Abstract: A sheet conveyance device for conveying a recording medium includes a fixed roller, a movable roller, an urging member, and a shock absorber, and an image forming apparatus including the sheet conveyance device. The position of the fixed roller is fixed. The movable roller is disposed opposite the fixed roller to contact the fixed roller, thereby defining a nip. The urging member urges the movable member to contact the fixed roller in the absence of the recording medium in the nip and allows the movable member to separate from the fixed roller by an amount corresponding to a thickness of a recording medium when the recording medium enters the nip. The shock absorber absorbs displacement energy generated when the urging member urges the movable roller to contact the fixed roller again after the recording medium passes through the nip.

Abstract: A main controlling part is configured to choose and execute either a constant belt speed control which controls a driving motor (a driving source for an intermediate transfer belt) to move the intermediate transfer belt at a predetermined target belt speed or a constant motor speed control which rotates the driving motor at a predetermined target rotational speed according to a print command, and then, prior to a first-time print job, after executing a writing position correcting process while moving the intermediate transfer belt under the constant belt speed control, forms a color shift detecting image by switching from the constant belt speed control to the constant motor speed control, measures a difference between amounts of color shift, and executes a speed correcting process for correcting the target rotational speed of the driving motor in the constant motor speed control based on the measurement result.

Abstract: An image forming apparatus includes an endless belt member; a drive unit moving the endless belt member; a first detecting unit detecting a rotating speed of the drive unit; a second detecting unit detecting an endless transport speed of the endless belt member; and a control unit controlling the rotating speed of the drive unit based on a first detection signal from the first detecting unit or a second detection signal from the second detecting unit selectively depending on a selection condition. Upon selection of the first detection signal in accordance with the selection condition, the control unit corrects the rotating speed of the drive unit using the second detection signal such that an average value of the endless transport speed of the endless belt member approaches a target average value.

Abstract: An image forming apparatus includes a control unit to control a latent image support with a target rate; a first unit to detect patterns; plural parts to be detected revolving with the support; a second unit to detect passing of the part; a first generating unit to obtain an amplitude and a phase of fluctuation and a pattern for canceling out the fluctuation from the amplitude and the phase; a second generating unit to perform a process to obtain an amplitude and a phase of fluctuation while the support rotates once or more, perform the process again, calculate a change in the amplitude and phase, and generate another pattern for canceling out the change; and a correcting unit to correct the target rate by superimposing the patterns with the target rate.

Abstract: A multicolor imaging system includes a controller which adjusts a phase difference in rotations of photoreceptors based on information detected by a rotary position detector, and drive elements for photoreceptors which generate a velocity fluctuation in the same cycle as that of a transfer unit. The controller is configured to concurrently adjust the phases of the photoreceptors and those of the drive elements so that a registration error in four color toner image on an intermediate transfer belt is reduced to a minimum.

Abstract: A printer according to the present invention is a so-called tandem-type printer, and has a configuration that a motor gear is directly connected to an M-photoconductor driving gear and an idler gear is directly connected to a Y-photoconductor driving gear and the M-photoconductor driving gear. A diameter of the Y and M photoconductors driving gear, a distance between transfer sections of the Y and M photoconductors, a motor gear input angle, and an idler input angle are set so that an absolute value of a value obtained by subtracting 1 from an ideal amplitude ratio, which indicates a ratio of an ideal amplitude of an eccentric component of the Y-photoconductor driving gear to an actual amplitude of an eccentric component of the M-photoconductor driving gear, is equal to or less than a maximum allowable amplitude ratio.

Abstract: In an image forming apparatus, a servomotor is used as a shared driving motor. A motor driver includes a gain changing unit that changes proportional gain. When a monochrome mode is selected, a driving control unit sets the proportional gain lower than a value that is set in a color mode.

Abstract: An imaging apparatus is disclosed that includes plural image carriers on which different-colored toner images are formed, the image carriers being driven and rotated to transfer the different-colored toner images onto one of an endless transfer member that is driven to rotate in contact with the image carriers or a transfer material that is carried by the endless transfer member. The imaging apparatus includes a phase calculating unit that extracts a periodic rotational variation component of each of the image carriers from a combination of periodic rotational variation components generated within said imaging apparatus and calculates a rotational phase of each of the image carriers based on the extracted periodic rotational variation component, and a rotational phase adjusting unit that adjusts a rotation stop phase of each of the image carriers based on the calculated rotational phase.

Abstract: In an image forming apparatus, a rotation detector detects an angular velocity or an angular displacement of a shared drive motor, or an angular velocity or an angular displacement of a photosensitive element. A drive control unit executes a process for controlling a drive speed of a drive source of the photosensitive element based on a result of detection by the rotation detector.

Abstract: A color-drift correcting method in an image forming apparatus includes a first and a second color-drift correcting. The first color-drift correcting includes correcting the color-drift amount in a sub scanning direction and a skew relative to the reference color image being based on each color-drift amount of at least three mark-patterns, each of which mark-pattern is formed each color image, so as to decide a corrected-image line as a virtual image line for each color, assumed when the color images are superposed onto a transfer media. A second color-drift correcting includes correcting the color-drift amount in the sub scanning direction so that the virtual image lines corresponding to each of the colors other than the reference color intersect with the virtual image line of the reference color at at least two points.

