Abstract: An optical fiber connector plug protecting cap is configured to be mounted to an optical fiber connector plug having a ferrule with an insertion hole into which an optical fiber is inserted and a holding member for holding the ferrule. The optical fiber connector plug protecting cap has a tubular cap member made of a resin material and configured to be fitted to a tip opening of the holding member to cover a tip portion of the ferrule in a non-contacting state, and a strap member having first and second end portions and comprised of an elastic body having a relatively greater flexibility than the cap member. The cap member has a connecting part having a locking hole for locking the first end portion of the strap member. The first end portion of the strap member has an engagement protrusion for engagement with the locking hole in a state in which the first end portion extends through the locking hole.

Abstract: A collar member and a ferrule with improved dimensional precision, a simplified manufacturing process, and reduced cost. The collar member is provided at the rear end of a ferrule tubular body that has an optical fiber insertion hole to which an optical fiber is inserted. The collar member has a metal pipe member with an inner diameter sufficient to slidably accommodate the ferrule tubular body, a collar portion integrally molded of plastic on the outer periphery of the pipe member, the collar portion having a key groove on its outer peripheral surface for positioning with respect to an optical connector housing, a coated fiber holding portion integrally molded of plastic in the rear half of the pipe member with an inner diameter smaller than that of the pipe member, for receiving therein a coated optical fiber.

Abstract: An optical fiber connector plug protecting cap mounted to an optical fiber connector plug having an ferrule to which an optical fiber is insertion-mounted and a holding member for holding the ferrule, including a resin-made cap member fitted to a tip opening of the holding member and covering a tip portion of the ferrule in a non-contacting state, and a strap member consisting of an elastic body relatively having more flexibility than the cap member, wherein the cap member is provided with a lock hole for locking one end portion of the strap member in an insertion state and the one end portion of the strap member is provided with an engagement protrusion engaging with the lock hole in a state that the one end portion has been passed through the lock hole to thereby make it engageable, and wherein an end portion side from the engagement protrusion of the strap member becomes a pinching portion capable of being pinched in order that the engagement protrusion is locked to an outer edge portion of the lock hole.