   #copyright

Watch

2007 Schools Wikipedia Selection. Related subjects: Engineering

          In naval parlance, watches are a timekeeping convention. The
          term in general use can mean any period of duty or
          responsibility, such as a hurricane watch.

   A wrist watch
   Enlarge
   A wrist watch

   A watch is a small portable timepiece or clock that displays the time
   and sometimes the day, date, month and year. In past centuries, these
   often took the form of pocket watches, which today are seldom carried
   or worn. In modern usage, watch is usually a contraction of wristwatch,
   a designation for the most popular style of timekeeping device worn on
   the wrist.

   Because most watches lack a striking mechanism, such as a bell or gong
   to announce the passage of time, they are properly designated as
   timepieces, rather than clocks.

Overview

   Today, the most common type of watch is the wristwatch, worn on the
   wrist and fastened with a watch strap or watchband, a bracelet made of
   real or synthetic leather, metal, nylon, or even ceramic. Before the
   inexpensive miniaturization that became possible in the 20th century,
   most watches were pocket watches, which had covers and were carried
   separately, often in a pocket and attached to a watch chain.

   Most inexpensive and medium-priced watches used mainly for timekeeping
   are electronic watches with quartz movements, powered by electricity.
   Expensive, collectible watches valued more for their workmanship and
   aesthetic appeal than for simple timekeeping often have purely
   mechanical movements and are powered by springs, even though mechanical
   movements are many times less accurate than quartz movements. The most
   accurate watches have radio-controlled movements that are miniaturized,
   portable versions of radio clocks (q.v.).

Watch cases

Pocket timepieces

   The earliest need for portability in timekeeping was navigation and
   mapping in the 15th century. The latitude could be measured by looking
   at the stars, but the only way a ship could measure its longitude was
   by comparing the midday (high noon) time of the local longitude to that
   of a European meridian (usually Paris or Greenwich)—a time kept on a
   shipboard clock. However, the process was notoriously unreliable until
   the introduction of John Harrison's chronometer. For that reason, most
   maps from the 15th century through the 19th century have precise
   latitudes but distorted longitudes.

   The first reasonably accurate mechanical clocks measured time with
   weighted pendulums, which are useless at sea or in watches. The
   invention of a spring mechanism was crucial for portable clocks. In
   Tudor England, the development of “pocket-clockes” was enabled through
   the development of reliable springs and escapement mechanisms, which
   allowed clockmakers to compress a timekeeping device into a small,
   portable compartment.

   In 1524, Peter Henlein created the first pocket watch. It is rumoured
   that Henry VIII (the portrait of Henry VIII at this link shows the
   medallion thought to be the back of his watch) had a pocket clock which
   he kept on a chain around his neck. However, these watches only had an
   hour hand—a minute hand would have been useless considering the
   inaccuracy of the watch mechanism. Eventually, miniaturization of these
   spring-based designs allowed for accurate portable timepieces which
   worked well even at sea.

   In 1850, Aaron Lufkin Dennison founded Waltham Watch Company, which was
   the pioneer of the industrial manufacturing of pocket watches with
   interchangeable parts, the American System of Watch Manufacturing.

   Breguet developed the first self-winding watch known as the perpetuelle
   in 1780[From the Breguet History Book].

