IMPROVEMENTS IN PIANO ACTIONS

Abstract: A piano action in which the hammer (112) has an abutment surface (143) which disengages by abutting limb (124b) the jack (124) from a recess (128) in the hammer to disengage the drive to the hammer before it strikes the string (110). The hammer (112) is made of a plastics material and the wippen (120) and the jack (124) are also formed integrally from a plastics material, being interconnected by a film hinge (129). The preferred embodiment also provides for a hammer check (136) and a damper (147) operating extension to be formed as an integral part of the wippen (120) and jack (124).

Description: Improvements in pianoactions The present invention relates to an upright piano and the like stringed keyboard instrument. Figure 1 of the accompanying drawings shows the action of a typical known prior art piano. The string 10 is struck by a hammer 12 of which the movement is controlled by a key 14 pivoted at a point 16. When the key 14 is depressed it acts by way of a distance piece 18 to raise a wippen 20 which is in turn pivoted at a point 22. The wippen 20 carries a jack 24 which is pivoted at its lower end 26 and at its upper end engages in a recess 28 in the base 30-of the hammer 12. It is necessary to ensure that the drive connection between the key 14 and the hammer 12 be disengaged before the hammer makes contact with the string 10. This is accomplished in the arrangement illustrated by providing a limb 32 on the jack which engages a fixed stop 34 after the jack has risen a predetermined distance. This engagement causes the jack to rotate clockwise as viewed so as to release the upper end of the jack 24 from the recess 28. After this, the jack continues travelling under its own inertia to strike the string 10. The disadvantage of this construction is that each note requires a separate stop 34 which when the piano is first assembled requires individual adjustment. Thus apart from the complexity of the action, its assembly is very time consuming and this has contributed to the high cost of such instruments. The present invention seeks to mitigate the above disadvantage and to provide a piano in which the diengagement of the jack from the hammer does not require a separately adjustable stop. According to a first aspect of the present invention, there is provided a piano comprising a pivotably mounted hammer, a manually operable key, a -wippen coupled to the key, a jack movably supported by the wippen and movable therewith, a recess in the hammer engageable by the jack and means for disengaging the jack from the recess prior to the hammer striking the string, wherein the means for disengaging the jack from the recess in the hammer comprises an abutment on the hammer engageable with a surface of the jack when the hammer is in a predetermined position. It will be noted that the disengagement from the jack in the invention is achieved by the hammer itself. It might at first be considered undesirable to take energy from the hammer to effect this disengagement from the jack but it has been found in practice that the kinetic energy imparted to the hammer prior to disengagement is very substantially greater than the energy absorbed by the abutment with the jack and the effect on the hammer is not noticeable. Referring again to Figure 1, it is necessary to ensure that the hammer 12 does not bounce during its return after striking the string 10. To absorb the energy of the hammer 12, a check 36 mounted on the wippen 20 includes a felt pad 38 which rubs against a similar pad 40 mounted on a foot 42 projecting from the base 30 of the hammer 12. This stops the hammer silently and when the key 14 is released the hammer 12 is brought to rest on a support bar 44 common to all the hammers. In the preferred embodiment of the invention, the wippen and the hammer are each formed of a plastics material and an extension of the wippen is operative to engage slidingly and frictionally with a surface on the base!of the hammer to check the return motion of the hammer. An advantage of the construction of the wippen from a plastics material is that thewippen may be formed integrally with the jack, the two being connected by a plastics flexible hinge. This makes for a particularly simple and inexpensive construction of the piano action requiring a minimum of separately moulded components. After a key is released, it is important to ensure that the string stops resonating. In the prior art arrangement of Figure 1, the damping is effected by means of a pivoted damper 46 which is pivoted out of engagement with the string 10 by a so-called spoon 48 mounted on the wippen 20. In other known constructions, the damper is moved by an extension of the piano key 14. Each of these costructions has its attendant disadvantages. If the damper is operated by the key, then the keyboard cannot be readily separated from the action of the piano, making therefore for a more complex assembly. On the other hand, the wippen and spoon construction illustrated adds substantially to the inertia of the moving parts. Accordingly in the preferred embodiment of the invention, the wippen of plastics material has an extension which acts both as a hammer check and as the means for lifting the damper off the string when the piano key is depressed. Because the hammer check is serving the dual function of raising the damper and checking the hammer, the inertia of the moving parts is minimised, while still permitting the action and the keyboard to be made and assembled separately. It is necessary to ensure that the hammer be returned to its rest position when the piano key is released in order to permit staccato playing of the instrument. This forcible retraction of the hammer is achieved in the arrangement of Figure 1 by a length of slack string or tape 50, extending from the wippen 20 to the hammer 12. During normal playing, this tape is ineffective, but if the wippen during staccato playing drops before the hammer 12 has returned to its rest position, then the tape 50 becomes taut and pulls the hammer 12 down with the wippen. In the preferred embodiment of the invention, the jack is operative to re-engage in the recess in the hammer and to cooperate with the lower edge of the recess to couple the hammer to the wippen as the wippen returns to its rest position. As the hammer and the jack are both preferably made of a plastics material, the re-engagement of the jack in the recess may cause a slight click. It is therefore preferred that a cushioning pad be incorporated in the recess to muffle any such noises. Brief description of the drawings. The invention will now be described further by way of example, with reference to the accompanying drawings, in which Figure 1 is a schematic representation of a known piano action as described above, and Figure 2 is a similar view of an embodiment in accordance with the present invention. Detailed description of the preferred embodiment. In Figure 2, there is illustrated an action in which the wippen 120 is coupled to the piano key 114 by means of a prolong 118 rather than a distance piece. The appropriate selection in any case will depend on the dimensions of the frame and the desired height of the keyboard relative to the action. It is simpler to employ distance pieces if the construction permits it since the keys are then totally separate from the action. However, in the described emodiment it is assumed that the keys are arranged higher than the mechanism. The wippen 120 is constructed in one piece with a jack 124 and with a mounting block 125 which is secured to the body of the piano. The wippen may pivot relative to the mounting block 125 about a film hinge 127 and the jack may pivot relative to the wippen about a film hinge 129. The hammer 112 is pivoted at 115 relative to the piano frame the pivot not being shown in detail. This bearing must be free and it may include a bearing insert. However, to simplify the assembly, the pivot may be formed by a keyhole slot so that it may be simply pushed into place over a pivot rod. The base 130 of the hammer 112 is formed with a recess 128 engageable by the head of the jack 124. The recess is lined with a sound muffling pad 123. The base of the hammer 112 is also formed with a check suface 142 which cooperates with a check surface 136 formed on an extension 137 of the wippen 120. The damper comprises a felt pad 147 mounted on a pivoted lever 146 which is biased by means of a spring (not shown) towards the string 110. The lower end of the lever 146 is not illustrated, in the interest of clarity, but is actuated by the extension 137 to lift the pad 147 off the string 110 when the wippen is in a raised position. The lower end of the lever 146 has, in known manner, a second limb operable by means of the loud pedal which enables all the dampers to be raised simltaneously off the strings 110. In operation, when a note is to be played, the player depresses the key 114 raising the end seen in the drawing. The wippen 120 is pivoted clockwise, as viewed, -about the film hinge 127, raising the jack 124 relative to the hammer 112. The nose 124a of the jack 124 acts on the upper edge of the recess 128 and pivots the hammer anti-clockwise, as viewed, about the bearing 115. When the hammer is near vertical, as viewed, a heel portion 143 of the base 130 of the hammer 112 abuts a limb 124b of the jack 124. Because of the inertia in the hammer, the jack is pivoted by this abutment clockwise about the film hinge 129 retracting its nose 124a from the recess 128. Consequently, the jack is disengaged from -the hammer and the latter continues under its own inertia to move in the direction of the string. After striking the string 110, the hammer 112 bounces back while the wippen 120 is still in a raised position. The surface 136 of the check and surface 142 on the base of the hammer then slidingly and frictionally engage one another to absorb the energy of the hammer and bring it smoothly and silently to a stop. It has been found, surprisingly, that the plastic surfaces suffice to achieve silent and effective checking of the return motion and the surfaces are not subjected to excessive wear. As the wippen rises, the extension 137 lifts the damper pad 147 off the string 110. When the wippen 120 again drops to its rest position, the lever 146 pivots counterclockwise to damp the string once again. During stoccato playing, the wippen returns to its rest position before the normal return of the hammer. Thus, while the hammer is near a vertical position, as viewed, the jack drops and and the nose 124a again enters the recess 128. The cushion 123 prevents any clicking from occuring during this movement. During the continued descent of the jack 124 its nose 124a engages the lower edge of the recess 128 and forcibly pulls the hammer back to its rest position so that the key may be played in rapid succession. Though the invention has been described by reference to a particular embodiment, it should be made clear that various modifications may be brought thereto without departing from the scope of the invention as set forth in the appended claims. In particular, it is not essential that the wippen be designed to operate the damper as the latter may, as already known, be operated directly by the key.

