Connector with ground connection improved in protection against a noise trouble

[0001] This application claims priority to prior Japanese patent application JP 2005-353855, the disclosure of which is incorporated herein by reference.

[0002] This invention relates to a connector adapted to be used in high-speed transmission and, in particular, to a connector suitable for a small-sized electronic apparatus such as a PDA (Portable Digital Assistant) and a mobile telephone.

[0003] For high-speed transmission, a coaxial cable is generally used widely. The coaxial cable comprises a center conductor and an outer conductor surrounding the center conductor via an insulating member. Therefore, a connector to be connected to the coaxial cable comprises a contact to be connected to the center conductor and a ground connection structure to be connected to the outer conductor.

[0004] Japanese Unexamined Patent Application Publication (JP-A) No. 2001-307822 discloses a connector including such ground connection structure. The connector comprises a shell covering an insulator holding a contact to be connected to a coaxial cable. The shell comprises a first shell member arranged at a position corresponding to a contacting portion of the contact and fixedly held by the insulator and a second shell member removably held by the insulator. The second shell member has a holding portion clamping and holding the coaxial cable in cooperation with the insulator.

[0005] The above-mentioned ground connector structure is connected to a mating connector via the shell. In addition, the number of points of ground connection is small. Therefore, an electric resistance is increased. As a result, a ground condition is insufficient so that a noise generated from a signal line is not sufficiently shielded to often cause a noise trouble.

[0006] It is therefore an object of this invention to provide a connector which can be considerably reduced in electric resistance in ground connection and is therefore improved in protection against a noise trouble.

[0007] It is another object of this invention to provide a connector capable of efficiently achieving ground connection of a ground line of a shielding wire of a thin coaxial cable used in a small-sized electronic apparatus such as a mobile telephone and a PDA.

[0008] Other objects of the present invention will become clear as the description proceeds.

[0009] According to an aspect of the present invention, there is provided a connector to be connected to a cable. The connector comprises a first contact having a terminal portion to be connected to a center conductor of the cable, a second contact having a grounding terminal portion, a housing holding the first and the second contacts, a ground bar clamping the cable and connected to an outer conductor of the cable, and a shell coupled to the housing. The ground bar has a contact connecting terminal to be connected to the grounding terminal portion of the second contact. The shell at least covers the terminal portion of the first contact, the grounding terminal portion of the second contact, and the ground bar. At least one of the ground bar and the shell has a shell connecting terminal to be connected to a shell of a mating connector.

[0027] Referring to FIGS. 1A to 6, description will be made of a structure of a connector according to one embodiment of this invention.

[0028] At first referring to FIGS. 1A to 1F, a plug connector 10 for high-speed transmission comprises a plurality of signal contacts as first contacts 1 and a pair of ground contacts 2 as second contacts each of which is made of a thin, long conductive material, an insulating housing 11 holding the signal contacts 1 and the ground contacts 2, a conductive ground bar 4 holding a plurality of cables 13 comprising coaxial cables and coupled to the housing 11, and a plug shell 12 made of a metal plate and covering the housing 11 and the ground bar 4 from the above. On opposite sides of the plug shell 12, a pair of plug shell holding portions 15 are formed. The plug shell holding portions 15 are held by a pair of fixing portions 14 formed on left and right sides of the housing 11, respectively.

[0029] The housing 11 is provided with a fitting portion 11a formed on its front side to be fitted to a mating connector. From a rear side of the housing 11, the cables 13 connected to the contacts 1 and 2 are extracted. The plug connector 10 illustrated in the figures has a small size, for example, with a length of 16.5 mm, a height of 1.4 mm, and a width of 2.3 mm.

[0030] As illustrated in FIGS. 2A to 2C, the housing 11 of the plug connector 10 has an upper surface provided with receiving grooves 11b assigned to the signal contacts 1 and with another receiving groove 11c which is formed at a center of the housing 11 and assigned to the ground contacts 2. Each of the signal contacts 1 has a terminal portion 1a which is placed in each receiving groove 11b and serves as a connecting portion to be connected to a center conductor 13a of each cable 13. The ground contacts 2 include, as a grounding terminal portion, terminal portions 2a, respectively, which are placed in the receiving groove 11c that is positioned at the middle portion of the housing 11. Each of the ground contacts 2 further includes another terminal portion 2b extending along a projecting wall 11d of the housing 11 and serving as a shell connecting terminal connected to a shell of a mating connector which will later be described with reference to FIGS. 8A-9C.

