GB2256522A - Repetition actions - Google Patents

Abstract

An action for upright piano or similar action for other instrument, including electronic, incorporating a repetition spring 21 mounted on the lever assembly which includes lever 2, check 13 and check wire and which spring or an extension thereon passes over the check 13 and balance hammer 12 and presses on the hammer shank 9 so as to push the butt 6 and jack 5 apart. The repetition spring 21 may be fixed at one end to the underside of the check 13, or the lever 2 (Figures 7, 9, 11). Movement of the repetition spring may be adjusted by a screw 25 on the check and a screw 29 on the damper slap rail 16. Thus an exact analogy of the grand piano repetition lever is obtained. The spring also pulls on the shank, so the bridle tape and wire can be omitted. To produce an effect identical to that of the grand action, a novel form of jack spring 34 is used, various other parts are changed in shape, and an adjusting screw 32 is provided for the butt spring. <IMAGE>

Description

IMPROVED REPETITION ACTIONS The invention relates to actions of musical instruments such as pianos, in which keys of a keyboard control movement of hammers to strike strings or equivalent parts. It is particularly though not exclusively applicable to upright pianos and electronic keyboard instruments intended to simulate the mechanical touch of grand pianos.

The objects of the invention include: to make an upright piano action resembling the grand action in playing characteristics, most particularly in repetition, impedance to the fingers, and dynamic response (minimum key speed); to minimise cost of manufacture and maintenance; to maximise reliability and durability; and retention of compactness and lightness.

Erard's British patent of 1821, no 4631, introduced the repetition lever for grand pianos. There followed hundreds of attempts at incorporating the same principle or effect into actions for upright pianos but they all proved impractical in various ways. For example, they were complicated to manufacture, difficult to keep in adjustment, relatively bulky, or did not actually work.

The nature of the problem to be solved may be better appreciated by consideration of the modern grand and upright actions.

In the accompanying drawings, Figure 1 shows the action of one note of a conventional upright piano; Figure 2 shows the action of an embodiment of the invention; Figure 3 shows a cross section of the hammer shank with the end of a repetition device hooking around it; Figure 4 shows the head of an adjusting screw; Figure 5 shows a screw for adjustment of a butt spring; Figure 6 shows part of a conventional grand piano action.

Figure 7 shows an action indicating alternative embodiments; Figure 8 is a horizontal cross section through the end of the lever; Figure 9 shows an action indicating alternative embodiments; Figure 10 is a view from above, of an alternative means of fixing a repetition spring to a lever.

Figure 11 shows an action indicating alternative embodiments; Figure 12 shows a bar featured in figure 11, clipped to a shank.

When the front of a key of a conventional modern upright piano is depressed, its far end rises and lifts the lever 2 (figure 1). This lever pivots on a flange 3 screwed to a fixed rail 4. A jack 5 pivots on the lever, and the upper end of the jack 5 lifts the hammer butt 6. This harnmer butt 6 pivots on a flange 7 screwed to the rail 4. The hammer butt 6 has a hammer head 8 mounted on it via a hammer shank 9. Thus pressing down the key causes the lever to lift the jack, and hence the butt, and so propels the hammer head 8 towards the string 10. But for the string to vibrate freely, the hammer head must be free to fall away immediately.To achieve this the jack 5 is caused to abut with a let-off button 11, such that it is deflected and no longer supports the butt 6. (This contrivance is called the escapement.) The fall of the hammer is limited by contact between the balance hammer 12 and the check 13.

To repeat the note it is necessary to relocate the jack 5 under the butt 6. Because there is no repetition device, this can be reliably done only by returning the mechanism to its starting position, that is, fully raising the key. (The hammer then rests on the rest rail 14, and the jack spring 15 can then push the jack back under the butt.) However, this makes for slowness and clumsiness of repeating of notes. Also, because of this, such actions are liable to block, with the key unable to go fully down. Modern upright actions use weak butt springs to give a compromise between repetition performance and minimum effective key speed.