Wristwatches

   The wristwatch was invented by Patek Philippe at the end of the 19th
   century. At the time, it was considered a woman's accessory. It was not
   until the beginning of the 20th century that the Franco-Brazilian
   inventor Alberto Santos-Dumont, who had difficulty checking the time
   while in his first aircraft (Dumont was working on the invention of the
   aeroplane), asked his friend Louis Cartier for a watch he could use
   more easily. Cartier gave him a leather-band wristwatch from which
   Dumont never separated. Being a popular figure in Paris, Cartier was
   soon able to sell these watches to other men. During the First World
   War, officers in all armies soon discovered that in battlefield
   situations, quickly glancing at a watch on their wrist was far more
   convenient than fumbling in their jacket pockets for an old-fashioned
   pocket watch. In addition, as increasing numbers of officers were
   killed in the early stages of the war, NCOs promoted to replace them
   often did not have pocket watches (traditionally a middle-class item
   out of the reach of ordinary working-class soldiers), and so relied on
   the army to provide them with timekeepers. As the scale of battles
   increased, artillery and infantry officers were required to synchronize
   watches in order to conduct attacks at precise moments, whilst
   artillery officers were in need of a large number of accurate
   timekeepers for rangefinding and gunnery. Army contractors began to
   issue reliable, cheap, mass-produced wristwatches which were ideal for
   these purposes. When the war ended, demobilized European and American
   officers were allowed to keep their wristwatches, helping to popularize
   the items amongst middle-class Western civilian culture.

   Today, many Westerners wear watches on their wrists, a direct result of
   World War I. The trend has since spread to other parts of the world,
   wherever accurate and convenient time references are required.

Watch movements

   A movement in watchmaking is the mechanism that measures the passage of
   time and displays the current time (and possibly other information
   including date, month, day et cetera) to the wearer of the watch.
   Movements may be entirely mechanical, entirely electronic (potentially
   with no moving parts), or a blend of the two. Most watches intended
   mainly for timekeeping today have electronic movements, with mechanical
   hands on the face of the watch indicating the time.

Mechanical movements

   Purely mechanical watches are still popular, although they are most
   commonly seen among expensive, collectible watches. The best of these
   are among the most precisely engineered mechanisms in existence, and
   this superb craftsmanship accounts for much of the attraction of purely
   mechanical watches.

   Compared to electronic movements, mechanical watches keep very poor
   time, often with errors of seconds per day. They are frequently
   sensitive to position and temperature, they are costly to produce, they
   require regular maintenance and adjustment, and they are more prone to
   failure. For this reason, inexpensive and moderately priced timepieces
   with electronic movements now provide most users with superbly accurate
   timekeeping and have almost entirely supplanted older watch designs
   with mechanical movements.

Tuning-fork movements

   Tuning fork watches (introduced by Bulova in 1960) use a 360 hertz
   tuning fork to drive a mechanical watch. Since the fork is used in
   place of a typical balance wheel, these watches naturally hum instead
   of ticking.

   The inventor, Max Hetzel, was born in Basel, Switzerland, and joined
   the Bulova Watch Company of Bienne, Switzerland, in 1948. Hetzel was
   the first to use an electronic device, a transistor, in a wristwatch.
   Thus, he developed the first watch that could be qualified as
   electronic. However, fork movements are actually more "electrical",
   like an old electrical wall clock, than electronic. The sweep second
   hand moves fluidly like that of an old electrical wall clock.

   Such watches were also sold by Swiss watch companies under license of
   Bulova. In 1974, after leaving Bulova, Hetzel developed a different
   tuning fork drive for Omega Watches. The watch featured a cal. 1220
   micromotor, and a tuning fork frequency of 720 hertz. This development
   was obsolete compared to the newer electronic quartz watch which had
   become cheaper to produce and even more accurate.

   Tuning fork movements are electromechanical. The task of converting
   electronically pulsed fork vibration into rotary movement is done via
   two tiny jeweled fingers that are connected to one of the tuning fork's
   tines. As the fork vibrates, the jeweled fingers precisely ratchet a
   tiny index wheel. This index wheel has over 300 barely visible teeth
   and spins more than 38 million times per year. The tiny electric coils
   that drive the tuning fork have 8000 turns of insulated copper wire
   with a diameter of 0.015 mm and a length of 90 meters. This amazing
   feat of engineering was prototyped in the 1950s.

Electronic movements

   Electronic movements have few or no moving parts. Essentially, all
   modern electronic movements use the piezoelectric effect in a tiny
   quartz crystal to provide a stable time base for a mostly electronic
   movement: the crystal resonates at a specific, highly stable frequency
   that can be used to accurately pace a timekeeping mechanism. For this
   reason, electronic watches are often called quartz watches. Most quartz
   movements are primarily electronic but are geared to drive mechanical
   hands on the face of the watch in order to provide a traditional analog
   display of the time, which is still preferred by most consumers.

