Abstract: An image reading apparatus which is capable of successfully reading an image off an original by correctly detecting a size of the original without degrading productivity even if mixed-size originals are placed on an original tray with edges not aligned. An image reading unit reads an image off an original passing through a reading position. An original size detection sensor detects an original. A first original size is determined using a result of detection by the original size detection sensor, and a second original size is determined using the image read off the original. The first original size or the second original size is adopted as an original size.

Abstract: An image forming apparatus can inhibit occurrence of defective images caused when a buffer consumption amount in sector correction exceeds a previously estimated capacity. The image forming apparatus comprises a line buffer for temporarily storing image data. The image forming apparatus performs correction processing of the image data to correct distortion of the image to store the corrected image data in the line buffer. Further, the image forming apparatus forms images on a recording medium based on the image data having experienced the correction processing. The CPU of the image forming apparatus determines whether a size of the image data having experienced the distortion correction by a first correction value based on a sector correction seed value exceeds the number of lines in the line buffer. If it is determined that it exceeds the number of lines, the CPU obtains a second correction value, correcting the first value.

Abstract: An image forming apparatus which can reduce the required number of line buffers and random number generation circuits when performing a magnification changing process in a band process. The CPU 51 determines a range of a random number value (random number value rnd) which is generated by a random number generator, based on the scanning width (band process width d) and the length in a sub-scanning direction of an area (sub-scanning length ay). The CPU 51 receives a random number (random number value rnd), which is in the above range, and performs image processing in which a pixel is inserted or deleted at the position determined by the received random number (random number value rnd).

Abstract: An image forming apparatus includes an image forming unit for forming an image on a recording medium, a fixing unit for fixing the image on the recording medium, a storage unit configured to store image data representing the image, a first generation unit for generating a first position information which represents a position of a target pixel in a first direction which corresponds to a conveyance direction of the recording medium. The apparatus further includes a second generation unit for generating a second position information which represents a position of the target pixel in a second direction which is perpendicular to the first direction; a setting unit for setting, based on magnification changing information in the first direction which corresponds to a conveyance direction of the recording medium, a division condition for dividing the image data representing the image into two or more areas in the first direction.

Abstract: An image reading apparatus which is capable of successfully reading an image off an original by correctly detecting a size of the original without degrading productivity even if mixed-size originals are placed on an original tray with edges not aligned. An image reading unit reads an image off an original passing through a reading position. An original size detection sensor detects an original. A first original size is determined using a result of detection by the original size detection sensor, and a second original size is determined using the image read off the original. The first original size or the second original size is adopted as an original size.

Abstract: An image forming apparatus for easily setting a parameter for avoiding an occurrence of defective image by the sector deformation is provided. The image forming apparatus forms a test image. The test image having a first line drawing and a second line drawing, each of which is extending in a first direction, and the first line drawing and the second line drawing are provided at different positions in a second direction which is perpendicular to the first direction. Further, the image forming apparatus obtains the length information of the first and the second line drawings. Based on the length information of the first and the second line drawings, a correction condition is set. Then, the image forming apparatus corrects the image data based on the correction condition according to a position of the second direction.

Abstract: An image forming apparatus that suppresses occurrence of color shift in images transferred from image bearing members onto an intermediate transfer member. A surface of each of a first photosensitive drum and second photosensitive drums is charged. An exposure device, provided for each photosensitive drum, forms an electrostatic latent image by exposing an associated one of the charged photosensitive drums. A developing device, provided for each photosensitive drum, develops the electrostatic latent image with toner. An intermediate transfer belt friction-drives the photosensitive drums for rotation and has the developed images transferred thereon. Timing for exposing the second photosensitive drums is controlled based on a first surface distance from an exposure light irradiated position to a primary transfer position of the first photosensitive drum, and a second surface distance from an exposure light irradiated position of each second photosensitive drum to a primary transfer position thereof.

Abstract: An image forming apparatus which inhibits occurrence of defective image caused when buffer consumption amount in the sector correction exceeds a previously estimated capacity. The image forming apparatus comprises a line buffer for temporarily storing image data. The image forming apparatus performs correction processing to the image data to correct distortion of the image to store the corrected image data in the line buffer. Further, the image forming apparatus forms images on a recording medium based on the image data having experienced the correction processing. The CPU of the image forming apparatus determines whether a size of the image data having experienced the distortion correction by a first correction value based on the sector correction seed value exceeds the number of lines in the line buffer. If it is determined that it exceeds the number of lines, the CPU obtains a second correction value, in which the first value is corrected.

Abstract: An image forming apparatus for easily setting a parameter for avoiding an occurrence of defective image by the sector deformation is provided. The image forming apparatus forms a test image. The test image having a first line drawing and a second line drawing, each of which is extending in a first direction, and the first line drawing and the second line drawing are provided at different positions in a second direction which is perpendicular to the first direction. Further, the image forming apparatus obtains the length information of the first and the second line drawings. Based on the length information of the first and the second line drawings, a correction condition is set. Then, the image forming apparatus corrects the image data based on the correction condition according to a position of the second direction.

Abstract: An image forming apparatus includes an image forming unit for forming an image on a recording medium, a fixing unit for fixing the image on the recording medium, a storage unit configured to store image data representing the image, a first generation unit for generating a first position information which represents a position of a target pixel in a first direction which corresponds to a conveyance direction of the recording medium. The apparatus further includes a second generation unit for generating a second position information which represents a position of the target pixel in a second direction which is perpendicular to the first direction; a setting unit for setting, based on magnification changing information in the first direction which corresponds to a conveyance direction of the recording medium, a division condition for dividing the image data representing the image into two or more areas in the first direction.

