Abstract: An image forming apparatus includes: a photosensitive member; an intermediate transferring member to which an image formed on the photosensitive member is transferred; a press/release operation controlling section for controlling a pressing of the intermediate transferring member to the photosensitive member and for controlling a release of the pressing; a rotational actuation controlling section for controlling a rotational actuation of the photosensitive member; a judging section for judging a finish of a pressing operation carried out by the press/release operation controlling section; and a start timing controlling section for starting a control for the rotational actuation of the photosensitive member when the judging section judges the finish of the pressing operation by the rotational actuation controlling section.

Abstract: There is described a method of controlling the rotational peripheral speed of the rotating photoreceptor drum to make it constant. The method includes the steps of: detecting angular velocity signals by means of angular velocity detecting device disposed on an axis of the photoreceptor drum; finding deviations from a reference angular velocity, based on the angular velocity signals; storing a profile of the deviations within a one-revolution of the photoreceptor drum in a storage section, while revising the profile in real-time base; applying an arithmetic processing to an angular velocity signal detected at a current rotational-position of the photoreceptor drum by referring data included in the profile obtained in a preceding one-revolution of the photoreceptor drum; and controlling the motor, based on results of the arithmetic processing for the angular velocity signals, so as to compress the deviations from the reference angular velocity as small as possible.

Abstract: The invention concerns an improvement of a drive system of a color image forming apparatus. The color image-forming apparatus includes a plurality of image-forming elements; a plurality of first driving motors, each of which corresponds to each of the image-forming elements, to drive the plurality of image-forming elements; an intermediate transfer element that is disposed opposite the plurality of image-forming elements; a second driving motor to drive the intermediate transfer element; and a controlling section to control the plurality of first driving motors and the second driving motor. In the color image-forming apparatus, the controlling section controls the plurality of first driving motors and the second driving motor independently of each other, so that a first peripheral speed of each of the image-forming elements coincides with a second peripheral speed of the intermediate transfer element.

Abstract: An image forming apparatus comprises: a photosensitive member; an intermediate transferring member to which an image formed on the photosensitive member is transferred; a press/release operation controlling section for controlling a pressing of the intermediate transferring member to the photosensitive member and for controlling a release of the pressing; a rotational actuation controlling section for controlling a rotational actuation of the photosensitive member; a judging section for judging a finish of a pressing operation carried out by the press/release operation controlling section; and a start timing controlling section for starting a control for the rotational actuation of the photosensitive member when the judging section judges the finish of the pressing operation by the rotational actuation controlling section.

Abstract: In an image forming apparatus for forming a color image by superposing component color images, a control device obtains position data representing a forming position of each of plural registration mark images for the component color images with respect to a positional reference value arbitrarily determined, divides the position data into each of a unit reference range representing a range in which one mark image is formed, converts the position data divided for each unit reference range into those based on respective reference values representing the front edge of the unit reference ranges, extracts the position data representing ranges common to the mutually overlapping ranges each of which is represented by a couple of position data corresponding to the rising and falling edges of a passage timing pulse as read position data of the mark image of the component color, and calculates the amounts of positional deviations of the component color images from one another on the basis of the position data extracted.

Abstract: There is described a signal controlling circuit particularly used in a printer or copier. The circuit includes a delay chain section to generate a plurality of delayed clock signals, a synchronized signal detecting section to detect a number of delay stages, a total delay time of which is equivalent to a single period of the reference clock signal, based on delayed clock signals synchronized with an index signal and are selected from the plurality of delayed clock signals, an index signal counting section to count index signals inputted into the index signal counting section, a phase shift calculating section to calculate a phase shift amount in respect to the reference clock signal, and a delayed clock selecting section to select a specific delayed clock signal out of the plurality of delayed clock signals in an alternative way, so as to output the specific delayed clock signal to an external section.

