It was a misaligned shield over one of the internal vacuum tubes that caused the issue, not the screen. And it was only certain models of GE color televisions that had the issue. The result was dangerous levels of X-rays emitted at a downward angle. If you happened to have one of the affected GE brand televisions, your X-ray films on the corners of the screen were likely above and outside the path of the X-rays. So, not a valid test in this case. The X-rays in the GE TV weren’t coming from the screen. They were coming from a vacuum tube inside the TV.
But, if you didn’t have one of the affected GE televisions, then there weren’t any dangerous levels of X-rays anyway. So you did at least disprove the common misconception at the time that all color televisions were bad.
I am kinda surprised that the film didn’t fog up a little, though. Cathode ray tubes do produce a small amount of X-rays during normal operation. The level of X-rays produced is small enough that it’s not a health risk, but it’s not zero.
I didn’t have to worry about X-rays because I had been warned many times, since the first day my parents got their first TV, that SITTING TOO CLOSE TO THE TV (any TV) WILL RUIN YOUR EYES.
Even better – it did triple duty. It also drove the front end of the power supply for the audio amplifier. The high frequency meant that filtering after rectification required less expensive capacitance.
Since the OP has been completely answered, let me say a word about really early color TV. The first color system approved by the FCC in the mid ‘50s used time multiplexing and a spinning color wheel, twice the size of the TV screen. They transmitted the threes colors in sequence and the color wheel spun in sync. This was the CBS system. RCA had a scheme that was ancestral to the one used today, but the quality was poor. A year or two later, RCA had improved it to the point that it was competitive and the FCC changed its mind. Imagine if they hadn’t. You want a 60" color TV, you need a 10’ color wheel spinning in your living room.
Experimental colour TV had been around for quite a while, even before WW2 (Baird claimed to have developed the spinning filter wheel). TPTB took their time deciding on whether and when to allow it to go ahead before giving permission to the BBC.
Video cuts the explanation of who and when the name for WWI came from:
Far from waiting until the Second World War had started, the First World War was rather pessimistically named as such in 1918. British Officer Lieutenant-Colonel Charles à Court Repington recorded in his diary for 10 Sep 1918 that he met with a Major Johnstone of Harvard University to discuss what historians should call the war. Repington said it was then referred to as The War, ‘but that this could not last’. They agreed that ‘To call it The German War was too much flattery for the Boche.’ Repington concludes: ‘I suggested The World War as a shade better title, and finally we mutually agreed to call it The First World War in order to prevent the millennium folk from forgetting that the history of the world was the history of war.’
From the QI site, the note from the QI site is gone, but Reddit did quote them as such.
DLP is in no way similar to a spinning color wheel. As the article you cited says,
In DLP projectors, the image is created by microscopically small mirrors laid out in a matrix on a semiconductor chip, known as a digital micromirror device (DMD). These mirrors are so small that DMD pixel pitch may be 5.4 μm or less.[2] Each mirror represents one or more pixels in the projected image.
Rapidly toggling the mirror between these two orientations (essentially on and off) produces grayscales, controlled by the ratio of on-time to off-time.
In lower end DLP systems the light shining on the micromirror array did pass through a color wheel. The micromirrors positions were changed in sync with the color wheel to project the appropriate pattern for each color.
Higher end/higher power DLP systems (like theater projectors) used three micromirror arrays, each with its own constant light source of the apppropriate color.
This information is in the Wikipedia source which you cite.
I forgot about those. Coming from the digital cinema world, I never saw those kinds of systems, which are used mainly in home projectors, IIRC. Thanks for the update.
They were originally used in rear-projection DLP TVs, which were the first DLPs to hit the market. They were shallower and lighter than the older rear projection TVs, but (like the old rear projection TVs) have been driven from the marketplace by LCD and other flat-panel technologies.
In a projector with a single DLP chip, colors are produced either by placing a color wheel between a white lamp and the DLP chip or by using individual light sources to produce the primary colors
Something would have been figured out. You could never have a direct-view 60" CRT anyway. It would have to be a projector of some kind, and the wheel for a projector can be much smaller. Eventually, they could have used a “modern” shadow mask system, but run the electron beams in sequential mode instead of concurrent. And then there’s the aforementioned DLP systems that also use sequential color.
IMO, sequential color sucks and gives obvious rainbow effects on all moving objects. Glad we avoided that outcome.
:
