JPS63229340A - Compression sensor element - Google Patents

Abstract

PURPOSE:To detect a wide range of deformation with high sensitivity, by bonding an elastomer layer having a projection and a thickness of 0.3mm or more to at least the single surface of a deformable conductive sheet. CONSTITUTION:The average height of the elastomer 11 from the bonding surface with a deformable conductive sheet 12 requires 0.3mm or more and the projection 16 on the surface of the elastomer 11 is pref. becomes large in its cross-sectional area toward the bottom part thereof. An insulated leaf spring part 15 is bonded to the other surface of said conductive sheet 12. In order to detect the electric resistance value of the deformable conductive sheet 12, a copper plate 14 is adhered to the spring pair 15 by a conductive adhesive 13. By this constitution, when compression force is applied to the projection, said compression force spreads to the whole of an element and a considerable quantity of deformation can be determined based on minute deformation as the large change in a resistance value with good sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a compression sensor element. More specifically, it relates to a sensor element made of a deformable conductive sheet that can be easily and elastically compressed and deformed by an external force, and furthermore can be compressed and deformed with stretching and bending, and whose electrical resistance value decreases with the deformation. .

[Conventional technology]

Conventionally, as a method of converting compressive deformation or compressive stress into a switch-like electrical signal, there are switches that mechanically repeat contact and non-contact, such as limit switches and touch switches. However, these switches tend to suffer from poor conduction due to oxidation of contact points, and there is a limit to how they can be made smaller and thinner due to their structure.

When thin metal wires such as mata, constantun, advance, and nichrome are deformed and their condensed films are deformed, the electrical resistance value changes, and strain gauges are known as devices that take advantage of this property.

However, since the resistance value change of this type of element is extremely small, in order to extract it as an electrical signal, the circuit must be equipped with filter functions such as signal amplification and averaging.
The N ratio must be improved, resulting in a complex and high-cost circuit. In addition, the strain gauge has an extremely small deformation rate.
Since it is less than 1%, it cannot handle large compression deformation.
It cannot be used for switches with large strokes.

There are also elements using piezoelectric elements and pressure-sensitive conductive rubber. Piezoelectric elements are used to detect mechanical strain deformation and voltage changes, but like strain gauges, they require complex and high-cost circuits and are only suitable for applications involving minute deformations. Another disadvantage is that the electrical characteristics are greatly affected by humidity.

On the other hand, pressure-sensitive conductive rubber is a sheet-like element in which conductive particles are dispersed in an insulating elastomer, and has a property that the electrical resistance value decreases when the sheet is compressed in the thickness direction. However, since this type of element uses an elastomer for the matrix, the temperature drift of the resistance value is extremely large, making it unusable in environments with large temperature changes. In addition, since the resistance value changes only in the area that has been compressed and deformed, if a planar switch with a large area is formed, the electrode pattern will be complicated, and depending on the way the compression is applied, there will be disadvantages in terms of detection sensitivity, such as non-detection. There is.

As mentioned above, conventionally known elements or switches have poor durability, their electrical characteristics are affected by environments such as temperature and humidity, their detection circuits are complex and expensive, and they can only be used for small deformations. I can't. Therefore, if there is an element that can detect minute deformations to considerable amounts of compressive deformation, or compressive deformations accompanied by elongation or bending with high sensitivity, and has excellent durability,
Although it is expected that there will be a wide range of application fields, the current situation is that nothing that satisfies this has yet appeared.

[Problem that the invention seeks to solve]

The present invention provides a compression sensor element that can detect a wide range of deformations with high sensitivity, from minute deformations to compression deformations accompanied by considerable amounts of compression, elongation, and bending, which cannot be achieved using conventionally known materials. The purpose is to provide.

[Means for solving problems]

An object of the present invention is to provide a compression sensor element in which a plurality of electrodes are attached to appropriate locations on a deformed conductive sheet whose electrical resistance value changes due to compression deformation, the deformed conductive sheet being disposed between the electrodes. This is achieved by a compression sensor element characterized in that an elastomer layer having a thickness of 0.3 mm or more and provided with protrusions is bonded to at least one of its surfaces.

