Abstract: An image reading apparatus including: a conveyor that conveys a sheet on which an image is formed by an image forming apparatus; a reader that reads the sheet conveyed by the conveyor, by using a contact image sensor; and a first hardware processor that extracts an edge of the sheet by analyzing a read image by the reader, calculates a blur amount of the edge based on the extracted edge, and calculates a curl amount of the sheet based on the calculated blur amount.

Abstract: An image reading apparatus including: a conveyor that conveys a sheet on which an image is formed by an image forming apparatus; a reader that reads the sheet conveyed by the conveyor, by using a contact image sensor; and a first hardware processor that extracts an edge of the sheet by analyzing a read image by the reader, calculates a blur amount of the edge based on the extracted edge, and calculates a curl amount of the sheet based on the calculated blur amount.

Abstract: An image forming apparatus includes: a conveyor that transports a sheet; an image former that forms an image on front and back surfaces of the sheet being transported in a transportation path and forms marks on the front and back surfaces; a reader that comprises a first line sensor that is disposed on a front surface side and reads the front surface; and a second line sensor that is disposed on a back surface side and reads the back surface; and a controller that: calculates a positional deviation between the images formed on the front and back surfaces based on positions of the marks on the front surface read by the first line sensor and positions of the marks on the back surface read by the second line sensor, and controls the image former to adjust positions of the images formed on the front and back surfaces.

Abstract: An image forming apparatus includes: a conveyor that transports a sheet; an image former that forms an image on front and back surfaces of the sheet being transported in a transportation path and forms marks on the front and back surfaces; a reader that comprises a first line sensor that is disposed on a front surface side and reads the front surface; and a second line sensor that is disposed on a back surface side and reads the back surface; and a controller that: calculates a positional deviation between the images formed on the front and back surfaces based on positions of the marks on the front surface read by the first line sensor and positions of the marks on the back surface read by the second line sensor, and controls the image former to adjust positions of the images formed on the front and back surfaces.

Abstract: An image inspection device includes a hardware processor. The hardware processor (i) captures a read image from a reading device, (ii) compares a reference image and an inspection image obtained by reading a paper sheet targeted for inspection on which an image corresponding to the reference image has been formed with the reading device, to inspect the inspection image, (iii) sets a first alignment region having a predetermined width on a leading end side of each of the reference image and the inspection image in a conveyance direction, and sets a second alignment region having a predetermined width on a rear end side in the conveyance direction, and (iv) corrects the reference image on a basis of amounts of positional deviation of the first alignment region and the second alignment region.

Abstract: An image forming apparatus includes: a photoreceptor; a light source; a rotational polygon mirror including a plurality of mirror surfaces on an outer circumferential surface of a rotating body; and a hardware processor that: controls the light source to perform emission of a light beam; controls to rotate the rotational polygon mirror to perform a sequential primary scanning; and corrects a shift of an exposure position of the light beam; and a clock characteristic changer capable of changing a clock characteristic including at least one of frequency and phase of a write clock, wherein the hardware processor controls to execute two-dimensional exposure with the clock characteristic of the write clock, controls to execute the two-dimensional exposure at a predetermined relative position with respect to the mirror surface, and specifies a mirror surface used for formation of each portion of the detection pattern.

Abstract: An image forming apparatus includes: an image carrier on which an image is formed; a light source that generates a light beam; an optical scanner that executes scanning of the light beam; a reflection surface identifier that identifies each reflection surface of a rotary polygon mirror; a sub-scanning direction driver that relatively moves the image carrier and the light beam to each other; a storage that stores first jitter information; a photodetector that detects scanning of the light beam; a measurement device that generates second jitter information; and a hardware processor that uses the first and second jitter information to change a frequency of a write clock and adjust a phase of the write clock, wherein the hardware processor obtains a correction characteristic for a dot position shift, and changes the frequency of the write clock and adjusts the phase of the write clock.

Abstract: An image forming apparatus includes: a photoreceptor; a light source; a rotational polygon mirror including a plurality of mirror surfaces on an outer circumferential surface of a rotating body; and a hardware processor that: controls the light source to perform emission of a light beam; controls to rotate the rotational polygon mirror to perform a sequential primary scanning; and corrects a shift of an exposure position of the light beam; and a clock characteristic changer capable of changing a clock characteristic including at least one of frequency and phase of a write clock, wherein the hardware processor controls to execute two-dimensional exposure with the clock characteristic of the write clock, controls to execute the two-dimensional exposure at a predetermined relative position with respect to the mirror surface, and specifies a mirror surface used for formation of each portion of the detection pattern.

Abstract: An image forming apparatus includes: an image carrier on which an image is formed; a light source that generates a light beam; an optical scanner that executes scanning of the light beam; a reflection surface identifier that identifies each reflection surface of a rotary polygon mirror; a sub-scanning direction driver that relatively moves the image carrier and the light beam to each other; a storage that stores first jitter information; a photodetector that detects scanning of the light beam; a measurement device that generates second jitter information; and a hardware processor that uses the first and second jitter information to change a frequency of a write clock and adjust a phase of the write clock, wherein the hardware processor obtains a correction characteristic for a dot position shift, and changes the frequency of the write clock and adjusts the phase of the write clock.

Abstract: Provided is an image forming apparatus outputs for each pixel, together with the pixel data, pixel position data which adjusts an irradiation position for each pixel of the laser light in a range of one pixel in a scanning direction, generates a pulse width signal at a pixel position corresponding to the pixel position data and having a pulse width corresponding to the pixel data, generates the laser light based on the pulse width signal, and corrects, via the adjustment by the pixel position data, the pulse widths of the pulse width signals to different values depending on whether the pulse width signals of the adjacent two pixels contact with each other.

Abstract: Provided is an image forming apparatus outputs for each pixel, together with the pixel data, pixel position data which adjusts an irradiation position for each pixel of the laser light in a range of one pixel in a scanning direction, generates a pulse width signal at a pixel position corresponding to the pixel position data and having a pulse width corresponding to the pixel data, generates the laser light based on the pulse width signal, and corrects, via the adjustment by the pixel position data, the pulse widths of the pulse width signals to different values depending on whether the pulse width signals of the adjacent two pixels contact with each other.

Abstract: Disclosed is an image forming apparatus that makes it possible to cope with the deviations in the main-scanning direction when the image forming velocity has been changed. The apparatus includes: a light source; a polygon mirror; a start-position light detecting section to detect a light beam at a main-scanning start point; a stop-position light detecting section to detect the light beam at a main-scanning stop point; a measuring section to measure a time difference between times when the start-position light detecting section and the stop-position light detecting section detect the light beam; a magnification correction data creating section to create magnification correction data for every rotation number of the polygon mirror, based on the main-scanning time; and a magnification factor correcting section to adjust interval distances between positions of exposed dots so as to correct the magnification factor in the main-scanning direction by using the magnification correction data.