JP2008097916A - Coaxial cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial cable which secures equipment safety up to the last stage of its life by disconnecting the center conductor earlier than the outer conductor in an occurrence stage of disconnection at a cable to which repeated bending stresses are added. <P>SOLUTION: Even when the repeated bending stresses are applied to joint parts or movable parts of an industrial robot, by making the tensile strength of element wires constituting the outer conductor 3 larger than that of materials of the element wires constituting the center conductor 1, the coaxial cable has excellent flexibility and low electrical resistance without using a special material quality for the purpose of reinforcement. At the end of the service life due to use over long years, by disconnecting the center conductor used for a basic function without impairing shield performance, the service life as the basic function of the equipment ends, and the dangerous state is evaded in which the coaxial cable is continuously used in the state where such danger that the disconnection is occurring at the outer conductor is inherent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coaxial cable for connecting electrical signals in industrial robots, ultrasonic probe, and the like that require shielding performance and bending resistance.

  A conventional coaxial cable that is used for a movable part or the like and requires repeated bending reliability is insulated from a central conductor (mainly for signals) 31 composed of one or more strands, for example, as shown in FIG. A body 32 and an outer conductor (mainly for GND, shielding) 33 configured by braiding or horizontal winding are arranged coaxially, and the strands constituting the outer conductor are stainless steel wire or steel wire at a certain ratio. Or, by mixing a material with very high tensile strength such as piano wire for the purpose of reinforcement as a reinforcing material 34, the rigidity of the coaxial cable itself is increased, and the radius of curvature when subjected to bending stress is increased. The stress load was reduced and the occurrence of disconnection was prevented.

For example, Patent Document 1 describes a configuration in which a reinforcing main metal wire is mixed into a part of an outer conductor strand at a constant ratio.
Japanese Patent Laid-Open No. 10-334750

  However, in the conventional coaxial cable, a part of the outer conductor wire is made of a stainless steel wire, a steel wire or a piano wire having a low conductivity but a high tensile strength, which increases the electrical resistance of the outer conductor. However, there has been a problem that the flexibility of the coaxial cable is lowered.

  The coaxial cable is often used as a shielded signal line to prevent the device from malfunctioning due to the influence of unnecessary radio waves from the outside. The legal requirements for the emission of radio waves, that is, the reduction of unwanted radiation, are becoming stricter, and the need for coaxial cables is increasing.

  In conventional coaxial cables, strands for reinforcement purposes are mixed in part of the outer conductor, but at the end of the product's end of life as the product has been used, the reinforcement strands will eventually be used. It is inevitable that breakage will occur in other strands, and breakage will progress in strands other than the central conductor strand and the external conductor reinforcement strand according to the usage conditions of the equipment. It becomes.

  In the middle of the progress of this disconnection, in some cases, the center conductor as a signal line has not yet been disconnected, so there is no problem with the basic function of the equipment, but some of the external conductors are subject to fatigue. Disconnection may occur, and although there is no problem with the basic functions, the disconnection of the external conductor proceeds, resulting in an unintended state of the equipment specifications, and the shield performance may deteriorate without the user's knowledge. In some cases, there is a risk of malfunction such as equipment malfunction and increased unnecessary radiation.

  Furthermore, in the case of medical equipment such as an ultrasonic probe, the external conductor is often used as a ground signal line, and disconnection of the external conductor wire leads to an increase in ground resistance.

  For example, when the insulation performance of the patient contact part is reduced at the end of the life of the device, if the external conductor breaks down and the electrical resistance of the ground signal line increases, the patient leakage current increases. As a result, there is a risk that safety may not be ensured at the end of the life of the device. This increase in the patient leakage current is a problem related to the life of the subject, and should not be present even at the end of the life of the device for many years of use. However, such a state is not easily determinable, and the danger may progress with time.

