The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 05, 2007
Filed:
Jan. 30, 2004
Masahide Yamashita, Numazu, JP;
Satoshi Mochizuki, Numazu, JP;
Tomio Kondou, Numazu, JP;
Kohsuke Suzuki, Numazu, JP;
Masahide Yamashita, Numazu, JP;
Satoshi Mochizuki, Numazu, JP;
Tomio Kondou, Numazu, JP;
Kohsuke Suzuki, Numazu, JP;
Ricoh Company, Ltd., Tokyo, JP;
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≦(σa/σb)<1.00 (1); 200≦(σb·ρc)≦400 (2); 10≦(σb/ρc)≦20 (3), wherein σb represents a magnetization of the carrier at 1,000 Oe, σa represents a magnetization of the carrier after frictionized with a cylindrical sleeve under a specific condition and ρc represents a true specific gravity of the carrier, wherein the carrier has a weight-average particle diameter of about 25 to about 65 μm and includes carrier particles having a weight-average particle diameter not greater than about 12 μm 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 1.0×10to about 1.0×10Ω·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×d (4), wherein d is 0.40±0.05 mm and E is a peak voltage.