JP5863156B2 - Differential signal transmission cable - Google Patents
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- JP5863156B2 JP5863156B2 JP2015030283A JP2015030283A JP5863156B2 JP 5863156 B2 JP5863156 B2 JP 5863156B2 JP 2015030283 A JP2015030283 A JP 2015030283A JP 2015030283 A JP2015030283 A JP 2015030283A JP 5863156 B2 JP5863156 B2 JP 5863156B2
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Description
本発明は、差動信号伝送用ケーブルに関する。 The present invention relates to a differential signal transmission cable.
従来の技術として、平行に並べられた一対の絶縁電線に、さらに、少なくとも１本のドレイン導体を平行に並べ、この一対の絶縁電線とドレイン導体とを一括して金属箔テープで巻き回してシールド導体とし、このシールド導体の外周部を外被で覆った平行２心シールド電線が知られている（例えば、特許文献１参照）。 As a conventional technique, a pair of insulated wires arranged in parallel is further arranged in parallel with at least one drain conductor, and the pair of insulated wires and the drain conductor are collectively wrapped with a metal foil tape to be shielded. 2. Description of the Related Art A parallel two-core shielded electric wire that is a conductor and whose outer periphery is covered with a jacket is known (for example, see Patent Document 1).
特許文献１に記載の平行２心シールド電線は、金属箔テープの巻き回しによりシールド導体を形成するので、製造にかかる時間を短縮することができる。 Since the parallel two-core shielded electric wire described in Patent Document 1 forms a shield conductor by winding a metal foil tape, the manufacturing time can be shortened.
特許文献１に係る平行２心シールド電線は、短手方向の断面において、金属箔テープが平坦な部分が生じる。この平坦な部分は、金属箔テープの張力の方向と、平坦な部分の表面が作る面と、が平行となるため、張力に基づく金属箔テープを押し付ける圧力が発生しなくなり、金属箔テープが緩み易くなる。従来の平行２心シールド電線は、金属箔テープの緩みによって、スキュー（skew）および差動同相変換量が増加する問題がある。 In the parallel two-core shielded electric wire according to Patent Document 1, a flat portion of the metal foil tape is produced in the cross section in the short direction. In this flat part, the direction of the tension of the metal foil tape and the surface created by the surface of the flat part are parallel to each other, so that the pressure for pressing the metal foil tape based on the tension is not generated and the metal foil tape is loosened. It becomes easy. The conventional parallel two-core shielded electric wire has a problem that skew and differential common-mode conversion amount increase due to looseness of the metal foil tape.
従って、本発明の目的は、スキューおよび差動同相変換量を抑制する差動信号伝送用ケーブルを提供することにある。 Accordingly, an object of the present invention is to provide a differential signal transmission cable that suppresses skew and differential common-mode conversion.
本発明は、上記目的を達成するため、離れて平行に並んだ一対の導体と、一対の導体を被覆し、短手方向の断面の外周形状が曲率半径が異なる複数の曲線を組み合わせた形状となる絶縁体と、絶縁体上に継ぎ目または重なり合う領域をらせん状に有するように巻き付けて設けられ、短手方向の断面の内周形状が絶縁体の外周形状に基づいた複数の曲線を組み合わせた形状となるシールド導体と、前記シールド導体を被覆した被覆部材と、を備え、前記シールド導体は、前記被覆部材と向い合う金属箔を有し、前記絶縁体は、前記断面の前記外周形状が楕円形状を有し、前記複数の曲線の曲率半径の最小値が、前記複数の曲線の曲率半径の最大値の１／２０以上１／４以下であると共に、前記断面の短径が、長径の０．３７倍以上０．６３倍以下である差動信号伝送用ケーブルを提供する。 In order to achieve the above-mentioned object, the present invention has a pair of conductors arranged in parallel apart from each other, a shape that covers the pair of conductors, and a combination of a plurality of curves having different curvature radii in the outer peripheral shape of the cross section in the short direction. And a shape in which the inner peripheral shape of the cross section in the short direction is a combination of a plurality of curves based on the outer peripheral shape of the insulator. A shield conductor covering the shield conductor, the shield conductor has a metal foil facing the cover member, and the insulator has an elliptical outer peripheral shape in the cross section The minimum value of the radius of curvature of the plurality of curves is 1/20 or more and 1/4 or less of the maximum value of the radius of curvature of the plurality of curves, and the minor axis of the cross section is 0. 37 times or more 0.63 times or more To provide a differential signal transmission cable is.
上記の差動信号伝送用ケーブルは、被覆部材が、編組であることが好ましい。 In the above differential signal transmission cable, the covering member is preferably a braid.
上記の差動信号伝送用ケーブルは、絶縁体が、発泡材料を用いて形成されることが好ましい。 In the differential signal transmission cable, the insulator is preferably formed using a foam material.
上記の差動信号伝送用ケーブルは、内部よりも発泡度の小さい層を外側に有することが好ましい。 The differential signal transmission cable preferably has a layer having a lower foaming degree than the inside on the outside.
本発明に係る差動信号伝送用ケーブルによれば、スキューおよび差動同相変換量を抑制することができる。 According to the differential signal transmission cable of the present invention, it is possible to suppress the skew and the differential common-mode conversion amount.
［実施の形態の要約］
実施の形態に係る差動信号伝送用ケーブルは、離れて平行に並んだ一対の導体と、一対の導体を被覆し、短手方向の断面の外周形状が曲率半径が異なる複数の曲線を組み合わせた形状となる絶縁体と、絶縁体に巻き付けて設けられ、短手方向の断面の内周形状が絶縁体の外周形状に基づいた複数の曲線を組み合わせた形状となるシールド導体と、を備える。
[Summary of embodiment]
The cable for differential signal transmission according to the embodiment combines a pair of conductors arranged in parallel apart from each other, and a plurality of curves that cover the pair of conductors, and whose outer peripheral shape of the cross section in the short direction has a different radius of curvature. An insulator having a shape, and a shield conductor that is provided by being wound around the insulator and has a shape in which an inner peripheral shape of a cross section in a short direction is a combination of a plurality of curves based on the outer peripheral shape of the insulator.
