Quartz Watch

Overview

A quartz watch tells time by counting the vibrations of a quartz crystal. When a small voltage is applied across the crystal it flexes at a highly stable frequency, exactly 32,768 times per second. An integrated circuit divides this oscillation down to one pulse per second, and that pulse advances the hands. Because the crystal's frequency varies far less than a mechanical balance, quartz watches are accurate to within seconds per month while costing a fraction of a comparable mechanical caliber.

The watch translates a steady electrical pulse into the motion of three hands. The Quartz Movement holds the oscillator, motor, and gearing; it sits inside the gasketed Case Assembly behind a Dial carrying applied hour markers. A Hand Set of hour, minute, and second hands reads the time, a Date Mechanism shows the calendar through a window, and the watch fastens to the wrist with a Strap.

How it works

At the core of the movement, a circuit board carries the timekeeping IC, the 32.768 kHz quartz resonator, and a trimmer capacitor for fine rate adjustment. The IC's frequency divider produces one electrical pulse each second and sends it to the coil block, energising the stator around a Lavet-type stepper motor.

The stepper's permanent-magnet rotor advances exactly one step per pulse, a half-turn that the rotor pinion feeds into the gear train. Train wheels and pinions step this motion down to drive the seconds wheel directly, while the motion works, cannon pinion, minute wheel, and hour wheel, produce the 12:1 ratio between minute and hour hands.

A silver-oxide cell supplies the 1.55 V the IC needs, held against a contact spring by a battery clamp. Pulling the crown engages the setting mechanism: its sliding clutch and setting lever redirect crown rotation away from winding (there is none) into hand-setting and date correction, then return the movement to its running state when the crown is pushed home.