Minolta Camera Kabushiki Kaisha

Minolta Company, Ltd.

Tateki Oka

Naoki Toyoshi

Tomoaki Yokoyama

Susumu Tanaka

Kenji Tabuchi

Kenichi Wada

Hiroshi Goto

Kunio Toda

Koji Uno

Hitoshi Saito

Yasuo Tanaka

Hiroshi Mizuno

Hirofumi Hasegawa

Mineyuki Sako

Shuichi Nakagawa

Kazuyoshi Hara

Hideyuki Kanbayashi

Hiroaki Mizunoe

Hiroshi Okamoto

Akihito Ikegawa

Hiroshi Murasaki

Narutaka Yoshida

Hirokatsu Shimada

Shizuo Yuge

Kouichi Etou

Shinichi Takemoto

Tamotsu Sakuraba

Tetsuo Kyogoku

Hisashi Myochin

Susumu Sakakibara

Toshikazu Suzuki

Yoshihiro Uchimoto

Norimasa Kubota

Katsunari Oda

Yoshihiro Isono

Akiyoshi Kamisaki

Teruo Narikawa

Toshitaro Kori

Yasuyuki Hiromoto

Kenji Miyashita

A developing apparatus according to the present invention comprises a developer carrying member for holding a developer and introducing the developer into a developing area opposite to the image carrying member at a required distance; a voltage applying device for applying an AC voltage to the developer carrying member; and a resistor inserted between the developer applying device and the developer carrying member, the AC voltage applied to the developer carrying member from the voltage applying device through the resistor being composed of a rectangular wave, and a time period during which a voltage, which is exerted in the direction in which the developer is fed to the image carrying member, in the AC voltage is less than 50% of a time period during which the AC voltage is exerted.

Developing apparatus including an AC voltage applying device

A toner discharging member is in contact with a developing sleeve at a position downstream to a developing region at which the developing sleeve (developer carrying member) confronts an electrostatic latent image carrier, extra toner returning to a toner supply region after the development is brought into contact with the discharging member and moves between the discharging member and the developing sleeve, a discharging bias voltage is applied to the toner discharging member, and the discharging bias voltage thus applied is controlled based on a toner charged state, an adhesion state of toner onto the electrostatic latent image carrier, a current flowing through a toner discharging member and others.

Developing device having a bias-controlled toner discharging member

An image forming apparatus comprising: a laser beam irradiating device for irradiating a laser beam onto a record support member; a storage device for storing image data composed of a plurality of dots; a detection device which reads out the image data from the storage device so as to detect whether or not dots to be subjected to light emission by the laser beam are arranged continuously; and a control device for controlling an irradiation period of the laser beam irradiating device to a smaller value when the detection device has detected that the dots to be subjected to light emission are arranged continuously.

Image forming apparatus

A fixing device of an image forming apparatus for fixing a toner image on a paper by a heating roller and a pressure roller, and having a detector for detecting the temperature of the heating roller. The fixing device controls to supply the electric current to the heating roller intermediately between on state and off state by repeatedly switching on and off the electric current when the difference between the detection temperature signal detected by the detector and a reference temperature signal is within a predetermined value. In detail, the fixing device overlays a periodically changing signal on at least one of the detection temperature signal and the reference temperature signal by a signal convertor so as to control the current supplied to the heating roller in accordance with the comparison result of the detection temperature signal and the reference temperature signal output from the signal convertor.

Fixing device having a temperature control system

An image fixing device for an image forming apparatus, comprises a hollow cylindrical fixing roller, and cylindrical pressure roller which is kept in contact with the fixing roller so as to rotate in accordance with rotation of the fixing roller. The pressure roller cooperates with the fixing roller to form therebetween a nip extending in a direction of the longitudinal axes thereof and serving to receive a sheet to which a toner image is transferred. The fixing roller is provided with a heater for locally heating the inner wall of the fixing roller at a location corresponding to the nip to fix the toner image to the sheet.

Image fixing device for image forming apparatus including means for

A contact type charging device having a contact member for making contact with the surface of a charge bearing member so as to apply an electric charge to the surface in an image forming apparatus of the electrophotographic type, and having a charging device which has a high resistance resistor connected serially to the contact member so as to apply a voltage to the contact member. The contact type charging device has a regulating member for regulating the upper limit of the absolute value of the voltage applied to the contact member to prevent excessive current flow to the contact member, or has a regulating member for regulating the lower limit of the absolute value of the voltage applied to the contact member to prevent a greater than necessary drop of the voltage applied to the charge bearing member.

