Ricoh Company, Ltd.

Hitachi Koki Co., Ltd.

Ricoh Printing Systems, Ltd.

Akio Tsujita

Shinya Kobayashi

Tadashi Kasai

Masato Iio

Masakazu Terao

Kentarou Matsumoto

Katsuhiro Shinohara

Takao Umeda

Yukio Otome

Tsuneaki Kawanishi

Tsuyoshi Asami

Takashi Rokutanda

Kaoru Kataoka

Tatsuya Kubo

Teruaki Mitsuya

Masayasu Anzai

Takashi Bisaiji

Hiroyuki Mabuchi

Hisao Okada

Yoshihiro Sonohara

Katsuhiko Suzuki

Shinichi Haruki

Yhuzi Furuya

Masato Lio

Kathuhiro Shinohara

A toner including a petroleum wax, wherein the petroleum wax comprises a paraffin wax having a polarity.

Toner, printed material, method of preparing printed material and image forming apparatus having varnish application means

An image forming method including forming a toner image on a transfer medium with a toner comprising a wax having a polar group, and applying a varnish to the toner image. The wax may be a plant wax having an ester group, a wax having a polar group derived from a fatty acid, an oxidized wax, or a mixture thereof. The varnish may include a surfactant, such as a polyoxyethylene glycol, and may be photocurable.

Image forming method, image forming apparatus, varnish applicator, and toner

After at least one toner image is transferred to a medium to which an image is transferred from at least one of a plurality of image forming stations used, at least one toner image is transferred from at least one of the rest of the image forming stations, and this transfer operation is repeated a plurality of times to transfer toner images to the medium to which an image is transferred. In this manner, the toner images on the medium to which an image is transferred are formed using a desired number of color toner including a transparent toner. In addition, the order in which the transparent toner is transferred from the image forming station that is used for the transparent toner and toner other than the transparent toner is transferred from image forming stations in which the transparent toner is not used can be freely or automatically selected.

Image forming apparatus

An image glossiness controller has a main component color specifying unit that identifies a prescribed component color and output identification information thereof. A change in amplitude of a convexoconcavity of a toner layer of the prescribed component color is greatest among those of the other component colors when each of the component color toner is formed and fixed alone. Three or more halftone dot signal generators convert clear toner image information into three or more binary clear toner image signals corresponding to three or more component colors per component color pixel using multiple halftone dot characteristics, respectively. Each of the multiple halftone dot characteristics generating three or more binary clear toner image signals has a reversed phase from that generating three or more binary component color image signals.

Controller and halftone dot signal generating method capable of controlling glossiness of image

An image forming apparatus including a color toner image forming unit that forms a color toner image on a recording medium; a first colorless transparent toner image forming unit that forms a first colorless transparent toner image on the color toner image; a first fixing unit that fixes the image on the recording medium; a gloss level increasing device that increases a gloss level of the entire image on the recording medium that has been fixed; a second colorless transparent toner image forming unit that forms a second colorless transparent toner image on the image whose gloss level has been increased; and a second fixing unit that fixes the second colorless transparent toner image on the recording medium.

An electrophotographic image forming apparatus is disclosed. The electrophotographic image forming apparatus includes a photoconductor body, a donor roller which develops an electrostatic latent image on the surface of the photoconductor body by using charged toners, and a development nip section formed between the photoconductor body and the donor roller by having a predetermined gap between the photoconductor body and the donor roller. A developing traveling-wave electrode for generating a traveling-wave electric field is disposed at a position facing the surface of the donor roller at an upstream side of the moving direction of the photoconductor body relative to the development nip section, and a removing traveling-wave electrode for generating a traveling-wave electric field is disposed at a position facing the surface of the donor roller at a downstream side of the moving direction of the photoconductor body relative to the development nip section.

Electrophotographic image forming apparatus

An electrophotographic apparatus includes: a photoconductor; and two developing rollers facing the photoconductor. A developer fed out from between the two developing rollers is supplied to the photoconductor by the two developing rollers to form a toner image on the photoconductor. The developer includes a carrier having a volume-average particle size smaller than 70 &#x3bc;m and a volume resistivity not lower than 10&#x3a9;&#xb7;cm. A volume ratio of the carrier in a facing portion between the photoconductor and the developing rollers is not lower than 30% and not higher than 46%.

