JP2011192526A - Movable cable for signal transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a movable cable for signal transmission with superior flexibility, while preventing noises. <P>SOLUTION: The movable cable for signal transmission has a shield layer 4 for covering a signal line flux 3 for signal transmission which is composed of an inner shield layer 4a consisting of a shield tape wound around in spiral shape with the adjoining turns overlapped partially and an outer shield layer 4b covering the inner shield layer. The outer shield layer 4b is composed of mixed braided wires in which a plurality of conductive metal wires and a plurality of insulating threads are knit in a braid shape, and each of metal wires and insulating threads are formed in a tube body extending in spiral shape with the different winding directions respectively, and the winding direction of each metal wire is constructed to be different from the winding direction of the shield tape constituting the inner shield layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a movable cable for signal transmission which is provided so as to connect between devices in which relative displacement occurs between them and is mainly used for transmitting signals.

  There is relative displacement between the robot's moving parts, such as the cable that connects the robot's moving parts, the cable that connects the robot and its controller, or the jumper cable that connects the cars at the connecting part of the train. Cables that are provided to connect the resulting devices and exchange signals between the devices must be able to move freely following the displacement of the device (have mobility) . Furthermore, since this type of cable is used to transmit a signal used for control, it must have a structure that can prevent noise from being mixed into the signal transmitted through the signal line. Since it is always deformed with the displacement of the part, it must have excellent durability.

  As a movable cable having a function of preventing noise from being mixed, as shown in Patent Document 1, a signal line bundle formed by bundling a plurality of signal wires (insulating wire cores) formed by insulating coating a core wire is electrically conductive. A cable having a structure in which a shielding material made of a material is covered and an outer periphery of the shielding material is covered with a sheath in which a conductive layer is laminated has been proposed.

  Further, Patent Document 2 discloses that a plurality of shielded conductors arranged in parallel on the outer periphery of the suppression insulating layer are formed by winding an insulating resin tape around the outer periphery of a signal line bundle formed by twisting a plurality of signal lines. A cable having a structure in which a shield layer is formed by winding a cable in a spiral shape is disclosed.

  Further, Patent Document 3 discloses a coaxial cable in which a shield layer is formed by a shield tape wound around an outer periphery of an insulating coating covering a core wire and a metal braided wire covering the outer periphery of the shield tape.

  Further, Patent Document 4 discloses a coaxial cable in which another shield tape is spirally wound around the outer periphery of a shield tape wound in a spiral shape around the outer periphery of an insulation coating covering the core wire to form a double shield layer. Is disclosed.

JP-A-6-176626 JP 2007-188738 A JP 2009-146704 A JP 2009-272209 A

  As shown in Patent Document 1, when a structure in which a plurality of signal lines are covered with a shielding material made of a conductive material and the outer periphery of the shielding material is covered with a sheath in which a conductive layer is laminated is employed, Since the flexibility of the sheath is impaired by the lamination of the conductive layers, it is difficult to give the cable great flexibility. Further, when the cable is repeatedly deformed, the conductive layer laminated on the sheath may be damaged.

  As shown in Patent Document 2, when a shield layer is formed by spirally winding a large number of shield conductors juxtaposed on the outer periphery of a signal wire bundle, the shield wires are adjacent to each other in comparison with the electrical resistance of each shield conductor. Since the contact resistance between the shield conductors is large, the ground current flowing through the shield layer flows spirally around the signal line bundle through each shield conductor. In this case, as shown in FIG. 4, the ground current I flowing spirally around the signal line has a component in the axial direction (longitudinal direction) of the cable (hereinafter referred to as an axial component) Ia and the axial direction of the cable. It has a component perpendicular to the direction (radial direction) (hereinafter referred to as a radial component) Ir. Among these components, the axial direction component Ia is usually a signal transmitted through the signal wire bundle inside the shield, and other signal wire bundles (insulated wires and twisted insulated wires, Although it does not become a noise source for shielded insulated wires), the radial component Ir is a signal transmitted through the signal line in the shield, and other signals arranged near or adjacent to the shield. There is a high possibility of being a noise source for the signal bundle. As described above, when the conductor constituting the shield is wound around the signal wire bundle in a spiral shape, when the ground current flows through the shield, the signal transmitted through the signal wire bundle disposed inside the shield. In addition, since a current component that may be a noise source is generated for a signal transmitted through another signal line bundle arranged in close proximity, the shield structure shown in Patent Document 2 uses a cable that is resistant to noise. Difficult to get.

