JP2020136082A - coaxial cable - Google Patents

Abstract

To provide a coaxial cable which prevents attenuation when a high-frequency signal is transmitted in a long distance, and is likely to be bent and routed when being laid in a long distance.SOLUTION: A coaxial cable includes: an internal conductor 2; an insulator 3 covering the periphery of the internal conductor 2; an external conductor 4 having a tape member 41 which has a resin layer 411 and a metal layer 412 provided on one surface of the resin layer 411, and is wound around the insulator 3, and a braid shield 42 covering the outer periphery of the tape member 41; and a sheath 5 covering the periphery of the external conductor 4, in which the internal conductor 2 is formed of a compressed twisted-wire conductor that is formed by twisting a plurality of element wires 2a and is compressed and worked so that a cross-sectional shape perpendicular to a cable longitudinal direction becomes a predetermined shape, and at least a part of the tape member 41 is not brought into close contact with the insulator 3 and is wound longitudinally around the insulator 3 with the metal layer 412 the outside.SELECTED DRAWING: Figure 1

Description

The present invention relates to a coaxial cable.

In recent years, the market for human-cooperative robots and small articulated robots has been expanding as a measure to improve productivity. As the robot cable used for such a robot, a cable for a movable part wired to a movable part of the robot and a cable for a fixed part for connecting the robot and a control device are used.

As prior art document information related to the invention of this application, there is Patent Document 1.

Japanese Patent No. 3671729

With the cable for the fixed portion, for example, transmission over a long distance of about 25 m to 100 m may be performed. Further, in recent years, it has been required to transmit a high frequency signal (for example, a band of 10 MHz to 6 GHz) such as a video signal taken by a camera installed in a robot or the like by using a coaxial cable. Therefore, the coaxial cable used for the fixed portion cable is required to have high transmission characteristics capable of transmitting high frequency signals over a long distance.

As such a coaxial cable, it is conceivable to apply a tape member such as a copper tape in which a copper foil is provided on a resin layer as an outer conductor. However, in such a coaxial cable, when a tape member such as a copper tape is spirally wound, a phenomenon called sack-out occurs in which abrupt attenuation occurs in a predetermined frequency band (for example, a band of several GHz). It ends up.

Further, as the coaxial cable used for the fixed portion cable, when a tape member is vertically attached and wound around the entire circumference of the insulator as shown in Patent Document 1 in a state of being in close contact with the insulator. , There are restrictions on the shape and location when arranging a long distance from the robot to the control device. For example, when a coaxial cable is bent and arranged, the insulators in close contact with the internal conductor or tape member, which is difficult to bend, may be pressed, and the transmission characteristics of high-frequency signals may be deteriorated. was there. Therefore, a coaxial cable that has both good high-frequency signal transmission characteristics (attenuation characteristics) and flexibility (flexibility) in long-distance transmission is desired.

Therefore, an object of the present invention is to provide a coaxial cable that is hard to be attenuated when a high frequency signal is transmitted over a long distance and is easy to bend and arrange when routing a long distance.

The present invention has an internal conductor, an insulator covering the periphery of the internal conductor, and a metal layer provided on one surface of the resin layer and the resin layer, for the purpose of solving the above problems. The inner conductor includes a tape member wound around the insulator, an outer conductor having a braided shield covering the outer periphery of the tape member, and a sheath covering the circumference of the outer conductor, and the inner conductor is made by twisting a plurality of strands. It is composed of a compression stranded wire conductor that has been compressed so that the cross-sectional shape perpendicular to the longitudinal direction of the cable is a predetermined shape, and at least a part of the tape member is not in close contact with the insulator, and the above Provided is a coaxial cable that is vertically attached around the insulator with the metal layer on the outside.

According to the present invention, it is possible to provide a coaxial cable that is hard to be attenuated when a high frequency signal is transmitted over a long distance and is easy to bend and arrange when routing a long distance.

It is a figure which shows the coaxial cable which concerns on one Embodiment of this invention, (a) is the sectional view which shows the cross section perpendicular to the cable longitudinal direction, (b) is the A part enlarged view. It is sectional drawing which shows the cross section perpendicular to the longitudinal direction of a tape member. It is explanatory drawing explaining the flexibility test.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

1A and 1B are views showing a coaxial cable according to the present embodiment, FIG. 1A is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of the cable, and FIG. 1B is an enlarged view of part A thereof.