（差動信号伝送用ケーブル１の構成の概要）
図１は、実施例１に係る差動信号伝送用ケーブルの斜視図である。図２（ａ）は、実施例１に係る差動信号伝送用ケーブルを短手方向で切断した断面図であり、（ｂ）は、差動信号伝送用ケーブルを短手方向で切断した断面の模式図である。図２（ｂ）に点線で示す２つの円は、説明を容易にするために図示したものであり、差動信号伝送用ケーブル１と同程度の短手方向の断面形状を有するケーブルを作成する際、用いられる絶縁電線の断面形状を示している。以下では、特に断らない限り、断面は、短手方向で切断した断面を示すものとする。
(Outline of the configuration of the differential signal transmission cable 1)
FIG. 1 is a perspective view of a differential signal transmission cable according to the first embodiment. 2A is a cross-sectional view of the differential signal transmission cable according to the first embodiment cut in the short direction, and FIG. 2B is a cross-sectional view of the differential signal transmission cable cut in the short direction. It is a schematic diagram. Two circles indicated by dotted lines in FIG. 2B are illustrated for ease of explanation, and a cable having a cross-sectional shape in the short direction similar to that of the differential signal transmission cable 1 is created. The cross-sectional shape of the insulated wire used is shown. Hereinafter, unless otherwise specified, the cross section indicates a cross section cut in the short direction.
この差動信号伝送用ケーブル１は、一例として、１０Ｇｂｐｓ以上の差動信号を用いたサーバ、ルータおよびストレージ等の電子機器間または電子機器内の差動信号伝送用のケーブルである。 The differential signal transmission cable 1 is, for example, a differential signal transmission cable between or in electronic devices such as servers, routers, and storages using differential signals of 10 Gbps or more.
この差動信号伝送とは、一対の導線において、位相が１８０°異なる信号をそれぞれの導線に伝送し、受信装置側において、この位相が異なる２つの信号の差分を取り出すものである。この一対の導線に流れる電流は、互いに逆方向に流れているため、この電流が流れる伝送経路である導線から放射される電磁波が小さくなる。また、差動信号伝送は、外部から受けたノイズが２つの導線に等しく重畳することから、差分を取ることにより、ノイズを除去することが可能となる。 In this differential signal transmission, signals having a phase difference of 180 ° are transmitted to the respective conductors in a pair of conductors, and the difference between the two signals having different phases is extracted on the receiving device side. Since the currents flowing through the pair of conductors flow in opposite directions, the electromagnetic waves radiated from the conductor that is the transmission path through which the current flows are reduced. Further, in differential signal transmission, noise received from the outside is equally superimposed on the two conductors, and therefore noise can be removed by taking the difference.
本実施例に係る差動信号伝送用ケーブル１は、例えば、図１に示すように、離れて平行に並んだ一対の導線２（導体）と、一対の導線２を被覆し、短手方向の断面の外周形状が曲率半径が異なる複数の曲線を組み合わせた形状となる絶縁体３と、絶縁体３に巻き付けて設けられ、短手方向の断面の内周形状が絶縁体３の外周形状に基づいた複数の曲線を組み合わせた形状となるシールド導体としての金属箔テープ７を備えて概略構成されている。 The differential signal transmission cable 1 according to the present embodiment, for example, as shown in FIG. 1, covers a pair of conductors 2 (conductors) arranged in parallel and apart, and a pair of conductors 2, An insulator 3 having a shape in which the outer peripheral shape of the cross section is a combination of a plurality of curves having different curvature radii, and the inner peripheral shape of the cross section in the short direction is based on the outer peripheral shape of the insulator 3. In addition, a metal foil tape 7 as a shield conductor having a shape formed by combining a plurality of curves is provided and schematically configured.
また、本実施例に係る差動信号伝送用ケーブル１は、例えば、金属箔テープ７を被覆した被覆部材としての押え巻きテープ８を備え、金属箔テープ７が、絶縁部材としてのプラスチックテープ５と、プラスチックテープ５の絶縁体３と向い合う面の反対側の面（すなわち、押え巻きテープ８と向かい合う面）に設けられた導電膜としての金属箔６と、を備えている。 Moreover, the differential signal transmission cable 1 according to the present embodiment includes, for example, a presser winding tape 8 as a covering member coated with a metal foil tape 7, and the metal foil tape 7 is connected to the plastic tape 5 as an insulating member. And a metal foil 6 as a conductive film provided on the surface opposite to the surface facing the insulator 3 of the plastic tape 5 (that is, the surface facing the presser winding tape 8).
導線２は、例えば、銅等の電気良導体の単線、または、この電気導体にメッキ等を施した単線である。また、導線２の半径ｒは、例えば、０．５１１ｍｍである。さらに、導線２と導線２の間隔Ｌは、例えば、０．９９ｍｍである。この間隔Ｌは、導線２の断面における、導線２の中心と導線２の中心との間隔を示している。なお、導線２は、例えば、屈曲特性を重視する場合、複数の導線を撚って形成する撚線を用いても良い。 The conducting wire 2 is, for example, a single wire of a good electric conductor such as copper, or a single wire obtained by plating the electric conductor. Moreover, the radius r of the conducting wire 2 is 0.511 mm, for example. Furthermore, the space | interval L of the conducting wire 2 and the conducting wire 2 is 0.99 mm, for example. This interval L indicates the interval between the center of the conducting wire 2 and the center of the conducting wire 2 in the cross section of the conducting wire 2. For example, when the bending characteristic is important, the conducting wire 2 may be a stranded wire formed by twisting a plurality of conducting wires.
絶縁体３は、例えば、誘電率、誘電正接の小さい材料を用いて形成される。この材料は、例えば、ポリテトラフルオロエチレン（ＰＴＦＥ）、パーフロロアルコキシ（ＰＦＡ）、ポリエチレン等である。なお、絶縁体３は、誘電率、誘電正接を小さくするため、発泡材料として発泡絶縁樹脂を用いて形成されても良い。絶縁体３は、例えば、発泡絶縁樹脂を用いて形成される場合、樹脂に発泡剤を練り込み、成型時の温度によって発泡度を制御する方法、窒素等のガスを成型圧力で注入し、圧力解放時に発泡させる方法等を用いて形成される。 The insulator 3 is formed using, for example, a material having a small dielectric constant and dielectric loss tangent. This material is, for example, polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), polyethylene or the like. The insulator 3 may be formed using a foam insulating resin as a foam material in order to reduce the dielectric constant and the dielectric loss tangent. For example, when the insulator 3 is formed using a foamed insulating resin, a foaming agent is kneaded into the resin, a method of controlling the degree of foaming according to the temperature at the time of molding, a gas such as nitrogen is injected at a molding pressure, It is formed using a method of foaming at the time of release.
絶縁体３は、例えば、図２（ｂ）に示すように、断面形状が略楕円形状であり、一例として、長軸方向の幅Ｗ1が２．８ｍｍ、短軸方向の幅Ｗ2が１．５４ｍｍである。 For example, as shown in FIG. 2B, the insulator 3 has a substantially elliptical cross-sectional shape. As an example, the width W 1 in the major axis direction is 2.8 mm, and the width W 2 in the minor axis direction is 1. .54 mm.
