thumb|300px|The Seiko Spacewalk is a limited edition Spring Drive model, designed specifically for use in space
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 (now a part of Epson after a 1985 merger). Specified to one second accuracy per day, 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. along with automatic and/or stem winding to store energy, just as in a mechanical watch. in total, no fewer than 230 patents have been applied worldwide for this movement. Initial development was hindered by the high energy consumption of the reference quartz crystal and integrated circuit another attempt in 1993 was also unsuccessful for the same reason.
The Spring Drive movement was announced publicly in 1997 and presented at the 1998 Basel Watch Fair. The first non-limited model was released in Japan in 2002.
Early models, manual wind and 48h power reserve:
- 7R68 : 30 jewels, date.
- 7R78 : 30 jewels, date.
- 7R88 : 30 jewels, date.
- 7R99 : 32 jewels.
Current calibers with standard features. Time accuracy: monthly rate within ±15 sec (equivalent to a daily rate of ±1 sec), and power reserve (72h) indicator. (Exceptions apply to some models.)
- 5R64 : 32 jewels, date, small seconds hand.
- 5R65 : 30 jewels, date.
- 5R66 : 30 jewels, date, GMT.
- 5R67 : 30 jewels, Moon Phase indicator.
- 5R77 : 30 jewels, Moon Phase indicator.
- 5R85 : 49 jewels, date, Chronograph, Izul.
- 5R86 : 50 jewels, date, GMT, Chronograph, Spacewalk.
- 7R06 : 88 jewels, manual winding, Sonnerie. (Produced by the Micro Artist Studio) (Produced by the Micro Artist Studio)
- 9R86 : 50 jewels, date, GMT, Chronograph.