JP5582090B2 - Multi-core differential signal transmission cable - Google Patents

Description

  The present invention relates to a multicore differential signal transmission cable formed by assembling a plurality of twinax cables.

  A twinax cable is generally used for communication of high-frequency signals in the GHz band. In recent years, with an increase in transmission capacity, a multi-core differential signal transmission cable formed by collecting a plurality of twinax cables has been used.

  A conventional multicore differential signal transmission cable is shown in FIG.

  As shown in FIG. 10, the multi-core differential signal transmission cable 70 is provided with an intervening 72 with a gap 74 around the outer periphery of two twinax cables 80, and on the outer periphery with six twinax cables 80, The intervening 72, the tape conductor 75, the braided wire 76, and the jacket 77 are sequentially provided.

  The twinax cable 80 used for the multi-core differential signal transmission cable 70 has two pairs of signal wires (cores) 83 formed by covering a conductor 81 with an insulator 82 in parallel and along these cores 83. The drain wire 84 is disposed and bundled into one, and the outer periphery thereof is configured to cover a shield material 85 made of a metal tape such as a copper / PET tape.

  In the multicore differential signal transmission cable 70 having a plurality of twinax cables 80 as shown in FIG. 10, when the twinax cables 80 are arranged in parallel without being twisted, the multicore differential signal transmission cables are arranged. When the cable is bent, the twinax cable 80 located on the inner side with the interposition 72 interposed therebetween is crushed and the twinax cable 80 located on the outer side is stretched, so that the length of the twinax cable 80 is increased between the inner side and the outer side of the bend. There is a difference in height, and a pairwise skew occurs.

  Therefore, conventionally, by twisting the twinax cable in order to suppress the occurrence of the skew between the pair due to the bending, a twinax cable located inside the bend and a twinax cable located outside the bend are provided. The length difference of each twinax cable is absorbed by gradually switching in the longitudinal direction of the multicore differential signal transmission cable.

JP 2004-87189 A JP-A-2005-340105

  However, the conventional multicore differential signal transmission cable has a problem that the twinax cable is crushed and deformed by an external force received in the process of twisting the twinax cables together.

  In order to prevent such deformation, a method of using an intervention when twisting the twinax cable or a method of controlling the twisting condition can be considered, but the deformation based on twisting cannot be completely prevented.

  When the twinax cable is deformed, the capacitance of the signal line and the effective dielectric constant are changed, the impedance characteristics of the individual signal lines are changed, and characteristics such as high-frequency transmission characteristics are deteriorated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce characteristic deterioration of a twinax cable in a multicore differential signal transmission cable formed by assembling a plurality of twinax cables. A core differential signal transmission cable is provided.

The present invention created to solve the above problems is a multicore differential signal transmission cable formed by assembling a plurality of twinax cables, a resin spiral tube, and the spiral tube, A plurality of the twinax cables that are movably accommodated along the axial direction of the spiral tube and arranged in parallel; and a gap formed between the twinax cable and the spiral tube ; The spiral tube is a multi-core differential signal transmission cable that is formed by stretching a record-made resin strip in the axial direction and spirally winding it .

  It is preferable that no intervention is included in the spiral tube.

  The strip is preferably made of a fluorine-based resin.

  The twinax cable may include a signal line in which two conductors arranged in parallel are collectively covered with an insulator, and a shield material made of a metal tape provided on the outer periphery of the signal line.

  The shield material may be vertically wound around the outer periphery of the signal line.

  ADVANTAGE OF THE INVENTION According to this invention, the cable for multi-core differential signal transmission which can suppress the characteristic deterioration of a twinax cable can be provided.

It is a cross-sectional view of the differential signal transmission cable according to the present embodiment. FIG. 2 is a perspective view in which a tape conductor, a braided wire, and a jacket are omitted from the differential signal transmission cable of FIG. 1. (A) is a twinax cable having a structure in which a shield material is horizontally wound, and (b) is a view showing a twinax cable having a structure in which a shield material is vertically wound (cigarette wound). It is a figure which shows the frequency characteristic of the insertion loss of the cable for multi-core differential signal transmission which concerns on this Embodiment. It is a figure which shows the frequency characteristic of the insertion loss of the conventional cable for multi-core differential signal transmission. It is a cross-sectional view of the multicore differential signal transmission cable according to another embodiment. FIG. 7 is a perspective view in which the tape conductor, the braided wire, and the jacket are omitted from the differential signal transmission cable of FIG. 6. It is a figure which shows the twinax cable of the two-core lump structure of the structure which wound the shield material horizontally. It is a figure which shows the cable for multi-core differential signal transmission which accommodated 24 twinax cables of a two-core collective structure. It is a cross-sectional view of a conventional multicore differential signal transmission cable.

  Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a multicore differential signal transmission cable according to the present embodiment, and FIG. 2 is a perspective view of the tape conductor, braided wire, and jacket omitted.

  As shown in FIGS. 1 and 2, the multicore differential signal transmission cable 1 according to the present embodiment moves along the axial direction of the spiral tube 2 within the resin spiral tube 2 and the spiral tube 2. A plurality of (eight in FIG. 1 and FIG. 2) twinax cables 3 that are accommodated and arranged in parallel are provided. A gap 4 is formed between the spiral tube 2 and the twinax cable 3. Further, the outer periphery of the spiral tube 2 is covered with a tape conductor 5, a braided wire 6, and a jacket 7 in order.

  Here, “movable along the axial direction” means that the twinax cable is fixed in the axial direction or restricted in movement in the axial direction by an interposition between the twinax cables or a covering that bundles multiple twinax cables. It means a state that does not happen.

  That is, the multi-core differential signal transmission cable 1 according to the present invention is different from the conventional multi-core differential signal transmission cable in that a plurality of twinax cables 3 are not twisted and the twinax cable 3 is not twisted. It does not include any intervening gaps.

  In the present invention, since the twinax cable 3 is formed to be movable, a slight twist may occur naturally in manufacturing or use. Are also included in a state in which a plurality of twinax cables 3 are arranged in parallel.

  1 and 2 show that two twinax cables 3 are arranged in an orderly manner and six in the outer periphery thereof, the twinax cables 3 do not have to be arranged in an orderly manner. Actually, the twinax cable 3 is accommodated biased below the spiral tube 2 due to gravity.

  The spiral tube 2 is formed of a resin band 2a, and the band 2a is spirally wound. The strip-shaped body 2a constituting the spiral tube 2 is wound to the same diameter over the longitudinal direction, and has a tube shape as a whole.

  The spiral tube 2 is required to have heat resistance in the covering process of the braided wire 6 and the jacket 7, and it is necessary to protect the twinax cable 3 from external force. For this reason, it is desirable that the belt-like body 2a for forming the spiral tube 2 is made of a fluorine-based resin. For example, FEP (tetrafluoroethylene-hexafluoropyrene copolymer) is used as the fluorine resin.

  The inner diameter of the spiral tube 2 may be determined according to the desired size of the gap 4 and the number of twinax cables 3 to be accommodated. Further, the thickness and width (spiral pitch) of the band-like body 2a constituting the spiral tube 2 are not particularly limited, depending on the number of the twinax cables 3 to be accommodated and the intended use (required strength, etc.). What is necessary is just to determine suitably.

  In the twinax cable 3, two pairs of signal wires (cores) 10 formed by covering the conductors 8 with the insulator 9 are arranged in parallel, and the drain wires 11 are arranged along the cores 10 and one of these wires is arranged. The shield member 12 made of a metal tape is coated on the outer periphery. As the metal tape, for example, a copper / PET tape obtained by bonding a copper foil to a PET film can be used.

  As the shielding material, one obtained by horizontally winding the shielding material 12 as shown in FIG. 3 (a) may be used, or the shielding material 12 is vertically attached (cigarette winding) as shown in FIG. 3 (b). A thing may be used.

  However, in the structure in which the shield member 12 is horizontally wound as shown in FIG. 3A, the conductor layer and the insulator layer (copper and PET in the case of copper / PET tape) of the shield member 12 are periodically extended in the longitudinal direction. Repeatedly, a so-called suckout in which the amount of attenuation increases rapidly due to resonance with a high-frequency signal may occur. In this case, a suck-out can be suppressed by adopting a structure in which the shield material 12 is vertically attached as shown in FIG.

