Ericsson type 1121 / Ericsson RMD 973

[seebart]

We've had this keyboard before here at DT, these do not show up that often. This Ericsson terminal keyboard uses the Ericsson RMD 973 linear PCB mounted switch. I found two similair keyboards online that were part of the Ericsson Portable PC and and the Ericsson 8088. I cannot see a production date anywhere that makes sense to me.

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DT Wiki:

Ericsson RMD 973 (formerly known as the "ICL switch") is a series of keyboard switches produced by Ericsson. These switches are comparatively rare and very little is known about them. The base of the switch contains the Ericsson logo and "RMD 973".[1] Since several switch types have "RMD 973" written in the mould, it seems fair to assume that this is the series name; the mould is more likely to contain the series name than part numbers. These switches are found in keyboards made by ICL, Ericsson, Nokia Data, Bundespost Telekom and Philips.

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The Ericsson RMD 973 switch works in that the bottom part of the white slider sits on a spring inside a duct in the center of the switch floor. When the switch is pressed the horizontal bar on the white slider presses the horizontal metal contact leaf upward.

The actual movement of the bottom of the slider in the duct therefore has nothing to do with the actual switch mechanism other than the movement. The white slider is held in position in two little vertical recesses on either side of the switch housing. I hope you can see all this in my pictures.

wiki/Ericsson_RMD_973_series

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On my personal switch smoothness scale this Ericsson RMD 973 switch can compete with 1985 MX blacks or NMB HI-TEK linears. Not shabby at all. There is no tactile feedback.

Key stabilization is interesting, the metal bars hook into the switch housing and snap into plastic plates that snap into the top inside of the keycap for the larger keys.

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The whole keyboard is pretty low-profile with some very sturdy "drop down feet".

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[terrycherry]

I hope to see which switches it has for long times. Glad you got and shot this.
Thanks to seebart.^^

[pyrelink]

What a sleek keyboard. Really cool way to do stabilizers too. How do the stabilized keys feel?

[Chyros]

I see, so this is actually quite close to the mechanism of Rafi contact switches. Interesting, thanks for the post .

[seebart]

Thanks guys;

pyrelink, I'd say this is the most effective key-stablilization solution I have ever seen. Hit the key anywhere and you still get super conform keypress, I don't feel those little plastic plates inside the keycap. Of course this involves more parts also. Now for the spacebar Ericsson had to go the regualr way:

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The printing on the keycaps is less than desirable but the brownish color is nice:

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Ugh, forgot the PCB shot:

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Like I said I only managed to find similair Ericsson keyboards online, not this exact terminal version.

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[jacobolus]

Thanks for all the pictures!

The plastic-peg-in-plastic-cylinder slider design looks pretty well shielded from dust, and assuming the plastic parts have reasonably low enough friction, probably also does a good job of keeping the switch stable / preventing binding from off-axis presses.