Vending machine control with improved vendor selector switch detection and decoding apparatus
First Claim
1. A vending machine control apparatus for control of a vending machine, said control apparatus having an improved vendor selector switch detection and decoding apparatus comprising:
- a plurality of vendor selection switches for selecting a product to be dispensed;
a plurality of impedances electrically connected to the plurality of vendor selector switches to form a keyboard network having at least one keyboard decode line which presents a unique keyboard impedance depending upon which switch of the plurality of vendor selector switches is closed;
a switch decode means for detecting and decoding a closure of at least one of the plurality of vendor selector switches, and for producing an output signal indicative of said closure on a switch decode line, said switch decode means having an input connected to the keyboard network by the keyboard decode line; and
a logic control means for making a determination of which of the plurality of vendor selection switches has been closed from the output signal on he switch decode line of the switch decode means and for utilizing said determination of the overall control fof the vending machine, said logic control means connected to the switch decode line of the switch decode means and to a plurality of vending machine means for controlling subfunctions of the vending machine.
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Accused Products
Abstract
A vending machine control with an improved vendor selector switch detection and decoding circuit is described which detects and decodes the closure of selector switches in a vending machine utilizing a low cost decoding arrangement. Each selector switch is associated with a corresponding impedance in a keyboard network so that a unique impedance is presented on a keyboard decode line from the keyboard network. Decode circuitry and a decode algorithm are also disclosed for a period based decoding scheme which compensates for various tolerances and environmental affects.
67 Citations
17 Claims
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1. A vending machine control apparatus for control of a vending machine, said control apparatus having an improved vendor selector switch detection and decoding apparatus comprising:
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a plurality of vendor selection switches for selecting a product to be dispensed; a plurality of impedances electrically connected to the plurality of vendor selector switches to form a keyboard network having at least one keyboard decode line which presents a unique keyboard impedance depending upon which switch of the plurality of vendor selector switches is closed; a switch decode means for detecting and decoding a closure of at least one of the plurality of vendor selector switches, and for producing an output signal indicative of said closure on a switch decode line, said switch decode means having an input connected to the keyboard network by the keyboard decode line; and a logic control means for making a determination of which of the plurality of vendor selection switches has been closed from the output signal on he switch decode line of the switch decode means and for utilizing said determination of the overall control fof the vending machine, said logic control means connected to the switch decode line of the switch decode means and to a plurality of vending machine means for controlling subfunctions of the vending machine. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of detecting and decoding a closure of a vendor selection switch arranged in a network of selector switches and impedances electrically connected to form a keyboard network having at least one keyboard decode line which presents a unique keyboard impedance depending upon which switch is closed, in a vending machine including a microprocessor based control system comprising the steps of:
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producing a signal having a period indicative of the unique keyboard impedance; measuring an all switch open base period when all the selector switches in the network are open; calculating a step change period value by effectively dividing the all switch open period by a value related to the unique keyboard impedance when all the selector switches in the network are open; remeasuring the period of the signal after the closure of a vendor selection switch; and determining which vendor selection switch has been closed by comparing the period measured after closure with the step change period value. - View Dependent Claims (16, 17)
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14. A vending machine control apparatus for control of a vending machine, said control apparatus having an improved vendor selector switch detection and decoding apparatus comprising:
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a plurality of vendor selection switches for selecting a product to be dispensed; a plurality of resistors on a substrate sheet electrically connected by connectors to the plurality of vendor selector switches to form a membrane keyboard network having at least one keyboard decode line which presents a unique keyboard resistance depending upon which switch of the plurality of vendor selector switches is closed; a switch decode means for detecting and decoding a closure of at least one of the plurality of vendor selector switches, and for producing an output signal indicative of said closure on a switch decode line, said switch decode means having an input connected to the keyboard network by the keyboard decode line; and a logic control means for making a determination of which of the plurality of vendor selection switches has been closed from the output signal on the switch decode line of the switch decode means and for utilizing said determination in the overall control of the vending machine, said logic control means connected to the switch decode line of the switch decode means and to a plurality of vending machine means for controlling subfunctions of the vending machine. - View Dependent Claims (15)
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Specification