JPH02304825A - Flexible planar switch - Google Patents

Abstract

PURPOSE:To obtain a planar switch as a thin, soft, and foreign material feeling free input switch by nipping a deformed conductive knitted fabric, in which an electric resistant value decreases due to deformation, into at least a partial area between two flexible conductive sheet-like electrodes. CONSTITUTION:A deformed conductive knitted fabric, that is a sensor cloth 1, in which an electric resistant value decreases due to deformation, is nipped into at least a partial area between electrodes 2 and 3 composed of two flexible conductive sheet-like substances. According to this constitution, a thin input switch having, excellent flexibility, and no hardness or feeling of physical disorder during use can be obtained, moreover performance such as flexibility, etc., can be further improved by using a cloth, thin rubber, and thin film, etc., not detracting flexibility and thinness of a planar switch as a material of cover sheets 4 and 5. Moreover a curved surface follow-up property is excellent, and an input switch can be provided even on a curved surface. Thus a thin planar switch, having excellent flexibility, neither hardness nor foreign material feeling, and good curved surface follow-up property, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a planar switch. More specifically, the present invention relates to a planar switch made of a deformed conductive knitted fabric to which compressive stress can be applied by an external force and whose electrical resistance value decreases as the compressive deformation occurs due to the stress.

[Conventional technology]

In recent years, there has been a demand for input switches that are thin, soft, and do not give the impression of a foreign body, mainly in the medical field, biometric sensors, industrial seating sensors, home appliance fields, and toy fields. However, ordinary mechanical switches are hard, have poor flexibility, and feel like a foreign body, and do not satisfy the requirements.

Further, pressure-sensitive conductive rubber is a material whose electrical resistance value decreases by compression deformation. Pressure-sensitive conductive rubber is made by kneading and dispersing metal particles such as carbon black or Nikkenope silver as conductive particles in an insulating elastomer such as silicone rubber or urethane rubber. Before compressive stress is applied, the metal particles are separated from each other and are almost electrically insulated, but when compressive stress is applied, they come into contact with each other and the electrical resistance value decreases. This switch, which has a pressure-sensitive conductive rubber with electrodes made of metal wire or metal foil, is more flexible than ordinary mechanical switches, but it is thicker and feels like a foreign body, so
It still didn't meet my expectations.

On the other hand, by the same applicant as the present invention, the intertwined parts of the threads constituting the sheet-like product and the electrical conductivity or electrical insulation between the intertwined parts are formed so as to satisfy the following conditions, so that the threads can be stretched in any direction. A deformable conductive knitted fabric whose electrical resistance value changes when subjected to deformation such as bending or compression has been proposed (see Japanese Patent Laid-Open No. 138651/1983).

■ Among all intertwined parts in a given area of knitted fabric,
Let Il+ be the number of intertwined parts that are electrically insulated,
When the number of electrically conductive intertwined parts is 1!2, the ratio is 11. The value of /II2 shall be 1!9 or more as measured value per square inch.

■ Between a plurality of adjacent intertwined parts in a constant length in the longitudinal direction of each yarn constituting the knitted fabric, the number of intertwined parts that are electrically insulated is defined as ml, and the number of intertwined parts that are electrically conductive is When the number between parts is m2, the value of the ratio m1/m2 is 1!9 or more as a measured value per inch.

Since this deformed conductive knitted fabric is cloth, it is thinner and softer than pressure-sensitive conductive rubber. Due to its thinness and softness, the deformed conductive knitted fabric can essentially be said to be a sheet-like material suitable for realizing an input switch that is thin and soft and does not give the impression of a foreign body.

Therefore, the present inventors have proposed a sensor element in which electrodes are provided at least at both ends of this deformed conductive knitted fabric (
JP-A-6L-259103). However, with this method,
If a portion between two electrodes is compressed, a change in resistance cannot be detected, so a large-area planar switch cannot be realized.

The inventors of the present invention have made extensive studies to solve the above-mentioned problems.

[Problem to be solved by the invention]

An object of the present invention is to provide a planar switch that is thin, soft, and has no presence, that is, a human-powered switch that does not give the impression of a foreign body.

[Means to solve the problem]

An object of the present invention is to sandwich a deformed conductive knitted fabric whose electrical resistance value decreases by deformation into at least a part of the area between two flexible conductive sheet-like electrodes. This is achieved by a flexible planar switch.

The present inventors initially printed or etched a conductive layer on a substrate (glass fiber-reinforced epoxy board, plastic board, etc.) using electrodes in order to create a pressure-sensitive conductive element using a deformed conductive knitted fabric. proposed a pressure-sensitive conductive element using a pressure-sensitive conductive element formed by et al. (Japanese Patent Application No. 63-227609). However, this element had the disadvantage that the electrodes were hard and the deformable conductive knitted fabric itself could not take advantage of its softness.

