Mechanical lock mechanism and injector head using the mechanism

The present invention relates to a mechanical locking mechanism and an injector head employing the mechanism, and more specifically, it relates to an improvement of a structure for attaining miniaturization of a mechanical locking mechanism and an injector head employing the mechanism. This injector head comprises a plunger capable of reciprocating in a direction of movement of a piston in a syringe , a plunger drive for converting rotary motion of a plunger motor to linear motion in order to supply reciprocation to this plunger , and a safety device as safety means for restraining rotation of a rotary shaft of the plunger motor when the plunger moves beyond a predetermined position. Thus, it is possible to provide a medical injector head attaining miniaturization and simplification of the apparatus while keeping a mechanical safety mechanism.