  As shown in Patent Document 3, the shield tape flows even when the shield layer is formed by the shield tape wound around the outer periphery of the insulation coating covering the core wire and the metal braided wire covering the outer periphery of the shield tape. Since the ground current flows in a spiral shape, the ground current has an axial component and a radial component, which may be a noise source for a signal in which the radial current component is transmitted.

  As shown in Patent Document 4, when the signal transmission cable has a structure in which the shield layer is formed by winding the shield tape twice, the winding direction of the shield tape to be wound twice is set. If different, the radial component of the ground current flowing through the inner shield layer and the radial component of the ground current flowing through the outer shield layer can be offset in substantially opposite directions, so a signal that is resistant to noise. It is possible to obtain a transmission cable. However, if the shield tape is wound around a plurality of signal wires in a double manner, the flexibility of the cable is lost, and it is difficult to obtain a signal transmission cable with excellent mobility. Further, in the structure shown in Patent Document 4, since a large friction is generated between the inner shield tape and the outer shield tape when the cable is deformed, there is a possibility that the shield layer may be damaged after a relatively short period of use. Yes, I am worried about durability. Therefore, Patent Document 4 discloses a signal transmission movable cable used for an application that requires particularly excellent mobility and durability such as a signal transmission cable for a robot and a jumper cable for a vehicle. It is not preferable to adopt a shield structure as shown in FIG.

  As described above, according to the prior art, a movable cable that satisfies the two conditions of eliminating the possibility of noise being mixed into the signal transmitted through the signal line and giving the entire cable great mobility is obtained. It was difficult.

  An object of the present invention is to provide a movable cable for signal transmission which is resistant to noise and can have a large mobility.

  The present invention relates to a signal transmission movable cable having a structure in which a signal wire bundle composed of a plurality of signal wires (insulating wire cores) formed by insulating coating a core wire is covered with a shield layer. The shield layer includes an inner shield layer made of a shield tape wound in a spiral shape with a part of adjacent turns being wrapped, and an outer shield layer covering the inner shield layer.

  In the outer shield layer, a plurality of conductive metal wires and a plurality of insulating yarns are knitted in a braid shape, and each metal wire and the insulating yarns extend in a spiral shape with different winding directions. It consists of the mixed braided wire which has the structure which has comprised the cylindrical body, Comprising: It is comprised so that the winding direction of each metal wire may differ from the winding direction of the shield tape which comprises an inner side shield layer.

  As described above, a shield tape in which the outer shield layer covering the inner shield layer wound in a spiral shape is configured by a mixed-strike braid, and the winding direction of the metal wire constituting the mixed-strike braid configures the inner shield layer If the configuration is different from the winding direction of the cable, the radial component of the cable having the ground current flowing through the inner shield layer and the radial component of the cable having the ground current flowing through the metal wire constituting the outer shield layer are mutually connected. Since it can be canceled substantially in the reverse direction, a signal transmission cable that is resistant to noise can be obtained.

  In addition, since the braided wire can have a greater flexibility than the shield tape wound in a spiral shape, as described above, when the outer shield layer is configured by a mixed braided wire, the inner shield layer and the outer Compared with the case where both of the shield layers are made of shield tape, it is possible to have much greater mobility. In addition, the braided wire can not only have high strength, but also easily deforms in all directions without causing large frictional resistance with the inner shield layer as the cable deforms. An unreasonable force can be prevented from being applied to the inner shield layer, and the damage of the shield layer caused by repeated deformation of the movable cable can be suppressed, thereby extending the life of the cable.

  Therefore, according to the present invention, it is possible to obtain a movable cable for signal transmission that is resistant to noise and excellent in mobility and durability.

  The shield tape is a tape having a conductive portion continuous along the longitudinal direction. This shield tape preferably has a structure in which a copper foil or an aluminum foil is bonded to one or both sides of a tape made of one plastic selected from polyester, polyethylene and polypropylene.

  Further, the metal wire constituting the mixed braided wire is preferably selected from copper wire, tin-plated copper wire, silver-plated copper wire, and stainless steel wire. The insulating yarn constituting the wire is preferably made of an insulating material selected from cotton, suf, polyester, nylon, and Kepla (trade name).

  By selecting the material as described above, a mixed braided wire having high flexibility and high mechanical strength can be obtained.

  In the cable according to the present invention, the thickness of the conductor portion of the shield tape and the wire diameter of the metal wire constituting the mixed braid so that the electric resistance of the inner shield layer is substantially equal to the electric resistance of the outer shield layer. It is preferable that the number is set.

  If the inner shield layer and the outer shield layer are configured as described above, the ground currents flowing through the inner shield layer and the outer shield layer can be made substantially equal, so that the effect of canceling the radial component of the ground current is enhanced. Thus, the noise reduction effect by the shield layer can be enhanced.

