Abstract: An image forming apparatus includes a rotating polygon mirror, a motor, a bearing portion, a measurement processing portion, and a determination processing portion. The rotating polygon mirror causes a light beam emitted from the light source to be scanned. The motor rotates the rotating polygon mirror. The bearing portion rotatably supports a rotation shaft of the motor via a lubricant. The measurement processing portion measures a transition time that is a time required for the motor to transition from a stationary state to a driving state in which the motor rotates at a predetermined speed. The determination processing portion determines whether or not a maintenance is required, based on the transition time measured by the measurement processing portion.

Abstract: An image forming apparatus includes a rotating polygon mirror, a motor, a bearing portion, a measurement processing portion, and a determination processing portion. The rotating polygon mirror causes a light beam emitted from the light source to be scanned. The motor rotates the rotating polygon mirror. The bearing portion rotatably supports a rotation shaft of the motor via a lubricant. The measurement processing portion measures a transition time that is a time required for the motor to transition from a stationary state to a driving state in which the motor rotates at a predetermined speed. The determination processing portion determines whether or not a maintenance is required, based on the transition time measured by the measurement processing portion.

Abstract: An image forming apparatus includes an image carrier, a motor, a cleaning portion, a measurement processing portion, and a cleaning control portion. The image carrier is configured to carry an electrostatic latent image. The motor is configured to rotate the image carrier. The cleaning portion is configured to clean the image carrier. The measurement processing portion is configured to measure a transition time that is a time required for the motor to transition from a stationary state to a driving state in which the motor rotates at a predetermined speed. The cleaning control portion is configured to control a cleaning time of the cleaning portion or whether or not to cause the cleaning portion to clean the image carrier.

Abstract: In sheet conveying device, first pair of rollers, driven by first driving motor, conveys sheet on conveyance path that passes image forming portion that forms image on the sheet. Second pair of rollers, driven by second driving motor, conveys the sheet on the conveyance path together with the first pair of rollers. Speed difference calculating portion calculates speed difference between speed related to sheet conveyance speed of the first pair of rollers and speed related to sheet conveyance speed of the second pair of rollers. The motor control portion determines target speeds respectively for the first driving motor and the second driving motor based on the speed difference calculated by the speed difference calculating portion, and performs control during non-image formation period so that driving speeds of the first driving motor and the second driving motor respectively become the target speeds.

Abstract: Provided is an image forming apparatus that performs smoothing in conversion of pseudo high resolution without using a large translation table. A smoothing process part performs smoothing based on a density of a peripheral pixel that adjoins a target pixel on edge. When a density change between both sides of the target pixel in a sub scanning direction is larger than a density change between both sides of the target pixel in a main scanning direction, a density of a plurality of pixels after conversion of pseudo high resolution of a sub scanning direction corresponding to the target pixel is mutually changed. Also, when a density change between both sides of target pixel in the sub scanning direction is not larger than a density change between both sides of the target pixel in the main scanning direction, the density set to the same.

Abstract: Provided is an image forming apparatus that performs smoothing in conversion of pseudo high resolution without using a large translation table. A smoothing process part performs smoothing based on a density of a peripheral pixel that adjoins a target pixel on edge. When a density change between both sides of the target pixel in a sub scanning direction is larger than a density change between both sides of the target pixel in a main scanning direction, a density of a plurality of pixels after conversion of pseudo high resolution of a sub scanning direction corresponding to the target pixel is mutually changed. Also, when a density change between both sides of target pixel in the sub scanning direction is not larger than a density change between both sides of the target pixel in the main scanning direction, the density set to the same.

Abstract: In sheet conveying device, first pair of rollers, driven by first driving motor, conveys sheet on conveyance path that passes image forming portion that forms image on the sheet. Second pair of rollers, driven by second driving motor, conveys the sheet on the conveyance path together with the first pair of rollers. Speed difference calculating portion calculates speed difference between speed related to sheet conveyance speed of the first pair of rollers and speed related to sheet conveyance speed of the second pair of rollers. The motor control portion determines target speeds respectively for the first driving motor and the second driving motor based on the speed difference calculated by the speed difference calculating portion, and performs control during non-image formation period so that driving speeds of the first driving motor and the second driving motor respectively become the target speeds.

Abstract: An image forming apparatus includes an exposing section, a pulse generating section, a frequency storing section, an emission control section, a smoothing section, and a driving-current generating section. The pulse generating section generates a periodic pulse signal indicating light amount of light beam emitted by a light source of the exposing section. The frequency storing section stores in advance a plurality of frequencies of the pulse signal. The emission control section selects, in the rendering of each main scanning line, any one of the plurality of frequencies and instructs the pulse generating section to generate the pulse signal having the selected frequency. The smoothing section smoothes the pulse signal generated by the pulse generating section according to the instruction of the emission control section and generates analog signal. The driving-current generating section generates driving current for the light source of the exposing section on the basis of the analog signal.

Abstract: Image forming apparatus includes elements as follows. Light-amount storing section stores, in the main scanning line divided into a plurality of blocks, light amounts of a light beam irradiated on the blocks. Change-data storing section stores a plurality of change data items set in the vicinity of each of block boundaries of the plurality of blocks. The plurality of change data items are used to cope with each of a plurality of events that are likely to affect the image quality in the vicinity of the block boundary. Irradiation control section selects, out of the plurality of change data items, change data for coping with an event selected out of the plurality of events and instructs Pulse generating section to generate, in the vicinity of the block boundary, pulse signal from which analog signal indicating a change in a value represented by the selected change data is obtained.

