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Posted by Rita Berkowitz on 11/07/07 02:33
Bob Myers wrote:
>> Not from an end-user's perspective when the LCD monitor dies quicker
>> than the stated MTBF. Most unsuspecting consumers are falsely lead
>> to believe that the whole unit has a chance of lasting the stated
>> MTBF.
>
> And the "M" in "MTBF" stands for what, again? That's right
> - it's the MEAN time before failure. Obviously some units will
> fail before this time is up. Some will last longer. All in all,
> though, field data very strongly shows that the reliability of LCD
> monitors is quite comparable to that of CRTs, if not at this point
> better.
LOL! I don't know what field data you are looking at, but I know that many
asset recovery specialists find the LCD one of the worst in terms of
reliability. There are 25% - 30% problematic LCD monitors per 1000 compared
to CRTs. Of course these are two to three-year-old used monitors pulled out
of service. So real world experience proves you wrong. You don't even want
to know about the scores of LCD monitors I sent back to Dell for warranty
replacement.
>> This sounds like one of them hairs that is to thin to split. The
>> bottom line is that pretty much any other part than a blown fuse in
>> an LCD monitor
>> makes it uneconomical to repair. As for CRT itself, that is a very
>> robust component and has less chance of failure provided it wasn't
>> dropped. Most of the time it's the surrounding components that need
>> fixing/replacing.
>
> Right, in terms of hard failure. But the CRT itself slowly becomes
> unusable due to a loss of cathode emissivity and phosphor
> brightness with age (well, technically, it varies with the amount
> of current delivered by the cathode, but we might as well simply
> say "age").
Failure is failure. And please don't tell me that an LCD doesn't lose
brightness and color accuracy as it ages. They all decay as they age, but a
CRT's decay slope isn't as steep as an LCD's slope.
>>> No, they're not. First, the color filters are NOT "between the
>>> backlight and the LCD." The color filter layer is produced on
>>> what is most often the "top" substrate (glass panel) that forms
>>> the LCD panel itself. The filters themselves are created via a
>>> photolithographic process and are basically a specially-made
>>> colored photoresist material.
>>
>> Interesting. I've split apart many LCD panels and I've found the
>> color correction filters in between. This even holds true with the
>> design of the
>> light engine in LCD projection TVs. It's more practical and
>> efficient to correct the light source before it hits the LCD than it
>> is to try to correct
>> everything after it has passed through the LCD. The surface filters
>> you are
>> referring to are there for antiglare.
>
> No, they're the individual color filters that are formed over each
> subpixel in the array. I think you're confusing the brightness
> enhancement films, diffusers, etc., with the color filters. It is
> simply not possible to create the color filters in a direct-view LCD
> as a layer that's physically separate from the panel - the alignment
> would be a nightmare.
Now you are starting to think. That's why the light source is filtered and
color corrected prior to reaching the LCD panel.
> There ARE, in addition, polarizers,
> anti-glare, etc., added to the basic panel, but the color filters are
> most definitely a part of the panel itself. I don't really care how
> many LCD panels you've "split apart" - I've watched the panels being
> made in the LCD fabs, and have been working with this technology for
> a good 20 years.
And how exactly does this make you even remotely correct? Please put forth
some hard evidence of the manufacturing process if you really want me to
take you seriously.
>> It would be nice, but some of us only have the luxury of reverse
>> engineering.
>
> In that case, you should be very careful about the conclusions you
> draw from this "reverse engineering," in the absence of other
> knowledge and experience regarding the technology.
I'll go by my hands on real world findings till an authoritative source
proves me wrong.
Rita
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