LCD projectors, dead pixels - AVS Forum
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post #1 of 5 Old 03-26-2004, 07:31 PM - Thread Starter
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I am ready to buy my first projector and have been reading about LCD & DLP. What is the "dead pixel" problem all about, how common is it, and can it be repaired? Does either type of proj. have a longer "life span"? The Panasonic 300 sounds great, but I'm a little worried about LCD. Thanks.
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post #2 of 5 Old 03-26-2004, 10:10 PM
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Search. But I'm not hearing much in dead pixels on the latest LCD's. Actually we've seen some dead mirrors on DLP's the past couple of days. I'm thinking this issue is becoming quite rare. (Knocks on wood for a while before next projector startup)
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post #3 of 5 Old 03-27-2004, 06:44 PM
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Jim Mcc,

An LCD image will have millions of little dots called pixels. They are constantly changing colors to produce your image. When an LCD pixel dies it will end up looking like a dark little spot on the screen, if it dies off. This to me is the least offensive, but it can die on in RED, GREEN, or BLUE. Man do I hate that. Once you see it you can't take your eyes off from it. There is no fix for it once you get it, in fact most warranties don't even cover it. I have actually seen manuals that will tell you this is normal. It does still happen, and in my experience to often. They have improved, since its not near as bad as it was in the past, but as long as the warranties do not cover it I will take no part of it. In fact my local Circuit City has a very large selection of LCD's, and last time I was there I counted 3 of there sets with dead colored pixels.

DLP's can get something similar if one of their little mirrors stops functioning. This will give you a small dark pixel spot. I have read about a few of those, but I have yet to actually see one and I would suspect it is less common for a dlp to have a faulty pixel vs an LCD.
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post #4 of 5 Old 03-28-2004, 01:22 PM
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pixel stands for picture element, and is the smallest division (bit of info)referenced in a picture (i.e. a pixel can only be one colour). what happens is that sometimes the device that produces that pixel can malfunction, and that is what is meant by dead pixel.

DLP: dead pixels are usually stuck to off, so you will get a black dot. But if it is stuck on, then you will get a white pixel. (this is because of the single chip design

LCD: all LCD projectors have 3 panels, so in theory 1/3 of pixel will be dead. That means that in theory a dead LCD pixel (on or off) will be less noticeable then a dead DLP pixel.

Because dead DLP pixels tend to be more noticeable TI has put greater care into having less dead pixels (i.e. more quality control before chips are sent out). Also a lot of the LCD manufacturers have some rules on where and how many dead pixels are acceptable. If you do have a dead pixel, then there is nothing you can do, it means that the chip/panel is bad and it needs replacing
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post #5 of 5 Old 03-28-2004, 02:57 PM
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The CircuitCity 'CityAdvantage' protection plan supposeddly covers dead pixels (according to long conversation with the store TV manager). It is a rather pricey plan... I think they calculate this based on a percentage of product cost.

HOWEVER, upon close inspection of their policy online, it clearly states that Dead Pixels are NOT covered. !!!!!!!!! Too bad. I was going to pay the extra $125 for the X1 protection plan... not worth it though, unless they replace upon a single dead pixel.

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