Shigemitsu Yamaoka

Touch‐responsive control apparatus for electronic musical instruments

A key-speed-responsive volume control apparatus for a keyboard-type electronic musical instrument includes a key switch associated with a key of the instrument, wherein a movable contact of the key switch moves out of engagement with a break contact and into engagement with a make contact upon depression of the key. A capacitor is charged following the movement of the movable contact out of engagement with the break contact and before engagement with the make contact. The capacitor is made to discharge at a first prescribed rate immediately after charging until the movable contact comes into engagement with the make contact, and then at a second prescribed rate until the movable contact disengages the make contact upon release of the key. The terminal voltage of the capacitor when the movable contact comes into engagement with the make contact is utilized for controlling the amplitude of a tone source signal corresponding to the depressed key, thereby providing a tone signal having an initial amplitude determined in accordance with the speed of key depression. Necessitating the use of only one capacitor for each key, the apparatus is suitable for fabrication in the form of an integrated circuit.