Abstract: A multiply-connecting image forming system in which a second image forming apparatus forms an image on a recording material on which an image has been formed by a first image forming apparatus, the multiply-connecting image forming system suppressing degradation in quality of an output image when only the second image forming apparatus continues duplex image formation because the first image forming apparatus has run out of toner during the duplex image formation.

Abstract: An image forming apparatus includes a direct transfer control unit that controls a direct transfer unit and a first image forming unit so as to directly transfer an image onto a transfer sheet, an indirect transfer control unit that controls an intermediate transfer unit and a second image forming unit so as to transfer images onto the intermediate transfer unit, a secondary transfer control unit that controls contact/separation between the direct transfer unit and the intermediate transfer unit, a first alignment control unit that corrects an amount of misalignment among the images formed on the intermediate transfer unit, thereby performing a first alignment control process, and a second alignment control unit that corrects an amount of misalignment of an image directly transferred onto the transfer sheet with respect to the image on which the first alignment control process has been performed, thereby performing a second alignment control process.

Abstract: An image forming apparatus includes a problem-occurrence determining unit, a problem-occurrence area determining unit, and a notifying unit. If the problem-occurrence determining unit determines that a problem has occurred in an image forming process, the problem-occurrence area determining unit determines whether the problem is caused by a toner filling process on the basis of toner-filling control data and toner-supply control data. The notifying unit then notifies the determination as to whether the problem is caused by the toner filling process.

Abstract: There is provided an image formation device, comprising: an image forming unit configured to execute image formation to form an image on a recording medium; a holding body configured to move relatively with respect to the image forming unit and to hold an image formed thereon by the image forming unit; a controller that controls the image forming unit to form a correction pattern in an area on the holding body, the area corresponding to an image formation area defined on the recording medium when the image formation is executed for the recording medium; a measurement unit configured to measure a position of the correction pattern formed on the holding body; and a correction unit configured to correct an image formation position of the image formation unit based on a measurement result of the measurement unit.

Abstract: An image forming apparatus with a correction function for correcting density of an image, including: an image bearing member configured to convey the image in a first direction; and a controller configured to perform a bias correction and a ? correction for the density, wherein the controller includes: a test patch generator configured to generate on the image bearing member a test patch including a first test patch and a second test patch; a first density sensor configured to detect density of the first test patch; a second density sensor configured to detect density of the second test patch; a selector configured to select one of a first detection signal from the first density sensor and a second detection signal from the second density sensor as a bias-correction detection signal and another detection signal as a ?-correction detection signal.

Abstract: An image-forming apparatus includes: a forming unit that forms an image on an image holder that is a rotating body holding an image; a measuring unit that measures a rotation amount of the image holder with reference to a certain position on the image holder; a determining unit that: identifies a position on the image holder from which an image is to be formed by the forming unit, according to the rotation amount measured by the measuring unit; if, while a plurality of images are successively formed on the image holder, an image for density correction is to be formed, postpones forming of the image for density correction until a timing arrives at which one image of the plurality of images is to be formed from a predetermined position on the image holder, and when the timing arrives at which the one image of the plurality of images is to be formed from the predetermined position on the image holder, determines to start forming of the image for density correction from the predetermined position, instead of form

Abstract: An image forming device and method improves image quality by detecting the density of a pattern and adjusting the voltage applied to a developer supply member if necessary in response to the detected density. The pattern can be a medium duty tone pattern, which is relatively sensitive to environmental changes that can affect image density. The density detection pattern can be produced and detected after every predetermined number of sheets are printed, to maintain an acceptable image density during large print jobs. The pattern is formed on the surface of a transferring unit, which transfers the sheets.

Abstract: An image forming apparatus includes an image carrier and a detection unit. The image carrier is stretched around a plurality of rolls. The detection unit detects a density of a toner image formed on the image carrier, based on an amount of regularly reflected light from a surface of the image carrier. A detection length where the detection unit performs the detection in a movement direction of the image carrier is longer than a length, in the movement direction of the image carrier, of a deformation area where a deformation of the image carrier is caused.

Abstract: An image forming apparatus, comprises: a plurality of color image forming units each forming an image for correction for each different color on a different paper to output a correction chart; an operation unit for accepting an input of density correction instruction information corresponding to each of the plurality of color image forming units based on the correction chart; a control unit for setting color of the image for correction according to the density correction instruction information input by the operation unit, generating the image for correction for the set color, and causing the image for correction to be formed on the paper by the color image forming unit in order to output the correction chart; and a density unevenness correction unit for correcting density unevenness of each pixel in a main scanning direction for each of the plurality of color image forming units based on the density correction unevenness information input by the operation unit.