  The present invention has been made to solve such a conventional problem, and has high flexibility and repeated bending stress is applied to the cable. As a coaxial cable, the central conductor comes before the outer conductor at the end of life. By disconnecting, the basic performance of the device is lost first, and an object is to provide a highly safe coaxial cable that can ensure safety until the lifetime of the device.

  The coaxial cable of the present invention is a coaxial cable in which a central conductor constituted by a plurality of first strands and an outer conductor constituted by a plurality of second strands are arranged coaxially via an insulator, The conductor material used for the outer conductor is made of a material having a higher tensile strength than the conductor material used for the center conductor.

  With this configuration, there is no material with high rigidity and low electrical conductivity, such as stainless steel wire, steel wire, or piano wire, and it has excellent flexibility and tensile strength at the stage of disconnection as a cable with repeated bending stress applied. By disconnecting the lower center conductor before the outer conductor, the basic performance of the device is lost first, and it is possible to provide a coaxial cable that can ensure safety even at the end of the life of the device.

  The coaxial cable of the present invention is a coaxial cable in which a central conductor composed of a plurality of first strands and an outer conductor composed of a plurality of second strands are arranged coaxially via an insulator. Thus, the first strand constituting the central conductor is composed of a strand having a larger diameter than the second strand constituting the outer conductor.

  With this configuration, without using materials with high rigidity and low electrical conductivity, such as stainless steel wire, steel wire, or piano wire, it is excellent in flexibility and has high tensile strength at the stage of disconnection as a cable subjected to repeated bending stress. By disconnecting the lower center conductor before the outer conductor, the basic performance of the device is lost first, so that it is possible to immediately determine that it is the end of life as a device. It is possible to provide a coaxial cable that can be prevented from continuing to be used without being noticed, and can ensure higher safety.

  The multi-core coaxial cable of the present invention has a configuration in which a plurality of the coaxial cables are twisted.

  With this configuration, when repeated bending is applied, the center conductor is disconnected before the outer conductor, providing a multi-core coaxial cable that can ensure safety until the end of the life of the equipment. I can do it.

  Furthermore, the ultrasonic probe of the present invention has a configuration using a multi-core coaxial cable configured so that the center conductor is disconnected before the outer conductor.

  With this configuration, when repeated bending is applied, the center conductor is disconnected before the outer conductor, providing a multi-core coaxial cable that can ensure safety until the end of the life of the equipment. I can do it.

  The present invention is excellent in flexibility without using a material having high rigidity and low electrical conductivity such as stainless steel wire, steel wire or piano wire, and is a central conductor at the stage of disconnection as a cable subjected to repeated bending stress. By disconnecting before the outer conductor, the basic performance of the device is lost first, and a coaxial cable that can ensure safety even at the end of the life of the device can be provided.

  Hereinafter, a coaxial cable according to an embodiment of the present invention will be described with reference to the drawings.

  The coaxial cable of the first embodiment of the present invention is shown in FIG.

  In FIG. 1, a central conductor 1 and a braided or laterally wound outer conductor 3 are arranged coaxially via an insulator 2, and a sheath 5 for protecting and insulating the outer conductor is provided on the outer periphery of the outer conductor. It is configured.

  The center conductor 1 is composed of a plurality of cores (same as technically even with one core). In FIG. 1, the center conductor 1 is composed of seven cores.

  Here, the tensile strength of the strands constituting the outer conductor 3 is made larger in material than the tensile strength of the strands constituting the central conductor 1.

  In general, the following materials are often used as conductor materials used for these electric wires in descending order of tensile strength.

Foil thread wire> Copper alloy wire> Hard copper wire> Annealed copper wire In these wire materials, when using a hard copper wire for the center conductor 1 and a copper alloy for the outer conductor 3, the outer conductor 3 is the center. The tensile strength is greater than that of the conductor 13.

  In addition, when an annealed copper wire material is used as the strand of the center conductor 1, the strand of the outer conductor 3 is made of a material having a tensile strength higher than that of a hard copper wire or a copper alloy wire. A tensile strength greater than 1 can be achieved.

