Abstract: An image forming apparatus include: a plurality of photosensitive drums; a latent image forming unit for forming an electrostatic latent image on each photosensitive drum; a developing unit for developing each electrostatic latent image; a transferring unit for superimposing and transferring the developed images onto a moving record medium; a measurement unit for measuring positions of the transferred images on the record medium; and a control unit for controlling the photosensitive drums, the latent image forming unit, the developing unit, and the transferring unit. The control unit includes: a calculating unit for calculating a value related to alignment errors in the positions measured by said measurement unit in accordance with a sine-curve fitting method; and a correcting unit for correcting the alignment errors by the calculated value.

Abstract: According to an embodiment of the present invention, an image forming apparatus includes a toner image carrier that carries a toner image, a toner image detection sensor that detects a reference toner image on the toner image carrier, a temperature sensor that detects a temperature in the apparatus, and storage section for storing a correlation between each temperature and a drive value for the toner image detection sensor, in which calibration of the toner image detection sensor is performed by acquiring a corresponding drive value from the storage section based on the temperature measured by the temperature sensor and driving the toner image detection sensor at the acquired drive value.

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: In one embodiment, the present invention provides an image forming apparatus that forms a plurality of images using a plurality of image carriers respectively corresponding to the images and stacks those images, the apparatus having a first group to which at least one image carrier among the plurality of image carriers belongs, a second group to which at least one image carrier among the remaining image carriers belongs, and a single detection sensor that detects a first detection information for identifying a rotation timing of the first group image carrier and also detects a second detection information for identifying a rotation timing of the second group image carrier.

Abstract: It is an object to prevent distortions and deviations of images caused by the eccentricity of a driven gear mounted to a rotational shaft of a photosensitive drum. There are provided a driving gear which is secured to a rotational shaft of a rotational driving power source and is rotated at a constant peripheral speed, a driven gear secured coaxially to a rotational shaft of a cylindrical-shaped photosensitive member, a phase control gear having the same diameter as that of the driven gear and having the same rotational speed variation characteristic as that of the driven gear, and a transmission gear, and a driving force from the driving gear is transmitted to the driven gear through the phase control gear and the transmission gear.

Abstract: In one embodiment, image reading apparatuses 100a and 100b start reading an original image after a reading start time Ta has elapsed since detecting the transport timing of an original G on the upstream side in a transport direction Y1 relative to an original reading position R1, adjust the reading start time Ta based on a reading timing adjustment time T1a from when the transport timing of an adjustment sheet P is detected until when original reading portions 200a and 200b read a position considered to be a leading edge P? in a first mark Q1 on the adjustment sheet P, and correct the reading start timing of the original G based on a leading edge reading error correction time T2a stored in advance.

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 forming apparatus including: image forming sections, each image forming section forming an image of a color component among plural color components under a predetermined condition, and forming a pattern of each color component for adjusting the condition; a detecting section that reads the formed patterns so as to perform a temporary detection and a main detection of a deviation from a reference under the condition; and a correction control section that determines whether the deviation of the temporary detection exceeds a predetermined threshold value or not, and when the deviation exceeds the threshold value, executes the main detection to fully detect the deviation so as to correct the condition, wherein the correction control section controls to form the pattern for the temporary detection, the number of the color components for the temporary detection being fewer than those of the patterns to be used for the main detection.

Abstract: To provide an image forming apparatus which can prevent malfunction of the open/close control of a shutter due to erroneous detection of the toner on the transfer belt when the opening and closing of the shutter is detected from the output from an optical sensor. The separation/contact assembly for moving a cleaning member into and out of contact includes an arm rotationally supported on a pivot, an abutment part fixed to the body frame so as to limit the rotation of the arm and a spring for pressing the arm in the clockwise direction. The cleaning member is attached at the distal end of the arm. The cleaning member cleans the transfer belt surface when the shutter is closed, so that the cleaned transfer belt surface can be always detected when the shutter is open.

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: 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: A rotational drive transmission mechanism used in an image forming apparatus for transmitting rotational drive force using an internal gear and an external gear having involute tooth profiles, includes photoreceptor drum drive couplings for transmitting rotational drive force to photoreceptor drums and a transfer drive coupling for transmitting rotational drive force to an intermediate transfer belt drive roller. The internal gears provided for these are so formed that all the drive vectors of the rotational drive force transmitted to the teeth of either the internal gear or the external gear in mesh with the internal gear, are made uniform so as to be oriented either outwards from the center of the rotational axis or inwards toward the center of the rotational axis, equivalently relative to the center of the rotational axis.

