JP2014143215A - Noise depression cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise depression cable that depresses both radioactive noise and transmission noise, and that exerts depression effect to wide frequency noise.SOLUTION: A noise depression cable includes: a conductor core; a sheath that coats a circumference of the conductor core; and a noise depression sheet that adheres to at least a part of the circumference of the sheath, wherein the noise depression sheet includes a fabric or a microporous film as a substrate, and a common logarithm value of a surface resistivity of at least one surface of the noise depression sheet is in a range of 0-4.

Description

  The present invention relates to a power / communication cable, and more particularly to a noise suppression cable in which a noise suppression sheet is attached to at least a part of a surface of a sheath.

  With the development of electronic devices such as personal computers and large-screen televisions, the amount of information handled has increased remarkably. For these electronic devices, there is an increasing demand for higher capacity, higher integration, and higher speed communication, faster processing of the increasing amount of information, and transmission with higher efficiency. In order to satisfy these requirements, the clock frequency of the LSI and the transmission frequency used in the electronic device are shifted to a higher frequency side, and the use frequency of the communication device is also higher.

  Generation of noise from electronic devices is increasing due to the increase in the frequency used, and these noises are transmitted through the cable or radiated to the outside from the cable, etc. There are many problems that affect electronic devices and cause malfunctions.

  In order to solve the above-described problems, various noise removal structures have been proposed for cables that connect inside or between electronic devices. For example, as a countermeasure for suppressing radioactive noise, a shielded cable is widely used like a power cable (Patent Document 1). FIG. 1 shows an example of a general shielded cable. In FIG. 1, the conductor 1 for passing signals and electric power is centered, and the periphery of the conductor 1 is covered with an insulating portion 2, and the periphery of the insulating portion 2 is shielded by a shield member such as a metal foil 3. A shielded cable having a configuration in which the periphery is covered with a sheath 4 is shown.

  However, since a shielded cable requires a measure for dropping the shielded wire to the ground, the manufacturing process becomes complicated. Further, although effective in suppressing radioactive noise, there is no significant suppression effect on transmission noise.

  In order to solve the problem of transmission noise, various noise removal structures have been proposed. For example, as described in Patent Document 2 or 3, a structure that absorbs noise by forming a magnetic material-containing material outside the central copper wire has been proposed.

JP 2005-32663 A Japanese Patent Application No. 2008-118175 Japanese Patent Application No. 2000-102187

  However, the noise suppression capability of the magnetic material described in Patent Document 2 or 3 is the magnitude of the imaginary part (μ ″) of the relative permeability, which is the magnetic loss term of the magnetic material, and the absolute amount of the magnetic material. In order to easily increase the noise suppression capability, a large amount of magnetic material may be used, but the cable becomes thicker and heavier in proportion to the amount of magnetic material, so the convenience of the cable is impaired. On the other hand, since a material with a large μ ″ is expensive, a cable using the material becomes very expensive.

  Furthermore, although the magnetic body described in patent document 2 or 3 exhibits a high noise suppression effect with respect to a low frequency current, a noise suppression effect becomes low with respect to a high frequency current. Therefore, these magnetic materials are not suitable for electronic devices in which higher frequency currents are used in recent years.

  It is also known that the sound quality and video quality of a cable in the audio / video field are deteriorated by noise from various devices. As a cable for improving sound quality and video quality, a shielded cable described in Patent Document 1 or a cable using a magnetic material described in Patent Document 2 or 3 is used. However, since the former has a low effect of suppressing transmission noise as described above, a sufficient effect cannot be obtained for cables in the audio / video field. On the other hand, in the latter, the noise suppression effect changes according to the frequency, and the high frequency noise is not suppressed so much, so the noise removal rate of the high frequency component is lower than the noise removal rate of the low frequency component, and the sound balance is reduced. As a result, the sound quality and video quality may be degraded.

  As described above, the conventional cable for suppressing noise has an effect in a specific situation, but has problems in handling property, price, noise suppression capability in a wide range, and the like.

  Therefore, this invention makes it a subject to provide the noise suppression cable which suppresses both radioactive noise and transmission noise, and exhibits the suppression effect with respect to the noise of a wide frequency.

  Moreover, this invention makes it a subject to provide the noise suppression cable which can be produced simply without performing a ground process.

