Automatic Player Piano Having Frame Structure Self-Aligned With Keyboard for Exactly Positioning Key Actuators Arranged in Staggered Manner

This invention relates to an automatic player piano and, more particularly, to an automatic player piano having a frame structure self-aligned with a keyboard for exactly positioning solenoid-operated key actuator units arranged in a staggered manner.

The automatic player piano is equipped with a plurality of solenoid-operated key actuator units under the keyboard, and the solenoid-operated key actuator units selectively project the plungers so as to move the black and white keys without a fingering of a pianist.

At typical example of the automatic player piano is disclosed in Japanese Utility model Publication of Examined Application No. 6-37269. The Japanese Utility Model Publication of Examined Application discloses two kinds of arrangement of solenoid-operated key actuator units. These two kinds of arrangement are firstly described hereinbelow. In the following description, term "lateral direction" means a direction parallel to the center line around which the black and white keys turn, term "fore-and-aft direction" means a direction perpendicular to the lateral direction on a virtual plane parallel to the key bed, and term "vertical direction" is a direction normal to the virtual plane or a direction parallel to the gravity. Direction of "clockwise" and direction of "counter clockwise" are determined on the figure which description refers to.

One of the two kinds of arrangement is featured by a staggered arrangement of solenoid-operated key actuator units. A bracket member is provided under the key bed, and the solenoid-operated key actuator units are attached to the bracket. The solenoid-operated key actuator units respectively have the projectable plungers aligned with the black and white keys, and are arranged in the lateral direction. The solenoid-operated key actuator units are staggered so as to space every other solenoid-operated key actuator unit from the adjacent solenoid-operated key actuator units in the vertical direction, and the staggered arrangement allows the solenoid-operated key actuator units to occupy wide spaces, respectively. In other words, the solenoid-operated key actuator units are allowed to have large solenoids, and the large solenoid imparts large force to the plunger.

The other kind of arrangement is featured by an elongated yoke shared between the solenoid-operated key actuator units. The yoke is elongated in the lateral direction, and accommodates the solenoids. Although the elongated yoke makes the solenoids stand in line, the solenoid-operated key actuator units have large solenoids, and impart strong forces to the associated black and white keys.

Thus, the prior art arrangements of solenoid-operated key actuator units allows the manufacturer to enlarge the solenoids, and the large solenoids cause the plungers to strongly push the associated black and white keys. However, the first prior art arrangement of solenoid-operated key actuator units encounter a problem in poor durability. As described hereinbefore, every other solenoid-operated key actuator unit is spaced from the adjacent solenoid-operated key actuator units in the vertical direction. Although the solenoid-operated key actuator units in the upper line are close to the black and white keys, the other solenoid-operated key actuator units in the lower line are fairly spaced from the associated keys, and the long distance requires long plungers to push the associated keys. When the plunger pushes the associated key, the reaction takes place at the leading end of the plunger, and causes the long plunger to be bent. Therefore, the solenoid-operated key actuator units in the lower line are not durable.

Another problem in the first prior art arrangement of solenoid-operated key actuator units is the over-crowded spacious arrangement under the key bed. The space under the key bed is occupied by various parts and mechanisms such as links of the pedal mechanisms, and the bracket interferes with these parts and mechanisms. For this reason, it is hard to retrofit an acoustic piano to the automatic player piano by using the first prior art arrangement of solenoid-operated key actuator units.

The second prior art solenoid operated key actuator units encounter a problem in insufficient force transferred to the associated key. Although the elongated yoke allows the manufacturer to enlarge the solenoids, the pitch of keys sets a limit to the enlargement. The pitch of keys incorporated in a standard acoustic piano ranges from 13 millimeters to 15 millimeters, and, accordingly, the plungers are also arranged at the same pitch. This means that the solenoids are never enlarged over the pitch, and limit the electromagnetic force.

One solution is proposed in Japanese Utility Model Publication of Unexamined Application No. 58-38195. The prior art automatic player piano disclosed in the Japanese Utility Model Publication is illustrated in FIG. 1 of the drawings. The prior art automatic player piano largely comprises an acoustic piano 1 and an automatic playing system 2. The acoustic piano 1 includes a keyboard mounted on a key bed 1b. A balance rail 1c is provided on the key bed 1b, and a plurality of black and white keys 1d are turnably supported by the balance rail 1c. Although the black and white keys 1d are connected to key action mechanisms for striking strings with hammers, the structure of the acoustic piano is well known to a person skilled in the art, and they are not shown in FIG. 1.

The automatic playing system 2 includes a plurality of solenoid-operated key actuator units 2a, a driving circuit 2b fabricated on a print board 2c and a frame structure 2d for supporting the solenoid-operated key actuator units 2a and the print board 2c. A pan 2e and a cover plate 2f form an inner space, and are bolted through a bracket member to the key bend 1b and the balance rail 1c, respectively. The print board 2c is inserted between the bracket member 2g and the pan 2e, and is fixed thereto.

