Oki Electric Industry Co., Ltd.

Oki Data Corporation

Toshiro Murano

Katsuyuki Ito

Masato Sakai

Toru Ishihara

Toshikazu Ito

Takehiko Okubo

An electrophotographic image forming apparatus has a photosensitive drum; a charging device for charging a surface of the photosensitive drum; an LED array for projecting a light beam on the surface of the photosensitive drum, thereby forming irradiated spots constituting an electrostatic latent image. The irradiated spots are formed on intersections of a grid which is composed of a plurality of first lines extending in a main-scanning direction and arranged at equal first intervals and a plurality of second lines extending in a sub-scanning direction and arranged at equal second intervals. The apparatus also has a developing device for attaching a toner particle extending to each of the irradiated spots, a transfer device for transferring the toner particle to a transfer material, and a fixing device for fixing the toner particle on the transfer material. A diameter of the toner particle is determined in such a way that a diameter of a fixed toner particle is equal to approximately a length of a diagonal line of the grid. Further, the diameter of the toner particle in the developing device is in a range of 0.7 times to 1.0 times as long as the first interval and/or the second interval.

Electrophotographic image forming apparatus

A sensor detects the leading edge of the print medium. A position counter counts a time length required for the print medium to advance from where the print medium is detected by the sensor to the photosensitive drum. The position counter also counts a time length for the print medium to advance past the photosensitive drum. The distance of the toner image from the leading edge of the print medium is determined on the basis of the image data of print data. A row counter counts the number of dots in a direction in which the print medium is transported and a column counter counts the number of dots in a direction perpendicular to the direction the print medium is transported. The distance between the first line of an image data and the line in which a first dot to be printed in the image data is determined on the basis of the contents of the column counter and the row counter. The controller switches the transferring device from the constant current control mode to the constant voltage control mode immediately before the first line is printed on the print medium, thereby allowing transferring of the toner image in accordance with the distance of the toner image from the leading edge of the print medium.

Electrophotographic printer having transferring device with control mode

An image forming apparatus having a unit for charging the surface of an image carrier uniformly with electricity, the charging unit being contacted by a conductive element which changes a polarity of toner adhering to the unit, a unit for forming an electrostatic latent image on the surface of the image carrier charged electrically, a unit for developing the electrostatic latent image formed on the surface of the image carrier to thereby form a toner image and a means for transferring and fixing the toner image to a transfer member. The developing unit includes a developing roller which is disposed so as to contact the image carrier. The developing roller is connected to a power source for charging the toner particles on the developing roller with electricity with the same polarity as the charging polarity of the the image carrier, and for applying an electric potential to the developing roller so that the toner particles remaining on the developing roller are stuck to an image portion of the image carrier and the toner particles remaining on a non-image portion of the image carrier are attracted by the developing roller. The developing roller rotates in the direction opposite to that of the image carrier and a peripheral velocity of the developing roller exceeds 1.2 times that of the image carrier. Since the collected toner particles are not necessary to be disposed of, the environment is not polluted and the efficiency of using the toner is improved.

Apparatus for and method of forming image

An image forming apparatus for collecting, through a developing device, and reusing remaining toner remained on a photosensitive drum, as an image carrier, for forming an electrostatic latent image, without being transferred to a transfer material, includes a toner uniforming member disposed between locations for a charging process and for an exposing process, for making the toner remained on the photosensitive drum during a transferring process adhere slightly and uniformly to the photosensitive drum. The toner uniforming member eliminates the remaining toner remained on the photosensitive drum temporarily, and is applied with a necessary voltage for making the remaining toner eliminated temporarily adhere to the surface of the photosensitive drum again.

Image forming apparatus for collecting toner with the developing roller

An image forming apparatus having a unit for charging the surface of an image carrier uniformly with electricity, a unit for forming an electrostatic latent image on the surface of the image carrier charged electrically, a unit for developing the electrostatic latent image formed on the surface of the image carrier to thereby form a toner image and a means for transferring and fixing the toner image to a transfer member. The developing unit includes a developing roller which is disposed so as to contact the image carrier. The developing roller is connected to a power source for charging the toner particles on the developing roller with electricity with the same polarity as the charging polarity of the the image carrier, and for applying an electric potential to the developing roller so that the toner particles remaining on the developing roller are stuck to an image portion of the image carrier and the toner particles remaining on a non-image portion of the image carrier are attracted by the developing roller. The developing roller rotates in the direction opposite to that of the image carrier and a peripheral velocity of the developing roller exceeds 1.2 times that of the image carrier. Since the collected toner particles are not necessary to be disposed of, the environment is not polluted and the efficiency of using the toner is improved.

A transfer assembly of an electrophotographic printer includes a photoconductor drum, a charger disposed against the photoconductor drum for charging a surface of the photoconductor drum, an exposure unit for exposing the charged photoconductor drum to form an electrostatic latent image thereon, a developer unit disposed against the photoconductor drum for providing adhesion of a toner to the electrostatic latent image to form a toner image, a transfer unit disposed against the photoconductor drum for transferring the toner image to a medium, and a fuser for fixing the transferred toner image on the medium. In such an assembly, a part of the transfer unit, which first touches the medium to which the toner image has been transferred, is provided with a conductive material adapted to provide a gradual discharge of electric charge on the medium.

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Tokyo, Japan

Toshiro Murano