In 2003 I had decided it was time to set up a high definition, large screen
home theatre system. As I looked around at Christmas time, I
realized I needed to learn a lot more about it in order to make a
decision I could live with.
I resisted the
Christmas specials, thinking 2004 would probably be a better  year to get into this arena, since it
continued to
become more competitive with newer technologies like LCoS and DLP
becoming more affordable - especially since chip maker Intel and
other companies such as Toshiba, Canon and Sony were entering the LCoS fray (note that Intel has since abandoned LCOS
production). Most units also had standard computer connections, so I
thought this
could make for an interesting alternative use as a monitor, particularly
with the upcoming very high resolution LCoS displays.
So I decided to persevere and get it figured out, and I started by spending
part of my Christmas shopping time looking into the various offerings. I
have been in the electronics field for over 35 years, so I have some
insight into these technologies - and I will try my best to demystify
some of the gobbledygook terminology. This series of articles will cover what I've
learned, and what I ended up purchasing. I hope it will help you make
your decision, if you are headed in the same direction.
In this series of articles, I will attempt to categorize and explain the differences between
the various technologies. At this time, HDTV large screen
systems can be broken down into four basic categories:
-Conventional 'picture tube' (CRT)
-Solid state direct display (LCD, Plasma, SED)
-Transmissive Projection (LCD, CRT)
-Reflective Projection (LCoS, DLP)
Notes: Transmissive Projection refers to a method of beaming light
through a light controlling element such as an LCD, whereas Reflective Projection refers to technologies
that bounce light off the surface of a light controlling element, such
as the Texas Instruments 'Micro-Mirror' chip (DLP) or a liquid crystal
reflector mounted on silicon (LCoS), such as the Sony SXRD chip.
CRT
projection, although included in the Transmissive category, uses the
actual CRT as the light source, transmitted through a lens/mirror system.
LCD, CRT, LCoS and DLP can be either front (i.e. projector and drop down screen) or
rear projection (all components contained in a housing). Rear projection
(RPTV) generally provides better resolution as the picture generating element
is closer to the screen, but the advantage of front projection is that
it is much more portable and can cover an entire wall (good for
presentation work, but more people are also using it for home theatre).
For the sake of clarity, here are some acronym and terminology definitions relating to
the various display technologies, used in the other table below to compare the
various screen types:
| TERM |
DEFINITION |
| TLA |
Three Letter
Acronym |
| HDTV |
High Definition
Television. The highest quality video picture
available in Digital TV. In the U.S., the 1080i and 720p
resolution formats in a 16:9 aspect ratio are the two acceptable
HDTV formats. Regular NTSC analog TV is 480i. |
| HTPC |
Home Theater
Personal Computer. The use of a PC as a processing
and source control platform for a home theater system. |
| RPTV |
Rear Projection
TV. The type of home theater screen system where the image
is projected onto the back of the screen. Can be DLP, LCD, CRT
projection technology. |
| Lumens |
An ANSI Lumen is
a measurement of light radiation or brightness. A 3,000 Lumen
projector creates a brighter picture than a 2,000 Lumen unit. The ANSI
prefix is a standards designation (American National
Standards Institute). |
| Nits |
Plasma and LCD
manufacturers use this term to define the brightness of their
screens. Another term for Nits is Candelas per square meter (Cd/m2).
One nit = 0.2919 foot-lambert. Nits includes an area definition,
unlike lumens, so you can't simply divide by Watts to establish a
Nits/watt spec. |
| 480i 720p
1080p |
resolution
measurement in lines, p for "progressive
scan", i for "interlaced scan".
