An image forming apparatus having a device for forming an image on a copy sheet, an input device for designating a due data, a device for storing the due date designated through the input device and a mechanism for inhibiting an operation of the image forming device after a lapse of the designated due...http://www.google.es/patents/US5142324?utm_source=gb-gplus-sharePatente US5142324 - Security device for rental photocopying machines
