Keyboard Patents

Catastrophically buckling compression column switch and actuator:
This is the original buckling springs patent. It does not share a lot in common with the later applied mechanisms used on the Model Fs and Ms, but it describes three related mechanisms based around a spring located in a barrel, like the later designs.

Toggle mechanism:
This is the earliest patent available describing the IBM beam spring switch - the rest of world filing of US18358371A from 24 September 1971 (of which I am currently unable to locate). The components of the switch and the mechanism's assembly are described and several diagrams are given.

Buckling spring torsional snap actuator:
Describes the IBM Model F's capacitive buckling springs switches, the applied form of Richard Hunter Harris' earlier patent regarding a similar design.

Rocking switch actuator for a low force membrane contact switch:
Describes the IBM Model M's membrane buckling springs switches, an adaptation of Richard Hunter Harris' capacitive design for use with a membrane contact sheet.

Analog input device located in the primary typing area of a keyboard:
The original TrackPoint-spawning patent that describes both a pointing stick device and an under-keycap mounted device that can make use of strain gauges or various other alternative technologies for sensing movement with a pointing stick.

Graphical user interface cursor positioning device having a negative inertia transfer function:
Describes the formula used for implementing the "negative inertia" feature found in TrackPoint III and IV pointing sticks. Negative inertia counteracts the feeling of sluggishness (ie, having inertia) via acceleration and is implemented in the TrackPoint module's firmware and thus applied before the data for cursor movement reaches the host PC.

Capacitive pointing stick:
Describes the force-sensing capacitor (FSC) technology behind the Synaptics TouchStyk pointing stick. The TouchStyk is competing technology against IBM/Lenovo TrackPoint that found its way into several IBM integrated pointing device and UltraNav keyboards (the SK-8835/8840/8845 family).