Abstract: An image forming apparatus includes image bearers, motors, a reference position detector, and processing circuitry. The circuitry senses a density of a toner image on each bearer; forms an image pattern and senses, based on a detection result of the detector and a sensing result of the density, density unevenness in a rotation cycle and a phase of the density unevenness with respect to a rotational position reference of each bearer; calculates a target phase based on the phase sensed; calculates a relative phase difference based on a rotational position and the target phase of each bearer; selects, as a reference image bearer, an image bearer having a minimum phase correction value, based on a calculation result of the difference; and controls the rotational position of each of the other image bearers with respect to the reference image bearer to the phase correction value, with the motors being driven.

Abstract: A transfer device includes: an endless member in an endless shape that orbits; primary transfer members that are respectively arranged on an opposite side of plural image holding bodies disposed side by side in a circumference direction of the endless member with the endless member interposed between the primary transfer member and the image holding body, and transfer an image held by the image holding body to the endless member; a secondary transfer member that transfers the image transferred to the endless member to a recording medium; an applying roll around which the endless member is wound, that is disposed on a downstream side of all the primary transfer members and on an upstream side of the secondary transfer member in the circumference direction, and that urges the endless member from an inner peripheral surface of the endless member to apply tension to the endless member; an upstream roll around which the endless member is wound, and that is disposed on the downstream side of all the primary transfe

Abstract: An image forming apparatus includes: a circulating member that is a part of a transport path that transports a recording medium; a holding member that is fixed to the circulating member, circulates, and holds a leading end portion of the recording medium; an image forming section that forms an image on the recording medium at an image forming position in a circulation path of the circulating member; and a feeding section that feeds out the recording medium to a holding position where the holding member holds the leading end portion of the recording medium. When a circulation velocity Vg is defined as a velocity at which the circulating member circulates the holding member, a transport velocity of the recording medium is reduced from a first transport velocity V1, which is higher than the circulation velocity Vg, to a second transport velocity V2, which is lower than the first transport velocity V1, before the leading end portion of the recording medium enters the holding position.

Abstract: An image forming apparatus includes an image forming device that forms an image on a recording medium and circuitry that controls the image forming device. The image forming device forms an invisible image with an invisible material on the recording medium and forms a visible image with a visible material on the invisible image. Each of first and second adhesion amounts includes respective adhesion amounts of the visible material and the invisible material per unit area in a portion, in which the visible image is formed on the invisible image, of the composite image. The second adhesion amount is smaller than the first adhesion amount. The controller adjusts the amount of the invisible material included in the second adhesion amount to be smaller than that included in the first adhesion amount, to cause the image forming device to form the image according to the second adhesion amount.

Abstract: In an image forming apparatus capable of turning over a sheet to form images on both sides of the sheet, when duplex printing is executed successively on three or more sheets, a controller causes a first sheet conveyed from an image forming unit and a second sheet conveyed from the image forming unit to be guided into a first path by positioning a guide member in a first position, and then conveyed into a third path by a first roller, and causes a third and subsequent sheets conveyed from the image forming unit to be guided into a second path by positioning the guide member in a second position, and then conveyed into the third path by a second roller.

Abstract: An image forming apparatus includes a transfer unit, a fixing unit, a reverse rotary member pair, a first conveyance path, a second conveyance path, an opening and closing member, a first guide member, a second guide member, and a dividing member. The second guide member is supported by the opening and closing member and forms an inserted portion where a case of the fixing unit is inserted and one side of guide surfaces of the second conveyance path. The second guide member forms one side of guide surfaces of the first conveyance path in a state where the opening and closing member is in a closed position. The dividing member, in the state where the opening and closing member is in the closed position, divides a gap formed between the second guide member and the case inserted into the inserted portion from the second conveyance path.

