阅读说明：本技术 通信电缆 (Communication cable ) 是由 望月大辅 东征臣 石川将大 于 2020-04-17 设计创作，主要内容包括：一种通信电缆(1),具有将具备包覆导体(3)的绝缘层(4)的信号线(2)捻合而成的双绞线(5)和收纳双绞线(5)的外皮(7),所述通信电缆(1)的特征在于,双绞线(5)具有一对信号线(2)和一对填充线(6),信号线(2)和填充线(6)以交替排列的方式捻合。(A communication cable (1) having a twisted pair (5) formed by twisting signal lines (2) each having an insulating layer (4) covering a conductor (3) and a sheath (7) for housing the twisted pair (5), wherein the twisted pair (5) has a pair of signal lines (2) and a pair of filler lines (6), and the signal lines (2) and the filler lines (6) are twisted in an alternating arrangement.)

1. A communication cable having a twisted pair formed by twisting signal wires each having an insulating layer covering a conductor and a sheath for housing the twisted pair,

the twisted pair has a pair of the signal lines and a pair of the filler lines, the signal lines and the filler lines being twisted in an alternating arrangement.

2. The communication cable of claim 1,

a shield is disposed between the twisted pair and the jacket.

3. The communication cable of claim 1,

an aggregate yarn obtained by twisting a plurality of twisted pairs is covered with a sheath.

4. The communication cable of claim 3,

a shielding layer is disposed between the collective line and the sheath.

5. The communication cable according to any one of claims 1 to 4,

when the twisted pair is cut along a plane orthogonal to the longitudinal direction, a pair of signal lines constituting the twisted pair are in contact with each other.

6. The communication cable according to any one of claims 1 to 5,

the outer diameter of the filler wire is smaller than the outer diameter of the signal wire.

7. The communication cable of any one of claims 1 to 6,

the outer diameter of the filling line is defined as R₁Defining the outer diameter of the signal line as R₂Then, the relationship of equation 1 is satisfied.

8. The communication cable of any one of claims 1 to 6,

the outer diameter of the filling line is defined as R₁Defining the outer diameter of the signal line as R₂Then, the relationship of equation 2 is satisfied.

9. The communication cable of any one of claims 1 to 6,

the outer diameter of the filling line is defined as R₁Defining the outer diameter of the signal line as R₂Then, the relationship of equation 3 is satisfied.

10. The communication cable according to any one of claims 1 to 9,

the elongation of the filler line is equal to or greater than the elongation of the signal line.

11. The communication cable of any one of claims 1 to 10,

the elongation of the filler line is 10 times or more the elongation of the signal line.

12. The communication cable of any one of claims 1 to 11,

the filling line is made of a material having a dynamic friction coefficient of 0.3 or less.

13. The communication cable of any one of claims 1 to 12,

the filling line is made of a material having a static friction coefficient equal to or less than a dynamic friction coefficient.

Technical Field

The present invention relates to a communication cable, and more particularly to a communication cable used for a signal transmission path for LAN satisfying standard values of category 6 and category 6A, and suitable for use in a movable part of various industrial apparatuses such as robots represented by various service robots such as industrial robots and humanoid robots, semiconductor manufacturing apparatuses, and the like.

Background

A LAN cable having a structure in which a sheath is provided on the outer periphery of an aggregate in which a plurality of twisted pairs are aggregated is widely used as a representative communication cable. With the spread of communication devices and the increase in the amount of communication data accompanying the spread, a high-speed, large-capacity data transfer function is required for communication cables.

As a standard indicating the performance of the LAN cable, a standard such as "category" is used. Generally, popular LAN cables are classified into category 5, category 5e, category 6A, and category 7 in order from cables with low performance, and it is recommended to use LAN cables of category 6 or more in recent communication environments.

In addition, with the spread of IoT (Internet of things), there are increasing scenarios in which data communication functions are mounted in various industrial devices such as industrial robots and semiconductor devices, and there are also many scenarios in which LAN cables are used as communication cables used in these devices.

Fig. 8 shows a general configuration of a LAN cable (communication cable) of category 6. In general, the communication cable 50 has a configuration in which the outer jacket 57 is provided on the outer periphery of an aggregate in which 4 twisted pairs 55 formed by twisting 2 signal lines 52 are aggregated, and in the communication cable 50 of category 6, a configuration in which 4 twisted pairs 55 are aggregated with fillers (cross fillers 58) having a cross-shaped cross section interposed therebetween is increased. The cross filler 58 keeps the distance between the twisted pairs 55 at a certain value or more, thereby suppressing crosstalk attenuation caused when the twisted pairs 55 approach each other, and contributing to improvement of communication characteristics.

However, when the general communication cable 50 using the cross filler 58 is used for an industrial robot or a semiconductor device, the following problems occur.

In general, industrial robots and semiconductor devices include movable portions such as a rotating portion, a bending portion, and a U-shaped bending portion, and communication cables used in these devices generate loads such as bending along with movement of the devices.

The cross filler 58 is poor in flexibility due to its shape, and therefore, it is difficult to follow bending, and the amount of bending is limited in many cases, and it is likely to be broken by a load due to bending. In the case where the cross filler 58 is broken, the following situation also occurs: the proximity of twisted pairs 55 within communication cable 50 results in increased crosstalk attenuation and failure to achieve category-specific communication characteristics.

As LAN cables corresponding to category 6 using a method other than cross filler, there are LAN cables described in patent documents 1 and 2. In the LAN cable described in patent document 1, the twist pitch of the twisted pairs constituting the LAN cable is changed for each twisted pair, so that the standard value of category 6 is satisfied without using a filler. In the LAN cable described in patent document 2, the twist angle of the twisted pair constituting the LAN cable is set to a predetermined value, and the standard value of category 6 is satisfied without using a filler.

