US 12,078,965 B2
Balance with hairspring, movement, mechanical watch, and method for manufacturing balance with hairspring
Akihiro Sawada, Matsumoto (JP); and Yosuke Sasaki, Shiojiri (JP)
Assigned to SEIKO EPSON CORPORATION, (JP)
Filed by Seiko Epson Corporation, Tokyo (JP)
Filed on Nov. 12, 2021, as Appl. No. 17/454,679.
Claims priority of application No. 2020-189610 (JP), filed on Nov. 13, 2020.
Prior Publication US 2022/0155727 A1, May 19, 2022
Int. Cl. G04B 17/06 (2006.01)
CPC G04B 17/063 (2013.01) [G04B 17/066 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A balance with a hairspring comprising:
a balance shaft rotatably supported by a support member;
a collet fixed to the balance shaft; and
a metal hairspring fixed to the collet, wherein
the hairspring includes
an inner end portion fixed to the collet,
a first winding portion continuously formed from the inner end portion and formed along a Grossmann curve, and
a second winding portion continuously formed from the first winding portion and formed along an Archimedes' spiral, and
the collet includes
a fixing portion to which the inner end portion of the hairspring is fixed, and
an outer peripheral shape portion arranged at a position facing an inner surface of the first winding portion and configured to form the first winding portion into a shape of the Grossmann curve.