Patent GB-191124372-A (GB)
Title: Improvements in or relating to Automatic Musical Instruments.
Inventor: BOULT ALFRED JULIUS
Filed: 1911-11-02
Granted: 1912-08-01
Abstract: 24,372. Boult, A. J., [Mills, H. S.]. Nov. 2. Pianofort:es without keyboards; actions; expression, controlling; winding - mechanism.-In an electro-magnetic player-piano, which is particularly adapted for accompanying an automatic violin, two electro-magnets, connected in parallel and having coils of different resistance, are provided for each note. The attraction of an armature, which is common to the electromagnets and comprises two relatively-movable parts, causes the circuit of the low-resistance coil to be broken at a time determined by the position of a bar controlled through electromagnetic means from the tune - sheet. The loudness of the notes can thus be controlled, electrical energy is economized, and sparking at the tracker-bar is reduced. Means are also provided for operating the dampers by a similar electro-magnetic device, and for locking them in position until released by another electromagnet. The piano actions are arranged in two sets one above the other, alternate strings being sounded by the hammers of the same set of actions. The player actions are also arranged in two sets, each comprising two rows of magnets. The armatures of the magnets 9, 10 have extensions 34 provided with adjustable weights and also with buttons for operating the piano stickers either directly or through vertical rods. Adjustable uprights are screwed on to the extensions 34 and secured in position by nuts. The magnets 9, 10 for a single note are mounted upon a bracket 24 carried by a beam 25. The coil of the magnet 9 is of low resistance and is connected to a terminal 33 on a yoke 27, which is pivoted at 28 to the bracket 24 and insulated therefrom. The other end of the coil is connected to a brass strip mounted on an insulating base which forms one side of a rectangular conduit containing the various wires. The coil 10 is connected to the brass strip and the iron framework. The armature 21 is pivotally mounted at 23 on the bracket 24 and is normally inside the yoke 27, so that the circuit of the magnet 9 is completed through platinum contacts 31, 26 on the yoke 27 and armature 21 respectively. A rubber - covered bar 15, which can be raised and lowered by electro-magnetic means controlled by the tunesheet, is adapted to co-operate with an extension 32 carried by the yoke 27. The armature 21 is bent near its centre, as shown at 22, to increase the tractive force of the magnets. In operation, if the circuits of the magnets 9, 10 are completed by a brush making contact with a roller, the armature 21 and yoke 27 are simultaneously attracted. The extension 32 of the yoke 27 then engages the bar 15 so that the motion of the yoke is stopped. The movement of the armature 21 continues, however, so that the contacts 26, 31 separate and the circuit of the magnet 9 is broken at a stage determined by the position of the bar 15. The loudness of the note sounded therefore depends upon the position of this bar. Several independently-controlled bars 15 may be provided. The bars 15 for two sets of actions are mounted upon pivoted arms which are coupled together and are operated through the rod 20 by the device shown in Fig. 3<a>. The lever 44 is mounted upon a bracket 43 and carries the armatures of the electro-magnets 53, 54. A spring 45 normally holds the lever 44 in the horizontal position, and its connexion with the rod 20 can be adjusted by nuts 20<a>, against one of which it is pressed by a spring 20<b>. By the energization of the magnets, the lever 44 is tilted in one direction or the other, so raising or lowering the bar 15. The lever 44 carries a rack 47 which drives a fan 52 for preventing abrupt movements. The device for operating the damper-rod 67 is shown in Fig. 6, and comprises high and low resistance magnets 57, 56 connected in parallel. The attraction of the armature 63 breaks the circuit of the magnet 56 which is normally completed through the contact-arm 66. A stop 65 limits the downward movement of the arm 66. A catch 62 holds the armature 63 depressed until the magnets 58 are energized. The armature 59 is then attracted against the action of a spring 61 to release the armature 63, which thereupon rises to its normal position owing to the action of the springs acting on the dampers. The tunesheet is driven by an electromotor, the circuit of which may be closed or opened by energizing electro-magnets controlled by push-buttons. At the completion of a tune, the motor circuit is opened by the energization of an electromagnet, controlled by the tune-sheet.