Abstract: There is described a duplex image-forming apparatus having a function of forming images onto both sides of a transfer material. The apparatus includes an image-forming section to respectively form an obverse-side image and a reverse-side image on a photoreceptor element by scanning a light beam, modulated with image signals based on pixel-clock signals and reflected from a polygon mirror rotating at an operating velocity based on polygon-clock signals; a transferring section to transfer said obverse-side image and said reverse-side image onto both surfaces of said recording sheet; a fixing section to fix the images onto both surfaces of said recording sheet; and a clock-frequency changing section to change a pixel-clock frequency, and a polygon-clock frequency, corresponding to a degree of shrinkage of said recording sheet caused by a fixing operation performed in said fixing section, at a transition time of an image-forming operation from one side to another side.

Abstract: There is described a method of controlling the rotational peripheral speed of the rotating photoreceptor drum to make it constant. The method includes the steps of: detecting angular velocity signals by means of angular velocity detecting device disposed on an axis of the photoreceptor drum; finding deviations from a reference angular velocity, based on the angular velocity signals; storing a profile of the deviations within a one-revolution of the photoreceptor drum in a storage section, while revising the profile in real-time base; applying an arithmetic processing to an angular velocity signal detected at a current rotational-position of the photoreceptor drum by referring data included in the profile obtained in a preceding one-revolution of the photoreceptor drum; and controlling the motor, based on results of the arithmetic processing for the angular velocity signals, so as to compress the deviations from the reference angular velocity as small as possible.

Abstract: An image forming device scans in a main scanning direction in synchronization with dot clock pulses for each scanning line to form an image; a basic clock pulse generator generates basic clock pulses with a predetermined interval; a delayed clock pulse generator generates a group of plural delayed clock pulses having different phases respectively; a synchronism detector detects at least two delayed clock pulses synchronizing with an index signal from the plural delayed clock pulses; a calculating section calculates a number of delay stages existing within a given time period based on the two synchronizing delayed clock pulses; and a clock pulse controller selects delayed clock pulses sequentially delayed from the synchronizing delayed clock pulse within a predetermined time period based on the calculated number of delay stages to control a number of clock pulses outputted as the dot clock pulses during the predetermined time period.

Abstract: The invention concerns an improvement of a drive system of a color image forming apparatus. The color image-forming apparatus includes a plurality of image-forming elements; a plurality of first driving motors, each of which corresponds to each of the image-forming elements, to drive the plurality of image-forming elements; an intermediate transfer element that is disposed opposite the plurality of image-forming elements; a second driving motor to drive the intermediate transfer element; and a controlling section to control the plurality of first driving motors and the second driving motor. In the color image-forming apparatus, the controlling section controls the plurality of first driving motors and the second driving motor independently of each other, so that a first peripheral speed of each of the image-forming elements coincides with a second peripheral speed of the intermediate transfer element.

Abstract: The invention concerns an image-forming apparatus employing a clock-generating circuit, which generates dot clock pulses utilized for an image-writing section of the image-forming apparatus. The clock-generating circuit includes a digital-delay dot clock adjusting section to generate first dot clock pulses having a predetermined number of pulses within a predetermined time interval at a constant exposing range of the image-writing section, wherein each period of the first dot clock pulses is slightly increased or reduced by changing a selection for a plurality of delayed clock pulses, which are generated by delaying clock-pulses, outputted from a reference oscillator, in slightly different delay times; and a jitter suppressing section to suppress a jitter component included in the first dot clock pulses, wherein the jitter suppressing section divides the first dot clock pulses to generate second dot clock pulses, and then, multiplies the second dot clock pulses to generate the dot clock pulses.

Abstract: A color image forming apparatus includes a photoreceptor and a plurality of exposure-scanning sections, one of which outputs a reference horizontal-sync. signal. The color image forming apparatus also includes a synchronizing section to synchronize a horizontal-sync. signal, output by another exposure-scanning section, with the reference horizontal-sync. signal, and to synchronize an image tip signal with the reference horizontal-sync. signal. The color image forming apparatus also includes an adjusting section to adjust a commencement of the exposure-scanning operation performed by each of the exposure-scanning sections, based on the reference horizontal-sync. signal output by one of the exposure-scanning sections, and a positional deviation detecting section to detect a positional deviation on the basis of a plurality of marks formed on said photoreceptor by the plurality of exposure-scanning sections.