Abstract:
An audio jack comprises a set of contacts including a stationary contact ( 25 ) and a movable contact ( 23 ), and an anti-dust dome member ( 5 ). The anti-dust dome member ( 5 ) includes a conductive sheet ( 51 ) extending from a horizontal plate portion ( 250 ) of the stationary contact ( 25 ) to a lateral beam ( 235 ) of the movable contact ( 23 ), and a middle conductive dome sheet ( 52 ) below the conductive sheet ( 51 ). The conductive dome sheet ( 52 ) is constantly actuated to establish an electrical connection between the stationary contact ( 25 ) and the movable contact ( 23 ). Thus, even if dust is deposited on the anti-dust dome member ( 5 ) will have no effect on the electrical connection as established.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electrical connectors, especially to an electrical connector with an anti-dust device to avoid the poor contact between the movable contact and the fix contact due to dust contamination. 
     2. Background of the Invention 
     With the ever-increasing miniaturization of computer and other electronic equipment, it becomes increasingly difficult to design electrical circuitry for connector thereof. One area of such difficulty is electrical switches or switch assemblies. An electrical switch assembly may be used as a normally open switch with switch contacts designed to be closed upon actuating the switch, or the switch assembly may be a normally closed switch with the contacts designed to be opened when the switch is actuated. 
     U.S. Pat. No. 4,937,404 issued to Kitagawa on Jun. 26, 1990 discloses an electrical connector comprising an insulative housing and a plurality of contacts, the insulative housing has an observation window, the contacts including signal contacts and switch contacts, the switch contacts including a first movable contact, a second movable contact; a first fix contact and a second fix contact are also included which act in concert with the first movable contact and the second movable contact. The first movable contact has a first elastic portion and a first contact portion extending from the first elastic portion. The first contact portion straps on the first fix contact to form a conductive circuit. 
     Unfortunately, problems continue to be encountered with the electrical connectors mentioned above. The observation window is helpful to examine the connection between the first contact portion and the first fix contact. However, the dust is easy to get into the observation window and make the first contact portion fail to connect with the first fix contact. Therefore, an improved electrical connector is desired to overcome the disadvantages of the prior arts. 
     SUMMARY OF THE INVENTION 
     An object, therefore, of the invention is to provide a new and improved electrical connector of the character able to prevent a poor electrical connection between contacts due to the dust contamination. 
     In order to achieve the objects set forth above, an audio jack for receiving a mating plug according to a preferred embodiment comprises an insulative housing defining a longitudinal plug-insertion hole, a set of contacts assembled on to the insulative housing and including a stationary contact and a movable contact. The stationary contact defines a plate portion. The movable contact has a lateral beam located proximate to the plate portion. An anti-dust dome member is disposed between the stationary contact and the movable contact. The anti-dust dome member includes a first insulative sheet attached onto the plate portion and defining an opening, a middle conductive dome sheet shaped to cover the opening of the first insulative sheet, and a second conductive sheet adhesively disposed on the first insulative sheet to cover the middle conductive dome sheet and to contact the lateral beam of the movable contact, wherein the first insulative sheet is configured to isolate an electrical connection between the second conductive sheet and the stationary contact. The middle conductive dome sheet is constantly actuated to establish an electrical connection between the second conductive sheet and the plate portion of the stationary contact. In this preferred embodiment, due to having the extension of the second conductive sheet from the plate portion to the lateral beam of the movable contact, the electrical connection between the second conductive sheet and the plate portion of the stationary contact will indirectly result in an electrical connection of the stationary contact and the movable contact. Thus, even if dust is deposited on the anti-dust dome member will have no effect on the electrical connection between the stationary contact and the movable contact, because the anti-dust dome member is constantly actuated having no influence of the dust deposition. 
     Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 
         FIG. 1  is an assembled, perspective view of an electrical connector embodying the concepts of the invention; 
         FIG. 2  is an exploded, perspective view of the electrical connector shown in  FIG. 1 ; 
         FIG. 3  is another exploded, perspective view of the electrical connector shown in  FIG. 1 ; 
         FIG. 4  is a perspective view showing a stationary contact electrically connected with a movable contact by an anti-dust dome member; and 
         FIG. 5  is an exploded, perspective view of the anti-dust dome member of the electrical connector shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , an electrical connector  100  includes an insulative housing  4 , a plurality of contacts, a retention device  3  and an anti-dust device or dome member  5 . 
     Referring to  FIG. 2 , contacts includes a signal contact and a switch contact, the signal contact has a first signal contact  21  and a second signal contact  22 ; the switch contact has a first movable contact  23 , a second movable contact  24 , a first fix or stationary contact  25  and a second fix or stationary contact  26 , the first fix contact  25  and second fix contact  26  coordinate with the first movable contact  23  and second movable contact  24  respectively. 
     Referring to  FIGS. 2 and 3 , the first signal contact  21  has a first block portion  210 , a first arm portion  211  and a first soldering portion  212  extending from two ends of the first block portion  210 , the first arm portion  211  extends from the free end and forms a first contact portion  213 , first thorn portions  2100  are formed on two sides of the first block portion  210 , the first contact portion  213  has a dimple  2130  on the surface. 
     The second signal contact  22  has a second block portion  220 , a second arm portion  221  and a second soldering portion  222  extending from two ends of the second block portion  220 . The second arm portion  221  extends from the free end and forms a second contact portion  223 , the second thorn portions  2200  are formed on two sides of the second block portion  220 . 
