Abstract: An insert pipe is fitted on an outer circumferential surface of a front end of a ferrule provided with a core wire receiving bore in an axial center thereof, and a small-diameter tubular portion is insert molded coaxially with the insert pipe 4 around the core receiving bore adjacent to the front end, a thin-walled plastic portion being formed inside the small-diameter tubular portion. A plastic reservoir may be provided in a part of the plastic ferrule remote from the front end of the core wire receiving bore. The provision of the thin-walled plastic portion and/or the plastic reservoir prevents the tapering of the core wire receiving bore due to thermal shrinkage following the injection molding process.

Abstract: The ferrule of the present invention comprises a ferrule main body including an insert pipe defining an outer circumferential surface of said ferrule main body and a molded plastic member disposed inside said insert pipe integrally therewith and having an optical fiber receiving bore in an axial center thereof; and a tubular base portion molded onto a rear end of the ferrule main body. Because the outer diameter of the ferrule main body is defined by the insert pipe, the rigidity, circularity and dimensional precision of the outer diameter can be improved. Because the base portion is molded separately from the ferrule main body, the manufacturing process can be simplified and the production cost can be reduced.

Abstract: In a multi-core ferrule for mounting two or more optical fiber cores, the core receiving bore is defined by a plurality of bore parts each having a circular cross section which are arranged in mutually parallel and contiguous relationship. Because the core receiving bore of this ferrule is formed by closely arranging a corresponding number of core receiving bore parts each having a circular cross section one next to another, the size of the outer diameter is minimized, and the ferrule is therefore adapted for a larger number of cores and a more compact design. Preferably, the bore parts communicate each with an adjacent one of the bore parts via a longitudinally extending narrow gap. The core pins for defining the core receiving bore are arranged in a mutually parallel and contiguous relationship so that they support each other against bending or other damages that could be caused by the pressure of the injected molding plastic material.

Abstract: An insert pipe is fitted on an outer circumferential surface of a front end of a ferrule provided with a core wire receiving bore in an axial center thereof, and a small-diameter tubular portion is insert molded coaxially with the insert pipe 4 around the core receiving bore adjacent to the front end, a thin-walled plastic portion being formed inside the small-diameter tubular portion. A plastic reservoir may be provided in a part of the plastic ferrule remote from the front end of the core wire receiving bore. The provision of the thin-walled plastic portion and/or the plastic reservoir prevents the tapering of the core wire receiving bore due to thermal shrinkage following the injection molding process.