Abstract: An image forming device that includes a first moisture amount derivation component, a drying component, a storage component, and a control component is provided. The storage component stores drying information, including information representing a pre-drying moisture amount previously derived by the first moisture amount derivation component, and a drying strength of the drying component at which a recording medium was dried when the previously derived pre-drying moisture amount was derived. The control component controls the drying strength of the drying component on the basis of the pre-drying moisture amount derived by the first moisture amount derivation component and the drying information stored by the storage component.

Abstract: A developing device includes a housing that forms a development chamber therein and a developer containing portion that forms a developer containing chamber therein and contains a one-component developer. A first transport path supplies a developer from the developer containing chamber to an upper side of the development chamber. A second transport path collects a developer from a lower side of the development chamber to the developer containing chamber. A developer carrier is disposed in the development chamber and carries a developer thereon. A developer supply member is disposed in the development chamber and supplies a developer to the developer carrier. A regulating member is in contact with the developer carrier and regulates a developer on a surface of the developer carrier. Stirring of the developer in the development chamber is performed by driving the first transport path and the second transport path to transport the developer.

Abstract: An image forming apparatus includes: a detected member of which a temperature is to be detected; a temperature sensor including a contact portion provided to contact the detected member, the temperature sensor being configured to detect the temperature of the detected member; and a condition determining unit. The condition determining unit is configured to control electric power supplied to the temperature sensor such that the temperature sensor self-heats during a heating time period, and determine a condition of the contact portion based on the temperature detected by the temperature sensor after the temperature sensor starts self-heating.

Abstract: A developer to be used in an image forming apparatus has a carrier and a toner containing a colorant, a binder resin, a release agent, a charge controlling agent containing Al and Mg, and a conductive inorganic oxide having an intrinsic resistivity of from 1.0×103? to 1.0×1010? in an amount of from 0.2 to 2.0 wt % based on a core toner.

Abstract: A paper coloring apparatus includes a coating apparatus which coats colored water on both faces of a paper sheet where an image has been formed by an electrophotographic image forming apparatus.

Abstract: Aspects of the disclosure provided a method to improve performance of a cleaning device to extend a usage life of the cleaning device. The method can include obtaining a performance characteristic of an electrostatic brush that degrades operations of the electrostatic brush, determining at least one parameter that compensates for the degradation, and controlling the electrostatic brush by the at least one parameter to maintain the electrostatic brush operating within a failure boundary.

Abstract: A fixing device includes: a heat member; a press member; a plurality of heat source members; temperature detectors; temperature control units that control outputs from the respective heat source members so that detected temperatures that the respective temperature detectors detect become preset controlled temperature; a processing target determining unit that determines whether at least one sheet to be subjected to the fixation includes a medium size sheet; and a controlled temperature determining unit that sets the controlled temperature of the heat source member corresponding to the temperature detection target area where the sheet does not pass to a temperature higher than the controlled temperature of the heat source member corresponding to the temperature detection target area where the sheet passes if it is determined that the medium size sheet is included.

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: An image forming apparatus includes an endless belt which is wound around a plural rollers and conveys a recording medium in a conveying direction; a plurality of image forming units which sequentially form images on the recording medium conveyed by the endless belt in an overlap manner; a fixing unit which is provided at a downstream of the endless belt in the conveying direction; a first detection unit which detects a temperature of a roller closest to the fixing unit; a second detection unit which detects a temperature of the endless belt; an error calculation unit which calculates an error of a conveying speed of the recording medium based on a difference between the detected temperatures, and a number of a recording medium, on which images are next to be formed; and a compensation unit which compensates the error calculated by the error calculation unit.

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 embodiment of the present invention relates to a fuser unit including first and second temperature detecting mechanisms that detect the temperature at the center in an axial direction of a first roller member in non-contact with the first roller member, a third temperature detecting mechanism that detects the temperature at an end in the axial direction of the first roller member and in an area where a developer carried by a bearing member is not present, and fourth and fifth temperature detecting mechanisms that detect the temperature at the center in an axial direction of a second roller member in non-contact with the second roller member. The detecting mechanism that detects the temperature in the area (the position) where the developer carried by the bearing member is not present may come into contact with the first roller member.

