Abstract:
A sealed pushbutton switch ( 1 ) includes an insulative housing ( 2 ), a number of fixed contacts ( 7 ), an actuator ( 3 ) moveably retained in the insulative housing, a moveable contact ( 6 ) fastened to the actuator and including a pair of elastic beams ( 62 ) each provided with a contact portion ( 621 ) contactable to corresponding fixed contacts to establish a reliable electrical connection between the fixed contacts, and a spring ( 5 ) mounted below the actuator. When the actuator is pushed, the moveable contact has an agile movement to break the electrical connection between the moveable contact and the fixed contacts.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a sealed pushbutton switch, and particularly to a normally closed sealed pushbutton switch used in various electronic appliance.  
         [0003]     2. Description of Related Art  
         [0004]     A conventional sealed pushbutton switch is described in U.S. Pat. No. 6,459,057, which was issued on Oct. 1, 2002. The pushbutton switch is normally in a closed position, comprising a base, a plurality of fixed contacts assembled to the base, an insulative housing snapping onto the base, an actuator retained in the insulative housing and provided with a shaft and a head, a contact spring normally contactable of an inner edge of fixed contacts for establish an engagement between the contact spring and the fixed contacts, a wire compression spring abutting against a bottom of the head, and an  0 -ring mounted around the shaft. In operation, the actuator is pushed downwardly to thereby move the contact spring away from the fixed contacts for breaking the electrical connection between the fixed contacts. The pushbutton switch is then caused to be in an electrical opened position.  
         [0005]     An electrical connection between the fixed contacts is established by an engagement between the contact spring and inner edges of the fixed contacts. However, the engagement between the contact spring and the fixed contacts is unreliable, not only because an out surface of the contact spring is discrete, but also because the inner edge of the fixed contact is narrow. Further more, the contact spring is moveably retained in the head of the actuator. As a result, the contact spring is hard to be availably driven by the actuator thus is hard to have a steady engagement with the fixed contacts.  
         [0006]     Hence, an improved pushbutton switch is required to overcome the above-mentioned disadvantages of the related art.  
       SUMMARY OF THE INVENTION  
       [0007]     A primary object of the present invention is to provide a sealed pushbutton switch having a moveable contact and a fixed contact, between which a reliable engagement is established.  
         [0008]     Another object of the present invention is to provide a sealed pushbutton switch formed with a moveable contact having an agile movement during operation.  
         [0009]     Another object of the present invention is to provide a sealed pushbutton switch provided with a moveable contact capable of being availably driven by the actuator.  
         [0010]     To achieve the aforementioned objects, a sealed pushbutton switch comprises an insulative housing defining a cavity, a plurality of fixed contacts mounted on the insulative housing each formed with an engaging portion, an actuator moveably retained in the insulative housing, a moveable contact fastened to the actuator and comprising a pair of elastic beams each provided with a contact portion contactable to corresponding engaging portions of the fixed contacts, and a spring mounted below the actuator. When the actuator is pressed and moves together with the moveable contact from a first position to a second position relative to the insulative housing along a top-to-bottom direction, an electrical connection between the moveable contact and the fixed contacts comes to break.  
         [0011]     The moveable contact comprising a pair of elastic beams each provided with a contact portion would not only get a reliable engagement between itself and the fixed contacts, but also have an agile movement of moving away from the fixed contacts when it is caused to be in electrical opened position.  
         [0012]     Additionally, another advantage of the invention is to provide an engaging portion on each fixed contact for enlarging contacting area between the moveable contact and the fixed contact. The engagement between the moveable contact and the fixed contacts is enhanced.  
         [0013]     Further more, the moveable contact fastened to the actuator would make itself unmovable relative to the actuator to have a reliable operation together with the actuator. The actuator would have an available manipulation to drive the moveable contact in operation.  
         [0014]     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is an exploded perspective view of a sealed pushbutton switch in accordance with the present invention;  
         [0016]      FIG. 2  is a perspective view of an actuator as shown in  FIG. 1 ;  
         [0017]      FIG. 3  is a perspective view of a moveable contact as shown in  FIG. 1 ;  
         [0018]      FIG. 4  is a perspective view of a base as shown in  FIG. 1 ;  
         [0019]      FIG. 5  is an assembled perspective view of the sealed pushbutton switch as shown in  FIG. 1 , with the base and fixed contacts being removed;  
         [0020]      FIG. 6  is an assembled perspective view of the sealed pushbutton switch as shown in  FIG. 1 ; and  
         [0021]      FIG. 7  is an assembled perspective view of the sealed pushbutton switch as shown in  FIG. 1 , with an insulative housing being removed. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     Reference will now be made to the drawing figures to describe the present invention in detail. Referring to  FIG. 1 , a sealed push button switch  1  in accordance with the preferred embodiment of the present invention comprises an insulative housing  2  defining a cavity  25 , an actuator  3  retained in the cavity  25  of the insulative housing  2 , a moveable contact  6 , a washer  4 , a wire compression spring  5  assembled to the actuator  3 , a base  8  attached to the insulative housing  2 , and a plurality of fixed contacts  7  mounted on the base  8 .  
         [0023]     Referring to  FIG. 1 , the insulative housing  2  is a substantially rectangular case, comprising a front wall  23 , a top wall  21 , a bottom wall  24  opposite to the top wall  21 , a pair of side walls  22  extending rearwardly from the front wall  23  to thereby define the cavity  25  therebetween. The top wall  21  has a circular through hole  26  defined in a central portion thereof. Each side wall  22  has a recess  221  defined in an inner surface thereof. A pair of protrusions  241  are symmetrically formed on the bottom wall  24 , each with an upmost thereof extending upwardly.  
