Patent ID: 7538568

Claim:
A probe, comprising: a conductive plunger received inside a cylindrical conductive barrel in which the plunger being capable of moving backward and forward; and an urging coil spring for pushing a rear end of the plunger also received inside the barrel so as to urge a front end of the plunger out of an opening at one end of the barrel; said plunger including a conductive coil spring said coil spring being compressible and having a first end and a second end; said conductive coil spring is inserted between an inner circumference of the barrel and an outer circumference of the plunger; and said conductive coil spring is provided for stabilizing electrical contact between said barrel and said plunger without urging said plunger, wherein a first protrusion and a second protrusion are disposed so as to respectively protrude towards the center from the inner wall of said barrel, in such a manner that said first protrusion is provided inside said barrel towards the side of said open end of said barrel for engaging said conductive coil spring between said first end and said second end; and said second protrusion is provided in an inner wall in the vicinity of the center in the longitudinal direction of said barrel for engaging a large-diameter portion formed at the side of the rear end of said plunger.