However, the LAN cables described in patent documents 1 and 2 do not mention the maintenance of communication characteristics in a scene where bending occurs. In particular, in a LAN cable not using a filler, twisted pairs constituting the LAN cable are always close to each other, and there is a concern that communication characteristics may be degraded when the twisted pairs are abnormally close due to bending.

In addition, when attention is paid to the operation of twisted pairs constituting a LAN cable, there are cases where: the coating of the signal lines constituting the twisted pair is compressed by a load due to bending, and the distance between the signal lines, particularly the distance between the conductors constituting the signal lines, varies at the bent portion. Due to this variation in distance, the radiation suppression effect of electromagnetic induction noise and the shielding effect of external electromagnetic induction noise of the twisted pair may vary, and this phenomenon also causes a reduction in communication characteristics.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-2837

Patent document 2: japanese laid-open patent publication No. 2001-155559

Disclosure of Invention

Problems to be solved by the invention

As described above, conventional communication cables have poor bending resistance, and it is difficult to maintain communication characteristics by repeated bending.

The present invention has been made in view of such circumstances, and an object thereof is to provide a communication cable which has excellent bending resistance and can maintain communication characteristics even when repeatedly bent.

Means for solving the problems

The communication cable according to claim 1 includes a twisted pair formed by twisting signal lines having an insulating layer covering a conductor, and a sheath for housing the twisted pair, wherein the twisted pair includes a pair of the signal lines and a pair of filler lines, and the signal lines and the filler lines are twisted in an alternating arrangement.

The communication cable according to claim 2 is characterized in that a shield layer is provided between the twisted pair and the sheath.

The communication cable according to claim 3 is characterized in that an aggregate formed by twisting a plurality of twisted pairs is covered with a sheath.

The communication cable according to claim 4 is characterized in that a shield layer is provided between the aggregate line and the outer sheath.

The communication cable according to claim 5 is characterized in that a pair of signal lines constituting the twisted pair are in contact with each other when the twisted pair is cut along a plane orthogonal to the longitudinal direction.

The communication cable according to claim 6, wherein the outer diameter of the filler wire is smaller than the outer diameter of the signal wire.

The communication cable according to claim 7, wherein the outer diameter of the filler wire is defined as R₁Defining the outer diameter of the signal line as R₂Then, the relationship of equation 1 is satisfied.

The communication cable according to claim 8, wherein the outer diameter of the filler wire is defined as R₁Determining the outer diameter of the signal lineIs defined as R₂Then, the relationship of equation 2 is satisfied.

The communication cable according to claim 9, wherein R is an outer diameter of the filler wire₁Defining the outer diameter of the signal line as R₂Then, the relationship of equation 3 is satisfied.

The communication cable according to claim 10, wherein the elongation of the filler wire is equal to or greater than the elongation of the signal wire.

The communication cable according to claim 11, wherein the elongation of the filler wire is 10 times or more the elongation of the signal wire.

The communication cable according to claim 12, wherein the filler wire is made of a material having a dynamic friction coefficient of 0.3 or less.

The communication cable according to claim 13, wherein the filler wire is made of a material having a static friction coefficient equal to or lower than a dynamic friction coefficient.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to suppress compression of the coating of the signal lines constituting the twisted pair, and to maintain a predetermined distance between the conductors even when the twisted pair is bent, and therefore, it is possible to maintain predetermined communication characteristics.

Drawings

Fig. 1 is an explanatory diagram showing an example of the configuration of a communication cable according to the present invention.

Fig. 2 is an explanatory diagram showing another example of the structure of the communication cable of the present invention.

Fig. 3 is an explanatory diagram illustrating twisted pairs of the communication cable of fig. 1 and 2.

Fig. 4 is an explanatory diagram showing a situation in which twisted pairs of the communication cable of fig. 2 are close to each other.

FIG. 5 is an explanatory view showing a test method of a bending resistance test.

Fig. 6A is an explanatory diagram showing transmission characteristics of the communication cable of embodiment 1.

Fig. 6B is an explanatory diagram showing transmission characteristics of the communication cable according to embodiment 1.

Fig. 7A is an explanatory diagram showing transmission characteristics of the communication cable of embodiment 2.

Fig. 7B is an explanatory diagram showing transmission characteristics of the communication cable of embodiment 2.

Fig. 8 is an explanatory diagram showing a basic configuration of a conventional communication cable having a cross filler.

Fig. 9 is an explanatory diagram of a case where a shield layer is provided on a twisted pair wire having a structure in which only 2 signal wires are twisted in the related art.

Fig. 10 is an explanatory diagram showing a basic configuration of a conventional communication cable having no filler wire.

Detailed Description

Hereinafter, a basic configuration of a communication cable according to the present invention will be described with reference to the drawings.

The communication cable 1 in fig. 1 is formed of a twisted pair 5 obtained by twisting a pair of signal lines 2 having a structure in which a conductor 3 is coated with an insulating layer 4 and a pair of filler wires 6, and the twisted pair 5 is housed in a sheath 7. The communication cable 1 is particularly provided with an example in which a shield layer 8 is provided to cover the signal line 2 and the filler line 6 both housed in the sheath 7 (however, in the communication cable, the shield layer is not essential).

The communication cable 10 in fig. 2 is configured by twisted pairs 15 obtained by twisting a pair of signal lines 12 having a structure in which an insulating layer 14 is coated on a conductor 13 and a pair of filler wires 16, and an aggregate obtained by twisting a plurality of twisted pairs 15 is housed in a sheath 17. The communication cable 10 is particularly provided with an example of a shield layer 18 to be covered by the communication line housed in the sheath 17 (however, in the communication cable, the shield layer is not essential). In the communication cable 10, particularly, the adhesive tape layer 19 is provided between the shield layer 18 and the aggregation line (however, in the communication cable, the adhesive tape layer is not essential).

