US 6,283,583 B1Granted

Image forming apparatus having float electrode provided to make uniform electric field

AssigneeSharp Kabushiki Kaisha

InventorsDaisaku Imaizumi, Yukihito Nishio, Hirokazu Fujita, Shirou Wakahara

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Abstract

An image forming apparatus capable of forming an image with uniform density includes a toner carrier for carrying a toner, an opposing electrode arranged opposing to the toner carrier, a high voltage power supply unit for supplying a voltage to generate a potential difference between the toner carrier and the opposing electrode, a control electrode including a plurality of electrodes arranged between the toner carrier and the opposing electrode, and a control power supply unit for implementing a plurality of potential states at respective ones of the electrodes of the control electrode, controlling passage of the toner through a passage portion, and for forming an image on a surface of a recording medium conveyed over the opposing electrode. The control electrode includes an insulating substrate, the aforementioned plurality of electrodes having a passage portion through which the toner passes provided in the insulating substrate, and a plurality of float electrodes having an opening provided such that at least part of the plurality of electrodes are directly or electrically exposed to the toner carrier, for making uniform an electric field formed between the toner carrier and the opposing electrode.

Claims18

Dependent claims

An image forming apparatus, comprising:

carrier means for carrying a developer;
an opposing electrode arranged opposing to said carrier means;
power supply means for supplying a voltage to generate a potential difference between said carrier means and said opposing electrode;
a control electrode arranged between said carrier means and said opposing electrode;
wherein said control electrode includes:
an insulating substrate having a plurality of passage portions through which the developer passes,
a plurality of developer control electrodes provided on said insulating substrate, each having a passage therethrough common to one of said plurality of passage portions in said insulating substrate, and
a plurality of float electrodes arranged between said carrier means and said opposing electrode, each floating electrode having an opening provided such that at least part of each of said plurality of developer control electrodes is exposed to said carrier means;
and
control means for implementing a plurality of potential states at respective ones of said plurality of developer control electrodes, thereby controlling passage of said developer through the passage portions of said substrate, so as to form an image on a surface of a recording medium conveyed between said control electrode and said opposing electrode.

7 more elements

Dependencies are inferred from the claim text.