Patent GB-838621-A (GB)
Title: Improvements relating to automatic control apparatus especially adapted for controlling automatic weighing machines
Inventor: BOOTH RICHARD HERBERT
IPC: G01G19/38
Filed: 1955-06-16
Abstract: 838,621. Electric calculating apparatus. ELECTRIC & MUSICAL INDUSTRIES Ltd. June 18, 1956 [June 16, 1955], No. 17390/55. Class 106 (1). The device described comprises three uniselectors U3, U4, U5, Fig. 1, which totalize up to four 3-digit decimal numbers read from a punched tape by contacts Q1 to Q5, together with a uniselector U2 which distributes the individual decimal digits read from the tape to the uni-selectors U3, U4, U5, and a uni-selector U1 which recedes each digit read from the tape after it has been temporarily stored on relays A, B, C and D. As described, the device also causes the resistance between two terminals P8 and P9 to vary linearly with the total registered on uni-selectors U3, U4, U5 and forms part of an automatic weighing-machine for preparing a mixture of specified amounts of up to four substances, the terminals P8 and P9 being connected to a bridge circuit also controlled by the weight actually on the scale pan for controlling a servo system feeding the several substances to the scale pan. With all the uni-selectors reset to their " ready " position (that is, all in their " zero position except uni-selector U2 which is in its one " position and being achieved by a " ready " instruction from the tape), the first digit of the first number is read from the tape and registered in the binary scale on relays A, B, C and D (the number in the square representing each relay indicating its number of contacts) causing, providing it is not zero, uni-selector U1 to advance to its corresponding position, stepping coil L1 being energized via at least one of contacts A/2, B/2, C/2, and D/2, contact arms CA35, CA45, CA52 and the lower contact H/3, and also causing relay H to be energized via normally-closed contact F/2, (contacts shaded black are closed when a relay is not energized and unshaded contacts are closed when a relay is energized). As uniselector U1 advances from its zero position contact arm CA16 energizes relay F, causing tape feed to stop (had the first digit been zero uniselector U1 would not have advanced, relay F would not have been energized and the next digit would have been read), and also since relay H is energized each single-step advance of uniselector U1 causes hundreds uni-selector U5 to advance one step (contact arm CA11, transferred contact H/3; contact arm CA21 and coil L5) until uni-selector U1 reaches the position specified by the number read from the tape. When this happens relay H is de-energized, breaking the connection via its contact H/3 to uni-selector U5, but uni-selector U1 continues advancing, by virtue of the connection from contact arm CA11 via normally closed contact H/3 to coil L1, until it reaches its zero position, whereupon contact arm CA16 causes relay F to be de-energized, which in turn energizes the tape feed clutch, and the next digit, the tens digit of the first number, is read and entered in a similar manner. As uni-selector U1 passes through position 11 to zero, uni-selector U2 is advanced one step to its third position by the connection then made from contact arm CA17 to coil L2, so that the next digit is entered into the tens uni-selector U4. The third digit of the first number-the units denomination-is entered in a similar manner into uni-selector U3. The next digit read from the tape will represent the instruction " weigh " and its effect will be to advance uni-selector U2 to its position 5, causing contact arm CA25 to apply a signal to terminal P1 which causes the weighing of the first ingredient to take place. When this weighing is completed the weighing-machine applies a signal to terminal P7 which causes tape feeding to commence and advances uni-selector U2 to its position 6 so that the next digit read from the tape is entered into the hundreds uniselector U5. The above sequence of events is repeated for the following number read from the tape. Carry from the units uni-selector U3 to the tens uni-selector U4 is effected by contact arms CA36 and CA32. When units uni-selector U3 reaches its position 10 a signal is applied by contact at CA36 to coil L4 advancing the tens uni-selector one step, and at the same time the circuit from contact arm CA15 via contact arm CA35 to coil L1 is broken so that uni-selector U1 stops advancing. A circuit is also complete via contact arm CA32 to coil L3 of the units uni-selector U3 which causes this arm-selector to advance two steps to its zero position, whereupon the circuit to coil L1 via contact arms CA35 is complete and uni-selector U1 continues advancing (the extra two advance steps given to units uni-selector U3 being necessary because each of its banks of contacts has 12 contacts and not 10).