Developer and image forming method
The present invention provides a developer suitable for a hybrid developing device which may provide a high-quality clear image by suppressing the occurrence of a ghost phenomenon, the occurrence of a carrier-jumping phenomenon and the occurrence of a current leaking phenomenon, and an image forming method which uses such a developer. In a developer which is used for a hybrid developing device which includes a developer transporting body for charging the developer containing carrier and toner while holding magnetism and a developer carrying body for transferring the toner thereto from the transporting body and for forming a thin toner film on a surface thereof, and which is for applying a developing bias to the developer carrying body so as to form a latent image of a latent image carrying body, a specific resistance of the carrier is set to a value which falls within a range of 1×10 9 to 1×10 12 Ω·cm, the saturation magnetization of the carrier is set to a value which falls within a range of 36 to 60 emu/g, and a specific resistance of the toner is set to a value which falls within a range of 1×10 13 to 1×10 16 Ω·cm.
1 . A developer which is used in a hybrid developing device which includes a developer transporting body for charging the developer containing carrier and toner while holding magnetism, a developer carrying body for transferring the toner thereto from the transporting body and for forming a thin toner layer on a surface thereof, and which is for applying a developing bias to the developer carrying body so as to form a latent image of a latent image carrying body, wherein
a specific resistance of the carrier is set to a value which falls within a range of 1×10 9 to 1×10 12 Ω·cm, the saturation magnetization of the carrier is set to a value which falls within a range of 36 to 60 emu/g, and a specific resistance of the toner is set to a value which falls within a range of 1×10 13 to 1×10 16 Ω·cm.
2 . The developer according to claim 1 , wherein an average particle size of the carrier is set to a value which falls within a range of 20 to 45 μm.
3 . The developer according to claim 1 , wherein the toner contains a binder resin and carbon black and, at the same time, an addition quantity of the carbon black is set to a value which falls within a range of 0.01 to 30 parts by weight with respect to 100 parts by weight of the binder resin.
4 . The developer according to claim 1 , wherein silica fine particles are exteriorly added to the toner and, at the same time, a covering ratio of the silica fine particles is set to a value which falls within a range of 50 to 90% with respect to the toner.
5 . The developer according to claim 1 , wherein a content of the toner is set to a value which falls within a range of 0.1 to 20 weight % when a total quantity of the developer is set to 100 weight %.
6 . The developer according to claim 1 , wherein assuming an average degree of circularity of toner as α and the saturation magnetization of the toner as β (emu/g), a following relationship formula (1) is established between α and β.
30α−26.8≦|β|≦30α−22.2 (1)
7 . The developer according to claim 1 , wherein in the hybrid developing device, a thickness restricting blade for restricting a height of a magnetic brush is arranged around the developer transporting body.
8 . The developer according to claim 1 , wherein in the hybrid developing device, a closest distance between the developer transporting body and the developer carrying body is set to a value which falls within a range of 0.3 to 1.5 mm, and a closest distance between the developer carrying body and the latent image carrying body is set to a value which falls within a range of 150 to 400 μm.
9 . The developer according to claim 1 , wherein in the hybrid developing device, a reverse bias applying means for returning the toner which is transported to the developer carrying body to the developer transporting body is provided.
10 . An image forming method which is characterized by using the developer described in claim 1.