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CRT "Burn-in"  
User currently offlineKPIE172 From United States of America, joined Nov 2006, 20 posts, RR: 0
Posted (6 years 12 months 3 days 18 hours ago) and read 3427 times:

Unless I am mistaken the picture below appears to show the FO's and center screens having what I've known as "burn-in"...? As a pilot is it distracting during daylight hours? What is the fix, just replacing? I know LCD's do not have this problem, so why not replace the crt's with newer lcd's of the same dimensions?


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21 replies: All unread, jump to last
 
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (6 years 12 months 3 days 5 hours ago) and read 3308 times:

Quoting KPIE172 (Thread starter):
Unless I am mistaken the picture below appears to show the FO's and center screens having what I've known as "burn-in"...?

That's certainly what it looks like.

Quoting KPIE172 (Thread starter):
What is the fix, just replacing?

Yes.

Quoting KPIE172 (Thread starter):
I know LCD's do not have this problem, so why not replace the crt's with newer lcd's of the same dimensions?

Boeing doesn't have any LCD's certified for the 757 flight deck, as far as I know. There are third parties who have STC's to do this though. I doubt it's a cheap modification.

Tom.


User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2543 posts, RR: 24
Reply 2, posted (6 years 12 months 3 days 2 hours ago) and read 3280 times:

When the CRT is operating burn-in would not be so noticeable. Replacement is the only answer.

Quoting Tdscanuck (Reply 1):
Boeing doesn't have any LCD's certified for the 757 flight deck, as far as I know. There are third parties who have STC's to do this though.

The one I've seen involves a complete panel replacement (full glass cockpit), rather than a direct LCD for CRT replacement. I don't suppose it comes cheap, but that is probably offset by reduced maintenance costs long term.

Even a straight LCD for CRT replacement would have to be certified, so with no additional benefit might not be cost effective.

CRT burn-in looks ugly with the CRT off, but when it is on it is nowhere near so obvious. Unless they have already changed the EADI's in the picture you can see both are on and neither looks abnormal. The lower EICAS is usually off in flight, so wouldn't look too good of course.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 3, posted (6 years 12 months 3 days ago) and read 3246 times:

Quoting KPIE172 (Thread starter):
Unless I am mistaken the picture below appears to show the FO's and center screens having what I've known as "burn-in"...?

That is not 'burn-in'..... he just has the brightness level turned way down



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2543 posts, RR: 24
Reply 4, posted (6 years 12 months 2 days 22 hours ago) and read 3226 times:

Quoting EMBQA (Reply 3):
That is not 'burn-in'..... he just has the brightness level turned way down

The F/O EADI is on low, but the EHSI looks like it is off. Being low brightness wouldn't make the display appear negative like that, would it?



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 5, posted (6 years 12 months 2 days 22 hours ago) and read 3226 times:

Quoting Jetlagged (Reply 4):
Being low brightness wouldn't make the display appear negative like that, would it?

After I took a second look at it.. you might be right.



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineMoo From Falkland Islands, joined May 2007, 3874 posts, RR: 5
Reply 6, posted (6 years 12 months 2 days 20 hours ago) and read 3171 times:

Quoting KPIE172 (Thread starter):
I know LCD's do not have this problem, so why not replace the crt's with newer lcd's of the same dimensions?

Theres no particular reason why LCDs and TFTs can't have the problem, and indeed we have a few at work that have burn in - it works differently, but it has the same effect.


User currently offlineModesto2 From United States of America, joined Jul 2000, 2789 posts, RR: 5
Reply 7, posted (6 years 12 months 2 days 19 hours ago) and read 3154 times:

I've seen "burn-in" on the RMU's in the E145's we fly. It's somewhat annoying but not that bad, and I'm certainly not expecting the company to change the displays anytime soon.

User currently offlineLincoln From United States of America, joined Nov 2004, 3887 posts, RR: 8
Reply 8, posted (6 years 11 months 3 weeks 6 days 9 hours ago) and read 2910 times:

Just remember that burn in occurs because the same image is displayed for an extended period of time (and/or at very high brightness settings), thus we can presume that that this is the "normal" display for those monitors and that the burned-in image won't be distracting the majority of the time because that's what's on the screen anyway (or something like that).