Therefore, the original pressure-sensitive conductive elements using deformed conductive knitted fabrics were not suitable for applications such as biological measurements that required thin, soft, and inconspicuous switches.

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems and have arrived at the present invention.

Here, the modified conductive knitted fabric has the configuration detailed in the above-mentioned conventional technique, and will be abbreviated as sensor fabric for the sake of explanation below.

In addition, in the following explanation, a planar switch has at least two electrodes and has compressive stress (
It has a property (hereinafter referred to as pressure-sensitive conductivity) in which the electrical resistance value decreases when a pressing force is applied.

In the present invention, the electrode made of a flexible conductive sheet material is a conductive fabric (JI) from the viewpoint of flexibility and strength.
S: L-1079: 5~ in drapability test
100, preferably 30 to 100), but is not particularly limited to this.

For example, a conductive adhesive that remains flexible even after curing (e.g., an acrylic resin binder containing carbon black powder) is applied on a thin film (e.g. EVA, nylon film, cellulose acetate film) that has flexibility similar to that of cloth. ) may be printed by means such as coating or transfer screen printing. In addition, a large number of conductive wires are lined up and glued onto a polyester or polyamide hot melt film so that they do not touch each other, and the wires are exposed on the surface of the film, making it as flexible as fabric. It may also be a sheet-like film.

The aforementioned conductive fabrics include, for example, polyester or acrylic taffeta coated with metal plating, nickel plating, copper plating, etc., or recycled cellulose fibers containing a conductive material (copper sulfide, etc.). things, and
There are acrylic tack coated with acrylic carbon resin, but the material is not limited to this as long as it has sufficient flexibility.

The present invention will now be described with reference to the accompanying drawings, which illustrate embodiments of the flexible planar switch of the present invention.

FIG. 1 shows one embodiment of the flexible planar switch of the present invention, and FIG. 2 shows another embodiment.

1(A) and 2(A) are cross-sectional views of the planar switch, and FIG. 1(B) and FIG. 2(B) are perspective views of the planar switch viewed from above. In the figure, 1 is a sensor cloth, 2.3 is an electrode made of a flexible conductive sheet, and 4.5 is a cover sheet.

As shown in Figures 1 and 2, if at least one of the electrodes is made smaller than the sensor cloth, and the two electrodes are not in direct contact with each other through the sensor cloth, the sensor cloth becomes useless. Since it is in an insulating state when loaded, it does not require a spacer and has a simple structure, which is desirable.

Further, as shown in FIG. 1, the terminals of the two electrodes may come out in the same direction, or as shown in FIG. 2, they may come out in opposite directions.

In addition, the sensor cloth may be placed in a part between the upper and lower electrodes, and in that case, a thin, flexible electrical insulating material is used in the part other than the sensor cloth to prevent the electrical connection between the upper and lower electrodes. It is better to prevent conduction. At this time, it is necessary to take care not to impair the flexibility of the planar switch.

A planar switch with such a structure can be operated only at any location of the planar switch depending on the purpose.

Next, the cover sheet plays a protective role by preventing the pressurizing body from directly touching the electrode or the sensor cloth. Therefore, depending on the purpose of use, it is not necessary to use a cover sheet. The material of this cover sheet is
It is best to use something that does not compromise the flexibility and thinness of the planar switch.
That is, it is preferable to use cloth, thin rubber, thin film, or the like.

If fabric is used for the cover sheet and fabric is also used for the electrodes, a planar switch made entirely of fabric is constructed, which is desirable because it becomes a very thin, flexible, and natural input switch.

Furthermore, by making the cover sheet waterproof (that is, using a fabric treated with waterproofing, or a film or rubber that is inherently waterproof), a waterproof planar switch can be obtained.

Furthermore, the air permeability of the flush switch can be adjusted by adjusting the air permeability of the cover sheet. For these reasons, environmental resistance can be improved by appropriately selecting the cover sheet.

Next, methods for sandwiching the electrodes and sensor cloth between the cover sheets include double-sided adhesive tapes made of acrylic, urethane, silicone, etc., hot melt films of polyester, and polyamide, and liquid adhesives such as amide. Examples include a method using an adhesive or the like as appropriate. However, if one side of the cover sheet is coated with polyester or polyamide hot-melt resin scattered in small dots, it will not impair the thinness and softness of the planar switch.
It is also most desirable because it has good workability when manufacturing a planar switch.

