[Title of the Invention]

WIRING MEMBER

[Technical Field]

[0001]

The present invention relates to a wiring member having a coaxial flat cable.

[Background Art]

[0002]

A coaxial cable harness in which end portions of plural coaxial cables are connected to a connection board(s) is known which is disclosed in Patent Document 1.

[Prior Art Documents]

[Patent Documents]

[0003]

[Patent Document 1] JP-5353634-B

[Summary of the Invention]

[Problems to be Solved by the Invention]

[0004]

Further miniaturization of cable harnesses (wiring members) is now demanded, and the wiring member of Patent Document 1 has room for further miniaturization.

An object of the present invention is therefore to provide a wiring member having compact end portions.

[Means for Solving the Problems]

[0005]

A wiring member according to the invention includes:

a coaxial flat cable including:

plural coaxial cables each having a center conductor, an inner insulator formed on an outer circumferential surface of the center conductor, an outer conductor formed on an outer circumferential surface of the inner insulator, and an outer sheath formed on an outer circumferential surface of the outer conductor; and a resin film which is bonded to the plural coaxial cables from at least one of the two sides of an arrangement plane of the plural coaxial cables to maintain a parallel arrangement of the plural coaxial cables; and

a connection board connected to at least one end portion, in its longitudinal direction, of the coaxial flat cable, wherein:

the connection board has plural unit terminal groups each including two straight signal terminal members to which the center conductors of two coaxial cables are soldered, respectively, and one straight ground terminal member which is electrically connected to the outer conductor of at least one coaxial cable;

in each of the plural unit terminal groups, the two signal terminal members and the one ground terminal member are arranged in this order in a direction that is perpendicular to an extending direction of the signal terminal members;

the signal terminal members and the ground terminal members extend in a direction that is perpendicular to an arrangement direction of the unit terminal groups; an arrangement pitch of the two signal terminal members of each of the unit terminal groups is equal to a pitch PI of the two coaxial cables that are paired and connected to them; and

the resin film maintains the parallel arrangement of the plural coaxial cables in such a manner that a pitch P2 of two adjoining coaxial cables that are connected to adjoining unit terminal groups is set longer than the pitch PI .

[Advantages of the Invention]

[0006]

The invention provides a wiring member having compact end portions.

[Brief Description of the Drawings]

[0007]

[Fig. 1] A top view of a wiring member according to a first embodiment of the present invention.

[Fig. 2] A sectional view of a coaxial flat cable of the wiring member shown in Fig. 1. [Fig. 3] An enlarged top view of an end portion of the wiring member shown in Fig. 1. [Fig. 4] A side sectional view corresponding to Fig. 3.

[Fig. 5] Top views of a connection board used in the first embodiment and a connection board used in a comparative example, respectively.

[Fig. 6] A top view of each connection board of a wiring member according to a second embodiment of the invention.

[Fig. 7] Views of a connection board of a wiring member according to a third embodiment of the invention.

[Fig. 8] Aside sectional view of a wiring member according to a fourth embodiment of the invention.

[Modes for Carrying Out the Invention] [0008]

<Outline of embodiments of invention>

First, embodiments of the present invention will be outlined below.

(1) A wiring member according to one aspect of the invention includes:

a coaxial flat cable including:

plural coaxial cables each having a center conductor, an inner insulator formed on an outer circumferential surface of the center conductor, an outer conductor formed on an outer circumferential surface of the inner insulator, and an outer sheath formed on an outer circumferential surface of the outer conductor; and a resin film which is bonded to the plural coaxial cables from at least one of the two sides of an arrangement plane of the plural coaxial cables to maintain a parallel arrangement of the plural coaxial cables; and

a connection board connected to at least one end portion, in its longitudinal direction, of the coaxial flat cable, wherein:

the connection board has plural unit terminal groups each including two straight signal terminal members to which the center conductors of two coaxial cables are soldered, respectively, and one straight ground terminal member which is electrically connected to the outer conductor of at least one coaxial cable;

in each of the plural unit terminal groups, the two signal terminal members and the one ground terminal member are arranged in this order in a direction that is perpendicular to an extending direction of the signal terminal members;

the signal terminal members and the ground terminal members extend in a direction that is perpendicular to an arrangement direction of the unit terminal groups; an arrangement pitch of the two signal terminal members of each of the unit terminal groups is equal to a pitch PI of the two coaxial cables that are paired and connected to them; and

the resin film maintains the parallel arrangement of the plural coaxial cables in such a manner that a pitch P2 of two adjoining coaxial cables that are connected to adjoining unit terminal groups is set longer than the pitch PI .

