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Description  |
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FIELD OF THE INVENTION
This invention relates to a keyboard musical instrument and, more
particularly, to a keyboard musical instrument equipped with a hammer
stopper implemented by a parallelogram link mechanism.
DESCRIPTION OF THE RELATED ART
The keyboard musical instrument is a compromise between an acoustic piano
and an electronic keyboard, and a hammer stopper and an electronic sound
generating system are installed inside the acoustic piano. A player
changes the hammer stopper between a free position and a blocking
position, and plays a tune on the keyboard so as to generate acoustic
sounds or electronic sounds depending upon the position of the hammer
stopper. When the hammer stopper stays in the free position, depressed
keys drive the associated hammers for rotation, and the hammers strike
associated strings. The strings vibrate, and generate acoustic sound. On
the other hand, when the hammer stopper is changed to the blocking
position, the hammer rebounds on the hammer stopper before the strike at
the strings, and the acoustic sound is never generated. However, a key
sensor detects the motion of the depressed key, and a headphone generates
an electronic sound from an audio signal produced on the basis of the key
motion. Thus, the hammer stopper changes the sound source between the
strings and the tone generator.
The hammer stopper is, by way of example, provided between the hammer
shanks and the strings. However, the space between the hammer shanks and
the strings is so narrow that the manufacturer hardly installs a large
hammer stopper in the narrow space. A damper assembly also occupies the
narrow space, and the hammer stopper is expected not to interfere with the
motion of the damper assembly. Major component parts of the acoustic piano
are made of wood, and require large margin for the assemblage. This means
that the damper mechanism and the hammer stopper require large tolerances,
and the large tolerances make the space further narrower. Thus, it is
preferable to design the hammer stopper to be smaller.
As described hereinbefore, the hammer stopper is changed between the free
position and the blocking position. Even if the hammer stopper occupies
narrow space, the hammer stopper requires additional space during the
motion between the free position and the blocking position. The hammer
stopper may interfere with another component part such as the damper
assembly during the motion. For this reason, it is preferable to design a
driving mechanism to change the hammer stopper between the free position
and the blocking position through small motion.
A typical example of the hammer stopper is disclosed in Japanese Patent
Publication of Unexamined Application (JPA) No. 8-123403, and the prior
art hammer stopper is changed between the free position and the blocking
position through rotation over 90 degrees. Cushion members project from a
shaft member, and are rotated together with the shaft member. When the
hammer stopper enters into the blocking position, the cushion members are
opposed to the hammer shank, and the hammer shank rebound on the cushion
member. On the other hand, when the hammer stopper is changed to the free
position, the cushion members turn over 90 degrees, and are shunted from
the trajectory of the hammer shank. The prior art hammer stopper requires
not only the space occupied at both of the free and blocking positions but
also the space along the trajectory of the cushion members. Thus, the
prior art hammer stopper requires the wide space.
Another prior art hammer stopper is directly connected to a wire, and a
player pulls the wire for changing the prior art hammer stopper. The prior
art hammer stopper is advanced toward the hammer shank at the home
position, and is spaced therefrom. Thus, the wire moves the hammer stopper
in the direction substantially identical with the direction of the turning
motion of the hammer shank. In this instance, the manufacturer is expected
to pass the wire through the complicated key action mechanism. Even if the
manufacturer succeeds in the hard work, the terminal end portion of the
wire connected to the hammer stopper is not always matched with the
direction of the motion of the hammer stopper. In this situation, when the
player pulls the wire, the force is not effectively transferred to the
hammer stopper. In order to smoothly move the hammer stopper in spite of
the in consistency in direction between the motion of the hammer stopper
and the motion of the wire, a suitable guide member is required for the
hammer stopper. This results in increase of the component parts of the
hammer stopper. It is desirable for the hammer stopper to decrease the
component parts so as to reduce the production cost.
SUMMARY OF THE INVENTION
It is therefore an important object of the present invention to provide a
hammer stopper which is free from interference with another component part
without increase of components parts.