The first feature of the present invention is that an elastomer having a specific thickness and having protrusions is bonded to at least one side of the deformed conductive sheet.

The deformable conductive sheet referred to in Koji means that when an elongation or compression deformation action is applied, or when a deformation action such as bending or twisting accompanied by elongation or compression deformation is applied, the electrical resistance value of the knitted fabric in the deformation direction becomes 1. This refers to knitted fabrics that are reduced by more than an order of magnitude. For example, there is a sheet-like knitted fabric included in "Deformed Conductive Knitted Fabric" filed as Japanese Patent Application No. 41024 on March 4, 1985 by the same applicant as the present invention.

The present inventors have made extensive studies to use a deformed conductive sheet having such unique characteristics as a compression sensor element, and have found that if the elastomer bonded to the deformed conductive sheet has a specific thickness and protrusions, It was discovered that the sensitivity of the sensor element is improved, leading to the present invention.

The thickness of the elastomer in the present invention refers to the average height of the elastomer from the bonding surface of the elastomer and the deformed conductive sheet, and it is necessary that this is 0.3 or more. If this value is less than 0.3■■, even if a compressive force is applied to the protrusion, this force will only be transmitted to the deformed conductive sheet in the area immediately below it, and will only locally deform it. , it does not spread to the entire element.

Furthermore, the term "protrusion" used in the present invention refers to a protrusion that protrudes from the surface of the elastomer, has an outer surface that is further away from the bonding surface between the elastomer and the deformed conductive sheet, and is substantially connected to an object that applies compressive stress to the outer surface. It suffices if it has a contact function. In addition, the shape and number of protrusions, their arrangement on the elastomer surface, and the mutual height of the protrusions are also determined by the object applying the compressive action (
It is arbitrarily set depending on the shape of the finger (for example, finger) and the desired sensitivity. In general, even if the total area of the outer surface of the protrusions is the same, the more uniformly the protrusions are arranged on the surface of the compression sensor element, the more the height and outer surface shape will be adjusted to match the surface shape of the object applying compression. The more it has, the more sensitive the compression sensor element becomes, which detects even minute compressive deformation as a change in electrical resistance.

Note that it is more preferable that the cross-sectional area of the protrusion increases toward the bottom, since this increases the area of the elastomer that is distorted. Further, the material of the protrusion does not necessarily have to be the same as the elastomer, and is preferably selected as appropriate depending on the environment of use and the external object with which it comes into contact.

Further, the elastomer having protrusions in the present invention may be any material that can be elastically deformed, but elastomers exhibiting rubber-like elasticity are particularly preferable because they are excellent in terms of durability, impact γ resistance, sensitivity, etc. , urethane rubber, silicone rubber, butadiene rubber, isoprene rubber, etc. In addition, when bonding the elastomer to the deformed conductive sheet, it is necessary to have uniform physical adhesion to the deformed conductive sheet, and furthermore, the compressive stress applied to the elastomer is inhibited at the bonding surface and the deformed conductive sheet is Therefore, it is preferable that the adhesive used for bonding has rubber elasticity, or the elastomer itself to be bonded is used as the adhesive.

When an elastomer having protrusions is bonded to at least one side of the deformable conductive sheet, compressive stress applied from the outside to the outer surface of the protrusions is transmitted to the bottom of the protrusion, which has a larger cross-sectional area, and the Since the elastomer in the vicinity is uniformly strained, the applied compressive strain is amplified and transmitted to the deformed conductive sheet. The deformed conductive sheet is made of a knitted fabric and forms a two-dimensionally expanded structure. Therefore, the strain applied to a part of the deformed conductive sheet is perceived two-dimensionally in the in-plane direction as tissue deformation of the knitted fabric (including the tightness of the yarns themselves and each other), and is therefore amplified by the elastomer. When strain is transmitted to the deformed conductive sheet, the electrical resistance value changes with higher sensitivity. If the elastomer does not have protrusions, there will be no distortion amplification effect, and the detection sensitivity will be correspondingly lower.

