Contact and electrical connecting apparatus

1. A contact comprising:

a plate-shaped first plunger contacting one member;

a plate-shaped second plunger contacting the other member with a large area in a state of being overlapped with the first plunger at the plates and conducting electricity between the one member and the other member in cooperation with the first plunger; and

a compression coil spring which is a member coupling the first plunger with the second plunger in a state where contact pieces thereof are in opposite directions from each other, covering outer circumferences of coupling portions of the first plunger and the second plunger, abutting on spring receiving portions of the respective plungers, and supporting the respective plungers to be relatively slidable; wherein,

as for the compression coil spring, an intermediate portion thereof is a compression coil spring having a large diameter, and both end portions thereof are constituted by adhesion small-diameter portions which are adhesion coil springs having small diameters, and wherein

an inside diameter of each of the adhesion small-diameter portions at both end portions is set to be equal to or smaller than a diameter of a circumscribed circle circumscribing a cross-sectional shape of the respective coupling portions of the first plunger and the second plunger in a state of being overlapped; wherein

one of the first plunger and the second plunger, and two of the other are provided, the coupling portion of the one plunger is configured to be sandwiched between the coupling portions of the other two plungers, and a width dimension of the coupling portion of the one plunger is larger than width dimensions of the coupling portions of the other two plungers.

2. The contact according to claim 1 , wherein each of the first and second plungers includes the coupling portion and the contact piece having a larger width dimension than that of the coupling portion, and the spring receiving portion is a step provided at a border part between the coupling portion and the contact piece.

3. The contact according to claim 1 , wherein the other two plungers slide independently of each other in a state of sandwiching the one plunger.

4. The contact according to claim 1 , wherein tip ends of the contact pieces of the other two plungers have tapered surfaces in mutually opening directions.

5. The contact according to claim 1 , wherein the tip ends of the contact pieces of the other two plungers are provided with recesses, each of which is formed in two cutting edge shapes.

6. The contact according to claim 1 , wherein the coupling portion of each of the first and second plungers is provided at an end portion opposite the spring receiving portion with a falling preventing portion.

7. The contact according to claim 1 , wherein the contact piece of the first plunger or the second plunger is provided with a plurality of projections, between which a slit is provided to separate the respective projections.

8. The contact according to claim 7 , wherein by the slit are formed a plurality of projection bar portions respectively provided at tip end portions with the respective projections, and the respective projection bar portions support the respective projections and are flexed freely.

9. An electrical connecting apparatus contacting electrodes of a device under test and performing a test, comprising:

contacts disposed at positions corresponding to the respective electrodes of the device under test and contacting the respective electrodes for electrical conduction,

wherein as the contacts are used the contacts according to claim 1 .