To accomplish the object, the present invention proposes to use a
parallelogram crank mechanism for changing a movable stopper between a
free position and a blocking position.
In accordance with one aspect of the present invention, there is provided a
keyboard musical instrument comprising an acoustic piano including a
keyboard having a plurality of keys turnable with respect to a stationary
board member, a plurality of string means vibratory for generating
acoustic sounds, and a plurality of key action mechanisms respectively
linked with the plurality of keys and having respective hammers each
driven for rotation along a trajectory so as to strike associated one of
the plurality of string means when associated one of the plurality of keys
is depressed, an electronic sound generating system monitoring the
plurality of keys and generating an electronic sounds when one of the
plurality of keys is depressed, and a silent mechanism including a movable
stopper changed between a free position and a blocking position, the
movable stopper in the free position being out of the trajectory of each
of the hammers so as to allow the aforesaid each of the hammers to strike
associated one of the plurality of string means, the movable stopper in
the blocking position being positioned in the trajectory of the aforesaid
each of the hammers so as to interrupt the aforesaid each of the hammers
before a strike against associated one of the plurality of string means, a
stationary member stationary with respect to the stationary board member,
two link members having respective first ends turnably connected to the
movable stopper and respective second ends turnably connected to the
stationary member so as to form a parallelogram crank mechanism together
with the stationary member and the movable stopper, and a driving means
connected to at least one of the two link members and the movable stopper
and changing an angular position of the two link members so as to change
the movable stopper between the free position and the blocking position.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the keyboard musical instrument will be more
clearly understood from the following description taken in conjunction
with the accompanying drawings in which:
FIG. 1 is a side view showing essential parts of a keyboard musical
instrument according to the present invention;
FIG. 2 is a side view showing a silent mechanism incorporated in the
keyboard musical instrument;
FIG. 3 is a perspective view showing the structure of a hammer stopper
incorporated in the keyboard musical instrument;
FIG. 4 is a perspective view showing the left end portion of the hammer
stopper;
FIG. 5 is a perspective view showing the right end portion of the hammer
stopper;
FIG. 6 is a side view showing a change-over mechanism connected to the
hammer stopper;
FIG. 7 is a front view showing a keyboard musical instrument equipped with
the hammer stopper shown in FIG. 3;
FIG. 8 is a front view showing another keyboard musical instrument
according to the present invention;
FIG. 9 is a side view showing the structure of another change-over
mechanism available for the silent mechanism incorporated in the keyboard
musical instrument according to the present invention;
FIG. 10 is a side view showing the movable stopper in a free position; and
FIG. 11 is a side view showing the movable stopper in a blocking position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Structure of Keyboard Musical Instrument
FIG. 1 illustrates the structure of a keyboard musical instrument embodying
the present invention. The keyboard musical instrument largely comprises
an acoustic piano 100, an electronic sound generating system 200 and a
silent mechanism 300. In the following description, term "front" means a
position closer to a pianist sitting in front of the upright piano 100
than "rear" position, and a direction between a front position and a rear
position is referred to as "longitudinal direction". Term "lateral"
indicates the perpendicular direction to the longitudinal direction.
The acoustic piano is a standard upright piano, and includes a keyboard 101
mounted on a key bed 102. The keyboard 101 consists of a plurality of
black keys 103 and a plurality of white keys 104, and the black/white keys
103/104 are arranged in the lateral direction. Notes of the scale are
respectively assigned to the black/white keys 103/104, and a player
specifies a tone by depressing one of the black/white keys 103/104.
The black/white keys 103/104 are turnable with respect to a balance rail
(not shown) between respective rest positions and respective end
positions. When a player does not exert force on the black/white key
103/104, the black/white key 103/104 is staying in the rest position. When
the player depresses the black/white key 103/104, the black/white key
103/104 turns from the rest position toward the end position. However, if
the player releases the black/white key 103/104, the black/white key
103/104 returns to the rest position.
