ALL-IN-ONE DOOR SWITCH INTERFACE TO MULTIPLE CONTROLLERS WITHIN A VENDING MACHINE
First Claim
Patent Images
1. A vending machine door switch interface comprising:
- power supply voltage and ground voltage connections;
an output connection coupled to a plurality of controllers within a vending machine; and
a comparator having first and second inputs coupled across terminals for a door switch for a service door within the vending machine, wherein the door switch is in a first state when the service door is closed and in a second state when the service door is open,wherein the first comparator input is coupled to the power supply voltage connection and the second comparator input is coupled to the ground voltage connection, andwherein the door switch interface is configured to produce an output signal on the output connection based upon an output of the comparator, the output signal having a first value when the door switch is in the first state and a second value when the door switch is in the second state.
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Abstract
A vending machine door switch interface allows multiple controllers, including the vending machine controller, to employ a single door switch without polarization or interference. The interface includes a comparator having inputs coupled across the door switch and, based on the door switch state, produces an output signal indicating whether the service door is closed or open. The comparator output when the service door is known to be open is recorded to subsequently distinguish open and closed states. Unbalanced connections to power and ground result in different voltages at the comparator inputs when the door switch is closed.
50 Citations
20 Claims
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1. A vending machine door switch interface comprising:
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power supply voltage and ground voltage connections; an output connection coupled to a plurality of controllers within a vending machine; and a comparator having first and second inputs coupled across terminals for a door switch for a service door within the vending machine, wherein the door switch is in a first state when the service door is closed and in a second state when the service door is open, wherein the first comparator input is coupled to the power supply voltage connection and the second comparator input is coupled to the ground voltage connection, and wherein the door switch interface is configured to produce an output signal on the output connection based upon an output of the comparator, the output signal having a first value when the door switch is in the first state and a second value when the door switch is in the second state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of detecting the state of a vending machine door, the method comprising:
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supplying power to a vending machine having an output connection for a door switch interface connected to a plurality of controllers within the vending machine, and first and second inputs for a comparator coupled across terminals for a door switch for a service door within the vending machine, wherein the door switch is in a first state when the service door is closed and in a second state when the service door is open, the first comparator input coupled to a power supply voltage connection, the second comparator input coupled to a ground voltage connection; and producing an output signal on the output connection based upon an output of the comparator, the output signal having a first value when the door switch is in the first state and a second value when the door switch is in the second state. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification