“Colored Television”…
“Colored Television”…
Did you know that up till about 1932, the pictures on cathode ray tubes were green…like an oscilloscope screen? Me either, but there it was in an article on the history of the Empire State Building antenna from 1967.
Quoting the article; “At that time, the tubes had green fluorescent screens, since the white phosphor later used for black-and-white television had not yet been developed.”
This was in relation to NBC’s first experimental television transmissions from the first Empire State antenna on December 22, 1931. The first experimental transmission from the Empire State Building were 120-line pictures using mechanical scanning of both film and live subjects.
The live subject would have most definitely included extended periods of Felix The Cat spinning on a turntable. As I reported in the NBC Studio History Series earlier in the year, Felix, the mechanical camera and the transmitter were in the Roof Garden Studio of The New Amsterdam Theater on 42nd Street and were 60 line transmissions received on these green tinted screens.
It would be interesting to know when the white phosphor process began. I’m looking but as yet, no luck, but I did find this rare photo from 1932. If anyone has any information on this, please share it with us
Actually, I guess the origin is lost n the sands of time. I have a copy of the official EIA tube registration Data base and P4 is shown as offically registered and specified to the industry in Tube release 3078 of Decenber 18 1960!
A note in that document says that “The P4 Phosphor was never formally registered and released to industry, However defining data was previously published in JEDEC Document J6-C3-1 dated February 1 1952. the Attached sheet include the previously published data (revised where necessary to meet the new JEDEC standards) as well as additional information not covered originally in j6-C3-1”
The document goes on to list three different types of P4 Phosphor, Silicate Sulphide for Theatre projection tubes, All Silicate for TV picture tubes and All Sulfide for “Direct view Television” (I thought that was a picture tube?) Interesting…
Many of the early CRTS are shown as registered in 1945, when the war secrecy came off, and the registration system started getting caught up, but in many cases only the P1 (green) version was actually registered, and the other colours were special order (P7 used for Radar, which has a short Blue glow and a long yellow glow is another common variant)
The CRT’s back then used the P1 phosphor as oscilloscope CRT’s did…Once they started using the P4 phosphor which was a silvery/white, and the entire look changed. P3 phosphor was orange…The CRT numbers showed the type of phosphor…for example, a common 21 inch monochrome CRT with the number 21FBP4 used the silver phosphor (P4). A common oscilloscope CRT was a 5UP1 (using the P1 phosphor…green). P22 was used in color CRT’s for example a common color CRT was a 21FJP22…The last 2 to 3 digits indicated the type phosphor. Hope this helps 🙂
I torched up one of my Pilot-radio TVs from 1949 and the picture was gray and green. No wonder kids sat so close to the tiny screen.
“It’s not that easy being green.” Kermit the Frog, The Muppet Show.