The acoustic piano 100 further includes sets of strings 105 corresponding
to the black/white keys. The sets of strings 105 are vibratory, and
respectively generate acoustic sounds having the notes.
The acoustic piano 100 further comprises a plurality of key action
mechanisms 106 respectively linked with the black/white keys 103/104. The
key action mechanism 106 is actuated by the associated black/white key
103/104 so as to strike the associated set of strings 105, and is broken
down into a whippen assembly 107, a hammer assembly 108, a regulating
mechanism 109 and a damper assembly 110.
The whippen assembly 107 includes a whippen flange 111 fixed to a center
rail 112, a whippen 113 turnably connected at one end thereof to the
whippen flange 111, a whippen heel 114 downwardly projecting from the
lower surface of the whippen 113 and a jack flange 115 upright from the
other end portion ofthe whippen 113. A capstan button 116 projects from
the rear end portion ofthe associated black/white key 103/104, and is held
in contact with the whippen heel 114. While the associated black/white key
103/104 is turning from the rest position toward the end position, the
capstan button 116 upwardly pushes the whippen heel 114, and the whippen
113 turns around the whippen flange 111 in the counter clockwise
direction.
The whippen assembly 107 further includes a jack 117 turnably supported by
the jack flange 115, a jack spring 118 urging the jack 17 to turn in the
counter clockwise direction, a damper spoon 119 upright from one end
portion of the whippen 113, a back check 120 upright from the other end
portion of the whippen 113 and a bridle wire 121 also upright from the
other end portion of the whippen 113. The damper spoon 119 is described in
conjunction with the damper assembly 110, and the back check 120 and the
bridle wire 121 cooperate with the hammer assembly 108 as will be
described hereinlater.
The hammer assembly 108 includes a butt flange 122 fixed to the center rail
112, a hammer butt 123 turnably connected to the butt flange 122, a hammer
shank 124 projecting from the hammer butt 123, a hammer head 125 fixed to
the leading end of the hammer shank 124 and a butt spring 126 urging the
hammer butt 123 in the clockwise direction so as to hold the hammer shank
124 in contact with a hammer rail cloth 127 attached to a hammer rail 128.
The position where the hammer shanks 124 are held in contact with the
hammer rail cloth 127 is hereinbelow referred to as "home position".
The hammer assembly 108 further includes a butt skin 129 bonded to a lower
surface of the hammer butt 123, and a leading end portion 117a of the jack
117 kicks the butt skin 129 so as to drive the hammer butt 123 for
rotation in the counter clockwise direction around the butt flange 122.
The hammer assembly 108 further includes a catcher shank 130 projecting
from the hammer butt 123 and a catcher 131 attached to the leading end of
the catcher shank 130. The catcher shank 130 is spaced from the hammer
shank 124 at 90 degrees, and the catcher 131 is opposed to the back check
120. The catcher 131 is connected through a bridle tape 132 to the bridle
wire 121. The bridle tape 132 links the returning motion of the hammer
assembly 108 with the returning motion of the whippen assembly 107, and
prevents the set of strings 105 from double strike. The back check 120
receives the catcher 131 during the rotation after the rebound.
While the associated black/white key 103/104 is staying in the rest
position, the capstan button 116 horizontally maintains the whippen 113,
the hammer shank 124 is resting on the damper rail cloth 127, and the jack
117 is held in contact with the butt skin 129 as indicated by the real
lines in FIG. 1. The pianist is assumed to depress the associated
black/white key 103/104. The associated black/white key 103/104 is turning
from the rest position toward the end position. The capstan button 116
upwardly pushes the whippen heel 114, and the jack 117 turns around the
whippen flange 111 together with the whippen 113. The jack 117 pushes the
hammer butt 123, and the hammer shank 124 and the hammer head 125 turn
around the butt flange 122 together with the hammer butt 123. When the
associated black/white key 103/104 reaches a certain point between the
rest position and the end position, the jack 117 kicks the butt skin 129,
and the hammer butt 123 escapes from the jack 117 so as to start the free
rotation toward the set of strings 105.
