Abstract:
An electrical connector ( 100 ) includes an insulative housing ( 2 ) extending in a front-to-back direction, a first set of contacts ( 3 ) held in the insulative housing, and a second set of contacts ( 4 ) held in the insulative housing and including at least one pair of differential contacts ( 41 ) held in the insulative housing for transferring high-speed signals. Each first contact includes a nonelastic contact portion ( 36 ). Each of the second set of contacts includes an elastic contact portion ( 43 ) located behind the nonelastic contact portion along the front-to-rear direction. At least one set of first and second sets of contacts are permanently held in the insulative housing, while the other set of first and second sets of contacts is replaceably held in the insulative housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is related to U.S. patent application Ser. No. 11/818,100, filed on Jun. 13, 2007 and entitled “EXTENSION TO UNIVERSAL SERIAL BUS CONNECTOR WITH IMPROVED CONTACT ARRANGEMENT”, which has the same assignee as the present invention. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an electrical connector, more particularly to an electrical connector compatible to standard Universal Serial Bus (USB) 2.0 connector. 
   2. Description of Related Art 
   Recently, personal computers (PC) are used of a variety of techniques for providing input and output. Universal Serial Bus (USB) is a serial bus standard to the PC architecture with a focus on computer telephony interface, consumer and productivity applications. The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standard body incorporating leading companies from the computer and electronic industries. USB can connect peripherals such as mouse devices, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, external storage, networking components, etc. For many devices such as scanners and digital cameras, USB has become the standard connection method. 
   As of 2006, the USB specification was at version 2.0 (with revisions). The USB 2.0 specification was released in April 2000 and was standardized by the USB-IF at the end of 2001. Previous notable releases of the specification were 0.9, 1.0, and 1.1. Equipment conforming to any version of the standard will also work with devices designed to any previous specification (known as: backward compatibility). 
   USB supports three data rates: 1) A Low Speed rate of up to 1.5 Mbit/s (187.5 KB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks; 2) A Full Speed rate of up to 12 Mbit/s (1.5 MB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices. All USB Hubs support Full Speed; 3) A Hi-Speed rate of up to 480 Mbit/s (60 MB/s). Though Hi-Speed devices are commonly referred to as “USB 2.0” and advertised as “up to 480 Mbit/s”, not all USB 2.0 devices are Hi-Speed. Hi-Speed devices typically only operate at half of the full theoretical (60 MB/s) data throughput rate. Most Hi-Speed USB devices typically operate at much slower speeds, often about 3 MB/s overall, sometimes up to 10-20 MB/s. A data transmission rate at 20 MB/s is sufficient for some but not all applications. However, under a circumstance transmitting an audio or video file, which is always up to hundreds MB, even to 1 or 2 GB, currently transmission rate of USB is not sufficient. As a consequence, faster serial-bus interfaces are being introduced to address different requirements. PCI Express, at 2.5 GB/s, and SATA, at 1.5 GB/s and 3.0 GB/s, are two examples of High-Speed serial bus interfaces. 
   From an electrical standpoint, the higher data transfer rates of the non-USB protocols discussed above are highly desirable for certain applications. However, these non-USB protocols are not used as broadly as USB protocols. Many portable devices are equipped with USB connectors other than these non-USB connectors. One important reason is that these non-USB connectors contain a greater number of signal pins than an existing USB connector and are physically larger as well. For example, while the PCI Express is useful for its higher possible data rates, a 26-pin connectors and wider card-like form factor limit the use of Express Cards. For another example, SATA uses two connectors, one 7-pin connector for signals and another 15-pin connector for power. Due to its clumsiness, SATA is more useful for internal storage expansion than for external peripherals. 
   The existing USB connectors have a small size but low transmission rate, while other non-USB connectors (PCI Express, SATA, et al) have a high transmission rate but large size. Neither of them is desirable to implement modern high-speed, miniaturized electronic devices and peripherals. To provide a kind of connector with a small size and a high transmission rate for portability and high data transmitting efficiency is much desirable. Such kind electrical connectors are disclosed in a U.S. Pat. No. 7,021,971 (hereinafter 971 patent) issued on Apr. 4, 2006. Detailed description about these connectors is made below. 
   From the FIGS. 4A-6H and detailed description of 971 patent, we can find that the invention material of 971 patent is to extend the length of the plug and receptacle tongue portions of the existing USB connectors and to extend depth of the receiving cavity of the existing USB connectors, thereby to accommodate additional contacts in extended areas as shown in FIGS. 4A-5H of 971 patent; or to provide the additional contacts on a reverse-side of the plug tongue portion and accordingly with regard to receptacle, to provide a lower tongue portion under a top receptacle tongue portion thereby four USB contacts are held on the top tongue portion and additional contacts are accommodated on the lower tongue portion of the receptacle. With contrast with existing USB type-A receptacle, the receptacle with top and lower tongue portion is higher in height than existing USB receptacle. 
