Compare HDTV Home Theatre: LCoS vs DLP LED, LCD, Plasma - technology review & definition of terms

home theatre: LCoS vs DLP, LCD, Plasma - technology review
LCoS, LCD, DLP, plasma review by Adrian Biffen, Software For Homes Home theater on a budget
'Understanding HDTV - a comparison' 

by Adrian Biffen
Systems Administrator 
AeroHOST Web Systems
Jan 1, 2004 (updated through 2006)
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HDTV home theater - did I want it? Yes, but after preparing to compare the offerings, I soon learned that I may have to get an engineering degree in order to understand it! You've got your LCoS, DLP, SXRD, SED, LED, Plasma, LCD & CRT projection, just to mention some of the major technologies, in a dizzying array of enclosures and configurations, with Dolby Digital EX, Pro Logic, Neo6 DTS and THX surround sound systems to contend with as well. 

I ended up purchasing the BenQ PB 6200 projector; you can read about my experience in the articles that follow, and how it is integrated with our smart home (for complementary home automation products such as lighting control and motorized blinds and shades, see our home automation DIY kit article).

Visiting your local video store doesn't necessarily provide any help either. I recently had a store salesman show me the difference (supposedly) between a cheap S video cable and an expensive one, looking at a split screen display of the same video source for a side by side comparison on the same screen. The difference was night and day, but after examining the setup carefully, I realized he was actually showing me the difference between a cheap cable on a composite video connection vs an expensive cable on an electronically superior S video connection. Not at all a fair comparison of cables, but a good demonstration of S video vs composite video ... caveat emptor!

This is the first of a series of articles (see article summary table below) designed to help you get through the complicated process of setting up a home theatre system. There are articles covering relevant announcements from the January CES show in Las Vegas, and reasons behind my decision to buy the BenQ PB6200 DLP front projector (the fifth article describes the projector setup process).

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 LCoS, DLP, LCD, plasma review 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.

This series of articles is designed to help you get through the complicated process of choosing and setting up an HDTV home theater system. It is part of our overall website, which is about the X10 home automation system that uses the A/C wiring in your home - you don't need to run any wires.
Article# Topic
1 HDTV Definitions and terminology used in home theatre systems
2 HDTV news from Jan 2005 Las Vegas CES show
3 HDTV remote control consolidation issues
4 DLP projector decision: My reasons for purchasing
5 BenQ DLP 6200 review -projector setup process
6 HTPC: using home theater PC for DVD display
7 DVD software player review: watch DVD on your PC
8 Upsampling DVD player vs HTPC - comparison with Zenith DVB 318
9 Sony HDRHC1 Handycam review: widescreen high definition 1080i camcorder
10 Wireless video sender solves the 'extra tv' problem
11 SED Toshiba-Canon HDTV display review - the flat panel HDTV race heats up!
12 Canon SX 50 Realis LCoS projector review - first 3 chip LCoS projector under $5,000
13 Optoma H78DC3 'DarkChip3' DLP projector review - first 'Dark Chip3' DLP projector under $4,000
14 Xbox 360 review: best buy for game play online? - Windows Media Center Extender
15 Play Station 3 vs Xbox 360 - Sony and Microsoft Compete for gaming market
16 SXRD vs SED vs DLP - Sony raises the HDTV bar with Qualia and Grand Wega series
17 LED DLP light engine from Samsung vs SXRD, SED - 1080p resolution arrives
18 HD DVD vs Blu-ray: We review the new Toshiba HD DVD players (HD-XA1 and HD-A1)
19 H.264 AVC: High Definition advanced codec for movie downloads and HDTV Online

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:


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:

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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