Abstract: An image forming apparatus includes an image holding member, a visible image detecting unit, a shielding part, a conveying passage, and a medium contact part. The visible image detecting unit includes a detecting part and detects a visible image, and the detecting part is disposed to face the image holding member. The shielding part is supported to be movable between a shielding position where the detecting part is shielded, and a detection permitting position where the detecting part is exposed. The medium contact part is supported to be movable between an entry position where the medium contact part enters a conveying passage, and a medium contact position where the medium contact part comes into contact with a medium and recedes from the entry position. The image forming apparatus moves the shielding part while interlocking with the movement of the medium contact part.

Abstract: Multi-color document processing systems and methods are described in which the toner detachment field distribution curve is measured as a function of transfer field and the curve is shifted by adjustment of one or more toner state adjustment actuators to facilitate operation at lower transfer field levels for mitigating retransfer and other high field defects.

Abstract: The invention relates to a method and a device for controlling the circumferential register in a digital multi-color printing machine for printing sheets during a printing process, whereby, for each sheet, at least one register mark per color printing unit of the multi-color printing machine is produced, assigned to said sheet and defined with respect to its position, and whereby, based on the determination of the position of the register marks of a sheet, the circumferential register of at least one sheet, which follows the sheet associated with said determined register marks downstream of the printing process, is controlled. In duplex printing a sheet by recto and verso printing with the invention, register marks are applied for each side and, in order to control recto and verso printing of at least one subsequent sheet, said register marks are analyzed.

Abstract: A characterization procedure for the a detector in a toner patch sensor of an electrophotographic image forming device is performed with the toner patch sensor operatively connected to the image forming device's power supply. During the characterization procedure, a gain setting is determined that produces a predetermined target output from the toner patch sensor based on electromagnetic radiation reflected from a reference reflectivity sample. Subsequently, a toner patch is generated by the image forming device and a reflectance of the toner patch is measured based on the gain setting, with the toner patch sensor operatively connected to the power supply. The measurement(s) may then be used to adjust at least one electrophotographic image forming parameter. More than one reference reflectivity sample may be used, with corresponding gain settings stored in the image forming device.

Abstract: An image forming apparatus includes an image carrier, a developer carrier, a runout measurement information storage unit to store runout measurement information of the image carrier and the developer carrier, including runout amounts on the circumference of the image and developer carriers in a development area, a development gap measurement information storage unit to store information obtained by measuring a development gap when runout measurement points of the image and developer carriers face each other, and a development electric field strength control unit to obtain each development electric field strength based on the runout measurement information and the development gap measurement information, and determine control contents of development electric field strength control to cause the entire development electric field strengths to fall within an acceptable range of a target electric field strength to perform the control contents.

Abstract: The subject embodiments disclose an electrostatic transfer control method that avoids undesired retransfer effects. A printing device develops and transfers several control patches. The patches are transferred at different electrostatic set points and a control strategy is utilized involving one or more density sensors to measure the transferred toner patches whereby the obtained density information can be used to compute the optimal value of electrostatic transfer bias. Print operators can adjust the bias value based on preferences for predetermined standards.

Abstract: Electrophotographic (EP) streaking compensation is performed. A tonescale is measured for each column and a per-column gain computed to compensate for variations. An adjustment tonescale is determined and a per-column adjustment-tonescale gain computed to correct for remaining error after the per-column gain is applied. The two corrections are used together to provide improved compensation quality.

Abstract: An image-forming device includes an image bearing member, a data providing unit, an image-forming unit, a detecting unit, a first calculating unit, a determining unit, and a second calculating unit. The image bearing member has a surface moving at a surface speed. The data providing unit provides pattern data indicative of a target test pattern to be formed on a target position of the surface in response to a test instruction. The image-forming unit forms an actual test pattern on an actual position of the surface in accordance with the pattern data provided from the data providing unit, and configure to form an image in response to an image-forming instruction. The detecting unit detects the actual position. The first calculating unit calculates a deviation of the actual position from the target position. The determining unit performs a first determination of whether the surface speed when the data providing unit receives the test instruction is stable or unstable.

