Initiator including a zone of weakness

An electropyrotechnic initiator for use as a component of a gas generator for an automotive safety device including an airbag or pretensioner, the gas generator having an annular shaped electropyrotechnic charge, the initiator comprising:

• an ignition support;
• an electrical initiation system connecting the ignition support to a source of electricity;
• and
• a cap containing at least one explosive composition, the cap being of a generally cylindrical shape having an open first end connected to the ignition support, and opposite second end that is closed by an end wall, and a peripheral side wall having at least one zone of weakness, the at least one zone of weakness extending along a non-closed trace and over a portion only of the side wall, the non-closed trace shaped such that after a zone of weakness has opened, a fragment of the wall situated between two adjacent ends of the trace remains attached to the wall upon ignition of the explosive composition, and wherein the fragment acts as a deflector to direct gases generated upon the ignition to be directed toward the electropyrotechnic charge when the initiator is disposed inside the charge.