Abstract: An image forming apparatus includes a latent image bearing body that bears a latent image, a charging member applied with a charging voltage and configured to charge a surface of the latent image bearing body, a developer bearing body applied with a developing voltage and configured to develop the latent image with a developer, a developer regulating member applied with a regulating-member-application voltage and configured to form a layer of the developer on the developer bearing body, and a voltage switching unit configured to switch the regulating-member-application voltage. In a non-image-forming period, the voltage switching unit switches the regulating-member-application voltage from a voltage set for an image forming period to a different voltage.

Abstract: In a method of checking a trouble point in a xerographic copying apparatus of the invention, a sequence code is selected from a plurality of sequence codes to distinguish a plurality of sequences to stop an operation of the xerographic copying apparatus in any one process of a plurality of print processing processes for print output of a sheet, an operation of a photoconductor in a state where toner is attached is stopped in any one process among the plurality of print processing processes in accordance with the sequence corresponding to the selected sequence code, and any one trouble point is checked, and therefore, the point where a poor image is generated is suitably grasped.

Abstract: An image forming apparatus including (a) a ? conversion unit having a ? conversion table ??i of a first one Vcont? of a designation development contrast in a case that a development contrast correction amount ?Vcont1 is a first value, and a ? conversion table ??i, different from the ? conversion table ??i, of a second one Vcont?, different from the first one Vcont?, of the designation development contrast in a case that the development contrast correction amount ?Vcont1 is a second value different from the first value, and (b) an arithmetic operation unit for calculating a ? conversion table ?Nowi of a third one VcontNow of the designation development contrast in a case that the development contrast correction amount ?Vcont1 is a third value, based on a formula: ?Nowi=??i+(??i???i)×(Vcont??VcontNow/(Vcont??Vcont?), wherein the subscript i is a value of an output density signal in the ? conversion table.

Abstract: An image forming apparatus having a developer container containing a developer and a developer carrying member for carrying the developer and adapted to switch an AC voltage to be applied to the developer carrying member, the apparatus comprising a detecting member for detecting the amount of developer in the developer container and a processing portion for determining the amount of developer in the developer container according to the value output by the detecting member when the AC voltage is applied to the developer carrying member, the processing portion being adapted to determine the amount of developer by executing a process that corresponds to the operation of switching the AC voltage.

Abstract: A disclosed image forming apparatus comprises: a conveying belt conveying a record medium attracted to the conveying belt using electrostatic force; a recording head for ejecting droplets on the record medium and forming an image; and a voltage waveform applying unit applying voltage waveforms, in which the shape of a positive waveform and the shape of a negative waveform are different, to the conveying belt so as to apply positive and negative electric charge thereto and generate the electrostatic force.

Abstract: An image forming apparatus, which reduces toner spatter and produces a good quality image when forming a toner image using the direct recording method. An image forming part includes: a toner carrier for carrying toner; and toner controlling means, which is disposed between the toner carrier and recording paper on which the toner is made to adhere, and which has a plurality of toner passage holes, the toner controlling means having a control electrode for controlling the passage of toner on the toner carrier side surface in the area around the toner passage hole, and forming a toner image by causing the toner to fly to the recording paper, and the image forming apparatus having liquid applying/humidifying means for either applying a liquid to or humidifying the imaging surface of the recording paper prior to forming a toner image.

Abstract: An image forming apparatus includes an image carrying member, an image writing unit, a development unit, a transfer device, a charging device, and a toner charge control device. The image writing unit forms a latent image on the image carrying member, which is developed as a toner image by the development unit, and the toner image is transferred to a transfer member by the transfer device. The charging device charges the image carrying member and toner on the image carrying member. The toner charge control device, controls a polarity of charge and charging voltage level of toner remaining on the image carrying member. The toner charge control device includes an endless belt having a surface made of a conductive material, a support member extending the endless belt pressed against the image carrying member, and a bias voltage applicator for supplying a voltage to the surface of the endless belt.

