Title: Key actuation systems for keyboard instruments
Abstract: A key actuation system that is designed for use with a keyboard instrument of the type having multiple keys. Each key is pivotally supported and has a front end that is depressed by a player to play a note. The actuation system includes multiple actuators that are operable to move at least some of the keys. The actuators together include a block of ferromagnetic material with a surface with multiple bores defined in the surface. Each of the bores has a diameter. A winding is positioned in each of the bores. Each of the windings has a hole. A piston is provided at least partially in each of the holes, with each piston being in mechanical communication with one of the keys such that movement of the piston causes movement of the key. Each piston has a width. A ferromagnetic flux plate with multiple openings is positioned on the surface of the block of ferromagnetic material with the openings aligned with the bores. The openings each have a width that is less than the diameter of the bores, such that the flux plate partially closes off the upper end of each bore. When the windings are energized, the corresponding piston moves, thereby moving one of the keys.
Patent Number: 7,019,201 Issued on 03/28/2006 to Meisel
| Inventors:
|
Meisel; David (7271 Kingswood Dr., Bloomfield Township, MI 48301)
|
| Appl. No.:
|
106301 |
| Filed:
|
April 14, 2005 |
| Current U.S. Class: |
84/16 |
| Current Intern'l Class: |
G10F 1/02 (20060101) |
| Field of Search: |
84/16-20,29
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Donels; Jeffrey W
Attorney, Agent or Firm: Gifford, Krass, Groh, Sprinkle, Anderson & Citkowski, P.C.
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
This is a continuation of U.S. patent application Ser. No. 10/932,762, filed
Sep. 2, 2004 U.S. Pat. No. 6,891,092, which is a continuation of U.S. patent application
Ser. No. 10/155,629, filed May 24, 2002 U.S. Pat. No. 6,888,052, which is a continuation-in-part
of U.S. patent application Ser. No. 09/772,736, filed Jan. 30, 2001, now U.S. Pat.
No. 6,781,046, which is a continuation-in-pan of U.S. patent application Ser. No.
09/387,395, filed Sep. 2, 1999, now U.S. Pat. No. 6,194,643.
U.S. patent application Ser. No. 10/155,629 claims priority from U.S. provisional
patent application Ser. Nos. 60/373,189, filed Apr. 17, 2002; 60/297,829, filed
Jun. 13, 2001; and 60/295,485, filed Jun. 1, 2001.
U.S. patent application Ser. No. 09/772,736 claims priority from U.S. provisional
patent application Ser. Nos. 60/179,319, filed Jan. 31, 2000; 60/205,723, filed
May 19, 2000; and 60/246,228, filed Nov. 6, 2000.
U.S. patent application Ser. No. 09/387,395 claims priority from U.S. provisional
patent application Ser. Nos. 60/099,081, filed Sep. 4, 1998; 60/104,920, filed
Oct. 20, 1998; 60/109,169, filed Nov. 20, 1998; 60/116,746, filed Jan. 22, 1999;
60/136,188, filed May 27, 1999; and 60/144,969, filed Jul. 21, 1999. The entire
content of each application and patent being incorporated herein by reference in
their entirety.
Claims
I claim:
1. A keyboard instrument comprising:
a key bed;
a key frame disposed on the key bed, the key frame pivotally supporting a plurality
of keys, each key having a front end that is depressed by a player to play a note; and
a key frame hold-down for holding the key frame in contact with the key bed,
the hold-down including a magnet and a target that is magnetically attracted to
the magnet.
2. The keyboard instrument according to claim 1, wherein the magnet is disposed
in the key bed and the target is disposed in the key frame.
3. The keyboard instrument according to claim 1, wherein the target is steel.
4. The keyboard instrument according to claim 1, wherein the magnet has a diameter
greater than a diameter of the target.
5. The keyboard instrument according to claim 1, further comprising:
a plurality of actuators operable to move at least some of the plurality of keys,
each actuator including:
a winding surrounding a hole; and
a piston at least partially disposed in the hole, the piston being in mechanical
communication with one of the keys such that movement of the piston causes movement
of the key;
wherein energizing one of the windings causes the corresponding piston to move
relative to the winding, thereby moving one of the keys.
6. A method for determining the position of an actuator piston relative to a
winding in an actuation system of a keyboard instrument, the method comprising:
providing a keyboard instrument having a plurality of keys, each key being pivotally
supported and having a front end that is depressed by a player to play a note;
providing a keyboard actuation system comprising a plurality of actuators operable
to move at least some of the plurality of keys, each actuator including:
a winding surrounding a hole; and
a piston at least partially disposed in the hole, the piston having a position
relative to the winding; the piston being in mechanical communication with one
of the keys such that movement of the piston causes movement of the key;
wherein energizing one of the windings causes the corresponding piston to move
relative to the winding, thereby moving one of the keys;
correlating the piston position with the current rise time in the winding;
applying power to the winding;
monitoring current rise time in the winding when power is applied to the winding; and
determining the position of the piston based on the correlation between the current
rise time and the piston position.
7. The method according to claim 6, further comprising:
correlating the temperature of the winding with the piston position and the current
rise time; and
determining the temperature of the winding;
wherein the position determining step comprises determining the position of the
piston based on the correlation between the current rise time, temperature and
piston position.
8. The method according to claim 7, wherein the temperature determining step
comprises measuring the temperature.
9. The method according to claim 7, wherein the temperature determining step
comprises modeling the temperature.
10. The method according to claim 6, wherein correlating the piston position
with the current rise time step comprises correlating the piston position with
the shape of the current versus time curve.
11. A method for determining the position of an actuator piston relative to a
winding in an actuation system of a keyboard instrument, the method comprising:
providing a keyboard instrument having a plurality of movable components, component
being movable by the action of a player;
providing an actuation system comprising a plurality of actuators operable to
move at least some of the plurality of components, each actuator including:
a winding surrounding a hole; and
a piston at least partially disposed in the hole, the piston having a position
relative to the winding; the piston being in mechanical communication with one
of the components such that movement of the piston causes movement of the component;
wherein energizing one of the windings causes the corresponding piston to move
relative to the winding, thereby moving one of the components;
correlating the piston position with the current rise time in the winding;
applying power to the winding;
monitoring current rise time in the winding when power is applied to the winding; and
determining the position of the piston based on the correlation between the current
rise time and the piston position.