[0009]

In the configuration of item (1), the pitch of the two signal terminal members of each unit terminal group is equal to the pitch of the two coaxial cables that are paired and soldered to them and the signal terminal members and the ground terminal members extend straightly in the direction that is perpendicular to the arrangement direction of the unit terminal groups. Therefore, the interval between adjoining ones of the signal terminal members and the ground terminal members of the connection board can be set equal to a minimum gap that is necessary for prevention of short-circuiting in soldering, over the length from one ends, in their longitudinal direction, of the signal terminal members and the ground terminal members to the other ends. This facilitates reduction of the dimension of each connection board in the arrangement direction of the unit terminal groups. Thus, the wiring member can be provided with more compact end portions.

[0010]

(2) The wiring member according to claim 1, portions of the outer sheaths exposed from an end of the resin film in its longitudinal direction are bonded to the connection board.

According to the configuration of item (2), the distance between the surface of the connection board and the exposed portions of the center conductors is made small, whereby the exposed portions of the center conductors can be soldered to the respective signal terminal members without deforming the exposed portions very much.

[0011]

(3) An end portion, in its longitudinal direction, of the resin film is bonded to the outer sheaths of the coaxial cables so as to be sandwiched between the connection board and the outer sheaths of the coaxial cables.

According to the configuration of item (3), the strength against bending of the coaxial cables that occurs when the coaxial flat cable is bent at the end of the connection board can be increased.

[0012]

(4) The coaxial cables are fixed to the connection board as a result of bonding of the end portion of the resin film to the connection board.

According to the configuration of item (4), the strength of connection between the coaxial flat cable and the connection board can be increased by the resin film.

[0013]

(5) Exposed portions of the outer conductors and further tip portions of the coaxial cables are covered with a protective film.

According to the configuration of item (5), short-circuiting between the conductors is prevented because the exposed portions of the outer conductors and the center conductors are protected by the protective film. Furthermore, peeling of the conductors is prevented.

[0014]

(6) The protective film is bonded so as to bridge the exposed portions of the outer conductors of the coaxial cables and the connection board.

According to the configuration of item (6), the strength of connection between the coaxial flat cable and the connection board can be increased by the protective film. [0015]

(7) The ground terminal members of the respective unit terminal groups are connected to each other at their portion near to the outer sheath of the coaxial cable by a pad portion, and the outer conductor of at least one of the coaxial cables is soldered to the pad portion.

According to the configuration of item (7), the pad portion facilitates establishment of electrical connection between the outer conductors and the ground terminal members.

[0016]

(8) The outer conductor of at least one of the coaxial cables is soldered to a ground bar which extends in the arrangement direction of the unit terminal groups, and the ground terminal members are electrically connected to the ground bar.

According to the configuration of item (8), a ground potential can be stabilized by grounding the outer conductors of the coaxial cables together by the ground bar.

[0017]

(9) The pitch P2 is equal to two times the pitch PI .

According to the configuration of item (9), the coaxial cables can be easily arranged in a plane in manufacturing the coaxial flat cable.

[0018]

(10) In the end portion of the coaxial flat cable, the outer conductor, the inner insulator and the center conductor are exposed in sequence in this order toward the tip of each of the coaxial cables, and portions of the center conductors exposed from the inner insulators are soldered to the respective signal terminal members of the connection board. According to the configuration of item (10), short circuiting between the center conductor and the outer conductor of each coaxial cable can be prevented.

[0019]

(11) Two resin films are bonded to the plural coaxial cables from the two respective sides of the arrangement plane of the coaxial cables.

According to the configuration of item (11), parallel arrangement of the coaxial cables can be firmly maintained.

[0020]

(12) The connection board has an additional ground terminal member which is adjacent to a signal terminal member located at an end in the arrangement direction of the unit terminal groups, and extends in the direction that is perpendicular to the arrangement direction of the unit terminal groups.

In the configuration of item (12), the signal terminal members are interposed between the ground terminal member and the additional ground terminal member in the arrangement direction of the unit terminal groups. Thus, the transmission characteristics of the wiring member can be enhanced.

