US 7,079,795 B2Granted

Image forming apparatus

AssigneeCanon Kabushiki Kaisha

InventorMasaru Hibino

Life of this patent

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Abstract

An image forming apparatus includes an image bearing member having a surface on which an electrostatic latent image is to be formed; a black developing device, containing a black developer including toner and carrier, for developing the electrostatic latent image; at least one color developing device containing a color developer having a color other than black; a supplying device, provided for each of the black developing device and the color developing device, for supplying a supply material containing toner and carrier; a discharging device for discharging the developer. A resistivity of the carrier contained in the black developer is higher than resistivity of the carrier contained in the color developer, and a weight percentage of the carrier contained in the supply material for the black developing device is higher than a weight percentage of the carrier contained in the supply material for the color developing device.

Claims3

Dependent claims

An image forming apparatus comprising:

a first developing device containing a black developer including black chromatic toner and a carrier and for developing an electrostatic image with the black chromatic toner, wherein a resistivity of the carrier in the black developer is not less than 1.0×109 Ωcm and not more than 1.0×1010 Ωcm;
a first developer supply device for supplying a black supply developer including black chromatic toner and a carrier into said first developing device, wherein a weight ratio of the carrier in the black supply developer is not less than 10 Wt % and not more than 40 Wt %;
a first developer discharging means for discharging the developer from said first developing device;
a second developing device containing a chromatic developer including chromatic toner and a carrier and for developing an electrostatic image with the chromatic toner,
wherein a resistivity of the carrier in the chromatic developer is not less than 1.0×107 Ωcm and less than 1.0×109 Ωcm;
a second developer supply device for supplying a chromatic supply developer including chromatic toner and a carrier into said second developing device, wherein a weight ratio of the carrier in the chromatic supply developer is lower than the weight ratio of the carrier in the black supply developer and is not less than 1 Wt % and not more than 15 Wt %;
and
second developer discharging means for discharging the developer from said second developing device.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/114,180Filed 26 Apr 2005
Priority: JP 2004-13031926 Apr 2004
Published: US 2005/0238391 A127 Oct 2005
Granted: 18 Jul 2006
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G03G 15/0121
Details of unit: for developing
G03G 9/108
Having magnetic components: ferrite carrier, e.g. magnetite
G03G 15/08
For developing: using a solid developer, e.g. powder developer
G03G 2215/0177
Plural rotations of recording member to produce multicoloured copy: rotating set of developing units

Family

US 2005/0238391 A1Pre-grant publication · published 27 Oct 2005
US 7,079,795 B2This patent

From the US filing history. Foreign family members aren’t listed.

Timeline

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