Contact terminal having a plunger pin

Abstract

A contact terminal having a main body case and a plunger pin received in an elongate hole formed in the main body case is provided. The plunger pin is a round bar provided with a step and includes a small diameter portion including the protrusion end portion and a large diameter portion that slides on a surface of the hole to freely move in a longitudinal direction thereof. A cut space is formed to extend from an end of the large diameter portion so as to leave at least a part of a side surface portion of the large diameter portion and the cut space receives an insulation ball including at least an insulation surface. A coil spring is arranged between the hole and the insulation ball to press the protrusion end portion of the plunger pin such that the protrusion end portion protrudes from the main body case.

What is claimed is: 
     
         1 . A contact terminal for providing an electrical connection by contacting a protrusion end portion of a plunger pin protruding from a main body case having an elongate hole with a target portion, the contact terminal comprising the main body case and the plunger pin,
 wherein said plunger pin received in said elongate hole of said main body case comprises a round bar with a step, having a small diameter portion including said protrusion end portion and a large diameter portion being able to slide on an inner surface of said elongate hole of said main body case to freely move in a longitudinal direction thereof, and   wherein said plunger pin is pressed by a coil spring in a direction that makes a minute angle with the center axis of the main body case to protrude said protrusion end portion of said plunger pin from said main body case since said coil spring presses a ball face of a press member to an oblique pit portion having a cone surface-shape on said large diameter portion.   
     
     
         2 . The contact terminal according to  claim 1 , wherein a center axis of said oblique pit portion is shifted from a center axis of said plunger pin. 
     
     
         3 . The contact terminal according to  claim 2 , wherein the ball face of said press member is provided an insulation surface. 
     
     
         4 . The contact terminal according to  claim 3 , wherein said press member comprises a ball. 
     
     
         5 . The contact terminal according to  claim 4 , wherein the oblique pit portion is in a bottom portion of a sac hole of the large diameter portion.