Electricity: circuit makers and breakers – Special application – Feeler moves into detecting contact with object
Reexamination Certificate
1999-08-17
2001-05-01
Oen, William (Department: 2855)
Electricity: circuit makers and breakers
Special application
Feeler moves into detecting contact with object
Reexamination Certificate
active
06225583
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a pressure sensitive sensor and a method for manufacturing the same, and more particularly to a pressure sensitive sensor used for a mechanism provided to a power window of an automobile or a residential shutter so as to prevent a foreign matter from being caught in, or used for sensing a collision of a resilient bumper of a transportation cp Japanese Patent Application Laid-Open 9-209615 discloses a mechanism for preventing a foreign matter from being caught in.
SUMMARY OF THE INVENTION
According to studies of the present inventors, as a mechanism for preventing a foreign matter from being caught in a power window of an automobile, there is given a pressure sensitive sensor structured such that a pair of conductive bodies comprising conductive rubbers are disposed integrally to a tube body (glass run) made of a rubber material fixed on an inner peripheral edge of a window frame and are disposed to be spaced slightly from each other in an opposing manner in a hollow portion of the glass run, and the conductive rubbers are brought into contact with each other to be made conductive to each other due to external force that acts on the glass run in a direction of compression thereof, so that a detection signal is output. Such a pressure sensitive sensor stops a motor for ascending/descending a window glass when detecting a foreign matter.
However, in a case that the pressure sensitive sensor is configured by providing the conductive rubbers integrally in the glass run made of a rubber material, when the electrical resistance value of the conductive rubber is increased due to aging, there may be a possibility that the detection sensitivity of the pressure sensitive sensor is affected.
Particularly, it is assumed that EPDM (Ethylene Propylene Terpolymer) is used as a rubber material of an ethylene-propylene copolymer for the glass run which structures a hollow base body for the pressure sensitive sensor, as it has an excellent slide-guiding performance for the window glass because of a low friction coefficient as well as a high weather resistance and a resiliency, while it is assumed that a material prepared by mixing carbon particles into a silicone rubber, as a main material, having an excellent insulation is used as the conductive rubber. Paraffin oil and naphthenic oil, which are plasticizers of the EPDM, have a solubility parameter (SP value) of about 7 to 8, while the silicone rubber having SP value of 7.3. That is, the SP value of the plasticizer of the rubber material constituting the hollow base body for the pressure sensitive sensor is approximately equal to that of the conductive rubber. Thus, when both the SP values are approximately equal to each other, there is a possibility that the plasticizer contained in the rubber material constituting the hollow base body for the pressure sensitive sensor bleeds to be moved in the conductive rubber due to heat of the atmosphere, and the conductive rubber swells to increase distances between the carbon particles, which results in conductivity failure. This is considered to possibly cause change in sensitivity of the pressure sensitive sensor.
The present invention has been attained in view of the above studies, and is to provide a pressure sensitive sensor which can maintain an excellent detection sensitivity for a long time without change in its electrical resistance value due to the heat of the atmosphere, and a method for manufacturing the same.
A pressure sensitive sensor according to the present invention comprises: a hollow base body made by use of a rubber material and having a hollow portion; a pair of electrically conductive bodies, at least one of which is made by use of an electrically conductive rubber material, disposed so as to be opposed to each other with a predetermined distance in the hollow portion of the hollow base body; and a plasticizer blocking layer which is provided between the hollow base body and the pair of electrically conductive bodies and which is made by use of a resin material having a different solubility parameter from that of a plasticizer in the hollow base body. Here, the pressure sensitive sensor becomes electrically conductive when the pair of the electrically conductive bodies come in contact with each other.
In other words, the pressure sensitive sensor in accordance with the present invention comprising: a hollow base body made by use of a rubber material and having a hollow portion; a pair of electrically conductive bodies, at least one of which is made by use of an electrically conductive rubber material, disposed so as to be opposed to each other with a predetermined distance in the hollow portion of the hollow base body; and a plasticizer blocking means disposed between the hollow base body and the pair of electrically conductive bodies, for blocking a plasticizer in the hollow base body from immigrating to the pair of electrically conductive bodies.
On the other hand, a method for manufacturing of a pressure sensitive sensor in accordance with the present invention comprises the steps of: preparing a hollow base body made by use of a rubber material and having a hollow portion; disposing a pair of electrically conductive bodies, at least one of which is made by use of a conductive rubber material, so as to be opposed to each other with a predetermined distance in the hollow portion of the hollow base body; and providing a plasticizer blocking layer, made by use of a resin material having a different solubility parameter from that of a plasticizer in the hollow base body, between the hollow base body and the pair of electrically conductive bodies.
REFERENCES:
patent: 4773183 (1988-09-01), Okushima et al.
patent: 4970446 (1990-11-01), Yaguchi
patent: 5166586 (1992-11-01), Yaguchi
patent: 5616997 (1997-04-01), Jackson et al.
patent: 5712620 (1998-01-01), Greenwood
patent: 5754017 (1998-05-01), Tsuge et al.
patent: 5880421 (1999-03-01), Tsuge et al.
patent: 9-209615 (1997-08-01), None
Ikuta Kenichi
Shigematsu Satoshi
Takamiya Takeomi
McDermott & Will & Emery
Nissan Motor Co,. Ltd.
Oen William
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