A digital watch or digital display is a watch without needles . Often also referred to as abuse of language digital watch 1 , it displays the time in the form of digits , by different means:
- By small mobile mechanical panels or sometimes covering themselves successively
- Of the light emitting diodes
- of liquid crystals , a technique which was invented by Gordon Moore , creator of one of the leading manufacturers of digital electronics , Intel .
Used in many electronic devices, the light emitting diode (LED or English LED) produces light when a current flows through. For example, digital watches include a 7-segment display , making it possible to form any digit from 0 to 9.
Its main advantages are:
- A lifespan of approximately 100,000 hours or more than 10 years without stopping
- Perfectly adapted to low lighting
- Higher efficiency (battery economy) than filament bulbs , but lower than that of liquid crystals
- Exceptional impact resistance
Some liquid crystals reflect different wavelengths of light as a function of the orientation of their molecules, which depends on the temperature. Thus, they are used for the design of thermometers displaying different colors according to the temperature of the body with which the liquid crystal is in contact.
Liquid crystals are used for the display, in the screens of digital watches, calculators, small televisions, laptops, etc. Liquid crystal displays often use less energy than conventional displays, such as those using diodes.
There are several types of liquid crystals in organic substances: liquid myelinic, smectic (layered) and nematic (liquid birefringent) crystals, each of which is characterized by a different arrangement of molecules in space. The optical properties of a liquid crystal can be demonstrated by applying a magnetic or electrical field to it which modifies the orientation of its molecules. For example, when a small electric field is applied to certain liquid crystals, a change in hue of the crystal is observed, which changes from a light shade to a dark shade. The crystal may also acquire the property of rotating the plane of polarization of the light.
At sufficiently high temperatures or low pressures, the orientation of the molecules disappears, causing the liquid crystal to become liquid. At sufficiently low temperatures or at sufficiently high pressures, the molecules of a liquid crystal move with difficulty relative to one another: the liquid crystal solidifies.
History of digital watches
- 1967: 1 st quartz wristwatch in the world, the Beta 21 .
- 1969: 1 st shows marketed quartz, but also the 1 st shows LEDs and one re watch LCD .
- 1971: 1 st plastic watch two .
- 1975: 1 re quartz analog wristwatch liquid crystal display.
- 1977: HP markets the first watch with built-in calculator , the HP-01 .
- 1981: 1 re quartz watch without electric battery: a thermoelectric generator converts the thermal flux passing through the watch into electrical energy that is stored in an electricity storage device .
- 1982: 1 st plastic watch where the wheels are implanted directly into the body.
- 1990: 1 re wristwatch radio shows radio controlled receives the radio signals from a radio transmitter which periodically transmits the time, among others .
- 1996: 1 re quartz watch without electric battery using an electrodynamic generator, the generated electricity is stored in a capacitor .
Notes and references
- ↑ digital is an anglicism coming from the English digit (number) and is confusing because digitale means belonging to the finger in French (ex: fingerprints)
- ↑ Technological Innovations [ archive ] , on the website argusdesmontres.com, accessed November 29, 2012