What is the meaning of DLP projector?
DLP stands for 'Digital Light Processing' and is a technology invented by Texas Instruments. The picture in a DLP projector is produced by light reflecting off a Chip which has millions of tiny mirrors fixed on it. This chip is commonly known as a 'Digital Micromirror Device' or DMD. Each mirror in the DLP projector's DMD Chip represents one pixel in the digital image, so for example, in a HD DLP DMD chip there will be 1920x1080 or a little more than 2 million mirrors assembled on the tiny DLP DMD Chip. The DLP chip mirrors vibrates or wobbles to either reflect the light beam to the final image or rejects the light falling on it.
3 chip DLP projectors can process individual beams of RGB light simultaneously and are capable of producing high quality images which are bright. Most cinema theaters use 3 chip DLP projectors to show movies.
The cheaper Home and portable DLP projectors uses only one DLP Chip and processes the RGB light sequentially one after the other with the help of a high speed rotating color wheel, as shown in the animation here (from https://commons.wikimedia.org).
A single chip DLP picture is actually a sequence of partial pictures of Red, Green and Blue picture frames. Due to the Persistence of Vision of our eyes, our brains assume it is a complete picture. Some people have problems watching fils or videos on a DLP projector. They see the different RGB color, and this is called 'Rainbow Effect'. The Rainbow Effect problem of DLP Projectors is explained further down on this page.
The animated image here shows how the DLP color wheel works. When white light passes through this colored glass, for example through Red glass, Green and Blue light in the white light is blocked and only Red light is allowed to pass through. Similarly at the Green section of the color wheel, only Green light passes through and in the Blue section only Blue light passes through. So in one complete revolution only ⅓ of the total white light has passed through the DLP color wheel. Thus in a single chip DLP projector, only ⅓ of the total white light source passes through for processing in the the single chip DLP projector.
So if the lumen spec of a DLP single chip projector says the projector lamp is 3000 Lumens, the picture it shows on the screen is only using 1000 lumens or ⅓ of the total white light source. An 3000 Lumen LCD projector on the other hand using 3 LCD chips shows a picture on the screen using all the 3000 Lumens and will be much brighter. A 3 Chip DLP projector will also be bright and will utilise the full 100% input Lumens, but 3 Chip DLP projectors are much more expensive than a 3 Chip LCD projector.
Both DLP and LED projectors have their advantages and disadvantages. The following table shows the difference between LCD and DLP projector
|Features||DLP Projector Pros and Cons||LCD Projector Pros and Cons|
|Size||DLP projectors are smaller, lighter and more compact than LCD projector||LCD Projectors tend to be bigger and slightly heavier than DLP projectors|
|Price||DLP projectors are usually cheaper than comparable LCD projector||LCD projectors tend to be more expensive than similar DLP projectors|
|Contrast Ratio||DLP Projectors have better Contrast ratios than LCD Projector.||LCD projectors cannot match the contrast ratios produced by DLP but modern LCD projectors have high contrast ratios, and even though the contrast ratio figures may be far apart, viewing actual images between DLP and LCD projectors side by side, you will struggle to notice any difference between DLP and LCD projector contrast ratios.|
|Brightness||DLP projectors tend to be less brighter than LCD projector because the light is sequentially split into RED, Green and Blue light, so only one-third of the DLP projector lamp lumens strike the projector screen at a time. So DLP projectors need to be played in darkened rooms.||In LCD projector there are three separate LCD elements and all of the light from the LCD projector lamp falls on the screen, so 3LCD projectors have three times the screen brightness compared to a DLP projector with the same Lumen rating. LCD projectors can be viewed in rooms which have window curtains open.|
|Rainbow effect||Some persons may experience Rainbow effects while watching DLP projector images. The rainbow effect is caused by not having the red, green and blue coloured images from a DLP projector on the screen at the same time.||In an LCD projector, the red, green and blue images on the screen are superimposed over each other at the same time. So no rainbow effect in an LCD projector and the LCD image is three times brighter when compared to a DLP projector with the same lamp lumens.|
Rainbow effect problem in DLP Projectors
What DLP Rainbow effect means is that some people who watch single Chip DLP projectors with a color wheel, feel as if they are seeing Red, Green and Blue flashes of light, even after they stop watching the DLP picture. The cause of the Rainbow Effect is believed to be caused by the illusion created by the single chip DLP picture showing in sequence, a series of partial RGB color pictures.
Single DLP Chip LED and Hybrid LED/Laser Projectors does not seem to suffer from this problem so much as single chip DLP projectors using a color wheel.
DLP LED Hybrid Projectors
Single Chip DLP LED and Hybrid LED/Laser Projectors are now becoming cheaper and quite common. The picture quality is good and the brightness good enough in darker rooms.
DLP Hybrid Projectors overcome the brightness issue that always plagued the LED only projectors. The Achilles heel in the pure LED only projector was that the Green LED could not be made bright enough. Since White light requires that the brightness of all three RGB colors have to be of equal intensity, the full power of the Red and Blue LEDs could not be used in pure LED only projectors. The intensity of the green LED was the limiting factor.
Now comes the Hybrid projector where they use a Laser to produce a bright Green light and this allowed the Red and Blue LEDs to be fired up to their maximum brightness. End result, a bright Hybrid Projector using solid state lighting with all the advantages of reliability, long lasting bulbs or light source, etc. ...For more visit our page on the different light sources for projectors.