JP2006172730A - Load sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a load sensor preventing erroneous detection from occurring even when a membrane switch is arranged on a curved surface having a small radius of curvature. <P>SOLUTION: This load sensor comprises a headrest 1 and a membrane switch 2. The membrane switch 2 is formed by stacking insulation films by interlaying a spacer, and has a bridge part 28 linearly extending by straddling a plurality of cells 27 arranged on straight lines; and the bridge part 28 is so mounted to the headrest 1 as to be arranged on the curved surface 11 of the headrest 1 in a direction generating the least flexure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a load sensor using a membrane switch in which conductive patterns facing each other come into contact with each other when a load in the thickness direction is applied, and more particularly to a load sensor that prevents occurrence of malfunction.

Conventionally, a seating sensor in which a seating state is detected by installing a membrane switch in a seat of an automobile, an aircraft, a backrest or the like is known (Patent Document 1). As shown in FIG. 7, the membrane switch is configured by polymerizing a pair of flexible sheets 101 and 102 via an insulating spacer 103. Conductive patterns 104 and 105 are formed on the opposing surfaces of the flexible sheets 101 and 102, respectively. An opening 106 is formed at a predetermined position of the insulating spacer 103, and the conductive patterns 104 and 105 above and below the opening 106 form a cell (contact part) 107. When a load in the thickness direction of the flexible sheets 101 and 102 is applied to the cell 107, the conductive patterns 104 and 105 come into contact with each other through the opening 106. Therefore, the presence or absence of the load is determined by detecting the current flowing through the contact. can do.
JP 2002-326554 A (paragraph 0008, FIG. 8)

  By the way, it is conceivable to use such a membrane switch as a load sensor for an automobile headrest, but the membrane switch constitutes a load sensor along the surface of a support having a curved surface with a small curvature radius like the headrest of an automobile. 8, the membrane switch is bent along the curved surface, and there is a problem that the upper and lower conductive patterns are conducted due to slight vibration, skin contraction, urethane deformation, and the like, and erroneous detection occurs.

  The present invention has been made in view of these points, and provides a load sensor that does not cause erroneous detection even when a membrane switch is arranged on a curved surface having a small curvature radius such as a headrest. For the purpose.

  The load sensor according to the present invention is formed by polymerizing a pair of flexible insulating films via a spacer, and a conductive pattern is formed on each of the opposing surfaces of the pair of insulating films. An opening is formed at a predetermined position, and a cell is formed by the opening and the conductive pattern above and below the opening. When a load in the thickness direction is applied to the insulating film in the cell, the conductive patterns facing each other at the position of the cell In a load sensor having a membrane switch in contact with each other and a support having a curved surface on which the membrane switch is mounted, the membrane switch is arranged in a straight line across the plurality of cells arranged in a straight line and these cells. A bridge portion made of a conductive pattern extending, and the bridge portion has the least deflection on the curved surface of the support. Characterized in that it is mounted on said support so as to be disposed in the gas.

  In one embodiment of the present invention, a plurality of the bridge portions are arranged in a direction orthogonal to the extending direction, and the membrane switch has one end side of the plurality of bridge portions extending in the extending direction of the bridge. This bending absorbing portion has a connecting portion made of a conductive pattern connected in an orthogonal direction, and one end of this connecting portion is extended to prevent bending propagation to the connecting portion made of a conductive pattern. The terminal part is formed through

  In this case, it is desirable that the insulating films on which the plurality of bridge portions are respectively formed are separated from each other except for an end portion connected to the connecting portion.

  According to the present invention, since the bridge portion extending linearly across the plurality of cells is arranged in the direction of least bending on the curved surface of the support, bending that causes malfunction in the cell occurs. This improves the reliability of the load sensor.

  According to the aspect in which the bending absorbing portion is formed at one end of the connecting portion that connects the plurality of bridges, the bending absorbing portion absorbs the distortion even when the pulling force is applied from the terminal portion side, and is bent to the connecting portion. Since propagation is prevented, it is possible to effectively prevent the bridge portion from being bent, and it is possible to improve the reliability as a load sensor.

  In addition, when the plurality of bridge portions are separated from each other except for the end portion connected to the coupling portion as described above, the bending generated in each bridge portion does not propagate to other bridge portions, and the bridge portion Can be more effectively prevented, and the reliability as a load sensor can be improved.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a front view showing an example in which the load sensor according to the first embodiment of the present invention is applied to a headrest of an automobile, and FIG. 2 is a side view of the same.

  The load sensor includes a headrest 1 as a support and a membrane switch 2 arranged along a curved surface in front of the headrest 1.

  The headrest 1 is made of a cushion material such as urethane that receives the head of the passenger. In this example, the head receiving surface 11 of the passenger forms a bowl-shaped curved surface that is curved in the vertical direction.

  The membrane switch 2 is configured by superposing a pair of flexible sheets 21 and 22 through an insulating spacer 23 as shown in an exploded perspective view of a part of FIG. Conductive patterns 24a, 24b, and 25 are formed on the opposing surfaces of the flexible sheets 21 and 22, respectively. In this example, the conductive patterns 24a and 24b are parallel line patterns that are insulated from each other, and the conductive pattern 25 is a circular isolated pattern that short-circuits these parallel line patterns. An opening 26 is formed at a predetermined position of the insulating spacer 23, and the conductive patterns 24 a, 24 b, and 25 above and below the opening 26 form a cell (contact part) 27. When a load in the thickness direction of the flexible sheets 21 and 22 is applied to the cell 27, the conductive patterns 24 a and 24 b and the conductive pattern 25 come into contact with each other through the opening 26. The presence or absence of a load can be determined by detecting a current short-circuited by the pattern 25 and flowing between them.