12. The method according to claim 11, further comprising:
correlating the temperature of the winding with the piston position and the current
rise time; and
determining the temperature of the winding;
wherein the position determining step comprises determining the position of the
piston base on the correlation between the current rise time, temperature and piston position.
13. The method according to claim 12, wherein the temperature determining step
comprises measuring the temperature.
14. The method according to claim 12, wherein the temperature determining step
comprises modeling the temperature.
15. The method according to claim 11, wherein correlating the piston position
with the current rise time step comprises correlating the piston position with
the shape of the current versus time curve.
Description
FIELD OF THE INVENTION
The present invention relates generally to devices for the actuation of keys
for acoustic and electronic keyboards.
BACKGROUND OF THE INVENTION
The piano is a stringed keyboard musical instrument which was derived from the
harpsichord and the clavichord. Its primary differences from its predecessors is
the hammer and lever action which allows the player to modify the intensity of
the sound emanating from the piano depending upon the force employed by the person
playing the piano.
The modern piano has six major parts: (1) the frame, which is usually made of
iron; (2) the sound board, a thin piece of fine grain spruce which is placed under
the strings; (3) the strings made of steel wire which increase in length and thickness
from the treble to the bass; (4) the action, which is the mechanism required for
propelling the hammers against the string; (5) the pedals, one of which actuates
a damper allowing the strings to continue to vibrate even after the keys are released,
another known as a soft pedal which either throws all the hammers nearer to the
strings so that the striking distance is diminished or shifts the hammers a little
to one side so that only a single string instead of two or three strings is struck,
and, in some pianos, a third or sustaining pedal that keeps raised only those dampers
already raised by the keys at the moment the pedal is applied; and finally (6)
the case. The piano's action functions primarily as follows: a key is pressed down,
its tail pivots upward, lifting a lever that throws a hammer against the strings
for that key=s note. At the same time a damper is raised from the strings, allowing
them to vibrate more freely. When the key is even partially released, the damper
falls back onto the strings and silences the note. When the key is fully released,
all parts of the mechanism return to their original positions.
The player piano is an evolution of the standard piano which includes a system
for automatically actuating the piano keys. There are numerous types of apparatuses
available for actuating the piano keys.
Credit for the mechanically operated (or player) piano is generally given
to Claude Felix Seytre of Leon, France. His patent was issued in 1842 for a playing
piano system that used stiff cardboard sheets. An Englishman named Alex Bain improved
the patent in 1848 with a roll operated piano. In 1863 the first pneumatically
operated piano was patented and achieved commercial success.
Originally, player pianos operated by means of suction which was created
by pumping bellows at the bottom of the piano. This in turn caused the keys to
go down, the music roll to turn and other various accessories to operate, such
as the sustain pedal and hammer rail. When suction is applied to a pneumatic actuator,
it collapses and performs a mechanical function such as playing a note, lifting
the dampers, or pushing on the hammer rails. To perform an action each pneumatic
actuator must have a valve associated with it for turning each actuator on and
off. Pneumatically operated player pianos tended to be extremely complicated machines.
More recently, to overcome the problems associated with using paper rolls and
pneumatic controls, electronically operated player pianos have been developed.
In these, CD-ROMs, cassette tapes and other electronic storage means replace the
paper rolls and electromagnetic actuators such as solenoids control key movement.
These electromagnetic actuators generally offer greater control over the movement
of the keys, which allows for finer control of the sounds emanating from the player piano.
The size of the player piano mechanisms has also been greatly reduced with the
use of electromagnetic actuators. In many cases, electromagnetic actuators were
substituted directly for the corresponding pneumatic actuators and were placed
beneath the rear of the keys to push the keys up. These push type solenoids were
first used in the early 1960s and continue to be used today. Locating the actuators
under the rear of the key makes installation problematic. Installation requires
cutting a slot along the entire lower side of the piano case, thus permanently
disfiguring the piano. Another disadvantage is that the solenoids are mounted separately
from the key frame and therefore cannot be removed and serviced with the key frame.
One potential improvement was offered in U.S. Pat. No. 4,383,464 to Brennan which
issued in 1983. It discloses an electromagnetic device for actuating piano keys.
In this invention, electromagnets were located above the key and behind the fulcrum
of the key and operated to pull a piece of magnetic material in the rear of the
key upwardly. The electromagnets were positioned forward of the structure that
holds the hammer mechanism, known as the tower. Also, the electromagnets did not
engage the key itself. Rather, they relied on a magnetic field. The patent was
never successful in commercial application. The location of the electromagnetic
device was problematic in that there is little room between the rear of the key
pivot or fulcrum and in front of the tower. The electromagnetic devices used in
the >464 patent had additional problems in that they charged much slower and
thereby consumed excess power and were slow to start up. They generated additional
heat and consumed far more power than a solenoid or servomechanism. Additionally,
the location of the electromagnetic devices in the >464 patent would be extremely
sensitive to any maintenance work which is performed upon the action due to the
fact that if the action is removed and worked upon, the alignment of the electromagnetic
devices would require adjustment after the action was reinstalled.
Many other approaches to the actuation of the keys of the piano have been attempted,
but all suffer from various shortcomings. It is desirable that an actuation system
provide a combination of playing power, key control, and quiet operation. It is
also desirable that an actuation system be easily installed into an existing piano
without requiring extensive modification to the piano. Presently available systems
generally fail to meet this combination of requirements. Therefore, there remains
a need for improved player systems.
In many player pianos, it is desirable to sense the movement of the piano keys.
This allows the player piano to "record" the playing of a user. Key movement sensing
may also be beneficial in the control of playback by allowing the player piano
to use some type of a feedback control loop.
