JP6893419B2 - coaxial cable - Google Patents

Description

The present invention relates to a coaxial cable used as a signal transmission line for high-frequency components such as information communication equipment, communication terminal equipment, and measuring equipment, and a device wiring path for medical equipment such as an endoscope and an ultrasonic diagnostic device.

In recent years, information communication equipment and communication terminal equipment have become smaller and smaller, the wiring space in the equipment has become narrower, and the coaxial cable is required to have a smaller diameter.
On the other hand, it is desired to maintain high frequency characteristics such as attenuation in information communication equipment having a small diameter but increasing in speed and capacity.

As a thinning of the coaxial cable, in addition to a horizontal winding shield structure in which a metal wire is wound around the outer circumference of an insulator, a structure in which a substantially rectangular ribbon-shaped conductor is spirally wound is known. (Patent Document 1, Patent Document 2)
However, the horizontal winding shield structure is still insufficiently thinned, and the ribbon-shaped conductor tends to be inferior in flexibility, and further improvement is required.

JP-A-2009-146850 Japanese Unexamined Patent Publication No. 2000-353435

The subject of the present invention is to reduce the diameter of the coaxial cable, and even if the diameter is small, it is excellent in high frequency characteristics such as attenuation, reflection loss (VSWR), shield characteristics, and crosstalk, and is also excellent in flexibility. To provide coaxial cables.

The gist of the present invention is as follows.

(1) In a coaxial cable having a shield layer, at least one layer of the shield layer has a structure in which a plurality of substantially flat conductors (substantially flat square members) are wound in parallel so as not to overlap each other. Have.
(2) In a coaxial cable having a shield layer, at least one layer of the shield layer is wound in a state in which a plurality of substantially flat conductors (substantially flat lumber) are arranged in parallel so as not to overlap each other. The winding angle α (<90 °) of the substantially flat square timber with respect to the line direction of the coaxial cable is 10 ° to 40 °.
( 3 ) In a coaxial cable having a shield layer, the shield layer has a structure in which a conductive tape material is vertically attached and a substantially flat square material is wound around the tape material.
(4) The dielectric outer diameter D constituting the coaxial cable and the width W of the substantially flat square lumber constituting the shield layer satisfy the following relational expressions.
(Relational expression) 0.7 ≤ D / W ≤ 10
(5) The dielectric outer diameter D constituting the coaxial cable and the thickness T of the substantially flat square lumber constituting the shield layer satisfy the following relational expressions.
(Relational expression) 8 ≤ D / T ≤ 80
(6) The shielding density of the substantially flat lumber constituting the shield layer is 80% or more.
( 7 ) The gap distance between the wound substantially flat lumber is 100 μm or less.
( 8 ) The tape material constituting the shield layer is vertically attached in a state where both ends in the width direction do not overlap.
( 9 ) In the vertically attached tape material, the gap distance to which the tape is not applied is 200 μm or less.

According to the present invention, the excellent effects described below can be expected.

(1) Since the inner conductor is not thinned but the outer conductor is thinned to reduce the diameter, it is possible to reduce the diameter while maintaining high frequency characteristics such as the amount of attenuation.
(2) Since a substantially flat square lumber is used, the outer conductor can be made thinner (that is, the diameter can be reduced) compared to a round wire, and a plurality of conductors can be arranged in parallel and wound together, so that the diameter is approximately flat. Compared to the case of wrapping one square timber, the flexibility is significantly improved.
(3) If the double structure is such that a conductive tape material is vertically attached as a shield layer and a substantially flat metal material is wound around the shield layer, the diameter is reduced and high frequencies such as attenuation and shield characteristics are obtained. It is also excellent in characteristics.
(4) Further, by setting the specifications (width, thickness) of the substantially flat square timber of the present invention, the relational expression of the outer diameter of the dielectric, the winding angle, and the gap distance between the substantially flat square timbers, the flexibility is not sacrificed. The diameter can be reduced, and free wiring can be performed inside a smaller device.
(5) Since the substantially flat square lumber is wider than the round wire, the number of wraps can be reduced as compared with the case where the round wire is used. As a result, the winding tension can be set high, and the occurrence of disconnection, overrunning (hump), etc. can be suppressed.
(6) In addition, compared to the case where a large number of round wires are bundled and wound as in the past, when a small number of wide wires are wound as in the substantially flat square lumber of the present application, the gap between the wires is reduced, so that the shield is used. It also contributes to the improvement of characteristics.
(7) Since the tape material of the present invention is vertically attached in a state where both ends in the width direction do not overlap, stable production is achieved by preventing the tape material from being inverted, wrinkled, broken, etc. when winding a substantially flat square material. It will be possible.