As shown in FIG. 1, the coaxial cable 1 includes an inner conductor 2, an insulator 3 that covers the periphery of the inner conductor 2, an outer conductor 4 that covers the periphery of the insulator 3, and a sheath 5 that covers the periphery of the outer conductor 4. And have. The coaxial cable 1 is used, for example, as a cable for a fixed portion that connects a robot and a control device in a factory or the like, and its length is, for example, about 25 m to 100 m.

(Inner conductor 2)
In the coaxial cable 1 according to the present embodiment, the internal conductor 2 is made by twisting a plurality of strands 2a and compressing the inner conductor 2 so that the cross-sectional shape perpendicular to the longitudinal direction of the cable becomes a predetermined shape such as a circular shape. It consists of a compression stranded conductor. In the present embodiment, the internal conductor 2 is formed by compressing a stranded conductor obtained by concentrically twisting seven strands 2a through a die having a diameter smaller than that of the stranded conductor and having a circular outlet. did. The strands 2a arranged at the center have a substantially hexagonal shape in a cross-sectional view, and the six strands 2a arranged around the wires have a substantially fan shape in a cross-sectional view. In the coaxial cable 1 according to the present embodiment shown in FIG. 1, an example is shown in which the internal conductor 2 is composed of a compression stranded conductor having a circular cross-sectional shape, but the cross-sectional shape is a shape other than the circular shape ( For example, the inner conductor 2 may be composed of a compression stranded conductor that has been compressed into a polygonal shape such as a quadrangular shape. Since the inner conductor 2 is a compression stranded conductor having a circular cross section, the coaxial cable 1 can be easily bent in any direction, so that it is easy to bend and arrange.

A normal stranded conductor is more flexible and easier to bend than a single wire conductor, but its conductivity is low because there are many gaps between the strands. By using a compression stranded conductor as the internal conductor 2 as in the present embodiment, the strands 2a are in close contact with each other and there is no gap between the strands 2a, so that the conductivity is improved and good damping characteristics are obtained. At the same time, the flexibility can be maintained. Further, since the compression stranded conductor is a stranded conductor, it is less likely to break when bent as compared with a single wire conductor.

In order to obtain good damping characteristics, it is desirable that the conductivity of the compression stranded conductor used as the internal conductor 2 is 99% IACS or more. In the present embodiment, in order to realize high conductivity, an annealed copper wire made of unplated pure copper is used as the wire 2a of the internal conductor 2. However, plating may be performed as long as it is plated with a conductivity of 99% IACS or higher, and for example, a silver-plated annealed copper wire may be used as the wire 2a. Further, by compressing through a die, strain is applied to the wire 2a and the conductivity is lowered. However, after that, heat treatment (annealing treatment) is performed to remove the strain and conduct conductivity of 99% IACS or more. The rate can be achieved.

(Insulator 3)
As the insulator 3, the dielectric constant is as low as possible in order to improve the transmission characteristics of the high frequency signal (more specifically, for example, to make it difficult to attenuate the high frequency signal in the band of 10 MHz to 6 GHz when transmitted over a long distance). It is desirable to use one. In the present embodiment, as the insulator 3, a foam layer 31 made of a foamed resin that covers the periphery of the inner conductor 2 and a non-foamed layer 32 made of a non-foamed resin that covers the periphery of the foamed layer 31 are used. There was.

As the foam layer 31, for example, one made of irradiation-crosslinked polyethylene foam can be used. The degree of foaming in the foamed layer 31 may be 40 to 70. If the degree of foaming of the foamed layer 31 is less than 40, the dielectric constant becomes large and the transmission characteristics of high frequency signals deteriorate, and if the degree of foaming exceeds 70, the foamed layer 31 becomes too soft and when bent. This is because the coaxial cable 1 is easily crushed by an external force generated, and the transmission characteristics of high-frequency signals are deteriorated. As the non-foaming layer 32, one made of non-foaming irradiation cross-linked polyethylene formed by tube extrusion molding around the foaming layer 31 can be used. The non-foaming layer 32 plays a role of protecting the foaming layer 31 and a role of maintaining the outer shape (cross-sectional shape) of the insulator 3 in a circular shape while having an insulating property. That is, by having the non-foam layer 32, it is possible to prevent the foam layer 31 from being crushed when the coaxial cable 1 is bent, and thus it is possible to suppress deterioration of the transmission characteristics of the high frequency signal. Can be done.