Abstract: After detecting a speed fluctuation pattern per rotation of a photosensitive drum, a process that forms an image based on image data while causing the photosensitive drum to rotate at a nonstandard linear speed is executed as an image forming process by driving a process driving motor that drives the photosensitive drum to curb a speed fluctuation of the photosensitive drum by using a driving speed fine tuning pattern. Before executing the image forming process, a fine-tuning-pattern correcting process is executed for correcting the driving speed fine tuning pattern of the process driving motor, based on the nonstandard linear speed.

Abstract: An image forming apparatus includes a plurality of image carriers, an optical writing unit, a plurality of developing units, a transfer member, a transfer unit, an image sensor, and a control unit. In at least one embodiment, the image sensor is configured to sense a positional displacement detection pattern including visible images on the transfer member to detect a positional displacement between the visible images on each of the plurality of image carriers. The control unit is configured to execute a positional displacement correction control to calculate an amount of the positional displacement and determine respective target drive speeds of the plurality of drive sources. The control unit is also configured to control so that the positional displacement detection pattern is formed when the plurality of drive sources are driven at substantially identical speeds and the positional displacement detection pattern thus formed is sensed by the image sensor.

Abstract: An image forming apparatus includes: image detectors to detect conditions of images, respectively, formed on a transfer member; sensors to detect rotational displacements of latent image carriers, respectively; and a controller to perform at least phase adjustment control and image-to-image displacement control before performing image forming operations on image carriers, respectively. Image-to-image displacement control includes adjusting image forming timing on the image carriers based upon conditions of a detection image (including images transferred from the image carrier) detected by the image detectors, respectively. Speed-variation detection control includes detecting a condition of a speed-variation detection image (including an image transferred from each of image carriers) via the image detectors, and determining speed variation of the image carriers, respectively, per one revolution based upon outputs of the image detectors and the sensors.

Abstract: A driving motor for a color black is shared between a photosensitive body for the color black and a driving roller that drives an intermediate transfer belt not shown. Furthermore, a driving motor for colors yellow, magenta, and cyan is shared between photosensitive bodies for the colors yellow, magenta, and cyan. Driving of the driving motor for the colors yellow, magenta, and cyan is controlled based on a first waveform as a speed fluctuation waveform of the photosensitive body for the color black obtained when the driving motor for the color black is driven at a predetermined speed and second waveforms as speed fluctuation waveforms of the photosensitive bodies for the colors yellow, magenta, and cyan obtained when the driving motor for the colors yellow, magenta, and cyan is driven at a predetermined speed.

Abstract: An image forming apparatus, in which a program for carrying out an image forming method is provided, includes a transfer member to receive respective images formed on a plurality of image bearing members, an image detecting unit to detect the images conveyed on the transfer member, a paper length detecting unit to detect a length of a recording medium in a sheet travel direction, a counting unit to count the number of recording media and to change a count up value according to a detection result by the paper length detecting unit, and a control unit to control an image forming timing with respect to the image bearing members based on a detection timing of the image and to perform a positional deviation adjustment each time a counted value increases by a predetermined amount so as to reduce an amount of a positional deviation of the image.

Abstract: An image forming apparatus includes image forming units, a toner supply device, a common-unit detection device, an initial operation execution device, and a determination device. Each image forming unit is detachably provided in the image forming apparatus, and includes at least a development device containing toner. At least two of the image forming units are common image forming units having a common structure. When the common-unit detection device detects a common image forming unit at installation thereof, the initial operation execution device supplies a predetermined amount of toner to a development device of the common image forming unit and mixes to charge the toner by friction for a predetermined time period. Then, the. determination device detects whether the toner in the development device is charged to a predetermined level, and determines, based on the detection, whether to mix the toner one more time for another predetermined time.

Abstract: An image forming apparatus to form an image on a recording medium, capable of reducing deterioration of image bearer, is disclosed. In one embodiment, the image forming apparatus includes an image bearer, a driver to move the image bearer, a image forming device to form a visible image on the image bearer, a contacting member to form a nip by contacting with the image bearer, and a controller to control the driver for driving stop with a distance shifted on a surface of the image bearer from a start of driving. An amount of the shifted distance is greater than a width of the nip and is not a divisional number of a peripheral length of the image bearer.

Abstract: An image forming apparatus includes a control unit to control a latent image support with a target rate; a first unit to detect patterns; plural parts to be detected revolving with the support; a second unit to detect passing of the part; a first generating unit to obtain an amplitude and a phase of fluctuation and a pattern for canceling out the fluctuation from the amplitude and the phase; a second generating unit to perform a process to obtain an amplitude and a phase of fluctuation while the support rotates once or more, perform the process again, calculate a change in the amplitude and phase, and generate another pattern for canceling out the change; and a correcting unit to correct the target rate by superimposing the patterns with the target rate.

Abstract: An image forming apparatus includes a latent image carrier having a moving surface on which a latent image is formed, a drive control mechanism to control a drive of the latent image carrier so as to match a rotation angular speed of the latent image carrier with a target rotation angular speed thereof, a surface moving member having a moving surface on which an adjustment pattern for use in controlling the drive of the latent image carrier is formed, an image forming mechanism to develop the latent image with toner and transfer a resultant toner image on the surface moving member so as to form the adjustment pattern along a surface moving direction thereof, a pattern sensor to detect the adjustment pattern, a correction mechanism to correct the target rotation angular speed of the latent image carrier based on an amplitude and a phase of a variable component in a pattern interval of the adjustment pattern detected with the pattern sensor.

Abstract: A color printing apparatus having a color registration difference correction function, the color registration difference caused by a difference of rotation speeds of each photosensitive drum after a print mode changes from a one photosensitive drum mode to an all photosensitive drums mode.