EP1628311A1 - Câble coaxial - Google Patents

Câble coaxial Download PDF

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Publication number
EP1628311A1
EP1628311A1 EP04254891A EP04254891A EP1628311A1 EP 1628311 A1 EP1628311 A1 EP 1628311A1 EP 04254891 A EP04254891 A EP 04254891A EP 04254891 A EP04254891 A EP 04254891A EP 1628311 A1 EP1628311 A1 EP 1628311A1
Authority
EP
European Patent Office
Prior art keywords
conductor
coaxial cable
voltage
insulator
outer circumference
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04254891A
Other languages
German (de)
English (en)
Inventor
Nobuo Harada Techno Co. Ltd. Harada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Harada Techno Co Ltd
Yosho Co Ltd
Original Assignee
Harada Techno Co Ltd
Yosho Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Harada Techno Co Ltd, Yosho Co Ltd filed Critical Harada Techno Co Ltd
Priority to EP04254891A priority Critical patent/EP1628311A1/fr
Publication of EP1628311A1 publication Critical patent/EP1628311A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00—Communication cables or conductors
    • H01B11/18—Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
    • H01B11/20—Cables having a multiplicity of coaxial lines
    • H01B11/206—Tri-conductor coaxial cables

Definitions

  • the present invention relates to a coaxial cable, and more particularly relates to a coaxial cable in which a central conductor is used for transmitting images, and a conductor and another conductor, which is outside the other conductor, are provided on the circumference of the concentric circles having the central conductor as their center.
  • coaxial cables having characteristic impedance of 75 " are generally employed. It is known that the attenuation of picture signals is phenomenally approximated by, roughly, one-half power of the frequency. There disclosed measured values, for example, in a 3C-2V coaxial cable, when the frequency of the picture signal is 4 MHz, the attenuation is 27 dB/Km; when the frequency of the picture signal is 6 MHz, the attenuation is 32 dB/Km; when the frequency of the picture signal is 8 MHz, the attenuation is 38 dB/Km; and when the frequency of the picture signal is 10 MHz, the attenuation is 42 dB/Km.
  • cable compensators are employed in accordance with needs to compensate the attenuation of the picture signals.
  • Cable compensators are amplification means of picture signals and essential means for providing images influenced by attenuation as little as possible, or for compensating attenuation. These compensators are disposed, in advance, at a predetermined distant interval in accordance with the attenuation state of the picture signals, and at every position, picture signals are amplified.
  • one cable compensator is disposed in about 100 m.
  • the first tubular electro-magnetic shielding conductor is provided outside a central conductor with an insulator therebetween
  • the second tubular electro-magnetic conductor is provided outside the first tubular electro-magnetic shielding conductor with an insulator therebetween
  • the outer circumference of the second tubular electro-magnetic shielding conductor is coated with external coating which is an insulator
  • the first tubular electro-magnetic shielding conductor and the second tubular electro-magnetic shielding conductor are configured for feeding current for driving devices.
  • this coaxial cable for example, when electricity is let flow with the inner first tubular electro-magnetic shielding conductor being negative and the outer second tubular electro-magnetic shielding conductor being positive, the magnetism in the center space becomes zero. Therefore, no magnetic disturbance is imposed on the central conductor and magnetic actions caused in them form a barrier thereby carrying out protection against disturbing electric waves coming in from outside. Therefore, for example, the picture waveform sent from a monitoring camera is not disturbed at all, and the image of a monitor is not disturbed and clear images can be obtained.
  • the present invention has been accomplished for solving above described problems, and its object is to provide a coaxial cable that is able to completely shut out external noises and transmit picture signals not influenced by noises over a long distance.
  • a first mode of the coaxial cable of the invention of the present application has a configuration in which a first conductor is provided on the outer circumference of a central conductor with an insulator therebetween; a second conductor is provided on the concentric circle which has the central conductor as its center and outside the first conductor with an insulator therebetween; outside of the second conductor is coated by an external coating which is an insulator; and a DC voltage source which is able to apply DC voltage between the first conductor and the second conductor is provided.
  • a second mode of the coaxial cable of the invention of the present application has a configuration in which a first conductor is provided on the outer circumference of a central conductor with an insulator therebetween; a second conductor is provided on the concentric circle which has the central conductor as its center and outside the first conductor with an insulator therebetween; outside of the second conductor is coated by an external coating which is an insulator; a DC voltage source which is able to apply DC voltage having a predetermined voltage value between the first conductor and the second conductor such that the direct current flowing in the first conductor and the second conductor takes a desired value, is provided; and a noise barrier zone is formed in the area surrounded by the first conductor which is on the outer circumference of the central conductor and the second conductor, by electro-magnetic action brought about by the desired current.
  • a third mode of the coaxial cable of the invention of the present application has a configuration in which, in the first or the second mode, the first conductor and/or the second conductor is a braided conductor.
  • a fourth mode of the coaxial cable of the invention of the present application has a configuration in which, in any of the first to the third mode, the second conductor comprises a plurality of conductors provided on the outer circumference of the first conductor with the insulator therebetween.
  • a fifth mode of the coaxial cable of the invention of the present application has a configuration in which, in any of the first to the third mode, the second conductor comprises a conductor provided so as to be winded around the outer circumference of the first conductor with the insulator therebetween.
