A large-screen TV set that uses one of several technologies for generating the image. All methods yield larger screens than the one-tube, direct view CRT TV, which reached a practical limit around 36". The depth of rear screen sets is reasonably shallow because the image is projected through a series of lenses and mirrors that turn it toward the screen at the very end.
They Started with CRTs
The first rear projection sets used three CRT guns to generate red, green and blue light. Newer technologies use tiny microdisplay panels no more than an inch square, which result in even shallower sets, although not as thin as plasma or LCD displays.
A Lot of TV for the Money
Rear-projection systems have traditionally suffered from a narrower viewing angle than other displays including CRTs and flat panels. Because the viewing screen itself is a lens, standing up or moving off to the side changes the brightness of the image for the viewer. However, newer sets have wider viewing angles, and although not as visually dazzling as plasma TVs, rear-projection sets offer a competitive alternative at a far more affordable price.
Rear Vs. Front Projection
Although rear-projection TVs have screens as large as six feet (diagonal measurement), front-projection TVs can project a much larger image onto an external screen, and the image size can be changed by replacing the screen and/or repositioning the unit (see front-projection TV). See microdisplay, plasma, LCD and video/TV history.
Rear Screen Vs. Front Screen
Rear-projection systems are self contained, whereas front-projection systems use a separate screen several feet from the unit.
CRT-Based (The Original)
The first rear-projection technologies used three CRT guns to create red, green and blue images, which were mixed together. In order to generate sufficient light, the tubes were large, but the depth of 50" units was still only about two feet. Since CRT-based units use traditional phosphor tubes, they easily provide variable resolutions, whereas newer microdisplay-based use a fixed pixel matrix just like plasma and LCD displays. However, the microdisplay-based units use tiny imaging panels and fit into much narrower cases.
LCD-Based Microdisplay (MicroLCD)
Light is beamed through three tiny LCD "microdisplay" panels (one red, one green, one blue) that are approximately 1.5" diagonal. Each microdisplay is modulated with the pixel pattern for that particular color. The image is enlarged to the size of the screen by a set of lenses.
DLP and LCoS Microdisplays
DLP (Digital Light Processing) and LCoS (Liquid Crystal over Silicon) systems reflect light from tiny panels. DLP rotates pixel-sized mirrors to reflect light. LCoS uses LCD microdisplay panels similar to the LCD-based units mentioned above, except after passing through the microdisplays, the light is reflected from a mirror to the lenses. To generate color, DLP units either use a single chip and color wheel or three chips, each with its own set of mirrors and color filter. LCoS units use three LCoS panels. For more details, see DLP and LCoS.
Which Is Better?
Visual display technologies are rather subjective. To your eye, one type may look superior to another. The only way to know is to play your favorite types of movies on as many different TVs as you can. Otherwise, all the specifications in the world are meaningless.
They Started with CRTs
The first rear projection sets used three CRT guns to generate red, green and blue light. Newer technologies use tiny microdisplay panels no more than an inch square, which result in even shallower sets, although not as thin as plasma or LCD displays.
A Lot of TV for the Money
Rear-projection systems have traditionally suffered from a narrower viewing angle than other displays including CRTs and flat panels. Because the viewing screen itself is a lens, standing up or moving off to the side changes the brightness of the image for the viewer. However, newer sets have wider viewing angles, and although not as visually dazzling as plasma TVs, rear-projection sets offer a competitive alternative at a far more affordable price.
Rear Vs. Front Projection
Although rear-projection TVs have screens as large as six feet (diagonal measurement), front-projection TVs can project a much larger image onto an external screen, and the image size can be changed by replacing the screen and/or repositioning the unit (see front-projection TV). See microdisplay, plasma, LCD and video/TV history.
Rear Screen Vs. Front Screen
Rear-projection systems are self contained, whereas front-projection systems use a separate screen several feet from the unit.
CRT-Based (The Original)
The first rear-projection technologies used three CRT guns to create red, green and blue images, which were mixed together. In order to generate sufficient light, the tubes were large, but the depth of 50" units was still only about two feet. Since CRT-based units use traditional phosphor tubes, they easily provide variable resolutions, whereas newer microdisplay-based use a fixed pixel matrix just like plasma and LCD displays. However, the microdisplay-based units use tiny imaging panels and fit into much narrower cases.