Conventional TV (e.g. 480i) is interlaced whereby the screen is
scanned twice by alternate lines that are interleaved
(interlaced), whereas HDTV (e.g. 720p) can scan all lines
sequentially (consecutively or progressively). |
| DVI HDCP |
Digital Visual
Interface technology with High-bandwidth Digital
Content Protection. Developed by Intel Corporation,
HDCP is a specification to protect digital entertainment content
through the DVI interface. The HDCP specification provides a
transparent method for transmitting and receiving digital
entertainment content to DVI-compliant digital displays. Some
products, such as set-top boxes and DVD burners will require this
connector. Even if you have a HDTV set-top box, if it lacks the
DVI, your signal may be degraded. |
| HDMI |
High Definition
Multimedia Interface. Like DVI, HDMI is another
digital interface, and from what we saw at CES 2005, it may become
the universal standard. Developed by Sony, Hitachi, Thomson (RCA),
Philips, Matsushita (Panasonic), Toshiba and Silicon Image, the
High-Definition Multimedia Interface (HDMI) has emerged as the
connection standard for HDTV and the consumer electronics market.
HDMI is the first digital interface to combine uncompressed
high-definition video, multi-channel audio and intelligent format
and command data in a single digital interface. |
| SACD |
Super Audio
CD uses a new recording technology called Direct Stream
Digital. DSD records a one bit digital signal at a
sample rate of 2.8 million times per second, 64 times higher than
conventional CD's.
|
| NTSC |
Existing color
TV standard developed in the U.S. in 1953 by the National Television
System Committee. NTSC vertical line resolution is
525 lines/frame and the vertical frequency is 60Hz. The NTSC frame
rate is 29.97 frames/sec.
|
| CRT |
Cathode Ray
Tube - venerable old style picture tube |
| PDP |
Plasma Display
Panel, plasma is a physics term for an electrically charged
gas |
| LCD |
Liquid Crystal
Display, same as laptop screens |
| TFT |
Thin Film
Technology, a type of LCD |
| DLP |
Digital Light
Processor, a reflective light switch chip developed by TI.
Has a very fast response time - no motion lag |
| TI |
Texas Instruments
Corp., original manufacturer of DMD's and DLP's |
| DMD |
Digital Micro-mirror
Device - chip for DLP technology by TI |
| DNIe |
Digital Natural
Image enhancement - chip for optimizing video
picture quality, by Samsung (used in their DLP units) |
| LCoS |
Liquid Crystal
on Silicon, reflective light switch |
| SXRD
projection |
Silicon X-tal Reflective Display:
Sony's incarnation of LCoS technology. Sharp picture, no pixelation, very high resolution, reflective
system won't burn out picture element, "no moving parts"
design usually incorporates 3 imaging chips for primary colors,
instead of color wheel. |
| SED |
Surface conduction
Electron emitter Display by Toshiba/Canon |
| FED |
Field Emission
Display: New technology from Sony |
| OLED |
Organic Light
Emitting Diode display: new technology from Seiko-Epson |
| D-iLA |
Direct
Drive Image Light Amplifier, LCoS chip
developed by JVC |
| QXGA |
high screen
resolution of 2048 x 1536, attained by D-iLA chip |
| DCDi |
Directional
Correlation Deinterlacing (a de-interlacing
method to eliminate jagged edges (jaggies) along diagonal lines
caused by interpolation, developed by Faroudja corp. An
important feature to look for, this Emmy® award
winning technology was once only available in products costing
$20,000 or more, and is now available in numerous products costing
well below $2,000 |
| aspect ratio |
ratio of screen
width to height. An aspect ratio of 4:3 is conventional TV and
16:9 is HDTV (and film) |
| 3-2 pulldown |
a method of
film-to-video conversion |
| twitter and
judder |
terms describing
film conversion related artifacts |
| anamorphic
lens |
a special lens
that compresses the pixels of a 4:3 screen into a 16:9 format, and
allows a projector to use the full brightness of the display,
without black bars above and below the image. Must normally be
removed for regular 4:3 viewing. |
| SDE |
Screen Door
Effect is a term used to refer to the visible pixel
structure on a screen. |
| YADR! |
Yet Another
Dang Remote! A common exclamation heard from people
who just bought their third or fourth home audio/video component.
