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Tiny volumetric display

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Re: Tiny volumetric display

#141

Post by Rebelgecko »

krenzo wrote: post #130
amelius wrote: post #126

Earlier quoted context omitted.

Another idea: why not put a tiny TFT display on the motor? You can get cheap ones at aliexpress.

Standard displays are 60 Hz. You need a much higher framerate because not only do you want 60 frames a second, but you also want some number of frames per angular rotation. For 1° of angular resolution, you would need: 360°*60 Hz = 21,600 Hz display. Liquid crystals can be modulated at KHz speeds, but you're not going to find associated driving circuitry to do that. It's not easy, and there's no demand for it. A TI D…

I saw a cool design where they stacked transparent displays

Re: Tiny volumetric display

#142

Post by TulliusCicero »

aj7 wrote: post #124

Why waste time with a bunch of discrete LED chips mounted at very coarse pitch when there are small LED DISPLAYS?

According to other comments, refresh rate.

When each pixel actually represents multiple pixels in a circle, you need a much higher refresh rate than 60 Hz.

Re: Tiny volumetric display

#143

Post by sowbug »

mhb wrote: post #136
sowbug wrote: post #53

A couple ideas for improvement. If you have extra identical motors and disassemble two, you can fashion a rotating power transmission system from the brushes in two assemblies. You sacrifice two motors for each unit, but it's a perfect fit and very reliable (with a cap and rectifier), and you don't have to worry about batteries anymore. The rectifier also provides a signal that the assembly has completed a rotation,…

What about keeping the motors intact and using the second as a generator?

I might be misunderstanding the idea, but I don't think it addresses the original problem that wires can't connect the two parts of something that rotates in a single direction.

Re: Tiny volumetric display

#144

Post by draugadrotten »

doubleg72 wrote: post #132
dekhn wrote: post #117

Earlier quoted context omitted.

It seems more likely that a mechanical engineer would end up using a slip ring, so the computer doesn't need to spin.

This is exactly what would be used, a Moog slip ring.

Thanks. Enjoyed the explanation of a Moog ring in this video: https://www.youtube.com/watch?v=bBrZw9CKDZo

Re: Tiny volumetric display

#145

Post by weinzierl »

"Small circuit boards from China are essentially free[..]"

A little later:

"Some time ago, I got access to a pick and place machine (a Charmhigh CHM-T36VA). I have it on semi-permanent loan."

Why is it, that it still makes sense to assemble boards yourself while outsourcing PCBs is a no-brainer?

It doesn't have to be "essentially free", but isn't there an assembly service that is suitable for hobby projects like this?

I assembled a fair share of PCBs, both for hobby and professionally (in R&D), but I neither have the time nor the space to do it anymore.

Re: Tiny volumetric display

#147

Post by randyrand »

weinzierl wrote: post #145

"Small circuit boards from China are essentially free[..]" A little later: "Some time ago, I got access to a pick and place machine (a Charmhigh CHM-T36VA). I have it on semi-permanent loan." Why is it, that it still makes sense to assemble boards yourself while outsourcing PCBs is a no-brainer? It doesn't have to be "essentially free" , but isn't there an assembly service that is suitable for hobby projects like thi…

because pick and place machines need to be setup per device

this is a solveable problem tho. I hope someone solves it.

Re: Tiny volumetric display

#149

Post by krenzo »

pyinstallwoes wrote: post #140
krenzo wrote: post #130

Earlier quoted context omitted.

Standard displays are 60 Hz. You need a much higher framerate because not only do you want 60 frames a second, but you also want some number of frames per angular rotation. For 1° of angular resolution, you would need: 360°*60 Hz = 21,600 Hz display. Liquid crystals can be modulated at KHz speeds, but you're not going to find associated driving circuitry to do that. It's not easy, and there's no demand for it. A TI D…

You seem to know a lot about this. Have you worked on similar things?

I work on VR/AR headsets where there's a drive for higher refresh rate displays to do things like multiple focal planes with the extra frames.

Re: Tiny volumetric display

#150

Post by i_am_proteus »

doubleg72 wrote: post #132
dekhn wrote: post #117

Earlier quoted context omitted.

It seems more likely that a mechanical engineer would end up using a slip ring, so the computer doesn't need to spin.

This is exactly what would be used, a Moog slip ring.

Mercotac makes nice slip rings too!

Most of the ones I have seen/worked with have been much bigger than this small display, though.

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