  According to the present invention, the outer shield layer covering the inner shield layer wound in a spiral shape is constituted by a cylindrical mixed-weaving braided wire made of insulating yarn and metal wire, and the metal constituting the mixed-bending braid By making the winding direction of the wire different from the winding direction of the shield tape constituting the inner shield layer, the radial component of the cable having the earth current flowing through the inner shield layer and the metal wire constituting the outer shield layer Since the radial component of the cable of the ground current flowing through the cable can be almost offset in the opposite direction, the signal transmitted through the signal line bundle arranged inside the shield and the other arranged closely A signal transmission cable that is resistant to noise can be obtained by reducing the current component that may be a noise source for the signal transmitted through the signal bundle.

  In the present invention, since the outer shield layer is composed of a mixed braided wire having excellent flexibility, a double shield structure resistant to noise can be realized without impairing the flexibility of the cable. In addition, the braided wire can not only have great strength, but it can be easily deformed in any direction without causing great frictional resistance with the inner shield layer as the cable is deformed. As a result, an excessive force is applied to the inner shield layer and the outer shield layer to prevent the shield layer from being damaged at an early stage, thereby extending the life of the cable.

  Therefore, according to the present invention, it is possible to obtain a movable cable for signal transmission which is resistant to noise and excellent in mobility and durability.

It is sectional drawing which showed the structure of one Embodiment of this invention typically. In this embodiment, it is the front view which showed the structure of the inner side shield layer which covers a signal wire bundle. In this embodiment, it is the front view which showed the structure of the outer side shield layer which covers a signal wire bundle. It is a vector diagram of the electric current which flows through a shield layer in the conventional movable cable. It is a vector diagram of the electric current which flows through a shield layer in the movable cable concerning the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view of a movable cable 1 according to this embodiment. In FIG. In the example shown in the figure, four signal lines 2 are star-quad twisted to form a signal line bundle 3. A shield layer 4 covers the signal line bundle 3, and an insulating sheath 5 covers the shield layer 4. Is provided. The signal line twisting structure includes pair twisting, quad twisting, and the like. In the present invention, the signal line twisting structure is arbitrary. The number of signal lines constituting the signal line bundle covered with the shield layer may be two or more.

  In the present invention, the shield layer 4 includes an inner shield layer 4a and an outer shield layer 4b. As shown in FIG. 2, the inner shield layer 4a is composed of a shield tape 4a1 wound in a spiral shape with a part of adjacent turns wrapped. As the shield tape 4a1, a tape having a structure in which a conductive foil is bonded to one or both sides of a tape made of flexible insulating plastic such as polyester, polyethylene, or polypropylene is used. It is preferable to use a copper foil or an aluminum foil as the conductive foil. The width w of the shield tape 4a1 is set to a size necessary for winding around the outer periphery of the signal wire bundle 3.

  As shown in FIG. 3, the outer shield layer 4b is formed by braiding a plurality of conductive metal wires 4b1 illustrated in black and a plurality of insulating threads 4b2 illustrated in white. It is composed of a mixed braided wire that is knitted into a tubular body.

  In the mixed braided wire shown in FIG. 3, a plurality of metal wires 4b1 and a plurality of insulating yarns 4b2 juxtaposed along a direction inclined to a different side with respect to the longitudinal direction are appropriately positioned vertically. While crossing differently, it has a structure in which each winding direction is different and extends in a spiral shape to form a cylindrical body. All the metal wires 4b1 constituting the mixed braided wire extend spirally along the same winding direction, and all the insulating yarns 4b2 extend spirally along a winding direction different from the metal wires. . In the present invention, the mixed braided wire constituting the outer shield layer is knitted so that the winding direction of each metal wire 4b1 extending spirally is different from the winding direction of the shield tape 4a1 constituting the inner shield layer 4a. It has been. In this embodiment, the shield tape 4a1 constituting the inner shield layer 4a is wound so as to extend spirally while rotating clockwise from the lower side to the upper side in FIG. In FIG. 3, the line 4b1 is provided so as to extend in a spiral shape while rotating counterclockwise from below to above.

  The outer shield layer 4b passes the cable on which the inner shield layer 4a is formed through a braiding machine including a bobbin wound with a metal wire and a bobbin wound with an insulating yarn, on the outer periphery of the inner shield layer. It is formed by closely knitting a mixed braided wire.

  As the metal wire 4b1 constituting the mixed braided wire, it is preferable to use a copper wire, a tin-plated copper wire, a silver-plated copper wire, or a stainless steel wire. As the insulating yarn constituting the mixed braided wire, it is preferable to use one made of at least one fiber material selected from cotton, suf, polyester, nylon, and Kepla (trade name).

