Riso Kagaku Corporation

Tetsunori Saito

Tomohiko Shimoda

Akihiro Tsumura

Masaaki Shinohara

Hiroshi Sugitani

Akira Nishiyama

Kazuyuki Aoki

Takuya Okamura

An inkjet printing apparatus includes: a print bar unit including an inkjet head configured to eject ink to a web being conveyed; and a guide configured to guide movement of the print bar unit in a print bar movement direction intersecting a conveyance direction of the web between a first position, a second position, and a third position. The first position is a position where the print bar unit performs printing on the web. The second position and third position are located on one and the other sides of the first position in the print bar movement direction.

Inkjet printing apparatus for web being print medium

A printing machine includes a printing unit which performs printing while transferring a sheet at a printing transfer speed, a circulation transfer unit which receives the sheet after simplex printing and transfers the sheet by reversing the sheet upside down, during duplex printing; and a paper refeed unit which refeeds, to the printing unit, the sheet transferred by the circulation transfer unit after simplex printing, wherein the circulation transfer unit includes a reversing unit which receives the sheet at the printing transfer speed, reverses the sheet upside down by switching back the sheet and accelerates the sheet up to a circulation transfer speed which is higher than the printing transfer speed when sheet transfer is restarted after temporal stop in the switching back, and a horizontal transfer unit which transfers the sheet switched back by the reversing unit, at the circulation transfer speed.

Printing machine

A controller in a one-side printing mode moves movable rollers to form a one-side printing route and moves a second head unit so that the second head unit faces a front side of a web. The controller then controls a first head unit and a second head unit to print images of respective pages on the front side of the web while transferring the web at a transfer speed twice as fast as that in a both-side printing mode.

Printing device

When a face of a paper sheet to be discharged on which an image is formed faces downward, a paper discharge device divides an image region of image data on the paper sheet to be discharged into areas along a discharge direction, detects an area in which maximum image density for each divided area is higher than or equal to a specified threshold, and controls a discharge angle so that the detected area does not come into contact with a stacked paper sheet until the paper sheet to be discharged has been discharged from a discharge roller.

Paper discharge device

A paper discharge device including discharge rollers that discharge a paper sheet and a paper discharge tray on which discharged paper sheets are stacked further includes a control unit that controls the discharge angle of a paper sheet according to at least the stacked amount of paper sheets that are stacked on the paper discharge tray so that the position at which the front end of a paper sheet to be discharged begins to come into contact with the stacked paper sheets on the paper discharge tray is within a specified range from the front end of the stacked paper sheets.

In an image forming apparatus, a paper discharge roller of a paper discharge unit has an upper roller as a driving roller and a lower roller as a driven roller. The lower roller has a nip roller which is fixed to a shaft and holds paper between the nip roller and the upper roller, and forming rollers having a diameter larger than that of the nip roller and arranged on both sides of the nip roller. Since a conveyance speed of the paper is constant, the number of revolutions of the forming roller having a large outer diameter is smaller than that of a nip roller having a small outer diameter. The friction between the forming roller and the paper is lower than that in conventional art. Attachment and accumulation of ink are suppressed, and inconvenience of contamination of the paper with ink upon paper discharge hardly occurs.

Growing community of inventors

Ibaraki, Japan

Tetsunori Saito