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How does a screen work?

makingsoftware.com

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Re: How does a screen work?

#11

Post by eastbound »

jagged-chisel wrote: post #9
retrac wrote: post #4

CRTs are still slightly magical to me. The image doesn't really exist. It's an illusion. If your eyes operated at electronic speeds, you would see a single incredibly bright dot-point drawing the raster pattern over and over. This YouTube video by "The Slow Mo Guys" shows this in action: https://youtu.be/3BJU2drrtCM?t=190

When I learned how TV worked at the beginning of television history, I found it super cool that the camera and all the TVs across the country had their scanning beams synchronized. That camera was driving your TV, almost literally.

I only recently found out that the tech to save images wasn’t invented, so they couldn’t display a revolving logo between shows. So… so the BBC had a permanent real-life logo with a permanent camera in front of it.

So yes, any image was extremely ephemeral at the time.

PS: Apparently it’s called a Noddy, it’s a video camera controlled by a servomotor to pan and tilt (or 'nod', hence the name Noddy): https://en.wikipedia.org/wiki/Noddy_(camera)

Re: How does a screen work?

#12

Post by hinterlands »

retrac wrote: post #4

CRTs are still slightly magical to me. The image doesn't really exist. It's an illusion. If your eyes operated at electronic speeds, you would see a single incredibly bright dot-point drawing the raster pattern over and over. This YouTube video by "The Slow Mo Guys" shows this in action: https://youtu.be/3BJU2drrtCM?t=190

That slo-mo video is somewhat misleading, though. The phosphor glows for a good while, so there is a reasonable chunk of the image that's visible at any given time.

The problem in that video is that the exact location the beam is hitting is momentarily very bright, so they calibrated the exposure to that and everything else looks really dark.

Re: How does a screen work?

#13

Post by snovymgodym »

retrac wrote: post #4

CRTs are still slightly magical to me. The image doesn't really exist. It's an illusion. If your eyes operated at electronic speeds, you would see a single incredibly bright dot-point drawing the raster pattern over and over. This YouTube video by "The Slow Mo Guys" shows this in action: https://youtu.be/3BJU2drrtCM?t=190

> It's an illusion.

In a sense, all vision is.

Re: How does a screen work?

#14

Post by grishka »

retrac wrote: post #4

CRTs are still slightly magical to me. The image doesn't really exist. It's an illusion. If your eyes operated at electronic speeds, you would see a single incredibly bright dot-point drawing the raster pattern over and over. This YouTube video by "The Slow Mo Guys" shows this in action: https://youtu.be/3BJU2drrtCM?t=190

To me the magical part about CRTs is color. I don't quite understand how the shadow mask works. Like, yeah, there are three guns, one for each color channel, and the openings in the mask match their layout, and somehow the beam coming out of each gun can only ever hit its corresponding phosphor dots. Even after being deflected. But... how? Also, wouldn't the deflection coils affect each of the three beams slightly differently?

Re: How does a screen work?

#15

Post by grishka »

snovymgodym wrote: post #13
retrac wrote: post #4

CRTs are still slightly magical to me. The image doesn't really exist. It's an illusion. If your eyes operated at electronic speeds, you would see a single incredibly bright dot-point drawing the raster pattern over and over. This YouTube video by "The Slow Mo Guys" shows this in action: https://youtu.be/3BJU2drrtCM?t=190

> It's an illusion. In a sense, all vision is.

All our senses are.

Re: How does a screen work?

#17

Post by ksec »

LCD on paper you see lots of drawbacks, in practice modern state of the art LCD for TV is pretty damn good. We will soon have RGB LED Backlight LCD with WHVA+ Panel that is about as wide angle as IPS, 95%+ REC 2020 colour, and 1-2ms response time.

Phosphorescent blue OLEDs should reduce current OLED display energy usage by 20-30%. But it still seems to be way off for phones and mass usage.

Re: How does a screen work?

#18

Post by vicurve »

I can appreciate these articles as they are but I personally don’t like them. They are junk food level of infotainment to me. Something I’d find on a Wikipedia summary section that covers general points.

A CRT - to name one - is a device whose actual understanding will challenge people in profound ways. To ask “how does a screen even work?” and to begin to answer this question will require a bit more than a summary form of “thing goes from point A to point B”. The history of this discovery is a stack of books and in and of itself is fascinating - the experiments and expectations and failures and theories as to why and how. I suppose I just expect more of the site. The illustrations are nice. Oh and my moniker is just a coincidence.

Re: How does a screen work?

#19

Post by vicurve »

nu11ptr wrote: post #8

Am I the only one who read this as the terminal program "screen" (the terminal multiplexer)?

It was 50/50 for me as well but the screen source code is fairly readable and if I remember right eerily over-commented for Unix code! The function names actually make sense.

Re: How does a screen work?

#20

Post by charcircuit »

YZF wrote: post #10
charcircuit wrote: post #5

>The fact that they ever made it out of the research lab and into our homes is astonishing to me. What is astonishing about LCDs? I don't mean to diminish the difficulty of scaling up the process, but if you think of early LCD displays they don't seem farfetched to be shipped to consumers.

One random example is that your eyes are extremely sensitive to the tiniest defect or variation. So making a large display that looks good and is uniform is very challenging. Not to mention scaling up all the various processes like the photolithography and working with very large and thin glass panels. It's all engineering but it's surprisingly hard to move things from the lab to manufacturing at scale. Years and yea…

You are moving the goal posts from it being a consumer product to requiring it to be large, good, and uniform. Yes, there was engineering work to make such a consumer product, but it is something I would expect there to have been line of sight for.
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