Heating device

Claim 1

A DEVICE FOR THE DEVELOPMENT OR PRINTING OF PHOTOGRAPHIC MATERIAL, COMPRISING: A HOLLOW CYLINDRICAL CONTACT MEMBER HAVING AN OUTER SURFACE OF EXTENDED AREA FOR CONTACTING MATERIAL TO BE DEVELOPED OR PRINTED; MEANS FOR MOUNTING SAID CONTACT MEMBER SO AS TO PERMIT ROTATION OF SAID MEMBER ABOUT THE AXIS THEREOF UPON THE PASSAGE OF PHOTOGRAPHIC MATERIAL OVER SAID MEMBER; AN ELECTRIC HEATER ELEMENT WHICH EXTENDS OVER AND IS IN GOOD THERMAL CONTACT WITH THE INNER SURFACE OF SAID CONTACT MEMBER SO THAT, UPON SUPPLY OF CURRENT TO SAID ELEMENT, HEAT IS SUPPLIED TO THE EXTENDED OUTER SURFACE OF SAID CONTACT MEMBER AT A RATE SUITABLE FOR PRINTING OR DEVELOPING CONTACTED MATERIAL; CONTROL MEANS; INCLUDING AN ELONGATED CONTROL MEMBER HAVING A CO-EFFICIENT OF THERMAL EXPANSION DIFFERENT FROM THAT OF THE SAID CONTACT MEMBER, SAID CONTROL MEMBER EXTENDING THROUGH THE INTERIOR OF SAID CONTACT MEMBER, PARALLEL WITH THE AXIS THEREOF, AND HAVING ONE END FIXEDLY SECURED RELATIVE TO ONE END OF SAID CONTACT MEMBER SO THAT RELATIVE MOVEMENT TAKES PLACE BETWEEN THE OTHER ENDS OF THE RESPECTIVE CONTACT AND CONTROL MEMBERS UPON A CHANGE IN TEMPERATURE OF SAID CONTACT MEMBER; AND SWITCH MEANS ELECTRICALLY CONNECTED TO SAID HEATER ELEMENT AND MOUNTED ON THE SAID OTHER END OF SAID CONTACT MEMBER, SAID SWITCH MEANS BEING ARRANGED TO BE ACTUATED BY A RELATIVE MOVEMENT OF THE SAID OTHER ENDS OF SAID RESPECTIVE CONTACT AND CONTROL MEMBERS CORRESPONDING TO A PREDETERMINED RISE IN TEMPERATURE OF SAID CONTACT MEMBER AND, UPON ACTUATION, TO CONTROL THE SUPPLY OF CURRENT TO SAID HEATING ELEMENT.