(Concept) Magnetic repulsion semidiscrete capacitive switch

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PlacaFromHell

07 Apr 2021, 09:58

Hello guys. Today I want to show you my newest concept, a magnetic repulsion switch inspired in Chyros' last switch teardown, but with some changes that make it substancially different and (I think) better. Allow me to introduce:

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That's a fuckton of information in a single picture, so we shall take the switch appart at first. The switch has a total of 10 parts consisting of the spring (I could model it but I hate doing them), slider, spring guide, 4 2x2x1mm magnets, housing, clicker and capacitive element. Anyways, the parts can be arranged in three groups according to their common purpose: housing (boring), slider and clicker. Let's take a look at the slider at first:

Image

This thing is quite simple, you stick a normal MX keycap on it and it goes up and down, but with two added oddities that make this more interesting. The spring is the same as in Cherry MX switches, but because the design lacks a bottom housing to hold it in place, I had to design a spring guide, which is basically a moving part that prevents the spring from scrap the PCB or bend. The other two pieces are fixed magnets, their only purpose is interact with the other two magnets in the clicker.

Clicker:

Image

This part is the trickiest, it took me a while to think the best possible way to make it work. Talking about the operation principle, we press the slider over it, the slider's magnets bypass the clicker magnets and because of the antiparallel configuration, it shoots the clicker up, producing bot a tactility and sound feedback and moving away the capacitive element under the plastic part (yes, this switch is normally closed like beamsprings). The thing is, yes, so easy, right? Right !? NO!!!! HOW DARE YOU!
As you might see the shape is weird. I wanted to make a very stable, maybe stupidly stable switch so I needed the moving parts to be as wide as a 1U key can fit (you can always make the switch taller, but this will make the entire keyboard taller). Also the force applied on the clicker must be as centered as possible. Ring magnets can make this easier but they come in not so great variety. So, the clicker basically goes right under the slider, in a way that the whole switch can be used without one coliding with the other, at the expense of that weird shape and not ideal stacking, neither the worst as the switch is sightly above 21mm. I think the tradeoff is better at the end, who knows.

Housing:

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Do I need to explain how a housing works? Well, in this case yes. I have a serious problem with nowadays and even vintage switches, not with what the housing does, but how it does it.
A)The mounting methods suck in most cases, square hole plates are harder to make, unless you mass produce plates by press cutting. Circular plate holes are way, WAY easier and cheaper. You can either CNC a plate in fewer steps or go with the good old marking tip and a very careful drill press job. If you already got one, you can stack them and make another plate out of it.
B)I dislike this whole new concept of hot swappable switches, but there is a smart and absolutely fair point in them. Applying heat to desolder/solder/reflow/whatever a switch is basically applying permantent damage to your PCB. You have a limited quantity of swaps until the traces burn and die. If this thing was resistive like a normal contact based switch, I would still use an open housing, simply because is better. Yes, you have to be a bit more creative, make a sandwich assembly and ensure to have a PCB, but come on, you can deep clean this thing as many times as you want.
C)I get the point with make switches that are shorter, but, why thinner? Beamsprings are the kings of stabilization, maybe because of the crazy amount of surface they cover, on the other side of the coin, Mitsumi miniature mechanicals suck because of their microscopic size. Come on, engineers, make your switches THICC.

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Go-Kart

07 Apr 2021, 13:53

I like this idea. I can see how that B2H vid got the cogs turning.

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Muirium
µ

07 Apr 2021, 14:23

I might be a bit thicc. Could use an animation of this design in action to help me understand which bits move where and when. :P

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PlacaFromHell

07 Apr 2021, 23:44

I have other switch concepts modeled, mostly magnetic separation. They share the mounting method, sensing and size. This looks easier to produce than the others.
As soon as I can I will create a Solidworks animation, first time doing one.

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PlacaFromHell

08 Apr 2021, 09:43

Muirium wrote:
07 Apr 2021, 14:23
I might be a bit thicc. Could use an animation of this design in action to help me understand which bits move where and when. :P
Some modifications aside, here it is (don't mind the weird oscilation after the click, Solidworks insists on doing it)
It's quite simple, when the magnets in the slider bypass the magnets in the clicker, the force of them repelling one to the other makes the clicker go straight up as it pushes the slider down, producing a sort of sudden collapse like buckling springs or other switches with similar nature.

EDIT: cutted some weird frames in Sony Vegas

User avatar
Muirium
µ

08 Apr 2021, 10:17

Actually, that's kind of what I was imagining. A video loop of the whole stroke we could stare at for a while would be good, though, because the bit of the stroke I'm having trouble with is at the end. Can you push the slider down into the clicker once they've already collided? What's holding the clicker up?

I like the idea of magnets giving a tactile hump. Feels like there's a lot you could tweak in this design, between the magnets and the springs, to give different flavours of the switch; with differently coloured sliders, as tradition demands!

HuBandiT

09 Apr 2021, 02:22

And then you could change one of the two pieces to use electromagnets, computer-controlled – turning the switch into a Voice Coil Actuator, which would give you force feed back, so your users can fiddle with the flavour per-switch, (macro) layers could switch keys between flavours on the fly according to the layer/function the key has in the layer, etc. Plus it would give you some ability to sense the speed of the motion of the key (from which you can infer the position of the key), to be used for more functions... for example, playing music (with force feedback emulating the kickback/sluggishness of the mechanism of a real piano), or the user could set the trigger point to be lower or higher depending on use (gaming, typing), or you could provide software (or provide the raw key velocity/position data to software to be written by others) that automatically infers a trigger point (e.g. if I am typing, and only semi-press a key, the system could infer from the text being typed whether I intended to press it or not).

Some of this was meant to be in jest. But I'm not telling you which parts. :P

User avatar
PlacaFromHell

09 Apr 2021, 03:35

Muirium wrote:
08 Apr 2021, 10:17
Can you push the slider down into the clicker once they've already collided? What's holding the clicker up?
Yes, the switch has the tactile event right after 2mm, while still having 4mm travel. The clicker is suposed to be holded by the magnetic field of the slider's magnets, but if by any reason goes a bit down, it still is far enough from the PCB to be sensed as pressed.
HuBandiT wrote:
09 Apr 2021, 02:22
And then you could change one of the two pieces to use electromagnets, computer-controlled – turning the switch into a Voice Coil Actuator, which would give you force feed back, so your users can fiddle with the flavour per-switch, (macro) layers could switch keys between flavours on the fly according to the layer/function the key has in the layer, etc. Plus it would give you some ability to sense the speed of the motion of the key (from which you can infer the position of the key), to be used for more functions... for example, playing music (with force feedback emulating the kickback/sluggishness of the mechanism of a real piano), or the user could set the trigger point to be lower or higher depending on use (gaming, typing), or you could provide software (or provide the raw key velocity/position data to software to be written by others) that automatically infers a trigger point (e.g. if I am typing, and only semi-press a key, the system could infer from the text being typed whether I intended to press it or not).

Some of this was meant to be in jest. But I'm not telling you which parts. :P
Sir, this is a christian thread :x (joke)

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