JPH1054768A - Waterproof construction for plane pressure sensitive sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plane pressure sensitive sensor for normally performing appropriate actuation without infiltration of water and the like into a space part in a plane pressure sensitive member. SOLUTION: In the plane pressure sensitive sensor which comprises conductive members are respectively positioned in vertically opposite substrate 3, 4 and in which the vertically opposite side conductive members are contacted with each other to electrify, a vent hole 6 communicating the space part 5 between the vertical substrates of the sensor with atmosphere is formed in at least one of the upper substrate or the lower substrate and also a porous film 7 which passes the air but does not pass water is bonded on a communicating surface with atmosphere of the vent hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar pressure-sensitive sensor whose resistance changes when a pressure or load is applied, wherein water or the like is prevented from entering an internal air layer. Related to waterproof structure.

[0002]

2. Description of the Related Art In recent years, planar pressure-sensitive sensors have been widely used as members for detecting pressure and load. For example,
In an automobile, an airbag device for detecting a collision and deploying an airbag to protect an occupant is usually operated in the event of a vehicle collision, even if a passenger is not in the passenger seat or not. Since the airbag is deployed together with the seat airbag, it is not necessary to deploy the passenger airbag when no passenger is on the passenger seat, and once deployed, the airbag must be replaced with a new one, which is wasteful. As a countermeasure, a system has been developed which detects whether or not a person is in the passenger seat and does not operate the airbag when the passenger is not. As a sensor for detecting whether or not a person is sitting on the front passenger seat used in such a system, it is an optimal sensor for detecting that a load exceeding a predetermined level is acting on a wide surface. A pressure sensor is used.

Further, in a motor vehicle, for example, in order to sound a horn, when a driver hits the vicinity of the center of the steering wheel, it is detected, and a planar pressure sensor is also used to operate the horn. Has been proposed, to detect that a human body such as the neck has been pinched in the power window, to stop the closing operation of the window and open it,
It has been proposed to use a planar pressure sensor as a means for detecting whether an object has been caught or the window has been closed to the end. Further, with the technical progress of the planar pressure-sensitive sensor, the planar pressure-sensitive sensor is used as a pressure-sensitive sensor not only in automobiles but also in various types.

As one of such planar pressure sensors,
The one shown in FIGS. 3 and 4 has been proposed. That is, this planar pressure sensor is commercially available under the trade name FSR from International Electronics and Engineering Company (IEEE) of Luxembourg, and is provided on the substrate layer surface 22 of the lower substrate 4 made of an insulating material. A resistor 23 made of a conductive resin whose resistance changes according to a load or a pressure is provided, and a particle-shaped conductor 24 made of carbon or the like is provided in the resistor 23 to constitute a pressure-sensitive film 25. A contact support layer 26 is disposed facing the pressure-sensitive film 25 via a spacer (not shown). A first contact 28 as a conductor and a second contact 28 are provided on a surface 27 of the contact support layer 26 facing the pressure-sensitive film 25. The contact 29 and the contact 29 are arranged and fixed at an interval. As a result, a space 5 is formed between the surface 22 of the substrate layer of the pressure-sensitive film 25 and the surface 27 of the contact support layer 26. The space 5 communicates as a whole, and its end is configured as described above. Edge 3 of pressure transducer 31
2 and is communicated to the outside through an opening 33. Electricity is supplied from a power source 34 between the first contact 28 and the second contact 29.

The pressure transducer 31 constructed as described above
Is used as a planar pressure-sensitive sensor as shown in FIGS.
As shown in FIG. 1, a pair of electrodes 28 and 29 are printed in a comb-like shape on one surface of a back side plastic film 3 serving as one substrate, and the ends thereof are connected to a connector 40. On the other hand, the above-mentioned pressure-sensitive film 25 is applied to one surface of the front side plastic film 4 serving as the other substrate. The pressure sensor 44 is used. When the surface pressure sensor 44 is used, when the pressure P is applied from the upper surface of the upper substrate 3 as shown in FIG. 3, the first contact 28 and the second contact 29 on the surface 27 of the upper substrate 3 are both Electricity flows through the resistor 23 by contacting the conductor 24 on the substrate layer surface 22 of the lower substrate 4. At this time, the pressure P and the pressure-sensitive film 2
As shown in FIG. 7, the relationship with the electrical resistance of No. 5 has a tendency that the electrical resistance decreases as the pressure increases, so that a predetermined pressure P is set in advance and the corresponding electrical resistance is determined. By detecting the electric resistance value, it is possible to detect whether a predetermined pressure is applied.

