Music – Instruments – Electrical musical tone generation
Reexamination Certificate
2002-06-13
2004-11-09
Fletcher, Marlon T. (Department: 2837)
Music
Instruments
Electrical musical tone generation
C084S423001, C084S439000, C084S719000, C084S720000, C084S745000
Reexamination Certificate
active
06815603
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an optical sensor array and, more particularly, to an optical sensor array for detecting current positions of plural moving objects such as, for example, keys and hammers incorporated in a keyboard musical instrument and a keyboard musical instrument using the same.
DESCRIPTION OF THE RELATED ART
Several sorts of composite keyboard musical instruments are sold in the market. A composite keyboard musical instrument is a compromise between an acoustic keyboard musical instrument, i.e., a piano and an electronic keyboard. A player can selectively play a tune through acoustic sound and electronic sound. This sort of composite keyboard musical instrument has been known as “silent piano”. When a pianist instructs the silent piano to enter the acoustic sound mode, a hammer stopper is moved out of the trajectories of hammers so as to permit the hammers selectively to strike the strings for generating the piano tones. On the other hand, if the pianist wishes to practice the fingering on the keyboard, he or she changes the silent piano to the silent mode. Then, the hammer stopper is moved into the trajectories of the hammers. While the pianist is fingering a tune on the keyboard, the action mechanism selectively drives the hammers for rotation. Although the hammers escape from the action mechanism, they rebound on the hammer stopper before striking the strings. No string vibrates. Thus, the pianist can practice the fingering without disturbance to his or her neighbors.
The silent piano is equipped with an electronic sound generating system. The electronic sound generating system comprises an array of key sensors, an array of hammer sensors, a data processing unit and a headphone. The array of key sensors is provided under the array of black and white keys, and supplies key position signals representative of the current key positions of the associated black and white keys to the data processing unit. On the other hand, the array of hammer sensors is provided in the vicinity of the array of the hammers, and supplies hammer position signals representative of the current hammer positions of the associated hammers to the data processing unit. The data processing unit periodically fetches the key position signals and hammer position signals from the signal ports assigned thereto, and accumulates pieces of data information representative of the variation of key/hammer position of each key/hammer in the data storage. The data processing unit periodically checks the data storage to see whether or not the pianist depresses any one of the black/white keys for generating a tone. If the data processing unit finds the pianist to depress a black/white key, the data processing unit determines the key velocity and timing at which the piano to is to be generated. The data processing unit produces music data codes representative of the tone to be produced, and converts the music data codes to an audio signal. The audio signal is supplied to the headphone, and the pianist hears the electronically produced tone through the headphone. Thus, the key/hammer sensors are indispensable component parts of the silent piano.
FIG. 1
shows a prior art optical sensor array
100
. The prior art optical sensor array serves as the key sensors, and is provided under the array of black/white keys. Reference numeral
101
designates shutter plates. The shutter plates are attached to the black/white keys, respectively, and downwardly project from the lower surfaces of the associated black/white keys.
The prior art optical sensor array
100
largely comprises a supporting plate
103
, plural sensor heads
104
and pairs of optical fibers
105
/
111
. Slits
102
are formed in the supporting plate
103
at intervals, and the shutter plates
101
are aligned with the slits
102
, respectively. The slits
102
are wider than the shutter plates
101
, and permit the shutter plates
101
to be moved deeply into the space under the supporting plate
103
.
The plural sensor heads
104
are attached to the supporting plate
103
at intervals, and are located on both sides of the slits
102
. Thus, the sensor heads
104
are arranged such that the shutter plates
101
project into and are retracted from the gaps between the sensor heads
104
.
The sensor heads
104
are formed of transparent acrylic resin, and have a configuration like a combination of large and small rectangular parallelepiped blocks. The small rectangular parallelepiped block projects from an end surface of the large rectangular parallelepiped block, and shoulders take place on both sides of the small rectangular parallelepiped block. A light outlet port
108
is provided on one of the shoulders, and a light inlet port
112
is provided on the other shoulder. The light outlet port
108
and light inlet port
112
of each sensor head
104
are aligned with the light inlet port
112
of one of the adjacent sensor heads
104
and the light outlet port
108
of the other adjacent sensor head
104
. Thus, the light outlet ports
108
and the light inlet ports
112
are provided on optical paths.
A prism
106
and a collimator lens
107
as a whole constitute the light outlet port
108
, and a condenser lens
109
and a prism
110
form in combination the light inlet port
112
. Two holes are formed in the large rectangular parallelepiped block, and are open to the shoulders and the other end surface. The optical fiber
105
is inserted into one of the holes, and reaches the prism
106
. The other optical fiber
111
is also inserted into the other hole, and reaches the prism
110
.
Though not shown in
FIG. 1
, a light emitting device (not shown) is connected to the other end of the optical fiber
105
, and a light detecting device is connected to the other end of the optical fiber
111
. When the light emitting device is energized, light is radiated from the light emitting device into the optical fiber
105
, and optical fiber
105
propagates the light to the prism
106
. The light is reflected on the oblique surface of the prism
106
, and is formed into a parallel ray through the collimator lens
107
. The parallel ray proceeds toward the light inlet port
112
of the adjacent sensor head
104
, and is incident into the light inlet port
112
of the adjacent sensor head
104
.
The incident light is reflected on the oblique surface of the prism
110
, and is fallen into the optical fiber
111
. The optical fiber
111
propagates the light to the light detecting device, and the light detecting device converts the light to photo current.
A pianist is assumed to depress a black/white key. The black/white key is sunk, and, accordingly, the shutter plate
101
is moved downwardly. The shutter plate
101
reaches the optical path, and gradually interrupts the parallel ray. Accordingly, the amount of incident light is reduced, and the light detecting device reduces the photo-current. Thus, the current key position is converted to the amount of photo-current.
FIG. 2
shows another prior art optical sensor array. The prior art optical sensor array comprises the supporting plate
103
, sensor heads
121
/
122
and optical fibers
105
/
111
. The sensor heads
121
/
122
are alternated with the slits
102
, and each sensor head
121
/
122
is associated with only one optical fiber
105
/
111
.
The sensor head
121
/
122
comprises a body
121
a
and a pair of lenses
107
/
109
. The body
121
a
has side surfaces parallel to each other, and the lenses
107
/
109
are attached to the side surfaces. A notch forms a pair of oblique surfaces
120
in the body
121
a
, and the optical fiber
105
/
111
is retained by the body
121
a
in such a manner that light is radiated to and received from the pair of oblique surfaces
120
.
The optical fibers
105
/
111
are connected to a combined optical device, i.e., the combination of light-emitting and light-detecting elements. The combined optical device sequentially supplies light to the sensor heads
121
. This means that the combined optical device supplies the light to the sensor head
Kato Tadaharu
Muramatsu Shigeru
Fletcher Marlon T.
Morrison & Foerster / LLP
Yamaha Corporation
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