JP4829764B2 - Low noise cable - Google Patents

Description

The present invention relates to a low noise cable for signal transmission in which a plurality of insulating core wires are twisted and a sheath is formed on an outer peripheral surface thereof with an electric shielding layer interposed therebetween.

When the detection signal is derived from an acceleration sensor that detects vibrations, or when various signals are derived from where the vibrations are occurring, various vibrations occur in the derived cable, and noise enters the signal due to the vibrations. Reliability is reduced.
On the other hand, the signal transmission cable is twisted through a plurality of insulated core wires, and a sheath is formed on the outer peripheral surface thereof. When this cable vibrates, an electrostatic noise voltage is generated due to friction between the insulation coatings of the respective insulation core wires, and the electrostatic noise voltage enters the electric conductor of the insulation core wire and becomes noise.
For this reason, the thing of the low noise (noise resistance) which does not produce such noise is requested | required.

As the low noise cable, as shown in FIG. 6, a plurality of insulating core wires 1 are twisted together via an interposition 2, and a semiconductive tape 3 is pressed and wound around the outer peripheral surface, and further, the outer peripheral surface is electrically shielded. There is one in which a sheath 5 is formed with a layer 4 interposed.
In the low noise cable P2, the movement between the insulation cores 1 at the time of vibration is restricted by the presence of the interposition 2, and the electrostatic noise voltage due to the friction between the insulation coatings of the insulation cores 1 due to the vibration is controlled. Suppresses the occurrence.

  As various technologies become more advanced, signal transmission cables are required to be able to transmit signals more accurately, and performance (low noise) higher than the low noise cable P2 having the above configuration is being demanded.

  This invention makes it a subject to set it as the low noise cable more than the low noise cable P2 of said structure.

In order to solve the above-mentioned problems, the present invention provides a cross-sectional fan shape for the insulation coating so as to further restrict the mutual movement between the insulation core wires, and the fan-like insulation coating for each insulation core wire is a cable. The side surface of each fan-shaped insulating coating is arranged around the center.
With such a configuration of each insulated core wire, each insulated core wire is in a solid form with no gap between each other and is difficult to move. For this reason, even if a vibration is given, it does not move mutually, and the electrostatic noise voltage by the friction between the insulation coating of each insulation core wire does not generate | occur | produce.

  The configuration of the present invention is a low noise cable in which a plurality of insulating core wires are twisted and a sheath is formed on the outer peripheral surface with an electric shielding layer interposed therebetween. It is assumed that the fan-shaped insulating coating of the insulating core wire is disposed around the center of the cable so that the side surfaces of the respective fan-shaped insulating coatings are in contact with each other and the outer peripheral surface thereof is covered with the sheath.

In this configuration, when the tape is pressed and wound on the outer peripheral surface of the plurality of twisted insulation core wires, and the sheath is formed on the outer peripheral surface with the electric shielding layer interposed, the tape is pressed and wound. As a result, a circular shape of the outer shape of the plurality of twisted insulation cores is secured, and the insulation cores are firmly pressed against each other to increase the frictional resistance between them. For this reason, the sliding between the insulation core wires is suppressed, and each insulation core wire is difficult to move, and the generation of electrostatic noise voltage due to the friction between the insulation coatings of each insulation core wire is further suppressed.
The tape is appropriately selected from conductive, semiconductive, and insulating tapes depending on the purpose and location of the cable.

In the configuration in which the tape is pressed and wound, the insulating coating of each of the insulating core wires can be deformed by pressing and winding the tape to have a cross-sectional fan shape.
In this case and other cases (including the case where the insulation coating has a fan-shaped cross section in advance), the hardness of the tape can be made higher than the hardness of the insulation coating of the insulation core.
In this way, when an external impact is applied to the cable, the impact is received by the hard tape, spreading the impact throughout the entire tape, reducing the impact per unit area, and softening the weakened impact. Since the insulation is buffered, it is difficult to transmit the impact to the conductor of the insulated core wire, and the generation of noise is suppressed.

  In addition, it is also conceivable that the outer peripheral surfaces of a plurality of twisted insulation core wires are subjected to extrusion coating as a sheath or separately from the sheath, regardless of the tape. A material harder than the insulation coating will be used. On the other hand, since the presser winding of the tape is easily bent at the boundary between the tapes of the winding layer, it is easy to bend. For this reason, when the extrusion coating and the tape have the same hardness, the latter tape press winding is more flexible as a cable than the former extrusion coating. The good flexibility is effective for low noise by dispersing the impact in the longitudinal direction of the cable. Incidentally, as with the tape, the extrusion-coated resin is appropriately selected according to the purpose of use and the location of the cable, as in the case of the tape.

