Watch collectors have strong feelings about quartz versus mechanical watches: Battery-powered quartz is inexpensive, accurate and robust, but it lacks the je ne sais quoi of an electricity-free mechanical watch rooted in the traditions of centuries-old craftsmanship. Japanese watchmaker Seiko's innovative Spring Drive movement, however, turns these common notions on their head and offers the best of all worlds. But how does this hybrid technology work, exactly, and why should you care?
Quartz v Mechanical: What's the Difference, Anyway?
You can't understand Seiko's Spring Drive without first grasping what it borrows from mechanical and quartz systems. Most watches available today can be divided into quartz or mechanical — you can usually spot the difference quickly because quartz watches tick every second, whereas mechanical watches have seconds hands that "sweep."
Each type of movement uses a different kind of power source and a different way of keeping time — the two key elements of any watch. Mechanical watches are powered by a coiled spring slowly unwinding, and a tiny balance wheel oscillating several times per second sets the pace. A quartz watch, on the other hand, gets its juice from a battery, and a vibrating quartz crystal does the balance wheel's work.
The difference in timekeeping is dramatic. The radically higher frequency of quartz not only makes the most basic quartz watch more accurate than even the most impressive mechanical version, but fewer moving parts make them more reliable and robust — not to mention that quartz movements can be produced for a fraction of the cost of their mechanical counterparts.
Why people pay so much more for mechanical watches is a complicated issue, but many are left underwhelmed by quartz's cold efficiency and its association with cheap mass-production. Seiko's Spring Drive, however, is a different kind of movement that can best be described as a hybrid of traditional mechanical watchmaking and quartz accuracy.
How Exactly Do Spring Drive Watch Movements Work?
A simple takeaway is that Spring Drive is like a traditional mechanical watch movement that's regulated by a quartz crystal instead of a balance wheel — but the nitty gritty is far more interesting. Like standard mechanical movements, Spring Drive derives its power from an unwinding spring (a mainspring), with no batteries involved.
If not controlled, however, the spring would unfurl all at once. Mechanical watches address this by stopping and releasing a toothed gear several times per second to slow the spring's release, but Spring Drive accomplishes this with magnetic force instead: A wheel connected to the mainspring barrel spins continuously without friction.
This causes the seconds hand to travel around the dial in a perfectly smooth glide — which looks cool and all, but this glide needs to represent accurate timekeeping. That's where the quartz crystal and an integrated circuit (IC) come into the picture: A small amount of electricity generated by the mainspring vibrates a tuning-fork shaped crystal at an extremely precise and regular rate.
The IC then compares wave forms from the spinning wheel and the crystal, adjusting the electromagnetic braking power in order to synchronize the waves. In other words, the reliable rate of the quartz's vibrations determine exactly how long it should take for the seconds hand to travel around the dial.
Ok, But Why Should I Care?
While this innovation itself is impressive, you'd be right to wonder what it can do for you. Spring Drive offers several benefits aside from simply being unique and interesting, the most notable of which are accuracy and durability — the primary factors which have driven horological innovation for centuries.
Seiko's most accurate current Spring Drive movement promises +/- 0.5 seconds deviation per day (or +/- 10 seconds per month). That's better than many standard, battery-powered quartz movements and far more accurate than, say, a mechanical chronometer watch that's proudly certified to be accurate within -4 to +6 seconds per day.
Spring Drive's use of electromagnetic force eliminates the stop-start friction of the balance found in mechanical watches, the mechanical components most vulnerable to wear. It's also less susceptible to variables caused by impacts like banging your watch on a doorjamb — and even problems caused by gravity due to the watch's position.
Finally, the Spring Drive movements offer an experience similar to wearing mechanical watches in many respects. They typically have a similar power reserve (72 hours, in many cases) and must be wound either manually via the crown or using the motion of the wearers wrist like with common automatic watches. The Spring Drive movements found in Grand Seiko watches also receive a high level of finishing and are often beautifully displayed through the case back.
A less practical characteristic of Spring Drive watches is that their operation is almost eerily quiet and smooth. If you look closely at mechanical watches' seconds hands, you can actually see them stuttering around the dial, but a Spring Drive seconds hand has a genuinely continuous sweep. It lacks the familiar ticking for the same reason.
Seiko named its system Spring Drive in order to help explain to consumers that it's powered by a spring — i.e., no batteries! It's the only technology that can be considered a true hybrid of the two systems. It's no surprise that this technology continues to cause head-scratching in a world that's more digestible when simply divided into quartz and mechanical watches, but understanding Seiko's incredible innovation is worth the extra effort.