JP2012014974A - Flat circuit body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light and inexpensive flat circuit body with excellent bending durability.SOLUTION: The flat circuit body 1 comprises an odd number of first flat conductors 3, a plurality of second flat conductors 4 having a width narrower than that of the first flat conductor 3, and an insulating coating 6 integrally coating the first flat conductors 3 and the plural second flat conductors 4 in parallel to each other at appropriate intervals on a flat surface. The first flat conductors 3 are arranged across a centerline C1 with a width of the insulating coating 6.

Description

  The present invention relates to a flat circuit body used for electrical wiring of an electric device or an automobile.

  FIG. 6 shows a general structure of the flat circuit body. The illustrated flat circuit body 101 includes a plurality of flat conductors 103 and an insulating coating 104 that collectively covers the plurality of flat conductors 103 in parallel with each other in a state of being arranged on a plane at an appropriate interval. It is a configuration.

  Such a flat circuit body 101 is suitable for space saving and weight reduction of wiring. In addition, it is easier to bend than a round cable or coaxial cable in which a plurality of covered electric wires are formed into a single wire bundle having a circular cross section, and is therefore used for routing to movable parts such as vehicle doors and reclining seats. There are many things.

  However, when used for routing to the movable part, it is important to increase the bending durability so that the circuit body is not cracked or disconnected due to repeated bending operations accompanying the movement of the movable part.

  Therefore, as a technique for improving the bending durability in the flat circuit body 101 described above, the following Patent Document 1 discloses an insulating coating 104 in which the composition of the resin material is adjusted so that the flexural modulus is 200 MPa or more and less than 800 MPa. A technique for forming the above has been proposed.

  Generally, in the flat circuit body 101, when the bending elastic modulus of the insulating coating 104 is increased, the bending rigidity is increased and the flexibility is lost. For this reason, if a bending wrinkle is formed during the bending operation, stress concentration occurs in the portion, and the conductor 103 is likely to be cracked, resulting in a decrease in bending durability. On the other hand, if the flexural modulus is reduced, the flexibility increases and bending with a small curvature is possible. However, since the rigidity is low, the conductor 103 is buckled at the bent portion, and disconnection is likely to occur. , Leading to a decrease in bending durability.

  The technique of the above-mentioned Patent Document 1 adjusts the composition of the resin material that forms the insulating coating 104, so that the flexural modulus of the insulating coating 104 is neither large nor small, and appropriate flexibility and bending rigidity. The bending durability is improved by adjusting to an appropriate range.

JP 2008-123755 A

  However, when the bending durability of the flat circuit body 101 is improved by the technique described in Patent Document 1, a resin material that has been expensive due to composition adjustment or the like is used, which causes an increase in the manufacturing cost of the flat circuit body. Occurred.

  In addition, in order to obtain a desired flexural modulus, it is often necessary to increase the thickness of the insulating coating 104 to a certain level or more, and increasing the thickness of the insulating coating 104 may lead to an increase in the weight of the flat circuit body. There was also.

  Accordingly, an object of the present invention is to provide a flat circuit body that is lightweight and inexpensive and has excellent bending durability in solving the above-described problems.

The above-described object of the present invention is achieved by the following configuration.
(1) An odd number of first flat conductors having a rectangular shape with a flat cross section and a plurality of second flat shapes having a flat rectangular cross section and a width smaller than that of the first flat conductor. A conductor, and an insulating coating that covers the odd number of first flat conductors and the plurality of second flat conductors in parallel with each other in a state of being arranged on a plane at appropriate intervals,
A flat circuit body, wherein the first flat conductor is disposed so as to straddle a center line of the width of the insulating coating.

  (2) An even number of the second flat conductors having the same width dimension are provided, and the first flat conductor and the second flat conductor are axisymmetric with respect to the center line of the width of the insulating coating. The flat circuit body according to (1) above, wherein

  When the flat circuit body is bent, the stress distribution acting on the flat circuit body is greatest in the central region across the center line of the width of the insulating coating. Therefore, high bending strength is required near the center in the width direction of the flat circuit body. Further, for example, when twisting or the like is applied when bent, the bending radius may be smaller near the end in the width direction of the flat circuit body than near the center in the width direction. Therefore, it is required to ensure flexibility so that the end in the width direction of the flat circuit body can be bent with a small curvature.

  According to the configuration of the above (1), the central region straddling the center line of the width of the insulating coating has the first flat conductor having a wide width, and has higher strength than the resin forming the insulating coating. Since the ratio of the flat conductor is increased, high bending strength is ensured. In addition, in the vicinity of both ends of the width of the insulating coating, the width of the second flat conductor disposed is narrower than that of the first flat conductor and there are many resin portions having low strength, so that the bending strength is in the width direction. It becomes lower than the vicinity of the center, and the flexibility becomes higher than the vicinity of the center in the width direction.

