| CPC G03G 15/065 (2013.01) [G03G 15/0266 (2013.01); G03G 15/0808 (2013.01); G03G 15/1675 (2013.01); G03G 2215/021 (2013.01)] | 17 Claims |
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1. An image forming apparatus comprising:
a rotatable image bearing member configured to bear a toner image;
a rotatable developing member configured to supply toner charged to a normal polarity to the image bearing member at a developing portion and to form the toner image on the image bearing member;
a supplying member configured to form a supplying portion by contacting the developing member and to supply the toner onto the developing member in the supplying portion;
a transferring member configured to form a transferring portion by contacting the image bearing member, the transferring member transferring the toner image from the image bearing member to a recording material nipped and conveyed by the image bearing member and the transferring member in the transferring portion;
a feeding member configured to feed the recording material toward the transferring portion;
a detecting portion configured to detect information on presence or absence of the recording material in a conveyance passage of the recording material fed toward the transferring portion by the feeding member;
a developing voltage applying portion configured to apply a developing voltage to the developing member;
a supplying voltage applying portion configured to apply a supplying voltage to the supplying member; and
a control portion configured to control the developing voltage applying portion and the supplying voltage applying portion,
wherein the control portion controls to perform a first operation in which a first potential difference is formed between the supplying member and the developing member, the first potential difference being a potential difference in a direction in which an electrostatic force in a direction toward the developing member from the supplying member is acted on the toner charged to the normal polarity, and
a second operation in which a second potential difference is formed between the supplying member and the developing member, the second potential difference being a potential difference in a direction in which an electrostatic force in a direction toward the supplying member from the developing member is acted on the toner charged to the normal polarity, and
wherein when an image forming operation in which the toner image is transferred onto the recording material is performed, the control portion controls timing for changing from the first operation to the second operation based on the information detected by the detecting portion in a non-image forming operation before the recording material is nipped and conveyed at the transferring portion.
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