Abstract: An image forming apparatus, for example, that is capable of accurately writing information into a developing unit or the like having an element is achieved. An image forming apparatus comprises: an attach/detach section to and from which a developing unit having an element into which information can be written and a developer containing section can be attached and detached; a photoconductor on which a latent image can be formed; a writing member for writing information into the element; and an AC voltage supply section for supplying an AC voltage. During a period from a start to an end of an image forming process, the writing member writes information into the element of the developing unit attached to the attach/detach section when the AC voltage supply section is not supplying an AC voltage.

Abstract: An image forming apparatus including a latent image bearing member, a charger to evenly charge a surface of the latent image bearing member, an electrostatic latent image forming device to form an electrostatic latent image on the surface of the latent image bearing member, a developing device to develop the electrostatic latent image into a toner image using toner, a transfer bias application device to apply a transfer bias to an image transfer area where the latent image bearing member faces a recording medium, a pre-transfer neutralizing device to reduce an electric potential at a portion on the surface of the latent image bearing member, a surface electric potential detector to detect an electric potential at the surface of the latent image bearing member, and a radiation amount control device to control an amount of radiation from the pre-transfer neutralizing device based on a detection result obtained by the surface electric potential detector.

Abstract: An image forming apparatus has a first image formation mode for forming an image on an image bearing member by using developer under a first predetermined image forming condition and a second image formation mode for forming an image on an image bearing member by using developer under a second image forming condition which is different from the first predetermined image forming condition and is set so that an amount of consumption of developer with respect to an identical image in the second image formation mode is smaller than that in the first image formation mode, the apparatus includes storing means for storing information on an amount of usage of the image bearing member, and control means for changing the second image forming condition in the second image formation mode depending on the information stored in the storing means.

Abstract: An image forming apparatus, includes: a photoreceptor on which a toner image is formed by a charging device, an image exposure device and a developing device; and a transfer section for transferring the toner image on the photoreceptor. DC bias and AC bias voltage is applied to a development roller of the developing device, and the DC bias and AC bias voltage is set to regular value for an image area on the photoreceptor, and only the AC bias voltage is changed for a non-image area on the photoreceptor.

Abstract: A control system for use with a development process including at least one magnetic roll with a settable speed is provided. The controller is directly or indirectly responsive to a reload feedback signal, which signal is generated in response to changes in output reload performance of the development process. In the case of direct responsiveness, the controller uses one or more reload feedback signals to facilitate magnetic roll speed setting. In the case of indirect responsiveness, the controller uses a reload sensitivity signal, which reload sensitivity signal varies as a function of input digital image content and output reload performance feedback, to facilitate magnetic roll speed setting.

Abstract: In case new and old toners may be mixed, a developing bias is set as follows. The time is first clocked. The number of times toner is replenished from a hopper into a buffer for a clocked period is counted. If a replenishment amount per clock time is a threshold value or higher, considering that new and old toners are mixed, the setting of the developing bias is changed. An electric field intensity between a developing roller and a photoconductor is set to cause normally-charged toner to fly in an image area but not to fly in a background area. No image fogging is therefore generated in the background area. Thus, an image forming apparatus and method capable of preventing low-charged toner and oppositely-charged toner generated by mixing of new and old toners from adhering to the background area of an electrostatic latent image on the photoconductor, thereby avoiding generation of image fogging.

Abstract: Developing bias is set as follows. An electric field intensity between a developing roller and a photoconductor is set to cause normally-charged toner to fly in an image area and not to cause the toner to fly in a background area. Thus, the normally-charged toner does not fly in the background area. The normally-charged toner caused to fly is therefore unlikely to flick low-charged toner and oppositely-charged toner. The low-charged toner and the oppositely-charged toner will not adhere to the background area and cause image fogging. Accordingly, an image forming apparatus can be provided to prevent the low-charged toner and the oppositely-charged toner from adhering to the background area of an electrostatic latent image on the photoconductor and to avoid the occurrence of image fogging in the background area on a printed material.

Abstract: An image forming apparatus includes a transfer bias set up section and a developing bias set up section. The transfer bias set up section sets a transfer bias applied to each transfer member so that the transfer bias applied to a transfer member corresponding to a photosensitive member on the most downstream side is greater than a transfer bias applied to a transfer member other than this transfer member. The developing bias set up section sets a developing bias applied to each developing member to a first developing bias in a single-side printing mode, and sets up the developing bias applied to each developing member in formation of an image on a first surface and in formation of another image on a second surface to a second developing bias lower than the first developing bias when the image formed on the second surface is a color image.

