LCD VS DLP Step 1 - Definition of each technology. The first step in comparing these two technologies is to understand how each works. Once we know the basics of how each works then we can proceed to step 2 the differences in performance. DLP Process 1. Light is emitted from a light source (ie Intense lightbulb). 2. It is condensed and passed through a color filter/color wheel. The color wheel turns at several thousand RPMs and had at least the 3 primary colors on it. When it wants to show a red pixel the light shines through the red part, likewise with green and blue. Some color wheels have more than 3 colors but 3 is all that is technically needed. 3. The light then hits the DLP chip. The DLP chip consists of thousands of mirrors that can effectively be turned on or off. Each pixel (a pixel is a dot that makes up the picture you see) is made up of a group of these mirrors. If half the mirrors are on when the light hits them then you get a darker color. If all of them are on you get a bright color. Because they are so small and on a micro chip, these mirrors can move off and on hundreds of times a second. The DLP Board, Processor and Memory change the incoming video signal to the picture. LCD Projection Process 1. Light is emitted from a light source. 2. It is broken apart into Red, Blue and Green and taken in 3 different paths. 3. Each of these light beams then passes through a transparent LCD. At this point we have 3 images (one red, one blue and one green). 4. These 3 LCD images come together in optics to form one full color picture that is projected onto the screen. First Thoughts and Comments LCD projection seems a simpler solution than DLP. LCD projection has no moving parts which may make it less prone to catastrophic. However the only major moving part is the color wheel as the likelihood of the DLP chip failing is slim. LCDs also have been shown to get dead pixels. So while the LCD is less likely to produce no image at all, it may be more likely to have dead spots which may or may not be noticeable. Also the above diagrams and explanations show systems with 1 light source. It is becoming more of a standard to have 3 light sources (red, green and blue). While this triples the number of light emitters (bulbs) needed, it produces an even sharper picture. How DLP and LCD Projection are Alike LCD Projection’s and DLP’s resolution (the amount of pixels or dots that make up the picture) are pretty comparable. Each television’s max resolution depends on the specific television that you are looking at. All will be at least 1080i (1,080 pixels across) but most will be able to show a much higher resolution. HD TV signals are usually 1080i but will be going up in the future. Higher resolutions are also desired for those who like to attach PCs (or Macs) to their televisions. DLP and LCD Differences/Downfalls DLP usually wins the battle of “Screen Door Effect” and “Contrast”. LCD wins the “Rainbow Effect” and “Color Saturation” war. These are all described below. Screen Door Effect The “Screen Door Effect” is very similar to what it sounds. Think of the difference between looking through a window and through a screen. The screen door effect is the distance between pixels as seen here. DLP normally beats LCD in this regard. The mirrors on a DLP chip are super close. By design it is harder to get the pixels on an LCD as close. Now remember this is normal generic terms. One can judge this by getting really close and looking at the pixels. If you get real close and see no difference then this “Screen Door Effect” doesn’t affect you. Rainbow Effect DLP has a “Rainbow Effect”. If you quickly move your eyes from one side of the screen to another you may see a rainbow of colors. Not everybody sees this. This is due to the colors being generated by light shining through a color wheel. If 3 colored light sources are used in a DLP projector/television there is no rainbow effect. However this is usually quite a bit more expensive. Faster color wheels and color wheels containing intermediate colors reduce this. Keep in mind that you will probably not even be able to tell. There is no rainbow effect for LCD Projection. Contrast Contrast is the difference between the darkest black and the brightest white. Traditionally DLP has the best range. However recent LCD advancement has made this difference almost nothing although DLP still has a slight advantage. Color Saturation Color saturation is intensity or purity of a color. Higher color saturation makes the picture more alive. Historically LCD/LCD Projection has a higher color saturation than DLP.
