Development apparatus
AssigneeRicoh Company, Ltd.
InventorsTeruyuki Ohnuma, Seiichi Miyakawa, Nobuo Mochizuki, Hajime Oyama, Yukio Tabata
Life of this patent
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Abstract
An apparatus for developing a latent electrostatic image formed on a photoconductive recording material in a dry type electrophotographic copying machine typically employing a one-component type developer comprises a conductive electrode held in contact with the developer. The electrode is connected to a power source through a switching device and serves to charge the developer to a predetermined polarity with a predetermined potential before the latent image is developed. In this way, the latent image can be developed selectively as either a normal image or a reverse image quite easily.
Claims25
A development apparatus for developing a latent electrostatic image formed on a photoconductor, comprising:
- container means for holding a one-component type developer and having an outlet for discharging said developer therefrom, said developer having a volume resistivity of no less than about 10.sup.9 ohm-cm;
- developer supplying means, having an endless conductive surface of a material having a volume resistivity no greater than about 10.sup.8 ohm-cm, for supplying said developer discharged from said container means to said photoconductor;
- means including a conductive element located at said outlet and held in contact with said developer for forming a toner layer with a predetermined thickness on said endless conductive surface when said developer is supplied from said container means to said photoconductor by said developer supplying means;
- and
- power source means connected to said conductive element for providing a voltage of a predetermined polarity thereto for charging said developer to a predetermined polarity.
An apparatus for developing a latent electrostatic image formed on a charged photoconductor by exposure of an original, comprising a supply of developer having a volume resistivity of at least about 10.sup.9 ohm-cm;
- transport means for bringing said developer into contact with said latent image;
- and charging means including a conductive electrode connected to a source of potential for applying a voltage to said developer for causing it to be attracted to selected portions of said latent image, said charging means including selection means for changing the polarity of the potential connected to said electrode for selectively applying a voltage to said electrode suitable for developing a positive or negative image of the original, as desired.
A developement apparatus for developing a latent electrostatic image formed on a photoconductor, comprising:
- container means for holding a one-component type developer and having an outlet for discharging said developer therefrom, said developer having a volume resistivity of no less than about 10.sup.9 ohm-cm;
- developer supplying means, having an endless conductive surface of a material having a volume resistivity no greater than about 10.sup.8 ohm-cm, for supplying said developer discharged from said container means to said photoconductor;
- doctor means for forming a toner layer with a predetermined thickness on said endless conductive surface when said developer is supplied from said container means to said photoconductor by said developer supplying means;
- power source means for providing a voltage of a predetermined polarity;
- and
- conductive electrode means connected to said power source means for charging said developer to a predetermined polarity;
- said conductive electrode means being disposed within said container means so as to contact said developer therewithin.
Dependencies are inferred from the claim text.