JP2010101827A - Pressure detector - Google Patents

Abstract

There is provided a pressure detection device which is excellent in flexibility and air permeability and can detect not only the presence or absence of pressure applied from the outside but also the magnitude of pressure in a stepwise manner.
A cloth comprising one or a plurality of pressure sensing elements having a pair of opposed planar conductive members formed of conductive fibers and flexible planar spacers interposed between the conductive members. A pressure detection device is configured by a pressure sensor and a detection circuit that detects the magnitude of pressure in the opposing direction of the pair of conductive members in a plurality of stages according to the degree of deformation of the spacer of the pressure detection element. .
[Selection] Figure 1

Description

  The present invention relates to a pressure detection device that has both flexibility and reliability and can detect the magnitude of pressure in a stepwise manner.

  In recent years, with the progress of the ubiquitous information society, flexible electronic systems have been developed for use in various uses using cloth, such as carpets, wallpaper, seat covers, and clothes. In particular, thin sensors and input devices are expected to be applied to wearable computers and packaging materials, and are required to have flexibility, flexibility, breathability, comfort to the human body, and the like.

  Conventionally, as a thin pressure sensor, for example, a capacitor is formed by interposing a dielectric formed of urethane or rubber between electrodes formed of a conductor such as iron or brass, and an electrode when pressure is applied There has been proposed a pressure-sensitive sensor that detects that a pressure is applied by detecting a change in electric capacitance due to a change in the distance between electrode plates as a voltage change in an electrode portion (for example, Patent Document 1).

  However, the pressure-sensitive sensor as described above can only recognize and detect an on / off state whether or not a pressure exceeding a certain value is applied, and cannot detect the magnitude of the pressure. Therefore, the use is limited. Furthermore, since the capacitor electrode plate is formed of a metal plate, it is not sufficient in terms of flexibility, flexibility, breathability, and comfort to the human body to be applied to wearable computers and packaging materials. There was a problem of being.

JP 2004-212183 A

  The present invention has been made in view of the above-mentioned problems, and the object thereof is excellent in flexibility and air permeability, and not only the presence or absence of pressure applied from the outside, but also the level of pressure. An object of the present invention is to provide a pressure detection device that can detect automatically.

  In order to achieve the above-described object, a pressure detection device according to the present invention includes a pair of planar conductive members facing each other formed of conductive fibers and a flexible planar shape interposed between the conductive members. The cloth-like pressure sensor having one or a plurality of pressure sensing elements made of a plurality of spacers, and the magnitude of the pressure in the opposing direction of the pair of conductive members according to the degree of deformation of the spacers of the pressure sensing elements in a plurality of stages And a detection circuit for detecting at the same time.

  According to this configuration, while using a flexible material such as conductive fiber, it has a structure excellent in flexibility and breathability, etc. Detection can be performed in a plurality of stages.

  In the cloth sensor according to the present invention, it is preferable to use conductive polyvinyl alcohol-based fibers containing conductive fine particles as the conductive fibers. By configuring in this way, it is possible to effectively prevent the conductive layer from being broken or peeled off even during bending and washing, and even when used for applications that use cloth such as clothes, it is highly reliable. Can be achieved.

  In the above-described pressure detection device, the cloth-shaped pressure sensor can be composed of a plurality of pressure detection elements each having a different detection sensitivity. If comprised in this way, the magnitude | size of a pressure can be detected in a several step | paragraph by detecting which pressure detection element which has which detection sensitivity detected the pressure. Further, when the cloth-like pressure sensor having such a configuration is employed, a pressure detection device having a simple structure using a conventional pressure switch for detecting only on / off can be used as the pressure detection element.

  As described above, when the cloth pressure sensor of the pressure detection device according to the present invention is configured from the plurality of pressure detection elements having different detection sensitivities, the cloth pressure sensor is connected to the plurality of pressure detection elements. It is good also as what is laminated | stacked on the opposing direction of a member. By configuring in this way, the magnitude of the pressure can be reliably detected in a plurality of stages for a predetermined area in a direction orthogonal to the direction in which the pressure is applied.

  Further, as described above, when the cloth-like pressure sensor of the pressure detection device according to the present invention is configured from a plurality of the pressure detection elements having different detection sensitivities, the pressure detection elements are formed on the spacer, A contact resistance type planar switch that detects pressure when the pair of planar conductive members come into contact with each other through a plurality of through holes penetrating in the opposing direction of the pair of planar conductive members can be used. . With this configuration, it is possible to detect the magnitude of pressure step by step using a simple detection circuit that detects changes in resistance due to contact between two conductive members of a planar switch. It becomes.

  When the contact surface type switch is used as the pressure detection element used in the present invention, the plurality of surface switches are provided with spacers made of different materials, so that the pressure detection of each surface switch. The sensitivity may be set to different values, or the pressure detection sensitivity of each planar switch is set to a different value by forming through holes with different structures in the spacers of the plurality of planar switches. It may be. In this way, setting the pressure detection sensitivity of each pressure detection element by selecting and adjusting the spacer material or the structure of the through hole makes it easy to set the detectable pressure value of the pressure detection device over a wide range. It can be carried out.

  As described above, when the cloth-like pressure sensor of the pressure detection device according to the present invention is configured from a plurality of the pressure detection elements having different detection sensitivities, the spacer is formed of a dielectric material as the pressure detection element. Capacitor type planar switches can also be used. A capacitor-type planar switch is an element that detects the addition of pressure by detecting a change in the capacitance of a capacitor due to a change in the distance between two conductive members when a pressure is applied. It becomes possible to detect the thickness step by step with higher reliability.

  When the contact surface type switch is used as the pressure detection element used in the present invention, the plurality of surface switches are provided with spacers made of different materials, so that the pressure detection of each surface switch. The sensitivity may be set to a different value.

