Sharp Kabushiki Kaisha Corporation

Hajime Yoshinaga

Shirou Wakahara

Kazuya Masuda

Yoshitaka Matsumoto

Kenji Tani

Yasuichi Onose

Teruki Sugiura

An image forming apparatus of the present invention includes ring electrodes for controlling flying of toner from a carrier to a sheet, and a control power source section for applying a potential that is in accordance with an image signal to each ring electrode. The control power source section carries out, in the case where the image signal is applied to each ring electrode so that the potential is applied at the same timing, a control of shifting the timing of applying ON potential so that the sum of transient current flowing through each ring electrode at a predetermined time is smaller than the sum of maximum value of the transient current flowing through each ring electrode. This ensures that the amount of transient current supplied at a predetermined time to each ring electrode by the control power source section is reduced.

Image forming apparatus

The array pitch `d` between the control electrode strips with respect to the conveyed direction of the recording medium is determined based on the order of applying operating voltage, the resolution `x` of the image with respect to the conveyed direction, and the number `m` of the control electrode strips. Illustratively, in order to obtain a particular resolution `x` with respect to the conveyed direction of the paper, by taking into consideration the reduction in dot interval or conveyed distance by the conveyance of the recording paper, the array pitch `d` between the control electrode strips with respect to the conveyed direction of the recording medium is set as the dot distance produced when the paper is not moved, plus the above reduction. This can be written as d=(n+1/m)/x where n is a natural number.

Apparatus for electrostatically forming a developer image on a conveyed

In a digital printer as an image forming device, a high voltage is applied to a counter electrode exclusively when the counter electrode is covered with a sheet of paper having a good insulating property, so that a strong electric field necessary for image formation is generated between the counter electrode and a toner carrier. When the counter electrode is not covered with a sheet of paper, a high voltage relay provided between the counter electrode and a high voltage power source is turned OFF so that the application of the high voltage to the counter electrode is suspended, so that the strong electric field is not generated. By doing so, it is possible to surely avoid discharge which tends to occur between the counter electrode and the toner carrier or between the counter electrode and the control electrode.

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Ikoma-gun, Japan

Hajime Yoshinaga