The regulating mechanism 109 determines the certain point. The regulating
mechanism 109 includes regulating brackets 133 fixed to the center rail
112, a regulating rail 134 supported by the regulating brackets 133,
regulating buttons 135 opposed to the tows 117b of the jacks 117 and
regulating screws 136 connecting the regulating buttons 135 to the
regulating rail 134. When the tow 117b is brought into contact with the
regulating button 135 during the rotation together with the whippen 113,
the reaction causes the jack 117 to quickly turn around the jack flange
115, and the jack 117 kicks the butt skin 129. Thus, the tow 117b is
advanced toward the regulating button 135, and the jack 117 kicks the butt
skin 129 upon contact with the regulating button. If a player wants to
make the certain point earlier, the player rotates the regulating screw
136 so as to decrease the gap.
The damper assembly 110 includes a damper flange 137 fixed to the center
rail 112, a damper lever 138 rotatably supported by the damper flange 137,
a damper wire 139 projecting from the damper lever 138, a damper head 140
fixed to the leading end of the damper wire 139 and a damper spring 141
urging the damper lever 138 in the counter clockwise direction so as to
hold the lower end portion in contact with the damper spoon 119. While the
whippen 113 is turning in the counter clockwise direction, the damper
spoon 119 declines, and pushes the damper lever 138. The damper lever 138
is rotated in the clockwise direction against the damper spring 141, and
the damper head 140 is spaced from the set of strings 105. On the
contrary, the whippen 113 turns in the clockwise direction upon release of
the black/white key 103/104, and the damper spring 141 urges the damper
lever 138 to turn in the counter clockwise direction. As a result, the
damper head 140 is brought into contact with the set of strings 105,
again.
While the black/white key 103/104 is turning from the rest position to the
end position, the damper spoon 119 firstly spaces the damper head from the
set of strings 105, and, thereafter, the jack 117 and the regulating
button 135 allow the hammer assembly 110 to escape from the set of strings
105. The hammer head 125 strikes the set of strings 105, and rebounds
thereon. After the release of the depressed black/white key 103/104, the
damper head 140 is brought into contact with the set of strings 105, and
takes up the vibrations.
The electronic sound generating system 200 includes a plurality of key
sensors 201, a controller 202 and a headphone 203. The key sensors 201
respectively monitor the black/white keys 103/104, and produce key
position signals KP. The key position signal KP is representative of the
motion of the associated black/white key 103/104, and is supplied to the
controller 202.
In this instance, the key sensor 201 is implemented by a shutter plate 204
and a photo-interrupter 205. The shutter plate 204 is attached to the
lower surface of the associated black/white key 103/104, and interrupts
optical beams of the photo-interrupter 205. The photo-interrupter 205
changes the key position signal KP depending upon the photo-interruption
of the shutter plate 204. The controller 202 determines the current key
position on the trajectory between the rest position and the end position
on the basis of the key position signal KP.
The controller 202 instructs a tone generator (not shown) incorporated
therein to produce an audio signal AD at a certain point on the
trajectory, and the headphone 203 produces an electronic sound from the
audio signal AD with the note assigned the depressed black/white key
103/104. On the other hand, while the depressed black/white key 103/104 is
released, the controller 202 instructs the tone generator to stop the
generation of the audio signal at another certain point on the trajectory,
and the electronic signal is extinguished.
The silent mechanism 300 is provided in a space between the hammer
assemblies 108 and the sets of strings 105, and is detailed in FIG. 2. The
silent mechanism 300 changes the keyboard musical instrument between an
acoustic sound mode and an electronic sound mode. The keyboard musical
instrument in the acoustic sound mode generates the acoustic sounds
through the vibrations of the sets of strings 105, and the silent
mechanism 300 stops the generation of the acoustic sounds in the
electronic sound mode. However, the electronic sound generating system 200
generates the electronic sounds, and the pianism hears the electronic
sounds produced by the headphone 203.