In each of the above-described configurations, it is preferable that the insulation coating of each of the insulation core wires be in close contact or fusion with each other on its side surface.
If the respective insulation coatings are in close contact or fused, it is difficult for movement between the respective insulation coatings to occur, and this is considered to suppress noise generation. Moreover, if it is close_contact | adherence or melt | fusion, the insulation core wire press-contacted by the tape pressing winding can be easily separated into individual core wires in the insulation core wire connection operation. As the close contact or fusion means, various known means such as close contact with a press-wound tape and fusion by heating can be employed. For example, in the fusion, when the sheath is covered by pressing the tape around the outer peripheral surface of a plurality of twisted insulating core wires and covering the outer peripheral surface with the electrical shielding layer interposed therebetween, the insulation core is heated by the heat of the sheath extrusion coating. A part of the surface of the insulating coating material of the wire is softened to fuse the insulating coating materials together.
In addition, the volume resistivity of the insulation coating of the insulation core is desired to be as small as possible from the viewpoint of reducing the generation of static electricity due to friction caused by the movement of each insulation coating. For example, 10 ^ 11 to 10 ^ 13 Ωcm.

  FIG. 1 shows an embodiment. This embodiment is based on the specification shown in FIG. 4. Four (4C) insulating core wires 11 are twisted together and a semiconductive tape 13 is formed on the outer peripheral surface thereof. And a sheath 15 is formed with an electric shielding layer 14 interposed therebetween.

The conductor 11a of the insulation core wire 11 employs “precipitation strengthened copper alloy containing appropriate amounts of Fe, PZr, In” described in Japanese Patent Publication No. 2-46656, and the insulation coating 11b and the sheath 15 are made of vinyl chloride. (PVC): 100% by weight, plasticizer (DOP, etc.): 90% by weight, stabilizer (Pb-based): 4% by weight, filler (heavy calcium carbonate): 50% by weight, other (coloring agent, lubricant) : A little blended composition.
The semiconductive tape 13 is obtained by applying and vulcanizing semiconductive butyl rubber on both sides of a nylon cloth base cloth. The volume resistivity of the tape 13 is 5 × 10 ^ 4 Ωcm (90 ° C.). It was.
Furthermore, the hardness of the insulating coating 11b of the insulating core wire 11 is Shore D31, the hardness of the semiconductive tape 13 is Shore D54, and the hardness of the semiconductive tape 13 is higher than the hardness of the insulating coating 11b of the insulating core wire 11. .

As shown in FIG. 1, each of the insulation core wires 11 made of the insulation coating 11b having this hardness is twisted as shown in FIG. 3, and the semiconductive tape 13 is pressed and wound around the outer peripheral surface by horizontal winding. The insulation coating 11b of the insulation core wire 11 is changed from a cross-sectional circle shape to a cross-sectional fan shape, and each fan-shaped insulation coating 11b is arranged around the center of the cable so that almost the entire side surface 11b 'of each fan-shaped insulation coating 11b is in contact It was.
In FIG. 1, the insulating coatings 11 b and between the insulating coatings 11 b and the semiconductive tape 13 are described as having gaps between them. In practice, the insulating coatings 11b are fused together, and the insulating coating 11b and the semiconductive tape 13 are in pressure contact.

The semiconductive tape 13 is pressed and wound, and the sheath 15 is extruded and coated on the outer peripheral surface of the insulation coating 11b of each insulation core wire 11 in a cross-sectional fan shape with the electrical shielding layer 14 interposed therebetween. The low noise cable P1 of this embodiment was obtained.
When the sheath 15 is formed (covered) on the outer circumferential surface of the presser winding of the semiconductive tape 13, the surface of the insulating coating 11b of the insulating core wire 11 is partially due to the heat of the sheath extrusion coating (sheath extrusion temperature is 160 ° C., for example). Softening (PVC softening temperature: 95 ° C.) caused the insulation coatings 11b and 11b to fuse together.

The 4 m length of the low noise cable P1 is connected to a detection circuit incorporating an oscilloscope C as shown in FIG. 5B, and the low noise cable P1 is connected to the middle as shown in FIG. And then gripping both ends by hand, hitting the iron table T 10 times with the same speed each time, and measuring the absolute value of the peak of the noise voltage displayed on the oscilloscope C at each hit. The average of the 10 measurements was “3 mV”.
As a comparative example, the same test was performed on the low noise cable P2 having the conventional configuration shown in FIG. 6 having the specification shown in FIG. 7, and the average was “68 mV”. The insulating coating 1b of the comparative example was ETFE (ethylene tetrafluoroethylene), and the semiconductive tape 3 was PTFE (polytetrafluoroethylene).

