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From: Gavin Melville on 23 Aug 2005 23:40

>>>>I think it's poorly stated.
>>>>All OLEDs will decay due to use, being at (for eaxample) 50% light output
>>>>at 5000 hours illuminated.
>>>>After 5000 hours, if pixel A is always on, and pixel B is never on,
>>>>then when you want to light A and B, A will be 50% dimmer than B.
>>>>
>>>>You need to think about this when designing displays, or live with the
>>>>fact that they will look blotchy.
>>>>light A and B together, you'll notice
>>>
>>> The OLED/PLED degradation is apparently greatly accelerated by high
>>> temperatures.
>>
>>That too.
>>I think the pixels'd be more or less isothermal though.
>
>Sure, but for a given set of display patterns, the difference in
>brightness of pixels due to burn-in should increase much more quickly
>(in relation to the expected life of product) at high temperatures.

I expect this to occur, but Delta indicate that it occurs over 1
minute, not 5000 hours, which in this use would be years.
--
Regards,
Gavin Melville
gavin.melville(a)acclipse.co.nz
From: Spehro Pefhany on 24 Aug 2005 00:36
On Wed, 24 Aug 2005 15:40:02 +1200, the renowned Gavin Melville
<gavin.melville(a)acclipse.co.nz> wrote:

>
>>>>>I think it's poorly stated.
>>>>>All OLEDs will decay due to use, being at (for eaxample) 50% light output
>>>>>at 5000 hours illuminated.
>>>>>After 5000 hours, if pixel A is always on, and pixel B is never on,
>>>>>then when you want to light A and B, A will be 50% dimmer than B.
>>>>>
>>>>>You need to think about this when designing displays, or live with the
>>>>>fact that they will look blotchy.
>>>>>light A and B together, you'll notice
>>>>
>>>> The OLED/PLED degradation is apparently greatly accelerated by high
>>>> temperatures.
>>>
>>>That too.
>>>I think the pixels'd be more or less isothermal though.
>>
>>Sure, but for a given set of display patterns, the difference in
>>brightness of pixels due to burn-in should increase much more quickly
>>(in relation to the expected life of product) at high temperatures.
>
>I expect this to occur, but Delta indicate that it occurs over 1
>minute, not 5000 hours, which in this use would be years.

The application note that I have says "a long time" not "1 minute",
which I would interpret as many hours (probably > 100 or >500). It
also says that the effect of temperature < 50ýC on life is small. They
do go on at some length about automatically blanking the display,
scrolling or doing other annoying things.

What's the document number of what you are looking at?


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff(a)interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
From: Gavin Melville on 24 Aug 2005 18:06
Hi Spehro,

http://www.delta-opto.com.tw/english/products/default.htm , click on
PDC1602M (a pdf file). Last page (22) , 15.4 says "(4) Do not hold
the same display picture over 1 min, because they will cause none
uniformity in the display screen."

Several other datasheets from Delta have similar warnings.

I have not found many other displays with reasonable power consumption
-- I can use either 16x2 text or 128 x 64 graphics.

On Wed, 24 Aug 2005 00:36:50 -0400, Spehro Pefhany
<speffSNIP(a)interlogDOTyou.knowwhat> wrote:

>On Wed, 24 Aug 2005 15:40:02 +1200, the renowned Gavin Melville
><gavin.melville(a)acclipse.co.nz> wrote:
>
>>
>>>>>>I think it's poorly stated.
>>>>>>All OLEDs will decay due to use, being at (for eaxample) 50% light output
>>>>>>at 5000 hours illuminated.
>>>>>>After 5000 hours, if pixel A is always on, and pixel B is never on,
>>>>>>then when you want to light A and B, A will be 50% dimmer than B.
>>>>>>
>>>>>>You need to think about this when designing displays, or live with the
>>>>>>fact that they will look blotchy.
>>>>>>light A and B together, you'll notice
>>>>>
>>>>> The OLED/PLED degradation is apparently greatly accelerated by high
>>>>> temperatures.
>>>>
>>>>That too.
>>>>I think the pixels'd be more or less isothermal though.
>>>
>>>Sure, but for a given set of display patterns, the difference in
>>>brightness of pixels due to burn-in should increase much more quickly
>>>(in relation to the expected life of product) at high temperatures.
>>
>>I expect this to occur, but Delta indicate that it occurs over 1
>>minute, not 5000 hours, which in this use would be years.
>
>The application note that I have says "a long time" not "1 minute",
>which I would interpret as many hours (probably > 100 or >500). It
>also says that the effect of temperature < 50ýC on life is small. They
>do go on at some length about automatically blanking the display,
>scrolling or doing other annoying things.
>
>What's the document number of what you are looking at?
>
>
>Best regards,
>Spehro Pefhany

--
Regards,
Gavin Melville
gavin.melville(a)acclipse.co.nz
From: Spehro Pefhany on 24 Aug 2005 19:23
On Thu, 25 Aug 2005 10:06:06 +1200, the renowned Gavin Melville
<gavin.melville(a)acclipse.co.nz> wrote:

>Hi Spehro,
>
<snip>

Thanks for the link. I see what you mean. Life appears to be 5,000
hours to 50%, since it's measured with 50% duty cycle. Still looks
like it should be hundreds of hours to see a visible difference.

Have you talked to the office in Taiwan? (they'll probably refer it
back to the dudes in FL, but it can't hurt)


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff(a)interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
From: gavin.melville on 27 Aug 2005 06:35
Spehro Pefhany wrote:
> Thanks for the link. I see what you mean. Life appears to be 5,000
> hours to 50%, since it's measured with 50% duty cycle. Still looks
> like it should be hundreds of hours to see a visible difference.
>
> Have you talked to the office in Taiwan? (they'll probably refer it
> back to the dudes in FL, but it can't hurt)

The reply from Taiwan was a bit of a stunner.

"Due to the display uniformity in the display screen , we advise our
customer that don't hold the same display picture over 1 min.

Display skills :
1. Try to scrolling the pattern after 1 min. then return to the
original pattern
2. After 1 min. turn off the pattern , when you want to see the
pattern , try to contact some key button to start the pattern"

Back to the search for low power display, and don't go near Delta.......

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