  Furthermore, an object of the present invention is to provide a noise suppression cable that does not use an expensive magnetic material, is inexpensive, and has excellent handleability.

  As a result of repeated studies, the inventors install a noise suppression sheet having at least one surface having a common logarithmic value of surface resistivity in the range of 0 to 4 on at least a part of the sheath surface of the cable. Thus, the inventors have found that the above problems can be solved, and have completed the present invention. The present invention specifically relates to the following aspects.

[1] A conductor core and a sheath covering the outer periphery of the conductor core,
The noise suppression cable includes a noise suppression sheet on at least a part of the outer periphery of the sheath, the noise suppression sheet includes a fabric or a microporous film as a substrate, and The said noise suppression cable whose common logarithm value of the surface resistivity of the at least 1 surface of a noise suppression sheet exists in the range of 0-4.

  [2] The noise suppression cable according to [1], wherein the noise suppression sheet is a non-magnetic material.

  [3] The noise suppression cable according to [1] or [2], wherein the noise suppression sheet includes the base material and a metal and / or a conductive polymer.

[4] The noise suppression cable according to any one of [1] to [3], in which the return loss (S ₁₁ ) at 1 GHz of the noise suppression sheet is 0.2 or less.

  [5] The noise suppression cable according to any one of [1] to [4], wherein the base material has a thickness of 10 μm to 200 μm.

  [6] The noise suppression cable according to any one of [1] to [5], wherein an average hole diameter of the base material is 0.5 μm to 200 μm.

  [7] The noise suppression cable according to any one of [1] to [6], wherein the fabric is a nonwoven fabric.

  [8] The noise suppression cable according to [7], wherein the nonwoven fabric includes fibers having a fiber diameter of 0.01 μm to 7.0 μm.

  [9] The nonwoven fabric includes two laminated layers, one layer is made of fibers having a fiber diameter of 10 μm to 50 μm, and the other layer has a fiber diameter of 0.01 μm to 7.0 μm. The noise suppression cable according to [7], comprising a fiber having the same.

[10] The nonwoven fabric was laminated in the following order:
A first layer comprising fibers having a fiber diameter of 10 μm to 50 μm;
A second layer composed of fibers having a fiber diameter of 0.01 μm to 7.0 μm; and a third layer composed of fibers having a fiber diameter of 10 μm to 50 μm;
The noise suppression cable according to [7].

  [11] The noise suppression cable according to any one of [1] to [6], wherein the base material is the microporous film.

  According to the present invention, the communication speed of an information processing device such as a personal computer can be increased. In addition, since the present invention has a high suppression effect on broadband noise, the sound quality or video quality of audio equipment or video equipment can be greatly improved. Furthermore, the cable of the present invention has the effects of reducing material and manufacturing costs and improving user handling.

It is sectional drawing of the conventional shielded cable. It is a typical sectional view of a noise suppression sheet used in an embodiment of the present invention. It is the schematic diagram which expanded a part of FIG. It is a schematic diagram showing a part of FIG. It is a block diagram of the system according to a microstrip line method. It is a graph showing the measurement result of a microstrip line method. It is a block diagram of the system for confirming the sine wave harmonic noise suppression effect. It is a schematic diagram showing the aspect which winds a noise suppression sheet | seat around the outer periphery of a sheath. 3 is a graph showing a test result of a 3m method in Example 1. FIG. 6 is a graph showing a test result of a 3m method in Comparative Example 1. It is a graph showing the measurement result of a sine wave harmonic noise suppression effect.

  In the embodiment for carrying out the present invention (hereinafter referred to as “this embodiment”), the type of the noise suppression cable is not particularly limited, but the noise suppression cable is used for, for example, a power / communication cable or an acoustic cable. Can. In the present specification, the term “noise suppression” refers to the property that a specific article suppresses noise from a device. The noise suppression cable is preferably a cable in which a noise suppression sheet, which will be described later, is attached to at least a part of the surface of a sheath covering a conductor core (for example, a conductive wire). Moreover, in order to express a higher noise suppression effect, it is preferable to use a noise suppression sheet having a larger area.

