A key actuation system that is designed for use with a keyboard instrument of
the
type having multiple keys. Each key is pivotally supported and has a front end
that is depressed by a player to play a note. The actuation system includes multiple
actuators that are operable to move at least some of the keys. The actuators together
include a block of ferromagnetic material with a surface with multiple bores defined
in the surface. Each of the bores has a diameter. A winding is positioned in each
of the bores. Each of the windings has a hole. A piston is provided at least partially
in each of the holes, with each piston being in mechanical communication with one
of the keys such that movement of the piston causes movement of the key. Each piston
has a width. A ferromagnetic flux plate with multiple openings is positioned on
the surface of the block of ferromagnetic material with the openings aligned with
the bores. The openings each have a width that is less than the diameter of the
bores, such that the flux plate partially closes off the upper end of each bore.
When the windings are energized, the corresponding piston moves, thereby moving
one of the keys.
