DLP and LCD Projector Technology Explained

Projectors can be broadly catogorised into two technologies, DLP (Digital Light Processing) or LCD (Liquid Crystal Display). This refers to the internal mechanisms that the projector uses to compose the image.

Until recently, LCD was reserved for less expensive designs while DLP models held the performance edge for high-end projectors. However, recent advances have seen both technologies converge and in most cases there is less of a reason to pick one technology over another.

LCD technology has improved immensely in the last year or two while DLP models are more competitively priced than ever before. So in short both technologies are now able to offer crisp, clear and vibrant images, the main consideration to make on which projector is right for you is down to the more specific requirements such as brightness, resolution, contrast and connectivity.

It is worth mentioning though before you read on that despite the advancement in both technologies, LCD and DLP still each have unique advantages over one another, which is why its important to understand what each of the technologies has to offer.

DLP
Digital Light Processing™ is the world's only all-digital display solution. DLP™ technology uses an optical semiconductor, known as the Digital Micromirror Device, or DMD chip to recreate source material. Please click on the icon below to launch a Flash demo to show you how it works.

Advantages of DLP
Less 'chicken wire' (or 'screen door') effect because pixels are much closer together. This doesn't make so much difference with data, but it produces smoother images for video.

A comparrison of an LCD and DLP projection to illustrate the 'screen door' or 'chicken wire effect on LCD projections.

Higher contrast achievable.
DLP has sealed optics which makes them better for use in a dusty environment.
DLP projectors are generally more poratable as fewer components are required.
It has been claimed that DLP projectors last longer than LCD projectors.

Disadvantages of DLP
The 'rainbow' effect, appearing as a momentary flash of rainbow-like striping typically trailing the bright objects when looking from one side of the screen to the other, or when looking away from the projected image to an offscreen object. Only some people see this effect, or you can create it for yourself by moving your eyes very quickly across the screen. There are two types of DLP projector - the old ones had four segments on the colour wheel, the new ones have six or even seven and spin faster, which means less rainbow effect and more saturated colour.

The 'halo' effect (or 'light leakage'). It may bother some people using their projector for home cinema. Basically it's a grey band around the outside of the image, caused by stray light being bounced off the edges of the tiny mirrors on the DLP chip. It can be a distraction, but can be overcome by having a black border a few inches wide around the screen, so the halo falls on to the border. However the halo effect is less evident in the newer DLP chips such as the DDR chip

LCD
LCD (liquid crystal display) projectors contain three separate LCD glass panels, one for red, green, and blue components of the image signal being transfered to the projector. As the light passes through the LCD panels, individual pixels can be opened to allow light to pass or closed to block the light. This activity modulates the light and produces the image that is projected onto the screen.

Advantages of LCD
LCD is generally more 'light efficient' than DLP (ie. the same wattage lamp in both an LCD and DLP would produce a brighter image through the LCD).
With 3LCD projectors, you get beautiful colour in clear, defined images - even in a bright room, and you get more than double the brightness on colour luminance, compared to non-3LCD projectors. What’s more, 3LCD projectors can project bright, vivid images with a low output lamp.
Hence, with a data signal, if you put a 1000 lumen LCD next to a 1200 lumen DLP and showed a colour image people would probably prefer the LCD for brightness.
LCD tends to produce a sharper image (ie. more precisely focused). This can actually be a bit of a disadvantage for video, where it makes the pixellation more obvious.

Disadvantages of LCD
Chicken wire effect causing the image to look more pixellated. Though with the recent advancements in 3LCD technology this is now barely noticeable.
Generally more bulky, as there are more internal components.
'Dead Pixels' - Pixels can become permanently on or permanently off, while this is barely noticeable with one dead pixel, if the projector develops multiple dead pixels it can be a irritation.
LCD panels can fail, and are very expensive to replace. DLP chips can also fail but as there are fewer parts in a DLP projector this is relatively rare.