  The mode in which the noise suppression cable has the noise suppression sheet on the outer periphery (for example, the surface) of the sheath is not particularly limited, and examples thereof include a means for bonding, covering, or winding the noise suppression sheet on the sheath. Specifically, the method of attaching the noise suppression sheet slit processed into a tape shape in a spiral manner, the method of attaching the noise suppression sheet in a spiral shape, etc., easily covers the entire sheath surface and exhibits a high noise suppression effect. It is preferable because it can be done. Furthermore, the method of attaching the noise suppression sheet slit processed in a tape shape to the sheath surface in a spiral shape is more preferable because the noise suppression sheet easily follows the operation of the cable and does not easily impair the flexibility of the cable.

Hereinafter, the noise suppression sheet used in the present embodiment will be described with specific examples.
In FIG. 2, the noise suppression sheet 11 is shown to include a fabric 12 and a metal layer 13 that has been metal-worked.

  In FIG. 3, the noise suppression sheet 11 includes a fabric 12 and a metallized metal layer 13, and the metal layer 13 is formed on the fibers 14 constituting the fabric 12. In FIG. 3, for the sake of convenience, it should be understood that the cross section of the fiber 13 is all represented by a perfect circle.

The noise suppression sheet has a common logarithmic value of the surface resistivity (Ω / □) of at least one surface that has been metal-worked within a range of 0 to 4, and preferably within a range of 0.1 to 3. . The common logarithm of the surface resistivity means a value of log ₁₀ X where the surface resistivity is X (Ω / □). When the common logarithm value of the surface resistivity is in the range of 0 to 4, the electromagnetic wave appropriately enters the inside of the noise absorbing sheet, and the electromagnetic wave that has entered is captured by the metal processed metal and converted into electricity. Furthermore, since it is converted into thermal energy by electric resistance, the noise absorption capability is increased. If the common logarithm of the surface resistivity is less than 0, the conductivity is too high, and the electromagnetic wave is mostly reflected at the surface of the noise suppression sheet, more precisely at the metal-worked surface, Noise absorption is inferior. On the other hand, when the common logarithm value of the surface resistivity is more than 4, electromagnetic waves may pass through the noise suppression sheet, and the electromagnetic wave absorption ability (capturing ability) may be inferior.
The surface resistivity can be measured by a four-terminal method using a low resistance meter Loresta-GP, model MCP-T600 manufactured by Mitsubishi Chemical Corporation.

  The noise suppression sheet preferably has a lower electrical conductivity inside than the metal processed surface of the metal layer. As an example for making the internal conductivity smaller than the conductivity of the metal-worked surface, the ratio of the metal to the total amount of metal and fabric in the noise suppression sheet is lower than that of the metal-worked surface. Can be mentioned. FIG. 4 is a diagram for explaining the conductivity gradient of the noise suppression sheet. In FIG. 4, the noise suppression sheet 11 is shown to include a fabric 12 formed from fibers 14 and a metal layer 13 processed with a metal 15. Further, FIG. 4 shows that the ratio of metal 15 to the total amount of metal 15 and fabric in the interior (lower) is lower than the ratio of metal 15 to the total amount of metal 15 and fabric in the surface (upper). Therefore, the noise suppression sheet 11 shown in FIG. 4 has a lower conductivity inside than on the surface. On the other hand, when a flat base material such as a film is used as the base material, the above-described conductivity gradient is not formed, so that the noise absorption ability is low. In FIG. 4, for the sake of convenience, the cross section of the fiber 14 is all represented by a perfect circle. In the present specification, “conductivity” means the degree of conductivity. Therefore, since conductivity is the reciprocal of the electrical resistance value, “high conductivity” means that the electrical resistance value is low, while “low conductivity” means that the electrical resistance value is high. Means that. When an appropriate gradient is provided in the conductivity, electromagnetic waves that enter from the outside are captured and converted into electric current at a portion having a high conductivity, but the conductivity is particularly small (ie, the electrical resistance value is large) in the interior. It becomes easy to be converted into thermal energy by electric resistance. Thereby, electromagnetic waves can be absorbed with high efficiency and noise can be absorbed. Furthermore, as described above, electromagnetic waves that have entered from the outside are captured by portions with high conductivity, converted into electric current, and then propagated to various places inside the sheet. It doesn't matter.