Abstract: An image forming apparatus which predicts VL fluctuations of a photosensitive drum in consideration of a double-sided print mode, and performs an image formation control based on the prediction, and thus always obtains a stable density image. The image forming apparatus performs an appropriate image formation control by controlling an image forming condition based on a photosensitive member rotation time, a photosensitive member stop time, a temperature of an atmospheric environment, an absolute humidity of the atmospheric environment, and whether an image formation that precedes a subsequent image formation is performed in single-sided printing or double-sided printing.

Abstract: An image forming apparatus includes an image supporting member for forming a developer image; a developing unit for forming a developer layer and forming the developer image on the image supporting member using developer of the developer layer; a developer supplying unit for supplying the developer to the developing unit; an image density detection unit for detecting an image density of the developer image; and a control unit for controlling a voltage applied to the developing unit and the developer supplying unit. The control unit corrects the voltage applied to at least one of the developing unit and the developer supplying unit according to the image density detected with the image density detection unit.

Abstract: An image forming apparatus includes an image supporting member for supporting a static latent image; and a developer supporting member for developing the static latent image formed on the image supporting member using developer. It is configured to supply developer to the developer supporting member so that a ratio of a maximum amount of the developer on the image supporting member per unit area with respect to an amount of the developer on the developer supporting member per unit area does not exceed 0.60.

Abstract: A reference developing image is formed on a photoreceptor drum under an image forming condition measured in advance, and the density of this reference developing image is detected. A development bias voltage is corrected based on the detection result, and when a correction value of the development bias voltage exceeds a predetermined range, a reference output voltage of an ATC sensor for detecting the density of toner in a developing device is corrected based on the detected value of humidity around the developing device, the frequency of use of the apparatus, and the agitation stress of developer.

Abstract: A method for calibrating the BID current in an electrophotographic printer includes the steps of measuring electrode capacitance of an empty BID unit, installing the BID unit in an electrophotographic printer, comparing the measured capacitance with a calibration curve to determine the proper current for the BID unit, and adjusting the operating current of the BID unit according to the calibration curve.

Abstract: An image forming apparatus includes an image forming section for forming an image on a recording material with transparent toner; a heater for heating a first image and a second image which are formed on the recording material by the image forming section as transparent images different in toner coverage per unit area; a glossiness detector for detecting glossiness of the first and second images after the first and second images are heated; and a correction section for correcting an image forming condition of the image forming section on the basis of a glossiness toner coverage characteristic obtained by a detection result of the detector.

Abstract: An image forming apparatus includes: a plurality of image carriers on each surface of which an electrostatic latent image is formed, each of the image carriers being attachable and detachable; a plurality of development units each adhering a toner to the electrostatic latent image carried on corresponding one of the image carriers, the development units adhering toners that are different from each other, a plurality of transfer units that transfer the toners adhering to the image carriers to a recording medium; an order detection unit that detects an arrangement order of the loaded image carriers; and an image formation condition setting unit that sets an image formation condition for at least one of the developing unit and each of the image carriers based on the arrangement order detected by the order detection unit.

Abstract: An image forming apparatus includes an alternating-current high-voltage power supply generating an alternating-current bias for detection of the remaining amount of toner. The alternating-current high-voltage power supply includes a piezoelectric transformer, a piezoelectric-transformer driving unit, a piezoelectric-transformer driving-signal generating unit, a voltage detecting unit, a voltage setting unit, and an controlling unit that feeds back a difference signal between a detection level signal supplied from a detection signal detecting unit and a setting signal supplied from the voltage setting unit to the piezoelectric-transformer driving-signal generating unit to control an output voltage from the piezoelectric-transformer.

Abstract: A developing apparatus includes a developer carrying member rotatably provided for carrying a developer; a regulating member that has conductivity, and is provided to be capable of being in contact with the developer carrying member for regulating a amount of the developer carried by the developer carrying member; a power supply that applies voltage to the regulating member; a deformation detecting unit that detects information relating to the deformation of the developer carrying member; and a control unit that controls the power supply to apply a correction voltage when a deformed portion of the developer carrying member passes through the regulating member in order that the amount of the developer carried by the developer carrying member in the circumferential direction is in uniform based on a result of the detection by the deformation detecting unit.