また、絶縁体３は、例えば、図２（ｂ）に点線で示す２つの円の頂点を結んだ面と絶縁体３とで囲まれる領域３０（斜線で示す領域）を有する。この点線で示す円は、例えば、絶縁体３の断面の外周に内接する円である。領域３０は、例えば、図２（ｂ）に点線で示す２つの円を絶縁電線とする場合、この２つの絶縁電線を被覆する絶縁体には、形成されない領域を示している。この領域３０の最大の幅ｔは、一例として、０．０７ｍｍである。以下に、比較例１および比較例２を参照しながら、絶縁体３の断面形状について、さらに説明する。 The insulator 3 has, for example, a region 30 (region indicated by hatching) surrounded by the insulator 3 and a surface connecting the vertices of two circles indicated by dotted lines in FIG. The circle indicated by the dotted line is, for example, a circle inscribed on the outer periphery of the cross section of the insulator 3. For example, when the two circles indicated by dotted lines in FIG. 2B are insulated wires, the region 30 indicates a region that is not formed in the insulator covering the two insulated wires. As an example, the maximum width t of the region 30 is 0.07 mm. Hereinafter, the cross-sectional shape of the insulator 3 will be further described with reference to Comparative Example 1 and Comparative Example 2.
図３（ａ）は、比較例１に係る断面が円形状となる絶縁電線に押え巻きテープを巻き付けた場合の張力Ｔと圧力Ｐとの関係を示す模式図であり、（ｂ）は、比較例２に係る平坦部を有する絶縁電線に押え巻きテープを巻き付けた場合の張力Ｔと圧力Ｐとの関係を示す模式図である。 Fig.3 (a) is a schematic diagram which shows the relationship between the tension | tensile_strength T and the pressure P at the time of winding a press-wound tape around the insulated wire whose cross section which concerns on the comparative example 1 becomes circular shape, (b) is a comparison. It is a schematic diagram which shows the relationship between the tension | tensile_strength T and the pressure P at the time of winding a pressing tape around the insulated wire which has the flat part which concerns on Example 2. FIG.
ここで、差動信号伝送用ケーブルは、数Ｇｂｐｓの高速信号を伝送するため、スキューを低減する必要がある。このスキューとは、差動信号間の到着時間の時間差（すなわち、ペア内スキュー）を示す。 Here, since the differential signal transmission cable transmits a high-speed signal of several Gbps, it is necessary to reduce the skew. This skew indicates a time difference in arrival time between differential signals (that is, skew within a pair).
スキューは、例えば、２本の絶縁電線を用いてケーブルが形成される場合、絶縁体の僅かな誘電率差、絶縁体の僅かな外径の差、絶縁体の長手方向に添えられるドレイン線の僅かなずれ、絶縁体の外側に設けられる金属箔テープの緩みによる絶縁体と金属箔テープとの界面にできる空隙等に起因して発生する。 For example, when a cable is formed using two insulated wires, the skew is a slight difference in dielectric constant of the insulator, a slight difference in outer diameter of the insulator, and a drain wire attached in the longitudinal direction of the insulator. This occurs due to a slight deviation or a gap formed at the interface between the insulator and the metal foil tape due to the looseness of the metal foil tape provided outside the insulator.
また、差動信号伝送用ケーブルは、ＥＭＩ（Electro-Magnetic Interference）を低減する必要から、差動同相変換量を低く抑える必要がある。ケーブルの（左右）対称性が良くないと、入力した差動信号の一部が同相信号に変換されてしまう。この同相に変換されてしまう割合を差動同相変換量と言う。特に、ポート１の差動信号に対するポート２にあらわれる同相信号の割合は、Ｓパラメータとして測定することができ、「Ｓｃｄ２１」であらわされる。 Moreover, since the differential signal transmission cable needs to reduce EMI (Electro-Magnetic Interference), it is necessary to keep the differential common-mode conversion amount low. If the (right / left) symmetry of the cable is not good, a part of the input differential signal is converted into an in-phase signal. This ratio of conversion to in-phase is called differential in-phase conversion amount. In particular, the ratio of the in-phase signal appearing at port 2 to the differential signal at port 1 can be measured as an S parameter and is represented by “Scd21”.
スキューを低減する方法としては、２つの導体を１つの絶縁体で一緒に被覆することで、絶縁体の誘電率差を抑える方法が知られている。また、他の方法として、２つの絶縁電線を、シールド用の導電体で覆う前に、絶縁体のテープを巻き付けて、シールドと導体の距離を相対的に離すことで、導体間の電磁結合を強くし、スキューが発生し難いケーブルとする方法も知られている。 As a method for reducing the skew, a method is known in which two conductors are covered together with one insulator to suppress a dielectric constant difference between the insulators. As another method, before covering the two insulated wires with the conductor for shielding, the insulating tape is wound and the distance between the shield and the conductor is relatively increased, so that the electromagnetic coupling between the conductors is achieved. A method is also known in which the cable is strengthened and is less likely to cause skew.
上記のスキューを低減する方法は、絶縁体内部の誘電率差に起因するスキューには、一定の効果が確認され、絶縁体の外周形状を一定とすること、導体の位置ずれが起きないようにすることと併せることで、スキューの低減を図れる。 The above-described method for reducing the skew is confirmed to have a certain effect on the skew caused by the dielectric constant difference inside the insulator, so that the outer peripheral shape of the insulator is constant and the conductor is not displaced. In combination with this, the skew can be reduced.
しかし、絶縁体に巻き付ける金属箔テープの緩みにより生じる空隙による影響は、上記の対策を施しても僅かに残る。差動信号伝送用ケーブルは、例えば、１０Ｇｂｐｓ相当の高速信号伝送用のケーブルとして用いられる際には、この空隙による影響により、歩留まりが下がる問題がある。 However, the effect of the air gap caused by the looseness of the metal foil tape wound around the insulator remains slightly even if the above measures are taken. For example, when the differential signal transmission cable is used as a high-speed signal transmission cable corresponding to 10 Gbps, there is a problem in that the yield decreases due to the influence of the air gap.
この金属箔テープの緩みは、例えば、金属箔テープを絶縁体に巻き付ける場合、または金属箔テープを縦添えし、押え巻きテープを巻き付ける場合、のいずれの場合にも発生する。 The looseness of the metal foil tape occurs, for example, in any case where the metal foil tape is wound around an insulator or when the metal foil tape is vertically attached and the presser tape is wound.
