Music – Instruments – Stringed
Reexamination Certificate
2001-05-17
2002-07-23
Fletcher, Marlon T. (Department: 2837)
Music
Instruments
Stringed
C084S171000, C084S243000, C084S719000, C084S744000
Reexamination Certificate
active
06423889
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a keyboard musical instrument and, more particularly, to a regulating button mechanism, a silent system cooperative therewith and a keyboard musical instrument.
DESCRIPTION OF THE RELATED ART
A silent piano is fabricated on the basis of an acoustic piano, and is fallen within the scope of the keyboard musical instrument. The silent piano is a combination of an acoustic piano, a silent system and an electronic sound generating system. A standard upright piano or a standard grand piano is available for the silent piano. Therefore, a keyboard, action mechanisms, hammer assemblies, dampers and strings are incorporated in the acoustic piano.
The electronic sound generating system includes key/hammer sensors, a data processing system, a tone generator and a sound system. The key/hammer sensors monitor the keys and/or hammers, and supply key/hammer position signals representative of current key/hammer positions to the data processing system. The data processing system periodically checks the key/hammer position signals to see whether or not any one of the keys and hammers changes the current position from the previous position. If a key/hammer has changed the current position, the data processing system specifies the key/hammer, and determines the velocity. A key code assigned to the key/hammer and the velocity are stored in music data codes together with instructions, and the music data codes are supplied to the tone generator at appropriate timing. The tone generator produces an audio signal from the music data codes, and a headphone converts the audio signal to an electronic tones. Thus, the electronic sound generating system generates electronic tones in response to the fingering on the keyboard.
The silent system includes a hammer stopper provided between the hammer assemblies and the strings, and the hammer stopper is changed between a free position and a blocking position. When the hammer stopper is staying at the free position, the hammer stopper is out of the trajectories of the hammer assemblies, and the strings are selectively struck with the hammer assemblies in response to the fingering on the keyboard. The strings vibrate so as to generate piano tones. However, when the hammer stopper is changed to the blocking position, the hammer stopper is moved into the trajectories of the hammer assemblies. Although the escape of jacks give rise to free rotation of the hammer assemblies, the hammer assemblies rebound on the hammer stopper before striking the strings, and any piano tone is not generated through the vibrations of the strings. Thus, a pianist can practice the fingering without disturbance to the neighborhood, and the silent piano is popular to the pianists who live in downtown areas of cities.
Although the hammer stopper is simply moved between the free position and the blocking position, i.e., out of the trajectories of the hammer assemblies and on the trajectories of the hammer assemblies, it is not easy for the manufacturer to adjust the hammer stopper to the most appropriate position in the narrow space between the hammer assemblies and the strings. This is because of the fact that the jacks escape from the associated hammer assemblies at a short distance between the hammer assemblies and the strings. The escape points are adjusted by regulating the distance between the hammer assemblies and the strings to a predetermined value under the condition that a tuner slowly depresses the associated keys. The predetermined value is of the order of 2 milliters in standard grand pianos. This means that the manufacturer is to install the hammer stopper in the extremely narrow space accurately. If the hammer stopper is too close to the hammer assemblies at the rest positions, the hammer assemblies are pinched between the jacks and the hammer stopper in the blocking position before the escape.
It is effective against the pinch to make the time to escape from the hammers earlier than usual. The escape takes place when the toe of the jack is brought into contact with the regulating button. The time to escape from the hammer is made earlier by decreasing the distance between the toe and the regulating button. However, the escape deeply concerns key touch unique to the acoustic piano. If the manufacturer advances the escape from the usual timing, the unique piano key touch is destroyed. For this reason, the regulation of the escape time is less desirable.
A tandem regulating button mechanism was proposed in order to change the escape point depending upon the position of the hammer stopper.
FIG. 1
shows the prior art tandem regulating button mechanism. In
FIG. 1
, the “front” is the right side, and the “rear” is the left side. A key, an action mechanism, a hammer assembly, a string and a tandem regulating button mechanism
5
are labeled with reference numerals
1
,
2
,
3
,
4
and
5
, respectively. The action mechanism
2
is held in contact with the key
1
by means of a capstan screw
2
a
, and the hammer assembly
3
is driven for free rotation by the action mechanism
2
. The action mechanism
2
, the hammer assembly
3
and the tandem regulating button mechanism
5
are supported by action brackets
6
a
, and, accordingly, the action mechanism
2
, the hammer assembly
3
and the tandem regulating button mechanism
5
assembled with the action brackets are hereinbelow referred to as “action bracket assembly”.
The action mechanism
2
includes a whippen flange
2
b
, a whippen assembly
2
c
, a jack
2
d
, a repetition lever
2
e
and a repetition spring
2
f
The whippen flange
2
b
is fixed to a whippen rail
2
g
, which is supported by the action brackets
6
a
. The whippen assembly
2
c
is rotatably connected to the whippen flange
2
b
at the rear end thereof, and forwardly projects from the whippen flange
2
b
. The jack
2
d
has an L- letter shape, and has a leg portion
2
h
and a foot portion
2
j
. The jack
2
d
is rotatably connected at a bend portion to the front end portion of the whippen assembly
2
c
, and the leg portion
2
h
is inserted into a hole formed in the repetition lever
2
e
. A toe
2
k
and a bump
2
m
are formed in the foot portion
2
j
, and the bump
2
m
is closer to the bent portion than the toe
2
k .
The prior art tandem regulating button mechanism
5
includes a regulating rail
5
a
, a plurality of first regulating buttons
5
b
, a plurality of second regulating buttons
5
c
and a shaft
5
d
. A shank flange rail
6
b
is supported by the action brackets
6
a
, and the regulating rail
5
a
is screwed to the shank flange rail
6
b
. The first regulating buttons
5
b
are hung from the regulating rail
5
a
, and are directed to the toes
2
k
of the associated jacks
2
d
. Each of the first regulating buttons
5
b
is rotatable around the center axis of a screw
5
e
so as to vary the gap between the toe
2
k
and the lower end surface thereof. On the other hand, the second regulating buttons
5
c
are connected to the shaft
5
d
by means of screws
5
f
, and the shaft
5
d
is rotatably supported by the action brackets
6
a
. The shaft
5
d
is connected to a driving mechanism (not shown), and the second regulating buttons
5
c
are swingable around the center axis of the shaft
5
d
. The second regulating buttons
5
c
are changed between the first angular position and the second angular position. When the hammer stopper
7
is changed to the free position, the second regulating buttons
5
c
are changed to the first angular position, and are moved out of the trajectory of the bump
2
m
. On the other hand, when the hammer stopper
7
is changed to the blocking position, the second regulating buttons
5
c
are changed to the second angular position, and the second regulating buttons
5
c
are moved into the trajectory of the bump
2
m
. The prior art tandem regulating button mechanism is advantageous in that the jack
2
d
escapes from the hammer assembly
3
at different speed between the two modes of operation. The toe
2
k
and the bump
2
m
are concurrently brought into
Fletcher Marlon T.
Morrison & Foerster / LLP
Yamaha Corporation
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