Patent Publication Number: US-7588445-B2

Title: Stacked electrical connector with improved signal transmission

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an stacked electrical connector, and more particularly to stacked electrical connectors with improved signal transmission. 
   2. Description of Related Art 
   Universal Serial Bus (USB) is used widely in variety electric devices as a standard and simple interface. 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 mentioned above supports three data rates respectively as follows: 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). 
   However, as the development of electric industry, even the USB 2.0 can not satisfied the requirement of many electric devices. For example, 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. 
   However, these non-USB protocols, such as PCI Express which is useful for its higher possible data rates, a 26-pin connectors and wider card-like form factor limit the use of Express Cards, and SATA which uses two connectors, one 7-pin connector for signals and another 15-pin connector for power, 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, especially in a stacked electrical connector. Due to its clumsiness, the PCI Express and SATA connector can not adapt to the development trend of gently, thin, short and small size. 
   USB connector is soldered on a circuit board of an computer usually. The USB 2.0 A type connector according to USB-IF usually comprises an insulative housing with a tongue plate extending forwardly, four contacts retained in the insulative housing and a metal shield. Each contact has a contact portion extending to a lower side of the tongue plate and exposing out thereof flexibly. The contact portion presents as arc type and can move along a thickness direction of the tongue. The four contacts comprise a power contact, a ground contact, a − data contact and a + data contact. The − data contact and + data contact present as a pair of differential signal contacts which are located between the power contact and the ground contact. The metal shield encloses the tongue plate and forms a first receiving space for receiving a USB plug. 
   Hence, an stacked electrical connector which is based USB interface, but has a high signal transmission and a simple structure, is desired to overcome the disadvantage of the prior art. 
   BRIEF SUMMARY OF THE INVENTION 
   According to the present invention, a stacked electrical connector comprises a first mating interface with a plurality of first contacts retained therein. The first mating interface comprises a first receiving space with a first tongue received therein. The first contacts comprise a plurality of first elastic contacts and a plurality of first flat contact. Each first elastic contact has a securing portion fixed in the first mating interface, an elastic contact portion extending to the first tongue and a soldering portion. Each first flat contact has a retention portion retained in the first mating interface, a flat contact portion extending to the first tongue and a tail portion. The first tongue has a pair of opposite upper face and lower face. A second mating interface is stacked with the first mating interface along a thickness direction of the first tongue. A plurality of second contacts are retained in the second mating interface. The flat contact portions and the elastic contact portions are located at a same side of the upper face, and are arranged in two rows along a length direction of the first tongue. 
   According to another aspect of the present invention, a stacked electrical connector comprises a first mating interface comprising a first receiving space with a first tongue received therein. A geometric profile of the first tongue is substantially same as what of a standard USB 2.0 A type receptacle. A plurality of first contacts are retained in the first mating interface. The first contacts comprise a group of first type contacts and a group of second type contacts. Each first and second type contact has a contact portion. The contact portions of the first type contacts and the contact portions of the second portions are exposed in the first receiving space in an offset manner in both a front-to-back direction and a vertical direction perpendicular to said front-to-back direction. A second mating interface is stacked with the first mating interface along a thickness direction of the first tongue. A plurality of second contacts are retained in the second mating interface. 