A plurality of pairs of through holes 2h are formed in the pan 2e and the cover plate 2f, and are arranged in a staggered manner. The pairs of through holes 2h are respectively assigned to the solenoid-operated key actuator units 2a, and, accordingly, the solenoid-operated actuator units 2a are arranged in the staggered manner. The solenoid-operated key actuator units 2a make two rows spaced apart from one another in the fore-and-aft direction.

Each of the solenoid-operated key actuator units 2a includes a bobbin 2i accommodated in the inner space, a coil 2j wound on the bobbin 2i, yokes 2k inserted into the pair of through-holes 2h, a plunger 2m slidably inserted into the yokes 2k and a cushion member 2n attached to the leading end of the plunger 2n. When the driving circuit 2b applies electric current to the coil 2j, the yokes 2k is magnetized, and cause the plunger 2m to upwardly project therefrom. As a result, the cushion member 2n pushes up the key 1d, and the key 1d is moved as if a player depresses it.

The solenoid-operated key actuator units 2a are arranged in the staggered manner on the key bed 1b, and the plungers 2m are relatively shorter than those of the solenoid-operated key actuator units incorporated in the Japanese Utility Model Publication of Examined Application No. 62-37269. For this reason, the plungers 2m are hardly bent, and are, accordingly, durable. However, the automatic playing system 2 encounters a problem in repairing work. The frame structure 2d is provided between the key bed 1b and the keyboard 1a, and the solenoid-operated key actuator units 2j are accommodated in the inner space between the pan 2e and the cover plate 2f. If one of the solenoid-operated key actuator units 2a is broken down, a repairing worker firstly removes the keyboard 1a, and loosens the bolts so as to move the frame structure to a floor. Then, the repairing worker removes the cover plate 2f from the pan 2e, and changes the broken solenoid-operated key actuator unit 2a to new one. The repairing work is usually required after a delivery to a user, and the repairing worker feels the work difficult.

Another solution is disclosed in Japanese Utility Model Publication of Unexamined Application No. 2-95394, and the prior art automatic player piano is illustrated in FIG. 2 of the drawings. The prior art automatic player piano also comprises an acoustic piano 3 and an automatic playing system 4. The acoustic piano 3 is a grand piano, and a keyboard 3a is placed on a key bed 3b formed of wood. Black and white keys 3c and 3d are turnably supported by a balance rail 3e. Key action mechanisms 3f are connected to the black and white keys 3c/3d, and drive hammers 3g, respectively, so as to strike strings (not shown).

The automatic playing system 4 comprises a plurality of solenoid-operated key actuator units 4a respectively associated with the black and white keys 3c/3d, a frame structure 4b for the solenoid-operated key actuator units 4a and a controller (not shown) for selectively driving the solenoid-operated key actuator units 4a. A slot 3h is formed in the key bed 3b, and is laterally elongated under the rear end portions of the black and white keys 3c/3d. The solenoid-operated key actuator units 4a are supported by the frame structure 4b, and the frame structure 4b is partially inserted into the slot 3h so as to position the solenoid-operated key actuator units 4a under the rear end portions of the black and white keys 3c/3d, respectively.

The solenoid-operated key actuator units 4a make two rows, and are arranged in a staggered manner in the slot 3h. The two rows are spaced from each other in the fore-and-aft direction, and are leveled. For this reason, all of the plungers are short, and are durable.

The frame structure 4b has an inner shell 4c and outer shell 4d. The outer shell 4d is fixed to the key bed 3b by means of bolts 4e, and the solenoid-operated key actuator units 4a are attached to the inner shell 4c. The inner shell 4c is inserted into the outer shell 4d, and is supported by regulating bolts 4f and 4g screwed through the outer shell 4d. The solenoid-operated key actuator units 4a are aligned with the rear end portions of the black and white keys 3c/3d by using the regulating bolts 4f and 4g. The solenoid-operated key actuator units 4a are supported by the inner shell 4c, and the inner shell 4c is supported through the regulating bolts 4f/4g by the outer shell 4d which in tern is supported through the bolts 4e by the key bed 3b.

When the solenoid-operated key actuator unit is troubled, a repairing worker loosens the bolts 4e, and removes the frame structure 4b from the acoustic piano 3. The regulating bolts 4f/4g are loosened, and the inner shell 4c is separated from the outer shell 4d. Then, the repairing worker has access to the solenoid-operated key actuator units 4a, and replaces the broken solenoid-operated key actuator unit with a new one.

