Music – Instruments – Electrical musical tone generation
Reexamination Certificate
2000-12-13
2002-06-11
Donels, Jeffrey (Department: 2837)
Music
Instruments
Electrical musical tone generation
C084S021000
Reexamination Certificate
active
06403872
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a keyboard musical instrument and, more particularly, to a keyboard musical instrument equipped with an information processing system and a data acquisition system for generating music data information representative of a performance on the keyboard musical instrument.
DESCRIPTION OF THE RELATED ART
An automatic player piano is categorized in the keyboard musical instrument. The automatic player piano is based on an acoustic piano, and an automatic playing system and a data acquisition system are assembled with the acoustic piano. While a pianist is playing a tune on the acoustic piano, the data acquisition system monitors the keys to see whether or not the pianist depresses any one of the keys. When the data acquisition system notices a key moving from the rest position toward the end position, the data acquisition system specifies the key and the key velocity, and generates a piece of music data information representative of the key motion. The data acquisition system successively generates pieces of music data information during the performance. The pieces of music data information are stored in a suitable memory for playback. Otherwise, the data acquisition system formats the pieces of music data information into music data codes, and supplies the music data codes to another musical instrument such as, for example, an electric keyboard for producing the electronic sounds.
The prior art data acquisition system has an array of key sensors, which are assigned to the keys of the keyboard, respectively. The key sensor is broken down into a pair of photo couplers and a shutter plate. The shutter plate is attached to the lower surface of the associated key, and downwardly projects therefrom. The photo couplers are provided under the associated key, and are arranged along the trajectory of the shutter plate. When the key is depressed, the shutter plate is downwardly moved together with the key, and sequentially interrupts the light beams of the photo couplers. The detecting signals are sequentially supplied from the photo couplers to a data processing unit. The data processing unit specifies the depressed keys and determines the key velocity on the basis of the time period between the interruption at the first photo coupler and the interruption at the next photo coupler. The key velocity determines the loudness of the sound to be proportional thereto. The data processing unit further estimates a time to strike the associated music string with the hammer on the basis of the key velocity and the time to be interrupted by the shutter plate.
If the player simply depresses all the keys from the rest positions to the end positions, the prior art data acquisition system will generate a set of music data codes exactly representing the original performance. However, such fingering is rare. A pianist repeats the depression without reaching the rest position. The times to strike the music string are different from those stored in the music data codes, and the loudness of the actual sound is deviated from the loudness stored in the music data code. For example, a player is assumed to insert a repetition in his performance. The keystroke is short, and the actual piano sound is weak. However, the key velocity is large, and the large loudness is stored in the music data code. If the automatic player reproduces the sound on the basis of the music data code, the hammer violently strikes the music string, and makes the reproduced sound different from the original sound.
A countermeasure has been proposed. In order to exactly determine the loudness of the actual sound, hammer sensors are attached to the acoustic piano.
FIG. 1
shows the prior art hammer sensors
70
associated with one of the hammers. In the following description, term “front” is indicative of a position closer to a player sitting for playing a tune on the keyboard, and, accordingly, term “rear” is indicative of a position farther from the player than the front position. Term “lateral” is indicative of a direction in which the keys are arranged on a key bed.
The hammer is broken down into a hammer shank
43
and a hammer head
44
. The hammer shank
43
upwardly projects from a hammer butt
41
, and the hammer head
44
is fixed to the leading end of the hammer shank
43
. Reference numeral
46
designates a catcher frontward projecting from the hammer butt
41
.
A shutter plate
71
and a photo coupler
77
serve in combination as the hammer sensor
70
. The shutter plate
71
is attached to the hammer shank
43
, and rearward projects form the hammer shank
43
. The shutter plate
71
is moved together with the hammer shank
43
, and is movable with respect to the associated music string S. A slit
71
a
is formed in the leading end portion of the shutter plate
71
. On the other hand, the photo coupler is attached to brackets, and is stationary with respect to the associated music string S. The photo coupler
77
consists of a light emitting element and a light detecting element, and a light beam P is radiated from the light emitting element to the light detecting element. When the hammer is staying at the rest position, the shutter plate
71
is spaced from the light bean P as indicated by the real line, and the photo coupler supplies a hammer position signal of a high voltage level to a data processing unit (not shown).
A player is assumed to depress the associated key. The depressed key actuates the associated action mechanism, and the action mechanism drives the hammer for rotation. When the hammer reaches an intermediate position H
2
, the shutter plate
71
interrupts the light beam P at the leading end thereof, and the hammer position signal falls to a low voltage level. The data processing unit acknowledges that the hammer head
44
reaches the intermediate position H
2
. The hammer is further rotated, and reaches the next intermediate position H
3
. Then, the slit
71
a
is aligned with the light beam P, and the photo coupler
71
recovers the hammer position signal to the high voltage level. The data processing unit acknowledges that the hammer reaches the next intermediate position H
3
. The distance between the intermediate positions H
2
and H
3
is known, and the data processing unit is notified the times when the hammer shank
43
reaches the intermediate position H
2
and the intermediate position H
3
. The data processing unit determines the interval between two interrupting times, and calculates the hammer velocity between the intermediate positions H
2
and H
3
. The intermediate positions H
2
and H
3
are arranged in such a manner as to be close to the final position where the hammer head
44
strikes the music string S, because the hammer velocity is exactly proportional to the intensity of the impact between the hammer head
44
and the music string S and, accordingly, the loudness of the original sound. The prior art data acquisition system formats the piece of music data information exactly representative of the loudness. When the automatic playing system reproduces the sound on the basis of the music data codes, the hammer strikes the music string S at the intensity equal to that in the original performance, and the music string S reproduces the sound at the original loudness.
The hammer sensors
70
are expected to detect the hammer velocity in the monitoring section between the intermediate positions H
2
and H
3
arranged to be as close to the music string S as possible. However, it is impossible to keep all the hammer sensors at the appropriate positions. This is because of fact that the distance between the hammers at the rest positions and the associated music strings S is varied. The variance is of the order of 2 millimeters in standard grand pianos.
In detail, the hammers are rotatably supported by a shank flange rail, which in turn is supported by the action brackets. The action brackets are mounted on the key bed. The total weight of the hammers is exerted on the shank flange rail, and the shank flange rail is less deformed. The action mechanis
Kato Tadaharu
Kawamura Kiyoshi
Muramatsu Shigeru
Oba Yasuhiko
Donels Jeffrey
Morrison & Foerster / LLP
Yamaha Corporation
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