  The noise suppression sheet can include a fabric or a microporous film as a substrate. Moreover, although a noise suppression sheet | seat can have various forms about a base material, surface processing, etc., it is preferable that it is a nonmagnetic material at least. In the present embodiment, the “non-magnetic material” refers to a material that is not a ferromagnetic material, for example, a material having at least one property of diamagnetism, paramagnetism, and antiferromagnetism.

  In the noise suppression sheet, the base material is preferably a fabric that is an aggregate of fibers. By adopting a fabric as the base material, a softer and more flexible base material can be adapted to the cable, which is preferable. In addition, it is preferable to select a fabric that is an aggregate of fibers as the base material because the entanglement points are increased and more performance can be exhibited. Further, the substrate is preferably a nonwoven fabric, and the fibers forming the fabric are preferably synthetic long-fiber nonwoven fabrics.

  In general, a fabric such as a woven fabric or a knitted fabric has a high ratio in which fibers are oriented in a specific pattern direction such as longitudinal and lateral of the fabric. In this case, the noise-absorbing fabric formed by metal processing on the fabric has the metal oriented in a certain direction and has a certain direction in noise absorption. On the other hand, if it is a noise suppression sheet | seat which made the base material the cloth which the fiber does not orientate in a fixed direction, for example, a nonwoven fabric, since it can absorb the noise of various directions, it is more preferable. Therefore, it is more preferable that the fabric used in this embodiment is a non-woven fabric.

  In the present embodiment, the fabric is more preferably formed by heat. Formation by heat is more preferable because the cost for producing the fabric can be further reduced.

  The fiber diameter of the fibers forming the fabric varies depending on the environment to which the noise suppression sheet is applied, but is generally preferably 50 μm or less. This is because when the fiber diameter is 50 μm or less, a fabric having a uniform inter-fiber distance can be obtained, and leakage (for example, transmission) of electromagnetic waves can be reduced. Moreover, since the strength of the fiber is high and the possibility that the fabric or the noise absorbing fabric is cut in the metal processing step or the environment in which it is used is low, stable processing and use can be performed.

  In the noise suppression sheet, it is preferable that the fabric serving as the base material includes a layer of fibers having a fiber diameter of 7 μm or less (hereinafter sometimes referred to as “extra fine fibers”). By including the ultrafine fiber layer, the number of fibers per unit volume is increased, and the specific surface area of the fiber is increased. As a result, the specific surface area of the metal layer is also increased, and the noise absorption capability is further increased. In addition, since the noise suppression sheet can be made thin by including the ultrafine fiber layer, it is suitable for a cable in the audio / video field aiming at weight reduction and thinning. In addition, since the noise suppression sheet is thin, the sheet can be flexibly bent, which is suitable for cables that require flexibility.

  The fiber diameter of the ultrafine fiber is preferably 0.01 μm or more, and more preferably 0.05 μm or more.

  In this embodiment, the nonwoven fabric used as a substrate can be formed from a plurality of different layers. For example, in the nonwoven fabric, at least one layer composed of fibers having a fiber diameter of 10 μm to 50 μm and at least one layer composed of fibers having a fiber diameter of 0.01 μm to 7.0 μm are laminated in any order. Is preferably obtained. More preferably, the nonwoven fabric comprises two layers laminated, one layer consisting of fibers having a fiber diameter of 10 μm to 50 μm, and the other layer having a fiber diameter of 0.01 μm to 7.0 μm. It consists of fibers. More preferably, the nonwoven fabric has a first layer composed of fibers having a fiber diameter of 10 μm to 50 μm; a second layer composed of fibers having a fiber diameter of 0.01 μm to 7.0 μm; and a fiber diameter of 10 μm to 50 μm. It is obtained by sequentially laminating a third layer made of fibers. In the present embodiment, any of the layer made of fibers having a fiber diameter of 10 μm to 50 μm and the layer made of fibers having a fiber diameter of 0.01 μm to 7.0 μm may be the upper surface of the substrate, and any of them is metal-worked. Also good.

  The thickness of the fabric is preferably in the range of 10 μm to 200 μm, and more preferably in the range of 15 μm to 200 μm. If the thickness of the fabric is less than 10 μm, if the noise suppression sheet is made thin and tape-like, the strength of the noise suppression sheet is weakened, and it may be difficult to coat the cable. On the other hand, if the thickness of the fabric exceeds 200 μm, the flexibility is lost and it may be difficult to coat the cable. Further, if the thickness of the fabric exceeds 200 μm, it is not preferable because the cable diameter of the final product becomes large when the cable is covered. The thickness of the fabric can be measured according to the method specified in JIS L-1906: 2000.

