LCD Screens - to they lose brightness with age ?

Does the white light source behind a LCD screen get dim with age?

--
a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore. Proudly then, even more so in hindsight.

On 22 May 2006 12:13:09 -0400, (Al Dykes) wrote:

>
>Does the white light source behind a LCD screen get dim with age?

My oldest SONY LCD is nearly four years old and has not lost any
brightness. I needed to turn the backlight down when it was new and
it's been on 50% ever since.

--
Steve Wolstenholme Neural Planner Software

EasyNN-plus. The easy way to build neural networks.
http://www.easynn.com

Previously Al Dykes <> wrote:

> Does the white light source behind a LCD screen get dim with age?

Yes. The same problem as with CRTs. The phorphorous substance
looses its ability to shine. That is one of the reasons they
are trying to go to LEDs, because they loose brighness
very slowly.

Arno

> --
> a d y k e s @ p a n i x . c o m

> Don't blame me. I voted for Gore. Proudly then, even more so in hindsight.

On 22 May 2006 12:13:09 -0400, (Al Dykes) wrote:

>
>Does the white light source behind a LCD screen get dim with age?

Yes they do - they are CCFL's (Cold Cathode Fluorescent Lamps) and they age/fail
just like any other fluorescent tube. The inverters which drive them also fail,
but they generally either work or don't work, rarely having any comtribution to
reducing light output.

Previously Arno Wagner <> wrote:
> Previously Al Dykes <> wrote:

>> Does the white light source behind a LCD screen get dim with age?

> Yes. The same problem as with CRTs. The phorphorous substance
> looses its ability to shine. That is one of the reasons they
> are trying to go to LEDs, because they loose brighness
> very slowly.

Just if it was unclear: The phosphorous stuff is in the
backlight in the case (pun intended) of an LCD.

Arno

"Al Dykes" <> 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.


(*>

In message <>, Hawk
<> writes
>
>"Al Dykes" <> 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?

--
Jeremy Boden

Previously Jeremy Boden <> wrote:
> In message <>, Hawk
> <> writes
>>
>>"Al Dykes" <> 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.

Arno

In message <>, Arno Wagner
<> writes
>Previously Jeremy Boden <> wrote:
>> In message <>, Hawk
>> <> writes
>>>
>>>"Al Dykes" <> 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!!!
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.

I think I will wait a few years before getting one of these flat panel
gizmos.

--
Jeremy Boden

"Jeremy Boden" wrote:

>>20'000 hour with 90% means that after 20'000 hours 90% are
>>still working.
>
> 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.
>
> I think I will wait a few years before getting one of these flat panel gizmos.
>

You'd have a 90% chance of having it last 11 years @ 5 hours of use per day. How
many of us will be sticking with the same monitor for 10 years? Besides, that
rating is just for the backlight (which can be replaced). I don't have the figure
offhand, but I'm sure the MTBF for the monitor (minus backlight) is a heck of a
lot longer.

I'm pretty confident that I'll be lured to a new display technology before my
current lcd's give it up.


(*>