   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 a perspective view of an stacked electrical connector according to a first embodiment of the present invention; 
       FIG. 2  is a view similar to  FIG. 1 , while taken from another aspect; 
       FIG. 3  is an exploded view of the stacked electrical connector shown in  FIG. 1 ; 
       FIG. 4  is a exploded view of an insulative housing of the stacked electrical connector; 
       FIG. 5  is a view similar to  FIG. 4 , while taken from another aspect; 
       FIG. 6  is a perspective view of an stacked electrical connector according to a second embodiment of the present invention; 
       FIG. 7  is an exploded view of the stacked electrical connector shown in  FIG. 6 ; 
       FIG. 8  is a perspective view of an stacked electrical connector according to a third embodiment of the present invention; 
       FIG. 9  is an exploded view of the stacked electrical connector shown in  FIG. 8 ; 
       FIG. 10  is a perspective view of an stacked electrical connector according to a fourth embodiment of the present invention; 
       FIG. 11  is a perspective view of an stacked electrical connector according to a fifth embodiment of the present invention; 
       FIG. 12  is an exploded view of the stacked electrical connector shown in  FIG. 11 ; 
       FIG. 13  is a perspective view of an stacked electrical connector according to a sixth embodiment of the present invention; 
       FIG. 14  is a perspective view of an stacked electrical connector according to a seventh embodiment of the present invention; 
       FIG. 15  is a perspective view of an stacked electrical connector according to a eighth embodiment of the present invention; 
       FIG. 16  is a perspective view of an stacked electrical connector according to a ninth embodiment of the present invention; 
       FIG. 17  is a perspective view of an stacked electrical connector according to a tenth embodiment of the present invention; 
       FIG. 18  is an exploded view of the stacked electrical connector shown in  FIG. 17 ; 
       FIG. 19  is a front elevational view of an stacked electrical connector according to a eleventh embodiment of the present invention; 
       FIG. 20  is a top plan view of the stacked electrical connector shown in  FIG. 19 ; 
       FIG. 21  is an exploded view of the stacked electrical connector shown in  FIG. 19 ; 
       FIG. 22  is a perspective view of an stacked electrical connector according to a twelfth embodiment of the present invention; 
       FIG. 23  is a perspective view of an stacked electrical connector according to a thirteenth embodiment of the present invention; 
       FIG. 24  is a perspective view of an stacked electrical connector according to a fourteenth embodiment of the present invention; 
       FIG. 25  is a partially exploded view of the stacked electrical connector shown in  FIG. 24 ; 
       FIG. 26  is another partially exploded view without shield of the  FIG. 24 ; 
       FIG. 27  is an exploded view of the stacked electrical connector shown in  FIG. 26 ; and 
       FIG. 28  is view similar to  FIG. 27 , while taken from another aspect. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   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. 
   Referring to  FIGS. 1-5 , an stacked electrical connector  100  according to a first embodiment of the present invention is disclosed. The stacked electrical connector  100  comprises an insulative housing  1 , a plurality of contacts  2  retained in the insulative housing  1 , a metal shield  3  enclosing the insulative housing  1  and a spacer  4  for fixing the contacts  2 . 
   The insulative housing  1  comprises a first housing  10  and a second housing  10  stacked with each other along a vertical direction. The first housing  10  has two first mating interfaces stacked with each other along the vertical direction. The structure of the first mating interface is similar to that of an existing standard USB 2.0 A type receptacle (not shown). The first mating interface comprises a first receiving space  101  with a first tongue  102  received therein. A geometric profile of the first tongue  102  is substantially same as that of a standard USB 2.0 A type receptacle. 
   The first tongue  102  has a pair of opposite upper face  1021  and lower face  1022 . The first tongue  102  defines five first passageways  1023  juxtaposed with respect to each other in a width direction of the first tongue  102 , and extending through the first housing  10  along a front-to-back direction. The first passageways  1023  are concaved inwardly from the upper face  1021 . The front-to-back direction is same with a length direction of the first tongue  102 . The vertical direction is same with a thickness direction of the first tongue  102 . A plurality of second and third passageways  1024 ,  1025  are concaved inwardly from the lower face  1022 . There are five second passageways  1024  juxtaposed with respect to each other in the width direction. The second passageways  1024  extend to a front end of the first tongue  102  and communicate with the first passageways  1023  respectively. There are four third passageways  1025  juxtaposed with respect to each other in the width direction. The third passageways  1025  extend to a rear end of the first housing  10 . The second and third passageways  1024 ,  1025  are arranged in two rows along the length direction and do not communicate with each other. 
   A clapboard  13  extends forwardly between two first mating interfaces for dividing them. The first housing  10  comprises a top wall  104 , a bottom wall  105  and a pair of side walls  106  therebetween. The first receiving spaces  101  of the two first mating interface are formed between the top wall  104 , bottom wall  105  and side walls  106 . Two side walls  106  are located at outsides of first tongue  102  respectively, and each side wall  106  defines an opening  1061  corresponding to each first receiving space  101 . A projection  1051  projects downwardly from the bottom wall  105 . The bottom wall  105  has a rib  1052  extending downwardly and located at a front position of the projection  1051 . 
   The second housing  11  comprises a lower wall  110  and two side walls  111 . The lower wall  110  and two side walls  111  define a second mating interface therebetween. The second mating interface has a second receiving space  112  with a second tongue  113  received therein. The second receiving space  112  is wider than the first receiving space  101 . The second mating interface presents as crisscross shape and is a standard External Serial ATA interface. The second housing  11  comprises a base portion  114 . The second tongue  113  extends forwardly from the base portion  114  and comprises a pair of opposite upper and lower faces  1131 ,  1132 . A plurality of contact passageways  1133  are concaved inwardly from the upper face  1131 . The second housing  11  defines a pair of apertures  1110  extending backwardly from a front end thereof and formed between the side wall  111  and lower wall  110 . Each side wall  111  has a protrusion  111  extending outwardly and a slot  1112  extending along the front-to-back direction at an upper position thereof. The slot  1112  engages with the projection  1051  for fastening the first and second housing  10 ,  11  together. The side walls  111  present as step shape at a top position to abut against the rear end of the rib  1052  for preventing the first housing  10  from moving backwardly. 