  When the spiral tube 2 is provided on the outer periphery of the twinax cable 3, for example, a plurality of twinax cables 3 are bundled together without being twisted, and the inner side of the record body in which the strip-shaped body 2a is wound around the outer periphery of the twinax cable 3 The belt-like body 2a may be stretched in the axial direction. Since a plurality of twinax cables 3 are temporarily bundled in manufacturing and are not fixed, they are movable along the axial direction of the spiral tube 2 when the spiral tube 2 is provided on the outer periphery thereof. . After the spiral tube 2 is formed, the outer periphery of the spiral tube 2 is covered with a tape conductor 5 such as an aluminum foil tape, a braided wire 6 such as a tin-plated wire, and a jacket 7 such as rubber, so that a multi-core differential signal transmission cable 1 is formed. Is obtained.

  Here, the frequency characteristics of the insertion loss between the multicore differential signal transmission cable 1 according to the present embodiment shown in FIG. 1 and the conventional multicore differential signal transmission cable 70 shown in FIG. 10 are compared. To do.

  4 shows the multi-core differential signal transmission cable 1 according to the present embodiment shown in FIG. 1, and FIG. 5 shows the differential signal of the conventional multi-core differential signal transmission cable 70 shown in FIG. The frequency dependence characteristics of the insertion loss SDD21 are shown respectively.

  4 and 5, the vertical axis represents the insertion loss SDD21 (dB) of the differential signal of the twinax cable, and the horizontal axis represents the frequency (GHz). 4 and 5 show the characteristics of two of the eight twinax cables, one of which is indicated by a thin line and the other by a bold line.

  As shown in FIG. 4, in the multi-core differential signal transmission cable 1 according to the present embodiment, the frequency-dependent characteristics of the differential signal insertion loss SDD 21 in the two twinax cables 3 are almost perfect. It looks like a single curve on the drawing. Further, the insertion loss SDD21 changes linearly with respect to the frequency, and it can be seen that the characteristics of the twinax cable are secured even when a plurality of twinax cables are assembled.

  On the other hand, as shown in FIG. 5, in the conventional multi-core differential signal transmission cable 70, the frequency-dependent characteristics of the differential signal insertion loss SDD21 in the two twinax cables 80 are greatly different. Furthermore, it does not change linearly with respect to the frequency, and it can be seen that the characteristic deterioration of the twinax cable is caused by the increase in the number of cores.

  The operation of the present embodiment will be described.

  In the multicore differential signal transmission cable 1, a plurality of twinax cables 3 are accommodated in the spiral tube 2 so as to be movable along the axial direction of the spiral tube 2.

  In the multicore differential signal transmission cable 1, since the respective twinax cables 3 are not twisted together, the twinax cable 3 is not crushed and deformed, and the characteristic degradation of the twinax cable 3 can be suppressed. That is, according to the multicore differential signal transmission cable 1, there is no deterioration in characteristics due to twisting of a plurality of twinax cables, and the twinax cable before being multicore even in a multicore state. The characteristics can be ensured.

  In the multicore differential signal transmission cable 1, the twinax cable 3 is accommodated in the spiral tube 2 so as to be movable in the axial direction, and a gap 4 is formed around the twinax cable 3. Therefore, when the multicore differential signal transmission cable 1 is bent, the twinax cable 3 can move to the gap 4, and the occurrence of skew between the pairs due to the bending of the multicore differential signal transmission cable 1 can be prevented. .

  In order to cope with the bending of the multi-core differential signal transmission cable 1, a method using a loose tube instead of the spiral tube 2 is conceivable. However, when a loose tube is used, a twinax cable is installed in the loose tube. It takes time to insert.

  On the other hand, the spiral tube 2 can be formed by, for example, bundling a plurality of twinax cables 3 and stretching the strip 2a in the axial direction from the inside of the record body in which the strip 2a is wound around the outer periphery thereof. The twinax cable 3 can be accommodated in the spiral tube 2 without taking time and effort. That is, the use of the spiral tube 2 makes it very easy to manufacture the multi-core differential signal transmission cable 1 compared to the case of using a loose tube.

  In addition, according to the present invention, the twinax cable 3 in the multicore differential signal transmission cable 1 does not have to be arranged in an orderly manner, and therefore the twinax cable is manufactured when the multicore differential signal transmission cable 1 is manufactured. There is no need to position 3, and the multi-core manufacturing process is facilitated. For this reason, it is possible to easily realize a multi-core differential signal transmission cable exceeding eight pairs, which has been difficult to realize in the past.

