Sharp Kabushiki Kaisha Corporation

Atsuyuki Katoh

Hiroshi Tachiki

Fumio Shimazu

Kiyoshi Toizumi

Kouichi Yamauchi

Hiromu Yoshimoto

Takuya Abe

Yoshie Iwakura

Tomohiro Oikawa

Hiroshi Ishii

Masaru Tsuji

Keizo Fukunaga

Takashi Mukai

Yoshinobu Tateishi

Hiroshi Onda

Yuhi Akagawa

Mitsuyoshi Terada

Yoshiya Kinoshita

Takayuki Ohno

Syohji Tomita

Kenji Sugimura

Toyokazu Mori

Yoshinobu Okumura

Yoshinori Ohtsuka

Hideki Umeda

A partition is provided to isolate a space from outside thereof, the space encompassing a space where an image holding member, a developing device, a charging device, a transfer device, and a fixing device. The isolated space is under reduced pressure. This allows the image forming apparatus to avoid negative effect caused by humidity change.

Image forming apparatus with partitioning member

An isolating wall is provided for isolating, from a space outside the isolation wall, a space including: a photosensitive drum; a developing unit; a charging device; a transfer device; and a fixing device. With this configuration, the space in which powder toner (toner which is not fixed on a recording material by the fixing device) is present is isolated from the space outside the isolation wall. Thus, in an image forming apparatus using powder developer, this configuration makes it possible to (i) prevent the floating toner from going out of the image forming apparatus, or (ii) prevent the floating toner from deteriorating a function of the image forming apparatus.

Image forming apparatus with isolating member for powder developer

Flanges are pressed into opposite ends of a photoreceptor drum. A noncontact charging roller is arranged so as to face, but have no direct contact with, the photoreceptor drum. On both end portions of the noncontact charging roller, spacers are provided for maintaing a gap between the photoreceptor drum and the noncontact charging roller. The spacers are of tape form and wound around the noncontact charging roller. Winding positions of the spacers are distant by more than an effective projection length of each of the flanges from respective opposite ends of the charging roller.

Image forming apparatus having non-contact charging roller

The present removing system has a feature to remove a left-over toner that is accumulated on a brush that touches a left-over toner on a photoreceptor. More specifically, the present removing system is so arranged that an alternating voltage (superimposing voltage) on which a positive direct current voltage is superimposed is applied onto a conductive brush in accordance with a user's instruction. With this arrangement, even if a positively electrified left-over toner is accumulated on the conductive brush, it is possible to remove the positively electrified left-over toner accumulated on the conductive brush, because a voltage value (positive) applied on the conductive brush in a moment is large. Moreover, because a voltage of the conductive brush becomes negative in a moment, it is possible to remove a negatively electrified left-over toner attached on the conductive brush.

Foreign material removing system, method of removing foreign material, printing apparatus and printing method

The invention provides a developing apparatus, an image forming apparatus and a toner replenishing method that can restrain deterioration of toner and can stably form high quality image. Replenishing bias voltage is applied to a developing roller and a replenishing roller to charge conductive toner kept on a surface of the replenishing roller to a predetermined amount of charge. By electric field generated between the developing roller and the replenishing roller on the basis of the applied replenishing bias voltage, charged conductive toner is made fly and replenished from the replenishing roller to the developing roller. An appropriate amount of conductive toner is kept in a toner transporting body formed on a surface of the developing roller and is supplied to a photoconductor roller.

Developing apparatus, image forming apparatus and toner replenishing method

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

By application of a voltage from a power source, a transfer roller carries out both transfers of (A) a first transfer for transferring a toner image on a photoreceptor to an intermediate transfer medium and (B) a second transfer for transferring overlapped color toner image on the intermediate transfer medium at once onto a recording sheet. A transfer voltage in accordance with, for example, a sheet thickness, as detected by sheet type detection of a sheet type detecting section is applied to the transfer roller in each stage. When the sheet type detecting section detects that the recording sheet is longer than a periphery of a fixing belt, a heater lamp is turned on in advance at any instant between a time when the recording sheet is brought into contact with the fixing roller and a time when the fixing roller completes one rotation, taking into consideration a time required for conduction of heat from the heater lamp to the fixing belt. As a result, it is possible to reduce ozone generated and make the device compact, and desirable transfer characteristics in accordance with a sheet type are obtained, thus realizing uniform fixing of an unfixed toner image onto the recording sheet, from the front end to the rear end.

Image forming apparatus having improved image transfer characteristics

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 which applies a voltage from a power source, to a transfer roller for performing a first transfer for transferring a toner image on a photoreceptor to an intermediate transfer medium, and a second transfer for transferring overlapped color toner image on the intermediate transfer medium to a recording sheet. A transfer voltage based on sheet thickness is detected by a sheet type detecting section and applied to the transfer roller in each transfer stage. When the sheet type detecting section detects that the recording sheet is longer than a periphery of a fixing belt, a heater lamp is turned on between a time when the recording sheet is brought into contact with the fixing roller, and a time when the fixing roller completes one rotation. As a result, it is possible to reduce ozone generated in the image forming apparatus and to make the apparatus compact. Further, with the image forming apparatus, desirable transfer characteristics in accordance with a sheet type are obtained, thus realizing uniform fixing of an unfixed toner image onto the recording sheet.

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.

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Tenri, Japan

Atsuyuki Katoh