   The first prototypes of electronic quartz watches were made by the CEH
   research laboratory in Switzerland in 1962. The first quartz watch to
   enter production was the Seiko 35 SQ Astron, which appeared in 1969.
   Modern quartz movements are produced in very large quantities, and even
   the cheapest wristwatches typically have quartz movements.

   The best quartz movements are significantly more accurate than the
   worst, but the difference is much smaller than that found between
   mechanical movements and quartz movements. Quartz movements, even in
   their most inexpensive forms, are an order of magnitude more accurate
   than purely mechanical movements. Whereas mechanical movements can
   typically be off by several seconds a day, an inexpensive quartz
   movement in a child's wristwatch may still be accurate to within 500
   milliseconds per day—ten times better than a mechanical movement.

Radio-controlled movements

   Some electronic quartz watches are able to synchronize themselves with
   an external time source. These sources include radio time signals
   directly driven by atomic clocks, time signals from GPS navigation
   satellites, and others. These watches are free-running most of the
   time, but periodically align themselves with the chosen external time
   source automatically, typically once a day.

   Because these watches are regulated by an external time source of
   extraordinarily high accuracy, they are never off by more than a small
   fraction of a second a day (depending on the quality of their quartz
   movements), as long as they can receive the external time signals that
   they expect. Additionally, their long-term accuracy is comparable to
   that of the external time signals they receive, which in most cases
   (such as GPS signals and special radio transmissions of time based on
   atomic clocks) is better than one second in three million years. For
   all practical purposes, then, radio-controlled wristwatches keep
   perfect time.

   Movements of this type synchronize not only the time of day but also
   the date, the leap-year status of the current year, and the current
   state of daylight saving time (on or off). They obtain all of this
   information from the external signals that they receive. Because of
   this continual automatic updating, they never require manual setting or
   resetting.

   A disadvantage of radio-controlled movements is that they cannot
   synchronize if radio reception conditions are poor. Even in this case,
   however, they will simply run autonomously with the same accuracy as a
   normal quartz watch until they are next able to synchronize.

Displaying the time

   There are two main ways in which watches display the time to their
   owners: analog and digital.

Analog display

   Traditionally, watches have displayed the time in analog form, with a
   numbered dial upon which are mounted at least a rotating hour hand and
   a longer, rotating minute hand. Many watches also incorporate a third
   hand that shows the current second of the current minute. Watches
   powered by quartz have second hands that snap every second to the next
   marker. Watches powered by a mechanical movement have a "sweeping
   second hand", the name deriving from its uninterrupted smooth
   (sweeping) movement across the markers. All of the hands are normally
   mechanical, physically rotating on the dial, although a few watches
   have been produced with “hands” that are simulated by a liquid-crystal
   display.

   Analog display of the time is nearly universal in watches sold as
   jewelry or collectibles, and in these watches, the range of different
   styles of hands, numbers, and other aspects of the analog dial is very
   broad. In watches sold for timekeeping, analog display remains very
   popular, as many people find it easier to read than digital display;
   but in timekeeping watches the emphasis is on clarity and accurate
   reading of the time under all conditions (clearly marked digits, easily
   visible hands, large watch faces, etc.).

Digital display

   Since the advent of electronic watches that incorporate small
   computers, digital displays have also been available. A digital display
   simply shows the time as a number, e.g., 10:30 AM instead of a short
   hand pointing towards the number 10 and a long hand pointing towards
   the number 6 on a dial.

   Cheaper electronics permitted the popularization of the digital watch
   in the second half of the 20th century. They were seen as the great new
   thing. Douglas Adams, in the introduction of his novel The Hitchhiker's
   Guide to the Galaxy, would say that humans were "so amazingly primitive
   that they still think digital watches are a pretty neat idea."