[0021]

<Details of embodiments of invention>

Wiring members according to embodiments of the invention will be hereinafter described with reference to the drawings. However, the invention is not limited to these embodiments but encompasses any modifications that are made within the scope of the claims and equivalents thereof.

[0022]

<Embodiment 1>

A wiring member 1 according to a first embodiment is used for electrical connection of, for example, a board or a circuit. The wiring member 1 is suitable for transmission of differential signals.

[0023]

Fig. 1 is a top view of the wiring member 1 according to the first embodiment of the invention. As shown in Fig. 1, the wiring member 1 is equipped with a coaxial flat cable 10 extending in the longitudinal direction and connection boards 20 which are disposed adjacent to the two respective ends, in the longitudinal direction, of the coaxial flat cable 10.

[0024]

Fig. 2 is a sectional view of the coaxial flat cable 10 of the wiring member 1 shown in Fig. 1. As shown in Fig. 2, the coaxial flat cable 10 is equipped with plural (in the illustrated example, four) coaxial cables 30 and resin films 41 which are applied to the coaxial cables 30. Each coaxial cable 30 is a coaxial cable having an outer diameter 0.16 to 0.3 mm, for example.

[0025]

Each coaxial cable 30 is equipped with a center conductor 31, an inner insulator 32, an outer conductor 33, and an outer sheath 34. The inner insulator 32 is formed on the outer circumferential surface of the center conductor 31. The outer conductor 33 is formed on the outer circumferential surface of the inner insulator 32. The outer sheath 34 is formed on the outer circumferential surface of the outer conductor 33. The center conductor 31 is, for example, a metal wire made of copper, and may be a wire of AWG #42 to 47. Each of the inner insulator 32 and the outer sheath 34 is made of an insulative resin.

[0026]

The plural coaxial cables 30 are arranged in a plane. The resin films 41 are bonded to the coaxial cables 30 from the both sides of their arrangement plane and thereby maintain the parallel arrangement of the coaxial cables 30. For example, each resin film 41 is a polyethylene terephthalate film having a thickness of several micrometers to several tens of micrometers (preferably, 8 to 20 μπι). The resin films 41 are bonded to the outer sheaths 34 of the coaxial cables 30 with adhesive. Alternatively, only one resin film 41 may be bonded to the coaxial cables 30 from one side of their arrangement plane. In this embodiment, it is easy to firmly maintain the arrangement plane of the coaxial cables 30 because the resin films 41 are bonded to the coaxial cables 30 from the two sides of their parallel arrangement.

[0027]

Fig. 3 is an enlarged top view of an end portion of the wiring member 1 shown in Fig. 1. As shown in Fig. 3, a connection board 20 is connected to each end portion, in its longitudinal direction, of the coaxial flat cable 10.

In each end portion of the coaxial flat cable 10, every layers of the coaxial cables 30 are exposed from the resin films 41 in sequence. More specifically, the outer sheath 34 is exposed from the resin film 41, the outer conductor 33 is exposed from the outer sheath 34, the inner insulator 32 is exposed from the outer conductor 33, and the center conductor 31 is exposed from the inner insulator 32.

[0028]

For example, each connection board 20 is a flexible board or a hard board having wiring patterns made of metal foil or the like. Each connection board 20 is provided with plural unit terminal groups 21 each consisting of two signal terminal members 22 and one ground terminal member 23. The signal terminal members 22 and the ground terminal member 23 extend straightly in the longitudinal direction of the coaxial cables 30. Each signal terminal member 22 is electrically connected to the center conductor 31 of the corresponding coaxial cable 30. The ground terminal member 23 is electrically connected to the outer conductors 33 of the coaxial cables 30.

[0029]

In each unit terminal group 21, the exposed portions of the center conductor 31 of the pair of coaxial cables 30 are soldered to the two respective signal terminal members 22. Each signal terminal member 22 extends straightly in the longitudinal direction of the coaxial cable 30 whose center conductor 31 is connected to the signal terminal member 22.

In this embodiment, the end portion of each coaxial cable 30 is exposed in sequence, whereby the inner insulator 32 prevents the center conductor 31 and the outer conductor 33 from being short-circuited with each other there.

