WO2010014432A2

WO2010014432A2 - Grounding member and grounding method of collective cable, and collective cable assembly

Info

Publication number: WO2010014432A2
Application number: PCT/US2009/050913
Authority: WO
Inventors: Toshiyuki Sawabe; Satoshi Ishizaki; Toshiroh Endoh
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2008-07-31
Filing date: 2009-07-17
Publication date: 2010-02-04
Anticipated expiration: 2011-01-31
Also published as: WO2010014432A3; TW201014089A; JP2010040214A

Abstract

Provided is a collective cable having a plurality of coaxial cables in circular parallel arrangement, connecting a shield layer of each coaxial cable easily and stably to a common ground while preventing positional deviation and bending of individual coaxial cable. More particularly, a grounding member includes an outer wall extending in an arcuate shape, and an inner wall integrally connected to the outer wall and extending in an arcuate shape. The outer wall and the inner wall are disposed to face each other with a predetermined gap defined therebetween. The gap is defined in such a manner that the coaxial cables of a collective cable are received between the outer wall and the inner wall while maintaining a circular parallel arrangement, and that the locally exposed shield layers of the coaxial cables contact both the outer wall and the inner wall. The grounding member is electrically conductive.

Description

GROUNDING MEMBERAND GROUNDING METHOD OF COLLECTIVE CABLE, AND COLLECTIVE CABLE ASSEMBLY

Technical Field

The present invention relates to a grounding member and a grounding method for a collective cable having a plurality of coaxial cables. The present invention also relates to a collective cable assembly including the grounding member.

Background

A collective cable (also referred to as a composite cable) having a plurality of cables, chords, etc., integrally contained in one sheath has been known to improve handling and space utilization efficiency of the cables, chords, etc. A plurality of coaxial cables for signal transmission that are integrated to a collective cable is also commercially available.

For example, Patent Document 1 (WO 2005/029099) discloses a collective cable integrating a plurality of coaxial cables used in a current measurement apparatus. This collective cable includes a plurality of coaxial cables, a fastener for fastening these coaxial cables in parallel arrangement so as to align respective ends in axial direction, a signal line connector for electrically connecting the signal lines of the coaxial cables to each other, and a shield connector formed of copper foil, etc. for electrically connecting shields of individual coaxial cables exposed near respective ends thereof. In Patent Document 1, (WO 2005/029099) there is a description that "by using the fastener, the signal line connector and the shield connector, a plurality of coaxial cables can be bundled into one body with length, etc. of the coaxial cables kept in identical state, and laying of the collective cable can be simplified so as to keep produced variation of the characteristics of each coaxial cable to a minimum."

Thus, in a collective cable, it is sometimes required to connect the shield elements of a plurality of cables, chords, etc. to a common ground. In such a case, as the number of contained cables, chords, etc. increases, the ground connection operation for connecting the shield elements to a common ground (that is, grounding method for a collective cable) becomes more and more complicated, so that there is a need for some means in order to simplify the ground connection operation.

In simplifying the ground connection operation, Patent Document 2 (Japanese

Unexamined Patent Publication (Kokai) No. 2005-093198) discloses a grounding structure for grounding a plurality of shielded wires. In this grounding structure, a braided shield wire is exposed by peeling off the cover material at intermediate part of each shielded wire, and a binding band with a metal foil applied to the inside surface thereof is wound around a splice part formed by placing the end of the grounding wire on the braided wire, and is fastened and fixed to the splice part. The braided wires are thereby pressed to each other and to the ground wires, and the outer circumferential surface of the splice part is brought into contact with the metal foil on the inner circumferential surface of the binding band to form conductive connection and to complete the grounding.

Summary In a collective cable having a plurality of coaxial cables, to realize high speed transmission of signal, it is necessary to connect the shield layers of individual coaxial cables stably to a common ground. In such a case, as described above, it is desirable to simplify the ground connection operation (that is, grounding method of a collective cable) for connecting the shield layer of each coaxial cable to a common ground. On the other hand, in a collective cable having a plurality of coaxial cables, it is proposed to construct the collective cable (also referred to as round-type collective cable) such that the coaxial cables are contained in a sheath in generally circular parallel arrangement along the inner surface of the tubular sheath. In this construction, it is required to maintain the relative position of the coaxial cables so as not to deviate from the circular parallel arrangement in order to prevent the increase of skew (that is, difference in transmission delay time). Further, it is also required to avoid deformation (especially change in thickness) of an insulator (a layer between a center conductor and the shield layer) due to bending of individual coaxial cables in order to prevent variation of characteristic impedance of the collective cable and the deterioration of the transmission characteristics of signals. In this respect, the shield connector formed of copper foil or the like and the binding band formed of metal foil in the prior art have a problem that they are likely to give rise to positional deviation or bending of coaxial cables. It is an object of the present invention to provide a grounding member which is used for a collective cable consisting of a plurality of coaxial cables contained in circular parallel arrangement in a sheath and which is capable of connecting the shield layer of each coaxial cable easily and stably to a common ground while preventing positional deviation or bending of individual coaxial cables.

