Abstract: A mode in which a toner image formed on an intermediate transfer belt passes through a primary transfer portion without a toner image being transferred from a photosensitive drum onto the intermediate transfer belt is provided. In the mode, an area of the photosensitive drum that passes through the primary transfer portion while the toner image is passing through the primary transfer portion is defined as a first area. When the first area passes through a charging position, a charging bias is adjusted so that the occurrence of an image defect is prevented.

Abstract: An image forming apparatus includes a control unit that performs two types of stop operations in which an image bearing member is rotated or is not rotated after forming an image. The control unit selects the stop operation according to operation time of the image bearing member.

Abstract: An image forming apparatus includes a control unit that performs two types of stop operations in which an image bearing member is rotated or is not rotated after forming an image. The control unit selects the stop operation according to operation time of the image bearing member.

Abstract: In a rotary-type image forming apparatus in which detection of electrostatic capacitance is performed when a developing apparatus is in a posture less affected by a toner density within the developing apparatus, a toner in the developing apparatus, which is located at a development position during the detection of the electrostatic capacitance, is avoided from being uselessly consumed. The image forming apparatus has a remaining amount detection mode of detecting a toner remaining amount on condition that a developing roller of one developing apparatus positioned opposite to another developing apparatus, for which the toner remaining amount is to be detected, stands by in a state spaced from a drum.

Abstract: A charge bias causing the surface potential of a photosensitive drum to be lower than that in image formation is applied to a charge roller during a period in which the stop position of a rotary is moved from an unknown state to a home position to cause a developing bias to be applied to a developing roller to be smaller than that in the image formation.

Abstract: An image forming apparatus is operable in a mode in which a speed of an intermediary transfer belt is changed after all of the toner images are primary-transferred onto the intermediary transfer belt, and the toner image primary-transferred on the intermediary transfer belt is passed through a secondary transfer position and primary transfer position in this order to reach the secondary transfer position, where the toner image is secondary transferred onto the transfer material, and a controller for making, before the image forming apparatus is operated in the mode to change the speed of the intermediary transfer belt, a potential difference between the intermediary transfer belt and the photosensitive member at the primary transfer position smaller than a potential difference between the intermediary transfer belt and the photosensitive member when the toner image is primary transferred from the photosensitive member onto the intermediary transfer belt.

Abstract: A developing device includes: a developer carrying member, rotatable while carrying a developer, for supplying the developer to an image bearing member; a developer supplying member, which is provided with a foam layer at its surface and is rotatable in contact to the developer carrying member, for supplying the developer to the developer carrying member; a first gear for transmitting a driving force to the developer supplying member; and a pressing member for pressing the first gear so that the first gear is, during initial drive of the developer carrying member, moved from a first position where the driving force is not transmitted to the developer supplying member to a second position where the driving force is transmitted to the developer supplying member.

Abstract: An image forming apparatus is operable in a mode in which a speed of an intermediary transfer belt is changed after all of the toner images are primary-transferred onto the intermediary transfer belt, and the toner image primary-transferred on the intermediary transfer belt is passed through a secondary transfer position and primary transfer position in this order to reach the secondary transfer position, where the toner image is secondary transferred onto the transfer material, and a controller for making, before the image forming apparatus is operated in the mode to change the speed of the intermediary transfer belt, a potential difference between the intermediary transfer belt and the photosensitive member at the primary transfer position smaller than a potential difference between the intermediary transfer belt and the photosensitive member when the toner image is primary transferred from the photosensitive member onto the intermediary transfer belt.

Abstract: In a rotary-type image forming apparatus in which detection of electrostatic capacitance is performed when a developing apparatus is in a posture less affected by a toner density within the developing apparatus, a toner in the developing apparatus, which is located at a development position during the detection of the electrostatic capacitance, is avoided from being uselessly consumed. The image forming apparatus has a remaining amount detection mode of detecting a toner remaining amount on condition that a developing roller of one developing apparatus positioned opposite to another developing apparatus, for which the toner remaining amount is to be detected, stands by in a state spaced from a drum.

Abstract: A mode in which a toner image formed on an intermediate transfer belt passes through a primary transfer portion without a toner image being transferred from a photosensitive drum onto the intermediate transfer belt is provided. In the mode, an area of the photosensitive drum that passes through the primary transfer portion while the toner image is passing through the primary transfer portion is defined as a first area. When the first area passes through a charging position, a charging bias is adjusted so that the occurrence of an image defect is prevented.

Abstract: An image forming apparatus includes a rotatable image bearing member configured to bear an electrostatic latent image, a plurality of development devices including a developer bearing member configured to bear a developer for developing the electrostatic latent image, a rotatable development device supporting member configured to support the plurality of development devices. In the image forming apparatus, the developer bearing member is configured to execute development while contacting the image bearing member at a development position via the developer, rotating in the same direction as rotating direction of the image bearing member at the development position, and rotating at a speed faster than a surface speed of the image bearing member.

Abstract: An image forming apparatus includes a control unit that performs two types of stop operations in which an image bearing member is rotated or is not rotated after forming an image. The control unit selects the stop operation according to operation time of the image bearing member.

Abstract: A charge bias causing the surface potential of a photosensitive drum to be lower than that in image formation is applied to a charge roller during a period in which the stop position of a rotary is moved from an unknown state to a home position to cause a developing bias to be applied to a developing roller to be smaller than that in the image formation.

Abstract: The invention realizes a uniform toner coating on a developing roller, thereby preventing a density unevenness and a toner dripping and suppressing a developing roller set mark image in a contact developing method, by conditions that the DC voltage applied to the developer regulating member is the same as the DC voltage applied to the developer carrying member or at a side of a charging polarity of the developer with respect to the DC voltage applied to the developer carrying member; and a frequency f (Hz) and a peak electric field strength E (V/m) of the AC electric field formed by the AC voltage between the developer regulating member and the developer carrying member, and a peripheral speed v (m/s) of the image bearing member satisfy conditions: 4.2×v?f?2500 and 2.2×106?E?5.2×106.

Abstract: The invention realizes a uniform toner coating on a developing roller, thereby preventing a density unevenness and a toner dripping and suppressing a developing roller set mark image in a contact developing method, by conditions that the DC voltage applied to the developer regulating member is the same as the DC voltage applied to the developer carrying member or at a side of a charging polarity of the developer with respect to the DC voltage applied to the developer carrying member; and a frequency f (Hz) and a peak electric field strength E (V/m) of the AC electric field formed by the AC voltage between the developer regulating member and the developer carrying member, and a peripheral speed v (m/s) of the image bearing member satisfies conditions: 4.2×v?f?2500 and 2.2×106?E?5.2×106.