Erard's repetition device makes compromise unnecessary and permits reliable repetition even with only slight lifting of the key. This is achieved by a spring-loaded repetition lever (721, figure 6) which supports the hammer roller 706 and shank 709 to allow the jack 705 to relocate. The principle of this modern grand repetition lever will hereinafter be referred to as the Erard principle.

For convenience of description the term hammer assembly will be used to denote the solid body usually composed from a hammer butt 6, shank 9, hammer head 8, and balance hammer 12. Likewise the term lever assembly will be used to denote the solid body usually comprising a lever 2, check 13, and check wire.

An upright action may best simulate a grand by incorporating this same Erard principle. Thus it should have a spring mounted on the lever assembly and tending to push the hammer assembly away from from the jack; the spring should be continually stressed such as to slightly exceed the force of the hammer; its action should be restrained by an abutment fixed to the lever and by a stationary abutment; it should tend to hold the hammer butt just above the jack except when near the string when it should be stopped by the stationary abutment. Numerous patents have incorporated these principles, from British patent of 1825, no 5065, to Japanese application of 1989, no 1-302397.

The conventional upright action has many merits so it could be advantageous if the Erard principle could be incorporated into an action substantially as customary. This was done in Erard's British patent of 1850, no 13252 but this was complicated to make and maintain; the repetition device was inconveniently located behind the jack.

When the key of a conventional upright action is depressed partway, the top of the check gets closer to the bottom of the hammer shank, but further from the top of the shank. It follows that there is a point on the shank that stays the same distance from the top of the check. Thus a condition is satisfied for location of an Erard principle repetition device approximately between the check and the shank.

According to the invention the repetition spring is arranged to apply its force from a point near the top of the check to a point on the shank.

Thus according to the invention the action may have the combination of: (1) effectively the arrangement customary in upright pianos as follows, namely a hammer assembly pivoting on and over a rail, a jack abutting it below, the jack pivoting on a lever pivoting on a rail, with the strings nearer to the lever pivot than they are to the jack pivot, and a check mounted on the lever such as to contact the balance hammer; (2) a repetition spring mounted directly or indirectly on the lever assembly; and (3) an extension of the spring or an extension therefrom extending over the balance hammer to abut directly or indirectly with the hammer shank or butt or equivalent part; such that the spring can tend to push the butt away from the jack.

European patent 0229746 describes a device located between the check and the hammer shank, supposedly to improve repetition, but it is not a spring or spring-loaded according to the Erard principle but instead a rigid jack.

According to the invention the repetition spring may further accord with the Erard principle by being continually stressed.

Also according to the invention, the repetition device may be comprised of a spring that by reason of its flexibility functions in place of a pivot, and that by reason of its degree of rigidity functions also in place of a lever. Thus the cost of making a lever and pivot can be avoided, and the repetition device does not prevent access to adjustments and screws underneath.

The repetition device could conceivably involve a tension or compression spring or a torsion spring located above the balance hammer; but these options do not seem particularly advantageous.

One satisfactory arrangement is for a spring wire to be mounted on the check 13, extending downward most of the way to the lever 2 and rising again adjacent to the check, its force being applied directly or indirectly to the hammer shank or equivalent.

This spring may be secured in a hole in the underside of the check 13, by bending the end of the spring back on itself so that it may be pushed to hold itself in the hole. To prevent the spring from rubbing against itself or deviating to one side the end of the spring may be held twisted as it is pushed into the hole.

Alternatively the spring may be mounted on the end of the lever 2 as will be described for some of the embodiments. At its upper end the spring may bend over the check to contact and hook around the shank 9, or the spring may terminate adjacent to the top of the check 13. In the latter case, an extension bar may be mounted on the end of the repetition spring, its other end having a slot that clips around the shank. Or a seperate bar may be designed to clip to the shank at one end and have a slot in its other end through which the spring passes.

These arrangements have been found to permit easy assembly and disassembly yet to be fully reliable. Even if the spring is dislocated to left or right it relocates itself when the note is played.