Next, FIGS. 3 and 4 show an example of a planar switch of the present invention in which a cover sheet is provided with protrusions.

In the figure, 1 is a deformed conductive knitted fabric, 2.3 is an electrode made of a flexible conductive sheet, 4.5 is a cover sheet, and 6
is a protrusion on the cover sheet. Figures 3 and 4
As shown in the figure, there should be no protrusions or irregularities on one side of the cover sheet, as long as the flexibility of the planar switch is not unnecessarily impaired.
For example, if rubber particles are scattered on the cover sheet, stress will be concentrated on the protrusions.
This is effective because the pressure-sensitive conductive characteristics of the planar switch can be made to have apparently high sensitivity. In addition, this protrusion or unevenness,
As shown in FIG. 3, it may be attached to the surface of the cover sheet on the electrode side, or as shown in FIG. 4, it may be attached to the surface of the cover sheet opposite to the surface in contact with the electrode. In addition, in Figures 3 and 4, protrusions or irregularities are attached to both the upper and lower cover sheets (4.5 in the figure), but even if they are attached only to either the upper or lower cover sheet, Of course it's a good thing.

Furthermore, the higher the hardness of the protrusions or irregularities, the higher the apparent sensitivity of the planar switch. The apparent sensitivity of the planar switch can also be adjusted by changing the size, shape, and spacing of the protrusions or unevenness.

FIG. 5 shows Example 1.4, which is a planar switch of the present invention.
exhibits pressure-sensitive conductive properties. In Example 4, a large number of glass beads are bonded to the cover cloth, whereas in Example 1, such protrusions are not provided.

As is clear from FIG. 5, the provision of protrusions greatly improves the sensitivity of the planar switch.

Regarding sensitivity adjustment, the sensitivity can be lowered by inserting a film with holes as a spacer between the electrode and the deformed conductive fabric.

This is an effective means when the planar switch is used in applications that are subject to large stress, such as a plantar pressure sensor.

Since the planar switch of the present invention is configured as described above, it is possible to obtain a human-powered switch that is thin and highly flexible, which was not available in the past, and that does not feel stiff or strange when used. Furthermore, when using a cover sheet, its material,
By devising the shape and arrangement structure as described above, performance such as flexibility can be further improved.

Further, the planar switch of the present invention has good ability to follow curved surfaces, and an input switch can be provided even on a curved surface. Also,
The structure takes advantage of the pressure-sensitive conductive properties of the deformed conductive knitted fabric, resulting in a highly sensitive, human-powered switch with a light touch.

Furthermore, since a deformed conductive knitted fabric is used, it goes without saying that the rate of reduction in electrical resistance value can be changed depending on the magnitude of the pushing force and the way in which it is pushed.

As mentioned above, it is thin, extremely flexible, has no hardness or foreign body feeling, has good ability to follow curved surfaces, is highly sensitive, and the rate of reduction in electrical resistance changes depending on the amount of pushing force and how it is pushed. The surface switch can be used as a soft switch that freely conforms to a curved surface, so it can be used in toys (for example, it can be incorporated into the stomach or limbs of a doll or stuffed animal, or it can be rolled up to emit sound or light), Soft alarm clocks, cushions that make noise when you sit down, medical applications (breath detection sensors, plantar pressure sensors built into shoe insoles, rehabilitation sensors, finger bending sensors, etc.) sports applications (joint bending sensors, training) (Exercise sensor, pedometer, etc.) Can be used for other purposes.

For example, by incorporating multiple planar switches into the insole of shoes, it is possible to analyze gait to determine which part of the foot touches the ground first and which part does not, which can be used for rehabilitation diagnosis, treatment, and training. be able to.

In addition, even if it is incorporated under a carpet, mat, or wall material, it is thin and does not feel like a foreign body, so it can be used as a bathroom without having a presence.

For example, it can be used as an energy-saving switch that detects where a person is sitting on an electric carpet and heats only that area. It can also be used as a seating position display panel that can be incorporated into seats in airplanes or theaters to show the seating position at a glance.

It can also be incorporated into the seats of cars, airplanes, amusement park rides, etc., and used as a seat belt safety device.

It is also possible to incorporate a matrix of surface switches under the futon sheets to continuously detect the sleeping position.

It can also be used in a wide range of other applications where normal planar switches can be used, such as those listed below.

That is, it can be applied to a wide range of fields that require the function of a man-machine interface where machines and humans come into contact. For example, a variable manual switch can be used to control the intensity of sound, brightness and darkness of light, speed and speed, etc., at will without any malfunction. More specifically, in the field of speed control, for example, there are fast-forward and slow-forward switches for digital timer settings, tape forward/reverse speed control switches for VTRs and camera-integrated VTRs, and zoom speeds for cameras and camera-integrated VTRs. It can be used for control switches, variable speed switches for automobile washers and power windows (all of which can be attached to the handle and controlled by the gripping force of the handle), and power tools such as continuously variable speed drills.