   The insulative housing  1  of the stacked electrical connector  100  in the first embodiment is divided into two parts. In nature, the insulative housing  1  can be formed integrally. The first and second mating interfaces are formed in an integral insulator for assembling conveniently. 
   The contacts  2  comprise a plurality of first contacts  20  retained in the first mating interface and a plurality of second contacts  21  retained in the second mating interface. 
   The first contacts  20  are divided in two groups retained in two mating interfaces of the first housing  10 . Two groups of the first contacts  20  have same structure, so we will describe one group of the first contacts  20  in follows. The first contacts  20  comprise two types of contacts, wherein one type contacts comprise four first elastic contacts  201 , and another type contacts comprise five first flat contacts  202 . The first elastic contacts  201  are adapted for USB protocol and an arrangement of the first elastic contacts  201  is compatible to a standard USB A type plug. Each first elastic contacts  201  has an elastic contact portion  2010  extending to a lower side of the first tongue  102 , a securing portion  2011  engaging with the third passageways  1025 , and a soldering portion  2012  extending out of the insulative housing  1 . The elastic contact portions  2010  are cantilevered and accommodated in the third passageways  1025  and protrude beyond the lower face  1022 , so that the elastic contact portion  2010  is deformable along the thickness direction. 
   The second contacts  202  comprise two pairs of differential signal contacts  2020  and a grounding contact  2021 . The two pairs of differential signal contacts  2020  are used for transferring/receiving high-speed signals, and the grounding contact  2021  is disposed between the two pairs of differential signal contacts  2020  for preventing cross-talk. Each differential contact  2020  of each pair has a first flat contact portion  2022  extending to a lower side of the first tongue  102 , a first connecting portion  2023  extending upwardly from a front end of the first flat contact portion  2022 , a first retention portion  2023  extending backwardly from the first connecting portion  2023 , and a first tail portion  2025  extending from the connecting portion  2023 . The grounding contact  2021  is of the same configuration as the differential contact  2020 . So the grounding contact  2021  comprises a second flat contact portion  2026 , a second connecting portion  2027  extending upwardly from a front end of the second flat contact portion  2026 , a second retention portion  2028  extending backwardly from the second connecting portion  2027  and a second tail portion  2025  located between the first tail portions  2029  of each pair. 
   When the differential signal contacts  2020  are inserted into first mating interface, the retention portions  2024 ,  2028  are fixed in the first passageways  1023 , and the connecting portions  2023 ,  2027  cover a front end of the first tongue  102 , and the flat contact portions  2022 ,  2026  are received in the second passageways  1024  and juxtaposed with each other in the width direction. The flat contact portions  2022 ,  2026  and the retention portion  2024 ,  2028  are parallel to each other wherein the flat contact portions  2022 ,  2026  are much shorter than the retention portions  2024 ,  2028 . The flat contact portions  2022 ,  2026  are perpendicular to the tail portions  2025 ,  2029 . 
   Meanwhile, the flat contact portions  2022 ,  2026  are located forward the elastic contact portions  2010  of the elastic contacts  201 . The flat contact portions  2022 ,  2026  are arranged at a front row, while the elastic contact portions  2010  are arranged at a rear row. Because the second and third passageways  1024 ,  1025  are discontinuous in the front-to-back direction, the flat contact portions  2022 ,  2026  and the elastic contact portions  2010  will not contact with each other and have a distance therebetween for preventing two types signal transmission from confusing. The flat and elastic contact portions  2022 ,  2026  and  2010  are arranged at a same side of the upper face  1021  and located at different rows for employing the space of the lower face  1022  adequately, and decreasing the crosstalk between adjacent contacts  2 . 
   In addition, the contact portions  2010 ,  2022  and  2026  are located at different plane along the thickness direction of the first tongue  102 , wherein the elastic contact portions  2010  are elastic and protrude beyond the lower face  1022 , while the flat contact portions  2022 ,  2026  are received in the second passageways  1024 , for connecting with two different plug (not shown) conveniently. When a USB 2.0 A type plug (not shown) inserts into the first receiving space  101 , the plug will electrically connect with the elastic contact portions  2010 , and not contact the flat contact portions  2022 ,  2026 . When another plug (not shown) inserts into the first receiving space  101 , it will contact with two different contact portions  2010 ,  2022  and  2026  effectively for ensuring the signal transmission. 
