CRT

Farabi · November 05, 2011, 03:05:39 AM

http://en.wikipedia.org/wiki/Cathode_ray_tube

Sounded like I asked this before, but I forget. So, where did the electron gone after we shot it to the phosphor layer? And how long the phosphor layer could stand? My Sony TV is 10 years old before I replaced it with LCD one. Is phosphor used to be last that long?

Also about analog signal, I saw that for example, we use 100 Mhz as a base frequency, 100.1 for 1 signal, 100.2 for 2 signal etc. And on digital, 100 for 0 and 101 is for 1, is what I get was right?

vanjast · November 09, 2011, 12:00:12 PM

Quote from: Farabi on November 05, 2011, 03:05:39 AM
So, where did the electron gone after we shot it to the phosphor layer?

The phosphor screen is part of the High Voltage electrical circuit, so the electron or other electron exits the screen into the rest of the circuit - That HT (high voltage) lead that plugs into the side of the tube. The other end of the HT circuit is the electron-gun buried in the thin portion of the tube.

Yup.. Phosphor lasted for eternity compared to LED/LCD.. I'm not sure of the TFT guarantee time lately, but I think it's still only 2 years

Quote from: Farabi on November 05, 2011, 03:05:39 AM
Also about analog signal, I saw that for example, we use 100 Mhz as a base frequency, 100.1 for 1 signal, 100.2 for 2 signal etc. And on digital, 100 for 0 and 101 is for 1, is what I get was right?

On the tube itself, it's about synchronised signals.. The same idea exist with digital television, but if you're talking about radio signals check this lot out...

http://en.wikipedia.org/wiki/Broadcast_television_system
http://en.wikipedia.org/wiki/Television_encoding

clive · November 09, 2011, 12:48:11 PM

TV's lasting 20-30 years is not unheard of, but that's for ones built with quality/care, I'd be surprised if the ones built today will run that long.

Usually the power supply or drive circuits fail, not the CRT. The phosphors fade over time, but the real issues with image burn in is with the single colour displays (like ATM machines) where the same image is on for years.

A lot of older displays have be obsoleted by changing video standards which haven't changed in 30 years, the last I remember was the transition from Black&White to Colour, or 525(?) to 625 lines (PAL)

dedndave · November 09, 2011, 03:39:21 PM

QuoteThe phosphor screen is part of the High Voltage electrical circuit, so the electron or other electron exits the screen into the rest of the circuit - That HT (high voltage) lead that plugs into the side of the tube. The other end of the HT circuit is the electron-gun buried in the thin portion of the tube.

nah - it just keeps going - shoots right out at ya :bdg

as for CRT's failing, Clive is right - something else will probably fail before the CRT does
when they do fail, they will probably develop small leaks and become "gaseous" - making for a fuzzy or blurry picture
the phospher generally stays good for longer than the life of the tube

vanjast · November 14, 2011, 10:05:06 PM

Quote from: dedndave on November 09, 2011, 03:39:21 PM
nah - it just keeps going - shoots right out at ya :bdg

You're actually correct here.. Has anybody noticed dark rings around the eyes of CRT users compared to TFT (led) screens.
When I switched my eyes immediately stopped feeling so 'tired'... CRT's buggered up your eyes.

dedndave · November 14, 2011, 10:08:37 PM

:P

well - you had it right, the first time
the electrons do complete the path of the circuit
however, there is considerable electro-magnetic radiation from a CRT
as well as a high voltage "field" - electrons trying very hard to find a path :P

vanjast · November 15, 2011, 05:08:07 AM

I'm thinking about the photon bombardment and other particles... :8)

dedndave · November 15, 2011, 12:52:07 PM

photons - of course
we get that from an LCD :P

MichaelW · November 15, 2011, 07:30:07 PM

I think it was the photon/electron bombardment from CRTs that turned my hair gray. I'm gonna sue.

dedndave · November 15, 2011, 08:58:53 PM

nahhhhhh - lol
photon is just another word for "visible light"

most men go grey because of most women
kids are no help, either

Farabi · November 23, 2011, 01:08:13 PM

VHS can play a good quality movie for 2 hours, or maybe Im too young to see the jitter. But a CD is only for half an hour. We should make the analog for the digital system, 1 dot for 1 bit is wasting too much space. We should make 1 dot depth as 8 carbon electron, so each dot is 1 byte. See?? We had 8xtimes space for only a CD. And with current blue ray tech?? Hahahahaha. I can record my daily life for 24 hours, and it will only cost 50 cent per day. Come on, mass produce it. And make the Writer hardware cheap, 40 bucks for the writer is affordable for me. :cheekygreen: Hell yeah.

Anyone from japan and china here? Western life cost is too high because of the currency, the only alternative is Israel. But, will they did it?

Bit 1 is ionized
Bit 0 is normal carbon.

dedndave · November 23, 2011, 03:42:26 PM

using x-Vid compression, you can get an entire movie onto a CD
it isn't "excellent" quality, but it's quite good
at about 1.4 Gb, you get what i would call "nearly excellent" :P

Farabi · November 24, 2011, 11:20:08 AM

Quote from: dedndave on November 23, 2011, 03:42:26 PM
using x-Vid compression, you can get an entire movie onto a CD
it isn't "excellent" quality, but it's quite good
at about 1.4 Gb, you get what i would call "nearly excellent" :P

If they really maked it come true, I'll die from heart attack :green

dedndave · November 24, 2011, 11:54:55 AM

http://fr33sp33k.h33t.com/index.php?topic=2573.0

Farabi · November 24, 2011, 12:00:30 PM

No, I mean, the ionized and normal carbon one. But I guess it could be feasible. I also thought about reading the whole disk using a Scanning Electron Microscope. It will make the reading fasters, a lot more more more fasters. With an optics as wide as the CD wide and a SEM read, we can read the wholde CD sectors on one shot.

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