Abstract: An image forming apparatus including a supporting member rotating around a rotation shaft thereof. A plurality of developing devices are arranged on the supporting member, each developing device including a developer supplying device. A plurality of cylindrically-shaped developer containers containing developer are provided, each developer container having an opening and a guide, and each developer container being detachably mounted on the developer supplying device. A container rotating device rotates the developer container, in which the guide is arranged that when one of the developing devices needs to be filled with the developer, the container rotating device rotates the developer container to transfer the developer in the developer container to the opening in accordance with a rotation movement of the developer container.

Abstract: A color image forming apparatus having a revolving type developing unit detachably installed therein. The revolving type developing unit includes a plurality of different color developing devices each having a developing roller therein. Each of the developing rollers is movably mounted on the developing device so that a gap between each of the developing rollers and a periphery of a photoconductive drum which is to be formed when the revolving type developing unit is set in the color image forming apparatus is enabled to be adjusted.

Abstract: An image forming apparatus includes an image bearing member, a developing device to develop a latent image on a surface of the image bearing member, a developer bearing member including a magnet therein, which bears developer on a surface thereof by a magnetic force of the magnet and carries the developer towards a developing position facing the image bearing member by being rotated, a limiting member that is placed facing the developer bearing member so as to limit a thickness of a layer of the developer borne on the developer bearing member, and a developing device casing.

Abstract: A color image forming apparatus having a revolving type developing unit detachably installed therein. The revolving type developing unit includes a plurality of different color developing devices each having a developing roller therein. Each of the developing rollers is movably mounted on the developing device so that a gap between each of the developing rollers and a periphery of a photoconductive drum which is to be formed when the revolving type developing unit is set in the color image forming apparatus is enabled to be adjusted.

Abstract: A rotary developing device includes a developing unit having a plurality of developing chambers arranged around an axis of rotation of the developing unit and each having a developer agitating mechanism thereinside wherein the rotary developing device is rotatable about the axis to locate any one of the plurality of developing chambers at a developing position where an image carrier is located. The device includes a drive inputting device located in proximity with the axis of the rotation for inputting a driving force to the agitating mechanism of one of the plurality of developing chambers which is located at the developing position. A drive transmitting mechanism is provided which transmits at a developing units side, a driving force to at least one of the plurality of developing chambers not located at the developing position.

Abstract: A rotary developing device includes a developing unit having plurality of developing chambers arranged around an axis rotation with each having a developer agitating device located therein wherein the rotary developing device is rotatable about the axis to locate any one of the plurality of developing chambers at a developing position where an image carrier is located, the developer agitating device of one of the plurality of developing chambers located at the developing position and the developer agitating device of at least one of the other developing chambers being drivable and wherein the developer agitating device of the at least one of the other developing chambers has a higher agitation speed than the developer agitating device of the one developing chamber located at the developing position.

Abstract: In an image forming apparatus, a rotary developing device has a developing unit in which a plurality of developing chambers are arranged around an axis of rotation. The developing unit is rotated about the axis to bring one of the chambers to a developing position where an image carrier is located. In each of the chambers, part of a developer removed by a doctor blade is received by a guide and then released from the guide into the chamber. This part of the developer is agitated in the vertical direction together with the developer existing in the chamber by the rotation of the device. As a result, the developer is agitated and charged in a desirable manner.

Abstract: An image forming device includes a plurality of developing devices and a photosensitive drum. Each of the developing devices includes a developer carrying roller. One of the developing devices is moved to a developing position confronting the photosensitive drum which is formed with a latent image. A first developing bias including a d.c. component and an a.c. component is applied to the developer carrying roller and developer on the developer carrying roller is rendered in contact with the latent image on the photosensitive drum so that the latent image is developed. On the other hand, when the developer on the developer carrying roller comes in contact with and separates from the photosensitive drum due to the movement of the developing device, a second developing bias is applied to the developer carrying roller.

Abstract: In an image forming apparatus, a rotary developing device has a developing unit in which a plurality of developing chambers are arranged around an axis of rotation. The developing unit is rotated about the axis to bring one of the chambers to a developing position where an image carrier is located. In each of the chambers, part of a developer removed by a doctor blade is received by a guide and then released from the guide into the chamber. This part of the developer is agitated in the vertical direction together with the developer existing in the chamber by the rotation of the device. As a result, the developer is agitated and charged in a desirable manner.

Abstract: A toner cartridge for a rotary developing device according to the current invention maximizes the storage capacity while it minimizes clogging or aggregation of stored toner. The toner cartridge is placed on an outer side surface of the rotary developing device and rotates around with the rotary developing device around the same axis of rotation. During the rotation, the stored toner is shaken and thrown against an internally projected dispersing portion in the cartridge for minimizing the aggregation of the toner. In addition, a vibration mechanism based upon the same rotational movement further minimizes the aggregation. The toner cartridges each containing a unique color such as cyan, magenta, yellow and black may be placed together to form a ring on the outer side surface. These toner cartridges are identical and maximize the storage capacity by substantially eliminating unused space between any adjacently placed cartridges.

