Abstract: An image formation apparatus includes an exposure unit to form an electrostatic latent image with image dots on a rotatable image carrier by exposing the image carrier to irradiation light, a development unit to form a developer image by attaching a developer to the electrostatic latent image, a voltage supply unit to supply the development unit with a development voltage, a cleaning unit to clean up the developer left on the image carrier after the development, and a developer discard amount controller to control an amount of the developer to be forcibly attached to the image carrier based on a total rotation number of the image carrier if the number of image dots printed during a prescribed number of rotations of the image carrier is smaller than a reference value, and to forcibly attach the controlled amount of the developer to the image carrier to discard the developer.

Abstract: A detecting unit detects a usage state of a charge storage unit for each predetermined time period. A setting unit determines whether the usage state of the charge storage unit satisfies a predetermined condition for each time period, and when it is determined that the usage state satisfies the predetermined condition, sets a corresponding time period as a charge-use permitted time. A control unit determines whether a current time falls in the charge-use permitted time, and when it is determined that the current time falls in the charge-use permitted time, allows a discharging unit to discharge the charge storage unit.

Abstract: An image forming apparatus includes an image forming unit that forms an image on a sheet; a receiving unit that receives a command that makes the image forming unit form an image; and a controller that controls the image forming unit so that the image forming unit forms an image on a sheet at a first image forming speed if a number of sheets on which images are to be formed due to the command is larger than a threshold and controls the image forming unit so that the image forming unit forms an image at a second image forming speed if a number of sheets is equal to or smaller than the threshold, the second image forming speed being higher than the first image forming speed.

Abstract: Methods for generating an inverse mask image are provided. In one aspect, image data is determined for an image to be printed said image data having color data for a first set of colors used in a first color model; and, an inverse mask toner image is generated using color data for one of the first set of colors. The inverse mask image is generated based upon the color data for a selected one of the first set of colors so that the inverse mask pattern can be generated without first determining of color separation toner images that define amounts of color toner to be applied to a receiver to form the image.

Abstract: An image forming apparatus includes a color image forming portion for forming a color toner image on an image bearing member and a transparent image forming portion for forming a transparent toner image on the image bearing member. The color and transparent image forming portions form test color and test transparent toner images on the image bearing member. A detecting portion detects a density of each of the test color and test transparent toner images and a control portion controls an image forming condition for an image to be formed on a recording material, on the basis of a result of the detection. The test transparent and test color toner images are formed on the image bearing member between operations for forming the images on the recording material. A frequency of formations of the test transparent toner images is lower than that of the formations of the test color toner images.

Abstract: An image forming apparatus includes a developing device including a developer bearing member for bearing and conveying a developer and configured to develop a latent image formed on an image bearing member using the developer, a bias application unit configured to apply at least an AC bias to the developer bearing member, an integration unit configured to integrate an application time of the AC bias applied by the bias application unit, and a determination unit configured to determine a replacement timing of the developing device based on an integrated value by the integration unit.

Abstract: An image forming apparatus for which a first mode using toners of plural colors including a black toner and a second mode using only the black toner can be set, includes a first printing cumulatively counting part that cumulatively counts a first number of pages for which image forming has been executed by using the toners of plural colors; a first printing determining part that determines whether the first number of pages counted by the first printing cumulatively counting part has exceeded a threshold; and a correction control part that controls not to execute a correcting process for image forming that uses the toners of plural colors but to execute a correcting process for image forming that uses only the black toner, when the second mode has been set in a case where the first printing determining part has determined that the first number of pages has exceeded the threshold.

Abstract: An image forming apparatus includes a photosensitive member (drum); a rotatable charging member for electrically charging the drum; a bias applying device for applying a charging bias to the charging member in the form of a DC voltage biased with an AC voltage; a current detector for detecting an AC current passing between the charging member and the drum; a temperature and humidity detector; a setting device for setting a condition of the charging bias on the basis of a plurality of detected AC currents passing between the charging member and the drum when a plurality of AC voltages depending on an output of the temperature and humidity detector are applied to the charging member; and a corrector for correcting the set condition of the charging bias on the basis of an output of the current detector when a predetermined AC voltage is applied to the charging member.

Abstract: An image forming apparatus acquires a print target image, scans an image on a sheet, recognizes reuse information in the image scanned from the sheet, generates reuse information after printing the print target image from the recognized reuse information and the acquired print target image, selects an area where the reuse information can be printed, in the acquired print target image, combines the reuse information with the selected area in the print target image, deletes the image on the sheet from which the image is scanned, and forms the combined image on the sheet from which the image is deleted, with a erasable image forming material.