Abstract: An image forming apparatus includes a charging device to electrically charge a photosensitive member, an exposure unit to expose the charged photosensitive member to light, a development device to develop, with a developer, a latent image formed on the photosensitive member by the exposure unit, and a development bias voltage generating circuit to apply a development bias voltage to the development device. The development bias voltage generating circuit includes a transformer, a capacitor connected to one end of the transformer, first-fourth switching elements, a power source to supply a voltage to the first and third switching elements, and a control unit to control an on and off action of the first to fourth switching elements and independently control the voltages applied by the power source to the first and third switching elements.

Abstract: This invention relates to a developing unit for maintaining constant density in an electrophotographic imaging process. The developing unit has a developer roll, wherein the developer roll provides a surface and a first voltage is applied to the developer roll; a skive device, wherein the skive device is positioned in contact with the developer roll and a second voltage is applied to the skive device; a cleaning device for the developer roll, wherein the cleaning device is in contact with the developer roll; and an ink container, wherein the developer roll and the cleaning device are inside the ink container. It is preferred that a current measuring device is present to measure current flow between skive device and the developer, or a voltage meter is present to measure a voltage across a known resistor that is in series with the power supply to the skive device.

Abstract: There is described an image forming apparatus, which makes it possible to suppress quality degradation of an image on the basis of a developing electric current profile without optically detecting density of a patch image. The image forming apparatus includes: a developing current detecting sensor to detect a developing current; and a control section that conducts consecutive operations of: creating a detecting-use image pattern for detecting a developing characteristic, by aligning a plurality of image patterns, which are different from each other in density; forming a latent image of the detecting-use image pattern onto the photoreceptor element; finding a developing electric current profile, which represents a transition of the developing electric current flowing during an operation of developing the detecting-use image pattern, from an outputted signal of the developing current; and changing an image forming condition, based on the developing electric current profile found by the finding operation.

Abstract: An image forming device includes a developing unit, which is removably inserted in the image forming device, and the developing unit includes an accumulating chamber, a developing member, and a storage medium. The accumulating chamber accumulates developer. The developing member moves the developer onto an image carrier and carries out an image forming process. The storage medium stores control information for determining a developing bias to be applied to the developing member, and usage performance information of the developing unit necessary for determining the developing bias.

Abstract: The invention provides an image forming apparatus having: an image holding member; an image holding member; a charging unit; a latent image-forming unit; a development unit; a measuring unit; and a control unit. The image holding member has a substrate having a surface having regular reflectance in a range of about 30% to about 95% with respect to light having a first wavelength and a subbing layer having a light transmittance of about 50% or greater per unit thickness of the layer with respect to light having the first wavelength and a photosensitive layer having absorption with respect to light having a second wavelength that is different from the first wavelength.

Abstract: An image forming apparatus that includes: an image forming portion for forming an image in accordance with image data contained in an input command; and a controller for controlling the image forming portion, and is constructed such that the controller includes: a mode switch for switching the image forming portion from a standby mode in which image forming is instantly enabled into a power-saving mode in which power supply to the image forming portion is partially stopped when no subsequent command has been received after a predetermined period elapsed from when image forming portion was operated last; a mode restoring portion for restoring the image forming portion from power-saving mode to standby mode when a subsequent command is received; and an image quality controller for performing image quality control of the image every time a predetermined time elapsed from when the image forming portion was last operated, and the image quality controller starts execution of the image quality control before the mod

Abstract: The development apparatus that develops an electrostatic latent image formed on an image carrier comprises: a developer roller operable to carry toner on a circumferential surface thereof and develop the electrostatic latent image using the toner; a supply roller operable to perform toner supply to the developer roller; a voltage applier operable to apply a bias voltage V1 to the developer roller and apply a bias voltage V2 to the supply roller; and a controller operable to control the voltage applier in a toner compulsive consumption mode so that a value obtained by subtracting an average S2 of the bias voltage V2 per unit time from an average S1 of the bias voltage V1 per unit time indicates the same polarity as a normal charging polarity of the toner. Here, the toner compulsive consumption mode performs development to compulsively consume the toner carried on the circumferential surface of the developer roller.