Currently, player pianos include some type of actuator mechanism that
moves individual piano keys, thereby "playing" the piano. Where key movement sensing
is desired, an entirely separate system of key movement sensors is added. Currently
available key movement sensing systems have several drawbacks. First, they typically
require the addition of a piece of metal to each key which may affect the weight
of the key and alter the playing characteristics of the piano. Secondly, because
the sensing system is entirely separate from the actuation mechanism, additional
wiring and installation is required. This also adversely affects the cost of such
a system. Therefore, there remains a need for improved key sensing systems.
Non-acoustical keyboard instruments, such as electronic keyboards,
typically include a plurality of keys with some type of sensor located so as to
sense movement of each key. When a sensor determines that a key has been moved,
a sound is electronically created by the instrument. This differs from a piano
wherein sound is created by a mechanical system. A drawback to non-acoustical keyboard
instruments is that most lack the "feel" associated with traditional acoustic keyboard
instruments. That is, there is a certain feel associated with operating the keys
on a traditional acoustic keyboard instrument, such as a piano. This feel results
from the mechanical design of the string striking mechanism, the weight of the
keys, and other factors. Non-acoustical keyboards lack the mechanical structure
of a piano and usually have keys which are significantly less massive. Consequently,
the keys feel entirely different when operated. Some musicians consider this a
drawback as they would prefer that non-acoustical keyboards have a feel similar
to acoustical keyboards such as a piano.
Another drawback to non-acoustical keyboard instruments is that it is typically
prohibitively expensive to provide a "player" version. Purchasers and owners of
non-acoustical keyboard instruments sometimes desire, as do owners of pianos, that
the keyboard instrument be able to play itself. Systems used to turn pianos into
player pianos may be adapted for use with some non-acoustical keyboard instruments,
but the cost and complexity is often high. For example, the player system may cost
as much or more than the non-acoustical keyboard instrument, thereby doubling its
purchase cost. Player systems typically provide both for operation of the keys
and for sensing of key movement so that the playing of a musician may be "recorded."
One or both of these features is often desired by purchasers of non-acoustical
instruments. In light of the above limitations of non-acoustical keyboard instruments,
there is a need for improving the feel of these keyboards as well as for player
systems designed for use with non-acoustical keyboard instruments.
SUMMARY OF THE INVENTION
There is disclosed herein a plurality of solutions to the shortcomings of the
prior art. For example, according to one aspect of the present invention, a key
actuation system is provided for a keyboard instrument. The keyboard instrument
is of the type having a plurality of keys with each key having an upper surface
and a lower surface and being pivotally supported above a key bed. Each key has
a front end that can be depressed by a player to play a note. The key bed extends
under and is spaced from the lower surface of the key. The actuation system includes
an underlever positioned in the space between the lower surface of the key and
the key bed, and between the front end of the key and the pivotal support. The
underlever has a first end that is supported in the stationary position relative
to the key bed and the second end that is movable towards and away from the key
bed. The second end of the underlever is in mechanical communication with the key
such that movement of the second end of the underlever towards the key bed causes
the key to move as if it is depressed by a player. An actuator is in mechanical
communication with the underlever and is operable to move the second end of the
underlever towards the key bed. Numerous other embodiments of the present invention
are also disclosed and described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the present invention will be had upon reference to
the
following detailed description when read in conjunction with the accompanying drawings
in which:
FIG. 1 is a perspective view of a single key for a keyboard instrument with
portions cutaway to show integral actuators disposed therein;
FIG. 2 is a top view of the key of FIG. 1;
FIG. 3 is a cross-sectional side view of the key of FIG. 1 taken along lines 3-3;
FIG. 4 is a bottom view of the key of FIG. 1 showing one approach to wiring
the actuators;
FIG. 5 is a detailed view of a portion of a balance rail for use with the embodiment
of FIG. 1 with a portion of a key superimposed thereon in phantom lines;
FIG. 6 is a cross-sectional side view of the balance rail of FIG. 5 taken along
lines 6—6;
FIG. 7 is a perspective view of a key similar to FIG. 1 showing an alternative
approach to providing power to the actuators;
FIG. 8 is a perspective view of a single key from the keyboard instrument with
an actuator system disposed partially in the key and partially in the key frame;
FIG. 9 is a cross-sectional side view of the key of FIG. 8 taken along lines 9—9;
FIG. 10 is a cross-sectional side view of a key similar to FIG. 8 with a single
coil actuator disposed in the key;
FIG. 11 is a cross-sectional side view of a key similar to FIG. 10 with a second
coil added;
FIG. 12 is a perspective view of a typical grand piano;
FIG. 13 is a side elevational view of a single key and key action from a typical
grand piano with an actuator disposed in the wippen flange rail and an optional
secondary actuator disposed in the front of the key bed;
FIG. 14 is a cross-sectional view of a key and actuator for use with the embodiment
of FIG. 13, showing an alternative engagement between the key and piston;
FIG. 15 is a cross-sectional view of a key and actuator similar to FIG. 13 showing
an alternative engagement between the piston and the key;
FIG. 16 is a perspective view of two keys from a typical grand piano along with
their corresponding key actions and back or damper actions, showing pull solenoids
installed in the back actions and designed to lift the rear portion of the keys;
FIG. 17 is a perspective view similar to FIG. 16 showing an alternative arrangement
of a pull type solenoid mounted in the back action of the piano;
FIG. 18 is a cross-sectional view of a key, the wippen flange rail, and the
actuator illustrating the interconnection between the piston and the key;
FIG. 19 is a side elevational view of a key, key action, and back action from
a typical grand piano with an actuator disposed above the area where the key and
the damper underlever overlap;
