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Ed's AV Handbook
Batting Practice for the AV Professional
and primer for the novice

Chapter 4  Page 6

Video Reproduction
The TV part 2

Light Emitting Diode TV

Organic and Inorganic light-emitting diode (LED) television offers unrivaled contrast.  Both provide a more dynamic grayscale and broader color volume than LCD television.  The source of light-emitting diode  technology lies in the oldest of solid-state technologies, the diode.

The Old Diode

OLED & IOLED descend from the pioneer of solid-state electronic technology - the diode.  An early example is the 1906 crystal radio.  It used a diode crystal called a 'cat's whisker' to detect electromagnetic radio waves (continuous electric sparks), induce an electric-magnetic current, and modulate a crystal earphone that created audible radio.  This 'old diode' consisted of mineral crystals such as galena -- lead crystal.

Another characteristic of the diode passes electric current in one direction while blocking electric current in the opposite direction.  This one-way behavior is called rectification. This trait is demonstrated by the rectifier that converts alternating current to direct current in the electrical product throughout our homes.

Diodes regulate voltage, protect circuits from surges, detect and generate radio waves, produce light.  Diodes perform these functions by varying their materials and using a technique of adding impurities called doping.  The diode materials include organic carbon-based silicon and inorganic substances such as germanium. 

Electroluminescence 

Light from a diode, derived from the phenomenon of 'electroluminescence', is an electrical phenomenon in which a material emits light in response to the passage of an electric current.  Diodes that produce light are the basis of OLED and IOLED TV.
Light Emitting Diode

OLED & IOLED TV

An OLED and IOLED television screen is a solid-state electronic device.
An electroluminescent layered cell-plate or film situated between anode and cathode electrodes.
The electrodes are a transparent front anode overlay and a rear metallic cathode layer. 
They and a transport layer sandwiched the electroluminescent cell. 

The Layers:
   1. A hole-injection layer
   2. A hole-transport layer
   3. An emmisive layer.
   4. an electron-transport negative layer.

Injected positive and negative electric charges recombine in the emissive layer to produce electroluminescent light.  The brightness and color are enhanced by 'doping' the emissive layer with a small amount of highly fluorescent molecules.  The result offers a lower black level, improved contrast, and a wider grayscale with more accurate broader color volume than LCD TV.

OLED IOLED Difference

IOLED screens are inorganic semiconducting crystal wafers made of gallium arsenide or gallium nitride.  OLED screens are organic crystal wafers made of materials such as plastic or glass. Due to lower thermal conductivity, an OLED emits less light than IOLED.  IOLED also has a longer illuminating life than OLED.  Yet OLED screens still have a life expectancy that is similar to plasma and LCD technologies. The key difference is cost.  OLED is less expensive to produce than IOLED.

OLED Buzz Words

Manufacturers will attempt to differentiate their LED based TVs from their competitors.  Therefore, prepare for an advertising avalanche of video 'buzz words'. 
Here is a shortlist of what you may confront.

AMOLED

Active Matrix OLED or AMOLED uses a thin-film transistor (TFT) backplane to control each sub-pixel of the display -- on/off or more/less light.
All OLED and IOLED televisions are active-matrix technology.

AMOLEDAMOLED TFT ARRAY

Super AMOLED / WOLED

WOLED, also referred to as Super-AMOLED, pairs a fourth white sub-pixel with red, green, and blue sub-pixels.  The extra white sub-pixel increases brightness.  There are two versions of AMOLED/WOLED. The first by LG OLED does not use side by side red, green, and blue OLED sub-pixels.  They stack a red, a green, and a blue OLED to produce a single sub-pixel. The RGB stack creates accurate white light.  LG then filters each white stack with a red, green, or blue filter.  A fourth remaining sub-pixel is left unfiltered.  A second discontinued Samsung version used side by side red, green, blue, and white OLEDs.  The LG stacked-method cost much less to manufacture. 

Changing LED Scene

LG WOLED technology has had the lead in the OLED market place.  But the LED race is heating up. 
Samsung is reentering the LED race with modified OLED and IOLED technologies.  

Samsung QD-OLED TV

Quantum Dot (QD) OLED eliminates the LG color filtered RGB stacked OLED white light concept.  QD-OLED employs a blue OLED layer to excite/illuminate red and green quantum dot film.  Some refer to this as color by blue.  Red and green sub-pixels are produced by the excited quantum dots.  Blue sub-pixels are produced by the blue OLED layer.  This method offers higher brightness, improved contrast, and a broader volume of color.  QD-LED

Samsung Micro-LED TV (IOLED)

Samsung has also developed a MicroLED TV.  It uses a micrometer-sized inorganic LEDs to produce individual red, green, blue IOLED sub-pixels. This Samsung technology offers two key features.

            1. Inorganic not organic LEDs.           
            2. It also eliminates color filters.

An inorganic LED offers longer life than an organic LED.  Eliminating filters increases brightness.  IOLED also avoids the possibility of screen burn-in.  A wall-sized commercial Micro-LED display is currently available. 

A smaller retail-friendly size version is not yet available.  But Micro-LED may become a potential alternative to home theater projection systems.

Samsung QNED TV

QNED

QNED TV is a quantum dot nanorod LED TV.  QNED as QD-OLED is a color-by-blue display.  But QNED replaces organic LEDs with inorganic LEDs.  As previously mentioned, inorganic LEDs are brighter with longer illuminating life.  QNED also cost less to manufacture than Micro-LED TV.  QNED should be the first IOLED TV to reach retail floors in the 2nd quarter of 2021.

Handbook QNED Note:
Current publicity does not describe QNED as inorganic LEDs.  But published QNED Illustrations have listed GaN (Gallium Nitride) as the essential component of the nanorod LED.  GaN crystal is an inorganic substance.

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Ed's AV Handbook   
Copyright 2007 Txu1-598-288 Revised 2021


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