Abstract: The first direct-current bias power supply applying the first direct-current bias Vdc1 and the first alternating-current bias power supply applying the first alternating-current bias Vac1 are connected to a development roller. The second direct-current bias power supply applying the second direct-current bias Vdc2 and the second alternating-current bias power supply applying the second alternating-current bias Vac2 are connected to a magnetic roller. The peak-to-peak value Vpp of the first alternating-current bias Vac1 applied to the development roller remains the same, and the second alternating-current bias Vac2 that is in phase with the first alternating-current bias Vac1 and that has a peak-to-peak value of a predetermined value or above is applied to the magnetic roller. Thus, the potential difference between the peak voltage of the development bias on the opposite polarity side to the polarity of the toner and the peak voltage of a supply bias is set at a predetermined value or below.

Abstract: An image forming apparatus including: an image bearing member having a photoconductive layer of a capacitance per unit area of 1.7×10?6 (F/m2) or more; and a developing device having a developer carrying member to which development voltage is applied for developing a latent image to form a toner image on the image bearing member, wherein the following expression is satisfied: ? Q M ? ? 0.

Abstract: A supplying roller supplies toner to a developing roller which develops the electrostatic latent image formed on a photoconductive drum. The controller controls the supply to output first and second voltages to the developing roller and supplying roller. A detector generates a signal indicative of remaining toner. The voltage controller performs voltage correction according to the signal either in a first mode where the first voltage has a smaller value when the signal has become below a reference than when the signal is above the reference, or in a second mode where the first voltage has a smaller value when the signal has become below the reference than when the signal is above the reference, and a difference between the first and second voltages has a larger value when the signal has become below the reference than when the signal is above the reference.

Abstract: An electrostatographic apparatus and method of forming a toner image on a receiver using a segmented roller in order to improve transfer of a pigmented toner image to a receiver. The pigmented toner image is applied using the segmented roller and is then transferred to a receiver sheet.

Abstract: An image forming apparatus includes a rotatable photosensitive drum, a charging apparatus to which a charging voltage is applied, an exposure apparatus forming an electrostatic image, a developing apparatus to which a development voltage is applied, a timer measuring an image formation time lapsed from start of rotation of the photosensitive drum and an image formation stop time lapsed from stop of the rotation of the photosensitive drum, and a temperature and humidity sensor detecting a temperature and a humidity of an atmosphere environment around the photosensitive drum. When the humidity is low, a charging voltage is controlled based on a measured result of the timer and detected results of the temperature and humidity sensor. When the humidity is high, the charging voltage is controlled based on the measured result of the timer and the temperature detected result of the temperature and humidity sensor without using humidity information.

Abstract: In an image density correction method in accordance with an embodiment of the present invention, an image density correction is carried out by obtaining an actual toner amount through obtaining a density of a between-sheet patch image having been formed during continuous printing, reconstructing relational characteristics in which the actual toner amount is associated with each variation in developing biases, by considering that the actual toner amount and a reference toner amount are to be made in agreement, when a determination that the actual toner amount disagrees with the reference toner amount is made, and resetting a developing bias for realizing the reference toner amount based on the reconstructed relational characteristics and the reference toner amount. By this means, a high quality image can be obtained by suppressing color fluctuations with printing efficiency maintained at a high level even if large color fluctuations occur during continuous printing.