(Outer conductor 4)
The outer conductor 4 has a tape member 41 that is vertically attached around the insulator 3, and a braided shield 42 that covers the outer periphery of the tape member 41.

(Tape member 41)
FIG. 2 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of the tape member 41. As shown in FIGS. 1 and 2, the tape member 41 has a resin layer 411 and a metal layer (metal foil) 412 provided on one surface of the resin layer 411. The tape member 41 is made of, for example, a resin layer 411 made of PET (polyethylene terephthalate) provided with a metal layer 412 made of copper, aluminum, or the like on one surface.

At least a part of the tape member 41 is not in close contact with a part of the insulator 3. The tape member 41 is vertically attached around the insulator 3 with the metal layer 412 as the outside. Further, the tape member 41 is not adhesively fixed to the outer periphery of the insulator 3. The tape member 41 is held by a braided shield 42 provided on the outer periphery thereof so that the winding is not unwound (so that the vertical winding is not opened and the insulator 3 is not exposed).

Here, "at least a part of the tape member 41 is not in close contact with the insulator 3" means that a part or all of the tape member 41 provided around the insulator 3 by vertical winding is the insulator 3. It means that it is not in contact with the surface of. Specifically, as shown in FIG. 1B, the range in which the maximum distance d from the surface of the insulator 3 to the inner surface of the tape member 41 (the surface facing the surface of the insulator 3) is 5 μm or more and 30 μm or less. The tape member 41 floats from the surface of the insulator 3 toward the braided shield 42. The maximum distance d is an insulator when the coaxial cable 1 is cut at a predetermined position and then the cross section of the cut portion (the cross section perpendicular to the longitudinal direction of the cable) is observed using an optical microscope or an electron microscope. It is obtained by measuring the maximum value of the linear distance from the surface of No. 3 to the inner surface of the tape member 41.

In the coaxial cable 1, the tape member 41 is provided around the insulator 3 by vertical winding in the state as described above, so that when the coaxial cable 1 is bent, the tape member 41 is on the surface of the insulator 3. Since it acts to move along the circumferential direction, the stress on the insulator 3 caused by bending can be relaxed, and the coaxial cable 1 can be provided with flexibility. As a result, in the coaxial cable 1, the coaxial cable 1 does not become stiff and has good flexibility (for example, flexibility that is easier to bend than the coaxial cable 1 in which the tape member 41 is spirally wound around the insulator 3). (Flexibility)). That is, the coaxial cable 1 has good transmission characteristics of high-frequency signals in long-distance transmission, and is easy to arrange when it is bent and routed over a long distance. In particular, when the distance d is 5 μm or more and 30 μm or less, the above-mentioned actions and effects can be easily obtained.

Therefore, "at least a part of the tape member 41 is not in close contact with the insulator 3" means that one end of the tape member 41 in the circumferential direction overlaps the outer periphery of the other end of the tape member 41. A portion that is not in close contact with the insulator 3 is generated near the end portion in the circumferential direction, or an air layer formed between the insulator 3 and the tape member 41 after the coaxial cable 1 is bent or the like. It does not include the occurrence of a portion where the tape member 41 is not in close contact with the insulator 3.

From the viewpoint of making the coaxial cable 1 easy to bend, it is preferable to wind the tape member 41 in a spiral shape. However, in this case, a phenomenon called suckout occurs in which abrupt attenuation occurs in a predetermined frequency band (for example, a band of several GHz). In the present embodiment, in order to suppress such a suckout and improve the transmission characteristics of a high frequency signal in long-distance transmission, the tape member 41 is vertically attached and wound.

The thickness d1 of the resin layer 411 is preferably 9 μm or more and 16 μm or less. This is because if the thickness d1 is less than 9 μm, the tape member 41 is easily torn, and if it exceeds 16 μm, the tape member 41 becomes hard and it becomes difficult to bend the coaxial cable 1. The thickness d2 of the metal layer 412 is preferably 7 μm or more and 11 μm or less. This is because if the thickness d2 is less than 7 μm, the metal layer 412 is likely to be cracked at the time of bending or the like, and if it exceeds 11 μm, the metal layer 412 becomes hard and it becomes difficult to bend the coaxial cable 1. In the present embodiment, the thickness d1 of the resin layer 411 is 12 μm, and the thickness d2 of the metal layer 412 is 9 μm.

