LED display

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One of the early LED digital watches of the 1970s with a seven-segment display . Because of the high power consumption, the display usually had to be activated by pressing a button.
Display of the TI-30 (from 1976), one of the first pocket calculators to be used in schools .
Dynamic indicator on a station of the Erzgebirgsbahn (2018).

A LED display (of LED , English light-emitting diode , or "light-emitting diode display") is a display device based on light-emitting diodes .

There are three types of LED displays:

  1. LED displays, which consist of individual, discrete, point-like , inorganic monocrystalline LEDs.
  2. LED displays, which are composed of individual, discrete, elongated , inorganic monocrystalline LEDs.
  3. LED displays, which are made up of organic light-emitting diodes in thin-film technology on a common substrate as integrated matrices (so-called OLEDs ).

History and overview

The first commercially used LED displays of types 1 and 2 as defined above were prepared from monolithic gallium arsenide - monocrystalline by sawing prepared and contacting. From this, among other things, numeric displays consisting of seven LED segments each ( seven-segment displays , type 2) were realized, which were used in products such as the first digital watches or pocket calculators at the beginning of the 1970s as glowing red displays. These were replaced around the beginning of the 1980s by LCD displays , which had a much lower power consumption.

Red-colored alphanumeric classified ads followed later, consisting of discrete, point-like LEDs of type 1 arranged in a matrix. One example of application are scrolling text displays ( dynamic text displays ) that are still used today for example. B. can be used by retailers or small service providers in the shop window, but also at train stations.

After different color displays were made possible by combining different colored LEDs ( additive color mixing of red, green and blue), the need for large displays of type 1 arose, especially in the advertising industry and in sports stadiums mm, which means that small-format displays from 82 "in full HD resolution can also be produced for indoor use . The devices are mostly suitable for displaying HDR video and are characterized by their durability and brilliance that even surpasses OLEDs. A more detailed description can be found under video wall .

Since the late 2000s, small-format screens with organic light-emitting diodes (OLEDs) in thin-film technology have been sufficiently mature to partially replace the previously common LC displays (LCDs) in smartphones , digital cameras and tablet computers . OLED displays have also been used since the 2010s, in which the individual pixels are controlled by means of thin-film transistors in the form of an active matrix (AM). These are often called AMOLED displays ( active matrix organic light emitting diode ).

See also

Individual evidence

  1. ↑ Nick Holonyak, SF Bevacqua: Coherent (visible) light emission from Ga (As1-xPx) junctions . In: Applied Physics Letters . tape 1 , no. 4 , December 1962, p. 82-83 , doi : 10.1063 / 1.1753706 .