Abstract: A control portion of an image forming apparatus causes an operation of a first fan start and then causes a second fan to start. The time when the operation of the second fan starts is from a predetermined time before the time when the leading end of one sheet reaches a fixing nip to the time when the rear end of the one sheet passes through the fixing nip. In this way, since the second fan operates after the first fan operates, fine particle dust is hardly discharged to the outside of the image forming apparatus, and it is possible to suppress dew condensation inside the image forming apparatus.

Abstract: An image forming apparatus includes an image bearing member, an optical sensor configured to detect a pattern image formed on the image bearing member, and an attachment member to which the optical sensor is attached. The optical sensor includes a circuit board, a light emitting element and a light receiving element which are provided on a first side of the circuit board, and a connector provided on a second side opposite to the first side of the circuit board. The attachment member has a surface contacting the second side of the circuit board. In an insertion/removal direction of a cable to be connected to the connector, a first thickness, from the surface, of a part of a portion, contacting the second side, of the attachment member is smaller than a second thickness, from the surface, of a portion, not contacting the second side, of the attachment member.

Abstract: According to one embodiment, an image forming apparatus includes: a registration roller; a motor configured to drive the roller; and a controller configured to control the motor. The roller is disposed at a first position on a conveyance path of paper on which an image is to be formed, and sends out the paper toward a second position on the conveyance path. The second position is downstream from the first position on the conveyance path and is an image transfer position on the paper. The controller controls the motor by using both speed control and position control when the leading end of the paper is at a position from the first position to the second position, and controls the motor by using only the speed control when the leading end of the paper reaches the second position.

Abstract: A positional-deviation correcting device includes a reading device and control circuitry. The reading device reads recording media on which marks and each of adjustment charts having different image densities are formed in accordance with the image densities. The control circuitry acquires data on image formation positions of the marks on the recording media, based on a reading result of the marks; and corrects an image formation position of an image to be formed on a recording medium. The control circuitry calculates a correction value of the image formation position corresponding to an image density for each of the image densities corresponding to the adjustment charts on a one-on-one relationship, based on a reading result of the adjustment charts; interpolates correction values corresponding to the image densities on a one-on-one relationship; and calculates a correction value of the image formation position corresponding to another image density different from the image densities.

Abstract: In an image forming apparatus that can form images on both surfaces of a sheet, a first roller conveys a sheet conveyed from a reversal roller and a first motor drives the reversal and first rollers. A one-way clutch restricts transfer of a driving force from the first motor to the first roller while the reversal roller is conveying a sheet in a first direction, and permits transfer of a driving force from the first motor to the first roller while the reversal roller is conveying a sheet in a second direction. Second and third rollers are provided on a downstream side of the first roller. A second motor drives the second and third rollers. A controller drives both of the first and second motors when resuming conveyance of a sheet conveyed on a duplex conveyance path after causing the sheet to await abutment with the second roller.

Abstract: A printer includes a first printing unit responsible for one of preceding printing and subsequent printing that are to be performed on one sheet in overprinting, an other of the preceding printing and the subsequent printing being performed by a second printing unit; and a base-printing controller that causes the first printing unit to print a base for printing by the second printing unit in an operation of forming a test pattern for registration between the preceding printing and the subsequent printing on the sheet.

Abstract: An image forming apparatus is configured to discharge droplets onto a web to form an image. The image forming apparatus includes a conveyor, a web position detector, and control circuitry. The conveyor is configured to convey the web while applying a tension to the web. The web position detector is configured to detect a position of the web during conveyance. The control circuitry is configured to adjust landing positions of the droplets onto the web in a main scanning direction and a sub-scanning direction in accordance with the position of the web detected by the web position detector and control the tension applied to the web by the conveyor. The web position detector is configured to detect the position of the web in a cycle that is at least twice a tension control cycle in which the control circuitry controls a magnitude of the tension.

Abstract: According to one embodiment, an image forming apparatus includes an image forming unit, a sensor, and a control unit. The image forming unit forms a pattern constituted by a plurality of straight lines intersecting each other on a sheet or a transfer belt. The sensor detects the pattern formed on the sheet or the transfer belt. The control unit adjusts a writing position in a main scanning direction on the basis of the pattern detected by the sensor.

