The idea of Spring Drive was conceived in 1977 by an engineer at SEIKO EPSON's Suwa plant in Japan.
There are 3 key innovations make Spring Drive possible.

Tri-synchro regulator Mainspring Magic Lever

An entirely new spring was created using a new high elastic material called Spron 510 to create more power. The result is a mainspring can deliver more power more smoothly and longer - Spring Drive has a power reserve of 72 hours.

Spron 510 is the registered trademark of Seiko Instruments Inc.

The electrical power required by the Quartz oscillator and the I.C. is generated by the electro-magnetic coil. The energy releases from the Mainspring, passes through the wheel train and exchanges the mechanical energy for the electricity.

The new Magic Lever system allows for more efficient transmission of the rotor's power to the mainspring. It is fitted directly to the shaft of the rotor and thus creates more efficient winding of the spring. This new system is 30% more efficient than traditional automatic winding systems.

Using the same power source - Wearer's movement
Using the same power storage - Mainspring
Using the same power path - Wheel train

The only one difference is the "source of time " and the control mechanism - Tri-synchro regulator.
This new concept brings us a high accuracy of time display --- ±1sec / day.

Grand Seiko: -3 +5 sec / day

C.O.S.C.: -4 +6 sec / day

Quartz: ±1 sec / day

C.O.S.C. Quartz: ±0.07 sec

Atomic Clock: 0.000000001 sec / day

Therefore, some people say that Spring Drive is a quartz watch.

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