   The first digital watch, a Pulsar prototype in 1970, was developed
   jointly by Hamilton Watch Company and Electro-Data. A retail version of
   the Pulsar was put on sale on April 4th 1972. It had a red
   light-emitting diode (LED) display. Another early digital watch
   innovator, Roger Riehl's Synchronar Mark 1, provided an LED display and
   used solar cells to power the internal nicad batteries. Most watches
   with LED displays required that the user press a button to see the time
   displayed for a few seconds, because LEDs used so much power that they
   could not be kept operating continuously. Watches with LED displays
   were popular for the next few years, but soon the LED displays were
   superseded by liquid crystal displays (LCDs), which used less battery
   power. The first LCD watch with a six-digit LCD was the 1973 Seiko
   06LC, although various forms of early LCD watches with a four-digit
   display were marketed as early as 1972 including the 1972 Gruen
   Teletime LCD Watch.

   Digital watches did not replace analog watches. In fact, after a number
   of years of great popularity, digital watches fell somewhat out of
   fashion, and today most watches display the time in analog form, with
   mechanical hands, even if all the internal parts of the watch are
   electronic.

   Almost all watches with digital displays today are in the category of
   simple timekeeping watches, and they are particularly popular with
   “geek watches” that incorporate a very large number of features besides
   simply showing the date and time. Watches sold as jewelry or
   collectibles almost never have digital displays.

   Expensive watches for collectors rarely have digital displays due to
   there being little demand for them. Less craftsmanship is required to
   make a digital face of a watch and most collectors find that analog
   dials (especially with complications)vary in quality more than digital
   dials due to the details and finishing of the parts that make up the
   dial (thus making the differences between a cheap and expensive watch
   more evident).

Watch functions

   All watches provide the time of day, giving at least the hour and
   minute, and usually the second. Most also provide the current date, and
   often the day of the week as well. However, many watches also provide a
   great deal of information beyond the basics of time and date.

   Some elaborate and more expensive watches, both pocket and wrist
   models, also incorporate striking mechanisms or repeater functions, so
   that the wearer could learn the time by the sound emanating from the
   watch. This announcement or striking feature is an essential
   characteristic of true clocks and distinguishes such watches from
   ordinary timepieces.

Complicated watches

   A complicated watch has one or more functionalities beyond the basic
   function of displaying the time and the date; such a functionality is
   called a complication. Two popular complications are the chronograph
   complication, which is the ability of the watch movement to function as
   a stopwatch, and the moonphase complication, which is a display of the
   lunar phase. Among watch enthusiasts, complicated watches are
   especially collectible.

Chronographs and chronometers

   The similar-sounding terms chronograph and chronometer are often
   confused, although they mean altogether different things. A chronograph
   is a type of complication, as explained above. A chronometer is an
   all-mechanical watch or clock whose movement has been tested and
   certified to operate within a certain standard of accuracy by the COSC
   (Contrôle Officiel Suisse des Chronomètres). The concepts are different
   but not mutually exclusive; a watch can be a chronograph, a
   chronometer, both, or neither.

Fashionable watches

   At the end of the 20th century, Swiss watch makers were seeing their
   sales go down as analog clocks were considered obsolete. They joined
   forces with designers from many countries to reinvent the Swiss watch.

   The result was that they could considerably reduce the pieces and
   production time of an analog watch. In fact it was so cheap that if a
   watch broke it would be cheaper to throw it away and buy a new one than
   to repair it. They founded the Swiss Watch company ( Swatch) and called
   graphic designers to redesign a new annual collection.

   This is often used as a case study in design schools to demonstrate the
   commercial potential of industrial and graphic design.

