Minolta Camera Kabushiki Kaisha

Minolta Camera Co., Ltd.

Kenji Tabuchi

Tateki Oka

Kenichi Wada

Susumu Tanaka

Hiroshi Okamoto

Naoki Toyoshi

Kaoru Takebe

Tomoaki Yokoyama

Hideyuki Kanbayashi

Hiroaki Mizunoe

Takanobu Yamada

Mineyuki Sako

Taisuke Nagao

Shoichi Tsuge

Tomohisa Kanada

Yoshihiro Isono

Hidehito Iwata

A multi-color image forming apparatus which comprises a rotatably supported photoreceptor drum movable sequentially past a first charging station at which the photoreceptor drum is electrostatically charged; a first exposure station at which a first electrostatic latent image is formed on the photoreceptor drum; a first developing station at which a first developing unit is disposed for developing the first electrostatic latent image into a toner image with a first toner material; a second charging station at which the photoreceptor drum is again electrostatically charged; a second exposure station at which a second electrostatic latent image is formed on the photoreceptor drum; a second developing station at which a second developing unit is disposed for developing the second electrostatic latent image into a toner image with a second toner material; a transfer station at which the toner image is transferred onto a recording medium; and a cleaning station. To avoid a color mixing as a result of an mixture of the first toner material into the second developing unit, the first toner material mixing into the second developing unit is separated and recovered from the second developing unit. A manually operated switch and a control system are provided for manually controlling the separation and recovery of the first toner material from the second toner material.

Image forming apparatus having a removal means for separating developers

An image forming apparatus which develops two latent images formed on a photoreceptor with developing agents respectively containing first and second toners of different colors, and is so constructed that, a clear image is obtained by processing mixed-color separation to restrain the mixed-color as much as possible, in response to respective consumptions of a first toner and a second toner, or every time a fixed amount of first toner is consumed, and further, in response to the amount of first toner mixed into a second developing agent detected when a fixed amount of first toner is consumed.

Image forming apparatus

An electrophotographic copying process produces a photocopy having a negative image in order to highlight information in a specified area. An original image is radiated onto a photosensitive medium to form a first image. A solid block is formed in the specified area of the first image. The first image is then transferred to blank paper. The original image is then radiated onto the photosensitive medium again and a portion of the image is erased in order to form a second image. The second image is then transferred to the sheet of paper having the first image. The resulting image formed on the sheet of paper includes a highlighted second image formed in the specified area.

Image highlighting method

By utilizing an electrophotographic image forming process, a reversal image can be obtained in the following manner:

Reversal image forming method

An image editing method utilizing an electrophotographic process, which method includes a first charging step of charging a photosensitive medium; a step of projecting an image onto the charged photosensitive medium to form an electrostatic latent image; a first developing step of developing the electrostatic latent image into a first powder image by the use of a first toner material having the same polarity as the charged polarity; a first transferring step of transferring the powder image onto a copying paper; a second charging step of again charging the photosensitive medium to a polarity the same as that of the charge established during the first charging step; a step of radiating rays of light to the charged photosensitive medium to remove the electrostatic charge at a specificed area of the photosensitive medium; a second developing step of developing the specified area of the photosensitive medium by the use of a second toner material different in color from the first toner material to form a second powder image; and a second transferring step of transferring the second powder image onto said copying paper so as to cover the first powder image which has been transferred onto the copying paper.

Image editing method

An image forming apparatus including a rotatable electrostatic latent image support member, a corona charger, an exposure device, a first developing device confronting the support member and having an effective developing width for developing an electrostatic latent image formed on the support member, a second developing device confronting the support member upstream of the first developing device in a rotational direction of the support member and having an effective developing width for developing, on the support member, not only a first area not to be developed by the first developing device but a second area for forming the electrostatic latent image, a device for forming, in the first area, a reference latent image for detecting a density of the image, a detection device for detecting a density of a reference toner image obtained by developing the reference latent image by the second developing device and a control device for controlling, on the basis of a detection signal from the detection device, the density of the image formed by the second developing device.

Image forming apparatus having a plurality of developers and a detection

A cleaning device comprising a cleaning web with a concave-convex pattern. The concave-convex pattern is constituted by a plurality of concave or convex portions arranged in cross stripe manner.