It is another object of the present invention to provide a collective cable assembly which includes a plurality of coaxial cables, a sheath containing these coaxial cables in circular parallel arrangement, and a grounding member for connecting the shield layers of individual coaxial cables to a common ground, and which permits the shield layer of each coaxial cable to be connected easily and stably to a common ground, and which permits high speed transmission to be realized with high reliability.

It is still another object of the present invention to provide a grounding method which is used for a collective cable assembly consisting of a plurality of coaxial cables contained in circular parallel arrangement in a sheath, and which is capable of connecting the shield layer of each coaxial cable easily and stably to a common ground while preventing positional deviation or bending of individual coaxial cables.

Brief Description of the Drawings

Fig. 1 is a perspective view showing a grounding member according to a first embodiment of the present invention and a collective cable assembly according to a first embodiment of the present invention and including the grounding member.

Fig. 2 is an enlarged perspective view showing the grounding member of Fig. 1. Fig. 3 is a view showing an example of a process for making the grounding member of Fig. 1 in steps (a)-(c). Fig. 4 is a sectional view showing an example of the construction of a collective cable to which the grounding member according to the present invention can be applied.

Fig. 5 is a perspective view showing a collective cable assembly according to another embodiment of the present invention.

Fig. 6 is a perspective view showing a grounding member according to a second embodiment of the present invention.

Fig. 7 is a perspective view showing a collective cable assembly according to a third embodiment of the present invention and including the grounding member of Fig. 6. Description of Reference Numerals

10, 10', 100 grounding member

12, 12', 102 collective cable assembly

14, 40 coaxial cable

16, 38 sheath

18, 18', 36 collective cable

20, 44' shield layer

22 outer wall

24 inner wall

26 connecting portion

28 covering

30 insulator

32 center conductor

34 fastening means

46 opening

48 extension

Detailed Description One aspect of the present invention provides a grounding member for connecting respective shield layers of several coaxial cables to a common ground, used for a collective cable configured to contain the coaxial cables in a circular parallel arrangement within a sheath, characterized in that the grounding member includes an outer wall; and an inner wall integrally connected to the outer wall; wherein the outer wall and the inner wall are disposed to face each other with a predetermined gap defined therebetween, the gap being defined in such a manner that the coaxial cables of the collective cable are received between the outer wall and the inner wall and that locally exposed portions of the respective shield layers of the coaxial cables come into contact with both of the outer wall and the inner wall; and wherein at least one of the outer wall and the inner wall is electrically conductive.

Another aspect of the present invention provides a collective cable assembly comprising several coaxial cables, a sheath containing the coaxial cables in a circular parallel arrangement, and a grounding member connecting respective shield layers of the coaxial cables to a common ground, characterized in that the grounding member includes an outer wall positioned along an outer circumferential side of the coaxial cables; and an inner wall integrally connected to the outer wall and positioned along an inner circumferential side of the coaxial cables; wherein the outer wall and the inner wall are disposed to face each other with a predetermined gap defined therebetween, and are configured to receive the coaxial cables between the outer wall and the inner wall and to contact with locally exposed portions of the respective shield layers of the coaxial cables; wherein at least one of the outer wall and the inner wall is electrically conductive; and wherein the at least one of the outer wall and the inner wall of the grounding member, which is electrically conductive, is fixedly connected to the locally exposed portions of the shield layers of the coaxial cables.

