Unveiling watch inner workings: why does a quartz watch seconds hand step?

As early as 1969, Seiko of Japan successfully miniaturised the quartz movement and launched the first quartz watch, delivering unprecedented performance. The average monthly deviation was within 5 seconds, making it over 100 times more precise than any watch of its era. More importantly, it could run continuously for an entire year, 250 times the operating duration of most mechanical watches. This marked the start of the Quartz Revolution.

　　DistinguishingQuartz watchesDistinguishing it from a mechanical watch can be done using the simplest and most direct method: observe whether the seconds hand ticks forward one increment at a time (commonly known as dead-beat seconds). If it does, it is a quartz watch. By contrast,Mechanical watch's seconds hand glides smoothly (commonly known as a sweeping seconds hand). Of course, this method is not entirely foolproof, as a ticking seconds hand is not necessarily quartz, and a sweeping seconds hand is not necessarily mechanical.

　　The reason for the difference in seconds hand movement between quartz and mechanical watches comes down to conserving power.

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　　A quartz watch operates via an electric motor, and a battery can only power the watch movement for half the time if driven constantly. Therefore, to extend battery life, the seconds hand was designed to step once per second, reducing the motor's operating time—a design choice where the advantages far outweigh the drawbacks.

　　In fact, the seconds hand of a mechanical watch also moves in discrete steps. If you doubt this, try using your phone's slow-motion feature to film a mechanical watch. In slow motion, you will notice that the seconds hand actually steps. Because the ticking frequency is so high—stepping several times per second rather than once—and each step is tiny, it is difficult to perceive with the naked eye. This is why people assume a mechanical watch seconds hand sweeps rather than ticks, commonly referred to as a “sweeping seconds” motion.