Thus, the automatic playing system 4 disclosed in Japanese Utility Model Publication of Unexamined Application No. 2-95394 is easily replaceable, because the frame structure 4b is downwardly taken away from the key bed 3b. However, trouble is encountered in the prior art automatic player piano in that the frame structure 4b is liable to fall down after the repairing work. The outer shell 4d is directly bolted to the key bed 3b, and the holes of the wooden key bed 3b tend to be enlarged during the loosening work. For this reason, the bolts 4e can not fixedly engage with the key bed 3b, and the frame structure 4b is liable to fall down due to insufficient fixing force. Moreover, when the holes are enlarged, the repairing worker is required to form new holes in both of the wooded key bed 3b and the outer shell 4d. However, the repairing work is usually carried out at user's home, and a special jig is not used for the repairing work. For this reason, the solenoid-operated key actuator units 4a are not exactly aligned with the keys 3c/3d.

It is therefore an important object of the present invention to provide an automatic player piano which is easy to repair without damage to a key bed.

To accomplish the object, the present invention proposes to insert a metallic bracket member between a wooden key bed and a supporting structure for solenoid-operated key actuator units.

In accordance with the present invention, there is provided an automatic player piano comprising: an acoustic piano including a keyboard having a plurality of turnable keys for generating acoustic piano sounds and provided over an upper surface of a wooden key bed formed with a slot under the plurality of turnable keys; and an automatic playing system including a bracket member formed of metal and fixed to a lower surface of the wooden key bed, a supporting structure bolted to the bracket member and partially inserted into the slot, and a plurality of solenoid-operated key actuator units supported by the supporting structure in a staggered manner on a virtual plane substantially in parallel to the lower surface of the wooden key bed and having respective plungers respectively aligned with the plurality of keys so as to push the plurality of keys when the plurality of solenoid-operated key actuator units are energized.

The features and advantages of the automatic player piano according to the present invention will be more clearly understood from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross sectional side view showing the prior art automatic player piano disclosed in Japanese Utility Model Publication of Unexamined Application No. 58-38195;

FIG. 2 is a cross sectional side view showing the prior art automatic player piano disclosed in Japanese Utility Model Publication of Unexamined Application No. 2-95394;

FIG. 3 is a cross sectional side view showing an automatic player piano according to the present invention;

FIG. 4 is a bottom view showing the arrangement of pedal mechanisms on a key bed of the automatic player piano;

FIG. 5 is a side view showing a key action mechanism, a hammer assembly and a damper mechanism incorporated in the automatic player piano;

FIG. 6 is a cross sectional view showing solenoid-operated key actuator units mounted on a frame structure;

FIG. 7 is a plan view showing a base plate of the frame structure;

FIG. 8A is a front view showing a center plate of the frame structure;

FIG. 8B is a plan view showing the center plate;

FIG. 9A is a side view showing a solenoid-operated key actuator unit incorporated in the automatic player piano;

FIG. 9B is a front view showing the solenoid-operated key actuator unit;

FIG. 10 is a plan view showing the layout of the solenoid-operated key actuator units;

FIG. 11A is a plan view showing a modification of the solenoid-operated key actuator unit;

FIG. 11B is a side view showing the modification;

FIG. 11C is a rear view showing the modification; and

FIG. 11D is a bottom view showing the modification.

Referring first to FIG. 3 of the drawings, an automatic player piano embodying the present invention largely comprises an acoustic piano 10, a recording system 20 and an automatic playing system 30. Description is hereinbelow made on the acoustic piano 10, the recording system 20 and the automatic playing system 30.

Structure of Acoustic Piano

The acoustic piano 10 includes a key board 11 placed on a key bed 12a, a plurality of key action mechanisms 13 supported by action brackets 14a on the key bed 12a, a plurality of hammer assemblies 15 turnably supported by the action brackets 14a, a plurality of sets of strings 16 stretched over the hammer assemblies 15 and a plurality of damper mechanisms 17 for absorbing vibrations of the strings 16.

A plurality of black keys 11a and a plurality of white keys 11b form the keyboard 11, and are turnable with respect to a balance rail 11c on a key frame 11d. The key bed 12a is attached to a leg block 12b, and the leg block 12b is supported by leg 12c. Though not shown in FIG. 3, the key bed 12a is further supported by other legs.

The acoustic piano 10 further comprises three pedal mechanisms 18a, 18b and 18c (see FIG. 4) respectively linked with a soft pedal, a damper pedal and a sostenuto pedal (not shown). When a player steps on the soft pedal, the soft pedal actuates the pedal mechanism for lessening the volume. The damper pedal causes the associated pedal link mechanism to hold off the damper heads (not shown) for prolonging the sounds, and the sostenuto pedal enables selected notes to be sustained independently.