FIG. 20 is a perspective view of a pair of keys from a typical grand piano along
with their corresponding key actions, showing an actuator system installed to the
rear of the keys and lifting the keys via actuator underlevers;
FIG. 21 is a side elevational view of a single key and key action from a typical
grand piano with an actuator system installed to the rear of the key and lifting
the key using an actuator underlever;
FIG. 22 is a side elevational view similar to FIG. 21 showing an alternative
actuator using an actuator underlever;
FIG. 23 is a detailed view of an actuator system for installation to the rear
of a key that uses an actuator underlever to lift the rear of the key;
FIG. 24 is a detailed view of a system similar to FIG. 23 with the actuator
moved rearwardly;
FIG. 25 is a side elevational view of the rear of a key and an actuator system
using a flexible actuator underlever to lift the rear of a key;
FIG. 26 is a side elevational view of a single key and key action from a typical
grand piano with an actuator system installed to the rear of the key and lifting
the rear of the key via a lever which is pivotally attached to the key frame forward
of the rear end of the key;
FIG. 27 is a cross-sectional side elevational view of a typical upright piano
with a standard tall key action showing two variations on actuators mounted above
the rear portion of the key;
FIG. 28 is a cross-sectional detailed view of a portion of the piano shown in
FIG. 27, illustrating an alternative embodiment of an actuator for lifting the
rear of the key;
FIG. 29 is a view similar to FIG. 28 showing yet another alternative embodiment
of an actuator for lifting the rear of the key;
FIG. 30 is a cross-sectional view of a key and a piston and coil of an actuator
showing one approach to interconnecting the piston with the key;
FIG. 31 is a cross-sectional view of a key and a piston and coil of an actuator
showing another approach to interconnecting the piston with the key;
FIG. 32 is a cross-sectional view of a key and a piston and coil of an actuator
showing yet another approach to interconnecting the piston with the key;
FIG. 33 is a cross-sectional side elevational view of a portion of a key, key
action and damper action from a standard upright piano having a shortened key action,
showing an actuator installed above the key and having a piston lifting the key
from below;
FIG. 34 is a view similar to FIG. 33 showing an alternative actuator for lifting
the rear of the key;
FIG. 35 is a cross-sectional side elevational view of a typical drop action
piano showing four alternative approaches to using actuators to move the key or
key action;
FIG. 36 is a perspective view of a single key action for a typical grand piano
and a portion of a damper action showing actuators used to directly actuate a wippen
and the damper rod;
FIG. 37 is a cross-sectional side elevational view of a key and damper action
from a typical upright piano with shortened key action showing an actuator disposed
so as to directly actuate the wippen;
FIG. 38 is a perspective view of a single key and a portion of the key frame
for a keyboard instrument showing an actuator and interconnection mechanism for
moving the key;
FIG. 39 is a cross-sectional view of the key and key frame of FIG. 38 taken
along lines 39—39;
FIG. 40 is a cross-sectional side elevational view of a key similar to FIG.
39 but with an alternative actuator and mechanism for moving the key;
FIG. 41 is an elevational side view of a single key showing a dual coil actuator
interconnected therewith;
FIG. 42 is a detailed view of the piston for the actuator of FIG. 41;
FIG. 43 is a cross-sectional view of a key along with a piston and coil of an
actuator, showing a piece of magnetic material disposed atop the key;
FIG. 44 is a cross-sectional view of a key along with a piston and coil of an
actuator showing a piece of magnetic material disposed atop the key;
FIG. 45 is a cross-sectional view of a key along with a coil and piston of a
typical push-type solenoid showing a piece of magnetic material disposed on the
bottom of the key;
FIG. 46 is a cross-sectional view of a key along with a piston and coil of an
actuator showing a piece of magnetic material disposed in a hole in the key;
FIG. 47 is a cross-sectional view of an actuator coil and piston with an optical
sensor integral therewith;
FIG. 48 is a cross-sectional view of the piston of FIG. 47 taken along lines 48—48;
FIG. 49 is a cross-sectional view of a single key resting on a key frame showing
two embodiments of sensing systems utilizing magnetic materials disposed in a key
with coils surrounding pins which extend upwardly through the key from the key bed;
FIG. 50 is a top view of the key of FIG. 49;
FIG. 51 is a side elevational view of a hammer rail and hammer along with an
actuator designed to directly actuate the hammer;
FIG. 52 is a side elevational view of a hammer and hammer rail similar to FIG.
51 showing an alternative actuator for directly actuating the hammer;
FIG. 53 is a perspective view of a damper lift lever and an actuator system therefore;
FIG. 54 is a perspective view of a grand piano with a thin film speaker disposed
in the lid thereof;
FIG. 55 is a bottom view of a piano case showing a transmission line subwoofer
installed thereon;
FIG. 56 is a cross-sectional elevational view of a portion of a key along with
an actuator therefore;
FIG. 57 is a side elevational view of a single key in key action along with
an actuator system therefore;
FIG. 58 is a side view of a portion of a key in key action along with another
embodiment of an actuator according to the present invention;
FIG. 59 is a side elevational view of a rear portion of a key along with yet
another embodiment of an actuation system therefore;
FIG. 60 is a side elevational view of a portion of a key along with a rocking
actuator system according to the present invention;
FIG. 61 is a top view of the key and actuator of FIG. 60;
FIG. 62 is a detailed view of a portion of a key along with a key hold down
clip according to the present invention;
FIG. 63 is a partially cutaway side elevational view of a key from an electronic
keyboard with a counterweight system, along with an embodiment of an actuation
system according to the present invention;
FIG. 64 is a side elevational view of a key and counterweight similar to FIG.
63 with an alternative embodiment of an actuator system therefore;
FIG. 65 is a side elevational view of another design of an electronic keyboard
key along with a counterweight system and an actuator for moving the counterweight;
FIG. 66 is a side elevational view of a key and counterweight similar to FIG.
65 along with an alternative actuator therefore;
FIG. 67 is a side elevational view of a key and counterweight similar to FIG.
65 along with another alternative actuator therefore;
FIG. 68 is a side elevational view of a key and counterweight similar to FIG.