A further aspect of the present invention provides a grounding method for connecting respective shield layers of several coaxial cables to a common ground, used for a collective cable configured to contain the coaxial cables in a circular parallel arrangement within a sheath, characterized in that the method includes providing a grounding member as set forth in any one of claims 1 to 5; locally exposing the respective shield layers of the coaxial cables; locating the outer wall of the grounding member along an outer circumferential side of the coaxial cables, and locating the inner wall of the grounding member along an inner circumferential side of the coaxial cables, so that both of the outer wall and the inner wall come into contact with locally exposed portions of the respective shield layers of the coaxial cables; fixedly connecting the at least one of the outer wall and the inner wall of the grounding member, which is electrically conductive, to the locally exposed portions of the shield layers of the coaxial cables; and connecting the grounding member to the common ground.

In the grounding member according to one aspect of the present invention, the positional deviation and bending of individual coaxial cables of a collective cable, and hence increase of skew, variation of characteristic impedance and deterioration of transmission characteristics attributable to the deviation or bending, can be prevented, and the shield layer of each coaxial cable can be easily and stably connected to a common ground. In the collective cable assembly according to the other aspect of the present invention, since the shield layer of each coaxial cable can be easily and stably connected to a common ground while preventing the positional deviation and bending of individual coaxial cables, high speed transmission can be realized with high reliability. In the grounding method according to the further aspect of the present invention, since the positional deviation and bending of individual coaxial cables of a collective cable can be prevented simply by connecting the grounding member to a common ground, the shield layer of each coaxial cable can be easily and stably connected to a common ground. Now, the present invention will be described in detail below with reference to appended drawings showing embodiments thereof. Throughout the drawings, corresponding constituents are denoted by common reference numerals and symbols.

Fig. 1 is a view showing a grounding member 10 according to a first embodiment of the present invention, and a collective cable assembly 12 according to a first embodiment of the present invention including the grounding member 10. Fig. 2 is an enlarged perspective view showing the grounding member 10 of Fig. 1. The grounding member 10 is a member for connecting the shield layers 20 of individual coaxial cables 14 of a collective cable (also referred to as round type collective cable) 18 consisting of a plurality of coaxial cables 14 contained in circular parallel arrangement in a sheath 16, to a common ground G.

The grounding member 10 includes an outer wall 22 extending in the arcuate shape, and an inner wall 24 integrally connected to the outer wall 22 and extending in the arcuate shape. As shown in Fig. 1, the outer wall 22 and the inner wall 24 are disposed to face each other with a predetermined gap S (Fig. 2) defined therebetween, the gap S being defined in such a manner that a plurality (all, in the drawing) of coaxial cables 14 of the collective cable 18 are received between the outer wall 22 and the inner wall 24 while maintaining the circular parallel arrangement and that the locally exposed portions of the respective shield layers 20 of the coaxial cables 14 come into contact with both the outer wall 22 and the inner wall 24. It should be noted that the term "a circular parallel arrangement" used in the present application represents a predetermined arrangement of the coaxial cables 14 in the collective cable 18, in which the coaxial cables 14 are disposed parallel to each other in a generally circular array along an inner face of the cylindrical sheath 16. The phrase "while maintaining the circular parallel arrangement" means a state where the relative position or mutual intervals of the coaxial cables 14, disposed in the natural circular parallel arrangement inside the sheath 16, are substantially maintained. The grounding member 10 is a one-piece member formed by stamping and bending process from a sheet metal material such as a copper plate, and the entire member including the outer wall 22 and the inner wall 24 is constructed so as to have suitable electrical conductivity suitable rigidity. Further referring to Fig. 3, the grounding member is made by first stamping a sheet metal material into a strip of a predetermined outline to form a blank 1OA (Fig. 3(a)), and then folding back the parts 1OB at both longitudinal ends of the blank 1OA by 180 degrees via respective U-shaped bent portions 1OC (Fig. 3(b)), and bending the remaining center portion 1OD of the blank 1OA together with both end portions 1OB in generally C-shaped form with both end portions 1OB facing inward (Fig. 3(c)). With this procedure, a grounding member 10 (Fig. 2) can be obtained in which the center portion 1OD of the blank 1OA forms an outer wall 22 extending in the shape of circular arc over a length of nearly complete circle (360 degrees), and both end portions 1OB form an inner wall 24 in opposition to and generally parallel to the outer wall 22 inside the outer wall 22 and similarly extending in the shape of circular arc over a length of nearly complete circle (360 degrees), and a pair of bent portions 1OC form U-shaped connecting portions 26 that connect the outer wall 22 at both ends to the inner wall 24.