巻き付けた金属箔テープが緩む原因は、例えば、金属箔テープが絶縁体を押す力、すなわち、金属箔テープが絶縁体に与える圧力Ｐが小さいことが挙げられる。 The cause of loosening of the wound metal foil tape is, for example, that the force with which the metal foil tape presses the insulator, that is, the pressure P applied to the insulator by the metal foil tape is small.
図３（ａ）に示すように、断面が円形状となる絶縁電線１００に金属箔テープ１０１を巻き付ける比較例１の場合、金属箔テープ１０１の張力Ｔと釣り合うように、絶縁電線１００に力が作用する。 As shown in FIG. 3A, in the case of Comparative Example 1 in which the metal foil tape 101 is wound around the insulated wire 100 having a circular cross section, the insulated wire 100 has a force so as to balance the tension T of the metal foil tape 101. Works.
この力が、絶縁電線１００の側面に加わる圧力Ｐとなるが、この圧力は、Ｐ＝Ｔ／（２ｗｒ1）（ｗ：金属箔テープの幅、ｒ1：絶縁電線の半径）で示す関係を有する。 This force becomes the pressure P applied to the side surface of the insulated wire 100, and this pressure has a relationship expressed by P = T / (2wr 1 ) (w: width of the metal foil tape, r 1 : radius of the insulated wire). Have.
一方、図３（ｂ）に示すように、断面が平坦部１０３と曲線部１０４とを組み合わせた形状となる絶縁電線１０２に金属箔テープ１０１を巻き付ける比較例２の場合、曲線部１０４には、上記のＰ＝Ｔ／（２ｗｒ1）で示すＰと同じ圧力が加わる。しかし、平坦部１０３においては、金属箔テープ１０１の張力Ｔの方向と、平坦部１０３の表面が作る面と、が平行となるので、張力Ｔに基づいて平坦部１０３に付加される圧力Ｐはゼロとなる。 On the other hand, as shown in FIG. 3B, in the case of the comparative example 2 in which the metal foil tape 101 is wound around the insulated wire 102 whose cross section is a combination of the flat portion 103 and the curved portion 104, the curved portion 104 includes: The same pressure as P indicated by P = T / (2wr 1 ) is applied. However, in the flat portion 103, the direction of the tension T of the metal foil tape 101 and the surface formed by the surface of the flat portion 103 are parallel, so the pressure P applied to the flat portion 103 based on the tension T is It becomes zero.
ここで、円形状の絶縁電線を２つ並べて形成された断面形状、および図３（ｂ）に示すような曲線部１０４と平坦部１０３とを組み合わせた断面形状のいずれにおいても、金属箔テープ１０１を巻き付けたとき、その断面に、金属箔テープ１０１が直線状になる部分が存在する。 Here, the metal foil tape 101 is either a cross-sectional shape formed by arranging two circular insulated wires side by side or a cross-sectional shape obtained by combining the curved portion 104 and the flat portion 103 as shown in FIG. When the wire is wound, there is a portion where the metal foil tape 101 is linear in the cross section.
つまり、比較例２の場合、金属箔テープ１０１を巻き付ける際に、金属箔テープ１０１の張力Ｔと、平坦部１０３の表面が作る面とが平行となるため、平坦部１０３には、力が作用しない。平坦部１０３では、金属箔テープ１０１を巻き付ける際の差動信号伝送用ケーブルのわずかな動き、金属箔テープ１０１の張力の僅かな変化等により、巻き付ける金属箔テープ１０１の緩みが生じる。その結果、スキューが発生し、また、差動同相変換量が増加する。 That is, in the case of the comparative example 2, when the metal foil tape 101 is wound, the tension T of the metal foil tape 101 and the surface formed by the surface of the flat portion 103 are parallel, so that force acts on the flat portion 103. do not do. In the flat portion 103, the metal foil tape 101 to be wound is loosened due to a slight movement of the differential signal transmission cable when the metal foil tape 101 is wound, a slight change in the tension of the metal foil tape 101, and the like. As a result, skew occurs and the differential common-mode conversion amount increases.
上記の結果により、本実施例に係る絶縁体３は、図２（ｂ）に示す斜線の部分である領域３０を、図２（ｂ）の紙面の上下に有する。従って、金属箔テープ７を巻き付けることにより生じる圧力Ｐのベクトルは、金属箔テープ７の張力Ｔの方向と、平坦部１０３の表面が作る面と、が平行となる箇所がなくなる。 Based on the above results, the insulator 3 according to the present example has regions 30 which are hatched portions shown in FIG. 2B above and below the paper surface of FIG. Therefore, the vector of the pressure P generated by winding the metal foil tape 7 eliminates a portion where the direction of the tension T of the metal foil tape 7 and the surface formed by the surface of the flat portion 103 are parallel.
金属箔テープ７のプラスチックテープ５は、例えば、ポリエチレン等の樹脂材料を用いて形成される。 The plastic tape 5 of the metal foil tape 7 is formed using a resin material such as polyethylene, for example.
金属箔テープ７の金属箔６は、例えば、プラスチックテープ５の一方の面に、銅またはアルミニウムを張り合わせて形成される。 The metal foil 6 of the metal foil tape 7 is formed, for example, by bonding copper or aluminum to one surface of the plastic tape 5.
また、金属箔テープ７は、絶縁体３の長手方向に沿って継ぎ目、または重なり合う領域を有する。本実施例に係る金属箔テープ７は、例えば、絶縁電線４の絶縁体３を覆うように、たばこ巻きされる。このたばこ巻きとは、絶縁体３の長手方向に金属箔テープ７を添え、絶縁体３の長手方向の側面から金属箔テープ７を１回で巻き付ける方法である。図１に示す継ぎ目７０は、例えば、金属箔テープ７の長手方向の一方端部と他方端部とが対向することにより、長手方向に沿って生じる。また、金属箔テープ７が、絶縁体３の短手方向の外周よりも長いとき、金属箔テープ７の一方端部と他方端部とが重なり合う領域が生じる。 The metal foil tape 7 has a seam or an overlapping region along the longitudinal direction of the insulator 3. For example, the metal foil tape 7 according to the present embodiment is cigarette-wound so as to cover the insulator 3 of the insulated wire 4. The cigarette winding is a method in which the metal foil tape 7 is attached in the longitudinal direction of the insulator 3 and the metal foil tape 7 is wound once from the side surface in the longitudinal direction of the insulator 3. The seam 70 shown in FIG. 1 is generated along the longitudinal direction when, for example, one end and the other end in the longitudinal direction of the metal foil tape 7 face each other. Moreover, when the metal foil tape 7 is longer than the outer periphery of the insulator 3 in the lateral direction, a region where one end portion and the other end portion of the metal foil tape 7 overlap is generated.
