Button assembly for input devices

Abstract

A button assembly has a housing having a palm portion configured to fit a hand of a user. A spring beam having a first spring beam end and a second spring beam end is supportively attached to the palm portion of the housing with a first fulcrum so as to form a first cantilever beam extending away from the palm portion of the housing. A switch button having a first switch button end and a second switch button end is supportively attached at the first switch button end to the second spring beam end with a second fulcrum so that the switch button forms a second cantilever beam extending from the second fulcrum towards the palm portion of the housing.

1 . A button assembly comprising: 
 a housing having a palm portion configured to fit a hand of a user;    a spring beam having a first spring beam end and a second spring beam end;    a first fulcrum having a first spring constant supportively attaching the first spring beam end to the palm portion of the housing so that the spring beam forms a first cantilever beam extending away from the palm portion of the housing;    a switch button having a first switch button end and a second switch button end; and    a second fulcrum having a second spring constant supportively attaching the first switch button end to the second spring beam end so that the switch button forms a second cantilever beam extending from the second fulcrum towards the palm portion of the housing.    
   
   
       2 . The button assembly of  claim 1  wherein the housing, the spring beam, the first fulcrum, the switch button, and the second fulcrum are molded as a single piece of plastic.  
   
   
       3 . The button assembly of  claim 1  wherein the first spring constant cooperates with the second spring constant so as to provide an increasing force profile from the second switch button end toward the first switch button end.  
   
   
       4 . The button assembly of  claim 1  wherein the first spring constant cooperates with the second spring constant so as to provide a decreasing force profile from the second switch button end toward the first switch button end.  
   
   
       5 . The button assembly of  claim 1  wherein the first spring constant cooperates with the second spring constant so as to provide a neutral force profile from the second switch button end toward the first switch button end.  
   
   
       6 . The button assembly of  claim 1  further comprising an electronic switch configured to actuate upon application of sufficient force to the switch button by the user wherein a first force is required to be applied at the first switch button end to actuate the electronic switch and a second force is required to be applied at the second switch button end to actuate the electronic switch, the first force being greater than the second force.  
   
   
       7 . The button assembly of  claim 6  wherein the first force is about twice the second force.  
   
   
       8 . The button assembly of  claim 7  wherein a distance between the first switch button end and the second switch button end is not less than 3 cm.  
   
   
       9 . The button assembly of  claim 6  wherein the first force is about 1.2 Newtons and the second force is about 0.6 Newtons.  
   
   
       10 . The button assembly of  claim 9  wherein a distance between the first switch button end and the second switch button end is not less than 3 cm.  
   
   
       11 . A trackball pointing device comprising: 
 a trackball housing having a palm portion and a distal portion;    an electronic switch;    a fulcrum having a spring constant proximate to the distal portion of the trackball housing;    a thumb pad having a distal end and a palm end, wherein the fulcrum flexibly connects the thumb pad to the distal portion of the trackball housing so as actuate the electronic switch when force is applied to the thumb pad, a first actuating force at the distal end of the thumb pad being greater than a second actuating force at the palm end of the thumb pad.    
   
   
       12 . The trackball pointing device of  claim 11  wherein the first actuating force is at least two times greater than the second actuating force.  
   
   
       13 . The trackball pointing device of  claim 11  wherein the distal end of the thumb pad is at least 3 cm away from the palm end of the thumb pad.  
   
   
       14 . The trackball pointing device of  claim 11  wherein the first actuating force is about 1 Newton and the second actuating force is about 0.5 Newtons.