  Therefore, physical properties (bending characteristics) suitable for bending can be obtained in each of the central region and the end in the width direction of the flat circuit body. Therefore, even if the bending operation is repeated, the circuit body is less likely to be broken or disconnected, and a flat circuit body having excellent bending durability can be provided.

  And since the physical properties suitable for bending as described above are obtained by devising the arrangement of the first flat conductor and the second flat conductor, the use of a thickened or expensive resin material for the insulation coating The bending durability can be improved without depending on the above.

  Therefore, it is possible to provide a flat circuit body that is light and inexpensive and excellent in bending durability.

  According to the configuration of (2) above, the flat conductor functioning as a strength member is arranged symmetrically with respect to the center line of the width of the insulation coating, so when bent, in either direction on the left or right side, The bending strength without a difference can be exhibited, and the bending durability in the flat circuit body 1 can be further improved.

  According to the flat circuit body of the present invention, a high bending strength is ensured in the central region straddling the center line of the width of the insulation coating as compared with the both ends of the insulation coating by the wide first flat conductor. Further, the vicinity of both end portions of the width of the insulating coating is more flexible than the vicinity of the center in the width direction because there are more resin portions than in the center region. Therefore, physical properties (bending characteristics) suitable for bending can be obtained in each of the central region and the end of the flat circuit body in the width direction.

  Therefore, bending durability can be improved without relying on the use of thickened or expensive resin materials for the insulation coating. Therefore, it is possible to provide a flat circuit body that is light and inexpensive and excellent in bending durability.

1 is a perspective view of a first embodiment of a flat circuit body according to the present invention. It is an enlarged view of the cross section of the flat circuit body shown in FIG. It is a perspective view of the bending state of the flat circuit body shown in FIG. It is an enlarged view of the cross section of 2nd Embodiment of the flat circuit body which concerns on this invention. It is a cross-sectional view of the flat circuit body used as the comparative example with 1st Embodiment. It is a cross-sectional view of a conventional flat circuit body.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a flat circuit body according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view of a first embodiment of a flat circuit body according to the present invention, and FIG. 2 is an enlarged cross-sectional view of the flat circuit body shown in FIG.

  The flat circuit body 1 of the first embodiment includes a first flat conductor 3 having a rectangular shape with a flat cross section, and a rectangular shape having a flat cross section and a narrower width than the first flat conductor 3. Insulation in which two second flat conductors 4 and these first flat conductors 3 and two second flat conductors 4 are collectively covered in parallel with each other on a plane at an appropriate interval. And a coating 6.

  In the first embodiment, as shown in FIG. 2, the width of the first flat conductor 3 is w1, the width of the second flat conductor 4 is w2, and the distance between the flat conductors (resin The width dimension of the layer only portion is w3. In the case of the first embodiment, the width dimension w2 of the second flat conductor 4 is set to a narrow width equal to or less than ½ of the width dimension w1 of the first flat conductor 3, but the value of w2 Can be appropriately set within the range where w1> w2.

  In the first embodiment, the two second flat conductors 4 have the same width dimension. As shown in FIG. 2, the first flat conductor 3 is disposed at the center in the width direction so as to straddle the center line C <b> 1 of the width of the insulating coating 6, and the first flat conductor 3 is disposed on both sides of the first flat conductor 3. Two flat conductors 4 are arranged. More specifically, the first flat conductor 3 and the second flat conductor 4 are arranged symmetrically with respect to the center line of the width of the insulating coating 6.

  Each of the flat conductors 3 and 4 is formed of a copper material such as oxygen-free copper, tough pitch copper, or phosphor bronze. The copper material may be soft or hard. These copper materials may be plated with metal such as tin or nickel. The thickness of the flat conductors 3 and 4 is not particularly limited, but is usually set to about 0.02 to 0.5 mm.

  The insulating coating 6 does not have to limit the material composition or the like particularly with a flexural modulus or the like, and various resin materials and rubber materials that have been conventionally used for insulating coatings of flat circuit bodies can be used. The resin material used for the insulating coating may be a synthetic resin or a natural resin, but preferably a thermoplastic resin is used.

  In general, in the flat circuit body 1, as shown in FIG. 3, when the flat circuit body 1 is bent into a U shape, the stress distribution acting in the flat circuit body 1 at the bent portion is the width of the insulating coating 6. It becomes the largest in the central region R1 straddling the center line C1. Therefore, high bending strength is required near the center in the width direction of the flat circuit body 1. Further, for example, when twisting or the like is applied when bent, the bending radius may be smaller in the vicinity of the end portions R2 and R3 in the width direction of the flat circuit body 1 than in the vicinity of the center in the width direction. Therefore, it is required to ensure flexibility so that the end portions R2 and R3 in the width direction of the flat circuit body 1 can be bent with a small curvature.