  The cloth-like pressure sensor of the pressure detection device according to the present invention is configured by a single capacitor-type pressure detection element in which the spacer is formed of a dielectric material, and the pressure is determined by a change in the capacitance of the capacitor due to deformation of the spacer. It is good also as what detects the magnitude | size of. By configuring in this way, the magnitude of the applied pressure is determined in steps by detecting the capacitance of the capacitor that changes in accordance with the deformation of the spacer, that is, the change in the distance between the pair of planar conductive members. In addition to the above, continuous detection is possible.

  Thus, according to the pressure detection device of the present invention, it is excellent in flexibility and breathability, can be applied to uses such as clothes and packaging materials, and is added from the outside. In addition to the presence or absence of pressure, the magnitude of pressure can be detected in stages.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments.

FIG. 1 is an exploded perspective view showing a schematic configuration of a pressure detection device 1 according to the first embodiment of the present invention. The pressure sensing device 1, a plurality a cloth-like pressure sensor 5 consists of a contact resistance type planar switch 3A ₁ to 3 A ₃ is a pressure sensing element 3 (three in the embodiment), cloth-like pressure sensor 5 The main component is the detection circuit 7 that detects the magnitude of the pressure detected in step S in a plurality of stages (three in this embodiment).

As shown in the exploded perspective view of FIG. 2, each of the contact resistance type planar switches 3 </ b> A _{1 to 3} </ b> A ₃ constituting the cloth pressure sensor 5 is a pair of planar conductive members facing each other, i.e., first conductive. The conductive member 11 and the second conductive member 13, and the planar spacers 15 </ b> A _{1 to} 15 </ b> A ₃ interposed between the conductive members 11 and 13. The first and second conductive members 11 and 13 are electrically connected to detection units 17 _{1 to} 17 ₃ in the detection circuit 7 via detection lines 16 made of a conductive material, respectively. As shown in FIG. 1, in the present embodiment, the cloth-like pressure sensor 5 includes planar switches 3 </ b> A _{1 to 3} </ b> A ₃ stacked in this order in the facing direction X of the first and second conductive members 11 and 13. It is configured.

  The first and second conductive members 11 and 13 are formed of conductive fibers, specifically, conductive polyvinyl alcohol fibers containing conductive fine particles (hereinafter sometimes referred to as conductive PVA fibers). However, as will be described later, other conductive fibers may be used.

In this embodiment, the planar spacers 15A _{1 to} 15A _{3 in} FIG. 2 are formed of an electrically insulating material having a large number of through holes 19 penetrating in the facing direction X. Against the planar switch _3A 1 to 3 A _3, when pressure is applied to the opposing direction X perpendicular to the surface direction of the planar switch _3A 1 to 3 A _3, first it was separated by planar spacer _15A 1 to 15A ₃ The first and second conductive members 11 and 13 come into contact with each other through the through hole 19 of the planar spacer when the flexible planar spacer 15 is deformed. This contact occurs conduction between the first and second conductive members 11 and 13, the change in electrical resistance due to the conduction, the detection unit 17 ₁ to 17 ₃ in the detection circuit 7 detects.

Since each of the planar spacers 15A _{1 to} 15A ₃ is formed of a material having different flexibility, the pressure detection sensitivity of the planar spacers 15A _{1 to} 15A ₃ , that is, the first and second conductive members 11 and 13 is determined. The pressures required to bring the two into contact with each other through the spacer through-holes 19 are set to different values. In the present embodiment, the pressure detection sensitivity of each of the planar switches 3A _{1 to} 3A ₃ is set to 25 g weight / cm ² , 75 g weight / cm ² , and 240 g weight / cm ² .

  In addition, when the cloth-like pressure sensor 5 is configured by a plurality of contact resistance type planar switches 3A as in this embodiment, in order to set the pressure detection sensitivity of each planar switch 3 to a different value, as described above. Instead of using a different material for each spacer 15A, or in addition to this, through holes 19 having different structures may be formed in the plurality of spacers 15A. That is, for example, the through holes 19 having different diameters and shapes of the through holes 19 and the number of holes per area in the spacer 15A may be formed in the plurality of spacers 15A.

  Next, operation | movement of the pressure detection apparatus 1 which concerns on this embodiment is demonstrated.

When the pressure P in the facing direction X is applied to the pressure detection device 1 shown in FIG. 1, the conductive members formed of conductive fibers of the planar switches 3A _{1 to} 3A ₃ stacked in the facing direction X. The planar spacers 15 </ b> A _{1 to} 15 </ b> A ₃ are deformed through the deformation of 11 and 13. Due to the deformation of the spacers 15A _{1 to} 15A ₃ , the first conductive member 11 and the second conductive member 13 arranged on both surfaces thereof come into contact with each other through a through hole 19 formed in the spacer.

By forming the spacers 15A1 to 15A3 with materials having different flexibility, the pressure detection sensitivity of each of the planar switches 3A _{1 to} 3A ₃ is 25 g weight / cm ² , 75 g weight / cm ² , 240 g weight / cm. ² , the value of the pressure P can be detected separately in stages. That is, when the first and second conductive members 11 and 13 are brought into contact with each other to cause conduction, the detection units 17 _{1 to} 17 ₃ corresponding to the planar switches 3A _{1 to} 3A _{3 in} which conduction has occurred cause electrical resistance. Detect changes in The detection unit in the detection circuit 7 can detect the value of the corresponding pressure P by determining which of the detection units 17 _{1 to} 17 ₃ detects a change in electrical resistance.

  Thus, according to the pressure detection device 1 according to the present embodiment, as the pressure detection element 3, the pair of planar conductive members 11 and 13 come into contact with each other through the plurality of through holes formed in the spacer. Since the contact resistance type planar switch 3A for detecting pressure is used to detect a change in resistance due to the contact of two conductive members of the planar switch, a planar switch and a detection circuit having a simple structure are used. It becomes possible to detect the magnitude of the pressure stepwise.

  Furthermore, since the conductive fibers, particularly conductive polyvinyl alcohol fibers containing conductive fine particles are used as the planar conductive members 11 and 13, the conductive layer can be broken or peeled even during bending or washing. Occurrence can be effectively prevented, and high reliability can be exhibited even when used in applications that utilize cloth such as clothes.