The silent mechanism 300 largely comprises a hammer stopper 301 and a
change-over mechanism 302, and the hammer stopper 301 is provided in the
space between the sets of strings 105 and the hammer shanks 124 at the
home position. Reference numerals 150 and 151 designate action brackets
respectively provided on both sides of the array of the hammer assemblies
108. However, the action bracket 150 on the left side is partially cut
away.
The hammer stopper 301 is illustrated in detail in FIG. 3, and both end
portions of the hammer stopper 301 are enlarged in FIGS. 4 and 5. The
hammer stopper 301 includes a pair of supporting brackets 303, and the
supporting brackets 303 are attached to the action brackets 150,
respectively. In detail, each of the supporting brackets 303 has a
horizontal portion 303a and vertical wall portion 303b upright from the
horizontal portion 303a. The vertical wall portion 303b is curved at 90
degrees, and a threaded through-hole 303c is formed in the vertical wall
portion 303b. Each of the action brackets 150/151 has a vertical portion
150a, and a threaded through-hole is also formed in the vertical portion
150a. The threaded through-hole 303c is aligned with the threaded
through-hole formed in the vertical portion 150a, and a bolt 304 is
screwed into the threaded through-holes so as to fix the supporting
bracket 303 to the action bracket 150/151.
The hammer stopper 301 further includes three coupling units 305, a stopper
rail 306, a plurality of brackets 307a/307b/307c fixed to the stopper rail
306 by means of bolts 308 and a plurality of cushion members
309a/309b/309c attached to the brackets 307a/307b/307c, respectively. The
coupling units 305 are provided on both ends of the stopper rail 306 and
an intermediate portion. In this instance, the cushion members
309a/309b/309c are formed of urethane foam. However, other shock absorbing
material such as felt covered with artificial leather is available for the
cushion members 309a/309b/309c. The stopper rail 306, the brackets
307a/307b/307c and the cushion members 309a/309b/309c as a whole
constitute a movable stopper 310.
The black/white keys 103/104 are divided into three groups, i.e., the first
key group for low-pitched tones, the second key group for middle-pitched
tones and the third key group for high-pitched tones, and the cushion
members 309a/309b/309c are provided for the hammer assemblies 108
associated with the first key group, the hammer assemblies 108 associated
with the second key group and the hammer assemblies 108 for the third key
group. Through-holes 307d are formed in the brackets 307a/307b/307c, and
are elongated in the longitudinal direction. For this reason, the
manufacturer can vary the gap between the front surface 306a of the
stopper rail 306 and the rear surfaces 307e of the brackets 307a/307b/
307c, and the cushion members 309a/ 309b/ 309d are independently adjusted
to respective appropriate positions for blocking the strings 105 from the
hammer heads 125 after the escape from the jacks 117. Accordingly, the
cushion members 309a/309b/309c are not expected to be equal in thickness.
In the upright piano, the strings 105 for the low-pitched tones cross the
strings 105 for the middle-pitched tones and the high-pitched tones, and
the hammer heads 125 and the damper heads 140 for some strings 105 closer
to the low pitched tones are higher than those for the other strings. For
this reason, the stopper rail 306 is substantially straight from the right
portion to a middle portion, and is upwardly bent at a certain point 307e
in the middle portion. Accordingly, the bracket 307b and the cushion
member 309b are bent so as to be matched with the stopper rail 306. The
stopper rail 306 is downwardly bend from the middle portion to the left
portion, and an oblique portion 306a connects the middle portion to the
left portion so that the bracket 307a is lower than the other brackets
307b/ 307c. Thus, the stopper rail 306 regulates the cushion members
309a/309b/309c to appropriate height so that the movable stopper 310
allows the hammer shanks 124 to appropriately rebound thereon without an
interference with the damper assemblies 110 and the hammer heads 125.
