Cortron and Licon
- Switch types
This page is at present an overview of ITW Licon and early ITW Cortron keyboards. Details on the product families is fairly scarce still.
The general pattern seems to be as follows:
|Keyboard part||PCB part||Possible series||Switch type|
|55-xxxxxx||80-55xxxx||Series 550?||Ferrite core, early|
|35-xxxxxx||80-35xxxx||Ferrite core, intermediate|
|25-xxxxxx||80-25xxxx||Series FC2500?||Ferrite core, low-profile|
Note that the third and fourth digits of the PCB part number correspond to the first two digits of the keyboard part number.
These are solid state switches which are sensed by controlling whether or not current will pass inductively from one wire to another through a ferrite core. They have been referred to as “magnetic valve” switches, but in advertisements from Licon and ITW, they are described as “ferrite core”. Here, the magnet in the plunger suppresses the inductance, and when the plunger is depressed, the inductance is enabled and the key will be detected. These solid state switches are almost the same age as Micro Switch SW, which is a Hall effect solid state keyboard series.
In most cases, the older switches are all Micro Switch mount. The DIN-compliant types use a German-style snap on mount, the compatibility of which with German switches is not confirmed. However, HP 264XX Data Terminal keyboards use early ferrite core switches with a cruciform mount, whose keycaps fit onto Alps Series KCC switches:
The technical literature for the simplified keyboard from this series—from August 1976—gives only HP part numbers for the “LICON” switches used.
The oldest switches are known from the Series 550 keyboard advertisement from December 1970. Although these have never been directly observed, keyboard model 55-100007 could potentially have these switches on account of its height. These earliest switches are very tall.
In Electronic Engineer magazine’s this is your keyboard reference from 1971 depicts the next known variant of early ferrite core switches. The main change is that the switch is substantially shorter, with the lower portion of the shell removed. These can be seen in model 55-500003 Univac Uniscope 100 keyboard from 1975.
US patent 4017850, filed in 1976 and granted in 1977, depicts a redesign of the switch. This new design is the most commonly-occurring form of the switch. The size appears to be unchanged, but the switch shell was redesigned, making it quite distinct from the previous form.
US patent 4028696, filed around the same time, depicts the double action version of the switch, exactly as found in an HP 9845 workstation keyboard. This switch is substantially taller than the standard switches.
These are surprisingly tall switches considering that they are a complete redesign. The same shell appears to support both ferrite core and mechanical contacts.
The low-profile switches appear to be related to FC2500 series keyboards, which appear to have been created to meet the infamous German standards. These keyboards were advertised as being available in linear and tactile forms, but they are only found in tactile form using buckling rubber sleeves.
This is a capacitive keyboard that uses a leaf spring under each key instead of a foam pad with foil attached. The design is very similar to Digitran metal leaf capacitive switches. The example below has a series of patents on the label but the switch patents thereon are for ferrite core switches.
This is a series of tall switches that were advertised in Modern Data, December 1970. The rated lifetime was 25 million cycles. These are older than any of the known patents for ferrite core switches from this group of companies. The design is similar to the “first generation” of so-called “ITW magnetic valve” switches, but considerably taller. Although the switch is illustrated in the magazine, the plunger is not. (It is not clear whether Licon or Micro Switch designed the keycap mount that they shared.)
Cortron suggested series 55 or 65 for the ferrite core switches, and possibly E3 or E4 for the mechanical versions. While they do have literature, they have not been willing to share anything more. Licon and ITW switch series names are often two-digit numbers that form the prefix of part numbers, e.g. part 11-304 is in Series 11, part 49-59113 is in Series 49-59W, and part 034-550-006 is in Series 034. Since older keyboards have model numbers beginning “55-”, this suggests that the switches were indeed Series 55.
These keyboards feature two similar designs of what were previously termed “first generation”. These keyboards list US patent 3035253 filed by George C Devol on magnetic storage.
Series 54 “solid-state” keyswitches got a brief mention in Computerworld, 31st of May 1976. They may not be computer keyboard switches: the details given are very brief. These may not be ferrite core either, but it seems likely that they would be.
In Interface Age, August 1981 on pages 132 and 134, there is a brief mention of the Cortron CP-4550 keyboard, which uses the “CP-4550 keyswitch”. This switch is said to give an “exceptional, true linear feel” and is “environmentally superior to foam pad design approaches”. The rated lifetime is in excess of 100 million cycles.