  The number of planar switches 3A constituting the cloth-like pressure sensor 5 may be set as appropriate according to the required pressure detection specifications. In this embodiment, the cloth-like pressure sensor 5 of the pressure detection device 1 is configured by laminating a plurality of contact resistance type planar switches 3A in the facing direction X. As shown in FIG. A plurality of planar switches 3A may be arranged side by side in the surface direction of the planar switch 3A. If the area in the surface direction of each planar switch 3A is set to be sufficiently smaller than the assumed contact area with the outside when the pressure P is applied, the pressure P is large even if arranged in this way. This can be detected in a plurality of stages.

As a modification of the first embodiment, as shown in FIG. 4, instead of the contact resistance type planar switch 3 </ b> A, a planar first conductive member 11 and a second conductive member 13 facing each other are provided. Capacitor-type planar switches 3B (3B _{1 to} 3B ₃ ) configured by interposing spacers 15B formed of a dielectric material between them can also be used as the pressure detection element 3.

  In this modification, when the pressure P is applied in the facing direction X, the spacer 15B of the planar switch 3B is deformed, whereby the first conductive member 11 and the second conductive member functioning as a capacitor plate. The distance D between the members 13 changes. As the distance between the electrode plates D changes, the capacitance of the planar switch 3B as a capacitor changes. Therefore, when the capacitance reaches a predetermined value, it is detected that a predetermined pressure is applied. .

  As shown in the block diagram of FIG. 5, the cloth-like pressure sensor 5 in this modification is configured as an oscillation circuit 21 including a capacitor-type planar switch 3B, and the change in the capacitance of the planar switch 3B is as follows. This is detected by the detection circuit 7 as a change in the oscillation period of the oscillation circuit 21.

  The oscillation circuit 21 when the capacitor-type planar switch 3B is used as the pressure sensing element 3 is particularly capable of switching by detecting the capacitance change of the planar switch 3B due to the change in the distance D between the electrode plates. Although not limited, a relaxation type oscillation circuit is preferable from the viewpoint of simple configuration and easy realization of a low oscillation frequency.

  As shown in FIG. 5, the relaxation oscillation circuit 21 includes a planar switch 3 </ b> B, a time constant circuit 23 using a resistor R, a comparator 25, and a charge / discharge switch 27. In FIG. 5, one terminal attached to the planar switch 3 </ b> B is grounded, and the other terminal is connected to the power source W through a resistor R.

  The current from the power source W is charged to the planar switch 3B as a capacitor through the resistor R, and the voltage at the point S between the time constant circuit 23 and the comparator 25 increases. When the voltage at point S reaches the reference voltage Vref (V) of the comparator 25, the comparator 25 turns on the charge / discharge switch 27. As a result, the current charged in the planar switch 3B is discharged all at once, and the voltage at the S point becomes equal to or lower than the reference voltage Vref. At this time, the charge / discharge switch 27 is turned off by the comparator 25, and charging of the capacitor starts again.

  In the relaxation oscillation circuit, the oscillation state is continued by repeatedly charging and discharging the capacitor in this manner. When the capacitance of the capacitor increases, the time until it reaches Vref (V) increases and the oscillation cycle becomes longer. Conversely, when the capacitance decreases, the oscillation cycle becomes shorter. Therefore, by measuring this oscillation cycle by the detection circuit 7, it is possible to detect a change in the capacitance of the capacitor, and as a result, it is possible to perform the switching operation of the detection circuit.

  For example, when the pressure in the facing direction X is applied to the conductive members 12 and 13 in FIG. 1, the spacer is deformed by the pressure, the distance D between the electrode plates is shortened, and the capacitance of the capacitor is changed. The capacitance change of the capacitor is reflected in the length of the oscillation cycle, and the change in the oscillation cycle is measured by the detection circuit 7. When the period measured by the detection circuit 7 exceeds a preset threshold, the detection circuit 7 finally outputs an output for turning on the detection circuit. The detection circuit 7 may use a microcomputer or a general-purpose IC depending on the required performance.

Pressure detection sensitivity between the planar switch 3B1~3B3 plurality (three in this modification), for example, by forming the spacer _15B 1 _{~15B 3} is a dielectric material different, set to different values be able to.

  FIG. 6 is a schematic diagram showing the configuration of the pressure detection device 1 according to the second embodiment of the present invention. In the pressure sensing device 1 according to the first embodiment shown in FIG. 1, the second embodiment is configured by a single capacitor-type pressure sensing element 3 </ b> C instead of the cloth pressure sensor 5 being composed of a plurality of pressure sensing elements 3. ing.

  The capacitor-type pressure sensing element 3C in FIG. 6 has the same structure as the capacitor-type planar switch 3B used in the modification of the first embodiment shown in FIG. Also in this embodiment, similarly to the modification of FIG. 4, the oscillation circuit 21 including the pressure detection element 3 </ b> C that is a capacitor is configured as the cloth pressure sensor 5, and the change in the oscillation cycle of the oscillation circuit 21 is changed. Detection is performed by the detection circuit 7.

  However, the capacitor-type planar switch 3B in FIG. 4 functions as a switch for detecting whether or not a predetermined electric capacity value corresponding to a predetermined electrode plate distance D has been reached. The detection element 3C directly detects a change in capacitance according to a change in the distance D between the electrodes due to the deformation of the spacer 15C when pressure is applied, directly at a plurality of stages or continuously by the detection circuit 7. By doing so, the value of the pressure P is detected in a plurality of stages or continuously.

  That is, a correlation characteristic between the applied pressure and the oscillation period is prepared in advance in the detection circuit 7 for a capacitor having a specific configuration by measurement or the like, and the oscillation of the oscillation circuit 21 actually detected in the detection circuit 7 is prepared. By comparing the period with this correlation characteristic, the pressure value can be detected.