A part of the tape member 41 enters between the insulator 3 and the tape member 41 by entering a gap 6 (see FIG. 1B) between the strands formed inside the braided shield 42 in the radial direction. The inner air layer 7 is formed in the air layer 7. For example, as shown in FIG. 1B, a gap 6 is formed between a plurality of first strands 421a constituting the first braided shield 421 of the braided shield 42 described later, and the gap 6 is formed. The structure is such that the tape member 41 provided in contact with the first braided shield 421 can be inserted. An inner air layer 7 is provided between the insulator 3 and the tape member 41 at a portion where the tape member 41 has entered the gap 6. The tape member 41 is loosely wound vertically around the insulator 3 (without being in close contact with the surface of the insulator 3) so that the inner air layer 7 is formed between the tape member 41 and the insulator 3.

For example, when the tape member 41 is wound vertically around the insulator 3, the tape member 41 is loosely wound vertically so that a part of the inner surface of the tape member 41 does not come into contact with the surface of the insulator 3, and then loosely wound vertically. The first braided shield 421 is provided around the tape member 41 so that the first braided shield 421 of the braided shield 42 presses (tightens) the entire outer periphery of the tape member 41 against the insulator 3 side. As a result, a part of the tape member 41 enters the gap 6 between the first strands 421a constituting the first braided shield 421, and in the portion where the tape member 41 enters the gap 6, the insulator 3 and the insulator 3 An inner air layer 7 can be formed between the tape member 41 and the tape member 41. With this configuration, when the coaxial cable 1 is bent during arrangement, the tape member 41 and the insulator 3 can move (slide) relative to the cable longitudinal direction or the cable circumferential direction. Therefore, the flexibility (flexibility) of the coaxial cable 1 is improved, and the coaxial cable 1 becomes easy to bend. The tape member 41 and the first braided shield 421 may be formed continuously on the same production line.

In order to improve the sliding between the tape member 41 and the insulator 3, the resin layer 411 of the tape member 41 may be made of fluororesin. Further, the resin layer 411 is located between the inner conductor 2 and the metal layer 412, and in order to contribute to the transmission characteristics, it is desirable that the dielectric constant is as low as possible. Examples of the fluororesin having a low dielectric constant and suitable for the resin layer 411 include PTFE (polytetrafluoroethylene). By using the tape member 41 having the resin layer 411 made of PTFE, it is possible to realize the coaxial cable 1 which is easier to bend and has more excellent transmission characteristics of high frequency signals.

Further, if the tape member 41 is tightly wound (closely adhered) to the insulator 3 by being adhered to the insulator 3, the tape member 41 is stretched and bent when the coaxial cable 1 is bent. There is a risk that it will be difficult or the tape member 41 will break due to bending. Further, in this case, when the coaxial cable 1 is bent, there is a risk that the insulator 3 may be cracked, or the arrangement of the wires constituting the braided shield 42 may be disturbed and the wires may be broken. By loosely winding the tape member 41 around the insulator 3 as in the present embodiment, the coaxial cable 1 can be bent more easily, the breakage of the tape member 41 when the coaxial cable 1 is bent can be suppressed, and further. It is possible to prevent the insulator 3 from being cracked and the wires constituting the braided shield 42 from being broken.

To prevent the tape member 41 from opening (unwinding the vertical winding) and exposing the insulator 3 when the coaxial cable 1 is bent, the tape member 41 has one end in the circumferential direction. It is preferable that the cable is vertically attached so as to overlap the outer circumference of the other end. That is, the width w perpendicular to the longitudinal direction of the tape member 41 is preferably larger than the length of the outer circumference of the insulator 3. More specifically, it is desirable that the width w of the tape member 41 is 1.3 times or more and less than 1.7 times the length of the outer circumference of the insulator 3. If the width w of the tape member 41 is less than 1.3 times the length of the outer circumference of the insulator 3, the tape member 41 may open and the insulator 3 may be exposed when the coaxial cable 1 is bent. This is because if the length of the outer periphery of the insulator 3 exceeds 1.7 times, the overlapping portion becomes too large and the coaxial cable 1 may become hard and difficult to bend. Further, by setting the width w of the tape member 41 to 1.3 times or more and less than 1.7 times the length of the outer periphery of the insulator 3, a gap formed between a plurality of first strands 421a is formed. The tape member 41 provided in contact with the first braided shield 421 can easily enter the sixth, which is effective for providing the inner air layer 7 between the insulator 3 and the tape member 41.

