Patent Publication Number: US-6335500-B1

Title: Push button type of switch

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a push button type switch, wherein the pressing element retains in an initial position despite the condition of the switch so as to be formed as a complete opening and closing loop. 
     The push button type switch of the current electronic products, as shown in FIGS. 1A and 1B, has a casing with a control rod slidable in the casing. An elastic element is installed between the control rod and an end surface of the casing. A plurality of confining blocks as a sliding guiding surface is formed on the control rod so as to be formed as a track guide. An elastomer displacing along the track guide is formed on the control rod. The control rod moves downward to press the elastic element and then to drive the elastomer to be moved along the track guide to a center confining block for positioning thereon. A driven piece connected to another end of the control rod will press contact pieces to cause terminals to be conductive, and then a force is applied to the control rod again so that it is moved along the track guide to the initial position. Then, the driven piece is driven synchronously to separate from a pressing position of the contact piece, and thus, the circuit is opened. However, the prior art push button type switch has the following disadvantages: 
     1. The parts of the push button type switch can not be easily assembled. As the elastomer moves in the track guide, the confining blocks are often worn so that the elastomer will deform or the confining block wears so that as the control rod is pressed downwards, the control rod can not substantially press the contact piece for controlling the opening and closing of the switch. 
     2. As the control rod is depressed to be positioned in the confining block, it can not restore to the initial condition, while at next time, as it is pressed for restoring to the initial condition, the switch is opened. Therefore, the operation is inconvenient. The push button type switch has on displaying device. The user can not determine the condition of the switch. Moreover, the contact piece is made of a single metal piece with only one thermal extension coefficient. Thus, the object of overload protection can not achieve. As a result, the applications are confined. 
     SUMMARY OF THE INVENTION 
     Accordingly, the primary object of the present invention is to provide a push button type switch, wherein the pressing element retains in an initial position despite the condition of the switch so as to be formed as a complete opening and closing loop. 
     Another object of the present invention is to provide a push button type switch, wherein a display lamp set is further installed for informing the user the condition of the current switch. 
     A further object of the present invention is to provide a push button type switch, wherein the contact piece is formed by two metal pieces with different extension coefficients for achieving the effect of over current or over voltage protection. 
    
    
     BRIEF DESCRIPTION OF FIGURES 
     Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: 
     FIGS. 1A and 1B are schematic views of the prior art push button type switch. 
     FIG. 2 is a schematic perspective view of the present invention. 
     FIG. 3 is an exploded perspective view showing the structure of the present invention. 
     FIGS. 4A,  4 B,  4 C and  4 D are assembled schematic views of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to FIGS. 2,  3  and  4 , the perspective view and the exploded schematic view of the present invention are illustrated. The push button type switch of the present invention includes a body  11 . One side of the body  11  has an opening for being assembled with a sealing piece  12 . The body  11  and sealing piece  12  are installed with matched posts  121 , positioning holes  114  and ear portions  115  and buckle holes  122  for being formed with a switch seat  1 . The body  11  has a hollow inner portion. The portion is spaced as two operation spaces  111 ,  112  by the spacing  113  with through hole  1133 . The spacing  113  is integrally formed the body  11 . A protrusion  223  is installed with a pressing element  2  formed with an operation section  222  by the protrusion  223  and a plurality of conductive elements  6   a,    6   b,  and  6   c  connected to the switch element  4 . The pressing element  2  includes a housing  21  with buckle hole  211  at the periphery and a supporting seat  22  with a buckle hole  221  with respect to the buckle hole  211  for forming the housing  21 . Two ends of the supporting seat  22  and the conductive elements  6   a,    6   b,  and  6   c  at two sides of the body  11  are formed two auxiliary elastic elements  33 ,  33 ′. A display lamp set  23  is arranged on the supporting seat  22 . The display lamp set  23  has pins  232 ,  233  which are connected to resistor  231 . Then, a spacer  225  and post  224  serve to space it for passing through the through hole  1132  and then is connected to the auxiliary elastic elements  33 ,  33 ′ so that the push button type switch is closed. The current passes through the conductive elements  6   a,    6   b,  and  6   c  to the auxiliary elastic elements  33 ,  33 ′ and then passes through the display lamp set  23  (the display lamp set  23  is a neon lamp set) so as to emit light. The housing  21  is made of transparent material in order to inform the user the condition of the lamp. A driving means  3  is installed within the body  11 , which is includes a depressing element  31  connected to the operation section  222  and an elastic element  32  installed in the depressing element  31  and having an end connected to a engaging portion  1131  of the spacing portion  113 , and a rotary seat  34  with an axial connecting portion  342  for being pivotally installed to the body  11  and having a guide groove  341  for resisting against the depressing element  31 . One end of the rotary seat  34  is installed with a positioning portion  343  connected to a switching element  4 . Besides, the switch element  4  has a contact piece  42  connected to the conductive elements  6   c.  Another end of the contact piece  42  is installed with a combining portion  421  which is made of metal wire. A swingable piece  43  with two notches  441  is installed between the contact piece  42  and the rotary seat  34 . The contact piece  42  has another end being installed with joints  43 ,  43 ′ with respective to the conductive elements  6   b.  The contact piece  42  is made of a metal piece with two different extension coefficients (bi-metal). In the present invention, when voltage or current is over the predetermined values, then the contact piece  42  heats due to resistivity. The metal piece with a low extension coefficient will bend to force the contact piece  42  to bend so that the present invention is tripped to be in an open condition (from the closing condition of FIG. 4C to the opening condition of FIG. 4A) so as to achieve the object the overload protection. 
     In the present invention, the conductive elements  6   a,    6   b,  and  6   c  are terminals or pins. With reference to FIG. 4 a,  the schematic view shows the initial condition of the present invention. When the user applies a force to the housing  21  of the pressing element  2  for driving the supporting seat  22  to move downwards. The elastic element  32  of the driving means  3  is a spring with a wider lower portion. The top of the depressing element  31  is formed with a head  311  having an outer diameter larger than the elastic element  32 . As the depressing element  31  is pressed by the pressing element  2  to move downwards to press the elastic element  32 . Then, since the guide groove  341  of the rotary seat  34  are inclined or have a round arc shape from the center to the two ends. The depressing element  31  is shifted along the track of the guide groove  341 . The head  311  of the depressing element  31  will not separate due to the confinement of the protrusion  224  of the operation area  222 . The rotary seat is pressed by the shift of the depressing element  31  and then rotates so that the swingable piece  43  at the same end of the rotary seat  34  will drive the contact piece  42  to move downwards. By the pressing of the elastic body  41 , the joint  43  of the contact piece  42  is connected to another joint  43 ′ on the conductive elements  6   b  so as to be formed as a closing condition (as shown in FIG.  4 ). When the outer force is removed, the elastic element  32  and the auxiliary elastic element  33 ,  33 ′ at two sides of the supporting seat  22  restore the elasticity so as to drive the press element  2  and the depressing element  31  to restore to the initial position. Now, the push button type switch remains in a closing condition (FIG.  4 C). When the user applies a force to the pressing element  2  again, then the depressing element  31  is driven to move along the track at another end of the guide groove  341  so as to drive the rotary seat  34  to move in a reverse direction and cause the swingable piece  44  to guide the contact piece  42  to move upwards so as to be formed as an open condition (as shown in FIG.  4 D). As the outer force disappears, by the restoring elastic forces of the elastic element  32  and the auxiliary elastic element  33 ,  33 ′, the pressing element  2  and the depressing element  31  are restored to the original position. 
     It will also be appreciated that other modifications and variations may be made to the embodiments as described and illustrated within the scope of the present application as defined in the following claims.