Spring Drive

Spring Drive is a name given to a series of watch movements produced by Epson in Shiojiri. The concept of using a mainspring to power a quartz timing package was first conceived in 1977 by Yoshikazu Akahane (赤羽 好和) at Suwa Seikosha^[1] (now a part of Epson after a 1985 merger).^[2] Specified to one second accuracy per day,^[3] the movement uses a conventional gear train as in traditional mechanical watches, but rather than an escapement and balance wheel, instead features Seiko's Tri-synchro Regulator system in which power delivery to the watch hands is regulated based on a reference quartz signal.^[3]

Commercially released in 1999,^[2] the movement is found in watches distributed by the Seiko Watch Corporation, including its Credor, Grand Seiko, Presage, and Prospex brands.