Abstract:
A plug assembly having a body portion, a plug housing that provides a mounting for AC prongs that creates a cavity therewithin, and a PCB located in the cavity. A pair of contact terminals are mounted on the PCB in a predetermined position so as to create a spring-loaded electrical contact with a corresponding one of the AC prongs during assembly. The present invention reduces the bulkiness, optimizes the packaging size, and reduces the profile of the plug assembly by using the cavity to house the PCB, thereby providing a reduction or elimination of the need to mount components within the body portion. The present invention eliminates the need to use flexible wires, springs, or direct soldering between the AC prongs and the circuitry on the PCB, thereby making assembly quicker and easier through use of the spring loaded contact terminal.

Description:
FIELD OF INVENTION 
     The present invention relates to electrical plug assemblies, and more particularly to an electrical plug assembly having a plug housing including a printed circuit board mounted therein, and spring-loaded contact terminals mounted on the printed circuit board to provide an electrical connection between the prongs of the plug housing and the circuit on the printed circuit board. 
     BACKGROUND OF THE INVENTION 
     Modern portable electronic devices, such as cellular phones, typically are powered by a DC power source, usually delivered by rechargeable batteries installed in the device. Plug assemblies, such as plug chargers, are typically used to couple these portable electronic devices to an AC power source in order to provide the required voltages to recharge the batteries. Various non-portable electrical devices typically are powered only from an AC power source, usually delivered through a plug connected to a wall receptacle or socket, but require that this AC power be converted into the required DC voltages for powering these devices. Electrical plug assemblies, such as plug adapters, are often used to convert the AC power to provide the required DC voltages to these electrical devices. The modern technology trend is towards higher density and lower profile electrical devices. A common disadvantage of known plug assemblies is that these assemblies are bulky and inefficient in the use of available space. There is thus a need to optimize the packaging size of plug assemblies used with electrical devices. 
     Plug assemblies typically include a body portion and a plug housing having an electrical plug for enabling the plug assembly to be connected to an AC power source through a wall receptacle or socket. Electrical plugs throughout the world include various configurations of AC prongs or pins (hereinafter referred to as prongs) that extend outwardly from the plug housing and are shaped to enable electrical and mechanical connection to the AC wall receptacle or socket. Various plug housings provide a mounting for the AC prongs which creates a hollow portion or cavity within the plug housing. The European plug standards CEE 7/16 and EN50075, for example, specify the use of an extended plastic base to house a portion of the AC prongs, thereby creating a hollow cavity portion. Various known plug assemblies, such as plug chargers for electrical devices having batteries, house circuitry usually mounted on a printed circuit board (PCB) positioned within a body portion. Typically, flexible wires are used to electrically couple the AC prongs to the circuit on the PCB. A drawback of such plug assemblies is that the cavity of the plug housing is not used to house this circuitry, or to reduce the amount of circuitry mounted on the PCB positioned in the body portion. 
     For plug assemblies that include a plug housing having a cavity portion, the body portion is bulkier than necessary and space is wasted within the plug housing. As a consequence, the packaging size of such plug assemblies is not optimized and the material cost is higher than necessary. 
     In addition, known means of providing electrical contact between the AC prongs and the circuit on a PCB to be powered by the AC power source is through the use of flexible wires, extended copper springs, or the direct soldering of the prongs to the PCB. The use of such wires, springs, or direct soldering makes assembly more difficult than necessary. What is needed is a structure that creates a secure electrical and mechanical contact between the AC prongs and the PCB within the plug assembly that can be assembled quickly and easily and which optimizes packaging size and reduces the plug assembly&#39;s profile. What is also needed is a structure that allows the PCB electrical contacts to be closer to the AC prongs in order to further optimize packaging size. 
     SUMMARY OF THE INVENTION 
     The present invention solves the above identified problems of known devices by providing a plug assembly wherein a PCB is located in the hollow portion of the plug housing and the AC prongs are electrically connected to the PCB using spring loaded contacts mounted on the PCB. 