Abstract: A developing device and image forming apparatus are provided, wherein high quality images, in which generation of development hysteresis (ghost image) is alleviated, are obtained over a long period using a hybrid development method comprising a toner-supplying developer supporting member and a toner-collecting developer supporting member. Bias voltage is applied in the direction in which the toner is supplied to the toner supporting member in the toner supply region and the toner collection region of the toner-supplying developer supporting member and the toner-collecting developer supporting member respectively so that the toner collecting capability in the toner collection region is higher than the toner collecting capability in the toner supply region.

Abstract: An image forming apparatus includes an auxiliary charging member contacting an image bearing member and for being supplied with a bias of an identical polarity to a normal charge polarity of toner at a position downstream from a transfer portion where a transfer member is located and upstream from a charging portion where a charging member is located with respect to a rotation direction of the image bearing member. When rotation of the image bearing member is stopped and then resumed, application of a toner transfer bias to the transfer member is started before a contact position between the image bearing member and the auxiliary charging member during the rotation stop of the image bearing member first reaches the transfer portion.

Abstract: An image forming apparatus includes a charge unit, an exposure unit, an exposure voltage detector, a development unit, and a concentration detector. The exposure voltage detector detects a potential of latent image formed as a test pattern on an image carrier. The concentration detector detects concentration of developed test pattern. The image forming apparatus further includes an exposure power controller, an exposure ratio controller, a charging voltage controller, a development bias voltage controller, and an image forming condition adjustment controller. A suitable image forming condition is computed using test patterns formed by changing combinations of charging voltage, exposure power, and exposure duty. The charging voltage is changed in two levels or more. The exposure power is changed in three levels or more. The exposure duty per unit area is changed in two levels or more.

Abstract: An image forming apparatus according to the present invention includes an image carrier, a charging section that electrically charges the image carrier, an exposure section that exposes the image carrier to light to form a latent image, a development section that develops the latent image by means of a liquid developer containing carrier and toner particles, a first squeezing roller that is held in contact with the image carrier carrying an image developed by the development section and adapted to bear a bias voltage Vs1 applied thereto, a second squeezing roller that is held in contact with the image carrier squeezed by the first squeezing roller and adapted to bear a bias voltage Vs2 applied thereto, and a transfer member that is held in contact with the image carrier squeezed by the second squeezing roller and adapted to receive the image transferred thereto, the absolute value of the bias voltage Vs1 and the absolute value of the bias voltage Vs2 showing a relationship of |Vs1|>|Vs2|.

Abstract: An image-forming device includes an image acquiring unit, an image forming unit, a determining unit, and a controller. The image acquiring unit acquires image data for one page. The image forming unit forms an image based on the image data. The image forming unit includes a developing roller, a supply roller, and a bias applying unit. The developing roller carries a developer. The supply roller supplies the developer to the developing roller. The bias applying unit applies a first voltage between the developing roller and the supply roller in a first mode, and applies a second voltage between the developing roller and the supply roller in a second mode. The determining unit determines whether the image data includes a part having density greater than or equal to a prescribed density.

Abstract: Upon receiving a request to control developing bias voltage, first and second square-wave signal output units output first and second square-wave signals, respectively. When a rising edge of the first square-wave signal coincides with a rising edge of the second square-wave signal, the rising edge of the second square-wave signal is advanced with respect to the rising edge of the first square-wave signal. When a falling edge of the first square-wave signal coincides with a falling edge of the second square-wave signal, the falling edge of the second square-wave signal is delayed with respect to the falling edge of the first square-wave signal. Subsequently, a voltage-controlling square-wave signal for controlling developing bias voltage is generated based on the first and second square-wave signals.

Abstract: An amount of toner adhered to a toner image formed on the photosensitive drum using decolorizing toner when forming an image is controlled to 0.75 (mg/cm2) or below. As a result, a toner image formed on a paper is erased satisfactorily for the purpose of reusing the paper and the image density remaining on the paper is lowered.

Abstract: A developing device capable of improving the image density and the dot reproducibility, and an image forming apparatus including the same are provided. A developing device applies an alternating voltage superimposed on a direct current voltage to a developing roller to thereby develop an electrostatic latent image formed on a photoreceptor with toner. A bias voltage waveform superimposed at this time has an original period (first period) in which each of a development-side electrical potential and an opposite development-side electrical potential is applied one time and a period (second period) in which a Vpp is gradually increased from the initial value to the maximum value.