  The fabric preferably has an average pore size of 0.5 μm to 200 μm, more preferably has an average pore size of 1.0 μm to 120 μm, and further preferably has an average pore size of 9 μm to 110 μm. When the average pore diameter is less than 0.5 μm, the distance between the respective fibers is too close and the flow of electricity is not hindered, so that the desired noise absorbing ability is not exhibited. Moreover, when an average hole diameter is 200 micrometers or less, the confounding point of fibers will increase and the noise absorptivity can be made higher by the switching effect. The average pore diameter can be measured by the method described in the examples.

  In this specification, “metal processing” means attaching metal, specifically, attaching metal to the fabric and / or in the fabric, or in some cases, to the fibers constituting the fabric. Any process that can be done.

  In the present embodiment, the metal to be processed is not particularly limited as long as it is a nonmagnetic metal. For example, aluminum, tantalum, niobium, titanium, molybdenum, chromium, copper, silver, gold, platinum, lead, And compounds such as oxides or nitrides thereof, and mixtures thereof.

  The conductive material processed into the base material of the noise suppression sheet may be a conductive polymer instead of the metal. Although it does not specifically limit as a conductive polymer, From a viewpoint which can reduce processing basic weight, a highly conductive thing, such as polyaniline, polypyrrole, polythiophene, or those derivatives, is preferable.

  As the base material of the noise suppression sheet, a microporous film may be used instead of the fabric. Since the microporous film forms a three-dimensional network in the same manner as the nonwoven fabric, it is preferable because it can exhibit noise suppression performance equivalent to that of the noise suppression fabric described above by being processed with a conductive material. The material of the microporous film is not particularly limited, but preferably has an average pore diameter of 0.5 μm to 200 μm, and preferably has an average pore diameter of 1 μm to 120 μm, in order to develop good noise suppression performance. Is more preferable. The thickness of the microporous film is not particularly limited, but is preferably 10 μm to 200 μm.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples. In addition, the noise suppression capability of a noise suppression sheet | seat and the measuring method and evaluation method of a noise suppression cable are as follows.

(1) Noise suppression performance of noise suppression sheet Evaluation was performed according to IEC standard 62333-2 (microstrip line method). That is, the microstrip line method was used as a quantification method for the noise suppression effect (see FIG. 5). The measurement was performed using a microstrip line fixture (manufactured by Microweb Factory) having an impedance of 50Ω by a S-parameter method and a network analyzer (model N5230C manufactured by Agilent Technologies). The size of the noise suppression fabric was measured using 5 cm × 5 cm, which was placed on the MSL. As shown in FIG. 5, the return loss (S ₁₁ ) and the transmission attenuation (S ₂₁ ) of the S parameter were measured at each frequency, and the loss rate represented by Equation-1 was calculated.
(Formula -1) loss rate _{(Ploss / Pin) = 1- (} S 11 + S 21) / 1

(2) Surface resistance value of noise suppression sheet The surface resistance was measured using a four-terminal method (low resistance meter Loresta-GP, model MCP-T600, manufactured by Mitsubishi Chemical Corporation). In the measurement, n = 3 and an average value was used.

(3) Metal Thickness Measurement Method of Noise Suppression Sheet For metal film thickness, N = 5 average of transmittance (OD value) measured with Macbeth densitometer (TD932 manufactured by Macbeth) was calculated. When the base material used for the noise-suppressing fabric is opaque and has a lot of irregular reflection, when metal processing is performed, a PET film is simultaneously introduced and the OD value of the PET film is measured to obtain the metal thickness.

(4) Magnetic Permeability Measurement Method of Noise Suppression Sheet A thin film magnetic permeability measurement system (Ryowa Denshi Co., Ltd. Model PMF-3000) was used. In order to fix the materials, the object to be measured was measured by sticking to a PET resin sheet with a double-sided tape (NW-5 manufactured by Nichiban). In the measurement, n = 3 and an average value was used.

