What is Seiko Spring Drive? Is it quartz? Is it mechanical?

Zach Blass

By now, the majority of watch nerds will see a headline like this, and think the answer is obvious. Spring Drive is a movement technology developed by the Seiko Corporation, largely used and popularised by its higher-tier Grand Seiko brand, known for its incredible accuracy within a second per day, and a perfectly fluid rotating seconds hand. But, Spring Drive was not born in a Grand Seiko watch, and actually made its debut inside Seiko and Credor watches. You know what… I’m getting ahead of myself. Let’s all get on the same page and answer the question: what is Seiko Spring Drive?

The origins of Spring Drive

The story of Seiko Spring Drive begins in the late 1970s and was the brainchild of Suwa Seikosha (now Seiko Epson Corporation) engineer Yoshikazu Akahane. Akahane joined the company in 1971, just two years after the launch of the world’s first quartz watch: the Seiko Astron born in 1969. At the time, Seiko was looking to further develop its solar and Kinetic technology to further bolster its quartz offerings. But Akahane would dream up a radically novel idea during this time, and idea he called “Quartz Lock.” The concept: to deliver the precision of a quartz watch that, rather than be dependent on a battery for energy was dependent strictly on the wearer like a mechanical watch.

This idea was conceived by Akahane in 1977 while he worked on “Twin Quartz” technology, and by 1978, a patent was filed for the technology that would later become known as Spring Drive. In 1982, after a second patent was filed, a team was then assembled to try and make Akahane’s theory a reality, but the technology available at the time did not produce a commercially viable Spring Drive movement. While the aim was to deliver a Spring Drive movement with 48 hours of power reserve, the first prototype was only able to run for four hours. In 1983, when Seiko realised it needed to wait for IC technology to mature, the project was put on hold.

After a decade, the necessary electronics technology that could theoretically make Spring Drive possible arose in 1993, and efforts resumed on the project. With more energy-efficient, low-power integrated circuits at its disposal, Seiko began its second attempt – a coordinated effort that brought Seiko Timing Instruments LTD (Seiko Watch Corporation), the mechanical arm of Seiko watchmaking, into the fold. This second attempt would end in failure once again in 1994. Unfortunately, the following prototype yet again could not meet the minimum power reserve benchmark of 48 hours, lasting less than a full day.

In 1997, Akahane, who then served as Deputy General Manager of the Watch Division at Epson, would once again push the pursuit of realising viable Spring Drive. While the landscape of technology at the development team’s disposal that could enrich its efforts into increasing power reserve had not really changed since the last attempt, the three-year break and a rethinked approach would fortunately yield a new way to better harness power. A year later, Akahane and his team would present what Seiko describes as a “technical release” at the 1998 edition of Baselworld, and Seiko would return to Baselworld a year later to finally present Spring Drive.

Akahane passed away in 1999, and was unable to see Spring Drive’s introduction to the world. Shortly after Baselworld, in December 1999, Seiko Spring Drive would make its debut in three limited edition watches. According to Grand Seiko, between all three models, only 900 total units were produced – 500 of which were the stainless steel Seiko SBWA001 I consider myself very privileged to own. Spring Drive would only become more regular in production when Grand Seiko debuted its 9R-series Spring Drive in 2004, and has since become much more commonplace in Seiko watches across its three main brands: Seiko, Grand Seiko, and Credor.

How does Spring Drive work?

The Seiko Museum Ginza explains how Spring Drive works in six steps.

1. Spring Drive works like a mechanical watch, driving the mechanisms with the force generated from the unwinding of the mainspring.
2. A small amount of power from the spring is transmitted to a rotor, fitted with a magnet that generates electricity.
3. The electric power activates the IC and vibrates the quartz oscillator, vibrating at 32,768 times per second (32,768Hz).
4. A circuit called a frequency divider changes the frequency of the quartz oscillator into a signal pulsing 8 times per second (8Hz), and sends the fixed reference signal at a frequency of 8Hz.
5. The IC keeps the rotor moving at a constant speed to synchronize the 8Hz reference signal. The rotor brake is sequentially activated and released by electromagnetic force, while the reference signal of the quartz and the rotational speed of the rotor are compared.
6. As a result, this mechanism achieves an accurate speed by transmitting a controlled movement in the following order: mainspring→ rotor→ wheels→ hands.

In layman’s terms, Spring Drive is exactly what Akahane set out to do – merging the precision of quartz with the autonomy of a traditional mechanical watch through an ingenious mechanism called the Tri-Synchro Regulator. This mechanism uses kinetic, electrical, and magnetic power to regulate the rate of the watch in conjunction with what Seiko calls the glide wheel. This glide wheel, named so due to the fluid gliding seconds hand it creates, uses electromagnets to slow the energy from the mainspring (the spring that stores potential energy in its coils as the automatic rotor self-winds or as the wearer manually winds the watch) without any friction while simultaneously generating an electrical current which is, in turn, run through the integrated circuit (IC) and a quartz crystal. This is then fed back through the electromagnets – regulating the glide wheel to turn precisely 8 times a second netting the signature glide and +/- 15 seconds per month accuracy.

Is Spring Drive quartz? Is it mechanical? Both?

Spring Drive cannot conform to the traditional quartz or mechanical binary. It’s its own third and novel segment of watchmaking. I jokingly refer to it as a mechanical movement technology that cheats with a quartz escapement. Spring Drive movements ultimately utilise a minute amount of electrical energy, so little in fact, that it was described to me that effectively the entire population of the United States wearing a Spring Drive watch would total enough energy to power a single lightbulb.

The majority of a Spring Drive movement is no different than a traditional mechanical movement, and therefore, while ultimately a hybrid, is closer to a mechanical than a quartz movement, if I had to choose to lean one way. Given the quartz-driven regulating organ, however, traditionalists are understandably hesitant to call it mechanical. So, what is the final answer? Simply put: a mechanically powered (spring-driven, if you will) movement with a quartz escapement.