Contact type charging device having voltage limiter

An electric charge supplying device for supplying electric charges to a body to be charged, comprises a charge-supplying member arranged in contact with the body to be charged, a power supply for supplying electricity to the charge-supplying member, and a shunt resistance connected in parallel with a series circuit including the charge supplying member and the body to be charged, the shunt resistance having environmental dependency of resistance substantially equal to that of the charge supplying member.

Electric charge supplying device and system employing the same

An image forming apparatus is provided with an optical system for forming a first electrostatic latent image and a second electrostatic latent image on a rotatable photosensitive member, a first developing device accommodating a first developer for developing the first electrostatic latent image, and a second developing device accommodating a second developer for developing the second electrostatic latent image. The second developing device is located downstream from the first developing device in a direction of rotation of the photosensitive member and is provided with a developing roller having a magnetic force. The second developer differs in color from the first developer and has a magnetism greater than the first developer. The second developer is transported to the second electrostatic latent image along a periphery of the developing roller. The image forming apparatus is further provided with a collector provided in the second developing device and having a collecting member confronting the developing roller. The first developer mixed in the second developer is moved toward and collected by the collecting member under the influence of an electric field formed between the collecting member and developing roller. Alternatively, the photosensitive member can act as a collector for collecting first developer mixed in the second developer.

Image forming apparatus having a plurality of developing devices

An image forming apparatus accommodates a developing bias power unit for applying a bias voltage to a developing sleeve confronting a photosensitive member. The developing bias power unit includes a DC power source, an electricity storage element interposed between the DC power source and the developing sleeve, and a controller for on-off controlling the DC power source. When an output of the DC power source is activated, the electricity storage element is electrically charged by an output voltage of the DC power source, and a first voltage is applied to the developing sleeve. In contrast, when the output of the DC power source is deactivated, a second voltage of reverse polarity is applied to the developing sleeve by electric charge held in the electricity storage element.

Developing bias power unit for use in an image forming apparatus

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

A developing device for developing an electrostatic latent image formed on an electrostatic latent image support member comprises a developer supplying member for supplying a developer to the electrostatic latent image support member, a developer containing portion containing the developer to be supplied to the developer supplying member, a conveying member provided in the developer containing portion for conveying the developer above the bottom part of the developer containing portion to the developer supplying member with the developer in the bottom part of the developer containing portion being left, and an agitating member provided in the developer containing portion for agitating in the developer containing portion the developer remaining in the bottom part of the developer containing portion without being conveyed by the conveying member.

Device for conveying developer in a developing device

A developing device for supplying toner particles to an electrostatic latent image support member having an electrostatic latent image formed thereon to develop the electrostatic latent image comprises a toner conveying member for conveying and supplying the toner particles to the electrostatic latent image support member having the electrostatic latent image formed thereon, a power supply for applying a predetermined developing bias voltage to said toner conveying member, and charge movement preventing means connected between the toner conveying member and the power supply for preventing charges induced in the toner conveying member as the electrostatic latent image is developed from flowing toward the power supply.

Developing device with electrically floating developing roller

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.

An image forming apparatus includes an image support member; a first electrostatic latent image forming device for forming a first electrostatic latent image on the image support member; a first developing device for developing the first electrostatic latent image with first toner; a second electrostatic latent image forming device for forming a second electrostatic latent image on the image support member; and a second developing device for developing the second electrostatic latent image with second toner; the second toner having a color different from that of the first toner and having charging characteristics relative to carrier, identical with those of the first toner; the second toner having an average particle diameter larger than that of the first toner.

Image forming apparatus having developing devices which use different

A color image forming apparatus comprises developing units each of which contains a developer of each of three primary colors, and another developing unit containing a white developer. An image on the original is subjected to color separation to obtain image density data corresponding to each primary color, and when all the density data are lower than a predetermined value, the density data are multiplied by a predetermined ratio, and a predetermined density of a white image is set. Based on the multiplied data of each color a developed image corresponding to the image density data of each primary color is formed on a recording material, and a white image corresponding to the white color density data is on the same recording material, thereby reproducing clear pastel or halftone color images.

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Sakai, Japan

Tateki Oka