A watch is a timepiece that is made to be worn on a person,
as opposed to a clock which is not. The term now usually
refers to a wristwatch, which is worn on the wrist with
a strap or bracelet. In addition to the time, modern watches
often display the day, date, month and year, and electronic
watches may have many other functions.
Most inexpensive and medium-priced watches used mainly
for timekeeping are electronic watches with quartz movements.
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 less accurate than
more affordable quartz movements. Before the inexpensive
miniaturization that became possible in the 20th century,
most watches were pocket watches, which had covers and were
carried in a pocket and attached to a watch chain or watch
fob. Watches evolved in the 1600s from spring powered clocks,
which appeared in the 1400s.
Mechanical movements
Compared to electronic movements, mechanical watches
are less accurate, often with errors of seconds per day,
and they are sensitive to position and temperature. As well,
they are costly to produce, they require regular maintenance
and adjustment, and they are more prone to failure. Nevertheless,
the "old world" craftsmanship of mechanical watches
still attracts interest from part of the watch-buying public.
Mechanical movements use an escapement mechanism to control
and limit the unwinding of the watch, converting what would
otherwise be a simple unwinding, into a controlled and periodic
energy release. Mechanical movements also use a balance
wheel together with the balance spring(also known as Hairspring)
to control motion of the gear system of the watch in a manner
analogous to the pendulum of a pendulum clock. The tourbillon,
an optional part for mechanical movements, is a rotating
frame for the escapement which is intended to cancel out
or reduce the effects of bias to the timekeeping of gravitational
origin. Due to the complexity designing a tourbillon, they
are very expensive, and only found in "prestige"
watches. The pin-lever, (also called Rosskopf) movement,
after its inventor: Georges Frederic Roskopf, is a cheaper
version of the fully levered movement which was manufactured
in huge quantities by many Swiss manufacturers as well as
Timex, until it was replaced by quartz movements.
Tuning fork watches use a type of electromechanical movements.
Introduced by Bulova in 1960, they use a tuning fork at
a precise frequency (most often 360 hertz) to drive a mechanical
watch. The task of converting electronically pulsed fork
vibration into rotary movement is done via two tiny jeweled
fingers, called pawls. Tuning fork watches were rendered
obsolete when electronic quartz watches were developed,
because quartz watches were cheaper to produce and even
more accurate.
Electronic movements
Electronic movements have few or no moving parts, as
they use the piezoelectric effect in a tiny quartz crystal
to provide a stable time base for a mostly electronic movement.
The crystal forms a quartz oscillator which resonates at
a specific and highly stable frequency, and which 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. 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. Some watchmakers
combine the quartz and mechanical movements, such as the
Seiko Spring Drive, introduced in 2005.
Radio time signal watches are a type of electronic quartz
watches which synchronizes (time transfer) its time with
an external time source such as an atomic clocks, time signals
from GPS navigation satellites, the German DCF77 signal
in Europe, WWVB in the US, and others. 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).
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 moon phase 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 (you may want to also research the 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.
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.
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 space-watches. (For a list of NASA-certified watches, see this
footnote).
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:
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.
You may want to do some additional research. If are interested, you can
investigate the following topics.
American Watchmakers-Clockmakers
Institute
Clock
Mechanical watch
Chronometer watch
Marine chronometer
Calculator watch
Horology
Watch manufacturers
Watch Brands
National Association of Watch and Clock Collectors
Timepiece
Wearable computer / Wearable Technology/ Smart Watches
Compass direction using a watch
BaselWorld
Wrist watch (history)
Georges Frederic Roskopf
Jewel bearing
Automatic Watch Winder
Jewelry
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