Load sensor, load sensor unit and insertion detection device

Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen

Reexamination Certificate

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Details

C073S824000

Reexamination Certificate

active

06606914

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a load sensor, a load sensor unit, and an insertion detection device.
2. Description of the Related Art
A technique is available for a load sensor mounted within an automobile seat, such as a driver's seat, for detecting the presence of a seated person. An example, conventional load sensor of this type is shown in FIG.
52
.
In the example, pressure sensors A
1
to A
4
, B
1
to B
4
, C
1
to C
4
, D
1
to D
4
and E
1
to E
4
are located at the intersections of vertical axes
1
to
4
and horizontal axes A to E in a sheet S disposed within a seat. A controller
5
determines from pressure detection results, provided by the pressure sensors A
1
to A
4
, B
1
to B
4
, C
1
to C
4
, D
1
to D
4
and E
1
to E
4
, whether the seat is bearing a load, and transmits the load determination results to a predetermined driver
6
. Pressure sensitive conductive material, having a resistance that varies in accordance with the pressure applied, is employed for the pressure sensors A
1
to A
4
, B
1
to B
4
, C
1
to C
4
, D
1
to D
4
and E
1
to E
4
.
For the load sensor in
FIG. 52
, the pressure sensors A
1
to A
4
, B
1
to B
4
, C
1
to C
4
, D
1
to D
4
and E
1
to E
4
, made of pressure sensitive conductive material, must be arranged as a matrix. Further, in order to detect pressure imposed at various points on the sheet S, multiple pressure sensors, A
1
to A
4
, B
1
to B
4
, C
1
to C
4
, D
1
to D
4
and E
1
to E
4
, are required. Thus, the resulting circuit is complicated, and the manufacturing costs are increased.
SUMMARY OF THE INVENTION
It is, therefore, one objective of the present invention to provide a load sensor, having a comparatively simple and inexpensive configuration and circuit structure, that can easily and accurately detect loads.
To achieve the above object, it is characterized by comprising:
an elastic tube, at least one part of which, in the circumferential direction, is a conductive portion;
an elongated insertion member that has longitudinally arranged first and second electrode members provided at a distance, and that is inserted into the elastic tube; and
envelope members that are provided longitudinally, at a predetermined distance, to enclose the insertion member, and that, together with the insertion member, are inserted into the elastic tube to separate the insertion member from the elastic tube,
wherein, while the elastic tube is in the normal state, the first and the second electrode members are so positioned, at a distance from the conductive portion of the elastic tube, that when an external load bends the elastic tube an electrical connection is established between the first and the second electrode members, with or without the conductive portion of the elastic tube.
Further, to achieve the objective, it is characterized by comprising:
an elastic tube, at least one part of which, in the circumferential direction, is a conductive portion;
an elongated insertion member that has longitudinally arranged electrode members provided at a distance, and that is inserted into the elastic tube; and
envelope members that are provided longitudinally, at a predetermined distance, to enclose the insertion member, and that, together with the insertion member, are inserted into the elastic tube to separate the insertion member from the elastic tube,
wherein, while the elastic tube is in the normal state, the electrode members are so positioned, at a distance from the conductive portion of the elastic tube, that when an external load bends the elastic tube an electrical connection is established between the electrode members and the conductive portion of the elastic tube, with or without the conductive portion of the elastic tube.
Preferably, for the envelope members, at least, one of the separating interval, the thickness, and the width in the longitudinal direction is set in accordance with the magnitude of the load that is to be detected.
Preferably, the envelope members are formed of insulating material.
Further, it is preferable that the envelope members be ring-shaped and externally engage the outer wall of the insertion member.
It is preferable that the envelope members be secured to the insertion member by an adhesive.
Preferably, the envelope members are thermally shrinking tubes.
Preferably, the envelope members are formed by winding insulating tape around the insertion member.
Preferably, the insulating tape is spirally and continuously wound around the insertion member in the longitudinal direction with a predetermined gap.
It is preferable that the envelope members each include a metal fixing member, attached via a predetermined insulating member to the outer wall of the insertion member, and a coated insulating member, fixed to and covering the outer wall of the metal fixing member.
It is preferable that the envelope members each include a metal fixing member, attached to the outer wall of the insertion member, and a coated insulating member, fixed to and covering the outer wall of the metal fixing member.
It is preferable that the insertion member includes, on the outer wall on which the first and the second electrode members are provided, the first and the second electrode members and an elastic insulating member.
Preferably, the load sensor further comprises a signal extraction output line that is electrically connected to the conductive portion of the elastic tube when the conductive portion, wound around the outer walls of the envelope members, is inserted into one end of the elastic tube.
In addition, preferably, the electrode members are formed of elastic conductive members through which hollow, longitudinal portions passes.
It is preferable that the conducive members be made of an elastic conductive material, a conductive metal, a compound material composed of an elastic conductive material and a conductive metal, or a compound material composed of a conducive metal and an insulating material.
It is preferable that the load sensor further include an exterior elastic tube enclosing the elastic tube.
Further, it is preferable that the load sensor include a load sensor body incorporating the elastic tube, the insertion member and the envelope member, and a substantially plate-shaped base member whereon the load sensor body is mounted.
It is preferable that the load sensor include a load sensor body incorporating the elastic tube, the insertion member and the envelope member, and two plate-shaped pressing members for vertically sandwiching and securing the load sensor body.
It is preferable that the electrode members be fashioned from flexible members, and that the electrode members constitute the insertion member.
Preferably, the electrode members have metal, longitudinally laid lines.
Preferably, the electrode members each include an elongated flexible core member and a metal line wound coil-like around the outer wall of the core member.
It is preferable that the core member be an insulating member of resin, rubber or a fibrous material, or a compound material incorporating several of these materials.
Preferably, the core member is formed of an elastic material, and the metal line is wound around and embedded in the outer wall of the core member.
It is preferable that a spiral groove into which the metal line is to be fitted is formed in the outer wall of the core member, and that the metal line is fitted into the groove when wound around the core member.
It is preferable that anticorrosive metal be employed for the metal line.
Preferably, the envelope members are integrally formed by molding resin or rubber on the outer wall of the electrode member.
Preferably, the sensitivity of the load sensor used to detect the load is adjusted by altering, at least, one of the interval between the envelope members for enclosing the electrode member, the width in the longitudinal direction of the electrode member, the distance between the metal, coil-like wound line and the elastic tube, the thickness of the elastic tube, and the outer diameter of the elastic t

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