A hottom boam 12d is attached to the lower surface of the key bed 12a, and a lyre block 12e is bolted to the hottom boam 12d. The lyre block 12e supports a lyre post 12f, and the soft pedal, the damper pedal and the sostenuto pedal are turnably supported by a lyre box (not shown) supported by the lyre post 12f. The pedal mechanisms are similar to those of a standard grand piano, and no further description is incorporated hereinbelow for the sake of simplicity.

FIG. 5 illustrates the key action mechanism 13, the hammer assembly 15 and the damper mechanism 17 when the associated key 11a/11b is in a rest position, i.e., state where no force is exerted on the associated key 11a/11b. A hammer shank rail 14b and a whippen rail 14c laterally extend, and are fixed to the action brackets 14. A whippen flange 13a is attached to the whippen rail 14c, and a whippen assembly 13b is turnably connected at one end thereof to the whippen flange 13a. A capstan screw 13c projects from the associated key 11a/11b, and is in contact with the whippen assembly 13b.

A jack 13d is shaped into an L-shaped configuration, and is turnably connected at the other end thereof to the whippen assembly 13b. A repetition lever flange 13e stands on the whippen assembly 13b at a central portion, and a repetition lever 13f is turnably supported by the repetition lever flange 13e. A through hole 13g is formed in one end portion of the repetition lever 13f, and the leading end portion 13j of the jack 13d is inserted into the through hole 13g. A repetition stop button 13h is fixed to the other end portion of the repetition lever 13f, and a repetition spring 13i is inserted between the whippen assembly 13b and the repetition lever 13f. The repetition spring 13i urges the repetition lever in the clockwise direction, and the repetition stop button 13h is pressed against the upper surface of the whippen assembly 13b. A jack button 13k projects from the jack 13d, and the repetition spring 13i urges the jack 13d so as to press the jack button against a jack stop spoon 13m implanted into the whippen assembly 13b.

A regulating rail 14d is fixed to the shank flange rail 14b, and a regulating button 13n is connected to the regulating rail 14d. The regulating button 13n is opposed to the toe 13o of the jack 13d, and the toe 13o is brought into contact with the regulating button 13n during the movement of the associated key 11a/11b.

A hammer shank flange 15a is fixed to the upper surface of the shank flange rail 14b, and a hammer shank 15b is turnably connected to the hammer shank flange 15a. A hammer wood 15c is fixed to the leading end portion of the hammer shank 15b, and holds a hammer top felt 15d. A back check 15e is supported by the rear end portion of the associated key 11a/11b, and the hammer wood 15c is brought into contact with the back check 15e after a rebound on the strings 16. A hammer roller 15f is rotatably supported by the hammer shank 15b, and is in contact with the upper surface of the repetition lever 13f around the through-hole 13g. A small gap takes place between the hammer roller 15f and the leading end portion 13j of the jack 13d inserted into the through-hole 13g.

A damper lever rail 14e laterally extends, and a damper lever flange 17a is fixed to the damper lever rail 14e. A damper lever 17b is turnably connected to the damper lever flange 17a, and a damper block 17c is turnably connected to the leading end portion of the damper lever 17b. The rear end portion of the associated key 11a/11b is brought into contact with the leading end portion of the damper lever 17b during the movement from the rest position to the end position. A damper wire 17d upwardly projects from the damper block 17c, and a damper head 17e is connected to the leading end of the damper wire 17d. The damper head 17e is held in contact with the associated set of strings 16, and prevents the associated set of strings from resonant vibrations. However, when the associated key 11a/11b is moved from the rest position to the end position, the rear end portion of the associated key 11a/11b causes the damper lever 17b to turn in the clockwise direction, and the damper lever 17b upwardly pushes the damper block 17c, the damper wire 17d and the damper head 17e so as to space the damper head 17e from the associated set of strings 16. As a result, the associated set of strings 16 becomes vibrative.

While the associated key 11a/11b is being moved from the rest position to the end position, the key action mechanism 13, the damper mechanism 17 and the hammer assembly 15 behave as follows.

The capstan button 13c pushes the whippen assembly 13b during the rotation of the associated key 11a/11b, and the whippen assembly 13b turns around the whippen flange 13a in the clockwise direction without a relative rotation between the whippen assembly 13b and the jack 13d. The jack 13d pushes the hammer roller 15f, and the hammer assembly 15 turns around the hammer shank flange 15a in the counter clockwise direction.

The rear end portion of the associated key 11a/11b is brought into contact with the damper lever 17b, and causes the damper lever 17b to turn around the damper lever flange 17a in the clockwise direction. The damper lever 17b pushes up the damper block 17c, the damper wire 17d and the damper head 17e, and the damper head 17e is spaced from the associated set of strings 16.

When the toe 13o is brought into contact with the regulating button 13n, the jack 13d turns around the whippen assembly 13b in the counter clockwise direction, and causes the hammer assembly 15 to escape therefrom. The hammer assembly 15 starts a free rotation, and strikes the associated set of strings 16. The damper head 17e has been already spaced from the set of strings 16, and the strings vibrate for generating a piano sound.

