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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Tue Jan 04, 2011 4:48 pm Post subject: Simple tube question |
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I am learning to my exam which will be on thursday, the subject called "infcommunication" about sound, vision, broadcasting and telephony.
What I've learned:
1.)the human eye is most sensitive for the green color (~555nm wave-length)
2.)the component luminosity signal came from 0,3R+0,59G+0,11B
My questions:
Why are the crt tubes worn out in G-B-R order, and why need to drive the green(tube) so hard when our eyes are the most sensitive for the green?
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Tue Jan 04, 2011 4:50 pm Post subject: |
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Actually I'd say the blue wears faster than the green.
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CRT.
HD done right!
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Jan 04, 2011 5:04 pm Post subject: Re: Simple tube question |
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| gjaky wrote: | | Why are the crt tubes worn out in G-B-R order, and why need to drive the green(tube) so hard when our eyes are the most sensitive for the green? |
to make full White 100IRE, your running green at 100% output, blue at roughly 50%, and red at around 20%. I also believe the majority of other colors require more green than B/R.
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virusc
Joined: 11 Apr 2007
Posts: 358
Location: Massachusetts
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| Posted: Tue Jan 04, 2011 5:16 pm Post subject: |
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blues only wear faster on ES older projectors. Also, the phosphors themselves have different efficiencies and wearing properties I believe so it is not fair to compare them as equal. Green also often has much tighter focus as blue is purposely defocused a little and not as sharp anyway so this adds the the wear of green vs. blue
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Tue Jan 04, 2011 10:43 pm Post subject: |
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Ahhh I've owned 5 ES sets. Hence my observation.
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Thu Jan 06, 2011 2:53 pm Post subject: |
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I've seen my fair share of projectors with a lot of tube wear. Green usually does wear out first, except in the case of projectors which are connected to a PC for a major portion of their lives. Then, blue wears out fastest as most Windows backgrounds are blue.
As for the drive levels, eventually that all comes down to the efficiency of the phosphor. Red, blue, and green phosphors are not
created equal. We're just lucky that there are usable phosphors, and even luckier that there are compatible phosphor triads which
require generally similar drive levels. Otherwise, the full color direct view CRT would have never been possible.
CJ
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