Importance

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Abstract

A carrier including 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): 0.90.ltoreq.(.sigma.a/.sigma.b)<1.00 (1); 200.ltoreq.(.sigma.b.rho.c).ltoreq.400 (2); 10.ltoreq.(.sigma.b/.rho.c).ltoreq.20 (3), wherein .sigma.b represents a magnetization of the carrier at 1,000 Oe, .sigma.a represents a magnetization of the carrier after frictionized with a cylindrical sleeve under a specific condition and .rho.c represents a true specific gravity of the carrier, wherein the carrier has a weight-average particle diameter of about 25 to about 65 .mu.m and includes carrier particles having a weight-average particle diameter not greater than about 12 .mu.m in an amount of not greater than about 0.3% by weight, wherein a ratio between the weight-average particle diameter and a number-average particle diameter of the carrier is about 1 to about 1.3, and wherein an electric resistance is from about 1.0.times.10.sup.9 to about 1.0.times.10.sup.11 .OMEGA.cm when an AC voltage represented by the following formula (4) is applied at a frequency of 1,000 Hz to a magnetic brush of the carrier is formed between parallel plate electrodes having a gap of d mm such that magnetic brush has a space occupancy of 40%: E(V)=250.times.d (4), wherein d is 0.40.+-.0.05 mm and E is a peak voltage.

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First Claim