The hammer top felt 15d rebounds on the set of strings 16, and turns in the clockwise direction. The back check 15e receives the hammer wood 15c.

When the key 11a/11b is released, the capstan button 13c is downwardly moved, and the rear end position of the key 11a/11b allows the damper lever 17b to turn around the damper lever flange 17a in the counter clockwise direction. The whippen assembly 13b turns around the whippen flange 13a in the counter clockwise direction. The toe 13o is spaced from the regulating button 13n, and the leading end portion 13j is moved beneath the hammer roller 15f. Thus, the key action mechanism 13 and the hammer assembly 15 return to the initial positions shown in FIG. 5. The damper lever 17b downwardly moves the damper block 17c, the damper wire 17d and the damper head 17e, and the damper head 17e is brought into contact with the set of strings 16, again. As a result, the damper head 17e absorbs the vibrations of the strings 16, and extinguishes the piano sound.

Recording System

Turing back to FIG. 3 of the drawings, the recording system 20 includes a plurality of key sensors 21 respectively associated with the plurality of black and white keys 11a and 11b, a plurality of hammer sensors 22 respectively associated with the hammer assemblies 15 and a controlling unit 23. The controlling unit 23 is shared between the recording system 20 and the automatic playing system 30 as described hereinlater.

The key sensor 21 is implemented by a shutter plate 21a and photo-interrupters 21b, and monitors the associated key 11a/11b. The photo-interrupters 21b are arranged along the trajectory of the associated shutter plate 21a. The shutter plate 21a sequentially interrupts the optical beams of the photo-interrupters 21b during the movement from the rest position to the end position, and allows the photo-interrupters 21b to establish the optical beams during the movement from the end position to the rest position. The photo-interrupter changes the potential level of a key position signal between the photo-interruption and the photo-detection, and the controlling unit 23 periodically scans the photo-interrupters of the key sensors 21b to see whether or not any one of the black and white keys 11a/11b changes the status of the key sensors 21b. One of the photo-interrupters 21b gives a key-on timing for generating the piano sound to the controlling unit 23, and the controlling unit 23 calculates a key velocity from a time interval between the photo-interruptions.

The hammer sensors 22 are also implemented by shutter plates 22a respectively attached to the hammer shanks 15b and photo-interrupters, and the photo-interrupters 22b are arranged along the trajectories of the shutter plates 22a. The photo-interrupters 22b generate hammer position signals, and the controlling unit 23 periodically checks the photo-interrupters to see whether or not any one of the hammer position signals changes the potential level as similar to the key sensors 21.

The controlling unit 23 generates music data codes representative of the key/hammer motions during a performance, and the music data codes are stored in a suitable memory such as, for example, a floppy disk (not shown).

Automatic Playing System

The automatic playing system 30 includes a frame structure 30a, a plurality of solenoid-operated key actuator units 31 respectively associated with the black and white keys 11a/11b, a driver circuit mounted on a circuit board 30c for selectively energizing the solenoid-operated key actuators 31 and the controlling unit 23.

A slot 12g is formed in the key bed 12a, and is elongated in the lateral direction (see FIG. 4). The solenoid-operated key actuator units 31 and the circuit board 30c are mounted on the frame structure 30a, and are accommodated in the slot 12g.

As will be seen in FIG. 6, the frame structure 30a includes a base plate 30d and a center plate 30e. The base plate 30d is fixed to bracket members 30fa by means of bolts 30y, and the bracket members 30fa in turn are bolted to the lower surface of the key bed 12a by means of the bolts 30fb as described hereinbefore. The bracket members 30fa are formed of metal, and the bolt holes of the bracket members 30fa are hardly broken. The center plate 30e is formed of magnetic material such as, for example, soft iron, and is assembled with the base plate 30d in such a manner as to be upright from the base plate 30d.

The base plate 30d is shaped into a channel, and is elongated as long as the slot 12g. As shown in FIG. 7, the base plate 30d has wing portions 30g, a flat portion 30h and side wall portions 30i between the flat portion 30h and the wing portions 30g, and elongated bolt holes 30j are formed in the wing portions 30g at a constant pitch. Two lines of rectangular through-holes 30k are formed in the flat portion 30h along the side wall portions at the constant pitch, and wirings 30m pass through the rectangular through-holes (see FIG. 6). A line of other rectangular through-holes 30n is further formed in the flat portion at the constant pitch between the two lines of rectangular through-holes 30k, and the rectangular through-holes 30n are deviated from the rectangular through-holes 30k by a half of the constant pitch. The center plate 30e passes through the rectangular through-holes 30n, and is assembled with the base plate 30d. Pairs of through-holes 30o are further formed in the flat portion 30h between the line of rectangular through-holes 30n and one of the side wall portions 30i, and countersinks are formed for the through-holes 30o.

