Method of manufacturing optical element with lens-barrel
The invention relates to a method of manufacturing an optical element with a lens barrel, in which an optical raw material is placed on a placement portion projecting toward the center of the lens barrel from the inner peripheral surface thereof, and assuming that a distance between the opposing ends of the projection of the placement portion is L 1 , the outside diameter of the optical raw material is L 2 , the inside diameter of the lens barrel portion which is positioned close to and above the placement portion and to which the perimeter of the optical element obtained after forming is joined is L 3 , and the inside diameter of the smallest opening on the upper end side of the lens barrel is L 4 , design is performed to satisfy a relation of L 1 <L 2 <L 3 <L 4 . Further, a wall surface providing said inside diameter L 3 is extended to a predetermined length in parallel with the optical axis to configure a straight wall surface, and the optical raw material placed on the placement portion is pressed by a pair of shaping dies consisting of an upper die and a lower die, causing the outer edge of the raw material to be joined to the straight wall surface of the inside surface of the lens barrel, wherein when the outside diameter of the optical element obtained after forming is assumed to be L 5 , the configuration is performed to satisfy L 4 <L 5 .
1. A method of manufacturing an optical element with a lens barrel, in which a heat-softened optical raw material is heat compressed by a shaping die so as to be integrally joined to the inside of a lens barrel, comprising the steps of:
placing the optical raw material on a placement portion projecting toward the center of the lens barrel from the inner peripheral surface thereof,
performing design to satisfy a relation of L 1 <L 2 <L 3 <L 4 ,
herein, L 1 is a distance between the opposing ends of the projection of the placement portion, L 2 is the outside diameter of the optical raw material, L 3 is the inside diameter of the lens barrel portion which is positioned close to and above the placement portion and to which the perimeter of the optical element obtained after forming is joined, and L 4 is the inside diameter of the smallest opening on the upper end side of the lens barrel,
extending a wall surface providing said inside diameter L 3 to a predetermined length in parallel with the optical axis to shape a straight wall surface, and
pressing the optical raw material placed on the placement portion by a pair of shaping dies consisting of an upper die and a lower die to cause the outer edge of the raw material to be joined to the straight wall surface of the inside surface of the lens barrel, wherein L 4 <L 5 is satisfied, herein L 5 is the outside diameter of the optical element obtained after forming.
2. The method of manufacturing an optical element with a lens barrel according to claim 1 , wherein the inner peripheral surface above the lens barrel portion to which the optical element is joined is shaped in an oppositely tapered shape.
3. The method of manufacturing an optical element with a lens barrel according to claim 1 , the opening inside diameter L 4 is shaped to be enclosed with a projection projecting from the inside surface of the lens barrel.