Abstract: An image forming apparatus includes an image carrier, a toner-image forming unit, a photosensor, an information obtaining unit, and a toner-amount calculating unit. The toner-image forming unit forms a toner image on the image carrier with toner. The photosensor detects a toner area where the toner is sticking to the image carrier. The information obtaining unit obtains particle-size-change information about how particle size distribution of the toner changes over time. The toner-amount calculating unit calculates a toner amount of the toner image based on the toner area and the particle-size-change information.

Abstract: There is provided an apparatus for developing a latent image recorded on an imaging surface, including: a housing defining a reservoir storing a supply of developer material comprising toner; a donor member positioned in the housing, spaced from the imaging surface, for transporting toner on an outer surface of the donor member to a region opposed from the imaging surface, a print quality system for monitoring a plurality of xerographic actuator parameters, the print quality system generating a feedback signal if at least one of a plurality of xerographic actuator parameters is beyond a predefined threshold limit; and system for translating the donor member from a first predefined spacing to a second predefined spacing from the imaging surface in response to the feedback signal from the print quality system.

Abstract: A method and apparatus for faster monochrome printing in an in-line electrophotographic printer is described. The printer is configured such that it has more light emitting sources for use in an image transfer assembly for black than for image transfer assemblies for any other color in the printer. When printing a color print job, less than all of the light emitting sources in the black image transfer assembly are used. A print controller directs print data for a monochrome print job to all of the available light emitting sources in the black image transfer assembly and increases the print medium transport speed. The system and method may be configured to operate with dedicated data channels for each light emitting source or may share some data channels for monochrome and color print jobs.

Abstract: An apparatus and method that determines toner age in a printing apparatus. The method can include placing an imaging surface cleaner in contact with an imaging surface. The method can include placing a toner patch on the imaging surface. The method can include rotating the imaging surface in a process direction. The method can include measuring a frictional interaction between the imaging surface cleaner and the imaging surface as the toner patch passes the imaging surface cleaner. The method can include determining whether toner should be purged based on the measured frictional interaction. The method can include purging the toner if the toner should be purged.

Abstract: In an image forming apparatus, a control device obtains an amount of toner in a first area and an amount of toner in a second area. The first area is defined on a conveying member that is in contact with a photosensitive member. The transfer of toner is assured in the first area of the conveying member, but is not assured in the second area. The control device determines a toner condition based on a difference in the amount of toner between the first area and the second area. When the difference in the amount of toner is larger, the control device determines that the toner is in a deteriorated condition. When the difference in the amount of toner is smaller, the control device determines that the toner is not in the deteriorated condition.

Abstract: A method is provided of determining the cause of artifacts in images produced by an electrophotographic (EP) printer. A reference image is printed and artifacts in it are detected. After printing normal images, a test image is printed and artifacts in it are detected. If a detected artifact in the test image does not correspond to a detected artifact in the reference image, a characteristic frequency spectrum of the artifact in the test image is determined. Run-out on rotatable imaging components is measured, and a characteristic frequency spectrum of each is determined. The test image spectrum is compared to each component spectrum to identify which component is causing the artifact.

Abstract: An image forming apparatus including: an image forming unit that forms an image; a carrier that carries and conveys the image; a detecting unit that detects a first adjustment image based on a light reception result of reflection of light projected toward the carrier; and an adjusting unit that adjusts a formation condition of an image to be formed on a sheet based on a result of the detection of the first adjustment image, wherein the image forming unit forms a second adjustment image having a first mark on the carrier, and wherein when the detecting unit detects the second adjustment image based on a light reception result of reflection of light projected toward the carrier, the adjusting unit adjusts a position of the first adjustment image to be formed on the carrier in the orthogonal direction by using a second orthogonal direction length of the first mark.

Abstract: In a color misalignment detection method, an alignment pattern is obtained by designating a plurality of lines having line width and line intervals formed by superposing a line image of a black color as a reference color and a line image of a color other than the reference color, for example, a cyan line image, as one patch, and continuously forming these patches by shifting the relative position between the line images of the two colors by an optional quantity. An alignment pattern detection sensor has a light emitting diode and a photodiode. These elements are arranged along the scanning direction of the alignment pattern such that the photodiode can only receive diffused reflected light of reflected light from the alignment pattern. A spot shape of the light emitting diode and a spot shape of the photodiode are both formed in a square shape.

