This application is based on and claims the benefit of priority from Japanese Patent Application No. 2010-143093, filed on 23, Jun. 2010 the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention is related to a contact for coaxial cable and an end processing method for coaxial cable. Particularly, the present invention relates to a structure of a contact for crimping an inner conductor and a dielectric body provided in a coaxial cable, and an end processing method of coaxial cable using the contact.
2. Related Art
A coaxial cable is an unbalanced shielded wire with characteristic impedance being defined for transmitting an electronic signal. The coaxial cable is characterized by preventing electromagnetic wave leakage to the outside and allowing bend to a certain extent, and is used as a feeder cable that connects a TV receiver, a radio or the like with an antenna.
In the coaxial cable, an inner conductor disposed in a central portion is covered with a dielectric body (insulating body) such as polyethylene. The dielectric body is covered with an outer conductor composed of braided wire, and the outer conductor is further covered with a sheath (protection covering).
In a case of connecting a contact to an end of such a coaxial cable, the contact is electrically connected to the outer conductor using an outer conductor contact having a conductor barrel that crimps the outer conductor and an insulation grip that crimps the sheath.
If a crimping force is high in a case of crimping the outer conductor by the conductor barrel, the conductor is deformed to be squashed and this affects impedance fluctuation during transmission of an electronic signal.
On the other hand, if a crimping force is low in a case of crimping the outer conductor by the conductor barrel, fixing strength between the outer conductor contact and the coaxial cable lowers and this may cause relative drop-off when a tensile force in a direction of separating the outer conductor contact and the coaxial cable is applied.
In order to prevent the abovementioned problems, for example Japanese Patent Application Publication No. 2006-302824 (hereinafter referred to as Patent Document 1) discloses a connector for coaxial cable having an outer conductor contact for crimping an outer conductor by a conductor barrel, in which a cylindrical metallic sleeve is applied to a dielectric body, covered with the outer conductor, and crimped by the conductor barrel.
The sleeve disclosed in Patent Document 1 is characterized in having a portion in which a first end edge of the abutting end edges being a joint in a circumference direction is formed to be a tapered face inclined in a diameter direction so as to climb over the other end edge and a portion which is formed to be a tapered face inclined in a diameter direction so as to slide under a second end edge, in a mixed manner, and the second end edge opposed to the first end edge is formed to be an inverse-tapered face so that it may slide along this tapered face.
Patent Document 1 discloses that such a sleeve can prevent deformation of a coaxial cable for high frequency wave when the outer conductor contact is connected to the coaxial cable, and can provide superior high-frequency response, high wire-fixing strength, and superior electrical connection.
According to a first embodiment of Patent Document 1, an inner conductor contact (inner conductor terminal 20), an outer conductor contact (outer conductor terminal 50), and a sleeve (cylindrical sleeve 30) are configured separately, thereby prolonging end processing step (fabrication time) of the coaxial cable. As a result, it is difficult to reduce production cost of a so-called wiring harness, in which connectors for coaxial cable are attached to ends of a coaxial cable.
According to a second embodiment of Patent Document 1, although an outer conductor contact (outer conductor terminal 51) and a sleeve (cylindrical sleeve 30) are integrally composed, a shell (separate shielding member 58 with a shield conductor crimp part 54 and a sheath crimp part 56) is required for connecting the outer conductor contact (outer conductor terminal 51) and a braided wire (shield conductor 16).
As a result, as in the first embodiment, it is difficult to reduce production cost of a so-called wiring harness, in which connectors for coaxial cable are attached to ends of a coaxial cable.
In addition, in the first and second embodiments of Patent Document 1, since the inner conductor contact (inner conductor terminal 20) and the sleeve (cylindrical sleeve 30) are configured to be separately attached, an attachment position, relative to the inner conductor contact, of the sleeve to the dielectric body (insulating body 14) is uncertain. If the sleeve cannot be attached to a specific position relative to the inner conductor contact and dislocation variation is great, a voltage standing wave ratio (VSWR), which is a designed value, varies due to signal reflection. If the VSWR is high, transmission failure such as noise may be caused on a reception side.
The present invention is made in view of the abovementioned problem and aims at providing a contact for coaxial cable and end processing method that can shorten an end processing step of a coaxial cable and can suppress variation of VSWR.