Cleaning device

An image forming apparatus for use in an electrophotographic copying process and an image forming method for the apparatus, which are arranged to reproduce an image portion of an original document by a black developing material on a white paper sheet when an area of the image portion of the original document is below a predetermined level, and also, reproducing a background portion of the image by a white developing material on a black paper sheet when the area of the image portion of the original document is above the predetermined level, and thus, the black developing material or white developing material is selectively used according to percentages of image areas on the original document.

Image forming apparatus and image forming method employed therefor

The disclosure relates to a method, using an electrophotographic system, including a first process of transferring the image of an original document to a copy sheet and a second process of transferring a half-tone solid on a specified region of the image on the copy sheet transferred at the first process. Accordingly, for example, when a copy sheet is white, a black toner is used in the first image forming process, and a white toner is used in the second image forming process, a white half-tone solid of the white toner is superimposed on the black toner image. As a result, the black toner image formed on the specified region looks soft half-tone.

Image forming method

An improved method of controlling toner concentration for electrophotographic copying apparatus employing a dual component developing material which is composed of toner particles and magnetic particles. The method is arranged to detect the amount of magnetic particles adhering onto a photosensitive member for controlling the toner replenishing amount according to the amount of the magnetic particles thus detected.

Method of controlling toner concentration for electrophotographic

A magnetic brush developing apparatus includes a material transport guide member extending from a developing material supply position to a developing region, in addition to a rotatable developing sleeve having an inwardly disposed rotatable manetic roller driven for rotation in the same direction as the sleeve. A clearance is maintained between the guide member and the outer peripheral surface of the developing sleeve to allow transport by the rotation of the magnetic roller of developing material, having magnetic carrier particles and electrically insulative toner particles, from the developing material supply position along the outer surface of the guide member to the developing region in a direction opposite to the direction of rotation of the magnetic roller and developing sleeve. Part of the used developing material is moved in a direction opposite to the direction of transportation of the supplied developing material through the clearance between the developing sleeve and the guide member by the rotation of the developing sleeve, so that undesirable exchanging between the fresh developing material and the used developing material is substantially prevented by the guide member.

Magnetic brush developing apparatus

A method for developing by a plurality of times, an electrostatic latent image carried on a surface of an electrostatic latent image support member through employment of developing sleeves having magnetic rollers to be driven for rotation provided therein, which includes the steps of effecting the developing for each of the plurality of times, with the magnetic roller being rotated under such a state that developing irregularities in a direction intersecting a relative moving direction of the electrostatic latent image support member with respect to the developing sleeve, are formed in a developed image when the developing for each of the plurality of times is effected independently, causing pitches of the developing irregularities to coincide with each other, and deviating phases of the respective developing irregularities so that the respective developing irregularities are offset to each other so as to obtain the developed image having a uniform and sufficient image density without developing irregularities.

Electrostatic image developing method correcting irregularities of

An electrophotographic copying apparatus which is capable of controlling copied image density under the state where the density variation of the line image and that of the solid image are generally kept constant, with a simultaneous increase of the amount of density variation for the line image.

Electrophotographic copying apparatus

The present invention is concerned with a developer removing device for a copying apparatus. An electrostatic latent image is developer by a magnetic brush developing using a developer mix of magnetic carriers of small diameter and insulative non-magnetic toner charged to polarity opposite to one another and in which some of the magnetic carriers are transferred onto the background portion of the latent image. The developer removing device has a structure for removing the magnetic carriers adhering to the background portion at least either by magnetic force or electrostatic force.

Developer removing device for copying apparatus

An improved magnetic brush developing method for use in electrography which employs a dual-component developing material including electrically insulative magnetizable particles and electrically insulative non-magnetizable particles. In the developing method, magnetic attractive force exerted on the magnetizable particles located at the developing position where a magnetic brush of the developing material formed on a developing material support member is in rubbing contact with electrostatic latent images on a recording medium, is made larger than the electric repelling force acting on the magnetizable particles for preventing the magnetizable particles from adhering to the recording medium.

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Sakai, Japan

Kenji Tabuchi