In particular, when the electrode end portion is installed in the in-plane direction of the deformed conductive sheet, the sensitivity is lower than when there is a protrusion.

In addition, when an elastomer having protrusions is bonded to only one side of the deformed conductive sheet, an elastomer having a flat surface such as the silicone rubber mentioned above or a plate-like material is bonded to the other side. Bonding is preferable because the compression sensor element has excellent durability and environmental resistance such as heat resistance and moisture resistance. Note that the plate-shaped objects mentioned here include materials with high toughness, such as metals with an insulating coating on the surface (e.g., phosphor bronze and helium copper), and plastic materials with high rigidity (polyacetal, polycarbonate, nylon 66, chloride). (vinyl, fluororesin, etc.), various FRP
(For example, combinations of reinforcing fibers such as glass fibers, carbon fibers, aramid fibers, or fiber fabrics with epoxy resins, unsaturated polyester resins, etc.), or all materials normally used for leaf springs, such as ceramics. Ru.

Furthermore, it is preferable to bond an elastomer having protrusions to both sides of the deformed conductive sheet, since the deformed conductive sheet is subjected to large compressive deformation accompanied by elongation and bending, resulting in higher sensitivity.

Next, the electrode ends provided on the deformed conductive sheet are usually arranged at both ends of the deformed conductive sheet.

However, one or more electrode ends may be provided in the middle of the deformed conductive sheet, or one or more electrode ends may be provided on the front and back surfaces of the sheet. In this case, by detecting a decrease in the electrical resistance value of the deformed conductive sort at any end of the electrode, it is possible to grasp the deformation behavior of the corresponding portion of the object to be measured.

That is, the ends of the electrodes for detecting the electrical resistance value of the deformed conductive sheet only need to be provided at intervals;
The position, number, shape, etc. may be appropriately selected depending on the purpose and method of use.

The electrode end can be made by applying a conductive adhesive containing a conductive substance such as nickel, copper, silver, or carbon directly onto the surface of the deformed conductive sheet by coating, transferring, screen printing, or other means. There are shapes printed, metal plates normally used as electrodes bonded with the conductive adhesive, mechanically attached with rivets, grommets, hooks, etc., and combinations of these. This list is not limited to this list.

In addition, circuits can be applied directly to the bonding surface of the elastomer or plate-like material to be bonded to the deformed conductive sheet by means such as coating with conductive adhesive, dipping, printing, transfer, screen printing, vapor deposition of metal, or pasting of metal foil. Draw (or
By attaching a flexible printed circuit film (ester film) obtained by etching or screen printing to a plate-like object, it becomes a compact and flat sensor element, making it suitable for light, thin, short and small applications such as in the electronics field.

Next, the compression sensor element of the present invention will be further explained using the drawings.

FIGS. 1a), b) to 5 show schematic diagrams of the compression sensor element of the present invention.

1a) and b) show that on one side of the deformed conductive sheet 12,
They are a sectional view and a top view of a compression sensor element in which an elastomer 11 having one protrusion is bonded, and an insulated leaf spring material 15 is bonded to a corresponding portion on the other side.

The compression sensor element in FIG. 2 differs from that in FIG. 1 in that the elastomer 21 has two protrusions.

Moreover, FIG. 3 shows a cross-sectional view of a compression sensor element in which elastomer material 1 having protrusions is bonded to both surfaces. Further, FIG. 4 shows a cross-sectional view of a compression sensor element to which an elastomer 4L1 having a flat elastomer protrusion on one side is bonded.

In addition, in the figure, 11, 21, 31, 31', 41 are elastomers having protrusions, 12, 22, 32,
42 is a deformed conductive sheet, 13, 23, 33
, 43 is a conductive adhesive, 14, 14'.

