The need arose to measure time with the development of agriculture. The farmers were the days best plants and primitive lunar calendar periods to be determined.
The Egyptians were the first to widely develop a means to measure time with clocks and calendars. By about 2800 BC they had established a 365-day calendar, based on their observations, the rise and fall of bright stars like Sirius and the periodic flooding of the Nile, thedependent on their agriculture. By 2100 BC the Egyptians the opportunity to share the day was developed in 24 hours. Around the same time made the first sundials or shadow clocks to measure time during the day. A sundial shows time of day for the position of the shadow of an object falling on the rays of the sun.
In 1500 BC the Egyptians had another way, more precise measurement of time in water, or water clock, which uses the constant dripping of water from one container to another disk inventedmechanical device that tells the time.
Babylonian astronomers' development of the water meter, taking into account the equation of time due to the varying distance between Earth and the sun causes, how it moves in an elliptical orbit. Since this effect could the lunch hour before or after the time when the sun is high in the sky.
Designed around 270 BC, the Alexandria Technical Ctesibios water clocks, the bells were ringing, dolls, and caused the mechanical singing birds.The water clock remained in use until the development of mechanical clocks nearly 3,000 years later.
The measurement of short intervals, but it has been possible with the hourglass. The search for precision watches began with the late medieval flourishing trade and the first fruits of the scientific revolution. This must lead the mechanical clock, time with simple weighted pendulum is measured. But these were not viable.
The first watches
The invention of the sources andMechanism of inhibition marked the era of portable clocks. The inhibition is a mechanism that limits and controls the execution of the clock, converting what would otherwise be simply an energy relaxation, releasing in a controlled environment and regular. The escapement does this by interlocking with a gear in a simple, "driven" and that between a state "free", with a sudden turn the latch on each end of the cycle. The escapement also for the same reason produces the ticking noise characteristicmechanical watches.
Another mechanical method is the mechanism wheel balance. The balance with the balance (also known as spiral) - this form of a simple harmonic oscillator that controls the movement of the march of the clock in a similar way the pendulum of a grandfather clock. This is possible because the inertia of the barbell is fixed, and the wheel as a whole provides a regular motion of known period. These produce watchesTick.
Purely mechanical watches are still popular. The craftsmanship of purely mechanical watches is much of its attractiveness. Compared to electronic movements, mechanical watches are inaccurate, often with errors of seconds per day. They are often sensitive to the position and temperature, are expensive to produce, they need regular maintenance and adjustment, and are subject to errors.
Improved accuracy was achieved in the sixties byTuning fork watches use a tuning fork at a precise frequency changer (usually 360 Hz) for a mechanical watch. Since the fork is used instead of a typical balance wheel, these watches are naturally hum instead of tick. Tuning fork movements are electromechanical. The task of converting electronically pulsed fork vibration into rotary motion by means of two tiny fingers precious stones, such as latches, one of which is connected to a tuning fork made. As the fork vibrates, the pawlsOnly a small index ratchet wheel. This index has over 300 bikes barely visible teeth and spins more than 38 million times a 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 in 1950's and early 60's as a prototype.
Advent of electronic quartz watch in 1969
Max Hetzel in 1948 used an electronic device, a transistor, which createthe first electronic watch. This development is obsolete with the use of a quartz crystal in quartz watches that use the piezoelectric effect in a tiny quartz crystal to provide a stable time for a mostly electronic movement: the crystal oscillator is a Quartz, a specific resonant frequency and very stable, and the pace can only be a timing mechanism. These movements are mainly oriented electronics to drive mechanical hands on the facethe clock. Quartz movements are ten times better than a mechanical movement.
Other developments were the following types of clocks:
Manual watches
Bred in the spring clocks manually, you should periodically turning the crown of the watch.
A winding or automatic watches
An automatic transmission or automatic is what is the spring of a mechanical movement with the natural movement of the wearer's body wraps.
