Image forming apparatus

An image forming apparatus comprising:

• a rotatable image bearing member on which an electrostatic latent image is formed;
• a rotatable developing member configured to supply a developer to the image bearing member, develop the electrostatic latent image and form a developer image;
• a rotatable supplying member configured to supply the developer to the developing member by contacting the developing member;
• a moving portion configured to move the developing member to a contacting position where the developing member is contacted to a surface of the image bearing member or a separated position where the developing member is separated from the surface of the image bearing member;
• a driving source configured to drive the image bearing member, the developing member and the supplying member;
• and
• a control means configured to control the moving portion and the driving source,
• wherein in a first period when the developing member is moved from the separated position to the contacting position by the moving portion before the electrostatic latent image is formed on the image bearing member, when a peripheral speed that is a moving speed of the surface of the image bearing member is defined as Vo1, a peripheral speed that is a moving speed of a surface of the developing member is defined as Vd1, a peripheral speed that is a moving speed of a surface of the supplying member is defined as Vr1, an absolute value of a difference between the peripheral speed of the image bearing member and the peripheral speed of the developing member is defined as |Vo1−Vd1|, and an absolute value of a difference between the peripheral speed of the developing member and the peripheral speed of the supplying member is defined as |Vd1−Vr1|, and
• in a second period while the electrostatic latent image is being formed on the image bearing member, when a peripheral speed that is a moving speed of the surface of the image bearing member is defined as Vo2, a peripheral speed that is a moving speed of the surface of the developing member is defined as Vd2, a peripheral speed that is a moving speed of the surface of the supplying member is defined as Vr2, an absolute value of a difference between the peripheral speed of the image bearing member and the peripheral speed of the developing member is defined as |Vo2−Vd2|, and an absolute value of a difference between the peripheral speed of the developing member and the peripheral speed of the supplying member is defined as |Vd2−Vr2|,
• the control means controls the driving source so as to satisfy a following relationship,
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• so as to monotonically change the peripheral speed that is the moving speed of the surface of the image bearing member from Vo1 to Vo2, the peripheral speed that is the moving speed of the surface of the developing member from Vd1 to Vd2, and the peripheral speed that is the moving speed of the surface of the supplying member from Vr1 to Vr2.