This invention relates to an image forming apparatus which employs a recycling
scheme of recovering and reusing transfer residue toner, and a convey control method
for recycle toner. In order to prevent a phenomenon such as fogging or character
thickening, a toner recycle mechanism shares one driving source with a photosensitive
body or fixing unit, and includes an electromagnetic clutch for switching driving
force transmission to the recycling means when driving the photosensitive body
or fixing unit, and a controller which controls power supply to the electromagnetic
clutch. The convey control method for recycle toner includes the steps of starting
copying, measuring a printing ratio of an image pattern per image, and suppressing
a return amount of the recycle toner when the printing ratio of the image pattern
is low.