On the other hand, the center plate 30e has a vertical plate portion 30p and a plurality of projecting portions 30q projecting from the lower end of the vertical plate portion 30p at the constant pitch as shown in FIGS. 8A and 8B. Four lines 30r/30s/30t/30u of elongated holes 30v are formed in the vertical plate portion 30p. The two lines 30r/30s of elongated holes 30v and the other lines of elongated holes 30v are close to the upper end and the lower end of the vertical plate portion 30p. The elongated holes 30v of the lines 30r and 30u are respectively deviated from the elongated holes 30v of the lines 30s and 30t, and elongated holes 30v of the lines 30r and 30s are respectively aligned with the elongated holes 30v of the lines 30u and 30t. The pitch of the elongated holes 30v in each line 30r/30s/30t/30u is approximately equal to the pitch of the keys 11a/11b. Pairs of threaded holes 30w are formed in the projecting portions 30q, respectively.

The base plate 30d is assembled with the center plate 30e as follows. First, an assembling worker obliquely inserts the projecting portions 30q into the rectangular through-holes 30n, and turns the vertical plate portion 30p so as to bring the projecting portions 30q into contact with the flat portion 30h. Then, the vertical plate portion 30p is upright from the flat portion 30h of the base plate 30d, and the pairs of threaded holes 30w are respectively aligned with the pairs of through-holes 30o. Bolts 30x are screwed through the through-holes 30o into the threaded holes 30w, and the bolts press the projecting portions 30g against the flat portion 30h. Thus, the projecting portions 30q are fixed to the flat portion 30h, and the center plate 30e is assembled with the base plate 30d. The solenoid-operated key actuator units 31 are supported by the vertical plate portion 30p as will be described hereinlater.

After the assemblage of the base plate 30d and the center plate 30e, bolts 30y are screwed through the elongated holes 30j into threaded holes formed in the bracket members 30fa. The elongated holes 30j allow the assembling worker to regulate the relative position between the base plate 30d and the bracket members 30fa in the lateral direction, and the solenoid-operated key actuator units 31 are respectively placed beneath the associated black and white keys 11a/11b. The vertical plate portion 30p extends in the slot 12g in the lateral direction, and is substantially positioned on the center line of the slot 12g. The solenoid-operated key actuator units 31 are alternately provided on both sides of the vertical plate portion 30p, and, accordingly, staggered along the center line of the slot 12g.

Moreover, the assembling worker regulates the gap between the wing portions 30g and the bracket members 30fa and, accordingly, the gap between the solenoid-operated key actuator units 31 and the lower surfaces of the associated keys 11a/11b by rotating the bolts 30y. The flat portion 30h is as wide as the slot 12g, and the base plate 30d is moved into and out of the slot 12g during the regulating work. In detail, when the assembling worker rotates the bolts 30y in one direction, the distance between the wing portions 30g and the bracket members 30fa is decreased, and, accordingly, the base plate 30d lifts the solenoid-operated key actuators 31. On the other hand, if the bolts 30y are rotated in the other direction, the distance between the wing portions 30g and the bracket members 30fa is increased, and the base plate 30d spaces the solenoid-operated actuator units 31 from the associated keys 30b.

The frame structure 30a further includes guard members 30za screwed to the key bed 12a at intervals by means of bolts 30zb. As described hereinbelow, the base plate 30d is fixed to the bracket members 30fa by means of the bolts 30y. However, if the bolts 30y are undesirably loosened, the base plate 30d, the center plate 30e and the solenoid-operated key actuator units 31 are dropped from the key bed 12a. However, the guard members 30za receive the base plate 30d, and prevent the solenoid-operated key actuator units 31 from destruction.

The solenoid-operated key actuate or unit 31 is illustrated in detail in FIGS. 9A and 9B. The solenoid-operated key actuator unit 31 includes a yoke 31a, a solenoid 31b and a plunger 31c. The yoke 31a is formed of magnetic material, and a magnetic path is formed in the yoke 31a. The solenoid 31b is combined with the yoke 31a, and the plunger 31c is inserted into the solenoid 31b.

The yoke 31a is formed from two members 31d and 31e. The first member 31d is bent like a crank, and the second member 31e is shaped into a channel. The first member 31d is combined with the second member 31e by means of bolts 31f and 31g in such a manner that fin portions 31h project. Holes 31ia and 31ib are formed in the fin portions 31h, and through-holes 31j are formed in the first and second members 31d/31e in such a manner as to be aligned with each other.

A coil member 31k is wound on a cylindrical bobbin 31m, and the coil member 31k and the cylindrical bobbin 31m form in combination the solenoid 31b. The solenoid 31b is inserted into the recess formed in the yoke 31a, and the through-hole of the cylindrical bobbin 31m are aligned with the through-holes 31j. The cylindrical bobbin 31m is snugly received between the first member 31d and the second member 31e, and the bolts 31g do not allow the solenoid 31b to fall from the yoke 31a.

