Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2001-11-29
2004-03-30
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S229000, C084S639000, C084S724000, C084S744000
Reexamination Certificate
active
06713751
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an optical sensor preferable for a musical instrument and, more particularly, to an optical sensor for producing an electric signal representative of a current position of a moving object and a musical instrument equipped with an array of the optical fiber sensors.
DESCRIPTION OF THE RELATED ART
There are several types of a composite keyboard musical instrument. A composite keyboard musical instrument is known as an automatic player piano, and another composite keyboard musical instrument is called as “silent piano”. In the following description, word “lateral” is indicative of the direction in which black keys and white keys are arranged on the well-known pattern employed in the standard acoustic piano. Word “perpendicular” is indicative of the direction crossing the lateral direction at 90 degrees.
The automatic player piano is the combination of an acoustic piano and an electric system for an automatic playing and recording. The electric system includes an array of solenoid-operated key actuators, an array of key sensors and a data processing system. The array of solenoid-operated is usually provided in a space formed in the key bed under the rear portions of the black/white keys, and the array of key sensors is placed on the key bed under the front portions of the black/white keys. A user is assumed to instruct the data processing system to record his performance on the keyboard. While the user is playing a piece of music on the keyboard, the key sensors periodically report the current key positions to the data processing system. The data processing system specifies the times at which the black/white keys are depressed and released, and estimates the loudness of the tones. The data processing system stores these pieces of music data information in music data codes, and records the music data codes representative of the performance in a suitable memory. When the user requests the data processing system to reproduce the tones, the data processing system reads out the music data codes, and determines times to move the black and white keys as well as the values to the key velocity to be imparted to the black and white keys. The data processing system sequentially supplies driving current signals to the solenoid-operated keys at the appropriate timings. Then, the solenoid-operated keys give rise to key motions so as to reproduce the tones.
The silent piano is the combination of an acoustic piano, a hammer stopper and an electronic tone generating system. When a user changes the hammer stopper to a free position, the hammer stopper is moved out of the trajectories of the hammers. While the user is fingering a piece of music on the keyboard, the depressed black/white keys give rise to free rotation of the hammers, and the hammers strike the associated strings so as to generate the piano tones. Thus, the silent piano behaves as an acoustic piano. The user is assumed to change the hammer stopper to a blocking position, the hammer stopper enters the trajectories of the hammers. After the entry into the blocking position, although the depressed key makes the action mechanism escape from the associated hammer, the hammer rebounds on the hammer stopper before striking the string. Any piano tone is not generated from the string. However, the electronic tone generating system produces electronic tones instead of the piano tones. The electronic tone generating system has an array of key sensors, a data processing system and a sound system. While the user is fingering a piece of music on the keyboard, the key sensors periodically report the current key positions of the associated black and white keys to the data processing system. The data processing system specifies the depressed keys and the released keys, and estimates the loudness of the tones. The data processing system stores these pieces of music data information in music data codes, and produces an audio signal from the music data codes. The audio signal is supplied to the sound system, and the sound system such as a headphone converts the audio signal to the electronic tones.
The key sensors may be replaced with hammer sensors. In this instance, the hammer sensors periodically report the current hammer positions to the data processing system, and the data processing system produces the music data codes on the basis of the hammer motion. Thus, the key sensors or the hammer sensors are indispensable components of the composite keyboard musical instrument.
Various kinds of key/hammer sensors have been employed in the composite keyboard musical instrument. Photo-couplers and optical fiber sensors are popular among the manufacturers. The photo-coupler, i.e., a light emitting element and a light detecting are provided on both sides of the trajectory of the associated black/white key, and a light beam is radiated from the light emitting element to the light detecting element across the trajectory of the associated black/white key. A shutter plate is fixed to the lower surface of the associated black/white key, and the shutter plate interrupts the light beam at predetermined points on the trajectory. The light detecting element converts the amount of light incident thereon to photo-current, and the key/hammer position is represented by the potential level converted from the photo-current. The potential level is further converted to a binary value of a digital signal, and the digital signal is supplied to the data processing system as the key/hammer position signal.
The photo-coupler is required for each of the black/white keys or each of the hammers. Eighty-eight keys usually form the keyboard. Accordingly, eighty-eight photo-couplers are to be installed in the narrow space between the key bed and the black/white keys or inside the piano case as close to the strings as possible. Although each photo-coupler is small in volume, the array of eighty-eight keys occupies a substantial amount of space. This results in complicated arrangement inside the piano case.
The optical fiber sensor was proposed in order to make the internal arrangement simple. The optical fiber sensor has a multiple-port sensor head connected through optical fibers to a combined optical element serving as a light emitting element and a light detecting element. Only the multiple-port sensor heads are installed inside the piano case, and the combined optical elements are provided in a relatively wide space. For this reason, the optical fiber sensors are preferable for the combined keyboard musical instrument.
FIG. 1
shows a typical example of the key sensor array implemented by the optical fiber sensors. The prior art key sensor array
50
includes plural sensor heads S
1
, plural shutter plates
52
, pairs of optical fibers
55
/
60
and combined optical elements (not shown). The sensor heads
51
are formed of transparent acrylic resin, and are arranged at intervals in the lateral direction. The shutter plates
52
are respectively fixed to the lower surfaces of the black and white keys
65
of the keyboard, and are movable together with the associated black and white keys. A light emitting port
53
and a light receiving port
54
are formed in each of the sensor heads
51
, and are laterally directed.
As will be better seen in
FIG. 2
, the sensor heads
51
has a pair of shoulder portions
51
a
, a bulk portion
51
b
and a neck portion
51
c
. The neck portion
51
c
is narrower than the bulk portion
51
b
, and the shoulder portions
51
a
are formed on the steps between the neck portion
51
c
and the bulk portion
51
b
. Lenses
57
/
58
are fixed to the perpendicular surfaces of the shoulder portions
51
a
, respectively, and slant surfaces
59
are formed in the shoulder portions
51
a
. The lens
57
and the shoulder portion
51
a
form the light emitting port
53
, and the other lens
58
and the shoulder portion
51
a
form the light receiving port
54
. A pair of holes
61
is further formed in the sensor head
51
, and extends from the lateral surface to certain points in the bulk portion
51
b
. The holes
Muramatsu Shigeru
Sasaki Tsutomu
Allen Stephone B.
Dickstein Shapiro Morin & Oshinsky LLP.
Yamaha Corporation
LandOfFree
Easily assembled optical fiber sensor and musical instrument... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Easily assembled optical fiber sensor and musical instrument..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Easily assembled optical fiber sensor and musical instrument... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3266538