Abstract: An image forming apparatus includes image forming devices, image output devices, an endless conveyor, a transfer device, holders, a detector, and circuitry. The image forming devices include image bearers. The image output devices form latent images on the image bearers. The image forming devices form visible images from the latent images. The transfer device transfers the visible images onto the endless conveyor that conveys the visible images in an image conveyance direction. The holders hold the image forming devices interchangeable at holding positions aligned in the image conveyance direction. The detector detects the visible images. The circuitry compares a first visible image of the visible images formed at a specific holding position of the holding positions with a second visible image of the visible images formed at another holding position of the holding positions on the endless conveyor, to correct misalignment between the first and second visible images.

Abstract: An image forming apparatus includes a rotating body to form an image, a sensor to detect a home position of the rotating body, a processor to acquire image density data of the image formed by the rotating body in odd-numbered rotation and even-numbered rotation of the rotating body separately based on a rotation home position signal output by the sensor, extract an image density fluctuation caused by a rotation of the rotating body, and correct an image forming condition based on the image density fluctuation.

Abstract: A first conveyance member reverses a sheet received from a first conveyance path. Second through fourth conveyance members are disposed on a second conveyance path and convey a sheet from the first conveyance member toward the first conveyance path. A restriction portion is capable of restricting driving force of a first driving source from acting on a sheet through the second conveyance member. A controller executes a first operation and a second operation. In the first operation, a second driving source stops driving the third and fourth conveyance members while a first sheet is being nipped at the fourth conveyance member, and a second sheet is conveyed to be abutted with the third conveyance member. In the second operation, the second driving source starts driving the third and fourth conveyance members while the restriction portion restricts driving force of the first driving source from acting on the second sheet.

Abstract: An image forming apparatus includes: plural image forming units that each include plural image forming sections and a first intermediate transfer body to which toner images formed by the plural image forming sections are transferred through first transfer; plural second transfer sections provided in correspondence with the plural image forming units to transfer the toner images on the first intermediate transfer body to a recording medium through second transfer; and a detection device that detects the toner images downstream of a most downstream one of the second transfer sections.

Abstract: An image forming unit forms an image on a sheet. A reverse unit pulls in the sheet from a main conveyance path and reverses a conveyance direction of the sheet to feed the sheet to a sub-conveyance path. A control unit causes a conveyance unit to convey a first sheet that is waiting to the main conveyance path after a trailing end of a second sheet that has been fed from a feeding unit and follows the first sheet has passed through a merging point, and moves a trailing end of the first sheet downstream of a branch point before the second sheet reaches the branch point.

Abstract: There is provided a printing apparatus. The printing apparatus includes: a memory storing a program; and at least one hardware processor configured to execute a process in the program. The process includes: performing pre-printing of overprinting which is an operation of performing pre-printing on a medium and then performing post-printing on the medium; and printing a chart asymmetric with respect to rotation toward a direction of the medium on the medium during test printing related to the pre-printing.

Abstract: An image forming apparatus includes a printer, a sensor, and a processor. The printer forms an image with image forming material of colors on a medium. The sensor detects the image forming material of each color on the medium. The processor forms a pattern with the image forming material of the colors on the medium using the printer, acquires a position of a pattern of each color using the sensor, and after executing correction for bringing positions where images of the other colors are formed close to a position where an image of a reference color is formed based on the position of each pattern, corrects a position where either an image of a first color or an image of a second color is formed by the printer based on a distance between patterns of the first color and second color furthest away from each other.

Abstract: A recording device discharge position adjustor includes a recording device to discharge liquid droplets onto a recording medium; an edge detector unit to detect a lateral edge position of the recording medium in a direction perpendicular to a recording medium conveyance direction; a discharge position adjustor to adjust a discharge position of the liquid droplets from the recording device relative to the recording medium; a controller to adjust the discharge position using the discharge position adjustor; and an edge position converter to convert the edge position of the recording medium detected by the edge detector unit to an edge position at a position of the recording device, in which the controller adjusts the discharge position of the recording device by an adjustment amount corresponding to the edge position of the recording medium at the position of the recording device converted by the edge position converter.