(5) Average hole diameter (μm) of the noise suppression sheet
PMI palm porometer (model: CFP-1200AEX) was used. For the measurement, SMIWICK made by PMI was used as the immersion liquid, and the sample was immersed in the immersion liquid and sufficiently deaerated to measure.
In this measuring device, the filter is immersed in a liquid with a known surface tension in advance, and pressure is applied to the filter from a state in which all pores of the filter are covered with a liquid film. The pore diameter calculated from the tension is measured. The following formula is used for the calculation.
d = C · r / P
(Where d (unit: μm) is the pore size of the filter, r (unit: N / m) is the surface tension of the liquid, P (unit: Pa) is the pressure at which the liquid film of that pore size is broken, and C is a constant .)
From the above formula, when the flow rate (wetting flow rate) when the pressure P applied to the filter immersed in the liquid is continuously changed from low pressure to high pressure is measured, the initial pressure is not broken even with the liquid film with the largest pores. Therefore, the flow rate is zero. As the pressure is increased, the liquid film with the largest pores is destroyed and a flow rate is generated (bubble point). When the pressure is further increased, the flow rate increases in accordance with each pressure, and the liquid film with the smallest pores is destroyed, which coincides with the dry flow rate (dry flow rate).
In this measuring device, the value obtained by dividing the wet flow rate at a certain pressure by the dry flow rate at the same pressure is called the cumulative filter flow rate (unit:%). The pore diameter of the liquid film destroyed at a pressure at which the cumulative filter flow rate becomes 50% was called the average flow pore size, and this was defined as the average pore size of the noise suppression sheet of the present invention.

(6) Noise suppression sheet base material thickness (μm)
According to the method prescribed in JIS L-1906, the thickness of 10 locations per 1 m width was measured, and the average value was obtained. The load was 9.8 kPa.

(7) Radiation noise suppression effect of noise suppression cable Using the noise suppression cable shown in the examples, noise measurement was performed by the 3m method, which is a measurement method of International Radio Interference Special Committee Standard CISPR22. The audio component was measured in a CD playback state using an EX-A150 manufactured by JVC.

(8) Sine Wave Harmonic Noise Suppression Effect in Acoustic System of Noise Suppression Cable In order to confirm the voice quality improvement effect of the present invention, an experimental system having the configuration of FIG. 7 was assembled and voice frequency analysis was performed. 21 is a CD player: Model 2500 manufactured by Sanden Audio Systems, and 22 is an amplifier: Model 6000 manufactured by Sanden Audio Systems. No. 23 was a Mitsubishi Electric Corporation speaker: Diatone DSA1. As the power cables 24 and 25, the cable 27 between 21 and 22, and the cable 28 between 22 and 23, the noise suppression cable shown in the example was used. The distance between the microphone 23 and the microphone 26 was 1 m. The sound source was a 1 kHz sine wave. The speaker output was 80 dB.

(9) Signal-to-noise ratio (S / N ratio) in the noise suppression cable acoustic system
Furthermore, in order to confirm the noise suppression effect of the present invention, a signal-to-noise ratio (S / N ratio) analysis was performed using the experimental system configured as shown in FIG.
In this experiment, the experimental apparatus of FIG. A 1 kHz sine wave was used as the signal wave. The energy level when the signal wave was input (signal level: S) and the energy level when the signal wave was not input (noise level: N) were measured, and the S / N was calculated. When the S / N ratio is large, it can be said that the signal wave is clearer, that is, noise can be reduced.

[Examples 1-8]
The noise suppression cable of Examples 1-8 was produced with the following method, and the noise suppression capability of the noise suppression sheet | seat and the performance of the noise suppression cable were measured. In Example 1, as a noise suppression sheet, a single-sided surface of a long-fiber nonwoven fabric (Precise AS030) made of polyester resin manufactured by Asahi Kasei Fiber was used. Presise is a laminated nonwoven fabric in which a spunbond nonwoven fabric layer as a general fiber, a meltblown nonwoven fabric layer and a spunbond nonwoven fabric layer as ultrafine fibers are laminated in that order.

  In order to protect the surface metal, the noise suppression sheet was obtained by bonding a PET film (thickness: 12 μm) to the upper surface of the aluminum layer.