   The second contacts  21  are inserted into the second mating interface from a rear end of the second housing  11 . Each second contact  21  has a fixing portion  210  retained in the base portion  114 , a mating portion  211  extending into the second receiving space  112 , and a soldering tail  212  bending downwardly from the fixing portion  210 . The mating portions  211  are all received in the contact passageways  1133  of the upper face  1131 . The spacer  4  is assembled in a lower position of the second housing  11 . A plurality of holes  41  extend through the spacer  4  for fixing the second contacts  21 . 
   The metal shield  3  comprises a front shield  30  covering a front face and two sides of the insulative housing  1 , a rear shield  31  covering a top face and the rear end of the insulative housing  1 , and two first inner shields  32  retained in the first receiving space  101 , and a second inner shield  33  retained in the second receiving space  112 . 
   The front shield  30  has a front wall  300  and two side walls  301 . The front wall  200  defines a plurality of openings  302  corresponding to each mating interface. Each side wall  301  has a number of first spring arms  303  extending forwardly, and a plurality of cutouts  304  at a rear position thereof. A pair of mounting legs  305  extend downwardly from each side wall  301 . The rear shield  31  has a top wall  310  and a rear wall  311 . A pair of latches  312  extend forwardly from each side of the rear wall  311  for locking with the cutouts  304 . 
   The first inner shield  32  encloses the first tongue  102 , and comprises a plurality of second spring arms  320  extending inwardly from each wall thereof for engaging with the plug, and two flanges  321  extending outwardly from a front end thereof for engaging with the front shield  30  for grounding. When the plug inserts into the first receiving space  101 , the plug abuts against the second spring arms  320 . The second spring arms  320  move outwardly and through the openings  1061  for contacting with the first spring arms  303  for grounding. The second inner shield  33  is assembled in the second receiving space  112  along the apertures  1110  and encloses the second tongue  113 . The second shield  33  comprises two locking holes  330  locking with the protrusions  1111  of the second housing  11 , and a pair of third spring arms  331  at upper and lower walls thereof for abutting against a corresponding plug (not shown). A pair of flanges  332  extend outwardly from a front end of the second inner shield  33  to contact with the front shield  30  for grounding. 
   As fully described above, the stacked electrical connector  100  of the present invention in the first embodiment adds two pairs of differential signal contacts  2020  and a grounding contact  2021  relative to the standard USB 2.0 connector as stacked with a Serial ATA connector. Thereby, the stacked electrical connector  100  has a simple structure, and the speed of signal transmission is increased as adding the two pairs differential signal contacts  2020 , which is adapted to the trend of development of the electrical industry. 
   Referring to  FIGS. 6 and 7 , a stacked electrical connector according to a second embodiment of the present invention is disclosed. The difference between the stacked electrical connectors of the first and second embodiments is that first, an insulative housing  5  is molded integrally; second, there is only a first mating interface  50  which is similar to the first mating interface in the first embodiment; third, the second mating interface  51  is a standard USB 2.0 A type interface. The second mating interface  51  has a second tongue  510 . Four USB 2.0 contacts extend to a lower side of the second tongue  510  for electrically connect with a USB 2.0 A type plug (not shown). The second mating interface  51  is located at top of the first mating interface  50 . 
   Referring to  FIGS. 8 and 9 , an stacked electrical connector according to a third embodiment of the present invention is disclosed. The difference between the stacked electrical connectors of the first and third embodiments is that first, an insulative housing  6  is molded integrally; second, there is only a first mating interface  60  which is similar to the first mating interface in the first embodiment; third, the second mating interface  61  is a standard High Digital Multimedia Interface (HDMI). The second mating interface  61  has a D-shaped receiving space and a second tongue  610  received therein. A plurality of flat contacts extend to two sides of the second tongue  610  for electrically contacting with a HDMI plug (not shown). 
   Referring to  FIG. 10 , an stacked electrical connector according to a fourth embodiment of the present invention is disclosed. The difference between the stacked electrical connectors of the first and fourth embodiments is that: first, a second mating interface  71  is located at an upper position of an insulative housing  7 , while a first mating interface  70  which is similar to that of the first embodiment is located at a lower position of the insulative housing  7 ; second, the second mating interface  71  is a standard DIN connector. The second mating interface  71  comprises an annular recess with a cylindrical portion  710  received therein. The cylindrical portion  710  defines a plurality of passageways  711  extending through the insulative housing  7 . A plurality of DIN contacts extend to the passageways  711 . 