According to the invention the movement of the repetition device may be regulated by abutment against a pad on the check and by abutment against a pad or surface on the damper slap rail 16.

By arranging the repetition device to hook or clip around the shank, it can be made not only to push but also to pull the shank, so that the bridle tape and bridle wire 99 can be omitted, saving cost and complication.

Embodiments of the invention will now be described with reference to the accompanying drawings.

Figures 2, 3, 4, and 5 relate to a first embodiment for upright pianos.

In most respects this is the traditional arrangement.

A wire repetition spring 21 is secured in a hole 37 in the check 13 by its own force by bending its end back on itself and pushing in the hole as described above. It has no coiled part. From the check it extends downwards most of the way to the lever 2 then rises again to pass adjacent to the check. It abuts against a cloth washer 24 fixed on an adjusting screw 25 on the check 13. The repetition spring bends over the check to contact a pad 26 wrapped around the shank 9. A loop of cord 27 is fixed to one side of the butt 6. The repetition spring is threaded through the loop and shaped so as to pull against it, thus keeping itself at the correct height on the shank. The upper end of the spring is shaped to hook around the shank, (as in figure 3 which shows a view from above) such that it can both push and pull (though some slack must be permitted).For this reason the bridle tape and wire (99, figure 1) are not required, giving a substantial cost saving.

The upper end of the repetition spring 21 abuts against a further pad 25 over an adjusting screw 29 on the damper slap rail 16.

The spring 21 is shaped such as to press gently on the side of the pad on the shank. Its endmost part 36 is bent back slightly to ensure that it cannot press on the screw 29 for the adjacent note.

The force of the repetition spring is set such that it raises the hammer butt off the jack. The adjustment can conveniently be done by setting the spacing between the two vertical arms to about 30-40 mm (as required) while disengaged from the hole 37. If the correct spring steel is used then readjustment will rarely if ever 'be needed. And the large size of the spring makes initial adjustment easy.

The screw 25 is adjusted such that the repetition spring raises the butt only a small distance above the jack. The screw 29 is adjusted such that the repetition spring cannot push the hammer head too close to the string.

In the grand action illustrated in figure 6, the screws 725 and 729 correspond to screws 25 and 29 respectively.

A preferred design of the heads of the adjusting screws 25 and 29 is shown in figure 4. They are formed with large flat heads with small cross-head indentations such as used in Phillips or Posidrive screws. The cushions can then partly cover the flat areas while leaving access for a screwdriver. These screws can be inserted by auto feed, minimising expense.

For a cheaper though still effective version, the screws can be omitted, any adjustment being made by shimming.

Because the repetition device acts relatively distant from the pivot of the hammer assembly, its force is relatively low and its adjustments are relatively uncritical; thus wear at the contact points will not be problematic.

This repetition device may advantageously be incorporated in an otherwise unmodified upright action. But other changes become advantageous, because the conventional design has been developed to compensate for lack of a repetition device. By such changes greater - indeed total - resemblance to the touch of a grand action can be obtained, along with further improvement of repetition particularly of the bass notes.

Most importantly, the butt spring 17 of the upright action is conventionally made relatively weak so as to ameliorate repetition. But this leads to two problems, firstly, sluggishness of the hammer head when returning, and secondly, reduced deceleration of the hammer when flying towards the string. This latter is particularly important because it greatly affects the dynamic response of the action. There is a minimum speed of depression of the key below which the note will not sound. For the quietest playing it is necessary to approach closely to this minimum speed, but also to avoid losing notes altogether.

To achieve the standard minimum key speed of a grand action having let-off distance of 1/16 inch, the butt spring must be made more forceful to simulate the force of gravity on the grand action. Also the butt spring must cancel out the non-uniform torque due to gravity on the upright hammer. These requirements can readily be satisfied by designing butt springs to have the required force and compliance, by known means.

To assist in providing greater torque, the flange 7 may be extended to about 10 mm above the pivot hole. The total deflection of the resulting butt springs is about one quarter of that of conventional ones so they will retain their original force for many years. The disadvantage of reduced total deflection is that a shaping error of I mm will produce up to 5 g error of touch weight. So either the springs must be made accurately or each spring be provided with an adjusting screw.