In addition, examples of brightness control of light include brightness control of portable lights, desk lamp lights, interior lights, and automobile headlights. Other examples include display elements that change light intensity by combining with electroluminescent elements (EL elements), liquid crystal devices (LCDs), and light emitting elements (LEDs).

The sound intensity control switch can be used as a control switch that allows the keyboard of an electronic piano, the horn of a car, the door chime, or the receiver of a telephone to be heard just right.

In addition, by mounting it on the detection circuit or output circuit board,
In addition to analog output, the A/D conversion circuit allows multiple stages of digital output, and a single pressure-sensitive conductive element can function as multiple switches (momentary switch/alternate switch).

Furthermore, since the sensor cloth is composed of a two-dimensionally expanded knitted fabric, by devising the knitting and weaving structure and thread usage, it can be used to create thin, high-resolution XY digitizers, handwriting tablets, stamps, and other characters. An input device that can also recognize shapes and shapes is realized.

Of course, it goes without saying that it can be used in all other applications in which ordinary switches are used.

Furthermore, it is clear that the applications of the planar switch of the present invention are not limited to the above-mentioned applications.

〔Example〕

Hereinafter, a more detailed explanation will be given using Examples, but it is clear that the pressure-sensitive conductive element according to the present invention is not limited to those shown in these Examples or the drawings.

Taffeta (warp 50 d/24 f, weft 75 d/36 f) made of polyester fiber yarn manufactured by Asahi Kasei Kogyo ■ was treated with a sodium hydroxide aqueous solution (80 g/I) at 100°C to reduce the weight (liquid volume rate 20%) to 5 nCj. !z: Hydrochloric acid is 3
After sensitization in a bath with a weight ratio of 2 to 10 and washing and dehydration, Pd
Cβ2: Hydrochloric acid is activated in a bath with a weight ratio of 1:15, and after washing and dehydrating, NtCj'2j 6H20, Na1 (PO2,
Sodium citrate, NHCl, ammonia water 1:1
:N
i Plated ester taffeta was produced. This is 10cm
A double cylindrical laminar flow generator (the inner cylinder rotates at high speed, the inner diameter of the outer cylinder is 25 cm)
m, outer diameter of the inner cylinder ioam) together with water, and treated at an inner cylinder rotation speed of 2 QQ rpm for 300 minutes to obtain a deformed conductive fabric.

Next, the obtained deformed conductive knitted fabric was cut into 3 cm square pieces. Furthermore, two pieces of nickel-plated acrylic fabric (drapeability 70 in a drape test conducted in accordance with JIS 1079) were cut into the shape shown in Figure 1.
Sandwich the deformed conductive knitted fabric in between, and from above and below, wrap polyester tricot fabric (two 4 cm square pieces with dots of nylon hot melt resin on one side) with the side with the hot melt resin on the inside. They were then sandwiched together as shown in FIG. 1, and 5 mm from the periphery was thermally bonded at 120° C. to create Example 1 of the planar switch of the present invention.

Next, similarly cut out a deformed conductive knitted fabric (3 cm square), an acrylic nickel-plated fabric, and a polyester fabric (waterproofed, with dots of nylon hot melt resin on one side). Cut the pieces into 4cm squares, stack them as shown in Figure 2, and cut them 5mm from the circumference.
were thermally bonded at 120° C. to create Example 2 of the planar switch of the present invention.

Next, we cut out two 4 cm square pieces of polyester fabric with dots of rubber grains of 2 diameters on one side, and cut out two sheets of 4 cm square pieces of polyester fabric with rubber particles of 2 diameters on one side.
The electrodes (two sheets) cut out in the same way as the electrodes in Example 1 and having drapability 60) in a drape test conducted in accordance with JIS 1079 were stacked as shown in Figure 3, and 5 m from the periphery was glued with acrylic adhesive. This was adhered to create Example 3 of the planar switch of the present invention.

Next, a deformed conductive knitted fabric, an ester-based nickel-plated fabric, and a polyester fabric coated with a polyester hot-melt resin on one side were cut out in the same manner as in Example 3. On the surface, diameter 0.
5th generation glass particles glued with epoxy resin at intervals of 1 tap are laminated as shown in Figure 4, and 5 mm from the periphery is 1
Example 4 of the planar switch of the present invention was prepared by thermal bonding at 50°C.