Abstract: An image forming apparatus includes a developing section, an image carrier, a deviation correction section, a specific pixel detection section and a determination section. The developing section forms a visible image on a photoconductor for each type of developer. The image carrier carries the visible images formed in a plurality of the developing sections. The deviation correction section corrects position deviation of the plurality of visible images formed on the image carrier. The specific pixel detection section detects the specific pixel used to form an image with a plurality types of developers. The determination section determines execution of correction in the deviation correction section according to information indicating an amount of the specific pixels.

Abstract: An image forming apparatus includes a conveyor to convey a conveyed object in a conveyance direction, a plurality of head units to perform image formation on the conveyed object, a displacement sensor disposed downstream from the plurality of head units to detect a position adjustment image on the conveyed object, formed by the plurality of head units, and at least one processor configured to adjust an image formation position of at least one of the head units in a direction orthogonal to the conveyance direction, based on a result generated by the displacement sensor. The image forming apparatus further includes a surface sensor to obtain surface data of the conveyed object at a position corresponding to the head unit to be adjusted, and the processor further adjusts the image formation position in the orthogonal direction based on the surface data obtained by the surface sensor.

Abstract: An image forming apparatus is capable of switching thresholds for deciding a color registration amount from a pattern image. A controller controls image forming units to form first and second color patterns of different colors on a rotational image bearing member. The second color pattern is formed at an upstream side of the first color pattern in a rotational direction of the image bearing member. The controller controls a sensor to detect the color patterns. A comparator compares a detection result by the sensor with a threshold, and outputs an output value according to a comparison result. The controller controls the color registration according to the output value. The controller sets a second threshold for the second color pattern based on an edge timing of the output value from the comparator according to the comparison result between the detection result about the first color pattern and a first threshold.

Abstract: An image forming apparatus includes a photosensitive member that rotates at a first speed, an intermediate transfer member that rotates at a second speed lower than the first speed, and a collecting member disposed in a state in which a fixed surface is pressed against the rotating intermediate transfer member. The collecting member collects toner remaining on the intermediate transfer member after a toner image is secondarily transferred from the intermediate transfer member to a transfer material.

Abstract: With reference to a correction value revision parameter table, a periodic non-uniformity correction value corresponding to changed rotational speed is obtained from the correction value revision parameter table, and set as a new periodic non-uniformity correction value corresponding to the rotational speed of a rotary component, and thereby a gradation which is an image formation parameter of image data is corrected.

Abstract: An image forming device is provided. The image forming device may include a transfer belt to move in a preset direction, a plurality of image generators to respectively generate a toner image on the transfer belt, and a controller to output an image generation signal to each of the plurality of image generators such that the plurality of image generators respectively generate a toner image. A plurality of toner images generated using the plurality of image generators are arranged on the transfer belt in parallel to each other, and an arrangement order of the plurality of toner images is identical to an arrangement order of the plurality of image generators.

Abstract: The image forming apparatus includes an adjustment unit that adjusts the position where the electrostatic latent image is formed in a rotation axis direction of a photoconductor in accordance with the position of a sheet that has reached the transfer unit in the rotation axis direction of the photoconductor. The adjustment unit adjusts the position where the electrostatic latent image is formed in the rotation axis direction of the photoconductor in normal printing and does not adjust the position where the electrostatic latent image is formed in the rotation axis direction of the photoconductor in a case where a test image is to be printed.