[0030]

The ground terminal members 23 extend in the same direction with the signal terminal members 22. End portions, close to the outer sheath 34, of the ground terminal members 23 extend closer to the outer sheath 34 than end portions of the signal terminal members 22. The ends, close to the outer sheath 34, of the plural ground terminal members 23 are connected to each other by a pad portion 25 which extends in the direction that is perpendicular to the longitudinal direction of the coaxial cables 30.

The exposed portion(s) of the outer conductor(s) 33 of at least one (in the illustrated example, all) of the outer conductor(s) of the coaxial cables 30 is soldered to the pad portion 25, whereby the outer conductor(s) is electrically connected to the ground terminal members 23 by the pad portion 25. The outer conductor(s) can easily be connected electrically to the ground terminal members 23 by the pad portion 25.

[0031]

Fig. 4 is a side sectional view corresponding to Fig. 3 and taken by a plane including the longitudinal direction of the coaxial cables 30, and shows the structure of the end portion and its neighborhood of a coaxial cable 30. As shown in Fig. 4, end portions of the outer sheaths 34 exposed from the ends of the resin films 41 in their longitudinal direction are bonded to the connection board 20 by adhesive 51. Since the exposed portions of the outer sheaths 34 are directly bonded to the connection board 20, the distance between the center conductor 31 of each coaxial cable 30 and the surface of the connection board 20 is short and hence the center conductor 31 can be soldered to the corresponding signal terminal member 22 with less bending of the coaxial cable 30.

The center conductors 31 are connected to the respective signal terminals 22 by solder 52. The outer conductors 33 are connected to the pad portion 25 by the solder 53.

[0032]

(Protective film)

The exposed portions of the outer conductors 33 and the further tip portions of the coaxial cables 30 are covered with a resin protective film 42. The protective film 42 is bonded so as to bridge the exposed portions of the outer sheaths 34 and the connection board 20 of the coaxial cables 30. The protective film 42 is bonded to the surface, provided with the coaxial cables 30, of the connection board 20. In this embodiment, the protective film 42 is bonded to cover the one resin film 41, the outer sheaths 34, the outer conductors 33, the inner insulators 32, the center conductors 31, and the connection board 20. The portions of the coaxial cables 30 exposed from the resin films 41 are protected by the protective film 42. The protective film 42 prevents a phenomenon that the center conductor 31 and the outer conductor 33 of a coaxial cable 30 are short-circuited with each other by a conductive substance attached to them or the tip portion of a coaxial cable 30 peels off the connection board 20.

[0033]

(Reinforcement film)

A resin reinforcement film 43 is bonded so as to bridge the other resin film 41 and the connection board 20. The reinforcement film 43 is bonded to the surface, opposite to the surface that is provided with the coaxial cables 30, of the connection board 20. The protective film 42 and the reinforcement film 43 increase the strength of the portion where the coaxial flat cable 10 and the connection board 20 are connected to each other.

Although the protective film 42 and the reinforcement film 43 are employed in this embodiment, they may be omitted.

[0034]

As shown in Fig. 3, in each of the plural (in the illustrated example, two) unit terminal groups 21 provided on the connection board 20, the two signal terminal members 22 and the ground terminal member 23 are arranged in this order in the direction that crosses the extending direction of the signal terminal members 22. The signal terminal members 22 and the ground terminal members 23 extend in the direction that is perpendicular to the arrangement direction of the unit terminal groups 21.

[0035]

In each unit terminal group 21, the arrangement pitch of the two signal terminal members 22 is equal to the pitch PI of the pair of coaxial cables 30 connected to the two respective signal terminal members 22. The term "pitch" as used herein means the interval between the centers of the signal terminal members 22 or the coaxial cables 30. The parallel arrangement of the coaxial cables 30 is maintained by the resin film 41 in such a manner that the pitch P2 of the two adjoining coaxial cables 30 that are connected to the adjoining unit terminal groups 21 is set longer than the pitch PI. In this embodiment, the pitch P2 is set equal to two times the pitch PI. With this measure, the connection board 20 can be manufactured in such a manner that the signal terminal members 22 and the ground terminal members 23 are arranged regularly with the same gap so as to have the same width.

