Patent Publication Number: US-2005115817-A1

Title: Push button switch

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a push button switch in which a plurality of separate contacts may be electrically connected together via a manual depression on the push button.  
      2. Description of the Prior Art  
      The push button switches are widely used in many applications such as home electric applications, business machines, and communication devices.  
      One conventional push button switch is disclosed in JP. Pat. No. 11-144560. The push button switch comprises a housing, a first contact, a second contact, a movable contact and an actuator. The housing has a substantially cubic configuration. The second contact separates with the first contact and is mounted with a planar base plate. The movable contact made of flexible conductive material is in a substantially U-shaped configuration. The movable contact has a contacting portion defined at one end of an arm and a positioning portion at one end of the other arm. The contacting portion slides to contact with the first contact. The positioning portion engages with the second contact and is capable of pivoting therearound. The actuator is substantially a rod and can be pressed downwardly to actuate the movable contact.  
      In operation, the actuator is pressed downwardly and the movable contact pivots around the positioning portion, which in turn causes the contacting portion to slide to contact with the first contact. Thus the first contact and the second contact are electrically connected, the switch is on.  
      Though the switch works well, there are some problems it cannot solve. The conventional switch needs lube between the contacting portion and the housing, thereby ensuring a smooth movement of the contacting portion during contacting/discontacting with the first contact. Furthermore, the first contact is mounted on the bottom wall of the housing and has a planar configuration. So the dust is easy to be gathered on the first contact. This structure may result in an unreliable electrical connection. So an improvement is in need.  
     BRIEF SUMMARY OF THE INVENTION  
      In according with the conventional invention, a main object of this invention is to provide a switch which is capable of establishing a convenient and reliable electrical connection. On the basis of this solution, a push button switch is available in which the structure of the movable contact is improved.  
      A push button switch having a reliable electrical connection comprises a housing, a cover, an actuator, a pair of fixed contacts and a movable contact. The housing has a base. A periphery wall extends from the base and a cavity is defined therein. The movable contact made of flexible conductive material is received in the housing and comprises a periphery section, and a pressable section. The pair of fixed contacts mounted in the housing comprises a common contacting contact and a non-common contacting contact. The non-common contacting contact has a non-common contacting strip projecting substantially parallel to the actuating direction. The common contacting contact engages with the periphery section of the movable contact and is able to be brought to surface contact with the non-common contacting contact strip in operation. The actuator actuates on the pressable section of the movable contact.  
      The switch further comprises a cover engaging with the housing and the cover defines a guiding hole. The actuator comprises an operating portion extending beyond the guiding hole. The common contacting contact has a common contacting strip and forms a hook portion at an upper end of the common contacting strip. The hook portion engages with the periphery section of the movable contact.  
      In the present invention, the common contacting strip is capable of being moved with the movable contact to touch the non-common contacting strip, thereby establishing electrical connection with the non-common contacting strip. As a result, the switch avoids a sliding operation. Thus, it&#39;s no need for the switch to use lube and this structure can also prevent the dust to be gathered on the contacts.  
      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  
       FIG. 1  is a perspective view of a switch according to this invention;  
       FIG. 2  is an exploded view of  FIG. 1 ;  
       FIG. 3  is another exploded view of  FIG. 1 ;  
       FIG. 4  is a cross-sectional view taken from line  4 - 4  of  FIG. 1  wherein the switch is in a normal status; and  
       FIG. 5  is a cross-sectional view taken from line  4 - 4  of  FIG. 1  but with the switch being depressed. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODYMENTS  
      Referring to  FIG. 2 , a push button switch  1  according to this invention comprises a housing  2 , a cover  3 , an actuator  4 , a common contacting contact  5 , a non-common contacting contact  6  and a movable contact  7 .  
      Referring  FIGS. 2 and 3 , the housing  2  is formed by molding an insulative material such as synthetic resin in a shape of substantially cubic. The housing  2  has a base  20 . A periphery wall extends from the base  20  and a cavity  25  is defined therein. The periphery wall has opposite front and rear walls  21  and  24  and opposite left and right walls  22  and  23 . The base  20  has a pair of posts  201  symmetrically projecting downwardly from a lower surface thereof. The base  20  also has a plurality of lower standoffs (not labeled) projecting from four corner portions of the lower surface of the base  20 . The opposite left and right walls  22  and  23  each have a projection  221  or  231  vertically projecting from the outer surface thereof. The opposite front and rear walls  21  and  24 , each defines a guiding groove  211  or  241  in a left portion of inner surface thereof. The periphery wall has four upwardly projecting protrusions  26  extending upwardly at the four corner portions on the upper surface thereof.  