As a comparative example, instead of the deformed conductive knitted fabric, a thickness of 50 mm was used.
Commercially available pressurized conductive rubber with 0 sound (Japan Synthetic Rubber PCR30
Comparative Example 1.5-05) was used with the same electrode materials and manufacturing procedures as in Examples 1 and 4 of the planar switch of the present invention.
2 was produced. The thickness of the planar switch of the present invention and the planar switch of the comparative example was determined in accordance with JISL 1079 using a "compressive elasticity tester" manufactured by Maebuseiki Manufacturing Co., Ltd., with an initial load of 5 g/
c[[The thickness is shown as 1 o'clock.

In addition, the flexibility of the planar switch can be improved by sandwiching half of the planar switch 70 between the base 11 (the end has a curvature of 1 R) and the acrylic flat plate 10, as shown in FIG. Evaluation was made based on the angle θ formed between the straight line connecting the edge of the stand and the hanging end of the planar switch 7 and the vertical line when a load 9 of Ig/cnf was applied to one end via the gripper 8. . Furthermore, the pressure-sensitive conductive properties were tested by applying a load in the thickness direction of the element using a compression tester manufactured by Toyo Baldwin (
(0 to 1 kg/c) The resulting decrease in electrical resistance was measured using a digital multimeter (manufactured by Atopan Test Co., Ltd.).

The results of these various measurements are summarized in Table 1.

Further, FIG. 5 shows the pressure-sensitive conductive characteristics of the planar switch 1°2 of the present invention and Comparative Example 2.

From these results, the planar switch of the present invention is more flexible than the comparative example using pressurized conductive rubber (θ = 80° for the present invention compared to θ = 3 to 40) and thinner (θ = 80° for the present invention) Example 100.40mm, corresponding comparative example 1
(0.80M), which is double the thickness), shows that the sensitivity is also good. In particular, Example 4, in which glass beads were bonded to the cover cloth, had extremely high sensitivity, but Comparative Example 2, in which beads were similarly bonded to the cover cloth, had no improvement in sensitivity at all.
The effects of using the deformed conductive knitted fabric in the product of the present invention are greatly demonstrated.

Next, wrap the planar switch of Example 1.2 in a sponge sheet (5 mm thick, 5 x 10 cm), put it into the abdomen of a stuffed doll, press the abdomen of the stuffed doll with your hand, When squeezed or twisted,
In both cases, the electrical resistance value of the planar switch decreased. In addition, the amount of reduction depends on the magnitude of the applied deformation,
Compatible with 1 to 6 digits (measurements are made using a multimeter manufactured by Atopan Test Co., Ltd. The same applies below). Furthermore, when deforming the stuffed toy doll, the electrical resistance value decreased no matter which direction the deformation was applied. This indicates that this is a new type of input switch that detects deformation in three-dimensional directions.

Furthermore, when the abdomen of the stuffed toy doll was pressed, squeezed, or twisted with a hand, there was no feeling of a foreign body at all, and the presence of the switch was not felt.

Next, Examples 3 and 4 were placed under the raised fabric on the surface of a stuffed toy doll, and when the fabric was lightly stroked with a hand, the electrical resistance value of the planar switch decreased by 1 to 4 digits. In addition, when I stroked it hard, it decreased by 4 to 6 digits. At this time as well, there was no feeling of a foreign body due to the built-in switch, and the presence of the switch was not felt.

〔Effect of the invention〕

The planar switch according to the present invention having the above-mentioned configuration is thin, extremely flexible, has no hardness or foreign body feeling, has good ability to follow curved surfaces, is highly sensitive, operates with a light touch, and has a large pressing force. Since the rate of reduction in electrical resistance changes depending on how the sheath is pressed, it can be used as a new type of human-powered switch.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the flexible planar switch of the present invention, FIG. 1(A) is a sectional view, FIG. 1(B) is a perspective plan view, and FIG. 2(A) is a sectional view, FIG. 2(B) is a perspective plan view, and FIGS. 3 and 4 are sectional views showing other embodiments, respectively. FIG. 5 is a graph showing the pressure-sensitive conductive characteristics of the planar switch, and FIG. 6 is a front view showing a test instrument for evaluating the flexibility of the planar switch. l... Deformed conductive knitted fabric, 2.3... Electrode made of a flexible conductive sheet material, 4.5... Cover sheet, 6... Protrusion, 7... Surface Switch, clip, 9. Load, 10. Acrylic plate, 11. Stand.

Claims (1)

[Claims] 1. A flexible surface characterized by sandwiching a deformed conductive knitted fabric whose electrical resistance value decreases through deformation in at least a partial area between electrodes made of two flexible conductive sheets. shape switch.