[0036]

To manufacture the coaxial flat cable 10, plural coaxial cables 30 are pulled out from plural respective reels on which they are wound, so as to be arranged in a plane. Furthermore, a resin film 41 is pulled out from a reel on which it is wound, so as to be applied to at least one of the two sides of the parallel arrangement of the coaxial cables 30. A coaxial flat cable in which the pitch P2 is equal to two times the pitch PI can be manufactured by paying out two pairs of coaxial cables 30 in such a manner that they are arranged so as to have, between them, a gap that is equal to the width of one coaxial cable 30.

[0037]

In this embodiment, the connection board 20 has an additional ground terminal member 24 which is adjacent to the signal terminal member 22 located at the one end in the arrangement direction of the unit terminal groups 21, and extends in the direction that is perpendicular to the arrangement direction of the unit terminal groups 21. With this measure, as regarding to the unit terminal groups 21, the pair of signal terminal members 22 are interposed between the ground terminal member 23 and the additional ground terminal member 24, whereby the electrical characteristics of the wiring member 1 are enhanced.

[0038]

A pair of signals are transmitted using the two signal terminal members 22 of each unit terminal group 21 and the center conductors 31 connected to them. A ground potential is secured by the outer conductors 33, and the ground terminal members 23, and the additional ground terminal member 24.

[0039]

Fig. 5(a) is a top view of each connection board 20 of the wiring member 1 according to this embodiment. Fig. 5(b) is a top view of each connection board of the wiring member (comparative example) disclosed in Patent Document 1.

As shown in Fig. 5(a), in the wiring member 1 according to this embodiment, since the straight signal terminal members 22 and the straight ground terminal members 23 are arranged in the arrangement direction of the unit terminal groups 21, the interval between each pair of adjoining signal terminal members 22 and the interval between a signal terminal member 22 and the adjacent ground terminal member 23 or the additional ground terminal member 24 do not vary in the longitudinal direction of the coaxial cables 30.

Therefore, the interval between adjoining signal terminal members 22 and the interval between a signal terminal member 22 and the adjacent ground terminal member 23 or the additional ground terminal member 24 can be set equal to a minimum gap d (hereinafter referred to simply as a "minimum gap d") that is necessary in soldering the center conductors 31 of the parallel-arranged coaxial cables 30 to the respective signal terminal members 22, over the length from one ends, in their longitudinal direction, of the signal terminal members 22 and the ground terminal members 23 to the other ends. This facilitates reduction of the width of each connection board 20 (i.e., the dimension in the arrangement direction of the unit terminal groups 21).

The minimum gap d is determined from the width of a terminal that is necessary for soldering the center conductor 31 thereto and the outer diameter of the coaxial cable 30. For example, where coaxial cables of AWG #44 are arranged parallel with each other, the minimum gap d is equal to 0.12 mm. In this case, the cable pitch is equal to 0.3 mm. This issue is more important when the wiring member 1 is constructed using thin coaxial cables 30.

[0040]

On the other hand, as shown in Fig. 5(b), in the wiring member of the comparative example, signal terminal members 122 made on a connection board 120 are bent so as to deviate in the direction that is perpendicular to their longitudinal direction. As a result, even if the interval between a signal terminal member 122 and an adjacent ground terminal member 123 is set equal to the minimum gap d on the side that is close to a coaxial flat cable 10, on the side that is far from the coaxial flat cable 10 the interval between the signal terminal member 122 and the adjacent ground terminal member 123 has a value D that is larger than the minimum gap d. As a result, the width of the connection board 120 becomes larger than that of the connection board 20 according to this embodiment.

As described above, in the wiring member 1 according to this embodiment, the connection board 20 can be made smaller than in the wiring member disclosed in Patent Document 1. Thus, the wiring member 1 can be provided with more compact end portions.

[0041] The shapes of the signal terminal members and the ground terminal member which are formed on each connection board are not limited to the ones described in the above embodiment. For example, the invention encompasses wiring members according to second to fourth embodiments which will be described below. In the second to fourth embodiments, members which are the same as in the first embodiment will be given the same reference numerals and descriptions therefor will be omitted.

[0042]

<Embodiment 2>

Fig. 6 is a top view of each connection board 220 of a wiring member according to the second embodiment of the invention. As shown in Fig. 6, a configuration is possible in which pad portions 225 are not continuous in the arrangement direction of unit terminal groups 221 and each outer conductor 33 is soldered to the closest pad portion 225. It is preferable that each pad portion 225 extend so as to reach an extension(s) of the corresponding signal terminal member(s) 222. With this measure, the outer conductor 33 of each coaxial cable 30 whose center conductor 31 is soldered to the corresponding signal terminal member 222 can be soldered to the corresponding pad portion 225 without the need for changing the posture of the outer conductor 33.

