Portable timepiece and method of fabricating crown provided to the timepiece

A portable timepiece, wherein a case band including a timepiece movement is attached with a pipe having a male screw portion disposed on an outer side of the case band, a crown connected to a hand setting stem for transmitting a rotational force to the timepiece movement is brought in mesh with the male screw portion attachably and detachably, and the crown is held so as not to be rotated by bringing the crown in mesh with the male screw portion, the crown comprising:

• a crown shaft including a rotational force receiving portion of a deformed shape formed with a first engaging portion at an outer periphery thereof, having a diameter larger than a diameter of the male screw portion, arranged at outside of the pipe and cooperatively moving the hand setting stem in a state of releasing the crown and the male screw portion from being brought in mesh with each other;
• a crown head, wherein other end of a head main body opening one end thereof is closed by a closed portion, further, an inner periphery of the head main body includes a rotational force transmitting portion, a ring mounting face in a circular shape, and an inner peripheral face in a circular shape, the rotational force transmitting portion is constituted by a shape having a second engaging portion engaged with and detached from the first engaging portion and fitted attachably and detachably to the rotational force receiving portion, the ring mounting face is formed on the one end side from the rotational force transmitting portion by a diameter equal to or larger than a maximum diameter of the rotational force transmitting portion, and the inner peripheral face is formed on the other end side from the rotational force transmitting portion by a diameter equal to or larger than the maximum diameter of the rotational force transmitting portion and a diameter brought into outer contact with the first engaging portion;
• a screw ring including a female screw portion attachably and detachably brought in mesh with the male screw portion and having a diameter smaller than a diameter of the rotational force receiving portion and mounted to the ring mounting face;
• and
• an elastic member squeezed between the crown head and the crown shaft for urging the crown head in a direction of being separated from the case band.

A method of fabricating a crown provided to a portable timepiece;

• wherein for a head material in which other end of a head main body opening one end is closed by a closed portion, and which includes a first space in a circular shape partitioned by an inner peripheral face of a circular shape having a diameter equal to or larger than a maximum diameter of a worked projected portion between the worked projected portion provided continuously in a peripheral direction at an inner periphery of the head main body and the closed portion, and including a second space in a circular shape partitioned by a ring mounting face in a circular shape having a diameter equal to or larger than the maximum diameter of the worked projected portion between the worked projected portion and the opened one end of the head main body, by a work member reaching the first space by crossing the worked projected portion from the second space, the first engaging portion is worked into the worked projected portion, and a crown head formed with a rotational force transmitting portion in a deformed shape is prepared;
• wherein for a crown shaft material including a shaft main portion and a shaft end portion in a circular shape expanded integrally from an outer periphery of one end portion of the shaft main portion, a second engaging portion brought into inner contact with the inner peripheral face is worked at an outer peripheral portion of the shaft end portion by a work member crossing the outer peripheral portion of the shaft end portion by being moved in an axial direction of the crown shaft material, thereby, a crown shaft formed with a rotational force receiving portion of a shape of being attachably and detachably fitted with the rotational force transmitting portion is prepared;
• wherein a ring material is worked by a work member penetrating the ring material in the axial direction by crossing an inner peripheral portion of the ring material, thereby, a screw ring formed by including a female screw portion having a diameter smaller than a diameter of the rotational force receiving portion is prepared;
• wherein the crown head is covered to the crown shaft and the rotational force receiving portion is contained in the first space while squeezing an elastic member in a compressed state between the closed portion of the crown head and the crown shaft;
• and
• wherein thereafter, the screw ring is mounted to the ring mounting face by press-fitting the screw ring into the second space.