JPH0599768A - Pressure sensor - Google Patents

Abstract

PURPOSE:To enable easy bending in lateral direction and to reduce aging effect thereof in a plate shaped pressure sensor. CONSTITUTION:A plate shaped soft and conductive rubber 6 of which resistance value changes according to pressure, a lead wire 7 which is arranged in the vicinity of the upper surface of the conductive rubber 6, and a lead wire 8 which is arranged at vicinity of a lower surface of the conductive rubber 6, are provided. The conductive rubber is formed by mixing metal oxide powder or carbon powder into ordinary rubber material. Each lead wire 7 and 8 is arranged in a full width of the conductive rubber 6 in a manner of single stroke figure of a pen. As the lead wires, a naked copper wire or a copper plated piano wire is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor used in an opening portion of a power window or an electric sunroof of an automobile.

[0002]

2. Description of the Related Art In a power window of an automobile, as shown in FIG. 1, a window glass 3 which is housed in a door 1 and which can be moved up and down by a drive motor and which abuts on an upper frame 2 of the door 1 to close it. It is provided. An elastic weather strip portion 4 for preventing rainwater from entering when the window glass 3 is closed is attached to the upper frame 2.

For example, when a child is carried in an automobile, there is a possibility that the child's hand, finger, neck or the like may be caught by a little carelessness. The pressure sensor 5 for detecting the entrapment of foreign matter such as hands and fingers is attached to a portion of the weather strip portion 4 that can come into contact with the window glass 3.

As shown in FIG. 2, the conventional pressure-sensitive sensor 5 has a structure in which a plate-shaped conductive rubber 6 and two conductive plates 6 are sandwiched between two metal plates to convert the pressing force into a resistance value. Electrodes 7 and 8 that form the structure, and an outer cover 9 that covers this structure with an insulating material such as a heat-shrinkable tube. When the pressure sensor 5 is pressed in the Y direction, the resistance value decreases when the width direction is the X direction, the thickness direction is the Y direction, and the depth direction is the Z direction.

Therefore, the pressure sensor 5 and the window glass 3 are
The upper surface of the window glass 3 is relatively arranged so as to press the one electrode 8 side of the pressure sensitive sensor 5. Further, the pressure-sensitive sensor 5 can be slightly curved in the Z direction only when the radius of curvature is large. Therefore, if the inner surface of the weather strip portion 4 of the upper frame 2 is curved only in one direction, that is, the Z direction, the weather sensor 5 can be used. It can be arranged along the inner surface of the strip part 4.

[0006]

However, in the door 1 of an ordinary automobile, not only the weather strip portion 4 is curved in the Z direction along the upper frame 2, but also the upper surface of the window glass 3 at the time of closing is closed. To accept and increase air tightness,
A single recess that is curved in the X direction is formed. As shown in FIG. 2B, it is extremely difficult to bend the conventional pressure-sensitive sensor 5 in the X direction, so that it cannot be attached in conformity with the recess of the weather strip portion 4.

This is because even if the conductive rubber 6 is flexible, the two metal plates adhered to the conductive rubber 6 form a bridge structure and hinder a curve having a small radius of curvature.
Further, the pressure-sensitive sensor 5 has to be arranged in substantially the entire area of the weather strip portion 4 in order to detect foreign matters such as hands and fingers, and when the hands and fingers are sandwiched between the window glass 3. To
The pressing force is averaged by the metal plate electrode, and the detection sensitivity is also lowered.

Further, the pressure-sensitive sensor is inevitably required to have an outer cover in order to fix the upper and lower electrodes and prevent corrosion of the electrodes. Due to the presence of this outer cover, the initial pressure fo is applied to the pressure-sensitive sensor without applying an external force, as shown in FIG. This causes the pressure sensitive area to be narrowed.

The present invention solves the above-mentioned problems by arranging, instead of the metal plate, an electrode formed by a single electric wire in the area occupied by each metal plate, and therefore, it is adjusted to the depression of the weather strip portion 4. Can be installed by
The object is to prevent the detection sensitivity from being lowered when a hand, a finger, or the like is sandwiched between the window strip 3 and the weather strip portion 4 even if the weather strip portion 4 is disposed in substantially the entire area. Further, it is also an object to prevent corrosion of the electric wire by exposing the electric wire to the air without using an outer cover.

[0010]

In order to achieve the above object, a pressure-sensitive sensor according to the present invention is a plate-shaped conductive flexible body whose resistance value changes with pressure, and one surface (upper surface) of the conductive flexible body. A first electrode embedded in the conductive flexible body, and a second electrode embedded in the vicinity of the opposing surface (lower surface) of the conductive flexible body, each of the first and second electrodes being formed of the conductive flexible body. It is characterized in that it is a one-stroke-shaped electric wire that spreads out over approximately the width.