  In the flat circuit body 1 of the first embodiment described above, the wide first flat conductor 3 is arranged in the central region R1 straddling the center line C1 of the width of the insulating coating 6, and the insulating coating 6 Since the ratio of the flat conductor having higher strength than the resin being formed is increased, a high bending strength is ensured. Further, in the vicinity of both end portions R2 and R3 of the width of the insulating coating 6, the width of the second flat conductor 4 arranged is narrower than that of the first flat conductor 3, and there are many resin portions with low strength. The bending strength is lower than that in the vicinity of the center in the width direction, and the flexibility is higher than that in the vicinity of the center in the width direction.

  Accordingly, physical properties (bending characteristics) suitable for bending can be obtained in the vicinity of the center in the width direction and the end of the flat circuit body 1. Therefore, even if the bending operation is repeated, the circuit body is less likely to be broken or disconnected, and the flat circuit body 1 having excellent bending durability can be provided.

  Since the physical properties suitable for bending as described above are obtained by devising the arrangement of the first flat conductor 3 and the second flat conductor 4, the insulating coating 6 is made thicker and expensive. The bending durability can be improved without depending on the use of the material.

  Therefore, it is possible to provide the flat circuit body 1 that is light and inexpensive and excellent in bending durability.

  Next, a second embodiment of the present invention will be described. FIG. 4 is an enlarged cross-sectional view of a second embodiment of the flat circuit body according to the present invention.

  The second embodiment differs from the first embodiment in the number of first flat conductors 3 in the flat circuit body 1. Since other configurations are the same, the same reference numerals as those in the first embodiment are given in FIG.

  The first embodiment includes one first flat conductor 3, but the second embodiment includes three first flat conductors 3. In the second embodiment, the center first flat conductor 3 of the three first flat conductors 3 arranged in the center in the width direction so as to straddle the center line C1 of the width of the insulating coating 6. It is arranged in the part.

  The second embodiment also has the same effect as the first embodiment. As in the above embodiments, the number of first flat conductors 3 is an odd number. In the present invention, the number of first flat conductors 3 may be an odd number of 1 or more.

  In order to evaluate the degree of improvement in the bending durability of the flat circuit body 1 of the first embodiment described above, the flat circuit body 10 shown in FIG. Tested.

  The flat circuit body 10 of the comparative example has a basic configuration in which one first flat conductor 3 and two second flat conductors 4 are covered with an insulating coating 6 according to the flat configuration of the first embodiment. The circuit body 1 is common. However, in the case of the flat circuit body 10, the first flat conductor 3 is not disposed so as to straddle the center line C <b> 1 having the width in the insulating coating 6, but is disposed near one side of the center line C <b> 1. The two second flat conductors 4 are disposed on the opposite side of the first flat conductor 3 with the center line C1 interposed therebetween, and the first flat conductor 3 and the second flat conductor 4 are disposed. The conductors 4 are not arranged symmetrically with respect to the center line C1 as in the first embodiment.

  As a result of the durability test, the case of the flat circuit body 1 of the first embodiment was 180,000 times, and the case of the flat circuit body 10 of the comparative example was 85,000 times. Therefore, it was confirmed that the flat circuit body 1 of 1st Embodiment has improved the durability 2 times or more with respect to the flat circuit body 10 of a comparative example.

  Further, in the flat circuit body 1 of the first embodiment, the flat conductor functioning as a strength member is arranged symmetrically with respect to the center line C1 of the width of the insulating coating 6, so that it can be bent in any direction left and right However, the bending strength without a difference can be exhibited, and the bending durability in the flat circuit body 1 can be further improved.

  The flat circuit body of the present invention is not limited to the above-described embodiments, and appropriate modifications and improvements can be made.

  For example, in the flat circuit body according to the present invention, the number of second flat conductors arranged in parallel with the first flat conductor is not limited to the above embodiment. The number of the second flat conductors provided in the flat circuit body can be set to an arbitrary number of three or more. It is desirable that the number of second flat conductors be an even number and be arranged symmetrically with respect to the center line C1 of the width of the insulation coating. However, the arrangement of the second flat conductor is the center line of the width of the insulation coating. A non-axisymmetric arrangement with respect to C1 is also conceivable.

  In the above embodiment, the plurality of second flat conductors have the same width, but a plurality of second flat conductors having different width dimensions may be provided.

DESCRIPTION OF SYMBOLS 1 Flat circuit body 3 1st flat conductor 4 2nd flat conductor 6 Insulation coating C1 Centerline R1 Center area

Claims (2)

An odd number of first flat conductors having a rectangular shape with a flat cross-section, and a plurality of second flat conductors having a flat cross-sectional shape and a narrower width than the first flat conductor, An insulation coating that covers the odd number of first flat conductors and the plurality of second flat conductors in parallel with each other in a state of being arranged on a plane at appropriate intervals;
A flat circuit body, wherein the first flat conductor is disposed so as to straddle a center line of the width of the insulating coating.   An even number of the second flat conductors having the same width dimension are provided, and the first flat conductor and the second flat conductor are arranged symmetrically with respect to the center line of the width of the insulating coating. The flat circuit body according to claim 1.

Images