The Recent Microsystems Announcements from Computer magazine, June 1981 cites this model as being a “Solid-state, capacitance unit”, with a unit price of $45 in volume quantity ($127 in June 2019).
The comparison with foam and foil indicates that it uses a different mechanism, with the Digitran-like capacitive system in model 45-500008 being the likely candidate considering that both use “45” as part of their respective identities.
US patent 4352144 filed in January 1981 depicts a metal leaf capacitive arrangement where the plunger contains a flexible prong that provides overtravel. However, model 45-500008 listed below (a Xerox 820-II keyboard) uses a Digitran-like design where a portion of the capacitive leaf serves to provide the overtravel instead.
In Computerworld, 28th March 1983, Illinois Tool Works advertised Series FC2500 keyboards. These are described as “low-profile” and offered linear and tactile options. In Computerworld, 2nd July 1984 it is also noted that these keyboards were reported to meet a 30 mm height requirement. There is a good chance that Series FC2500 is the low-profile type that was later manufactured by Devlin in the UK, as the description and date of introduction suggest DIN-compliance. In neither case were any illustrations provided.
The article La Tastiera in the Italian magazine Selezione di elettronica e microcomputer from June 1985 contains the following description of Series FC2500 on page 59:
Tastiera ITW Cortron con feedback sia tattile che visivo. Il modello FC2500 emette un suono simile a quello di un grillo quando viene premuto un tasto. Essa adotta la tecnologia a ferrite; il feedback tattile è fornito da interruttori a cupola.
This translates to:
ITW Cortron keyboard with both tactile and visual feedback. The FC2500 model emits a sound similar to a cricket when a key is pressed. It adopts ferrite technology; tactile feedback is provided by dome switches.
Computer Weekly (supplement) 5th of January 1984 announced the launch of an unspecified series of Cortron ferrite core keyboards, noting:
The low profile keyswitch measures 17.1 mm high with keytop, 21.9 mm, and has a full travel of 4mm. Keyswitches can be provided with linear or tactile feel.
The following is a list of known Licon and Cortron keyboard models with both the switch type and part numbers known, arranged in date order:
|Part number||PCB number||Manufacturer||Switches||Serial||Date||Notes||Reference|
|55-100007||80-550461||Licon||Ferrite core, early Ⅰ or Ⅱ||7131||eBay|
|55-500003||80-550782 REV G||Licon||Ferrite core, early Ⅱ||005315||7585||Univac Uniscope 100 keyboard||Deskthority|
|55-500140||80-550932 REV F||Licon||Ferrite core, early Ⅲ||59710||7621||Unidentified keyboard||eBay|
|55-500161||80-551093 REV. J||Cortron||Ferrite core, early Ⅲ||293869||7934||Raytheon model 6101-04||Deskthority|
|55-500056||80-551101 REV D||Cortron||Ferrite core, early Ⅲ||346831||8004||Unspecified Raytheon model||Deskthority|
|55-500135||80-551478 REV. B||Cortron (Licon PCB)||Ferrite core, early Ⅲ||367693||8012||Double-shot Japanese keycaps||Flickr|
|55-500539||80-551879||Cortron||Ferrite core, early Ⅲ||370322||8016||Xerox X998; part of the case is from 1982||Flickr|
|55-500219||80-551655 REV.B||Cortron||Ferrite core, early Ⅲ||406859||8030||Unknown origin||imgur.com|
|55-500219||80-551655||Cortron||Ferrite core, early Ⅲ||8107||Unknown origin||eBay|
|35-500095||80-350128 REV. A||Cortron||Ferrite core, intermediate||526148||8133||Unidentified Univac keyboard||Flickr|
|45-500008||?||Cortron||Digitran-like metal leaf||1009281||8314||Xerox 820-II keyboard||q7.neurotica.com|
|?||80-350128 REV. A||Cortron||Ferrite core, intermediate||?||~1983||Prime/Pr1me ESA 5146 keyboard||Deskthority|
|55-500582||80-551646 REV. C||Cortron||Ferrite core, early Ⅲ||1029395||8406||Unidentified keyboard||Deskthority|
|25-500035||80-250092 REV C||Cortron||Ferrite core, low-profile||1019362||8438||Xerox 820-II keyboard||Flickr|
|25-500200||80-250177 REV. H||Cortron||Ferrite core, low-profile||112122||8630||Burroughs B25 K1 AB||Deskthority|
The serial numbers appear to be monotonic, but on at least two occasions ITW seem to have started a new numbering range. The Taiwan-made example has a serial number from a separate system.