Abstract: A developing device is provided which has a developing chamber, a toner container and a hopper portion all provided together on a revolving holding mechanism. A drive device is provided to revolve the driving mechanism and a stopping device is provided to stop this holding mechanism revolving movement at least to provide the developing chamber in a facing relationship to an image carrier. Moreover, the relative position of the toner chamber and the hopper portion are such that the hopper portion can be replenished with toner from the toner chamber at least once during a complete rotation of the revolving holding mechanism. Replenishment can occur independently of image formation, while the holding mechanism is revolving or during a pause in the revolving of the holding mechanism.

Abstract: In an image forming apparatus, a developing device has a toner container having a toner outlet, and a receptacle having a mount portion for removably mounting the container. The insertion space of the mount portion and the toner outlet are each tapered such that the width in the up-and-down direction sequentially decreases toward the deepest end. In a developing device of the type causing the container to be rotated to bring the toner outlet into alignment with a toner inlet formed in the receptacle, the edge portion of the toner outlet is tapered to reduce a load during rotation and to ensure close contact at the end of the mounting of the container.

Abstract: An image forming apparatus of the type having a rotary developing device or revolver, and a power supply device. When the revolver is rotated to bring one of its developing sections to a developing position, the end of a developing roller disposed in the developing section faces a bracket mounted on a rear wall included in the apparatus body. A retractable rod-like terminal is mounted on the bracket and constantly biased by a spring. A bias for development is applied from a bias circuit to the developing roller via the retractable terminal.

Abstract: A developing device is provided with a toner container rotatable to a toner replenishing position. The toner container has a toner outlet in a wall of the container. This outlet includes an edge portion that is downstream in the direction of the rotation of the container that is jutted towards the center of toner container rotation which is inside the toner container. This inwardly jutted edge portion of the toner outlet provides a toner outlet profile having an edge that is lower than the other edge of the toner outlet in the direction of toner container rotation so that the lower edge does not engage into contact with a toner inlet on a wall of a developing chamber of a developing device until after the toner outlet is in a position overlapping at least most of the toner inlet.

Abstract: An image forming device includes a plurality of developing devices and a photosensitive drum. Each of the developing devices includes a developer carrying roller. One of the developing devices is moved to a developing position confronting the photosensitive drum which is formed with a latent image. A first developing bias including a d.c. component and an a.c. component is applied to the developer carrying roller and developer on the developer carrying roller is rendered in contact with the latent image on the photosensitive drum so that the latent image is developed. On the other hand, when the developer on the developer carrying roller comes in contact with and separates from the photosensitive drum due to the movement of the developing device, a second developing bias is applied to the developer carrying roller.

Abstract: In an image forming apparatus, a rotary developing device has a developing unit in which a plurality of developing chambers are arranged around an axis of rotation. The developing unit is rotated about the axis to bring one of the chambers to a developing position where an image carrier is located. In each of the chambers, part of a developer removed by a doctor blade is received by a guide and then released from the guide into the chamber. This part of the developer is agitated in the vertical direction and conveyed together with the developer existing in the chamber by the rotation of the device. As a result, the developer is agitated, conveyed and charged in a desirable manner.

Abstract: An image forming apparatus of the type having a rotary developing device or revolver, and a power supply device. When the revolver is rotated to bring one of its developing sections to a developing position, the end of a developing roller disposed in the developing section faces a bracket mounted on a rear wall included in the apparatus body. A retractable rod-like terminal is mounted on the bracket and constantly biased by a spring. A bias for development is applied from a bias circuit to the developing roller via the retractable terminal.

Abstract: In an image forming apparatus, a rotary developing unit or revolver is loaded with a removable black developer container at the center thereof. The container is formed with a toner outlet. A receptacle assigned to black toner is provided at the end of the axis of the revolver and formed with a toner inlet. The receptacle constitutes a hopper portion. A supply roller is disposed in the receptacle. A screw conveyor extends out from a black developing chamber defined in the revolver into a communication chamber which communicates the receptacle to the developing chamber. A shutter is located at the loner inlet of the receptacle and rotatable due to its own weight while the revolver is in rotation. When more than a predetermined number of printings are produced by use of the black developing chamber, printing is interrupted. Then, the revolver is rotated to transfer the toner from the container to the hopper portion. The revolver may be rotated every time a single printing is produced.

Abstract: For image reproduction, a submodular unit including a developing roller and a doctor blade is adjustably mounted on a modular developing unit of a rotary developing apparatus. In general, the modular developing unit is rotatably positioned to juxtapose a photoreceptor drum. This juxtaposed position defines the developing position. The toner loaded on the developing roller in the developing position travels over a spacial gap between the developing roller surface and the photoreceptor drum surface. This crucial gap is necessary for successful image reproduction. However, this gap usually cannot be optimally maintained over extended time. The gap is also changed due vibration caused during shipment. In adjusting the gap, the submodular unit allows an independent and fine adjustment for each modular image developing unit. The submodular unit also allows an efficient assembly of the modular rotary developing unit.

Abstract: An image forming apparatus having a rotary developing device or revolver in which a plurality of developing sections are defined. The revolver is rotated over a target position by a first drive source, then returned by a second drive source producing a moment acting in the opposite direction, such as due to the drive of one of the developing sections, and then positively stopped by a positioning mechanism. The revolver is, therefore, accurately positioned at the target position without regard to, for example, irregularities in a motor for driving the revolver.