Abstract: A plug engagement pin provided on each side of the plug connector is inserted into an engagement section of a hook and locked there when the shaft is rotated. The hook is fixed to a rotatable shaft provided for the receptacle connector and includes a projection. If the plug connector is inserted in a slanted state, the projection of the hook prevents the pin from being rotated.

Abstract: A connector has a board with a plurality of contact pads electrically connected to a plurality of signal lines on one side. The connector also has a modularized structural unit on the other side. The structural unit includes a plurality of spring contacts as the mate to which the contact pads are electrically connected. The connector further has a shaft provided near the central part of the board and perpendicular to the board and a roller provided on the structural unit. To combine the contact pads and the contacts, the shaft is rotated to cause the rollers to engage with a projecting part provided at the tip of the shaft. The roller is provided higher in position than the circuit board on which the connector is to be mounted.