Sharp Kabushiki Kaisha Corporation

Hiromu Yoshimoto

Fumio Shimazu

Kiyoshi Toizumi

Hiroshi Tachiki

Atsuyuki Katoh

Kouichi Yamauchi

Takuya Abe

Yoshie Iwakura

Tomohiro Oikawa

Yoshinobu Tateishi

Shirou Wakahara

Eiichi Kido

Yuhi Akagawa

Hideo Yamasa

Mitsuyoshi Terada

Keizo Fukunaga

Takayuki Ohno

Koichi Inui

Yuuhi Yui

An image forming apparatus includes a transfer drum which attracts and holds a transfer paper electrostatically. A voltage is applied to a conductive layer provided on an inner side of the transfer drum, and a grounded conductive electrode member is pressed against a dielectric layer provided on an outer side of the transfer drum through the transfer paper. A toner image formed on a photosensitive drum is transferred onto the transfer paper when the transfer paper is wound around the transfer drum and brought into contact with the photosensitive drum. The image forming apparatus further includes a member which charges the transfer paper in a polarity reversed to a polarity of the transfer drum, so that the transfer drum can attract the transfer sheet electrostatically in a satisfactory manner. The image forming apparatus further includes a charge control mechanism for controlling the amount of charges on the photosensitive drum. In addition the photosensitive drum has a voltage applying mechanism for applying a voltage to the internal surface of the drum.

Image forming apparatus

An image forming apparatus includes a transfer drum which attracts and holds a transfer paper electrostatically. A voltage is applied to a conductive layer provided on an inner side of the transfer drum, and a grounded conductive electrode member is pressed against a dielectric layer provided on an outer side of the transfer drum through the transfer paper. A toner image formed on a photosensitive drum is transferred onto the transfer paper when the transfer paper is wound around the transfer drum and brought into contact with the photosensitive drum. The image forming apparatus further includes an upstream member or layer on the electrode member which charges the transfer paper in a polarity reversed to a polarity of the transfer drum, so that the transfer drum can attract the transfer sheet electrostatically in a satisfactory manner.

Image forming apparatus having transfer drum with transfer paper charging member

An image forming apparatus includes a transfer drum which attracts and holds a transfer paper electrostatically. A voltage is applied to a conductive layer provided on an inner side of the transfer drum, and a grounded conductive electrode member is pressed against a dielectric layer provided on an outer side of the transfer drum through the transfer paper. A toner image formed on a photosensitive drum is transferred onto the transfer paper when the transfer paper is wound around the transfer drum and brought into contact with the photosensitive drum. A nip time changing controller changes the amount of time that a transfer sheet is in the nip between the transfer drum and the grounded conductive electrode member.

Image forming apparatus with nip time changing device

An image forming apparatus includes a transfer drum which attracts and holds a transfer paper electrostatically. A voltage is applied to a conductive layer provided on an inner side of the transfer drum, and a grounded conductive electrode member is pressed against a dielectric layer provided on an outer side of the transfer drum through the transfer paper. A toner image formed on a photosensitive drum is transferred onto the transfer paper when the transfer paper is wound around the transfer drum and brought into contact with the photosensitive drum. The image forming apparatus further includes a member which charges the transfer paper in a polarity reversed to a polarity of the transfer drum, so that the transfer drum can attract the transfer sheet electrostatically in a satisfactory manner. The image forming apparatus further includes a mechanism for removing the charges on the surface of the transfer drum via a bias switching device and a cleaning device for cleaning the surface of the transfer drum so as to eliminate defects in a transferred image, thereby upgrading the quality of a resulting image. The cleaning device may be a blade having a particular engagement crossover between the blade and transfer drum.

Image forming apparatus having transfer roller with charge-removing and

An image forming apparatus includes a transfer drum which attracts and holds a transfer paper electrostatically. A voltage is applied to a conductive layer provided on an inner side of the transfer drum, and a grounded conductive electrode member is pressed against a dielectric layer provided on an outer side of the transfer drum through the transfer paper. A toner image formed on a photosensitive drum is transferred onto the transfer paper when the transfer paper is wound around the transfer drum and brought into contact with the photosensitive drum. The transfer drum includes the inner side conductive layer, a semi-conductive layer, and a dielectric layer provided on the surface of the drum. The dielectric layer can be made to adhere to the semi-conductive layer by thermally contracting this layer or the semi-conductive and dielectric layer can be made of a one-piece construction. In another embodiment, the dielectric's inner side can have projections and depressions in contact with the semi-conductive layer.