     Broadly stated, the present invention is directed to a plug assembly including a body portion and a plug housing connected thereto and having a plurality of AC prongs extending therefrom shaped to enable the plug assembly to be connected to an AC female outlet, the plug housing providing a mounting for the plurality of AC prongs and creating a cavity in the plug housing, the plug assembly comprising a first printed circuit board mounted in the plug housing and extending into the cavity, and a pair of contact terminals mounted on the first printed circuit board, each contact terminal in a predetermined position so as to create a spring-loaded electrical contact with a corresponding one of the AC prongs. 
     In one embodiment of the present invention, the first PCB is mounted to the body portion of the plug assembly. For a second embodiment, the plug assembly has a second printed circuit board mounted in the body portion operatively connected to the first printed circuit board. For a third embodiment, the first printed circuit board has one portion mounted in the body portion and a second portion mounted in the plug housing. In anther embodiment of the plug assembly of the present invention, a second printed circuit board is mounted in the body portion and extended into the plug housing, wherein the first printed circuit board is operatively connected to the second printed circuit board. In yet another embodiment, a second printed circuit board is mounted in the body portion, wherein the first printed circuit board extends into the body portion and is operatively connected to the second printed circuit board. 
     The present invention also provides a preferred and two alternate contact terminals, any of which can be used with any of the plug assembly embodiments described herein. The present invention also provides a corresponding method for assembling the plug assembly. 
     The present invention reduces the bulkiness, optimizes the packaging size, and reduces the profile of the plug assembly by using the hollow area of a plug housing to house a PCB having components mounted thereon, thereby providing a reduction or elimination of the need to mount components within the body portion of the plug assembly. A further advantage of the present invention is that it eliminates the need to use flexible wires, springs, or direct soldering between the AC prongs and the circuitry on the PCB, thereby making assembly of the plug assembly quicker and easier through use of a spring loaded contact terminal. A further advantage of the present invention is that it reduces the overall material cost of the plug assembly as a result of the optimized packaging size. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The forgoing aspects and the attendant advantages of the present invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an exploded view of a preferred embodiment of the plug assembly of the present invention showing the plug housing in phantom for clarity; 
     FIG. 2A is a front perspective view of the contact terminal of the plug assembly embodiment of FIG. 1; 
     FIG. 2B is a rear perspective view of the contact terminal of the plug assembly embodiment of FIG. 1; 
     FIG. 2C is an enlarged front perspective view of the contact terminal of the plug assembly embodiment of FIG. 1; 
     FIG. 3 is an exploded view of a first alternate embodiment of the plug assembly of the present invention showing the plug housing in phantom for clarity; 
     FIG. 4A is a front perspective view of the contact terminal of the plug assembly embodiment of FIG. 3; 
     FIG. 4B is a rear perspective view of the contact terminal of the plug assembly embodiment of FIG. 3; 
     FIG. 4C is an enlarged rear perspective view of the contact terminal of the plug assembly embodiment of FIG. 3; 
     FIG. 5 is an exploded view of another alternate embodiment of the plug assembly of the present invention; 
     FIG. 6 is an exploded view of the embodiment of the plug assembly of FIG. 5, showing the plug housing and the body portion in phantom for clarity; 
     FIG. 7 is an enlarged elevational view of an exemplary PCB of the plug assembly of FIG. 5, showing contact terminals according to the present invention; 
     FIG. 8 is a perspective view of the embodiment of the plug assembly of FIG. 5, showing the plug housing and the body portion connected in the operative position and in phantom for clarity; 
     FIG. 9 is an isometric view of the contact terminal of the plug assembly of FIG. 5; 
     FIG. 10 is an exploded view of an embodiment of the plug assembly of the present invention showing the plug housing, printed circuit board, and exemplary battery all in phantom; 
     FIG. 11 is an exploded view of an embodiment of the plug assembly having AC prongs conforming to a U.S. plug standards where the plug housing and body portion are both shown in phantom for clarity; and 
     FIG. 12 is a perspective view of the embodiment of the plug assembly of FIG. 11, showing the plug housing and the body portion connected in the operative position and in phantom for clarity. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now be described in more detail with reference to FIGS. 1-10. FIG. 1 is an exploded view of an embodiment of the plug assembly of the present invention. Plug assembly  10  has a body portion  11  having a first printed circuit board  16  mounted therein and a plug housing  12  (shown in phantom in FIG. 1 for clarity). In an alternate embodiment of the present invention, e.g., as shown in FIG. 5, plug assembly  30  also includes a second printed circuit board  38  operatively connected to the first printed circuit board  36 . In the preferred embodiment, printed circuit board  13  in FIG. 1 comprises one portion  16   b  mounted to the body portion  11  and a second portion  16   a  mounted in the plug housing  12 . In the embodiment of FIG. 5, as described below, the second printed circuit board  38  is mounted in the body portion  11  and operatively connected to a first printed circuit board  36  mounted in the plug housing  12 . In the embodiment of FIG. 8, as described below, the second printed circuit board  38  extends from the body portion into the plug housing  12  and is operatively connected to the first printed circuit board  36  mounted in the plug housing. 
