There are so many projectors on the market that when you’re looking for the right equipment for your school or educational institution it can often be difficult to know where to start. The main issue is whether you choose LCD (Liquid Crystal Display) projector or DLP (Digital Light Processing). Both types of projector have advantages and disadvantages, and understanding more about the technology could help you make the right decision.
The technical difference between DLP and LCD projectors
LCD projectors have a single source of light that is split into three beams, which pass through one of three LCD glass screens, one each for the red, blue and green components that make up the picture. Each panel is made of thousands of liquid crystal pixels which act like shutters and can be open, closed or partially closed, depending on the data that determines what colours are to be produced. The three beams then combine to project an image onto the screen.
DLP projectors also normally use a single source of light that is reflected off a DLP chip. The chip has hundreds of thousands of tiny mirrors that reflect the light through a spinning colour wheel. A combination of timing and tilting of the mirrors to create an on/off effect modulates the colour of the light, which is then directed through a lens and onto the screen. (There is also another type of DLP projector that uses three DLP chips, but this is usually only seen in high-end, very expensive equipment.)
The difference between DLP and LCD – advantages and disadvantages
So now we understand more about how DLP and LCD projectors work, let’s look at the advantages and disadvantages of both systems.
Smoother video playback
Colours can be saturated
“Digital noise”-like effect
Restriction on lens size/zoom
Uses less power
Emits less heat
Zoom capability for more flexible installation
More stable images
Units are much larger
Unknown lifespan of LCD screens
As you can see, both DLP and LCD projectors have pros and cons, but which type of projector is the best buy for your school? Let’s look at each type in more detail.
The big problem with LCD units is they require quite a lot of maintenance to keep them working correctly. They have filters that need cleaning regularly, and it’s possible for dust to get into the projector itself, causing dust spots on the projected image. There’s the chance of “screen burn” – where an image is on screen for long enough that a ghost image is left behind. LCD projectors can also suffer from convergence, where the three lights move out of alignment and affect the image. However, the biggest disadvantage of LCD projectors is that the lifespan of the LCD screens is unknown. They can deteriorate quite quickly and it’s very expensive to replace them; in fact it would be more cost-effective to replace the entire projector.
On the other hand, DLP projectors are very low maintenance. They are filter-free, and the DLP chip is a sealed unit so dust can’t enter. Because they use a single beam there’s no risk of convergence. The technology means that screen burn doesn’t occur, and the image will not degrade over time. But most importantly of all, the only part of the projector likely to expire is the bulb, which is replaceable – so the projector will last a lot longer.
The main disadvantage of DLP projectors is they only have a short focal length and no zoom capability so installation is not especially flexible. In order to project an image properly they need to be sited close to the screen (usually between 1-2 metres away) and preferably suspended from the ceiling. While this is fine in a classroom situation, it does mean they are perhaps not suitable for use in large school halls or other areas where they might need to be placed at the back of the room. This is where LCD projectors triumph – as they have longer lenses and up to 2x zoom, they work equally well whether at the front of the room or on a shelf at the back.
To summarise, understanding the difference between DLP and LCD projectors is very important when you’re buying equipment for your school. DLP units are smaller, require less maintenance and will last longer, but they do need to be located close to the screen. However, if you need the flexibility to locate the unit at the back of a room or hall, you may need to look at LCD projectors.
At Smarter Interactive we can supply your school with a projector to suit your needs and budget, from an entry level LCD projector to high end DLP projectors with a huge range of features. We also have a mid-range DLP projector developed with schools in mind; for example, it has an option for the teacher to blank out the screen to regain students’ attention. Other features such as the dimming of the projector bulb when no source is attached and a Smart Eco mode where the bulb delivers exactly the right light to suit the conditions mean the overall cost of ownership is reduced through lower power consumption and extended bulb life. We also offer education providers a three year warranty on bulbs.