Keyboard switch assembly
First Claim
1. A key-board switching unit which comprises (a) a printed circuit board provided with a plural number of pairs of fixed contact points on a first surface thereof, and (b) an insulating covering sheet member having a bottom surface provided with a multiplicity of electroconductive members formed of a pressure-sensitive electroconductive rubber forming movable contact points, said bottom surface arranged facing said first surface, the size of each of the electroconductive members being sufficiently small in comparison with the dimensions of the fixed contact points, the electroconductive members forming the movable contact points are distributed over the whole bottom surface and are supported relative to the printed circuit board so that a switch is formed with each pair of the fixed contact points on the printed circuit board and at least one movable contact point with the density of distribution of the electroconductive members forming the movable contact points being sufficiently large to ensure that at least one electroconductive member is contacted with the fixed contact points to bridge therebetween when the covering sheet member is pressed toward the printed circuit board due to the pressure sensitive electroconductive material forming the electroconductive members.
1 Assignment
0 Petitions
Accused Products
Abstract
A key-board switching unit for electronic instruments is constructed with a printed circuit board provided with a plural number of pairs of fixed contact points on the surface and an insulating covering sheet member mounted on or above the printed circuit board and provided on the bottom surface with movable contact points to face the fixed contact points. Different from conventional units in which exact correspondence in the positions of the fixed and movable contact points is required with time- and labor-consuming assembling works, the movable contact points in multiple numbers distributed over the whole bottom surface of the covering sheet member in such a manner that, when the covering sheet member is pushed and depressed at the switching position, the fixed contact points forming a pair of the counter-electrodes are contacted and electrically connected with at least one movable contact point even without exact positioning of the covering sheet member and the printed circuit board to give a great advantage of the increased productivity in the works of assembling. In particular, the movable contact points are formed of a pressure-sensitive electroconductive rubber.
160 Citations
7 Claims
- 1. A key-board switching unit which comprises (a) a printed circuit board provided with a plural number of pairs of fixed contact points on a first surface thereof, and (b) an insulating covering sheet member having a bottom surface provided with a multiplicity of electroconductive members formed of a pressure-sensitive electroconductive rubber forming movable contact points, said bottom surface arranged facing said first surface, the size of each of the electroconductive members being sufficiently small in comparison with the dimensions of the fixed contact points, the electroconductive members forming the movable contact points are distributed over the whole bottom surface and are supported relative to the printed circuit board so that a switch is formed with each pair of the fixed contact points on the printed circuit board and at least one movable contact point with the density of distribution of the electroconductive members forming the movable contact points being sufficiently large to ensure that at least one electroconductive member is contacted with the fixed contact points to bridge therebetween when the covering sheet member is pressed toward the printed circuit board due to the pressure sensitive electroconductive material forming the electroconductive members.
Specification