   Referring to  FIGS. 11 and 12 , an stacked electrical connector according to a fifth embodiment of the present invention is disclosed. The difference between the stacked electrical connectors of the first and fifth embodiments is that an insulative housing  8  comprises a frame  81 , a first housing  80  and a second housing  82  fixed to the frame  81 . The frame  81  defines a pair of upper and lower space  810  for receiving the first and second housing  80 ,  82  respectively. The second housing  82  comprises a first mating interface  820  which is similar to that of the first embodiment. While the first housing  80  comprises a second mating interface  800  protruding forwardly and presenting as D shape. The second mating interface  800  is a standard D-SUB interface. Each first and second mating interface  820 ,  800  has a mating face mating with a corresponding plug (not shown). The mating faces of the first and second mating interface  820 ,  800  are arranged in an offset manner in both length direction and the thickness direction. In addition, the second mating interface  800  defines a plurality of passageways  801  for receiving D-SUB contacts  802 . 
   Referring to  FIG. 13 , an stacked electrical connector according to a sixth embodiment of the present invention is disclosed. The difference between the stacked electrical connectors of the first and sixth embodiments is that: first, a first mating interface  90  which is similar to that of the first embodiment is located at a lower position of an insulative housing  9 , while a second mating interface  91  is located at an upper position; second, the second mating interface  91  is a standard USB B type interface. The second mating interface  91  comprises a second tongue  910 . Two pairs of second elastic contacts  911  extend to upper and lower faces of the second tongue  910  respectively. 
   Referring to  FIG. 14 , an stacked electrical connector according to a seventh embodiment of the present invention is disclosed. The difference between the stacked electrical connectors of the first and seventh embodiments is that a second mating interface  122  is a standard Displayport interface. A second tongue  1221  of the second mating interface  122  presents as a reverse U shape. A plurality of second contacts  1222  extend to an upper face and a lower face of the second tongue  1221  for electrically connecting with a standard Displayport plug (not shown). There is only a first mating interface  121  which is similar to that of the first embodiment stacked with the second mating interface  122  at an upper position. 
   Referring to  FIG. 15 , an stacked electrical connector according to a eighth embodiment of the present invention is disclosed. The difference between the stacked electrical connectors of the first and eighth embodiments is that a second mating interface  132  is a standard IEEE 1394 A type interface. There are two first mating interfaces  131  stacked with the second mating interface  132  and located at a lower position. And referring to  FIG. 16 , a second mating interface  142  in a ninth embodiment is a standard IEEE 1394 B type interface. And there are two first mating interfaces  141  stacked with the second mating interface  142  and located at a lower position. 
   Referring to  FIGS. 17 and 18 , an stacked electrical connector  15  according to tenth embodiment of the present invention is disclosed. In the tenth embodiment, the stacked electrical connector  15  comprises an insulative housing  151 , two groups of contacts  152  which are similar to the first contacts  20  of the first embodiment retained in the insulative housing  151 , an outer shield  153  enclosing the insulative housing  151 , a rear shield  154  covering a rear end of the insulative housing  151 , an inner shield  155  retained in the insulative housing  151  and a spacer  156  for fixing the contacts  152 . There are two stacked mating interfaces  1511  which are all similar to the first mating interface of the first embodiment and integrally molded in the insulative housing  151 . A clapboard  157  extends forwardly between two mating interfaces  1511 . Each mating interface  1511  comprises a tongue plate  1512  extending forwardly and parallel to the clapboard  157 . Each group contacts  152  have same structure with the first contact  20 , and are arranged on each tongue plate  1512  same as the arrangement of the first contact  20 . The spacer  156  defines a plurality of holes  1561  for receiving a lower portion of each contact  152 . The inner shield  155  encloses the clapboard  157  and locking with the outer shield  153 . The inner shield  155  comprises two pairs of spring arms  1551  extending into each mating interface  1511  for engaging with a corresponding plug (not shown). 
   Referring to  FIGS. 19-21 , an stacked electrical connector  16  according to eleventh embodiment of the present invention is disclosed. The stacked electrical connector  16  is approximately same as the stacked electrical connector  15  in the tenth embodiment. The difference is that a soldering portion  163  of each contact  161  is parallel to a contact portion  162  thereof. The stacked electrical connector  16  is soldered to a circuit board  17  vertically. 
