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What's the difference between quartz and liquid crystal?


The Role of Quartz

Let's review the basic components that a watch or clock needs to work correctly:

  • a timekeeping mechanism, which measures the length of time by transmitting a constant frequency
  • a display to convey time in a way we can understand
  • an integrated circuit, which stores the date and time and communicates with the timing mechanism and the display
  • a battery to power these elements
  • a circuit board to house and connect all of the pieces [source: Exploring the Nanoworld]

Remember that we're talking specifically about digital quartz watches and clocks. These are different from the mechanical watches that must be wound regularly and do not usually incorporate quartz, and they're different from the analog watches and clocks that use gears to drive the hands along a face, which typically don't incorporate liquid crystals.

Quartz functions as the timekeeping mechanism. First introduced into watches by Seiko in 1969, quartz crystals have become standard for modern watch manufacturers in the decades since [source: Seiko]. The quartz used in watches vibrates at a very high frequency. This translates to great accuracy: The time displayed on a quartz watch might deviate from real time by just a few seconds in a given month [source: Lombardi]. Additionally, because quartz is piezoelectric, it requires very little power to vibrate, enabling a single alkaline battery to power a quartz watch for years on end.

Quartz works in tandem with the watch's integrated circuit. In short, the battery sends a small electric charge to the integrated circuit, which is attached to a quartz oscillator with a pair of tiny electrodes. The circuit passes the electricity through to the quartz oscillator and it begins vibrating. The quartz oscillators used in watches have been standardized to vibrate 32,768 times per second, or at a frequency of 32.768 kilohertz. The integrated circuit is programmed to count the vibrations of the oscillator and measure the intervals -- seconds, minutes, hours and so on. At each interval, the circuit transmits an electric pulse.

And where does this pulse go? The liquid crystal display. How does liquid crystal display numerals on a digital watch face? Read on to find out.