The TV part 1 canvases the
discontinued and waning technologies of the CRT, Plasma, and
LCD. Part 1 also outlines current home theater projector
technology. The next page, part 2, features the advanced
LED technologies of OLED, IOLED, and Micro LED.
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 is a mosaic matrix array of neon/zeon gas-filled
phosphor-coated glass cells; red, green, blue phosphor.
The TV video processor applies voltage to each cell as
dictated by the video signal. Electrically-ionized-gas
emits ultraviolet light. Ultraviolet light illuminates
the red, green, or blue phosphor. The illuminated array
recreates the original picture.
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 on the next 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. OLED, IOLED, and
Micro-LED are the only real-LED TVs.
Home Theater Projectors
An LCD projector consists of a bright UHE-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
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 UHE-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.
LCOS 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 LCOS
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.
The Laser Projector
Misused buzzwords can add confusion to any subject.
Laser is the current buzzword in home theater projection.
Let's clear the air with this description.
• Laser home theater projectors
are Laser-lit DLP, LCD, or LCOS projectors.
• The conventional projector
lamp is replaced with a laser or hybrid laser light.
The significance, they offer
brighter light, cooler operation, and longer life.
Three Lasers & 3 Chips
High-performance projectors engage three LED lasers;
• A separate red, green, and blue LED
focused on dedicated LCD, DLP, or LCOS chip. (3 chips),
each is combined, magnified, and routed to the projection
Single Laser, Hybrid
Laser LED, & 1 Chip
More affordable single-chip
projectors reduce the light source to a single laser or a
The Single Laser
Single laser models reduce the
number of lasers from three to one blue laser.
The single blue laser version
splits the light into two beams, with one beam filter-converted
into yellow and green light beams.
The three beams are combined/mixed
in a lens and prism assembly to produce white light.
The hybrid laser-led light source
combines a red led with a blue laser.
The blue laser splits with one path
blue, and the other is directed through phosphor to generate a
3rd green light path.
In both cases, single blue or
hybrid, the light is combined/mixed to create white light.
The corrected white light
passes through .....
color wheel and reflected by a DLP DMD chip.
passes through and reflected by an LCOS chip.
passes through an LCD chip.
....... And then magnified and
projected onto the screen.
A Word of Caution
You can find claims of a 3,600 LED lumen projector as twice
the brightness of a 1,500 ANSI lumen projector based on the
spec sheets. Many online or big-box types are unaware of
the difference between the lumen and ANSI lumen. 3,600
LED lumen converts to the neighborhood of 1,500 ANSI
Additional confusion -- many manufacture-spec sheets lack
standardized testing. Therefore manufacturer versus manufacturer
spec sheet comparison is suspect. Choose a
high-performance projector based on the Foot Lambert.