Minolta Company, Ltd.

Seiichi Munemori

Takanobu Yamada

Yuusuke Morikami

Hirokazu Matsuo

Takeshi Minami

Toru Kasamatsu

Kazunobu Maekawa

Kuniaki Ishiguro

Tetsuya Onuki

Yasunori Nakayama

Takeshi Satake

Masato Yasui

Satoru Kawata

A tandem-type color image forming apparatus forms an image in a monochrome mode or in a full color mode. The apparatus has a controller which delays an image forming operation for a predetermined period of time when a color mode is switched from the monochrome mode to the full color mode during different images are continuously formed.

Mode switching in a color printer

A color image forming apparatus of the present invention comprises: an intermediate transfer member being driven to rotate by a driving roller; a plural image forming units for forming superposed toner images on the intermediate transfer member, the plural image forming units being located below the intermediate transfer belt; a transfer member for transferring the superposed toner images formed on the intermediate transfer member onto a sheet of paper in a transfer area; and a pair of rotatable conveyance rollers for conveying the paper to the transfer area in synchronization with the superposed toner images on the intermediate transfer member, wherein a first distance from a image forming position, for the image forming unit located most-downstream in the plural image forming units relative to the movement of the intermediate transfer member, to the transfer area is longer than a second distance from a nipping area formed by the pair of conveyance rollers to the transfer area.

Color image forming apparatus

When it is judged that a sheet S is not an ordinary paper but a thick paper or an OHP film sheet, or that the arrival of the sheet S at a pair of timing rollers is delayed due to a slip for example beyond an allowable period of time, a controller judges that a condition for transferring or fixing an image on the sheet S is not met. As a result, a secondary transfer roller and a cleaner are retreated from an intermediate transfer belt , and in this state, the intermediate transfer belt carrying a toner image I thereon is made idle at least about one revolution without transferring the image I.

Image forming apparatus capable of judging whether it is appropriate to form an image on a sheet and controlling the image formation accordingly

A color image forming apparatus in accordance with the present invention including an intermediate transfer member having a movable surface. The apparatus also includes plural image forming units for forming toner images on the intermediate transfer member at each of image-forming positions, and a transfer roller for transferring the toner images formed on the intermediate transfer member onto a sheet, the transfer roller having a circumferential length equal to the distance between the adjacent image forming positions.

Tandem type color image forming apparatus having an intermediate transfer belt

An image forming apparatus comprising an intermediate transfer belt having a horizontal belt part , and a transfer section arranged opposite the horizontal belt part of the intermediate transfer belt for transferring to a sheet overlaid images formed on the intermediate transfer belt by a plurality of image forming sections Y, M, C, K for overlaying multiple images of respectively different color, wherein a belt unit comprises a frame , at least three rollers supported on frame , and the intermediate transfer belt supported on the exterior surface of these rollers, and wherein the belt unit can be installed and removed from the image forming apparatus body perpendicular to the shafts of the rollers , and parallel to the horizontal part

Image forming apparatus

A color image forming apparatus of the present invention has an intermediate transfer member having a movable surface, a plural image forming units for forming superposed toner images on the intermediate transfer member at a predetermined image forming pitch, and a transfer member for transferring the superposed toner images formed on the intermediate transfer member onto a sheet of paper, wherein the peripheral length of the intermediate transfer member is a non-integral multiple of the image forming pitch.

Color image forming apparatus with intermediate transfer member length a non-integral multiple of image pitch

The recording sheet supporting surface of the transport belt comes in contact with the photosensitive drums for cyan, magenta, yellow, and black in the color copy mode, and is separated from the photosensitive drums aside from the photosensitive drum used for forming a black image in the monochrome copy mode with the image forming units for cyan, magenta, and yellow not being activated. With this separating operation, the distance on the transportation path of the recording sheet measured from the synchronizing roller to the transfer position of the photosensitive drum used for forming a black image in the monochrome copy mode is longer than in the color copy mode. Thus, the start time of scanning the surface of the photosensitive drum used for forming the black image is delayed in the monochrome mode according to the difference in distances between the color and monochrome modes.

Tandem-type image forming apparatus operating in color mode and monochrome mode

An inverting document feeder feeds a document from the document tray to the position where the image reader reads the document, turns the document over, and then reads the second side. Document size determination sensors detects the document passing through, and determines the size of the document from detections signals of the width of the document and the time elapsed between the detection of the top end of the document and the detection of the bottom end of the document. When the top end of the document reaches the document reading position, image reading is started by a scanner, regardless of whether the document size has been determined or not. The image data thus obtained are written into and read out of a memory unit in a specified order. Even if the document reading has not been finished at the time of determining the document size, feeding of a copying sheet of a size corresponding to the document size is started, and the image data stored in the memory unit are read out to form an image on the copying sheet.

Copying machine provided with an image reading apparatus for scanning

An image forming apparatus operates in a color mode using a plurality of image holding components and in a monochrome mode using one of the plurality of image holding components to perform the image formation. The mode is switched between the color mode and the monochrome mode in accordance with information, such as the number of monochrome images having been successively formed, the number of monochrome images to be successively formed, a time period having been taken for the monochrome image formation, productivity or life priority specified the user, and a standby state of the image forming apparatus in the color mode or the monochrome mode, with a distance between the recording sheets to be transported being controlled according to predetermined conditions.

Image forming apparatus operating in color mode and monochrome mode

An image forming apparatus equipped with a monochrome mode and color mode, in which the transfer drum is made to rotate without any paper wrapped around it to clean the transfer drum each time a series of copy operations is completed. By controlling the cleaning period through increasing or decreasing the number of non-paper rotations in response to the last copy operation mode, the transfer drum may be adequately cleaned at all times, and the amount of wear on the transfer drum and cleaning device caused by the cleaning operation is reduced.

Growing community of inventors

Toyokawa, Japan

Seiichi Munemori