Quoting Moo (Reply 6):
Theres no particular reason why LCDs and TFTs can't have the problem, and indeed we have a few at work that have burn in - it works differently, but it has the same effect.

Ditto that! In litterally hundreds of LCD displays I've stared at I've seen burn-in like symptoms on maybe 3. On one of them it just kind of disappered over time...not really sure what happened to the other two.

Lincoln



CO Is My Airline of Choice || Baggage Claim is an airline's last chance to disappoint a customer || Next flts in profile
User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 9, posted (6 years 11 months 3 weeks 6 days 4 hours ago) and read 2867 times:

Quoting Moo (Reply 6):

Theres no particular reason why LCDs and TFTs can't have the problem, and indeed we have a few at work that have burn in - it works differently, but it has the same effect.

LCDs can have image persistance, not burn in. It can be cured easily (display a solid block of colour for a while, or rotate through the colour range), whilst burn in can't be cured economically.


User currently offlineKlaus From Germany, joined Jul 2001, 21411 posts, RR: 54
Reply 10, posted (6 years 11 months 3 weeks 6 days 3 hours ago) and read 2852 times:

Quoting Moo (Reply 6):
Theres no particular reason why LCDs and TFTs can't have the problem, and indeed we have a few at work that have burn in - it works differently, but it has the same effect.

CRT burn-in is a local and irreversible degradation of the fluorescent layer. Since LCD don't have such a layer at all and are working completely differently, they can't experience the same effect.

As said above LCDs can show "ghost images" for a while when changing between contrasting images, but those will vanish on their own again.

Degradation with an LCD primarily affects the separate backlight through gradual loss of maximum brightness, but those can usually be replaced at reasonable cost while the CRT would have to be replaced completely, quite possibly with its deflection circuits as well and usually followed by nontrivial re-calibration, especially when colour CRTs are concerned.


User currently offlineGoldenshield From United States of America, joined Jan 2001, 5970 posts, RR: 14
Reply 11, posted (6 years 11 months 3 weeks 6 days 2 hours ago) and read 2846 times:

Quoting Klaus (Reply 10):
CRT burn-in is a local and irreversible degradation of the fluorescent layer. Since LCD don't have such a layer at all and are working completely differently, they can't experience the same effect.

Oh my. Klaus posting outside of the non-an forum, and not discussing Macs? Alright, who are you, and what have you done with Klaus!



Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineKlaus From Germany, joined Jul 2001, 21411 posts, RR: 54
Reply 12, posted (6 years 11 months 3 weeks 6 days 2 hours ago) and read 2838 times:

Quoting Goldenshield (Reply 11):
Oh my. Klaus posting outside of the non-an forum, and not discussing Macs? Alright, who are you, and what have you done with Klaus!

We're getting a bit off-topic, aren't we?  mischievous 

Tech/Ops is by far the most interesting aviation forum for me around here; I just didn't have the time to follow it much in recent months...

But I appreciate the enthusiastic welcome, of course! Big grin


User currently offlineNoWorries From United States of America, joined Oct 2006, 539 posts, RR: 1
Reply 13, posted (6 years 11 months 3 weeks 5 days 16 hours ago) and read 2766 times:

As noted above, the liquid crystals in an LCD are not light emitters, just "valves". Each pixel typically has four segments arranged in a square, two with green coatings, one with a blue, and one with a red. The crystals change their twist (and ability to pass light) when a voltage is applied. Some displays use crystals that are twisted "shut" when unpowered and when a voltage is applied, they twist open. Others are twisted "open" when unpowered and when a voltage is applied, they twist shut. Not sure which type is more prevalent. The degree to which the crystals open or shut depends on the voltage applied (and in this sense an LCD is very much an analog device). If a group of crystals has maximum voltage applied for an extended period, they can fatigue and lose their ability to fully recover. In extreme cases the damage can be permanent.

User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 14, posted (6 years 11 months 3 weeks 5 days 1 hour ago) and read 2664 times:

I am surprised to see the ERJ uses CRTs. The benefits of LCDs outweigh CRTs, lighter, cooler-running, and much less power consumption, and being a younger aircraft, I sure would have thought the LCD would be a better option.

Quoting Goldenshield (Reply 11):
Oh my. Klaus posting outside of the non-an forum, and not discussing Macs? Alright, who are you, and what have you done with Klaus!