The invention is characterized by having the following structure: as shown in fig. 3, the twisted pairs 5, 15 constituting the communication cables 1, 10 have a pair of signal lines 2, 12 and a pair of filler lines 6, 16, and the signal lines 2, 12 and the filler lines 6, 16 are twisted in an alternating arrangement.

By twisting the signal lines 2, 12 and the filler lines 6, 16 in an alternating arrangement, when the twisted pairs 5, 15 are bent along with bending of the communication cables 1, 10, particularly when bent along the line segment L in fig. 3, a part of the load intended to compress the insulating layers 4, 14 is absorbed by the filler lines 6, 16. Therefore, the load applied to the insulating layers 4 and 14 at the time of bending is reduced, and the compression of the insulating layers 4 and 14 is suppressed.

By suppressing the compression of the insulating layers 4 and 14, the variation in the distance between the conductors 3 and 13 of the signal lines 2 and 12 constituting the twisted pairs 5 and 15 is reduced, and the variation in the radiation suppression effect of electromagnetic induction noise and the shielding effect of external electromagnetic induction noise, which are possessed by the twisted pairs 5 and 15, is reduced. As a result, it is possible to suppress the variation in communication characteristics due to the bending of the communication cables 1 and 10 using the twisted pairs 5 and 15, and to contribute to maintaining predetermined communication characteristics.

Further, since the filler wires 6 and 16 absorb the load generated when the communication cables 1 and 10 are bent, the load on the signal wires 2 and 12 is reduced, and disconnection of the conductors 3 and 13 due to bending can be suppressed.

Further, by twisting the filler wires 6 and 16, the effect of improving the bending resistance to the shield layers 8 and 18 can be obtained as described below.

In general, when the communication cables 1 and 10 are configured, as shown in fig. 1 and 2, the shielding layers 8 and 18 collectively covering the signal lines housed in the outer covers 7 and 17 are often provided.

As shown in fig. 9, in general, when the shield layer 68 is provided on the twisted pair 65 having a structure in which only 2 signal lines 62 are twisted, the shield layer 68 is provided in a substantially elliptical portion, and the cross-sectional shape of the portion has a major axis and a minor axis.

When a communication cable having such a shield layer 68 with a cross-sectional shape having a major axis and a minor axis is bent, there is a difference in size between the major axis and the minor axis, and therefore, the following tendency exists: the load generated in the shield layer 68 varies, and the load is concentrated on a specific place. Therefore, the shield layer 68 is likely to be broken starting from the location where the load is concentrated.

On the other hand, when the shield layer 8 is provided, the twisted pair 5 used in the present invention has a shape close to a square as shown in fig. 1, and the difference in size between the major axis and the minor axis is substantially eliminated. Therefore, the load generated in the shield layer 8 when the communication cable 1 is bent is uniformly dispersed, and the breakage of the shield layer 8 is suppressed. As a result, the bending resistance of the communication cable 1 is improved.

As will be described later, the presence of the filler wire 6 also contributes to a reduction in the diameter of the communication cable 1.

When the shield layer 68 is provided on the twisted pair 65 formed by twisting only the signal lines 62, as shown in fig. 9, the shield layer 68 is in a state close to the signal lines 62, and 2 spaces surrounded by 2 signal lines 62 and the shield layer 68 are formed. On the other hand, when the shield layer 8 is provided on the twisted pair 5 in which the filler wire 6 is also twisted, 4 spaces surrounded by the signal wires 2, the filler wire 6, and the shield layer 8 are formed in addition to 2 spaces surrounded by the 2 signal wires 2 and the filler wire 6 due to the presence of the filler wire 6.

The space formed serves to lower the effective dielectric constant of the twisted pair 5 surrounded by the shield layer 8, and the more the space formed, the greater the effective relative dielectric constant is.

When setting the characteristic impedance of the twisted pair 5, it is necessary to adjust the inter-conductor distance in accordance with the effective dielectric constant of the twisted pair 5, but when the effective dielectric constant decreases, the inter-conductor distance for setting the predetermined characteristic impedance becomes shorter, so the outer diameter of the signal line 2 can be made smaller, and as a result, the outer diameter of the twisted pair 5 can be made smaller.

That is, the twisted pair 5 formed by twisting the filler wires 6 forms a large space due to the presence of the filler wires 6, and therefore the effective relative permittivity is significantly reduced, and the outer diameter can be set smaller than in the case where the filler wires 6 are not twisted, and therefore, it contributes to the reduction in the diameter of the communication cable 1 using the twisted pair 5.

Further, since signal attenuation due to dielectric loss is suppressed as the effective relative permittivity decreases, the presence of the filler wire 6 also contributes to improvement of communication characteristics.

As described above, the twisted pair 15 in which the signal line 12 and the filler line 16 are alternately twisted contributes to maintaining the communication characteristics even when the communication cable 10 is configured using an integrated line in which a plurality of twisted pairs 15 are twisted as shown in fig. 2.

In the communication cable 10 having a plurality of twisted pairs 15 shown in fig. 2, when the twisted pairs 15 are close to each other, crosstalk attenuation that is transmitted to the signal line 12 constituting one twisted pair 15 to the signal line 12 constituting the other twisted pair 15 is likely to occur in the signal, and the communication characteristics of the communication cable 10 are degraded by the crosstalk attenuation.

When the twist pitches of the twisted pairs 15 constituting the communication cable 10 are set to different values for the twisted pairs 15, crosstalk attenuation that significantly degrades the communication characteristics is not observed in portions that are close to each other in the contact with the outer diameter circle of the twisted pairs 15 as shown in fig. 4, and the communication characteristics of the communication cable 10 are maintained.