押え巻きテープ８は、例えば、樹脂材料を用いて形成される。 The presser winding tape 8 is formed using, for example, a resin material.
押え巻きテープ８は、金属箔テープ７上に継ぎ目または重なり合う部分をらせん状に有する。本実施例に係る押え巻きテープ８は、例えば、金属箔テープ７を覆うように、らせん状に巻き付けられる。押え巻きテープ８は、短手方向の一方端部と他方端部とが重なり合わないように絶縁体３に巻き付けられる。従って、図１に示す継ぎ目８０は、金属箔テープ７上にらせん状に形成される。また、押え巻きテープ８の一方端部と他方端部とが重なり合うように金属箔テープ７上に巻き付けられるとき、金属箔テープ７上に重なり合う領域がらせん状に生じる。 The presser winding tape 8 has a joint or overlapping portion on the metal foil tape 7 in a spiral shape. The presser winding tape 8 according to the present embodiment is wound in a spiral shape so as to cover the metal foil tape 7, for example. The presser winding tape 8 is wound around the insulator 3 so that one end portion and the other end portion in the short direction do not overlap each other. Accordingly, the seam 80 shown in FIG. 1 is formed in a spiral shape on the metal foil tape 7. Further, when the presser winding tape 8 is wound on the metal foil tape 7 so that one end and the other end thereof overlap each other, an overlapping region on the metal foil tape 7 is formed in a spiral shape.
以下に、本実施例に係る差動信号伝送用ケーブル１の製造方法について説明する。
（差動信号伝送用ケーブル１の製造方法）
まず、一対の導線２を絶縁体３によって被覆し、絶縁電線４を作製する。具体的には、導線２を離して平行に配置する。この一対の導線２は、一例として、０．９９ｍｍ離して平行に配置される。また、導線２の半径ｒは、一例として、０．５１１ｍｍである。次に、発泡ポリエチレンを用いて一対の導線２を被覆し、絶縁体３を形成する。この絶縁体３の形成は、発泡度を調整することにより、一例として、絶縁体３の比誘電率が１．５となるように行われる。
Below, the manufacturing method of the cable 1 for differential signal transmission which concerns on a present Example is demonstrated.
(Manufacturing method of the differential signal transmission cable 1)
First, a pair of conducting wires 2 are covered with an insulator 3 to produce an insulated wire 4. Specifically, the conducting wires 2 are separated and arranged in parallel. As an example, the pair of conductive wires 2 are arranged in parallel with a separation of 0.99 mm. Moreover, the radius r of the conducting wire 2 is 0.511 mm as an example. Next, a pair of conducting wires 2 are covered with foamed polyethylene to form an insulator 3. The insulator 3 is formed by adjusting the foaming degree so that the relative dielectric constant of the insulator 3 is 1.5 as an example.
また、絶縁体３の形状は、図２（ｂ）に示すような曲率半径が異なる複数の曲線からなる形状を有し、一例として、長軸方向の幅Ｗ1が２．８ｍｍ、短軸方向の幅Ｗ2が１．５４ｍｍとなる。ここで、領域３０の最大幅ｔは、一例として、０．０７ｍｍである。この領域３０の曲率半径は、一例として、７ｍｍである。 The shape of the insulator 3 has a shape composed of a plurality of curves having different radii of curvature as shown in FIG. 2B. As an example, the width W 1 in the major axis direction is 2.8 mm, and the minor axis direction. The width W 2 is 1.54 mm. Here, the maximum width t of the region 30 is 0.07 mm as an example. As an example, the radius of curvature of this region 30 is 7 mm.
この絶縁体３は、例えば、絶縁体３の形状に基づいた押出機の押出口金を作製し、この押出口金から一対の導線２と共に発泡ポリエチレンを押出すことにより形成される。 The insulator 3 is formed by, for example, producing an extrusion die for an extruder based on the shape of the insulation 3 and extruding foamed polyethylene together with a pair of conductors 2 from the extrusion die.
次に、絶縁電線４の長手方向に金属箔テープ７を添え、金属箔テープ７を絶縁電線４に巻き付ける。この巻き付けは、プラスチックテープ５側が絶縁体３に対向し、金属箔６側が外側に露出するように行われる。なお、金属箔６は、後工程においてハンダ付けが行われるため、外側に露出させている。 Next, the metal foil tape 7 is attached to the longitudinal direction of the insulated wire 4, and the metal foil tape 7 is wound around the insulated wire 4. This winding is performed so that the plastic tape 5 side faces the insulator 3 and the metal foil 6 side is exposed to the outside. The metal foil 6 is exposed to the outside because soldering is performed in a later process.
次に、押え巻きテープ８を金属箔テープ７にらせん状に巻き付け、所定の工程を経た後、差動信号伝送用ケーブル１を得る。
（曲率半径と金属箔テープ７の緩みの関係について）
図４は、実施例１に係る差動信号伝送用ケーブルの曲率半径と金属箔テープの緩みが発生する確率との関係を示す図である。図４は、横軸が曲率半径、縦軸が金属箔テープ７の緩み発生率である。この金属箔テープ７の緩み発生率とは、作製したケーブル全体において、あるケーブル断面において、絶縁体３と金属箔テープ７の間に空隙が発生する確率を示す。
Next, the presser winding tape 8 is wound around the metal foil tape 7 in a spiral shape, and after a predetermined process, the differential signal transmission cable 1 is obtained.
(Relationship between radius of curvature and looseness of metal foil tape 7)
FIG. 4 is a diagram illustrating a relationship between the radius of curvature of the differential signal transmission cable according to the first embodiment and the probability that the metal foil tape is loosened. In FIG. 4, the horizontal axis represents the radius of curvature, and the vertical axis represents the rate of looseness of the metal foil tape 7. The looseness occurrence rate of the metal foil tape 7 indicates a probability that a gap is generated between the insulator 3 and the metal foil tape 7 in a certain cable cross section in the entire produced cable.
金属箔テープ７の緩み発生率の測定は、以下に示す方法で実施する。まず、作製したケーブル全長から偏ることなく、ケーブルサンプルを抜き取り、ケーブルの断面を観察する。それぞれのサンプルにおいて、絶縁体３と金属箔テープ７の間に空隙が有るか無いかを確認し、サンプル全体の数に対する、空隙が有るサンプルの数の割合を緩み発生率とする。 The rate of occurrence of looseness of the metal foil tape 7 is measured by the following method. First, a cable sample is extracted without deviating from the total length of the produced cable, and the cross section of the cable is observed. In each sample, it is confirmed whether or not there is a gap between the insulator 3 and the metal foil tape 7, and the ratio of the number of samples having a gap to the total number of samples is defined as a looseness occurrence rate.
