceable state, and it also has a superior texture. Furthermore, when using a sensing fiber member as a fiber sensor inserted between connecting yarns of a three-dimensional knitted fabric, which has at least two covering yarns in which a high-resistance fiber as a covering material is wound in one direction around a linear conductor as a core material, and two of these covering yarns are arranged in close proximity to each other, such a linear sensing member can be processed in long lengths, is highly productive in mass production, is flexible and has a superior texture, and is significantly less expensive than conventional sensing fiber members (piezoelectric threads) that use piezoelectric materials for contact. In other words, such a linear sensing member can sense load and moisture using common fiber materials such as polyester, nylon, synthetic fibers, or natural or regenerated cellulose fibers, resulting in very low costs. Moreover, because it uses covering technology, a fiber processing technology for which know-how has been established, it can be processed in long lengths, is highly productive in mass production, and a processed yarn with a much better texture than piezoelectric thread can be realized, making it easy to process into a sheet-like sensing member. Therefore, the sheet-like sensing member according to the present invention can be widely used in various applications, such as smart textile applications where an electrical functional element is provided on a flexible and stretchable fiber base material, for example, rugs that can be detected when stepped on, security mats for detecting people entering and leaving, mats for counting people, etc., contact sensing woven or knitted fabrics, for example, monitoring sensors in nursing and care settings, sensors that digitize and transmit tactile sensations in production sites such as factories, seat members for various vehicles, members for embedding sensors in vehicle seat belts, etc., for example, embedding contact sensors (biosensors) in vehicle seat belts, steering wheels, dashboards, etc., sensors for detecting the presence or absence of people, sensors for preventing children from being left unattended in the back seat, and monitoring sensors. [Explanation of Symbols]

[0054] 5. Linear conductor as core material 6. High-resistance fibers as covering material (cover yarn) 7 Covering Yarn 8. Covering yarn twisted together to form a double-twisted yarn.

Claims

1. A sheet-like sensing member characterized in that a linear sensing member is fixed inside a sheet-like cushioning material of a predetermined thickness having voids inside, in the thickness direction thereof.

2. The sheet-like sensing member according to claim 1, wherein the sheet-like cushion material having a void inside is a three-dimensional knitted fabric of a predetermined thickness composed of a front knit fabric, a back knit fabric, and a plurality of connecting yarns connecting them, and the linear sensing member is inserted in any direction between the plurality of connecting yarns and is gripped by contact with the connecting yarns.

3. The sheet-like sensing member according to claim 2, wherein, when unloaded, all or part of the connecting thread is curved, and when loaded, the thickness of the sheet-like sensing member decreases and the degree of such curvature increases.

4. The following formula: Cross-sectional area of ​​connected yarn per unit area = (N × D) / (1 × 10) ６ ×ρ) {In the formula, N is the finished diameter of the knitted fabric, 1 cm} ２ Number of connected threads per cm ２ ) and D is the fineness of the connecting thread (dtex: 1 x 10 ６ The mass per cm is (g), and ρ is the specific gravity of the connecting thread material (g / cm³). ３ The cross-sectional area of ​​the connecting yarn per unit area of ​​the three-dimensional warp knitted fabric, calculated as follows, is 0.01 cm². ２ 0.10cm or more ２ The sheet-like sensing member according to claim 2 or 3, which is as follows:

5. The sheet-like sensing member according to claim 2 or 3, wherein the material of the connecting thread is polytrimethylene terephthalate (PTT).

6. The sheet-like sensing member according to claim 2 or 3, wherein the fineness of the connecting yarn is 50 dtex or more and 500 dtex or less.

7. The sheet-like sensing member according to claim 6, wherein the fineness of the connecting yarn is 200 dtex or more and 300 dtex or less.

8. The sheet-like sensing member according to any one of claims 1 to 3, wherein the thickness of the sheet-like sensing member is 2 mm or more and 20 mm or less.

9. The linear sensing member has at least two covering yarns, each covering a linear conductor as a core material by winding high-resistance fibers as a covering material in one direction, with two of these covering yarns arranged in close proximity to each other. The sensing member reads the change in resistance between the linear conductors of the two closely arranged covering yarns, wherein the resistance (sensor resistance) between the linear conductors of the closely arranged covering yarns is in the range of 0.5 kΩ to 5 GΩ per 10 cm of length of the linear conductor, and the sensor resistance is 20 to 1 × 10⁻¹⁶ times the resistance (wiring resistance) per 10 cm of length of the linear conductor alone. ９ A sheet-like sensing member according to any one of claims 1 to 3, which is a linear sensing member that is double the length of a linear sensing member.

10. The sheet-like sensing member according to claim 9, wherein the high-resistance fibers of the linear sensing member include either multifilament high-resistance fibers or spun yarn made of high-resistance fibers.

11. The sheet-like sensing member according to claim 9, wherein the linear sensing member senses contact or load of an object on the sheet-like sensing member.

12. The sheet-like sensing member according to claim 9, wherein the linear sensing member senses expansion, contraction, or bending deformation of the sheet-like sensing member.

13. The sheet-like sensing member according to claim 9, wherein the linear sensing member senses contact with a liquid or a change in humidity.

14. The following formula for the covering yarn of the linear sensing member: Twist coefficient K = (SS + SC) １／２ × R The sheet-like sensing member according to claim 9, wherein the twist coefficient K, expressed in the formula {wherein SS is the fineness (dtex) of the linear conductor as the core material, SC is the total fineness (dtex) of the covering material, and R is the number of turns (twists) (turns / m) of the covering material}, is 7,000 or more and 50,000 or less.

15. The sheet-like sensing member according to claim 9, wherein the covering yarn of the linear sensing member is a double covering yarn in which a linear conductor as a core material is covered with two covering materials, and the winding directions of the two covering materials are the same.

16. The sheet-like sensing member according to claim 9, wherein two covering yarns of the linear sensing member, which are arranged in close proximity to each other, have intersecting contact points.

17. The sheet-like sensing member according to claim 9, wherein the linear conductor used as the core material of the linear sensing member is a multifilament conductive fiber having 10 to 200 filaments.

18. The sheet-like sensing member according to claim 9, wherein the linear sensing member has two covering yarns arranged in close proximity to each other, in which the winding direction of the multifilament high-resistance fibers is the same, and the two covering yarns are multi-twisted yarns that are twisted in directions opposite to the winding direction of the multifilament high-resistance fibers.

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