Abstract: The humidity detecting device includes a detection unit and a controller. The detection unit includes a humidity sensor for producing a humidity detection signal by detecting a humidity, a temperature sensor for producing a temperature detection signal by detecting a temperature surrounding the humidity sensor, and a common power supply line connected to the humidity sensor and the temperature sensor. The controller includes an application circuit for applying a power supply voltage to the humidity sensor and the temperature sensor through the common power supply line, a read circuit for producing a read-out humidity value corresponding to the humidity detection signal and a read-out temperature value corresponding to the temperature detection signal, and a correction circuit for correcting the read-out humidity value based on the read-out temperature value.

Abstract: An image forming apparatus capable of detecting a resistance value of an intermediate transferring member at a stabilized sensitivity irrespective of the influences of environmental conditions, disturbing elements, etc. and contributing to the promotion of the image quality when forming images. The image forming apparatus is equipped with an electric potential controller to fix electric potential of the photosensitive surface of a photosensitive drum, a power source to supply a prescribed voltage or current to the photosensitive surface through the transferring surface of an intermediate transferring member, and a resistance detector to detect a current value flowing through the intermediate transferring member against a prescribed voltage supplied from the power source or a voltage value generated in an intermediate transferring member against a prescribed current and detect a resistance value of the intermediate transferring member based on the detected current value or voltage value.

Abstract: An image forming device includes an image carrier having a surface onto which an electrostatic latent image is formed, a development station including a case made of a conductive body and one or more developer rollers, which supply toner housed in the case to the surface of the image carrier, and develop the electrostatic latent image formed on the surface of the image carrier as a toner image, a unit, which forms a standard concentration toner image of on the surface of the image carrier, a detector, which detects a toner adhesion amount of the standard concentration toner image formed on the surface of the image carrier by the standard concentration toner image-forming unit, and a voltage controller, which controls a bias voltage to be applied to the case according to a detected result of the toner adhesion amount of the standard concentration toner image by the detector.

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: An image forming apparatus includes a high-voltage power supply having a piezoelectric transformer. The power supply includes a positive output voltage generation circuit and a negative output voltage generation circuit. Each of the positive output voltage generation circuit and the negative output voltage generation circuit includes a piezoelectric transformer, a piezoelectric transformer driving circuit, an output voltage detection circuit, and a drive control circuit for outputting a control signal for controlling the piezoelectric transformer driving circuit using a signal from the output voltage detection circuit and an output voltage setting signal for setting an output voltage. The positive output voltage generation circuit and the negative output voltage generation circuit are simultaneously turned on when the output polarity of the high-voltage power supply with a piezoelectric transformer is switched.

Abstract: An image forming apparatus capable of appropriately cleaning an image carrier is provided. An image forming apparatus 1 including toner cartridges 11Y, 11M, 11C, and 11K, a developing section which forms toner images, an image carrier 4 which carries the toner images formed by the developing section, a transfer member 5 which transfers toner images from the image carrier 4 to a recording sheet S, and a cleaner 14 which is operable for press and release operation to/from the image carrier 4 and which is pressed to the image carrier 4 to scrape off the toner remaining on the image carrier 4 is provided with a control means 23 which decreases the number of press and release operations of the cleaner 14 when the cumulated value of the number of images formed since the first use of the brand-new toner cartridges 11Y, 11M, 11C, and 11K is large.

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: An image forming apparatus includes an intermediary transfer member for primary-transferring the toner at a primary transfer position so that a second color toner image is primary-transferred from an image carrying member onto a first color toner image which has been transferred in a superposition manner; a secondary transfer member for secondary-transferring the first and second color toner images together from the intermediary transfer member onto a recording; a fixing apparatus for fixing the toner images on the recording material; a guide member for guiding the recording material to the fixing apparatus; an electrical discharging member, for electrically discharging the recording material onto which the toner images are secondary-transferred; and a voltage application apparatus for applying, to the electrical discharging member before the secondary transfer, a voltage of a polarity identical to that of the first color toner image on the intermediary transfer member at a predetermined period.