LCD-Based Microdisplay (MicroLCD)
Light is beamed through three tiny LCD "microdisplay" panels (one red, one green, one blue) that are approximately 1.5" diagonal. Each microdisplay is modulated with the pixel pattern for that particular color. The image is enlarged to the size of the screen by a set of lenses.
DLP and LCoS Microdisplays
DLP (Digital Light Processing) and LCoS (Liquid Crystal over Silicon) systems reflect light from tiny panels. DLP rotates pixel-sized mirrors to reflect light. LCoS uses LCD microdisplay panels similar to the LCD-based units mentioned above, except after passing through the microdisplays, the light is reflected from a mirror to the lenses. To generate color, DLP units either use a single chip and color wheel or three chips, each with its own set of mirrors and color filter. LCoS units use three LCoS panels. For more details, see DLP and LCoS.
Which Is Better?
Visual display technologies are rather subjective. To your eye, one type may look superior to another. The only way to know is to play your favorite types of movies on as many different TVs as you can. Otherwise, all the specifications in the world are meaningless.
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2008 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- Photos: Top 10 reviews of the week
- Here are CNET Reviews' 10 favorite items from the past week, including the Pantech flip phone, Sony Bravia LCD TV, Acer Aspire laptop, and Canon PowerShot ultracompact. by CNET News.com
- Image galleries 2008-10-11
- Tickerz 3 (exe)
- Revolbyte Tickerz is a multimedia client which allows you to enjoy TV and radio channels via Internet. You don't need any additional TV-Card in your PC order notebook. You just need an ordinary Internet connection. With Tickerz you have access to thousands of radio- and TV-streams from all over the...
- Software downloads 2008-10-09
- Have we all become a bunch of anxious, depressed, sleep-deprived irritable stress-heads?
- Have we all become a bunch of anxious, depressed, sleep-deprived irritable stress-heads?To answer your question, yes.I'd write more, but I'm too busy.ChrisBusy IT LifestyleIt's true - the IT world is very hectic and requires lots of work as well as time to research and respond to messages in many forms....
- Discussion threads 2008-10-08
- Have we all become a bunch of anxious, depressed, sleep-deprived irritable stress-heads?
- Let's face it, the last month or so has been a challenge for just about anyone's tolerance of stress and has made even the most "stable" of us question our own emotional and mental health. But I've discovered that IT workers in particular, or anyone who...
- Blog posts 2008-10-08
- Poker sites fight to get domain names back from Kentucky
- This is a novel legal strategy. And so far it's working. Last month, in an effort to preserve the state's monopoly on legal gambling, Kentucky Gov. Steve Beshear sued to have 141 online gambling sites' domains transferred to the state's control. According to the Washington Post, a big...
- Blog posts 2008-10-08
- YouTube teams with iTunes, Amazon to offer e-commerce feature
- It's Business 101: Don't wait for your customers to come to you. Go to the places where they are. That's why you've seen the launches of music streaming services within MySpace and Google's AdSense program extended into Web-based video games. Now, YouTube has partnered with Amazon and...
- Blog posts 2008-10-08
- Core i7 sensitive to RAM voltages over 1.65V
- Core i7 sensitive to RAM voltages over 1.65VOf course people will!People will do it anyway thinking it won't happen to them...because we all know that these things happen only to others. And when the CPU makes a funny smell and suddenly the computer is like a big powerless door...
- Discussion threads 2008-10-08
- Google extends AdSense into video games
- Google has injected some legitimacy into the Web-based video game market, announcing a beta launch of AdSense for games. Techmeme In-game advertising isn't new. Many of the more popular games for the big console players have had ads embedded in them for a while. And the feedback...
- Blog posts 2008-10-08
- $236m judgment against spammer couple
- $236m judgment against spammer coupleSadly, it's pointlessSadly, in reality such a judgment is pointless.Let them pay it in jail time$236m is a fair bill to run up. I say let them paying it back in jail time.Let's even be generous and say 1 day in jail will reduce the bill...