24, 34 and 44 are copper plates, 15 and 25 are leaf spring materials, 45 is a flat elastomer, and 16 is the top of the protrusion, respectively.

These products of the present invention are sensitive to small to considerable amounts of compressive deformation, elongation, and bending, as a large change in resistance value, and can be detected by an unprecedented hour wheel-type detection circuit, and are particularly sensitive to mechanical deformation. It becomes a compression sensor element with excellent durability.

These compression sensor elements of the present invention can be used in the following applications. For example, as a pedometer,
Compression sensor element of the present invention (hereinafter abbreviated as element) on shoes
A sensor that detects the number of steps taken by compressing the element as you walk, and a sensor that attaches the element to the bending part of various training equipment and equipment for the purpose of muscle strengthening, shake-up, and rehabilitation, or the human body. It is possible to detect the number of compressions involved.

In addition, by selecting the type of protrusion appropriately, it can be used as a load meter that can handle from minute stress to large stress, and by propagating the motion of an object that vibrates or accelerates to the element,
Can be used as a vibration meter or accelerometer. Furthermore, it can be used as a sensor for measuring the occlusal force of teeth to adjust the engagement of teeth, the engagement of dentures, etc.

In addition, the compressive conductivity of the element can be used to create tactile sensors for robots, non-contact switches for keyboards and handwriting input, seating detection sensors that can be used in seats to confirm seating, and window frames and handrails for crime prevention and safety purposes. It can be used for crime prevention and danger prediction sensors installed (pressure sensors such as touch sensors, danger prediction sensors for power windows of automobiles, etc.).

Industrial sensors include position control '4JII sensors for controlling the position of industrial robot hands, limit switches and microswitches, safety switches that are installed around the surrounding area to prevent robots from running out of control, and more. By placing sheet-like (mat-like) sensor elements in hazardous areas, they can be used in safety switches, etc. that detect when a worker enters the area and bring the robot to an emergency stop. Further, it can be used as a diaphragm, a pressure gauge, a sensor for detecting the expansion rate of an expanding body, a pulse meter, a blood pressure meter, and various flow rate meters (for fluids such as liquids and gases).

The sensor element of the present invention will be further specifically explained below using Examples.

〔Example〕

Polyester taffeta manufactured by Asahi Kasei Corporation (50 d
/24f, latitude 75d/36f) was subjected to weight reduction processing (iS2
PdCff 2 was made irritating in a bath with a weight ratio of 3:10 (mass ratio 20%) and SnCe z :hydrochloric acid, and after washing and dehydration with water, PdCff 2
: Hydrochloric acid was activated in a bath with a weight ratio of 1:15, and after washing and dehydration NiCA z ・6 HzO, Na1lPOz ・11
20, sodium citrate, NH4, Cl aqueous ammonia in a bath with a weight ratio of 1:1:3:2:2 at 90°C x 2
A Ni-plated ester tough fabric was prepared by performing a separate treatment. This was cut into samples with a size of 10cI]l x 10cm, and a double cylindrical laminar flow generator (inner cylinder rotates at high speed,
The mixture was placed in an outer tube with an inner diameter of 25 cm and an inner tube with an outer diameter of 10 cm together with water, and treated at an inner tube rotation speed of 200 rpm for 300 minutes to obtain a deformed conductive sheet. Next, 50% of commercially available urethane elastomer resin (solvent DMF, solid content 10vt%) was added.
After coating on release paper with pm gauge, 100'c
After drying for 5 min, the deformed conductive knitted fabric was thermally adhesively transferred to both sides of the sheet-like deformed conductive knitted fabric at 110°C with a pressure of 4 kg/cm.This was cut in the bias direction into 1cm!1 width x 5cm length, and the deformed conductive A sheet ■ was prepared.This deformed conductive sheet ■ was 1 co + width x 7 cm length x thickness 500
A printed circuit board made of a glass epoxy board (1 CT11 square 35 μm thick copper plates are laminated on both ends of a 7 cm length) with an epoxy adhesive, and 1C111 from both ends of the sheet (1) is attached to a conductive UiN i wire. Element 2 was fabricated by electrically connecting it to the copper plate of a printed circuit board using adhesive. Motoko ■
The elastomer having protrusions to be bonded to is made by pouring a commercially available silicone elastomer into the mold using a mold having a desired shape and heating it at 130°C for 1 hr to form an elastomer with an average height of II.
It was made in m. Elastomers with one and two protrusions were bonded to the surface of element (1) using a room temperature curing silicone adhesive to form samples N001 and 2 of the present invention shown in FIGS. 1 and 2.
was created. Next, as shown in Fig. 3, a deformed conductive sheet (■) and a copper plate are adhered to the opposite plane of the silicone elastomer having two protrusions using the silicone adhesive side.
A Ni-based conductive adhesive was used to electrically connect the copper plate and the sheet (1), and a silicone-based elastomer having one protrusion was bonded thereon using a silicone adhesive. Sample No. of the present invention having protrusions on both sides , got 3.