Abstract: An image forming apparatus includes image bearing members, an intermediate transfer member, a transfer unit, a control unit, and image forming units respectively corresponding to the image bearing members and each configured to form and transfer an image to the intermediate transfer member, which is then transferred to the conveyed recording material. Image patterns on the intermediate transfer member are detected for positional deviation detection. In a first mode, timing of image formation is determined using a first reference. In a second mode, timing of image formation is determined using a second reference. Based on timings at which formed image patterns are detected, the control unit, in the second mode, corrects timing of image formation performed by a second image forming unit or corrects timing at which the recording material is conveyed to the transfer unit.

Abstract: An image forming apparatus includes a photo sensor, which is configured to detect a measurement image formed on an intermediate transfer belt, and a controller. The controller includes a first comparator, a second comparator, an XOR unit, and a CPU. The first comparator is configured to binarize an analog detection waveform, which represents a detection result of a measurement image by the photo sensor, in accordance with a first threshold value to generate a first binary signal. The second comparator is configured to binarize the detection waveform in accordance with a second threshold value to generate a second binary signal. The XOR unit is configured to perform an XOR operation in accordance with the first binary signal and the second binary signal to generate an XOR signal.

Abstract: An image forming apparatus performs misregistration correction based on a detection result of a detection pattern. The detection pattern includes basic patterns arranged at a first interval in a sub-scanning direction. Each basic pattern includes N image groups arranged at a second interval. In the N image groups, a first group including an image at a first angle and a second group including an image at a second angle are arranged alternately in the sub-scanning direction. The first interval corresponds to a distance that a surface of an image carrier moves in a period of M times a first period corresponding to a rotation period of a rotational member, and the second interval corresponds to a distance that a surface of the image carrier moves in a period of 1/(N?1) of the first period.

Abstract: Disclosed herein is an image forming apparatus. The image forming apparatus includes a sensing unit having a window and a sensor which senses a developer through the window, and a shutter device which opens and closes the window, and thereby the sensing unit in a sensible state is maintained, and a lifetime thereof is extendable.

Abstract: Two types of correction data, first correction data and second correction data, are used to correct density on the basis of reading results obtained by a reading unit reading a test image formed on a sheet. The first correction data is data for correcting image density in the rotation axis direction of the photoconductor. The correction using the first correction data is performed in each of multiple areas on the photoconductor which correspond to an area in which a toner image of the test image is formed. The second correction data is data for correcting image density in the rotation axis direction of the photoconductor. The correction using the second correction data is performed in areas outside the area in which the toner image of the test image which is read by the reading unit is formed.

Abstract: To suppress the wrong detection of the image pattern, an image forming apparatus includes a plurality of image forming units respectively configured to form images of different colors, an intermediate transfer member to which a pattern to detect an amount of color misregistration of an image formed by the plurality of image forming units is transferred, a sensor configured to assure reflected light from the pattern on the intermediate transfer member to output an output value in accordance with a measurement result, a comparator configured to compare the output value output from the sensor with a threshold, and a controller configured to control the plurality of image forming units to respectively form a plurality of patterns of different colors on the intermediate transfer member, to control the sensor to measure reflected light from the plurality of patterns.

Abstract: A document reading device includes: a conveying unit configured to convey a document; a background member having a mark for correcting an inclination of the document; a color reading unit configured to read an image of the document and to output color image data; a monochrome reading unit configured to read the image of the document and to output monochrome image data; a switching unit configured to switch between a first state and a second state; and a hardware processor configured to switch into the first state at the time of a color mode, and to switch into the second state at the time of the monochrome mode, configured to detect the inclination of the document, and configured to correct the inclination of the color image data, and to correct the inclination of the monochrome image data, in accordance with the detected inclination of the document.

Abstract: Prediction accuracy of a color misregistration amount in an image formation executed in an image forming apparatus is improved. The image forming apparatus comprises an optical box storing an optical system for irradiating a laser beam from a laser source to a photosensitive drum, a scanner temperature sensor provided near the optical box, and an environmental temperature sensor for detecting a surrounding temperature of the image forming apparatus, and a control section. When image formation is executed, the control section obtains a temperature Tscn detected by the scanner temperature sensor and a temperature Tenv detected by the environmental temperature sensor and calculates a prediction value of a position misregistration amount to the photoreceptor of the laser beam using the difference between Tscn and Tenv.