[0006]

In the above-mentioned conventional planar pressure-sensitive sensor, as shown in FIG.
5 is formed between the surface 22 of the substrate layer and the surface 27 of the contact support layer 26, and a passage communicating with the space 5 is formed at a part of the edge 32 of the sensor member. In addition, since it is configured to communicate with the outside through the opening 33, this planar pressure sensor is used to determine whether or not a person is sitting in the passenger seat in the passenger airbag system as described above. When the sensor is installed in the passenger seat and used as a sensor for detection, for example, when water or the like is spilled on the passenger seat, if water enters the space 5 through the opening 33, the first There is a short circuit between the contact 28 and the second contact 29, which makes it impossible to perform a proper operation as a pressure-sensitive body.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a planar pressure-sensitive sensor in which water or the like does not enter the space inside the planar pressure-sensitive body and always performs proper operation.

[0008]

According to the present invention, in order to solve the above-mentioned problems, conductors are respectively arranged on upper and lower opposing substrates, and the conductors on the upper and lower opposing surfaces are brought into contact with each other by pressure acting on the surfaces. In a planar pressure-sensitive sensor that is energized by air, at least one of the upper substrate and the lower substrate is provided with a ventilation hole that communicates the space between the upper and lower substrates of the sensor with the outside air, and allows air to pass through the sensor. Is a film in which a porous film that does not pass through is adhered to a surface of the vent hole communicating with the outside air.

According to the present invention, as described above, when pressure is applied to the surface of the planar pressure-sensitive sensor in a normal use state, the conductors disposed on the upper and lower opposing surfaces in the sensor come into contact with each other. To apply electricity and detect that pressure has acted. At that time, the air in the space between the upper and lower opposing surfaces in the sensor is pushed out, or the air in the entering space is passed through a porous film adhered to the surface communicating with the outside air through the ventilation hole. And come and go freely. When water is spilled on this planar pressure-sensitive sensor, even if the water comes into contact with the porous film attached to the communicating surface between the vent and the outside air, water cannot pass through this porous film, Water does not enter the sensor and prevents the planar pressure sensor from malfunctioning due to water.

[0010]

Embodiments of the present invention will be described with reference to the drawings. Since the details and the overall configuration of the contact and the like of the planar pressure-sensitive sensor are the same as those of the conventional one, the description of the detailed configuration and the like is omitted. The point that the present invention is particularly different from the conventional one is that, as shown in FIGS. 1 and 2, a space formed between an upper substrate 3 and a lower substrate 4 which are separated from each other by spacers 2 and 2. 5 communicates with the atmosphere communication opening 6 formed in the substrate 3 in the embodiment shown in FIG. 2, and the air in the internal space 5 communicates with the outside air and the atmosphere communication opening 6 in a normal use state. Are coming and going through.

A porous film 7 is provided in the air communication opening 6.
The porous film 7 is, for example, a porous film commercially available from Nitto Denko Corporation under the trade name of Microtex as a generic name of a porous film of ethylene tetrafluoride resin. This porous membrane has hundreds of millions of micropores per square centimeter, and can simultaneously exhibit waterproof and dustproof properties and air permeability. It is a material that has a selective permeability.

By sticking such a porous film 7 to the atmosphere communication opening 6, there is no hindrance at all in distributing the internal air to the outside in the normal use condition as described above. On the other hand, for example, as described above, this pressure-sensitive sensor is installed in the seat portion of the passenger seat as a sensor for detecting whether or not a person is sitting in the passenger seat in the airbag system for a passenger seat of an automobile as described above. When used, for example, when water or the like is spilled in the passenger seat, water tends to enter the space 5 through the air communication opening 6, however, since the porous film 7 is stuck to this portion. Water cannot enter the inside due to its selective permeability, and it is possible to prevent the sensor from malfunctioning due to the water entering the internal switch portion.