65 along with yet another embodiment of an actuator therefore;
FIG. 69 is a partial view of a key bed and key frame showing the end interconnection
system according to the present invention;
FIG. 70 is a perspective view of a portion of a system for producing sound from
a sound board;
FIG. 71 is a sketch of a force and vibration creation system for transmitting
vibrations into a sound board;
FIG. 72 is a top plan view of a sound board of a grand piano-style instrument
with vibration sources similar to FIG. 71;
FIG. 73 is a perspective view of an electric violin according to the present invention;
FIG. 74 is a perspective view of a portion of a bow for use with the electric
violin of FIG. 73;
FIG. 75 is a detailed view of one embodiment of a sensor for use with the electric
violin of FIG. 73;
FIG. 76 is a cross-sectional side elevational view of a key in key action, illustrating
an additional embodiment of a key actuation system according to the present invention;
FIG. 77 is a cross-sectional side elevational view of an upright piano, showing
a key in key action and another embodiment of a key actuation system according
to the present invention;
FIG. 78 is a view similar to FIG. 77, showing an alternative actuation system
according to the present invention;
FIG. 79 is a view similar to FIGS. 77 and 78, showing yet another alternative
embodiment of an actuation system according to the present invention;
FIG. 80 is a top plan view of an embodiment of a plurality of actuators housed
in a ferromagnetic block;
FIG. 81 is a perspective view of the plurality of actuators and block of FIG. 80;
FIG. 82 is a schematic view showing one approach to wiring an actuator to a
control circuit and power supply;
FIG. 83 is a schematic view showing an improved wiring system according to the
present invention;
FIG. 84 is a side elevational view, partially in cross-section, of an embodiment
of an actuator disposed in a ferromagnetic block, using a flux plate and a driver
circuit board disposed atop the block;
FIG. 85 is a partially exploded view of a plurality of actuators, wherein each
winding is disposed in a board of ferromagnetic block;
FIG. 86 is a current rise time graph; and
FIG. 87 is another current rise time graph.
DETAILED DESCRIPTION OF THE INVENTION
A common goal in the design of player systems for both acoustic and non-acoustic
keyboard instruments is to move the keys of the instrument. This may actually "play"
the instrument or, in some electronic keyboards, may merely mimic the movement
of the keys that would be associated with the sound being internally produced by
other means. In accordance with the first aspect of the present invention, a system
for moving the keys of either an acoustic or a non-acoustic instrument will be described.
Referring now to FIGS. 1-3, a twin coil actuator system according to the
present invention is shown. The system is installed in a key
10 which has
a front end or playing end
12 and a rear end
14. The key
10
is supported midway along its length by a balance rail or fulcrum
16. A
front rail
18 is positioned under the front end
12 of the key. Normally,
a guide pin would extend upwardly from the front rail
18 into a hole in
the underside of the front end
12 of the key for guiding the key during
movement. When a keyboard instrument is played, a player presses downwardly on
the front end
12 of the key
10 causing the rear end
14 to
pivot upwardly. In an acoustic keyboard instrument, such as a piano, the upward
movement of the rear end
14 of the key
10 sets a mechanism in motion
which mechanically produces a sound. In a piano, this occurs when a hammer is flicked
upwardly such that it hits a string, producing a note. In a non-acoustic instrument,
movement of the key
10 triggers a sensor which causes the instrument to
electronically produce a sound. The actuation system will now be described. A first
coil
20 is embedded in the front end
12 of the key
10. A generally
rectangular hole or recess
22 is defined in the center of the coil. This
recess
22 extends upwardly from the underside of the key
10 part
way to the top of the key
10. A stationary ferromagnetic guide pin
24
is mounted to the front rail
18 of the key frame
26 and is aligned
so as to extend partially into the recess
22 in the first coil
20.
When electrical power is applied to the first coil
20, the front end
12
of the key
10 is drawn downwardly so that the coil
20 can surround
the guide pin
24. As shown, the recess or hole
22 and the guide pin
24 are generally rectangular. Likewise, a second coil
28 is embedded
in the rear end
14 of the key
10 with a rectangular recess
30
in the top side of the key
10 A second stationary ferromagnetic guide pin
32 extends downwardly from a support member
34 and is aligned so
as to extend into the recess
30. Once again, by energizing the second coil
28, the rear end
14 of the key
10 is lifted upwardly so that
the guide pin
32 extends into the recess
30 in the coil
28.
It should be noted that while the use of both the first coil
20 and the
second coil
28 is preferred for some applications, the use of only a single
coil is sufficient for other applications.
In FIG. 1, electrical leads
36 are shown extending from the coils
20
and
28. Obviously, it is preferable to configure the wiring such that it
does not interfere with the movement of the key
10. One approach to providing
a more convenient wiring system is shown in FIGS. 4-6. As shown in FIG. 4, the
bottom side of the key
10 may have wiring traces
38 defined thereon.
A pair of electrical contacts
40 are provided adjacent the pivot hole
42
in the key
10. As shown in FIG. 4, a key
10 normally rests on a balance
rail
16 with a fulcrum pin
44 extending upwardly therefrom. The hole
42 is generally elongated so that the fulcrum pin
44 can rock forwardly
and backwardly in the hole
42. As shown in FIGS. 1 and 3, a bushing
46
is normally provided atop the balance rail
16 with the bushing
46
surrounding the fulcrum pin
44. As shown in FIGS. 5 and 6, this bushing
46 may include positive and negative electrical contacts
48 aligned
so as to make contact with the contacts
40 on the underside of the key
10
when the key
10 is placed in its normal position on the bushing
46.
Wiring traces
50 may run along the top of the balance rail
16 to
power supplies. The wiring traces
50 provide a convenient method for providing
power to the bushing
46 and from the contacts
40 to the coils
20
and
28. The key wiring traces
38 may be deposited directly on the
underside of the key
10, thus avoiding the labor intensive process of running
individual wires.
