The TV part 1 canvasses
discontinued and waning technologies of the CRT, Plasma, and
LCD. It also outlines current home theater projector
The next page, part 2, features
the advanced LED technologies of OLED, IOLED, and Micro
The Relevant Past
As LCD TV dominance comes to an end, we begin with the
discontinued CRT and Plasma TV technologies. All are
relevant to understanding the TV.
Cathode Ray Tube (CRT)
The cathode ray tube, the technology that launched television,
dominated the 20th Century. CRT Color TV's key
components include the cathode, the anode, two electromagnets,
an electronic steering circuit, a shadow mask, and vertical
sets of red, green, & blue phosphor stripes.
Anode/Cathode Electron Gun
Similar to an incandescent light bulb filament, three
filaments in the cathode
generate three distinct negative charged electrical
currents. Each assigned a primary video color. The
draws each stream from the cathode. The combined cathode-anode
produces an electron gun
that generates a tight three beam stream. The RGB
voltages modulate each
assigned color beam.
The electron gun beam targets the
center of the shadow mask.
The mask plus screen-wide vertical sets of red,
green, & blue phosphor
stripes are adjacent to the front TV screen.
Two separate electromagnetic
coils encircle the three beams. The first coil
shifts the electron beams vertically up and down. The
second coil sweeps the electron beams horizontally left to
right. A steering circuit,
directed by the horizontal & vertical
synchronizing signals, controlls each
Modulating Electron Beams
The three modulating electron beams, guided by the
electromagnetic coils, navigate the screen from left to right,
top to bottom. Each beam aligns with its assigned red, green,
or blue vertical phosphor stripe located
behind the shadow mask. The shadow
mask, a fine wire mesh of about 482 rows by 720 holes
per row, allows the phosphorescent light to pass. This
framed array of passing-light creates illuminated pixels that
recreate an image on the screen.
Rear Projection CRT TV
The rear projection CRT TV consisted of three
mounted at the bottom of a large
enclosure. They were generally about 5 to 7 inches in
diameter. Each had a dedicated red, green, or blue
An assembly of a magnifying
lens attached to each CRT
Each assembly mated to its primary color voltage. Each
magnified image converged at a large-first-surface
at the rear of the enclosure. The mirror
redirected the magnified light through
three front-mounted translucent screens
The the Fresnel
(fra-nell) screen lens and the Lenticular
screen lens redirected
the light. The Fresnel lens redirected the light
perpendicularly from its surface. The Lenticular lens
redistributed light laterally. A
third protection screen shielded
the Fresnel and Lenticular lenses from dust and scratches.
The plasma TV was a mosaic matrix array of neon/zeon
gas-filled phosphor-coated glass cells; red, green, blue
phosphor. The TV video processor applied voltage to each
cell as dictated by the video signal.
Electrically-ionized-gas emitted ultraviolet light.
Ultraviolet light illuminated the red, green, or blue
phosphor. The illuminated array recreated the original
As explained on page 3, digital TV builds each video frame
line by line. Plasma, LCD, OLED, IOLED, LED TV video
processors hold the lines of data until they have a complete
frame. They then flash the entire video frame to the
LCD TV, a back-lit array of red,
green, or blue
color filtered liquid crystal pixels, controlled by a
thin-film transistor (TFT) backplane.
Each pixel is a string of crystals suspended in a
liquid. A front crystal anchors the crystal
string. Like a row of dominoes, each following crystal
stands parallel but slightly off-axis. Each pixel string
allows polarized light to pass until the crystal string begins
to unwind and block light.
Front and rear glass plates sandwich the LCD array. The
rear-plate encases the TFT grid of electrical conducting
points that align behind each LCD pixel string. The
electrical-conducting points control the amount of unwind. The
voltage specified by the video decoder controls the
conducting-point. The picture is the array-sum of the
illuminated red, green, and blue filtered pixels.
LCD Back Lighting
There are two types of LCD TV backlighting -- fluorescent and
LED. LED lighting consumes less energy than fluorescent
lights. LED lighting is also much thinner than
fluorescent lights. Thin sells TVs.
LED Back Lighting
LED backlighting consist of two types -- full-array
. Full-array is an array of LED
blocks placed behind the panel.
Edge-lit installs LEDs around the edge of the TV panel.
A diffuser panel redistributes light across the entire
Quantum Dot Fix
LED backlighting does not produce accurate white light.
It leans toward the color blue, which distorts RGB
color. Quantum dot film -- placed between the LED
lighting and the LCD layer -- fixes the problem. Quantum
dots are nanocrystals that illuminate when struck by LED
light. A mix of red and green Q-Dots plus blue LED light
produces accurate white back-light that improves video color.
Mini-LED Back Lighting
A mini-LED is smaller than 0.2-millimeters. It allows
for more block-zones of LCD backlighting. As an example, a
recent 65 inch LCD TV with more than 25,000 min-LEDs offered
more than 1000 zones of backlighting. To put this in
perspective, a typical 75-inch full-array backlight LCD TV may
have up to 500 zones. The increase in zones improves contrast
and supports HDR formats.
1. A min-LED is not a
micro-LED. Micro-LED is introduced later on this page.
2. Beware of advertising that obscures the term LCD in the
description of an LED-back-lit LCD TV or a Quantum Dot
back-lit filtered TV. It is an attempt to imply that an
LCD TV is an LED or a Quantum-Dot TV. Real Q-Dot TV has
not yet reached retail floors. Currently, OLED, and soon
IOLED, is the only real LED TV on the market.
Home Theater Projectors
An LCD projector consists of a bright lamp targeted through
polarizing mirrors that split and redirect the light with one
path each to a red-filtered, green-filtered, and blue-filtered
LCD mosaic chip. Each mosaic passes or blocks light per
its color video instruction. The polarized mirror
assembly recombines and projects the red, green, blue light
through magnifying lenses to the projection screen.
A digital light projector (DLP) features a Digital
or DMD. The DMD is an
integrated chip comprised of a mosaic matrix of microscopic
mirrored pixels. Each micro-mirror is mounted on a pivot and
, plus or minus ten/twelve
A DLP assembly begins with a bright lamp or laser light that
creates a light beam directed through a spinning color
, and blue
filters in route to the micro-mirrors of a single DMD
chip. The tilt of the mirrors reflects and directs the
color light into an empty enclosed area within the projector
or through a magnifying lens
assembly on route to a
projection screen. A video digital controller coordinates each
mirror's tilt with the color wheel to recreate the correct mix
and amplitude of red, green, blue light and recreates the
A more costly version of the DLP projector engages three
separate DMD chips and eliminates the color wheel. As an
LCD projector, the light targeted through polarizing mirrors
splits into three beams. Each beam directed through a
red, green, or blue filtered DMD, and recombines, and projects
to the screen.
LYCOS / DILA Projector
LYCOS and DILA projection TV is an LCD projector with a
different polarizing twist. It's a bit of DLP and LCD
combined. Similar to the LCD projector, the LYCOS/DILA
projector includes a bright light, a polarizing beam splitting
mirror, and three color-filtered LCD mosaics.
The difference is the addition of a mirrored surface behind
each LCD mosaic. In this case, the light passes through the
mosaic. Its mirrored surface reflects the light through
the LCD mosaic chips the polarized mirrors. The
polarized mirror assembly recombines and projects the light
through the magnifying lenses to the projection screen.