  According to the pressure detection device 1 according to the present embodiment, the magnitude of the pressure applied by detecting the capacitance of the capacitor that changes according to the deformation of the spacer, that is, the change in the distance between the pair of planar conductive members. Thus, it is possible to detect not only stepwise but also continuously. Furthermore, also in this embodiment, conductive fibers, in particular, conductive polyvinyl alcohol-based fibers containing conductive fine particles are used as the planar conductive members 11 and 13, so that they are conductive even in bending and washing. It is possible to effectively prevent the layer from being broken or peeled off, and high reliability can be exhibited even when it is used for an application using a cloth such as clothes.

  Below, the raw material which can be used for each component of the pressure detection apparatus 1 which concerns on the said 1st and 2nd embodiment is demonstrated in detail.

(Conductive member)
The conductive member includes, for example, at least conductive polyvinyl alcohol-based fibers (hereinafter sometimes referred to as conductive PVA-based fibers) containing conductive fine particles. The conductive member may be formed only from conductive PVA-based fibers, or may be formed from conductive PVA-based fibers and fibers other than conductive PVA-based fibers (insulating fibers). The insulating fiber may be an organic fiber (eg, natural fiber, chemical fiber, etc.), or may be an inorganic fiber (eg, lock fiber, glass fiber, etc.).

  Examples of natural fibers include animal fibers (for example, silk, visas, wool, mohair, angora, cow hair, etc.), plant fibers [for example, cotton (for example, cotton, linter, etc.), hemp (for example, cannabis, flax) , Jute, manila hemp, sisal, etc.), kapok, bamboo, kenaf, coconut, etc.].

  Examples of chemical fibers include synthetic fibers [eg, polyvinyl alcohol fibers (eg, polyvinyl alcohol fibers, ethylene-vinyl alcohol fibers, polyvinyl acetal fibers, etc.), polyester fibers (eg, polyethylene terephthalate fibers, polytrimethylene terephthalate fibers). , Polybutylene terephthalate fiber, etc.), polyamide fiber (eg, aliphatic nylon fiber, aromatic nylon fiber, etc.), acrylic fiber (eg, polyacrylonitrile fiber, acrylonitrile-acrylate fiber, acrylonitrile-methacrylate fiber, acrylonitrile) -Vinyl acetate fibers, etc.), polyolefin fibers (eg, polypropylene fibers, polyethylene fibers, polytetrafluoroethylene fibers, etc.), poly salts Vinyl fibers, polyvinylidene chloride fibers, polyurethane fibers, etc.], regenerated fibers (eg, cellulose derivative fibers such as rayon, cupra, modal, lyocell; chitin, collagen, alginic acid, etc.), semi-synthetic fibers (eg, cellulose acetate, cellulose triacetate) Etc.).

  These fibers can be used alone or in combination. Among these insulating fibers, organic fibers are preferable from the viewpoint of flexibility and flexibility, and for example, polyester fibers, polyamide fibers, polyacrylonitrile fibers, and the like are preferable.

  The ratio of the conductive PVA fiber and the insulating fiber is not particularly limited as long as the fiber structure exhibits conductivity. For example, as the conductive PVA fiber / insulating fiber (part by weight), 50/50 to 100 / 0, preferably about 60/40 to 95/5, and more preferably about 70/30 to 90/10.

  In the present invention, the fineness of the conductive PVA fiber and the insulating fiber is not particularly limited. For example, the fineness is about 0.1 to 100,000 dtex, preferably about 0.3 to 50,000 dtex, more preferably, It may be about 1 to 10,000 dtex.

  The shape of the conductive member can be freely set according to the shape fixed to the capacitor spacer, and may be any one of a one-dimensional structure, a two-dimensional structure, and a three-dimensional structure. Of these shapes, a one-dimensional structure and a two-dimensional structure are preferable from the viewpoints of flexibility and bending resistance. These conductive members can be produced in a predetermined shape by a known or conventional method.

  For example, when the conductive member is a one-dimensional structure, the one-dimensional structure includes, for example, a filamentous material (for example, single yarn, double yarn, alignment yarn, filament yarn, triplet yarn, spun yarn, etc.), string shape For example, a braided string, a twisted string, a braided string, a braided string, a rope, etc. When these one-dimensional structures are fixed to the capacitor spacer, the shape of the one-dimensional structure does not have to be a straight line, and may have a curved portion or a branched portion. Also good.

  For example, when the conductive member is a one-dimensional structure and has a comb shape formed from a plurality of comb teeth protruding in the same direction and a base connecting the comb teeth, the conductive member protrudes from the base. The number of comb teeth may be about 1 to 10 rows, preferably about 2 to 8 rows.

  When the conductive member is a one-dimensional structure, for example, the diameter of the conductive member can be appropriately selected from a wide range of about 0.01 mm to 10 mm depending on the purpose of use. For example, comfort as clothing is good. From the viewpoint of satisfying both the electrical conductivity and the conductive performance, the diameter of the conductive member may be about 0.03 mm to 5 mm, preferably about 0.1 mm to 3 mm, and more preferably about 0.5 mm to 2 mm.

  When the conductive member is a two-dimensional structure, the two-dimensional structure may be a fabric [for example, a woven fabric (for example, a plain woven fabric, a twill woven fabric, a satin woven fabric, etc.), a knitted fabric (for example, a weft knitted fabric, a warp knitted fabric, Flat knitted fabrics, tengu knitted fabrics, lace knitted fabrics, etc.], non-woven fabrics (for example, dry non-woven fabrics, wet non-woven fabrics, etc.)], strips, and the like.

  When the conductive member is a two-dimensional structure, for example, the thickness of the conductive member can be appropriately selected from a wide range of about 0.01 mm to 1 cm depending on the purpose of use. Since the conductive PVA fiber is used, even if the thickness of the conductive member is, for example, about 0.03 mm to 5 mm (preferably about 0.1 mm to 3 mm, more preferably about 0.3 mm to 2 mm). Both flexibility and electrical conductivity can be achieved.

