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OLED
Tutorial
Organic Light-Emitting Diode (OLED) technology
An OLED is an electronic device made by placing a series
of organic thin films between two conductors. When electrical current
is applied,
a bright light is emitted. This process is called electrophosphorescence.
Even with the layered system, these systems are very thin, usually
less than 500 nm (0.5 thousandths of a millimeter).
When
used to produce displays, OLED technology produces self-luminous displays
that do not require backlighting. These properties result in thin,
very compact displays. The displays also have a wide viewing angle,
up to 160 degrees and require very little power, only 2-10 volts.
OLED
displays have other advantages over LCDs as well:
- Increased brightness
- Faster response time for full motion video
- Lighter weight
- Greater durability
- Broader operating temperature ranges
There
are two types of OLED displays - passive and active. These distinctions,
plus narration about the OLED 2001 conference and the market challenges
that the technology will face can be read in WAVE
151 or as a separate article on the WAVE
Report site.
Coverage of the OLED 2002 conference was
published in WAVE 0245.
Comparing
Technologies
Liquid Crystal Displays (LCDs)
For comparison, LCDs, which are widely used today, are nonorganic,
nonemissive light devices, which means they do not produce any
form of light. Instead they block/pass light reflected from an
external light source or provided by a back lighting system. The
back lighting system accounts for about half of the power requirements
for LCDs, which is the reason for their increased power consumption
(over OLED technologies).
LCD
production involves the same sort of layering technique used
in OLED displays, with some modification. First there is the
formation
of electrodes on two glass substrates. Then the substrates are
joined together and the liquid crystals are sealed within them.
Backlights are used to spead light out by a thin light difuser.
Finally the system is placed into a metal frame.
Cathode Ray Tubes
(CRTs)
Displays made from CRTs are produced using electron tubes
in which electrons are accelerated by high-voltage anodes, formed
into a beam by focusing electrodes, and projected toward a phosphorescent
screen that forms one face of the tube. The electrons beam leaves
a bright spot wherever it strikes the phosphor screen.
Pros and Cons
CRTs
- Cost
less and produce a display capable of more colors than LCD displays.
- CRTs
also use emissive technology, meaing that they can provide their
own light - this means you can view images from any angle.
LCDs
- LCDs have gained popularity due to their smaller, lighter
form factor and their lower power consumption.
- Many users report lower eyestrain and fatigue due to the
fact that LCD displays have no flicker.
- LCDs emit fewer low-frequency electromagnetic emissions
than CRTs.
Additional
sources of information*
Oled-Info.com
Oled-display.net
WAVE
Article - OLED 2002
WAVE
Article - OLED 2001
Kodak
OLED Tutorial
Sarnoff
Corporation - AMOLED
How
Stuff Works - LCDs
Companies
Developing OLED Displays
Cambridge
Display Technology
Universal
Display Corporation
Dupont
Displays - Olight
Siemens
Kodak
*The WAVE Report is
not responsible for content on additional sites. |