[0031] In the housing 11, the fixing portions 14 are formed on the opposite sides thereof to receive the plug shell 12. Each of the fixing portions 14 is provided with a ground bar fitting hole 14b and a ground bar fitting groove 14c.

[0032] As shown in FIG. 3, the plug shell 12 is provided with the plug shell holding portions 15 formed on its opposite sides. Each of the plug shell holding portions 15 has a plug shell connecting member 15a formed on its front side and extending downward and a C-shaped plug shell connecting member 15b formed on its rear side. The plug shell connecting members 15a and 15b cooperate with each other to fix the plug shell 12 to the fixing portions 14 of the housing 11. The plug shell 12 has a front end portion 12b bent in a generally vertical direction and a rear end portion 12e bent upward in a rounded shape. The plug shell 12 has an opening portion 12f formed on its rear side to serve as a soldering hole as will later be described.

[0033] Referring to FIG. 4, the ground bar 4 includes a ground bar body 4c, a cable holding member 4d having a generally S-shaped section, and a pair of ground bar connecting members 4b having a generally U shape and formed on left and right sides of the ground bar body 4c. The ground bar body 4c includes a contact connecting terminal (contact connecting member) 4a formed at its center and extending frontward. The contact connecting terminal 4a includes an inclined part extending from the ground bar body 4c and a horizontal part extending from the inclined part. The horizontal part of the contact connecting member 4a is soldered and connected to the connecting portions 2a of the ground contacts 2 illustrated in FIG. 1E.

[0034] The ground bar 4 preliminarily holds the cables 13. Specifically, each of the cables 13 has the center conductor 13a, an outer conductor (not shown) surrounding the center conductor 13a via an insulating member, and an outer sheath (not shown) covering the outer conductor. The cables 13 are arranged at a predetermined pitch in a transversal direction. The outer conductor has an exposed part clamped between the ground bar body 4c and the cable holding member 4d and fixed by soldering. At one end of each cable 13, the center conductor 13a is exposed. At a part spaced from the one end, the outer conductor is exposed.

[0035] Each of the ground bar connecting members 4b is inserted into the ground bar fitting hole 14b and the ground bar fitting groove 14c of the fixing portion 14 as clearly shown in FIG. 2C. Thus, the ground bar 4 is held by the housing 11 as illustrated in FIG. 5. After the ground bar 4 is held by the housing 11, the center conductors 13a of the cables 13 held by the ground bar 4 are soldered and fixed to the connecting portions (terminal portions) 1a of the signal contacts 1 located in the receiving grooves 11b of the housing 11, respectively.

[0036] As clearly shown in FIG. 1E, the ground bar 4 is covered with the plug shell 12. At this time, as illustrated in FIG. 6, the positional relationship between the ground bar 4 and the plug shell 12 is fixed in the state where the plug shell holding portions 15b are located above the ground bar connecting members 4b.

[0037] Referring to FIGS. 7A to 7C, description will be made of a method of producing a structure including the cables 13 held by the ground bar 4, i.e., a cable assembly 5. A part to finally become the ground bar 4 is designated by same reference numerals as those in FIG. 4.

[0038] As illustrated in FIGS. 7A and 7B, a member for forming the ground bar 4 includes first and second plate members 31 and 32 extending in a widthwise direction. The first and the second plate members 31 and 32 are formed integral to each other by press-punching and bending a single metal plate. In the state illustrated in FIGS. 7A and 7B, transportation and handling are carried out.

[0039] The ground bar 4 is formed by a part of the first plate member 31. The first plate member 31 includes a pair of first straight portions 31 b formed on outer sides of the ground bar 4 via a pair of connecting portions 31a, respectively. Each of the straight portions 31b has a circular hole 31c for positioning.

[0040] On the other hand, the second plate member 32 has a long supporting portion 32d extending in a longitudinal direction and a pair of straight portions 32e formed on longitudinal opposite ends of the supporting portion 32d and extending in a direction perpendicular to the longitudinal direction. Each of the straight portions 32e has a positioning hole 32f formed at its center. The supporting portion 32d of the second plate member 32 is connected to the cable holding member 4d of the ground bar 4 via two connecting portions 32g.

