Perfecting press apparatus
AssigneeHitachi Printing Solutions, Ltd.
InventorsTakashi Rokutanda, Yukio Otome, Hiroyuki Mabuchi
Life of this patent
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Abstract
A perfecting press apparatus for forming images on both sides of a transfer medium. With respect to a transferring current Ipt of an image forming unit, current Ipc is made large which flows from a charge control instrument for controlling charge polarity of the toner on the transfer medium in the direction of the transfer medium. In particular, in the image forming unit causing retransfer, a de-charging light source is installed between the a developing device and a transferring device for canceling charges other than at a latent image part of an image carrier, so that the relationship between Ipt and Ipc is to be 3×Ipc≦Ipc≦6×Ipt, whereby the retransfer is suppressed to minimum for producing satisfied quality of image.
Claims7
A perfecting press apparatus, comprising:
- at least a first image forming unit, a second image forming unit and a third image forming unit;
- and
- a charge controlling unit of corona discharging type;
- wherein
- each of the first, second and third image forming units includes:
- an image carrier;
- a charging unit for evenly charging the image carrier;
- an exposure unit for making image exposure on the charged image carrier on the basis of image information to thereby form an electrostatic latent image on the image carrier;
- a developing unit for supplying developer to the image carrier holding electrostatic latent image to thereby form a toner image on the image carrier;
- and a transfer unit of corona discharging type for transferring the toner image formed on the image carrier to a transfer medium;
- the image carriers of the first image forming unit, the second image forming unit and the third image forming unit are alternately arranged at both sides of the transfer medium;
- the charge controlling unit controls charging polarities of the toner images formed on both faces of the transfer medium by the first and second image forming units before the transfer medium is sent to the third image forming unit;
- an absolute value of current flowing from the charge controlling unit in the direction of the transfer unit is made larger than an absolute value of current flowing from the transfer unit of the third- image forming unit in the direction of the transferring medium.
Dependencies are inferred from the claim text.