Abstract: An optical position transducer is provided for each of the black/white keys incorporated in a composite keyboard musical instrument; the optical position transducer includes a photo-coupler radiating a light beam, an optical filter moved across the light beam, a recess formed in the black/white key at a proper position where the optical filter is aligned with a target trajectory crossing the light beam and an elastic coupler pressed to an inner surface defining the recess and secured to the optical filter so that a worker assembles the optical filter with the key by inserting the elastic coupler into the recess.

Abstract: A performance operator control apparatus adapted to a player piano comprises a motion control unit and a key drive unit comprising a plurality of key I/O control ICs in connection with keys of a keyboard, which are driven by solenoids so as to realize automatic performance, wherein upon detection of electrification abnormality of solenoids or temperature abnormality, LEDs are turned on to indicate the abnormality. The key I/O control ICs receive velocity signals regarding the solenoids so as to perform feedback controls on the keys in the automatic performance. In addition, unoccupied channels of the key I/O control ICs, which are not assigned to the keys and sensors, are used to input monitoring signals and to output inspection signals. Herein, the abnormality is determined based on the difference between pre-inspection data and post-inspection data, which are transferred using a loop connection channel of the key I/O control IC.

Abstract: An optical transducer includes a multi-port light emitting unit for distributing sensing light to minor bundles of optical fibers connected to input ports thereof and a multi-port light detecting unit for converting the sensing light to photo-current; an optical fiber plug, a socket and light detecting elements received in the socket are assembled in the multi-port light detecting unit; the optical fiber plug is made of semi-transparent colored synthetic resin, which is transparent to short-wavelength light and non-transparent to long-wavelength light, so that the minor bundles are adhered to the optical fiber plug through adhesive compound cured in the radiation of the short-wavelength light; the long-wavelength light serves as the sensing light so that leakage light does not reach the adjacent input ports.

Abstract: An optical transducer includes a photo-electric converter supported by a shank flange rail and optical modulators respectively attached to hammers of an automatic player piano; since a neck portion makes a photo-modulating pattern closer to the rotational axis of each hammer than a boss portion adhered to the side surface of the hammer shank, the photo-modulating pattern is rotated in a narrow space in the vicinity of the rotational axis so as to permit the photo-electric converter to monitor the hammer motion between the rest position and the end position without any interference with other component parts, and the boss portion is easily adhered to the side surface under the condition that a worker lifts the hammer over the adjacent hammers.

Abstract: An optical transducer includes a light emitting unit, a light detecting unit, light radiating sensor heads and light receiving sensor heads; the light radiating sensor heads and light receiving sensor heads are alternately arranged at intervals, and moving objects pass through the intervals in such a manner as to intersect light beams between the sensor heads; since the light emitting unit and light detecting unit are remote from the sensor heads, the light emitting unit and light detecting units are optically coupled to the sensor heads through optical fibers; a bundle of optical fibers is clipped on a predetermined route, and the optical fibers swerve from predetermined points of the bundle so that the optical fibers are surely warped so as to exert the resilient force on the inner surfaces of the optical devices, thereby being kept stable during the adhesion therebetween.

Abstract: A shutter holder has a frame-like base portion and a tie plate inwardly projecting from a side portion of the base portion in a cantilever fashion, and the tie plate has a rectangular cross section smaller in thickness and/or width, i.e., second moment of inertia than the cross section of the base plate at the boundary; even if a staple is deeply driven into a moving object such as a wooden key, the tie plate is widely deflected so as to absorb the deformation of the wooden key, and permits a shutter plate to keep itself perpendicular to the lower surface of the wooden key.

Abstract: An electronic piano is controllable with a remote controller; since the remote controller is physically separated from the electronic piano, users are liable to mislay the remote controller somewhere around the electronic piano; in this situation, the user instructs the electronic piano to transmit a radio wave representative of inquiry, and the missing remote controller responds to the inquiry by transmitting a radio wave representative of annunciation; the electronic piano is equipped with antennas separated from each other on the piano cabinet, and the received power at the antennas is varied depending upon the location of the missing remote controller; the electronic piano analyzes the received power so as to notify the user of the possible location of the missing remote controller.

Abstract: An optical position transducer is provided for each of the black/white keys incorporated in a composite keyboard musical instrument; the optical position transducer includes a photo-coupler radiating a light beam, an optical filter moved across the light beam, a recess formed in the black/white key at a proper position where the optical filter is aligned with a target trajectory crossing the light beam and an elastic coupler pressed to an inner surface defining the recess and secured to the optical filter so that a worker assembles the optical filter with the key by inserting the elastic coupler into the recess.

Abstract: An optical sensor array includes plural sensor heads arranged on a supporting plate at intervals for monitoring moving objects such as black/white keys of a composite keyboard musical instrument; the sensor head has resiliently deformable arms on both side portions thereof and a locating hole/guide groove are formed in the reverse surface portion of the sensor head, and an expander, a grip and projections are formed in the supporting plate; when a worker slides the sensor head on the expander, the resiliently deformable arms make the gap wider so that the grip is pinched between the resiliently deformable arms and that the projections are engaged with the locating hole and guide groove, whereby the sensor head is easily fixed to and located at a predetermined position on the supporting plate.

Abstract: A shutter holder has a frame-like base portion and a tie plate inwardly projecting from a side portion of the base portion in a cantilever fashion, and the tie plate has a rectangular cross section smaller in thickness and/or width, i.e., second moment of inertia than the cross section of the base plate at the boundary; even if a staple is deeply driven into a moving object such as a wooden key, the tie plate is widely deflected so as to absorb the deformation of the wooden key, and permits a shutter plate to keep itself perpendicular to the lower surface of the wooden key.

