Patent Publication Number: US-7592556-B2

Title: Vibration switch

Description:
BACKGROUND 
   1. Technical Field 
   The present invention relates to vibration switches, more specifically, to a vibration switch that is capable of minimizing clattering sounds during use. 
   2. General Background 
   A roller/ball vibration switch is capable of instantly changing its switching state when jerked by a force coming from any direction or a predetermined direction. The roller vibration switch generally includes a housing and a ball disposed in the housing. The ball is rollable/movable in the housing when the housing is caused to quiver in an unsteady state so as to effect a change of an electric switching state. However, the ball will produce a clattering sound when it hits against the housing. 
   Accordingly, there is a need to provide a vibration switch to eliminate or decrease the clattering sound during vibration switch is shaked. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an schematic view of a vibration switch in accordance with one embodiment of the present invention. 
       FIG. 2  is a cross-sectional view of the vibration switch of  FIG. 1 , taken form the line II-II in  FIG. 1 . 
       FIG. 3  is a cross-sectional view of a vibration switch in accordance with another embodiment of the present invention. 
       FIG. 4  is cross-sectional view of a vibration switch in accordance with another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIGS. 1 and 2  show a vibration switch  10  in accordance with one embodiment of the present invention. The vibration switch  10  includes a housing  20 , two side caps  31 ,  32 , a first spring  41 , a second spring  42 , two contact terminals  51 ,  52 , and an inertial weight  60 . 
   The vibration switch  10 , as shown in the  FIG. 2 , is in a normally closed state. In one embodiment, the housing  20  may be electrically insulating and other parts of the vibration switch  10  may be electrically conductive. 
   A chamber  21  is formed in the housing  20  and extends in a longitudinal direction. The side caps  31 ,  32  are of flanged cylinder shapes and each includes a flanged portion and a cylindrical portion. Each of the two side caps  31  and  32  is attached to the housing  20  at one end, respectively, with the flanged portion engaging the chamber  21 . 
   The first spring  41  and the second spring  42  have slightly smaller sizes in the radial direction than that of the chamber  21  and are received in the chamber  21 . As shown in  FIG. 2 , both of the first spring and the second spring  42  are coil springs. One end of the first spring is attached to the cylindrical portion on the side cap  31 . One end of the second spring  42  is attached to the cylindrical portion on the side cap  32 . The contact terminal  51  is attached to the side cap  31  and the contact terminal  52  is attached to the side cap  32 . 
   The inertial weight  60  may be of a flat cylinder shape and can be constructed of metallic material. The inertial weight  60  has a slightly smaller size in the radial direction than that of the chamber  21  and is received in the chamber  21 . The inertial weight  60  is placed between the first spring  41  and the second spring  42  and is kept in an initial balancing position by the spring force of the first spring  41  and the second spring  42 . In one embodiment, the inertial weight  60  is attached to the first spring  41  and is biased by the second spring  42 . In another embodiment, the inertial weight  60  is biased by the first spring  41  and the second spring  42  and is capable of coming out of contact with the first spring  41  and the second spring  42 . 
   When the vibration switch  10  is shaken in the longitudinal direction, the inertial weight  60  moves by the inertial force and is capable of moving to a plurality of disengaging positions. In the disengaging positions, the inertial weight  60  is out of contact with the first spring  41  or the second spring  42 , making the vibration switch  10  change from the normally closed state to an open state. 
   After the shaking of the vibration switch  10  ceases, the inertial weight  60  returns to the initial balancing position by the spring force of the first spring  41  and the second spring  42 , making the vibration switch  10  change from the open state to the normally closed state. 
     FIG. 3  shows a vibration switch  10   a  in accordance with another embodiment of the present invention. The vibration switch  10   a  is constructed similarly to the vibration switch  10 . The two vibration switches  10  and  10   a  have a structural difference in the relationship between the two springs and the inertial weight. As shown in  FIG. 3 , an inertial weight  60   a  is attached to a first spring  41   a  and is out of contact with a second spring  42   a , making the vibration switch  10   a  be in a normally open state. 
   When the vibration switch  10   a  is shaken in a longitudinal direction, the inertial weight  60   a  is capable of moving from an initial position to a plurality of engaging positions. In the engaging positions, the inertial weight  60   a  contacts the second spring  42   a , making the vibration switch  10   a  change from the normally open state to a closed state. After the shaking of the vibration switch ceases, the inertial weight  60   a  returns to the initial position by the spring force of the first spring  41   a  and the vibration switch  10   a  returns to the normally open state. 
     FIG. 4  shows a vibration switch  10   b  in accordance with another embodiment of the present invention. The vibration switch  10   b  is constructed similarly to the vibration switch  10 . The only difference between the two vibration switches  10   b  and  10  is that two springs of the vibration switch  10   b  are not attached to the side caps. 
   When the vibration switch  10   b  is shaken in a longitudinal direction, a inertial weight  60   b  is capable of moving from an initial position to a plurality of disengaging positions. In the disengaging positions, a first spring  41   b  or a second spring  42   b  is capable of returning from a compression state to a normal state and out of contact with a side cap  31   b  or a side cap  32   b , changing the vibration switch  10   b  from a normally closed state to an open state. 
   After the shaking of the vibration switch  10   b  ceases, the inertial weight  60   b  returns to the initial position by the spring force of the first spring  41   b  and the second spring  42   b  and the vibration switch  10   b  thus returns to the normally closed state. 
   Vibration switches described above are constructed with two springs and an inertial weight enclosed by a housing and two side caps, in other words, the two springs and the inertial weight are enclosed by a three-part assembly. However, when needed, other types of structure may be used for enclosing the two springs and the inertial weight, such as a two-part assembly. 
   During the vibration switches are shaken, the inertial weight moves along the longitudinal direction and dose not hit against the housing, clattering sound is thus eliminated. 
   While various embodiments have been described and illustrated, the invention is not to be construed as being limited thereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.