To facilitate accurate adjustment of force each butt spring may be provided with an adjusting screw 32 set in a hole in the butt. As shown in figure 6, this screw has a groove or collar 33 around it just below its head, such that an end of the spring may rest in the groove or on the collar.

Thus the position of the screw determines the position of the end of the spring. The springs may be graduated in correspondence with the weights of the hammers. To monitor adjustment the action may be tipped over 90 degrees, whereupon the hammers should rest as if touching the strings.

The jack spring 15 of an upright action becomes progressively compressed as soon as the key starts to go down, and hence the jack spring makes its presence felt much more significantly in the upright than the grand. It is customary to use a low compliance jack spring to compensate for the varying torque of gravity on the hammer. But where this variation has already been compensated by changes to the butt springs, it is desirable to make the jack spring forces also resemble those of a grand. For this purpose a new design of jack spring may be used.

This new design of jack spring, shown in figure 2, is a torsion spring 34, mounted on the jack towards the keyboard; it has an upward arm disposed to press and slide against a padded rail 35 fixed in place near the top of the jack. The resting force of this spring need only be slight, so friction and wear are not problematic.

The conventional balance hammer 12 and check 13 are not very effective at holding the hammer against the force of a repetition spring. To make the operation fully resemble that of a grand action, the line of contact between the balance hammer and check may be changed so that it is at substantially smaller angle to the line of movement of the contacting surface of the balance hammer. Half the usual 30 degrees angle gives very satisfactory results.

To give the correct force of "after-touch" (friction at the moment of let-off), the lower arm of the jack 5 may be lengthened. To give the correct distance of sliding, the leather of the butt 6 may be extended and shaped more convexly.

Figures 7 and 8 show an alternative form of the repetition spring 2 1, which may be secured to the lever 2 by its own force by means of a hole 23 and oblique slot 22 in the lever; the end of the wire being bent to fit into the hole. This arrangement has been found to permit easy assembly and disassembly yet to be fully reliable. Even if the spring is dislocated to left or right it relocates itself when the note is played.

To provide the effect of a grand una corda pedal the dampers may be mounted on a seperate rail screwed to the iron frame, as shown in figure 9.

The damper springs 50 could then be placed below the rail 51 and the damper flanges would be screwed beneath the rail.

Figures 9 and 10 also show an alternative means of securing the spring 21 to the lever, such that it is held by its own force and adjustable by a screw. The end of the spring is bent to fit into a hole 55 in the end of the lever. A screw 56 holds a clip 57 against the spring. The clip may be prevented from turning by means of engagement in a slot or hole 58.

Figure 9 also shows an alternative form of the repetition device. In this version the repetition spring wire does not bend over the check but rather terminates by it and a seperately formed bar 40 is attached at its upper end. Pads on the shank retain the bar at the correct position.

Figures 11 and 12 show a further form of the repetition device. In this version the repetition spring 61 is a simple torsion spring with a coil 62 at its lower end set in a slot in the end of the lever 2. The spring is held in place by a cord or peg passing through the coil and holes in the lever (as is known). Its force is adjusted by the screw 63 pressing against its shorter arm. A bar 64, most conveniently moulded from plastic, is designed such as to clip onto the shank 9. The bar has a slot or hole 65 in its other end, through which the spring 61 is placed. The bar has a narrowed section 66 to enable flexing in a vertical plane.

The spring 61 has a button or knob 67 of plastic or wood pressed onto its upper end to retain the bar on the spring and to abut with screw 29.

Adjusting screws 25 and 29 serve the same functions as in other embodiments. Padding 68 may be fixed to the spring and other padding incorporated as required to suppress clicking.

This version has two advantages, namely freedom of rotation of the bar against the wire, and offsetting of screw 29 from the line of force along bar 64, in concordance with the offsetting of screw 729 in the grand action.

