Abstract: A belt conveying device includes an endless belt stretched by a plurality of rollers; a drive unit that is connected to one of the plurality of rollers and drives the roller; a plurality of belt velocity detectors that are arranged at a plurality of locations along a belt width direction perpendicular to a moving direction of the endless belt and detect conveyance velocities of the endless belt; and a belt-inclination calculating unit that calculates an inclination of the endless belt in the moving direction from a difference between conveyance velocities of the endless belt detected by the plurality of belt velocity detectors.

Abstract: In a belt moving device that is capable of reducing belt speed fluctuation and positional deviation from a target belt position in a sub-scanning direction and performing highly precise position control in a main scanning direction, and an image forming apparatus that uses this belt moving device to prevent color shift in both the main scanning direction and sub-scanning direction of a formed image such that a high-quality image can be formed, belt shift control means reduce shift position variation within a single round trip of an endless belt by feeding back a target value for canceling out the shift position variation within a single round trip of the endless belt and feeding forward a value obtained by multiplying an inverse transfer characteristic of moving means by a transfer characteristic of a target value of the moving means in relation to the control content of the moving means.

Abstract: A belt conveying device includes an endless belt stretched by a plurality of rollers; a drive unit that is connected to one of the plurality of rollers and drives the roller; a plurality of belt velocity detectors that are arranged at a plurality of locations along a belt width direction perpendicular to a moving direction of the endless belt and detect conveyance velocities of the endless belt; and a belt-inclination calculating unit that calculates an inclination of the endless belt in the moving direction from a difference between conveyance velocities of the endless belt detected by the plurality of belt velocity detectors.

Abstract: In a belt moving device that is capable of reducing belt speed fluctuation and positional deviation from a target belt position in a sub-scanning direction and performing highly precise position control in a main scanning direction, and an image forming apparatus that uses this belt moving device to prevent color shift in both the main scanning direction and sub-scanning direction of a formed image such that a high-quality image can be formed, belt shift control means reduce shift position variation within a single round trip of an endless belt by feeding back a target value for canceling out the shift position variation within a single round trip of the endless belt and feeding forward a value obtained by multiplying an inverse transfer characteristic of moving means by a transfer characteristic of a target value of the moving means in relation to the control content of the moving means.

Abstract: An image forming apparatus of the present invention includes two developing units each including two developing rollers facing a particular photoconductive drum and rotatable about respective axis parallel to the axis of the drum. Each developing unit is supported by a respective image forming unit and angularly movable about an axis substantially parallel to the axis of the drum. When each developing unit is angularly moved by a preselected angle, a gap for development is established between one of the developing rollers and the associated drum.

Abstract: An image forming apparatus of the present invention includes two developing units each including two developing rollers facing a particular photoconductive drum and rotatable about respective axis parallel to the axis of the drum. Each developing unit is supported by a respective image forming unit and angularly movable about an axis substantially parallel to the axis of the drum. When each developing unit is angularly moved by a preselected angle, a gap for development is established between one of the developing rollers and the associated drum.

Abstract: An image formation apparatus has photo conductor drums, and upstream developing rollers and downstream developing rollers that are brought into contact with respective photo conductor drums based on a changeover. The developing rollers develop latent images into visual images. A time required to change over a developing unit from one developing unit to the other developing unit is set as follows. A changeover time T2 from the downstream developing rollers to the upstream developing rollers respectively is set shorter than a changeover time T1 from the upstream developing rollers to the downstream developing rollers.

Abstract: An image forming method causes each of a plurality of image stations to form a test patch image on a respective image carrier and senses the density of the test patch image for executing image quality compensation control. The test patch image is formed after image formation using an upstream one of two developing portions in a direction of rotation of the image carrier or before image formation using a downstream one of the developing portions. This method promotes high-speed operation, miniaturization and low-cost configuration of an image forming apparatus.

