Zipp Phones and Cathode Ray Tubes · 5:15pm Oct 23rd, 2022
Zipp’s folding phone feels like a joint marketing opportunity with Samsung that wasn’t fully realised. Her cool hoofset has something like their Infinity Flex Display, which can be literally folded in half, but the shape is more like the Galaxy Z Fold series than a Z Flip (“Zip”) phone.
This type of gadget was once pure fiction. They are now real and let us read our fanfics on a decent-sized screen while waiting at the bus stop, then fold it up and put in a pocket when the bus comes. In the future, they may become as mundane and exciting as paper envelopes, and the industry will move on to wow us with stretchable wearable screens, or whatever the next thing will be.
Semiconductor physicists have been plotting for years to take over the world. The first glimmer of a revolution on the visual display front came with the invention of the Light Emitting Diode or LED. The early gallium arsenide devices from the 1950s provided the first replacements for incandescent bulbs for indicator lights, but it took many years for more materials to be developed to reduce the cost, provide more colours, and move beyond little red lights. The invention of the blue LED, using gallium nitride, was a major breakthrough, recognised by the 2014 Nobel Prize for Physics. This was the historical era I imagined in The Great Luminescence Theft.
The preferred technology for gadget screens these days is organic LEDs – OLEDs. A large group of organic semiconductors developed to emit light in a variety of colours. However, the light emitter is only one part on a working display. You need protect the air-and-water-sensitive OLEDs in some sort encapsulation. You need a substrate to mount it on; a grid of electrodes to deliver power to the pixels; a transparent protective layer to stop your lovely shiny screen getting scratched. Every bit of this is the result of years of research.
There is one more bit of physics to consider, if you want your screen to be touch-sensitive then you need to cover it with an electrostatic grid of indium tin oxide (or something similar) and apply an electric charge so you can sense the presence of an electrically conductive finger by the distortion of the field. The impedance of a large keratin hoof, or an iron horseshoe, would be rather different. It should be easy to adapt the technology for ponies, but it as it is clear that the new generation hooves have a magic well beyond our technology, there is little point in speculating too much about the precise mechanism behind those hoof taps.
Instead let’s take a trip back to the time when particle physicists controlled our view of the world.
For decades, televisions, and whatever display you connected to your video cassette recorder, games console, or home computer, worked by firing a beam of electrons through a cathode ray tube onto a phosphorescent screen. This was great as an example of applied particle accelerator technology. You used electric fields to deflect the beam left and right, up and down, applying an oscillating voltage to electrodes to scan across the screen many times a second. They were big, heavy, needed a lot of power, and not at all practical as a display on a pocket-sized gadget. The only reason the technology stayed around for so long was the lack of alternatives.
Last week I had some extra roof insulation fitted in my loft (all part of a grand scheme to thwart Vladimir Putin’s evil plans, counter the climate emergency, and reduce my heating bills). The fitters brought down all the junk left up there by previous occupants, including old light fittings, a cat basket, pair of pink bunny ears, and an old particle accelerator / CRT television set.
I turned it on. It seems to be working, although there is no analogue TV signal for it to receive. Now I am wondering if I can take some inspiration from Izzy Moonbow and unicycle this into a cool particle physics demo to show how you can manipulate charged particle beams in electric fields. Might be a fun project. When I asked around, it turns out I know some retro-gamers with ideas about this. We’ll see where this goes.
The HD chipset standard supports down to 480i, standard NTSC and depends what extra sockets are on the back of the thing unless it is so old it only has an RF input. Inside the RF is decoded down to RGB at some pojt, which is why TVs ended up with that as an input option on the back. It was just a set of cheap sockets wired to pins that already existed.
If you really want to demonstrate fields and aprticle accelerators, depending on your global location, the TV image can twist visibly depending which direction the CRT is pointing because the beam spirals due to the interactions between teh quadrapole and hexapole focusing magnet arrays round the tubes neck.