  In configuring the shield layer 4, in order to make the ground currents diverted to the inner shield layer 4a and the outer shield layer 4b substantially equal to each other, the electric resistance of the inner shield layer 4a made of shield tape is changed from the mixed braided wire. Of the conductor portion of the shield tape 4a so that the electrical resistance of the outer shield layer 4b is approximately equal to the electrical resistance of the outer shield layer 4b (preferably the difference between the two electrical resistances is 10% or less of the electrical resistance of the inner shield layer). It is preferable to set the thickness and the diameter and the number of metal wires constituting the mixed braid.

  Also, since the axial component of the cable having the ground current flowing through the inner shield layer and the axial component of the cable having the ground current flowing through the outer shield layer are oriented in approximately opposite directions, the shield tape is in the axial direction of the cable (longitudinal direction). The inner shield layer and the outer shield layer are configured so that the absolute value of the inclination angle formed with respect to) and the inclination angle formed by the metal wire constituting the mixed braided wire with respect to the axial direction of the cable are substantially equal. Is preferred.

  In a signal cable in which a shield layer is formed so as to cover the signal line bundle, a ground current flows through the shield layer due to non-uniform positional relationship between the signal lines and electromotive force generated due to external noise or the like. When the shield layer is made of a shield tape wound in a spiral shape, even if the conductive portions of the tape are in electrical contact with each other at the overlapped portion, the contact resistance of the shield tape itself Since it is considerably larger than the electric resistance, the ground current flowing through the shield layer flows spirally through the inside of the shield tape.

  When the shield layer is composed of a shield tape extending spirally around the signal wire bundle, the ground current I flowing in a spiral manner around the signal wire bundle is directed in the axial direction of the cable as shown in FIG. It has an axial component Ia and a radial component Ir oriented in the radial direction of the cable. Among these components, the axial direction component Ia does not normally serve as a noise source for signals transmitted through signal bundles inside the shield layer and signals transmitted through other signal bundles arranged close to each other. The radial component Ir has a high possibility of becoming a noise source for a signal transmitted through a signal line bundle inside the shield layer and a signal transmitted through another signal line bundle arranged close to the shield layer. Therefore, if the shield layer is constituted only by the shield tape wound in a spiral shape, noise may enter the signal line, which is not preferable.

  Especially when a relative displacement always occurs between devices connected by a cable, such as a robot cable or a jumper cable that connects vehicles at the connecting part of the vehicle, the signal wire bundle inside the cable is always moved. Therefore, the positional relationship between the pair of signal lines constituting the round-trip line always changes, and a portion that becomes a weak point against noise intrusion tends to occur. In the unlikely event that noise enters the signal line, the device may malfunction, so it is necessary to avoid as much as possible that the earth current flowing through the shield layer has a radial component that becomes a noise source.

  In particular, since signal transmission cables for robots and vehicles also recently transmit LAN signals with a communication speed of 100 Mbps or higher, the characteristics of the near end crosstalk (NEXT) are the LAN standard (JIS X 5150). Must have passed. Therefore, it is extremely important to reduce the radial component Ir of the earth current (component facing the radial direction of the cable) Ir, which is likely to be a noise source.

  In a movable cable for signal transmission, it is conceivable that the shield layer that covers the signal line bundle is composed only of the metal braided wire, but if the shield layer is composed of only the metal braided wire, high-frequency noise with a short wavelength is internally transmitted through the braided wire mesh. Therefore, if the signal flowing through the signal line is a high-frequency signal having a short wavelength such as a LAN signal or an image signal, the signal may be affected by noise.

  Like the present invention, the shield layer 4 is constituted by an inner shield layer 4a made of a shield tape wound in a spiral shape in a partially wrapped state and an outer shield layer 4b made of a mixed braided wire, When the winding direction of the metal wire constituting the mixed braided wire is opposite to the winding direction of the shield tape, the earth current I flowing through the inner shield layer 4a is, for example, as shown in the vector diagram on the right side in FIG. Thus, it has the axial direction component Ia which faced the axial direction of the cable, and the radial direction component Ir which faced the radial direction of the cable. The ground current I ′ flowing through the metal wire 4b1 constituting the outer shield layer 4b is also the axial component Ia ′ facing the cable axial direction and the cable radial direction as shown in the vector diagram on the left side in FIG. The radial component Ir ′ of the earth current flowing through the metal wire 4b1 constituting the outer shield layer 4b is equal to the radial component Ir of the earth current flowing through the inner shield layer. Is facing the opposite direction. As described above, when configured as in the present invention, the radial component Ir of the earth current I flowing through the inner shield layer and the radial component Ir ′ of the earth current I ′ flowing through the outer shield layer are opposite to each other. Since the directions can be almost canceled out, a signal transmission cable resistant to noise can be obtained.

