Home Theater Projectors - Information on : CRT - LCD
- DLP - Screens - HDTV
1. CRT. (Cathode Ray Tube) Unlike your home TV that has 1 tube with all of its
colors being produced internally a CRT Projector has three tubes a Red, Green
and Blue. When the three tubes are converged and focused onto a screen we
can achieve a vivid and bright picture with great resolution especially when
used with Laser disc or DVD. The main advantages of CRT projectors are their
Video performance, Picture quality, Ceiling and floor mounting and capability to
connect into various output devices. These units can handle harsh install
environments and are ideal for installation within the pub and leisure industries,
as well as being a popular choice for Home Cinema installation.
2. LCD. (Liquid Crystal Display) a newer technology that offers many forms of
imaging capabilities, which during the last decade has also been used for
projection. Just like a CRT projector that has three tubes a LCD projector has
three LCD panels and a lamp. The light is separated into Red, Green and Blue
and passed through the dedicated LCD panel representing that color. The
modulated light sources that have passed through the LCD panel are merged
and projected through a lens that offers zoom and focus. The main advantages
of LCD projectors is the amount of light output from these devices, their graphic
image capabilities, a zoom lens for correct projector positioning, light-weight
portability, and a large product range to suit individual requirements. These
projectors are ideal for professional presentations and conference meetings.
3. DLP. (Digital Light Projector) is the most recent projector technology on the
market and was invented by Texas Instruments. This projector technology is
not that dissimilar to that of LCD projectors where you have an image device
and a light source. The basic difference here is the image device (the Texas
Digital mirror). This image device is heavy populated with tiny mirrors that are
mounted onto springs so individual mirrors can be tilted either to reflect or
displace the light back down to a lens. There is only one image device * (1 chip
DLP) so the light is separated into the three colors by a spinning wheel and
synchronized to the modulation sent to the tiny mirrors. The main advantages
of DLP projectors are the good Video and Data resolution with high light
output and various versions of projector for different application.
* Texas also make 3 chip DLP but this is usually only used for the high end
application
Video Only Capable of connecting to a video source (e.g. VCR). Some
projectors are multi-standard so they can be used in other countries and also
have a built in speaker so sound can be produced.
Multimedia Have
the best input specification that offers video, PC/MAC and
maybe new digital inputs. For example, imagine you have 1 composite input, 1
SVHS input, a PC input at SVGA and a MAC computer, it can be possible,
depending on the specification of the projector, to connect all of the above and
switch between the inputs via a remote control.
Data & Graphics Can display an image that has been generated on a PC/MAC.
These images can range from low resolution VGA up to very high resolution
VXGA. You need to check the output Data Source to confirm the minimum
requirements for the projector to show.
Signal Types
There have been many advancements in Computer and Video output signals
that has lead to the products being compatible to these inputs.
Composite output
refers to a signal that has the luminance, chrominance
and sync information combined into one cable.
SVHS output refers
to a signal that has the luminance and chrominance
separated into two outputs. This improves the signal quality.
RGB output refers
to a signal that has been separated into the red, green
and blue components. The sync signal is either applies to the green
output or sent individually or separated in vertical and horizontal sync.
Digital outputs are
the newest signal type that comes into different
characteristics altogether. There are advantages in using the digital
output of your source machine but you need to check for compatibility
between two units.
Home Theater
The Image- Screens
Complementary with the sound, the visual image in home theater is designed to capture the
audience.
The screen must utilize the audience’s peripheral
vision by offering a picture larger than life. Most home theaters project the film onto a
six to ten foot diagonal screen to provide the greatest impact.
Screens are designed in three types: curved fixed, for rooms with ambient light; flat
retractable and flat fixed, both of which require darkened viewing rooms. Lighting and
room
size help to determine the best choice.
Projectors can be stationed behind the screen, on or in the ceiling, or on the floor
encased in furniture, like in a coffee table. Depending on the size of the room, the
distance between the screen and the projector can be anywhere from seven to
fourteen feet.
HDTV
The latest in visual technology is high definition
television (HDTV) which brings the
home theater audience closer to actually being in the picture. Did you ever notice the
black bands across the top and bottom of your home screen while watching a film, or
feel you were missing part of the picture on the left and right sides of the screen? The
reason for this is that films were made to project on theater screens that are different
dimensions than home screens. HDTV screens, while not exactly the same, more
closely resemble the dimensions of theater screens. In addition, there are twice as many
scanning lines in HDTV (the lines you see when you put your face right up to the screen)
that help to provide a sharper image. This sharper effect also can be achieved with a
high resolution line doubler or scaler.
The Home Theater
Home theater is an environment created by sound, picture, and comfortable surroundings
(no more stiff necks and sticky floors!). This is best achieved when the interior designer
works in partnership with the home theater engineers. Thus, the ideal time to consider a
home theater is while a home is being designed by architect or at least with the
knowledge that an existing room may need to be re-designed to create the home theater
ambiance.
It is important to educate interior designers about home theater so they understand they
are helping to re-create the ideal motion picture viewing environment--not just
designing furniture for existing audio and video components. It’s actually a
wonderful
challenge for designers to create the appropriate atmosphere.
Part of that challenge is to balance hard and soft surfaces in the room to cut
reverberation
and compensate for dead spots. Lighting is key since the room must be able to go
completely dark. Seating must be centered and focused toward the screen for the largest
number of people that ordinarily would fit comfortably in the room. The goal is to
create a large, theater sized ambience in a much smaller space.
More Information can be found at:
The LucasFilm Ltd THX site
Dolby Labs site
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HT-200 & HT - 250
