REVIEWS / Video Projector Reviews (DLP, LCD, HD, 4K, 3D...)
Projectors have one consumable that needs to be replaced: the bulb. After an average of 2,000 hours of use, it has to be changed and this can cost anywhere between £200 and £600. Two thousand hours might not seem like much, but if you watch three two-hour films a week, you won't need to change your bulb for six years.
If you are a real gaming buff and want to connect your console though, using it for two hours a day will result in changing the bulb after three years.
For everyday use, it's still worth sticking to a traditional TV and keeping the projector for special occasions. After all, you don't need a twelve foot screen to watch tomorrow's weather forecast ...
Two rival technologies are at war in this market: some projectors use DLP technology while others opt for LCD. The two systems work in different ways and produce different results. DLP fans enjoy deeper blacks and the total absence of ghosting, but LCD projectors can produce larger images at the same distance from the screen, and they don't produce 'rainbow effects', which make some users see flashes of red, green and blue when watching DLP projections. Note that Sony has now thrown its own type of projector technology—called SXRD—into the mix too!
DLP, LCD or SXRD?
DLP - Digital Light Processing. This system is based on three elements: a light source, a colour wheel and a DMD (Digital Micromirror Device) chip. The colour wheel is divided into segments of three different colours—red, green and blue—and as it spins, it splits up white light coming from the lamp. These colour fragments are then reflected by tiny mirrors on the DMD chip, whose position varies by up to 10°, to send a particular image towards the projection lens. Your eye then reconstructs the colours of the final image by fusing all of the colours reflected by the mirrors. For example, when these mirrors rapidly reflect red and green light, you will see yellow. The number of mirrors in the chip is equal to the resolution of the projector. For example, a resolution of 1280 x 720 pixels requires 921,600 mirrors.
LCD - Liquid Crystal Display. This system is comprised of a lamp, two prisms and three LCD panels. The first prism is in charge of separating the light the lamp emits into the three components of red, green and blue. Thanks to a series of mirrors, the separate light rays each hit an LCD panel which, depending on the position of its cells, may or may not let the light through. A last prism placed between the panels recombines the three light beams and sends the image through a projection lens.
SXRD - Silicon X-tal Reflective Display. This Sony system uses a custom variety of three-panel liquid crystal on silicon technology, using mirrors to transmit certain colours of light and liquid crystals to block others. You can find a full description of the system on Sony's website or this Sony micro site.