In a first aspect of the present invention, a contact for coaxial cable that is attached to an end of a coaxial cable includes: an inner conductor disposed in a central portion; a dielectric body that covers the inner conductor; braided wire that covers the dielectric body; and a sheath that covers the braided wire, the contact including: a contact part that is connected to a contact of a corresponding part; and an elongated connection part that extends from a base end portion of the contact part and is connected to the end of the coaxial cable, in which the connection part includes: a conductor barrel that is disposed on a side to the base end portion of the contact part and open in a U-shape that can crimp the inner conductor; an open crimp barrel that is adjacent to the conductor barrel and open in a U-shape that can crimp an exposed portion of the dielectric body so as to surround the exposed portion of the dielectric body in a cylindrical shape; and a junction band that is narrow in width and joins a part of an end edge of the conductor barrel with a part of an end edge of the open crimp barrel so as to form a bridge, and wherein the junction band is formed such that both end portions thereof are tearable during or after crimping of the conductor barrel and the open crimp barrel, so as to separate the conductor barrel and the open crimp barrel.
The “barrel” of the conductor barrel and the open crimp barrel disclosed in the first aspect indicates a crimp portion for constituting a contact, and “crimping of . . . barrel” indicates plastic deformation by shaping the barrel for obtaining superior connection. In the first aspect, the conductor barrel is crimped to the inner conductor, thereby holding the conductor barrel on the inner conductor and making the conductor barrel electrically connectable to the inner conductor. Accordingly, the open crimp barrel is crimped to the dielectric body, thereby holding the open crimp barrel to the dielectric body.
In the contact for coaxial cable according to the first aspect, a distance between the conductor barrel and the open crimp barrel is defined by a junction band. Therefore, the distance therebetween is maintained even if the junction band is torn after crimping of the conductor barrel and the open crimp barrel.
In a second aspect of the present invention, an end processing method for coaxial cable for attaching a contact for coaxial cable to an end of a coaxial cable, the coaxial cable including: an inner conductor disposed in a central portion; a dielectric body that covers the inner conductor; braided wire that covers the dielectric body; and a sheath that covers the braided wire, includes: a contact part that is connected to a contact of a corresponding part; and an elongated connection part that extends from a base end portion of the contact part and is connected to the end of the coaxial cable, in which the connection part includes: a conductor barrel that is disposed on a side to the base end portion of the contact part and open in a U-shape that can crimp the inner conductor; an open crimp barrel that is adjacent to the conductor barrel and open in a U-shape that can crimp an exposed portion of the dielectric body so as to surround the exposed portion of the dielectric body in a cylindrical shape; and a junction band that joins a part of an end edge of the conductor barrel with a part of an end edge of the open crimp barrel so as to bridge, the end processing method comprising: a cutting and peeling step of measuring the coaxial cable, cutting the end of the coaxial cable, and peeling the dielectric body, the braided wire, and the sheath in a stepped manner, from an end face of the inner conductor to predetermined lengths; a braided wire folding step of folding back the braided wire so as to cover the sheath; and a crimping and cutting step of cutting both end portions of the junction band during or after crimping of the conductor barrel and the open crimp barrel, so as to separate the conductor barrel and the open crimp barrel.
The end processing method for coaxial cable as described in the second aspect further includes: a braided wire recovery step of covering the open crimp barrel in the cylindrical shape, which has been crimped, with the braided wire; and an outer conductor contact attaching step of, using an outer conductor contact having a first crimp part and a second crimp part, crimping the open crimp barrel, which has been crimped over the braided wire, with the first crimp part and the sheath with the second crimp part.
In the contact for coaxial cable according to the present invention, the inner conductor contact, including the contact part and the conductor barrel, and the sleeve for protecting the dielectric body from deformation (after crimping of the open crimp barrel thereto) are integrally configured. As a result, at least any one of ease, reliability and accuracy of attachment to the coaxial cable can be increased. In addition, the contact for coaxial cable according to the present invention contributes to a shorter end processing step (processing time) of coaxial cable and reduction of production cost of a wiring harness.
In the present invention, the inner conductor contact for crimping the inner conductor of a coaxial cable and the open crimp barrel for crimping the dielectric body of the coaxial cable are integrally configured. When the open crimp barrel is crimped to the dielectric body of the coaxial cable, the sleeve that has been crimped is separated from the inner conductor contact such that the sleeve in a state of being covered with the braided wire functions as a sleeve for protecting the dielectric body when a braided wire is crimped. Such a configuration can solve the abovementioned problem. A preferred mode for carrying out the present invention is described hereinafter with reference to drawings.
