Escrow credit controllers and method of operation thereof

A method of operating an escrow credit controller for vending machines for providing vend units to customers and which has a vend path within the controlled vending machine capable of serially processing a plurality of vent units simultaneously, the controller being capable of accumulating total value added by a customer through one of several value-accepting peripheral devices, enables the controlled vending machine based on the value accumulated, removes value from the accumulated total based upon operation of the vending machine, and disables the vending machine, the controller having value-added input means for accepting signals from the value-accepting peripheral equipment indicative of value accepted by said peripherals, value-return switch input means for accepting a command from the customer to return the remaining value of the accumulated total value, value-return output means for commanding a value-emitting peripheral device to supply the customer with a specific amount of value, enabling output means for permitting the vending machine to perform its vending function, and vended signal input means for accepting signals from the vending machine indicating that the vending machine has supplied the customer with a vend unit, in which the improvement comprises a method of operation, comprising, in the following specified sequence:

• a pre-operation step, an initialization operation, a primary operating loop and a second value-return loop;
• a. the pre-operation step comprising setting a trigger amount which is at least equal to one more than the number of vend units in the vend path, times the price of one vend unit;
• b. the initialization operation comprising setting the accumulated total to zero;
• c. the primary operating loop comprising the steps of:
• 1. examining the value-added input means to determine if value has been added by a customer;
• if value has been added, proceeding with step c.2, if not, proceeding with step c.5;
• 2. adding the value added to the accumulated total value;
• 3. comparing the accumulated total to the trigger amount;
• if the accumulated total is at least equal to the trigger amount, then activating the enable output means;
• 4. repeating step c.1;
• 5. examining the vended signal input means to determine if a vend unit has been vended by the controlled vending machine;
• if one has been vended, proceeding with step c.6, if not, proceeding with step c.9;
• 6. subtracting the value of the vended unit from the accumulated total;
• 7. comparing the accumulated total with a vend path value which is equal to the number of possible units in the vend path times the value of a single vend unit;
• if the accumulated total is less than or equal to the vend path value, then de-activating the enable output means;
• 8. repeating step c.1;
• 9. examining the value-return switch input means to determine if a value-return switch has been pressed;
• if a value-return switch has been pressed, then de-activating the enable output means and proceeding with the secondary value-return loop;
• if not, then repeating step c.1;
• d. the secondary value-return loop comprising the steps of:
• 1. starting a delay timer;
• 2. comparing the time elapsed in the delay timer with a time period which is at least sufficient for all of the possible vend units in the vend path to be processed;
• 3. if the time elapsed is at least equal to the time period, then activating the value-return output means to cause the value-emitting peripheral device to supply the customer with the amount of value remaining
• 4. examining the vended signal input means to determine if a vend unit has been vended by the controlled vending machine;
• 5. if one vend unit has been vended, then subtracting the value of the vended unit from the accumulated total;
• 6. repeating from step d.2.