GB2289157A

GB2289157A - Piano action with hammer disabling function

Info

Publication number: GB2289157A
Application number: GB9509072A
Authority: GB
Inventors: Gabor Bartos
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-05-04
Filing date: 1995-05-04
Publication date: 1995-11-08
Also published as: GB9509072D0; GB9408852D0

Abstract

Thereis disclosed a hammer disabling mechanism for a piano having strings 13, pivoted hammers 12 for striking the strings and a hammer operating lever arrangement including lever jacks 14 urged by the piano keys 11 against the hammers near (126) their pivots to propel them towards the strings, the hammers having balance hammers 12c held by catchers 10 on rebound from the strings, the disabling mechanism comprising wedge means 15 operable to act on the lever jacks to push them to one side and prevent them engaging the hammers when the keys are struck and hammer displacing means 31, 32, 43 operative simultaneously to displace the hammers to allow the catchers full movement on depression of the keys by displacing the balance hammers so that the keys can be depressed to their full extent as if the disabling mechanism were inoperative. The disabling action is thus transparent to the key operator. <IMAGE>

Description

KEYBOARD MECHANISM This invention relates to a keyboard mechanism and in particular to a piano mechanism.

A piano mechanism comprises a key, which constitutes a lever on a pivot. Striking the key raises the end of the lever beyond the pivot, which raises one side of a smaller lever which carries a lever jack which in turn urges the hammer against the string. At the same time, the smaller lever moves a further lever to lift the damper from the string so that the note will sound and continue to sound so long as the damper is held off the string.

The jack is pivotally mounted on the said small lever so that it can move (against a light spring force) out of the path of the returning hammer which is held by a back check arrangement against bouncing back on the string.

WO 93/19454 discloses a harpsichord mechanism that can be incorporated (even retro-fitted) in both upright and grand pianos. One embodiment of such mechanism is described in which a wedge is interposed between elements of the hammer-operating lever arrangement to cause the hammer to stop short of the string when the key is depressed.

In fact, since the harpsichord modification was disclosed, it has became popular with piano manufacturers to incorporate an electronic synthesiser or like equipment operated by switches disposed beneath the keys, and silent keyboard arrangements have been proposed for use with such equipment.

With the exception of what is disclosed in WO 93/19454, all commercially offered silent keyboard arrangements to date have involved introducing an element into the path of the hammer (whether this be the hammer proper or the balance hammer which is essentially a counterweight) to arrest it before it strikes the string.

All such arrangements have the serious disadvantage that they materially affect the keyboard action. And, because of the repeated impacts the piano mechanism was not designed to take, there will be undue wear and a tendency for the action to go rapidly out of its correct adjustment.

The arrangement disclosed in WO 93/19454 does not suffer these disadvantages, and the present invention represents a further improvement over the arrangement disclosed in WO 93/19454.

The invention comprises a hammer disabling mechanism for a piano having strings, pivoted hammers for striking the strings and a hammer operating lever arrangement including lever jacks urged by the piano keys against the hammers near their pivots to propel them towards the strings, the hammers having balance hammers held by catchers on rebound from the strings, the disabling mechanism comprising wedge means operable to act on the lever jacks to prevent them engaging the hammers when the keys are struck and hammer displacing means operative simultaneously to displace the hammers to allow the catchers full movement on depression of the keys by displacing the balance hammers so that the keys can be depressed to their full extent as if the disabling mechanism were inoperative.

The wedge means may comprise blades on a shaft extending from end to end of the action and mounted for limited rotation about its axis so that the blades can contact the lever jacks and move them, on their pivots, away from the hammer butts, against their spring pressure. Said shaft may have an arm attached for rotation therewith together with the blade means and forming part of the hammer displacing means. Said arm may be acted on by a disabling mechanism operating lever accessible from the keyboard. Said arm may be connected to the operating lever by a Bowden cable.

The hammer displacing means may comprise means (independent of the soft pedal) moving the half blow rail to its half blow position.

The arm aforesaid may be connected to the half blow rail to move the half blow rail to its half blow position when the shaft is rotated to disable the hammers. Said arm may be connected to the half blow rail by a lost motion arrangement, which may comprise a flexible wire that can bend when the half blow rail is operated by the soft pedal but the disabling mechanism is inoperative.

The mechanism may be installed in a piano to give a silent keyboard for practice, but the piano may also have piano key operated electric switches connected to an electronic synthesiser or like arrangement.

One embodiment of hammer disabling mechanism for a piano according to the invention will now be described with reference to the accompanying drawings in which Figure 1 is a side elevation of an upright piano action with the disabling mechanism inoperative, Figure 2 is a side elevation like Figure 1 with the disabling mechanism operative, and Figure 3 is a perspective view of the disabling mechanism in its ready-for-fitting condition.

The drawings illustrate a hammer disabling mechanism for an upright piano having strings 13, pivoted hammers 12 for striking the srings 13 and a hammer operating lever arrangement including lever jacks 14 which push on the hammers 12 near their pivots 12a to propel them towards the strings 13. The hammers 12 have balance hammers 12c held by catchers 10 on rebound from the strings 13. The disabling mechanism comprises wedge means 15 operable to act on the lever jacks 14 to prevent them engaging the hammers 12 when the keys 11 are struck and hammer displacing means 16 operative simultaneously to displace the hammers 12 to allow the catchers 10 full movement on depression of the keys 11 by displacing the balance hammers so that the keys 11 can be depressed to their full extent as if the disabling mechanism were inoperative, or, indeed, not present.