Sectional drawing which shows an example of the coaxial cable which concerns on this invention Schematic diagram of a substantially flat lumber constituting the shield layer of the present invention Schematic diagram showing winding of a substantially flat lumber of the present invention Schematic diagram showing how to evaluate flexibility Evaluation result (attenuation amount) of electrical characteristics of a coaxial cable or the like according to the present invention. Evaluation Results of Electrical Characteristics of Coaxial Cable, etc. According to the Present Invention (Reflection Loss (VSWR)) Evaluation Results of Electrical Characteristics of Coaxial Cable, etc. According to the Invention (Crosstalk)

Hereinafter, as an example of the coaxial cable of the present invention, the basic configuration will be described with reference to the drawings.

The coaxial cable 1 of FIG. 1 is, in order from the center, an inner conductor 2, a dielectric layer 3, a tape material 4 forming a shield layer 6, a substantially flat square material 5, and an outer layer 7.

At least one layer of the shield layer has a structure in which a plurality of substantially flat conductors (substantially flat square members) are wound in a state of being arranged in parallel so as not to overlap each other. From the viewpoint of high frequency characteristics, it is preferable that the shield layer 6 is provided with two layers, a layer in which the conductive tape material 4 is vertically attached and a layer in which a plurality of substantially flat conductors (substantially flat square members) 5 are wound.

The material of the tape material 4 is not particularly limited as long as it has conductivity and shield characteristics can be obtained.
For example, a composite tape with a resin such as polyester provided with a metal foil such as copper or aluminum on both sides or one side, a metal foil tape such as copper or aluminum, a tape containing a conductive filler, or the like can be mentioned.

The dimensions of the tape material 4 are not particularly limited, but it is preferable that the tape material 4 is vertically attached in a state where both ends in the width direction do not overlap. The state in which both ends in the width direction do not overlap indicates that the width of the tape material 4 is smaller than the peripheral diameter of the dielectric. (Fig. 3)
Further, the gap distance (in the circumferential direction) where the tape material 4 is not applied is preferably 200 μm or less, more preferably 150 μm or less, from the viewpoint of preventing inversion, wrinkles, breakage, etc. of the tape material.
It is most preferably 100 μm or less from the viewpoint of shielding characteristics and preventing dielectric damage due to laser light during terminal processing.

The material of the substantially flat lumber 5 is preferably made of metal, but may contain a resin or the like as long as the shielding characteristics are maintained, and is not particularly limited. An annealed copper wire or a hard copper wire plated with silver, tin, or the like is preferable.

The shape of the substantially flat square lumber 5 is not particularly limited as long as it is, for example, a rolled metal conductor of a round shape, has a shape such as an ellipse or a flat square, and has a thickness smaller than that of a round wire.

The number of substantially flat square timbers 5 is not particularly limited as long as it is 2 or more, but 4 to 16 pieces are preferable from the viewpoint of flexibility and productivity.
By making the number more than 4, the width of the substantially flat square timber 5 can be reduced, which contributes to flexibility, and by making it smaller than 16, the strength of wrapping around the wire can be set strongly, and the unevenness becomes more uneven. Since a small amount of smooth surface can be obtained, unevenness defects are suppressed and contribution to productivity is contributed.