   Referring to  FIGS. 22 and 23 , two stacked electrical connector  18 ,  19  according to twelfth and thirteenth embodiment of the present invention are disclosed. The stacked electrical connector  18  comprises three mating interfaces  181 , while the stacked electrical connector  19  comprises four mating interfaces  191 . All mating interfaces  181 ,  191  are similar to the first mating interface in the first embodiment. 
   Referring to  FIGS. 24-28 , a stacked electrical connector  22  according to a fourteenth embodiment of the present invention are disclosed. The outside of the stacked electrical connector  22  is approximately same to the stacked electrical connector  15  when the stacked electrical connector  22 ,  15  are assembled together. The stacked electrical connector  22  comprises a divided housing  220  which is different from the insulative housing  151  in the tenth embodiment, two groups of contacts  223  which are similar to that in the tenth embodiment are retained in the divided housing  220 , an outer shield  226  enclosing the divided housing  220 , an rear shield  227  covering a rear end of the divided housing  220 , and a spacer  228  positioned at a lower portion for fixing the contacts  223 . 
   The divided housing  220  comprises an upper housing  221 , a lower housing  222  positioned at a lower position of the upper housing  221  and a top cap  229  fixed at a top position of the upper housing  221 . The upper housing  221  comprises a first mating interface with a first tongue  2212  extending forwardly form a top end thereof, and a clapboard  2213  parallel to the first tongue  2212  and located at a lower position thereof. An inner shield  225  encloses the clapboard  2213  and connects with the outer shield  226 . The first tongue  2212  defines a plurality of first passageways  22125  at a top side thereof, a plurality of second and third passageways  22124 ,  22123  at a lower side thereof and arranged in two rows along a length direction of the first tongue  2212 . The upper housing  221  comprises a pair of embosses  22112  projecting upwardly at a top end thereof, and a swallow-tailed projection  22114  at a lower end thereof. The top cap  229  defines a pair of holes  2291  engaging with the embosses  22112 . 
   The lower housing  222  comprises a second mating interface with a second tongue  2222  extends forwardly from a top end of the lower housing  222 . The second tongue  2222  is similar to the first tongue  2212 , and the second mating interface is similar to the first mating interface. The lower housing  222  comprises a pair of block  22215  extending upwardly from two sides thereof. Each block  22125  defines a recess  22124  for engaging with the swallow-tailed projection  22114  of the upper housing  221 . A. 
   Each group of contacts  223  is similar to the first contacts  20  in the first embodiment and transmit same signal with the first contacts  20 . Each group of contacts  223  comprises four elastic contacts  2231  and five flat contacts  2232 . We will describe one group contacts  223  positioned in the upper housing  221  for example. Each elastic contact  2231  comprises an elastic contact portion  2233  extending to the third passageways  22123  and protruding beyond the first tongue  2212 , a securing portion  2234  retained in the upper housing  221  and a soldering portion  2235  extending out of the divided housing  220 . Each flat contact  2232  comprises a flat contact portion  2236  extending to the second passageways  22124 , a retention portion  2237  received in the first passageways  22125  and a tail portion  2238  extending out of the divided housing  220 . The flat contact portions  2236  and the retention portion  2237  are parallel to each other, and wherein the flat contact portions  2236  are much shorter than the retention portions  2238 . The flat contact portions  2236  and the elastic contact portions  2233  are arranged in two row along the length direction of the first tongue  2212  and do not contact with each other. 
   After the contacts  223  assembled in the divided housing  220 , the top cap  229  covers the top end of the upper housing  221  and presses the retention portions  2237  for preventing the flat contacts  2232  from moving upwardly. The spacer  228  defines a plurality of hollows  2282  for fixing all contacts  223 . Another group contacts  223  are arranged on the second tongue  2222  same as the arrangement of said one group contacts  223  above. 
   As fully described above, different embodiments of the present invention have been disclosed, but these are only some preferable embodiments used continually in fact, and such as a standard interface of POF connector, Module jack etc, can be stacked with a mating interface which is similar to the first mating interface in the first embodiment also for improving speed of signal transmission thereof, if it is necessary. All stacked electrical connectors described above have simple structure which is adapted to development trend of the electrical industry, and improve the speed of signal transmission thereof. 
   It is to be understood, however, that even though numerous, characteristics and advantages of the present invention have been set fourth in the foregoing description, together with details of the structure and function of the invention, the disclosed is illustrative only, and changes may be made in detail, especially in matters of number, 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.