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For Clare-Pendar patents, see the Clare-Pendar page.

General switch patents

Known switch types that are yet to be documented anywhere are indicated in bold.

Company Patent Title Filed Published Notes
Willcox US 3290439 A Data encoding keyboard 1963-04-29 1966-12-06 A flat keyboard that in some ways was a precursor to Datanetics elastic diaphragm array
Cherry Electrical Prod US 3644855 A Keyboard reed switch 1970-07-10 1972-02-22 Never observed in the wild; the external design is fairly similar to Cherry M7
Cherry Electrical Prod US 3739127 A Keyboard pulse switch 1972-02-17 1973-06-12 A variant of pre–Serie M7 that causes the contacts to re-open immediately after closing, generating a pulse of current; not known to be in any catalogues
Cherry Electrical Prod US 3849621 A Illuminated push-button switch 1974-05-09 1974-11-19 Cherry M41 corner-illuminated (this design was omitted from Serie M7)
Tokai Communication Ind JP S5276687 A Push button switch 1975-12-23 1977-06-28 Tokai MM9 series
Alps Electric Co., Ltd. US 4153829 A Pushbutton switch assembly 1977-02-16 1979-05-08 Never observed in the wild; the patent depicts an older design of switchplate before SKCC series, suggesting that SKCC series was introduced in 1977 or later
Omron Tateisi Electronics Co JP S53136680 A Keyboard Switch 1977-05-04 1978-11-29 Magnetic tactile and click system within a compact reed switch; the switch depicted is not known, but the magnet system has been found in B2H-F7W which is very similar in shape
Omron Tateisi Electronics Co JP S53136680 A Contactless Keyboard Switch 1979-02-16 1982-08-23 Covers the internally-sprung centre illumination system found in B2R and B2H, depicted in a Hall effect switch largely identical to B2R; the alternate action mechanism is also covered, although it seems not to match up with the provisions made on B2R, and this arrangement is seemingly also extendable to tactility (based on a fragmentary translation)
Omron Tateisi Electronics Co JP S55105916 A Method of Producing Illumination Keyboard Switch 1979-02-06 1980-08-14 Covers the Hall effect arrangement in B2H and the Hall equivalent to B2R
Omron Tateisi Electronics Co JP S5743324 A Electrostatic Capacitance Type Keyboard Switch 1980-08-26 1982-03-11 Some kind of foam and foil arrangement, with an optional spring-over-foam arrangement to get a more linear feel
Omron Tateisi Electronics Co JP S5746418 A Electrostatic Capacitive Keyboard Switch 1980-09-02 1982-03-16 A revision of the previous patent to include Topre-like springs, possibly over some kind of rubber mat (a translation would make things clearer)
Omron Tateisi Electronics Co JP S5750721 A Electrostatic Capacitive Keyboard Switch 1980-09-12 1982-03-25 A revision of JP S5743324 A (some kind of foam and foil including spring over foam); a translation would reveal the specifics
Omron Tateisi Electronics Co JP S5755014 A Electrostatic Capacitance Type Keyboard Switch 1980-09-19 1982-04-01 A revision of JP S5746418 A (foam and foil, and Topre-like springs)
SMK KK JP S6017 A Switch Element and Method of Producing the Same 1983-06-15 1985-01-05 Mitsumi/Hosiden–style contact assembly fitted to a J-M0404–style switch; never seen in the wild
SMK KK JP S60243912 A Method of Producing Switch Element 1984-05-17 1985-12-03 Mitsumi/Hosiden–style contact assembly fitted to a proto–second generation switch; never seen in the wild
Fujitsu Ltd US 4803316 A Push button switch using dome spring and switch element thereof 1986-10-16 1989-02-07 Fujitsu lever action
Omron Tateisi Electronics Co. US 5015811 A Snap-action pushbutton switch with click sound 1989-06-13 1991-05-14 Inverted, moving click leaf design for Omron B3G-S switches; never observed in the wild
Silitek Corporation US 5310973 A Structure of key switch 1991-10-08 1994-05-10 Alternative patent for Silitek (MX mount) dome with slider
Tokai Communication Ind JP H07220561 A Contactless switch 1994-02-01 1995-08-18 Optoelectronic adaptation of Tokai MM9 series, never observed in the wild; patent filed ten months before that of Tokai SPT-0101
Silitek Corporation US 6184481 B1 Key switches for computer keyboards 1994-03-30 2001-02-06 (!) Silitek (Alps mount) dome with slider
Focus Electronic Co Ltd US 5442152 A Computer key switch 1994-09-28 1995-08-15 Focus spring over dome — a clicky dome switch similar to Fujitsu Peerless; the click sound is attributed to “barbs” within the spring tube hitting some part of the tube within the slider in which it fits
Tokai Communication Ind JP H08167361 A Semiconductor photocoupling switch 1994-12-12 1996-06-25 Tokai SPT-0101
Silitek Corp US 5938009 A Key switch for a keyboard 1998-08-24 1999-08-17 Silitek spring over dome — a clicky dome switch similar to Fujitsu Peerless (the sudden extension of the coil spring is said to generate the click sound)

