IKOR

Contents

• History
• Capacitive encoding
• Documentation

History

IKOR, Inc. was (amongst other things) an American keyboard manufacturer. IKOR, Inc. was founded on the 16th of March 1965 as a Massachusetts company located in Boston. On the 6th of July 1966 they relocated to Burlington in the Boston outskirts. On the 3rd of April 1969, IKOR Incorporated was created in Delaware, over 280 miles away, and registered in Massachusetts on the 30th September. IKOR, Inc. merged into IKOR Incorporated on the 9th of May 1969, in the process becoming the Massachusetts branch of IKOR Incorporated. IKOR Incorporated of Massachusetts closed on the 14th of November 1994; the situation of the Delaware parent company is unclear.

A separate IKOR Incorporated was set up in Pennsylvania on the 2nd of August 1996; whether this is related is not known.

Donald Gove, inventor of IKOR’s self-encoding capacitive switch arrangement, was named as a director and the treasurer of Control Devices, Inc. upon its founding in October 1969, suggesting that he left IKOR to co-found Control Devices.

Capacitive encoding

IKOR invented what may be an encoding technique unique to them: a capacitive encoder. Each switch (or specifically each row of switches) is provided with a pair of back-to-back AC emitter strips. Each emitter strip is plated with a dieletric layer and then a conductive layer above that, forming an electrostatic shield. Apertures in this shield allow the electromagnetic field to emanate at specific positions. These positions are sensed capacitively by tracks on a facing PCB. Each PCB track forms a single bit, and in this condition, each track would be energised by the emitter.

Each key is in turn fitted with a pair of metal sheets, each one forming another electrostatic shield, preventing capacitive coupling to the PCB. Holes punched into each shield allow specific bits to be detected once the key is pressed sufficiently far as to allow the holes in the moving shield to line up with the apertures in the emitter and the PCB tracks. The diagram below shows the single-key shield, the sensing PCB and the emitter, broadly in the form described in the patent, but simplified for the purposes of illustration:

The next illustration is an exploded view of these components in operation, demonstrating that the per-key movable shield selects which bits of the output code are enabled:

One advantage of this approach is the ability to reconfigure a keyboard by simply swapping keys around: there is no need to rewire or reconfigure the internals of a switch in order to set a new output code. The design as patented has two separate emitter plates back-to-back and joined together, with inwardly-facing PCB, as shown in the final illustration:

The use of two sets of encoding plates increases the number of output bits per key to a sufficiently usable level. In reality, the two movable shield plates are very close together, at the rear of the key: this is the only part of the workings visible in the magazine advertisement. The rest of the internals are yet to be observed, so the precise form that they take remains unclear, but the magazine article appears to confirm that there is a single, central emiter plate that faces both directions. The article also shows two PCB tracks for each sensing position, unlike the patent.

The patents are not easy to understand, and it’s not clear whether they address the problem of overtravel, and the risk of the switch being operated twice during the press and release portions of each keystroke. The diagram in the 1967 article does not match the patent, and it appears that by 1968 the design was revised again.

Only only model is described, Model 600, and thus far no such keyboard is known to have been observed. It would appear that IKOR did not remain a keyboard manufacturer for many years.

This technique is covered by two US patents:

Documentation

All documentation was scanned by Bitsavers except where otherwise noted.

• Electronic Keyboard article, Computer Design, November 1967, pages 32–33
• IKOR advertisement, Computer Design, April 1968 (from Marcin Wichary)
• IKOR advertisement, Computer Design, March 1969, page 60