When Mechanical Watchmaking Met Quartz Precision
There are moments in watchmaking when two apparently opposing ideas come together and create something genuinely new.
Spring Drive is one of them.
It has a mainspring. It has a gear train. There is no battery driving the watch and no conventional electric motor moving the hands.
Yet at the heart of its regulation sits a quartz crystal.
The result is neither a conventional mechanical movement nor a conventional quartz movement, but one of Seiko's most remarkable contributions to modern watchmaking.
And its story began with one engineer asking a rather difficult question.
An Engineer's Idea
In the late 1970s, quartz had already transformed watchmaking.
Seiko had played an enormous part in that transformation, having introduced the Quartz Astron in 1969. The extraordinary accuracy that electronic timekeeping could offer was becoming increasingly clear.
But engineer Yoshikazu Akahane wondered whether that accuracy could be achieved without abandoning the traditional mainspring.
His idea was deceptively simple: create a watch powered mechanically by a mainspring but regulated electronically using quartz.
In other words, take something from both worlds.
Akahane had been involved with Seiko's advanced quartz technology, including Twin Quartz, but his new idea would prove considerably more difficult.
The first Spring Drive patent application was filed in 1978.
Turning the idea into a practical wristwatch would take more than twenty years.
The Problem Was Power
A mechanical watch stores energy in its mainspring. As that spring unwinds, the movement's gear train transfers the energy through the watch.
Normally an escapement controls how that energy is released.
Spring Drive would need to do something entirely different.
The movement had to generate enough electrical energy from the unwinding mainspring to operate a quartz oscillator and integrated circuit, while consuming so little energy that the watch could still achieve a useful power reserve.
Early prototypes proved the principle could work.
They also demonstrated just how far away a practical watch remained.
Development stopped and restarted as technology caught up with Akahane's idea. Work resumed in the 1990s, and by 1997 a prototype finally demonstrated that the concept could become a viable watch movement.
Across the long development programme, more than 600 prototypes were produced.
Three Forms of Energy
The solution became what Seiko calls the Tri-synchro Regulator.
Instead of a conventional escapement, Spring Drive regulates the movement using three forms of energy working together.
The mainspring provides mechanical energy to drive the watch.
A tiny portion of that energy is converted into electrical energy, powering an integrated circuit and quartz oscillator which provide an extremely precise reference signal.
Finally, electromagnetic energy applies a brake to the glide wheel, controlling the rate at which the mainspring releases its energy through the movement.
There is no traditional stop-start action of an escapement.
And that produces Spring Drive's most immediately recognisable characteristic.
The Hand That Doesn't Tick
Watch the seconds hand of a conventional mechanical watch closely and, however smooth it may appear, it is actually advancing in a series of tiny steps determined by the movement's escapement.
Spring Drive doesn't do that.
Its seconds hand moves continuously around the dial in what Seiko calls glide motion.
Spring Drive's continuous glide motion. Film: Grand Seiko.
No tick.
No series of little jumps.
Just a continuous journey around the dial.
It's one of those rare pieces of watchmaking that can be understood before anybody explains the engineering behind it. Put a Spring Drive beside a conventional watch and your eyes tell you immediately that something different is happening.
Perhaps that's why the technology has become so closely associated with Grand Seiko.
Twenty Years to Reach the Wrist
Spring Drive was publicly exhibited at Baselworld in 1998.
Tragically, Yoshikazu Akahane died that August, shortly before the technology he had pursued for so long reached production.
The first commercial Spring Drive watch followed in 1999, using Seiko's manually wound calibre 7R68.
Credor followed with its own manual-winding Spring Drive calibre in 2002.
Then, in 2004, came the development that would make Spring Drive inseparable from the modern Grand Seiko story: calibre 9R65.
It brought automatic winding and a 72-hour power reserve to Grand Seiko's Spring Drive platform while delivering accuracy of approximately one second per day.
The idea Akahane had pursued since the 1970s had finally matured.
Neither One Thing Nor the Other
Collectors sometimes try to settle the question of whether Spring Drive is really mechanical or really quartz.
Perhaps that's asking the wrong question.
Its power comes from a mainspring. Its gears transmit that power through the movement. But its rate is controlled using a quartz oscillator, integrated circuit and electromagnetic brake.
Spring Drive exists because Seiko possessed deep experience on both sides of watchmaking.
The company that helped push mechanical watchmaking towards ever-higher frequencies was also one of the companies that transformed the industry through quartz.
Spring Drive didn't require Seiko to choose between those histories.
It joined them together.
And perhaps the seconds hand tells the story better than anything else.
Mechanical energy enters at one end. Quartz precision governs what happens within.
And on the dial, time simply flows.