Abstract: According to an embodiment of the invention, an image forming apparatus comprises a fixing unit including: a pair of rollers rotating with a recording sheet holding a toner image interposed therebetween; a driving motor rotating at least one of the pair of rollers; a heater being built in at least one of the pair of rollers to heat the roller; a timer measuring a period of time after starting operation; and a rotation speed control unit controlling the driving motor so that one of the rollers rotates in a speed higher than a rotation speed under normal conditions until a predetermined time measured by the timer.

Abstract: An image forming device whereby stable fixing performance is obtained and whose fixing properties are excellent and that does not produce curling of the paper after fixing, due to performing control for correcting fixing temperature by environmental sensing not only during standby but also over time. A plurality of temperature detecting units are provided in the fixing device and a plurality of detecting units that detect temperature and humidity are provided within the image forming device. Temperature correction is performed whereby the target control temperature of the fixing device is changed to a prescribed value in accordance with the temperature or humidity detected by the plurality of detecting units.

Abstract: A charging device includes a charging member that charges a body to be charged; a detector that detects an AC component of a current flowing through the charging member; an integration section that integrates the AC component of the current detected by the detector; a controller that controls the current flowing through the charging member, according to a result of integration executed by the integration section; a periodic signal generating section that generates a periodic signal having a cycle period corresponding to a cycle period of the AC component; and an integration period adjusting section that adjusts a period of integration executed by the integration section, with reference to the periodic signal.

Abstract: An image forming apparatus forming an image by fixing a developer on a recording medium with heat includes a fixing member, a pressure member, a drive unit, a heat unit, a temperature detection unit, a control unit, and a temperature record storing unit. The fixing member is rotatably supported and heats the recording medium. The pressure member presses against the fixing member. The drive unit rotationally drives the fixing member. The heat unit heats the fixing member. The temperature detection unit detects temperature of the fixing member. The control unit controls the heat unit and the drive unit. The temperature record storing unit stores a temperature record of the temperature detection unit. The control unit controls, based on the temperature record of the temperature record storing unit, a rotation drive of the drive unit in a case of non-fixing.

Abstract: An image forming apparatus to which a developer storage container can be detachably mounted, includes: a reception unit arranged to receive information from the developer storage container; a first temperature detection unit provided in an inside of the image forming apparatus and arranged to detect a temperature of the inside of the image forming apparatus; a cooling unit arranged to cool the inside of the image forming apparatus; and a control unit arranged to determine on the basis of the received information whether second temperature detection unit is provided to the developer storage container, control the cooling unit on the basis of the detection result of the first temperature detection unit when the second temperature detection unit is not provided, and control the cooling unit on the basis of the detection results of the first and second temperature detection units when the second temperature detection unit is provided.

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: An system and related method for maintaining print quality based on development potential measurements that include comparing the current process measurements to a toner concentration related set-point; calculating a quality adjustment range based on current process measurements and the toner concentration related set-point, or a derivative thereof, indicative of print quality; and adjusting current process conditions related to the current process measurements to trend towards a new set point within the quality adjustment range so that a rate of change is proportional to the difference between the current process measurements and the set point.

Abstract: An image forming apparatus is provided, which prevents occurrence of conveying malfunction or image failure due to variation of conveying speed caused by endurance of a fixing unit or a conveying unit, variation of using environment, or a type of a recording material. The image forming apparatus includes: a fixing unit for heating and fixing a toner image on a recording sheet (P); a secondary transferring portion for conveying the recording sheet (P) to the fixing unit; a loop sensor for detecting a degree of a loop of the recording sheet (P) generated according to a speed difference between a conveying speed of the fixing unit and a conveying speed of the secondary transferring portion; a CPU for controlling the conveying speed of the fixing unit; a fixing deliver sensor for detecting a used amount of the fixing unit; and an EEPROM for storing information on the used amount of the fixing unit detected by the fixing deliver sensor.