  When the conductive member is a strip-shaped conductive band, the width of each conductive band may be, for example, about 1 mm to 10 cm, preferably about 5 mm to 7 cm, and more preferably about 1 cm to 5 cm.

(Conductive polyvinyl alcohol fiber)
The conductive PVA-based fiber contains conductive fine particles. Examples of the conductive fine particles include various metals (metal simple substance, metal oxide, metal sulfide, etc.), graphite and the like. Among these conductive fine particles, a metal sulfide, particularly copper sulfide (for example, monovalent copper sulfide or divalent copper sulfide) is preferable from the viewpoint of bonding with polyvinyl alcohol fibers.

  The average particle diameter of the conductive fine particles is preferably 500 nm or less from the viewpoint of fine dispersion inside the fiber. For example, the average particle size of the conductive fine particles is 400 nm or less (for example, about 1 nm to 400 nm), preferably 300 nm or less (for example, about 5 nm to 200 nm), more preferably 100 nm or less (for example, about 7 nm to 50 nm). May be. The copper sulfide fine particles in the conductive PVA fiber can be confirmed with a transmission microscope (TEM).

  By using such fine particles, the distance between particles in the fiber can be remarkably reduced, and high conductivity can be expressed with a small amount. For example, it is known that when the particle diameter becomes 1/100 at the same content by weight, the inter-particle distance becomes as small as 1 / 10,000. In such a case, it is also known that the interaction between particles works very strongly, and the polymer molecules sandwiched between them show functions similar to those of conductive particles (size effect) [for example, See the world of nanocomposites, p22 (Industry Research Committee)]. Therefore, this size effect makes it easier for current to flow inside the fiber, and even a small amount can give excellent conductivity, and therefore a capacitor using such a fiber exhibits excellent sensing characteristics. To do.

  Furthermore, since such fine particles are normally finely dispersed not only in the surface layer of the fiber but also in the fiber, a strong conduction path can be formed inside the fiber. By forming such a conduction path, the conductive PVA fiber can achieve high conductivity even though it is a fiber. That is, the conductive PVA fiber can be compatible with the flexibility and conductivity of the fiber itself, unlike the metal plated fiber or the metal fiber. In the present invention, the surface layer of the fiber means a depth range of about 1 μm from the fiber surface, and the inside of the fiber means a range from the surface of the fiber to the center of the fiber.

  In addition, in the conductive PVA-based fiber, since the integrity of the fiber body and the conductive fine particles is high, the volume specific resistance value of the fiber hardly changes even when a compressive force is repeatedly applied. Furthermore, since the conduction path is not broken even when a load such as bending or washing is applied, the capacitor of the present invention can be provided with bending resistance and washing resistance.

  That is, the conductive PVA fiber used in the present invention does not cause breakage or peeling of the conductive layer during bending or washing, and can maintain stable performance with repeated use. Furthermore, compared with metal plating fiber and metal fiber, it is excellent in air permeability, a softness | flexibility, and a texture.

  The conductive PVA fibers used in the present invention can be used in any form such as short fibers (for example, staple fibers and shortcut fibers) and long fibers (for example, filament yarns such as monofilaments and multifilaments). Such a fiber can be processed into a predetermined shape such as a thread or a fabric by a known or conventional method, and can impart excellent conductivity and bending resistance.

The volume specific resistance value of the conductive PVA fiber is, for example, about 1 × 10 ³ to 1 × 10 ⁻² Ω · cm, preferably about 5 × 10 ^{2 to} 5 × 10 ⁻² Ω · cm, and more preferably 1 It may be about × 10 ² to 1 × 10 ⁻¹ Ω · cm. The volume specific resistance value is measured by the method described later. If the volume specific resistance value is too large, there are cases where good sensing characteristics cannot be obtained, such as insufficient conductivity and malfunction. Further, if the volume specific resistance value is too small, there is a risk of short circuit due to overcurrent.

  Further, in the conductive PVA-based fiber, the variation rate of the volume resistivity value before and after performing the bending resistance test (load 1.5 kgf; 1000 times) based on JIS P 8115 is, for example, within about 50%, preferably It may be within about 40%, more preferably within about 30%. If the variation rate of the volume resistivity value is too high, not only will the sensor malfunction, but it will not be possible to develop stable sensing characteristics due to repeated use, resulting in poor reliability.

(PVA polymer)
The PVA polymer that forms the conductive PVA fiber used in the capacitor of the present invention is not particularly limited as long as it has a vinyl alcohol unit as a main component. You may have a unit (denaturation unit). Examples of such a structural unit include olefins (for example, ethylene, propylene, butylene, etc.), acrylic acids (for example, acrylic acid and salts thereof, acrylic esters such as methyl acrylate, etc.), methacrylic acids (for example, Methacrylic acid and salts thereof, methacrylic acid esters such as methyl methacrylate), acrylamides (for example, acrylamide, N-methylacrylamide, etc.), methacrylamides (for example, methacrylamide, N-methylol methacrylamide, etc.), N -Vinyl lactams (for example, N-vinyl pyrrolidone, etc.), N-vinyl amides (for example, N-vinyl formamide, N-vinyl acetamide, etc.), vinyl ethers (for example, allyl ethers having a polyalkylene oxide in the side chain, Mechi Vinyl ether), nitriles (e.g., acrylonitrile, etc.), halogenated vinyl compound (vinyl chloride), unsaturated dicarboxylic acids (e.g., maleic acid and salts or anhydrides or esters thereof) and the like. These denaturing units can be used alone or in combination. Such a modified unit may be introduced by copolymerization or post-reaction.

  The ratio (molar ratio) of the modified unit to the vinyl alcohol unit is (vinyl alcohol unit) / (modified unit) = about 85/15 to 100/0, preferably about 88/12 to 99/1, and more preferably 90 / It is about 10 to 98/2. Of course, as long as the effect of the present invention is not impaired, addition of a flame retardant, an antioxidant, an antifreezing agent, a pH adjusting agent, a concealing agent, a coloring agent, an oil agent, a special functional agent, etc. in the polymer depending on the purpose. An agent may be included. These additives may be included alone or in combination.

