Plug and receptacle

A receptacle having an opening into which a plug is inserted, said receptacle comprises:

• a recess in the inner wall of said opening,
• wherein said plug includes:
• an insulating plug frame portion having a cylindrical shape;
• an insulating header portion of a flat plate shape for being housed in said plug frame portion and exposed at its forward end to said receptacle;
• a pair of lock arms supported on the both side faces of said plug frame portion;
• and an insulating plug shutter for moving back and forth in the inserting/extracting directions with respect to said plug frame portion,
• wherein said header portion has a forward end for being inserted into the opening of said receptacle and includes contacts juxtaposed on its two faces,
• wherein each of said paired lock arms includes:
• a body extending toward said receptacle;
• a hook portion formed on the forward end side of said body and protruding from said plug frame portion for engaging in the recess of said receptacle;
• and an action member formed on the rearward end side closer than said hook portion, and
• wherein said plug shutter includes:
• a cylindrical shutter frame portion for covering said header portion;
• a pair of lever portions formed on the both side faces of said shutter frame portion and protruding from said plug frame portion;
• and a pair of projections formed on the both side faces of said shutter frame portion and disposed to confront said lock arms individually,
• whereby when said plug shutter is moved backward of said receptacle by holding said lever portions with the fingers, the projections of said plug shutter push the action members of said lock arms inward to elastically deform said lock arms inward thereby to move the hook portions of said lock arms inward.