Abstract: An image forming apparatus includes a charging unit, an image carrier, an exposing unit, a developing unit, a transfer belt on which the transfer material is placed, a fixing unit that fixes the toner image transferred onto the transfer material, a cleaning unit that cleans up toner attached to the fixing unit, and a control unit that controls printing of the image on the transfer material. The control unit causes the exposing unit to expose a latent image of a first image having an image-area ratio equal to or larger than a predetermined ratio, causes the developing unit to form a toner image of the latent image and to transfer the toner image to the transfer material, and causes the fixing unit to fix the toner image transferred by the transfer belt to the transfer material.

Abstract: An apparatus includes a controller controlling feeding of a recording material. When the recording material size is smaller than a reference size, the controller expands an interval between precedent and subsequent recording materials gradually. When image formation on recording materials smaller than a reference size starts, when the elapsed time from the end of the last image formation exceeds a predetermined time, an initial value of the interval is set to a predetermined minimum value. When image formation on recording materials smaller than the reference size starts, when the elapsed time is shorter than the predetermined time, the initial value of the interval is set in accordance with the elapsed time and a last feeding interval at the time of an image formation of the last time or a last temperature in a non-sheet-passing region at the time of an image formation of the last time.

Abstract: An image forming apparatus includes first and second developer carrying members and a control device. The apparatus is operable in a first mode where an image of a single color is formed using the first developer carrying member and is operable in a second mode, wherein an image of a plurality of colors is formed using the first and second developer carrying members. The control device controls a first discharging operation for discharging developer from the first developer carrying member and a second discharging operation for discharging developer from each of the first and second developer carrying members. When the apparatus executes only the first mode, the control device performs more image formations, in a period between completion of the second discharging operation and start of the first discharging operation, compared to a period between completion of the first discharging operation and start of a subsequent first discharging operation.

Abstract: A dry electrophotographic printer is operated to remove toner from a longitudinal member. A process-control time interval, and a cleaning time interval that is a positive multiple thereof, are selected. Prints are produced until the process-control time interval elapses, as measured by a timing device. A process-control patch is produced in a process-control frame. This is repeated until the cleaning interval has elapsed. In the process-control frame, after the cleaning interval elapses, the photoreceptor and development member are spaced apart, then, after a selected time delay, brought into operational relationship, so that a stop at one end of the photoreceptor contacts an end block at one end of the development member, and toner is removed from the longitudinal member, which is connected to the end block.

Abstract: Methods and apparatus for adjusting printing device power consumption based on previously acquired usage data. The printing device has multiple energy consumption states including at least a ready state in which the printing device is ready to commence processing of a print job immediately upon receipt and including at least a low power state where the printing device is not ready to commence processing of a newly received print job. Acquired usage data includes parameters of print jobs submitted during a data collection period of time. The parameters may include time and date of submitted print jobs. Based on the usage data a usage profile is determined. The usage profile identifies one or more high usage periods of time and one or more low usage periods of time. Methods and apparatus then switch the printing device among the multiple energy consumption states based on the usage profile.

Abstract: An image forming apparatus is configured to perform a collecting operation for moving the attached matter held on a holding roller onto the photosensitive drum and collecting the attached matter by a collecting unit. A bias control unit for controlling a bias applied to the holding roller is configured to: during an image forming operation, apply a first bias for moving the matter onto the holding roller; and during the collecting operation, apply a second bias for moving the attached matter onto the photosensitive drum. A speed control unit is configured to: control the holding roller to rotate at a first rotating speed during the image forming operation; and in a progress of the collecting operation, control the holding roller to rotate at a second rotating speed for a first period after the bias control unit applies the second bias to the holding roller.

Abstract: In an image forming apparatus, a processor generates a first density variation data based on the surface potential of the pattern in relation to the rotational position of the image bearer and a second density variation data based on the first density variation data and the density of the toner pattern, stores the first density variation data and the second density variation data in a memory, makes a pattern in a predetermined timing, decides whether the first density variation data is changed or not, change the first density variation data based on the decision, controls the toner image forming condition of the toner image forming device based on the first density variation data and the second density variation data.

