Projection Screen

Projection screens are installations consisting of blank surface and a support structure used for projecting an image for the view of an audience. Projection screens may be permanently installed as in a movie theater, painted on the wall, semi-permanent or mobile, as in a conference room or other non-dedicated viewing space.

Uniformly white or grey screens are used almost exclusively as to avoid any discoloration to the image, while the most desired brightness of the screen depends on a number of variables, such as the ambient light level and the luminous power of the image source.

Flat or curved screens may be used depending on the optics used to project the image and the desired geometrical accuracy of the image production, flat screens being the more common of the two. Screens can be further designed for front or back projection, the more common front projection systems having the image source situated on the same side of the screen as the audience.

Home theater projection screen displaying a high-definition television image.Different markets exist for screens targeted for use with digital projectors, movie projectors, overhead projectors and slide projectors, although the basic idea for each of them is very much the same: front projection screens work on diffusely reflecting the light projected on to them, whereas back projection screens work by diffusely transmitting the light through them.

Projector

A video projector takes a video signal and projects the corresponding image on a projection screen using a lens system. All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other inconsistencies through manual settings. Video projectors are widely used for conference room presentations, classroom training, and home theater applications.

Video projectors may also be built into cabinets which use a rear projection screen to form a single unified display device, now popular for "home theater" applications.

The cost of a device is not only determined by its resolution, but also by its brightness. While most modern projectors will provide sufficient brightness at night or under controlled lighting such as in a basement with no windows, a projector with a higher lumens rating is required for a room with a higher amount of ambient light. A rating of 1000 to 1500 ANSI lumens or lower is suitable for smaller rooms with controlled lighting or low ambient light. Between 1500 to 3000 ANSI is suitable for medium sized rooms with some ambient light or dimmed light. Over 3000 ANSI is appropriate for very large screens in a large room with no lighting control (for example, a conference room). Projected image size is also important, as the total amount of light does not change, as size increases, brightness decreases. An increase in a widescreen image from 80 inches diagonal to 100 inches diagonal reduces the image brightness by 35 percent.

LCD TV

LCD technology is based on the properties of polarized light. Two thin, polarized panels sandwich a thin liquid-crystal gel that is divided into individual pixels. An X/Y grid of wires allows each pixel in the array to be activated individually. When an LCD pixel darkens, it polarizes at 90 degrees to the sandwiching polarizing screens.

This cross-polarizing blocks light from passing through the LCD screen where that pixel has darkened. The pixel darkens in proportion to the voltage applied to it: For a bright detail, a low voltage is applied to the pixel; for a dark shadow area, a higher voltage is applied. LCDs aren’t completely opaque to light, however; some light will always penetrate even the blackest LCD pixels.

Liquid crystal display television (LCD TV) is a television using LCD technology for its visual output. This technology is generally TFT. It is contrasted to alternate visual output technologies, such as cathode ray (CRT) or plasma display (PDP TV).

Early LCD television had drawbacks relative to traditional visual display technologies. It displayed fast-moving action with "ghosting" and could be viewed best only looking straight at the screen or from a slight angle. These problems have largely been overcome in recent years, and LCD televisions, along with plasma displays, have taken over the dominant market position worldwide from cathode ray displays.

For a long time it was widely believed that LCD technology was suited only to smaller sized televisions, and could not compete with plasma technology at larger sizes. This belief has been undermined by the announcements of seventh-generation panels by companies such as Sharp Corp. Sony, Samsung, LG Philips and others.

Modern LCD TV sets are geographically universal because they have a multisystem tuner, to display PAL, NTSC and SECAM norms. And they include an electronic (step-down & step-up) transformer that automatically can use 110/250 V AC indifferently and universal grounded adapter plugs.

Risk

Space is an important issue when setting up a home theater. If you dot have a lot of room, a home theater in a box is just what you need. They are really compact and dont take up a lot of space, which is perfect for setting up a home theater in a room designated for something else, such as the family room.


These affordable home theater systems, however, do have some negative characteristics. Their quality is generally not up to par with the kinds of components one can purchase separately. Those who tend to be very sound conscious may be disappointed by all-in-one home theater systems.These systems also lack versatility.


They are designed for watching movies using the included DVD player. You can use them as stereos for DVDs in many cases, but they are not true stereo systems. They are generally very limited with respect to carrying additional inputs or outputs, too. They are, simply, limited systems.Al-in-one solutions also risk complete system shut down in the event of one problem. A single broken cable or one problem with the receiver can render the rest of the set virtually useless. One cannot simply replace on part of the system. It is generally an all or nothing proposition. The lack of flexibility can be frustrating for some.


If you necessitate a full-featured home entertainment system that can continue to grow with technology and your interests, these cheaper systems may be a bad investment.When deciding if an all-in-one solution can work, ones needs must be kept in mind. One must simply know what they want the end result of their home theater experience to be. For some, this will lead to an inexpensive purchase. For others, it will produce a need to buy more expensive and higher quality components. If you are looking for a very simple and inexpensive means of trying out the home theater experience in a limited space, however, all-in-one systems may be the perfect way of doing just that...