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 £300+VAT.  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.  Manufacturers stopped producing OHPs in favour of multimedia projectors.

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 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 1,000 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.

There are now projectors on the market that use an LED (light emitting diode) light source. LED's are energy saving and can last up to 20,000 hours, depending on the make and model of your projector. 

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 1.5 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 5 kg. These projectors often have light levels over 1,900 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.  Some makes and models have a stacking function, which means you can stack two projectors one on top of the other, and adjust the lens focus so that they projector one very bright beam of light.  This could be used, for example, to project an image across a motorway onto another building.

Projector manufacturers now make short throw projectors and these are designed to be used with interactive whiteboards. As the projector sits on a short boom arm on the wall above the whiteboard, this almost eliminates the glare of light when using the board.  It also eliminates your shadow as you work on the whiteboard.   Promethean Activboards and SMARTBoards have brought out  interactive whiteboards attached to a wall frame with a boom arm and short throw projector, all-in-one solutions.  These are available as fixed height or height adjustable frames. Other manufacturers such as Hitachi, Panasonic and PolyVision have boards with compatible projectors and wall mounts to give an all-in-one solution.

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 where most projectors sold are now XGA (1024 x 768 pixels) resolution, with many models offering WXGA widescreen XGA, SXGA, WSXGA, and high definition (1920 x 1080 pixels).

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.

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. 

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 channelled 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.

Traditionally, LCD projectors gave sharper, clearer data images than DLP units. DLP projectors normally produced smoother video images. Despite the often slightly smaller size of DLP projectors, the better data quality of LCD projectors meant that LCD technology accounted for around 80% of sales. 

Nowadays, both LCD and DLP projectors give clear images.

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 or SXGA+ resolution. This combined with LCoS having minimum space between pixels means you get very clear images especially on text. Larger projected images look clearer.  These are ideal if you display photographs or images which have lots of detail.

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.

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.