Abstract: The image forming apparatus includes image forming parts, a developing device and a cleaner to clean at least the intermediate transfer material or the transfer device, wherein at the image forming operation starting time, in each image forming part, after starting the charging, the application of the developing bias is started before the top end of the charging portion of the image bearing member surface reaches a developing area in which the image bearing member and the developer bearing member are set against each other, and from among the areas on the image bearing member in which the charging is not yet performed in each image forming part, in case each area having passed the developing area when the developing bias is applied is brought into contact with the intermediate transfer member, the contact area with each area in the intermediate transfer member is controlled without superposing on the intermediate transfer member.

Abstract: When an image forming apparatus, after a feeding error of a recording material occurs in a fixing device, re-forms on the recording material an image corresponding to image data which image was formed on a sheet which caused the feeding error, an image forming condition is caused to be different from an operation condition used when the feeding error has occurred. This makes it possible to prevent a JAM corresponding to the same image from recurring in the fixing device.

Abstract: An image forming apparatus including: an image forming section for forming an image, the image forming section including a photoconductor, a charging unit, a developing unit, a toner supply unit which supplies a toner to said developing unit, and a developing bias power supply section which supplies a developing bias voltage to said developing unit; and a controller that activates said image forming section, determines a target value of a charging potential of said photoconductor and/or a developing bias voltage, for forming the image, and controls the charging unit and/or the developing bias power supply section in accordance with a determined result, wherein when an absolute value of the determined target value of the charging potential or an absolute value of the determined developing bias voltage is larger than a prescribed value, said controller controls replacement of a prescribed amount of a toner in the developing unit.

Abstract: The residual potential and charging potential of the surface of a photosensitive drum 20, or the charging potential and exposure potential of the surface of the photosensitive drum 20 are detected by an exposure sensor 28. The lifetime of the photosensitive drum 20 is judged in accordance with the difference between the detected charging potential and residual potential, or the difference between the detected charging potential and exposure potential.

Abstract: There is disclosed an image forming apparatus includes an image bearing member; a charging device to charge the image bearing member; an exposing device to form a latent image on the image bearing member; a developing device to form a toner image on the image bearing member; a transferring device to transfer the toner image onto an intermediate transfer member by applying a transfer bias voltage; an image stabilization controlling section for keeping a density of the toner image transferred onto the intermediate transfer member within a predetermined range; a transfer output controlling section for controlling a transfer output based on a density of a toner patch image; and an overall controlling section to control both the image stabilization controlling section and the transfer output controlling section, in such a manner that the image stabilization controlling operation is conducted preceding to the transfer output controlling operation.

Abstract: An image forming apparatus includes a plurality of developing units to form a color image using at least a two pass developing process by developing electrostatic latent image with toners having different colors and polarities when performing a first pass of the developing process, and an exposing unit to form a tri-level potential on a photosensitive medium, in which a development applied voltage applied to a second developing unit among a first developing unit and second developing unit of the plurality of developing units operating during the first pass of the developing process is divided into a development voltage Vd, a collection voltage Vc, and at least one intermediate voltage Vn.

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: A developer device applies bias voltage including an alternating-current component equal to or larger than a value corresponding to a developing electric field of 9 V/?m to a developing roller. The bias voltage is set to apply developer to a latent image on a photosensitive element to develop the image in an image forming mode. The bias voltage is set so that a difference between an area central potential and a surface potential of the photosensitive element is shifted to a direction attracting the normally charged developer to a developer carrier, in relation to a difference between an area central potential and a surface potential of the image carrier in the latent image section in the image forming mode, and a supply amount of the developer to the photosensitive element is smaller than that in the latent image section in the image forming mode.

Abstract: The developing device according to the present invention includes a developing tank for containing two-component developer, a toner density sensor, and a toner cartridge. Further, the developing device according to the present invention includes a control section for inputting, to the toner density sensor, a control voltage (Vc) for correcting a sensor output. The control section sets the control voltage (Vc), by using a standard control voltage having been set so as to correspond to each of the stirring velocities, so that a sensor output (Vo) has a value within a range indicative of predetermined toner density. With the arrangement, it is possible to set the toner density sensor so that the toner density sensor operates in the most suitable manner so as to correspond to each of the stirring velocities, thereby realizing a developing device capable of detecting toner density with high accuracy.