Abstract: An image forming apparatus includes an exposure device having an adjustment period for adjusting an output while exposing a photosensitive drum to light prior to image formation and a developing device. The developing device is configured to change between a contact state where the photosensitive drum and a developing roller are in contact with each other and a separation state where they are separated from each other. The developing device changes from the separation state to the contact state when a portion on the photosensitive drum exposed to light in the adjustment period of the exposure device is at a developing position.

Abstract: An image forming apparatus includes a toner carrying member for supplying toner to an image bearing member to visualize the latent image; a rotatable toner supply member, contacted to the toner carrying member, for supplying toner to the image bearing member; a voltage applying device for applying voltages to the toner carrying member and the toner supply member; and a controller for controlling the voltage applying device to control voltages applied to the toner carrying member and the toner supplying member.

Abstract: An image forming apparatus using an electrophotographic process includes an image forming unit, a storage unit, and a control unit. The image forming unit performs monochrome printing and color printing. The storage unit stores print ratio data that relates to printing in the image forming unit is measured over time. The control unit separately performs correction of monochrome toner density and color toner density based on a predetermined first condition. If the first condition in the monochrome printing is met, the control unit performs correction of the monochrome toner density if a predetermined second condition concerning an amount of variation in the print ratio identified from the print ratio data is also met.

Abstract: Apparatus for removing toner after a selected time interval from a longitudinal member in a dry electrophotographic printer for printing a visible image on a receiver. An end block is disposed at one end of a rotatable development member, and a longitudinal member is disposed adjacent to the development member or photoreceptor and is connected to the end block. A backup bar is disposed adjacent to the photoreceptor and can selectively make physical contact with at least one point on the end block. When a measured time interval of printer operation reaches the selected time interval, a controller causes the backup bar to apply a selected force to the end block to cause toner on the longitudinal member to be removed from the member.

Abstract: When carrying out monochrome printing, an engine unit of a printer calculates an amount of toner consumed as lubricant by a color photoreceptor according to the number of sheets to be printed (S63). When carrying out color printing, the engine unit calculates an amount of toner remaining on the color photoreceptor after the printing based on an amount of toner necessary for printing calculated from a printing rate and an amount of actually transferred toner that is calculated from the transfer rate (S65). The toner remaining on the color photoreceptor is used as lubricant, and the engine unit calculates an amount of toner by subtracting the residual toner amount from the amount of toner as lubricant calculated from the number of sheets for monochrome printing (S67), and supplies the calculated amount of toner as lubricant to the color photoreceptor when carrying out monochrome printing.

Abstract: An image forming apparatus includes: a heating device that heats images that have been formed on a sheet-like recording medium to thereby fix the images to the recording medium; an ejection member that rotates in a forward direction and ejects to the outside the recording medium that has been conveyed from the heating device; a blower member that blows air onto the recording medium conveyed between the heating device and the ejection member; and a controller that controls the blower member such that the blower member operates when a recording page count where images are continuously formed on the recording medium is equal to or greater than a predetermined recording page count.

Abstract: This invention provides an image forming apparatus which performs sleep control for a shift to the sleep mode for each function and provides a user-friendly operation system, and a method of controlling the same. To accomplish this, the image forming apparatus sets a shift time until a power state of the image forming apparatus shifts to the low-power state after execution of image formation; and performs control to shift the power state of the image forming apparatus to the low-power state, when the shift time is not more than the predetermined time, before an elapse of the shift time after execution of image formation by the printing function, while shifting the power state of the image forming apparatus to the low-power state, in response to an elapse of the shift time after execution of image formation by the copying function.

Abstract: A charging device includes a charging member and a pulling device. The charging member charges a surface of an image carrier and includes a charging member body and axial-end members. The charging member body is arranged so as to face the image carrier and extends along an axial direction of a rotation shaft of the image carrier. The axial-end members are supported at both ends of the charging member body in the axial direction and do not extend through the inside of the charging member body in the axial direction. The pulling device pulls the charging member in the axial direction.

Abstract: An image forming system is provided with an Image Forming Operation Unit, an Air Cleaning Operation Unit, a power source, and a Control Unit. The Control Unit has a coordinated OFF control function of coordinating a first power supply OFF control for turning off power supply from the power source to the Image Forming Operation Unit and a second power supply OFF control for turning off power supply from the power source to the Air Cleaning Operation Unit, and the coordinated OFF control function is configured to execute the second power supply OFF control when a preset time period elapses after executing the first power supply OFF control. Also, in the image forming system, an air cleaning operation of an air cleaning apparatus is stopped when an image forming apparatus is set to an a night mode or when a fixed time period elapses after the night mode is set. The air cleaning operation of the air cleaning apparatus is restarted when the image forming apparatus is resumed from the night mode.