  In this membrane switch 2, as shown in FIG. 1, three cells 27 are arranged in a straight line in the horizontal direction, and the conductive patterns 24a and 24b are bridges 28 formed so as to straddle the cells 27 in the horizontal direction. Is forming. Three bridges 28 are arranged in the vertical direction, and one end portion thereof is connected by a connection portion 29 extending in the vertical direction. A lower end portion of the connecting portion 29 is extended toward the central portion to form a bending absorbing portion 30 made of a conductive pattern. An end portion 31 is formed through the bending absorbing portion 30. It is further desirable that the flexible sheets 21 and 22 and the insulating spacer 23 have a lateral comb-like outer shape along the bridge 28, the connecting portion 29, the bending absorbing portion 30, and the end portion 31.

  By adopting such a shape and arrangement of the membrane switch 2, only the connecting portion 29 is curved by the influence of the curved surface in the vertical direction of the head receiving surface 11 of the headrest 1, and the bridge 28 that straddles the cell 27 is hardly used. Does not bend. For this reason, there is almost no occurrence of erroneous contact. Further, according to this embodiment, even when the terminal portion 31 is pulled from the lower side, only the bending absorbing portion 30 bends and the bending does not propagate to the connecting portion 29. For this reason, it is possible to effectively prevent the bridge 28 from being bent due to the presence of the bending absorbing portion 30 even against a pulling force from the terminal portion 31 side.

  As shown in FIG. 4, such a load sensor is applied to a seat 42 with a movable headrest function having a drive unit 41 that drives the headrest 1, and the head 44 of the occupant 43 and the headrest 1. By detecting the contact and stopping the movement of the headrest 1, it can be used in a system that stops the headrest 1 at the optimum position.

  FIG. 5 is a front view showing a load sensor according to the second embodiment of the present invention, and FIG. 6 is a plan view seen from the same top surface.

  In the previous embodiment, the headrest 1 was a saddle shape curved in the vertical direction, but in this embodiment, the headrest 5 has a head receiving surface 51 curved in the lateral direction with the central portion as a recess, A membrane switch 6 is mounted along the head receiving surface 51.

  In this embodiment, a plurality of cells 67 constituting the membrane switch 6 are arranged in the vertical direction, and a bridge 68 extending in the vertical direction is formed so as to straddle the cells 67. The connection part 69 and the terminal part 71 are formed in the lower end part. The outer shape of the membrane switch 6 is an upward comb-teeth shape.

  In this embodiment, the bridge portion 68 is disposed in the longitudinal direction where the bending of the headrest 5 is gentle, so that the bridge portion 68 is not easily bent and the malfunction of the cell 67 does not occur.

  In the above, the load sensor of the present invention is applied to the headrest, but it goes without saying that the support may be any load sensor as long as the membrane switch is attached to the support having a curved surface. .

It is a front view showing a schematic structure of a load sensor concerning a 1st embodiment of the present invention applied to a headrest. It is a side view of the load sensor. It is a perspective view which decomposes | disassembles and shows a part of membrane switch of the load sensor. It is a figure which shows the example of application of the same load sensor. It is a front view which shows schematic structure of the load sensor which concerns on the 2nd Embodiment of this invention applied to the headrest. It is the top view seen from the upper surface of the load sensor. It is a perspective view partly cut and showing the configuration of a conventional membrane switch. It is an expanded sectional view of the cell part of the conventional membrane switch.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,5 ... Headrest, 2,6 ... Membrane switch, 27, 67 ... Cell, 28, 68 ... Bridge part, 29, 69 ... Connection part, 30 ... Bending absorption part, 31, 71 ... Terminal part.

Claims (3)

It is formed by polymerizing a pair of flexible insulating films through a spacer, and conductive patterns are formed on the opposing surfaces of the pair of insulating films, respectively, and an opening is formed at a predetermined position of the spacer. A membrane switch in which a cell is formed by the opening and the conductive pattern above and below the opening, and when the load in the thickness direction is applied to the insulating film in the cell, the conductive patterns facing each other at the position of the cell are in contact with each other,
In a load sensor having a support having a curved surface on which the membrane switch is mounted,
The membrane switch has a plurality of the cells arranged on a straight line and a bridge portion made of a conductive pattern extending linearly across the cells, and the bridge portion is most bent on the curved surface of the support. The load sensor is mounted on the support so as to be arranged in a direction with less. A plurality of the bridge portions are arranged in a direction orthogonal to the extending direction,
The membrane switch has a connecting portion made of a conductive pattern that connects one end side of the plurality of bridge portions in a direction orthogonal to the extending direction of the bridge, and one end of the connecting portion is extended to form a conductive pattern. The load sensor according to claim 1, wherein a bending absorbing portion that prevents bending propagation to the connecting portion is formed, and a terminal portion is formed through the bending absorbing portion.   The load sensor according to claim 2, wherein the insulating films in which the plurality of bridge portions are respectively formed are separated from each other except for an end portion connected to the connecting portion.

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