An image forming apparatus detects a first current value and a second current value of currents flowing between an image bearing member and a developer carrying member. When a difference between the detected first current value and the detected second current value exceeds a threshold in a state in which the image bearing member and the developer carrying member are rotated and a first developing voltage is applied to the developer carrying member, a controller controls AC voltage applied to the developer carrying member.

A measurement device is provided with: a measurement unit including a first mode that measures an electrical resistance of a recording medium used in an image forming apparatus in a first predetermined range of electrical resistance values and a second mode that measures the electrical resistance in a second range of electrical resistance values different from the first range, the second range and the first range being set such that with respect to the electrical resistance of multiple brands of recording media, a number of brands belonging to the second range is greater than a number of brands belonging to the first range; and a control unit that controls the measurement unit to prioritize execution of the second mode over the first mode.

An image forming apparatus includes a developing device that forms a toner image, by developing an electrostatic latent image formed on a photoconductor drum, a charging device that electrically charges the photoconductor drum, a developing power source that applies a predetermined developing bias voltage to the developing device, and a calculation device that calculates a surface potential of the photoconductor drum, on a basis of the developing current flowing in the developing device. The developing power source applies the developing bias voltage in a plurality of levels, to the developing device. A current measurement device measures a developing current, with respect to the developing bias voltage of each level. The calculation device calculates the surface potential, on the basis of each developing current.

The electrophotographic apparatus includes: an electrophotographic photosensitive member; a charging unit; an image-exposing unit; a charge transfer amount-sensing unit for sensing the amount of charge transferred to the electrophotographic photosensitive member; and an exposed portion potential-controlling unit for controlling the potential of each of the exposed portions of the electrophotographic photosensitive member based on a sensing result, which is obtained by charging the electrophotographic photosensitive member with the charging unit, performing image exposure with the image-exposing unit in at least one light amount weaker than a light amount in which the normalized radius of curvature R of the electrophotographic photosensitive member represented by the following equation (E1), the normalized radius of curvature being obtained by a method of measuring an EV curve, shows a minimum, and in at least two light amounts stronger than the light amount in which the normalized radius of curvature shows the minimum.

[00001]$\begin{array}{cc}R=\frac{{\left[1+{\left(\frac{\mathrm{dy}}{\mathrm{dx}}\right)}^2\right]}^{3/2}}{.Math.\frac{d^2}{{\mathrm{dx}}^2}.Math.}& \left(E1\right)\end{array}$

An image forming apparatus includes an image-carrying component configured to carry a colorant image including an adjustment image, a transferring component having a recess in an outer peripheral surface and configured to transfer the colorant image from the image-carrying component to a recording medium in a transfer area while rotating in such a manner as to allow a retainer that is retaining the recording medium to pass through the recess, an image-forming component configured to form the adjustment image at such a position of the image-carrying component as to face the recess of the transferring component, and a transporting component configured to cause the recording medium retained by the retainer to pass through the transfer area.

An image forming apparatus includes an image carrier, a charging device, a developing device, a transfer device, a development power supply, a current measurement device, and a processor. The development power supply applies a predetermined bias voltage to the developing device. The processor functions as a calculator and a controller. The calculator calculates a surface potential of the image carrier based on the development current measured by the current measurement device. The controller controls the charging device, the developing device, the transfer device, and the development power supply. The controller sets a tentative transfer current to be flowed through the transfer device while the calculator calculates the surface potential.

An image forming apparatus includes a photosensitive member, a charging member, an exposure unit, a developing unit including a developing member, a motor, a contact and separation unit, a controller, an acquiring portion for acquiring information on a switching time which is a time required for switching a state of the developing member from a separated state to a contact state by executing a contact operation by the contact and separation unit, and a setting portion for setting, on the basis of the information on the switching time acquired by the acquiring portion, a start timing which is a timing when the contact operation by the contact and separation unit is started in a preparation operation and which is a timing before a region on the photosensitive member exposed to light in a light emission period reaches a developing position.

An image forming apparatus includes a fixing member that fixes, onto a recording material, a toner image that has been transferred onto the recording material, a recovery roller that recovers toner adhering onto the fixing member, a cleaning unit, and a controller. The cleaning unit includes a cleaning web that cleans the recovery roller, a first roller around which the cleaning web is wound in advance, a second roller that winds the cleaning web supplied from the first roller, and a third roller that presses the cleaning web against the recovery roller to clean the recovery roller. The controller stops a rotation of a rotor of a motor that drives the second roller, in a case where a value corresponding to a torque applied to the rotor exceeds a threshold while the rotor is rotating.

An image forming apparatus includes: an image carrier; an exposing device; a developing device with a developing roller; a development current detector that detects development current between the image carrier and the developing roller; and a hardware processor. Under an image forming condition, the hardware processor causes the exposing device to draw, on the image carrier, a development current-detection pattern that includes a solid image and a halftone image that follows the solid image in an image-conveying direction of the image carrier, causes the developing device to develop the development current-detection pattern, obtains information on a chronological change of the detected development current from the development current detector, and determines whether or not a ghost image due to the solid image occurs based on a temporary drop of the detected development current during development of the halftone image.

An image forming portion applies a bias voltage in which an AC component is superimposed on a DC component between a first carrying member and a second carrying member, and transfers toner from the first carrying member to the second carrying member to form an image on the second carrying member. An AC setting processing portion performs AC calibration to set a magnitude of the AC component of the bias voltage. A potential measurement processing portion measures a surface potential of the first carrying member or the second carrying member based on a target current flowing between the first carrying member and the second carrying member. A drive processing portion executes the AC calibration before measurement of the surface potential in a case where, when measuring the surface potential, an activation condition is satisfied.