The substantially flat square timber 5 is composed of a plurality of pieces bundled in an appropriate number of holdings, and the substantially flat square timbers are wound in a state of being arranged in parallel so as not to overlap each other. By winding a plurality of substantially flat square timbers 5 having a small diameter at the same time, it contributes to flexibility. Although the manufacturing method is not limited, it is preferable that a plurality of substantially flat lumbers are wound together at the same time.

The specifications of the substantially flat lumber 5 and the winding angle are preferably set as follows for the purpose of maintaining the flexibility of the coaxial cable 1.

That is, it is preferable that the width W of the substantially flat lumber 5 satisfies the following relational expression with the dielectric outer diameter D constituting the coaxial cable.
0.7 ≦ D / W ≦ 10 (relationship formula 1)
Further, from the viewpoint of flexibility and productivity, more preferably.
2 ≦ D / W ≦ 8 (relationship formula 2)
Is.

This relational expression indicates that a suitable width of a substantially flat lumber can be set with respect to the outer diameter of the dielectric in order to maintain flexibility. In particular, as shown by the relational expression 2, when the dielectric outer diameter D is about 2 to 8 times the width of the substantially flat lumber, both flexibility and productivity are excellent.
That is, when it is 2 times or more, it contributes more flexibility, and when it is 8 times or less, the number of substantially flat lumber can be reduced, which contributes to productivity.

Regarding the thickness T of the substantially flat lumber 5, it is preferable that the outer diameter D of the dielectric constituting the coaxial cable satisfies the following relational expression.
8 ≦ D / T ≦ 80 (relationship formula 3)
Further, from the viewpoint of flexibility and productivity, more preferably.
8 ≦ D / T ≦ 60 (relationship formula 4)
Is.

This relational expression indicates that an appropriate thickness of a substantially flat lumber can be set with respect to the outer diameter of the dielectric in order to maintain flexibility. In particular, as shown by the relational expression 4, when the dielectric outer diameter D is about 8 to 60 times the thickness of the substantially flat lumber, both flexibility and productivity are excellent.
That is, when it is 8 times or more, it contributes more flexibility, and when it is 60 times or less, the winding strength can be set strongly, which further contributes to productivity.

The shielding density of the substantially flat lumber 5 is preferably 80% or more, but is particularly preferably 90% or more from the viewpoint of shielding characteristics.

The winding angle α (<90 °) of the substantially flat lumber 5 is preferably 5 ° to 60 ° with respect to the line direction of the coaxial cable 1. From the viewpoint of improving productivity, it is more preferably 5 ° to 50 °. In addition to improving productivity, it is most preferably 10 ° to 40 ° from the viewpoint of flexibility. (Fig. 3)

It is preferable that each of the substantially flat square timbers 5 is arranged in parallel so as not to overlap each other. That is, since both ends in the width direction do not overlap each other, no matter which part of the coaxial cable 1 is taken, only one layer of substantially flat lumber is applied, so that smoothness is maintained and electrical characteristics are improved. Connect.

The gap distance between the wound substantially flat square timbers 5 is preferably 50 μm or less from the viewpoint of shield characteristics. The smaller the gap distance, the smoother the flat lumber is applied, the lower the reflection loss (VSWR) is suppressed, and the more it contributes to the improvement of the damping characteristics. Therefore, it is more preferably 30 μm or less, most preferably 30 μm or less. It is 20 μm or less.

(Measurement method of flexibility)
The flexibility of the coaxial cable 1 is evaluated by a method in which a cable having a constant length with a weight at the tip is hung from a measuring table and the degree of dripping is measured. (See Fig. 4)
(1) Fix the cable to the measuring table. At that time, fix the cable so that it protrudes 50 mm outside the fulcrum of the base, and attach a weight of 5 g to the tip of the cable.
(2) Measure the horizontal distance X between the base and the cable at a point 25 mm below the fulcrum.

The remaining configuration in the present invention is a general cable specification and is not particularly limited.

