Patent document No. 1 discloses a detachable connector between a face piece and a filter of a breathing apparatus comprising a bayonet connection mechanism for connecting a pair of members by pushing and twisting operation.
The bayonet connection mechanism comprises a male side member provided with a lug, a female side member provided with a lug or an L-shaped slot and a spring, wherein pushing force is applied to the male side member so as to push the lug of the male side member into the L-shaped slot of the female side member or to the rear near one end of the lug of the female side member, twisting force is applied to the male side member so as to twist the lug of the male side member along the slot or the lug of the female side member, and then the pushing force and the twisting force are released from the male side member so as to force the lug of the male side member against a side surface of the L-shaped slot or a rear surface of the lug of the female side member by means of the biasing force of the spring, thereby connecting the male side member with the female side member. The L-shaped slot of the female side member is provided with a projection near an entrance and the lug of the female side member is provided with a projection near aforesaid one end. The projection extends in the direction of the pushing force applied to the male side member. Thus, the lug of the male side member cannot be released from engagement with the slot or the lug of the female side member by simple twisting of the male side member in the releasing direction.