Abstract: An image forming apparatus includes a first image forming unit for forming a first developer image; a second image forming unit for forming a second developer image; a transfer unit for transferring at least one of the first developer image and the second developer image; a separation contacting unit for moving at least one of the first image forming unit and the second image forming unit to a first position and a second position; a density measurement unit for measuring a first image density and a second image density of the first developer image; and a control unit including a density calculation unit for calculating a difference between the first image density and the second image density and a density correction unit for correcting a density of the first developer image according to the difference.

Abstract: In an image forming apparatus, a density adjustment unit causes to form a cleaner toner image on a surface of an image carrier and remove the cleaner toner image for density adjustment, and causes to form a test pattern after removing the cleaner toner image. The cleaner toner image is formed to cover a whole area on which the test pattern may be formed.

Abstract: An apparatus (100) and method (200) that evaluates printing apparatus cleaner performance. The method can be performed in a printing apparatus that can include an intermediate transfer belt (150), an intermediate transfer belt sensor (155), a developer (115), a photoreceptor (110), and a photoreceptor cleaner (120). The method can include placing (220) marking material on the photoreceptor using the developer. The method can include cleaning (230) the marking material on the photoreceptor using the photoreceptor cleaner. The method can include transferring (240) the marking material to the intermediate transfer belt. The method can include sensing (250) marking material on the intermediate transfer belt using the intermediate transfer belt sensor.

Abstract: A printing apparatus includes an image forming section which forms a toner image of the image to be printed on a recording medium; a transport belt which transports the toner image formed by the image forming section; a light-emitting section which emits a light to the transport belt; a first light-receiving section which is disposed at a position through which a regular reflection light, of the light emitted from the light-emitting section, reflected from the transport belt passes; a second light-receiving section which is disposed at a position different from the position of the first light-receiving section; a transmissive member which is disposed at a position through which the light emitted from the light-emitting section and a reflection light, of the light, reflected from the transport belt pass and which transmits the light and the reflection light.

Abstract: An image forming apparatus including an image carrier; an intermediate transfer member having a first portion and a second portion that has a higher glossiness than that of the first portion; a primary transfer member; a light source to emit light to the intermediate transfer member side; a detector to detect intensity of reflected light emitted from the light source and then reflected from the intermediate transfer member and a density adjustment pattern formed on the intermediate transfer member; a processor including a light-emission intensity adjuster to adjust light-emission intensity from the light source based on detected intensity of light reflected from the second portion of the intermediate transfer member; and an image forming condition controller to control image forming conditions for forming a toner image based on the detected intensity of the light reflected from the density adjustment pattern formed on the intermediate transfer member.

Abstract: A prediction table is stored in an NVM and an in-apparatus temperature is measured by a temperature sensor, a registration control adjustment based on the prediction table is carried out if an absolute value of a variation in the in-apparatus temperature is smaller than a threshold, and a registration adjusting patch is formed to actually measure a positional shift amount if the absolute value of the variation in the in-apparatus temperature is equal to or greater than the threshold. When the positional shift amount measured actually is greatly different from a value of the prediction table, the value of the prediction table is modified into the actually measured value.

Abstract: An image forming apparatus and a control method of the image forming apparatus. The image forming apparatus includes a photosensitive medium, a charger to charge the photosensitive medium, an exposing unit to expose light to the photosensitive medium to form a latent image on the photosensitive medium, a developing unit which is disposed opposite to the photosensitive medium to develop the latent image into a visible image, a density sensing unit to sense a density of an area of the photosensitive medium, and a controller to determine whether a preset developing condition corresponds to a background image generating condition based on the density sensed by the density sensing unit and to adjust the developing condition based on the determination.

Abstract: An image forming apparatus includes an image bearing member to bear a toner image, a transfer device to transfer the toner image onto a recording medium, and a moving device controller to control a moving device that moves the transfer device such that the moving device moves the transfer device to contact the image bearing member during transfer of the toner image on the image bearing member to the recording medium; separates the transfer device from the image bearing member as a toner patch on the image bearing member passes through the transfer area; and maintains the transfer device in contact with the image bearing member from a preceding transfer of a toner image to a succeeding transfer of a toner image during continuous printing, as at least one of areas between successive toner images on the image bearing member without the toner patch passes through the transfer area.

