Abstract:
Composite or plastic molded articles used in a grand piano piano action. The articles make up a piano action with less dynamic mass which is, thus, more responsive to the piano player. In addition, the new action provides the extremely valuable collateral benefits of increased efficiency of manufacture and maintenance. Low inertia grand piano piano action comprises a repetition base with one or more of the following: an angled main beam, an angled balancier support beam, an integrated jack button stop, and a means to optionally connect a rest cushion assembly. Low inertia grand piano piano action may also comprise a heel with extremely low mass.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The instant application is a continuation-in-part of U.S. application Ser. No. 11/762,990 entitled “Grand Piano Composite Piano Action”, filed on Jun. 14, 2007, which is hereby incorporated by reference herein. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention pertains to the piano actions of grand pianos and specifically to piano actions that “actuate” or cycle with a substantially smaller energy requirement than other grand piano piano actions. 
   2. Description of Related Art 
   Pianists feel improvement in a piano action when the energy requirement to actuate or cycle the action in a particular way is reduced. This is because the work required by pianists&#39; fingers to cycle the action in a particular way is reduced, thereby making the piano more comfortable to play. Reductions in energy requirements to actuate piano actions allow pianists to play music with less finger strength which improves finger control. Thus, the pianist can play in a more virtuoso fashion more easily and the pianist&#39;s playing abilities are thereby improved by the new piano action. Accordingly, there is a need for a grand piano piano action that cycles in a particular way from less finger work. 
   The cycling of a grand piano piano action primarily occurs through rotational motion of action members, causing a hammer to strike piano strings, thereby making piano music. The finger energy requirement to actuate a grand piano piano action is directly proportional to the change in angular momentum of the members of the action system. 
   Grand piano piano actions consist primarily of: a repetition base, a jack, a balancier, a heel, and a set of two regulating buttons. The repetition base is the largest and heaviest of the grand piano piano action components and also incurs the largest change in inertia or momentum during cycling of the piano action. Thus, the repetition base plays a significant role in the energy requirements to actuate a piano action. Accordingly, there is a need for a repetition base for a grand piano action that incurs less momentum change during the actuation cycle of the piano action. 
   The heel also incurs a relatively large momentum change during cycling of the action. Accordingly, there is a need for a heel for a grand piano action that incurs less momentum change during the actuation cycle of the piano action. 
   BRIEF SUMMARY OF THE INVENTION 
   It is an aspect of this invention to yield a grand piano action that actuates with significantly less energy requirements. As stated in the parent application, this improvement is achieved by redesign of action components using moment analysis as the main factor affecting design rather than mass and rigidity as the key design factors. 
   It is an aspect of this invention to provide a low inertia repetition base of a grand piano piano action with a main beam and a balancier support beam that are connected at an acute angle where the balancier support beam is angled towards the jack end of the main beam. 
   It is an aspect of this invention to provide a low inertia repetition base of a grand piano piano action with an integrated jack regulating button stop that stands essentially planar with the longitudinal axes of said main beam and said balancier support beam, and is integrated into the structure of said main beam. 
   It is an aspect of this invention to provide a low inertia repetition base of a grand piano piano action with a balancier regulating button stop that is adjacent to or contiguous with one end of the balancier support beam of the repetition base. 
   It is an aspect of this invention to provide a low inertia repetition base of a grand piano piano action with a main beam that includes a main beam angled section where this section has a longitudinal axis that essentially coincides with a hypothetical line between the repetition base center of rotation hinge pin hole and center point-of-contact between the heel and the repetition base. 
   It is an aspect of this invention to provide a range of low profile lightweight heels with various heights to function in tandem with the preceding aspect in order to greatly reduce the overall angular momentum change of the piano action during an action cycle. 
   It is an aspect of this invention to provide the option of attaching a rest cushion assembly to the grand piano piano action in order to accommodate grand piano brands requiring such. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view of a grand piano piano action. 
       FIG. 2  is a front view of a Repetition Rest Cushion Bracket Assembly (RBA). 
       FIG. 3  is a front view of a Repetition Rest Cushion Bracket Heel Assembly (RBHA). 
       FIG. 4  is a front view of a Repetition Base depicting the major elements of a repetition base. 
       FIG. 5  describes the juxtaposition of the main beam angled section of a repetition base in relation to the whole repetition base. 
       FIG. 6  depicts a Prior Art Repetition Base with common points of interest called out as related to the invention. 
   