And then there are further unmentionable expletives when you find
out a component isn't supported, or it's just too complicated to
program everything in?? Maybe it's time to read about our experience in the remote
control review article. |
The following table provides a quick comparison of the display types;
"pixelation" refers to the ability to see individual picture elements
(pixels) at normal viewing distances (note that all the types below can
contribute to the YADR index). Please note that these products are being
constantly improved and not all manufacturer's models may be subject to
the disadvantages listed below:
| DISPLAY
TYPE |
PRO
- ADVANTAGE |
CON
- DISADVANTAGE |
CRT
conventional
picture tube |
Cathode Ray
Tube: very
sharp and bright, high contrast ratio, good picture view from
side, low cost, handles regular analog NTSC channels well, no
moving parts |
heavy
and bulky, limited in size to about 36", picture can fade |
CRT
projection
|
low
cost, large screens possible, no moving parts |
heavy
and bulky, limited viewing angles, visible raster lines, mis-convergence
can be a problem, picture can fade over time |
| LCD flat
screen panel |
Liquid Crystal
Display: bright,
sharp picture, light and compact, can hang on wall, solid state,
no moving parts |
picture can fade over time |
| LCD
projection |
fairly
bright, large screens possible, sharp picture, no moving parts |
display can fade due to heat damage to
organic compounds that some manufacturers use in the LCD,
projector bulb can fail |
| PDP Plasma
flat screen panel |
Plasma Display
Panel: bright
picture, light and compact, can hang on wall, wide viewing angle,
no moving parts, handles fast motion really well |
expensive,
some pixelation, display can burn out. |
| DLP
projection |
Digital Light
Processor: bright,
sharp picture, high contrast, no pixelation, reflective
system won't burn out picture element, very fast response time -
no motion lag. |
possible visual "rainbow" artifacts on single chip versions
caused by spinning color wheel, projector
bulb can fail |
| LCoS
projection |
Liquid Crystal
on Silicon: bright,
sharp picture, no pixelation, very high resolution, reflective
system won't burn out picture element, "no moving parts"
design usually incorporates 3 imaging chips for primary colors,
instead of color wheel. |
projector bulb can
fail |
| SXRD
projection |
Silicon X-tal Reflective Display:
Sony's incarnation of LCoS technology. Sharp picture, no pixelation, very high resolution, reflective
system won't burn out picture element, "no moving parts"
design usually incorporates 3 imaging chips for primary colors,
instead of color wheel. |
projector bulb can
fail |
| SED
panel display |
Surface conduction Electron emitter Display:
very bright
picture, very high resolution, can hang on wall, very high
contrast ratio, can be viewed from any angle,
no moving parts, handles fast motion really well |
expensive at
first, not available yet |
| FED
panel display |
Field Emission
Display: New technology from Sony, properties are similar
to SED |
expensive at
first, not available yet |
| OLED
panel display |
Organic Light
Emitting Diode display: new technology from Seiko-Epson |
expensive at
first, not available yet |
I bought and installed the Sony STR-DE995 Dolby digital 7.1
surround sound receiver. With 7 speakers - front, center, side and rear -
and a sub-woofer for bass, it certainly brings DVD viewing to a new level
of realism. We watched LOTR II for the second time with the new system -
it was awesome. At 110 watts per channel, that's a total output of nearly
900
watts RMS, quite enough to shake the foundation of our home every time
Treebeard takes a step ...
I have a venerable 10 year old Toshiba 27" TV that still has an
excellent picture. I haven't upgraded to a large screen because I haven't
seen all the new stuff yet, but I'll be making this decision soon enough.
I'm going to Houston where I hope to see some of the latest; at this point, my
money is on DLP or LCoS, from what I've seen so far, although LCD and Plasma flat panels
are getting much better too. Watch for LCoS systems coming up with
cinematic on-screen contrast ratios as high as 2500:1 and progressive
scan resolutions
as high as 2048 x 1536 pixels.
NB Author's Note April 24/04: I've made my screen choice; the fourth article explains the reasons behind my
decision to buy the BenQ
PB6200 DLP front projector.
This article series will be developed and updated as new information comes in,
so bookmark this site and stay tuned! We'll be reporting on the newer DLP,
LCoS, SED and SXRD systems soon.
The major show event in this field is the CES 2007 (Consumer Electronics Show)
trade show in Las Vegas, next January. We'll be reporting on
this as soon as it is over.
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