Image forming apparatus and method using different transfer voltages when recording material is heated in different image forming modes using different numbers of heating device

An image forming method comprising the steps of:

• preparing an image bearing member configured to carry a toner image;
• preparing transferring means for forming a transfer portion for transferring a toner image from said image bearing member onto a recording material by being supplied with a transfer voltage;
• preparing a first image heating device configured to heat the toner image transferred onto the recording material;
• preparing a second image heating device configured to heat the toner image transferred onto the recording material;
• preparing a cassette for storing recording materials;
• preparing supplying means for supplying the recording material into said transfer portion from said cassette;
• preparing resupplying means for resupplying the recording material from one of said first and second image heating devices into said transfer portion;
• preparing executing means for executing an operation in a first image forming mode for forming an image using said first image heating device without using said second image heating device, and an operation in a second image forming mode for forming an image using said first image heating device and said second image heating device;
• and
• preparing adjusting means for adjusting the transfer voltage in accordance with the kind of the recording material,
• wherein (i) when the kind of the recording material is plain paper and
• (i-i) when an image has already been formed on the plain paper in the first image forming mode and resupplied using said resupplying means to said transfer portion, said adjusting means adjusts the transfer voltage to a first level, and
• (i-ii) when an image has already been formed on the plain paper in the second image forming mode and resupplied using said resupplying means to said transfer portion, said adjusting means adjusts the transfer voltage to a second level, and
• wherein (ii) when the kind of the recording material is coated paper and
• (ii-i) when an image has already been formed on the coated paper in the first image forming mode and resupplied using said resupplying means to said transfer portion, said adjusting means adjusts the transfer voltage to a third level, and
• (ii-ii) when an image has already been formed on the coated paper in the second image forming mode and resupplied using said resupplying means to said transfer portion, said adjusting means adjusts the transfer voltage to a fourth level, and
• wherein the first level F1, the second level F2, the third level F3, and the fourth level F4 of the transfer voltages satisfies, |(F2-F1)|<|(F4-F3)|.