This invention relates to key operated percussion devices such as grand pianos and, more specifically, to the “actions” of such devices. A piano action transmits motion from the pianist's fingers to the piano strings.
The grand piano is a mature product that has remained relatively unchanged for nearly 100 years. Pianists, in general, must spend many years playing a piano in order to develop their technique. As a result, pianists, generally, prefer traditional piano actions because they learned to play on traditional piano actions which have remained unchanged. Traditional piano actions are made of wood. Typically, hornbeam or maple is used.
Relative to more modern materials, such as composites or plastics, wood is an inefficient raw material from which to manufacture piano action components. Wood action pieces must be drilled to produce the holes required for pivotal connections and assembly with other action components. The hole-drilling process is a laborious and costly process as compared to the production of molded piano action pieces with holes accurately formed therein during the initial molding process.
Wood is hydroscopic, i.e. wood swells or shrinks as its moisture content changes in response to the environment. This can cause binding in the action. Additionally, after repeated occurrences, this causes compression of the wood leading to failure of the piano action component. For instance, wood flanges often crack due to expansion from a rise in moisture content, as the screw crushes the wood in the flange where it is fastened to the rail. Moreover, wood has different strengths in different directions, complicating manufacturing processes, also resulting in reduced manufacturing efficiencies. Additionally, the production of any finished wood piece necessarily involves relatively large quantities of wasted material in the form of saw dust, which is inherent in any wood-working process. Finally, the lifespan of wood piano action components is limited as compared to that of other materials such as composites or plastics because wood eventually crumbles into dust after a certain amount of environmental cycles. On the other hand, composite piano action components would eliminated all the preceding drawbacks and result in more efficient manufacture and maintenance of a piano. Composite is defined as an engineered material made from two or more constituent materials with significantly different physical or chemical properties and which remain separate and distinct on a macroscopic level within the finished structure.
Thus far, all but one attempt to use composite piano action components has met with less than satisfactory market acceptance. This is because composite material is heavier than wood. Thus far, manufacturers have simply replaced traditional wood components with similarly designed and shaped composite components, resulting in heavier or, at best, equivalent mass composite action members. Our experimentation shows that, in all cases, current composite grand piano actions do not decrease and generally increase moments of inertia as determined by touch weight on the piano keys.
An increase in overall moment of inertia of a piano action is unacceptable to the pianist. Playing the piano requires a great deal of hand strength. This requirement is amplified when the pianist is playing difficult musical pieces that require the key to respond very quickly for both volume and repetition. It is probably true that virtuosic piano pieces require strength and agility at the very limit of the abilities of the human hand. A pianist who depends on a key to move with a certain amount of finger strength will reject a piano action that requires more strength to produce the same key motion.
U.S. Pat. No. 6,740,801 (Yoshisue I) and U.S. Pat. No. 7,141,728 (Yoshisue II) have met with limited market acceptance. The object of Yoshisue I is to increase the efficiency of manufacture and maintenance and to extend the lifespan of a grand piano action mechanism. In every claim, Yoshisue I is limited to piano actions with at least one component of the action made of “synthetic resin having electrical conductivity at least on the surface thereof”. The goal of this limitation is to eliminate static charge, thereby reducing the tendency of foreign particles to adhere to the action members as the particles cause wear, thereby increasing the lifespan of the action mechanism. Yoshisue I did not include the object of reducing the moment of inertia of the piano action. Yoshisue I teaches away from the use of plastic with a non-conductive surface in a piano action.
The object of Yoshisue II is to increase rigidity of the repetition base of the piano action. Increased rigidity can decrease the moments of the action when the rigidity increase is paired with certain changes in centers of mass of rotating action members and reductions in overall mass of certain action members. The repetition base in Yoshisue II, on the other hand, is without substantial change in repetition base center-of-mass and its overall mass is the same or heavier than the counterparts of this invention. Thus, the moment of the repetition base of Yoshisue II and the overall moment the whole piano action is significantly larger than those of this invention. Yoshisue II and this invention may seek to cure the same problem, i.e. reduce the energy requirements to cycle a grand piano action or improve the performance of the action; however, Yoshisue II failed at this object because it failed to discover and address the main source of the problem, which is inertia, dynamic mass, or moment analysis.