  The noise suppression sheet was slit to a width of 10 mm, and was wound spirally around the sheath surface of an acoustic power cable (FullTech: Evolution Power, length: 1.8 m, cable diameter: 16.5 mm) ( (See FIG. 8). In that case, it wound so that noise suppression sheets might overlap about 1 mm, and it was made to cover the whole cable surface with a noise suppression sheet. Furthermore, the same spiral winding was performed three times (in triplicate). At this time, the both ends of the noise suppression sheet and the cable sheath were bonded with a double-sided tape (NW-5 manufactured by Nichiban, size: 5 × 10 mm).

The physical properties of the noise suppression sheet and the noise suppression capability of the noise suppression cable in each example are shown in Table 1 and supplemented below.
Example 2 followed Example 1 except that the metal coated on the noise suppression sheet was changed to silver.
Example 3 followed Example 1 except that the metal coated on the noise suppression sheet was changed to a conductive polymer (polythiophene).
Example 4 followed Example 1 except that the base material of the noise suppression sheet was changed to regular spunbond: EO5050 (material: polyester, manufactured by Asahi Kasei Fibers) not containing ultrafine fibers.
Example 5 is the same as Example 1 except that the base material of the noise suppression sheet is changed to regular spunbond not containing ultrafine fibers: EO5050 (material: polyester, manufactured by Asahi Kasei Fibers), and the coating metal amount is reduced to about 1/10. I followed.
Example 6 is the same as Example 1 except that the base material of the noise suppression sheet was changed to regular spunbond not containing ultrafine fibers: EO5050 (material: polyester, manufactured by Asahi Kasei Fibers), and the amount of coating metal was increased approximately 5 times. It was.
Example 7 followed Example 1 except that the base material of the noise suppression sheet was changed to regular spunbond: N05050 (material: nylon, manufactured by Asahi Kasei Fiber).
Example 8 followed Example 1 except that the base material of the noise suppression sheet was changed to taffeta with ester yarn.
Example 9 followed Example 1 except that the base material of the noise suppression sheet was changed to a polyolefin microporous film manufactured by Asahi Kasei E-Materials.

[Comparative Examples 1-6]
Comparative Example 1 was performed under the same conditions as in Example 1 except that a cable in a state before winding the noise suppression sheet was used instead of the cable after winding the noise suppression sheet.
Comparative Example 2 followed Example 4 except that the amount of coating metal was approximately 10 times.
Comparative Example 3 followed Example 4 except that the amount of coating metal was approximately 1/20.
The comparative example 4 followed Example 1 except having changed the base material of the noise suppression sheet into the PET film (Teijin Tetoron film, thickness: 16 μm).
The comparative example 5 followed Example 1 except having changed the metal which coats a noise suppression sheet | seat into nickel.
The comparative example 6 followed Example 1 except having changed the noise suppression sheet | seat into the magnetic sheet | seat (NEC TOKIN bustalaid: R4N).

[Microstrip line measurement results]
The microstrip line measurement result of the noise suppression sheet of Example 1 is shown in FIG. Also shown 1GHz in the micro-strip line measurements of each example, 3 GHz, the loss rate and _{S 11} of 10GHz in Table 1.

[Radiation noise suppression effect]
FIG. 9 shows the result of noise reception in the antenna vertical direction in the 3 m method test in Example 1 (cable after using the noise suppression sheet), and FIG. 10 shows the result in the 3 m method test in Comparative Example 1 (cable before using the noise suppression sheet). Describes the result of noise reception in the vertical direction of the antenna. 9 and 10, it can be seen that the spike-shaped noise is reduced in the cable after using the noise suppression sheet in a wide range of 30 MHz to 1 GHz as compared with the cable before using the noise suppression sheet.

[Sine wave harmonic noise suppression effect in acoustic systems]
The measurement result of the sine wave harmonic noise suppression effect in the acoustic systems of Example 1 and Comparative Example 1 is shown in FIG. The thick line in the graph is the result of Example, and the thin line is the result of Comparative Example 1. Note that the results of Example 2 and Comparative Example 2 in FIG. 11 are normalized by an energy value of 1 kHz that is a signal wave. From FIG. 11, the harmonic noise of 2 kHz and 3 kHz is reduced in the cable after using the noise suppressing sheet compared to the cable before using the noise suppressing sheet. From this, it turns out that the harmonic noise which transmits the inside of a cable can be suppressed by using this invention. Furthermore, from FIG. 11, the floor noise from 1 kHz to 20 kHz is reduced. This suggests that by using the present invention, noise derived from signals other than signal waves, for example, noise entering from the space outside the cable, noise generated by audio equipment, and the like can be suppressed. In contrast to the signal wave, the signal wave can be heard more clearly because the frequency of the signal other than the signal, that is, noise is reduced.