Abstract: A developing unit has a voltage-applicator (80) to apply a developing bias voltage to a developing roller (72). The voltage-applicator (80) applies the developing bias voltage for a first duration to apply an AC voltage having a rectangular waveform, and a second duration to stop applying the AC voltage. The AC voltage has a duty ratio of 50% or more in a direction for causing toner to develop an electrostatic latent image. The number of cycles of the AC voltage in the first duration is two or more, and the AC voltage has a voltage in a direction for pulling the toner back to the developing roller, just before transition to the second duration. The developing unit suppresses occurrence of image unevenness due to a fluctuation in developing gap. Thus, an image forming apparatus equipped with the developing unit forms a high-quality image while suppressing image unevenness.

Abstract: In an implementation of a printing system, an electrophotographic imaging plate electrostatically attracts a first concentration of an ink having a particular color. A developer unit is biased with a developer voltage and the first concentration of the ink is transferred onto the electrophotographic imaging plate from the developer unit according to the developer voltage. The electrophotographic imaging plate then electrostatically attracts a second concentration of the ink. The developer unit is biased with an adjusted developer voltage and the second concentration of the ink is transferred onto the electrophotographic imaging plate from the developer unit according to the adjusted developer voltage.

Abstract: An image forming apparatus having a touchdown-development type developing apparatus, in which a toner collecting roller that collects scattered toner suspended in the vicinity of a toner holding body and a two-component developer holding body is arranged on the downstream side in a rotational direction of the two-component developer holding body from a closest position of the two-component developer holding body and the toner holding body, and between the two-component developer holding body and the housing wall, and further, bias means that applies a bias voltage for collecting the scattered toner to the toner collecting roller, and image density sensing means for sensing a density of a toner image developed on the electrostatic latent image holding body surface or a toner image on a transfer body onto which the toner image developed on the electrostatic latent image holding body surface is transferred to control the bias voltage are provided.

Abstract: A developing device includes a developing housing which faces an image carrier on which an electrostatic latent image is carried and stores a developer which contains toner and magnetic carrier; a developer carrier that is disposed apart from the image carrier in the developing housing and carries and transports the developer; a developing bias applying unit that is disposed between the image carrier and the developer carrier and applies a developing bias comprising an AC component and a DC component which is superposed to a DC component; a volume resistivity detecting unit which detects a volume resistivity of the developer on the developer carrier; and a developing bias adjusting unit which sets the AC component of the developing bias to a reference value when the volume resistivity of the developer detected by the volume resistivity detecting unit falls within a given range, and corrects the AC component of the developing bias such that an image quality evaluation parameter falls within an allowable range

Abstract: An image forming apparatus includes an image former which comprises a photosensitive body and a developing device to apply a developer to the photosensitive body, a power supply which supplies developing voltage to the developing device, a detector which detects a density of an image formed by the image former, and a controller which controls the power supply to adjust a level of the developing voltage if the detected density is out of a permissible range.

Abstract: Provided is a development technique of supplying a developing bias voltage having DC and AC components to a developing roller thereby to supply a developer to a photosensitive surface of a photosensitive material, which can contribute to improvement of the image quality of an image to be developed. The image forming apparatus, includes: a developing roller for supplying a developer to a photosensitive surface of a photosensitive material carrying an electrostatic latent image thereby to make the electrostatic latent image visible; and a voltage control unit for supplying a combination of a predetermined DC voltage and a predetermined AC voltage as a developing bias voltage to the developing roller as well as controlling the predetermined AC voltage so that a relation between a circumferential speed N of the developing roller and a frequency f of the AC voltage is as follows: ?0.097×N+61.17?(f/N)??0.093×N+67.33.