Conclusions
LCD projectors are generally better where colour reproduction is critical, although DLP projector manufacturers are working towards a much better colour accuracy with the introduction of "Colour Enhancement Technology" and "Brilliant Colour Technology" from Varies Brands.

There are some great LCD and DLP machines availble on the market, and the technology for both is always improving.

Before Buying your LCD TV....Think

Planning to buy an LCD TV this season. However, not sure how to go about hunting, what to look for? What size, what features and at what price points. The wide range and schemes being offered by various electronics makers like Toshiba, LG, Sony, BenQ, Samsung and Panasonic only making task more difficult. Worry not, here's a readymade guide to hand hold you through the entire process. Tell you the essentials you need to keep in mind while picking up that LCD.

As a buyer, screen size is the first thing you need to decide on. Users generally fancy large size LCDs. The general view is the bigger the LCD, the better. However, ideally one must decide the screen size depending upon the space and distance available. For a proper viewing experience, one must maintain the right distance between viewing area and television screen. This is important as a larger display when viewed from closer distance shows grainy or pixelated images. It also causes eye strain. The accepted distance for LCD displays is two to five feet for 20-27-inch displays, six to eight feet for 32-37-inch displays, 10-14 feet for 42-46-inch displays and 16 feet for 50-inch display and above. Also, LCD scores over CRT models in physical depth. Most are less than 3 inch in depth. Along with size, it is important to check viewing angle. LCD TVs have a good side-to-side view angle, with wide angle ranging from 160 degrees to 80 degrees from the center viewing spot. Another important thing to keep in mind while buying an LCD, is the space you have to put up your LCD television. Since they are thin, they can be either wall or table mounted. However, wherever you place them make sure they are not near or over a microwave or a heater. As the heat may affect their life and performance. Also, make sure that you leave space for ventilation and connection access.

Pixel resolution
Resolution or picture detail defines how finer or sharper the picture quality would be. Better the resolution, sharper the picture quality. Average LCD TVs offer a minimum pixel resolution of 1280x720. This should be treated as the minimum pixel count one should go for. Some large screen LCD TVs have as high pixel resolution as 1920x1080 , accompanied by obviously a high price tag. Like LG’s popular Scarlet range which comes in 47 inch to 42 inch range has 1,920 x 1,080 pixel resolution while the 37 inch and 32 inch models offer 1,366 x 768 pixel resolution.

Contrast ratio
Another factor to note is the contrast ratio. It determines the degree of variation of the whitest and darkest parts of the image. If LCD TV has a low contrast ratio, dark images will look grey and while light images looks washed or blurred. An average contrast ratio to have in an LCD TV is 10,000:1 for 32-inch. Toshiba's new range of LCD TVs offer Higher Dynamic Contrast ratio (maximum 30,000:1 in 37-inch LCD). Samsung's latest LCD LA46A650 has a Dynamic Contrast Ratio of 50,000:1 in 46-inch. LG's Scarlet series also has a Dynamic Ratio of 50,000:1 in all models.

Motion Response Time
In case you are a sports lover or action movie buff, Motion Response Time is a must check. Motion Response Time is the ability of an LCD TV to display fast moving objects. This is important as otherwise fast moving scenes like say a speeding car or in a tennis match scene, you may see notice a blur. It is described as fast motion blur. So, before you buy, check the specifications for Motion Response Time (ms = milliseconds). On an average, an LCD TV should have a Response Time of either 6 ms, 8ms or 12ms.

Compatibility
Check for the connectors offered. If you have a home entertainment equipment, make sure that the LCD TV has all the connections necessary to hook up to your home entertainment systems. Also, your LCD TVs can work as a computer screen. So, check for connections for composite, S-video, component video and RGB SCART inputs. You may also want to connect your TV to gaming console, HD DVD or Blu-ray player.

Price
LCD TV price depends on the size and features you are looking for. As the features and size go high, so does the price. In some cases, it may depend on the brand. Ensure to follow the guide before spending your hard earned money.