A bracket 310a is attached to the lower surface of a connecting portion
306b between the right portion and the middle portion of the stopper rail
306, and a center stay 310b is provided between the center rail 112 and
the bracket 310a. One of the coupling units 305 is provided between the
bracket 310a and the center stay 310b. The center stay 310b supports the
load of the movable stopper 310, and prevents the movable stopper 310 from
undesirable deformation.
The stopper rail 306 is connected at both end portions thereto to the
coupling units 305 by means of bolts 311, and the coupling units 305 are
supported by the supporting brackets 303.
The coupling unit 305 includes a bracket 305a attached to an end portion
306fc of the stopper rail 306, and the bracket 305a has a horizontal
portion and a vertical portion. A through-hole 305b is formed in the
horizontal portion of the bracket 305a, and is elongated in the lateral
direction. The bolts 311 are screwed through the through-hole 305b into
the end portion 306c, and the manufacturer can regulate the position of
the cushion members 309a/309b/309c by changing the length overlapped
between the end portions 306c and the brackets 305a.
The coupling unit 305 further includes pins 305c/305d implanted into the
vertical portion of the bracket 305a, pin members 305e/305f implanted into
the vertical portion of the supporting bracket 303 and link members
305g/305h rotatably engaged with the pins 305c/305d and 305e/305f. The
pins 305c/305d are spaced from each other in the longitudinal direction,
and the pins 305e/305f are also spaced from each other in the longitudinal
direction. The pins 305c/305d are slightly deviated from the pins
305e/305f, and the pins 305c/305d/305e/305f are located at the four
corners of a parallelogram as will be seen in FIG. 2.
The link members 305g has an upper bobbin, a lower bobbin and a connecting
plate between the upper bobbin and the lower bobbin, and the pin 305c and
the pin 305e are inserted into the hole formed in the upper bobbin and the
hole formed in the lower bobbin, respectively. Clamp rings 305i are
engaged with the pins 305c/305d, and the upper and lower bobbins of the
link member 305g are rotatable around the pins 305c and 305e,
respectively.
The link member 305h also has an upper bobbin, a lower bobbin, a connecting
plate 305j between the upper bobbin and the lower bobbin and a journal
305k attached to the leading end of the connecting plate 305j, and the
connecting plate is curved so that the journal 305k projects from the
vertical portion 303b of the supporting bracket 303. The journal 305k has
C-letter like cross section, and a slit 305m is open to the cylindrical
inner space 305n. The clamp rings 305i are also engaged with the pins 305d
and 305f, and the upper bobbin and the lower bobbin are rotatable around
the pins 305d/305f, respectively. Thus, the link members 305g/305h, the
supporting block 303 and the bracket 305a form a parallelogram crank
mechanism, and the movable stopper 310 turns around the pin members
305e/305f.
The coupling unit 305 further includes a torsion coil spring 305p. The
torsion coil spring 305p has a first arm engaged with the upper bobbin of
the link member 305g and a second arm engaged with the lower bobbin of the
link member 305h, and urges the link members 305g/305h so that virtual
line between the pins 305c and 305e makes a certain angle with virtual
line between the pins 305e and 305f.
The coupling unit between the bracket 310a and the center stay 310b is
similar in arrangement to the coupling units 305 on both sides of the
movable stopper 310. The coupling unit at the intermediate portion of the
movable stopper 310 also has the bracket 305a attached to the bracket
310a, and the pins 305e/305f are fixed to the center stay 310b.
The change-over mechanism 302 is illustrated in FIG. 6 in detail, and a
pianist changes the movable stopper 310 between the free position and the
blocking position by means of the change-over mechanism 302.