  Furthermore, in conventional multi-core differential signal transmission cables with a twisted twinax cable, there is a risk of the shield material being damaged and the shield material being damaged. However, in the present invention, since the twinax cable 3 is not twisted, it is possible to use the vertically attached twinax cable 3. As a result, it is possible to prevent the occurrence of suckout of the attenuation amount in the high frequency region and to apply a high frequency signal.

  Next, another embodiment will be described.

  The multi-core differential signal transmission cable 50 shown in FIGS. 6 and 7 has basically the same configuration as the multi-core differential signal transmission cable 1 described in FIGS. The difference is that an Inax cable 51 is used.

  As shown in FIG. 8, the twinax cable 51 is obtained by vertically wrapping a shield material 12 around the outer periphery of a two-core signal line 54 in which two conductors 52 arranged in parallel are covered with an insulator 53. It is.

  As shown in FIGS. 3A and 3B, in the twinax cable 3 in which two single-wire signal lines 10 are combined, the characteristics of the entire twinax cable 3 are varied due to variations in the characteristics of the insulator 9 of each signal line 10. Although there is a possibility of deterioration, in the twinax cable 51, two conductors 52 arranged in parallel are collectively covered with an insulator 53 to form a signal line 54, so the characteristics of the insulator 53 around the two conductors 52 are characteristic. Are substantially equal, and the characteristic degradation of the twinax cable can be suppressed.

  In the twinax cable 51, by covering the two conductors 52 at once, the dimensional error when forming the signal line 54 can be reduced, and the distance between the conductors 52 can be kept constant in the longitudinal direction. Furthermore, characteristic deterioration can be suppressed.

  Further, when two single-core signal lines 10 are combined like the twinax cable 3, two signal lines 10 originally designed one by one are combined, so the distance between the conductors 8 is the insulation of the signal lines 10. Although it is determined by the outer diameter of the body 9, according to the twinax cable 51 having the two-core collective structure, the distance between the two conductors 52 can be set to a desired distance.

  Thereby, the state of electromagnetic coupling of the twinax cable 51 can be controlled. For example, by reducing the distance between the conductors 52, the influence of the characteristics caused by the shield member 12 wound around the outer periphery of the insulator 53 can be reduced to a single signal. Compared with the case where two lines 10 are combined, the size can be reduced, and the characteristics can be made more stable and satisfactory.

  A multi-core differential signal transmission cable 60 shown in FIG. 9 is a multi-core differential signal transmission cable 50 shown in FIG. 6 and accommodates 24 twin-core cables 51 having a two-core structure. Thus, according to the present invention, a multi-core differential signal transmission cable exceeding eight pairs can be realized by using spiral tubes having a diameter corresponding to the number of twinax cables to be accommodated. In addition, although the case where eight or 24 twinax cables 51 were accommodated was described here, the number accommodated is not limited to this and may be two or more.

1 Multi-core differential signal transmission cable 2 Spiral tube 3 Twinax cable 4 Air gap 5 Tape conductor 6 Braided wire 7 Jacket 8 Conductor 9 Insulator 10 Signal line 12 Shielding material

Claims (5)

In a multi-core differential signal transmission cable formed by assembling a plurality of twinax cables,
A spiral tube made of resin, a plurality of the twinax cables which are accommodated in the spiral tube so as to be movable along the axial direction of the spiral tube, and are arranged in parallel; the twinax cable and the spiral; and a gap formed between the tube,
The multi-core differential signal transmission cable according to claim 1, wherein the spiral tube is formed by stretching a resin-made strip-like body wound in a record in the axial direction and spirally winding the strip .   The multi-core differential signal transmission cable according to claim 1, wherein no interposition is included in the spiral tube. The strip is a fluorine-based resin in which claim 1 or 2 multi-core differential signal transmission cable according. The twinax cable, two parallel arranged conductors and signal lines collectively coated with an insulator, to any claims 1 to 3 and a shielding member made of a metal tape provided on the outer periphery of the signal line The multi-core differential signal transmission cable described. The multi-core differential signal transmission cable according to claim 4 , wherein the shield material is vertically wound around an outer periphery of the signal line.