Configuration of Contact for Coaxial Cable
First, a configuration of a contact for coaxial cable according to an embodiment of the present invention is described.
With reference to
The inner conductor 9a is also called a central conductor, and can be either a single wire or a stranded wire of a plurality of fine wires. As the dielectric body 9b, polyethylene is generally used; however, foamed resin can also be used depending on a use. The dielectric body 9b is a nonconductive insulating body having predetermined relative permittivity. Characteristic impedance can be obtained from a cross-sectional shape and relative permittivity of the coaxial cable.
The braided wire 9c is a plurality of fine copper wires braided in a cylindrical shape and can be expanded in diameter to a predetermined extent, therefore can be folded back to the side of the sheath 9d. The sheath 9d is an insulating body covering the braided wire 9c, and can be composed of an insulating material such as polyvinyl chloride, polyethylene, fluorine resin and the like.
A developed conductive metal plate is preferably formed as the first contact (contact for coaxial cable) 10. For the developed metal plate, as a nonlimiting example, copper alloy is preferably used from a viewpoint of conductivity.
With reference to
With reference to
With reference to
With reference to
As shown in
With reference to
With reference to
In addition, with reference to
End Processing Method of Coaxial Cable
First, steps for processing an end of a coaxial cable using the first contact 10 according to the present embodiment are described.
First, with reference to
Subsequently, as shown in
Thereafter, as shown in
Next, as shown in
Subsequently, as shown in
In
Function of Contact for Coaxial Cable
Next, function and effect of the first contact 10 according to the present embodiment are described.
With reference to
The conductor barrel 21 and the open crimp barrel 22 are crimped to the first contact 10 with the carrier that is unreeled from the reel, using an automatic crimping machine (not illustrated) (see
As described above, the first contact 10 according to the present embodiment is suitable for crimping by the automatic crimping machine. By using the automatic crimping machine, the both end portions of the junction band 23 can be immediately torn during or after crimping of the conductor barrel 21 and the open crimp barrel 22. This can improve productivity of a wiring harness.
In general, a crimping contact for crimping wires (including coaxial cables) is configured such that a conductor barrel and an open crimp barrel are difficult to separate. On the other hand, with reference to
With reference to
With reference to
For example, in Patent Document 1, an inner conductor contact (inner conductor terminal 20) and a sleeve (cylindrical sleeve) are crimped separately. On the other hand, in the present invention, the conductor barrel 21 (inner conductor contact) and the open crimp barrel 22 (sleeve) are crimped at the same time as shown in
As described above, the first contact 10 according to the present embodiment can shorten the end processing step (processing time) of the coaxial cable 9. The first contact 10 according to the present embodiment can thus contribute to reduction of production cost of a wiring harness.
On the other hand, with reference to
When a high-frequency signal (traveling wave) of a several GHz bandwidth is sent (transmitted) to the coaxial cable 9 shown in
Comparing
With reference to
With reference to
As described above, according to
With reference to
In the contact for coaxial cable according to the present invention, the inner conductor contact, including the contact part and the conductor barrel, and the sleeve for protecting the dielectric body from deformation (after crimping of the open crimp barrel thereto) are integrally configured. As a result, at least any one of ease, reliability and accuracy of attachment to the coaxial cable can be increased.
Number | Date | Country | Kind |
---|---|---|---|
2010-143093 | Jun 2010 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
6808417 | Yoshida | Oct 2004 | B2 |
7115006 | Onuma | Oct 2006 | B2 |
7160150 | Annequin | Jan 2007 | B2 |
7198509 | Takasu | Apr 2007 | B2 |
7422480 | Musick et al. | Sep 2008 | B1 |
Number | Date | Country |
---|---|---|
06-068939 | Mar 1994 | JP |
2003-257560 | Sep 2003 | JP |
2003-297493 | Oct 2003 | JP |
2003-317882 | Nov 2003 | JP |
2006-302824 | Nov 2006 | JP |
2006-310135 | Nov 2006 | JP |
2006-318788 | Nov 2006 | JP |
2009-187826 | Aug 2009 | JP |
2009-266452 | Nov 2009 | JP |
2010-0033726 | Feb 2010 | JP |
Number | Date | Country | |
---|---|---|---|
20110318960 A1 | Dec 2011 | US |