Canon Kabushiki Kaisha

Tetsuya Ohta

Yutaka Kakehi

Yusuke Minato

Etsuji Kojima

Toshiyuki Yamada

Tohru Nakaegawa

An image forming apparatus includes an image bearing member, an intermediary transfer belt, a transfer member, a voltage source for applying a voltage to the transfer member, a detecting portion for detecting a current flowing through the transfer member, and a controller for carrying out constant-voltage control so that the voltage applied to the transfer member becomes a target voltage when a recording material P passes through a transfer portion. The controller is capable of changing the voltage applied to the transfer member so that a detection result detected by the detecting portion during transfer falls within a predetermined range. The controller changes the predetermined range on the basis of the detection result detected by the detecting portion when the voltage is applied to the transfer member in a state in which the recording material P is absent in the transfer portion.

Image forming apparatus

An image forming apparatus includes an image bearing member, a transfer member, a voltage source, a current detecting portion, a controller, and a receiving portion. During the recording material passing through the transfer portion, the controller controls a voltage applied to a transfer member on the basis of a detection result of the current detecting portion so that a current flowing through the transfer member falls within a predetermined range. The controller sets at least one of an upper limit and a lower limit of the predetermined range on the basis of a predetermined voltage changing instruction received by the receiving portion.

An image forming apparatus includes an image bearing member, an intermediary transfer belt, a primary transfer roller provided so that a contact region between the roller and the belt and a contact region between the image bearing member and the belt are in a non-overlapping state with each other with respect to a movement direction of the belt, a primary transfer voltage source, a current detecting portion, an executing portion configured to acquire information on a discharge start voltage on the basis of a detection result of the detecting portion in a period other than a period of primary transfer by applying the voltage to the roller and a setting portion configured to set, on the basis of an execution result of the executing portion, a primary transfer voltage applied to the roller by the primary transfer voltage source in the period of the primary transfer.

Image forming apparatus with control of primary transfer voltage

An image forming apparatus includes an image bearing member, a transfer member, a voltage source, a speed setting portion, a test mode executing portion, a renewing mode executing portion, and a setting portion for setting a voltage applied to the transfer member. In a period in which the toner image exists at the transfer portion when image formation is executed at a first speed, the setting portion sets the voltage applied to the transfer member at a first target voltage last renewed. In a period in which the toner image exists at the transfer portion when the image formation is executed at a second speed, the setting portion sets the voltage applied to the transfer member at a voltage on the basis of the first target voltage last renewed and a conversion coefficient last renewed.

Image forming apparatus with updates for speed-based setting of transfer voltage

An image forming apparatus includes an image bearing member, a voltage source, a fixing device including a rotatable member, an executing portion for executing an operation in a both side mode, and a setting portion. The setting portion sets a transfer voltage in the operation for a second surface so that an absolute value of the transfer voltage when a recording material region, which starts from a most downstream end position and which passed through a fixing portion through a first one full circumference of the rotatable member when the toner image is fixed on a first surface passes through the transfer portion, is greater than an absolute value of the transfer voltage when a recording material region passed through the fixing portion through a second one full circumference of the rotatable member when the toner image is fixed on the first surface passes through the transfer portion.

An image forming apparatus includes: an image bearing member; a toner image forming unit; a belt member; a transfer member; a transfer voltage source for generating a voltage applied to the transfer member; an obtaining portion for obtaining information on an electric resistance of the belt member; a detecting member for optically detecting a test toner image formed on the image bearing member and transferred on the belt member; and an executing portion for executing, on the basis of a detection result of the test toner image by the detecting member, an adjusting operation for adjusting an image forming condition of the toner image forming unit. The executing portion sets, on the basis of the information, a voltage applied to the transfer member when the test toner image is transferred onto the belt member in the adjusting operation.

Image forming apparatus controlling transfer conditions based on resistance of transfer member

An image forming apparatus includes a movable image bearing member, a transfer member, a constant voltage source for applying a transfer voltage and a returning voltage to the transfer member, an executing portion capable of selectively executing an operation in a first mode in which image formation is executed at a first speed and an operation in a second mode in which the image formation is effected at a speed slower than the first speed, and a setting portion for setting a falling time from transfer voltage falling start timing toward the returning voltage until a current flowing through said transfer member is zero. The setting portion sets the falling time in the operation in the second mode so as to be longer than the falling time in the operation in the first mode.

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Abiko, Japan

Tetsuya Ohta