However, as shown in fig. 10, in the communication cable 70 having no filler wire, when the twisted pairs 75 are close to the extent that the outer diameter circles of the twisted pairs 75 overlap, crosstalk attenuation increases, and particularly, when one of the signal lines 72 constituting one twisted pair 75 enters the gap between the 2 signal lines 72 constituting the other twisted pair 75 and comes into contact with the 2 signal lines 72 constituting the other twisted pair 75, it can be confirmed that communication characteristics are degraded.

In the present invention, the filler wire 16 is twisted with the twisted pair 15, thereby restricting abnormal proximity of the signal wires 12 constituting the twisted pair 15, suppressing crosstalk attenuation, and maintaining the communication characteristics of the communication cable 10.

Twisted pair 15 of communication cable 10 used in the present invention has the following structure: since the pair of signal lines 12 and the pair of filler lines 16 are provided and the signal lines 12 and the filler lines 16 are twisted in an alternating manner, there is no gap between the 2 signal lines 72 constituting the other twisted pair 75 as shown in fig. 10 and the signal lines are in contact with the 2 signal lines 72 constituting the other twisted pair 75, and a predetermined communication characteristic can be maintained.

Since abnormal proximity of the twisted pair 75 shown in fig. 10 is likely to occur when the communication cable 70 is bent, deterioration of communication characteristics due to bending is suppressed by twisting the filler wire 16 in the twisted pair 15.

Further, since the filler wire 16 is present in the sheath 17 in a state twisted with the signal wire 12, the communication cable 10 of the present invention is superior in bending resistance to the communication cable 50 using the cross filler.

In the present invention, as shown in fig. 3, it is preferable that the pair of signal lines 2 and 12 are twisted so that the signal lines 2 and 12 are in contact with each other when the pair of signal lines 2 and 12 constituting the twisted pairs 5 and 15 are viewed in cross section.

By bringing the pair of signal lines 2 and 12 constituting the twisted pairs 5 and 15 into contact with each other, the twisted pairs 5 and 15 have a stable radiation suppression effect of electromagnetic induction noise and a shielding effect of external electromagnetic induction noise due to the configuration of the twisted pairs 5 and 15, and contribute to maintaining communication characteristics.

In the present invention, it is preferable that the outer diameters of the filler wires 6 and 16 are smaller than the outer diameters of the signal wires 2 and 12. By making the outer diameters of the filler wires 6, 16 smaller than the outer diameters of the signal wires 2, 12, the filler wires 6, 16 can be suppressed from interfering with the contact of the signal wires 2, 12 constituting the twisted pairs 5, 15, and the outer diameters of the twisted pairs 5, 15 can also be suppressed, contributing to the reduction in the diameters of the communication cables 1, 10.

Preferably, the outer diameter of the filling line 6, 16 is defined as R₁The outer diameters of the signal lines 2 and 12 are defined as R₂The outer diameter R of the filling lines 6, 16₁In the range shown in the following formula 1.

By making the outer diameter R of the filling line 16₁In the formulaThe range of 1 can suppress the signal lines 12 constituting the twisted pairs 15 from approaching to such an extent as to affect the communication characteristics even when the twisted pairs 15 are close in the communication cable 10 obtained by twisting a plurality of twisted pairs 15, and contributes to maintaining the communication characteristics.

Further, preferably, R is₁In the range shown in the following formula 2.

By making the outer diameter R of the filling lines 6, 16₁In the range of expression 2, the increase in the outer diameter of the twisted pairs 5 and 15 due to the presence of the filler wires 6 and 16 can be suppressed, contributing to the reduction in the diameter of the communication cables 1 and 10. In addition, the outer diameter R of the filling line 16₁When the upper limit of expression 2 is close, the twisted pair 15 is round as a whole, and the gap between the twisted pairs 15 is reduced when the sheath 17 is provided in the communication cable 10 in which a plurality of twisted pairs 15 are twisted, so that the positional relationship of the twisted pairs 15 is not easily distorted when the communication cable 10 is bent, and this contributes to maintaining the communication characteristics.

As described above, R is particularly preferable in the present invention₁The range of (b) is a range represented by the following formula 3.

By making the outer diameter R of the filling lines 6, 16₁In the range of expression 3, the signal lines 2 and 12 can be prevented from approaching each other to such an extent that they affect the communication characteristics, and the outer diameters of the twisted pairs 5 and 15 can be prevented from increasing due to the presence of the filler lines 6 and 16, which contributes to both maintenance of the communication characteristics and reduction in diameter.

The filler wires 6 and 16 used in the present invention are preferably made of a material having excellent sliding properties. By using the filler wires 6 and 16 having excellent slidability, frictional resistance between the twisted pairs 5 and the inner circumferential surface of the sheath 7 and between the twisted pairs 15 when a plurality of twisted pairs 15 are used is also reduced, and the sliding of the twisted pairs 5 and 15 occurring when the communication cables 1 and 10 are bent is smoothed. As a result, the load on the twisted pairs 5 and 15 is reduced, and disconnection of the signal lines 2 and 12 due to bending can be suppressed, which contributes to improvement in the bending resistance of the communication cables 1 and 10.

In the case where the tape layer 19 and the shield layers 8 and 18 for noise countermeasure, which will be described later, are provided between the twisted pairs 5 and 15 and the outer covers 7 and 17, damage due to abrasion of the tape layer 19 and the shield layers 8 and 18 can be suppressed by using a material having excellent slidability for the filler wires 6 and 16, and therefore, the communication characteristics can be maintained.

Specifically, it is preferable to use a material having a dynamic friction coefficient of 0.3 or less as the filling lines 6 and 16. Examples of the material having a coefficient of dynamic friction of 0.3 or less include fluororesin, polyethylene, nylon 66, and the like.

