Patent ID: 6430948
Filing Date: 2002-08-13
Classification: F25B,F25D,G07F

Abstract:
An automatic vending machine comprising:a commodity storage for storing a number of items to be sold; a refrigerating circuit having a cooling unit connected to said commodity storage for cooling said items; a defrosting unit connected to said cooling unit for intermittently carrying out a defrosting operation for said cooling unit; a temperature sensor connected to said commodity storage for detecting a storage temperature within said commodity storage to produce a temperature signal; a calculating unit connected to said temperature sensor and responsive to said temperature signal for calculating a temperature variation rate prior to said defrosting operation; and a defrost control part connected to said calculating unit and said defrosting unit for controlling said defrosting operation with reference to said temperature variation rate; wherein said calculating unit comprises: a first calculating part connected to said temperature sensor and responsive to said temperature signal for calculating a predetermined number of variation rates of temperature per unit time; and a second calculating part connected to said first calculating part and said defrost control part for calculating an average value of said variation rates to supply said average value as said temperature variation rate to said defrost control part; and said automatic vending machine further comprising a unit time setting part connected to said first calculating part for setting said unit time.