When the grounding member 10 is in its initial state with no external force applied to it, it retains the shape with uniform gap S maintained between the outer wall 22 and the inner wall 24 (Fig. 2). Here, the inner wall 24 is held in cantilever fashion via the connecting portion 26 by the outer wall 22, whereby the spring properties are imparted to the structure, permitting the gap S between the outer wall 22 and the inner wall 24 to be varied elastically. The gap S between the outer wall 22 and the inner wall 24 is set to be equal to or slightly smaller than the outer diameter D (Fig. 1) of the shield layer 20 of each coaxial cable 14 of the collective cable 18. By setting the gap S between the outer wall 22 and the inner wall 24 to be slightly smaller than the outer diameter D of the shield layer 20 of the coaxial cable 14, the locally exposed shield layers 20 of all the coaxial cables 14 which are received between the outer wall 22 and the inner wall 24 are brought into close contact with both the outer wall 22 and the inner wall 24 under uniform and suitable pressure applied by the spring properties of the grounding member 10.

The collective cable assembly 12 is made by assembling the grounding member 10 having the construction as described above to a collective cable 18 according to the following procedures. First, the sheath 16 is removed from the collective cable 18 over the end region of a predetermined length to expose end portion of a plurality of coaxial cables 14, and the covering 28 of the coaxial cable 14 is removed from individual coaxial cables 14 over the end region of a predetermined length to expose the shield layer (for example, braided wire) 20. Suitable termination processing is performed on the exposed portion of each coaxial cable 14, for example, such that the exposed lengths of the shield layers 20, the insulators 30 inside the shield layers 20, and the center conductors 32 become uniform (Fig. 1).

Then, to the collective cable 18 on which termination processing has been performed, the grounding member 10 is assembled such that the outer wall 22 is disposed along the outer circumferential side of the exposed portions of the coaxial cables 14 arranged in circular parallel arrangement, and the inner wall 24 is disposed along the inner circumferential side of the exposed portions of the coaxial cables 14. Here, all the coaxial cables 14 can be collectively inserted into the empty space between the outer wall 22 and the inner wall 24 of the grounding member 10 beginning from the exposed center conductors 32. When the locally exposed shield layers 20 in the end region of all the coaxial cables 14 are disposed between the outer wall 22 and the inner wall 24 of the grounding member 10, the outer wall 22 and the inner wall 24 are both brought into close contact with the individual shield layers 20, preferably under generally uniform pressure applied by the spring properties determined by the dimensional relation of "gap S" and "outer diameter D". In this state, by the friction of the outer wall 22 and the inner wall 24 with the shield layer 20 of each coaxial cable 14, the grounding member 10 is temporarily held on the coaxial cables 14 (such that it is not displaced or falls off from the coaxial cables 14 by its own weight). The pressure determined by the dimensional relation of "gap S" and "outer diameter D" as described above should not be so high as to cause deformation of the insulator 30 of each coaxial cable 14.

Finally, the grounding member 10 that has been temporarily held on the coaxial cables 14 is mechanically and electrically fixed and connected to the shield layer 20 of each coaxial cable 14 by fastening means 34, such as soldering, that do not produce substantial deformation of the grounding member 10 and the coaxial cables 14 (Fig. 1). Fabrication of a collective cable assembly 12 is thereby completed. The collective cable assembly 12 made in this way permits the shield layers 20 of the coaxial cables 14 to be stably connected to a common ground G simply by connecting the grounding member 10 to the common ground G.

The grounding member 10 having above-described construction can receive all the coaxial cables 14 of the collective cable 18 as they are arranged in circular parallel arrangement between the outer wall 22 and the inner wall 24 such that the shield layer 20 of each coaxial cable 14 is brought into contact with both the outer wall 22 and the inner wall 24. Thus, with suitable rigidity of the grounding member 10 of its own, the exposed portions of all of the coaxial cables 14 can be held in the natural circular parallel arrangement predetermined in the collective cable 18. In this state, the grounding member 10 applies substantially no pressure or only a suitable pressure (that is, a pressure not so high as to produce deformation of the insulator 30) uniformly to all the coaxial cables 14, so that bending of individual coaxial cables 14 and associated deformation of the insulator 30 (especially change of thickness) can be avoided. By using fastening means (such as soldering) 34 which produce substantially no deformation of the grounding member 10 and the coaxial cables 14, the grounding member 10 can be stably connected mechanically and electrically to the shield layer 20 of individual coaxial cables 14. When the grounding member 10 is to be assembled to a collective cable 18, the exposed portion of all the coaxial cables 14 can be collectively inserted into the empty space between the outer wall 22 and the inner wall 24 of the grounding member 10, and the grounding member 10 can be temporarily held on the coaxial cables 14, so that final fixing and connecting operation by using the fastening means 34 can be simplified. Thus, with the grounding member 10, the shield layer 20 of each coaxial cable 14 can be easily and stably connected to a common ground G while preventing the positional deviation and bending of individual coaxial cables 14 and thus avoiding associated increase of skew, variation of characteristic impedance, and deterioration of transmission characteristics caused by the .positional deviation and bending of coaxial cables.

In accordance with the grounding method of a collective cable 18 using the grounding member 10 as described above, shield layers 20 of a plurality of coaxial cables 14 can be easily and stably connected to a common ground G simply by connecting the grounding member 10 to the common ground G while preventing the positional deviation and bending of individual coaxial cables 14.

With the collective cable assembly 12 having the grounding member as described above, it is possible to realize high speed transmission with high reliability, since the shield layer 20 of each coaxial cable 14 can be easily and stably connected to a common ground G while preventing the positional deviation and bending of individual coaxial cables 14.

Fig. 4 is a view showing an example of the construction of another collective cable 36 to which the grounding member according to the present invention is applicable. The illustrated collective cable 36 includes a plurality of coaxial cables 40 contained in a sheath 38 in generally circular parallel arrangement along the inner circumferential surface of the tubular sheath 38, and a plurality of pair stranded cables 42 disposed inside the coaxial cables 40. In this collective cable 36, when external force is applied in radial direction to the coaxial cables 40 in circular parallel arrangement, the pair stranded cables

42 are relatively easily deformed and displaced due to the pressure exerted by the coaxial cables 40 to the inner pair-stranded cables 42, so that positional deviation of the coaxial cables 40 is likely to occur. The grounding member according to the present invention is particularly effective for preventing the positional deviation and bending of individual coaxial cables 40 and permits the shield layer 44 of each coaxial cable 40 to be easily and stably connected to the common ground.

Fig. 5 is a view showing a collective cable assembly 12' according to a second embodiment of the present invention. The collective cable 12' has the construction in which a collective cable 18' consisting of several sets (two sets in the Figure) of coaxial cables 14 respectively arranged in circular parallel arrangement with several sets disposed in superimposition to one another in axial direction, is collectively contained in a sheath 16, and has plural (two in the Figure) separate grounding members 10, 10' of different dimensions assembled thereto. The grounding member 10 has the same construction as the grounding member 10 shown in Fig. 1 and Fig. 2, and can connect the shield layers 20 of the first set of coaxial cables 14 which are arranged in circular parallel arrangement along the inner surface of the sheath 16 to a common ground G. The grounding member 10' has the construction substantially similar in reduction (except the gap S) to the grounding member 10, and can connect the shield layers 20 of the second set of coaxial cables 14 which are arranged in circular parallel arrangement inside the first set of coaxial cables 14 to the common ground G. With such construction, even if the number of coaxial cables 14 increases significantly, the shield layer 20 of each coaxial cable 14 can be easily and stably connected to the common ground while preventing positional deviation or bending of individual coaxial cables 14.

Various alteration and modification can be made to the grounding member 10 according to the first embodiment of the present invention.

For example, as shown in Fig. 1 and Fig. 2, the outer wall 22 of the grounding member 10 may be provided with one or more openings 46 that penetrate the outer wall 22 in thickness direction. The openings 46 act so as to reduce the overall heat capacity of the grounding member 10 to enable efficient heating thereof. When soldering is used as the fastening means 34, the openings 46 may also have the function to facilitate injection of solder between the outer wall 22 and the shield layer 20 of each coaxial cable 14. Thus, by providing openings 46 in the grounding member 10, solder wettability is enhanced and the quality of solder junction structure is thereby improved, and accumulation of stress in the coaxial cable 14 and deformation of the insulator 30 (especially change of thickness) due to overheating can be avoided in advance, so that increase of skew of the collective cable 18, variation of characteristic impedance and deterioration of transmission characteristics can be prevented. In this respect, it is preferable that a plurality of openings 46 be distributed uniformly along the longitudinal direction of the outer wall 22.