(Braid shield 42)
The braided shield 42 is provided around the tape member 41 and is provided around the first braided shield 421 formed by knitting the first wire 421a and the first braided shield 421, and is outside the first wire 421a. It has a second braided shield 422 formed by knitting a second wire 422a having a large diameter. In the braided shield 42, for example, as described above, a plurality of strands 421a are braided around a tape member 42 loosely vertically wound around the insulator 3 to provide a first braided shield 421. , A plurality of strands 422a are braided around the first braided shield 421, and the second braided shield 422 is provided so as to be in contact with the first braided shield 421. The formation of the first braided shield 421 and the second braided shield 422 may be continuously performed on the same production line, or may be performed on separate production lines.

The second braided shield 422 provided on the outside is mainly for shielding noise from the outside. The coaxial cable 1 is used in, for example, a factory, and is affected by high-energy noise such as low-frequency noise due to on / off of a motor that drives a robot, a control device, or the like. Therefore, in the second braided shield 422, it is desirable to use a second wire 422a having a large outer diameter to reduce the conductor resistance.

On the other hand, the first braided shield 421 provided inside is mainly for suppressing the internal signal from being radiated to the outside. Since the coaxial cable 1 transmits a high-frequency signal of, for example, 10 MHz to 6 GHz, if the mesh of the braided shield (gap between the strands) is large, the signal is likely to be radiated to the outside. Therefore, in the first braided shield 421, it is desirable to use the first wire 421a having a small outer diameter and reduce the mesh size. Further, if the outer diameter of the first wire 421a of the first braided shield 421 is increased, it becomes difficult to bend the coaxial cable 1.

More specifically, the outer diameter of the first wire 421a is preferably 0.08 mm or more and 0.14 mm or less in order to realize flexibility and fineness of the mesh. The outer diameter of the second wire 422a is preferably 0.10 mm or more and 0.16 mm or less in order to realize flexibility and small conductor resistance. Further, in order to clarify the functions of the first braided shield 421 and the second braided shield 422, the outer diameter of the first wire 421a may be 90% or less of the outer diameter of the second wire 422a. Here, the outer diameter of the first wire 421a is 0.12 mm, and the outer diameter of the second wire 422a is 0.14 mm.

(Sheath 5)
The sheath 5 is made of an insulating resin such as PVC (polyvinyl chloride), urethane, or polyolefin. The sheath 5 is formed by extrusion molding, but when solid molding is performed, the resin constituting the sheath 5 gets into between the strands 422a of the braided shield 42, and the coaxial cable 1 becomes hard and difficult to bend. Therefore, in the present embodiment, the sheath 5 is formed by tube extrusion. As a result, the resin constituting the sheath 5 is suppressed from entering between the strands 422a of the braided shield 42, and the sheath 5 and the braided shield 42 are separated. That is, in the present embodiment, the sheath 5 and the braided shield 42 are not in close contact with each other, and the air layer 8 is formed between the strands 422a constituting the braided shield 42. With this configuration, the braided shield 42 can move relatively freely in the sheath 5, and the coaxial cable 1 can be easily bent.

(Characteristics of coaxial cable 1)
The coaxial cable 1 of Example 1 according to the present invention was manufactured by the above-mentioned manufacturing method, and the damping characteristics were measured. In the coaxial cable 1 of the first embodiment, the characteristic impedance is 75Ω, the distance d from the surface of the insulator 3 to the inner surface of the tape member 41 vertically wound is in the range of 5 μm or more and 30 μm or less, and the outer diameter is 7. It was set to 65 mm. For comparison, a normal stranded conductor was used as the internal conductor, and a coaxial cable of Comparative Example 1 having substantially the same configuration as that of Example 1 except that the tape member was spirally wound was produced, and the damping characteristics were measured. .. The measurement results of Example 1 and Comparative Example 1 are shown in Table 1.

As shown in Table 1, the coaxial cable 1 of Example 1 has an attenuation characteristic of 0.17 dB / m in the 0.625 GHz band, an attenuation characteristic of 0.28 dB / m in the 1.25 GHz band, and a attenuation characteristic in the 6 GHz band. It can be seen that a very good damping characteristic is realized with a damping characteristic of 0.82 dB / m. On the other hand, in the coaxial cable of Comparative Example 1, the attenuation characteristic in the 0.625 GHz band is 0.49 dB / m and the attenuation characteristic in the 1.25 GHz band is 1.41 dB / m because it is also affected by the suckout. The attenuation characteristic in the m and 6 GHz band is 1.58 dB / m, which is a characteristic with extremely large attenuation.