Abstract: An image formation apparatus has photo conductor drums, and upstream developing rollers and downstream developing rollers that are brought into contact with respective photo conductor drums based on a changeover. The developing rollers develop latent images into visual images. A time required to change over a developing unit from one developing unit to the other developing unit is set as follows. A changeover time T2 from the downstream developing rollers to the upstream developing rollers respectively is set shorter than a changeover time T1 from the upstream developing rollers to the downstream developing rollers.

Abstract: An image forming method causes each of a plurality of image stations to form a test patch image on a respective image carrier and senses the density of the test patch image for executing image quality compensation control. The test patch image is formed after image formation using upstream one of two developing means in a direction of rotation of the image carrier or before image formation using downstream one of the developing means. This promotes high-speed operation, miniaturization and low-cost configuration of an image forming apparatus.

Abstract: An image forming apparatus is provided which can selectively drive a plurality of developing units by a simple structure accommodated in a small space. Two image stations are arranged along a direction of movement of an intermediate transfer belt. Each of the image stations is provided with a plurality of developing units arranged around a photosensitive drum. A developing unit driving system drives the plurality of developing units. A switching mechanism switches a transmission path of a power generated by the developing unit driving system so that the power is selectively transmitted to one of the developing units.

Abstract: An image forming apparatus for transferring a toner image from an image carrier to a sheet-like recording medium by way of an intermediate transfer body is disclosed. A position on the intermediate transfer body where image formation should start is determined in accordance with the frequency of use of each of a plurality of regions defined on the intermediate transfer body. Specifically, one of the regions minimizing the sum of the frequencies of use of the regions is selected as the above position. The intermediate transfer body can therefore be evenly used over its entire circumference. While the intermediate transfer body is in a stand-by state, it is intermittently driven so as to be free from deformation.

Abstract: A developing apparatus for supplying toner includes a toner hopper configured to hold unused toner, a developing tub, and a toner hopper mounting part provided between the developing tub and the toner hopper. The toner hopper is adapted to be mounted to and removed from the toner hopper mounting part. The toner hopper mounting part includes a vibration apparatus for vibrating the toner hopper mounting part to loosen the unused toner stored in the toner hopper.

Abstract: An image forming apparatus includes a common mount member formed with a shaft support portion for supporting a shaft supporting an image carrier and a writing device support portion for supporting the writing device. The common mount portion is affixed to a stationary member. The image carrier and writing device are held in a preselected positional relation via the common mount member. Also, a positional relation between the image carrier and a developing device is set via the common mount member. The image carrier and members surrounding it can be accurately assembled and adjusted in position with ease.

Abstract: A separation type optical pickup device divided to a fixed optical unit and a movable optical unit. The device comprises an optical output system for emitting an optical beam arranged in the fixed unit. An optical detection system is arranged in the fixed unit. A focusing system is arranged in the movable unit for forming an optical spot on an information record medium. A deflection member is arranged in the fixed unit for deflecting and guiding the beam emitted from the optical output system to the movable unit. The member has a deflection surface which is universally rotatable about a deflection point thereof. An optical axis adjuster mechanism is arranged in the fixed unit for shifting and adjusting the optical output system in a direction perpendicular to an optical axis thereof.

Abstract: The separation type optical pick-up device includes a movable optical unit and a stationary optical unit having a detection portion for detecting a discrepancy between an optical axis of a light beam emitted from an emitting portion of the stationary optical unit and an optical axis of a light beam returned from the movable optical unit, and is adapted to correct the discrepancy while driving a carriage of the movable optical unit on the basis of the detected discrepancy.

Abstract: A separation type optical pickup device which comprises a fixed optical system and a movable optical system which is separated from the fixed system. The fixed optical system is unmovable with respect to an optical information recording medium. The fixed system includes an optical beam emission system and a deflection member which deflects a beam emitted from the emission system. The deflection member is disposed on an optical axis of the beam and rotatable about a rotary axis which is parallel to the optical axis of the beam. The movable optical system is movable with respect to the information recording medium and guides the beam transmitted from the fixed optical system to the recording medium.