Conventionally, from the point of view of the effective use and reuse of paper resources, there are writing instruments that use inks that become colorless when heated to a high temperature such as above 60° C., etc. Further, there are ink jet printers that have a recording section using inks that become colorless when heated and a heating section that is placed before said recording section and that makes the ink colorless (see, for example, Japanese Patent Application Publication No. 2001-302954).
In a situation such as reading out by scanning the personal information written in questionnaires and converting it to an electronic form, and managing it by storing it in a data base, etc., it is required to appropriately dispose of the paper after converting to an electronic form thereby preventing the leakage of personal information. In such cases, if the entering is done using a writing instrument using an ink such as the above that becomes colorless upon heating, it is possible to erase the entered part by heating the sheet after it has been read out and the information is converted into an electronic form, and hence it is possible to prevent the leakage of personal information. In addition, if only the entered part can be erased, it is also possible to use the sheet again as a questionnaire form that has not been filled in.
However, in a work flow in which, after reading by a scanner and converting the information to an electronic form, the sheet is erased by heating in a different apparatus, there is no guarantee that the erasing operation is definitely done after reading out and converting to an electronic form. In addition, if the time of leaving the document after reading and converting to an electronic form until the erasing operation is carried out becomes long, the possibility of information leakage becomes correspondingly higher.
The present invention was made with the aim of solving the above problem, and the purpose of the present invention is to provide an image reading apparatus that can, after reading out and converting to an electronic form a document containing a part that is written using a pigment that becomes colorless when heated, quickly erase the part that is written in such an ink.