The embodiment disclosed in FIGS. 1-6 provides a simple way to provide automatic
actuation of the keys. New keys with wiring traces and coils may be substituted
for existing keys. A new front rail
18 with the guide pins
24 may
be substituted for the existing one and a new support member
34 with guide
pins
32 may also be substituted for the existing one. Then, the wiring traces
on the balance rail
16 are connected to a power supply. Obviously, it is
necessary to individually control the various keys
14. Therefore, individual
control circuits may also be provided in close proximity to the keys. The system
of FIGS. 1-6 also provides several other advantages over the prior art. First,
by placing the coils in the keys, heating concerns are reduced. If an arrangement
were such that the guide pins were part of the keys and the coils were embedded
in the front rail and support member, multiple coils would be located side by side
in the rail and support member. This may create concentrated heat loads as the
coils are energized, which may in turn cause changes in the dimensions of the front
rail and support member. Also, the guide pins
24 and
32 weigh substantially
more than their corresponding coils
20 and
28. Keys, on the other
hand, have spaces between them so expansion of individual keys by a small amount
should not affect their action. Also, more air is able to circulate around the
key than would be able to circulate about the front rail or support member, thereby
increasing cooling of the coils. Therefore, positioning the coils in the keys has
less of an effect on the weight of the keys than would mounting the guide pins
thereto. This in turn reduces any affects on the "feel" of the keys. It should
also be noted that the illustrated shape of the guide pins
24 and
32
are preferred but not required. The rectangular cross-section of the pins and the
corresponding coils allows for heavy magnetic saturation. The rectangular shape
also allows the guide pins to be of substantial size, thereby increasing the magnetic
saturation. The guide pins also serve to replace the function of a normal small
oval guide pin that would be located at the front
12 of the key
10.
Therefore, the guide pins, especially the front guide pin
24, acts to stabilize
the key during its motion in the same way that a traditional guide pin would.
FIG. 7 illustrates an alternate approach to energizing a twin coil actuator
system, such as was shown and discussed with respect to FIGS. 1-6. In the embodiment
of FIGS. 1-6, power was provided to the twin coils
20 and
28 via
contacts provided between the underside of the key
10 and the balance rail
16 on the key frame
26. In the embodiment of FIG. 7, a primary coil
52 is provided in the balance rail
16. A secondary coil
54
is disposed inside the key
10 and is wired to the twin coils
20 and
28. In use, the primary coil
52 is pulse energized which inductively
charges the secondary coil
54. The secondary coil
54 converts this
energy to a voltage and current to drive the twin coils
20 and
28.
This system provides the advantage that no electrical contact is required between
the key
10 and the balance rail
16.
In some non-acoustical keyboard instruments, full size keys, such as key
10
in FIG. 1, are not used. Instead, half size keys, such as shown in FIGS. 8-11,
are used. Referring to FIG. 8, a half size key
60 has a front or playing
end
62, which a player depresses in order to play a note. Instead of having
a rear end and a mid portion that is supported by a fulcrum, the other end of the
half size key
60 is a pivot end
64. This pivot end
64 is supported
by pivotal support
66 which extends upwardly from the key frame
68.
The front end
62 of the half size key
60 is typically thickened with
the remainder of the key being thinned out, as shown, to save weight and cost.
A guide pin
70 extends upwardly from the front of the key frame
68
into a recess
72 in the under side of the front end
62 of the half
size key
60. A plurality of these half size keys
60 are used to assemble
a complete keyboard instrument. As discussed previously, purchasers of these instruments
also often desire player systems that move the keys
60. FIGS. 8-11 illustrate
systems for accomplishing this goal.
In the embodiment of FIGS. 8 and 9, a solenoid coil
74 is embedded in
the
thickened front end
62 of the key
60 surrounding the recess
72.
As discussed earlier, a guide pin
70 extends upwardly from the key frame
68 into the recess
72 and acts to guide the key
60 as it moves
downwardly. In this embodiment, the pin
70 is made at least partially of
a magnetic material. As will be clear to those of skill in the art of electromechanics,
energizing the coil
74 causes it to act as an electromagnet. Therefore,
when the coil
74 is energized, magnetic force will be created between the
pin
70 and the key
60. This may be used to pull the key
60
downwardly thereby playing a note. The coil
74 may also be used in other
ways, as will be described with respect to other aspects of the present invention.
FIGS. 8 and 9 also show a second coil
76 embedded in the key frame
68
so as to surround the base of the pin
70. The second coil
76 may
be used to assist the first coil
74 or may be used in other ways, as will
be described with respect to other aspects of the present invention.
FIG. 10 shows a view of a key similar to FIGS. 8 and 9 but with only a single
coil embedded in the key. FIG. 11 is similar to FIG. 10 but adds a second coil.
As discussed above, grand pianos are those pianos in which the strings are arranged
horizontally. A typical grand piano is shown in FIG. 12. FIGS. 13 and 16 show two
views of a typical key action, which controls striking of the strings, and a back
action, which controls damping of the strings, for a grand piano. FIGS. 13 and
16 also show key actuation systems, the workings of which will be later described.
FIG. 13 shows an elevational side view of a single key and key action while FIG.
16 shows a perspective view of two keys in their associated key actions and back
actions. Reference will be made commonly to both of these drawings during the following
discussion of the internal workings of a grand piano. The key action includes an
elongated key
80 which is pivotally supported near its center by a balance
rail
82 where the key
80 has a pivot or fulcrum hole
84 surrounding
a fulcrum pin
86 that extends upwardly from the balance rail
82.
