Patent ID: 7760945
Filing Date: 2010-07-20
Classification: B41J

Abstract:
1. A method of indicating and detecting a remaining amount of an ink ribbon having a transparent sheet on which an ink layer is formed in a thermal transfer type image forming apparatus which prints an image by applying heat from a thermal head to the ink ribbon to transfer ink to a sheet of paper, the method comprising: forming a print number mark that is optically detectable on the ink ribbon by removing part of the ink layer by applying heat to the ink ribbon from the thermal head; and detecting the print number mark using at least one optical sensor before a subsequent print starts to determine the remaining amount of the ink ribbon, wherein the ink ribbon comprises: a plurality of print areas divided corresponding to a length of the sheet of paper, each having an ink layer of a predetermined color; a plurality of non-print areas having a higher light transmissivity and provided at leading end portions of the print areas to separate the print areas; and a header mark provided in each non-print area, on which an ink layer having a low light transmissivity is coated, wherein the forming of the print number mark comprises removing a portion of the ink layer of the header mark.