Re: UNUSUAL CRT Instruments?

Don Black <donald_black@...>

I think the HP recorder I'm thinking of just used a very high intensity tube to "burn" a trace directly onto a paper strip. I don't think it was particularly light sensitive paper but not sure about that. he tube may have produced light in the UV in which case I expect the tube would need something like a quartz or similar faceplate. Does anyone have more information on these?

Don Black.

On 05-Sep-13 1:47 AM, edbreya@... wrote:

The Tek 4600 series hard copy units used a line-scan CRT that had a fiberoptic faceplate to carry the light from the phosphor to the surface, where it printed onto special silver-based paper that was scrolled past. The paper then went through a heated roller section, which turned the exposed parts to a dark brownish-black.

These were used to make hard copies of the screen images on the Tek 4050 series computers, which had  direct view storage tube (DVST) displays. Remember, there was no electronic display memory - the data was stored on the tube only. The printing process actually scanned the stored display tube image in a special mode, and read the tiny current changes between light and dark, converted these to binary, and sent the serial signal to the 4600 unit, where it replicated the light and dark. All of this had to be synchronized, making it an electro-opto-thermo-mechanical wonder.

This was a destructive readout system - the scanning process gradually destroyed the stored data, so only one to a few copies could be made, getting progressively worse. The 4600s were huge beasts too, with all kinds of subsystems needed to make everything work - paper transport, air blowers, heating and cooling, and of course, the electronics for the CRT. The 4610 that I had weighed about 80 pounds, as I recall. The main problem was the special silver copy paper. It was very expensive, and had limited shelf life. Sometimes old rolls would show up at the Country Store, but otherwise, forget it. Inside the 4610, the paper roll was stored in a special insulated box that was TE-cooled to prolong its standby life, and protect it from the hot processes all around it.



--- In TekScopes@..., wrote:

Those single axis tubes used in the Tektronix hard copiers sound like the equivalent to the HP one I mentioned.
Also the B&K flying spot scanners that I should have thought of (I have one). Flying spot scanners were also used professionally for scanning movie film, some very high quality units were made. Since there was only one photo detector for monochrome or the for color (for Red, Green, Blue) it was possible to get good video correction and color matching. While it was possible to use a raster scan for each film frame being stopped in the gate, single line scanning was also used with the film steadily moving for the vertical scan. The CRT scan was split to scan the image twice to get interlacing.

Don Black.

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