Further, according to another aspect of the pressure-sensitive sensor of the present invention, each of the first and second electrodes is a corrugated electric wire in which the same shape is repeated periodically, and these corrugated electric wires are , Having a phase difference of 180 degrees from each other and embedded in the vicinity of both surfaces of the conductive flexible body.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pressure sensitive sensor of the present invention will be described below with reference to the drawings. FIG. 4 shows a perspective view of the pressure-sensitive sensor 5 according to the present invention after assembly. In this figure, members corresponding to those of the conventional pressure sensor 5 are designated by the same reference numerals.

Therefore, the pressure-sensitive sensor 5 according to the present invention is a plate-like flexible conductive rubber 6 whose resistance value changes with pressure.
And a first electrode 7 buried near the upper surface of the conductive rubber 6 and a second electrode 8 buried near the lower surface of the conductive rubber 6.
It has and.

The conductive rubber 6 is formed by mixing a normal rubber material and a conductive material such as carbon powder into a plate shape. As the conductive material, instead of carbon powder, metal oxide powder having a resistance value larger than that of metal powder is also used.

The first electrode 7 is a single-stroke-shaped electric wire 7 that extends over substantially the width of the conductive rubber 6. Further, the electric wire is preferably a bare copper wire having high ductility or a copper wire plated with copper. On the other hand, the second electrode 8, that is, the electric wire 8 is also made of the same material as the first electric wire 7.

The finished pressure-sensitive sensor 5 is, for example, an electric wire 8
It is easily adhered in the recess of the weather strip portion 4 so that the arrangement surface of can contact the upper surface of the window glass 3.

Of course, the pressure sensor 5 may be manufactured in a continuous process. In this case, the conductive rubber 6 is extruded from the rectangular nozzle of the extrusion molding machine, and the electric wires or bare copper wires 7 and 8 which are previously formed in a wave shape are placed on the upper and lower surfaces of the conductive rubber 6,
On these wavy wires 7 and 8, further conductive rubber 6 is added from the rectangular nozzle of another extruder to form an assembly.

Thereafter, this assembly is placed in a pressurizing and heating chamber, the conductive rubbers 6 are adhered to each other under high temperature and pressure, and the electric wires 7 and 8 are arranged in the vicinity of both surfaces of the conductive rubbers 6. The finished pressure-sensitive sensor 5 has a predetermined length, for example, 100 m.
Is wound up on the roller until.

At the time of use, the pressure-sensitive sensor 5 is cut a little longer than the length of the mounting portion, and the conductive rubber 6 at a slightly longer portion is cut.
After peeling off, the electric wires 7 and 8 at that portion are used as lead wires for extracting electrodes.

As described above, the wavy electric wires 7 and 8 are shown in FIG.
The same shape is repeated periodically as shown in FIG. The wavy upper electric wire 7 shown by the solid line and the lower electric wire 8 shown by the dotted line in FIG. ..

This is because when the pressure-sensitive sensor 5 is pressed by a considerably strong force, the upper electric wire 7 and the lower electric wire 8 are made of conductive rubber 6.
This is because, if they are arranged at substantially the same position (in phase) with the pin between, the risk of contact between the wavy electric wires increases. Also,
Although various shapes can be considered as wavy, mainly sinusoidal,
Indicates triangular or rectangular wave.

[0022]

As described above, since the pressure-sensitive sensor according to the present invention uses the corrugated electric wire as the electrode, the pressure-sensitive sensor can be easily bent in the width direction. Therefore, for example, the upper frame of doors of various shapes of automobiles or the like. It can be easily installed in the recess of the weather strip. Further, even if a pressing force is applied to a part of the pressure sensitive sensor, only that part is deformed and the detection sensitivity can be enhanced. Furthermore, since the electric wire is embedded in the conductive rubber 6, corrosion of the electric wire does not proceed, and thus a pressure-sensitive sensor with little secular change can be formed. Also, the pressure sensitive area is not limited.

[Brief description of drawings]

FIG. 1 is a perspective view of a conventional flat pressure sensor.

FIG. 2 is a schematic view of a vehicle door to which the pressure-sensitive sensor of the present invention can be attached and a cross-sectional view near the upper frame.

FIG. 3 is an F-R characteristic diagram of a pressure sensitive sensor using conductive rubber.

FIG. 4 is a perspective view of a pressure sensor according to the present invention.

[Explanation of symbols]

 5 Pressure Sensitive Sensor 6 Conductive Flexible Body (Conductive Rubber) 7 First Electrode (Electric Wire) 8 Second Electrode (Electric Wire)

Claims (3)

[Claims] 1. A conductive flexible body whose resistance value changes with pressure, a first electrode embedded near one surface of the conductive flexible body, and a second electrode embedded near the opposing surface of the conductive flexible body. The pressure-sensitive sensor including: a pressure-sensitive sensor, wherein each of the first and second electrodes is a one-stroke-shaped electric wire that extends over substantially the width of the conductive flexible body. 2. The pressure sensitive sensor according to claim 1, wherein each of the first and second electrodes is a wavy electric wire in which the same shape is periodically repeated. 3. The pressure sensitive sensor according to claim 2, wherein the corrugated electric wires are embedded in the vicinity of both surfaces of the conductive flexible body with a phase difference of 180 degrees.