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LCD Screens - to they lose brightness with age ?
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#11
 
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Re: LCD Screens - to they lose brightness with age ? -
05-25-2006
, 02:43 PM
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In message <4dj1vtF1a9l0rU1 (AT) individual (DOT) net>, Arno Wagner me (AT) privacy (DOT) net> writes Previously Jeremy Boden <jeremy (AT) jboden (DOT) demon.co.uk> wrote: In message <1276ovthen69i11 (AT) corp (DOT) supernews.com>, Hawk jedi001 (AT) netscape (DOT) net> writes "Al Dykes" <adykes (AT) panix (DOT) com> wrote : Does the white light source behind a LCD screen get dim with age? Yes they do. If you leave your monitor on 24/7 you will want to make sure that it goes into standby mode when not in use so that the backlight turns off. LCD and Plasma TV's also slowly degrade in brightness over time. It happens so gradually that you may not notice it. Luckily...most are so bright that you need to turn them down anyways, so you have some room to crank it up later if needed. The backlights on my Samsung LCD's are rated at a roughly 20,000 hour lifespan (with 90% certainty). That equates to about 10 hours of usage per day over 5 1/2 years. What does the phrase "with 90% certainty" mean? You are either certain or you are not... How about quoting a MTBF? MTBF is sort-of expected time to failure. i.e. something like 50% have failed after the MTBF time (roughly, bad ststistics on my part, I know). 20'000 hour with 90% means that after 20'000 hours 90% are still working. That sounds pretty bad!!! |
(non-standby) hours, then that should give you 5 years lifetime
or so. I think that is acceptable.
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I don't know what the statistical distribution of failure is - perhaps a 100,000 hours MTBF??? |
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My Seagate disk drive (a mechanical device!) quotes a MTBF of 1,400,000hours. |
the MTBF does not hold anymore. And HDD manufacturers have been
known to lie about the MTBF of their products.
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I think I will wait a few years before getting one of these flat panel gizmos. |
pixel policies currently used.
Arno
#12
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That sounds pretty bad!!! I don't know what the statistical distribution of failure is - perhaps a 100,000 hours MTBF??? My Seagate disk drive (a mechanical device!) quotes a MTBF of 1,400,000hours. |
So how do they arrive at that figure? There would hardly be a sufficient
statistical base to make such long projections.
#13
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That sounds pretty bad!!! I don't know what the statistical distribution of failure is - perhaps a 100,000 hours MTBF??? My Seagate disk drive (a mechanical device!) quotes a MTBF of 1,400,000hours. Which is roughly 160 years of continuous operation if my maths are half-decent. So how do they arrive at that figure? There would hardly be a sufficient statistical base to make such long projections. |
the same type in parallel for a small number of hours, and do
complicated statistical analysis on the results of that, to get the MTBF
figure.
In other words, it's a number good only for comparing to other similar
devices, and not an actual predictor of when the drive will fail.
Rob
#14
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On Thu, 25 May 2006 14:00:51 +0100, Jeremy Boden <jeremy (AT) jboden (DOT) demon.co.uk wrote: That sounds pretty bad!!! I don't know what the statistical distribution of failure is - perhaps a 100,000 hours MTBF??? My Seagate disk drive (a mechanical device!) quotes a MTBF of 1,400,000hours. Which is roughly 160 years of continuous operation if my maths are half-decent. So how do they arrive at that figure? There would hardly be a sufficient statistical base to make such long projections. |
Component lifetime is 5 years typically for HDDs. After this time
the failure rate increases. Component life is determined separately.
For MTBF, they take, e.g. 1000 drives and do a "burn in" on them, i.e.
run them for a week or so at high load. Then they run them for e.g.
a month and look how many drives have failed in that month. That
monts equals 720'000 operating hours. If one drive has failed,
they het an MTBF of 720'000 hours. With two drives they get
360'000 h MTBF, and so on.
For the Seagate number they could have, e.g., run 2000 drives for
2 month and have had 2 failures.
Arno
#15
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budgie wrote: That sounds pretty bad!!! I don't know what the statistical distribution of failure is - perhaps a 100,000 hours MTBF??? My Seagate disk drive (a mechanical device!) quotes a MTBF of 1,400,000hours. Which is roughly 160 years of continuous operation if my maths are half-decent. So how do they arrive at that figure? There would hardly be a sufficient statistical base to make such long projections. I've been told that they run stress testing on several hundred drives of the same type in parallel for a small number of hours, and do complicated statistical analysis on the results of that, to get the MTBF figure. |
lifetime, but about determining failure probability during the
lifetime.
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In other words, it's a number good only for comparing to other similar devices, and not an actual predictor of when the drive will fail. |
conditions.
Arno
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