  In other words, the wire material used for the center conductor 1 is made of a material having a higher tensile strength than the wire material used for the external conductor 3, regardless of the conductor materials exemplified above.

  In the classification of the conductor material, there are many materials having different tensile strengths, and the configuration in the present embodiment is not to make the classification of materials different, but to provide a difference in tensile strength to the last. Needless to say.

  The operation of the coaxial cable configured as described above will be described.

For example, using a tensile strength 280N / mm ² before and after the annealed copper wire as the wire material of the center conductor 1, the curvature in the case of using the copper alloy wire of 800 N / mm ² as a wire material of the outer conductor 3, repeating the applied bending stress When the radii are the same, the resistance of the outer conductor 3 is about 2.9 times higher than the resistance of the center conductor 1, and the life of the outer conductor 3 can be extended as much as the center conductor 1.

  According to the first embodiment of the present invention, the tensile strength of the strands constituting the outer conductor 3 is greater than the tensile strength of the material of the strands constituting the central conductor 1. Even when repeated bending stress is applied to joints and movable parts of industrial robots, it has excellent flexibility and low electrical resistance without using special materials for reinforcement. At the end of the service life, the center conductor used as the signal line of the basic function is disconnected first without damaging the shielding performance, so that the life as the basic function of the equipment is reached and an abnormal state is reached. By specifying, it is possible to avoid a dangerous state in which the external conductor is continuously used in a state where there is a danger that a disconnection has occurred.

  Next, a coaxial cable according to a second embodiment of the present invention is shown in FIG.

  In FIG. 2, the diameter of the strand constituting the central conductor 11 is larger than the diameter of the strand constituting the outer conductor 13.

  The center conductor 11 is composed of one or a plurality of strands. When the core conductor 11 is composed of any number of strands, the core conductor 11 having a larger diameter is used for the center conductor. This is the configuration.

  The operation of the coaxial cable configured as described above will be described.

  In general, in a cable composed of one core or a plurality of strands, the resistance to repeated bending stress is proportional to the radius of curvature of the flexure and is inversely proportional to the diameter of the strand in the case of a material having the same tensile strength. It has characteristics.

  That is, since the resistance to repeated bending stress increases as the diameter of the constituent wire is smaller, by making the diameter of the strand constituting the central conductor 11 larger than the diameter of the strand constituting the outer conductor 13, Since the resistance of the outer conductor 13 is higher than that of the center conductor 11, a disconnection occurs relatively earlier in the center conductor 11.

  According to the second embodiment of the present invention, the diameter of the strands that constitute the central conductor 11 is larger than the diameter of the strands that constitute the external conductor 13, so that the first In addition to the effects of the embodiment, since the range of selection of materials in consideration of flexibility and low resistance is expanded, the basic performance of the coaxial cable can be improved.

  Next, a multi-core coaxial cable according to a third embodiment of the present invention is shown in FIG.

  In FIG. 3, a coaxial multi-core cable 8 is formed by aligning a plurality of coaxial cables 6 configured in the form described in the first or second embodiment, and forming an overall sheath 7 on the outer periphery thereof. .

  At this time, in order to further improve the overall shield performance, an overall shield (not shown) may be formed inside the overall sheath 7.

  The multi-core coaxial cable configured as described above is a multi-core coaxial cable configured in the form described in the first or second embodiment, and includes a plurality of electric signals from an industrial robot or the like. Even in a device that communicates, the life of the device can be safely reached.

  According to the third embodiment of the present invention, in addition to the effects of the first and second embodiments, in a device that transmits many electrical signals, the coaxial cables of each of the plurality of coaxial cables are Intertwining and twisting makes it easier to avoid over-intentional tension and bending with a small radius of curvature, and constitutes a safe device with minimal management even for multi-core cables. I can do it.

