How do honeywell hall effect switches mechanically work?

[krfkeith]

So obviously they work electronically using the hall effect, but I'm confused as to how they work in terms of the mechanics? I've seen references to "non-contact," is that just referring to the fact that the switch doesn't make contact, or are the keys literally magnetically suspended or something? Does anyone have a cross-section of the switches or anything like that?

[gcb]

"no contact" obviously means it does not touch the signal leads like every other switch. but since it does not "have" to touch anything, the guide design can be as smooth as possible, theoretically. I have never used them.

http://deskthority.net/wiki/Honeywell_Hall_Effect

[mougrim]

Not many people did... not since they stopped manufacturing them.

[BlueBär]

You can find some disassembly pictures here: http://deskthority.net/photos-videos-f8/custom-hall-effect-switch-keyboard-t2857.html

The switch consists of a slider that has a magnet attached to it, held up by a spring. At the bottom of the switch there is a hall effect sensor. If now the slider gets pushed down, the magnet get's closer to the sensor and if it comes close enough current can flow.

Here is another disassembled hall effect switch: https://www.flickr.com/photos/triplehaata/11413991325/in/set-72157638752863983
As you can see it works pretty much the same way, but has two springs and the magnets actually surround the sensor when the slider is pushed down.

[Daniel Beardsmore]

On the DT wiki page, you'll see a link to this document:

Technical document on Honeywell Hall Effect switches

It's 126 pages long, so there shouldn't be anything left unanswered by the end!

I'm hoping that an electronics person can summarise this in a few paragraphs on the wiki, with a few diagrams. You know, Hall Effect Keyswitches for Dummies (the PDF is Hall effect sensing for someone like Feynman or Tesla). Basically split it off from the contact mechanism page into a page of its own.

[Harms]

I always heard of these hall effect switches and how great and godly they are however what makes me wonder is; yea they were so godly then why did they stop production of them? Why doesn't a manufacturer or whoever owns the patent create a modern keyboard out of them it would be sick.

[esko997]

I always heard of these hall effect switches and how great and godly they are however what makes me wonder is; yea they were so godly then why did they stop production of them? Why doesn't a manufacturer or whoever owns the patent create a modern keyboard out of them it would be sick.

Have also wondered this -- why did they just die, and no one scooped up the manufacturing rights?

Maybe its not that simple. \/(' .')\/

[mougrim]

It's simple. At that time it stopped to be profitable

[BlueBär]

I always heard of these hall effect switches and how great and godly they are however what makes me wonder is; yea they were so godly then why did they stop production of them? Why doesn't a manufacturer or whoever owns the patent create a modern keyboard out of them it would be sick.

They're probably fairly expensive to produce.

[dorkvader]

On the DT wiki page, you'll see a link to this document:

Technical document on Honeywell Hall Effect switches

It's 126 pages long, so there shouldn't be anything left unanswered by the end!

I'm hoping that an electronics person can summarise this in a few paragraphs on the wiki, with a few diagrams. You know, Hall Effect Keyswitches for Dummies (the PDF is Hall effect sensing for someone like Feynman or Tesla). Basically split it off from the contact mechanism page into a page of its own.

I've read this document through a few times. While it is excellent, only a few pages pertain to hall effect sensors in keyboards. The document itself is a design guide showing what is possible with hall senors and switches in general.

about patents: both types were introduced in the 1970's so patents have expired.

The disassembly of the "dual magnet" type shows how they work quite well (and shows the awesome window over the hall sensor. You can see the discrete components on it!) Both types work the same: a magnet is embedded in the stem and the stem uses a spring to hold itself up. When your press it down past the hall sensor, the gauss increases. When it's past a certain threshold value (as set by the hall sensor and not changeable) the hall sensor outputs 5V.

Now how does the hall sensor itself actually work...? I recommend taking a class in semiconductors and/or nanotechnology. It can get quite complicated. The easy answer is just "it's a material property that just does that". Then there's amplifiers after it, etc.

There were options (see the long document) to get hall sensors with hysterisis, etc. but from what I have been able to determine, weren't ever implemented in a keyboard switch.

I encourage anyone interested to actually read the document. Most of the information you need to understand this is at the very beginning. The bulk of it focuses on numerous applications.

[ander]

Okay, I know this thread's from last year, and you'll probably give me a hard time about posting to it again—but I really thought this would interest you peeps: It's a great video by a physics prof in the UK that shows quite clearly how the Hall Effect works.

When flowing electrons (i.e. electricity) encounter a magnetic field, they change direction. So by moving a small magnet closer to current, you can cause a switching effect—and because there's no physical contact, there are no switch contacts to wear out.

This may seem like an idea type of long-life KB switch. Unfortunately, as the prof shows, it even works through metal. (Even though some metals are attracted to a magnetic field, they don't block it; it continues right through them.) This, I imagine, was where Hall Effect boards became impractical: The switches had to be precisely designed and positioned so the magnetism of one wouldn't wander over to other switches and activate them too.

Okay, back to the lab with this topical corpse... Buh ha ha!!

[Bucake]

beautiful switch! i wish i had a board with them

[CaplockJack]

Maybe they will come back!

[ander]

Yeah, it's a pretty cool concept.

Don't worry, though—pretty soon we'll have quantum keyboards that will create characters based on the likelihood that we've already typed them in alternate universe. Now that'll be smooth.