Watch what you are buying with accuracy

Press, 14 December 1977, Page 32

Watch what you are buying with accuracy

Choosing a watch is a very personal undertaking. Some people buy a watch for its looks, and some for its price. Others consider only its practicality. But, if it is performance and accuracy you are after, you ought to consider the quartz watch, which has revolutionised time-keeping technology during the last decade. The first quartz watch was produced in Switzerland in 1967. It revolutionised the watchmaking industry, being more accurate, more reliable and easier to service than any previous miniaturised form of timekeeping. Quartz had been used in time-keeping before. As early as 1925 a quartz clock had been made. It was not until 1952 that quartz technology received world recognition, with its introduction at the Olympic Games in Helsinki. The Omega Time Recorder I made it possible to measure runners’ times to 1/100th of a second. Looking at the bulky machinery used in Helsinki, no-one could have believed that in less than 20 years people would be wearing the same technology on their wrists. Time measurement involves splitting the second into parts. Traditional methods used oscillations of a pendulum, dividing the second into five oscillations. The more parts the second can be divided into, the more accurate the measurement of that second will be. The first radical improvement on the five oscillations per second came with the introduction of the tuning fork, which initially vibrated at about 360 times a second. Quartz, however, vibrates thousands of times each second, in some watches, millions. The Omega Megaquartz 2’400, for example, vibrates 2,359,296 times a second. Here is how the quartz principle works in a wristwatch: The current from a battery is supplied through an integrated circuit to the quartz crystal. This energy makes the crystal vibrate at a high and constant fre-

quency (for example, 32,768 times a second). You cannot see it or hear it. A divider integrated circuit reduces the vibrations to a single impulse per second. This is transmitted to a micromotor, which activates the wheel-train and hands of a traditional watch. Or, the impluse is transmitted to the decoder integrated circuit which controls a digital display. The Omega Megaquartz 2’400 is the extreme in wristwatch accuracy. It is the only wristwatch in the world to have passed the rigorous tests to qualify as a “marine chronometer.” In 50 days of testing, the watch revealed a standard deviation of only 2/1000th of a second per day. Marine chronometers are used for navigation and their accuracy is crucial. A deviation of just one second corresponds, at the equator, to an error in position of 463 m. The conventional marine chronometer is about 1500 cubic centimetres in size. The megaquartz 2’400 measures 4.76 cubic centimetres. Obviously, the average person has no need for a watch of such meticulous accuracy, but the Megaquartz 2’400 is an example of the potential of quartz technology. Apart from being the most accurate watch available, the quartz has other advantages. Unlike a selfwinding watch, a quartz will keep working if you leave it off your wrist. A good battery should keep a quartz watch going for at least a year, and can »pe easily replaced within minutes. Quartz watches have less moving parts than traditional watches, so are

easier to service. Omega, of course, is not the only watchmaker manufacturing quartz watches. At the Christchurch Duty Free Shop quartz watches are available also from Casio, Roamer, Girard Perregaux, Nivada, Seiko, Tissot and Citizen. Another important consideration when buying a watch is whether to choose a digital face or the traditional analogue display. According to the makers of Omega watches, there is no difference in precision or reliability between the two displays,, providing the watch is from a good maker. There are two types of digital display systems to choose from. The LCD, or liquid-crystal display shows the time continuously. The digits are readable in all daylight conditions, and most LCD watches have a nightlight. LED watches, or lightemitting diodes, display the time with the push of a button. Some watches incorporate both analogue and digital systems. The Omega Chrono-quartz, for instance, incorporates a LCD digital stopwatch with an analogue display on the one electronic module. The quartz watch operates indepently of the chronograph (stopwatch), and is accurate to within five seconds per month. The duty free shop has more than 100 watches to choose from, ranging in price from $3O to $5OO. Nine manufacturers are represented. So, there ought to be a watch to suit everybody’s taste and budget.