Developing device and electrophotographic apparatus using the same

A developing unit includes a plurality of developing rolls over which a developer is conveyed and supplied onto an image carrier which is rotatably supported; and at least one pair of the developing rolls being adjacent to each other. In the pair of the developing rolls, one developing roll rotates in a direction opposite to a rotary direction of the image carrier, and the other developing roll rotates in the same direction of the rotary direction of the image carrier. A regulation member is interposed between the pair of the developing rolls. The regulation member regulates a conveyed amount of the developer. The regulation member is disposed to be opposed to a magnet which is provided within the two adjacent developing rolls. A polarity of the magnet in the pair of developing rolls opposed to each other is different from each other.

Developing unit and image forming apparatus

In a charging device having saw-tooth electrodes for generating corona discharges, an amount of dust, toner, or paper dust attached to the tip end portions of saw-tooth electrodes is reduced. First to third pairs of saw-tooth electrode plates are disposed in a side-by-side fashion along the periphery of a photosensitive drum in which the first pair is disposed at an upstream side with respect to a direction in which the photosensitive drum rotates, the third pair at a downstream side, and the second pair at a central portion between the remaining two. A current flowing per a unit length of the second pair is set to 1.3 to 3 times as much as a current flowing per a unit length of each of the first and third pairs. The currents flowing per a unit length of the first and third pairs are set to be equal to each other.

Electrophotographic device with contaminant-resistant photoconductor and charger

An image forming apparatus has an image retaining body which is supported so as to be able to move endlessly, a transfer means which is installed at a specific distance away from the surface of the image retaining body or in contact with the surface of the image retaining body, and a paper guide which is installed upstream and downstream, of or at least upstream or downstream the transfer means along the moving direction of the image retaining body for guiding a sheet of paper between the image retaining body and the transfer means and for pressing the paper onto the surface of the image retaining body. The image forming apparatus is equipped with an adjusting means for adjusting the distance between the paper guide means and the transfer means along the moving direction of the image retaining body, thereby varying the length of the paper wound onto the image retaining body.

Image forming apparatus with adjusting device

A transport roll 1 consists of a metal roll 3 of 40 mm in diameter covered with a conductive PFA tube 2 of 10.sup.10 .OMEGA.cm in volume resistivity and 200 .mu.m in thickness. A DC voltage source 4 is connected to the metal roll. A sheet of paper 5 bearing toner images 6 and 7 on both sides thereof receives a drive force from a paper drive roll, and turns with the movement of the paper. The DC voltage source produces voltage VB1 of the same polarity as the charging polarity (positive) of the toner image 6 being in contact with the transport roll. The voltage VB1 is optimumly controlled so as to prevent the transport roll from being soiled with toner.

Electrostatographic printing machine

In an image forming apparatus forming an electrostatic latent image on a surface of a photosensitive body by exposing the charged photosensitive body, developing the latent image using a toner to form a toner image, transferring the toner image to a image holding body, and erasing the remaining charge on the surface of the photosensitive body after completion of the transferring, the photosensitive body is formed of a base material consisting of As.sub.2 Se.sub.3 or a-Si, and wherein the wavelength .lambda..sub.0 of the writing light used for the exposure is limited to a wavelength not larger than 780 nm, the wavelength .lambda..sub.1 of charge erasing light used for the charge erasing is limited to a wavelength smaller than 680 nm, and the time T.sub.1 from completion of the exposure to initiation of the development is limited within the range of 70 milliseconds to 300 milliseconds.

Image forming apparatus having a photosensitive body formed of a base

An electrophotographic recording apparatus using an amorphous silicon hydride photosensitive drum for recording images through processes comprising uniformly charging the drum, exposing the drum to light to form a latent image thereon, developing the latent image and transferring the developed image onto a recording medium wherein the charging and transferring processes are implemented by corona dischargers. To prevent pale or blurred image recording which occurs when the image recording is resumed after expiration of a long period of time, a shielding means is provided in association with each of the corona dischargers for shielding the corona discharger to interrupt atmospheric contact with the peripheral surface of the photosensitive drum.

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Kanagawa, Japan

Akio Tsujita