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Measuring Piano Key Action Damper Events across the Keystroke Disclosure Number: IPCOM000237809D
Publication Date: 2014-Jul-14

Publishing Venue

The Prior Art Database

Related People

Hugh Richard Voit II: INVENTOR

Related Documents

U.S. patent 8,049,090: PATENT [+3]


This article deals with forces and events that occur during a piano key's stroke, when the sustain pedal of the piano is not disengaged. The article describes the continuous measurement of damper forces encountered during a piano key's downstroke and upstroke. In addition to damper down force (damper down weight) and damper balance force, a means and method is discussed for determining the damper engagement point (damper start point) in the keystroke.

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This is the abbreviated version, containing approximately 15% of the total text.

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Measuring Damper Forces at the Piano Key, using a Well-Controlled Plunger and Simultaneous Reaction Force Measurement

    There is a longstanding practice of measuring "static" values of Down Weight, Up Weight, and (indirectly) Balance Weight and Friction, by applying "gram weights" to the keys of the piano action. New methods and apparatus were disclosed in U.S. Patent 8,049,090, "Apparatus and Method for Actuating Keyboard Mechanisms and Evaluating..." [ref. 1], by Rick Voit, which eliminated the need for the old "gram weight" techniques, producing more scientific and repeatable results. These new methods involved reaction forces at the Application Point (AP) of the key being measured continuously during constant-speed downstrokes and upstrokes, resulting in continuous force data for the stroke. Sophisticated equipment is required for both the well-controlled movement and the continuous force acquisition. In addition, averages of these forces were described, being declared as "replacements" for the old parameters of Down Weight, Up Weight, Balance Weight and Friction Weight. Additional information was disclosed, regarding all of these continuous "static" forces, in the article "The Key Force One: Measuring Real and Continuous "Static" Forces at the Key", pp. 19-23 of The Piano Technicians Journal, November 2013 [ref. 2]. The current disclosure discusses nearly identical techniques as those, but extended to the case where the damper levers (i.e. the sustain pedal mechanisms) are not temporarily disengaged or removed from the backs of the individual notes.

    The structure and means of providing the well-controlled plunger, and the continuous reaction force measurement at the AP, may be identical with those discussed in references 1 and
2. The main goals will include:

− for any given note, determine the added "down force" produced, due to the damper lever (or damper underlever) becoming engaged on a controlled downstroke,
− for any given note, determine the added "up force" produced by the engaged damper lever (or damper underlever), during that region of a controlled upstroke,
− for any given note, determine the additional friction created in the keystroke, by the engagement and movement of the damper lever,
− for any given note, determine the additional "balance force" created by an engaged damper lever


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− for any given note, determine the point in the keystroke - relative to either the "at rest" key position or some "zero position/plane" - where the damper lever begins to engage the key mechanism on a downstroke, or disengage the key mechanism on an upstroke. This point represents that key mechanism's Damper Engagement Point (or damper start point), which is more specifically defined below.

    The forces measured (and the forces indirectly calculated from those) are continuous in nature, and can be easily graphed as a function of plunger and/or key travel. The terms Down F...