Collectible and jewelry watches

   Wristwatches are often treated as jewelry or as collectible works of
   art rather than as timepieces. This has created several different
   markets for wristwatches, ranging from very inexpensive but accurate
   watches intended for no other purpose than telling the correct time, to
   extremely expensive watches that serve mainly as personal adornment or
   as examples of high achievement in miniaturization and precision
   mechanical engineering, without any pretense at being accurate for
   telling the time. Still another market is that of “geek
   watches”—watches that not only tell the time, but incorporate
   computers, satellite navigation, complications of various orders, and
   many other features that may be quite removed from the basic concept of
   timekeeping.

   Most companies that produce watches specialize in one of these markets.
   Companies such as Rolex or Chopard specialize in watches as jewelry or
   fine mechanical devices. Companies such as Casio specialize in watches
   as timepieces or multifunctional computers. Since watches are
   considered by many to be both functional and attractive, there are many
   types and manufacturers to choose from.

   Important collectible American made watches from the early 20th Century
   were the best available at any price. Leading watchmakers included
   Elgin, Gruen, Hamilton, and Illinois. Hamilton is generally considered
   as having the finest early American movements, while the art deco
   styling of The Illinois Watch Company was unsurpassed worldwide. Early
   Gruen Curvex models remain very desired for how they entwined form and
   function, and Elgin made more watches than anyone else.

Advanced watches

   Many technological enhancements to wristwatches have been explored but
   most of them remained unnoticed. In 2005 for example, one company
   marketed an alarm wristwatch with an accelerometer inside that monitors
   the user's sleep and rings during one of his almost-awake phases.

   A number of functionalities not directly related to time have also been
   inserted into watches. As miniaturized electronics became cheaper,
   watches have been developed containing calculators, video games,
   digital cameras, keydrives, GPS receivers and cellular phones. In the
   early 1980s Seiko marketed a watch with a television receiver in it,
   although at the time television receivers were too bulky to fit in a
   wristwatch, and the actual receiver and its power source were in a
   book-sized box with a cable that ran to the wristwatch. In the early
   2000s, a self-contained wristwatch television receiver came on the
   market, with a strong enough power source to provide one hour of
   viewing.

   These watches have not had sustained long-term sales success. As well
   as awkward user interfaces due to the tiny screens and buttons possible
   in a wearable package, and in some cases short battery life, the
   functionality available has not generally proven sufficiently
   compelling to attract buyers. Such watches have also had the reputation
   as ugly and thus mainly geek toys. Now with the ubiquity of the mobile
   phone in many countries, which have bigger screens, buttons, and
   batteries, interest in incorporating extra functionality in watches
   seems to have declined.

   Several companies have however attempted to develop a computer
   contained in a wristwatch (see also wearable computer). As of 2005, the
   only programmable computer watches to have made it to market are the
   Seiko Ruputer, the Matsucom onHand, and the Fossil, Inc. Wrist PDA,
   although many digital watches come with extremely sophisticated data
   management software built in.

Spacewatches

   The Omega Speedmaster, selected by both Soviet and US space agencies.
   Enlarge
   The Omega Speedmaster, selected by both Soviet and US space agencies.

   Zero gravity environment and other extreme conditions encountered by
   astronauts in deep space requires the use of specially tested watches.
   During the 60s, a large range of watches were tested for durability and
   precision under extreme temperature changes and vibrations. The Omega
   Speedmaster was selected by both Soviet and US space agencies.

   The Breitling Navitimer Cosmonaute was designed with a 24-hour dial to
   avoid confusion between AM and PM, which are meaningless in space. It
   was first worn in space by astronaut Scott Carpenter on May 24th, 1962
   in the Aurora 7 capsule.

   More recently, Soviet and Russian cosmonauts have used the Fortis B-42.

   Chinese taikonauts wear the Fiyta spacewatches.

Mobile phones as pocket watches

   In the early 2000s, the carrying of mobile telephones has become
   ubiquitous in many affluent and even some developing countries. As
   these phones typically display the time on their screens when not in
   use, it has become common to rely on them for time-keeping, effectively
   making the mobile phone serve the function of a pocket watch.

   Retrieved from " http://en.wikipedia.org/wiki/Watch"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