      The cover  3  has a planar base plate  31 , a pair of U-shaped locking lugs  32  depending from the planar base plate  31  to lock with the projections  221  and  231 . The locking lug  32  is narrower than the planar base plate  31 . The planar base plate  31  also has an upwardly projecting guiding block  310  corresponding to the guiding grooves  241  and  211  on a left portion thereof. A guiding hole  311  is defined downwardly through the block  310  and the planar base plate  31  for guiding the movement of actuator  4 .  
      The actuator  4  comprises an operating portion  41 , a holding portion  42  and a pressing portion  43 . The operating portion  41  is substantially a rectangular shaped rod. The operating portion  41  extends downwardly and has press portion  43  laterally projecting from a lower end. The pressing portion  43  is substantially a block. The operating portion  41  has a holding portion  42  extending from the lower end in the directions vertically to the pressing portion  43 . The holding portion  42  has a pair of tabs  421  respectively extending downwardly from opposite side portions thereof.  
      The common contacting contact  5  made of conductive material comprises a common contacting contact mounting portion  51  and a common contacting strip  53 . The common contacting strip  53  extends upwardly from the common contacting contact mounting portion  51 . The common contacting contact mounting portion  51  has a pair of common contacting terminal pieces  52  oppositely extending therefrom. The common contacting strip  53  has an arch-shaped hook portion  530  formed at an upper end. The non-common contacting contact  6  comprises a non-common contacting strip  63  and a non-common contacting contact mounting portion  61 . The non-common contacting contact mounting portion  61  has a pair of common contacting terminal pieces  62  oppositely extending therefrom. The non-common contacting strip  63  extends upwardly from the non-common contacting contact mounting portion  61 .  
      The movable contact  7  has a V-shaped configuration and comprises a resilient supporting portion  76 , a connecting portion  77  and a bent portion interconnecting the supporting portion  76  and the connecting portion  77 . A pair of offsetting fingers are formed on the supporting portion  76  and each has a curved end to form a supporting foot  72 . A substantially rectangular shaped hole  75  is defined in the connecting portion  77  and is located adjacent to a right distal end of the connecting portion  77 . A periphery section  71  surrounds the hole  75 . A pressable section  74  is defined on the bent portion of the V-shaped movable contact  7 .  
      In assembly, the common contacting contact  5  and the non-common contacting contact  6  are retained in the housing  2  by insert molding. The common contacting terminal piece  52  and the non-common contacting terminal piece  62  extend out from the housing  2 . The movable contact  7  is received in the cavity  25 . The supporting foot  72  abuts a lower corner portion of the right wall  23 . The periphery section  71  couples with the hook portion  530  of the common contacting strip  53 . The non-common contacting strip  63  is located between the offsetting fingers, and a top portion extending through the hole  75 . The top portion of the non-common contacting strip  63  is proximate to the movable contact  7  but not contacting it (best shown in  FIGS. 4 and 5 ). The holding portion  42  catches movable contact  7  between the tabs  421 . The pressing portion  43  abuts on the pressable section  74 . The operating portion  41  upwardly projects through the guiding hole  311 . The cover  3  engages with the housing  2  and is retained between the protrusions  26 . The catch lugs  32  engage with the projections  221  and  231 .  
      In operation, when the actuator  4  is downwardly pressed, the actuator  4  moves along the guiding grooves  211  and  241  and the pressing portion  43  downwardly presses the pressable section  74  of the movable contact  7 . Upon depression on the pressable section  74 , the supporting portion  76  is elastically deformed and the movable contact  7  pivots around the supporting foot  72 . The periphery section  71  moves rightwards. As a result, the hook portion  530  of the common contacting strip  53  is brought to electrically contact with the non-common contacting strip  63 . Thereby, the electrical connection is established (best shown in  FIG. 5 ). When released, the deformed common contacting strip  53  recovers and the movable contact  7  restores to the normal status.  
      In the present invention, the common contacting strip  53  is capable of being moved with the movable contact  7  to touch the non-common contacting strip  63 , thereby establishing electrical connection with the non-common contacting strip  63 . As a result, the switch avoids a sliding operation. Thus, it&#39;s no need for the switch to use lube and this structure can also prevent the dust to be gathered on the contacts.  
      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 be limited to the details given herein.