         [0024]     Referring to  FIG. 2 , the actuator  3  comprises a body portion  32  and a button  31  extending upwardly from a top of the body portion  32 . The button  31  includes a columnar portion  311 , and a guiding portion  312  having a conical shape for facilitating an insertion of itself into the through hole  26  during assembly. The button  31  defines therearound an annular groove  313 , which is positioned adjacent to the body portion  32 . The body portion  32  is provided with a rectangular primary wall  320 , a pair of periphery walls  321  perpendicular to opposite sides of the primary wall  320 , and a columnar post  33  extending downwardly from the primary wall  320  for fastening the spring  5 . A nose portion  322  configured as a flat plane projects rearwardly from a center of an upper portion of the primary wall  320 , and is flush with a top surface of the primary wall  320  for upholding the button  31 . A slot  324  is defined at a bottom of the nose portion  322  in a longitudinal direction. The nose portion  322  has a tongue portion  323  extending parallel thereto and being located therebelow in a certain distance.  
         [0025]     Referring to  FIG. 3 , the moveable contact  6  is formed by bending a punched metal plate, comprising a retention portion  61  and a pair of elastic beams  62 . The retention portion  61  has an primary plate  612 , an insertion plate  611  extending parallel to the primary plate  612  and positioned a certain distance above the primary plate  612 . The insertion plate  611  has a pair of click projections  6110  formed at opposite edges thereof. A connection plate  613  extends in another direction perpendicular to the extending direction of the primary plate  612  for connecting the insertion plate  611  and primary plate  612  together. The pair of elastic beams  62  extend symmetrically horizontally firstly from a center of opposite sides of the primary plate  612  and then outspread obliquely downwardly. A contact portion  621  having a semi-circular curved surface is formed on a free end of each elastic beam  62 .  
         [0026]     Referring to  FIG. 1 , each fixed contact  7  comprises a body portion  71 , a pair of soldering portions  74 , and a pair of connection portions  72  connecting the corresponding soldering portions  74  to the body portion  71 . The body portion  71  is configured as a lying “L”, with one end thereof protruding laterally therefrom to form an engaging portion  711 . The body portion  71  has an indentation  73  defined beside the engaging portion  711  thereof.  
         [0027]     Referring to  FIG. 4 , in conjunction with  FIG. 1 , the base  8  is substantially a flat plane, comprising an inner face  81 , an out face  82  and a pair of tubers  83  formed at opposite sides thereof. The inner wall  81  has a pair of retaining channels  841  symmetrically defined therein. The outer wall  82  defines therein two pairs of insertion channels  142  respectively communicating with corresponding retaining channel  841  for extension of the soldering portions  74  of the fixed contacts  7 .  
         [0028]     Referring to  FIGS. 5-7 , in conjunction with  FIG. 1 , in assembly of the sealed pushbutton switch  1 , the moveable contact  6  is fastened to the body portion  32  of the actuator  3  firstly. The retention portion  61  of the moveable contact  6  is confined between the nose portion  322  and the tongue portion  323  of the actuator  3 , with the insertion plate  611  thereof being inserted into the slot  324  and the click projections  6110  thereof frictionally engaging with the slot  324 . The pair of elastic beams  62  are positioned between the pair of periphery walls  321 . The spring  5  is assembled to the actuator  3  by encircling around the post  33 . Secondly, The actuator  3  together with the moveable contact  6  and the spring  5  are received in the cavity  25  of the insulative housing  2 , with the button  31  extending outside the top wall  21  through the through hole  26 . The washer  4  is then inserted into the annular groove  313  for preventing leaks between the actuator  3  and the insulative housing  2 .  
         [0029]     Thirdly, the pair of fixed contacts  7  are assembled to the base  8 . The body portions  71  of the fixed contacts  7  are respectively partially retained in corresponding retaining channels  841 , with engaging portions  711  thereof being exposed on the inner face  11 , the connection portions  72  thereof inserted into the corresponding insertion channels  142 , and the soldering portions  74  thereof extending outwardly through the insertion channels  142 . Finally, the base  1  together with the fixed contacts  7  are attached to a rear portion of the insulative housing  2 . Referring to  FIGS. 5, 7 , the spring  5  is located between the actuator  3  and the bottom wall  24  of the insulative housing  2 , with a lower portion thereof fixed between the pair of protrusions  241 . The pair of elastic beams  62  of the moveable contact  6  are positioned between the fixed contacts  7 , with the contact portions  621  thereof respectively contacting with the corresponding engaging portions  711 . An electrical connection between the fixed contacts  7  is established, via an engagement between the contact portions  621  and the engaging portions  711  of the fixed contacts  7 . The sealed pushbutton switch  1  is in the closed position.  
         [0030]     In operation, when the button  31  of the actuator  3  is downwardly pushed due to an external force exerted thereon, the moveable contact  6  is driven to move downwardly together with the actuator  3  to thereby make the contact portions  621  moving away from the engaging portions  711  and plunging into the indentations  73 . The sealed pushbutton switch  1  is caused to be in an electrical opened position, when the electrical connection between the engaging portions  711  of the fixed contacts  7  is broken. At the same time, the spring  5  is compressed. When the external force is removed, the pushbutton switch  1  restores itself to a normally closed position, due to an elastic force provided by the compressed spring  5 .  
         [0031]     In another embodiment, the fixed contacts  7  could be assembled to the walls  21 - 24  of the insulative housing  2 , with the engaging portions  711  thereof exposed to the cavity  25  for being contacted by the moveable contact  6 .  
         [0032]     However, the disclosure is illustrative only, changes may be made in detail, especially in matter of shape, size, and arrangement of parts within the principles of the invention.