Frost collector for refrigerated display cases

Claim 1

IN LOW TEMPERATURE REFRIGERATED EQUIPMENT HAVING A STORAGE SPACE THEREIN PROVIDED WITH AN ACCESS OPENING, MEANS FOR FORMING AN AIR CURTAIN DIRECTED ACROSS SAID ACCESS OPENING AND INCLUDING DUCT MEANS HAVING AN AIR OUTLET AT ONE SIDE OF SAID ACCESS OPENING AND A RETURN AIR DUCT AT THE OPPOSITE SIDE OF SAID ACCESS OPENING, MEANS FOR CIRCULATING AIR IN A SUBSTANTIALLY CONTINUOUS CIRCUIT THROUGH SAID DUCT MEANS AND OUTLET TO SAID RETURN AIR DUCT TO ESTABLISH SAID AIR CURTAIN, REFRIGERATING MEANS INCLUDING AN EVAPORATOR LOCATED IN SAID DUCT MEANS AND OPERABLE DURING A REFRIGERATING CYCLE TO MAINTAIN THE AIR CIRCULATED THROUGH SAID DUCT MEANS AND ACROSS SAID ACCESS OPENING AND THROUGH SAID RETURN AIR DUCT AT A TEMPERATURE BELOW FREEZING, THE IMPROVEMENT COMPRISING MEANS FOR REDUCING THE ACCUMULATION OF FROST ON SAID EVAPORATOR COMPRISING A NON-REFRIGERATED FROST COLLECTOR LOCATED IN SAID RETURN AIR DUCT AND IN ADVANCE OF SAID EVAPORATOR FOR ACCUMULATING ON SAID FROST THEREON, MEANS FOR CONVERTING FROST ACCUMULATED ON SAID FROST COLLECTOR FROM A SOLID TO A LIQUID FROM WITHOUT SUBSTANTIAL VAPORIZATION OF THE LIQUID PRODUCED INCLUDING HEATING MEANS OPERABLE PERIODICALLY TO RAISE THE TEMPERATURE OF SAID FROST COLLECTOR TO A TEMPERATURE ABOVE FREEZING FOR A LIMITED TIME AND TO AN EXTENT SUFFICIENT ONLY TO CONVERT THE ACCUMULATED FROST INTO DROPS OF WATER WITHOUT CAUSING VAPORIZATION THEREOF AND MIGRATION OF MOISTURE FROM SAID FROST COLLECTOR TO SAID EVAPORATOR, SAID HEATING MEANS BEING OPERABLE AT LEAST AT TIMES DURING SAID REFRIGERATING CYCLE.