Sharp Kabushiki Kaisha Corporation

Tomohiro Oikawa

Yoshie Iwakura

Fumio Shimazu

Kiyoshi Toizumi

Hiroshi Tachiki

Atsuyuki Katoh

Kouichi Yamauchi

Hiromu Yoshimoto

Takuya Abe

Yukikazu Kamei

Hideki Ohnishi

Hiroshi Doshoda

Shirou Wakahara

Iwakazu Honda

Toshihiko Takaya

Hideki Onishi

Yoshinobu Tateishi

Yoichi Yamamoto

Kimihide Tsukamoto

Shiro Narikawa

Shunju Anzai

Takasumi Wada

Hirokazu Tanaka

Shiro Wakahara

Seiichi Yoshida

Hiroe Ando

The present invention relates to an image forming apparatus with a charging member which charges an image bearer with a photoconductive surface. Forming a layer containing ferroelectric as part on the charging member, and applying the electric field formed by dipoles of the ferroelectric, the photosensitive member surface is electrified, thereby downsizing a charger and reducing power consumption thereof are achieved for realizing low-cost and reducing the number of consumable parts sufficiently.

Image forming apparatus

In an image forming portion, a grounded, drum-shaped photosensitive member rotating in a predetermined direction is provided. Arranged around the photosensitive member are a charger, an exposure unit, a developing unit, a cleaning unit, an erasing unit and a transfer roller with a ferroelectric layer formed on the surface thereof. The ferroelectric laminated transfer roller includes a grounded, metal core of aluminum, a conductive rubber layer of an elastomer having a volume resistivity of 10 &OHgr;&bull;cm or below with a thickness of about 3 mm, molded in a roller shape formed on the metal core and a ferroelectric element having a film thickness of some &mgr;m to some tens of micrometers, coating the surface of the conductive rubber layer.

Image forming apparatus including transfer device outer displacive type ferroelectric layer

A transfer apparatus having a photoconductor drum for holding thereon an image formed by toner charged with a negative polarity and a transfer roller disposed opposite the photoconductor drum, in which paper is fed to an area where the photoconductor drum and the transfer roller face each other and the toner image on the photoconductor drum is transferred to the paper by using a unidirectional transfer electric field formed by the transfer roller. The transfer roller also serves as charge supply control device for supplying a charge to the toner held on the photoconductor drum to thereby substantially neutralize the charge of the toner while retaining the negative polarity of the toner.

Transfer 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 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.

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 is provided with: a photoconductor drum having a surface on which a toner image is formed, a transfer drum for transferring the toner image onto a copying material by allowing the copying material to contact the photoconductor drum, and a ground roller for electrostatically attracting the copying material onto the transfer drum prior to transferring the toner image onto the copying material. He transfer drum is constituted by a semi-conductive layer and a dielectric layer that are stacked on a conductive layer. [Supposing that] The nip width between the photoconductor drum and the transfer drum is L1, the rotation speed of the two drums is Vp, and the time constant, which is represented by a product of the resistance and the capacitance between the two drums, is .tau., the relationship represented by L1/Vp&lt;.tau. is satisfied. By defining the time constant of the transfer drum [as described above], it becomes possible to stabilize an electric field made by the transfer drum, and consequently to carry out a desired transferring operation.

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 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 device according to the present invention is provided with an image-carrying body, a transfer medium, which transfers the toner image formed on the image-carrying body to a transfer material, and an affixing body provided at the perimeter of the transfer medium, which electrically affixes and holds the transfer material to the transfer medium. The transfer medium is made up of at least a semiconducting layer and a conductive substrate supporting it. The semiconducting layer has a foam portion with foam particles which increase in diameter toward the conductive substrate. This foam portion is made of a dielectric sheet, which is manufactured by forming a foaming dielectric polymer into a sheet, and heating the two surfaces thereof at different temperatures. The foregoing structure can provide a desired elasticity with the portion with foam particles of large diameter, and a desired surface smoothness with the portion with foam particles of small diameter. Accordingly, the surface potential of the transfer drum can be maintained uniformly and stably, thus eliminating poor affixing of the transfer material to the transfer drum and poor transfer of the toner image to the transfer material.

Image-forming device and method of manufacturing dielectric sheet

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

A toner image fixing device realizes a stabilized fixing process by smoothly controlling a surface temperature of its heating roller, preventing peeling-off of a layer of the roller core. The toner image fixing device comprises a heating roller consisting of a core covered with a layer of, e.g., a silicon rubber, a heat lamp mounted in the heating roller and a pressure roller for pressing a sheet of paper against the heating roller. The toner image fixing device is provided with a temperature sensor for sensing a surface temperature of the heat roller and for operating the heater lamp at a preset ON-OFF ratio (e.g., 1:3) to elevate the heating roller surface temperature from a first preset value to a second preset value and thereafter to maintain it at the second preset temperature.

Toner-image fixing device with roller-temperature limitation

An image forming apparatus includes a photoreceptor allowing an electrostatic latent image to be formed by light exposure, a light source emitting light beams, a light deflecting device for deflecting light beams from the light source, an exposure controlling device for controlling deflecting actions of the deflecting device, and an image-forming optical device receiving light beams deflected by the light deflecting device and image-forming the light beams on the photoreceptor so as to create a latent image composed of a plurality of pixels thereon. In the configuration, the light deflecting device includes a micro-mirror array device which is composed of a multiple number of mirror facet elements arranged matrix-wise, in two-dimensions, and which is disposed so that each row of the mirror facet elements extends in parallel with the rotating axis of the photoreceptor and normals of the mirror facet elements are substantially perpendicular to the rotating axis of the photoreceptor. Each of the mirror facet elements in a single column can individually be controlled to be oriented at any angle to simultaneously deflect light to the same location on the photoreceptor to vary density of the image formed thereon.

Image forming apparatus with a light directing device for varying

An image forming apparatus is arranged so as to include an optical head unit constituted of exposing device and information reading device, one cylindrical white light source which is commonly used as a light source for the above both devices, liquid crystal shutter arrays for individually opening and closing optical paths of the light source in direction of a photoreceptor, and to control open/close operation of an exposure shutter array according to an image signal and to control the shutter arrays such that when the exposing device operates, the information reading shutter array closes and that when the information reading device operates, the exposure shutter array closes. As a result, in an arrangement which is carried out a simultaneous charge-expose-development process and has exposing function and information reading function, it is possible to sufficiently miniaturize an apparatus. Moreover, since the liquid crystal shutter array is used, open/close operation of the optical paths from the cylindrical white light source to the photoreceptor can be easily and securely control.

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Chiba, Japan

Tomohiro Oikawa