Abstract: An image forming apparatus according to an embodiment includes an image forming unit that forms a toner image on an image carrier body. A primary transfer member transfers the toner image formed on the image carrier body onto an intermediate transfer body. A secondary transfer member transfers the toner image from the intermediate transfer body onto a recording medium. A control unit applies a cleaning bias to the secondary transfer member while an idle operation of the secondary transfer member is being performed before the toner image is secondarily transferred onto the transferring target material.

Abstract: An image forming apparatus includes: a density unevenness measurement mode processing portion that, in a density unevenness measurement process, detects density of a density unevenness measurement toner image, which has been formed in a rotational direction of the photoreceptor drum, multiple times in the rotational direction and captures in a memory portion all detected density information associating thereof with rotation phases of the photoreceptor drum; and an image quality adjustment processing portion that, in an image quality adjustment mode, detects density of an image quality adjustment toner image, which has been formed at any position in the rotational direction of the photoreceptor drum, in the rotational direction and corrects detected density information based on density information associated with a rotation phase matching a rotation phase where density of the image quality adjustment toner image has been detected among said all density information having been captured in the memory portion by

Abstract: An image forming apparatus includes a photoreceptor, an exposure unit, a developing unit, and a control unit. The control unit sets the toner-layer-forming electric potential difference lower than an electric potential when forming the image on the print medium, forms a combined patch for calibration by the set toner-layer-forming electric potential difference for calibration, so as to adjust the developing-bias potential by measuring a print density of the formed combined patch. The combined patch includes a first patch and a plurality of second patches. The plurality of second patches have a width within a range of 0.2 mm to the predetermined value in the peripheral-velocity direction of the photoreceptor, extend with a length equal to or more than the predetermined value in the rotation-shaft direction of the photoreceptor, and are arranged at a predetermined interval in the peripheral-velocity direction of the photoreceptor.

Abstract: An image forming apparatus includes a movable endless belt, a toner image forming unit, a movable transfer member, a voltage source, a setting portion. When a maximum cumulative value in a case where a length in which an adjusting toner image is formed with respect to a movement direction of the belt at a plurality position with respect to a widthwise direction of the belt perpendicular to the movement direction is accumulated is defined as a representative cumulative value, the setting portion sets the second voltage when the adjusting toner image passing through the transfer portion is a first adjusting toner image so as to be lower than the second voltage when the adjusting toner image passing through the transfer portion is a second adjusting toner image smaller in representative cumulative value than the first adjusting toner image.

Abstract: An image forming apparatus includes a plurality of image forming units, an intermediate transfer member, a detection unit, and a controller. The controller is configured to control the plurality of image forming units to form, on the intermediate transfer member, a pattern image including a first detection image having a reference color among the plurality of detection images and a second detection image having another color among the plurality of detection images. The first detection image and the second detection image are superimposed on a predetermined detection image. The controller is configured to control the detection unit to detect the amount of color misregistration which is related to a relative position of the first detection image and the second detection image, and to determine an adjustment value for adjusting an image write start timing of the other color different from the reference color.

Abstract: An optical scanning apparatus of the present invention includes: a splitting element which splits a light flux emitted from a light source into first and second light fluxes; a deflecting unit which deflects the first and second light fluxes to scan first and second scanned surfaces in a main scanning direction; and an imaging optical system which includes a first imaging lens on which both the first and second light fluxes deflected by the deflecting unit are incident and guides the first and second light fluxes to the first and second scanned surfaces. The condition expressed by ?1.1??1/?2??0.9 is satisfied where ?1 and ?2 are angles within a main scanning cross section between a first axis parallel to the main scanning cross section and directions of incidence of the first and second light fluxes on the deflecting unit, respectively.