Hereinafter, the coaxial cable 1 (FIG. 1) of the present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited thereto.

(Examples 1 to 4, Comparative Examples 1 to 2, Conventional Examples 1 to 2)
In Example 1, the inner conductor 2 is a silver-plated annealed copper wire 7 / 0.05 having an outer diameter of 0.15 mm, and the dielectric 3 is a PFA resin having a wall thickness of 0.125 mm and an outer diameter of 0.40 mm.
The shield layer 6 is formed by vertically attaching a copper polyester tape having a width of 1.20 mm and a thickness of 0.01 mm, and two substantially flat square timbers 5 made of silver-plated annealed copper wire having a width of W0.60 mm and a thickness of T0.05 mm. Bundle them, arrange them in parallel so that they do not overlap each other, and wind them all at once. The winding angle of the substantially flat lumber 5 is 12 °.
The outer layer 5 is a PFA resin having a wall thickness of 0.05 mm and an outer diameter of 0.56 mm.

In Example 2, in Example 1, the dimensions of the substantially flat lumber 5 are a width W0.16 mm, a thickness T0.02 mm, and a number of holdings of eight.

In Example 3, the outer diameter of the dielectric is 0.60 mm, and the dimensions of the substantially flat lumber 5 are width W0.08 mm, thickness T0.01 mm, and number of holdings 24.

In the fourth embodiment, the outer diameter of the dielectric is 0.80 mm, and the dimensions of the substantially flat square lumber 5 are a width W0.08 mm, a thickness T0.01 mm, and a number of 30 pieces.

In Comparative Example 1, in Example 1, the outer diameter of the dielectric is 0.34 mm, and the dimensions of the substantially flat square lumber 5 are a width W of 0.60 mm, a thickness of T0.05 mm, and two holdings.

In Comparative Example 2, in Example 1, the outer diameter of the dielectric is 0.90 mm, and the dimensions of the substantially flat lumber 5 are a width W0.08 mm, a thickness T0.01 mm, and a number of 30 pieces.

In Conventional Example 1, the shield structure is a general braided structure, and the outer diameter of the outer layer 5 is 0.81 mm. (The outer diameter of the dielectric is the same size as in Example 2, and the characteristic impedance is adjusted to 50Ω.)

In Conventional Example 2, the shield structure is a general horizontal winding structure, and the outer diameter of the outer layer 5 is 0.64 mm. (The outer diameter of the dielectric is the same size as in Example 2, and the characteristic impedance is adjusted to 50Ω.)

The electrical characteristics (attenuation amount, return loss (VSWR), crosstalk) of Examples 2 and Conventional Examples 1 and 2 were evaluated, and the results are shown in FIGS. 5 to 7.

(Electrical characteristic evaluation method)
Cable length: 1000 mm (with measurement connector)
Measuring instrument: Network analyzer Frequency range: 0-12GHz

From FIGS. 5 to 7, in the second embodiment of the present invention, as compared with the braided structure of the conventional example 1 and the horizontal winding structure of the conventional example 2, the attenuation amount and the reflection loss (VSWR) are reduced in spite of the small diameter. , Crosstalk, all of which are excellent in electrical characteristics.

As a reason for the excellent electrical characteristics, in Example 2 of the present invention, the diameter is reduced by using a substantially flat square timber 5 instead of using a conventional round wire as the shield layer 6, while copper is used inside the substantially flat square timber. The vertical attachment of polyester tape contributes to the amount of attenuation and reflection loss (VSWR). Further, since the substantially flat square timbers 5 are densely arranged in parallel, it is considered that the excellent smoothness also contributes to the crosstalk in addition to the attenuation amount and VSWR.

Table 1 shows the evaluation results of flexibility and appearance of Examples 1 to 4, Comparative Examples 1 and 2, and Conventional Examples 1 and 2.

All of Examples 1 to 4 were confirmed to be superior in terms of flexibility and productivity.

