GB1361023A - Switching devices - Google Patents

Abstract

1361023 Positioning apparatus GAF CORP 29 June 1971 [30 June 1970] 30482/71 Heading G4H [Also in Division H1] A switching device comprises a contact finger 60b wiping over a common contact 38 and a contact finger 60a wiping over ten "tens" contacts 40, 41 ... 49, and ten contact fingers 62a, 62b ... 62j, simultaneously wiping over ten "units" contacts 40-0, 41-1, 42-2 ... 49-9 integral with the "tens" contacts 40, 41 ... 49. Contact fingers 62a, 626 ... 62j are so arranged with respect to contact finger 60a that a finger 60a wipes over the length of one "tens" contact, each of the contact fingers 62a, 62b ... 62j wipes over one "units" contact, thus as the contact fingers are rotated, ten "units" contacts are engaged for each "tens" contact engaged. In general, the number of contact fingers 62a, 62b ... 62j, when multiplied by the number of "units" contacts equals the product often times the number of "tens" contacts. In the embodiment shown in Figs. 2 and 5 there are 100 contact combinations but in a second embodiment, Fig. 6 (not shown), two systems are combined so that one system gives 100 contact combinations and the other gives 80 contact combinations. The switching device is intended to select a particular slide from a rotary slide projector carrying 100 (or in the case of the second embodiment, 100 or 80) slides. Ten resistors 65a ... 65j are connected as shown in Fig. 5 and as the contact fingers 60a and 62a, 62b ... 62j wipe over the contacts, 100 different resistance combinations are made, the combination shown in Fig. 5 being combination 93, i.e. finger 60a is on contact 49 and finger 62e is on contact 43 (in actual fact it would be on 43-3 which is integral with contact 43) so that 100 resistance combinations are obtained with ten resistors. The resistors 65a ... 65j are connected to resistor banks 67, 68 in the slide projector which are varied as the magazine rotates. The magazine is driven by a motor and when this is switched on by a separate switch (not shown) and the switching device is rotated, the motor rotates the magazine until the resistance value in the projector is equal to the resistance value of the switch at which position the motor stops and the selected slide is opposite the projection gate. The contacts are rotated by a knob (13), Fig. 1 (not shown), or inched round one at a time by a button (23) (forward) or (24) (reverse) which when depressed cam pawls into engagement with a toothed wheel to which the moving contacts are joined. Detent button (20), Fig. 4 (not shown), retains the wheel in position. Simple spring contact (25), when depressed by a button (22), Fig. 1, actuates the circuit.