Abstract: An image forming apparatus include: a plurality of photosensitive drums; a latent image forming unit for forming an electrostatic latent image on each photosensitive drum; a developing unit for developing each electrostatic latent image; a transferring unit for superimposing and transferring the developed images onto a moving record medium; a measurement unit for measuring positions of the transferred images on the record medium; and a control unit for controlling the photosensitive drums, the latent image forming unit, the developing unit, and the transferring unit. The control unit includes: a calculating unit for calculating a value related to alignment errors in the positions measured by said measurement unit in accordance with a sine-curve fitting method; and a correcting unit for correcting the alignment errors by the calculated value.

Abstract: An image forming apparatus includes a controller for detecting the opening and closing of a shutter from the output from an optical sensor and controlling the opening and closing operation of the shutter based on the detected result. The controller determines that if the optical sensor is turned “ON” within a predetermined period of time from when the shutter begins opening, the operation of the shutter from the closed state to the open state is correctly detected. When no reflected light is detected by the optical sensor even after a predetermined time has elapsed, the controller determines that an anomaly has occurred and closes the shutter and repeat another detecting process.

Abstract: In an embodiment of the present invention, an image forming apparatus includes a transfer belt that primarily transfers a toner image formed on a photosensitive drum; a secondary transfer unit including a transfer mechanism portion that secondarily transfers the primarily transferred toner image to a paper; an optical sensor that detects a reference toner image on the transfer belt; and a shutter that protects a detection face of the optical sensor, wherein a separation/contact mechanism portion disposed so as to be brought into contact with both of the shutter and the secondary transfer unit is provided, and the separation/contact mechanism portion allows the shutter to move so as to open and allows the secondary transfer unit to move so as to separate from the transfer belt when the reference toner image is detected by the optical sensor, and allows the shutter to move so as to separate from the transfer belt when the secondary transfer unit is drawn out from an apparatus main body.

Abstract: There is provided an image forming apparatus that includes couplings for photoreceptor drums, couplings for waste toner transporting screws, and couplings for developing rollers, that transmit driving force to each of a plurality of driving shafts for driving a process portion that performs image formation by an electrophotographic method, and a plurality of coupling attaching/detaching members for attaching/detaching the plurality of coupling members, so as to drive the process portion. In the image forming apparatus, the plurality of coupling attaching/detaching members are provided so as to be movable independently, and the image forming apparatus includes a coupling attaching/detaching member driving mechanism that operates the coupling attaching/detaching members in association with each other.

Abstract: A sub CPU of an image forming section forms a toner image based on test line data on an intermediate transfer belt, detects an inclination of the formed toner image for each color component, calculates an adjustment indicative value for correcting the detected inclination for each color component, and outputs the adjustment indicative values to the BK adjusting section, C adjusting section, M adjusting section, and Y adjusting section, respectively, of an inclination adjusting section. The BK adjusting section, C adjusting section, M adjusting section, and Y adjusting section generate, based on the respective adjustment indicative values obtained from the sub CPU, adjustment amounts for an inclination adjustment process to be executed on image data, execute the inclination adjustment process based on the generated adjustment amounts, and output the obtained image data to the respective LDs of an exposure unit.

Abstract: It is an object to prevent distortions and deviations of images caused by the eccentricity of a driven gear mounted to a rotational shaft of a photosensitive drum. There are provided a driving gear which is secured to a rotational shaft of a rotational driving power source and is rotated at a constant peripheral speed, a driven gear secured coaxially to a rotational shaft of a cylindrical-shaped photosensitive member, a phase control gear having the same diameter as that of the driven gear and having the same rotational speed variation characteristic as that of the driven gear, and a transmission gear, and a driving force from the driving gear is transmitted to the driven gear through the phase control gear and the transmission gear.

Abstract: An image forming apparatus with an image adjusting function using a adjustment patterns transferred on an endless belt including; a calculation unit that obtains, based on the measured positions of the adjustment patterns, a deviation in a rotating direction and/or in a width direction, respectively; and an adjustment unit that adjusts an image to be formed based on each obtained deviation, the adjustment patterns including a first oblique pattern obliquely intersecting with one straight line extending in the width direction of the endless belt in a right front direction and a second oblique pattern obliquely intersecting with the line in a left front direction, the calculation unit obtaining the deviation in the rotating direction from an average of the deviations of the first and second oblique pattern in the rotating direction and obtaining the deviations of the first and second oblique pattern in the width direction, respectively.

Abstract: An LD switch is turned ON to output image data outputted from an image processing section to a laser diode, and to irradiate a laser light to a photosensitive drum. The number of pixel dots included in the image data outputted from the image processing section is computed by line basis to detect an image density based on the total sum of the pixel dots of each color at a timing when the image data of Nth line is outputted from the image processing section. The detected image density is compared with a threshold value to turn OFF the LD switch at a timing when the image data of (N+?)th line is outputted when the image density is greater than the threshold value. This suppresses a variation in a rear-end-void length due to sheet slippage.