The fulcrum hole
84 is elongated so as to allow the key
80 to tip
front to back on the balance rail
82. Key
80 has a front or playing
end
88 and a back or action end
90. Key
80 and balance rail
82 are in turn supported by a generally horizontal key frame
92 as
shown in FIG. 13. When the piano is played in its normal mode, an operator pushes
down on the playing end
88 of the key
80 causing the key
80
to pivot or tip on the balance rail
82 so that the action end
90
of the key
80 moves upwardly. The key action portion of the piano also includes
a wippen flange rail
94 which extends side to side in the piano a short
distance above the action end
90 of all of the keys
80. The wippen
flange rail
94 is a structural piece designed to support portions of the
key action. The wippen flange rail
94 may be made out of metal or out of
wood. The wippen flange rail
94 remains stationary as the key
80
and key action are manipulated. A wippen
96, also called a grand lever,
is pivotally attached to the wippen flange rail
94 and extends generally
horizontally over the action end
90 of the key
80 toward the fulcrum
pin
86. When a user plays the piano, depressing the front end
88
and causing the action end
90 of the key
80 to move upwardly, the
key
80 pushes on the wippen
96 causing it to pivot upwardly. The
wippen
96 in turn pushes on a repetition lever
98 which in turn flicks
a hammer
100 upwardly so that it impacts a horizontally positioned string
102. The hammer
100 includes a head
104 and a shaft
106
which is pivotally supported by a hammer rail
108. The hammer rail
108,
like the wippen flange rail
94, is a stationary structural piece designed
to support a portion of the key action. The hammer rail
108 may be made
out of metal or out of wood.
Because of the configuration of the key action, the hammer
100 is
flicked upwardly very rapidly enabling the piano to create loud sounds. The details
of the key action vary from piano to piano but generally include the components
as discussed above.
Also shown in FIG. 16 is the back action portion of a grand piano. The back
action, also called a damper action, includes a damper underlever
110 which
is pivotally supported by a damper rail
112 positioned at the back of the
piano case. The damper underlever
110 extends forwardly from the damper
rail
112 so that its other end is positioned above the very rear portion
of the action end
90 of the key
80. Therefore, as the key
80
is pivoted, the action end
90 of the key
80 lifts upwardly on the
damper underlever
110. A damper rod
114 extends upwardly from the
damper underlever
110 to a damper
116 which in its normal position
rests atop the string
102. When the key
80 is struck, the damper
116 is lifted off of the string
102 by the movement of the damper
underlever
110, thereby allowing the string
102 to resonate. As the
key
80 is released, the damper
116 falls back into contact with the
string
102, thereby dampening the vibration of the string
102.
Referring now to FIG. 13, an embodiment of an actuator for a player piano
key action is shown. In this embodiment, a solenoid body or coil
120 is
embedded in the wippen flange rail
94 and a corresponding solenoid core
or piston
122 extends downwardly from the coil and engages the action end
90 of the key
80. When the solenoid coil
120 is energized,
the core or piston
122 is drawn upwardly into the coil thereby actuating
the key action and producing a sound.
It should be noted that the word "solenoid" is used throughout this application
to refer to an electromechanical actuator. The term is to be interpreted broadly
to refer to any type of electromechanical actuator including solenoids, servos,
and other devices wherein application of electrical power causes pieces of the
device to move relative to one another. The two pieces are referred to herein as
a coil and a piston or core. These terms should also be interpreted broadly. Also,
more sophisticated electromechanical devices such as dual coil solenoids may be
used wherein each of the two moving pieces may be energized thereby increasing
the mechanical output of the device.
FIG. 18 shows a cross section of the key
80 and wippen flange rail
94
in the actuator to better illustrate the interconnection between the piston
122
and the action end
90 of the key
80. Referring to both FIGS. 18 and
13, this inner connection will now be described. The piston
122 extends
through a hole
124 in the key
80 and extends out the bottom of the
key and terminates. A washer
126 and a spring
128 is positioned between
the bottom of the key and the key frame. When the coil
120 is energized,
the piston
122 is pulled upwardly thereby pulling the key
80 upwardly
with it. The washer
126 and spring
128 serve to take up play and
prevent noise. The washer
126 may be made of any of a number of materials
to optimize this reduction in noise.
Referring now to FIG. 14, an alternate approach to interconnecting the
piston with the key is shown. In this alternative, a piston
130 is embedded
directly into the key
80, extending upwardly therefrom into the coil
120.
The embodiment of FIG. 13 has the advantage that movement of the key does not necessarily
move the piston
122. Therefore, that embodiment minimizes any re-weighting
of the key or alteration to the "feel" of the key. The alternative of FIG. 14,
on the other hand, slightly weights the key by making the piston
130 a portion
thereof. However, for some applications, as will be discussed later, it is desirable
to have the piston
130 move with the key
80. This alternative accomplishes
this objective. Referring now to FIG. 15, a variation on the embodiments of FIGS.
14 and 18 is shown. In this variation, a piston
132 includes a loop
134
which surrounds the key
80. When the coil
120 is energized, the piston
132 is pulled upwardly thereby pulling the loop
134 and the key
80
upwardly. An optional pad, cushion, or spring
136 may be placed between
the underside of the key
80 and the loop
134 to prevent noise. The
variation of FIG. 15 has an advantage over the embodiment of FIGS. 14 and 18 in
that the key
80 is not modified and therefore the weight of the key
80
is not changed.
In practice, a method for installing an above discussed embodiment of the invention
involves the removal of the key action from the piano and then removing all 88
wippens from the key action. The solenoid coil or body
120 is installed
in the wippen flange rail
94 by milling a hole perpendicular to the wippen
screw hole (used for attaching the wippen). There is one wippen screw hole for
each of the keys in the piano. This procedure is done for all 88 wippen screw holes.
Preferably, there is a technique for aligning each solenoid piston
122
with the proper location on each key
80. In one approach, a transfer punch
is inserted into the central hole of each of the 88 solenoid bodies to mark the
key. This alignment process is executed after the wippen flange rail
94,
with the solenoid bodies installed, has been reinstalled.
Referring again to FIG. 13, an additional actuator
138 may be placed
in the front of the key frame
92 with the piston
140 extending upwardly
into the underside of the key
80. As will be clear to those of skill in
the art, one of the actuators may be used without the other to actuate the key
80. However, using both actuators allows for greater dynamic range and for
cooler running actuators. The design illustrated in FIG. 13 also incorporates a
limited contact with the key
80. As best shown with the additional actuator
138, the piston
140 terminates inside of an empty space inside of
the key
80. As the key
80 is depressed, the key
80 may move
without moving the piston
140. The actuator
120 in the wippen flange
rail
94 is likewise configured. This arrangement allows the player to actuate
the key
80 without moving the pistons of the actuators, thereby avoiding
a "weighted" feel to the key.
