Abstract: An image forming apparatus has a photosensitive member, a charging member, an exposing device, a developing device, a transfer member, a polishing member, a driving device, a voltage applying device, a torque detector, and a control portion. The photosensitive member has a photosensitive layer and a surface protection layer formed on the surface of the photosensitive layer. The polishing member has an elastic layer on its circumferential surface, and rotates with a linear velocity difference from that of the photosensitive member. The torque detector detects the torque of the driving device. The control portion estimates an attachment condition of discharge products to the surface of the photosensitive member based on the torque of the driving device detected by the torque detector. When the torque is equal to or higher than a predetermined value, the control portion performs an image degradation suppression process.

Abstract: A characteristic measuring portion measures current-voltage characteristics of a primary transfer member before a toner image for a first surface of a sheet is primarily transferred. A characteristic information storage portion stores characteristic information that indicates the current-voltage characteristics. A first transfer voltage determining portion determines a first transfer voltage based on a first target current value and the characteristic information. A second transfer voltage determining portion determines a second transfer voltage based on a second target current value and the characteristic information that was used when the first transfer voltage was determined, the second target current value being smaller than the first target current value. A voltage control portion applies the first and second transfer voltages to the primary transfer member by a constant-voltage method when the toner images for the first and second surfaces of the sheet are primarily transferred, respectively.

Abstract: An image forming apparatus 1 includes four developing devices 43, four primary transfer rollers 51, an intermediate transfer belt 54, voltage applicators 61, a current detector 62 and a voltage controller 911. The voltage applicators 61 each apply a voltage to a corresponding one of the four primary transfer rollers 51. The current detector 62 detects a first total current value JS of currents flowing through the four primary transfer rollers 51. The voltage applicators 61 apply a detection voltage VS to a primary transfer roller 51y among the four primary transfer rollers 51 while applying a voltage having the same polarity as the detection voltage VS to all the other primary transfer rollers 51c, 51m, and 51k. The detection voltage VS is applied to detect a resistance value Ry of the primary transfer roller 51y. The detection voltage VS has a predetermined voltage value.

Abstract: A characteristic measuring portion measures current-voltage characteristics of a primary transfer member before a toner image for a first surface of a sheet is primarily transferred. A characteristic information storage portion stores characteristic information that indicates the current-voltage characteristics. A first transfer voltage determining portion determines a first transfer voltage based on a first target current value and the characteristic information. A second transfer voltage determining portion determines a second transfer voltage based on a second target current value and the characteristic information that was used when the first transfer voltage was determined, the second target current value being smaller than the first target current value. A voltage control portion applies the first and second transfer voltages to the primary transfer member by a constant-voltage method when the toner images for the first and second surfaces of the sheet are primarily transferred, respectively.

Abstract: An image forming apparatus 1 includes four developing devices 43, four primary transfer rollers 51, an intermediate transfer belt 54, voltage applicators 61, a current detector 62 and a voltage controller 911. The voltage applicators 61 each apply a voltage to a corresponding one of the four primary transfer rollers 51. The current detector 62 detects a first total current value JS of currents flowing through the four primary transfer rollers 51. The voltage applicators 61 apply a detection voltage VS to a primary transfer roller 51y among the four primary transfer rollers 51 while applying a voltage having the same polarity as the detection voltage VS to all the other primary transfer rollers 51c, 51m, and 51k. The detection voltage VS is applied to detect a resistance value Ry of the primary transfer roller 51y. The detection voltage VS has a predetermined voltage value.

Abstract: An image forming apparatus includes an image carrier, a cleaning member, a rotation controlling part, a first obtaining part and a mode changing part. The image carrier has a surface to carry a toner image transferred onto a sheet. The cleaning member contacts the surface of the image carrier at a downstream side in a rotating direction of the image carrier from a transferring position transferring the toner image to collect a toner from the image carrier and to hold the toner. The rotation controlling part has a first speed control mode rotating the cleaning member at a first rotational speed and a second speed control mode rotating the cleaning member at a second rotational speed faster than the first rotational speed and switches from the first speed control mode to the second speed control mode at predetermined switch timing.

Abstract: An image forming apparatus includes an image carrier, a cleaning member, a rotation controlling part, a first obtaining part and a mode changing part. The image carrier has a surface to carry a toner image transferred onto a sheet. The cleaning member contacts the surface of the image carrier at a downstream side in a rotating direction of the image carrier from a transferring position transferring the toner image to collect a toner from the image carrier and to hold the toner. The rotation controlling part has a first speed control mode rotating the cleaning member at a first rotational speed and a second speed control mode rotating the cleaning member at a second rotational speed faster than the first rotational speed and switches from the first speed control mode to the second speed control mode at predetermined switch timing.