Electronic keyboards do not need an action to produce satisfactory tones, but to produce the touch and feel of an acoustic piano an action is necessary, and the feel and touch will only be the same as a grand piano if the action is suitably designed. Yamaha's Japanese patent application no 62208092 describes an electronic instrument having a complete grand action to provide correct touch. According to the new invention an action as herein described may be incorporated in an electronic keyboard instrument, to give the correct touch without the expense, weight, and bully of a grand action.

Many other embodiments of the principles of the invention are possible and are not excluded by this specification.

Claims (18)

92 CLAIMS In the following, hammer assembly means a solid object customarily comprising hammer head, shank, butt, balance hammer and balance hammer shank; lever assembly means a solid object customarily comprising lever, check and check wire.

1. An upright piano action (or similar action for other musical instrument), including a repetition spring; Wherein the action has effectively the arrangement customary in upright pianos as follows, namely a hammer assembly pivoting on and over a rail, a jack abutting it below, the jack pivoting on a lever pivoting on a rail, with the strings nearer to the lever pivot than they are to the jack pivot, and a check mounted on the lever such as to contact the balance hammer; And wherein the repetition spring is mounted directly or indirectly on the lever assembly (but not on the jack); And wherein the spring or an extension therefrom extends over the check and balance hammer to abut directly or indirectly with the hammer shank or butt or equivalent part; And wherein the spring can tend to push the butt away from the jack.

2. An action as in Claim 1, wherein said spring is continually stressed.

3. An action as in Claims 1 or 2, wherein the repetition spring by reason of its flexibility functions in place of a pivot and by reason of its degree of rigidity functions also in place of a lever.

4. An action as in Claims 1, 2, or 3, wherein the repetition spring comprises a wire mounted on the lever assembly and rising by the check.

5. As in any preceding Claim, wherein a bar is designed to clip at one end onto the shank (or equivalent part of the hammer assembly), and designed such that its other end may flex up and down, with that end having a slot or hole through which the repetition spring passes, and wherein the spring or an extension thereon projects upwards and abuts against a stop fixed on or adjacent to the hammer rest rail, and wherein a cap or knob is fitted on the end of the spring to hold the bar in place.

6. As in Claims 1, 2, 3, or 4 wherein the spring wire bends over the check to contact directly or indirectly the hammer assembly.

7. As in Claim 6, wherein the upper end of the repetition spring or device is maintained at the required level relative to the shank by means of its pulling against a loop of cord attached to a side of the butt.

8. As in any preceding Claim, wherein the spring is mounted on the check and extends downwards most of the way to the lever, and then bends around to rise adjacent to the check.

9. As in any preceding Claim, wherein the spring wire is secured by friction from its own force in a hole in the part of the lever assembly, by having its end bent back on itself and pushed into the hole.

10. As in Claims 1, 2, 3, 4, 5, 6, or 7, wherein the spring wire is secured by its own force by means of a bend in the wire near its end and a hole and oblique slot in the lever into which the wire is fitted.

11. As in Claims i, 2, 3, 4, 5, 6, or 7, wherein the spring wire is secured by its own force by means of a bend in the wire near its end, a hole in the end of the lever (into which the end of the wire fits), an adjusting screw set in the end of the lever, and a clip held by the screw, against which screw and clip the spring presses.

12. As in any preceding Claim (except Claim 5), wherein movement of the repetition spring/bar is limited by abutment with the damper slap rail.

13. As in any preceding Claim, wherein the repetition lever hooks or clips around part of the hammer assembly, so as to both push and pull.

14. As in any preceding Claim, wherein the butt spring, jack spring, and key weighting are modified to increase resemblance of touch to a grand action.

15. As in Claim 14, wherein an end of the butt spring rests on a collar or groove formed around an adjusting screw set in the butt.

16. As in Claim 14, wherein the jack spring is a torsion spring mounted on the jack, with an upward arm pressing and sliding against a fixed rail located near the top of the jack.

17. As in Claim 14, wherein the angle between (a) the line of contact between balance hammer and check and (b) the line of movement of the contacting surface of the balance hammer is substantially reduced from the customary angle.

