Music – Instruments – Stringed
Patent
1999-02-26
2000-10-10
Ip, Paul
Music
Instruments
Stringed
84253, G10C 318
Patent
active
061303720
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention concerns a striking mechanism for a string instrument, such as a piano or grand piano, and of the kind which comprises, for each string, a hammer which is made to strike the string via a power transmission when the associated key in the keyboard of the instrument is depressed, and also with a first and a second check having, respectively, a first and a second check zone for, in mutual engagement, stopping and temporarily retaining the hammer during rebound for as long as the associated key is depressed.
BACKGROUND ART
When the hammer of such string instruments has struck the string, it must be caught at a certain position during rebound. In conventional string instruments, the hammer is caught at a relatively great distance from the string.
The applicant's European Patent No. EP 0 500 701 B1, which is incorporated into the present patent application as reference, discloses a striking mechanism in which it is possible to catch the hammer at a relatively short distance from the string so that the strike can be repeated immediately.
Anyhow, it is important that the hammer is caught in such a way during rebound that it does not jump back and thereby spontaneously hits the string in an unintended repetition strike.
The catching of the hammer conventionally takes place when the check zone of one of the checks collides with the check zone of the other check resulting in a relatively sudden stopping of the swinging parts. Due to the inertia of the system, tensions arise in the rod system of the striking mechanism. The resultant of these tensions acts in the opposite direction of the rebound and will therefore, in some cases, be able to provoke the above-mentioned unintended repetition strike. Evidently, the risk is greatest when the catching of the hammer takes place near the string as is the case in the known structure of the applicant's above-mentioned EP Patent.
A known method for preventing the hammer, on the catching, from jumping so far back that it can restrike the string is to put a buffer in the form of usually a piece of soft felt between the check zones of the checks. Thereby, the braking of the swinging masses of the mechanism is softened, and the reactive forces in the resilient rod system of the striking mechanism become correspondingly smaller whereby the risk of the hammer being thrown back at the string is reduced.
However, it has appeared that even with, for example, a layer of felt between the check zones, unintended repetition strikes may occur. The reason for this is that it is not constructively possible to attain a sufficiently long braking length by, in this way, only mechanically braking the rebound.
SUMMARY OF THE INVENTION
The object of the invention is to show a striking mechanism of the type mentioned in the opening paragraph which is able to catch the hammer during rebound more safely and with a softer braking than known so far.
This is, according to the invention, achieved by the fact that, on each check zones, a magnetic or magnetizable material is placed. Now, the braking length is no longer determined by the limited thickness and compressibility of solid materials but by the extent of the magnetic field which now is present between the two check zones. This magnetic field has, in principle, an unlimited extent and can, without difficulties, be provided with sufficient strength to be able to start the braking operation already at a relatively great distance from the two check zones. The braking length is therefore long and the braking soft. At the same time, the braking is safe since the strength of the magnetic field increases by the square of the distance between the check zones.
At the final position, the two check zones can engage with each other along an outer surface on each zone. Some of the magnets or magnetic material can then be placed flushing with the respective outer surface, whereby the two check zones can accidentally hit each other during rebound with a usually undesirable, metallic sound. To efficiently eliminate this inconvenie
REFERENCES:
patent: 3979990 (1976-09-01), Hinago
patent: 5505115 (1996-04-01), Vandervoort
Ip Paul
Lockett Kim
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