Furthermore, a flat silicone sheet with a thickness of 1 cm (1 cm
Deformed conductive sheets ■ made of silicone elastomer with different heights of protrusions (width XT cm length), protrusion heights, and outer surface shapes were used as samples No.
Sample No. 4 of the present invention was obtained by bonding in the same manner as No. 3.

As a comparative example, a thickness of 1 cm was applied to the surface of the element
Comparative Example (2) was prepared by joining silicone sheets with a width of 6clII length with a silicone adhesive.

Attach lead wires to samples Nos. 1 to 4 and comparative example ■, and measure the resistance with a digital multimeter made by Takeda Riken. We investigated the relationship between values. However, sample no.
, 4 was compressed through a curved surface, but all the others were compressed between two parallel plane metal plates. As a result, sample No. of the present invention.

All numbers 1 to 4 have a compressive stress of 100 g and a resistance value of 4 x 1.
06Ω to 1×103Ω or less, but in Comparative Example ■, even when 100g of compressive stress was applied, the decrease was only about one order of magnitude, from 4×10bΩ to I×10″′Ω. It was found that the sensitivity was excellent.

〔Effect of the invention〕

The compression sensor element according to the present invention having the above-described configuration has excellent durability against compression deformation including compression deformation, elongation, and bending deformation, and is sensitive to small deformation to considerable deformation as a large change in resistance value. Since it can be detected well, it can be used as a compression sensor element that can detect with a simple circuit, which cannot be done using conventionally known sensor elements.

[Brief explanation of drawings]

1 to 4 show schematic diagrams of embodiments of the compression sensor element of the present invention. 11.11', 21, 31.31', 41... Elastomer with protrusion≠rumor, 12, 22, 32, 42... Deformed conductive sheet, 13, 23, 33, 43... Conductive glue,
14, 14', 24, 34.44...Copper plate, 15
, 25...Temporary spring material, 45...Flat elastomer, 16...Protrusion. a) b) Figure 1 Figure 2 Figure 3 Figure Otsu 1 Figure 4

Claims (1)

[Scope of Claims] 1. A compression sensor element comprising a plurality of electrodes attached to appropriate locations on a deformed conductive sheet whose electrical resistance value changes due to compressive deformation, wherein the deformed conductive sheet between the electrodes is 0 with protrusions on at least one surface of the sheet
．． A compression sensor element characterized in that an elastomer layer having a thickness of 3 mm or more is bonded. 2. Claim 1 in which a plurality of the protrusions are present
Compression sensor element described in Section. 3. The elastomer layer is provided on only one side of the conductive sheet, and a rigid flat member is bonded to a corresponding position on the opposite side. Compression sensor element according to item 2. 4. The compression sensor element according to claim 1 or 2, wherein the elastomer layer is bonded to both sides of the conductive sheet.