The change-over mechanism 302 largely comprises a pedal sub-mechanism 320,
a pair of flexible wires 321 and a glide structure 322. A cylindrical pin
member 323 is connected to the leading end of the flexible wire 321, and
is inserted into the inner cylindrical space 305n. For this reason, the
cylindrical pin member 323 is rotatable with respect to the journal 305k,
and the flexible wire 321 exerts pulling force on the journal 305k without
disconnection from the journal 305k. The leadings end portion of the
flexible wire 321 passes through the slit 305m, and downwardly extends
from the cylindrical pin member 323. The flexible wire 321 passes through
the key bed 102, and is terminated at a coil member 325.
The pedal sub-mechanism 320 includes a foot pedal 320a projecting through a
slit 160a formed in a bottom sill 160 ofthe acoustic piano 100 and a
connecting member turnable around a pin 320c and a hook 320d upright from
the connecting member 320b. The foot pedal 320a is fixed to the leading
end of the connecting member 320b, and the hook 320d is engaged with the
coil member 325. Though not shown in FIG. 6, the pedal sub-mechanism 320
is associated with a ratchet mechanism, and the ratchet mechanism
maintains the foot pedal 320a at the depressed position. When the pianism
further depresses the foot pedal 320a, the ratchet mechanism is released,
and torsion coil member 305p allows the foot pedal 320a to return to the
rest position.
The guide structure 322 includes flexible sheathes 322a and a bracket 322b
attached to the lower surface of the key bed 102. The flexible wires 321
are guided by the flexible sheathes 322a to the coupling units 305 at both
sides of the movable stopper 310, and the coil members 325 of both
flexible wires 321 are engaged with the hook 320d. However, the pedal
sub-mechanism 320 is not linked with the coupling unit between the bracket
310a and the center stay 310b.
Each of the flexible sheaths 322a is fixed at one end thereof to the
horizontal portion 303a of the supporting bracket 303 and at the other end
thereto to the bracket 322b. The flexible sheath 322a passes through a
through-hole 102a formed in the key bed 102, and is twice bent so that the
flexible wire 321 is vertically connected to the cylindrical pin member
323 and the coil member 325 at both end thereof When a pianist presses
down the pedal 320a, the flexible wire 321 effectively transfers the force
to the coupling unit 305, and causes the movable stopper 310 to turn
between the free position and the blocking position.
The silent mechanism 300 is simple, and the manufacturer easily installs
the silent mechanism 300 in the upright piano 100. The movable stopper 310
is advanced toward the hammer shanks 124 at the home position, and is
spaced from the hammer shanks 124 at the home position. Therefore, the
trajectory of the movable stopper 310 is matched with the trajectory of
the hammer shanks 124, and the movable stopper 124 occupies additional
space only when the movable stopper 124 is staying at the free position.
Thus, the movable stopper 310 requires extremely narrow space, and does
not interfere with other component parts such as damper assembly 110.
FIG. 7 illustrates the silent mechanism 300 installed inside a piano case
170 of the acoustic piano 100. The keyboard 101 is covered with a fall
board 171. Though not shown in FIG. 7, the key action mechanisms 106 and
the sets of strings 105 are installed inside the piano case 170, and the
hammer stopper 301 is provided in the lateral direction. The pair of
parallelogram crank mechanisms on both sides of the hammer stopper 301 is
connected through the flexible wires 321 to the pedal 320a.
The change-over mechanism 302 may be connected to the coupling unit 305 at
one end of the movable stopper 310 and the coupling unit 305 at the
intermediate point as shown in FIG. 8. In this instance, the span between
the coupling units 305 to be driven is short, and the movable stopper 310
is lightly rotated. Moreover, one more supporting member 303x is provided
between the center stay 310b and the supporting member 303 on the left
side of the movable stopper 310, and the supporting member 303x is
connected through another coupling unit 305x to the movable stopper 310.
The coupling unit 305x makes the movable stopper 310 smoothly turn between
the free position and the blocking position.
