Image forming apparatus and control method therefor

A method of controlling an image forming apparatus which primarily transfers a formed toner image onto an intermediate transfer member at a primary transfer position, and secondarily transfers the primarily transferred toner image onto a printing medium at a secondarily transfer position, the method comprising the steps of:

• determining whether to change a rotation speed of the intermediate transfer member;
• when the rotation speed is determined in the determining step to change, primarily transferring, onto the intermediate transfer member, a toner image which is to be secondarily transferred onto the printing medium from the intermediate transfer member at a second speed by using, as a start position, a position spaced apart, by at least a distance necessary to change the rotation speed from a first speed to the second speed, from a position of a back end of a final toner image before changing a speed that is to be secondarily transferred onto the printing medium from the intermediate transfer member at the first speed;
• and
• starting changing the rotation speed from the first speed to the second speed after the back end of the final toner image before changing the speed is secondarily transferred onto the printing medium from the intermediate transfer member at the first speed.

A computer program which causes a computer to execute a method of controlling an image forming apparatus which primarily transfers a formed toner image onto an intermediate transfer member at a primary transfer position, and secondarily transfers the primarily transferred toner image onto a printing medium at a secondarily transfer position, the computer program comprising the steps of:

• determining whether to change a rotation speed of the intermediate transfer member;
• when the rotation speed is determined in the determining step to change, primarily transferring, onto the intermediate transfer member, a toner image which is to be secondarily transferred onto the printing medium from the intermediate transfer member at a second speed by using, as a start position, a position spaced apart, by at least a distance necessary to change the rotation speed from a first speed to the second speed, from a position of a back end of a final toner image before changing a speed that is to be secondarily transferred onto the printing medium from the intermediate transfer member at the first speed;
• and
• starting changing the rotation speed from the first speed to the second speed after the back end of the final toner image before changing the speed is secondarily transferred onto the printing medium from the intermediate transfer member at the first speed.

An image forming method of primarily transferring a formed toner image onto an intermediate transfer member at a primary transfer position, and secondarily transferring the primarily transferred toner image onto a printing medium at a secondary transfer position, the method comprising the steps of:

• primarily transferring, onto the intermediate transfer member moving at a first speed, a first toner image which is to be secondarily transferred onto a printing medium at the first speed;
• primarily transferring, onto the intermediate transfer member moving at the first speed at an interval corresponding to a time taken to change a moving speed of the intermediate transfer member from the first speed to the second speed, a second toner image which is successive to the first toner image and is to be secondarily transferred onto a printing medium at the second speed different from the first speed;
• secondarily transferring the first toner image onto the printing medium from the intermediate transfer member moving at the first speed;
• changing the moving speed of the intermediate transfer member to the second speed after secondarily transferring the first toner image onto the printing medium;
• and
• secondarily transferring the second toner image onto the printing medium from the intermediate transfer member moving at the second speed after changing the moving speed of the intermediate transfer member to the second speed.