A quartz watch is a watch that uses an electronic oscillator that is regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with a very precise frequency so that quartz watches are at least an order of magnitude more accurate than mechanical watches. Quartz is a specific form of a compound called silicon dioxide. It is a piezoelectric material that is, when the crystal is subjected to mechanical stress, such as bending it accumulates electrical charge across some plane. In a reverse effect, if charges are placed across the crystal plane, quartz crystals will bend a process called electrostriction.
The quartz crystal is cut in the shape of a small tuning fork (XY-cut), laser-trimmed or precision lapped to make a quartz crystal oscillator. The microchip is made from a metal-oxide-semiconductor. The battery is a single coin cell. The battery drives an electric stepping motor. The circuit is made to connect the microchip to other components. There is a crown screw for setting time. Inside gears to turn at different speeds. In the center, a tiny central shaft holds hands in place. The battery is connected to the microchip. The microchip is connected both to the quartz crystal oscillator and the electric stepping motor. The stepping motor is connected to the gears. The gears are connected to a shaft that holds the hands. The gears are also connected to the crown screw.
In a watch with a digital display, instead of gears, a chip repeatedly divides the oscillator frequency to drive the hours, minutes and seconds segments.
Do quartz watches need batteries?
The battery provides current to the microchip circuit. The microchip circuit makes the quartz crystal oscillate 32768 times per second. The microchip circuit detects the crystal’s oscillations and turns them into regular electric pulses, one per second. Electric pulses drive a miniature electric stepping motor. This converts electric energy into mechanical energy. Electric stepper motor turns gears. Gears sweep hands around the clock face to keep time.
Merits of Quartz Watch
Quartz watch are by far more advantageous than ordinary watches and pendulum clocks;
- They do not depend on gravity.
- They are not much affected by changes in temperature.
- They use so little power; the battery can often last several years before replacement.
- The quartz crystal inside regulates the gears with precision giving them high accuracy.
A quartz watch does not keep time with absolute accuracy forever. This is because the quartz crystal vibrates at different temperatures and pressure. However, the impact is to a tiny degree to the watch.
Wearing the watch reduces this error significantly since the ambient temperature (of humans) is constant. The problem is also solved by mounting the quartz oscillator in a miniaturized temperature-controlled container, called a crystal oven.
Quartz watches are efficient in timekeeping. With the advancing miniaturization technology, quartz watches are becoming cheaper to make and use. This is also advantageous to the power used by the watch.