Ricoh Company, Ltd.

Noritake Co., Ltd.

Seiichi Miyakawa

Susumu Tatsumi

Shigeru Suzuki

Koji Sakamoto

Hajime Oyama

Toyoo Okamoto

Kenichi Shimizu

Teruyuki Ohnuma

Akira Midorikawa

Kazuaki Iizuka

Kiyoshi Ohshima

Eishu Ohdake

Yoshiyumi Tamiya

Tadahiro Suzuki

Takashi Yano

Yutaka Koizumi

Makoto Obu

Yusuke Takeda

Manabu Mochizuki

Tamaki Kaneko

Yasuhiro Tabata

Toyokazu Satomi

Isao Nakamura

Tadahiro Eda

Takeo Tsukamoto

Takashi Seto

Tsuneo Kurotori

Kenji Kojima

Tatsuo Tani

Kazuyoshi Matsumoto

Toshio Watanabe

Mie Yoshino

Kenzo Ariyama

Sadayuki Iwai

Kunio Hibi

Itsuo Ikeda

Yukio Tabata

Toshio Inada

Harumitsu Mashiko

Nobuo Mochizuki

Masami Hiramatsu

Taro Kimura

Yoshihiro Ogata

Satoshi Shinguryo

Junichiro Hashimoto

Sakae Ota

Yuichi Kobayashi

Haruhiko Fukuda

Mitsuhiro Nonaka

Kozoh Sudoh

Yoshiumi Tamiya

Youichi Ueda

Hidenori Kanno

Youtarou Kakitani

Kaoru Shimizu

Yasuyuki Kani

An apparatus which forms a discharge electric field in order to discharge an object. The apparatus includes an electrode member facing and separated by a preselected gap from the object, and a power source which applies a discharge voltage to the electrode member to thereby cause discharge to occur between the object and the electrode member. Further, the electrode member at the gap includes a material selected in association with the gap so that a functional relationship between the discharge voltage and a discharge current caused by the discharge voltage is a continuous function.

Image forming device which forms an electric field to discharge an object

A wet-type image forming apparatus produces a high-quality toner image by condensing a toner image on a photosensitive drum and adhering the toner image onto the photosensitive drum without contacting a liquid carrier applied on the photosensitive drum. The photosensitive drum carries a latent image formed thereon. The toner image is formed by developing the latent image by using a developing liquid including the liquid carrier and toner dispersed in the liquid carrier. An excessive amount of liquid carrier on the photosensitive drum is removed after the toner image is formed. An electric field is formed which causes a current to flow between an electrically conductive member and the photosensitive drum. An air gap is formed between the liquid carrier on the photosensitive drum and the electrically conductive member so that the current flows through the gap, the liquid carrier and the toner image. The toner image on the photosensitive drum is transferred to a transfer material after the toner image passes an area in which the electric field is generated.

Wet-type image forming apparatus for forming a condensed toner image

An image forming apparatus for electrostatically transferring a latent image formed on a photoconductive drum or similar image carrier to a recording medium held by a clamp drum or similar medium conveying member. The clamp drum has a cylinder or base made of aluminum, a conductive rubber layer covering the cylinder, and an overcoat layer covering the rubber layer and higher in electric resistance than the rubber layer. A bias voltage for latent image transfer is applied while the rubber layer is connected to ground. The photoconductive drum and clamp drum are pressed against each other by a predetermined force, the former following the rotation of the latter. The photoconductive drum is provided with a photoconductor having a great electrostatic capacity, thereby preventing the effective transfer voltage at the time of image transfer from increasing.

Image forming apparatus having clamp for conveying a recording medium

The structure of a sheet-like electrostatic recording medium which may be configured as a roll and connected to ground via an electrostatic recorder with which it is usable. A connecting member is provided on at least one of axially opposite ends of the roll of the recording medium and electrically connected to an external electrode which is mounted on the recorder.

Structure of a recording medium for an electrostatic recorder

An image formation method for forming an image includes the steps of electrostatically transferring a latent electrostatic image formed on a latent-electrostatic-image bearing member to an intermediate transfer medium composed of at least a support, and an electroconductive layer and a dielectric layer which are successively overlaid on the support, developing the latent electrostatic image which has been electrostatically transferred onto the intermediate transfer medium into a visible image by a wet-type development method, and non-electrostatically transferring the visible image on the intermediate transfer medium to a final recording medium with the application of heat and pressure thereto. An image formation apparatus for carrying out the above method is disclosed.

Image formation method and apparatus with preheating and pressure image

A developing apparatus using a liquid developer and a developing head located to face a path along which a recording medium carrying, for example, an electrostatic latent image thereon is transported. A groove is formed in the surface of the head that faces the transport path. After development, the liquid remaining at the corner defined by the upper inner portion of the groove and the medium is rapidly collected to allow a minimum of smear to occur on the part of the medium which will be transported later. When the transport of the medium should be interrupted during development due to, for example, a jam, the liquid in the groove is collected to prevent a great amount of liquid which would smear a drive roller and other transport members from being transferred from the head to the medium.

