====== Quartz watch ======
A **quartz watch** uses quartz for timekeeping and electronics for the other main functions, display and power.

===== History =====
The history of quartz watches begins with the [[electric watch]]es introduced by [[LIP]]/[[Elgin]] and [[Hamilton]] in [[1958]]. These used a conventional [[wheel train]] and [[balance wheel]] with an electric contact rather than an escapement. The next major advance was the [[1960]] [[Bulova Accutron]], which used a [[tuning fork]] and [[pawl]]-driven wheel train. Bulova was the first to use a transistor in a watch movement, a technology that was soon adopted by [[electric]] watches as well. The Accutron technology was licensed in [[1968]] to [[Ebauches SA]] as the [[Mosaba]] and later to [[Citizen]] as the [[Hi-Sonic]].

The quartz wrist watch was actively developed throughout the 1960s and brought to market in [[1969]] and [[1970]]. Many Swiss companies joined together as the [[Centre Electronique Horloger]] in [[Neuchâtel]] to develop the [[Beta 21|Beta series]] of movements. The initial [[1967]] Beta 1 used a [[dead beat]] [[stepper motor]] and achieved [[chronometer]] precision but was not practical for production. The [[1968]] Beta 2 switched to a [[pawl]] similar to the tuning fork movements but driven by a micro-motor. This showed greater promise and was developed for production as the Beta 21 movement.

[[Longines]] was first to announce a production quartz watch, however. The [[Longines Ultra-Quartz]], announced August 20, [[1969]], used a quartz rod and micro-motor as a resonator, stepping down with a transistor and driving the wheel train with a micro-motor and pawl like the Beta 2. Referred to as "cybernetic" at the time, it did not use an integrated circuit or modern quartz resonator.

On Christmas Day, [[1969]], Seiko announced their [[Seiko Astron|Astron]] quartz watch. It used a quartz resonator and integrated circuit and drove the hands using a stepper motor, the hallmark of modern quartz watches. This model is usually credited today as the first quartz watch.

The [[Basel Fair]] in [[1970]] was positively filled with quartz watches, including [[Longines]], [[Girard-Perregaux]], and [[Omega]] as well as the [[Beta 21]] members. The Beta 21 was a production version of the Beta 2, with a quartz rod resonator and integrated circuit counter but a micro-motor and pawl wheel train. The Beta 21 consortium members launching product at the fair included [[Bulova]], [[Doxa]], [[Elgin]], [[Enicar]], [[IWC]], [[Longines]], [[Rado]], and [[Zodiac]]. In addition to the [[Longines Ultra-Quartz]], fairgoers saw high-frequency quartz movements from [[Girard-Perregaux]] and [[Omega]], the [[Girard-Perregaux Elcron|Elcron]] and [[Omega Megaquartz|Megaquartz]].

Many other companies worked to commercialize the quartz movement after this, both inside and outside Switzerland. Swiss projects included the [[Neosonic]] system, [[Omega]]'s Beta 22, and [[Universal Geneve]]. In Japan, [[Seiko]] and [[Ricoh]] were in the lead, with [[Citizen]] a few years delayed. [[Junghans]] of Germany and [[LIP]] of France would also soon deliver their own quartz technology, as would [[Bulova]] and [[Hamilton]] in the United States. In addition to analog watches, [[digital]] displays soon appeared, including mechanical, [[LED]], and various [[LCD]] technologies. [[Texas Instruments]] brought dramatic improvements in integrated circuit technology, as did [[EEM]] and [[Faselec]] in Switzerland. Quartz crystals from [[Seiko]], [[NDK]], [[Statek]], and [[Micro Crystal]] were also widely used.

===== Construction concept =====
A **quartz watch** is a timepiece that uses the oscillation of a quartz crystal to keep time, triggering a electrically-powered stepper motor to advance the [[wheel train]], usually once per second. Although other timepieces ([[Seiko]] [[Spring Drive]] and [[Bulova]] [[Accutron]], for example) include quartz crystals, these are generally not called quartz watches.

In a quartz movement, a crystal is made to vibrate. The uniform oscillation is now used to drive a motor with the help of a chip, ie an integrated circuit. This turns a [[gear train]] in the rhythm of the supplied pulses. Quartz watches do not contain a [[spring]], [[balance wheel]] or [[escapement]].

One advantage of this concept is the very high accuracy and the low space consumption, disadvantages are the environmental pollution by the battery and its dependence on the battery change.

With [[quartz watch]]es there are essentially two display systems 

  * digital display with light emitting diodes or liquid crystals
  * analog hands, which are driven by a motor

Because of the required electric power most quartz watches have batteries. This makes it possible that the watch may stop suddenly - a fact which has to be urgently regarded especially at [[dive watch]]es and which has once again led to develop mechanical dive watches, such as the [[IWC GST Deep One|GST Deep One]] by [[IWC]].

===== Thermocompensation and Adjustment =====
Temperature plays a major role in the accuracy of a quartz movement. First- and second-generation quartz watch movements were generally not thermocompensated at all, leading to varying levels of accuracy. Even today, most quartz movements are second-generation CMOS circuits with no thermocompensation or other adjustments for accuracy.

There are three methods of fine accuracy adjustment in quartz movements 

  - Automatically thermocompensated movements (e.g. [[Citizen]] High-Accuracy Quartz)
  - Thermocompensated with calibration terminals (e.g. [[ETA Thermoline]], [[Seiko 9F]], [[Rolex OysterQuartz]])
  - Non-thermocompensated with calibration terminals (e.g. [[Jaeger-LeCoultre Mechaquartz]])

===== Further developments =====
Also known are [[solar watch]]es by Junghans, Citizen or Casio, that draw their power from solar cells.

[[Heuer]] introduced the world's first [[quartz chronograph]] watch in [[1975]], the [[LED]]/[[LCD]] [[Heuer Chronosplit]]. [[Seiko]] would be the first to produce an analog quartz chronograph, the [[Seiko 7A|Cal. 7A]], with [[Heuer]] once again close behind in [[1983]]. [[Frédéric Piguet]] and [[Jaeger-LeCoultre]] both delivered slim and compact quartz chronograph movements in [[1987]], the confusingly-named [[Meca-Quartz]] and [[Mechaquartz]].

A combination of quartz precision and mechanical winding is the [[autoquartz]] technology developed by [[Seiko]].

In [[2019]], [[Citizen]] introduced [[Calibre 0100]], claimed to be the most accurate watch movement ever produced. Accurate to 1 second per year, this [[quartz]] movement uses an "AT Cut" oscillator rather than the more conventional [[tuning fork]] shape and operates at much higher frequency.

===== Economical aspects of the quartz watch =====
Because of the competition for the most accurate quartz watch and the most advanced technology, the Swiss watch industry collapsed late 1970s and early 1980s into their worst crisis (keyword [[quartz crisis]]), from which in the meantime it nevertheless emerged strengthened again. This was mainly due to two things the launch of the (quartz-driven) [[Swatch]], which led the audience back to the Swiss watch, and secondly the successful renaissance of the [[mechanical watch]] in the luxury segment of the market.


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