Also, that picture youtre looking at? I thought I heard somewhere that a third of that noise is CMB signal. the pity is that its not easily selectable.
5694043
While it is true that a fraction of the static in an old TV set comes from the CMB, that fraction is very small, on the order of a percent or less. Microwave and radio signals from the surrounding galaxy contribute far more. In theory, you might be able to rig up an antenna system that can sufficiently isolate and display just the static from the CMB component, but you'd have to first subtract out all the terrestrial and galactic sources, which is by no means trivial.
The touchscreen is more complex than just adding another layer or two of indium tin oxide to sense capacitance changes. There are also orthogonal clocking signals driven through those layers to determine exactly where the capacitance changes are on an x-y plane and the relative area of each of the changes. Active matrix (LCD or OLED) touchscreen displays are a pain for the RF engineers working on cell phones because the semiconductor and conductive layers in the panels both reflect radio waves from the phone’s transmitters in unwanted ways and radiate all the various clocking signals driving the display and touchscreen very close to the phone’s receiving antennae and the RF amplifier circuit paths. A lot of work is spent mitigating all the electromagnetic interference the phone itself generates: desense, as it’s called.
5694043
This is a European set, so I need to learn more about SCART connectors.
5694057
Yes, I've not done a proper analysis, but as I live in the city, I expect most of the radio noise in my house is terrestrial. If I lived in the country, then it might be a fun project to set up an antenna and try to tune in to some galactic or extragalactic sources, but where I am - no chance.
5694061
Indeed, when you start to go into it, there's a lot more. I did download a few papers on new developments, and then decided that to keep this post of manageable length, I'd just stick with my simple summary.
5694073
SCART?
Excellent.
If you are lucky, you might find the R.G.B pins are actually connected, making it Extremely simple to get a modern box signal into it.
Usually by using a set top box with a SCART socket on it and a decent 12 way plus cable? Simplest is to call up the on screen menu and scroll through to see what it gives you for RGB, A/V, YUV, SVHS etc.
Even if you only have Composite plus stereo audio, 3 wires and shield connected, that bypasses the RF.
Suprised me when I found out from the manual pin out that the ZX Spectrum has RGB signals on the edge connector.
RGB to HDMI is easy. HDMI to RGB is.. lets say not that easy or cheap to get due to legal reasons.
5694073
Let’s just say I have first-hand experience in dealing with cell phone display and camera desense and other related electrical engineering issues and leave it at that.
5694151
You’re not going to give us any hints on the future of wearable tech?
Back in grad school our graphics lab had some cutting-edge tech for the time: 19" RGB monitors driven off a Raster Technologies 512x512 framebuffer with polygon-rendering ability (the RasterTech itself being driven over a 19.2k serial line from the VAX)! One of the monitors got a bit misaligned and my advisor, a very quirky person, decided to realign it himself. With the power on. So I came in one evening to see him poking around the inside of an open monitor with some sort of probe adjusting the deflection coils and am like "Um, Al, you know that's about 30 kV in there, right?" Unfazed he continued on. Not sure if I was more concerned for him or my degree program, you understand.
Loosely related, the graphics lab was underneath the computer center. A couple of years later we had actual HP graphics workstations donated through an NSF grant, and to be able to work without excessive noise, the power-hungry machines lived upstairs. We had a 6" hole cut in the concrete floor and keyboard/mouse/RGB cables fed through to the lab. It was all going great except for the unpleasant <i>hum</i> scrolling constantly over the monitors. And soon a smart EE (we were actually in the EE building, despite it being a CS lab) figured out that the ground planes of the computer room and the graphics lab were about 1V apart. Eventually worked around though I don't recall how.
I'm current working in semi-conductor patents at the USPTO, and I've learned more about LEDs, thin film transistors, and LCD's in the past few weeks than I thought I would need to. For proprietary (I think that's the right word) reasons I can't say anymore, but it's been an experience.