Quoting Klaus (Reply 12):

Agreed...Klaus has posted much in Tech/Ops lately. I guess I'll have to start a Leopard vs. Vista debate in Non-Av and keep him busy  wink 


User currently offlineKlaus From Germany, joined Jul 2001, 21411 posts, RR: 54
Reply 15, posted (6 years 11 months 3 weeks 3 days 22 hours ago) and read 2582 times:

Quoting NoWorries (Reply 13):
Each pixel typically has four segments arranged in a square, two with green coatings, one with a blue, and one with a red.

I can't say for sure that such an arrangement didn't exist anywhere, but normally there are only three colour-sub-pixels of equal size. LED-based displays sometimes use more than one LED for a given colour to compensate for colour-specific performance deficits. But I've not seen that in LCDs so far where the colours are realized by semitransparent filters in front of three monochrome LCD shutters. And given that the filters are of comparable quality there isn't a reason for it.

Quoting N231YE (Reply 14):
Klaus has posted much in Tech/Ops lately. I guess I'll have to start a Leopard vs. Vista debate in Non-Av and keep him busy

You'll manage.  cool 


User currently offlineNoWorries From United States of America, joined Oct 2006, 539 posts, RR: 1
Reply 16, posted (6 years 11 months 3 weeks 3 days 20 hours ago) and read 2567 times:

Quoting Klaus (Reply 15):
I can't say for sure that such an arrangement didn't exist anywhere, but normally there are only three colour-sub-pixels of equal size.

Yep, thanks. Halfway through I must've forgot I was writing about displays and thought I was writing about cameras. One common CCD arrangement with lower cost cameras is four cells per pixel (two grreens, one red and one blue).


User currently offlineKlaus From Germany, joined Jul 2001, 21411 posts, RR: 54
Reply 17, posted (6 years 11 months 3 weeks 3 days 19 hours ago) and read 2543 times:

Quoting NoWorries (Reply 16):
Halfway through I must've forgot I was writing about displays and thought I was writing about cameras. One common CCD arrangement with lower cost cameras is four cells per pixel (two grreens, one red and one blue).

Ah, okay. That's quite possible... in a camera the pixel area relates to its susceptibility for noise as well, so it could well be in order to dampen the noise in the colour which the eye reacts the most to.

It is also one reason why "many megapixels" can be a bad criterion to choose a camera by if they are squeezed into the same physical area...

[Edited 2007-08-10 21:01:54]

User currently offlineZenarcade From Canada, joined Nov 2006, 85 posts, RR: 0
Reply 18, posted (6 years 11 months 3 weeks 3 days 10 hours ago) and read 2483 times:

Quoting Lincoln (Reply 8):
hus we can presume that that this is the "normal" display for those monitors and that the burned-in image won't be distracting the majority of the time because that's what's on the screen anyway (or something like that).

Well said!

Which aircraft was the first to have LCD panels? 777? 717?



If a plane falls on the tarmac and no one is there, does it make any sound? - Starlionblue
User currently offlineN231YE From , joined Dec 1969, posts, RR:
Reply 19, posted (6 years 11 months 3 weeks 2 days 21 hours ago) and read 2450 times:

Quoting Zenarcade (Reply 18):
Which aircraft was the first to have LCD panels? 777? 717?

I believe it was the 777.


User currently offlineAJ From Australia, joined Nov 1999, 2386 posts, RR: 24
Reply 20, posted (6 years 11 months 3 weeks 1 day 15 hours ago) and read 2366 times:

On the 767 (so presumably the 757) the EICAS and EHSI screens are interchangeable so occasionally slightly burned engine gauges are visible sideways on the EHSI. Our company policy is to turn down all EFIS screens whenever conducting the secure checklist to minimise CRT damage. Whilst our 747-400s are getting LCD screens the 767 is not.

User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 21, posted (6 years 11 months 3 weeks 1 day 7 hours ago) and read 2329 times:

Quoting AJ (Reply 20):
On the 767 (so presumably the 757) the EICAS and EHSI screens are interchangeable so occasionally slightly burned engine gauges are visible sideways on the EHSI. Our company policy is to turn down all EFIS screens whenever conducting the secure checklist to minimise CRT damage

True.The B757s EICAS & EHSI crt screens are interchangable.Company SOP is to reduce Brightness when not needed.
regds
MEL



Think of the brighter side!
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