     In FIG. 1, the plug housing  12  and body portion  11  are shaped to enable secure mechanical contact therebetween. Plug housing  12  has a pair of AC prongs  18 ,  19  mounted therein and extending therefrom. AC prongs  18 ,  19  are shaped to enable electrical and mechanical connection to an outlet or receptacle of a commercial AC power source (not shown). As seen in FIG. 1, a portion of each prong  18 ,  19  extends into plug housing  12 . In the exemplary embodiment of FIG. 1, plug housing  12  conforms to the applicable European plug standards CEE 7/16 and EN50075. In another embodiment shown in FIGS. 11 and 12, U.S. type prongs are shown in a plug housing conforming to the applicable plug standards UL 498 and UL 1310. The present invention, however, is not limited to the use of a European or U.S. plug. Any suitably shaped prongs and plug housing may be used. 
     In FIG. 1, plug housing  12  provides a mounting for the AC prongs  18 ,  19  and creates a hollow “cavity” portion  17  within the plug housing  12 . A pair of contact terminals  100 ,  101  are mounted to the printed circuit board  13  at a predetermined position so as to create a spring-loaded electrical contact with a corresponding one of the AC prongs  18 ,  19 . For the preferred embodiment of the plug assembly of FIG. 1, one PCB portion  16   b  is mounted to the body portion  11  and AC prongs  18 ,  19  are mounted to the plug housing  12  to enable the contact terminals  100 ,  101  on the other PCB portion  16 a to have spring-loaded contact with the AC prongs  18 ,  19 ; such that the other PCB portion  16   a  is within the cavity portion  17  when the body portion  11  and plug housing  12  are joined together during assembly. 
     The present invention overcomes the drawbacks of the known plug assemblies by utilizing the hollow cavity portion  17  to accommodate the first circuit board  16 . Cavity portion  17  provides space to house circuitry that would otherwise be located in the body portion  11  or to reduce the amount of circuitry in the body portion  11 , thereby reducing the size and bulkiness of the plug assembly  10 . The contact terminals  100 ,  101  of the present invention provide a spring-loaded contact with a corresponding one of the AC prongs  18 ,  19  which further reduces the size of the plug assembly by providing a contact with the PCB that is closer to the AC prongs  18 ,  19 . The plug assembly of the present invention also makes assembly simpler and easier by providing for slidable assemby and eliminating the need for wires to connect to the AC prongs  18 ,  19 . The pair of contact terminals  100 ,  101  and the spring-loaded contact are described in more detail in FIGS. 2A -2C. 
     FIGS. 2A and 2C show front perspective views of one of the contact terminals  100 ,  101  of the preferred embodiment of the plug assembly in FIG. 1, the contact terminals  100 ,  101  being identical. FIG. 2B is a rear perspective view of one of the contact terminals  100 ,  101 . Contact terminals  100 ,  101  includes a first portion  150  and a contact spring member  110 . Contact terminals  100 ,  101  are made of a conductive material, preferably copper. First portion  150  has a pair of support legs  130 ,  160  and a lateral portion  120 . The lateral portion  120  extends laterally between the pair of support legs  130 ,  160 . Lateral portion  120  couples spring member  110  to the support legs  130 ,  160 . Contact spring member  110  includes a vertical portion  170  and a blade portion  180 , both being flexible portions. Vertical portion  170  is disposed on the lateral portion  120  and extends vertically therefrom. Blade portion  180  is coupled to the vertical portion  170  and extends therefrom at a predetermined angle. 
