Patent GB-266930-A (GB)
Title: Improvements in and relating to automatic musical instruments and expression controlling means therefor
Filed: 1926-04-19
Abstract: 266,930. Imray, O. Y., (American Piano Co.). April 19, 1926. Actions, pneumatic ; exhausting air; expression-controlling.-A tension-regulating means, variable incrementally or progressively, the latter at two speeds, for expression-controlling, comprises flexible means having substantially no inertia, such as a diaphragm acting as a valve which is exposed on different areas of one side to the high exhaust of the main suction and the regulated exhaust supplied to the action, and on the other side to a controlled exhaust variable by varying the admission of air. The striking- pneumatics 1 and their secondary valves 4 are arranged on opposite sides of a board 8 having diagonal passages 9 connecting the valves with the treble and bass suction-chests 13 separated by a partition 12. The regulating-diaphragm 22 is mounted on the action-chest and controls the passage between regulated exhaust in the chest 13 and high exhaust in a chamber 15 connected to the source of suction 17, the diaphragm peeling away from, or closing up to, a perforated plate 20 in its action. The controlled-exhaust chamber 25 is connected at 26, with semi-permanent adjustment at 27, to the high exhaust and at 28 to air-admission means. These means comprise atmosphere ports 38 - - 38<b> which are connected by passages 36, 32 with a chamber 29 and are opened against the action of springs 40 - - 40b by suction when valves 44 are in their lower position. To vary the controlled exhaust at 25, and therefore the regulated exhaust at 13, by a definite increment, one or more of the atmosphere ports 38 - - - 38<b>, which are of different sizes, are closed from tracker-bar apertures 54 - - - 54b operating the valves 44. A valve 44 once raised is preferably maintained in this position although the tracker-duct is immediately closed, through the atmosphere admitted by the valve 44 also reaching, by a passage 61, 86<1>, 63, the diaphragm 51. Such maintenance of any one or more of the valves 44 in raised position is cancelled so as to open the ports 38 - - - 38<b>, by opening a single tracker-duct 81, lifting a valve 73 to admit atmosphere to diaphragms 88 to close the passages 86'; but opening a trackerduct 54 simultaneously with the duct 81 will maintain the valve 44 raised owing to the passage 63 being constricted by a bleed 62. To assist the regulated exhaust at 13 to change rapidly from relatively high to relatively low exhaust, when port 38 is opened the suction also opens, by a duct 95, a port 91 admitting atmosphere to the regulated exhaust. To obtain a continuous crescendo or diminuendo, a needle-valve 35 is moved by the gradual exhaustion or expansion of a bellows 105 on opening or closing a trackerduct 122 to raise or lower a valve 114, the speed at which the needle-valve moves being variable by adjustment of a screw 123. A more rapid crescendo or diminuendo is obtained by opening a bye-pass 124 having an adjusting screw 126 causing less constriction than the screw 123. The bye-pass is opened by opening a trackerduct 138 operating a valve 129 to admit suction to a diaphragm-valve 125, and tracker-duct 122 is then simultaneously opened or closed to operate the valve 114.