Abstract: A light scanning device includes an optical unit. The optical unit includes a polygon mirror and a polygon motor. The polygon mirror includes n (n is an integer equal to or larger than 1) mirror surfaces and guides light in a main scanning direction of an image bearing member. The polygon motor includes m (m is an integer equal to or larger than 1 and is coprime with n) poles and rotates the polygon mirror.

Abstract: An image forming apparatus includes a photosensitive body, an exposure unit, a pulse generating unit, a smoothing unit, a drive current generating unit, and a second emitting control unit. The exposure unit includes a light source for emitting a light beam, and causes the light beam emitted from the light source to perform scanning in a main scanning direction, thereby drawing a main scanning line on the photosensitive body. The second emitting control unit causes the light source to emit the light beam, in an APC period of automatically controlling the light quantity of the light beam, by causing the pulse generating unit to generate a pulse signal having a duty ratio of 100 percent, causing the smoothing unit to smooth the pulse signal thereby generating an analog signal, and causing the drive current generating unit to generate a drive current based on the analog signal.

Abstract: Image forming apparatus includes elements as follows. Light-amount storing section stores, in the main scanning line divided into a plurality of blocks, light amounts of a light beam irradiated on the blocks. Change-data storing section stores a plurality of change data items set in the vicinity of each of block boundaries of the plurality of blocks. The plurality of change data items are used to cope with each of a plurality of events that are likely to affect the image quality in the vicinity of the block boundary. Irradiation control section selects, out of the plurality of change data items, change data for coping with an event selected out of the plurality of events and instructs Pulse generating section to generate, in the vicinity of the block boundary, pulse signal from which analog signal indicating a change in a value represented by the selected change data is obtained.

Abstract: An image forming apparatus has an intermediate transfer belt stretched lightly across rollers to move endlessly in a sub-scanning direction upon image formation and has an outer surface to which a toner image formed by a development unit is transferred. A secondary transfer opposing roller is one of the rollers across which the intermediate transfer belt is stretched. A secondary transfer roller contacts the outer surface of the intermediate transfer belt and transfers the toner image on the intermediate transfer belt to recording paper. A movement mechanism moves at least one of the rollers or the secondary transfer roller and changes a pressed state of the intermediate transfer belt by the secondary transfer roller at a nip of the secondary transfer opposing roller and the secondary transfer roller. A movement mechanism control unit controls a travel distance of the roller to be moved by the movement mechanism.

Abstract: An image forming apparatus has a first light controller to shift starts of image writing operations of light sources by a first time interval. A test data storage stores, beforehand, test image data having dot columns formed by one-dot images arranged in a row in a sub-scanning direction and at predetermined intervals in a main scanning direction. An operation controller controls an image carrier at a speed so that adjacent dot images in the sub-scanning direction overlap. A second light controller forms electrostatic latent test images on the image carrier based on timing signals with the image carrier moved by the operation controller, and draws electrostatic latent test images with different time intervals. A density measurer measures densities of the developed test images. A time interval adjusting section adjusts the time interval based on the time interval used to draw the electrostatic latent test image having the lowest measured density.

Abstract: An image forming apparatus includes a pattern formation control unit for forming a plurality of evaluation patterns by repeatedly turning on and off a plurality of light emitters arranged in a row in units of n dots (n is an integer equal to or greater than 1) to irradiate light to a photoconductor while changing write timings of the respective light emitters in a predetermined range, an adjustment unit for improving reliability of density difference information among the plurality of evaluation patterns, and a determination unit for obtaining information on densities of the respective evaluation patterns based on a detection result on the densities of the respective evaluation patterns and determining write timings derived from the evaluation pattern having the lowest or highest density as the write timings of the plurality of light emitters.

Abstract: An image forming apparatus has an intermediate transfer belt stretched lightly across rollers to move endlessly in a sub-scanning direction upon image formation and has an outer surface to which a toner image formed by a development unit is transferred. A secondary transfer opposing roller is one of the rollers across which the intermediate transfer belt is stretched. A secondary transfer roller contacts the outer surface of the intermediate transfer belt and transfers the toner image on the intermediate transfer belt to recording paper. A movement mechanism moves at least one of the rollers or the secondary transfer roller and changes a pressed state of the intermediate transfer belt by the secondary transfer roller at a nip of the secondary transfer opposing roller and the secondary transfer roller. A movement mechanism control unit controls a travel distance of the roller to be moved by the movement mechanism.

Abstract: An image forming apparatus has a first light controller to shift starts of image writing operations of light sources by a first time interval. A test data storage stores, beforehand, test image data having dot columns formed by one-dot images arranged in a row in a sub-scanning direction and at predetermined intervals in a main scanning direction. An operation controller controls an image carrier at a speed so that adjacent dot images in the sub-scanning direction overlap. A second light controller forms electrostatic latent test images on the image carrier based on timing signals with the image carrier moved by the operation controller, and draws electrostatic latent test images with different time intervals. A density measurer measures densities of the developed test images. A time interval adjusting section adjusts the time interval based on the time interval used to draw the electrostatic latent test image having the lowest measured density.

Abstract: A write reference signal generating unit uses horizontal synchronization signals output from BD sensors to generate, for each laser scanning unit of respective image forming units, a main scanning write reference signal for irradiating laser light from a semiconductor laser every other predetermined number of reflective surfaces when photosensitive drums are driven to rotate at a second speed of rotation which is slower than a standard speed of rotation. A phase adjustment unit adjusts the phase of a control signal for driving a polygonal mirror, which is output to a polygon motor of each image forming unit, on the basis of a relative time difference between image write timings of the respective laser scanning units as measured by a time difference measurement unit.