  • a sixth mode of the coaxial cable of the invention of the present application has a configuration in which, in any mode of the first to the fifth mode, the DC voltage having a predetermined power supply voltage value is applied such that the first conductor side has positive voltage and the second conductor side has negative voltage or the first conductor side has negative voltage and the second conductor side has positive voltage; and the direct current having the desired current value flows in the first conductor and the second conductor.
  • a seventh mode of the coaxial cable of the invention of the present application has a configuration in which, in any mode of the first to sixth mode, the power supply voltage value of the DC voltage source falls within 10 V to 150 V.
  • a noise barrier zone which is an electro-magnetically active field where the magnetic fields constantly cancel each other out is formed, and the intrinsic noise shielding effect of the shield is added so as to produce extremely strong noise shielding effect. Therefore, according to the coaxial cable of the present invention, external noises can be completely shut out, cable compensator or the like for preventing attenuation of picture signals can be reduced, a simple system can be composed, and picture signals under no influence of noises can be transmitted over a long distance. In addition, considerable economic effects are brought about.
  • FIG. 1 is a schematic view of a coaxial cable according to an embodiment of the present invention.
  • FIG. 2 is a sectional view of a coaxial cable according to the embodiment of the present invention.
  • FIG. 3 is a diagram showing an example of a simple experiment for confirming the external noise shielding effects of the embodiment of the present invention.
  • FIG. 4 is a schematic view of a coaxial cable according to a second embodiment of the present invention.
  • FIG. 5 is a schematic view of a coaxial cable according to a third embodiment of the present invention.
  • FIG. 6 is a schematic view of a coaxial cable according to a fourth embodiment of the present invention.
  • FIG. 7 is a schematic view of a coaxial cable according to a fifth embodiment of the present invention.
  • FIG. 1 is a schematic view of a coaxial cable according to an embodiment of the present invention.
  • 1 denotes a coaxial cable
  • 2 denotes a central conductor for transmitting signals, for example, of images
  • 3 denotes a first conductor on the outer circumference concentric to the central conductor
  • 4 denotes a second conductor positioned on the circumference concentric to the central conductor 2 and outside the first conductor
  • 5 denotes a first insulator composed of, for example, polyvinyl chloride (PVC) on the outer circumference of the central conductor 2
  • 6 denotes a second insulator composed of, for example, polyvinyl chloride (PVC) provided between the first conductor 3 and the second conductor 4
  • 7 denotes a third insulator composed of, for example, polyvinyl chloride (PVC) provided outside the second conductor
  • 8 denotes a DC voltage source for applying DC voltage having a predetermined voltage value between the first conductor 3 and the second
  • the DC voltage source 8 which causes direct current having a desired current value to flow in the first conductor 3 and the second conductor 4, is connected to one end of the first conductor 3 and the second conductor 4, and the other end of the first conductor 3 and the second conductor 4 are short-circuited.
  • FIG. 2 is a sectional view of the coaxial cable according to the embodiment of the present invention.
  • the numbers as same as those in FIG. 1 are denoted by the same reference numerals and explanations thereof are omitted.
  • one end of the first conductor 3 and second conductor 4 are connected to the DC voltage source 8, the other end of the first conductor 3 and the second conductor 4 are short-circuited thereby forming a DC closed circuit comprising the DC voltage source 8, the first conductor 3, and the second conductor 4.
  • a constant direct current which is determined by the predetermined voltage value of the DC voltage source 8 and the value of the resistance components of the first conductor 3 and the second conductor 4 flows.
  • FIG. 3 is a diagram showing an example of a simple experiment for confirming the external noise shielding effect of the embodiment of the present invention.
  • the reference numerals as same as those in FIG. 1 denote the same numbers, therefore explanations thereof are omitted.
  • 9 denotes a television receiver
  • 10 denotes a television camera
  • 11 denotes a pulse noise generator.
  • the television receiver 9 may be a noise level detector.
  • illustrations of the first insulator on the outer circumference of the central conductor 2, the second insulator provided between the first conductor 3 and the second conductor 4, and the third insulator outside the second conductor 4 are omitted.
  • a constant desired current brought about by the predetermined DC voltage value flows in the closed circuit which is composed of the first conductor 3, the second conductor 4, and the DC voltage source 8.
  • the current flowing through the first conductor 3 and the current flowing through the second conductor 4 have the same current value and directions thereof are opposite to each other.
  • the magnetic field caused by the current flowing in the first conductor 3 and the magnetic field caused by the current flowing in the second conductor 4 have the same magnetic field strength.
  • the magnetic field of the first conductor 3 is orthogonal to the longitudinal direction of the first conductor 3 and derived radially from everywhere of the first conductor 3.
  • the magnetic field of the second conductor 4 is orthogonal to the longitudinal direction of the second conductor 4 and derived radially from everywhere of the second conductor 4.
  • the magnetic fields have directions opposite to each other. Therefore, in the part surrounded by the first conductor 3 and the second conductor 4, the magnetic fields cancel each other out and the magnetic field is seemingly zero.
  • the magnetic fields having directions opposite to each other are constantly generated from the first conductor 3 and the second conductor 4, and at the same time, they cancel each other out. Therefore, even though the magnetic field of the part surrounded by the first conductor 3 and the second conductor 4 is seemingly zero, an extremely active field in which magnetic fields constantly cancel each other out is generated.
  • the aimed distance for transmitting images via a coaxial cable is determined and the overall length of the coaxial cable is determined.
  • the overall length of the cable is 400 m.
  • the variable DC voltage source 8, and the first conductor and the second conductor of the coaxial cable are connected in series so as to form a closed circuit.
  • the picture signals of the television camera 10 are transmitted to the television receiver via the coaxial cable while noise is generated from the pulse noise generator 11.
