Polymer LED display issue
in [Design]
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From: Gavin Melville on 22 Aug 2005 21:25 Hi, I have an application that just suits a Polymer LED display perfectly. I can get a 2 line 16 char display (such as a Delta PDC1602M), and all looks good (power consumption, life, interface etc) The only problem is that buried in the specs is the line that says "Do not hold the same display picture over 1 min, because they will cause none uniformity in the display screen." Ignoring the bad english, I think this is some kind of burn in phenomonon. Other makers mention a "differential burn in" issue, but put no time limit on it, however most manufacturers do not even mention this. Trying it, so far, has produced no observable effects. I can see it would be easy to solve this on a graphics display, but much harder on a text display that never has quite enough characters anyway. A web search has not prodiced any real useful info -- does anyone have any real experience with PLED displays and this issue in particular ? TIA, -- Regards, Gavin Melville gavin.melville(a)acclipse.co.nz
From: Ian Stirling on 23 Aug 2005 08:34 Gavin Melville <gavin.melville(a)acclipse.co.nz> wrote: > Hi, > > I have an application that just suits a Polymer LED display perfectly. > I can get a 2 line 16 char display (such as a Delta PDC1602M), and all > looks good (power consumption, life, interface etc) > > The only problem is that buried in the specs is the line that says "Do > not hold the same display picture over 1 min, because they will cause > none uniformity in the display screen." > > Ignoring the bad english, I think this is some kind of burn in > phenomonon. Other makers mention a "differential burn in" issue, but > put no time limit on it, however most manufacturers do not even > mention this. 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
From: Spehro Pefhany on 23 Aug 2005 12:17 On 23 Aug 2005 12:34:22 GMT, the renowned Ian Stirling <root(a)mauve.demon.co.uk> wrote: >Gavin Melville <gavin.melville(a)acclipse.co.nz> wrote: >> Hi, >> >> I have an application that just suits a Polymer LED display perfectly. >> I can get a 2 line 16 char display (such as a Delta PDC1602M), and all >> looks good (power consumption, life, interface etc) >> >> The only problem is that buried in the specs is the line that says "Do >> not hold the same display picture over 1 min, because they will cause >> none uniformity in the display screen." >> >> Ignoring the bad english, I think this is some kind of burn in >> phenomonon. Other makers mention a "differential burn in" issue, but >> put no time limit on it, however most manufacturers do not even >> mention this. > >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. 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: Ian Stirling on 23 Aug 2005 14:05 Spehro Pefhany <speffSNIP(a)interlogdotyou.knowwhat> wrote: > On 23 Aug 2005 12:34:22 GMT, the renowned Ian Stirling > <root(a)mauve.demon.co.uk> wrote: > >>Gavin Melville <gavin.melville(a)acclipse.co.nz> wrote: >>> Hi, >>> >>> I have an application that just suits a Polymer LED display perfectly. >>> I can get a 2 line 16 char display (such as a Delta PDC1602M), and all >>> looks good (power consumption, life, interface etc) >>> >>> The only problem is that buried in the specs is the line that says "Do >>> not hold the same display picture over 1 min, because they will cause >>> none uniformity in the display screen." >>> >>> Ignoring the bad english, I think this is some kind of burn in >>> phenomonon. Other makers mention a "differential burn in" issue, but >>> put no time limit on it, however most manufacturers do not even >>> mention this. >> >>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.
From: Spehro Pefhany on 23 Aug 2005 15:44 On 23 Aug 2005 18:05:31 GMT, the renowned Ian Stirling <root(a)mauve.demon.co.uk> wrote: >Spehro Pefhany <speffSNIP(a)interlogdotyou.knowwhat> wrote: >> On 23 Aug 2005 12:34:22 GMT, the renowned Ian Stirling >> <root(a)mauve.demon.co.uk> wrote: >> >>>Gavin Melville <gavin.melville(a)acclipse.co.nz> wrote: >>>> Hi, >>>> >>>> I have an application that just suits a Polymer LED display perfectly. >>>> I can get a 2 line 16 char display (such as a Delta PDC1602M), and all >>>> looks good (power consumption, life, interface etc) >>>> >>>> The only problem is that buried in the specs is the line that says "Do >>>> not hold the same display picture over 1 min, because they will cause >>>> none uniformity in the display screen." >>>> >>>> Ignoring the bad english, I think this is some kind of burn in >>>> phenomonon. Other makers mention a "differential burn in" issue, but >>>> put no time limit on it, however most manufacturers do not even >>>> mention this. >>> >>>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. 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
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