  Further, since the braided wire has great flexibility, as described above, when the outer shield layer 4b is configured by the mixed braided wire, the inner shield layer and the outer shield layer are both configured by shield tape as compared with the case where the outer shield layer 4b is configured by the shield tape. Can have excellent mobility.

  Furthermore, the braided wire can not only have a high strength, but also can easily be deformed in all directions without causing a large frictional resistance between the outer shield layer 4b and the inner shield layer 4a as the cable is deformed. Therefore, it is possible to prevent an excessive force from being applied to the inner shield layer 4a when the cable is deformed. Therefore, the shield layer can be prevented from being damaged in a short period of time, and the cable life can be extended.

  In the above embodiment, the signal line bundle 3 is constituted by four signal lines. However, in the present invention, the number of signal lines constituting the signal line bundle is arbitrary.

  In the above embodiment, the present invention is applied to a movable cable having a structure in which one signal line bundle is covered with a shield. However, a unit cable or at least one signal line bundle having a structure in which at least one signal line bundle is covered with an insulating coating. When a unit cable having a structure in which a unit cable is covered with a shield layer and an insulation coating is assembled to cover a unit cable assembly composed of multiple unit cables within a range that does not impair mobility. The present invention can also be applied. In this case, at least the shield layer provided in a lump is constituted by an inner shield layer made of a shield tape wound in a spiral shape and an outer shield layer made of a mixed braided wire as in the above embodiment.

  As described above, when a structure in which an assembly of a plurality of unit cables is collectively covered with a shield layer is adopted, each unit cable accommodated inside may or may not have a shield. When providing a shield for each unit cable, the shield of each unit cable may be composed only of a metal braided wire, or may be composed of an inner shield layer made of shield tape and an outer shield layer made of mixed braid. Good. In order to prevent a current component that becomes a noise source from being generated in a ground current with respect to a signal to be transmitted, it is desirable to avoid a shield provided for each unit cable from being composed only of a shield tape wound in a spiral shape. .

  The movable cable for signal transmission according to the present invention is a cable mainly used for transmitting signals, but if necessary, other insulated wire cores such as an insulated wire core for DC power supply are mixed. I will not prevent it.

  The present invention relates to a movable cable that connects a robot and its controller, a movable cable that is provided at a joint part of the robot, a movable cable that connects between devices that cause relative displacement in other industrial machines, and a vehicle between trains. Used for applications that require resistance to noise, such as jumper cables provided to connect vehicles between connecting parts, and that require excellent mobility and durability. Can be widely applied to movable cables.

1 Signal transmission movable cable 2 Signal line (insulated core)
Reference Signs List 3 Signal line bundle 4 Shield layer 4a Inner shield layer made of shield tape 4b Outer shield layer made of mixed braided wire 5 Insulation sheath

Claims (4)

In a signal transmission movable cable having a structure in which a signal wire bundle composed of a plurality of signal wires formed by insulating coating a core wire is covered with a shield layer,
The shield layer is composed of an inner shield layer made of a shield tape wound in a spiral shape with a part of an adjacent turn being wrapped, and an outer shield layer covering the inner shield layer,
The outer shield layer has a plurality of conductive metal wires and a plurality of insulating yarns knitted in a braid shape, and each metal wire and the insulating yarns extend spirally with different winding directions. It is composed of a mixed braided wire having a cylindrical shape, and is configured such that the winding direction of each metal wire constituting the mixed braided wire is different from the winding direction of the shield tape constituting the inner shield layer. That
A movable cable for signal transmission characterized by The shield tape has a structure in which a copper foil or an aluminum foil is bonded to one or both sides of a tape made of one plastic selected from polyester, polyethylene and polypropylene;
The movable cable for signal transmission according to claim 1. The metal wire constituting the mixed braided wire is selected from the group consisting of copper wire, tin-plated copper wire, silver-plated copper wire and stainless steel wire,
The insulating yarn constituting the mixed braided wire is made of at least one fiber material selected from the fiber material group consisting of cotton, sufu, polyester, nylon and kepla;
The movable cable for signal transmission according to claim 1 or 2.   The thickness of the conductor portion of the shield tape and the wire diameter and number of metal wires constituting the mixed braided wire are set so that the electric resistance of the inner shield layer is substantially equal to the electric resistance of the outer shield layer. The signal transmission movable cable according to claim 1, wherein the signal transmission movable cable is provided.

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