18. An action for a keyboard instrument substantially as described herein with reference to the figures of the accompanying drawings.

18. An action for a keyboard instrument substantially as described herein with reference to the figures of the accompanying drawings.

Amen~ts to the dawns have been tied as flows CLAIMS In the following, hammer assembly means a solid object customarily comprising hammer head, shank, butt, balance hammer and balance hammer shank [said balance hammer being absent in the patent GB 0699826 cited in the search report]; lever assembly means a solid object customarily comprising lever, check and check wire.

1. An upright piano action (or similar action for other musical instrument), including a repetition spring; Wherein the action has effectively the arrangement customary in upright pianos as follows, namely a hammer assembly pivoting on and over a rail, a jack abutting it below, the jack pivoting on a lever pivoting on a rail, with the strings nearer to the lever pivot than they are to the jack pivot, and a check mounted on the lever such as to contact the balance hammer [said balance hammer being absent in the patent GB 0699826 cited in the search report]; And wherein the repetition spring is mounted directly or indirectly on the lever assembly (but not on the jack);; And wherein the spring or an extension therefrom extends over the check and balance hammer to abut directly or indirectly with the hammer shank or butt or equivalent part [unlike in the patent cited in the search report]; And wherein the spring can tend to push the butt away from the jack.

2. An action as in Claim 1, wherein said spring is continually stressed.

3. An action as in Claims 1 or 2, wherein the repetition spring by reason of its flexibility functions in place of a pivot and by reason of its degree of rigidity functions also in place of a lever.

4. An action as in Claims 1, 2, or 3, wherein the repetition spring comprises a wire mounted on the lever assembly and rising by the check.

5. As in any preceding Claim, wherein a bar is designed to clip at one end onto the shank (or equivalent part of the hammer assembly), and designed such that its other end may flex up and down, with that end having a slot or hole through which the repetition spring passes, and wherein the spring or an extension thereon projects upwards and abuts against a stop fixed on or adjacent to the hammer rest rail, and wherein a cap or knob is fitted on the end of the spring to hold the bar in place.

6. As in Claims 1, 2, 3, or 4 wherein the spring wire bends over the check to contact directly or indirectly the hammer assembly.

7. As in Claim 6, wherein the upper end of the repetition spring or device is maintained at the required level relative to the shank by means of its pulling against a loop of cord attached to a side of the butt.

8. As in any preceding Claim, wherein the spring is mounted on the check and extends downwards most of the way to the lever, and then bends around to rise adjacent to the check.

9. As in any preceding Claim, wherein the spring wire is secured by friction from its own force in a hole in the part of the lever assembly, by having its end bent back on itself and pushed into the hole.

10. As in Claims 1, 2, 3, 4, 5, 6, or 7, wherein the spring wire is secured by its own force by means of a bend in the wire near its end and a hole and oblique slot in the lever into which the wire is fitted.

11. As in Claims 1, 2, 3, 4, 5, 6, or 7, wherein the spring wire is secured by its own force by means of a bend in the wire near its end, a hole in the end of the lever (into which the end of the wire fits), an adjusting screw set in the end of the lever, and a clip held by the screw, against which screw and clip the spring presses.

12. As in any preceding Claim (except Claim 5), wherein movement of the repetition spring/bar is limited by abutment with the damper slap rail.

13. As in any preceding Claim, wherein the repetition lever hooks or clips around part of the hammer assembly, so as to both push and pull.

14. As in any preceding Claim, wherein the butt spring, jack spring, and key weighting are modified to increase resemblance of touch to a grand action.

15. As in Claim 14, wherein an end of the butt spring rests on a collar or groove formed around an adjusting screw set in the butt.

16. As in Claim 14, wherein the jack spring is a torsion spring mounted on the jack, with an upward arm pressing and sliding against a fixed rail located near the top of the jack.

17. As in Claim 14, wherein the angle between (a) the line of contact between balance hammer and check and (b) the line of movement of the contacting surface of the balance hammer is substantially reduced from the customary angle.