Abstract: According to an aspect of the invention, an image forming apparatus having a plurality of processing velocities is characterized by a control for determining the image forming process conditions by redefining a first approximate expression for estimating the unexposed surface potential value Vo of a photoconductive drum as a continuous function of the charging potential Vd according to the change of the natural environmental temperature, the change of the surface temperature of the photoconductive drum, the change of the photoconductive drum due to fatigue, or the exposure value, and a second approximate expression for estimating the exposed surface potential value VL of the photoconductive drum as a continuous function of the charging potential Vd according to the change of the processing velocity, using the first approximate expression and the second approximate expression to determine the optimal values of the developing potential, the background potential, and the exposure value for the respective process

Abstract: An image forming apparatus includes a first image bearing member; a first charger for electrically charging the first image bearing member; a first developer carrying member for carrying a first color developer to develop an electrostatic image formed on the first image bearing member with the first color developer; a first voltage source for applying a first oscillating voltage to the first developer carrying member; a second image bearing member; a second charger for electrically charging the second image bearing member; a second developer carrying member for carrying a second color developer to develop an electrostatic image formed on the second image bearing member with the second color developer; a second voltage source for applying a second oscillating voltage to the second developer carrying member; and a third voltage source for applying a common DC voltage to the first charger and to the second charger, wherein a frequency of the first oscillating voltage and a frequency of the second oscillating vol

Abstract: An image forming apparatus includes: a photoreceptor, a charging unit which charges the photoreceptor; an exposing unit which forms a latent image onto the photoreceptor; a developing unit which develops the latent image to a toner image; a sensor which detects a line width of a toner patch formed on the photoreceptor by the exposing unit and the developing unit; and a controller which changes a background voltage based on the line width detected by the sensor during an image forming operation so that the line width is secured within a predetermined line width. The controller returns the background voltage to value adjacent to an initial setting background voltage and changes the light amount of the exposing unit by a light amount corresponding to a returning amount of the background voltage.

Abstract: Control circuitry associated with an electrophotographic imaging device is adapted to operate in conjunction with a sensor to adjust a difference in electrical bias between a photoconductive surface and an associated roller. The sensor detects a reflectance or luminosity of a developed image and the control circuitry uses this detected information and information related to reflectance or luminosity of the underlying surface and the developing toner to determine whether the developed image is produced as desired. The control circuitry adjusts the difference in electrical bias between the photoconductive surface and an associated roller in response to a comparison between the detected and desired images. In one embodiment, a predetermined test pattern is developed over a range of electrical bias differences and an optimum operating point is determined from the iterations.

Abstract: An image forming apparatus includes: a plurality of development units having developing-agent carriers which are provided in correspondence to three or more developing agents, and developing electrostatic latent images on surfaces of image carriers to form developing-agent images on the image carriers; and a recovery unit that recovers the developing agent adhering to the developing-agent carrier during non-development operation. The recovery unit is provided for at least the development unit other than the development unit that transfers the developing-agent image first in sequence among the plurality of development units. When one of the plurality of development units performs development by the developing agent whose charge capability is higher than that of the developing agent of the development unit that transfers the developing-agent image later in sequence, the recovery unit starts recovery of the developing agent or performs recovery operation for improving recovery capability of the developing agent.

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.

Abstract: An image forming apparatus is constituted by an image carrying member movable while carrying a toner image, or a recording material carrying member movable while carrying a recording material onto which a toner image is to be transferred; a contact member movable while contacting the image carrying member or the recording material carrying member; and a voltage adjusting member for adjusting a voltage to be applied to the contact member so that an absolute value of the voltage when a state of the image carrying member or the recording material carrying member and the contact member is changed from a rest state in which these members are resting to a moving state in which these members are moving is larger than an absolute value of the voltage in the rest state.

