Image forming apparatus

An image forming apparatus comprising:

• a first image forming unit configured to form an image on a sheet with a first material that is not erasable by heating;
• a second image forming unit that is located on a downstream side of the first image forming unit in a sheet conveying direction, the second image forming unit configured to form an image on the sheet with a second material that is erasable by heating to an erasing temperature:
• a fixing device that is arranged between the first image forming unit and the second image forming unit, the fixing device configured to fix the image with the first material on the sheet by heating the sheet to a fixing temperature lower than the erasing temperature in a fixing process, and configured to heat the sheet on which the image is formed with the second material to a temperature above the erasing temperature in an erasing processing;
• a stacking unit in a sheet conveying path, the stacking unit configured to stack the sheet subjected to the erasing process, and configured to feed the stacked sheet to the second image forming unit in the sheet conveying path;
• and
• a control unit configured to control a sheet conveying operation such that, if the second image forming unit is to form an image on the sheet that is subjected to the erasing process by the fixing device, a time for the sheet to be conveyed from the fixing device to the second image forming unit is made to be equal to or longer than a predetermined cooling time, and to cause, in a period until the sheet subjected to the erasing process reaches the second image forming unit, the stacking unit to stack the additional sheets;
• and
• a sheet conveying unit configured to convey the sheet subjected to the erasing process to the second image forming unit in the sheet conveying operation.

An image formation processing control method in an image forming apparatus including:

• a first image forming unit configured to form an image on a sheet with a first material that is not erasable by heating;
• a second image forming unit that is located on a downstream side of the first image forming unit in a sheet conveying direction, the second image forming unit configured to form an image on the sheet with a second material that is erasable by heating to an erasing temperature;
• and a fixing device that is arranged between the first image forming unit and the second image forming unit, the fixing device configured to fix the image with the first material on the sheet by heating the sheet to a fixing temperature lower than the erasing temperature in a fixing process, and configured to heat the sheet on which the image is formed with the second material to a temperature above the erasing temperature in an erasing process, the method comprising:
• conveying a sheet subjected to the erasing process to the second image forming unit in a sheet conveying operation;
• controlling the sheet conveying operation such that a required time for the sheet subjected to the erasing process to be conveyed from the fixing device to the second image forming unit is equal to or longer than a predetermined cooling time;
• stacking the sheet subjected to the erasing process;
• feeding the stacked sheet to the second image forming unit;
• stacking additional sheets for a period until the sheet subjected to the erasing process reaches the second image forming unit;
• and
• forming an image on the sheet subjected to the erasing process with the second image forming unit.