この図４に示す測定結果から、絶縁体３の領域３０の曲率半径が１４ｍｍ（長軸方向に位置する曲線の曲率半径の２０倍）以下であれば、金属箔テープ７の緩み発生率は、数％以下となり、差動信号伝送用ケーブル１の性能を維持することができる。 From the measurement results shown in FIG. 4, if the radius of curvature of the region 30 of the insulator 3 is 14 mm or less (20 times the radius of curvature of the curve located in the long axis direction), the looseness rate of the metal foil tape 7 is Thus, the performance of the differential signal transmission cable 1 can be maintained.
一方、領域３０の曲率半径が２．８ｍｍ（長軸方向に位置する曲線の曲率半径の４倍）となるとき、金属箔テープ７の緩み発生率は低くなるが、領域３０による厚みの増加が約０．２５ｍｍとなる。この増加により、差動信号伝送用ケーブル１の特性インピーダンスが大きくなる。また、曲率半径が２．８ｍｍとして作製された差動信号伝送用ケーブルは、複数の差動信号用伝送用ケーブルを寄り合わせたケーブルの外径が大きくなり、取り扱いが困難となる。よって、曲率半径の範囲は、４倍から２０倍が好ましい。
（実施例１の効果）
本実施例に係る差動信号伝送用ケーブル１によれば、スキューおよび差動同相変換量を抑制することができる。具体的には、差動信号伝送用ケーブル１の絶縁体３の断面の外周は、図２（ｂ）に示すように、曲率半径が異なる複数の曲線の組み合わせ、つまり、曲率半径が０．７ｍｍの長軸方向に位置する曲線と、曲率半径が７ｍｍの領域３０を含んで構成される。よって、差動信号伝送用ケーブル１では、絶縁電線４に押え巻きテープ８を巻き付ける際、金属箔テープ７の張力Ｔと釣り合うように、絶縁体３の表面に常に圧力Ｐが加わる。張力Ｔを一定とすると、圧力Ｐは、断面の外周の曲率半径に反比例すると考えられるので、領域３０における圧力Ｐは、長軸方向の約１／１０に低下するが、領域３０を絶縁体３に形成しない場合は、上記に示すように、直線部分において、絶縁体に圧力Ｐが加わらない。
On the other hand, when the radius of curvature of the region 30 is 2.8 mm (four times the radius of curvature of the curve positioned in the major axis direction), the looseness rate of the metal foil tape 7 is reduced, but the thickness due to the region 30 is increased. It is about 0.25 mm. Due to this increase, the characteristic impedance of the differential signal transmission cable 1 increases. In addition, the differential signal transmission cable manufactured with a curvature radius of 2.8 mm has a large outer diameter of the cable in which a plurality of differential signal transmission cables face each other, and is difficult to handle. Therefore, the radius of curvature is preferably 4 to 20 times.
(Effect of Example 1)
According to the differential signal transmission cable 1 according to the present embodiment, the skew and the differential in-phase conversion amount can be suppressed. Specifically, as shown in FIG. 2B, the outer periphery of the cross section of the insulator 3 of the differential signal transmission cable 1 is a combination of a plurality of curves having different curvature radii, that is, the curvature radius is 0.7 mm. And a region 30 having a radius of curvature of 7 mm. Therefore, in the differential signal transmission cable 1, when the holding tape 8 is wound around the insulated wire 4, the pressure P is always applied to the surface of the insulator 3 so as to balance the tension T of the metal foil tape 7. If the tension T is constant, the pressure P is considered to be inversely proportional to the radius of curvature of the outer periphery of the cross section, so the pressure P in the region 30 drops to about 1/10 in the major axis direction. When not formed, the pressure P is not applied to the insulator in the straight line portion as described above.
また、本実施例に係る絶縁体３は、領域３０が形成されるため、圧力Ｐが、常に絶縁体３に付加されるので、金属箔テープ７を絶縁体３に巻き付ける際に、絶縁電線４が移動したり、押え巻きテープ８の張力Ｔが所定の張力より弱くなったりしたとしても、押え巻きテープ８の緩みの発生を抑制することができる。従って、金属箔テープ７の緩みを抑制することができるので、絶縁体３と金属箔テープ７との界面に生じる空隙の形成を抑制することができる。よって、本実施例に係る差動信号伝送用ケーブル１は、スキューおよび差動同相変換量が増大することによる性能の低下を抑制することができる。 Moreover, since the area | region 30 is formed in the insulator 3 which concerns on a present Example, since the pressure P is always applied to the insulator 3, when winding the metal foil tape 7 around the insulator 3, the insulated wire 4 Even if the tape moves or the tension T of the presser winding tape 8 becomes weaker than a predetermined tension, the occurrence of looseness of the presser tape 8 can be suppressed. Therefore, since the looseness of the metal foil tape 7 can be suppressed, the formation of voids generated at the interface between the insulator 3 and the metal foil tape 7 can be suppressed. Therefore, the differential signal transmission cable 1 according to the present embodiment can suppress a decrease in performance due to an increase in skew and differential in-phase conversion amount.
実施例２は、絶縁体３の短手方向の断面の外周形状が楕円形状となる点において、実施例１とは異なっている。 The second embodiment is different from the first embodiment in that the outer peripheral shape of the cross section in the short direction of the insulator 3 is an elliptical shape.
図５（ａ）は、実施例２に係る差動信号伝送用ケーブルの短手方向の断面図であり、（ｂ）は、曲率半径の最大値と最小値とに関するグラフである。図５（ｂ）は、横軸がｘ軸、縦軸がｙ軸である。この楕円において、ｘ軸上に長軸が存在し、ｙ軸上に短軸が存在する。なお、以下の各実施例において、実施例１と同じ構成および機能を有する部分については、実施例１と同じ符号を付し、その説明は省略するものとする。 FIG. 5A is a cross-sectional view in the short-side direction of the differential signal transmission cable according to the second embodiment, and FIG. 5B is a graph regarding the maximum value and the minimum value of the radius of curvature. In FIG. 5B, the horizontal axis is the x axis and the vertical axis is the y axis. In this ellipse, a major axis exists on the x-axis and a minor axis exists on the y-axis. In the following embodiments, portions having the same configurations and functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.
本実施例における差動信号伝送用ケーブル１は、絶縁体３の外周形状が、焦点Ａおよび焦点Ｂを有する楕円形状となっている。他の構成については、実施例１に係る差動信号伝送用ケーブル１と同様である。 In the differential signal transmission cable 1 in the present embodiment, the outer peripheral shape of the insulator 3 is an elliptical shape having a focal point A and a focal point B. Other configurations are the same as those of the differential signal transmission cable 1 according to the first embodiment.