   As shown in FIGS. 4C, 4D, 5C, 5D and 6C, 6D of the 971 patent, number of the additional contacts is eight. The eight additional contacts plus the four USB contacts are used collectively or in-collectively for PCI-Express, SATA or IEEE 1394 protocol as required. To make the extended-USB plug and receptacle capable of transmitting PCI-Express or SATA or IEEE 1394 signals is the main object of the 971 patent. To achieve this object, at least eight contacts need to be added. Adding eight contacts in existing USB connector is not easy. May be, only embodiments shown in 971 patent are viable options to add so many contacts. As fully discussed above, the receptacle equipped with two tongue portions or plug and receptacle both with a longer length are also clumsiness. That is not very perfect from a portable and small size standpoint. 
   BRIEF SUMMARY OF THE INVENTION 
   Accordingly, an object of the present invention is to provide an electrical connector with low profile and lower cost. 
   Another object of the present invention is to provide a method of assembling the electrical connector the same. 
   In order to achieve the above-mentioned object, an electrical connector comprises an insulative housing extending in a front-to-rear direction, a first set of contacts held in the insulative housing, and a second set of contacts held in the insulative housing and comprising at least one pair of differential contacts held in the insulative housing for transferring high-speed signals. Each first contact comprises a nonelastic contact portion. Each of the second set of contacts comprises an elastic contact portion located behind the nonelastic contact portion along the front-to-rear direction. At least one set of first and second sets of contacts are permanently held in the insulative housing, while the other set of first and second sets of contacts is replaceably held in the insulative housing. 
   The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is an exploded, perspective view of an extension to an electrical connector in accordance with the present invention; 
       FIGS. 2-3  are views similar to  FIG. 1 , but viewed from different aspects; 
       FIGS. 4-6  are partially assembled views of  FIGS. 1-2 ; 
       FIG. 7  is an assembled view of  FIG. 1 ; and 
       FIGS. 8-10  are cross-section views taken along lines  7 - 7  to  10 - 10  of  FIG. 7 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. In other instances, well-known circuits have been shown in block diagram form in order not to obscure the present invention in unnecessary detail. For the most part, details concerning timing considerations and the like have been omitted inasmuch as such details are not necessary to obtain a complete understanding of the present invention and are within the skills of persons of ordinary skill in the relevant art. 
   Reference will be made to the drawing figures to describe the present invention in detail, wherein depicted elements are not necessarily shown to scale and wherein like or similar elements are designated by same or similar reference numeral through the several views and same or similar terminology. 
   Within the following description, a standard USB connector, plug, and signaling all refer to the USB architecture described within the Universal Serial Bus Specification, 2.0 Final Draft Revision, Copyright December, 2002, which is hereby incorporated by reference herein. USB is a cable bus that supports data exchange between a host and a wide range of simultaneously accessible peripherals. The bus allows peripherals to be attached, configured, used, and detached while the host and other peripherals are in operation. This is referred to as hot plugged. 
   Referring to  FIGS. 1-3 , an extension to an electrical connector  100 , that is a USB plug  100 , according to the present invention is disclosed. The extension to USB plug  100  comprises an insulative housing  2  which has an insulative base portion  21  and an insulative tongue portion  22  extending from the insulative base portion  21  in a front-to-rear direction, a first set of contacts  3  and a second set of contacts  4  supported in the insulative housing  10 , and a metal shell  7  enclosing the insulative housing  10  and the contacts  13 ,  16 . Besides, a cable  5  having first and second sets of wires  51 ,  52  to electrically connect with the contacts  3 ,  4 . In order to provide a strong structure of the extension to USB plug  100 , an outer insulative cover  6  is over molded on a rear section of the insulative housing  2  together with the metal shell  7  and the cable  5 . The outer insulative cover  6  is adapted for being grasped by a user when the extension to USB plug  100  is used. Detail description of these elements and their relationship and other elements formed thereon will be detailed below. 