Abstract: An image forming apparatus forms images. A developer bearing body receives a first voltage and supplies developer to the electrostatic latent image formed on an image bearing body. A supplying member receives a second voltage and supplies the developer to said developer bearing body. A detector detects at least one of an environmental condition, e.g., temperature and humidity outside of an apparatus and an environmental condition e.g., temperature inside of the apparatus. A controller controls the difference between the first voltage and the second voltage in accordance the environmental conditions. The controller makes a decision to determine whether the outside temperature is not lower than a first reference, whether outside humidity is not higher than a second reference, and whether inside temperature is not lower than a third reference. If the above criteria are met, the controller decreases the absolute value of the difference.

Abstract: To generate a toner cloud in a development system, a first potential is applied to a donor roll for a first pulse time to project toner from the donor roll toward a photoreceptor; a second potential is applied to the donor roll for a second pulse time to slow the speed at which the toner is projected toward the photoreceptor; a third potential is applied to the donor roll for a third pulse time to hold toner between the donor roll and the photoreceptor; and a fourth potential is applied to the donor roll for a fourth pulse time to urge undeveloped toner to the surface of the donor roll. Voltages may also be applied for selectivity removing toner from a donor roll.

Abstract: High quality images are provided by controlling development conditions based on the proportion of the toner layer potential difference, which a difference between the toner layer potential and electrostatic latent image potential, to the development contrast potential difference, which is a difference between the development bias potential and electrostatic latent image potential. The control section for controlling a development power supply controls the voltage supplied by the development power supply, based on the toner layer potential difference and development contrast potential difference in the development section. This arrangement ensures formation of high-quality images free from concentration of toner.

Abstract: Provided is an image forming apparatus including a charging device for charging a photoreceptor drum, a developing device for developing an electrostatic latent image formed on the photoreceptor drum, a developing bias applying device for applying a developing bias voltage to the developing device, a toner image density sensor for detecting an image density of a toner image formed on the photoreceptor drum, and a control portion for controlling an output value of the developing bias applying device, in which the control portion adjusts the developing bias voltage based on an average print coverage of document in previous printing jobs.

Abstract: An image forming apparatus includes a control device that calculates a developing ability of the developing device based on a detection value detected by an optical detection device from the plural toner patches. The control device adjusts an image formation condition based on the calculated developing ability. A factor detection device is provided to detect a contributing factor that causes the developing ability to largely change after the last adjustment of the image formation condition. The control device controls image formation such that when the factor detection device does not detect the contribution factor and a developing ability calculated this time is different from that calculated last time (as to a part of the plural toner patches), the plural toner patches are formed based on a prescribed fixed image formation condition so that an attraction amount of toner attracting to the plural toner patches enter a prescribed range detectable for the optical detection device.

Abstract: The developing apparatus of the present invention is a developing apparatus that develops an electrostatic latent image using a two-component developer containing a toner and a carrier; wherein the developing apparatus has a developing roller that rotates with a developer adhering to the peripheral surface thereof in order to transfer the developer to an electrostatic latent image; a bias unit having a DC voltage applicator that applies a prescribed DC voltage to the developing roller and an AC voltage applicator that applies an AC voltage to the developing roller; a timer that measures the developing apparatus drive time; a measuring unit that measures the amount of developing performed by the developing apparatus; and a bias adjustor whereby the amplitude component of the AC voltage applied by the AC voltage applicator is lowered based on an increase in output of the timer and/or the measuring unit.

Abstract: An image forming apparatus includes: a moving speed ratio change section which changes a circumferential speed ratio between a surface of a developer bearing member and a surface of an image carrier; and a memory section which stores a target value of fog toner. After the circumferential speed ratio has been changed by the moving speed ratio change section, a controller determines a fog control parameter based on comparing the value detected by the fog toner detection section with the target value stored in the memory section. After then, and the controller controls the moving speed ratio change section to return the circumferential speed ratio to the circumferential speed ratio prior to the change.

Abstract: An image forming apparatus includes an image supporting member; a developer supporting member for attaching developer to the image supporting member to form a developer image; a regulation member for forming a thin layer of the developer on the developer supporting member; a charge adjustment member for receiving a charge adjustment voltage and contacting with the thin layer of the developer formed on the developer supporting member to adjust a charge amount of the developer; and a charge adjustment voltage switching unit for switching the charge adjustment voltage applied to the charge adjustment member between an image forming voltage upon forming an image and a non-image forming voltage during a preparation operation.

