These pages feature general information on projectors, projector technologies and practical advice on projector setups.

Video / Data Projection Technologies	LCD (Liquid Crystal Display) DLP (Digital Light Processing) LCOS (Liquid Crystal On Silicon)
Projector Setup Guide	Click here
Projection Screens	Click here
Using Audio	Click here
Projecting from an APPLE MAC	Click here
GLOSSARY	Click here
Placement - Optimal placment is for the screen to be placed centrally at a 90 degree angle to the projection device, with the bottom the screen and the lens being level. The distance between the screen & unit should be twice the width of the screen image. It is possible to compensate for situations where the projector & screen bottom are not level using the digital keystone facility. Our XGA units allow for horizontal keystone adjustment if the projector cannot be placed centrally. Keystoning (in case you are unaware) results in the image being distorted and no longer rectangular. eg. If you are projecting from below the screen the image will be wider at the top than at the bottom. Digital keystone allows for the image to be adjusted to restore the desired rectangular shape onscreen.
LCD - LCD projectors use Liquid Crystal Display (LCD) panels, similar to those found in watches, clocks, games and other display devices. A light source is shone through the LCD panel which is covered in a grid of individually controllable cells (picture elements). Each LCD picture element is equivalent to a pixel in the display resolution, ie. an SVGA resolution LCD projector will have a grid of 800 wide by 600 high individual picture elements. Each individual picture element can be faded between 100% transparent and 100% black, controlling the light level emitted for each particular pixel. All but the cheapest LCD projectors will actually have three of these LCD display units, with the light source being split (using dichroic mirrors) into separate Red, Green & Blue (RGB) streams, each of which is then fed through its own LCD display panel, thereby controlling the amount of red, green & blue light hitting each pixel. By controlling the relative mixes of these three primary colours hitting each pixel all other colours can be created.
DLP - DLP projectors work by shining light through a DLP chip which consists of a grid of tiny mirrors, each mirror corresponding to a pixel, therefore an SVGA DLP projector will have a griod of 800 wide by 600 high mirrors. These mirrors can be manipulated electronically to either allow light to shine through or be deflected away internally for any given pixel. By flicking between on & off for any given frame a 50% brightness can be created for a given pixel. High end (and therefore expensive, ie. over £10,000) DLP projectors use three of these panels with separate Red, Green and Blue (RGB) light channels. Cheaper models use a colour wheel which can either have three (RGB) or 6 colours. The colour wheel is rotated in conjunction with a screen image faster than the eye can see which means that the three separate Red, Green & Blue imges are perceived (theoretically) by the eye as one full colour image. This in itself will be a little too quick for the eye to see but when repeated we get a faithful replication of the moving (or still) image input into the DLP projector. The first generation of DLP projectors had a colour wheel which rotated at 60Hz or 3600 revolutions per minute. Unfortunately some people do not see the complete image as intended and instead see separate red, green & blue components causing headaches, eyestrain and other side effects. This is known as the "rainbow effect". Next generation DLP projectors have 2x (or faster) colour wheel rotation as an attempt to reduce this effect, although for certain viewers it still remains a problem.
LCOS - LCOS projectors are a hybrid of LCD & DLP technologies mentioned above and are not particularly widely available at this time. Pioneered by Hitachi they look like they may become the dominant projector technology in the future. Liquid crystal is placed in front of a silcon grid which also contains (or masks) the electronics. The liquid crystal is manipulated electrically by the silcon grid which is highly refelective, thereby allowing light on any given pixel to shine through (or not). This produces a gray scale image which can then be coloured either by a rotating colour wheel in the case of a single panel system or by dichroic red, green & blue mirrors in a three panel system. LCOS projectors tend to be less bright than equivalent DLP of LCD projectors. LCOS offers high resolution, high quality images.
Screens come in various different sizes and types. The most basic and easy to use is the tripod screen which is a free standing unit, with a pull down roller type screen. It can be packed away or erected in a minute or so. These screen can be for front projection only. Screens can also be pulldown screens which must be hung from above - Just imagine a tripod screen without the stand. These are often used for theatre work and such like where the tripod screen is unsightly / unpractical. These also are suitable for front projection only. The last standard type of screen is the fast fold which are supplied with front & rear projection surfaces which can be used as required. They have a large frame which must be unfolded and the chosen surface & legs must be fixed. They can also be hung if required. These screens are a little more complicated than the others to assemble, and are more expensive to hire. All screens are available in various sizes, measured in width (not diagonally).
Audio Playback - Modern projectors are generally not equipped with speakers of any note therefore if your usage requires audio then external speakers & amplification must be used. These will generally be connected directly to your image source (eg. DVD players, laptop, etc), with a video output only connected to the projector.
Projecting from an Apple Mac - Macintosh computers use a different system of connectors from PC monitors but they are generally supplied with a convertor which you will require to plug in to the projector. The projector uses a standard 15 pin d-sub connector as found on non-Ma c computer monitors.