The invention can prevent problems due to the feeding of an OHT sheet for
ink jet, such as damaging a fixing device or deterioration of the image,
as well as damaging of the fixing device due to the feeding of a sheet
with a thickness exceeding a regular thickness, and can transmit related
information to the user, so as to enhance reliability and usability of the
image forming apparatus. The image forming apparatus includes a feeding
unit for feeding a recording material, an image forming unit for forming
an image on the recording material fed by the feeding unit, a reading unit
capable of reading an image of an area including a portion of a surface of
the recording material fed by the feeding unit, a determining unit for
determining whether or not the recording material is an irregular
recording material, based on the image read by the reading unit, and a
controlling unit for stopping or suppressing a specific operation of the
apparatus, when it is determined by the determining unit that the
recording material is an irregular recording material.
