The Fundamentals of Display Technologies 1589- When a voltage is applied to the diode, holes (posi-
tive charges) and electrons (negative charges) meet in
the active layer to produce light. - The wavelength of light emitted by the diode is
dependent on the chemical composition and relative
energy levels of the doped semiconductor materials,
and can be varied to produce a wide range of wave-
lengths. - After being fabricated, the chip is mounted in a
reflector cup connected to a lead frame, and is
bonded with wire to the anode and cathode terminals. - The entire assembly is then encased in a solid epoxy
dome lens that enables emitted light to be focused,
controlled by embedding tiny glass particles into the
lens that scatter light and spread the light beam, or
angled, via changing the shape of the lens, or the
reflector cup.
44.9 Resolution
What is resolution? A simple definition of resolution is
the degree of sharpness and clarity of a displayed
image. In LED displays, resolution is determined by the
matrix area and pitch.
The area, also known as the pixel matrix, corre-
sponds to the number of pixels that make up the display
area. In our industry, we express the matrix area in the
number of pixels vertically by number of pixels hori-
zontally, such as 16 × 64.
The pitch is defined as the distance between two
pixels. The distance is measured from the center of one
pixel to the center of the next pixel.
Pitch can also influence the pixel matrix for a given
area. For example, a 16 mm pitch will give you a 5 × 7
matrix area, while a 10 mm pitch will give you a 8 × 11
matrix area for the same area.
Pitch determines the amount of empty space between
the pixels.
Therefore, the smaller the pitch and larger the matrix
area, the greater the resolution.44.10 ConclusionThe one thing we can be certain of is that display tech-
nologies are constantly evolving with advances taking
place in months not years. We can look forward to
plasma and LCD displays becoming thinner and lighter
with significant power consumption reduction while pro-
ducing brighter displays with longer panel life. Environ-
mentally unfriendly CCFL backlights in LCD displays
will be replaced with LED and laser illumination will
gain acceptance for projectors and RPTVs. OLED is set
to take on conventional LCD and plasma displays and
will become larger and more economically priced in the
next few years. The only constant is change in the world
of display technologies and we all benefit in the end.