 |
|
 |
 |
|
|
|
|
|
The
Technologies Theatre Accessories
CRT Advantages:
Brightness and clarity
Excellent color and contrast potential
Price value
High life expectancy
CRT Disadvantages:
Heavy weight limits size
Deep footprint
Analog or D/A connection
Screen burn-in potential
|
|
|
|
|
|
|
|
Direct View (CRT)
In past years,
most 35" or smaller TVs had a picture tube called a "cathode
ray tube" (CRT). Because you would actually watch the picture on
the glass of the "tube" they are called Direct View TVs as distinguished
from sets whose image is projected onto another surface.
Historically they operated using a 50-year old standard called
NTSC or what is now called "Standard Definition"
(analog).
There are still many excellent analog sets in use today and in
fact, most of the programming we now watch is in this Standard
Definition NTSC broadcast standard. Direct view on a CRT can still
give excellent picture quality with the contrast and colour
capability closest to the truest rendition possible. HDTV sets
have been built as CRT Direct View sets; however, size is limited
as the extreme pressures of a large glass tube under vacuum
require a very heavy glass tube. Small sets (30" and smaller)
represent great value as the picture quality is very high and
price is low. As the price of flat screens is coming down
rapidly, the CRT sets larger than 30" are now becoming rare,
despite the superior image.
The images on this large vacuum tube are produced as an electron
beam paints the picture on the inside face of the screen by
sweeping this phosphorescent coated screen horizontally and
exciting the colour phosphors. 480 image lines are swept with the
phosphors giving off light depending on the electron beam strength
at the moment it contacts the phosphor. See 480i
(interlaced).
The basic factors affecting resolution are: 1) dot pitch, 2)
electron beam size, and 3) bandwidth of the video amplifier.
The dot pitch is the diagonal spacing between like colour
phosphors. Typically it is 0.8 - 0.9 mm compared to a
computer monitor which has a dot pitch in the range of 0.15 mm to 0.30 mm.
The larger dot pitch for a CRT TV allows a brighter picture to
offset the ambient light in a room lit in daylight. Commonly, CRT
TVs have video amplifiers with a 20MHz bandwidth with higher- end
sets exceeding 30MHz.
Rear Projection TV (RPTV)
To overcome the size limitation of the CRT direct-view set, a method was
devised using mirrors to project the image on the back of a large screen.
Mounted in a cabinet, three
CRT tubes (separate red, blue and green) would be used to in
effect create a small movie theatre screen in a box. Price is the
major advantage of the CRT based RPTV, as it is relatively
inexpensive; however, micro-display and flat screen technologies
are displacing CRT in the marketplace.
One of the difficulties of this type of CRT set has been the need to
periodically realign the 3 colour "guns" and calibrate
the colour, black level and contrast settings. If you are a
stickler for quality, you'll likely want to have this calibration
done professionally by an ISF certified technician.
The newer players in the RPTV game are called
micro-displays. Micro-displays are lighter, shorter, and thinner than CRT-based rear-projection
RPTVs. They are called micro-displays because they consist essentially of a lamp that
passes light through or bounces it off a tiny pixel-filled microchip and onto a
large viewable screen. Today, many of these DLP, LCD or LCoS sets can display computer as well as high-def and standard TV and usually
display the best image when connected digitally (DVI, HDMI, or
FireWire) rather than via analog wires. Unlike rear-projection CRT sets, all
micro-displays can
be set quite brightly without losing appreciable detail, so they're
suitable for brightly lit rooms, although the most satisfactory
image is still achieved in dimly lit rooms.
Front Projection
To get the maximum visual experience to mimic the movie theatre,
projecting the image onto a fixed or pull-down screen allows the
largest image - to visibly immerse yourself in the experience. No longer is it necessary to spend tens of
thousands of dollars to acquire a quality super-sized image for
your home theatre. CRT based projectors were at one time the only
type that could offer satisfactory resolution to please the
average consumer. Cost and the necessity of periodic
re-calibration made this a choice for only the wealthy or the very
dedicated video enthusiast. Today very good quality front
projectors are available in several affordable technologies
including CRT, DLP, LCD and LCoS. The buyer should be aware that for
a rewarding home theatre, data projectors are inadequate and the features
of a home theater projector are well worth the investment. For
example, data projectors are designed to be used in rooms with
relatively bright ambient light to enable note taking and document
reading. Home
theater projectors are designed to display deep black levels and
allow significant gradation of light and shadow to show very fine
detail and give an almost 3-dimensional feeling. This is best
attained in a darkened room. ....see
more
Flat Panel
Flat panels -- plasma and LCD displays -- are only a few inches thick.
Their minimal space requirement is a large factor in their
adoption as a lifestyle display offering relatively large picture
size with more than satisfactory picture quality. Many of these
sets are simply video displays and do not have satisfactory
speakers attached, nor a TV tuner included. Others have built-in
TV tuners and quite acceptable audio speakers. For more detail see
our Technologies section.
|
|
|
|
With a team behind you Custom Home Entertainment is easier and more affordable than you might think.
No matter the size of your project we'll give you ideas to install and set up a small home theatre,
through to planning, designing, and wiring your whole house for audio and video.
Check out some exciting accessories to get you started on building your
dream theatre.
|
|
|
|
|
Vancouver, B.C. - Alberta: Edmonton - Calgary - Saskatchewan: Regina - Saskatoon - Manitoba: Brandon - Winnipeg - Ontario: Windsor - London - Ancaster - Dundas
- Hamilton - Burlington - Oakville - Milton - Mississauga - Etobicoke - Toronto - Ottawa - Quebec: Montreal - Quebec City - New Brunswick: Fredricton - St. Johns - Nova Scotia: Dartmouth - Halifax - PEI: Charlottetown - Newfoundland: St. John's
|
|
|
