Printed image erasing system

1. A printed image erasing system configured to erase image information obtained by printing both characteristic identification information and document information or only the document information with an erasable color material on a printing medium,

comprising:

a printer unit configured to print the image information on the printing medium;

an erasing unit configured to erase an image printed on the printing medium with the erasable color material;

a reading unit configured to read the characteristic identification information on the printing medium to be erased by the erasing unit; and

a document management unit configured to manage an erasability condition of the document information on the basis of the characteristic identification information and instruct the printer unit to output new document information according to the erasability condition of the document information, the erasability condition being contained in the characteristic identification information read by the reading unit.

2. The printed image erasing system according to claim 1 , wherein, the erasability condition is version information; and when an old version of a document is erased, a latest version of the document is outputted from the printer unit.

3. The printed image erasing system according to claim 1 , wherein, the erasability condition is information about a retention period; and when a document within the retention period is erased, the contents of the document are outputted from the printer unit.

4. A printed image erasing system configured to prompting a user to erase image information obtained by printing both characteristic identification information and document information or only the document information with an erasable color material on a printing medium,

comprising:

a printer unit configured to print the image information on the printing medium;

an erasing unit configured to erase an image printed on the printing medium with the erasable color material;

a reading unit configured to read the characteristic identification information on the printing medium to be erased by the erasing unit;

an announcement unit configured to announce erasure of the image information by the erasing unit; and

a document management unit configured to manage the necessity of erasing the document information on the basis of the characteristic identification information, extract, on the basis of the characteristic identification information of a document instructed to be outputted from the printer unit, another existing document necessary to be erased, and instruct the announcement unit to announce erasure of the existing document.

5. A printed image erasing system configured to erase image information obtained by printing both characteristic identification information and document information or only the document information with an erasable color material on a printing medium,

comprising:

a printer unit configured to print the image information and the characteristic identification information on the printing medium;

an erasing unit configured to erase an image printed on the printing medium with the erasable color material;

a reading unit configured to read the image information on the printing medium to be erased by the erasing unit;

a plurality of discharge units prepared for the printing medium conveyed to the erasing unit; and

a document management unit configured to manage a discharge destination condition for the document information on the basis of the characteristic identification information and discharge the printing medium to one of the discharge units that corresponds to the discharge destination condition according to the characteristic identification information read by the reading unit.

6. The printed image erasing system according to claim 5 , wherein the discharge destination condition is erasability of a printed image.

7. The printed image erasing system according to claim 5 , wherein the discharge destination condition is a level of secrecy.