Further preferably, a material having a static friction coefficient equal to or less than a dynamic friction coefficient is used as the filling lines 6 and 16. A general material has a larger static friction coefficient than a dynamic friction coefficient, but some sliding materials have a static friction coefficient equal to or lower than a dynamic friction coefficient. By using the above-described material for the filler wires 6 and 16, the sliding of the twisted pairs 5 and 15 generated when the communication cables 1 and 10 are bent is made smoother, which contributes to the improvement of the bending resistance of the communication cables 1 and 10.

In the present invention, "a material having a static friction coefficient equal to or less than a dynamic friction coefficient" means a material that exhibits a property that the static friction coefficient is equal to or less than the dynamic friction coefficient when the same materials are brought into contact with each other and slid. The dynamic friction coefficient and the static friction coefficient in the present invention are values measured in accordance with JIS K7125.

It is preferable that the filling lines 6 and 16 have an elongation equal to or greater than that of the signal lines 2 and 12. By setting the elongation of the filler wires 6, 16 to be equal to or more than the elongation of the signal wires 2, 12, disconnection of the filler wires 6, 16 at the time of bending can be suppressed, which contributes to maintaining the communication characteristics at the time of bending the communication cables 1, 10.

More preferably, the elongation of the filler wires 6, 16 is preferably 10 times or more the elongation of the signal wires 2, 12. By making the elongation of the filler wires 6, 16 sufficiently higher than the elongation of the signal wires 2, 12, the disconnection suppressing effect of the filler wires 6, 16 at the time of bending and the communication characteristic maintaining effect can be improved.

The filler wires 6 and 16 used in the present invention can be used by appropriately selecting a monofilament material and a multifilament material.

The monofilament filling lines 6 and 16 are preferably not easily deformed when bent from the viewpoint of maintaining communication characteristics. By using the monofilament filling lines 6 and 16 which are hardly deformed, even when the insulating layers 4 and 14 in the twisted pairs 5 and 15 are compressed and a plurality of twisted pairs 15 are used, the proximity of the twisted pairs 15 is suppressed, which contributes to maintaining the communication characteristics, and the monofilament filling line 16 is preferably excellent in the slidability with less unevenness on the surface.

A specific material of the filling lines 6, 16 particularly preferably used in the present invention is PTFE which is a kind of fluororesin. PTFE has a static friction coefficient of not more than a dynamic friction coefficient and excellent mechanical strength such as high elongation. Further, since the dielectric constant is small, transmission loss at the time of twisting with the signal lines 2 and 12 is suppressed, which also contributes to maintaining communication characteristics.

PFA, FEP, ETFE as other fluororesins are also suitable for use in the present invention because they have a static friction coefficient equal to or less than a dynamic friction coefficient, a high elongation, and a low dielectric constant.

The filling lines 6 and 16 may have a porous structure or a hollow structure from the viewpoint of maintaining communication characteristics. Since the porous structure or the hollow structure contains air, it has a lower dielectric constant than that of the solid structure, and contributes to maintaining communication characteristics, and also contributes to improving bending resistance because of excellent flexibility.

As the filling threads 6 and 16 having a porous structure, stretched PTFE having a porous structure formed of nodes and fibrils formed by stretching treatment in the production process can be preferably used. PTFE after the stretching treatment is excellent in mechanical strength against elongation, and therefore, PTFE can be preferably used from the viewpoint of improving bending resistance.

As the hollow-structured filling lines 6 and 16, hollow-structured filling lines obtained by extruding a fluororesin into a tubular shape can be used.

In addition, from the viewpoint of reducing the diameter of the communication cables 1 and 10, the filler wires 6 and 16 having a low dielectric constant may be preferably used.

As an example of a communication cable, there is a LAN cable (communication cable 10) using 4 twisted pairs, but a conventional LAN cable has an outer diameter of about 5 to 7mm, and a cable having an outer diameter of 5mm or less tends to be handled as a small-diameter cable.

When the outer diameter of the LAN cable is 5mm or less, the outer diameter of the twisted pair 15 is preferably 1mm or less, and it is necessary to sufficiently reduce the effective relative permittivity in order to reduce the outer diameter of the twisted pair 15. By using the filler line 16 having a low dielectric constant, the effect of lowering the effective relative permittivity due to the presence of the space formed by the filler line 16 is also used, and the effective relative permittivity of the twisted pair 15 can be sufficiently reduced.

In order to set the outer diameter of the twisted pair 15 to 1mm or less, the filler wire 16 made of a material having a dielectric constant of 2.4 or less may be used, and various fluororesins may be preferably used. Among fluororesins, PTFE can be particularly preferably used.

When the communication cable 10 is configured by using a plurality of twisted pairs 15, the twisted pairs 15 having the same twist direction may be used for the twist direction of the twisted pairs 15, or the twisted pairs 15 having different twist directions may be used in combination.

From the viewpoint of maintaining communication characteristics, it is preferable to combine twisted pairs 15 having different twist directions. By making the twist direction of the twisted pair 15 different, the direction of the unevenness existing on the surface of the twisted pair 15 is different, and it is possible to suppress the proximity in which the outer diameter circles of the twisted pair 15 overlap.

In the present invention, the presence of the filler wire 16 can suppress the approach of overlapping of outer diameter circles of the twisted pairs 15, and therefore, the present invention can be particularly preferably used when the twist directions of the twisted pairs 15 are aligned.

The conductors 3 and 13 used in the present invention may be selected as appropriate and used as known conductors for electric wires and cables. From the viewpoint of bending resistance and torsion resistance, it is preferable to select a conductor having a structure excellent in bending resistance and torsion resistance.

The insulating layers 4 and 14 used in the present invention may be made of any material known as an insulating material for electric wires and cables. From the viewpoint of bending resistance, as in the case of the filler wires 6 and 16, a fluororesin such as PTFE, PFA, FEP, or ETFE can be preferably used.

