An Explanation of Typical Watch Movements
Quartz Movement
A quartz watch is a watch that uses an electronic pendulum that is regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz timepieces are at least an order of magnitude more accurate than good mechanical clocks. Generally, some form of digital logic counts the cycles of this signal and provides a numeric time display, usually in units of hours, minutes, and seconds. Quartz timekeepers are the world’s most widely-used timekeeping technology, used in most clocks and watches, as well as computers and other appliances that keep time.
Automatic Movement
An automatic or self-winding watch is a mechanical watch, whose mainspring is wound automatically by the natural motion of the wearer’s arm, providing energy to keep the watch active, making it unnecessary to manually wind the watch.
These are powered by an internal spiral spring called a mainspring which turns the gears that move the hands. The spring loses energy as the watch runs, so in a manual watch movement the spring must be daily “wound” by the owner turning a small knob on the case to provide energy to run the watch, otherwise the watch runs down and stops.
A self-winding watch movement is similar to a manual movement with the addition of a mechanism powered by an eccentric weight which winds the mainspring. The watch contains a semicircular ‘rotor’, an eccentric weight that turns on a pivot, within the watch case. The normal movements of the user’s arm and wrist cause the rotor to pivot back-and-forth on its staff, which is attached to a ratcheted winding mechanism. The motion of the wearer’s arm is thereby translated into the circular motion of the rotor that, through a series of reverser and reducing gears, eventually winds the mainspring. Modern self-winding mechanisms have two ratchets and wind the mainspring during both clockwise and counterclockwise rotor motions.
Chronometers
Chronometers use a form of Quartz movement and are designed as time standards. They often include a mechanism to keep the crystal at a constant temperature to avoid any variance in density or otherwise interrupt the precise running of the timepiece. Some self-rate and include “crystal farms,” so that the clock can take the average of a set of time measurements to ensure that they are running on time.