Patent GB-1386338-A (GB)
Title: Coin control circuits for vending machines
IPC: G07F5/22
Filed: 1972-10-13
Abstract: 1386338 Vending machine control circuit H R ELECTRONICS CO 13 Oct 1972 [6 Dec 1971] 47305/72 Heading G4V In a vending machine control circuit a coin switch, such as 14, is associated with a pair of cross-coupled NAND gates 26, 28 that function to provide a single pulse on line 38 on the passage of a coin and eliminate false entries to an accumulator 80 caused by faulty switch operation. The embodiment shown accepts coins of three denominations, i.e. nickels, dimes and quarters and comprises three coin switches 14, 16 and 18, nickels operating only switch 14, dimes switches 14, 16 sequentially and quarters all three switches sequentially. The " dime " switch 16 is also associated with a pair of crosscoupled NAND gates 40, 44 the former of which also receives an input from gate 26 to ensure that a dime produces two distinct pulses from NAND gate 42, this gate being connected to the binary counter 80. The circuit may be set to vend at 15 c., 20 c. or 25 c. by switches 76, 78 which as shown are set for a 15 c. vend and in this condition, after the establishment of 10 c. credit, three of the inputs to NAND gate 91 will be 1 the next pulse from gate 42 therefore causing the output of gate 91 go to 0 and hence energizing vend circuit 70 via NAND gates 66, 68 and resetting the stages of accumulator 80 via reset circuit 98. If a dime were the last coin inserted a further pulse will be produced by dime switch 16 and gates 40, 44 and this is effective via gates 42, 60 to set all the stages of the accumulator and accordingly energize a payback control circuit 118 to dispense a nickel in change. During operation of the changemaker switch 20 is operated to reset the accumulator. If a quarter is inserted for a 15 c. purchase coin switches 14, 16 and 18 are operated sequentially the latter energizing vend circuit 70 via gates 66, 68 and also setting stages 84, 86 of the accumulator via switch contact 78b. The input conditions of gate 114 are thus met and payback circuit 118 is energized, but since stage 82 of the accumulator is in its reset state two operations of switch 20 are required before the accumulator is reset and the payback circuit deenergized. For a 20 c. vend contacts 76a, 76b are switched over and vend circuit 70 is then not energized via gates 91, 66, 68 until the reception of the fourth pulse from gate 42. If a quarter is inserted the vend circuit is energized and since contact 76b is now closed all three stages of the accumulator are set and only one nickel is paid in change. For a 25 c. vend contacts 76a, 76b are as shown and contacts 78a, 78b switched over, the vend circuit is energized via gate 64 on the reception of the fifth pulse from gate 42 or on operation of the quarter switch 18. Various safety features are provided including lines 142, 144 from coin switches 16, 14 to payback control gate 114 to prevent payback in the event of a jammed switch, circuit 128, 130 for resetting the accumulator as power to the circuit is switched on and circuit 132 for prolonging operation of vend control gate 68. In another embodiment (Fig. 2, not shown) change of either a nickel or dime is paid back according to whether only one of or both of payback control circuits (334),(352) are energized.