Abstract: Disclosed is an image forming apparatus including an image forming unit which performs image forming on a paper, an image carrier on which a toner image is formed by the image forming unit, a patch image generation unit which generates a patch image for image density detection so as to be disposed between toner images, a patch density sensor which detects a density of the patch image, a correction unit which performs correction processing to match a detected density and an aimed density by comparing the detected density of the patch image detected by the patch density sensor and the aimed density of the patch image which is set in advance, a toner deposit control unit which controls a toner deposit when the image forming unit performs image forming, and a paper interval control unit which control an interval between consecutive papers.

Abstract: An image forming apparatus which includes a photosensitive member and an image forming station. The image forming station includes a charging device for charging the member, an exposure device for exposing the member to light, a developing device for developing an electrostatic latent image on the member, and a bias applying device for applying a developing bias. The image forming apparatus also includes, a transfer device for transferring a toner image to a sheet, a setting device for setting an AC voltage, an executing device for executing a test mode, a density detecting device for detecting the density of the test image, and an adjusting device for adjusting an image forming condition for the station. When the executing device executes the test mode, test images can formed at various AC voltages.

Abstract: An image forming apparatus, having an exposing unit for exposing a photosensitive body to form a_latent image, a developing unit for forming a developer image corresponding to the latent image, a carrier body moved through a portion opposite to the photosensitive body onto which the developer image formed on the photosensitive body is transferred, a mark forming unit for controlling the exposing unit to form a mark on a surface of the carrier body, a light sensor for sensing light reflected by the carrier body, an edge detector for sensing an edge of the mark on the carrier body based on an_output of the light sensor and a deciding unit for deciding a positional relation between a focal point of the exposing unit and the surface of the photosensitive body based on the edge detected by the edge detector.

Abstract: An image forming apparatus that is capable of carrying out processes such as an image forming process in an efficient manner while reducing downtime. Laser beam is emitted onto an intermediate transfer belt. The light intensities of light scattered from the laser beam reflected by at least a part of the surface of the intermediate transfer belt are detected, and light intensity distribution information on the distribution of the detected light intensities are acquired. Phase information on phases on the intermediate transfer belt is acquired based on the light intensity distribution information. An image forming process in which an image is formed on the intermediate transfer belt is carried out in synchronization with a predetermined phase included in the acquired phase information.

Abstract: A method of automatically monitoring and controlling print quality in digital printing with a first and second scanner capturing an image from different locations in the printing engine. In an exemplary embodiment, a first scanner captures an image from a surface internal to the print engine while an external scanner captures an image from a printed sheet. If the external print image quality is acceptable, the internally captured image is saved as a reference. The system periodically compares internally captured images with the saved reference and provides automatic image correction if the variation from the reference is within a correctable range. If the image variation is not within a correctable range, the system runs a new test print and creates a new reference image.

Abstract: A sensor used for determining area coverages of each colorant in a printed image is provided. The sensor includes a plurality of sensing elements for determining area coverages of each colorant in a printed image that includes a plurality of colorants including a black colorant. One of the sensing elements is an infrared sensing element configured to measure infrared reflection, and the others of the sensing elements are each configured to detect a visible color.

Abstract: A toner density is calculated from outputs of light-receiving elements based on a difference between a reflection property of a supporting member and a reflection property of a toner pattern. Light-emitting elements aligned in one direction that is inclined to a sub-direction emit a detection light in such a manner that a distance between adjacent spots falling on the supporting member in a second direction is equal to or smaller than a width of the toner pattern in the second direction. The light-receiving elements receive a reflected light reflected from the supporting member and/or the toner pattern. The light-receiving elements are aligned, opposed to the supporting member, in a one direction corresponding to the light-emitting elements.

Abstract: A color image forming apparatus having photosensitive members; developing devices for developing electrostatic latent images formed on the photosensitive members into toner images with developers comprising toner and carriers; toner concentration sensors for detecting toner concentrations of the developers in the respective developing devices; a toner image bearing member for bearing the toner images temporarily; a toner adherence amount sensor for detecting toner adherence amounts of the toner images held on the image bearing member; and a controller for calculating, with respect to the developing devices, individual optimal developing bias voltage ranges within which a target toner adherence amount can be achieved while the toner concentrations of the developers are within a predetermined toner concentration range from a lower limit to an upper limit, so as to specify a common optimal developing bias voltage range that are commonly suitable for all the developing devices to achieve the target toner adherenc

Abstract: An image forming apparatus includes a toner image forming device that forms a toner image by using at least one of a plurality of toners that include a color toner and a first transparent toner; an intermediate transfer body to which the toner image is transferred; a second transfer unit that transfers the toner image to a recording medium; and a controller that acquires characteristic information that represents a characteristic of in-plane resistance variation of a currently-used recording medium before the toner image forming device forms the toner image, and if the characteristic information indicates that the in-plane resistance variation of the currently-used recording medium is larger than a predetermined value, controls the toner image forming device so that the toner image forming device forms a transparent toner image in such a way that a color toner image is superimposed on the transparent toner image on the intermediate transfer body.