Abstract: A control unit controls a device that executes an image forming process, compares changes of each toner adhesion amount in an image-density-detection pattern image when a developing-bias control condition is changed, with respect to a toner adhesion amount in an image-density-detection pattern image in a normal status, performs a malfunction-occurrence prediction process according to the degree of each change of the densities, and displays the result.

Abstract: A developing apparatus includes a developing roller for developing an image with a developer; a non-rotary magnet roll inside the roller; a blade; and an abutting member abutting against the roller, wherein the following expressions are satisfied: |Vs|>|Vdev|, |Br|/|B|?0.5, and L/(BH×R)?0.1, where |Vdev|: a DC component Vdev of a voltage applied to the roller, |Vs|: a DC component Vs of a voltage applied to the member, B(G): the magnetic flux density formed on the surface of the roller at the abutting position by the magnet roll, Br(G): the component of the magnetic flux density B(G) perpendicular to the surface of the roller, and L(mm): the abutting width between the roller and the member, BH(rad): the half value width of the component B?(G) horizontal to the surface of the roller, and R(mm): the radius of the roller.

Abstract: A bias voltage-applying unit applies a bias voltage to an insulating toner that includes an electric charge, by making a contact with the insulating toner. A light irradiating unit irradiates the insulating toner with a light. An electric-charge control unit controls an electric charge amount of the insulating toner by causing an optical switch phenomenon in which an electrostatic charge amount of the insulating toner changes, by irradiating the insulating toner with the light using the light irradiating unit while applying the bias voltage to the insulating toner using the bias voltage-applying unit.

Abstract: The present invention provides a method and apparatus for forming an image. A controller manages a charger and a developing bias voltage to increase an absolute value of the charging voltage to an image-bearing member and an absolute value of a developing bias voltage to a developer-bearing member to predetermined values in a plurality of steps. The controller controls the developing bias voltage applied to the developer-bearing member; wherein the following relation holds in each of the plurality of steps: |VD|>|Vi|, where VD represents a developing bias voltage applied to the developer-bearing member and Vi represents a charged potential of the image-bearing member. This invention is especially useful for mono-component development using DC voltage as a development driving mechanism.

Abstract: A method and apparatus to clear the accumulation of toner particles from a doctor element by periodically reversing a bias field between a doctor element and a developer member. The developer member may be biased to a first electrical potential while the doctor element may be biased to a second electrical potential. The second electrical potential may be higher than the first electrical potential. The doctor element and the developer member may be biased from a single voltage supply and a voltage dividing circuit. A bias reversing circuit may cause the second electrical potential to fall, at least temporarily, below that of the first electrical potential when power from the voltage supply is removed. The bias reversing circuit may also cause the first electrical potential to fall with a longer time constant than that of the second electrical potential when power from the voltage supply is removed.

Abstract: The residual potential and charging potential of the surface of a photosensitive drum 20, or the charging potential and exposure potential of the surface of the photosensitive drum 20 are detected by an exposure sensor 28. The lifetime of the photosensitive drum 20 is judged in accordance with the difference between the detected charging potential and residual potential, or the difference between the detected charging potential and exposure potential.

Abstract: An image forming apparatus includes: a developing device which applies a developing bias voltage obtained by superimposing an AC bias voltage onto a DC bias voltage to a photoreceptor, and develops a latent image on the photoreceptor with a developer to form a toner image. The apparatus has a toner forced discharge mode for forming a toner image for forced discharge in a first image formation area provided in a non-image formation area other than a second image formation area on the photoreceptor to forcibly discharge a toner from the developing device. When the mode is selected, an AC bias voltage at a frequency lower than that in the second image formation area is applied to the first image formation area to develop a latent image for forced discharge, to form a toner image, and a toner of the toner image is collected by a cleaning device.

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 an image bearing member attenuates after a developing bias applied to the developing member has been turned off after completion of an image forming operation. Accordingly, it is possible to mitigate adherence of developer due to a large potential difference between the developing member and the image bearing member.