US 6,661,987 B2Granted

Image forming apparatus for forming color images

AssigneesKabushiki Kaisha Toshiba, Toshiba Tec Kabushiki Kaisha

InventorMasashi Hiroki

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Abstract

In an image forming apparatus, developing rollers of plural color developing units having respective color developers are arranged at an equal space of a first distance along a circumference in contact with an image carrier separately from a black developing unit and on the other hand, the developing rollers from the last part in the revolving direction of a revolving body to the foremost part in the revolving direction are arranged at a space of a second distance that is longer than the first distance, a revolving-type developing device to supply a color developer to the image carrier by bringing anyone of plural color developing units to oppose to the image carrier, and for the developing roller at the last part in the revolving direction to the developing roller at the foremost part separated by the second distance, a black developer is supplied to the image carrier by the black developing unit.

Claims19

Dependent claims

An image forming apparatus comprising:

an image carrier;
a latent image forming unit to form latent images on the image carrier;
a black developing unit arranged near the image carrier to supply a black developer to the image carrier;
and
a revolver type developing unit arranged at a position near the image carrier and differing from the black developing unit, comprising developing rollers of plural color developing units which have different color developers arranged at an equal space of a first distance along the circumference of a revolving body in contact with the image carrier, wherein a developing unit at the last part in the revolving direction of the revolving body and a developing unit at the foremost part in the revolving direction are separated at a second distance longer than the first distance, and anyone of the plural color developing units is arranged opposing to the image carrier and supply a respective color developer;
wherein an area from the developing unit at the last part of the revolver type developing device to the foremost developing unit separated by the second distance opposing to the image carrier, a black developer is supplied to the image carrier by the black developing unit.

3 more elements

An image forming apparatus comprising:

an image carrier;
a latent image forming unit to form a latent image on the image carrier;
a black developing unit arranged near the image carrier to supply black developer to the image carrier;
and
a revolver type developing unit arranged at a position near the image carrier and differing from the black developing unit, comprising developing rollers of plural color developing units which have different color developers arranged at an equal space of a first distance along the circumference of a revolving body in contact with the image carrier of a revolving holder wherein a developing roller at the last part in the revolving direction of the revolving holder to a developing roller at the foremost part in the revolving direction are separated at a second distance longer than the first distance, and anyone of the developing rollers is arranged to oppose to the image carrier and supply color developer;
and
wherein an area from the developing roller at the last part of the revolving-type developing unit to the developing roller at the foremost part separated by the second distance opposing to the image carrier, a black developer is supplied to the image carrier by the black developing unit.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/055,015Filed 25 Jan 2002
Published: US 2003/0142996 A131 Jul 2003
Granted: 9 Dec 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G03G 15/0131
Details of unit: for transferring a pattern to a second base
G03G 2215/0106
Plural electrographic recording members: at least one recording member having plural associated developing units
G03G 2215/0109
Plural electrographic recording members: single transfer point used by plural recording members
G03G 2215/0177
Plural rotations of recording member to produce multicoloured copy: rotating set of developing units