   Referring to  FIGS. 1-3 , the base portion  21  and the tongue portion  22  of the insulative housing  2  are integrally injecting molded as a unit one piece. The base portion  21  comprises a front engaging section  211  for engaging with the metal shell  7  and a rear terminating section  212  for the termination between the contacts  3 ,  4  and the wires  51 ,  52 . The engaging section  211  defines a plurality of cutouts  2110  in upper surface thereof adjacent to a front surface thereof for engaging with the metal shell  7 . Four first passageways  2111  and five second passageways  2112  are arranged in an upper row and a lower row to protrude through the engaging section  211  of the base portion  21  for receiving the first and second sets of contacts  3 ,  4 . The rear termination section  212  is of U-shape and comprises a pair of lateral walls  2121  and a transversal flat board  2122  connecting with the lateral wall  2121 . Four first channels  2123  and five second channels  2124  respectively aligning with the first and second passageways  2111 ,  2112  are respectively defined in lower and upper surfaces of the flat board  2122  for exposing tail portions of the first and second sets of contacts  3 ,  4  for soldering with the first and second wires  51 ,  52 . 
   The tongue portion  22  has a first supporting surface  221  lower than the upper surface of the base portion  21  and opposite second supporting surface  222  coplanar with lower surface of the base portion  22 . Four first passages  223  and five second passages  224  respectively recess downwardly from the first supporting surface  221  of the tongue portion  22  and are arranged in a front row and communicating with the first passageways  2111  in height direction and a rear row aligning with the second passageways  2112  in front-to-back direction. Four tip openings  225  are recessed inwardly from the front surface of the tongue portion  22  to communicate with the first passages  223  for receiving corresponding parts of the first set of contacts  3 . A pair of through holes  225  is defined in each first passage  223  to communicate with the first and second supporting surfaces  221 ,  222  and is arranged in the first passage  223  along front-to-back direction for pins of die to hold the first contacts  3  when molding to assure the relative position between the insulative housing  2  and the first contacts  3 . 
   Referring to  FIGS. 1-3  in conjunction with  FIGS. 4-6 , the first set of contacts  3  include four plug conductive contacts designated with numeral  31 ,  32 ,  33  and  34 . The four first contacts  3  are insertmolded with the insulative housing  2  when forming the insulative housing  2 . Thus, the insulative housing  2  has better intensity and assembly time is decreased. Each first contact  3  comprises a rear flat body section  35  received in the first passageways  2111  with rear tail section  350  thereof exposed in the first channel  2123 , a flat contacting section  36  embedded in the first passage  223  and coplanar with the first supporting surface  221 , a vertical connecting section  37  connecting with the body section  35  and the contacting section  36  and embedded in the tongue portion  22 , and a front L-shape tip end  38  embedded in the front opening  225  for preventing the upward deflection of the contacting section  36 . The four first contacts  3  are juxtaposed arranged and the contacting sections  36  thereof are nonelastic. The body section  35  is parallel to the contacting section  36  and is much longer than the contacting section  36 . 
   The additional second set of contacts  4  include two pairs of differential contacts  41  and a grounding contact  42 . The two pairs of differential contacts  41  are used for transferring/receiving high-speed signals, and the grounding contact  42  is disposed between the two pairs of differential contacts  41  for preventing cross-talk. Each differential contact  41  of each pair comprises an elastic contact portion  43  formed with an elastic contacting end  430  curved upwardly, a middle retention portion  44  formed with a pair of retention tabs  440  arranged along front-to-back direction and a flat tail portion  45  extending rearwardly from the retention portion  44 . The second contacts  4  are inserted into the insulative housing  2  from rear-to-front direction with the retention portions  44  interferentially engaging with inner walls of the second passageways  2112  via the retention tabs  440 , the elastic contact portions  43  partially received in the second passages  224  and the contacting ends  430  exposed beyond the first supporting surface  221  of the tongue portion  22 , and the tail portions  45  exposed in the termination section  212  and locating in the second channels  2124  for soldering with the second wires  52 . Thus, the differential contacts  41  and the grounding contact  42  are juxtaposed with respect to one another along the front-to-rear direction. The contacting sections  36  of the four first set of contacts  31 ,  32 ,  33  and  34  occupy a majority of length of the tongue portion  22  along the front-to-rear direction with respect to that of the contact portions  43  of the additional second set of contacts  4 . Meanwhile, the tail portions  45  are offset from the tail sections  350  of the first set of contacts  31 ,  32 ,  33  and  34  in a height direction perpendicular to the front-to-rear direction. The tail portions  45  are located under the tail sections  350  of the first set of contacts  31 ,  32 ,  33  and  34  to prevent electrical shorting. Besides, each contact portion  43  is cantileveredly received in the second passages  224  and protrudes upwardly beyond the supporting surface  121  so that the contact portion  43  is elastic and deformable when engaging with corresponding contacts of an extension to USB receptacle (not shown). The contact portions  43  and the contacting sections  36  are separated in the front-to-rear direction with no portion of them contacting one another. 
