JPH051090Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a piezoelectric element fixing structure with improved waterproofness that can be suitably used, for example, in a contact type piezoelectric sensor.

BACKGROUND ART Conventionally, in order to detect contact with an object on a rug such as a carpet or flooring material, or a wall material,
The use of pressure-sensitive rubber or strip-shaped piezoelectric elements is being considered. Among these, pressure-sensitive rubber is not sensitive to deformations other than those in the thickness direction, so if it is to be used to perform good contact detection, it must be provided over almost the entire desired detection area. On the other hand,
A strip piezoelectric element is made by providing electrodes on both sides (or three or more layers in a laminated structure) of a polymeric piezoelectric film such as PVDF (polyvinylidene difluoride resin).
It exhibits good sensitivity to elongation or bending deformation other than in the thickness direction, and therefore good contact detection is possible just by providing it locally in the desired detection area.
In particular, if a strip-shaped piezoelectric element is disposed on the front surface, back surface, or inner layer of the constituent material of the desired detection region, it becomes possible to efficiently detect contact over a wide area.

However, in order for the band-shaped piezoelectric element to function properly, the electrodes provided on both sides must maintain good insulation from each other, and in order to prevent short circuits due to moisture or dust adhesion when exposed, waterproofing is required. There is a need for protection. An example of a piezoelectric element fixing structure that takes such waterproof protection into consideration is one in which a strip piezoelectric element is sandwiched between a pair of frames, with an insulating resin coated on the end face or the entire surface of the strip piezoelectric element to form a waterproof protective film. has been proposed (Japanese Unexamined Patent Publication No. 58-78338). However, there are several problems in forming a waterproof protective film using such a coating. First, it is difficult to form a strong coating film on the end face of the strip-shaped piezoelectric element, which is most in need of waterproofing treatment. From the viewpoint of improving waterproofness, as described in the above-mentioned Japanese Patent Application Laid-Open Publication No. 1999-1991, it is effective to attach a strip-shaped piezoelectric element to an elastic film in advance and form a thick coating film near the end surface of the strip-shaped piezoelectric element. It is true. However, in this case, the attachment to the elastic body itself is not necessarily advantageous because it is accompanied by a change in the characteristics of the strip piezoelectric element, and there is also the disadvantage that the characteristics are not constant due to the formation of an excessive coating film. After all, the above-mentioned coating-type waterproofing treatment does not provide waterproofness to the extent that it can withstand, for example, an underwater immersion test. Furthermore, in the prior art, no consideration has been given to how to provide waterproof protection for terminal portions that have not been subjected to waterproof treatment.

Summary of the invention In view of the above-mentioned circumstances, the main purpose of the invention is to provide a fixing structure for a band-shaped piezoelectric element that has good waterproof properties to the extent that it can withstand, for example, a waterproof test by immersion in water.

The piezoelectric element fixing structure of the present invention was developed to achieve the above-mentioned object, and more specifically, the piezoelectric element fixing structure of the present invention was developed to achieve the above-mentioned purpose. The strip-shaped piezoelectric element is housed in a bag strip body, and is sandwiched between an upper lid body and a lower lid body while electrically connecting a pair of lead terminals to the exposed portion, and the strip piezoelectric element is exposed by the upper lid body and the lower lid body. The present invention is characterized by having a terminal portion that also holds a bag band adjacent to the terminal portion, thereby making the terminal portion a sealed structure as a whole.

That is, in the above piezoelectric element fixing structure, the strip piezoelectric element is housed in the bag strip in advance except for the exposed portion, and when the exposed portion and the adjacent open end of the bag strip are connected to the lead terminal, the exposed portion and the open end of the bag strip adjacent to the exposed portion are placed in the upper cover. Since it is held between the body and the lower lid body, a firm sealing structure can be obtained as a whole. In this case, if a polymer film is used as the bag strip, not only water impermeability can be obtained, but also one with a uniform thickness can be easily obtained, so that the change in properties of the strip piezoelectric element is uniform. In addition, a good sealing effect is exhibited when the upper and lower lids are held together, so
Good waterproof properties are imparted to the piezoelectric strip in the bag strip.

Examples Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is an exploded perspective view of a piezoelectric element fixing structure according to an embodiment of the present invention developed for embedding in a carpet, and FIG. 2 is an assembled perspective view thereof.