     In FIG. 1, each of the contact terminals  100 ,  101  is mounted to the first circuit board  16 . Means for securely electrically and mechanically connecting the contact terminals  100 ,  101  to the first circuit board  16  are provided; such means being known to one of ordinary skill in the art. In the operative position, with the support legs  130 ,  160  and lateral of first portion  120  of first portion  150  secured to the first circuit board  16 , the blade portion  180  of contact spring member  110  flexibly contacts the corresponding one of the AC prongs  18 ,  19 . The blade portion  180  and vertical portion  170  flexible couple the corresponding one of the AC prongs  18 ,  19  to the first portion  150  mounted on first circuit board  16 , providing a secure spring-loaded mechanical and electrical contact between the corresponding on of AC prongs  18 ,  19  and the contact terminal  100 ,  101 . As a result, the pair of contact terminal  100 ,  101  securely electrically connects the corresponding one of AC prongs  18 ,  19  to the first circuit board  16  in the plug housing  12 . 
     An exemplary embodiment of the plug assembly of the present invention will now be described in more detail with reference to FIGS. 3-4C. FIG. 3 is an exploded view of a first alternate exemplary embodiment of the plug assembly  20  of the present invention showing the plug housing in phantom for clarity. The embodiment of FIG. 3 includes alternate contact terminals  200 ,  201  to provide a snap fitting to a corresponding one of the AC prongs  18 ,  19 . FIG. 4A is a front perspective view of one of the contact terminals  200 ,  201  of FIG.  3 . FIGS. 4B and 4C are rear perspective views of one of the contact terminals  200 ,  201  of FIG.  3 . Contact terminals  200 ,  201  are identical and made of a conductive material, preferably copper. For plug assembly embodiment  20 , contact terminals  200 ,  201  are mounted to the first printed circuit board  16  and provide electrical contact thereto. 
     As shown in FIGS. 4A-4C, each one of the contact terminals  200 ,  201  includes contact spring member  210  coupled to a first portion  250  and extending therefrom. Contact spring member  210  has a plurality of contact members  220  forming an opening  260 . Preferably, contact members  220  are flexible tabs. First portion  250  includes a first base member  230 , a second base member  270 , and a lateral member  240 . First base member  230  is coupled to contact spring member  210  and spaced apart from second base member  270 . Lateral member  240  extends between first base member  230  and second base member  270 . 
     During assembly of the plug assembly  20 , a corresponding one of the prongs  18 ,  19  is extended into the opening  260  and flexibly engages contact members  220  of contact spring member  210  that is oriented in a direction as shown in the exploded view of FIG.  3 . Operatively connected, contact members  220  provide a flexible spring action to provide secure mechanical snap fitted contact to a corresponding one of the AC prongs  18 ,  19 . 
     First printed circuit board  16  has a first surface  280  and an opposite second surface (not shown in FIG. 3, but facing into the page). Lateral member  240  separates the first base member  230  and second base member  270  by a distance such that first base member  230  flexibly connects to a first surface  280  and second base member  270  flexibly connects to the second surface. In this way, contact terminals  200 ,  201  are clipped to the first printed circuit board  16  to provide secure electrical and mechanical connection therewith. Means are provided on the first printed circuit board  16  to provide the electrical and mechanical connection to each of the contact terminals  200 ,  201 , such means are well known to one of ordinary skill in the art. 
     FIG. 5 is an exploded view of another alternate embodiment of the plug assembly of the present invention. FIG. 6 is an exploded view of the embodiment of the plug assembly of FIG. 5, showing the plug housing and the body portion in phantom for clarity. Plug assembly  30  has a body portion  34  (shown in the operative position in FIG. 8) comprised of case portions  35  and  37 , and a plug housing  32  (shown in phantom in FIG.  6  and FIG.  8 ). Body portion  34  has a second printed circuit board  38  mounted therein. The second printed circuit board  38  is operatively connected to a first printed circuit board  36 . Contact terminals  300 ,  301  are mounted on first printed circuit board  36 . FIG. 7 is an enlarged elevational view of an exemplary first printed circuit board  36  of the plug assembly of FIG. 5, showing contact terminals  300 ,  301 . 