Also, as shown in Fig. 1 and Fig. 2, the outer wall 22 of the grounding member 10 may be provided with one or more extensions 48 that locally project in the direction along the wall surface 22a of the outer wall 22. The extensions 48 are portions where heat capacity is locally reduced on the grounding member 10, and therefore, if soldering is employed as fastening means 34, solder can be applied around the extensions 48 to improve the quality of the solder junction structure and to avoid in advance the accumulation of stress in the coaxial cable 14 and deformation of the insulator 30 due to overheating. Thus, increase of skew of the collective cable 18, variation of characteristic impedance and deterioration of transmission characteristics can be prevented by providing the extensions 48 on the grounding member 10. In this respect, it is preferable that a plurality of extensions 48 be distributed uniformly along the longitudinal direction of the outer wall 22 as shown in the Figure. Further, as shown in the Figure, the openings 46 and the extensions 48 can be both provided in combination on the grounding member 10 to prevent deterioration of the transmission characteristics, etc. more effectively.

The grounding member 10 may be constructed such that either the outer wall 22 or the inner wall 24 is electrically conductive. In this construction, the outer wall 22 and the inner wall 24 can be formed from different materials. In this case, the grounding member 10 can be integrally formed in one piece by using multicolor molding method, or the outer wall 22 and the inner wall 24 (and, in some cases, a connecting portion 26) can be formed separately to be later joined into one unit in a post-processing step. In any construction, substantially same effect can be obtained as with the above-described grounding member 10 which is an entirely conductive one-piece member. When soldering is to be employed as fastening means 34, in view of workability for soldering operation, it is desirable that at least the outer wall 22 is electrically conductive.

In place of above-described construction in which the grounding member 10 is formed in the shape of a strip from sheet metal material, the grounding member 10 may be constructed as a linear member such as a wire as long as required rigidity, and preferably the spring properties, can be ensured. The grounding member is not limited to above- described construction in which it is mounted to the exposed portion of the coaxial cables 14 at the end of the collective cable 18, but may be constructed such that it is mounted to an exposed portion formed by removing the sheath and the covering 28 of each coaxial cable 14 in an arbitrary length region in a longitudinal intermediate portion of the collective cable 18. Further, in place of above-illustrated construction in which a plurality of coaxial cables 14 in circular parallel arrangement are collectively connected to the ground, it is also possible to divide the coaxial cables 14 in circular parallel arrangement into two or three groups, and to employ smaller (for example, semi-circular) grounding members 10 for separately grounding the coaxial cables 14 of each group.

In the grounding method using the grounding member 10, when soldering is employed as fastening means 34, preliminary processing may be performed in advance to apply flux, etc., to the grounding member 10. With such construction, quality of the solder joint structure can be improved, and accumulation of stress in the coaxial cables 14 and deformation of the insulators 30 due to overheating can be avoided. It is also possible to use a conductive adhesive in place of soldering as fastening means 34. The collective cable assembly 12, 12' according to the first and second embodiments of the invention may be made by a process other than the aforementioned assembling process. For example, a not-shown connector may be attached to the collective cable 18 through an insert molding process wherein a plurality of contacts and the exposed ends of the coaxial cables 14 of the collective cable 18, which are conductively contacted with each other, are disposed at predetermined positions in a molding cavity of an exclusive mold, and a molten resinous material is poured into the molding cavity to form a connector body. In this process, if the grounding member 10 previously and temporarily holding the coaxial cables 14 is also disposed in the molding cavity of the mold and the connector body is formed by the molten resinous material, the grounding member 10 can be fixedly attached to the collective cable 18 without using the fastening means 34 such as solder. Alternatively, in a case where the connector is secured to the collective cable 18 by mechanical means such as a caulking member, the grounding member 10 previously and temporarily holding the coaxial cables 14 may be located near the caulking member, so that the grounding member 10 can be fixedly attached to the collective cable 18 by the securing function of the caulking member without using the fastening means 34 such as solder. The collective cable assembly 12, 12' made through any one of the above processes is useful as a collective cable assembly with connector.