Referring to FIG. 1, a strip piezoelectric element 1 has a thickness of approximately 2 to 100 μm, a width of 2 to 100 mm, and a length of 0.1 μm, for example.
An electrode film of aluminum, nickel, gold, copper, etc. with a thickness of 0.01 to 2 μm is formed on both sides of a belt-shaped polymer piezoelectric film of ~10 m in length (the illustration of the laminated structure is omitted. (It is also possible to adopt a structure in which piezoelectric films are laminated via an electrode film.) Here, the polymeric piezoelectric film is a polarized composition mainly composed of polymers or copolymers of highly polar monomers such as vinylidene fluoride, vinyl fluoride, trifluoroethylene, and fluorochloroethylene. A piezoelectric polymer film obtained by the above method is preferably used. Among these, vinylidene fluoride polymers or copolymers containing 50 mol% or more of vinylidene fluoride are preferred because they have good piezoelectricity. It is also possible to use a polymeric piezoelectric film made of a composition containing a vinylidene fluoride polymer or copolymer as a main component, mixed with an inorganic ferroelectric material such as PZT.

This strip-shaped piezoelectric element has approximately 10
~20 mm is left as the exposed portion 1a, and the remaining portion is housed in a water-impermeable bag strip 2. The bag strip 2 is preferably made of a high-quality material that can be heat-sealed, including heat sealing in a narrow sense, high-frequency sealing, and ultrasonic sealing, such as polyvinyl fluoride, polyvinylidene fluoride, polyamide, polyacetal, polycarbonate, and polyethylene terephthalate. It is made of a molecular film and has a thickness of, for example, about 2 to 100 μm. For example, both edges 2 of about 2 mm
a, 2b and the opposite end 2c (FIG. 2) are heat sealed. Exposed portion 1a of band-shaped piezoelectric element 1
are sandwiched by a pair of conductor pieces 4a, 4b connected to lead wires 3a, 3b (shown only in FIG. 2, not shown in FIG. It is held by the body 5b. For the lead wires 3a and 3b, for example, according to JIS standards, the total inner diameter of 12 core wires is 0.7 mm, and the outer diameter of the sheathing is 0.7 mm.
A 1.6mm one is used. The conductor pieces 4a and 4b are
For example, it is made of copper, phosphor bronze, brass, nickel, aluminum, etc. with a thickness of 0.002 to 0.4 mm, and corresponds to the pressing and fixing force from the upper lid body 5a and the lower lid body 5b.
It is preferable to apply an elastic pressing force to the exposed portion 1a of the band-shaped piezoelectric element. For this purpose, conductor strip 4
For a and 4b, in addition to those provided with wave-shaped unevenness as in this example, those provided with hemispherical convex portions are also preferably used. Lead wires 3a, 3b and conductor piece 4
A and 4b may be joined by caulking a part of the conductor piece as in this example, or by soldering. In addition, if the tip portions of the lead wires 3a and 3b (only the tip portion of 3a is shown as 3aa) are flattened including the core wire portion and the covering portion before joining with the conductor piece, the upper lid body and the lower lid The fixation of the lead wire is improved by engagement with the hole-forming recess 5d provided in the body.

The upper lid body 5a and the lower lid body 5b are preferably made of materials having relatively good heat resistance such as Bakelite resin, ABS resin, vinyl chloride resin, polycarbonate, polyvinylidene fluoride, polyphenylene sulfide, etc. , an exposed portion 1a, a recess 5c for holding and accommodating the stacked conductor pieces 4a and 4b, a recess 5d for forming a hole for lead wire extraction, and an end of the bag strip 2 by machining or injection molding. It is preferable to form a thin holding recess 5e of 2d in the upper lid 5a and/or the lower lid 5b. Before the conductor pieces 4a, 4b are held between the upper lid body 5a and the lower lid body 5b, a sponge,
It is also preferable to use an elastic body such as rubber or metal spring material.

When the conductor pieces 4a, 4b are clamped by the upper and lower lids 5a, 5b, the ends 2d of the bag strip 2 are also clamped and pressed at the same time, and the strip piezoelectric element in the bag strip 2 is sealed. Furthermore, for areas where there is a possibility that voids may remain, such as the joint between the upper lid body 5a and the lower lid body 5b or the vicinity of the recesses 5d and 5e, apply epoxy resin, urethane resin, phenolic resin, silicone resin, etc. to these areas in advance. Nitrile resin, polyester resin,
Adhesive 6 made of thermosetting or thermoplastic adhesive resin such as butyral resin, chloroprene resin, etc.
(Fig. 2), and after confirming the sealing, release the pressing force on the upper and lower lids 5a and 5b. The generally box-shaped terminal portion 5 formed by the combination of the extended portion of the element 1 and the upper and lower lids 5a and 5b is provided with a good hermetic and waterproof structure. It is also preferable that the upper lid body 5a and the lower lid body 5b are connected in advance with a hinge. Lid body 5a,
By appropriately setting the thickness of 5b, the thickness of the conductor piece, etc., the thickness of the box-shaped terminal portion 5 can be adjusted to, for example, 3 to 8 mm.
It is also possible to keep it within the range of .