     FIG. 8 is a perspective view of the embodiment of the plug assembly of FIG. 5, showing the plug housing and the body portion connected in the operative position and in phantom for clarity. The two prongs  18 ,  19  extend outwardly from the plug housing  32  to provide connection to an outlet or receptacle of an AC power source (not shown). A portion of prongs  18 ,  19  extends into plug housing  32 . Plug housing  32  has a cavity portion  31  (seen best in FIG. 6) therein. As shown in the operative position in FIG. 8, first printed circuit board  36  is within the cavity portion  31  and extends into body portion  11  and is operatively connected to the second circuit board  38 . 
     FIG. 9 is an isometric view of the alternate contact terminals  300 ,  301  of the plug assembly of FIG.  5 . Contact terminals  300 ,  301  include a first portion  350  and a contact spring member  310 . Contact terminals  300 ,  301  are made of a conductive material, preferably copper. The first portion  350  has a pair of legs  330 ,  360  and a lateral portion  320  that extends between the legs  330 ,  360  and couples spring member  310  thereto. Lateral portion  320  has a first surface  380  and an opposite second surface (not shown in FIG. 9, but facing into the page), and an opening  370 . The opening  370  extends through the first surface  380  and the opposite second surface. 
     Contact spring member  310  includes a first raised portion  390  and a second raised portion  340  that are coupled to lateral portion  320  and extend therefrom. As seen best in the exemplary embodiment of FIG. 9, the first raised portion  390  extends from one end of lateral portion  320  proximate to the opening  370 . Second raised portion  340  extends from an opposite end of lateral portion  320 . First raised portion  390  extends from first portion  350  at a first angle with respect to lateral portion  320 . Second raised portion  340  extends at a second angle from first portion  350  with respect to lateral portion  320 . First raised portion  390  and second raised portion  340  are flexibly coupled at a junction point. The orientation of the first raised portion  390  and a second raised portion  340  for use in the plug assembly  30  are best seen in FIG.  7 . 
     For an exemplary assembly, a corresponding one of the AC prongs  18 ,  19  initially slidably engages the first raised portion  390  which flexibly contacts the corresponding prong. As seen best in FIG. 8, each of the prongs  18 ,  19  has a conical tip which is flexibly and securely contacted by the corresponding contact terminal  300 ,  301  through a spring action provided by the flexible contact spring member  310  of contact terminal  300 ,  301 . Contact terminal  300 ,  301  provides a spring loaded contact to provide a secure electrical connection between a the AC prongs  18 ,  19  and the first printed circuit board  36  that the contact terminals  300 ,  301  are mounted thereto. 
     In another embodiment, the plug assembly has U.S. type AC prongs in a plug housing conforming to the applicable plug standards UL 498 and UL 1310. FIG. 11 is an exploded view of an embodiment of a plug assembly  50  having U.S. type AC prongs  58 ,  59  in a plug housing  52 . FIG. 12 is a perspective view of the embodiment of the plug  15  assembly of FIG. 11, showing the plug housing  52  and the body portion  54  connected in the operative position. The plug housing  52  and body portion  54  in FIGS. 11 and 12 are shown in phantom for clarity. 
     An exemplary plug assembly of the present invention further includes an output connector and a means to connect the output connector to a battery. FIG. 10 is an exploded view of an exemplary embodiment of the plug assembly  40  of the present invention showing the plug housing  42 , a printed circuit board, and a battery  48  all in phantom. For this alternate embodiment, plug assembly  40  has a single printed circuit board  46  having circuitry thereon (not shown) that extends from the body portion  44  into the plug housing  42 . In the example shown in FIG. 10, plug assembly  40  serves as a plug charger providing power to a rechargable battery  48  connected to the plug assembly  40  by means of an exemplary cable  49  coupled between the body portion  44  and a rechargable battery  48  (details not shown). Preferably the battery  48  is coupled to an electrical device (not shown). The present invention is not limited to this exemplary application, any suitable device may be connected by suitable means to the plug assembly of the present invention. The plug assembly of the present invention, for example, can also serve as a plug adaptor to provide the conversion of AC power into the required DC voltages for powering an electrical device that is powered only from an AC source. 
     The foregoing detailed description of the invention has been provided for the purposes of illustration and description. Although exemplary embodiments of the present invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments disclosed, and that various changes and modifications to the present invention are possible in light of the above teaching.