     The first movable contact  23  includes a first retention portion  230 , and a third soldering portion  231  extending from the end of the first retention portion  230 . A first elastic portion  232  and an interfering portion  234  are formed on two sides of the first retention portion  230  respectively. A third contact portion  233  extends from the end of the first elastic portion  232 . 
     The second movable contact  24  includes a second retention portion  240  and a fourth soldering portion  241  extending from the second retention portion  240 , the second retention portion  240  has a fourth thorn portion  2400  on two sides thereof. A second elastic portion  243  is formed on one side&#39;s middle part of the second retention portion  240 . The end of second elastic portion  243  extends and forms a fourth contact portion  244 . 
     The first fix contact  25  sticks to the first movable contact  23  firmly and includes a first base or a plate portion  250  and a fifth soldering portion  251 , the fifth soldering portion  251  extending from one side of the first base portion  250 . A dust-proof portion  5  of the elastic slice  52  is set at the part where the third contact portion  233  of the first movable contact  23  strap on the first base portion  250  of the first fix contact  25 . The fifth thorn portion  2500  is formed on the first base portion  250 . 
     The second fix contact  26  includes a second base portion  260 , a sixth contact portion  261  extending from the second base portion  260  and a sixth soldering portion  262  extending from one side of the second base portion  260 . The sixth contact portion  261  sticks to the fourth contact portion  244  of the second movable contact  24 . A sixth thorn portion  2600  is set on the top of the second base portion  260 . 
     The retention device  3  has a nick which is helpful to the plug&#39;s retention after inserting into the electrical connector  100 . 
     The insulative housing  4  includes a main body  40 ; a joint portion  41  protruding from one side of the main body  40 ; and a patch hole  42  running through the main body  40  and the joint portion  41 . The main body portion  40  includes a top wall  43 , a bottom wall  44 , a first side wall  45 , a second side wall  46  and a back wall  47 , the top of the joint portion  41  has a nick portion  410  which connects the patch hole  42 . 
     The first side wall  45  and the second side wall  46  have a first opening  450  and a second opening  460 . A lock opening  451  is formed on the first side wall  45  near the back wall  47 ; the back wall  47  has the first groove  471  and the second groove  472 . 
     The top wall  43  includes a first passageway  431 , a second passageway  432 , a third passageway  433 , a fourth passageway  434 , a fifth passageway  435 , a sixth passageway  436  and a seventh passageway  437 . The third passageway  433 , the fifth passageway  435  and the seventh passageway  437  are set along the side near the first sidewall  45 . The first passageway  431 , the second passageway  432 , the fourth passageway  434  and the sixth passageway are set along the side near the second sidewall  46 . 
     The bottom wall  44  includes a first groove portion  441 , a second groove portion  442 , a third groove portion  443 , a fourth groove portion  444 , a fifth groove portion  445 , a sixth groove portion  446  and a seven groove portion  447 , which are corresponding to the top wall  43 . 
     Referring to  FIG. 4 , the stable or first fix contact  25  defines the plate portion  250 . The movable contact  23  has a lateral beam  235  located proximate to the plate portion  250 . The anti-dust dome member  5  is attached between the stationary contact  25  and the movable contact  23 . Referring to  FIG. 5 , the anti-dust dome member  5  includes a first insulative sheet  53 , a second conductive sheet  51  and a middle conductive dome sheet  52 . The first insulative sheet  53  is attached onto the plate portion  250  and defining an opening  531 . The middle conductive dome sheet  52  is shaped to cover the opening  531  of the first insulative sheet  53 . The second conductive sheet  51  is adhesively disposed on the first insulative sheet  53  to cover the middle conductive dome sheet  52  and to contact the lateral beam  235  of the movable contact  23 , wherein the first insulative sheet  53  is configured to isolate an electrical connection between the second conductive sheet  51  and the stationary contact  25 . As shown in  FIGS. 4 and 5 , the middle conductive dome sheet  52  is constantly actuated by an elastic force, which is generated by an elastic arm  233  of an actuating element in its normal state, to enable an electrical contact between the second conductive sheet  51  and the plate portion  250  of the stationary contact  25  via the middle conductive dome sheet  52  on the opening  531  of the first insulative sheet  53 , which indirectly results in an electrical connection of the stationary contact  25  and the movable contact  23  due to having the extension of the second conductive sheet  51  from the plate portion  250  to the lateral beam  235  of the movable contact  23 . In this preferred embodiment, the elastic arm  233  of the actuating element is part of the movable contact  23 . Thus, even if dust is deposited on a joint of the anti-dust dome member  5  and the elastic arm  233  of the actuating element will have no effect on the electrical connection between the stationary contact  25  and the movable contact  23 , which is indirectly and constantly actuated by the elastic force from the actuating element, that is exerted on the an anti-dust dome member  5 . This will avoid the poor electrical connection between the stationary contact  25  and the movable contact  23  due to the influence of dust. In addition, when the elastic arm  233  of the movable contact  23  is at a second state where a complementary plug is inserted into the electrical connector to urge said elastic arm  233  away from said middle conductive dome sheet  52 , the middle conductive dome sheet  52  is no longer actuated to enable the electrical connection between the stationary contact  25  and the movable contact  23  due to having the middle conductive dome sheet  52  left away from the stationary contact  25  and no longer electrically contacting the stationary contact  25 . 
     It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. 
     While preferred embodiment in accordance with the present invention have been shown and described, equivalent modifications and changes known to persons skilled in the art according to the spirit of the present invention are considered within the scope of the present invention as defined in the appended claims.