Abstract: An image forming device includes an image support object, a charging unit, an exposure unit, and a developing unit. The image forming device further includes a monitoring unit that sequentially updates a count value to a new count value according to a rotation state and a stop state of the image support object, and an intermittent driving unit that intermittently rotates the image support object according to the new count value generated by the monitoring unit after an image formation operation to form the toner image on the image support object surface is completed.

Abstract: An image forming apparatus includes a receiver to receive image information from an external device, a movable intermediate transfer member, a plurality of latent image bearing members on which a latent image is formed based on the image information, a plurality of developing devices, each of which disposed in proximity to the latent image baring member, to develop the latent image on the latent image bearing member with toner to form a toner image thereon, a transfer bias application mechanism to apply a transfer bias to the intermediate transfer member and halt temporarily and periodically application of the transfer bias in a continuous output mode in which a plurality of images are continuously formed on different recording media sheets based on the image information of the plurality of images received continuously by the receiver, and a secondary transfer member to transfer the superimposed toner image onto a recording medium.

Abstract: An image forming apparatus includes a latent image holder that holds a latent image; a developing unit that contains developer including toner particles and carrier particles, develops a latent image with the toner particles, and forms a toner image; a voltage applying unit that applies a voltage to the developing unit; a toner concentration detection unit that detects a toner concentration that is a proportion of the toner particles to the developer contained in the developing unit; and a setting unit that sets a setting value of the voltage on the basis of the toner concentration detected by the toner concentration detection unit, the voltage being applied by the voltage applying unit to the developing unit, wherein a difference between an upper limit and a lower limit of the set value increases as the toner concentration increases, the set value being set by the setting unit.

Abstract: A method for controlling a printing system adapted to perform an adjustment operation with an adjusting unit includes storing information indicating a timing for performing the adjustment operation in a storage unit, causing the adjusting unit to perform the adjustment operation based on the information indicating the timing for performing the adjustment operation stored in the storage unit, causing the adjusting unit to perform the adjustment operation at a timing different from the timing indicated by the information in response to a print interruption occurring in the printing system if a previous adjustment operation has not been performed within a predetermined period of time, and updating the information indicating the timing for performing the adjustment operation stored in the storage unit in response to the adjusting unit performing the adjustment operation to delay a timing for performing a next adjustment operation with the adjusting unit.

Abstract: Disclosed an image forming system including: an image forming section to perform an image forming processing to form an image on a sheet to eject the image-formed sheet to an sheet ejection section; a control section to control the image forming processing by the image forming section; a specify section to specify the number of units for stop in a temporary stop mode in which the image forming processing by the image forming section is temporarily stopped, wherein the control section allows the image forming section to stop the image forming processing when the image forming processing by the image forming section reaches the number of units for stop specified with the specify section.

Abstract: An image forming apparatus includes a count section configured to count time during which no image forming is performed and a control section configured to allow heating of a heat generating section at temperature for decolorizing after the time counted by the count section reaches the a predetermined threshold time.

Abstract: An image forming apparatus includes an operation progressing condition that is considered when the image forming apparatus enters an apparatus protection mode. Further, a method of controlling the image forming apparatus includes receiving an apparatus protection mode entry condition of the image forming apparatus, detecting the temperature of the image forming apparatus or the number of continuously printed sheets, judging whether or not the apparatus protection mode entry condition is satisfied, if the temperature of the image forming apparatus is higher than a predetermined temperature or the number of continuously printed sheets is greater than the predetermined number of sheets, and maintaining a basic printing operation of the image forming apparatus, if the apparatus protection mode entry condition is not satisfied, thereby increasing user's satisfaction and operation efficiency.

Abstract: An image forming apparatus including a carriage including image forming units, the carriage driven reciprocally in a main scanning direction; a conveyance unit to convey a sheet of recording media to a position where the image forming units perform image formation; a first detector provided to the carriage, the first detector including a light emitting part and a light receiving part to periodically detect a surface of the sheet; a calculation unit to calculate a relative amount of movement between the sheet and the image forming units by comparing patterns periodically detected by the first detector; and a control unit to control a timing to perform image formation by the image forming units and an amount of conveyance of the sheet conveyed by the conveyance unit based on a result calculated by the calculation unit.

