Abstract: An image forming apparatus in which a plurality of color component images of different colors, which include a reference color (e.g. black) serving as a reference and adjustment colors (e.g. cyan, magenta and yellow) to be adjusted, are formed on respective photosensitive drums and then transferred to a transfer belt. Respective positions of the color component images transferred to the transfer belt are detected by a CCD. Timing adjustment can be performed so that the difference between the detected position of each of the color component images and a prescribed position is not more than a predetermined value, based on the reference color image as the reference. In this case, the color component images are formed on the corresponding photosensitive drums with the same timing by utilizing a single polygon mirror.

Abstract: An original reading device includes a registration roller located upstream of an original reading position in an original transport path for adjusting the timing of feeding an original to the original reading position. There is at least one original feed roller for transporting the original which has been fed from an original loading tray into the original transport path toward the registration roller. A rotary motion controller is also provided, and it causes the original feed roller closest to the registration roller to rotate when a rear part of the original close to a trailing edge thereof passes over the original feed roller closest to the registration roller.

Abstract: A color registration method in a color image forming apparatus including a plurality of drum-type photoconductors for driving some or all of the photoconductors having the same diameter to match pitch fluctuations which correspond to a rotational cycle of the photoconductors, the method including: a first measurement step for forming a first registration image for each color and measuring formation positions of a plurality of predetermined portions in each registration image; a second measurement step for forming a second registration image for each color and measuring formation positions of a plurality of predetermined portions in each registration image; a calculation step for calculating a periodic fluctuation component being contained in the images in different colors and corresponding to the rotational cycle of the photoconductors so as to obtain phases thereof; and a step for adjusting a rotational phase of the photoconductors in order for the obtained phases matching to each other, wherein the interval

Abstract: A color image forming apparatus including: a plurality of drum-type photoconductors for forming an image in a different color on each peripheral surface and the photoconductors having at least two different diameters; a plurality of driving sections for driving each photoconductor at a driving speed in accordance with the diameter so that each photoconductor rotates at a predetermined peripheral speed; a correction signal output section for outputting a speed correction signal to correct a periodic pitch fluctuation included in each formed image; and a drive control section for controlling the driving section to correct the driving speed of each photoconductor by the speed correction signal, wherein the speed correction signal is a signal having the same cycle as a rotational cycle of each photoconductor.

Abstract: A color test image of each color composed of a plurality of partial images arranged at predetermined intervals in the moving direction of a conveyance belt is formed, at a position on the conveyance belt separated from relative positions where the respective color images are formed by distances according to the respective colors. A detection sensor detects the position of each partial image, and the distance between corresponding partial images in the respective colors is calculated. The distance between the respective color test images by finding an average value of a plurality of partial image distances is calculated, and based on the calculated distance, an adjustment amount for adjusting a position of forming each color image on the medium is calculated so that the respective color images are superimposed on each other without causing color misregistration.

Abstract: An image forming apparatus includes an image forming unit that forms a color image in which a plurality of color component images are superimposed; and a formation controlling unit that allows the image forming unit to form images for adjustment of formation positions of the respective color component images. The formation controlling unit allows the image forming unit to form, for each color, a plurality of adjustment images having different tilts with respect to a main scanning direction. A shift of a detected position of each adjustment image from a reference position in which each adjustment image should be formed is calculated, a tilt and an intercept of a regression line that uses the reference positions and the calculated shifts as variables are calculated, and a shift in the main scanning direction and a shift in a sub-scanning direction are determined based on the calculated tilt and intercept.

Abstract: An image device includes a movable member, a guide shaft, and a shaft bearing. The movable member moves back and forth inside the device along a guide shaft when reading or recording image information. The guide shaft includes an arc portion in at least part of a cross-section. The shaft bearing is penetrated by the guide shaft at two locations in the movement direction that differ from the center of gravity in the movable member. The shaft bearing includes two inclined faces contacted by the arc portion of the guide shaft in the cross-section. The respective two inclined faces of the shaft bearing are at an angle ?f (rad) and an angle ?r (rad) with the perpendicular direction. The angle ?f (rad) and the angle ?r (rad) satisfy the following inequality: cos {?/2?(?f+?r)}>0.

Abstract: Multiple photoconductive drums on which images with different color components are formed respectively are rotated using individual motors, multiple adjustment images are formed at a predetermined interval along the cycle length of one rotation of each photoconductive drum, the reference phases for the rotation of the respective photoconductive drums are determined based on the maximum portions of the divergences between the predetermined interval and the detection interval of each adjustment image, and the individual motors are controlled so that the respective reference phases determined are aligned. The image forming region corresponding to the cycle length of one rotation of the photoconductive drum is divided into four or more even numbered regions, the, divergence amount of each region is calculated, and the maximum portions of the divergences are determined based on the difference between the divergence amounts of the divided regions being away from each other by a half cycle length.

Abstract: An image forming apparatus in which a plurality of color component images of different colors, which include a reference color (e.g. black) serving as a reference and adjustment colors (e.g. cyan, magenta and yellow) to be adjusted, are formed on respective photosensitive drums and then transferred to a transfer belt. Respective positions of the color component images transferred to the transfer belt are detected by a CCD. Timing adjustment can be performed so that the difference between the detected position of each of the color component images and a prescribed position is not more than a predetermined value, based on the reference color image as the reference. In this case, the color component images are formed on the corresponding photosensitive drums with the same timing by utilizing a single polygon mirror.

Abstract: An image formation apparatus that comprises: a plurality of laser diodes that form color-component images that correspond to a plurality of color components onto a plurality of corresponding photosensitive drums respectively; and a transfer belt onto which the color-component images that are formed on the respective photosensitive drums are transferred; and adjusts the image formation timing based on the positions of the color-component images that are transferred to the transfer belt; and when adjusting the image formation timing, the respective laser diodes form color-component images at formation intervals that correspond to an integral multiple of the period of a periodic noise. Adjustment of the image formation timing is performed at high precision.

Abstract: Rack gear(s) of far-side paper guide(s) is/are constituted such that manner(s) of meshing with pinion gear(s) is/are made tight at respective region(s) corresponding to location(s) for constraining paper of standard size(s) (e.g., A4 landscape and B4 portrait) capable of being contained within paper supply apparatus(es), and such that manner(s) of meshing therewith is/are made loose elsewhere.

Abstract: A color test image of each color composed of a plurality of partial images arranged at predetermined intervals in the moving direction of a conveyance belt is formed, at a position on the conveyance belt separated from relative positions where the respective color images are formed by distances according to the respective colors. A detection sensor detects the position of each partial image, and the distance between corresponding partial images in the respective colors is calculated. The distance between the respective color test images by finding an average value of a plurality of partial image distances is calculated, and based on the calculated distance, an adjustment amount for adjusting a position of forming each color image on the medium is calculated so that the respective color images are superimposed on each other without causing color misregistration.

Abstract: An original reading device includes a registration roller located upstream of an original reading position in an original transport path for adjusting the timing of feeding an original to the original reading position. There is at least one original feed roller for transporting the original which has been fed from an original loading tray into the original transport path toward the registration roller. A rotary motion controller is also provided, and it causes the original feed roller closest to the registration roller to rotate when a rear part of the original close to a trailing edge thereof passes over the original feed roller closest to the registration roller.