As previously described, the grounding member 10 of the first embodiment has a configuration wherein both of the outer wall 22 and the inner wall 24 extend in an arcuate shape, and the coaxial cables 14 of the collective cable 18 are received between the outer wall 22 and the inner wall 24 while maintaining the circular parallel arrangement. Basically, the grounding member 10 having such a configuration may be fitted to the coaxial cables 14 exposed from the sheath 16 of the collective cable 18 at any position in the longitudinal direction thereof. However, in a practical use, there is a case where it is required to intentionally break the circular parallel arrangement of the coaxial cables 14, such as a case where a general purpose connector with multiple contacts in a parallel array is attached to the collective cable 18 subjected to termination processing. In this case, the grounding member 10 can be used at a location near the terminated end of the sheath 16 (i.e., a location where the circular parallel arrangement of the coaxial cables 14 is not significantly broken) to ground the coaxial cables, in place of using a grounding plate provided within the connector. On the other hand, taking into consideration the situation where it is required to intentionally break the circular parallel arrangement of the coaxial cables when, e.g., a connector is attached to the collective cable 18, the grounding member according to the present invention may be configured in such a manner that the coaxial cables are received between the outer and inner walls in a shape other than the circular parallel arrangement. In this configuration, however, it is also required to prevent the relative position of the coaxial cables 14 from deviating from the natural circular parallel arrangement as far as possible, in order to prevent the increase of skew (i.e., difference in transmission delay time) of the collective cable 18. In this context, the grounding member according to the present invention may have a configuration that can maintain the coaxial cables 14 of the collective cable 18 in a predetermined arrangement such that the positional deviation of the coaxial cables 14 from the natural circular parallel arrangement is limited within an allowable range determined due to required signal transmission properties.

For example, it is preferred that a connector attached to the collective cable 18 is provided with a plurality of contacts disposed in a multiple (e.g., double) array resembling the circular parallel arrangement of the coaxial cables 14, from a viewpoint of preventing the increase of skew. In relation to the connector having such a configuration, the grounding member according to the present invention can be effectively used at a location near connecting points between the coaxial cables 14 and the corresponding contacts of the connector, instead of a location near the terminated end of the sheath 16 of the collective cable 18. Figs. 6 and 7 show, respectively, a grounding member 100 according to a second embodiment of the present invention and effectively used for the aforementioned connector, and a collective cable assembly 102 according to a third embodiment of the present invention and provided with the grounding member 100. The grounding member 100 has a configuration substantially identical to that of the grounding member 10 according to the first embodiment, except for the shape of inner and outer walls, and therefore, corresponding components are denoted by common reference numerals and the detailed description thereof are not repeated.

The grounding member 100 includes an outer wall 22 extending in a generally U- shape, and an inner wall 24 integrally connected to the outer wall 22 and extending in a generally L-shape. The outer wall 22 and the inner wall 24 are disposed to face each other with a predetermined gap S defined therebetween, and are configured to receive a plurality (all, in the drawing) of coaxial cables 14 of the collective cable 18 between the outer wall 22 and the inner wall 24 in a double parallel array resembling the natural circular parallel arrangement, so that the locally exposed shield layers 20 of individual coaxial cables 14 come into contact with both the outer wall 22 and the inner wall 24. The grounding member 100 may have spring properties permitting the gap S between the outer wall 22 and the inner wall 24 to be varied elastically.

The collective cable assembly 102 is made by assembling the grounding member 100 having the construction as described above to a collective cable 18 according to the following procedures. The collective cable 18 subjected to the termination processing is prepared in a state where the distal end lengths of the coaxial cables 14 exposed from the sheath 16 are disposed in a double parallel array corresponding to the array of contacts of a connector (not shown), which is slightly deformed from the natural circular parallel arrangement, in order to be attached with the connector. The grounding member 100 is assembled to the thus prepared collective cable 18 at a location away from the sheath 16, in such a manner that the outer wall 22 is disposed along the outer circumferential side of the exposed portions of the coaxial cables 14 arranged in the double parallel array, and the inner wall 24 is disposed along the inner circumferential side of the exposed portions of the coaxial cables 14. As a result, the outer wall 22 and the inner wall 24 come into close contact with the shield layers 20 of the respective coaxial cables 14, preferably under generally uniform pressure applied by the spring properties. In this state, by the friction between the outer and inner wall 22, 24 and the shield layer 20 of each coaxial cable 14, the grounding member 100 is temporarily held on the coaxial cables 14.

Finally, the grounding member 100 that has been temporarily held on the coaxial cables 14 is mechanically and electrically fixed and connected to the shield layers 20 of the respective coaxial cables 14 by fastening means 34, such as soldering, that do not produce substantial deformation of the grounding member 10 and the coaxial cables 14 (Fig. 1). Fabrication of a collective cable assembly 102 is thereby completed. The collective cable assembly 102 made in this way permits the shield layers 20 of the coaxial cables 14 to be stably connected to a common ground G simply by connecting the grounding member 100 to the common ground G.

