Jack Constantly Controlled Patents (Class 84/247)
  • Patent number: 5272950
    Abstract: In a striking mechanism (1) for a piano, grand piano, or similar string instrument the power for the key (8a) is transferred to the hammer (3) via a rod system (10, 11, and 12) so adapted that the connection of the key (8a) and the hammer (3) is never interrupted. The rod system (10, 11, and 12) is supported during the striking movement against deflection by a first guide boss or roller (18) supported by a first curve guide (19), and during the return movement by a second guide boss or roller (20) supported by a second curve guide (21). The first curve guide (19) can swing between a first, advanced position in which it is releasably locked by a locking pawl (28) and the rod system is capable of causing the hammer (3) to touch the string when the key (8a) is pressed down, and a released second retracted position in which this is no longer possible. This ensures that the hammer (3) is withdrawn so rapidly after having struck the string (2) that the string can vibrate freely and deliver its note.
    Type: Grant
    Filed: May 15, 1992
    Date of Patent: December 28, 1993
    Inventor: Erik I. Petersen
  • Patent number: 5249497
    Abstract: A keyboard apparatus for an electronic musical instrument has a jack which is movable and rotatable by a force to be transmitted from a key, and a hammer which is rotatable by a force to be transmitted from the jack. The jack is rotatably engaged by a fulcrum which is provided in the key. The jack is urged to its original position by a spring. The key has a return load applying portion which abuts the hammer when the hammer rotated by the jack returns to its original position.
    Type: Grant
    Filed: April 13, 1992
    Date of Patent: October 5, 1993
    Assignee: Kabushiki Kaisha Kawai Gakki Seisakusho
    Inventor: Shinji Niitsuma
  • Patent number: 4896577
    Abstract: The subject action is a modification of the traditional upright action. The traditional jack spring is eliminated. Its function is assumed by a jack/repetition spring, which is a compression spring adjustably mounted between the jack near the end that engages the hammer butt and a pilot attached to the back stop portion of the hammer assembly. The hammer return spring mounting enables adjustment of the range of force applied by the spring to the hammer. The force range magnitude is such that the hammer return torque is commensurate to the torque that would be applied by gravity if the hammer shank were mounted horizontally instead of vertically. The operating force of the jack/repetition spring is related to that of the hammer return spring in such a way that re-engagement of the jack with the hammer butt is assured before hammer return beyond the back-checked point.
    Type: Grant
    Filed: October 2, 1987
    Date of Patent: January 30, 1990
    Inventors: Chris A. Trivelas, Darrell G. Fandrich
  • Patent number: 4840101
    Abstract: The prolongation of a jack in the escapement mechanism of an upright piano is provided with a repetition lever having a roller that is engageable with a vertically adjustable repetition button positioned beneath the roller so that priming of the mechanism begins from the moment the wippen enters its downstroke movement.
    Type: Grant
    Filed: September 26, 1988
    Date of Patent: June 20, 1989
    Inventor: Fernand Kummer