  The degree of polymerization of the PVA polymer constituting the conductive PVA fiber can be appropriately selected according to the purpose and is not particularly limited. However, considering the mechanical properties and dimensional stability of the obtained fiber, a 30 ° C. aqueous solution The average degree of polymerization obtained from the viscosity of about 1200 to 20000 (preferably about 1500 to 15000, more preferably about 2000 to 10,000) is desirable. The use of a polymer having a high degree of polymerization is preferable because it is excellent in terms of strength, heat and humidity resistance, and the like, but in many cases, the average degree of polymerization is 1500 to 5000 from the viewpoint of polymer production cost and fiberization cost.

  Further, the degree of saponification of the PVA polymer can be appropriately selected according to the purpose and is not particularly limited. However, from the viewpoint of the mechanical properties of the obtained fiber, for example, 88 mol% or more, preferably 90 mol% or more. More preferably, it may be 95 mol% or more. If the degree of saponification of the PVA polymer is too low, it is often not preferable in terms of mechanical properties, process passability, production cost, and the like of the obtained fiber.

  The conductive PVA fiber of the present invention can be obtained by a known or conventional method. For example, the conductive PVA fiber in which copper sulfide is finely dispersed is used in a normal PVA fiber manufacturing process. It can be obtained by impregnating a compound containing copper ions in the fiber and subjecting copper to sulfuration treatment in the subsequent step.

In order to obtain conductive PVA fibers, first, a spinning stock solution in which a PVA polymer is dissolved in a solvent is prepared.
As the solvent for the spinning dope, various polar solvents can be used. For example, water, organic solvents [sulfoxides such as dimethyl sulfoxide (hereinafter referred to as DMSO); nitrogen such as dimethylacetamide, dimethylformamide, N-methylpyrrolidone, etc. Containing polar solvents; polyhydric alcohols such as glycerin and ethylene glycol], and mixtures thereof with swellable metal salts such as rhodan salts, lithium chloride, calcium chloride, and zinc chloride. These solvents can be used alone or in combination. Among these, water and DMSO are preferable in terms of process passability such as cost and recoverability.

  The polymer concentration in the spinning dope varies depending on the composition, polymerization degree, and solvent, but is preferably about 8 to 60% by weight (preferably about 10 to 50% by weight), for example. The liquid temperature at the time of discharging the spinning dope is preferably in a range in which the spinning dope is not decomposed or colored, and specifically 50 to 200 ° C. is preferable.

  The obtained spinning dope is usually discharged from a nozzle into a solidified liquid having a solidifying ability with respect to the PVA polymer or a gas. Examples of the spinning method include wet spinning, dry wet spinning, and dry spinning. Wet spinning is a method in which a spinning stock solution is discharged directly from a spinning nozzle into a solidification bath, and dry and wet spinning is a method in which a spinning stock solution is temporarily placed in air or inert gas at an arbitrary distance from the spinning nozzle. It is a method of discharging and then introducing into the solidification bath. Dry spinning is a method of discharging a spinning solution into air or an inert gas.

  In the present invention, the solidification bath used in wet spinning or dry wet spinning differs depending on whether the stock solvent is an organic solvent or water (or an aqueous solution). In the case of a stock solution using an organic solvent, it is preferably a mixed solution composed of a solidification bath solvent and a stock solution solvent from the viewpoint of fiber strength and the like obtained, and the solidification solvent is not particularly limited, but for example, methanol, ethanol, An organic solvent capable of solidifying PVA-based polymers such as alcohols such as propanol and butanol, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone can be used. Among these, a combination of methanol and DMSO is preferable in terms of low corrosivity and solvent recovery. On the other hand, when the spinning dope is an aqueous solution, the solidification solvent constituting the solidification bath is not particularly limited as long as it has a solidification ability with respect to the PVA polymer, and examples thereof include inorganic substances such as sodium sulfate (sodium sulfate), ammonium sulfate, and sodium carbonate. An aqueous salt solution; an aqueous sodium hydroxide solution or the like can be used. Further, an aqueous solution in which boric acid or the like is added together with a PVA polymer can be gel-spun in an alkaline solidification bath.

  Next, in order to extract and remove the solvent of the spinning dope from the solidified yarn, it is passed through an extraction bath. At this time, when the raw yarn is wet-drawn simultaneously with the extraction, it is preferable from the viewpoint of suppressing the sticking between the fibers during drying and improving the mechanical properties of the fibers. In this case, the wet draw ratio is preferably 2 to 10 times in terms of processability and productivity. As the extraction solvent, a solidified solvent alone or a mixed solution of a stock solvent and a solidified solvent can be used. The wet-drawn yarn may be further subjected to dry heat drawing and heat treatment after drying. Drawing is preferred because the degree of crystallinity and orientation of the fiber is increased, and the mechanical properties of the fiber can be significantly improved.

  Stretching can be performed by known or conventional means, for example, at 100 ° C. or higher (preferably about 150 ° C. to 260 ° C.). If the temperature is too low, whitening of the fiber will occur, which will result in a decrease in mechanical properties. On the other hand, if the temperature is too high, partial melting of the fiber occurs, and in this case, mechanical properties are deteriorated. Further, the stretching ratio may be a total stretching ratio of 3 times or more (preferably about 5 to 25 times). In addition, the total draw ratio here is a product of the wet draw in the solidification bath before drying described above and the draw ratio after drying. For example, when the wet stretching is 3 times and the subsequent dry heat stretching is 2 times, the total stretching ratio is 6 times.

  In the conductive PVA-based fibers, the swollen yarns after wet drawing or the yarns after drying or drawing are passed through a bath in which a compound containing copper ions is dissolved to impregnate the compound into the fibers. . In this case, in order to uniformly penetrate the compound containing copper ions into the fiber and coordinate bond the copper ion and the hydroxyl group of the PVA polymer, the fiber needs to be swollen by a bath solvent. . Therefore, the solvent used in the bath is preferably an alcohol such as methanol, water, an aqueous solution such as a salt, or a mixture thereof.

