Easily assembled optical fiber sensor and musical instrument using the same

#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.

#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 features and advantages of the optical sensor and the musical instrument will be more clearly understood from the following description taken in conjunction with the accompanying drawings in which:

#FIG. 1 is a plane view showing the array of the prior art optical fiber sensors;

#FIG. 2 is a partially cut-away plane view showing the structure of sensor head incorporated in the prior art optical fiber sensor;

#First Embodiment

#Referring to FIG. 3 of the drawings, an automatic player piano embodying the present invention is largely comprises an acoustic piano 70, a recording system 72 and an automatic playing system 74. The acoustic piano is a standard grand piano, and comprises eighty-eight black and white keys 71a, action mechanisms 71b, clampers 71c, strings 71d and hammer assemblies 4. These component parts 71a, 71b, 71c and 71d are assembled in the grand piano 70 as well known in the art, and no further description is hereinbelow incorporated for the sake of simplicity.

#The recording system 72 comprises an array of hammer sensors 1 and a data processing system 72a. The hammer sensor 1 is implemented by an optical fiber sensor. For this reason, the optical fiber sensor is also labeled with reference numeral 1. The eighty-eight hammer assemblies 4 are monitored by the eighty-eight hammer sensors 1, and the hammer sensors 1 periodically supply hammer position signals to the data processing system 72a. The data processing system 72a fetches pieces of positional data information stored in the hammer position signals, and stores the pieces of positional data information in a working memory thereof. The data processing system 72a analyzes the pieces of positional data information so as to specify the black/white keys 71a depressed and released by a pianist and estimate the loudness of piano tones to be produced through the vibrations of the strings 71d. The data processing system 72a further determines the time at which each black/white key 71a is depressed or released. Thus, the data processing system 72a obtains pieces of music data information representative of the performance through the analysis on the pieces of positional data information, and produces a set of music data codes also representative of the performance.