Abstract: A developer nozzle is moved from a periphery of a wafer toward the central portion while an exposed substrate held at a spin chuck is being rotated about a vertical axis and while a developing solution is being discharged from the developer nozzle, and this way the developing solution is supplied to the surface of the wafer, the developer nozzle having a slit-like ejection port whose longitudinal direction is oriented to the direction perpendicular to the radial direction of the wafer. The movement speed of the nozzle is higher than a case where a nozzle with a small-diameter circular nozzle is used, and this enables a development time to be reduced. Further, the thickness of a developing solution on a substrate can be reduced, so that the developing solution can be saved.

Abstract: An image forming apparatus includes a plurality of image forming units each having an image supporting member, a developer supporting member, and a cleaning member for cleaning developer on the image supporting member. The image forming apparatus further includes a transfer device for transferring a developer image to a medium; a fixing device for fixing the developer image to the medium; a first detection unit for detecting a first physical value of an external environment of the image forming apparatus; a second detection unit for detecting a second physical value of an internal environment of the image forming apparatus; and a control unit for determining whether at least one of the image forming units performs a developer discard mode in which developer is discarded according to the first physical value, the second physical value, and a distance between the one of the image forming units and the fixing device.

Abstract: An image forming apparatus includes a photoreceptor having on a surface thereof a photosensitive layer, in which an electrostatic latent image is formed, a contact charging roll applied with a bias containing a direct current component having superimposed thereon an alternating current component, the contact charging roll charging the photoreceptor to a predetermined potential, a film thickness detecting unit detecting a film thickness of the photosensitive layer of the photoreceptor, an environment detecting unit detecting environment, and a contact area changing unit changing a contact area between the contact charging roll and the photoreceptor based on detected results of the film thickness detecting unit and the environment detecting unit.

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 formation apparatus is provided and includes: a photoconductor; a charging section that applies a bias voltage having an AC voltage superposed on a DC voltage to the photoconductor so as to charge the photoconductor; a controller that controls at least one of the AC voltage and an AC current in response to a fluctuation amount of a DC current flowing between the photoconductor and the charging section when an AC voltage is applied; and a detector that detects the DC current.

Abstract: A developing device capable of adjusting to an appropriate toner density just after replacement of developer regardless of a humidity environment, and an image forming apparatus provided with the same. In a developing device, when developer is replaced, an initial toner density of developer for replacement is set so as to be equal to a toner density in its life or lower, and after replacement of the developer for replacement, a control section determines whether toner replenishment is necessary or not based on a detection value of a humidity sensor prior to a development operation.

Abstract: An image forming apparatus, such as a printer, includes an image forming unit forming a toner image on an image carrier, a transfer unit for transferring the toner image onto a recording medium, a pair of a fusing rotating body and a pressure rotating body, a fusing unit for fusing the toner image on the recording medium, a temperature detecting unit for detecting the temperature on the surface of the fusing rotating body, and a control unit. An amount of decrease in the temperature of the fusing rotating body surface is measured at a predetermined time, and the time between an image formation request and the arrival of the recording medium, with the toner image formed thereon, at a fusing/nipping portion formed between the fusing rotating body and the pressure rotating body is extended when the temperature decrease amount is greater than a threshold value.

Abstract: An image forming apparatus mounted with a toner cartridge having a memory unit includes a toner cartridge which stores a plurality of control data depending on toner in the memory unit, an acquisition unit which selects one of the plurality of control data in the memory unit and acquires image formation-related information and a setting unit which sets image formation parameters on the basis of the image formation-related information.

Abstract: In a printing machine having at least one transfer device driven in response to an electrical signal and operable to transfer a medium onto a sheet, a method controls the magnitude of the electrical signal driving the transfer device. The method includes assigning a magnitude of the electrical signal for driving the transfer device to each of at least two transfer stress levels, evaluating only operating parameters of the printing machine that have a pre-determined priority value relative to a corresponding pre-determined threshold value, selecting one of the at least two transfer stress levels based on the evaluation of the at least one operating parameter, and applying the magnitude of the electrical signal corresponding to the selected stress level to the electrically-driven transfer device.

Abstract: Disclosed is an image forming apparatus which forms an image on a paper including a detection unit to detect a present temperature of one component or a plurality of components to be replaced among components constituting the image forming apparatus and a control unit to determine whether the component is replaceable or not based on the detected present temperature and to execute a replacement guide for the component which is determined to be replaceable.

