Cantilever force sensor

Abstract

A cantilever force sensor with relatively lower On-Force is disclosed, which comprises a top stack, a bottom stack, and a spacer. The first spacer is configured between the top stack and the bottom stack and configured in a first side of the force sensor. A second side, opposite to the first side, of the top stack, is cantilevered from the bottom stack. When the force sensor is depressed from the top side, the second side of the top stack moves down using the first spacer as a fulcrum. Since the cantilevered side can be easily depressed down so that the On-Force for the force sensor is reduced and hence a force sensor with a relatively higher sensitivity is created.

What is claimed is: 
     
         1 . A cantilever force sensor, comprising a top stack, a bottom stack, a first spacer, a bottom switch, and a second spacer, wherein
 the first spacer is configured, in a thickness direction of the force sensor, between the top stack and the bottom stack, and is configured in a first side of the force sensor,   a second side, opposite to the first side, of the top stack, is cantilevered from the bottom stack,   in response to the top stack being depressed toward the bottom stack, the second side of the top stack moves down using the first spacer as a fulcrum,   one of the top stack and the bottom stack is a first stack,   another of the top stack and the bottom stack is a second stack,   the first stack comprises:
 a first substrate, 
 a first piezo layer, and 
 a first electrode between the first substrate and the first piezo layer in the thickness direction, 
   the bottom switch comprises:
 a first conductive contact configured on a bottom side of the bottom stack; 
 a second conductive contact aligned with the first conductive contact, and configured on a top side of a third substrate, and 
   the second spacer is configured between the bottom stack and the third substrate in the thickness direction, and configured in the first side of the force sensor.   
     
     
         2 . The cantilever force sensor as claimed in  claim 1 , wherein
 the third substrate is a printed circuit board.   
     
     
         3 . The cantilever force sensor as claimed in  claim 1 , wherein
 the first conductive contact and the second conductive contact are configured in the second side of the force sensor.   
     
     
         4 . The cantilever force sensor as claimed in  claim 3 , wherein
 in a state where the top stack is not depressed toward the bottom stack, the first conductive contact slightly touches the second conductive contact without turning on the bottom switch, and   in response to the top stack being depressed toward the bottom stack, the first conductive contact is caused to touch the second conductive contact firmly to turn on the bottom switch.   
     
     
         5 . The cantilever force sensor as claimed in  claim 3 , wherein
 in a state where the top stack is not depressed toward the bottom stack, the first conductive contact is slightly apart from the second conductive contact, and   in response to the top stack being depressed toward the bottom stack, a second side opposite to the first side of the bottom stack moves down using the second spacer as a fulcrum and causes the first conductive contact to touch the second conductive contact firmly to turn on the bottom switch.   
     
     
         6 . The cantilever force sensor as claimed in  claim 1 , wherein
 the second stack comprises:
 a second substrate, 
 a second piezo layer, and 
 a second electrode between the second substrate and the second piezo layer in the thickness direction, and 
   along the thickness direction, the first spacer overlaps the first substrate and the second substrate, without overlapping the first electrode, the first piezo layer, the second electrode and the second piezo layer.   
     
     
         7 . The cantilever force sensor as claimed in  claim 6 , wherein
 as seen along the thickness direction, the first spacer has a shape of a segment of a circle.   
     
     
         8 . The cantilever force sensor as claimed in  claim 1 , wherein
 the second stack comprises:
 a second substrate, 
 a second piezo layer, and 
 a second electrode between the second substrate and the second piezo layer in the thickness direction, and 
   along the thickness direction, the first spacer overlaps the first substrate, the first electrode, the first piezo layer and the second substrate, without overlapping the second electrode and the second piezo layer.   
     
     
         9 . The cantilever force sensor as claimed in  claim 1 , wherein
 along the thickness direction, the first spacer overlaps the second spacer.   
     
     
         10 . The cantilever force sensor as claimed in  claim 9 , wherein
 the second stack comprises:
 a second substrate, 
 a second piezo layer, and 
 a second electrode between the second substrate and the second piezo layer in the thickness direction, and 
   along the thickness direction, the second spacer overlaps the first substrate, the first electrode, the first piezo layer, the second substrate, the second electrode and the second piezo layer.   
     