Abstract: To prevent image defects such as fog and irregularities caused by the accumulation of the oppositely charged toner by flying the toner toward a photoreceptor to compulsorily consume the toner even though the toner is oppositely charged toner having a small charged amount. A potential difference between the photoreceptor and the development roller is set at a value at which the normally charged toner on the development roller can be flown toward the photoreceptor in the development phase at the time of compulsorily consuming the toner, and this potential difference is set at a value at which the flown normally charged toner can be returned to the development roller in the recovery phase.

Abstract: A method for controlling an image forming apparatus is disclosed. An image pattern is developed both by a DC developing process using a developing bias voltage of only a DC voltage and by an AC+DC developing process using a developing bias voltage of a DC voltage overlapped with an AC voltage. The densities of the two developed image patterns is compared with each other to implement toner density control.

Abstract: The image forming apparatus include: a resistance detection section (14) for measuring a volume resistivity of a two component developer (11) on a surface of a developer bearing member (12); a resistance memory section (16) for storing therein a preset volume resistivity; a resistance comparison section (15) for comparing the volume resistivity of the two component developer (11) which has been measured by the resistance detection section (14) with the preset volume resistivity stored in the resistance memory section (16); and a control section (17) for carrying out a process for replacing the two component developer or carrier if the volume resistivity of the two component developer (11) is lower than the preset volume resistivity.

Abstract: An image forming apparatus has a plurality of developing devices each including a developing member carrying and transferring developer toward a developing region and a charging member charging developer carried by the developing member, a development bias applying device applying an AC development bias voltage to the developing member, and a charge bias applying device applying to the charging member an AC charge bias voltage having a phase synchronized with the AC development bias voltage and representing a charge bias voltage value causing an offset potential difference with respect to the AC development bias voltage in a phase on one of positive and negative sides. The charge bias voltage applied by the charge bias applying device provided for each of the developing devices has the same voltage value as the charge bias voltages applied by the charge bias applying devices of the other charge bias applying devices.

Abstract: A device for measuring electrostatic charge amount of toner is provided. The device comprises a hollow toner suction port for sucking the toner from a toner substrate and a means for measuring electrostatic charge amount of the sucked toner. The toner suction port forms a hermetically sealed space with the toner substrate.

Abstract: There is provided an image forming apparatus, including: a image bearing member; a charging member; a developing device; a transfer member that forms a transfer portion, thereby transferring a toner image on the image bearing member, to a transfer material; a first toner charging member disposed on the lower stream side of the transfer portion and on the upper stream side of the charging member in a rotating direction of the image bearing member, thereby charging the toner on the image bearing member by applying voltage; wherein the developing device develops the electrostatic latent image and recovers the toner charged by the first toner charging member, the image forming apparatus further including: a first current detecting portion that detects a current value flowing through the first toner charging member; and a changing portion that changes a transfer condition according to the detected current value.

Abstract: An image forming apparatus includes a photoconductive medium electrified by an electrifying apparatus to a predetermined electric potential, a plurality of color developing apparatuses which are fixed around the photoconductive medium, each color developing apparatus having a developing roller to adhere a predetermined color toner to an electrostatic latent image formed on the photoconductive medium by a laser scanning unit, and a supplying roller to supply a toner to the developing roller, a voltage supplying apparatus to apply a predetermined bias voltage to the developing roller and the supplying roller, and a controlling apparatus to control a degree and a timing of applying the bias voltages to the developing roller and the supplying roller to control a movement state of the toner between the supplying roller and the developing roller.

Abstract: An image forming apparatus is provided capable of preventing fog from happening and obtaining more stable image density, which includes an image carrier; a charging section for charging surface of the image carrier; an exposing section for forming an electrostatic latent image on the image carrier; a developing section for making developer adhere to the electrostatic latent image formed on the image carrier so as to form a visible image; a transferring section to transfer the visible image onto a transfer member; a density detecting section to detect a density of the visible image; a development voltage setting section to set a development; a charge voltage setting section to set a difference between the charge voltage and the development into a value in a predetermined range; and an exposure quantity setting section to set an appointed exposure quantity with respect to the charge voltage.