  • a variation is made by the DC voltage source 8 such that the DC value flowing in the closed circuit of the series connection of the variable DC voltage source 8, and the first conductor and the second conductor of the coaxial cable is varied.
  • the DC value in the closed circuit is varied and desired current value can be sought and determined.
  • the voltage condition in which no attenuation or disturbance of the image of the television receiver is shown or optimal state having the lowest noise level is exhibited is sought while the image of the television receiver is checked with eyes or the noise level is measured by the noise level detector.
  • the DC value in a closed circuit is determined depending on the resistance components in the closed circuit, therefore, to be precise, the DC power supply voltage value required to flow the desired current value differs depending on the value of resistance components in every closed circuit.
  • the resistance component based on the distance affects, in the highest ratio, in determination of a current value in the coaxial cable.
  • approximate power supply voltage value that allows a desired current value to flow was confirmed by experiments sought in the distance of 400 m.
  • the DC voltage value falls within about 12 V to about 120 V. Therefore, it was discovered that in order to provide the power supply voltage value for obtaining and flowing direct current having a desired value, a DC power supply which is able to provide DC power supply voltage value in the range 10 V to 30 V, preferably 10 V to 150 V, should be prepared.
  • the reached distance of the transmitted clear image exhibiting no disturbance or attenuation caused by noise was 500 m.
  • the reached distance of the transmitted clear image exhibiting no disturbance or attenuation caused by noise was 450 m. Therefore, generally in coaxial cables, at least in the distance of 400 m, there exhibited effects in which any external noise including the influence of, for example, high frequency noises having steep wave forms generated when accelerator via an electric system of an engine, for example, of motorcycle is suddenly stamped on, are shut off. Therefore, regarding the transmission, via a coaxial cable, of clear images exhibiting no disturbance or attenuation caused by noises , the aim for reaching the distance of 400 m without employing cable compensators is accomplished.
  • a coaxial cable of the present invention clear images are transmitted at least in the distance of 400 m without providing cable compensators, because a DC voltage source which is able to apply DC voltage having a predetermined voltage value between a first conductor and a second conductor such that the direct current flowing in the first conductor and the second conductor takes a desired value is provided.
  • FIG. 4 is a schematic view of a coaxial cable according to a second embodiment of the present invention.
  • the numbers as same as those in FIG. 1 are denoted by the same reference numerals and explanations thereof are omitted.
  • 31 denotes a first conductor on the outer circumference concentric to the central conductor 2
  • 41 denotes a second conductor positioned on the outer circumference concentric to the central conductor 2 and outside the first conductor
  • 8 denotes a DC voltage source which applies a predetermined DC voltage between the first conductor 31 and the second conductor 41 in order to cause direct current having desired current value to flow in the first conductor 31 and the second conductor 41.
  • the first conductor 31 and the second conductor 41 consist of a metal plate cylindrically winded up.
  • the illustrations of a first insulator on the outer circumference of the central conductor 2, a second insulator provided between the first conductor 31 and the second conductor 42, and a third insulator outside the second insulator 42 are omitted.
  • FIG. 5 is a schematic view of a coaxial cable according to a third embodiment of the present invention.
  • 32 denotes a first conductors on the circumference concentric to a central conductor 2
  • 42 denotes a plurality of second conductors positioned on the outer circumference concentric to the central conductor 2 and outside the first conductor 31
  • 8 denotes a DC voltage source which applies a predetermined DC voltage between the first conductors 32 and the second conductors 42 in order to cause direct current having a desired current value to flow in the first conductors 32 and the second conductors 42.
  • the first conductor 32 and the second conductor 42 consist of plurality of parallel metal conductors electrically connected in respect of both side.
  • the illustrations of a first insulator on the outer circumference of the central conductor 2, a second insulator provided between the first conductors 32 and the second conductors 42, and a third insulator outside the second conductors 42 are omitted.
  • FIG. 6 is a schematic view of a coaxial cable according to a fourth embodiment of the present invention.
  • the numbers as same as those in FIG. 1 are denoted by the same reference numerals and explanations thereof are omitted.
  • a first conductor which is winded around the outer circumference concentric to a central conductor 2 is denoted by 33
  • 43 denotes a second conductor winded around the outer circumference concentric to the central conductor 2 and outside the first conductor 33
  • 8 denotes a DC voltage source which applies DC voltage between the first conductor 33 and the second conductor 43 in order to cause direct current having a desired current value to flow in the first conductor 33 and the second conductor 43.
  • the first conductor 33 and the second conductor 43 consist of metal conductors winded spirally.
  • the illustrations of a first insulator on the outer circumference of the central conductor 2, a second insulator provided between the first conductor 33 and the second conductor 43, and a third insulator outside the second conductor 43 are omitted.
  • FIG. 7 is a schematic view of a coaxial cable according to a fifth embodiment of the present invention.
  • 34 denotes a braided conductor outside the central conductor 2
  • 44 denotes a second conductor positioned on the outer circumference concentric to the first conductor 2 and outside the braided conductor 34 which is a first conductor
  • 8 denotes a DC voltage source which applies a predetermined DC voltage between the braided conductor 34 and the second conductor 44 in order to cause direct current having a desired current value to flow in the braided conductor 34 and the second conductor 44.
  • the illustrations of a first insulator on the outer circumference of the central conductor 2, a second insulator provided between the braided conductor 34 and the second conductor 44, and a third conductor outside the second conductor 44 are omitted.

