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Projecting the right image
Projectors, over the past few years, have improved in
technology, whilst the cost has come down, which means you can buy a multimedia
projector for less than £500. In fact, with projector lamps at an average
of £250, some businesses prefer to upgrade to new projector models rather than
replace the lamp.
In universities and hospitals, OHPs and slide projectors are still used but are
not as common as they once were.
With a projector, as well as the benefit of high quality, high impact PC
generated ‘slides’, presentations using data/video projection can
incorporate video clips and sound, allowing companies to easily and
cost-effectively create true multimedia presentations. Most projectors
will also project from a video source such as a VCR or DVD player.
No need to dim the lights
Early multimedia projectors had low light output levels
meaning they could only be used in rooms with blinds or heavy curtains.
Even though projectors that can be linked to a computer have been
available for the last six or seven years, it wasn’t until about two
years ago that projector brightness increased enough to allow use in a
wider range of environments.
Brightness of projectors is measured in ‘ANSI
lumens’ and whilst early projectors had ratings of only 200 or so,
even the latest ultra portable models now offer 800 ANSI lumens and
above. This means that the projector can quite happily be used in a well
lit room with no need to dim the lights. Anyone considering buying a
projector offering less than 500 ANSI lumens should be very careful
about the environment they intend to use it in.
Small is beautiful
Not only are projectors brighter, they are also smaller.
Early ‘portable’ projectors weighed 12 or 13 kg and were not a
viable option for use off site. The fastest growing market sector
is now ‘ultra portables’ weighing around 4 kg and with a footprint
area of an A4 piece of paper. These projectors are revolutionizing
presentations for the so called ‘road warriors’, constantly
travelling from one client meeting to the next. Because this type of
projector is likely to get more knocks, products that have a
lightweight, but durable magnesium alloy case, instead of a plastic one,
are leading the way.
The next sector up is ‘portable/desktop’ projectors
with weights up to 8 kg. These projectors often have light
levels over 1,000 ANSI lumens and are used mainly on site in boardrooms,
meeting rooms, training rooms etc., with occasional use off site for
sales conferences, exhibitions etc.
At the top end projectors for fixed installations in
large auditoriums, with brightness ratings of 2,000 ANSI lumens or more.
BECTA an organisation that makes recommendations for the education
market, maintains that a projector should be no more than 1,500 in a
classroom that is using an interactive whiteboard, because of the glare.
However, many projectors now offer eco mode, so you could in theory, buy
a 1,900 ANSI projector and run it in eco mode at 1,400 for the
classroom, thus benefiting from prolonged projector lamp life, and then
running it at full power of 1,900 when used in the school assembly hall.
Pixel power - the resolution dilemma solved
Another factor that held back projector sales until
recently was the resolution. For some time data projectors lagged behind
mainstream computer display technology, offering only SVGA (800 x 600
pixels) resolution. Potential buyers understandably held back with
future proofing concerns. However, projector technology has now improved
to the point most projectors sold are now XGA (1024 x
768 pixels) resolution with some models offer WXGA widescreen XGA.
Plug and Play
One area that still puts people off using multimedia
projectors, is setting them up. In reality modern projectors are
incredibly easy to use and automatically lock on to just about any
standard computer output automatically. In most cases just a single
connection cable is required.
Leave the computer behind
Of course one way to overcome connection difficulties is
to take away the requirement for a computer. Sanyo was the first
manufacturer to introduce an innovative PCMCIA slot on their ultra portable computers.
This means that a presentation can be downloaded from a PC onto a normal
type II PCMCIA card. The card is then inserted straight into the
projector so that the presenter can leave their laptop behind. Not only
does this make the projector even easier to use, it also means around 3
kg less to carry around.
LCD vs DLP
There are currently three projector technologies being
used by manufacturers:
LCD (liquid crystal display) is the established
technology used by most of the leading manufacturers. Light from a
powerful lamp is split into red, green and blue and then channeled
through three panels made up of liquid crystal dots or pixels. Electric
currents are used to ‘switch’ individual pixels off or on in each of
the panels, thereby letting the different colour light through to make
up the image.
DLP (digital light processing) is a newer technology
used on some of the smallest, lightest projectors currently available.
Thousands of tiny mirrors are used to reflect light in order to produce
the picture.
LCD projectors invariably give sharper, clearer data
images than DLP units. DLP projectors normally produce smoother video
images. Despite the often slightly smaller size of DLP projectors, the
better data quality of LCD projectors means that LCD technology accounts
for around 80% of sales.
LCOS (liquid crystal on silicon) technology is currently available from a few
manufacturers. LCD uses liquid crystals on glass panels, and light passes
through the LCD panels to the lens. DLP uses tiny tilting mirrors to pass
light. LCOS uses both these ideas, in that it is a reflective technology that
uses liquid crystals instead of tiny mirrors. LCOS projectors typically use
three LCOS panels, one for red, blue and green.
LCOS projectors are mainly SXGA which is cheaper than the
other technologies to produce this resolution. This combined with LCOS having
minimum space between pixels means you get very clear images especially on
text. Larger projected images look clearer.
Projector pitfalls
Be careful when considering ‘micro portables’ i.e.
under 3 kg. This latest category of projector offers extreme portability
but something has to give. Usually this means image quality but it can
also mean that the projector has no zoom lens fitted. Without the
flexibility to adjust image size from a particular distance the
presenter is severely restricted as to where they can position the unit
in a room. In fact, micro portables without a zoom lens are something of
a contradiction in terms. Their portable nature means they will be used
in a wide variety of rooms. However this is just when a zoom lens is so
important, giving the presenter the flexibility to adapt to different
room settings and layouts.
Although most SVGA projectors will cope with and XGA
signal, how they cope with a resolution other than their native
one is very important. Cheaper SVGA models will compress XGA by simply
dropping lines of data giving very poor image quality. Likewise, low end
XGA projectors will give poor image quality when expanding out the 800 x
600 signal to fill the full 1024 x 768 area. With so many SVGA screen
laptops around still, how an XGA projector handles the lower resolution
is a key factor that many buyers overlook. The majority of
projectors now offer XGA resolution.
Quality counts
The multimedia projector market differs from many others
in terms of the market share controlled by the high quality
manufacturers. It would be normal for the volume sales to go to low end,
cheaper product, however this is not the case in the projector market.
It seems as though once end users have taken the decision to invest in a
projector they’re not willing to compromise on either image quality or
reliability for the sake of a slightly lower price.
Data
and video projectors
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