A control unit controls a transfer power source in such a manner that a current value detected by a detection unit is a predetermined value while a transfer medium is not held in a transfer portion, and the control unit sets a transfer voltage based on a voltage value applied from the transfer power source to a transfer member. Then, the transfer voltage is applied from the transfer power source to a transfer roller after the leading edge of the transfer medium in the conveyance direction for the transfer medium is held in the transfer portion and before the leading edge is held in a fixing portion. While the transfer voltage is applied, the control unit sets a voltage to be applied from the transfer power source to the transfer member based on the value of current detected by the detection unit.

An image forming apparatus includes a charger, a photoconductor, a charging high-voltage power supply, and circuitry. The charging high-voltage power supply supplies a charging bias to the charger and generates an output value feedback voltage representing a voltage value corresponding to an output current value from the charger to the photoconductor. The circuitry extracts a minimum value of the output value feedback voltage based on the output value feedback voltage generated in a given time. The circuitry calculates a maximum gap value between the charger and the photoconductor based on the minimum value. The circuitry calculates an AC voltage value based on the maximum gap value. The circuitry adds the AC voltage value to a DC voltage value to generate and transmit an output value control signal to the charging high-voltage power supply, to cause the charging high-voltage power supply to adjust the charging bias.

When executing a job which is a series operations for forming images on a single or a plurality of transfer materials and outputting the transfer material(s), started by a start instruction, a control device switches a polarity of a voltage applied by a first transfer power source in response to a switching of a polarity of a voltage applied by a charging power source, and switches a voltage applied by a second transfer power source from a first voltage to a second voltage which is larger in absolute value than the first voltage.

An electrophotographic image forming apparatus includes: an image carrier that carries and conveys a toner image; a charging member arranged in contact with or close to the image carrier; a charging power supply that charges the image carrier; an exposurer that forms a latent image on the charged image carrier; a developing member arranged close to the image carrier; a developing power supply that develops the latent image and forms a toner image on the image carrier; a transfer member that transfers the toner image to a medium; and a hardware processor that controls the image forming apparatus, wherein the hardware processor obtains a potential of an exposure part and a non-exposure part, on the image carrier after the toner image has been transferred to the medium, determines a charging bias based on a difference between the obtained potentials, and determines a developing bias based on the determined charging bias.

In a case where a collection mode in which an exposure unit forms a first potential on a photosensitive member and a developing unit collects discharging toner discharged from the developing unit to a position where the first potential is formed is executed, a potential forming unit forms, on an intermediate transfer member, a potential same as a normal charging polarity of toner and an absolute value greater than an absolute value of the first potential, and a charging power supply applies, to a charging member, a voltage having a polarity same as the normal charging polarity and an absolute value greater than an absolute value of the first potential.

A contact point end portion of a second ring connected to a first ring portion on a power reception portion side protrudes further in the direction of a power reception portion than a contact point end portion of the first ring connected to a spring portion on a power reception portion side.

An electrostatic collecting apparatus includes: a collecting rotating member rotatably arranged opposed to a surface of an object to be cleaned and to which a substance to be collected attaches; an adsorption force generating unit for generating an electrostatic adsorption force between the collecting rotating member and the substance to be collected; a removing member for coming in contact with a circumferential surface of the collecting rotating member, and removing the substance to be collected from the collecting rotating member; and a collecting portion for collecting the substance to be collected, which has been removed from the collecting rotating member by the removing member. The electrostatic collecting apparatus includes an adsorption force reducing unit for partially reducing the electrostatic adsorption force between the substance to be collected, which is borne on the collecting rotating member, and the collecting rotating member at around the circumferential surface of the collecting rotating member.

An image forming apparatus has a photosensitive member, a plurality of corona chargers configured to charge the photosensitive member by corona discharge, a plurality of charge output circuits configured to output a charging voltage being applied to each of the corona chargers, a plurality of abnormal discharge detection circuits configured to output an abnormal discharge detection signal according to abnormal discharge occurring in each of the corona chargers, and a controller configured to have a common input port connected to the abnormal discharge detection circuits wherein the abnormal discharge detection signal output from each of the abnormal discharge detection circuits is input to the controller through the common input port. Each of the abnormal discharge detection circuits is connected to a corresponding one circuit out of the charge output circuits.

A control unit performs control to satisfy T.sub.Va<T T.sub.Vb, where T is a time from a point when irradiation with light by a pre-exposure member is started to a point when a predetermined portion of the photosensitive member which is located at the pre-exposure position when the irradiation is started reaches a charging position, T.sub.Va is a time from the point when the irradiation is started to a point when application of a first voltage is started, and T.sub.Vb is a time from the point when the irradiation is started to a point when application of the second voltage is started.

A power supply apparatus including a transformer, a first rectifier smoothing unit, a separation unit, a second rectifier smoothing unit, a resistor, and a rectifier unit. The first rectifier smoothing unit is configured to rectify and smooth an alternating-current voltage generated in a secondary coil of the transformer. The separation unit configured to use the alternating-current voltage generated in the secondary coil of the transformer as an input and generate an alternating-current voltage, from which alternating-current components are separated, as an output. The second rectifier smoothing unit is configured to rectify and smooth the output of the separation unit. The resistor is connected to a line branched from a line that connects the separation unit to the second rectifier smoothing unit. The rectifier unit is connected in series between the resistor and a reference potential.