Topic Today: DLP projection technology

I purchased a re-manufactured InFocus DLP-350 off of ebay. That makes me either the bravest, or most stupid, person you know.

So far, I haven't gotten burned. I'm satisfied with the projector but, to be completely honest, now that I own it I would never recommend it to anybody else.

I would recommend DLP, but learn from my advice, and research it better than I did.

First of all, yes, DLP blows away LCD. The technology behind it, is simply amazing!

Here's the URL for a website that discusses the technology:

What makes DLP so amazing is that it's a *MECHANICAL* TV!

Some scientist invented a micro-mirror, something like 1/10th the size of a human hair. It is mounted on a small pivot and when current is run through it, the mirror turns towards or away from incoming light.

If the mirror is away from the light, then the pixel is 'black' and if the mirror is towards the light, then the pixel is 'white'. The mirrors vibrate back and forth 10,000 times a second, strobing at an insanely high speed to produce a grayscale pixel.

Now, on a DLP system (DLP of course stands for 'digital light processor'), there can be roughly one million of these micromirrors mounted on a chip. I don't know the exact size, but imagine a million mirrors the size of a single frame of a film!

So, if these mirrors can only produce grayscale images, how do you get color? Well, in most all consumer DLP projectors there is a color wheel. This is a filter that spins very rapidly in front of the lens. The filter is red, green, and blue, and the digital light processor is synchronized to produce a grayscale image representing the brightness level for each of these color components.

So, when you watch a DLP projector, you are actually seeing 3 seperate frames strobing at a very high speed. Just like film, your eyes and brain combine these strobing images as if they were one continuous color.

There is an artifact from this technique that causes most people to see a rainbow effect when staring at the projected image. You mostly notice if you move your head rapidly, or simply waggle your finger in front of your eyes. The rainbow effect is more or less pronounced from one person to the next.

It doesn't really bother me at all, though I do see it from time to time. It's certainly a lot less annoying than hearing film spool or dealing with the scratches and lines we put up with conventional film.

If you use a DLP projector then you want a DVD player that has component out, so you can get the absolute maximum resolution video signal possible.

A key component of a DLP projector is the de-interlacer. Film is analog so when you project it there is no such thing as 'pixels', it's just smooth automatically. But with a system like LCD or DLP you begin with a fixed resolution image that you are then trying to blow up on a screen. It's a major technical challenge to prevent the pixels from being obvious or distracting.

The InFocus DLP350 I own has an incredible de-interlacer. And I can *never* see individual pixels. It's simply amazing technology. Very film like indeed.

As I said before, my only objection to DLP (and it *may* just be my machine) is the lack of contrast.

With the micromirror technology, even if a mirror is completely 'off' it still projects a lot of light. A DLP projector showing a 'black' image is very obviously bright on the screen. If you are a computer guy and used to thinking in grayscale, then I would say a 'black' pixel is about a 64 on a grayscale range of 0 to 255.

That's a long way from black.

Plus, I think the filter somewhat deadens or dulls the overall color depth.

The high-end DLP3 projectors do not have this problem. This is the technology George Lucas has been promoting with his digital theatre concept.

DLP3 uses 3 seperate digital light processors and a prism. There is no color wheel or strobing effect. The light is broken up by the prism and recombined to produce color that *exceeds* film quality. If you can believe that. It's truly amazing. It also costs something like a $100,000 for a system.

Here's an Ebay auction of the same projector I own:

Here's a link to the InFocus website:


Now, I would not recommend the InFocus DLP 350. However, I *strongly* recommend DLP technology. Just do more research than I did. Pay really close attention to the quality of the deinterlacer, the base resolution and, most importantly, the color reproduction quality.

I project my DLP system onto a 72" screen on a regular basis and it looks awesome. I put it up on a 9 foot screen once, and it still looked incredible.

This technology is seriously expensive. High end DLP projectors typically run 6-9 thousand dollars. So, even with the problems I described, I really feel like I got a bargain at $1900 for mine.

The only costs for running it is to replace the lamp after about 2,000 hours of viewing. A new lamp is around $200.

John

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