- Discussion threads 2008-10-08
- Student indicted for Palin e-mail hack
- Student indicted for Palin e-mail hackno luck for youseems your daddy wont be able bail you out of this one. Just remember to bring plenty of vaseline with you in prisonoh boy, is this kid in the crapperThis little jerky-boy is headed for a really miserable experience. Having a...
- Discussion threads 2008-10-08
- C'mon, Vista really isn't that bad
- C'mon, Vista really isn't that badRE: C'mon, Vista really isn't that badI agree, it eases the transition from the digital to the physical world for computer users and seems especially geared towards newer computer users and explaining steps and giving more information about the system itself and any software installed....
- Discussion threads 2008-10-08
- Image Gallery: HAVA Platinum HD
- The HAVA Platinum HD lets you connect your HD source to the device and then watch your HD content on your PC, Windows Mobile device, S60 device, or Nokia Internet Tablet. You can even control your TV source just as if you were there in front of your TV/HD source....
- Image galleries 2008-10-08
- News to know: Clickjacking redux; SAP pricing; BlackBerry Storm; Windows 7
- Here are today's notable headlines. You can get News To Know via email alert and RSS daily: Ryan Naraine: Webcam hijack demo highlights clickjacking threat Dancho Danchev: Atrivo/Intercage's disconnection briefly disrupts spam levels Adobe posts workaround for clickjacking flaw, NoScript releases ClearClick ...
- Blog posts 2008-10-08
- Google is NOT your friend
- Google is NOT your friendthe old call the enemy of my enemy is my best friendas long as google will pick on MS im willing to live with it happily .... when MS will be out of the picture will trun to the next monsterRE: Google is NOT your friendSure,...
- Discussion threads 2008-10-07
- Watching you watch the debate
- Tonight, as you watch the second presidential debate, Google will be watching you to see what you're searching for. It's just another peek into the minds of voters to find out which issues matter most or which are most confusing or unclear. Take, for example, the results...
- Blog posts 2008-10-07
- Trying to increase productivity? Send your employees home.
- Companies that give their workers the option of telecommuting are seeing greater productivity, lower costs, improved employee health and greater employee retention, according to a survey released today by the Computing Technology Industry Association. Case in point: I'm typing this from this from my own home office...
- Blog posts 2008-10-07
- Ask revamps for faster Web search, more relevance
- Ask.com is overhauling its Web search engine to deliver faster results and improved relevance as it bids to win share from market leader Google. NEW YORK--IAC Corp's Ask.com is overhauling its Web search engine to deliver faster results and improved relevance as it bids to win share from market...
- News items 2008-10-07
- Asset smart? AMD moves manufacturing off its balance sheet; Bolsters capital
- AMD said Tuesday that it will split off its manufacturing operations in a deal with the Advanced Technology Investment Company of Abu Dhabi. AMD will also receive a capital infusion from Mubadala Development Company, which will wind up owning more than 19 percent of Intel's smaller rival. ...
- Blog posts 2008-10-07
- Review: HAVA Platinum HD lets you watch TV on your Nokia Internet Tablet, S60 or WM device
- I've been using a Slingbox since they were first launched a few years ago and have used all of the mobile clients to watch my TV content on the road. I still have my Slingbox Classic and use it on my S60 and Windows Mobile devices from time to time....
- Blog posts 2008-10-07
- News to know: AMD; iPhone security; Linux; SAP
- Here are today's notable headlines. You can get News To Know via email alert and RSS daily: Sam Diaz: AMD to spin off manufacturing. Techmeme Heather Clancy: The color that shall not be named. AMD's Vertal downplays green credentials, plays up efficiency arguments ...
- Blog posts 2008-10-07
Neighboring Terms
Premier Vendor Content Whitepapers, webcasts & resources from our Power Center Sponsors
- Printers
- 'Green' Font Cuts Costs and Saves Trees (BNET)
- Three Ways to Save Paper (BNET)
- CNET Reviews printer buying guide (CNET)
- View all printers-tagged content on ZDNet
- Plan B from Brother
- It's the smarter way to work in color Our professional color ink-jet all-in-ones give you more choices, more features, and more value. Make the Smarter Choice. Learn More »