Automatic kinetic powerQuartz
Some electronic watches are powered by the movement vector with the power clock. Kinetic powered quartz watches use the motion of the arm turning a rotating weight, which makes a battery to power a generator that runs the clock manager. The concept is similar to the one-winding spring movements, except that the power is generated instead of mechanical force of the spring.
Battery-powered watches in 1957
ElectronicWatches require electricity as an energy source. Some mechanical movements and hybrid electronic-mechanical movements also require electricity. Normally, the flow through a replaceable battery. Watch batteries (strictly speaking cells) are specially designed for the purpose. They are very small and provide small amounts of energy continuously for long periods (several years or more). Mercury batteries, which are harmful to the environment than silver oxide and lithium batteries. InexpensiveThey are alkaline, silver oxide, the same size, but provides a shorter duration. The batteries are used in some solar powered watches.
Wrist Light
Some electronic watches are powered by light. A photovoltaic cell on the face of the watch converts light into electricity, which in turn uses a rechargeable battery. The watch movement is powered by the battery. Until the clock regularly exposed to strong enoughLight (sunlight, for example), does not need to replace the battery, and some models need a few minutes of sunlight to provide energy in weeks.
Some of the early solar watches of 1970 had a unique and innovative design, the array of solar cells is necessary to feed them (Nepro, and some models of Cristalonic Sure, Alba, Seiko and Citizen) to accept. Over the decades, has developed and improved the efficiency of solar cells, while the current needs of the movement and displaydecreased, solar watches began designed to look like other conventional watches.
Radio-controlled movements
Some electronic quartz watches are able to synchronize with an external time source. These sources include the time radio signals directly driven by atomic clocks, time signals from GPS navigation satellites, the German DCF77 signal in Europe, WWVB in the U.S. and others. These watches are free-running most of the time, but close at regular intervals, theautomatically selected external source of time, usually once a day.
Since these watches are regulated by an external time source extremely high precision, never have more than a small fraction of a second day (depending on the quality of their quartz movements), provided they receive signals external time they expect. In addition, long-term accuracy comparable to that of the external timing signals they receive, which in most cases (eg GPSSignals and special radio broadcasts of the time based on atomic clocks) is better than 1 second in 3 million years. For practical purposes, then keep almost perfect time radio watches.
To synchronize the movements of this kind not only the time of the day, but also the date, leap year status for the current and the current state of daylight saving time (on or off). You can get all this information by external signals they receive. For this reasonContinuous auto-update, never had a manual or reset.
One disadvantage of remote control of movements is that you do not synchronize if radio reception is poor. In this case, however, will simply run autonomously with the same precision as a normal quartz watch until they are next able to synchronize.
See display
Have been developed in the seventies, two types of displays.
Analog display
A numbered dial, mounted onat least a rotating hour hand and a hand longer, turning minutes. Many watches also have a third hand that shows the current minute of the second current. Watches powered by quartz have second hands that snap every second to the next marker. Watches have a mechanical movement powered by a "second hand", the name comes from its uninterrupted smooth (sweeping) movement across the markers, the hand only moves in small increments, typically 1 / 6 of a second, according to the rhythmbalance. All hands will be produced are usually mechanical, physically rotating on the dial, although a couple of watches with the "hands", simulated by a liquid crystal display.
Digital display
A digital display simply shows the time as a number, such as 0:40 AM instead of a hand pointing to the short number 12 and a long hand pointing to the number 8 on a dial.
The LEDs were (LCD) are replaced, the less energy and have been usedmuch easier to use, the display always visible and do not have to click a button to push ahead of time.
Since 1980, technology in digital watches greatly improved. The new features have been added each year.
1982 Seiko produced a small clock with built-in screen TV
1983 Casio produced a digital watch with a thermometer and another to see that 1500 could translate the Japanese words in English
1985 Casio produced the CFX-400 scientific calculatorobserved.
1987 Casio produced a watch that your telephone number and Citizen you may respond to your voice can dial.
1995 Timex release a watch, which allows the wearer to download and store data from a computer on the wrist.
