Power sources
Traditional mechanical watch movements use a
spiral spring called a mainspring as a power
source. In manual watches the spring must be
rewound by the user periodically by turning
the watch crown. Antique pocketwatches were
wound by inserting a separate key into a
hole in the back of the watch and turning
it. Most modern watches are designed to run
40 hours on a winding, so must be wound
daily, but some run for several days and a
few have 192 hour mainsprings and are wound
weekly.
A self-winding or automatic
mechanism is one that rewinds the mainspring
of a mechanical movement by the natural
motions of the wearer's body. The first
self-winding mechanism, for pocketwatches,
was invented in 1770 by Abraham-Louis
Breguet;[4] but the first "self-winding," or
"automatic," wristwatch was the invention of
a British watch repairer named John Harwood
in 1923. This type of watch allows for a
constant winding without special action from
the wearer: it works by an eccentric weight,
called a winding rotor, that rotates with
the movement of the wearer's wrist. The
back-and-forth motion of the winding rotor
couples to a ratchet to automatically wind
the mainspring. Self winding watches usually
can also be wound manually so they can be
kept running when not worn, or if the
wearer's wrist motions don't keep the watch
wound.
Some electronic watches are also powered
by the movement of the wearer of the watch.
Kinetic powered quartz watches make use of
the motion of the wearer's arm turning a
rotating weight, which turns a generator to
supply power to charge a rechargeable
battery that runs the watch. The concept is
similar to that of self-winding spring
movements, except that electrical power is
generated instead of mechanical spring
tension. Electronic watches require
electricity as a power source. Some
mechanical movements and hybrid
electronic-mechanical movements also require
electricity. Usually the electricity is
provided by a replaceable battery. The first
use of electrical power in watches was as
substitute for the mainspring, in order to
remove the need for winding. The first
electrically-powered watch, the Hamilton
Electric 500, was released in 1957 by the
Hamilton Watch Company of Lancaster,
Pennsylvania. Watch batteries (strictly
speaking cells) are specially designed for
their purpose. They are very small and
provide tiny amounts of power continuously
for very long periods (several years or
more). In most cases, replacing the battery
requires a trip to a watch-repair shop or
watch dealer; this is especially true for
watches that are designed to be
water-resistant, as special tools and
procedures are required to ensure that the
watch remains water-resistant after battery
replacement. Silver-oxide and lithium
batteries are popular today; mercury
batteries, formerly quite common, are no
longer used, for environmental reasons.
Cheap batteries may be alkaline, of the same
size as silver-oxide but providing shorter
life. Rechargeable batteries are used in
some solar powered watches. Some electronic
watches are powered by light. A photovoltaic
cell on the face (dial) of the watch
converts light to electricity, which in turn
is used to charge a rechargeable battery or
capacitor. The movement of the watch draws
its power from the rechargeable battery or
capacitor. As long as the watch is regularly
exposed to fairly strong light (such as
sunlight), it never needs battery
replacement, and some models need only a few
minutes of sunlight to provide weeks of
energy (as in the Citizen Eco-Drive). Some
of the early solar watches of the 1970s had
innovative and unique designs to accommodate
the array of solar cells needed to power
them (Synchronar, Nepro, Sicura and some
models by Cristalonic, Alba, Seiko and
Citizen). As the decades progressed and the
efficiency of the solar cells increased
while the power requirements of the movement
and display decreased, solar watches began
to be designed to look like other
conventional watches.[5] A rarely used power
source is the temperature difference between
the wearer's arm and the surrounding
environment (as applied in the Citizen
Eco-Drive Thermo).
Analog
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 "sweep second
hand", the name deriving from its
uninterrupted smooth (sweeping) movement
across the markers, although this is
actually a misnomer; the hand merely moves
in smaller steps, typically 1/6 of a second,
corresponding to the beat of the balance
wheel. 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.). They are specifically designed for
the left wrist with the stem (the knob used
for changing the time) on the right side of
the watch, this makes it easy to change the
time without removing the watch from the
hand.
Digital
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.,
12:40 AM instead of a short hand pointing towards the number
12 and a long hand pointing towards the number 8 on a dial.
Some watches, such as the Timex Datalink USB, feature dot
matrix displays. The first digital watch, a Pulsar prototype
in 1970, was developed jointly by Hamilton Watch Company and
Electro-Data. John Bergey, the head of Hamilton's Pulsar
division, said that he was inspired to make a digital
timepiece by the then-futuristic digital clock that Hamilton
themselves made for the 1968 science fiction film 2001: A
Space Odyssey. On April 4, 1972 the Pulsar was finally
ready, made in 18-carat gold and sold for $2,100 at retail.
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.[6] 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 and were much
more convenient in use, with the display always visible and
no need to push a button before seeing the time. 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, and the Cox Electronic
Systems Quarza.[7][8] Digital watches were very expensive
and out of reach to the common consumer up until 1975, when
Texas Instruments started to mass produce LED watches inside
a plastic case. These watches, which first retailed for only
$20, and then $10 in 1976, saw Pulsar lose $6 million and
the brand sold to competitors twice in only a year,
eventually becoming a subsidiary of Seiko and going back to
making only analogue quartz watches.
From the 1980s onward, technology in digital watches vastly
improved. In 1982 Seiko produced a watch with a small TV
screen built in and Casio produced a digital watch with a
thermometer and another watch that could translate 1,500
Japanese words into English. In 1985, Casio produced the
CFX-400 scientific calculator watch. In 1987 Casio produced
a watch that could dial your telephone number and Citizen
revealed one that would react to your voice. In 1995 Timex
release a watch which allowed the wearer to download and
store data from a computer to their wrist. Since their apex
during the late 1980s to mid 1990s high technology fad,
digital watches have mostly devolved into a simpler, less
expensive basic time piece with little variety between
models. Despite these many advances, almost all watches with
digital displays are used as timekeeping watches. Expensive
watches for collectors rarely have digital displays since
there is little demand for them. Less craftsmanship is
required to make a digital watch face 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).