  From this, it can be understood that the cable P1 of this embodiment is a low-noise cable that is less susceptible to noise than the conventional cable P2.

In addition, as long as there is no hindrance, the conventional interposition 2 can be appropriately interposed in the space between the insulation core wires 11.
Further, not only the four-core cable P1 of the embodiment but also two-core, three-core, five-core, six-core, and so on cables can be made low noise by adopting the present invention. .
Furthermore, the material of the insulation coating 11b, the tape 13, the sheath 15 and the like of the insulation core wire 11 is not limited to the above-mentioned materials. For example, the tape 13 is appropriately changed from an insulating material to the purpose and location of the cable P1. Needless to say, you can.

The low noise cable P1 according to the present invention can be used as a signal cable from various sensors and the like that are disliked by noise generation due to impact. For example, it can be used as a signal cable from an acceleration sensor, and the acceleration sensor generally uses a piezoelectric element, an electrodynamic element, a strain gauge, a semiconductor element, etc., including vehicles such as automobiles and trains, It can be used to measure electrical products such as personal computers and audio equipment, electronic parts used in them, industrial equipment, various plants, grounds and buildings, and ultimately human movements.
For example, (1) Abnormal vibration monitoring / equipment diagnosis of various plants, such as vibration monitoring of rotating machinery and bearing deterioration diagnosis such as steel, paper, petrochemical, power plant, cement factory, (2) automobile, aircraft, ship, Vibration characteristics research and reliability test and shipping inspection of products such as rockets, satellites, motors, HDDs, fans, AV equipment, mobile phones, etc. (3) Unbalance vibration such as balance correction of lathes, grinders, silicon wafer cleaners, etc. Measurement, (4) Earthquake resistance research of large structures such as buildings, dams, bridges, steel towers, (5) Monitoring of operating conditions of air conditioners such as clean rooms and intelligent buildings, (6) Construction sites, road traffic, factories, ground (7) Plant maintenance, detection of leaks in piping and traps for energy conservation measures, (8) Investigation of transportation environment, vibration during product transportation such as rationalization of packaging materials Impact measurement, (9) Research on ride comfort of vehicles such as railways, automobiles, aircraft, agricultural machinery, construction machinery, (10) Development of sports equipment such as ski mode analysis of skis, rackets and helmets, (11) Diagnosis of osteoporosis Medical field such as human body motion monitor, (12) Water leak sound detection, use as a hearing aid for lifesaving at the time of disaster, etc. can be considered.

Cross-sectional view of one embodiment Dimensions explanatory drawing of insulation coating of insulation core wire of same embodiment Production explanatory diagram of the same embodiment Specification diagram of the embodiment Performance test explanatory diagram of the same embodiment Cross section of conventional example Specification diagram of the conventional example

Explanation of symbols

P1, P2 Low noise cable 1, 11 Insulating core wire 11a Insulating core wire conductor 11b Insulating core wire insulating coating 11b 'Insulating coating side surface 2 Intervening 3, 13 Semiconductive tape 4, 14 Electrical shielding layer 5, 15 Sheath

Claims (5)

In a low noise cable (P1) in which a plurality of insulating core wires (11) are twisted together and a sheath (15) is formed on the outer peripheral surface with an electric shielding layer (14) interposed therebetween,
The insulation coating (11b) of the insulation core wire (11) has a cross-sectional fan shape, and the fan insulation coating (11b) of each insulation core wire (11) has a side surface ( 11b ') Rutotomoni the outer peripheral surface generation is suppressed electrostatic noise voltage is covered with the electrically shielding layer (the sheath interposed 14) (15) due to friction inter insulating coating is disposed in contact with the Low-noise cable for signal transmission , characterized by A tape (13) is pressed and wound around the outer peripheral surface of the twisted insulation core wires (11), and a sheath (15) is formed on the outer peripheral surface with the electric shielding layer (14) interposed therebetween. The low-noise cable for signal transmission according to claim 1. The insulation coating (11b) of each of the insulation core wires (11) is deformed by pressing and winding the tape (13) to form a sectional fan shape, and the side surface (11b) of each fan-shaped insulation coating (11b) around the center of the cable. The low noise cable for signal transmission according to claim 2, wherein ') is arranged in contact. The low noise cable for signal transmission according to claim 2 or 3, wherein the hardness of the tape (13) is higher than the hardness of the insulating coating (11b) of the insulating core wire (11). The signal transmission according to any one of claims 1 to 4, characterized in that the insulation coating (11b) of each of the insulation cores (11) is adhered or fused to each other at its side surface (11b '). Low noise cable for use .

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