Calibre record · Spring Drive (mainspring with quartz-regulated glide wheel)
Seiko Spring Drive (7R, 9R, 5R families)
Documented
A mainspring drives the train as in a mechanical watch, but the escapement is replaced by a 'glide wheel' braked electromagnetically under control of a quartz crystal — the 'Tri-synchro regulator'. The seconds hand sweeps continuously.
- Manufacturer
- Seiko
- Type
- Spring Drive (mainspring with quartz-regulated glide wheel)
- Winding
- Automatic or manual, by family
- Production
- 1999–present
- Country
- Japan
- Diameter
- Undocumented here
- Height
- Undocumented here
- Jewels
- 30 (9R65)
- Frequency
- 32,768 Hz reference crystal
- Power reserve
- 72 h (9R65)
- Oscillator / escapement
- Quartz crystal oscillator
- Complications
- By calibre: date, GMT, power reserve, chronograph (5R86)
Figures are those commonly published for the standard version; individual versions and grades differ. “Undocumented here” means the value has not yet been confirmed for this record.
History
Conceived by Seiko engineer Yoshikazu Akahane in 1977, Spring Drive reached the market in 1999 after decades of work on low-power circuits. The 9R65 of 2004 introduced it into Grand Seiko.