[Signal-to-noise ratio (S / N ratio) in noise suppression cable acoustic systems]
From Table 1, the S / N ratios of Examples 1 to 9 are all higher than those of the cable before using the noise suppression sheet. From this, the noise suppression cable using the noise suppression sheet has a reduced noise in the sound emitted from the acoustic system as compared to the cable before using the noise suppression sheet, that is, the listener has more noise. It can be said that it delivers a small and clear sound.

On the other hand, from Table 2, the S / N ratio of Comparative Examples 2 and 4 is smaller than that of the cable before using the noise suppression sheet. That is, the noise suppression cable using the noise suppression sheet has increased noise in the sound emitted from the acoustic system as compared to the cable before using the noise suppression sheet. This is because the noise suppression sheet used for the cable has a small surface resistance value and S ₁₁ (reflection amount of noise) in the microstrip line measurement is too large, so that the noise suppression sheet does not absorb the noise inside the cable and is reflected. This is because the noise increased due to the resonance of the noise inside the cable.

  Moreover, in the comparative example 3 of Table 2, S / N ratio does not change compared with the cable before noise suppression sheet use. Since the surface resistance value of the noise suppression sheet is too large and does not have sufficient noise suppression capability, noise in the cable is not reduced.

  The present invention is applied to many fields in which noise suppression is required, and is used, for example, in the manufacture of power / communication cables, acoustic cables, and the construction of power / communication systems, acoustic systems, etc. Can do.

DESCRIPTION OF SYMBOLS 1 Conductor 2 Insulation part 3 Metal foil 4 Sheath 11 Noise suppression sheet 12 Fabric 13 Metal layer 14 Fiber 15 Metal 20 Power supply 21 CD player 22 Amplifier 23 Speaker 24 Power cable 25 Power cable 26 Microphone 27 Cable 28 Cable 51 Network analyzer 52 Microstrip Line 53 Sample 54 Incident wave 55 Transmitted wave

Claims (11)

A conductor core and a sheath covering the outer periphery of the conductor core;
The noise suppression cable includes a noise suppression sheet on at least a part of the outer periphery of the sheath, the noise suppression sheet includes a fabric or a microporous film as a substrate, and The said noise suppression cable whose common logarithm value of the surface resistivity of the at least 1 surface of a noise suppression sheet exists in the range of 0-4.   The noise suppression cable according to claim 1, wherein the noise suppression sheet is a non-magnetic material.   The noise suppression cable according to claim 1, wherein the noise suppression sheet includes the base material and a metal and / or a conductive polymer. The return loss at 1GHz of noise suppression sheet _{(S 11)} is 0.2 or less, the noise suppression cable according to any one of claims 1 to 3.   The noise suppression cable of any one of Claims 1-4 whose thickness of the said base material is 10 micrometers-200 micrometers.   The average hole diameter of the said base material is a noise suppression cable of any one of Claims 1-5 which are 0.5 micrometer-200 micrometers.   The noise suppression cable according to claim 1, wherein the fabric is a nonwoven fabric.   The noise suppression cable according to claim 7, wherein the nonwoven fabric includes fibers having a fiber diameter of 0.01 μm to 7.0 μm.   The nonwoven fabric includes two laminated layers, one layer is made of fibers having a fiber diameter of 10 μm to 50 μm, and the other layer is made of fibers having a fiber diameter of 0.01 μm to 7.0 μm. The noise suppression cable according to claim 7, comprising: The nonwoven was laminated in the following order:
A first layer comprising fibers having a fiber diameter of 10 μm to 50 μm;
A second layer composed of fibers having a fiber diameter of 0.01 μm to 7.0 μm; and a third layer composed of fibers having a fiber diameter of 10 μm to 50 μm;
The noise suppression cable of Claim 7 containing this.   The noise suppression cable according to claim 1, wherein the base material is the microporous film.

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