In the communication cables 1 and 10 of the present invention, the combination of the material of the filler wires 6 and 16 constituting the twisted pairs 5 and 15 and the material of the insulating layers 4 and 14 used for the signal lines 2 and 12 can further improve the bending resistance.

As an example, a mode in which a material having a higher flexural modulus than that of the filler wires 6 and 16 is used for the insulating layers 4 and 14 may be mentioned. By making the insulating layers 4, 14 have a larger flexural modulus of elasticity than the filler wires 6, 16, the filler wires 6, 16 deform more than the insulating layers 4, 14 when the communication cables 1, 10 are bent. As a result, the load due to bending is absorbed mainly by the filler wires 6 and 16, and this contributes to suppressing breakage of the insulating layers 4 and 14 and disconnection of the conductors 3 and 13.

As another example, the insulating layers 4 and 14 may be made of a material having a lower tensile elastic modulus than the filler wires 6 and 16. When the communication cables 1, 10 are bent, a force is generated which stretches the twisted pairs 5, 15 toward both sides of the bent portion. At this time, by making the tensile elastic modulus of the insulating layers 4, 14 smaller than that of the filler wires 6, 16, the insulating layers 4, 14 constituting the signal lines 2, 12 twisted together with the filler wires 6, 16 are less likely to be subjected to tensile deformation before the filler wires 6, 16 start tensile deformation. That is, the load due to the tension is absorbed mainly by the filler wires 6 and 16, which contributes to suppressing breakage of the insulating layers 4 and 14 and disconnection of the conductors 3 and 13.

When the PTFE filler wires 6 and 16 particularly preferably used in the present invention are used, the insulating layers 4 and 14 that can be preferably used are made of FEP, which tends to have a higher flexural modulus and a lower tensile modulus than PTFE.

It is also preferable to use a method in which the insulating layers 4 and 14 and the filling lines 6 and 16 are made of the same material. When the insulating layers 4 and 14 and the filler wires 6 and 16 are made of the same material, when the communication cables 1 and 10 are bent, the load generated in the signal wires 2 and 12 and the filler wires 6 and 16 is substantially equally distributed to the signal wires 2 and 12 and the filler wires 6 and 16, and therefore, concentration of the load on the signal wires 2 and 12 is suppressed, which contributes to suppression of breakage of the insulating layers 4 and 14 and disconnection of the conductors 3 and 13.

Examples of a method of forming the insulating layers 4 and 14 and the filler lines 6 and 16 from the same material include a method of using FEP and a method of using PFA.

In the above description, insulated wires in which the conductors 3 and 13 are covered with the insulating layers 4 and 14 are used as the signal lines 2 and 12, but the configuration of the signal lines 2 and 12 is not limited thereto, and known coaxial cables may be used as the signal lines 2 and 12.

The outer skins 7 and 17 may be made of any material known as a material for outer skins of cables, such as PVC and silicone rubber.

As shown in fig. 2, a tape layer 19 covering the twisted pair 15 and a shield layer 18 for noise countermeasure may be provided between the twisted pair 15 and the sheath 17. Further, the present invention is focused on obtaining a communication cable having excellent communication characteristics without using a cross filler, but a modification using a cross filler may be adopted as needed.

Hereinafter, communication cables 1 and 10 configured by using 4 or 1 twisted pair 5 and 15 will be described as examples of the present invention.

Example 1

As shown in fig. 2, the communication cable 10 of example 1 uses 4 twisted pairs 15, and the signal line 12 and the filler line 16 used in the twisted pair 15 are designed in common in each twisted pair 15.

As the signal line 12, FEP as the insulating layer 14 was coated with a thickness of 0.16mm by an extrusion molding machine on the outer periphery of a conductor 13 made of a tin-plated annealed copper wire having a diameter of 0.26mm, and a signal line having an outer diameter of 0.58mm was prepared. The elongation of the signal line 12 is less than 10%.

As the filling line 16, PTFE fibers having a diameter of 0.38mm were prepared. The diameter of the filling line 16 is substantially equal to the upper limit of the range shown in the above formula 2. The filling line 16 has an elongation of 200% or more.

There are 2 signal lines 12 and 2 filler lines 16, and the signal lines 12 and the filler lines 16 are twisted in an alternating arrangement to form a twisted pair 15. By changing the pitch of the twisted pairs 15, 4 kinds of twisted pairs 15 were prepared.

The twist directions of the twisted pairs 15 are all unified in the same direction. In addition, the twisted pairs 15 are in a state where the signal lines 12 are in contact with each other in a cross-sectional view at the stage of completion of twisting, and have an outer diameter of 1.2 mm.

The prepared 4 kinds of twisted pairs 15 are collectively twisted to form an integrated wire. The twist direction is opposite to the twist direction of twisted pair 15. The diameter of the total twisted pair 15 is 2.8 mm.

An aluminum laminated PET (polyethylene terephthalate) tape is transversely wound as a tape layer 19 around the outer periphery of the twisted pair 15 after the total twisting.

Next, the shield layer 18 is provided on the outer periphery of the tape layer 19. The shield layer 18 was a braided shield made of 16 groups of wire bundles in which 8 shield wires were aligned in parallel to each other, and a copper foil wire having an outer diameter of 0.08mm was used as the shield wire.

Finally, the outer periphery of the shield layer 18 was coated with PVC (polyvinyl chloride) as the outer sheath 17 with a thickness of 0.4mm using an extrusion molding machine, thereby completing the communication cable 10 of example 1. The outer diameter of the communication cable 10 is finally 4 mm.

Example 2

The communication cable of embodiment 2 has the same configuration as that of embodiment 1, and therefore, the description will be given using fig. 2. The communication cable 10 of example 2 uses 4 twisted pairs 15, and the signal line 12 and the filler line 16 used in the twisted pair 15 are designed in common in each twisted pair 15.