   The extension to USB plug  100  is compatible to existing standard USB receptacle. The geometric profile of the tongue portion  22  is same as that of the standard USB plug within an allowable tolerance. That is, length, width and height of the tongue portion  22  are substantially equal to those of the standard USB plug. An arrangement of the four first set of contacts  31 ,  32 ,  33  and  34  is compatible to that of the standard USB receptacle. The four first contacts  31 ,  32 ,  33  and  34  are for USB protocol to transmit USB signals. In detail, the four first set of contacts  31 ,  32 ,  33  and  34  are for power (VBUS) signal, −data signal, +data signal and grounding, respectively. So now, from assignment of each first contacts standpoint, different terminology are given to each of the four first set of contacts  31 ,  32 ,  33  and  34 , wherein the first contacts  31 ,  32 ,  33  and  34  are respectively named as power contact  31 , −data contact  32 , +data contact  33  and ground contact  34 . 
   Referring to  FIGS. 1-3  in conjunction with  FIGS. 7-10 , the metal shell  7  comprises a lower first half  71  and an upper second half  72  engaging with the first half  71  to form the whole metal shell  7 . The first half  71  comprises a front tube-shape mating frame  710  and a rear U-shape holding section  712  with opposite flanges  7120  each formed with a pair of tubers  7121  bending outwardly for engaging with locking holes  7220  of the second half  72  to secure the first and second halves  71 ,  72 . The front mating frame  710  defines two pairs of rectangular windows  7101  in upper and lower walls thereof and a rear locking opening  7102  in upper wall adjacent to the holding section  712 . The second half  72  is assembled to the rear holding section  712  of the first half  71  and comprises a n-shape front holding section  720  and a rear crimping section  721  for grasping the cable  5  to realize strain relief. The holding section  722  forms two pairs of locking holes  7220  in opposite lateral walls thereof and a bending tab  7221  bending from a front edge of upper wall thereof to lock into the locking opening  7102  of the first half  71 . After the metal shell  7  is assembled to the insulative housing  2  and the contacts  3 ,  4 , the mating frame  710  of the metal shell  7  touches other three sides of the tongue portion  22  except the first supporting surface  221 , thus, a receiving cavity  101  circumscribed by the mating frame  710  and the first supporting surface  221  is formed. The contacting sections  36  of the first set of contacts  3  and the contact portions  43  of the second set of contacts  4  are all exposed in the receiving cavity  101  surrounded by the mating frame  710  and first supporting surface  221  for mating with corresponding contact portions of a complementary connector. An arrangement of the metal shell  7  and the tongue portion  22  is also compatible with what of standard USB receptacle. 
   In the preferred embodiment of the present invention, the first set of contacts  3  are all formed of a metal sheet and separated form one another. It is also to be understood that, in other embodiments, the first contacts  31 ,  32 ,  33  and  34  can be conductive pads formed on a printed circuit board which is supported on the supporting surface  221  of the tongue portion  22 . These two options to make contacts are both viable in current industry. 
   The cable  5  comprises the four first wires  51  arranged in a lower row to be soldered with the tail sections  350  of the first set of contacts  3  and a pair of second wires  52  arranged in an upper row to be soldered with the tail portions  45  of the second set of contacts  4 . Each first wire  51  comprises an inner conductor  510  soldered with the tail section  350  and an outer jacket  512  enclosing the inner conductor  510 . Each second wire  52  comprises a pair of differential pair  521  each having the same structure as that of the first wire  51 , a grounding conductor  522 , and an outer jacket  523  enclosing the differential pair  521  and the grounding conductor  522 . The two differential pairs  521  of the second wires  52  are respectively soldered to the tail portions  45  of the differential contacts  41 , while the pair of grounding conductors  522  are both soldered to the single grounding contact  42 . The metal shell  7  is assembled of the insulative housing  2 , the contacts  3 ,  4  and the cable  5  as described above. Then, the outer insulative cover  6  is overmolded with the metal shell  7 , the cable  5 . 
   Under the non-USB protocol, the two pairs of differential contacts  41  transfer differential signals unidirectionally, one pair for receiving data and the other for transmission data. 
   In the preferred embodiment of the present invention, the number of the additional second set of contacts  4  is five which consists of two pairs of differential contacts  41  and a grounding contact  42  disposed between each pair of the differential contacts  41  as best shown in  FIGS. 1-3 . However, in alternative embodiments, the additional second set of contacts  4  can only comprise a pair of differential contacts for transmitting/receiving high-speed signals, and if necessarily, a grounding contact can be provided to be positioned on each lateral side of the pair of differential contacts. 
   It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the tongue portion is extended in its length or is arranged on a reverse side thereof opposite to the supporting side with other contacts but still holding the contacts with an arrangement indicated by the broad general meaning of the terms in which the appended claims are expressed.