また、本実施例に係る差動信号伝送用ケーブル１の製造方法は、長径（＝２ａ）が３．２０ｍｍ、短径（＝２ｂ）が１．６４ｍｍとなる楕円形状を有する絶縁体３を形成する点において、実施例１と異なっている。 In addition, the manufacturing method of the differential signal transmission cable 1 according to the present embodiment forms the insulator 3 having an elliptical shape having a major axis (= 2a) of 3.20 mm and a minor axis (= 2b) of 1.64 mm. This is different from the first embodiment.
本実施例に係る差動信号伝送用ケーブル１は、押え巻きテープ８を金属箔テープ７に巻き付ける際、圧力Ｐが、常に絶縁体３に付加される。また、金属箔テープ７が絶縁体３に付加する圧力Ｐのベクトルは、図５（ｂ）に示す焦点Ａおよび焦点Ｂのいずれかに向くこととなる。 In the differential signal transmission cable 1 according to the present embodiment, the pressure P is always applied to the insulator 3 when the holding tape 8 is wound around the metal foil tape 7. Further, the vector of the pressure P applied to the insulator 3 by the metal foil tape 7 is directed to either the focal point A or the focal point B shown in FIG.
この金属箔テープ７の張力Ｔを一定としたとき、上記に示したように、圧力Ｐは絶縁体３の断面の外周の曲率半径に反比例する。そこで、図４に示すように、長径２ａ、短径２ｂの楕円を示す式を式（１）とするとき、この楕円曲線上の任意の点（ｘ、ｙ）における曲率半径は、式（２）となる。 When the tension T of the metal foil tape 7 is constant, the pressure P is inversely proportional to the radius of curvature of the outer periphery of the cross section of the insulator 3 as described above. Therefore, as shown in FIG. 4, when an equation representing an ellipse having a major axis 2a and a minor axis 2b is defined as equation (1), the radius of curvature at an arbitrary point (x, y) on the elliptic curve is expressed by equation (2). )
しかし、本実施例に係る差動信号伝送用ケーブル１は、実施例１と同様、常に絶縁体３に圧力が付加されるように金属箔テープ７を巻くことができるので、金属箔テープ７を絶縁体３に巻き付ける際に、絶縁電線４が移動したり、押え巻きテープ８の張力Ｔが所定の張力より弱くなったりしたとしても、押え巻きテープ８の緩みを発生を抑制することができる。 However, since the differential signal transmission cable 1 according to the present embodiment can wind the metal foil tape 7 so that pressure is always applied to the insulator 3 as in the first embodiment, the metal foil tape 7 Even when the insulated wire 4 moves or the tension T of the presser tape 8 becomes weaker than a predetermined tension when wound around the insulator 3, the presser tape 8 can be prevented from loosening.
その結果、金属箔テープ７の緩みを抑制することができるので、絶縁体３と金属箔テープ７との界面に生じる空隙の形成を抑制することができる。また、実施例１に比べて、曲率半径が急激に変化する箇所がないので、より隙間が生じる確率が小さくなる。従って、本実施例に係る差動信号伝送用ケーブル１は、スキューおよび差動同相変換量が増大することによる性能の低下を抑制することができる。 As a result, loosening of the metal foil tape 7 can be suppressed, so that formation of voids generated at the interface between the insulator 3 and the metal foil tape 7 can be suppressed. Further, since there is no portion where the radius of curvature changes abruptly as compared with the first embodiment, the probability that a gap is generated becomes smaller. Therefore, the differential signal transmission cable 1 according to the present embodiment can suppress a decrease in performance due to an increase in skew and differential in-phase conversion amount.
なお、曲率半径の最小と最大との比は、上記で示したとおり、（ｂ／ａ）3である。よって、曲率半径が、１／２０以上１／４以下となる範囲は、絶縁体３の断面の短径が、長径の０．３７倍以上０．６３倍以下であり、曲率半径がこの範囲に収まれば実施例１と同様、金属箔テープ７の緩みを抑制することができる。 The ratio between the minimum and maximum curvature radius is (b / a) 3 as described above. Therefore, the range in which the radius of curvature is 1/20 or more and 1/4 or less is such that the minor axis of the cross section of the insulator 3 is 0.37 to 0.63 times the major axis, and the radius of curvature is within this range. If it fits, loosening of the metal foil tape 7 can be suppressed as in the first embodiment.
実施例３は、絶縁体３の内部と外周部とで発泡度が異なる点で上記の各実施例と異なっている。 Example 3 is different from the above examples in that the degree of foaming is different between the inside and the outer periphery of the insulator 3.
図６は、実施例３に係る差動伝送用ケーブルの断面図を示す。図６において、絶縁体３の外周と点線と、で囲まれた領域は、絶縁体層３１である。 FIG. 6 is a cross-sectional view of the differential transmission cable according to the third embodiment. In FIG. 6, a region surrounded by the outer periphery of the insulator 3 and a dotted line is an insulator layer 31.
本実施例における差動信号伝送用ケーブル１は、絶縁体３の内部と外周部とで発泡度が異なっている。他の構成については、実施例１に係る差動信号伝送用ケーブル１と同様である。この発泡度は、一例として、内部は５０％であり、絶縁体層３１は数％である。 The differential signal transmission cable 1 in the present embodiment has different degrees of foaming inside and outside the insulator 3. Other configurations are the same as those of the differential signal transmission cable 1 according to the first embodiment. As an example, the foaming degree is 50% inside, and the insulator layer 31 is several percent.
絶縁体３の絶縁体層３１は、絶縁体３の内部よりも発泡度が小さくなっている。つまり、絶縁体３は、絶縁体層３１が形成されるため、内部よりも外周部が硬くなっている。 The insulating layer 31 of the insulator 3 has a lower foaming degree than the inside of the insulator 3. That is, since the insulator 3 is formed on the insulator 3, the outer peripheral portion is harder than the inside.
また、本実施例に係る差動信号伝送用ケーブル１の製造方法は、実施例１および実施例２と同様に、押出機を用いて、一対の導線２を被覆するが、その際に絶縁体３の最外周に発泡度の小さい絶縁体層３１を再被覆するように押し出す工程を含む。他の製造方法は、実施例１および実施例２と同様である。 Moreover, the manufacturing method of the differential signal transmission cable 1 according to the present embodiment covers the pair of conductors 2 using an extruder as in the first and second embodiments. 3 includes a step of extruding the outermost outer periphery 3 so as to recoat the insulating layer 31 having a small foaming degree. Other manufacturing methods are the same as those in the first and second embodiments.