As the signal wire 12, FEP as the insulating layer 14 was coated with a thickness of 0.095mm by an extrusion molding machine on the outer periphery of a conductor 13 having an outer diameter of 0.24mm, which was formed by concentrically twisting 7 tinned annealed copper wires having a diameter of 0.08mm, to prepare a signal wire having an outer diameter of 0.43 mm. The elongation of the signal line 12 is less than 10%.

As the filling line 16, PTFE fibers having a diameter of 0.42mm were prepared. The diameter of the filler wire 16 is about the same as the diameter of the signal wire 12, and is out of the range shown in the above equation 2. The filling line 16 has an elongation of 200% or more.

There are 2 signal lines 12 and 2 filler lines 16, and the signal lines 12 and the filler lines 16 are twisted in an alternating arrangement to form a twisted pair 15. By changing the pitch of the twisted pairs 15, 4 kinds of twisted pairs 15 were prepared.

The twist directions of the twisted pairs 15 are all unified in the same direction. In addition, the twisted pairs 15 are in a state where the signal lines 12 are in contact with each other in a cross-sectional view at the stage of completion of twisting, and have an outer diameter of 0.9 mm.

The prepared 4 kinds of twisted pairs 15 are collectively twisted to form an integrated wire. The twist direction is opposite to the twist direction of twisted pair 15. The diameter of the total twisted pair 15 is 2.8 mm.

An aluminum laminated PET (polyethylene terephthalate) tape is transversely wound as a tape layer 19 around the outer periphery of the twisted pair 15 after the total twisting.

Next, the shield layer 18 is provided on the outer periphery of the tape layer 19. The shield layer 18 was a braided shield made of 16 groups of wire bundles in which 8 shield wires were aligned in parallel to each other, and a copper foil wire having an outer diameter of 0.08mm was used as the shield wire.

Finally, the outer periphery of the shield layer 18 was coated with PVC (polyvinyl chloride) to be the outer sheath 17 with a thickness of 0.4mm using an extrusion molding machine, thereby completing the communication cable 10 of example 2. The outer diameter of the communication cable 10 is finally 4 mm.

Example 3

As shown in fig. 1, the communication cable 1 of example 3 uses only 1 twisted pair 5.

As the signal line 2, the following signal lines are prepared: a twisted wire was formed by twisting 7 tin-plated copper alloy wires having a diameter of 0.05mm, and FEP as an insulating layer 4 was coated on the outer periphery of a conductor 3 formed of a collective twisted wire formed by twisting 3 wires of this twisted wire by an extrusion molding machine to have a thickness of 0.15mm, thereby forming a signal wire having an outer diameter of 0.58 mm. The elongation of the signal line 2 is less than 10%.

As the filling thread 6, PTFE fibers having a diameter of 0.38mm were prepared. The diameter of the filling line 6 is substantially equal to the upper limit of the range represented by the above formula 2. The filling line 6 has an elongation of 200% or more.

The twisted pair 5 is formed by twisting 2 signal lines 2 and 2 filler lines 6 in such a manner that the signal lines 2 and the filler lines 6 are alternately arranged. The twisted pair 5 is in a state where the signal lines 2 are in contact with each other in a cross-sectional view at the stage of completion of twisting, and has an outer diameter of 1.2 mm.

Next, the shield layer 8 is provided on the outer peripheries of the signal line 2 and the filler line 6. The shield layer 8 was a braided shield composed of 24 groups of wire bundles in which 7 shield wires were aligned in parallel to each other, and a copper foil wire having an outer diameter of 0.08mm was used as the shield wire.

Finally, the outer periphery of the shield layer 8 was coated with PVC (polyvinyl chloride) to be the outer sheath 7 with a thickness of 0.4mm using an extrusion molding machine, thereby completing the communication cable 1 of example 3. The outer diameter of the communication cable 1 is finally 2.3 mm.

[ comparative example ]

A communication cable was produced in the same manner as the communication cable of example 3, except that the filler wire 6 was omitted from the communication cable 1 of example 3, as a communication cable of a comparative example to example 3.

The transmission characteristics of the communication cables of the examples and comparative examples prepared as described above were compared before and after the bending resistance test. In the communication cables 10 of examples 1 and 2 including the plurality of twisted pairs 15, and the communication cables of examples 3 and comparative examples including 1 twisted pair 5, since there is a difference in durability and evaluation items due to differences in size and structure, test conditions and evaluation items are partially changed in consideration of this, and details are as follows.

[ Transmission characteristic evaluation methods for examples 1 and 2]

The NEXT (Near End crosstalk Talk) of the communication cable 10 is evaluated by following the method of TIA/EIA-568-b.2-1 to evaluate the transmission characteristics for the magnitude of the minimum margin of NEXT required for the category 6A communication cables.

[ method for testing bending resistance in examples 1 and 2]

The bending resistance of the communication cable 10 was evaluated in the bending resistance test apparatus 100 shown in fig. 5. The test conditions were: the communication cable 10 having a length of 1000mm and fixed upward by the fixing portion 101 and loaded with a load 103 of 500g is gently sandwiched between the mandrels 102 of the R20mm, and bent at a rate of 90 degrees and 60 times/minute to the left and right. The bending was performed 90 degrees to the left and right, and the NEXT after 10 ten thousand bending was examined and compared with the NEXT before bending.

The design and evaluation results of the communication cables 10 of examples 1 and 2 are shown in table 1, and NEXT of examples 1 and 2 before and after the bending resistance test is shown in fig. 6A, 6B, 7A, and 7B.

[ Table 1]

The communication cable 10 of example 1 had a minimum margin of +8.9dB relative to the standard value for category 6A, which also did not change after the flex resistance test. From the above, it can be said that the communication cable 10 of embodiment 1 is a communication cable excellent in bending resistance capable of maintaining communication characteristics even when repeatedly bent.

