A proof-of-concept prototype of an inductive key position sensor system. A single sensor under each key replaces the two or three switches typically used for velocity and adds linear key position sensing through the whole keystroke, output as a controller. The bottom region of the keystroke may be processed to provide polyphonic aftertouch, starting at a programmable depth of the full keystroke.
In a synthesizer, key position may be used as an expressive performance input for MPE or MIDI 2.0 with a Per-Note Controller. New types of musical expression can be realized, while retaining the standard key action familiar to all keyboard players.
In a digital piano, the accurate key position enables better emulation of an acoustic piano’s key action response.
The key response can be customized to suit any key action. For example, when used in a digital piano, the velocity response can be set to match the velocity curve of the MIDI-CI Profile for Piano. In a synthesizer, one program might have standard velocity, and the next program might have positional expression and polyphonic aftertouch for MPE.
Parts of the keystroke may be partitioned into various control signals. For example, a shallow trigger-on may be utilized, followed by position data on the MIDI Brightness CC, to end the stroke with polyphonic aftertouch. The user will be able to fine-tune the keyboard keystroke sensitivity.
The raw position data is also post-processed on the module to provide instantaneous velocity and acceleration outputs. These additional instantaneous outputs may be used as further MIDI control signals for highly expressive synthesizer patches.
