Music – Instruments – General features
Reexamination Certificate
2000-10-13
2001-08-28
Hsieh, Shih-Yung (Department: 2837)
Music
Instruments
General features
C084S184000, C084S185000, C084S187000, C084S192000, C029S896220
Reexamination Certificate
active
06281419
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of mounting a plate in a grand piano, and more particularly, to a method of mounting a plate on a base assembly of a grand piano in which an outer rim, a sound board, and so on have already been assembled.
2. Description of the Related Art
A plate of a grand piano comprises a back mechanism together with a back assembly comprised of an outer rim, a soundboard and so on, and serves to support tensions applied to strings attached therein.
FIGS. 1 and 2
show an example of a conventional method of mounting a plate on a back assembly. The illustrated back assembly comprises an outer rim
2
, a backpost (not shown) and a back beam
3
, which have been integrally assembled, a soundboard
4
adhered to overlay the top surfaces of these components, and so on. The soundboard
4
has been previously mounted with a long bridge
5
and a short bridge
6
on its top surface, and a plurality of sound ribs (not shown) on its bottom surface. Also, the soundboard
4
is forcedly dried before the ribs are mounted, and left in a normal state after the ribs are mounted to cause the top surface side to swell due to restrictions imposed by the sound ribs, so that a crown has been previously formed. The long bridge
5
and the short bridge
6
, in turn, have respective predetermined lengths, and have been individually worked. Specifically, each bridge is shaved on the top surface at locations at which strings are fixed (hereinafter called the “bridge shaving”) and bridge pins are struck into the bridge hooking strings (hereinafter called the “bridge pin striking”). The bridges
5
,
6
are adhered on the top surface of the soundboard
4
after such working has been completed individually on the respective bridges.
For mounting a plate
7
on the back assembly
1
constructed as described above, a set of holes consisting of dowel holes
8
a
on both sides, and a lower hole
8
b
in the middle of the dowel holes
8
a
are drilled, for example, by means of a three-fluted drill fixed to an NC machine, from the top surface of the soundboard
4
deep into the middle of the inner rim
2
at a plurality of predetermined positions along the outer periphery of the top surface of the back assembly
1
. In this event, as shown in
FIG. 2
, the depth of the dowel holes
8
a
is set with reference to the bottom surface of the inner rim
2
, such that the height of the dowel holes
8
a
from the bottom surface of the inner rim
2
to the bottom of the dowel holes
8
a
is equal to a predetermined constant height H. Next, after a dowel
9
having a predetermined length L is driven deep into the bottom of each dowel hole
8
a,
the plate
7
is carried on the dowels
9
, and mounting screws
11
are inserted into bolt holes
10
and the lower hole
8
b
previously formed through the plate
7
, and fastened to mount the plate
7
on the back assembly
1
. In this way, an installation height HF of the plate
7
(from the bottom surface of the inner rim
2
to the bottom surface of the plate
7
) is set to a constant value equal to the sum of the height H of the bottom of the dowel holes
8
a
and the length L of the dowels
9
(HF=H+L).
As described above, the long bridge
5
and the short bridge
6
are set at a predetermined thickness, and the installation height HF of the plate
7
is set at a constant value to allow a bridge pressure (a relative height between strings stretched on the plate
7
and the top surface of the long bridge
5
and the short bridge
6
) to be controlled to some extent. As a result, it is possible to eliminate a time-consuming bridge pressure adjustment (which involves planing the top surface of the long bridge
5
or the like for achieving an appropriate bridge pressure after the soundboard
4
has been mounted on the inner rim
2
), which has been traditionally performed.
While the foregoing conventional plate mounting method can relatively accurately set the installation height HF of the plate
7
with reference to the bottom surface of the inner rim
2
, the method encounters significant difficulties in correctly controlling the shape of the crown since it is formed by the swelling of the soundboard
2
itself, as stated above, and the heights of the long bridge
5
and the short bridge
6
from the bottom surface of the inner rim
2
may vary in accordance with the amount of the swelling. Thus, the heights of the long bridge
5
and the short bridge
6
inevitably vary from one piano to another, and as a result, the bridge pressure, determined by a relative height relationship between the long bridge
5
and the short bridge
6
and the plate
7
, also varies from one piano to another, causing a problem that an appropriate bridge pressure cannot be ensured.
OBJECT AND SUMMARY OF THE INVENTION
The present invention has been made in view of the problem mentioned above, and it is an object of the present invention to provide a method of mounting a plate in a grand piano which is capable of ensuring an appropriate bridge pressure in accordance with an actual amount of swelling of the soundboard and its distribution by means of a simple expedient without requiring the setting and re-adjustment of the bridge pressure.
To achieve the above object, the present invention provides a method of mounting a plate on a back assembly having a soundboard assembled therein and a bridge adhered on a top surface of the soundboard in a grand piano. The method comprising the steps of measuring the heights of the bridge from a reference plane at a plurality of predetermined positions of the bridge on the back assembly; attaching a plurality of plate bases at a plurality of positions along the outer periphery of the top surface of the back assembly at heights corresponding to the measured heights of the bridge; and carrying the plate on the plurality of plate bases, and fixing the plate carried on the plate bases to the back assembly.
According to this mounting method, the plate is mounted on the back assembly having the soundboard assembled therein with the bridge adhered on the top surface thereof, in the following manner. First, the heights of the bridge from the reference plane are measured at a plurality of positions. Then, the plurality of plate bases are attached at a plurality of positions along the outer periphery of the top surface of the back assembly at heights corresponding to the measured heights of the bridge. Then, the plate is carried on these plate bases, and fixed on the back assembly as it remains carried on the plate bases.
As described above, the mounting method of the present invention measures the actual heights of the bridge with the soundboard assembled in the back assembly, and the plurality of plate bases are attached to the back assembly at predetermined heights in accordance with the measured heights of the bridge. Therefore, a relative height relationship between the bridge and the plate fixed as carried on the plate bases, i.e. the bridge pressure can be optimally controlled in accordance with the actual amount of swelling of the soundboard previously formed thereon. As a result, an optimal bridge pressure can be ensured with the plate mounted in the manner described above, thereby eliminating subsequent bridge pressure setting and re-adjustment.
Preferably, in the foregoing method, the predetermined heights of the plurality of plate bases are individually determined in accordance with the height of the bridge measured at the position closest to each of the plate bases.
In this preferred form, since the plurality of plate bases are individually determined in accordance with the height of the bridge measured at the position closest to each plate base, an optimal bridge pressure can be accurately ensured in accordance with the actual amount of swelling of the soundboard previously formed thereon and its distribution.
Also preferably, in the foregoing method, the plurality of plate bases comprise a plurality of buried members mutually having the same predetermined height,
Crowell & Moring , L.L.P.
Hsieh Shih-yung
Kabushiki Kaisha Kawai Gakki Seisakusho
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