KBK update for Sunday, 23rd May
As far as mysteries go, a five-year resolution is far from the 11-year record for Datanetics DC-60. This mystery relates to the switch type in an unidentifiable Univac-like keyboard, photos that I can see that I archived locally in 2015. The part number cannot be read, and the plungers did not match any other known keyboards, until a Xerox 860 IPS example showed up. This latter find indicated that, whatever this switch is, it was not Univac-specific.
A revisit of ITW’s patents showed a remarkable resemblance to US patent 4352144 “Capacitive keyswitch with overtravel plunger mechanism”, filed in January 1981. The patent was the right age for the Xerox 860 keyboard, and indeed these switches look capacitive. (The patent was also left out of the patents table on my ITW page.)
Finally, further digging turned up details of a Xerox 820 keyboard. This page tied the plunger to Cortron CP-4550, which was their capacitive system. That keyboard is the same model as the Xerox 820-II keyboard shown at q7.neurotica.com, whose gallery of photos lacks a critical detail: the plunger design. Putting both sets of images together, all the implementation details can be seen.
Thus, these mystery plungers are Cortron CP-4550 metal leaf capacitive, a design very closely related to Digitran Golden Touch.
There are still lots of Licon and Cortron discoveries remaining to be made, in particular:
- The mechanical types corresponding to Series 555 and 35-xxxxxx keyboards, both patented
- Confirmed examples of both FC-2550 and FC2500 such that their part numbers can be observed, along with the differences between these two series
- What Series III (ss3) switches look like
- What Series 54 (Superwitch II) switches look like
- What series the 35-xxxxxx keyboards belong to
- The original wired inductive ferrite core keyboards (possibly 55-0xxxxx)
- Another example of the old 55-1xxxxx type, that can be seen in more detail (all the photos of the one known example are all lost)
Some of these details are waiting for me in an envelope on a desk at Cortron, and one day they will be revealed … One day.
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