In particular, in Examples 2 and 3 of the present invention, even if the D / W is 2 to 8 or the D / T is 8 to 60 and the structure is such that the substantially flat lumber 5 is wound, the conventional examples 1 to 1 to 3 While maintaining the same flexibility as No. 4, it can be said that the flat lumber 5 is excellent in productivity (appearance) because there is no unevenness due to disconnection or overcoming.

Compared with Comparative Example 1, when the D / W is 0.7 or more, or the D / T is 8 or more, the influence of the substantially flat lumber on the flexibility can be suppressed to a low level, and the number of holdings is 2 or more. Therefore, the tension at the time of winding is maintained appropriately, the appearance defect is reduced, and the productivity is improved.

When the D / W is 10 or less or the D / T is 80 or less as compared with Comparative Example 2, the number of substantially flat square timbers 5 can be reduced, appearance defects such as unevenness due to overlapping can be reduced, and productivity can be improved. Contribute to improvement.

From the above, the embodiment of the present invention is superior to the braided structure of Conventional Example 1 and the horizontal winding structure of Conventional Example 2 in spite of its small diameter, and is excellent in electrical characteristics such as attenuation, VSWR, and crosstalk. Despite the fact that the substantially flat lumber 5 is used, it has the same flexibility as the conventional example and is excellent in productivity.

The coaxial cable of the present invention has excellent high-frequency characteristics such as attenuation while being easily reduced in diameter, and is also excellent in flexibility. Therefore, signals of high-frequency components such as information communication equipment, communication terminal equipment, and measuring equipment are also excellent. It is useful not only for transmission lines and equipment wiring lines for medical instruments such as endoscopes and ultrasonic diagnostic devices, but also for signal transmission lines for small electronic devices in general.

1 Coaxial cable 2 Inner conductor 3 Dielectric layer 4 Tape material 5 Approximately flat square lumber 6 Shield layer 7 Outer layer W Approximately flat lumber width T Approximately flat lumber thickness α Approximately flat lumber winding angle X Measurement length (index of flexibility) )

Claims (9)

In a coaxial cable with a shield layer
A coaxial cable characterized in that at least one layer of the shield layer has a structure in which a plurality of substantially flat conductors (substantially flat square members) are wound in a state of being arranged in parallel so as not to overlap each other.
In a coaxial cable with a shield layer
At least one layer of the shield layer has a structure in which a plurality of substantially flat conductors (substantially flat square members) are wound in a state of being arranged in parallel so as not to overlap each other.
A coaxial cable characterized in that the winding angle α (<90 °) of a substantially flat square timber with respect to the line direction of the coaxial cable is 10 ° to 40 °.
In a coaxial cable with a shield layer
The shield layer is vertically attached with a conductive tape material.
Characterized in that it has a winding attaching structure the substantially flat wire over said tape,
The coaxial cable according to claim 1 or 2.
The dielectric outer diameter D constituting the coaxial cable and the width W of the substantially flat square lumber constituting the shield layer satisfy the following relational expressions.
The coaxial cable according to any one of claims 1 to 3.

(Relational expression) 0.7 ≤ D / W ≤ 10
The dielectric outer diameter D constituting the coaxial cable and the thickness T of the substantially flat square lumber constituting the shield layer satisfy the following relational expressions.
The coaxial cable according to any one of claims 1 to 4.

(Relational expression) 8 ≤ D / T ≤ 80
The shielding density of the substantially flat lumber constituting the shield layer is 80% or more.
The coaxial cable according to any one of claims 1 to 5.
The gap distance between the wound substantially flat lumber is 100 μm or less.
The coaxial cable according to any one of claims 1 to 6.
The tape material constituting the shield layer is characterized in that both ends in the width direction are vertically attached without overlapping.
The coaxial cable according to any one of claims 1 to 7.
In the vertically attached tape material, the gap distance to which the tape is not applied is 200 μm or less.
The coaxial cable according to any one of claims 1 to 8.

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