How one tiny mineral works to be so precise
Ever wonders how the quartz watch got its name? The name has a more literal significance than you might think. It is actually powered by the quartz crystal, a mineral most closely resembling the compound of sand and which comes from the Earth’s continental crust. It is this mineral in minute quantity that has the ability to keep time more accurately than any other mechanical or automatic watch.
The discovery of how a quartz crystal could accurately power a wrist watch changed portable timekeeping like no other invention. When the first quartz watch was introduced in the United States in the early 1970s it was an expensive wrist watch priced at around $500. Not only that, it wasn’t the most beautiful face ever to adorn a wrist. The LED (light emitting diode) that showed digital time was bright red, and the technology was only applied to digital watches. Later, the engineering behind quartz watches was transformed so the displays could be shown in digital format using LCD (liquid crystal display) or an hour and minute hand, just like a mechanical watch’s face.
Shaping the Quartz Crystal
The quartz crystal of course is at the heart of how a quartz watch works. Quartz crystals have long worked as transmitters. They were and still are used in transistor radios. This same theory, in order to be applied to powering a wrist watch, had only a couple of obstacles to overcome. One was to get the frequency to not give off too much power. Quartz in a solid form gives off a low voltage of power when it is bent a specific way. The other obstacle was to create circuit boards, in miniature, that could regulate the power given off by the crystal and work at low power.
One of the reasons quartz is such a good material for the job of powering watches, or any other device, is that quartz, stays in a solid form at even extremely high temperatures. Because of this, once it is shaped, it will stay the same shape and therefore give off the same frequency and consistent power. It is also unchanged by just about any solvent, so it can work well with other materials needed to manufacture the inner workings of the watch.
Watchmakers soon figured out that a straight bar of quartz or one shaped like a tuning fork could keep the power going indefinitely. This action is referred to as the Piezoelectric Effect. When a piece of quartz is cut properly it provides a starting frequency which then causes oscillation. This translates into pulses that can be recognized by digital circuits on the circuit board. This then shows as a display of numbers that change at the exact timing with the oscillation caused by that perfect frequency.
The exact method used in a quartz watch involves using thin bars of quartz that are plated. Then, using chemicals, it is etched into the optimum shape. This works just like an integrated circuit.
There are certainly different quality levels and accuracy levels within the general category of “quartz watch.” This is because some quartz bars are cut better than others. The real objective is to have the precise relationship of the angle cut into the quartz bar correlate with the crystalline axis. Another major difference has to do with contamination of the components of the watch. If the quartz bar and circuit are well encapsulated, they are less likely to get contaminated, which will negatively impact the accuracy of the watch.
Quartz for Powering Watches with Hands
For a quartz watch with second, minute and hour hands the initial process is the same. However, at the point where a display would register on a digital watch, the oscillation instead activates an electric motor which then powers gears to move the hands at precise increments, or pulses that equal exactly one second, just like a mechanical watch.
Quartz watches have truly changed the way watches are made. There are still some people who prefer the “art” of a watch made solely by mechanical means. However, in a world where exactness and accuracy in keeping time often count, there is no substitute for the quartz watch.