The grounding member 100 having the above-described configuration can achieve several effects equivalent to those of the grounding member 10, on the assumption that the positional deviation of the coaxial cables 14 is limited within an allowable range determined due to required signal transmission properties. In particular, a conventional connector attaching process tends to require an operator's skill due to the fact that the coaxial cables 14 disposed in an unconfmed double parallel array at a location away from the sheath 16 for the attachment of the connector are liable to be subjected to a positional deviation. On the contrary, according to the grounding member 100, it is possible to attach the connector to the coaxial cables 14 in a state where the coaxial cables 14 are stably held in the double parallel array, and thus to readily and properly perform the connector attaching process without requiring the operator's skill. It should be noted that the aforementioned various changes or modifications in connection with the grounding member 10 and the collective cable assembly 12, 12' may be similarly adopted in the grounding member 100 and the collective cable assembly 102.

Claims

What is claimed is:

1. A grounding member for connecting respective shield layers of several coaxial cables to a common ground, used for a collective cable configured to contain said coaxial cables in a circular parallel arrangement within a sheath, characterized in that said grounding member comprises: an outer wall; and an inner wall integrally connected to said outer wall; wherein said outer wall and said inner wall are disposed to face each other with a predetermined gap defined therebetween, said gap being defined such that the coaxial cables of the collective cable are received between said outer wall and said inner wall and that locally exposed portions of the respective shield layers of the coaxial cables contact both of said outer wall and said inner wall; and wherein at least one of said outer wall and said inner wall is electrically conductive.

2. A grounding member of claim 1, wherein said outer wall and said inner wall extend in an arcuate shape, the coaxial cables of the collective cable being received between said outer wall and said inner wall while maintaining the circular parallel arrangement.

3. A grounding member of claim 1 or 2, wherein said outer wall is electrically conductive.

4. A grounding member of claim 3, wherein said outer wall is provided with an opening penetrating through said outer wall.

5. A grounding member of claim 3 or 4, wherein said outer wall is provided with an extension projecting locally in a direction along a surface of said outer wall.

6. A grounding member of any one of claims 1 to 5, wherein said grounding member has spring properties and allows said gap between said outer wall and said inner wall to elastically vary.

7. A collective cable assembly comprising several coaxial cables, a sheath containing said coaxial cables in a circular parallel arrangement, and a grounding member connecting respective shield layers of said coaxial cables to a common ground, characterized in that said grounding member comprises: an outer wall positioned along an outer circumferential side of said coaxial cables; and an inner wall integrally connected to said outer wall and positioned along an inner circumferential side of said coaxial cables; wherein said outer wall and said inner wall are disposed to face each other with a predetermined gap defined therebetween, and are configured to receive said coaxial cables between said outer wall and said inner wall and to contact locally exposed portions of said respective shield layers of said coaxial cables; wherein at least one of said outer wall and said inner wall is electrically conductive; and wherein said at least one of said outer wall and said inner wall of said grounding member, which is electrically conductive, is fixedly connected to said locally exposed portions of said shield layers of said coaxial cables.

8. A collective cable assembly of claim 7, wherein said outer wall and said inner wall extend in an arcuate shape, the coaxial cables being received between said outer wall and said inner wall while maintaining the generally circular parallel arrangement.

9. A collective cable assembly of claim 7 or 8, wherein said several coaxial cables comprise several sets of coaxial cables coaxially disposed relative to and adjacent to each other with each set being in said circular parallel arrangement; and wherein said grounding member comprises several discrete grounding members for connecting respective shield layers of said several sets of coaxial cables to said common ground.

10. A grounding method for connecting respective shield layers of several coaxial cables to a common ground, useful for a collective cable configured to contain said coaxial cables in a circular parallel arrangement within a sheath, the method comprising: providing a grounding member of any one of claims 1 to 6; locally exposing said respective shield layers of said coaxial cables; locating said outer wall of said grounding member along an outer circumferential side of said coaxial cables, and locating said inner wall of said grounding member along an inner circumferential side of said coaxial cables, so that said outer wall and said inner wall contact locally exposed portions of said respective shield layers of said coaxial cables; fixedly connecting said at least one of said outer wall and said inner wall of said grounding member, which is electrically conductive, to said locally exposed portions of said shield layers of said coaxial cables; and connecting said grounding member to said common ground.