Abstract: An image density control apparatus which includes a photoreceptor having a photosensitive surface to be uniformly charged to a reference potential and formed with a charge latent image by a reference light amount, a device for developing the charge latent image at a reference developing potential so as to obtain a test pattern, a device for detecting density of the test pattern so as to control image forming condition during an actual image formation according to the detected value. The image density control apparatus further includes a reference condition control device which sets the reference image forming condition for forming the test pattern in accordance with the image forming condition for forming a document which was previously set by detecting a representative density of the document.

Abstract: An image forming apparatus for forming images by an electrophotographic process. The image forming apparatus includes a humidity sensor for detecting the humidity in the area around the image forming members provided therein, a density sensor for detecting the density of images formed on a photoreceptor, and a humidity controller having a dehumidifying unit and a humidifying unit for adjusting the humidity in the area around image forming members. The humidity controller is operated according to humidity historical data generated based on the humidity data outputed from the humidity sensor, a detected photoreceptor potential, a detected amount of developer scattered from the developing unit or the detection result from the density sensor.

Abstract: An image forming apparatus provided with a mechanism for causing an intermediate transfer member to be in contact with a photoconductor while a toner image formed on the photoconductor after development is firstly transferred onto the intermediate transfer member and otherwise keeps the transfer member away from the photoconductor.The mechanism for causing contact or separation keeps the intermediate transfer member away from a cleaner by its function of contacting the intermediate transfer member with the photoconductor, and keeps the intermediate transfer member in contact with the cleaner by its function of keeping the intermediate transfer member away from the photoconductor.

Abstract: An image forming apparatus using the electrophotographic process in which a toner image on a photoconductive drum is transferred onto a secondary transferring belt and the transferred toner image is further transferred onto a copy paper provides a sensor for detecting an occurrence of a paper jam before the copy paper reaches the secondary transferring belt and resumes the copying operation from the action suspended by the paper jam as soon as it is recovered from the paper jam.

Abstract: Apparatus for measuring developer density comprising, a container containing a developer constituted by a toner and a carrier, a rotary member agitating the developer in the container with its rotation, a transparent detection window facing the container, and having an electrically conductive film on its surface facing the developer, a measuring section measuring developer density in container on the basis of reflected light from developer illuminated through the detection window, an electrode which is supported by the rotary member, and is rotated together with the rotary member such that a gap between the electrode and the detection window is maintained at a predetermined value, the electrode being made, at least at one portion facing the detection window, of electrically conductive material, at least one magnet which is supported by the electrode, retains the developer, so that the magnet makes the developer to be brought into contact with the detection window with rotation of the rotary member, and a bias

Abstract: A developing device for color copiers and the like. The developing device has a plurality of developing units, each of which has a developing roller for developing an electrostatic latent image formed on an image carrier; a developing unit switching device for moving the developing units linearly and for selecting one of the developing units to oppose the image carrier; a fixed driving source for generating a driving force to drive the developing rollers; wrapping connecting apparatus which has a wrapping member and movable rotating structure having at least one rotating member and movable together with the developing units, the wrapping connecting apparatus being for conveying the driving force to the movable rotating structure; and a plurality of clutches, each of which is provided for one developing unit and is switched to a first state wherein the clutch conveys the driving force from the movable rotating structure to the developing roller and to a second state wherein there is no conveyance.