Damper adjustment device

Details Damper adjustment device Damper adjustment device

2000-04-04

2003-10-14

Lockett, Kimberly (Department: 2837)

Music

Instruments

Stringed

C084S217000, C084S218000

Reexamination Certificate

active

06632988

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a damper adjustment device for pianos, and in particular to the damper timing in grand and upright pianos.
An acoustic piano, by way of a keyboard and hammer mechanism (action), excites tensioned strings to produce tones. The strings are dampened by a second mechanism, the damper assembly. The “feel” of the piano action, that is, the real and perceived heaviness of the piano keys, depends on the damper timing—the point in the piano keystroke at which the damper is removed from the string. If the dampers are displaced from the strings early in the piano keystroke, it takes more force to depress the keys, making the keys “feel heavy”. On the other hand, if the dampers are displaced later in the keystroke, the keys feel “livelier” to the pianist. Personal preferences can dictate the exact timing desired.
Referring to
FIGS. 1 and 2
, a prior art damper assembly
100
of a typical grand piano includes cushions
1
mounted on a damper head
2
, which is typically held above a piano string
30
as shown. When cushions
1
are in contact with string
30
, cushions
1
dampen vibrations of string
30
. Cushions
1
are typically made of felt or another material which can absorb vibration, and damper head
2
is typically made of wood. Damper head
2
is supported by a rigid damper wire
3
attached at one end
3
a
to damper head
2
and at an opposite end
3
b to a top flange
5
by a locking mechanism
4
, e.g., a barrel and screw as shown in FIG.
1
. Top flange
5
is mounted to an underlever
7
to rotate relative to underlever
7
about a pin
6
. Underlever
7
is mounted to a mounting flange
8
to rotate relative to mounting flange
8
about a pin
31
. Mounting flange
8
is attached to other structural elements, described below, by a flange screw
9
.
FIG. 2
demonstrates how the prior art damper assembly of
FIG. 1
operates to displace cushions
1
from piano string
30
when a piano key
10
is depressed. As shown in
FIG. 2
, a downward force
32
is applied at a proximal end
35
of piano key
10
. Since piano key
10
rests on a fulcrum
33
, this results in upward displacement of the opposite, distal end
37
of piano key
10
(arrow
39
). Distal end
37
comes in contact with an underside
36
of underlever
7
, and subsequently rotates underlever
7
about pin
31
(arrow
41
), transmitting the upward displacement through top flange
5
, damper wire
3
and damper head
2
(arrow
43
), lifting cushions
1
off piano string
30
. This allows an undamped vibration of piano string
30
when struck by a hammer (not shown). Associated movements of other components of the piano action, causing the hammer to strike piano string
30
and produce a tone, are not shown.
An important adjustment in the regulation of piano actions is the proper spacing
14
between the underside
36
of underlevers
7
and the distal end
37
of keys
10
. This determines the distance the distal end of the key must travel before damper head
2
is displaced from string
30
, and thus the amount of downward force
32
which must be applied to proximal end
35
of the piano key
10
. In practice, the spacing is adjusted by the “feel” of a trained technician. According to the prior art, this adjustment is made by loosening locking mechanism
4
between top flange
5
and damper wire
3
, rotating the underlever about pin
31
to provide the desired spacing
14
, and then retightening locking mechanism
4
. In a typical prior art grand piano, this adjustment must be repeated for the sixty damper assemblies present in the piano. Analogous adjustments are made for upright pianos as well.
Referring to
FIG. 3
, prior art damper assembly
100
typically includes a rail assembly
41
with a damper tray
11
. Damper tray
11
, designed to contact the underside
36
of each of a number of underlevers
7
in a group of underlevers, is typically operated by a foot pedal. This allows the vibrations of all piano strings associated with the group of underlevers to remain undamped as long as the foot pedal is operated. Rail assembly
41
includes a pair of stationary blocks
12
to which damper tray
11
is coupled by pivot pins
16
received in pivot cavities
17
defined by blocks
12
for rotation relative to blocks
12
about pins
16
. Pivot blocks
12
are fixedly mounted to piano case
40
by mounting screws
19
.
When damper tray
11
is rotated, for example, by actuating a mechanism (not shown) attached to a foot pedal (not shown), a pad
34
attached to tray
11
(typically made of felt or other material capable of absorbing noise) contacts the underside
36
of underlever
7
, causing upward displacement of cushions
1
through the same mechanism as described above with respect to the piano key action. Rotation of damper tray
11
results in motion of underlever
7
, even before contact between pad
34
and the underside
36
of underlever
7
. This is true unless the axes of rotation of underlever
7
(through pin
31
) and damper tray
11
(through pins
16
) are coincident.
FIG. 4
depicts an alternate embodiment of a prior art damper assembly
100
a.
Damper assembly
100
a
includes an underlever
7
a
mounted to piano casing
40
by a rail assembly
41
a,
and a damper tray
13
a
independently mounted to the piano casing
40
. Rail assembly
41
a
is mounted to piano casing
40
in a fixed position with screws
43
a.
Damper tray
13
a
includes a pad
34
a
for contacting the underside
36
a
of underlever
7
a.
Tray
13
a
is mounted to piano case
40
with mounting flanges
42
a
and screws
44
a.
Tray
13
pivots about pins
46
a.
Upward force on damper tray
13
causes pad
34
to contact the underside of underlever
7
. Further movement of tray
13
causes upward displacement of cushions
1
in an equivalent way as described with respect to
FIG. 3
, but rotation of independent damper tray
13
does not, in and of itself, cause movement of underlever
7
until pad
34
contacts the underside of underlever
7
. That is, the rotation of underlever
7
and damper tray
13
are not coupled until pad
34
contacts the underside
36
of underlever
7
.
Referring to
FIG. 5
, a piano action of an upright piano, according to the prior art, includes a damper assembly
200
. As in a grand piano, cushions
101
dampen vibrations of piano strings
130
. Cushions
101
are mounted on a damper head
102
(typically made of wood), which is positioned adjacent to string
130
as shown. Damper head
103
is supported by a rigid damper wire, a lower end
105
of which is press-fit into an underlever
136
. Underlever
136
is rotatably connected to a flange
137
by a pin
106
. Flange
137
is mounted to a primary action rail
138
.
In operation, piano key
110
, resting on a fulcrum
133
, is subjected to a downward force
132
at proximal end
134
. This results in upward displacement (arrow
107
) of the opposite, distal end
135
of piano key
110
. Distal end
135
comes in contact with the underside of one end
141
of a wippen assembly
139
, causing the latter to pivot about a pin
131
. The opposite end
143
of wippen assembly
139
, which has a spoon
140
mounted on its upper surface
145
, is thereby rotated downward (arrow
146
) and contacts underlever
136
, producing rotation of underlever
136
about pin
106
. This causes the upper end
149
of underlever
136
(and consequently damper wire
103
, damper head
102
and cushion
101
) to move away from piano string
130
(arrow
148
), acting against the bias introduced by a wire spring
141
. This allows piano string
130
to vibrate freely when it is struck by a hammer
151
.
The spacing
114
between spoon
140
and underlever
136
is important in determining when, during the piano keystroke, cushion
101
is lifted off string
130
. The greater the spacing
114
, the later during a keystroke cushion
101
is displaced from string
130
. This significantly affects the way the keys feel to a pianist, as described above. As with grand pianos, space
114
is individually adjus

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