  The swelling ratio of the fibers by the bath solvent is preferably 20% by mass or more (preferably about 30% to 300% by mass, more preferably about 50% to 250% by mass). In order to adjust the swelling rate, it may be desirable to first immerse Yinshino in a predetermined bath and then immerse in a bath in which a compound that releases copper ions is dissolved. If the swelling ratio is too small, copper ions cannot form a sufficient coordination bond with the hydroxyl group of the PVA polymer, and therefore copper sulfide nanoparticles cannot be formed inside the fiber. On the other hand, when the swelling rate becomes too large, elution of the PVA polymer into the bath occurs, which is not preferable in terms of process passability.

  Next, for the purpose of subjecting the copper ions coordinated in the PVA fibers to a sulfidation reduction treatment, the copper ions are passed through a bath in which a compound containing sulfide ions is dissolved. In that case, the amount of the compound containing sulfide ions added to the bath may be appropriately set depending on the amount of copper ions introduced, and is, for example, about 1 to 100 g / L (preferably 10 to 90 g / L). Or about 20 to 80 g / L). If the amount added is too small, the reduction treatment may not proceed to the copper ions inside the fiber, which is not preferable. Moreover, when there is too much addition amount, although it is an amount sufficient for carrying out the reduction process of the copper ion contained in a PVA-type fiber, it is not much preferable in terms of process property, such as a collection system and an odor problem.

  The reaction to sulfidize the copper ions impregnated in the fiber occurs instantaneously, especially when a compound having a high sulfidation-reducing ability is used. For the purpose of performing a reduction treatment, the residence time is desirably 0.1 seconds or longer. In addition, in the step of impregnating the copper ions described above, the step of sulfiding the copper ions in the fiber here, irradiating ultrasonic waves of a specific frequency is advantageous in securing the obtained conductivity and quality. Sometimes.

  Further, the physical properties of the fiber can be improved by heat-treating the raw yarn or drawn yarn in which the copper sulfide nanoparticle is introduced into the fiber thus obtained. The heat treatment is generally performed at a temperature of 100 ° C. or higher, preferably about 150 ° C. to 260 ° C. If the temperature is too low, the effect of improving the physical properties of the fiber is insufficient. On the other hand, if the temperature is too high, partial melting of the fiber occurs, and even in this case, the mechanical properties are lowered.

[Contact resistance type planar switch spacer]
The planar flexible spacer is insulative and has a through-hole. When the first and second conductive members respectively disposed on both sides of the spacer are in a non-contact state, the conductive flexible spacers Prevents conduction. When the sensor receives a compressive force, the first and second conductive members come into contact through the through holes of the spacer, and these conductive members are conducted. In the present invention, since a specific conductive PVA fiber is used for the conductive member, it is not necessary to use a deformed conductive woven or knitted fabric or the like as the spacer. That is, even if there is no conductive object inside the spacer, conduction between the conductive members is possible.

  Such a soft spacer is not particularly limited as long as a through-hole can be provided by a known or conventional method. For example, a fabric (for example, a fabric formed of insulating fibers exemplified in the section of the conductive member or Knitted fabric), rubber, soft foam (for example, soft urethane foam) and the like.

  The rubber forming the spacer includes natural rubber, synthetic rubber (for example, isoprene rubber (IR), butadiene rubber, styrene / butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene / propylene rubber, silicone rubber), thermoplasticity. Examples include elastomers (TPE) (for example, styrene-based TPE, olefin-based TPE, vinyl chloride-based TPE, urethane-based TPE, polyester-based TPE, and polyamide-based TPE). These soft spacers not only do not hinder the contact of the conductive member due to compressive force, but also have excellent bending resistance. Of these soft spacers, a fabric is preferable from the viewpoint of having washing resistance.

  As described above, the fabric can be formed using various insulating fibers exemplified in the section of the conductive member. For example, from the viewpoint of insulation, synthetic fibers (for example, polyester fibers, acrylic fibers, polyolefin fibers) Etc.) is preferable.

  In order to secure both the insulating state between the conductive members and the conductive state due to the contact of these fabrics, the size (hole diameter) of the through hole of the spacer can be appropriately selected according to the thickness of the spacer body. For example, the hole diameter of the spacer is about 0.1 mm to 3 cm, preferably about 0.5 mm to 2 cm, and more preferably about 1 mm to 1 cm. In many cases, the spacer usually has a plurality of through holes. When the spacer is a fabric, it may be a coarse woven or knitted fabric having an opening of about 0.1 mm to 1 cm, preferably about 0.5 mm to 5 mm, more preferably about 1 mm to 3 mm, instead of the hole diameter. .

  The thickness of the spacer is not particularly limited as long as both the insulation state between the conductive members and the conduction state due to the contact of these fiber structures can be secured, but for example, about 0.1 mm to 1 cm, preferably 0.2 mm to It may be about 5 mm, more preferably about 0.3 mm to 3 mm.

Furthermore, the spacer may have not only a specific thickness and a hole diameter but also a specific basis weight (weight per unit area). For example, in the case of a fabric, the basis weight is about 5 to 200 g / m ^2. The weight may be about 10 to 150 g / m ² , more preferably about 15 to 100 g / m ^{2. In} the case of rubber, the basis weight is about 10 to 300 g / m ² , preferably about 30 to 200 g / m ^2. More preferably, it is about 50 to 100 g / m ^{2. In} the case of a soft foam, the basis weight is about 5 to 200 g / m ² , preferably about 10 to 150 g / m ² , more preferably about 30 to 100 g / m ^2. May be.

(Capacitor spacer)
The spacer used in the capacitor-type pressure sensing element (capacitor-type planar switch) of the present invention is formed of a dielectric, and the conductive members are fixed to predetermined positions of the spacer by sewing or bonding without contacting each other. ing.

