Temperature control means for electrically heated impulse sealing elements

Claim 1

AUTOMATIC TEMPERATURE CONTROL MEANS FOR CONTROLLING THE TEMPERATURE OF A HEAT-EXPANSIBLE ELEMENT IN RESPONSE TO THE EXPANSION OF THE ELEMENT BY CONTROLLING THE HEATING THEREOF, COMPRISING: CIRCUIT MEANS INCLUDING A HEAT-EXPANSIBLE ELEMENT CONNECTED THEREIN, TRANSFORMER MEANS COUPLED TO AN ELECTRICAL SOURCE AND OPERABLE WHEN ENERGIZED TO PASS A HEATING CURRENT OF HIGH AMPLITUDE THROUGH THE ELEMENT, FIRST AND SECOND RELATIVELY MOVABLE ELECTRICAL CONTACT MEANS, AT LEAST ONE OF WHICH IS MOVABLE WITH THE ELEMENT UPON THE EXPANSION THEREOF, RELAY MEANS HAVING CONTACTS IN CIRCUIT WITH SAID TRANSFORMER AND SAID SOURCE AND OPERABLE WHEN ENERGIZED TO DE-ENERGIZE SAID TRANSFORMER MEANS, SAID FIRST AND SECOND CONTACT MEANS BEING OPERABLE UPON ABUTMENT THEREBETWEEN TO DE-ENERGIZE SAID RELAY MEANS TO DISCONTINUE THE PASSAGE OF THE HEATING CURRENT THROUGH THE ELEMENT, SAID CONTACT MEANS BEING RELATIVELY MOVABLE FROM SPACED, FIRST POSITIONS THEREOF WHEN THE ELEMENT IS IN THE UNHEATED CONDITION THEREOF TO ABUTTING, SECOND POSITIONS OF THE CONTACTS WHEN THE ELEMENT IS IN THE HEATED CONDITION THEREOF, AND MEANS TO MAINTAIN SAID FIRST AND SECOND CONTACT MEANS SPACED APART BY A PREDETERMINED DISTANCE WHEN THE ELEMENT IS IN THE UNHEATED CONDITION THEREOF NOTWITHSTANDING ANY PERMANENT ELONGATION WHICH MAY DEVELOP IN THE ELEMENT DUE TO THE HEATING THEREOF, AND SECOND RELAY MEANS OPERABLE UPON THE ENERGIZATION THEREOF TO MAINTAIN THE FIRST-MENTIONED RELAY MEANS DE-ENERGIZED UNTIL SAID SECOND RELAY MEANS ARE DE-ENERGIZED, AND SWITCH MEANS TO DE-ENERGIZE SAID SECOND RELAY MEANS.