Abstract: An image forming apparatus of the present invention includes a latent image forming device for forming a latent image on an image carrier and a developing device for developing the latent image with toner to thereby form a corresponding toner image. The surface of an intermediate image transfer body is movable and includes an high-resistance layer having a volume resistivity of 1010 &OHgr;.cm or above. A primary image transferring device transfers the toner image from the image carrier to the intermediate image transfer body. Secondary image transferring device transfers the toner image from the intermediate image transfer body to a sheet. A polarization uniforming device uniforms, at the beginning of an image forming operation, polarization left in the high-resistance layer while preserving the polarity of the polarization after the surface of the intermediate image transfer body has started moving, but before the toner image is transferred from the image carrier to the secondary image transfer body.

Abstract: An image forming apparatus of the present invention includes an image carrier. A rotary developing device adjoins the image carrier and includes a plurality of developing sections for developing a latent image formed on the image carrier with a magnetic developer. A toner cartridge unit includes a plurality of toner cartridges and is rotatable integrally with the developing device. A plurality of toner conveying device each connect one toner cartridge to the associated developing section and each include a toner passage and a toner conveying member disposed in the toner passage. A magnet adjoins a toner outlet, which is formed in the toner passage and communicated to the developing section, for forming a magnetic field that traverses the toner passage over the entire diameter of the toner passage. Toner stored in each toner cartridge is prevented from unexpectedly flowing into the associated developing section when replenishment is not effected.

Abstract: In an electrostatic image forming apparatus, including a corona discharger located so as to face an image carrier on which a toner image is to be formed. When a paper or similar recording medium is brought between the image carrier and the discharger, the discharger effects corona discharge at the rear of the recording medium so as to charge the medium to a polarity opposite to the polarity of the toner image. The toner image is then transferred from the image carrier to the recording medium. A polarity switcher allows a voltage of substantially the same polarity as the toner to be applied to a discharge wire included in the discharger, and environmental sensing device allows this voltage to be changed based on temperature and humidity conditions. The apparatus is free from defective discharge and defective image transfer ascribable to the deposition of free or isolated toner on the discharger.

Abstract: In an electrostatic image forming apparatus, including a corona discharger located so as to face an image carrier on which a toner image is to be formed. When a paper or similar recording medium is brought between the image carrier and the discharger, the discharger effects corona discharge at the rear of the recording medium so as to charge the medium to a polarity opposite to the polarity of the toner image. The toner image is transferred from the image carrier to the recording medium. A polarity switcher allows a voltage of substantially the same polarity as the toner to be applied to a discharge wire included in the discharger. The apparatus is free from defective discharge and defective image transfer ascribable to the deposition of free or isolated toner on the discharger.

Abstract: An apparatus having a photosensitive body and intermediate transfer body for successively transferring color toner images formed on the photosensitive body onto the intermediate transfer body to form an overlay transfer image which is transferred in batch onto transfer paper. Passage of a mark in a portion of the intermediate transfer body is detected by a mark detector in a passage area for the mark. A primary transfer device is provided in a primary transfer section of the appartus so as to contact the photosensitive body. An electrifying device is provided at a position of upstream in a rotating direction of the photosensitive body from the primary transfer device.

Abstract: In an image forming apparatus, toner images of respective colors are sequentially formed on an image carrier. A primary image transfer unit sequentially transfers the toner images from the image carrier to an intermediate image transfer belt one above the other, thereby producing a composite color image on the belt. A secondary image transfer unit transfers the composite color image from the belt to a sheet or similar transfer material. When the belt makes a turn without image transfer, i.e., idles, an electric field output lower than an electric field output preselected for image formation is applied to the primary image transfer unit.

Abstract: An image density control method and a color image forming apparatus for controlling the density of a multi-color image to be reproduced, having functions of forming for each color a first reference latent image, to be developed in a medium density, on a latent image carrying member, forming for each color a second reference latent image, to be developed in a low density, on the latent image carrying member, depositing toner of a color corresponding to each of the first and second reference latent images on respective of the first and second reference latent images, sensing the quantities of different by colored toners deposited on respective of the first and a second reference latent images for each color and controlling, at least one image forming condition in the formation of images of each color to correct the density of the medium toner density portion of the image for toner color on the basis of the sensed results.

Abstract: In a multicolor image-forming apparatus having a photoelectric sensor for detecting the amount of toner of an unfixed toner image adhering onto a photosensitive element, and a toner density sensor for detecting the density of a developer in a developing machine to form a multicolor image by overlapping the toner images having a plurality of colors, a color-balance control method comprises the steps of correcting a setting value of an output of the toner density sensor of the developing machine in accordance with the change in amount of toner adhering onto a photosensitive element detected by the photoelectric sensor with respect to a high density section; setting an allowable range of the toner density in advance in the developing machine with respect to the toner having at least one color; setting the amount of toner adhering onto a photosensitive element of the at least one color as a reference when the toner density is changed outside the allowable range; and correcting the amount of toner adhering onto a