Patent GB-889719-A (GB)
Title: Improvements relating to electronic counters
Inventor: COADY-FARLEY JAMES TRAIN
IPC: H03M1/00
Filed: 1958-06-27
Abstract: 889,719. Electric selective signalling systems. FERRANTI Ltd. June 26, 1959 [June 27, 1958], No. 20613/58. Class 40 (1). Apparatus which may be applied to the control of a machine tool comprises means for presetting a number in an electronic counter including for each denomination a presettable selector having a digit contact connected for distinctive energization in accordance with the number in the counter. As described, a servo actuator 11 is arranged to drive a machine tool (not shown) along a co-ordinate axis 12, the position of the tool being represented on a binary counter 13. Presettable selectors SOS3 are provided for four decimal denominations, the contacts 0-9 of each selector being connected to four arrays AO-A3 of ten output leads from a binary-decimal converter 14, the arrangement being such that one lead in each denomination is marked in accordance with the value registered in the counter 13. The contacts of each selector are engaged by three movable wipers 15, 16, 17, the wiper 16 being set to engage the selected contact, and the wipers 15, 17 engaging respectively the contacts of lower and higher significance. The wipers 15 are connected to relays RO-R3 and the wipers 16 to relays QO-Q3. The relays control contacts qO-q3, rO-r3 arrayed in the energizing circuits of a relay 21 controlling the direction of operation of the servo actuator 11 and an arresting relay 22. In operation, the value desired to be preset in the counter 13 is set up on the selector switches SO-S3. The arrangement of contacts qO-q3, r0-r3 is such that the highest significant different digit between the actual value in the counter and the desired value is effective if the selected digit is higher than the digit registered, to energize over the corresponding " r " contact and the closed " q " contacts of higher order (if any), the relay 21 thereby maintaining an additive drive to the machine tool and a corresponding additive supply of pulses to the counter 13. If the highest significant different digit is such that the selected digit is lower than the digit registered, the corresponding " R " relay is not energized and the relay 21 is also not energized so that its changeover contact 23 ensures a supply of negative potential to drive the servo actuator 11, machine tool, and counter 13 negatively or subtractively. When the registered digit equals the selected digit, the corresponding " Q " relay is energized and control of the actuator 11 passes to the next lowest different digit. When all the registered digits equal all the selected digits, all contacts qO-q3 are closed to complete a circuit for the relay 22 whose contact 24 opens to stop the operation of the actuator 11.  Modifications.-The wipers 17 may be dispensed with where the converter 14 does not require closed circuits in the unenergized leads. The wipers 15 may be on the other side of the wipers 16. The relay 21 may be replaced by two relays adapted for respective energization when the selected digit is greater than or less than the corresponding registered digit, a second relay R<SP>1</SP> " being provided for each of the wipers 17 (Fig. 12, not shown). The converter 14 may be dispensed with where the counter 13 is decimal instead of binary. The " Q " and " R " relays and associated contacts may be replaced by junction-type transistors (Figs. 13 and 14, not shown). In a further modification, Fig. 15, the selectors are in the form of a relay system. As shown, for the " nth " power each digit 0-9 is provided with arelay OPn-9Pn arranged to be energized over an appropriate one of leads 31. The output leads from the counter are arranged in an array An to be connected to the movable contacts of change-over contacts OPn3-9Pn3, the associated make contact being connected to a relay Qn and the associated break contact to a relay Rn. In operation, the selector is preset to the required digit, say 2, by momentarily energizing the lead 31 of the relay 2Pn which locks over its contact 2Pn1. The contacts OPn2 -9Pn2 of lower significance than the selected digit are thus connected to the relay Rn and the make contacts of the change-over set 2Pn3 thus connect the lead " 2 " of the array An to the relay Qn. The system of connections is now similar to that of Fig. 1 and subsequent operation is similar to that described. In the modification of Fig. 16 (not shown), provision is made for a single wiper only to be used instead of a combination of a single wiper and at least one multiple wiper, and transistors are employed instead of the " Q " and " R " relays.