Abstract: A method for determining a location on an image bearing surface of an image printing system where a toner image is to be printed is provided. The method comprises generating a first signal from a detector that is configured to detect a reference mark on the image bearing surface, and a second signal from a clock system that counts incremental movements of the image bearing surface, determining a first value that correlates the first signal and the second signal, where the first value corresponds to a value of the second signal at a start of characterization of the image bearing surface, and determining a second value using the first value, where the second value provides the location on the image bearing surface where the toner image is to be printed.

Abstract: A scanning apparatus and a reference light quantity determining method includes scanning a patch that does not overlap previously established reference colors but displays each of the previously established reference colors in a plurality of regions that are spaced a portion from each other, and determining reference light quantities based on the scanning result.

Abstract: A supply control unit is configured to, in a successive image-forming operation, perform a process of successively generating a driving control pattern for a toner supply device based on image information of each page, and synthesizing an unused portion of the driving control pattern which is obtained by eliminating a portion of the driving control pattern already reflected on a driving control of the toner supply device from the driving control pattern generated based on image information of a previous page with a driving control pattern generated based on a subsequent page.

Abstract: An image forming apparatus includes a first forming unit that forms a color image on a first image-carrier using a color toner, a first transfer unit that transfers the color image formed on the first image-carrier to a transfer medium at a first transfer bias, a second forming unit that, using an invisible toner absorbing infrared light or ultraviolet light, forms on a second image-carrier a code image representing information by an arrangement of dots, and a second transfer unit that transfers the code image formed on the second image-carrier to the transfer medium at a second transfer bias higher than the first transfer bias.

Abstract: A control device includes an acquiring unit acquiring code image data expressing a code image having dots arranged in an array that expresses information; a generating unit extracting the dots from the code image and generating patch image data expressing patch images having the dots orderly arranged in different densities; an image-formation control unit controlling an image forming unit so as to form the patch images based on the patch image data in accordance with a preset image forming condition by using an invisible toner; a measuring unit measuring densities of the patch images; and a changing unit changing the image forming condition if at least one measured density is outside a density range set according to a corresponding dot density based on a correspondence relationship between the measured densities and densities of the dots, so that all of the measured densities are set within the corresponding density ranges.

Abstract: An image forming apparatus including a latent image carrier; a developing device to develop a latent image formed on a surface of the latent image carrier with toner to form a toner image; a transfer device to either directly transfer the toner image onto a recording medium, or to primarily transfer the toner image from the latent image carrier onto an intermediate transfer body and then secondarily transfer the toner image from the intermediate transfer body onto a recording medium; a post-transfer imaging unit to photograph the surface of the latent image carrier or the intermediate transfer body after transfer of the toner image; and a control unit to control one or more image forming conditions based on a quantified value for residual toner of a detection pattern formed on the surface of the latent image carrier or the intermediate transfer body.

Abstract: A representative configuration of an image forming apparatus according to the invention is provided. The image forming apparatus has a plurality of developing devices which develops an electrostatic latent image formed on a photosensitive drum into a toner image using developer of plural colors. The image forming apparatus includes a density sensor which detects the amount of toner of the toner image for each color. In a case where it is determined that the amount of toner of any color departs from a predetermined range based on the detection result of the density sensor, a development condition of the rest developing devices other than the developing device departing from the predetermined range is changed such that the image densities developed by the respective developing devices are equal to each other.

Abstract: An image forming apparatus that is capable of generating highly accurate read timing of a patch image, thereby achieving highly accurate density adjustment and improving color stability. A patch image for color adjustment is read in read timing generated when a trigger bar is detected. The patch image and the trigger bar that are to be read by a color sensor are formed on a transfer material. Image formation is executed by a printer controller in an image forming condition set differently for the trigger bar and for the patch image.