Spring Drive
The Spring Drive is a novel watch movement that was developed by Seiko Epson.
It uses a mainspring, barrel, automatic winder and stem winding like in a mechanical watch to store the watch energy. It replaces the conventional escapement with a device that Seiko calls a Tri-synchro Regulator to regulate the unwinding of the mainspring. The regulator controls the use of the three forms of energy used in the Spring Drive mechanism; the mechanical power of the mainspring, the electrical energy generated from this mechanical power, and the electromagnetic energy that governs the rotation of the glide wheel. The energy produced by the glide wheel is used to power a control circuit and quartz crystal oscillator, which in turn regulates the electro-mechanical braking of the glide wheel. The glide wheel brakes the gears eight times per second to control the release of energy from the mainspring providing an electronically controlled, mechanically powered escapement and controlling the release of the stored energy which drives the watch works. The Tri-synchro Regulator's innovations result in a watch where the hands do not tick as with a watch with a periodic escapement; rather, they glide. This is because the movement never stops as in a traditional escapement, it is slowed to the proper speed by the brake. The manufacturer claims that the watch is accurate up to 1 second per day.
It's used on the Spring Drive International collection and in some watches of Grand Seiko, CREDOR, GALANTE, IZUL, PROSPEX series. Complications include moon phase, power reserve, chronograph, sonnerie, GMT and calendar functions. These watches are fairly expensive, with the least complicated models costing several thousand dollars. The top of the line Credor Sonnerie in Rose Gold is over $150,000 and can be considered a grande complication.
History
The design was first conceived in 1977, and patents were applied for in 1982. The movement was announced publicly in 1997, presented at the 1998 Basel Watch Fair and first appeared commercially in the Credor 'luxury watch' range as a limited edition in 1999. A version which included an automatic winder was shown in Seiko models at the 2005 Basel Watch Fair. The internationally available Seiko models were officially launched at the Musée d'Orsay in Paris on September 14, and went on sale the following day.
Swatch's research company ASULAB has developed a conceptually similar movement called the High Precision Mechanics calibre. [1]. Several proof of concept prototypes based on the ETA 2824 calibre were produced in the late 1990's.
Seiko's efforts with the Spring Drive predates ASULAB's HPM, since Spring Drive watches were already on sale in 1999.
Movement calibers
- 5R64 : 32 stones, day, small seconds hand.
- 5R65 : 30 stones, day.
- 5R66 : 30 stones, day, GMT.
- 5R67 : 30 stones, Moon Phase indicator.
- 5R77 : 30 stones, Moon Phase indicator.
- 5R86 : 50 stones, day, GMT, Chronograph.
- 7R06 : 88 stones, Sonnerie.
- 7R68 : 30 stones, day.
- 7R88 : 30 stones, day.
- 7R99 : 32 stones.
- 9R65 : 30 stones, day.
- 9R66 : 30 stones, day, GMT.
- 9R86 : 50 stones, day, GMT, Chronograph.
Standard features:
- Time accuracy: Monthly rate within ±15 sec (equivalent to a daily rate of ±1 sec)
- Power reserve(72h) indicator.