Claims: AMENDED CLAIMS [received by the International Bureau on 19 September 1983 (19.09.83) original claims 1 to 6 have been replaced by amended claims 1 to 5] 1. A piano comprising a pivotably mounted hammer, a manually operable key, a wippen coupled to the key, a jack movably supported by the wippen and movable therewith, a recess in the hammer engageable by the jack and means for disengaging the jack from the recess prior to the hammer striking the string, the the means for disengaging the jack from the recess in the hammer comprising an abutment on the hammer engageable with a surface of the jack when the hammer is in a predetermined position, characterised in that the jack (124) is operative to re-engage in the recess (128) in the hammer and to cooperate with the -lower edge of the recess to couple the hammer to the wippen as the wippen returns to its rest position. 2. A piano as claimed in claim 1, wherein the wippen - (120) and the hammer (112) are each formed of a plastics material and an extension (137) of the wippen (120) is operative to slidingly and frictionally engage-with a surface (142) on the base (130) of the hammer (112) to check the return motion of the hammer. 3. A piano as claimed in claim 2, wherein the wippen (120) is formed integrally with the jack (124), the two being connected by a plastics flexible hinge (129). 4. A piano as claimedin claim 2 or 3, wherein a damper (146,147) is provided for damping the vibrations of the string when the key (114) is released, and wherein the wippen (120) has an extension (137) which acts both as a hammer check and as means for lifting the damper (146,147) off the string when the key is depressed. 5. A piano as claimed in any preceding claim, wherein a cushion (123) is provided in the recess (128) to prevent noise upon engagement of the jack (124) in the recess (128).

Inventors: STANWELL-SMITH COLIN HOWARD, STANWELL-SMITH, COLIN, HOWARD
Applicants: PRUTEC LTD, PRUTEC LIMITED
Application year: 1983
Main classification: G10C3
IPC codes: G10C3