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  • Communication Cables (AREA)
EP04254891A 2004-08-13 2004-08-13 Câble coaxial Withdrawn EP1628311A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04254891A EP1628311A1 (fr) 2004-08-13 2004-08-13 Câble coaxial

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP04254891A EP1628311A1 (fr) 2004-08-13 2004-08-13 Câble coaxial

Publications (1)

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EP1628311A1 true EP1628311A1 (fr) 2006-02-22

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EP04254891A Withdrawn EP1628311A1 (fr) 2004-08-13 2004-08-13 Câble coaxial

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EP (1) EP1628311A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4642417A (en) * 1984-07-30 1987-02-10 Kraftwerk Union Aktiengesellschaft Concentric three-conductor cable
US20010032732A1 (en) * 2000-04-19 2001-10-25 Japan Aviation Electronics Industry, Limited Coaxial cable improved in transmission characteristic
JP2004273258A (ja) * 2003-03-07 2004-09-30 Harada Techno Co Ltd 同軸ケーブル

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4642417A (en) * 1984-07-30 1987-02-10 Kraftwerk Union Aktiengesellschaft Concentric three-conductor cable
US20010032732A1 (en) * 2000-04-19 2001-10-25 Japan Aviation Electronics Industry, Limited Coaxial cable improved in transmission characteristic
JP2004273258A (ja) * 2003-03-07 2004-09-30 Harada Techno Co Ltd 同軸ケーブル

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