Abstract: An image forming apparatus which can reduce the required number of line buffers and random number generation circuits when performing a magnification changing process in a band process. The CPU 51 determines a range of a random number value (random number value rnd) which is generated by a random number generator, based on the scanning width (band process width d) and the length in a sub-scanning direction of an area (sub-scanning length ay). The CPU 51 receives a random number (random number value rnd), which is in the above range, and performs image processing in which a pixel is inserted or deleted at the position determined by the received random number (random number value rnd).

Abstract: An image forming apparatus that suppresses occurrence of color shift in images transferred from image bearing members onto an intermediate transfer member. A surface of each of a first photosensitive drum and second photosensitive drums is charged. An exposure device, provided for each photosensitive drum, forms an electrostatic latent image by exposing an associated one of the charged photosensitive drums. A developing device, provided for each photosensitive drum, develops the electrostatic latent image with toner. An intermediate transfer belt friction-drives the photosensitive drums for rotation and has the developed images transferred thereon. Timing for exposing the second photosensitive drums is controlled based on a first surface distance from an exposure light irradiated position to a primary transfer position of the first photosensitive drum, and a second surface distance from an exposure light irradiated position of each second photosensitive drum to a primary transfer position thereof.

Abstract: An image forming apparatus accumulates the number of input print jobs when a control circuit of the image forming apparatus recognizes that, during the execution of the first print job having a sheet post-processing setting, a subsequent new print job having no sheet post-processing settings is input. If the accumulated number of input print jobs is less than or equal to a predetermined value, the image forming apparatus allows the interruption of the first print job by the subsequent new job.

Abstract: An image forming apparatus, which forms an image by forming an electrostatic latent image on a photosensitive member with a laser beam, developing the electrostatic latent image with a developer to obtain a developer image, and transferring the developer image to a sheet, includes a light source which outputs the laser beam for exposing the photosensitive member; a PLL circuit which generates a multiplied clock that is obtained by multiplying a reference clock; a pulse-width modulating circuit which outputs a pulse-width-modulated signal based on image data and the multiplied clock in order to drive the light source; and a CPU which obtains image data to be input to the pulse-width modulating circuit and, when it is unnecessary to output the pulse-width-modulated signal based on the obtained image data, controls the PLL circuit so as not to generate the multiplied clock.

Abstract: An image forming apparatus which is capable of properly correcting a scanning length while suppressing occurrence of moiré fringes to reduce degradation of image quality. A laser drive device generates laser beam by driving a laser beam source on an auxiliary pixel basis according to a lighting pattern that defines a pattern for turning on or off the laser beam on an auxiliary pixel basis. A CPU sets the scanning magnification of a photosensitive member in a main scanning direction. Further, the CPU sets the lighting pattern, based on the image data, according to the set scanning magnification, pixel by pixel basis such that the lighting pattern becomes aperiodic in a sequence of pixels. The CPU outputs the lighting pattern to the laser drive device.

Abstract: An image forming apparatus which forms an image by forming an electrostatic latent image on a photosensitive member with a laser beam, developing the electrostatic latent image with a developer to obtain a developer image, and transferring the developer image to a sheet, the image forming apparatus including: a light source which outputs the laser beam for exposing the photosensitive member; a PLL circuit which generates a multiplied clock that is obtained by multiplying a reference clock; a pulse-width modulating circuit which outputs a pulse-width-modulated signal based on image data and the multiplied clock in order to drive the light source; and a CPU which obtains image data to be input to the pulse-width modulating circuit and, when it is unnecessary to output the pulse-width-modulated signal based on the obtained image data, controls the PLL circuit so as not to generate the multiplied clock.

Abstract: An image forming apparatus for forming a tone image using a density pattern method has a ROM for storing a density pattern corresponding to each of a number of tones and an ideal density value of each density pattern, and a sensor for detecting the optical density of an image that has been formed by an image forming unit that forms the image by an electrophotographic method. An image is formed by the image forming unit based upon the density pattern corresponding to each tone, and the density pattern corresponding to each tone is modified based upon optical density, which has been obtained by detecting the density of the image by the sensor, and the ideal density value of each density pattern.

Abstract: An image forming apparatus for forming a tone image using a density pattern method has a ROM for storing a density pattern corresponding to each of a number of tones and an ideal density value of each density pattern, and a sensor for detecting the optical density of an image that has been formed by an image forming unit that forms the image by an electrophotographic method. An image is formed by the image forming unit based upon the density pattern corresponding to each tone, and the density pattern corresponding to each tone is modified based upon optical density, which has been obtained by detecting the density of the image by the sensor, and the ideal density value of each density pattern.

Abstract: An image forming apparatus for forming a tone image using a density pattern method has a ROM for storing a density pattern corresponding to each of a number of tones and an ideal density value of each density pattern, and a sensor for detecting the optical density of an image that has been formed by an image forming unit that forms the image by an electrophotographic method. An image is formed by the image forming unit based upon the density pattern corresponding to each tone, and the density pattern corresponding to each tone is modified based upon optical density, which has been obtained by detecting the density of the image by the sensor, and the ideal density value of each density pattern.

Abstract: An image forming apparatus accumulates the number of input print jobs when a control circuit of the image forming apparatus recognizes that, during the execution of the first print job having a sheet post-processing setting, a subsequent new print job having no sheet post-processing settings is input. If the accumulated number of input print jobs is less than or equal to a predetermined value, the image forming apparatus allows the interruption of the first print job by the subsequent new job.