In the above embodiment, FS is used as a planar pressure-sensitive sensor whose resistance changes with pressure.
Although an example using R has been described, other sensors may be used.
For example, the upper and lower contacts arranged via a spacer are always kept apart, and when pressure is applied, the contacts come into contact with each other against the elasticity of the substrate, and a planar pressure sensor that closes the switch may be used. Can be used. As the porous film to be stuck to the air communication opening, various types can be used in addition to the microtex described above, as long as the film has the same function. In addition, the planar pressure-sensitive sensor may be arranged between two opposing films so as to be uneven and continuous with each other, and may be arranged in various ways.

Further, this planar pressure sensor is used for detecting whether or not a person is sitting in the passenger seat in the above-described passenger airbag system. It may be used as a membrane switch for detecting whether or not a person has pressed this portion.

[0015]

The present invention is constructed as described above. When water is spilled on the surface pressure sensor, the water comes into contact with the porous film adhered to the communicating surface between the vent and the outside air. However, since water cannot pass through the porous film, water does not enter the sensor, and it is possible to prevent the surface pressure sensor from malfunctioning due to water.

[Brief description of the drawings]

FIG. 1 is a horizontal sectional view of an embodiment of a planar pressure-sensitive sensor according to the present invention.

FIG. 2 is a partial sectional view taken along line AA of FIG.

FIG. 3 is a sectional view showing a structure of a planar pressure-sensitive sensor to which the present invention is applied.

FIG. 4 is a plan view seen from a direction B in FIG. 3;

FIG. 5 is a perspective view in which a part of the planar pressure-sensitive sensor is released in a state where it is assembled as a product.

FIG. 6 is a sectional view of the same.

FIG. 7 is a characteristic diagram of a pressure-sensitive resistor of the pressure-sensitive sensor.

[Explanation of symbols]

 2 Spacer 3 Upper substrate 4 Lower substrate 5 Space 6 Opening to atmosphere 7 Porous film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location // B60R 16/02 610 B60R 16/02 610B

Claims (6)

[Claims] 1. Conductors (24, 28, 29) are respectively disposed on upper and lower opposing substrate surfaces, and the conductors on the upper and lower opposing surfaces come into contact with each other and are energized by pressure applied to the surfaces. In the planar pressure-sensitive sensor, a ventilation hole (6) for communicating a space (5) between upper and lower substrate surfaces of the sensor with the outside air is formed in at least one of the upper substrate (3) and the lower substrate (4). A waterproof structure for a planar pressure-sensitive sensor, characterized in that a porous film (7) that allows air to pass through but does not allow water to pass through is attached to the communication surface of the ventilation hole (6) with the outside air. 2. The waterproof structure for a planar pressure-sensitive sensor according to claim 1, wherein the electric resistance value of the planar pressure-sensitive sensor changes according to the surface pressure acting on the sensor. 3. The planar pressure-sensitive sensor according to claim 1, wherein the pressure sensor is an upper substrate.
Two contact members (28, 29) are arranged on the inner surface of the lower substrate (4), and conductors (24) are arranged on the inner surface of the lower substrate (4) at intervals, and the electric resistance between the conductors is increased by pressure. The waterproof structure of a planar pressure-sensitive sensor according to claim 2, wherein a variable pressure-sensitive film (25) is arranged. 4. The planar pressure sensor according to claim 1, wherein a contact portion is disposed on each of the inner surfaces of the substrate opposed to each other, and both contacts are electrically connected by a surface pressure acting on the sensor. Waterproof structure of planar pressure sensor. 5. The surface according to claim 1, wherein said planar pressure-sensitive sensor is arranged non-uniformly between two opposing film substrates and so as to be continuous with each other. Waterproof structure of pressure sensor. 6. The planar pressure sensor according to claim 1, wherein the planar pressure sensor is an occupant detection sensor that is installed in a seat of an automobile and detects the presence or absence of an occupant. Waterproof structure.