Method for erasing a thermoplastic record

Claim 1

METHOD FOR ESTABLISHING A UNIFORM DEFORMATION PATTERN IN A THERMOPLASTIC RECORD USING A DEFORMATION PATTERN THEREIN HAVING BOTH DEFORMED AREAS AND NONDEFORMED AREAS THEREIN AND BEING OF SUCH NATURE THAT A GIVEN TEMPERATURE OF HEATING SAID RECORD NORMALLY IS REQUIRED FOR ERASING A LATTER PATTERN, COMPRISING THE STEPS OF: (A) CHARGING FIRSTLY SAID THERMOPLASTIC RECORD SURFACE, SAID SURFACE BEING IN AN INITIAL CONDITION IN ACCORDANCE WITH INFORMATION TO BE STORED THEREIN, (B) HEATING SAID THERMOPLASTIC RECORD SURFACE AT ONE TEMPERATURE TO ESTABLISH SAID LATTER DEFORMATION PATTERN THEREIN REPRESENTATIVE OF SAID INFORMATION, (C) CHARGING SECONDLY SAID SURFACE UNIFORMLY IN A FIRST REGION THEREOF, INCLUDING BOTH THE DEFORMED AREAS AND NON-DEFORMED AREAS THEREIN, AND (D) HEATING A SECOND REGION OF SAID SURFACE AT ANOTHER TEMPERATURE LOWER THAN SAID GIVEN TEMPERATURE, SAID REGIONS OVERLAPPING EACH OTHER, TO RE-ESTABLISH SAID INITIAL CONDITION IN SAID OVERLAPPING REGION.