gray vs dark gray CRT screen

[Dreamsbeard]

Somewhere in the mid 80's company all seemed to switch from light gray CRT screen to dark gray ones. Was there any advantage in picture quality behind this decision? Was it a difference in how the shadow mask where made?

Thanks!

[Jon A.]

I think it was an anti-glare measure.

A 1986 Hitachi console I had very briefly had a removable pane of tinted glass in front of the screen.

[Dreamsbeard]

Hummm, and I was sitting here expecting a mind shatering advance in technology...haha!

And to say that my plasma tv is literrally like a mirror...it's like technology is going backward! It has amazing picture quality in the dark, but when the sun shines in...well its another story. Still better than LCD or LED if you ask me.

[Jon A.]

You have a plasma TV? That's mind-shattering to me, ha.

[old_tv_nut]

It's just a matter of trading some brightness for better contrast. The light coming from the phosphor gets attenuated once, but light from the room gets attenuated once going in and again reflecting back out.

[Dreamsbeard]

Originally Posted by Jon A.

You have a plasma TV? That's mind-shattering to me, ha.

Well, my blu-ray don't look quite as impressive on my 1979 19'' Hitachi

[Dreamsbeard]

Originally Posted by old_tv_nut

It's just a matter of trading some brightness for better contrast. The light coming from the phosphor gets attenuated once, but light from the room gets attenuated once going in and again reflecting back out.

So it does gives a better picture! Brightness is good, but trading a bit of that for contrast must give the picture a better look. It has been my experience that TV are often too bright for optimal viewing anyway.

[Jon A.]

Originally Posted by Dreamsbeard

Well, my blu-ray don't look quite as impressive on my 1979 19'' Hitachi

Of course not, you need a 25" set for that.

I just like to pretend that a lot of newer technology doesn't exist. It's been working well for me so far.

[Username1]

I think it's for daytime contrast. I got a few older tv's where the screen almost looks
like it's off white by just a little.... And compare that to my 2000 Sanyo, for example,
sitting here in a really well lit living room, the Sanyo screen is dark.. really dark...

.

[jr_tech]

old_tv_nut nailed it in the above post:

Originally Posted by old_tv_nut

It's just a matter of trading some brightness for better contrast. The light coming from the phosphor gets attenuated once, but light from the room gets attenuated once going in and again reflecting back out.

Room light reflected from the CRT phosphor surface gets attenuated twice a much as light produced by the phosphor hence contrast enhancement. I suspect that there is also a trade off with tube life, as beam current might be turned up a bit to compensate for the brightness loss.
Another enhancement can be achieved by depositing an anti-reflection coating on the *front* surface of the CRT to reduce the approximately 4% reflection of room light from that surface... I don't recall seeing a consumer TV with CRT AR coating, but perhaps it was used on some high end models.

jr

[timberstx]

Sylvania had them earlier in the 70's I think. They had the commercials saying best color picture, Better than zenith and rca. You can find them on youtube. I personally like the lighter tube better. When I was a kid my mom got a 79 Magnavox videomatic, still with the old type channel knobs. Had a black matrix inline picture tube, but still the lighter tube. A year later my grandmother got the sylvania superset II. The sylvania had a wow factor because of the dark tube. But in my opinion the magnavox had a more realistic everyday viewing. When adjusted right the dark areas of the screen still showed black, in a light or dark room.
My first set was the 1992 Panasonic super black super flat gaoo system ( I think this is what they called it). Nice set, and had a nice picture. But to get the dark areas black the faces would be too dark. Lighting the faces up enough for good viewing the dark areas were no longer completely black like in the old set. So even though it had the dark picture tube, it still did not compare to the sets made in the 70's.
Also my sister had a early 70's zenith 19". Lighter tube, but still better than any of the later dark picture tubes.
My post is just my opinion.

[sampson159]

sylvanias 25vdmp22 was considered the best looking crt back in the 70s.they produced the absolute best picture but they didnt last long.3-5 years and they were gone.their earlier 25vamp22 crts seemed to last forever.these are delta guns.the ultimate set would be a flat chassis zenith with the sylvania dark matrix crt.the zenith chromacolors were the first black matrix picture tubes.

[Kamakiri]

Originally Posted by jr_tech

old_tv_nut nailed it in the above post:



Room light reflected from the CRT phosphor surface gets attenuated twice a much as light produced by the phosphor hence contrast enhancement. I suspect that there is also a trade off with tube life, as beam current might be turned up a bit to compensate for the brightness loss.
Another enhancement can be achieved by depositing an anti-reflection coating on the *front* surface of the CRT to reduce the approximately 4% reflection of room light from that surface... I don't recall seeing a consumer TV with CRT AR coating, but perhaps it was used on some high end models.

jr

Interesting, I always wondered about this!

[Dreamsbeard]

Originally Posted by jr_tech

old_tv_nut nailed it in the above post:



Room light reflected from the CRT phosphor surface gets attenuated twice a much as light produced by the phosphor hence contrast enhancement. I suspect that there is also a trade off with tube life, as beam current might be turned up a bit to compensate for the brightness loss.
Another enhancement can be achieved by depositing an anti-reflection coating on the *front* surface of the CRT to reduce the approximately 4% reflection of room light from that surface... I don't recall seeing a consumer TV with CRT AR coating, but perhaps it was used on some high end models.

jr

Very interesting, thank you for the information. So I guess this only helps in a bright lit room, and doesnt really change anything while watching the TV at night.