Image forming apparatus having transfer drum with specific construction

An image forming apparatus includes a transfer drum which attracts and holds a transfer paper electrostatically. A voltage is applied to a conductive layer provided on an inner side of the transfer drum, and a grounded conductive electrode member is pressed against a dielectric layer provided on an outer side of the transfer drum through the transfer paper. A toner image formed on a photosensitive drum is transferred onto the transfer paper when the transfer paper is wound around the transfer drum and brought into contact with the photosensitive drum. The image forming apparatus further includes a member which charges the transfer paper in a polarity reversed to a polarity of the transfer drum, so that the transfer drum can attract the transfer sheet electrostatically in a satisfactory manner. The image forming apparatus further includes a mechanism for removing the charges on the surface of the transfer drum and cleaning the surface of the transfer drum so as to eliminate defects in a transferred image, thereby upgrading the quality of a resulting image.

An image forming apparatus of the present invention includes a photoreceptor drum on which a toner image is formed, a transfer drum for transferring the toner image formed to transfer paper by bringing the transfer paper into contact with the photoreceptor drum, and a pair of register rollers for supplying the transfer paper to the transfer drum at a predetermined time and for curling the transfer paper in an arc. The register rollers include first and second rollers pressed against each other, the first roller being a predetermined hardness and the second roller being a hardness larger than the first roller. The transfer drum is disposed on the same side as the second roller with respect to an imaginary tangent line touching the surface of the second roller at one end of a contact section between the first and second rollers. The image forming apparatus also includes transporting means for supplying the transfer paper to the register rollers so that a front edge of the transfer paper comes into contact with the second roller, temporarily stops, and then continues to the transfer drum. The image forming apparatus also includes a means for changing the pressure that the register rollers are pressed together. Paper type, quality, thickness, and size are detected and the pressure is adjusted accordingly. The means for changing pressure includes a resilient member for the pressing the second roller against the first, and a changing member for changing the amount of deformation of the resilient member.

Image forming apparatus equipped with register rollers for curling

An image forming apparatus includes a transfer drum which attracts and holds a transfer paper electrostatically. A toner image formed on a photosensitive drum is transferred onto the transfer paper when the transfer paper is wound around the transfer drum and brought into contact with the photosensitive drum. A variable voltage is applied to a conductive layer provided on an inner side of the transfer drum so as to either transfer the image onto the transfer paper or attract the transfer paper to the transfer roller. The transfer voltage is lower than the attracting voltage. The voltage applied to the transfer drum for both transfer and attraction will be variable depending on a detected humidity or type of transfer paper. In addition, a manual adjusting device is capable of adjusting the transfer or attraction voltage. A grounded conductive electrode roller is pressed against a dielectric layer provided on an outer side of the transfer drum for providing potential difference between the conductive layer and the transfer paper.

Image forming apparatus having variable transfer and attraction voltage

An image forming apparatus of the present invention includes a photoreceptor drum on which a toner image is formed, a transfer drum for transferring the toner image to paper by bringing the paper into contact with the photoreceptor drum, the transfer drum having a dielectric layer, a semi-conductive layer and a conductive layer laminated in this order from the paper side, a power source which is connected to the conductive layer so as to apply a predetermined voltage to the conductive layer, and a conductive roller for pressing the paper against a surface of the dielectric layer so as to produce a potential difference between the conductive layer and the paper. The potential difference induces charges of the same polarity as the voltage applied to the conductive layer on the surface of the dielectric layer, and charges of the opposite polarity on a back surface of the paper pressed against the surface of the dielectric layer. Thus, the paper electrostatically adheres to the transfer drum in a satisfactory manner. Moreover, unlike charging by atmospheric discharge, since the surface potential of the transfer drum is stable, it is possible to prevent unsatisfactory transfers and improve the image quality.

Transfer device for an image forming apparatus

An image forming apparatus provides a photosensitive body, a main charger, an exposing unit, developing unit and a contact-transfer charger. The main charger charges the photosensitive body with a predetermined electric potential. The exposing unit applies a laser beam on the surface of the photosensitive body to form an electric latent image. The developing unit develops the electrostatic latent image to form a toner image. The contact-transfer charger transfers the toner image on an image transfer paper. The image forming apparatus further provides controller for power supplies. The controller controls the power supplies after an image forming operation in a manner to enhance the electric potential of the photosensitive body to a high level by the main charger, drop the surface potential of the photosensitive body to a low level by the contact-transfer charger and then to cut off a bias voltage of the developing unit.

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Yamabe-gun, Japan

Hiromu Yoshimoto