Though not shown in FIG. 8, a plate of cast iron vertically extends inside
the piano case 170, and is reinforced by four ribs. The rein forcing ribs
project from the front surface of the plate, and also vertically extend at
intervals. The rear end portions ofthe black/white keys 103/104 are placed
between the reinforcing ribs, and gaps take place between the reinforcing
rib and the rear end portions of the black/white keys 103/104. The bracket
310a (see FIG. 3) is provided over a wider gap between the second
reinforcing rib from the right side and the rear end portion of the
black/white key 103/104, and the wire 321 downwardly passes through the
wider gap. For this reason, the wire 321 never interferes with the key
action mechanisms 106.
FIG. 9 is another change-over mechanism 400 available for the hammer
stopper 301. The change-over mechanism 400 is connected to the coupling
unit 305 on both sides of the movable stopper 310. However, description is
made on the change-over mechanism 400 linked with the coupling unit 305 on
the left side of the movable stopper 310.
The change-over mechanism 400 includes the cylindrical pin member 323, an
L-letter shaped plate member 401 turnably connected to the piano case 170
by means of a pin 402 and a wire 403 connected to the cylindrical pin
member 323 and one end of the L-letter shaped plate member 401. The wire
403 vertically extends between the L-letter shaped plate member 401 and
the cylindrical pin member 323, and transfers the angular motion of the
L-letter shaped plate member 401 to the link member 305h.
The change-over mechanism 400 further includes an L-letter shaped plate
member 403 turnably connected to the piano case 170 by means of a pin 404
and a wire 405 connected between the L-letter shaped plate members 401 and
403. The L-letter shaped plate member 403 is spaced from the L-letter
shaped plate member 401 in the longitudinal direction, and the angular
motion of the L-letter shaped plate member 403 is transferred through the
wire 405 to the L-letter shaped plate member 401.
The change-over mechanism 400 further includes a pedal 406 projecting form
the bottom sill 160, a wire 407 connected to the L-letter shaped plate
member 403 and a coupling member 408 connected between the pedal 406 and
the coupling member 408. The pedal 406 is turnable with respect to a pin
409. When a pianist presses down the pedal 406, the coupling member 408
changes the moment exerted on the pedal 406 to a force exerted on the wire
407 along the center axis thereof, and the wire 407 is pulled down. The
wire 407 exerts moment on the L-letter-shaped plate member 403, and the
L-letter shaped plate member 403 turns around the pin 404. Thus, the
angular motion of the pedal 406 is transferred to the L-letter shaped
plate member 403, and the angular motion of the L-shaped plate member 401
is transferred through the L-letter shaped plate member 401 to the link
member 305h as described hereinbefore.
Though not shown in FIG. 9, the pedal 406 is associated with the ratchet
mechanism. The ratchet mechanism maintains the pedal 406 at the depressed
position, and releases the pedal 406 therefrom.
Behavior of Keyboard Musical Instrument
When the movable stopper 310 is changed to the free position, the keyboard
musical instrument behaves as follows. The change-over mechanism 302 does
not exert any moment on the link member 305h, and the torsion coil string
305p urges the link members 305g/305h to rearwardly decline. As a result,
the parallelogram crank mechanism shunts the movable stopper 310 from the
trajectory of the hammer shanks 124.
Assuming now that a pianism depresses the white key 104 (see FIG. 1) during
playing a tune on the keyboard 101, the capstan button 116 pushes up the
whippen heel 114, and the whippen 113 turns around the whippen flange 111
in the counter clockwise direction. The jack 117 also turns around the
whippen flange 111 without relative rotation around the jack flange 115,
and causes the hammer butt 123 to turn around the butt flange 122 in the
counter clockwise direction.
The damper spoon 119 turns together with the whippen 113, and rearwardly
declines. The damper spoon 119 pushes the damper lever 138, and spaces the
damper head 140 from the set of strings 105. Thus, the set of strings
becomes ready for vibration. When the damper head 140 is spaced from the
set of strings 105, the damper | | |
