What was the purpose of.....

[grimer]

What was the purpose of putting plastic filters in front of a B&W crt?
I have an Emerson(pictured) with a blue filter,and a 721 with a really
dark filter.Both sets are on the ever growing "to-do" list,so I have not been
able to see for myself

[David Roper]

Apparently the dark filters were intended to improve contrast. Just An odd tint was probably more gimmick than anything else.

[Red Raster]

It sounds like a sales gimmick using big buzz words, my Mitsubishi tv has a blue optic picture tube and the best one i heard from a stereo salesman was " Alpine car audio amps are better because they have bi-polar transistors"

[Reece]

In the fifties they sold plastic "colorizing" filters to stick on your B&W TV. There were color bands, at the top sky blue, farther down blending into pink, I think, and finally blending into green at the bottom. You were supposed to think you were watching color TV. Ha. You weren't.

[MelodyMaster]

Are you talking about add-on filters, or the leaded safety glass that was needed to protect the viewer from the high levels of Xrays given off by 1950s CRT's?

[bgadow]

Aside from projection sets and some early color tubes, leaded glass wouldn't be needed. I hadn't seen a blue glass before-sounds like a sales gimmick to me, like the Hoffman green glass. I had an RCA from the later 50s with a purple tinge around the edges and I think Zenith did the same thing on some models. Something to set one brand apart from the others. Then as now, most stores seemed to sell more than one brand, so I guess any little thing would help. "Hey Marge, check out this Halolite!" "Not now, Len, I really like this set with the swivel base..."

[electronjohn]

Of course there's always the plastic film you'd stick to the screen so you could draw a bridge for Winky Dink to get over the canyon.

[Sandy G]

Sound like Personal Experience there, John...Pray enlighten us further ?!? (grin)

[leadlike]

My Dad still has his original Winky Dink set. Although he used to draw a pit filled with spikes instead of a bridge for Winky to cross.

[MelodyMaster]

Originally Posted by bgadow

Aside from projection sets and some early color tubes, leaded glass wouldn't be needed. I hadn't seen a blue glass before-sounds like a sales gimmick to me, like the Hoffman green glass. I had an RCA from the later 50s with a purple tinge around the edges and I think Zenith did the same thing on some models. Something to set one brand apart from the others. Then as now, most stores seemed to sell more than one brand, so I guess any little thing would help. "Hey Marge, check out this Halolite!" "Not now, Len, I really like this set with the swivel base..."

I was working on 1950s TVs in the 1960s... Where did you hear that misinformation? All 1950s TVs I've ever seen had leaded safety glass - no exceptions other than some early sets where I guess they didn't realize the risks. It was required by UL and CSA. If a TV has a glass in front of the tube that glass will be leaded. Period. Bonded faceplates didn't come in until the late fifites. Leaded glass can look almost clear with just a bit of tinting but will be 5 to 10% heavier than the same volume of regular glass.. and leaded glass can also be blue - or be a plastic mix instead of silica.

[old_coot88]

If there were any truth to the much-ballyhooed Xray threat from TVs in the 1950s, all my kids shoulda had two heads, 6 fingers and toes.
And hell, I ain't croaked yet.

[cwmoser]

Originally Posted by old_coot88

If there were any truth to the much-ballyhooed Xray threat from TVs in the 1950s, all my kids shoulda had two heads, 6 fingers and toes.
And hell, I ain't croaked yet.

I remember as a youngster playing with the X-ray machine in the Shoe Department at Sears Roebucks department store. We liked to see the bones in our feet. The X-ray machine must have been left running all the time because when Mom to us to Sears, we would run to the Shoe Department and couldn't wait to "see the bones in our feet".

Carl

[bgadow]

Remember that many, many sets used clear plastic instead of glass, even in the 40s. It is my understanding (and I do not claim to be an expert) that the voltages used in the average bw set are not high enough to create xrays at the CRT. This was more an issue when color came along, especially later on when the HV started approaching 30kv. I would be interested in reading documentation from the 50s indicating the need for leaded glass on bw sets. If it is available, please post it, so we can all learn from it.

[Phil Nelson]

That's my understanding, too. The HV from an everyday 1950s B/W set doesn't generate X-rays in significant amounts. Early color and projection sets have higher HV and generate more. The safety glass (or plastic) is there for implosion protection.

On a related note, I have been told that the cages enclosing the HV sections on B/W TVs are intended to reduce interference and keep fingers away from HV, not to limit X-rays.

Phil Nelson

[N2IXK]

My understanding is that X-rays are actually created from about 10 kV on up, but that below 20 kV or so, they are too weak to penetrate the glass tube envelope, so there is no way they can pose an exposure hazard at all.