How Cathode Ray Tubes Work.

I was a CRT engineer back in the 1960s. This video is a pretty good basic explanation. But, the stuff on the front glass is “phosphor,” not phosphorous. Warning, do not put your hands near a CRT while it is on, or you may be zapped. Also, don’t try opening a CRT that is under vacuum. The whole tube could implode, shooting glass everywhere. The dots or stripes were aligned with the shadow mask and electron guns. The inside front of the envelope was first coated with a phosphor of one color mixed with a light sensitive material. The mask was put in place and a light was shined from the position corresponding to the location of the electron gun for that color. The light caused the dots or lines to bind to the front glass. The mask was removed and the unbound phosphor was rinsed away. Repeat two more times for the other colors. Then remove the mask once more and flash a thin layer of aluminum on the gun side of the phosphors, to reflect emitted light forward and avoid static charges. Finally, seal the front panel to the rest of the envelope. Amazing for mass production of a $190-$200 CRT!!

It’s impressive how they were able to line up the shadow mask and the phosphor so accurately.

It's weird to think about but CRTs are a primitive sort of particle accelerator. If you're over 30yo you spent a significant period of time staring at a particle accelerator.

Honestly, the way CRTs work just sound so much more “advanced” in a way, like just the thought of getting an electron gun to shoot across the field that fast is incredible in hindsight, especially when you consider how some games were able to actually use that to creative effect— like how the waterfalls in Sonic the Hedgehog have a rainbow effect on a CRT.

For those who want to know. The TL:DR of the Trinitron is they use an aperture grille instead of the shadow mask, as well as a single electron gun, with three separate cathodes.

Thank you for the shadow mask demonstration. I've always understood the concept of "There's a metal sheet in here which magically somehow makes the guns only strike certain phosphors", but I never understood it was an alignment trick until your demonstration!

There's a more recent technology called the "Laser Phosphor Display" where it's similar to a CRT but the beam of light is driven mechanically with a UV laser. This removes the need for a vaccuum seal and therefore a bulky weight, and also allows it to have very low power consumption on par with or better than today's OLED displays. I always thought this is a great way to preserve the look and feel of retro games, but no company seems to realize it.

Cathode Ray Dude is doing computers now and 8-bit Guy is doing cathode ray tubes!

There was a class action lawsuit about the misleading way CRT sizes were described. That's why, in later ads, you'll see the size listed with wording like "15" TV (14" viewable)"

Touching the internals while the screen is on gives me chills.

Sitting here in my game room with 6 Sony PVMs and an HD CRT. CRTs still are alive and well for me.

Resolution (not dot pitch) is how closely a CRT can display lines to each other that can still be visually separated (or "resolved"). Resolution is measured in lines: it's how many parallel alternating black and white lines can be displayed and visually separated. Dot pitch only applies to color CRTs: it's the distance from the center of one phosphor dot to the center of the next phosphor dot of the same color. Monochrome CRTs don't have dots: they have a continuous field of one color of phosphor. A spot is the area lit up at a given instant by an electron beam. Monochrome CRTs have one spot, and color CRTs have three. The spot(s) are constantly moved (scanned) across the screen from left to right to draw the image in horizontal lines from the top to the bottom. A CRT's resolution is effectively limited by the spot size, the dot pitch, the scanning format (how many scan lines per picture), and the signal bandwidth (how quickly the signal can change between light and dark). The vertical resolution is the number of horizontal black & white lines that can be resolved across the picture height, and is generally limited by the number of scan lines per picture in the scanning format. The horizontal resolution is the number of vertical black & white lines that can be resolved across a width of the screen equal to the screen's height ("TV lines per picture height"), and is limited by the source signal's bandwidth and the bandwidth of the display's signal processing.

I remember moving from one state to another back at the end of the CRT era... moving a 40 something inch crt up a flight of stairs was like moving an elephant... the weight difference is certainly an advantage of flatscreens. Great video David.

thank YOU for explaining TUBEs

Smearing away the phosphor with your finger like that was MIND BLOWING.

I remember CRT tvs gave off a high pitch noise, something like tinitus. It wasn't hard on the ears but it did give you away to your parents if you were staying up late playing your NES.

What an impact screen technologies have had even on furniture. TVs used to be pieces of furniture. Next they moved to sitting on furniture. Now they mount on the wall. How many households have entertainment centers anymore? I’m sure many do, but I’m sure the number of mounted TVs is growing. Great content, David. Thank you.

In terms of aspect ratio. I think the key reason why 16:9 got popular, was because it fit most movie and DVD videos better. Even though for computing one usually wants more horizontal space.

It's a tiny particle accelerator!

I'm definitely old. I went to High School in the mid '70s and took a Radio/TV repair shop class and we learned how to repair TVs. My achievement was finding two different TVs that were both broken but the guts were the same even though they were different models. So I took the CRT from one and put it in the other and got myself a Free 25" color TV and I put it in my bedroom. The family TV was a 19" black and white one in the den. I have lots of experience with playing around with the yokes and such. Also I burned my finger once in the flyback cage. It actually just went in one side and out the other side of my finger. Otherwise I'd be dead now.