Image forming apparatus and image forming method

An image forming apparatus, comprising:

• developing means which makes toner adhere to an electrostatic latent image formed on a photosensitive member to thereby form a toner image;
• an intermediate transfer medium onto which said toner image is primarily transferred during rotations of said intermediate transfer medium;
• secondary transfer means which secondarily transfers said toner image thus primarily transferred and now on said intermediate transfer medium onto a transfer paper;
• and fixing means which fixes said toner image on said transfer paper while said transfer paper is transported,
• wherein said image forming apparatus comprises transportation control means which has a normal mode for transporting a transfer paper at a first speed and a low speed mode for transporting a transfer paper at a second speed which is slower than said first speed at least from a secondary transfer position to a fixing end position,
• said image forming apparatus comprises intermediate transfer medium control means which drives said intermediate transfer medium at said first speed in said normal mode, but drives said intermediate transfer medium at said first speed in said low speed mode at least until the end of forming a toner image performed by said developing means, reduces a driving speed of driving said intermediate transfer medium from first speed to said second speed after the end of forming said toner image and then maintains said second speed at least until the end of secondary transfer,
• said image forming apparatus comprises image form control means which controls image forming on said photosensitive member so as to change a primary transfer start position on said intermediate transfer medium in accordance with a transfer paper size,
• said intermediate transfer medium has a transfer area, in which primary transfer of a toner image is possible and which is preset from the downstream side toward the upstream side along a direction of rotational driving, and
• said image form control means, in said low speed mode, controls said image forming so that a toner image will be primarily transferred onto such a portion of said transfer area which is on the upstream side of said intermediate transfer medium along a direction of rotational driving.