Patent GB-1033220-A (GB)
Title: Electronic musical instrument switch means
IPC: H01H21/26
Filed: 1963-06-26
Abstract: 1,033,220. Retractive switches; switches held set and freed mechanically. WURLITZER CO. June 26, 1963 [June 26, 1962], No. 25438/63. Heading H2B. [Also in Division G5] In an electronic organ depression of a pedal closes a first switch appropriate to the note to be played together with a second switch, common to all pedals, which allows the note to be heard and on release of the pedal the second switch opens to mute the note but the first switch remains closed and is opened only when a different pedal is depressed. This arrangement, whilst allowing repetition of any note, prevents the simultaneous sounding of any two notes which, in the case of the low frequencies of pedal notes, could give rise to objectionable beats. The invention, however, although described in connection with pedal notes, is also applicable to notes played on the manuals. Fig. 2 (not shown) depicts the general scheme in which tones from generator 34 are fed via pedaloperated switches 46 and amplifier 50 to dividers 52, 54 which are rendered operative by the application of B+ via switch 56. The latter switch, which is common to all the pedals, is closed simultaneously with the selected pedal switch 46 and the note sounds via filters 38 and audio devices 40, 42 with an attack (and decay) determined by capacitor 64 and the discharge resistors 66, 70 selected by manual mounted stop switches 68, 72. On release of the depressed pedal the switch 56 opens and the note decays but the switch 46 appropriate to such pedal remains closed and'is not opened until a different pedal is depressed such action again closing switch 56 together with the newly selected switch 46. In one embodiment the latter switches, Fig. 7 (also Figs. 3 to 6, not shown) are operated by an actuator 138 (Fig. 6) which is pivoted at 142 to a bracket 90 (Fig. 5) screwed to each pedal 26 and further linked to the bracket by an overcentre spring 136 (Fig. 4) such that when a pedal is depressed the actuator is tripped over to close the contacts 46 (Fig. 8, not shown) and remains in this position when the pedal is subsequently released (Fig. 9, not shown). The downward movement of the actuator is decelerated by a resilient pad 98 (e.g. of polyurethane) and finally stopped by a pad 96 (e.g. of neoprene) of lesser height and of lesser compliance and the upward movement is cushioned by a neoprene pad 112. When a pedal is depressed, a bail 176, pivoted at 174 and extending over the full length of the pedal board is forced downwardly against a plurality of leaf springs 186 by a flange 108 formed on bracket 90 so that the bail acts on the heal 146 of any actuator already operated by a pedal to cause it to trip back to the position in which contacts 46 are opened (Fig. 10, not shown). The single switch 56 common to all notes is closed and opened by a bracket 188 (Figs. 3 and 8) secured to the bail for each pedal depression and release respectively. In a second embodiment each switch 46 comprises a pair of contacts 230b (Fig. 12, not shown), carried by each pedal 26b the contacts being shorted when the pedal is depressed by a conductive plate 236b carried by a "butterfly" member 232b loosely pivoted at 242 so that, when the pedal is released, the " butterfly " is carried upwardly to maintain the shorting of contacts 230b by virtue of the frictional grip between the contacts and plate 236b which grip may be enhanced by the provision of a projection 244 on the member 222b carrying contacts 230b so that the " butterfly " is gripped between the latter and the projection. When a different pedal is depressed the bight 210b of a bail device 208b (also Fig. 11, not shown) is lowered against the tension of spring 212b and operates to depress any previously raised butterfly to remove the shorting of contacts 230b and so open a switch 46. Every downward movement of the bight 210b operates a single switch 56 (Fig. 11, not shown). In another embodiment each switch 46 comprises a pair of shorting arms 254 (Fig. 13) carried by a " butterfly " 232c pivoted on a rod 242c the arms operating, when a member 222c (also pivoted on rod 242c) carrying three conductive patches 258, 260, 262 is pulled downwardly by brackets 256 attached to the pedals, to change-over the short between patches 258, 262 to a short between patches 258, 260. On release of the pedal the butterfly is frictionally retained and rises with member 222c to maintain the short. On depression of another pedal a bail 232e pressed downwardly by the member 222c associated with such pedal operates to depress any raised butterfly and so change-over the shorting action to the initial position. As in the previous embodiment switch 56 (not shown) is operated by each downward movement of the bail. Fig. 14 (not shown) is a further embodiment in which the " butterfly " 232d attached to a member 268 pivoted on a rod 242a has already been " picked-up " (after depression and release of pedal 26d) by members 226c also pivoted on rod 242a to change-over the short produced by arms 254 from conductive patches 258d and 262d to patches 258d and 260d. The " pick-up " of the " butterfly " is partly frictional and partly aided by a detent mechanism comprising a spring 276 carried by member 226e co-operating with a projection 278 formed in member 268, the spring lying to the left of the projection when the " butterfly " is down. On depression of any other pedal a bail member 176d pivoted about a rod 174d and comprising a comb-like configuration of radial arms 282 is carried downwards to lower any raised " butterfly " by engagement of a stud 280 with the appropriate arm 282. As before, the switch 56 (not shown) is operated by movement of the bail. In all embodiments felt pads are employed to reduce operational noise, e.g. 148, 182, 184 (Fig. 7), 238 (Fig. 12) and 108d, 238d, 264 and 274 (Fig. 14).