Next, the coaxial cable 1 of Example 2 according to the present invention was produced in the same manner as the coaxial cable of Example 1, and the flexibility was tested. In the coaxial cable 1 of the second embodiment, the distance d from the surface of the insulator 3 to the inner surface of the tape member 41 wound vertically is set to be in the range of 5 μm or more and 30 μm or less. As shown in FIG. 3, in the flexibility test, the deflection of the coaxial cable 1 when one end of the coaxial cable 1 is fixed to the pedestal 91, the other end is extended 1000 mm from the pedestal 91, and the coaxial cable 1 is suspended by its own weight. The amount was measured. The amount of deflection was defined as the distance from the pedestal 91 to the coaxial cable 1 at a position 300 mm below the surface of the pedestal 91. Considering that the coaxial cable 1 is provided with a bending habit, the amount of deflection was measured in the direction in which the bending habit is applied (bending habit direction) and in the opposite direction.

For comparison, Comparative Examples 2 and 3 were prepared in which the configuration of the internal conductor was changed and the tape member was vertically attached and wound so as to be in close contact with the periphery of the insulator, and the same test was performed. In Comparative Example 2, the inner conductor 2 was a single wire conductor, and in Comparative Example 3, the inner conductor 2 was a stranded conductor. In both Example 2 and Comparative Examples 2 and 3, the conductor cross section was 0.82 mm ² , and the characteristic impedance was 75 Ω. The results of the flexibility test are summarized in Table 2.

As shown in Table 2, it can be seen that the coaxial cable 1 of the second embodiment according to the present invention has a small bending amount of 150 mm or less in both the bending habit direction and the opposite direction, and good flexibility is obtained. On the other hand, in Comparative Example 2 in which the insulator and the tape member are brought into close contact with each other using a single wire conductor, the amount of deflection is 200 mm or more in both the bending habit direction and the opposite direction, and sufficient flexibility is obtained. Not done. In Comparative Example 2, the amount of deflection is slightly smaller than that of Comparative Example 2 by using the stranded conductor, but the amount of deflection is 180 mm or more due to the influence of the tape member 41 wound in close contact with the conductor. It's getting bigger. As described above, the coaxial cable 1 according to the present invention realizes both good damping characteristics and good flexibility.

(Actions and effects of embodiments)
As described above, in the coaxial cable 1 according to the present embodiment, the internal conductor 2 is compressed so that a plurality of strands 2a are twisted together and the cross-sectional shape perpendicular to the longitudinal direction of the cable becomes a predetermined shape. At least a part of the tape member 41 is made of a compressed stranded conductor and is not in close contact with the insulator 3, and is vertically attached around the insulator 3 with the metal layer 412 as the outside.

The inner conductor 2 is composed of a compression stranded conductor, the tape member 41 is loosely wound around the insulator 3 (without being in close contact with the surface of the insulator 3), and the sheath 5 is formed by tube extrusion. By preventing the coaxial cable 1 from being in close contact with the braided shield 42, the transmission characteristics (attenuation characteristics) of the high-frequency signal of the coaxial cable 1 can be improved, and the flexibility of the coaxial cable 1 can be improved to make it easier to bend. Can be done. As a result, it is possible to realize a coaxial cable 1 that is not easily attenuated when a high-frequency signal is transmitted over a long distance and is easy to bend and arrange when routing a long distance.

(Summary of embodiments)
Next, the technical idea grasped from the above-described embodiment will be described with reference to the reference numerals and the like in the embodiment. However, the respective symbols and the like in the following description are not limited to the members and the like in which the components in the claims are specifically shown in the embodiment.

[1] An inner conductor (2), an insulator (3) that covers the periphery of the inner conductor (2), and a metal layer provided on one surface of the resin layer (411) and the resin layer (411) (1). An outer conductor (4) having a tape member (41) having 412) and wound around the insulator (3) and a braided shield (42) covering the outer periphery of the tape member (41), and the outer side. A sheath (5) that covers the periphery of the conductor (4) is provided, and the internal conductor (2) has a plurality of strands (2a) twisted together and has a predetermined cross-sectional shape perpendicular to the longitudinal direction of the cable. It is composed of a compression stranded conductor that has been compression-processed so as to be such that at least a part of the tape member (41) is not in close contact with the insulator (3), and the metal layer (412) is on the outside. A coaxial cable (1) that is vertically attached around an insulator (3).