[0043]

Although the ground terminal member 223 and the additional ground terminal member 224 need not always be connected to each other electrically as in the second embodiment, it is preferable that all of the ground terminal member 23 and the additional ground terminal member 224 be electrically connected to each other as in the above-described first embodiment.

[0044] <Embodiment 3>

Fig. 7(a) is a top view of a connection board 320 of a wiring member according to a third embodiment of the invention. Fig. 7(b) is a perspective view of the connection board 320.

As shown in Figs. 7(a) and 7(b), the connection board 320 used in this embodiment is provided with a ground bar 325 instead of the pad portion. The ground bar 325 is a straight, conductive member. The ground bar 325 is provided for the connection board 320 so that its longitudinal direction coincides with the arrangement direction of the unit terminal groups 21. The ground bar 325 is disposed so as to traverse the plural ground terminal members 23 which project toward the coaxial flat cable 10 from the line formed by the ends of the signal terminal members 22. The portions of the outer conductors 33 exposed from the outer sheaths 34 are soldered to the ground bar 325, and the ground bar 325 is soldered to the ground terminal members 23 and the additional ground terminal member 24. The ground bar 325 gives a common ground potential to the outer conductors 33 of the coaxial cables 30.

[0045]

<Embodiment 4>

Fig. 8 is a side sectional view of an end portion, including a connection board 420, of a wiring member according to a fourth embodiment of the invention. As shown in Fig. 8, an end portion of the one resin film 41 in its longitudinal direction may be bonded to the outer sheaths 34 of the coaxial cables 30 so as to be sandwiched between the connection board 420 and the outer sheaths 34 of the coaxial cables 30.

In this case, it is preferable that the coaxial cables 30 be fixed to the connection board 420 as a result of bonding of the end portion of the resin film 41 to the connection board 420. The resin films 41 on the connection board 420 can support the coaxial cables 30 firmly on the connection board 420.

[0046]

In the above-described wiring member according to each of the second to fourth embodiments, as in the connection board 20 according to the first embodiment, the connection board 220, 320, or 420 has the plural unit terminal groups 21 each of which consists of the two straight signal terminal members 22 to which the center conductors 31 of the coaxial cables 30 are soldered and the one straight ground terminal member 23 which is electrically connected to the outer conductor(s) 33 of at least one coaxial cable 30. In each of the plural unit terminal groups 21, the two straight signal terminal members 22 and the one straight ground terminal member 23 are arranged in this order in the direction that crosses the extending direction of the signal terminal members 22. The signal terminal members 22 and the ground terminal member 23 extend in the direction that is perpendicular to the arrangement direction of the unit terminal groups 21. The arrangement pitch of the two signal terminal members 22 of each unit terminal group 21 is equal to the pitch PI of the two coaxial cables 30 connected to them. The resin films 41 maintain the parallel arrangement of the plural coaxial cables 30 in such a manner that the pitch P2 of the two adjoining coaxial cables 30 that are connected to the adjoining unit terminal groups 21 is set longer than the pitch PI .

Therefore, the interval between adjoining signal terminal members 22 and the interval between a signal terminal member 22 and the adjacent ground terminal member 23 or the additional ground terminal member 24 can be set equal to the minimum gap d that is necessary in soldering the center conductors 31 of the parallel-arranged coaxial cables 30 to the respective signal terminal members 22, over the length from one ends, in their longitudinal direction, of the signal terminal members 22 and the ground terminal members 23 to the other ends. This facilitates reduction of the width of each connection board 20. Thus, the wiring member can be provided with more compact end portions.

[Description of Symbols]

[0047]

1 : Wiring member

10: Coaxial flat cable

20: Connection board

21 : Unit terminal group

22: Signal terminal member

23: Ground terminal member

24: Additional ground terminal member

25: Pad portion

30: Coaxial cable

31 : Center conductor

32: Inner insulator

33: Outer conductor

34: Outer sheath

41: Resin film

42: Protective film

43: Reinforcement film

325: Ground bar