本実施例に係る差動信号伝送用ケーブル１によると、実施例１および実施例２の差動信号伝送用ケーブルと比べて、外周部に絶縁体層３１が形成されているため、絶縁体３の形状が安定するので、より押え巻きテープ８から受ける圧力Ｐが安定して絶縁体３に作用する。その結果、金属箔テープ７の緩みを抑制することができるので、絶縁体３と金属箔テープ７との界面に生じる空隙の形成を抑制することができる。従って、本実施例に係る差動信号伝送用ケーブル１は、スキューおよび差動同相変換量が増大することによる性能の低下を抑制することができる。
（変形例）
図７は、変形例に係る差動信号伝送用ケーブルの斜視図である。変形例に係る差動信号伝送用ケーブル１は、金属箔テープ７が、絶縁体３上に継ぎ目８０をらせん状に有し、金属箔テープ７を被覆する被覆部材が、編組９である。この金属箔テープ７は、プラスチックテープ５の一方の面に銅からなる金属箔６を張り合わせたものであり、編組９は、素線径が０．０８ｍｍの銅素線を６４本用いたものである。
According to the differential signal transmission cable 1 according to the present embodiment, the insulator layer 31 is formed on the outer peripheral portion as compared with the differential signal transmission cables of the first and second embodiments. Therefore, the pressure P received from the presser winding tape 8 acts on the insulator 3 more stably. As a result, loosening of the metal foil tape 7 can be suppressed, so that formation of voids generated at the interface between the insulator 3 and the metal foil tape 7 can be suppressed. Therefore, the differential signal transmission cable 1 according to the present embodiment can suppress a decrease in performance due to an increase in skew and differential in-phase conversion amount.
(Modification)
FIG. 7 is a perspective view of a differential signal transmission cable according to a modification. In the differential signal transmission cable 1 according to the modification, the metal foil tape 7 has a joint 80 spirally on the insulator 3, and the covering member that covers the metal foil tape 7 is the braid 9. This metal foil tape 7 is obtained by bonding a metal foil 6 made of copper to one surface of a plastic tape 5, and the braid 9 is made of 64 copper strands having a strand diameter of 0.08 mm. is there.
本変形例に係る差動信号伝送用ケーブル１は、絶縁体３が実施例１〜実施例３のいずれかに記載の形状を有しているので、金属箔テープ７をらせん状に巻き付けたとしても、緩みの発生を抑えることができる。その結果、絶縁体３と金属箔テープ７との界面に生じる空隙の形成を抑制することができる。従って、本変形例に係る差動信号伝送用ケーブル１は、スキューおよび差動同相変換量が増大することによる性能の低下を抑制することができる。 In the differential signal transmission cable 1 according to this modification, since the insulator 3 has the shape described in any one of the first to third embodiments, the metal foil tape 7 is wound in a spiral shape. Also, the occurrence of looseness can be suppressed. As a result, the formation of voids generated at the interface between the insulator 3 and the metal foil tape 7 can be suppressed. Therefore, the differential signal transmission cable 1 according to the present modification can suppress a decrease in performance due to an increase in skew and differential in-phase conversion amount.
なお、金属箔テープ７は、絶縁体３上に重なり合う領域をらせん状に有していても良い。 Note that the metal foil tape 7 may have a spiral region overlapping the insulator 3.
以上、本発明の実施の形態、実施例及びその変形例を説明したが、上記に記載した実施の形態、実施例及び変形例は特許請求の範囲に係る発明を限定するものではない。また、実施の形態、実施例及び変形例の中で説明した特徴の組合せの全てが発明の課題を解決するための手段に必須であるとは限らない点に留意すべきである。 As mentioned above, although embodiment, Example, and its modification of this invention were described, embodiment, Example, and modification which were described above do not limit the invention which concerns on a claim. In addition, it should be noted that not all the combinations of features described in the embodiments, examples, and modifications are essential to the means for solving the problems of the invention.
１…差動信号伝送用ケーブル
２…導線
３…絶縁体
４…絶縁電線
５…プラスチックテープ
６…金属箔
７…金属箔テープ
８…押え巻きテープ
９…編組
３０…領域
３１…絶縁体層
７０…継ぎ目
８０…継ぎ目
１００…絶縁電線
１０１…金属箔テープ
１０２…絶縁電線
１０３…平坦部
１０４…曲線部
DESCRIPTION OF SYMBOLS 1 ... Cable for differential signal transmission 2 ... Conductor 3 ... Insulator 4 ... Insulated electric wire 5 ... Plastic tape 6 ... Metal foil 7 ... Metal foil tape 8 ... Pressing tape 9 ... Braid 30 ... Area 31 ... Insulator layer 70 ... Seam 80 ... Seam 100 ... Insulated wire 101 ... Metal foil tape 102 ... Insulated wire 103 ... Flat part 104 ... Curve part
Claims (8)
前記一対の導体を被覆し、短手方向の断面の外周形状が曲率半径が異なる複数の曲線を組み合わせた形状となる絶縁体と、
前記絶縁体上に継ぎ目または重なり合う領域をらせん状に有するように巻き付けて設けられ、短手方向の断面の内周形状が前記絶縁体の前記外周形状に基づいた前記複数の曲線を組み合わせた形状となるシールド導体と、
前記シールド導体を被覆した被覆部材と、
を備え、前記シールド導体は、前記被覆部材と向い合う金属箔を有し、
前記絶縁体は、前記断面の前記外周形状が楕円形状を有し、前記複数の曲線の曲率半径の最小値が、前記複数の曲線の曲率半径の最大値の１／２０以上１／４以下であると共に、前記断面の短径が、長径の０．３７倍以上０．６３倍以下である
差動信号伝送用ケーブル。 A pair of conductors spaced apart in parallel;
An insulator that covers the pair of conductors and has a shape that combines a plurality of curves in which the outer peripheral shape of the cross section in the short direction has a different curvature radius;
A shape in which the inner peripheral shape of the cross section in the short direction is combined with the plurality of curves based on the outer peripheral shape of the insulator is provided so as to spirally have a seam or an overlapping region on the insulator. A shield conductor,
A covering member covering the shield conductor;
The shield conductor has a metal foil facing the covering member,
In the insulator, the outer peripheral shape of the cross section has an elliptical shape, and the minimum value of the curvature radius of the plurality of curves is 1/20 or more and 1/4 or less of the maximum value of the curvature radius of the plurality of curves. In addition, a differential signal transmission cable in which the minor axis of the cross section is not less than 0.37 times and not more than 0.63 times the major axis.
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