The plunger 31c is inserted into the through-holes 31j and the through-hole of the cylindrical bobbin 31m, and is slidable along the through-holes of the cylindrical bobbin 31m. The plunger 31c is formed of magnetic material, and a stopper 31n is attached to the upper end portion of the plunger 31c. The stopper 31n does not allow the plunger 31c to fall down from the cylindrical bobbin 31m.

The yokes 31a are bolted to the vertical plate portion 30p of the center plate 30e, and the solenoid-operated key actuator units 31 are alternately attached to both vertical surfaces of the vertical plate portion 30p. As a result, the solenoid-operated key actuator units 31 are arranged in a staggered manner in the lateral direction as shown in FIG. 10. The staggered arrangement allows the manufacturer to enlarge the solenoids 31b, and the solenoid-operated key actuator unit 31 exerts large force on the associated key 11a/11b. Moreover, the two rows of solenoid-operated key actuator units 31 are spaced in the fore-and-aft direction, and the plungers 31c are leveled. This results in improvement in durability.

As described hereinbefore, the elongated holes 30v are formed in the vertical plate portion 30p, and the elongated holes 30v of the outer lines 30r/30u and the elongated holes 30v of the inner lines 30s/30t are aligned with the outer through-holes 31ia and the inner through-holes 31ib, respectively. In order to attach the solenoid-operated key actuators 31f on one side of the vertical plate portion 30p are fixed to the center plate 30e, the outer through-holes 31ia are aligned with the elongated holes 30v of the outer lines 30r/30u, and regulates the solenoid-operated key actuators 31 to appropriate positions for the associated keys 11a/11b. Bolts 31p are screwed into the outer through-holes 31ia and the elongated holes 30v of the outer lines 30r/30u, and the solenoid-operated key actuator units 31 are fixed to the vertical surface of the vertical plate portion 30p. On the other hand, when the other solenoid-operated key actuator units 31 are fixed to the other vertical surface of the vertical plate portion 30p, the inner through-holes 31ib are aligned with the elongated holes 30v of the inner lines 30s/30t, and the solenoid-operated key actuator units 31 are regulated to appropriate positions for the associated keys 11a/11b. Bolts 31q are screwed into the inner through-holes 31ib and the elongated holes 30v of the inner lines 30s/30t. Thus, the solenoid-operated key actuator units 31 are arranged in the staggered manner on both vertical surfaces of the center plate 30e, and the elongated holes 30v allow an assembling worker to exactly align the plungers 31c with the keys 11a/11b. The vertical plate portion 30p is formed of the magnetic material, and allows the magnetic paths to pass therethrough.

The solenoids 31b are connected through the wirings 30m to the driver circuit mounted on the circuit board 30c accommodated in the space under the solenoid-operated key actuators 31 (see FIG. 6). For this reason, the wirings 30m are short, and the wiring arrangement is simple. The driver circuit is powered by an electric power source mounted on another rigid circuit board (not shown), and a controlling circuit is also provided on the rigid circuit board. The controlling circuit forms a part of the controlling unit 23, and instructs the driving circuit to selectively energize the solenoid 31b. The controlling circuit may be fabricated on the circuit board 30c together with the driving circuit.

In this instance, the bracket members 30fa serve as the bracket member, and the base plate 30d and the center plate 30e as a whole constitute the supporting structure.

Description is hereinbelow made on a repairing work on the assumption that one of the solenoid-operated key actuators is damaged at user's home. Firstly, the repairing worker loosens the bolts 30zb, and takes away the guard members 30za. The guard members 30zb are light, and the removal is easy.

After the driving circuit is disconnected from the controlling circuit, the repairing worker loosens the bolts 30y , and separates the base plate 30d from the bracket members 30fa. The base plate 30d and, accordingly, the solenoid-operated key actuator units 31 attached to the center plate 30e slowly fall out from the slot 12g of the key bed 12a. The keyboard 11 is never removed from the key bed 12a.

Subsequently, the repairing worker loosens the bolts 31p or 31q, and separates the yoke 31a of the damaged solenoid-operated key actuator unit from the center plate 30e. The stopper 31n is taken away, and the plunger 31c is removed. The repairing worker loosens the bolts 31g, and changes the damaged solenoid 31b to new one.

The plunger 31c is inserted into the new solenoid 31b, and the stopper 31n is attached to the plunger 31c, again. The repairing worker bolts the solenoid-operated key actuator unit 31 to the center plate 31e, and regulates the new solenoid-operated key actuator unit 31 to the appropriate position for the associated key 11a/11b.