Abstract: A wet electrophotographic image forming apparatus detects color per print page and executes printing by turning on only the development bias of a developing unit to be used for printing. The wet electrophotographic image forming apparatus has a color detecting unit for detecting colors for developing the electrostatic latent images per print page; and a controller for selectively turning on and turning off development bias applied to developing rollers of the plurality of the developing units according to the colors detected by the color detecting unit.

Abstract: A method for adjusting a developing device including a magnetic roll for holding a two-component developer composed of a carrier and toner filled in a developing tank in a brush state, and a developing roll for developing an electrostatic latent image formed in an image carrier by holding toner conveyed from the magnetic roll, includes a bias voltage adjustment step for adjusting a conveyance amount of toner from the magnetic roll to the developing roll by adjusting bias voltages applied to the magnetic roll and the developing roll respectively, and a mixing ratio adjustment step for adjusting a conveyance amount of the toner by adjusting a mixing ratio of the two-component developer.

Abstract: A development station that improves toner halftone dot development over a wide range of environmental conditions includes a developer housing for retaining semi-conductive carrier particles and toner particles, a first magnetic roll having a stationary core with at least one magnet and a sleeve having longitudinal grooves that rotates about the stationary core of the first magnetic roll, a second magnetic roll having a stationary core with at least one magnet and a sleeve having longitudinal grooves that rotates about the stationary core of the second magnetic roll, an environmental sensor for generating an environmental condition signal, a variable voltage supply coupled to the first magnetic roll and the second magnetic roll, and a control circuit for adjusting an output level for the variable voltage supply.

Abstract: An image forming apparatus includes a density detector to detect a density of an image to be printed, and an image density controller to adjust a toner supply amount and a developing bias based on a detection result of the density detector to thereby adjust a density of the image.

Abstract: An amount of toner transfer on a reference pattern is calculated by using an optical detecting unit that detects both regular reflection light and diffuse reflection light from a detection target simultaneously, based on a relative ratio between a value obtained by subtracting a result of multiplying a “diffuse reflection output” by a “minimum value of a ratio between a regular reflection output and the diffuse reflection output” from the “regular reflection output” of the density detection reference pattern, and a value obtained by subtracting a result of multiplying the “diffuse reflection output” by a “minimum value of a ratio between the regular reflection output and the diffuse reflection output” from the “regular reflection output” in the background of a transfer belt or an intermediate transfer body.

Abstract: An image forming apparatus in which a toner layer is formed onto a developing roller which is restricted by a toner restricting member and rotated, toner is supplied to a photosensitive drum by the toner layer, and a toner image is formed onto the drum and transferred onto a print medium, thereby forming an image. The apparatus has: a counter which counts the toner image, on a dot unit basis, formed on the drum and a control unit which stops the rotation of the developing roller for a predetermined time and intermittently executes a series of image forming operation when a count value is equal to or larger than a predetermined reference value. The occurrence of filming is prevented by preventing an increase in toner temperature.

Abstract: A development device configured to develop an electrostatic image formed on an image bearing member by applying a developing bias in a development operation includes a developer bearing member configured to bear a developer, a bias applying unit configured to apply an input waveform bias including an alternating component to the developer bearing member, a bias detection unit configured to detect information concerning an output waveform bias generated on the developer bearing member when the bias applying unit applies the input waveform bias to the developer bearing member, and a controller configured to execute a mode for controlling the developing bias to be applied to the developer bearing member based on the input waveform bias and the output waveform bias.

Abstract: An image forming apparatus includes: an image carrying body; a latent image forming unit to form an electrostatic latent image on the image carrying body; a developing unit to develop the electrostatic latent image on the image carrying body to form a toner image, the developing unit including a developing agent carrying body to carry a developing agent in a development region, and a direct-current power supply and an alternating-current power supply, both applying a developing bias voltage to the developing agent carrying body, the developing bias voltage generated by superimposing a direct-current voltage to an alternating voltage; a printing rate detecting unit to detect a printing rate; and a control unit to control the alternating-current power supply, wherein the control unit controls an output of the alternating-current power supply based on a detection result of the printing rate detecting unit.

Abstract: An image forming apparatus changes over an electric potential on an image bearing member in response to an attenuation region in which a remaining potential on a developing member is attenuating after a developing bias applied to the developing member has been turned off after completion of an image forming operations. Accordingly, it is possible to mitigate adherence of developer due to a large potential difference between the developing member and the image bearing member.