Patent ID: 7226713
Filing Date: 2007-06-05
Classification: G03G

Abstract:
1. A carrier comprising: a magnetic core material; and a layer located on a surface of the magnetic core material, wherein the carrier satisfies the following relationships (1) to (3): wherein σb represents a magnetization (emu/g) of the carrier at 1,000 Oe, ρc represents a true specific gravity of the carrier, and σa represents a magnetization of the carrier determined by the following method including: (1) magnetically holding the carrier on a cylindrical sleeve having a magnetic pole area located over a magnetic pole and having a peak magnetic flux density of 100 mT in a direction perpendicular to an axis of the cylindrical sleeve; (2) rotating the cylindrical sleeve around the axis thereof for about 30 min; (3) removing the carrier from the magnetic pole area by applying a force which is three times as much as a weight of the carrier in the direction perpendicular to the axis of the cylindrical sleeve; and (4) measuring a magnetization at 1,000 Oe to determine the magnetization σa, wherein the carrier has a weight-average particle diameter (D wherein a ratio (D wherein an electric resistance R is about is about 1.0×10 wherein d is 0.40±0.05 mm and E is a peak voltage.