   DEFINITION LIST 
   
     
       
             
             
           
             
             
           
         
             
                 
             
             
               Term 
               Definition 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               10 
               Grand Piano Piano Action 
             
             
               20 
               Capstan contact point 
             
             
               30 
               Repetition center of rotation hinge pin hole 
             
             
               40 
               Repetition Base for Grand Piano 
             
             
               43 
               Hole for “Helper Springs” 
             
             
               46 
               Stop for the Jack Regulating Button 
             
             
               50 
               Rest Cushion 
             
             
               60 
               Rest Cushion Bracket 
             
             
               70 
               Repetition Rest Cushion Bracket Assembly (RBA) 
             
             
               80 
               RBA Center of Mass 
             
             
               90 
               RBA Effective Radius 
             
             
               93 
               Balancier Attachment Hinge Pin Hole 
             
             
               96 
               Jack Attachment Hinge Pin Hole 
             
             
               100 
               Repetition Rest Cushion Bracket Heel Assembly (RBHA) 
             
             
               110 
               RBHA Center of Mass 
             
             
               120 
               RBHA Effective Radius 
             
             
               130 
               Jack 
             
             
               140 
               Heel 
             
             
               150 
               Balancier 
             
             
               160 
               Balancier Regulating Button 
             
             
               170 
               Jack Regulating Button 
             
             
               180 
               Repetition Main Beam 
             
             
               190 
               Balancier Support Beam 
             
             
               200 
               Balancier Regulating Button Stop 
             
             
               210 
               “V” Connection with Web Support 
             
             
               220 
               Main Beam/Balancier Support Beam Connection Location 
             
             
               225 
               Prior Art “T” Connection 
             
             
               230 
               Prior Art Repetition Base 
             
             
               235 
               Main Beam - Balancier Support Beam Angle 
             
             
               240 
               Repetition Base Effective Length 
             
             
               250 
               “Main Beam/Balancier Support Beam Connection Location” to 
             
             
                 
               “Balancier Regulating Button Stop” Distance 
             
             
               260 
               Main Beam Angled Section 
             
             
               270 
               Hypothetical Line Between Repetition Base Center of Rotation 
             
             
                 
               and the Center of Contact Between the Heel and Repetition 
             
             
                 
               Base 
             
             
               280 
               Center of Contact Between the Heel and Repetition Base 
             
             
                 
             
           
        
       
     
   