     
         11 . A cantilever force sensor, comprising a top stack, a bottom stack, and a first spacer, wherein
 the first spacer is configured, in a thickness direction of the force sensor, between the top stack and the bottom stack, and is configured in a first side of the force sensor,   a second side, opposite to the first side, of the top stack, is cantilevered from the bottom stack,   in response to the top stack being depressed toward the bottom stack, the second side of the top stack moves down using the first spacer as a fulcrum,   the top stack comprises:
 a top substrate, 
 a top piezo layer, and 
 a top electrode between the top substrate and the top piezo layer in the thickness direction, 
   the bottom stack comprises:
 a printed circuit board having, on a top side thereof, a conductive contact, and 
 a bottom piezo layer on the top side of the printed circuit board, wherein the bottom piezo layer is wider than the conductive contact and covers the conductive contact. 
   
     
     
         12 . The cantilever force sensor as claimed in  claim 11 , wherein
 along the thickness direction, the first spacer overlaps the top substrate and the printed circuit board, without overlapping the top electrode, the top piezo layer, the conductive contact and the bottom piezo layer.   
     
     
         13 . The cantilever force sensor as claimed in  claim 12 , wherein
 as seen along the thickness direction, the first spacer has a shape of a segment of a circle.   
     
     
         14 . The cantilever force sensor as claimed in  claim 11 , wherein
 along the thickness direction, the first spacer overlaps the top substrate, the top electrode, the top piezo layer, the printed circuit board and the bottom piezo layer.   
     
     
         15 . The cantilever force sensor as claimed in  claim 11 , wherein
 along the thickness direction, the first spacer overlaps the top substrate, the top electrode, the top piezo layer, the printed circuit board, without overlapping the bottom piezo layer.   
     
     
         16 . The cantilever force sensor as claimed in  claim 11 , wherein
 along the thickness direction, the first spacer overlaps the top substrate, the printed circuit board and the bottom piezo layer, without overlapping the top electrode and the top piezo layer.   
     
     
         17 . A cantilever force sensor, comprising a top stack, a bottom stack, and a first spacer, wherein
 the first spacer is configured, in a thickness direction of the force sensor, between the top stack and the bottom stack, and is configured in a first side of the force sensor,   a second side, opposite to the first side, of the top stack, is cantilevered from the bottom stack,   in response to the top stack being depressed toward the bottom stack, the second side of the top stack moves down using the first spacer as a fulcrum,   the top stack comprises:
 a top substrate, 
 a top piezo layer, and 
 a top electrode between the top substrate and the top piezo layer in the thickness direction, 
   the bottom stack comprises:
 a bottom substrate, and 
 a bottom piezo layer on a top side of the bottom substrate, 
   along the thickness direction, the first spacer overlaps the top substrate and the bottom substrate, without overlapping the top electrode, the top piezo layer and the bottom piezo layer, and   as seen along the thickness direction, the first spacer has a shape of a segment of a circle.   
     
     
         18 . The cantilever force sensor as claimed in  claim 17 , wherein
 at least one of the top piezo layer or the bottom piezo layer is made of a material selected from the group consisting of piezo-electric material, triboelectric material, resistive material, and dielectric material.   
     
     
         19 . The cantilever force sensor as claimed in  claim 17 , further comprising:
 a bottom switch which comprises:
 a first conductive contact configured on a bottom side of the bottom stack; 
 a second conductive contact aligned with the first conductive contact, and configured on the top side of a third substrate; and 
   a second spacer which is configured between the bottom stack and the third substrate in the thickness direction, and configured in the first side of the force sensor,   wherein   the first conductive contact and the second conductive contact are configured in the second side of the force sensor,   in a state where the top stack is not depressed toward the bottom stack, the bottom switch is not turned on, and   in response to the top stack being depressed toward the bottom stack, the first conductive contact touches the second conductive contact to turn on the bottom switch.   
     
     
         20 . The cantilever force sensor as claimed in  claim 17 , wherein
 the bottom substrate is a printed circuit board having, on the top side thereof, a conductive contact, and   the bottom piezo layer is wider than the conductive contact and covers the conductive contact.