[2] In the outer conductor (4), the braided shield (42) is not in close contact with the sheath (5), and an air layer is formed between the strands (422a) constituting the braided shield (42). The coaxial cable (1) according to [1], which has (8).

[3] The tape member (41) is vertically attached around the insulator (3) so that an inner air layer (7) is formed between the tape member (41) and the insulator (3). The coaxial cable (1) according to [1] or [2].

[4] The air layer (7) is formed by a part of the tape member (41) entering the gap (6) between the strands (421a) of the braided shield (42). 3] The coaxial cable described in.

[5] The item according to any one of [1] to [4], wherein one end of the tape member (41) in the circumferential direction is wound so as to overlap the outer periphery of the other end. Coaxial cable (1).

[6] The braided shield (42) is provided around the tape member (41), and is formed by braiding the first wire (421a) to the first braided shield (421) and the first braided shield (421). A second braided shield (422) provided around the 421) and formed by braiding a second wire (422a) having a diameter larger than that of the first wire (421a), [1] to [ 5] The coaxial cable (1) according to any one of the items.

[7] The coaxial cable (1) according to any one of [1] to [6], wherein the resin layer (411) of the tape member (41) is made of a fluororesin.

Although the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

In addition, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention.

1 ... Coaxial cable 2 ... Inner conductor 2a ... Wire 3 ... Insulator 4 ... Outer conductor 41 ... Tape member 411 ... Resin layer 412 ... Metal layer 42 ... Braided shield 421 ... First braided shield 421a ... First wire 422 ... 2nd braided shield 422a ... 2nd wire 5 ... sheath 7 ... inner air layer 8 ... air layer

The present invention has an internal conductor, an insulator covering the periphery of the internal conductor, and a metal layer provided on one surface of the resin layer and the resin layer, for the purpose of solving the above problems. The inner conductor includes a tape member wound around an insulator, an outer conductor having a braided shield covering the outer periphery of the tape member, and a sheath covering the circumference of the outer conductor, and the inner conductor twists a plurality of strands. It is composed of a compression stranded conductor that has been compressed so that the cross-sectional shape perpendicular to the longitudinal direction of the cable is a predetermined shape, and at least a part of the tape member enters the gap between the strands of the braided shield. As a result, an inner air layer is provided between the insulator and the inner air layer, and the insulation is provided within a range in which the maximum distance from the surface of the insulator to the inner surface of the tape member is 5 μm or more and 30 μm or less. The tape member provides a coaxial cable that floats from the surface of the body to the braided shield side and is vertically attached around the insulator with the metal layer on the outside.

Claims (7)

With the inner conductor
An insulator that surrounds the inner conductor and
An outer conductor having a resin layer and a metal layer provided on one surface of the resin layer, a tape member wound around the insulator, and a braided shield covering the outer periphery of the tape member.
A sheath that covers the periphery of the outer conductor is provided.
The internal conductor is composed of a compression stranded conductor obtained by twisting a plurality of strands and compression-processing so that the cross-sectional shape perpendicular to the longitudinal direction of the cable becomes a predetermined shape.
At least a part of the tape member is not in close contact with the insulator, and is vertically attached around the insulator with the metal layer on the outside.
coaxial cable. In the outer conductor, the braided shield is not in close contact with the sheath and has an air layer between the wires constituting the braided shield.
The coaxial cable according to claim 1. The tape member is vertically attached around the insulator so that an inner air layer is formed between the tape member and the insulator.
The coaxial cable according to claim 1 or 2. The inner air layer is formed by a part of the tape member entering the gap between the strands of the braided shield.
The coaxial cable according to claim 3. The tape member is wound so that one end in the circumferential direction overlaps the outer periphery of the other end.
The coaxial cable according to any one of claims 1 to 4. The braided shield is provided around the tape member and is provided around the first braided shield formed by knitting the first wire and the first braided shield, and has a diameter larger than that of the first wire. It has a second braided shield made by braiding the second wire.
The coaxial cable according to any one of claims 1 to 5. The resin layer of the tape member is made of fluororesin.
The coaxial cable according to any one of claims 1 to 6.

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