In the above, a piezoelectric element fixing structure for embedding in a carpet has been described as a preferred embodiment of the present invention. However, devices with a similar structure are effectively used for contact detection by being attached to or buried in flooring or wall materials, and are mainly used for waterproofing of the band-shaped piezoelectric elements protruding from the terminals. It can also be effectively used for piezoelectric elements in general, including vibration sensors and the like. Therefore, in the present invention, the word "band-shaped" in the band-shaped piezoelectric element means that it has a part that extends outside in addition to the part accommodated in the terminal part, and the length of the external extension part is equal to the length of the external extension part. It does not need to be significantly larger than the width. However, for the purpose of contact detection as described above, it is preferable that the length is essentially larger than the width (for example, four times or more). In addition, including such uses, instead of exposing one end of the strip piezoelectric element as in the above embodiment, the terminal portion may be formed by exposing a part of the center of the strip piezoelectric element housed in the bag strip. Alternatively, a band-shaped piezoelectric element having one end exposed may be added to this to form a T-shaped band-shaped piezoelectric element as a whole.

Effects of the Invention As described above, according to the present invention, after the band-shaped piezoelectric element is housed or wrapped in a water-impermeable bag band,
A piezoelectric element fixing structure fixed with good sealing properties is provided. In addition, the fixed terminal part can have a sealed fixed structure without using conductive adhesive that is generally used for bonding belt-shaped electrical products, so the piezoelectric element fixed structure has good durability against environmental temperature changes. is provided.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a piezoelectric element fixing structure according to an embodiment of the present invention, and FIG. 2 is an assembled perspective view thereof. 1... Band-shaped piezoelectric element (1a... exposed part), 2...
...Bag band, 3a, 3b...Lead wire, 4a, 4b
...Conductor piece, 5a... Upper cover body, 5b... Lower cover body.

Claims (1)

[Claims for Utility Model Registration] 1. A strip piezoelectric element is housed in a water-impermeable bag strip with at least a portion of its longitudinal direction left as an exposed portion, and a pair of lead terminals are electrically connected to the exposed portion. The terminal portion is sandwiched between an upper lid body and a lower lid body, and a bag strip adjacent to the exposed portion of the strip piezoelectric element is also sandwiched by the upper lid body and the lower lid body, so that the terminal portion has an airtight structure as a whole. A piezoelectric element fixing structure having. 2. The structure according to claim 1, in which the band-shaped piezoelectric element has one end exposed and the remaining part accommodated in the bag band. 3. A pair of lead terminals each consists of a lead wire and a conductor piece joined to the lead wire, and the exposed portion of the band-shaped piezoelectric element is sandwiched between the pair of conductor pieces, and is further sandwiched between an upper cover body and a lower cover body. The structure according to claim 1 or 2 of the utility model registration claim. 4. The utility model according to claim 3, wherein the pair of conductor pieces has a structure that applies an elastic pressing force to the exposed portion of the band-shaped piezoelectric element due to the pressing force from the upper lid body and the lower lid body. Structure. 5. The structure according to claim 4, wherein each of the pair of conductor pieces is formed into a wave shape. 6. The terminal section which is clamped and fixed and divided by the upper lid body and the lower lid body has a generally rectangular box-shaped structure, and the strip piezoelectric element housed in the lead terminal and bag strip body is taken out from another side of the box-shaped structure. Claims 1 to 5 for utility model registration
A structure described in any of the sections. 7. The structure according to claim 6, wherein the lead terminal and the band-shaped piezoelectric element housed in the bag band are taken out from different sides of the box-shaped structure that are substantially orthogonal to each other. 8. The structure according to any one of claims 1 to 7, wherein the bag strip is made of a polymer film. 9 Utility model registration claim 8, in which the bag band is formed by heat-sealing a polymer film.
The structure described in section.