The key 11 is pivoted at 21 and constrained against lateral movement by a fixed peg 22 engaging a slot in the underside of the key 11. The end 11b of the key distal from the ivory end 11a rests normally on a cushioned support 23 and the key 11 may have a weight 24 at said distal end lib.

A lever 25 pivoted at 26 is, on the right hand side of the pivot 26 as viewed in the drawings, moved upwardly by an adjustable stud 27 in the key 11 acting against a cushion 28. The lever jack 14 is pivotally mounted on the lever 25 on this same right hand side of the pivot 26 and urged counterclockwise, as viewed, by a compression spring 29 so that the end 14a of the lever jack 14 normally lies beneath the contact face 12b of the hammer 12 and, when the key 11 is struck, pushes the face 12b to propel the hammer 12 towards the string 13.

The lever 25 a-lso carries the catcher 10 which cooperates with the balance hammer 12c to prevent the hammer 12 rebounding on to the string - the catcher 10 has a cushion 10a that contacts the balance hammer 12c when the hammer 12 first returns after striking the string 13, if the key 11 is still depressed at this moment, and holds it against rebounding.

The hammer 12 normally rests on a cushion 31 on the half blow rail 32 which sits on the hammer rest rail 33.

On the left hand side of lever 25 is an upstanding finger 34 that pushes against a cushion 37 on a lever 38 pivoted at 39 which carries the damper 41 so as to lift the damper 41 from the string 13 when the key 11 is struck.

The wedge means 15 comprise blades on a shaft 44 extending in bearings 45 from end to end of the keyboard and mounted for limited rotation about its axis. The shaft 44 has an arm 46 attached for rotation therewith together with the blades 15. When the blades rotate to the Figures 2 position, they move the jacks 14 away from the butts of the hammers 12. When the disabling mechanism is made inoperative, the springs 29 restore the jacks 14 to their hammer engaging positions.

Said arm 46 is acted on by a disabling mechansim operating lever 47 accessible from the keyboard and connected to the lever 47 by a Bowden cable 48.

The hammer displacing means 16 comprise means (independent of the soft pedal) moving the half blow rail 32 to its half blow position.

The arm 46 is connected to the half blow rail 32 to move the rail 32 to its half blow position (Figure 2) when the shaft 44 is rotated to disable the hammers 12.

The arm 46 is connected to the half blow rail 32 by a lost motion arrangement that comprises a flexible wire 43 (threaded through a hole 43b in a bracket 43a attached for the purpose to the half blow rail 32). The wire 43 can bend (or run through the hole 43b) when the half blow rail 32 is operated by the soft pedal but the disabling mechanism is inoperative.

These combined movements put the locus of the jacks 14 well clear of the hammers 12 when the keys 11 are depressed, so that the hammers are not propelled towards the strings, and the keyboard is silenced.

The balance hammers 12c - which, because the hammers 12 are not moved by striking the keys 11 with the disabling mechanism operative, would interfere with the movement of the catchers 10 which are mounted on the levers 25 and hence would present the keys 11 being fully depressed - now are moved to a position where they do not interfere with the catchers 10, thus enabling the keys 12 to be fully depressed.

The full normal motion of the key 11 is permitted. The feel or touch of the keyboard is affected much less by the mechanism than by mechanisms that allow the hammers to be propelled towards the strings and arrest them.

Electric switches 49 of known type can be installed beneath the keys 11 connected to an electronic synthesiser or like arrangement (not shown, but conventional). The fact that full key movement is permitted with the disabling mechanism of the invention also facilitates optimum arrangements for the switches.

Claims

1. A hammer disabling mechanism for a piano having strings, pivoted hammers for striking the strings and a hammer operating lever arrangement including lever jacks urged by the piano keys against the hammer near their pivots to propel them towards the strings, the hammer having balance hammers held by catchers on rebound from the strings, the disabling mechanism comprising wedge means operable to act on the lever jacks to prevent then engaging the hammers when they keys are struck and hammer displacing means operative simultaneously to displace the hammers to allow the catchers full movement on depression of the keys by displacing the balance hammers so that the keys can be depressed to their full extent as if the disabling mechanism were inoperative.

2. A mechanism according to claim 1, in which the wedge means comprise blades on a shaft extending from end to end of the keyboard and mounted for limited rotation about its axis.

3. A mechanism according to claim 2, in which said shaft has an arm attached for rotation therewith together with the blade means and forming part of the hammer displacing means.

4. A mechanism according to claim 3, in which said arm is acted on by a disabling mechanism operating lever accessible from the keyboard.

5. A mechanism according to claim 4, on which said arm is connected to the operating lever by a Bowden cable.

6. A mechanism according to any one of claims 1 to 5, in which the hammer displacing means comprise means (independent of the soft pedal) moving the half blow rail to its half blow position.

7. A mechanism according to claim 3, in which said arm is connected to the half blow rail to move the half blow rail to its half blow position when the shaft is rotated to disable the hammers

8. A mechanism according to claim 7, in which said arm is connected to the half blow rail by a lost motion arrangement.

9. A mechanism, according to claim 8, in which said lost motion arrangement comprises a flexible wire that can bend when the half blow rail is operated by the soft pedal but the disabling mechanism is inoperative.

10. A mechanism according to any one of claims 1 to 9, installed in a piano to give a silent keyboard for practice.

11. A mechanism according to any one of claims 1 to 10, installed in a piano together with piano key operated electric switches connected to an electronic synthesizer or like arrangement.