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 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: 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 including: a first and a second photoconductor groups constituted of one or more photoconductors respectively; a first and a second drive control sections for controlling the drive of the first and the second photoconductor groups respectively to rotate the photoconductors thereof, wherein the rotational phases of the first photoconductor group and the second photoconductor group are adjusted to be matched therebetween; and the first and the second drive control sections control so that predetermined profile of a target speed is applied to the first and second photoconductor groups wherein, in the target-speed profile, the first photoconductor group starts rotating after a elapse of a predetermined startup delay time from the second photoconductor group starts rotating, and both groups end at a same final speed predetermined for full-color image formation, wherein the startup delay time is predetermined based on measurements of times needed for each of the first and the second photo

Abstract: An image forming apparatus including: a first and a second photoconductor groups constituted of one or more photoconductors respectively; a first and a second drive control sections for controlling the drive of the first and the second photoconductor groups respectively to rotate the photoconductors thereof, wherein the rotational phases of the first photoconductor group and the second photoconductor group are adjusted to be matched therebetween; and the first and the second drive control sections control so that the first and the second photoconductor groups are driven simultaneously with an equal target speed during a formation of a image, wherein an initial drive speed is lower than a predetermined speed for image-formation, and after the first and the second photoconductor groups reaches the initial drive speed, the target speed is changed from the initial drive speed to the speed for image-formation.

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: A document reading device includes a movable member and a flexible document holder. The document holder is fixed at a first end to a free end of the movable member. The document holder is also fixed at a second end to the vicinity of a right-side end of a bottom surface of the document reading device. A portion of the document holder positioned immediately below a pivot axis of the movable member is not fixed to the bottom surface. When the movable member is pivoted to expose a portion of a document transport path, the document holder, except for the first and second ends as fixed to the bottom surface, hangs down without being folded.

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: 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.

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: An image forming apparatus including: an output image forming section for forming an image and a pattern on a supporting medium under a prescribed condition; an output section for transferring the formed image on a recording sheet; a correction section for performing reading of the formed pattern and correcting the condition based on a result of the reading; and a correction control section for controlling operations of the output image forming section, the output section, and the correction section, wherein the correction control section identifies whether or not an area where the image is to be formed and an area where the pattern is to be formed overlap each other, and when the areas are identified that they do not overlap each other, the correction control section controls the output image forming section to simultaneously form the image and the pattern in parallel on the supporting medium.

Abstract: A document reading device includes a document transport and, for reading a document image, an optical reader having a movable exposure which stops at a predetermined reading position and emits light onto the document. A guide member guides the document to the reading position to form a predetermined inclination angle with respect to a flat-plate face of a support, which supports the document being transported when it passes over the reading position. A transport path is formed with the support so that the document passing over the reading position is transported along the flat-plate face. A detection member detects a leading end position of the guide member, the predetermined reading position being set to within a predetermined distance in a transport direction from the leading end of the guide member, which is known beforehand to be stain-free.

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 document reading device includes a movable member and a flexible document holder. The document holder is fixed at a first end to a free end of the movable member. The document holder is also fixed at a second end to the vicinity of a right-side end of a bottom surface of the document reading device. A portion of the document holder positioned immediately below a pivot axis of the movable member is not fixed to the bottom surface. When the movable member is pivoted to expose a portion of a document transport path, the document holder, except for the first and second ends as fixed to the bottom surface, hangs down without being folded.

Abstract: A document reading device includes a document transport and, for reading a document image, an optical reader having a movable exposure which stops at a predetermined reading position and emits light onto the document. A guide member guides the document to the reading position to form a predetermined inclination angle with respect to a flat-plate face of a support, which supports the document being transported when it passes over the reading position. A transport path is formed with the support so that the document passing over the reading position is transported along the flat-plate face. A detection member detects a leading end position of the guide member, the predetermined reading position being set to within a predetermined distance in a transport direction from the leading end of the guide member, which is known beforehand to be stain-free.