Sequential Color Project

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Sequential Color Project

Postby Lawnboy » Tue Sep 23, 2014 8:11 am

Ever since I saw photos of Peter Yanczer's replica of Baird's 1928 color system, I wanted to build one myself. But rather than copy Peter's replica directly, I want to design something a bit more modern that others could easily build, which means tweaking the format somewhat.

Baird's original format is as follows: it used a 3 spiral, non-interlaced, 45 aperture, vertically scanned disc giving a 15 line image with an aspect ratio of 1:2. Each spiral is covered by a red, green, or blue color filter. The light source was a pair of custom made gas discharge tubes: neon for the red color, and a helium-mercury vapor mix to supply the blue and green color. The tubes were successively switched via a commutator on the receiving disc's shaft. The disc spun at 600 rpm giving 10 frames (or 30 color traversals) per second.
My idea is much the same as Baird's, but the image is made up of a more logic-friendly 16 lines, and there are no commutators, instead relying on the color filters, to, well, filter the colors. The signal will be generated by a computer (hopefully via Video2NBTV) and fed to the LED drivers in the same way a typical club monitor is driven, with the exception that all three LED drivers will be fed the same signal.
I chose to stick with the original 10 fps frame rate. This is so that a single frame drawn by the disc will be made of three video frames from a 30 fps NTSC source, with each color traversal taken from a different video frame. This should simulate any color break up that occurred with quick movement of the subject in the original demonstration.

Rather than building a new monitor from scratch, I just made a new disc for a parallel RGB color monitor that was built for use with the 19” club disc. Unfortunately the disc pattern must have slipped a bit during the marking process, and one (or two) of the spirals is/are a bit out of line. This makes the image appear to wobble up and down slightly, a bit like a flag. I don’t have a way to generate the correct format yet, so the following pictures were taken with Peter Smith's color bar generator, manually synced, with no filters on the disc. The first picture shows spiral 1 with the other 2 masked off. The second picture shows the effect with all 3 spirals. In real life the second image is nowhere near as distorted as it appears, instead replaced by the vertical flag-waving effect, but the distortion may show itself once the filters are put on. Actually, when viewed at its original size (9/16" x 1"), it really doesn't look half bad.
Attachments
IMG_2978 crop res.jpg
Single Spiral
IMG_2978 crop res.jpg (81.05 KiB) Viewed 3368 times
IMG_3022 crop res.jpg
3 Spirals
IMG_3022 crop res.jpg (91.44 KiB) Viewed 3368 times
Lawnboy
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