Abstract: A lubricant supplying device includes a lubricant supplying roller configured to rotate in a certain direction and makes a sliding contact with an image carrier on which a toner image is carried; a solid lubricant arranged to slide in contact with the lubricant supplying roller; a changing unit configured to change a revolution of the lubricant supplying roller to adjust an amount of the solid lubricant supplied onto the image carrier; and a calculation unit configured to obtain a product life or total consumption of the solid lubricant from a total running distance or total operating time of the image carrier or the lubricant supplying roller, the product life or the total consumption of the solid lubricant being corrected based on the amount of the solid lubricant supplied onto the image carrier.

Abstract: An image forming apparatus including: plural sheet supplying sections which accommodate a recording sheet and feed out the recording sheet; an image forming section which forms an image on the recording sheet, fed out from the sheet supplying section, based on a printing job; a memory section which stores information of the printing job, including information of the recording sheet; and a control section which determines a sheet supplying section, based on the information of the recording sheet, included in the printing job stored in the memory section, and displays an event using a time axis provided on a vertical axis or a horizontal axis on a display section, the event is generated by a schedule for using the sheet supplying section determined above, and is generated when the sheet supplying section is switched to another sheet-supplying section, or the event is generated at a predetermined time cycle.

Abstract: Toner is removed, after a selected time interval, from a skive mount in a dry electrophotographic printer. An end block is disposed at one end of the rotatable development member, and a skive mount disposed adjacent to the development member connects a skive to the end block. A timing device measures a time interval of printer operation. At the selected time interval, a controller causes a backup bar to lift away from the photoreceptor, then, after a selected time delay, causes the backup bar to make physical contact with at least one point on the end block, so that the backup bar applies a selected force to the end block to cause toner on the skive mount to be removed.

Abstract: An image forming apparatus includes a counting section, a storage section, a control section, and a driving member control section. The counting section counts the number of recording media subjected to successive printing. The storage section stores the number counted by the counting section. The control section performs a control process including: setting a power saving mode by selecting a printing speed of the fixing section which is lower than a preset normal speed used in the normal mode while selecting a preset fixing temperature of the fixing section which is lower than a preset normal temperature used in the normal mode when the normal mode is alive while a frequency of successive printing on not more than three recording media is a predetermined percentage or more. The driving member control section switches a current printing speed of the fixing section to a printing speed selected by the control section.

Abstract: An image forming apparatus includes: an image carrier; a developer carrier configured to supply developer to the image carrier; a power supply unit configured to apply a voltage to the developer carrier; a drive unit configured to rotationally drive the image carrier and developer carrier; a rotation amount determiner configured to determine the amount of rotation of the image carrier or the developer carrier in a predetermined time period; and a drive control unit configured to instruct the drive unit to rotate the image carrier and the developer carrier in a non-printing state, when it is determined that the rotation amount in a printing operation in the predetermined time period was equal to or greater than a threshold.

Abstract: Provided is an image forming apparatus including an image forming section forming images on image forming faces of a recording medium, a condition setting section individually setting an operating condition of the image forming section for forming the image on a first image forming face of a recording medium and another operating condition of the image forming section for forming the image on a second image forming face of the recording medium opposite to the first image forming face in the manual duplex mode, and a control section controlling the image forming section on the basis of each operating condition set by the condition setting section.

Abstract: An image forming apparatus includes a controller that starts a forced drive stop sequence for stopping image formation at least by stopping rotation of a developer carrier in a first direction when a number of printed sheets reach a threshold. The forced drive stop sequence rotates the developer carrier in a second direction for a prescribed time period when the image formation is stopped. The forced drive stop sequence stops the rotation of the developer carrier in the second direction and resumes the image formation after the prescribed time has elapsed.

Abstract: A method of controlling the inverter dwell time of the first print engine in order to print any sheet size within a pitch mode without the need for a belt sync dead-cycle. The method uses a small nominal inverter dwell time based on the maximum sheet size for a given pitch mode. For any sheet size within the pitch mode that is smaller than the maximum sheet size, the inverter dwell time will increase proportionally.