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: An image forming apparatus prevents defective fixing of a toner image from occurring and shortens a printout time for a first sheet by determining a start timing for conveying the recording medium to a transferring position of the toner image in accordance with a warm-up state of a fixing unit, a voltage state of a power supply, and an environmental temperature.

Abstract: An image forming apparatus includes an image bearing member which bears a toner image, a transfer member which transfers the toner image on the image bearing member to a transfer material, a cleaning blade which is brought into contact with and separated from the image bearing member and which removes transfer remaining toner remaining on the image bearing member where the toner image is transferred; and executing means which executes a toner cleaning mode such that the cleaning blade is brought into contact with and separated from the image bearing member so as not to remove a part of the transfer remaining toner remaining on the image bearing member, and then the cleaning blade having been separated from the image bearing member contacts the part of the transfer remaining toner remaining on the image bearing member when the cleaning blade again is brought into contact with the image bearing member.

Abstract: A fixing unit adapted to fix a developing agent onto an image forming medium by way of a heat roller containing a heater and a press roller conducts a warming up operation for the optimum warming up time as determined based on the temperature and the humidity of ambient air detected by a temperature/humidity sensor.

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 improved color EP (laser) printer is provided for use in high humidity conditions. A humidity sensing circuit determines if the print quality might be degraded due to environmental conditions, using a resistivity sensing circuit, or a humidity sensor. If the print quality would likely be degraded, the invention is able to enhance toner transfer by printing supplemental process black toner dots underlaying standard black toner dots at predetermined pixel locations in the bitmap of a print job. This assumes that the black printing station is the “last” station along the travel of the intermediate transfer member. Other colors could be used for the supplemental toner dots.

Abstract: An image forming apparatus is provided that has a developing agent holder arranged as opposed to an image holder having an electrostatic latent image formed thereon, the developing agent holder attaching the developing agent to the image holder, a developing agent supplying unit rotatably arranged in contact with the developing agent holder, the developing agent supplying unit supplying a developing agent to the developing agent holder, an adjustment unit capable of adjusting a contacting state between the developing agent holder and the developing agent supplying unit.

Abstract: An imager temperature sensor and a current correction apparatus are provided which use dark pixel measurements from an imager chip during operation together with a fabrication process constant as well as a chip dependent constant to calculate chip temperature. The chip temperature may be used to generate a current correction signal. The correction signal is used to tune a current on the imager chip to correct for temperature variations.

Abstract: An image forming apparatus includes a light source unit, an image carrier on which a latent image is formed by a light beam emitted from a light source, a developing unit configured to develop a latent image formed on the image carrier using a toner, an intermediate transfer unit on which a toner image developed by the developing unit is transferred, a heating unit configured to heat the intermediate transfer unit on which a toner image is transferred, a fixing unit configured to fix the toner image heated by the heating unit on a recording medium, a temperature detection unit configured to detect temperature of the intermediate transfer unit, and a control unit configured to control a magnification of a latent image to be formed on the image carrier according to a detection result of the temperature detection unit.

Abstract: A fixing apparatus includes a control circuit which controls the electrifying to a first heater so that a temperature detected by a first temperature detection portion reaches a first target temperature and controls the electrifying to a second heater so that a temperature detected by a second temperature detection portion reaches a second target temperature, when warm-up is initiated, and, when the warm-up initiated, if an initial temperature of a rotary member is below a predetermined temperature, the control circuit sets the first target temperature to a temperature value greater than the first target temperature set when the initial temperature of the rotary member is greater than the predetermined temperature and sets the second target temperature to a temperature value greater than the second target temperature set when the initial temperature of the rotary member is greater than the predetermined temperature.

Abstract: An image forming apparatus includes an image bearing member on which an electrostatic image is formed; a developing device for developing the electrostatic image formed on the image bearing member with a developer including toner and a carrier; a supplying apparatus for supplying into the developing device a supply developer including toner by rotating a feeding screw; inclination detecting means for detecting an inclination of the feeding screw; and control means for controlling rotation of the feeding screw on the basis of a result of detection of the inclination detecting means.

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 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.