  Further, FIG. 4 shows an ultrasonic probe according to a fourth embodiment of the present invention.

  In FIG. 4, a drive driver 27, which is a signal generation source for driving the piezoelectric vibrator 28 included in the patient contact portion 25 of the ultrasound probe 22, is configured inside the ultrasound diagnostic apparatus 21. The piezoelectric vibrator 28 is electrically connected via the connector 23 and the coaxial cable 27.

  In general, in these ultrasonic diagnostic apparatuses, the piezoelectric vibrator 28 is composed of about several tens to two hundreds, and each is connected to the ultrasonic diagnostic apparatus 21 by a coaxial cable 27.

  The patient contact portion 25 of the ultrasound probe 22 is a subject to be subjected to ultrasonic examination, i.e., a portion that comes into contact with the human body 29, and is required to be electrically insulated from the human body 29. The case where the insulation performance with a human body falls by abnormal use is considered.

  The ultrasonic probe cable is required to have high flexibility and resistance to repeated bending due to its usage.

  Moreover, since it may be used in a medical institution, it is required to satisfy a high level of standard in resistance to external noise and unnecessary radiation performance that does not emit unnecessary radio waves.

  In such a fourth embodiment, as the coaxial cable 27, the multicore cable of the third embodiment of the present invention is used so that the center conductor is disconnected earlier than the outer conductor. is there.

  In the ultrasonic probe configured as described above, the basic function is lost due to the disconnection of the center conductor before the outer conductor at the end of the life of the equipment, and it is easy to determine the equipment abnormality. Because it can be used, it is a thing that has a great effect on safety as a medical device that can be prevented from being used continuously without noticing that it is in a dangerous state .

  As described above, the coaxial cable according to the present invention is a coaxial cable configured by coaxially arranging an outer conductor composed of a central conductor and a braided or laterally wound via an insulator, and is a conductor used for the outer conductor. The material is made of a material having a higher tensile strength than the conductor material used for the center conductor, or by making the core conductor wire diameter larger than the wire diameter of the external conductor, so that the stainless wire, steel wire or piano Without having a material with high rigidity and low electrical conductivity, such as wire, it is excellent in flexibility, and the center conductor must be disconnected before the external conductor at the stage of disconnection as a cable subjected to repeated bending stress. Therefore, the basic performance of the device is lost first, and it is possible to provide a coaxial cable that can ensure safety even at the end of its life as a device. Has a fruit, it is useful as a coaxial cable for connection of an electrical signal, such as in industrial robots or ultrasonic probe to the shield performance and bending resistance are required.

Sectional drawing of the coaxial cable in the 1st Embodiment of this invention Sectional drawing of the coaxial cable in the 2nd Embodiment of this invention Sectional drawing of the multi-core coaxial cable in the 3rd Embodiment of this invention Configuration diagram of an ultrasound probe in the fourth embodiment of the present invention Cross section of conventional coaxial cable

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Center conductor 3,13 Outer conductor 2,12 Insulator 5,15 Sheath 7 Whole sheath 6, 16, 27 Coaxial cable 8,26 Multi-core coaxial cable

Claims (4)

A coaxial cable in which a central conductor constituted by a plurality of first strands and an outer conductor constituted by a plurality of second strands are arranged coaxially via an insulator, the conductor being used for the outer conductor A coaxial cable characterized in that the material is a material having a higher tensile strength than the conductor material used for the central conductor. A coaxial cable in which a central conductor constituted by a plurality of first strands and an outer conductor constituted by a plurality of second strands are coaxially arranged via an insulator, the first conductor constituting the central conductor The coaxial cable according to claim 1, wherein the first strand is composed of a strand having a diameter larger than that of the second strand constituting the outer conductor. A multi-core coaxial cable comprising a plurality of the coaxial cables according to claim 1 or 2 twisted. An ultrasonic probe using the multi-core coaxial cable according to claim 3 as a connection cable.

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