An image forming apparatus includes an image carrier, a developing device, a voltage applier, a current detector, a weight detector, and a control device. The control device acts as a first measurer, a second measurer, and an estimator. The first measurer acquires a toner use amount indicating weight per unit area, of the toner that has migrated from the developing agent carrier to the image carrier, according to a detection result provided by the weight detector. The second measurer acquires the developing current from the current detector. The estimator calculates a value of decision coefficient, obtained by dividing variance of an estimated value in a regression model between the toner use amount and the developing current, by variance of a sample value, and estimates deterioration status of the toner, according to the value of the decision coefficient.

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.

A control board configured to be mountable to a first image forming apparatus and to a second image forming apparatus of a type different from a type of the first image forming apparatus, the first image forming apparatus including a first load, the second image forming apparatus including a second load having a function different from a function of the first load. The control board comprising a connector to which the first load is to be connected in a case where the control board is mounted to the first image forming apparatus, and to which the second load is to be connected in a case where the control board is mounted to the second image forming apparatus, a common drive circuit configured to drive the first load and the second load via the connector, and one or more processors.

When, in a state where a developer borne by a developer bearing member is sandwiched by an opposing portion of an image bearing member and the developer bearing member, C denotes capacitance between the image bearing member and the developer bearing member, ΔV denotes a development contrast, Q/S denotes a charge amount per unit area of the developer borne by the developer bearing member, and Δv denotes a peripheral velocity ratio which is a ratio of a peripheral velocity of the developer bearing member to a peripheral velocity of the image bearing member, a first peripheral velocity ratio is set so that |Q/S×Δv|≤|C×ΔV| is satisfied, and a second peripheral velocity ratio which is larger than the first peripheral velocity ratio is set so that |Q/S×Δv|>|C×ΔV| is satisfied.

An image forming apparatus includes an image bearing member, a brush, and a controller. The controller controls so that, in a case where, in a state where a recording material trailing edge in a conveyance direction is sandwiched at a transfer portion, an area of the image bearing member in the conveyance direction where the recording material is sandwiched in a direction perpendicular to the conveyance direction is a first area, and an area of the image bearing member in the conveyance direction where the recording material is not sandwiched is a second area, a first potential difference formed between a surface potential formed on the second area and a brush voltage, which is based on first information, when the second area reaches the brush and a second potential difference formed between the second area surface potential and the brush voltage, which is based on second information, are different.

An image forming apparatus includes: a conveyance section that sequentially conveys a plurality of recording media; a transfer member that transfers an image formed on an image carrier to each of the recording media conveyed by the conveyance section, with a potential difference; a detection section that detects an electrical characteristic value of the transfer member in transferring the image to each of the recording media; and a determination section that determines multi feeding of the recording media, by comparing an electrical characteristic value in transferring the image to each of the recording media with an electrical characteristic value in transferring the image to each of the recording media.

A power supply device that applies a voltage in which a direct-current (DC) voltage and an alternating-current (AC) voltage are superimposed on each other to a charging member that charges an image bearer, includes: an AC voltage generation circuit that generates the AC voltage; a DC voltage generation circuit that generates the DC voltage; a DC current detection circuit provided on an output terminal side of the DC voltage generation circuit, which detects an output DC current flowing into the image bearer; and a reduction circuit that reduces an inflow of an AC current to the DC current detection circuit.

In some examples, a controller can generate operational profiles of printing device components by determining an electrical measurement of a component of a printing device, generate an operational profile of the electrical measurement, compare the operational profile against a baseline operational profile the component, and generate an alert based on the comparison.

An image forming apparatus includes a rotatable photosensitive member, a charging unit, a developing unit, a support frame, and a sensor unit. The sensor unit is detachably attached to the support frame in a direction that intersects a rotation-axis direction of the photosensitive member and includes a potential sensor, a support portion, a fixing portion, an electric board, and a linking portion. The support portion supports the potential sensor at an area from the charging unit to the developing unit in a rotational direction of the photosensitive member. The fixing portion is fixed to the support frame at a position that faces an area from the developing unit to the charging unit in the rotational direction of the photosensitive member. The support portion is positioned with respect to the support frame at a position downstream of the support portion in an attachment direction of the sensor unit.

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.