[0041] As illustrated in FIG. 7C, the connecting portions 31a and 32g are cut off to separate the cable assembly 5 from the other part. Thus, the cable assembly 5 including the cables 13 held by the ground bar 4 is obtained.

[0042] Turning back to FIGS. 1E and 1F , description will be made of assembling of the plug connector 10.

[0043] As illustrated in FIG. 1F, the cable assembly 5 is fixed to the housing 11 and the center conductors 13a at one ends of the cables 13 are fixed by soldering to the terminal portions 1a of the contacts 1. The plug shell connecting members 15a and 15b are fitted to the shell fitting holes 14c and the shell fitting grooves 14a formed on the fixing portions 14 at the opposite sides of the housing 11, respectively. Thus, the plug shell 12 is fixed and covers the ground bar connecting members 4b at the opposite sides of the ground bar body 4c.

[0044] In the above-mentioned manner, the plug shell 12 and the ground bar 4 are securely connected as illustrated in FIG. 1E. The contact connecting terminal (connecting member) 4a of the ground bar 4 is soldered and fixed to the terminal portions 2a of the ground contacts 2 at the center.

[0045] As illustrated in FIG. 1F, the plug shell connecting members 15a and 15b on the opposite sides of the plug shell 12 are fitted to the fixing portions 14. At this time, the ground bar body 4c and the shell 12 are electrically connected and fixed to each other with a solder fillet standing around the opening portion 12f.

[0046] With the above-mentioned plug connector 10, it is possible to achieve direct ground connection from the ground bar. Because the number of connection points is large, it is possible to considerably lower an electric resistance. Therefore, it is possible to provide ground connection improved in protection against a noise trouble. Further, it is possible to efficiently achieve ground connection of a shield wire of a thin coaxial cable used in a small-sized electronic apparatus such as a portable telephone and a PDA.

[0047] Next referring to FIGS. 8A to 9C, description will be made of a receptacle connector as the mating connector.

[0048] FIGS. 8A to 8D show the receptacle connector 20 that is for high-speed transmission. The receptacle connector 20 is adapted to be connected to the plug connector 10 illustrated in FIGS. 1A to 1F. The receptacle connector 20 has a small size, for example, with a width of 17.3 mm, a height of 0.95 mm, and a length of 2.4 mm. The receptacle connector 20 is mounted to a substrate and fitted to the plug connector 10 illustrated in FIG. 1A to achieve connection of the coaxial cables. The receptacle connector 20 comprises a housing 21, a shell 22 covering a side surface of the housing 21, and a plurality of signal contacts 23 held by the housing 21. Each of the signal contacts 23 has an L shape. The signal contacts 23 have one ends extending to outsides of opposite wall portions of the housing 21 to form soldering portions.

[0049] As shown in FIGS. 9A to 9C, the housing 21 is provided with a long groove 21a formed at its center, extending along a longitudinal direction thereof, and opened upward. Along a wall portion of the groove 21a, the contacts 23 are arranged on a plane perpendicular to a longitudinal direction of the groove 21a. The contacts 23 are held by the housing 21 and the receptacle shell 22 are fitted to cover an outer periphery of the housing 21 and the contacts 23. The receptacle shell 22 has a pair of first shell contacts 22a formed at its center, a pair of second shell contacts 22b, and a pair of third shell contacts 22c. The first shell contacts 22a have a generally U shape and have end portions exposed outward from opposite frame sides 22f of the receptacle shell 22. The second shell contacts 22b and the third shell contacts 22c are formed on opposite sides to face each other. The receptacle shell 22 has a pair of soldering terminal portions 22g formed outside to be soldered to the substrate and a pair of soldering terminal portions 22e formed on opposite sides thereof. When the plug connector 10 is fitted to the receptacle connector 22, the other terminal portion 2b of each ground contact 2 of the plug connector 10 becomes in contact with each shell contact 22a of the receptacle connector 20 so that ground connection is established.

[0050] While the present invention has thus far been described in connection with a few preferred embodiments thereof, it will readily be possible for those skilled in the art to put this invention into practice in various other manners. Although the description is made about the connector including a plurality of signal contacts and a pair of ground contact, the present invention is applicable also to a connector including a single signal contact and a single ground contact.