Referring now to FIG. 16, another embodiment of an actuator mechanism for
a player grand piano is shown. In this embodiment, a solenoid
144 is mounted
in the back action of the piano with an L-shaped piston
146 extending downwardly
and forwardly therefrom such that the piston
146 terminates under the very
rear of the action end
90 of the key
80. The L-shaped piston
146
extends through a hole
148 in the damper underlever
110. This embodiment
takes advantage of the fact that there is room for a larger solenoid when it is
positioned in the back action of the piano. Use of larger solenoids potentially
increases the dynamic range of the player piano and also allows the use of less
expensive materials and designs for the solenoid
144. A solenoid positioned
in this location may be mounted either to the rear of the piano case (not shown)
or to the damper rail
112. As discussed earlier, the damper rail
112
is the stationary structural piece on which the damper underlever
110 is
pivotally supported.
Referring now to FIG. 19, another embodiment of the present invention for
use with grand pianos is shown. In this embodiment, a solenoid
150 is mounted
in the back action of the grand piano forward of the damper rod
114. Preferably,
the solenoid is positioned directly above where the damper underlever
110
and the key
80 overlap. Piston
152 of the solenoid
150 extends
downwardly from the solenoid
150 and terminates in a loop
154 which
surrounds both the action end
90 of the key
80 and the end of the
damper underlever
110. In this way, actuation of the solenoid coil
150
lifts the key
80 and the damper underlever
110 which sits on top
of the key
80. As discussed in an earlier embodiment, a pad or spring may
be located between the underside of the key
80 and the loop
154 to
help prevent play and noise. A spring (not shown) may also be positioned between
the underside of the loop and the key frame to preload the piston. Also, the loop
154 may be taller than shown to allow the key to be played without moving
the piston. The coil
150 may be mounted either to the rear of the piano
case or to the damper rail
112 by means of an offset rail. Such an offset
rail would run end to end in the piano and be solidly interconnected with either
the damper rail
112 or the piano case. It is most preferred that the solenoid
coil
150 be mounted to damper rail
112 by means of an offset rail.
In this way, the player piano actuating mechanism can be removed from the piano
case along with the damper or back action.
As will be clear to one of skill in the art, the solenoid configuration shown
in FIG. 19 may be interconnected to the key
80 in several ways. For example,
as shown in FIG. 17, a hole may be drilled through the rear end
90 of the
key
80 with an elongated piston
156 passing therethrough with a fixed
washer
158 and spring
160 between the key
80 and the key frame
92. A hole or slot
162 is also provided through the end of the damper
underlever
110.
As will be clear to one of skill in the art, a solenoid can be mounted farther
forward to a position just ahead of where the damper underlever
110 ends,
thereby preventing the need to drill a hole through the damper underlever
110.
In this configuration, if a loop were used, as shown in FIG. 19, the loop could
be made smaller since it no longer needs to surround the end of the damper underlever
110. This configuration of the actuator mechanism allows a large amount
of room for the solenoid, thereby allowing the use of less sophisticated and/or
more powerful solenoids.
Referring now to FIGS. 20 and 21, another embodiment of an actuation system
according to the present invention is shown. In this actuator system, a bracket
168 is mounted in the back action of the piano below the traditional position
for damper under levers. The bracket
168 includes a generally horizontal
roof
170 that is supported above the base of the key frame
92 by
roof support columns
172. The roof
170 is a generally continuous
member and the support columns
172 may be either a plurality of individual
columns or a continuous support. An actuator under lever
174 is pivotally
supported at its rear end
176 by the bracket
168 and extends forwardly
with its forward end
178 positioned under the rear end
90 of the
key
80. An electromechanical actuator
180 hangs downwardly from the
roof
170 of the bracket
168 so that the coil or body
182 is
supported just below the roof
170. The coil or body
182 is supported
in this position by a support
184 that allows slight pivotal movement of
the actuator
180. The actuator
180 is preferably a pull-type actuator
with the piston
186 extending downwardly out of the bottom of the coil
182
where it attaches to a mid portion of the actuator under lever
174 with
a pivotal connection
188. When the actuator
180 is energized, the
piston
186 is drawn upwardly into the coil
182 thereby pivoting the
actuator under lever
174 upwardly. This lifts the forward end
178
of the actuator under lever
174 upwardly causing the back end
90
of the key
80 to move upwardly as if it were struck by a human player.
Alternating actuators may be positioned forwardly or rearwardly of their
adjacent actuator to allow room for wider actuators. As shown in FIGS. 20 and 21,
this embodiment of the present invention requires an actuator that is very compact
vertically so as to allow the actuator to be packaged in the limited space below
the existing damper under lever. However, this approach avoids unnecessary modifications
to the case of the piano as it takes advantage of an area of unused space in the
back action of the piano.
As shown, the actuator system takes the place of the typical damper under lever
as was shown in earlier figures and therefore other provisions for lifting the
damper
116 from the string
102 must be made. One approach to relocation
of the damper system is shown in FIGS. 20 and 21. In this approach, a damper lift
foot
190 is positioned atop the rear end
90 of the key
80
and is housed in a guide hole
192 cut into the roof
170 of the bracket
168. The damper rod
114 extends upwardly from the foot
190
to the damper
116 so that upward movement of the rear end of the key
80
causes the damper
116 to be lifted from the string
102. The position
of the damper
116 on the string is important for proper performance of the
damper. Therefore, it may be necessary to reshape the damper
116 so as to
position it rearwardly of where shown so that it is in the same position as with
a traditional damper under lever. It is preferred that the foot
190 have
a felt and/or delrin® bottom portion so as to cushion and allow sliding movement
between the foot
190 and the key
80. This is also desirable between
the front ends of the under levers and the bottom side of the keys so as to reduce
noise and friction in the system.
An alternative approach to relocating the damper system is shown in FIG. 22.
In
this embodim