Developing apparatus using a liquid developer and having a system for

Image forming equipment for performing a predetermined image forming operation by use of a stepwise drive source such as a stepping motor or pulse motor. Either one of a recording medium and a record head is driven by a pulse motor, and whether or not it has reached a predetermined position is determined. While such a decision as to the position of the recording medium or the record head is under way, the displacement per step is changed over to a displacement per step smaller than a displacement to be effected while the predetermined image forming operation is under way.

Image forming equipment with variable stepwise drive means operation

A solid state charger having covered electrodes with dielectric and uncovered discharge electrodes disposed parallel to each other. The covered electrodes and the discharge electrodes are both disposed on the same surface of an insulating substrate. An ac voltage is applied between the covered electrodes and the discharge electrodes, or between the covered electrodes, and a dc voltage is applied to the discharge electrodes.

Solid state charger

A flat solid discharging device applicable to an electrophotographic copier, facsimile apparatus and other electrostatic recording apparatuses for charging or discharging a photoconductive element. The device includes a dielectric element, a first and a second electrode juxtaposed to each other through the dielectric element, and a power source for applying an ac voltage across the first and second electrode to produce ions in the vicinity of the two electrodes. The first electrode has a hairline configuration and extends along the length of the device. The second electrode is constituted by a plurality of comblike conductive strips each of which extends crosswise relative to the first electrode through the dielectric. By adequately selecting the pitch of the conductive strips and the distance between the second electrode and the photoconductive element, irregularity in charging which corresponds to the pitch of the conductive strips is made negligible. The second electrode is divided into a plurality of segments in order to selectively charge the photoconductive element over different charging areas as desired.

Flat solid discharging device

A developing device for developing an electrostatic latent image formed on an imaging surface includes a developing electrode disposed opposite to the imaging surface and a control circuit for controlling the potential of the developing electrode. In one form, when the control circuit causes the developing electrode to be electrically floating, the upper limit of the voltage excursion is set at different levels as desired. In another form, the control circuit includes a sensor for sensing the potential of the imaging surface thereby allowing to carry out so-called fixed bias or auto-bias developing modes. In a further form, the mode of developing operation is automatically set depending upon the position of a pressure plate which is to be placed on an original for keeping the original in position during copying process.

Developing device

A developing unit for use with an electrophotographic copying apparatus of the type comprising a developing electrode and at least one corona discharger includes a conductive member arranged within a shield casing of the discharger for obtaining a voltage to be applied to the developing electrode as a bias voltage thereto. In the case where an a.c. discharger for charge elimination is being used in addition to the primary discharger, conductive members are incorporated with respective dischargers and the outputs from the conductive members are superimposed on each other and applied to the developing electrode. In this instance, the output of the conductive member associated with the a.c. discharger is continuously applied to the developing electrode after the de-energization of the primary discharger, i.e., the completion of developing an electrostatic latent image to thereby prevent the deposition of toner on the developing electrode.

Developing unit for electrophotography

An apparatus for developing a latent electrostatic image formed on a photoconductive recording material in a dry type electrophotographic copying machine typically employing a one-component type developer comprises a conductive electrode held in contact with the developer. The electrode is connected to a power source through a switching device and serves to charge the developer to a predetermined polarity with a predetermined potential before the latent image is developed. In this way, the latent image can be developed selectively as either a normal image or a reverse image quite easily.

Development apparatus

A reverse development is performed with application of development bias voltage to a development sleeve at the time of development, and the polarity of the bias voltage is reversed or the bias voltage is reduced to zero at the time of non-development. Furthermore, positive images and negative images can be selectively formed by changing the voltage to be applied to a charge injection electrode, without changing the bias voltage to be applied to the development sleeve.

Reverse development method

First and second sensors (37), (39) are provided in a developing tank (36) containing a liquid developer consisting of a liquid carrier or dispersant and toner particles dispersed in the carrier. The first sensor (37) measures the electrical resistivity of the developer whereas the second sensor (39) measures the optical transmissibility thereof. Additional toner is supplied into the developer to maintain the transmissivity at a value which is a predetermined function of the resistivity. The transmissibility value is reduced as the resistivity increases, thereby maintaining the copy image density constant. The first sensor (37) includes two electrodes immersed in the developer and an A.C. or D.C. voltage is applied thereacross. The current flow through the electrodes (37) and thereby the developer is measured to determine the resistivity of the developer. Where the applied voltage is D.C., an arrangement is provided to mechanically scrape accumulated developer off the electrodes (37) at intermittent intervals.

Electrostatic copying apparatus

An exposure unit radiates a light image of an original document onto a charged photoconductive member to form an electrostatic image through localized photoconduction. A developing unit applies a powdered developing substance comprising carrier particles and toner particles to the photoconductive member to develop the electrostatic image and produce a toner image which is transferred and fixed to a copy sheet to produce a permanent reproduction of the original document. Prior to exposure with the light image a reference electrostatic image is formed on the photoconductive member and the electrostatic potential thereof is measured. The intensity of the light image of the original document and/or a developing bias voltage are regulated in accordance with the sensed electrostatic potential. The reference image may be of a reference surface having a predetermined optical density or a portion of the original document produced by reverse optical scanning.

Exposure control and other component control for electrostatic copying

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Nagareyama, Japan

Seiichi Miyakawa