Comment by MenhirMike
2 years ago
I'm kinda curious if CRT technology advanced to the point where a TV like that would've been possible at a better weight and price tag? I assume that CRT technology development stopped decades ago, but could we have e.g., replaced the heavy glass with some plastic-like material to save weight without compromising the picture? And are there any heavy components in the mechanism itself (Coils, Magnets?) that would have had alternatives?
I know it's just theorycrafting, but I do wonder what kind of CRT someone could've created if it wasn't for market economy forces.
Here's the last gasp of thinner, bigger CRTs, in 2005.[1]
"Today, CRT markets are being threatened by flat-panel displays (FPDs) even though the screen quality of the CRT is one of the best of existing display devices. The depth of CRTs is one of its most important design factors to maintain its dominant position in the display market. Thus, a 32-in.-wide deflection-angle 125° CRT (tube length of 360 mm) has been developed, and mass production began in January 2005."
That was the Samsung Vixlim.[2] Apparently worked OK, but obsolete at launch.
Goes down in history as another last and greatest achievement of the wrong technology, along with the Doble steam car, the SS United States, 3-projector Cinerama, quadrophonic phonograph records, and the Olivetti Divisumma 24 mechanical four-function calculator.
[1] https://sid.onlinelibrary.wiley.com/doi/abs/10.1889/1.216683...
[2] https://www.reddit.com/r/crtgaming/comments/xgtmdw/does_anyo...
32 inch wide, 14.5 inch deep. Not bad. You could actually fit that on a 80cm desk.
/r/crtgaming ... calling it, this the new hip before it's cool
"These wide-deflection CRTs attracted an extraordinary amount of attention even from end users in a variety of display shows last year and will help maintain the solid positions of CRTs in the coming era."
On top of the mechanical issues, CRT glass also functions as x-ray shielding, for which reason it is leaded (Pb). You can't really make that part lighter.
https://en.wikipedia.org/wiki/Cathode-ray_tube#Body
https://www.epa.gov/hw/frequent-questions-about-regulation-u...
(This isn't really an answer to the overall question—just a narrow observation of interest).
This is an interesting point. Does anyone know how much lead would be in a 21 inch monitor?
According to [0], about 1.2 kg (2.6 lbs). Surprisingly this is mostly in the neck and funnel of the tube - the screen itself uses different metals because lead would affect its optical performance.
[0] https://www.sciencedirect.com/science/article/pii/S187802961...
Oh I didn’t know that. Neat.
The next big thing was supposed to be Field Emission Displays. Microscopic electron guns directly behind each phosphor. The big manufacturers experimented and tried getting it commercialized for decades, then pretty much gave up in the 2000s when LCDs got stupid cheap.
https://www.engineersgarage.com/field-emission-display/
There was also a brief reign of plasma TVs in-between, now almost a forgotten technology
I have an HD plasma and it is fantastic. It is the very best living room display I have owned.
Like the CRT, it has glowing phosphors in a tube. Unlike the CRT, it is pixel addressable, where the CRT is basically not addressable, or maybe just field, frame and or line addressable. Of course the tradeoffs are well known. Resolution scaling on a CRT is rarely an issue, except when the dot mask is too coarse. It still looks great. It can be a major issue with pixel addressable displays, when uneven multiples are in play.
In my experience, a good plasma is right there with the CRT on color gamut and contrast, even does well on speed. Or can. Mine is 120Hz and does not lag more than a CRT does on 60Hz signals.
(If you want a fast one, get one of the 3D capable TV sets from that era. They have fast video processors and basically can run at least double the necessary frame rate. And if you have an nVidia GPU and good CAD software, you can even use one as a wall sized 3D display featuring a bunch of things an ordinary set will struggle with and large assembly visualization as well as technical surfacing being two use cases I found amazing.)
AMOLED looks like it may be the next plasma. I have one from Waveshare that is 10.5" and has 2560x1600 resolution. I wish it were bigger. It is fantastic! It has a much higher DPI than my plasma does and appears to not require a PWM cycling of pixels to get those hard to hit grey levels.
I am learning I like displays where the light is not filtered down to a color, instead is just emitted at the color. Micro LED could be another contender if they can get the dot pitch high enough.
All that said, I keep a few CRT displays. I really like them for retro computing and gaming.
4 replies →
A good 720p plasma is still a great display to this day.
7 replies →
Despite its benefits over LCDs, it had no chance to compete on price. LCD prices just plummeted to far too fast.
OLED is the current equivalent (with perhaps QLED) and micro LED on the horizon.
4 replies →
I imagine much of the weight is for the tube to be strong enough to hold the vacuum without shattering. As the screen area increases, you need stronger electron sources, and higher HT to get the electrons to the phosphor. I think small 14 inch trinitrons are already using 20-30kV so I imagine the power supply and associated HT stuff will be quite scary in these larger sets.
There are all sorts of complex magnet arrangements to tune the beam to stay in focus across the image area, i don't know how that will scale with size, but it's probably more of a complexity when assembling the sets to calibrate the tubes.
You’d be surprised how little glass is needed to be strong enough to withstand a near perfect vacuum.
I worked in a lab where we routinely held a few micro-torr of vacuum, which is about the limit for mechanical pumps. Cathode ray tubes are typically thousands or tens of thousands higher pressure.
We ran 1/4” wall thickness glass even in large flat stretches without issue.
I’m guessing the weight of large cathode ray tubes are more for durability than need for the vacuum inside.
That's a bit misleading the level of vacum might differ by factor of 10000, but most of the force is still coming from atmosphere. For overall mechanical strength it doesn't matter that much if its 0.99 or 0.99999999999 atmospheres of pressure difference, temperature and other wheather changes are probably causing much bigger change in force applied to glass.
1 reply →
How much did the flat sections bend or deflect under vacuum?
Living room tv sets need to be child-save, unlike lab equipment.
I assume that CRT technology development stopped decades ago, but could we have e.g., replaced the heavy glass with some plastic-like material to save weight without compromising the picture?
Metal-cone CRTs were common in the early decades, and had a flatter screen than typical all-glass construction; here's the largest of those, a 30":
https://www.earlytelevision.org/dumont_30bp4.html
a TV using it cost almost $1800 in 1952 (equivalent to over $21k today):
https://www.earlytelevision.org/dumont_ra-119.html
I think metal-cone CRTs became unpopular due to the glass-to-metal seal not being as reliable, and difficulties with insulation (the whole cone is at the final accelerating voltage.)
I remember reading somewhere that there was this wild prototype flat CRT where the electron gun was at the top, shooting down, and the beam did a 180 degree turn at the bottom before being deflected into the surface of the screen.
Yes, the Sinclair TV80 worked on that principle: https://en.wikipedia.org/wiki/TV80
Nope, it's that, but folded in half. Found a mention of it (that I commented on, lol): https://mastodon.social/@tubetime/111219376410543899
The glass has to be thicker, thus more weight, to withstand implosion from the vacuum it is holding.
Gorilla glass or sapphire glass might have enabled lighter tubes at a higher price, had CRTs retained popularity, but from what I can see, Corning never even considered it as a use case for Gorilla glass in their original 1960s attempt at development.
Would there be any point? Given the TV sizes of the 60s standard glass was probably more than strong enough, and the tube wouldn’t be very heavy.
No one would need to really think about until around 2000.