One day I was wandering GoodWill and I saw a giant Alpha 2015 typewriter for $13. I popped off one of the caps as I usually do on these things (to see if the caps are worth harvesting) and saw that it looked like a cherry MX mount. I bought the thing and brought it home and later found out from your Wiki that it was a Type 1 Mitsumi Standard Mechanical board. I knew I had something interesting when I realized some of them were different colors from the ones on the Wiki, so i went ahead and disassembled the typewriter.
Inside, serving as the sensor switch for the swing bar that holds the paper to the roller was a Mitsumi switch very different from the others. It was mounted to the plate, with 4 wires coming off of it. I recalled from the wiki that there were 4 holes, "implying" a DPST variant, so I registered for an account and here I am.
In addition, there are several different weighted switches identifiable by color. The Blacks are very heavy for caps lock and such, the yellows are very light because they used 2 lightweight switches instead of one normal switch and a stabilizer, and the whites are normal from what I can tell. Typing is very smooth, I'm guessing typical for a Mitsumi Type 1 board.
On to the good stuff:
http://imgur.com/Se4odRx - Here's the full keyboard without keycaps
http://imgur.com/76nCKoh - Here's the rear of the keyboard which highlights the Nakajima All and Mitsumi branding. Date code hints that the keyboard is from 1984
http://imgur.com/vD3PD1G - This highlights the FLIPPING EPIC THICK doubleshot keycaps that came shipped with this thing
http://imgur.com/okJa8rn - Switch with top popped off to show internal structure
http://imgur.com/lffZ5Pu - Internal structure spread out on the table, with XXX key for good measure. This is switch porn after all
Here's the Album link for all photos: http://imgur.com/a/AagD5
As you can see the switch uses two springs. A light spring for what feels like a normal press and an incredibly heavy spring which requires a considerable amount of force to depress (something impractical for a Rip-o-meter test methinks).
A light press will depress the first spring and trigger the first actuation, then you press harder and the second spring depresses which causes 2 lips near the spring on the slider to depress the little metal tabs on the second part, which triggers the second actuation. It's a really clever switch design. I don't have the nickels required for a Rip-O-Meter test right now, but I'll be sure to attempt to measure the different weights when I have the chance.
EDIT: There appears to be ANOTHER Mitsumi Dual-Stage switch in the BACKSPACE/DELETE key. This makes sense for rapid delete. Press it harder to rapidly delete.
EDIT2: Found 2 more dual-stage switches in the keys to the right of the keyboard to the left of the red LEDS. that makes 4 dual-stage mitsumi switches in this device altogether.
