Patent GB-1267205-A (GB)
IPC: G08B5/22
Filed: 1969-01-23
Abstract: 1,267,205. Control of motors. BECKETT, LAYCOCK & WATKINSON Ltd. 28 Jan., 1970 [23 Jan., 1969], No. 4014/69. Heading H2J. [Also in Division G5] A scroll or blind (Fig. 2) is driven by electric motors past a display window (not shown) in order to display selectively items such as X, Y and Z. An electric pulse transmitter (not shown) operated by conducting strips 19, 20, 21 completing a circuit at wiper contacts 22 as the blind moves, sends pulses to a counter (not shown), the counter providing an operator with a visual advance warning of the arrival of a selected display item at the window. When the operator moves the switch 10 to contact 11, a first positive feed is supplied to a relay coil R2, energizing it to cause switches R2/1, R2/2, R2/3 and R2/5 to-close, and switch R2/4 to open. This provides:- (1) A positive feed to the motors via line 15 and switches R2/3 and R2/5 (a permanent negative feed is provided by line 16). (2) A positive feed to the counter via line 17 and switches R3/4 and R2/5. (3) Negative feed via switch R2/2 and positive feed via switch R2/5 to a forward driving clutch CLF to set the blind in motion. (4) An alternative positive feed to coil R2 via switch R2/5, so that, if switch 10 is now returned to its neutral position, thus cutting off the first positive feedto the coil R2, the coil R2 remains energized and the blind continues to move. Further conducting strips 13 are provided on the blind, and when these pass wiper contacts 14, a circuit is completed which energizes relay coil R1 which opens switch R1/1 and cuts off the alternative positive feed to the coil R2 provided as in (4) above. This means that, if the switch 10 has been returned to its neutral position as described, the coil R2 becomes deenergized and the blind stops moving. However, if the switch 10 has been held in its contacting position throughout, the first positive feed to coil R2 is uninterrupted and the blind continues to move. When strips 13 have passed, the contacts 14 switch R1/1 closes and the alternative feed to R2 is restored. Moving switch 10 to contact 12 moves the blind in the opposite direction by energization of coil R3 and reverse clutch CLR and operation of switches R3/1, R3/2, R3/3, R3/4 and R3/5 in a similar manner to that described above. The counter may be in the form of an indicator which is a miniature replica moving blind, synchronized with the original, moving intermittently under the action of the electric pulses past a display aperture in sight of the operator. Because of the relative positions of the strips 19, 20, 21, and the strips 13, the indicator displays the replica of an item in advance of the item itself appearing at the display window. The operator therefore has merely to hold the switch 10 in the forward or reverse position until the replica of the item he desires to display appears at the indicator aperture, and then return the switch to its neutral position, ensuring that the blind will stop when the strip 13 on the desired display item passes the contacts 14. This basic system may be used, in a similar manner, to synchronize the movement of several similar display blinds, for instance, the route indicators at the front and back of a bus, control being achieved by the use of one switch 10 only. Several alternative arrangements are possible on the display scroll to perform the same funetion as the strip and wiper contact device.