  The relative dielectric constant of the capacitor spacer is not particularly limited as long as the conductive member can form a capacitor. For example, the relative dielectric constant may be about 1 to 100, and preferably about 2 to 50. .

  The shape of the capacitor spacer can be appropriately changed according to the shape of the conductive member, and is not particularly limited. Further, when the conductive member is disposed on both sides of the capacitor spacer, the spacer does not have a through hole for contacting the paired conductive members.

  For example, as the capacitor spacer, a dielectric fabric or a sheet can be used. In addition, from the viewpoint of excellent integral moldability, the capacitor spacer may be an adhesive layer that bonds the conductive members existing on both sides of the spacer. In the present invention, when the adhesive layer is present between the conductive members in a sheet form in the capacitor, the adhesive layer is included in the category of the dielectric sheet.

  For example, as a dielectric fabric used as a capacitor spacer, various natural fibers (for example, animal fibers and plant fibers), chemical fibers (for example, synthetic fibers and semi-synthetic fibers) described in the section of the conductive member are used. Examples thereof include woven and knitted fabrics and nonwoven fabrics formed by known or conventional methods.

In addition, examples of the dielectric sheet used as the capacitor spacer include sheets formed from various resins (preferably soft resins) and rubber by a known or conventional method.
Examples of the soft resin include polyolefin resins (eg, polyethylene, polypropylene, polymethylpentene, ethylene vinyl acetate copolymer, etc.), ionomer resins, polyvinyl alcohol resins (eg, polyvinyl alcohol, ethylene-vinyl alcohol copolymer). Etc.), polyester resins (eg, polyethylene terephthalate, polybutylene terephthalate, etc.), styrene resins (eg, polystyrene, etc.), chlorine resins (eg, polyvinyl chloride, polyvinylidene chloride, etc.), polyamide resins (eg, Polyamide 6, polyamide 66, polyamide 610, etc.), cellulose derivatives (eg, cellophane, cellulose acetate, cellulose acetate petitate, etc.), acrylic resins (eg, poly (meta Acrylate, polymethyl (meth) acrylate, polyacrylonitrile, ethylene - methacrylic acid copolymer), polyimide resin (polyimide, polyamideimide, polyetherimide, etc.), polycarbonate resins, polystyrene resins.

  Examples of rubber include natural rubber, synthetic rubber (eg, isoprene rubber (IR), butadiene rubber, styrene / butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene / propylene rubber, silicone rubber, etc.), thermoplastic elastomer ( TPE) (for example, styrene TPE, olefin TPE, vinyl chloride TPE, urethane TPE, polyester TPE, polyamide TPE, etc.).

  The thickness of the capacitor spacer is not particularly limited as long as it can be appropriately set according to the arrangement mode of the conductive member and can sufficiently insulate the conductive member and exhibit the function as a capacitor. For example, it may be about 0.1 mm to 1 cm, preferably about 0.2 mm to 5 mm, more preferably about 0.3 mm to 3 mm.

  As described above, the preferred embodiments of the present invention have been described with reference to the drawings, but various additions, modifications, or deletions can be made without departing from the spirit of the present invention. Therefore, such a thing is also included in the scope of the present invention.

It is a disassembled perspective view which shows schematic structure of the pressure detection apparatus which concerns on 1st Embodiment of this invention. It is a disassembled perspective view which shows the planar switch used for the pressure detection apparatus of FIG. In the pressure sensing device concerning a 1st embodiment of the present invention, it is a schematic diagram showing the example which arranged the field switch along the field direction. It is a disassembled perspective view which shows schematic structure of the planar switch used for the modification of 1st Embodiment of this invention. It is a block diagram which shows the circuit structural example of the pressure detection apparatus which concerns on the modification of FIG. It is the schematic which shows the structure of the pressure detection apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure detection apparatus 3 Pressure detection element 5 Cloth-like pressure sensor 7 Detection circuit 11 1st electroconductive member 13 2nd electroconductive member 15 Spacer X Opposite direction of electroconductive member

Claims (10)

A cloth-like pressure sensor having one or a plurality of pressure sensing elements, each comprising a pair of opposed planar conductive members formed of conductive fibers and a flexible planar spacer interposed between the conductive members; ,
A detection circuit that detects the magnitude of pressure in the opposing direction of the pair of conductive members in a plurality of stages according to the degree of deformation of the spacer of the pressure detection element;
A pressure sensing device comprising:   2. The pressure detection device according to claim 1, wherein the conductive fiber is a conductive polyvinyl alcohol fiber containing conductive fine particles.   The pressure detection apparatus according to claim 1 or 2, wherein the cloth-shaped pressure sensor includes a plurality of the pressure detection elements having different detection sensitivities.   The pressure detection device according to claim 3, wherein the cloth-like pressure sensor is formed by laminating the plurality of pressure detection elements in a direction opposite to the conductive member.   5. The pressure detection device according to claim 3, wherein the pressure detection element is formed in the spacer through a plurality of through holes penetrating in a facing direction of the pair of planar conductive members. A pressure detection device that is a contact resistance type planar switch that detects pressure when conductive members are in contact with each other.   6. The pressure detection device according to claim 5, wherein the plurality of planar switches are provided with spacers made of different materials, so that the pressure detection sensitivity of each planar switch is set to a different value.   The pressure detection device according to claim 5 or 6, wherein the pressure detection sensitivity of each planar switch is set to a different value by forming a through hole having a different structure in each spacer of the plurality of planar switches. Detection device.   5. The pressure detection device according to claim 3, wherein the pressure detection element is a capacitor-type planar switch in which the spacer is formed of a dielectric material.   9. The pressure detection device according to claim 8, wherein the plurality of planar switches are provided with spacers made of different materials, so that the pressure detection sensitivity of each planar switch is set to a different value.   3. The pressure detecting device according to claim 1, wherein the cloth-like pressure sensor includes one capacitor type pressure detecting element in which the spacer is formed of a dielectric material, and the capacitance of the capacitor is changed by deformation of the spacer. A pressure detector that detects the magnitude of pressure.

Images