Abstract: A print control apparatus that controls a printing unit is provided. A determination unit determines print quality of a print image printed by the printing unit. A first counting unit counts the number of pages of each of sets whose print quality is determined by the determination unit not to satisfy a predetermined criterion. A second counting unit counts the number of same pages of the sets whose prnt quality is determined by the determination unit not to satisfy a predetermined criterion. A control unit stops printing by the printing unit if a count value counted by the first counting unit reaches a first predetermined value and stops printing by the printing unit if a count value counted by the second counting unit reaches a second predetermined value.

Abstract: An image forming apparatus includes an image carrier, a transfer member provided at a position at which the transfer member can be pressed against the image carrier, a detection device for detecting a toner attachment amount of the toner image formed on the image carrier, an avoidance judging section for judging whether or not avoidance of a pressed region should be performed when a toner image for image formation is formed on the image carrier, the pressed region serving as a region located on the image carrier and being pressed against the transfer member from the end of a previous image forming operation to the start of a present image forming operation, and an avoidance continuation judging section for judging the necessity for continuation of the avoidance by being operated when it is judged as avoidance by the avoidance judging section.

Abstract: An image forming apparatus includes an image forming unit having image forming elements and a fixing unit. The image forming elements includes an image carrier, a charging unit, a developer carrier, and a developer supplier. The image forming apparatus further includes a post unoperated period image formation preparation processor operable to, when the unoperated period, which is a time period from an end of an image forming operation to a start of a subsequent image forming operation is equal to or greater than a threshold, perform an idling operation to rotate the image carrier while applying a post unoperated period image formation preparation voltage, which is different from a normal image formation voltage, to a given one or more of the image forming elements.

Abstract: An image forming apparatus includes a rotatable drum; a charging roller for electrically charging the drum; a developing device for developing a latent image formed on the drum into a developer image; a cleaning device for removing a developer remaining on the drum after transfer; and a control device. The cleaning device includes a cleaning blade contacting the drum. The control device is capable of performing an operation for rotating the drum, in a direction identical to the rotational direction of the drum during image formation effected by rotating the drum, after a lapse, without next instruction of image formation, of a predetermined period from a stop of rotation of the drum after completing image formation. The predetermined period is longer with a larger number of sheets subjected to the image formation in an image forming job before the rotation of the image bearing member is stopped.

Abstract: An image forming apparatus includes a control mechanism capable of selecting a plurality of print modes and a fixing device fixing an image developed based on one of the print modes selected by the control mechanism. The control mechanism selects any one of the print modes based on a successive print sheet number determined by print information received from a host device and a power consumption amount of each of the print modes calculated from fixing temperature of the fixing device prior to starting print operation.

Abstract: Methods and apparatus for adjusting printing device power consumption based on previously acquired usage data. The printing device has multiple energy consumption states including at least a ready state in which the printing device is ready to commence processing of a print job immediately upon receipt and including at least a low power state where the printing device is not ready to commence processing of a newly received print job. Acquired usage data includes parameters of print jobs submitted during a data collection period of time. The parameters may include time and date of submitted print jobs. Based on the usage data a usage profile is determined. The usage profile identifies one or more high usage periods of time and one or more low usage periods of time. Methods and apparatus then switch the printing device among the multiple energy consumption states based on the usage profile.

Abstract: An image forming apparatus which predicts VL fluctuates of a photosensitive drum, taking a rotation speed of the photosensitive drum during image formation into consideration, and controls the image formation based on the prediction, for always obtaining an image of a stable density. The image forming apparatus performs appropriate image formation control by controlling image forming conditions based on a photosensitive member rotation time, a photosensitive member stop time, a temperature of the environment, an absolute humidity of the environment, and the rotation speed of the photosensitive member.

Abstract: An image forming apparatus includes a photosensitive member driving part that drives a photosensitive member, a counting part that carries out an adding operation when the photosensitive member driving part drives the photosensitive member, and carries out a subtracting operation when the photosensitive member driving part stops the photosensitive member; and a control part that interrupts, when a count value of the counting part becomes equal to or more than a first predetermined value, a printing operation of driving the photosensitive member, forming an electrostatic latent image on the photosensitive member, and fixing a toner adhering to the photosensitive member onto a recording sheet, and causes the counting part to start the subtracting operation.

Abstract: An image forming apparatus is configured to control the timing to switch a development unit by a development rotary after forming an image, based on the size of the image to be formed. Accordingly, if the switching of the development unit is completed within a time period corresponding to a trailing edge margin of an image area, a subsequent color image can be formed without idling an intermediate transfer member, so that the image forming apparatus can suppress or reduce degradation of the throughput.