The repairing worker lifts the base plate 30d, and screws the bolts 30y through the holes of the base plate 30d into the holes of the bracket members 30fa. The gap between the keys 11a/11b and the plungers 31c is regulated to 0.5 millimeter to 1 millimeter by using the bolts 30y.

The bracket members 30fa and the keyboard 11 have been never removed from the key bed 12a, and the relative position between the bracket members 30fa and the keyboard 11 is never changed. For this reason, when the base plate 30d is bolted to the bracket members 30fa, the plungers 31c are exactly aligned with the rear end portions of the associated keys 1a/11b, respectively. Finally, the guard members 30za are bolted to the key bed 12a, again.

As will be appreciated from the foregoing description, the bracket members 30fa are never taken away from the wooden key bed 12a, and the bolts 30fb are strongly engaged with the wooden key bed 12a. For this reason, the base plate 30d does not undesirably fall down due to insufficient engagement between the bolts 30fb and the wooden key bed 12a.

Moreover, the bracket members 30fa create a space under the solenoid-operated key actuator units 31, and the circuit board 30c is accommodated in the space. This results in the simple wiring arrangement, and makes the automatic playing system 30 compact.

The solenoid 31b is enlarged by virtue of the staggered arrangement of the solenoid-operated key actuator units 31, and the plungers 31c are hardly deformed.

The frame structure 30a and the solenoid-operated key actuator units 31 are accommodated in the slot 12g, and the automatic playing system 30 does not interfere with the pedal mechanisms 18a to 18c. Therefore, a standard acoustic piano is retrofitted to the automatic player piano.

The magnetic path is formed through the center plate 30e and the yoke 31a. In other words, the center plate 30e serves as part of the yoke 31a, and decreases the total weight of the frame structure 30a and the solenoid-operated key actuator units 31.

The automatic player piano behaves as follows. When a player instructs the recording system 20 to record a performance on the keyboard 11, the key sensors 21 and the hammer sensors 22 cooperate with one another, and the controlling unit 23 determine the motions of depressed keys 11a/11b and the associated hammer assemblies 15. The key/hammer motions are described in music data codes, and are stored in a suitable non-volatile memory such as a floppy disk.

When the player instructs the automatic playing system 30 to playback the performance, the controlling unit 23 reads out the music data codes, and instructs the driving circuit to selectively energize the solenoids 31b of the solenoid-operated key actuator units 31.

If the controlling unit 23 instructs the driving circuit to energize the solenoid-operated key actuator unit associated with the key 11a shown in FIG. 6, the driving circuit supplies the current through the wiring 30m to the coil member 31k, and the coil member 31k generates magnetic field. The yoke 31a and the vertical plate member 30p serve as the magnetic path, and the electromagnetic force is exerted on the plunger 31c. Then, the plunger 31c upwardly projects from the solenoid 31b, and pushes up the rear end portion of the associated key 11a.

The key 11a turns as if a player depresses it, and actuates the key action mechanism 13. The key action mechanism 13 allows the hammer assembly 15 to escape therefrom, and the hammer assembly 15 strikes the set of strings 16 for generating the piano sound.

After the strike with the hammer assembly, the driving circuit stops the current, and the plunger 31c is retracted into the solenoid 31b.

Although a particular embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention.

FIGS. 11A to 11D illustrate a modification of the solenoid-operated key actuator unit. The modification is only different in the structure of yoke 50 from the solenoid-operated key actuator unit 31. For this reason, description is focused on the structure of the yoke 50, and other components are labeled with the same references used for the solenoid-operated key actuator unit 31. The yoke 50 also includes a first member 50a and the second member 50b. The lower end portion 50c of the first member 50a and the corresponding portion 50d of the second member 50b are tapered as will be seen in FIG. 11C. The tapered portions 50c and 50d decrease the total weight of the yoke 50, and allow a tool to reach the bolts 31p/31q. Through-hole 50e is formed in the lower end portion 50c, and a bolt 50 is screwed through the through-hole 50e into the corresponding portion 50d. The first member 50a and the second member 50b are combined with each other by means of the bolts 31g on the diagonal line on the upper portion 50f of the first member 50a. The bolts 31g sandwich the solenoid 31b between the first and second members 50a/50b without loss of balance. The fin portion 50g of the second member 50b is partially cut away, and a repairing worker makes the tool easily reach the bolts 31p/31q.

The four lines of elongated holes 30v may be replaced with two pairs of rails attached to the vertical plate portion 30p, and the solenoid-operated key actuator units 31 are regulated to the appropriate positions by using the rails.

The yokes 31a may be slidably supported in the up-and-down direction by the center plate 31e, and bolts individually move the yokes so as to regulate the gaps between the plungers and the associated keys.

The acoustic piano may be an upright piano, and hammer stoppers may be provided for preventing the strings from the hammers.