The communication cable 10 of example 2 has a minimum margin of +4.3dB relative to the standard value for category 6A, which decreases to +3.8dB after the bend resistance test. From the above, the communication cable 10 of embodiment 2 is a communication cable for category 6A having practical bending resistance, but it can be said that the communication cable for category 6 has sufficient performance as a communication cable for category 6, because there is still a margin for the required characteristics of category 6A, although the communication cable is repeatedly bent.

As a result of examples 1 and 2, it can be said that, based on the above equation 2, it is preferable in terms of communication characteristics and bending resistance when the diameter of the filler wire 16 constituting the twisted pair 15 is smaller than the diameter of the signal wire 12, as compared with the case where the diameter of the signal wire 12 is made to be the same.

[ Transmission characteristic evaluation methods for example 3 and comparative example ]

The transmission characteristics were evaluated according to the conductor resistance values of the signal lines 2 constituting the communication cable 1. The conductor resistance value was measured as follows: at one end of a communication cable 1 cut to a predetermined length, conductors 3 of 2 signal lines 2 constituting the communication cable 1 are brought into contact, and at the other end of the communication cable 1, a test lead on the positive side of a tester is connected to the conductor 3 of one signal line 2, and a test lead on the negative side is connected to the conductor 3 of the other signal line 2. The measurement was performed at normal temperature, and the transmission characteristics were evaluated. The higher the conductor resistance value is, the more the transmission characteristics deteriorate.

[ method for testing bending resistance of example 3 and comparative example ]

In example 3, the bending resistance of the communication cable 1 was also evaluated by using the bending resistance test apparatus 100 shown in fig. 5. The test conditions were as follows: a communication cable 1 having a length of 1000mm and fixed upward by a fixing portion 101 and loaded with a load 103 of 100g is gently sandwiched between mandrels 102 of R3mm, and bent at 90 degrees and 90 times/minute every time to the left and right. The conductor was bent 90 degrees to the left and right, and 1 time was taken, and the change in the conductor resistance value with the increase in the number of times of bending was examined and compared with the conductor resistance value before bending.

Table 2 shows the design and evaluation results of the communication cable 1 of example 3 and comparative example.

[ Table 2]

The conductor resistance value of the communication cable 1 of example 3 was 600m Ω, a value indicating that there was no trouble when used as a communication cable, no change at the time when the number of bending times reached 1 ten thousand 6000 times, and an increase to 612m Ω at the time when the number of bending times reached 16 ten thousand times. The increase amount is 2%, which is an increase in the extent that no particular trouble occurs when the cable is used as a communication cable. In addition, no disconnection of the conductor 3 constituting the signal line 2 was observed.

On the other hand, the conductor resistance value of the communication cable of the comparative example was 600m Ω before the bending resistance test as in example 3, but was 690m Ω at the time when the number of bending times reached 1 ten thousand 6000 times, and was increased by 10% or more, and disconnection of the conductor was also confirmed. It is estimated that the communication cable of the comparative example is broken due to the load caused by bending of the conductor and the resistance value of the conductor increases, and it is estimated that the communication cable 1 of example 3 absorbs the load caused by bending by the filler wire 6 and reduces the load on the conductor 3, thereby suppressing the progress of the disconnection.

From the above, it can be said that the communication cable 1 of example 3 is a communication cable excellent in bending resistance capable of maintaining communication characteristics even when repeatedly bent.

As described above, the present inventors have conducted intensive studies on the structure of a communication cable, and as a result, have found that if the compression of the coating of a signal line present in a twisted pair constituting the communication cable is suppressed and the signal line constituting the twisted pair adjacent to a gap between the signal lines is not dented, a communication characteristic sufficient for practical use can be obtained, thereby obtaining a communication cable in which the compression of the coating, the dent of the signal line is suppressed and the durability against bending is also improved.

In addition, the communication cable of the present invention can expect the following excellent effects.

(1) The compression of the coating of the signal lines constituting the twisted pair is suppressed, and a predetermined distance between the conductors can be maintained even when the twisted pair is bent, so that predetermined communication characteristics can be maintained.

(2) Since predetermined communication characteristics can be obtained while minimizing the change in the outer diameter of the twisted pair, it contributes to the reduction in the diameter of the communication cable.

(3) In the case of a communication cable formed using a plurality of twisted pairs, even if the communication cable has excellent communication characteristics without using a cross filler, the bending resistance is improved as compared with a communication cable using a cross filler because the cross filler is not used.

(4) When a communication cable is formed using a plurality of twisted pairs, it is possible to suppress abnormal proximity of the twisted pairs and maintain predetermined communication characteristics even when the communication cable is bent.

The present application claims priority of patent application No. 2019-085722, filed in japan on 26/4/2019. The present specification is incorporated in its entirety with reference to the specification, claims and drawings of Japanese patent application laid-open No. 2019-085722.

The present invention is capable of various embodiments and modifications without departing from the broader spirit and scope of the invention. The above embodiments are illustrative of the present invention, and do not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the claims. Also, various modifications made within the meaning of the claims and equivalent inventions are regarded as being within the scope of the present invention.

Industrial applicability

As described above, the communication cable of the present invention is suitably used for movable parts of various industrial apparatuses such as robots represented by various service robots such as industrial robots and humanoid robots, semiconductor manufacturing apparatuses, and the like, but the use is not limited thereto, and a communication cable used for other than the movable parts or a power supply cable for movable parts not involving communication may be suitably used.

Description of the reference numerals

1 communication cable

2 signal line

3 conductor

4 insulating layer

5 twisted pair

6 filling line

7 outer skin

8 Shielding layer

10 communication cable

12 signal line

13 conductor

14 insulating layer

15 twisted pair

16 filling line

17 outer skin

18 shield layer

19 adhesive tape layer