Abstract: A light emitting device includes an optical fiber plug formed with a through-hole into which a bundle of optical fibers is inserted and a light-emitting device holder formed with a through-hole in which a condenser lens and a light emitting device are accommodated, and the optical fiber plug is assembled with the light-emitting device holder so that the light emitting device is optically coupled to the optical fiber through the condenser lens; a positioning device, a hyperboloid lens surface or a reflecting surface is formed in the optical fiber plug/light emitting device holder, condenser lens or the inner surface of the light-emitting device holder so that the light incident on the light input end is increased by virtue of the exact positioning between the optical fiber and optical axis, reduction of aberration or increase of light directed to the condenser lens.

Abstract: An optical sensor array includes light-emitting devices and sensor heads remote from the light-emitting devices, and each light-emitting device is optically coupled to plural sensor heads through optical fibers; the light-emitting device is optically connected to the optical fibers by means of a multicore optical fiber connector, and the multicore optical fiber connector keeps the optical axes of the optical fibers equally spaced from the optical axis of the light-emitting device; even though the light intensity is isotropically dispersed on the cross section of the light beam, the total amount of light incident on each optical fiber is equal to the total amount of light incident on any one of the other optical fibers so that a strict calibration is not required for the optical sensor array.

Abstract: An optical sensor system includes a light emitting unit, a light detecting unit, light radiating optical sensor heads connected through optical fibers to the light emitting unit and light receiving optical sensor heads connected through optical fibers to the light detecting unit, and light is selectively distributed to the light radiating optical sensor heads for radiating light beams from both side surfaces of each sensor head to the adjacent light receiving optical sensor heads for converting the incident light to photo-current; each light radiating optical sensor head has prisms for splitting the light into two beams; however, the stray light is produced at the edge between the reflection surfaces; the stray light is reduced or predictably controlled by forming textured pattern on the side surfaces, a photo-shield member or notches; otherwise, the edge is sharpened by separately forming the prisms.

Abstract: A hammer sensor includes a photo-filter plate movable together with a hammer assembly and having a base plate fixed to the hammer shank and an arc pattern formed on the base plate and different in transparency from the base plate, a photo radiating element radiating a light beam toward the arc pattern and a photo detecting element disposed on the optical path of the light beam for converting the amount of transmitted light to an electric signal, wherein the photo-filter plate converts the rotational angle of the hammer assembly to the amount of light incident on the photo detecting element, and makes the photo radiating element and the photo detecting element stationary so that a suitable photo-shield case prevents the photo elements from environmental light.

Abstract: An optical position transducer is provided for each of the black/white keys incorporated in a composite keyboard musical instrument; the optical position transducer includes a photo-coupler radiating a light beam, an optical filter moved across the light beam, a recess formed in the black/white key at a proper position where the optical filter is aligned with a target trajectory crossing the light beam and an elastic coupler pressed to an inner surface defining the recess and secured to the optical filter so that a worker assembles the optical filter with the key by inserting the elastic coupler into the recess.

Abstract: A hammer sensor includes a photo-filter plate movable together with a hammer assembly and having a base plate fixed to the hammer shank and an arc pattern formed on the base plate and different in transparency from the base plate, a photo radiating element radiating a light beam toward the arc pattern and a photo detecting element disposed on the optical path of the light beam for converting the amount of transmitted light to an electric signal, wherein the photo-filter plate converts the rotational angle of the hammer assembly to the amount of light incident on the photo detecting element, and makes the photo radiating element and the photo detecting element stationary so that a suitable photo-shield case prevents the photo elements from environmental light.

Abstract: An electromagnetic device has a bobbin with collars projecting from a cylindrical body, L-shaped conductive pins partially embedded in the collar so that first end portions and second end portions respectively project from the side surface and the lower surface of the collar, an insulated wire wound on the cylindrical body and connected at both ends thereof to the first end portions, a plunger projectable from and retractable into the cylindrical body, a socket holder attached to the bobbin so as to prevent the first and second end portions from damage and a socket coupled to the socket holder for connecting a cable to the second end portions, thereby allowing a manufacturer to increase the turns of the coil without enlarging the bobbin.

Abstract: An optical sensor array includes plural sensor heads arranged on a supporting plate at intervals for monitoring moving objects such as black/white keys of a composite keyboard musical instrument; the sensor head has resiliently deformable arms on both side portions thereof and a locating hole/guide groove are formed in the reverse surface portion of the sensor head, and an expander, a grip and projections are formed in the supporting plate; when a worker slides the sensor head on the expander, the resiliently deformable arms make the gap wider so that the grip is pinched between the resiliently deformable arms and that the projections are engaged with the locating hole and guide groove, whereby the sensor head is easily fixed to and located at a predetermined position on the supporting plate.

Abstract: An automatic player is combined with an acoustic piano for selectively moving black/white keys with plungers of solenoid-operated key actuators, and plunger sensors detect current positions of the plungers on trajectories for supplying feedback signals to a controller for exactly controlling the solenoid-operated key actuators, wherein each of the plunger sensors has a reflecting plate fixed to the bottom surface of the plunger and a photo-coupler radiating a light beam to the reflecting plate for producing the feedback signal from the reflection so that the plunger sensor is compact and free from noise and aged-deterioration.

Abstract: An automatic player piano is an acoustic piano equipped with a data acquisition system and a playback system, and the data acquisition system monitors the hammers with hammer sensors for producing a set of music data codes representative of a performance on the keyboard, wherein the hammer sensor has a detectable range over the trajectory of the associated hammer so that the data acquisition system obtains pieces of music data accurately representative of the trajectory of hammer to be required for a faithful reproduction of the original performance.