   DETAILED DESCRIPTION OF THE INVENTION 
   Grand piano piano action  10  is depicted in  FIG. 1 . Grand piano piano action  10  comprises: a repetition base  40 , a jack  130 , a balancier  150 , a heel  20 , a balancier regulating button  160 , a jack regulating button  170 , a stop for balancier regulating button  200 , a stop for jack regulating button  46 , and a rest cushion assembly ( 50  and  60 ). As stated in the parent application, these elements are essentially elements of traditional grand piano piano actions  10 . 
   Prior art repetition base  230  is depicted in  FIG. 6 . Repetition base  40  of this invention is depicted in  FIG. 4 . Both comprise: a center of rotation hinge pin hole  30 , a maim beam  180 , a balancier support beam  190 , a balancier attachment hinge pin hole  93 , a stop for balancier regulating button  200 , a stop for jack regulating button  46 , and a jack attachment hinge pin hole  96 . As with any traditional repetition base, the center of rotation hinge pin hole  30  is used to create a pivotal connection between the repetition base  40  and the repetition flange where such connection is accomplished by a hinge pin placed through hole  30 . The main beam  180  supports the balancier support beam  190  and the stop for jack regulating button  46  above main beam  180 . Stop for balancier regulating button  200  is located on the upper surface of main beam  180 . With prior art repetition base  230 , the jack regulating button stop  46  consists of a metal spoon that is affixed to the main beam  180 . Repetition base  40  incorporates stop element  46  into main beam  180  as an integral unit to reduce weight of the repetition base  40  and reduce inertia of the action  10 . Balancier support beam  190  supports a balancier  150  above main beam  180  where the balancier  150  is attached to support beam  190  with another pivotal connection accomplished by a hinge pin placed through hole  93 . A jack  130  is attached with another pivotal connection accomplished by a hinge pin placed through hole  96 . 
   Repetition rest cushion bracket assembly  70  comprises: a repetition base  40 , a rest cushion bracket  60 , and rest cushion  50 . Repetition rest cushion bracket assembly  70  is depicted in  FIG. 2 . Rest cushion bracket  60  supports the rest cushion  40  slightly above repetition base center of rotation hinge pin hole  30  to allow clearance for the rotation of repetition base  40  during the cycling of piano action  10 . The rest cushion  50  is made of soft padding material, typically felt. Rest cushion  50  supports a hammer shank (not depicted) of an associated hammer (not depicted) when the piano key is at rest or upon release of the hammer by the back check, which occurs when a depressed piano key is released. Rest cushion  50  must catch the hammer shank without causing the hammer to bounce back up from the rest cushion  50 . Rest cushion  50  is connected to repetition base  40  by the rest cushion bracket  60 . Any known means may be used to connect these three elements together. 
   Some grand pianos require the rest cushion  50  to be attached to repetition base  40 , while other grand piano designs require attachment of the rest cushion  50  to another part of the piano. Repetition bases  40  of this invention are interchangeable with both types of grand pianos because the rest cushion assembly ( 50  and  60 ) can be attached to the repetition base  40  or left off. Thus, repetition base  40  further comprises a rest cushion location and attachment means. 
   Rest cushion bracket heel assembly  100  comprises: a repetition rest cushion bracket assembly  70  and an attached heel  140 . Rest cushion bracket heel assembly  100  is depicted in  FIG. 3 . Heel  140  provides primary support for the piano action  10  as heel  140  sits atop the capstan contact point  20  when the piano key and action  10  are at rest. Heel  140  is essentially a step member in the general shape of a rectangular prism, attached at its upper surface to the lower surface of said repetition base main beam. A capstan is fixed to each piano key. The piano action  10  is also supported at the repetition center of rotation  30 . The repetition center of rotation  30  remains fixed as the piano action  10  cycles. The capstan contact  20  point moves primarily vertically upward and downward as the piano action cycles, i.e. piano key is depressed and released. It is this upward and downward motion that rotates the repetition base  40  around the repetition base center of rotation  30 . The rotation of the repetition base  40  causes the hammer of the piano to strike the piano strings and retract there from. 
   An embodiment of this invention includes a repetition base  40  with repetition main beam  180  that is not straight, as with prior art repetition bases, but rather includes at least one angled section  260  that is angled toward the heel  140  of the action  10  and the capstan of the piano key. As shown in  FIG. 6 , prior art repetition bases  40  do not have this angled section  260 . A repetition base  40  with main beam angled section  260  results in a lower inertia piano action primarily because of two reasons. 
   First, a main beam  180  with angled section  260  that extends downward toward the heel  140  of the action allows for a much shorter heel  140 . A shorter heel  140  is desirable because shorter heels weigh less than taller heels. Weights of heels  140  are very important to the moment of inertia of the piano action  10  because heels  140  are relatively heavy components of the action  10  that are located relatively far from the repetition center of rotation  30 . A main beam  180  with angled section  260  allows for a substantial weight savings in the heel  140 . For instance, a mode of heel  140 , as depicted in the drawings in this application, weighs 61% less than most heels in the public domain. The main beam angled section  260  is a component of the repetition main beam  180 . 
   Second, the “V” connection with web support  210  between the repetition main beam  180  and the balancier support beam  190  delivers much more rigidity than the prior art “T” connection  225  between analogous components of the repetition base. Thus, the increased rigidity of this design, allows for a reduction in material and mass of the repetition base  40  in the vicinity of area  225  without compromise to the overall rigidity requirement of the piano action  10 . 
   An embodiment of the repetition base  40  includes a balancier support beam  190  that connects with the repetition main beam  180  at a connection location  220  that is essentially immediately adjacent to the balancier regulating button stop  200 . Main beam/balancier support beam connection location  220  is a hypothetical location on the repetition base  40 , introduced to help articulate description of the invention. Main beam/balancier support beam connection location  220  is defined as a point on the upper surface of the repetition base  40  that lies at the seem between the repetition main beam  180  and the balancier support beam  190 . See  FIG. 5  for a depiction of the location  220 . 
   Prior art repetition bases have main beam/balancier support beam connection location  220  located relatively far from the balancier regulating button stop  200 , typically by a distance  250  that is about 25% of the effective length of the repetition base  240 . Repetition base effective length  240  is defined as the distance between repetition center of rotation  30  and jack attachment hinge pin hole  96 . See  FIG. 6  for a depiction of prior art repetition bases  40  with points  220  and  200  called out. The new design moves the center of mass of the repetition base  40  towards the repetition center of rotation  30 , thus reducing the moment of inertia of the piano action  10 , without sacrificing rigidity. 
   Repetition base  40  may also includes a novel connection angle  235  between the repetition main beam  180  and balancier support beam  190 . This angle  235  has always been essentially 90 degrees. See  FIG. 6  for a depiction of prior art. As a result of the scientific method described above aimed to move mass, reduce mass, and increase rigidity of the repetition base  40  in order to reduce touch weight of the action  10 , we introduce a repetition base with an acute angle  235  as seen on  FIG. 5  as the best mode. The best mode angle depicted here is within the breadth of claim  1 . 
   The moment of inertia of a rigid body rotating about a fixed axis is ∫r 2 dm, where r is the distance from center of rotation to the differential mass point of the body dm. The moment of inertia of a piano action component can be approximated by: (the distance from center of rotation to the center of mass) 2 ×(mass). 
   The moment of inertia of a repetition rest cushion bracket assembly (RBA)  70 , can be accurately approximated using the distance from repetition center of rotation  30  to the RBA center of mass center of mass  80 —hereafter know as the RBA effective radius  90 —and the mass of the RBA  70 . A mode of this invention has a moment of inertia equal to 17,456 gmm 2  from a RBA weight of 9.35 grams and RBA effective radius of 43.19 mm. This moment is a dramatic improvement over the prior art in that it is substantially less than that of prior art and thus yields a piano action  10  with greatly improved response. 
   The moment of inertia of a rest cushion bracket heel assembly (RBHA)  100 , can be accurately approximated using the distance from repetition center of rotation  30  to the RBHA center of mass center of mass  110 —hereafter know as the RBHA effective radius  120 —and the mass of the RBHA  100 . A mode of this invention has a moment of inertia equal to 20,861 gmm 2  from a RBHA weight of 10.31 grams and RBHA effective radius of 44.97 mm. This moment is a dramatic improvement over the prior art in that it is substantially less than that of prior art and thus yields a piano action  10  with greatly improved response.