How does a backside projection tv work?
i will be giving out 10 points to the best answer
Answers: A rear projection box (or RPTV as it’s often set in the consumer electronics world) is a specific type of reverse projection display system the latter of which may be classified into two primary categories base on their principle of operation: transmissive and reflective. Reflective RP systems can be further subdivided into single-mirror and dual-mirror systems.
Purely transmissive rear projection systems are highly rare within residential applications. Most rear projection display systems, including RPTVs, that are designed for residential use, utilize a mirror structure which comprises constituent of a chassis often roofed by an outer cabinet.
A reflective display system consists of an internally mounted projector (or projection ‘engine,’ not unlike that of the typical front projector,) one or two mirrors (preferably of the first-surface variety,) a transmissive display blind (either optical diffusion or the much more common Fresnel-Lenticular type,) and some form of an outer crate. Projectors used in RPTVs function no different than projectors used surrounded by front projection applications (other than the image is reversed) and are available surrounded by any of the standard projection display technologies, such as CRT, LCD, LCoS, or DLP, near which you may already be familiar.
Though here are many variation when it comes to specifics on RPTV construction, in standard a video signal is input to an internal projector where the video portrait is produced and magnified by a set of lenses. From the projector the image is next focused onto a mirror assembly consisting of one or two mirrors, which in turn magnify and imitate the video image onto the support of a large transmissive display eyeshade fastened to the front of the RPTV’s chassis.
In addition to the project of image magnification the mirrors are also used to ‘fold the bedside light path’ thereby greatly reducing the overall depth of the enclosure. However, within the real world mirrors are not best reflectors though some mirrors are better than others. The best reflectivity that a person could expect within a high carrying out rear-projection display system is typically no more than 94% (and on very infrequent occasion 97%) per mirror; so respectively mirror that is used will effectively dull the efficiency of the overall optical subsystem. This is one nouns where a purely transmissive system have the advantage over a reflective system.
Among diverse factors, including the want to counter multiple and/or lower quality mirrors, as economically as lower powered projectors, manufacturers of RPTV systems will invariably resort to the use of Fresnel-Lenticular blind technology to optically boost the light output of the their RPTVs. A Fresnel-Lenticular eyeshade has several undesirable characteristics when compared to a part optical diffusion screen but is repeatedly necessary when using an RPTV contained by a viewing environment where a soaring quantity of ambient night light may be present.
To get a better impression of what I’ve described above please have a look at the following documents and pictures.
http://electronics.howstuffworks.com/pro...
http://www.da-lite.com/education/angles_...
http://www.da-lite.com/education/angles_...
http://www.da-lite.com/products/product....
http://www.draperinc.com/images/RearScre...
http://www.draperinc.com/images/RearScre...
http://www.draperinc.com/images/RearScre...
http://www.draperinc.com/images/RearScre...
http://www.draperinc.com/images/2007Cata...
http://www.stewartfilmscreen.com/mirrorp...
http://www.stewartfilmscreen.com/spec_sh...
http://www.stewartfilmscreen.com/spec_sh...
http://www.stewartfilm.com.cn/001/busine...
Modern DLP and LCD rear-projectors work amazingly similar to the movie theater projectors. A light-bulb shines onto a color wheel or LCD panel that contain the actual movie. The light is reflect onto the back of a plastic peak and you watch from the front.
However: the old-style "Big Screen" television work a bit different. They have 3 CRT tubes (like a frail TV tube), but each of these tubes are steadfast to a different color. The 3 tubes (called "Guns") focus onto a mirror that then reflect the image onto the hindmost of a plastic screen.
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