Scissor switch patents

Just listing the priority dates for these as the new Google Patents site doesn’t want to make filing dates easy to access when exploring patents. Note that non-crossed designs (where the two arms are not attached to each other and do not scissor) are also included, and are marked “non-cross”.

This list also covers stabiliser arrangements with scissor arms, as these appear to be precursors to modern scissor switches.

Company Patent Title Priority Notes
General Instrument Corporation US 4433225 A Keytop levelling mechanism 1983-02-22 This is a stabiliser design in the form of scissor arms
Brother Industries Ltd US 5278374 A Assembly with an asymmetrical resilient spring 1992-02-14
Brother Industries Ltd US 5463195 A Key switch 1993-01-06
Nagano Fujitsu Component Ltd US 5874696 A Key switch, keyboard and portable information processing unit with keyboard 1996-08-12 Non-cross
Fujitsu Ltd JP H11185564 A Key switch, keyboard and information processor using these 1997-12-22 Non-cross
Nagano Fujitsu Component Ltd US 6118092 A Key switch for keyboard 1998-09-22 Non-cross
Fujitsu Ltd, Nagano Fujitsu Component Ltd US 6257782 B1 Key switch with sliding mechanism and keyboard 1998-06-18 Suggested to be spring-over-membrane
SMK Corp US 6297461 B1 Key switches for computer keyboards 1999-12-17 Both leaf spring and dome actuators are implied
Behavior Technical Computer Corp US 6572289 B2 Pushbutton structure of keyboard 2001-06-28
Minebea Co Ltd US 6759614 B2 Keyboard switch 2002-02-27
Fujitsu Component Ltd US 7138587 B2 Key switch, keyboard and key-switch assembling jig 2004-07-01 Non-cross
Fujitsu Component Ltd US 8624140 B2 Key switch and keyboard 2006-07-10 Non-cross

Other keyboard-related patents

The following table covers patents for aspects of keyboards other than keystroke sensing. In particular, it lists patents for mechanical shift lock mechanisms. These do not use alternate action switches. Instead, pressing shift lock causes a special mechanism (external to the switch) to hold the key down, and pressing either shift key (or just left shift, if right shift is not connected) releases shift lock. Mechanical shift lock mimiced the shift lock mechanism on manual typewriters, where the shift mechanism could be locked in place for convenient entry of capitalised text.

Also covered are stabiliser mechanisms that do not use scissor arms; those types with scissor arms are covered above alongside scissor switches.

Company Patent Title Filed Published Notes
CLARE PENDAR Co US 3626120 A Key-locking assembly 1970-09-30 1971-12-07 Mechanical shift lock mechanism; here, the keycap itself operates the release mechanism
Cherry Electrical Prod US 3678255 A Mechanical key lock-in 1971-06-18 1972-07-18 Mechanical shift lock mechanism, used by M61-0300/0310/0500/0510 (early 1970s) and later M61-0025/0026/0027/0028 (by the late 70s)
Cherry Electrical Prod US 3711685 A Keyboard switch actuator 1971-12-27 1973-01-16 Cherry paddle-type stabiliser, as seen in B70-05AB; replaced with the wire-type stabiliser
Burroughs Corp US 4010838 A Spacer bar mechanism 1975-01-17 1977-03-08 Space bar stabiliser
Cherry Electrical Products Corp US 4188136 A Keyboard switch actuator and locking assembly 1978-01-19 1980-02-12 The Cherry stabiliser arrangement (wire-type), plus a mechanical shift lock mechanism (unclear switch types)
Illinois Tool Works Inc US 4295012 A Secretarial shift mechanism for an electric keyboard 1980-02-04 1981-10-13 Mechanical shift lock mechanism

Funny terminology

membrane sheet
“plunger” according to Omron
Another term for scissors
spacer bar
An old term for space bar