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 watches
include alarms.Other elaborated 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. This feature is available on most
digital 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. Other more expensive
complications include, Tourbillion, Perpetual calendar,
Minute repeater and Equation of time. A truly complicated
watch has many of these complications at once (see Calibre
89 from Patek Philippe for instance). Among watch
enthusiasts, complicated watches are especially collectible.
Some watches include a second 12-hour display for UTC (as
Pontos Grand Guichet GMT).
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 watch 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.
Types
Fashion 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. 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. A dual time
watch is designed for travelers, allowing them to see what
time it is at home when they are elsewhere. Most companies
that produce watches specialize in one of these markets.
Companies such as Breitling, Patek Phillipe, Jaeger-LeCoultre,
Omega and Rolex specialize in watches as jewelry or fine
mechanical devices, while companies such as Casio specialize
in watches as timepieces or multifunctional computers. In
the 1980s, the Swiss Swatch company hired graphic designers
to redesign a new annual collection of non-repairable
watches.
Computerized multi-function watches
Many computerized wristwatches have been developed, but none
have had long-term sales success, because they have awkward
user interfaces due to the tiny screens and buttons, and a
short battery life. As miniaturized electronics became
cheaper, watches have been developed containing calculators,
tonometers, video games, digital cameras, keydrives, GPS
receivers and cellular phones. In the early 1980s Seiko
marketed a watch with a television in it. Such watches have
also had the reputation as ugly and thus mainly geek toys.
Several companies have however attempted to develop a
computer contained in a wristwatch (see also wearable
computer). As of 2005, these include the Timex Datalink,
Seiko Ruputer, the Matsucom onHand, and the Fossil, Inc.
Wrist PDA.
For space travel
Zero gravity environment and other extreme conditions
encountered by astronauts in space requires the use of
specially tested watches. On April 12, 1961, Yuri Gagarin
wore a Shturmanskie (a transliteration of Штурманские which
actually means "navigators") wristwatch during his historic
first flight into space. The Shturmanskie was manufactured
at the First Moscow Watch Factory. Since 1964, the watches
of the First Moscow Factory have been marked by a trademark
"ПОЛЕТ" and "POLJOT", which means "flight" in Russian and is
a tribute to the number of many space trips its watches have
accomplished. In the late 1970s, Poljot launched a new
chrono movement, the 3133. With a 23 jewel movement and
manual winding (43 hours), it was a modified Russian version
of the Swiss Valjoux 7734 of the early 1970s. Poljot 3133
were taken into space by astronauts from Russia, France,
Germany and Ukraine. On the arm of Valeriy Polyakov, a
Poljot 3133 chronograph movement-based watch set a space
record for the longest space flight in history. During the
1960s, a large range of watches were tested for durability
and precision under extreme temperature changes and
vibrations. The Omega Speedmaster was selected by U.S. space
agencies. TAG Heuer became the first Swiss watch in space
thanks to an Heuer Stopwatch, worn by John Glenn in 1962
when he piloted the Friendship 7 on the first manned U.S.
orbital mission. The Breitling Navitimer Cosmonaute was
designed with a 24-hour analog dial to avoid confusion
between AM and PM, which are meaningless in space. It was
first worn in space by U.S. astronaut Scott Carpenter on May
24, 1962 in the Aurora 7 mercury capsule.[9] Since 1994
Fortis is the exclusive supplier for manned space missions
authorized by the Russian Federal Space Agency. China
National Space Administration (CNSA) astronauts wear the
Fiyta[10] spacewatches. (For a list of NASA-certified
watches, see this footnote).[11]
For scuba diving
Watches may be crafted to become water resistant. These
watches are sometimes called diving watches when they are
suitable for scuba diving or saturation diving. The
International Organization for Standardization issued a
standard for water resistant watches which also prohibits
the term "waterproof" to be used with watches, which many
countries have adopted. Water resistance is achieved by the
gaskets which form a watertight seal, used in conjunction
with a sealant applied on the case to help keep water out.
The material of the case must also be tested in order to
pass as water resistant.[12] The watches are tested in still
water, thus a watch with a 50 meter rating will be water
resistant if it is stationary and under 50 meters of still
water. For normal use, the ratings must then be translated
from the pressure the watch can withstand to take into
account the extra pressure generated by motion. Watches are
classified by their degree of water resistance, which
roughly translates to the following:[13]
Water resistant - Will tolerate splashes of water or
rain
50 meter - Usable while showering, bathing,
dishwashing, and swimming in shallow water 100 meter -
Usable while swimming, and snorkeling
150 meter - Usable during general water sports
200 meter - Usable during general water sports,
including free diving
Diver's 150 meter - ISO standard for scuba diving
Some watches use bar instead of meters, which may then be
multiplied by 10 to be approximately equal to the rating
based on meters. Therefore, a 10 bar watch is equivalent to
a 100 meter watch. Some watches are rated in atmospheres (atm),
which are roughly equivalent to bar.
History
In the 15th century, the increase in European sea-goingnavigation
and mapping increased the demand for a portable timepiece,
because 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) using the time kept on a shipboard clock.
However, the process was notoriously unreliable until the
introduction of John Harrison's marine 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 simple weighted pendulums, which are unworkable when
irregular movement of the fulcrum occur whether 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 by 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.[14] Early watches only had an hour hand—a minute hand
would have been useless because of the inaccuracy of the
watch mechanism. Eventually, miniaturization of these
spring-based designs allowed for accurate portable
timepieces (marine chronometers) 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
perpetual in 1780.[15]