Abstract: An image forming apparatus capable of performing color misregistration correction at image forming speeds while reducing downtime. Image forming units form images of different colors. The formed images are transferred to an intermediate transfer belt. A pattern sensor detects color misregistration amounts of color patterns formed on the intermediate transfer belt. A CPU causes the image forming units to form first color patterns at a first speed and the pattern sensor to detect first color misregistration amounts, and causes the former to form second color patterns at a second speed different from the first speed and the latter to detect second color misregistration amounts. The CPU determines third color misregistration amounts at a third speed based on the first and second color misregistration amounts. The third speed is different from the first and second speeds.

Abstract: A belt device includes a belt member, a detected unit, a window, an optical detector, and a regulation member. The belt member is movable in a direction of belt movement. The detected unit disposed on at least one side of the belt in a width direction of the belt intersecting with the direction of belt movement and extending in the direction of belt movement. The window transmits detection light emitted toward the detected unit and reflected light from the detected unit. The optical detector detects the detected unit. The regulation member is disposed on at least one side in a width direction of the window to keep the detected unit away from the window.

Abstract: An image forming apparatus includes an image forming unit that forms a developer image, a transfer portion that transfers the developer image to a transfer object, an endless transfer belt that rotates passing between the image forming unit and the transfer portion, a driving roller that drives the transfer belt to rotate, a plurality of marks provided on the transfer belt and arranged in a rotating direction of the transfer belt, a measurement unit that measures a rotation period of the transfer belt using the plurality of marks, and a controller that adjusts a timing at which the image forming unit forms the developer image, based on a measurement result of the rotation period measured by the measurement unit. A circumferential length L of the transfer belt in the rotating direction has a length based on a natural number multiple of a circumferential length m of the driving roller.

Abstract: An image forming apparatus includes a first image forming unit configured to form a first image in a chromatic color, a second image forming unit configured to form a second image in black, an intermediate transfer member, a sensor, a first adjustment unit configured to adjust the image forming position for the black based on an adjustment value, a second adjustment unit configured to adjust image forming position based on an adjustment condition, and a generation unit configured to generate the adjustment condition. The generation unit generates a first adjustment condition based on a user instruction relating to a first test image having chromatic color on a sheet input from the input unit. The generation unit generates a second adjustment condition based on the reading result of the second test image having black on a sheet from a reading device.

Abstract: A density correction unit (a1) obtains density measurement values of a surface in a measurement section of an image carrier at a first round, (a2) calculates as section background data at the first round respective differences between the density measurement values at the first round and an average value thereof, (a3) obtains density measurement values of a surface at least in the measurement section at a second round, (a4) calculates as section background data at the second round respective differences between the density measurement values at the second round and an average value thereof in a specific section with the same length as the measurement section, and (a5) determines the rotation period on the basis of a correlation between the section background data at the first round and at the second round. Here the measurement section is a part in a circulating direction of the image carrier.

Abstract: A fixing device is equipped with a lower pressure roller, an upper pressure roller and a fixing belt which fix a toner image onto a sheet, by holding and conveying the sheet by a nip portion, and a control unit which controls rotation of the lower pressure roller. The control unit periodically changes a velocity of rotational drive of the lower pressure roller, at a frequency of which a period is shorter than a time needed for the sheet to pass through the nip portion, when the sheet passes through the nip portion.

Abstract: An image formation apparatus includes: an intermediate transfer belt that carries and conveys a developer image formed by an image formation section; a driver that conveys the intermediate transfer belt in a predetermined direction; a transfer device that transfers the developer image carried on the intermediate transfer belt onto a predetermined medium; a first detector that detects a belt conveyance speed, which is the speed of the intermediate transfer belt conveyed; a controller that controls the driver; a conveyer section that conveys the medium to the transfer device; and a second detector that detects a medium conveyance speed, which is the speed of the medium conveyed by the conveyer section. The controller controls driving of the driver on the basis of the belt conveyance speed and the medium conveyance speed.