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:
Nov. 03, 2009
Filed:
Jul. 15, 2003
Hideki Sugiura, Shizuoka, JP;
Satoshi Mochizuki, Shizuoka, JP;
Kazuhiko Umemura, Shizuoka, JP;
Shinya Nakayama, Shizuoka, JP;
Yasuo Asahina, Shizuoka, JP;
Hideki Sugiura, Shizuoka, JP;
Satoshi Mochizuki, Shizuoka, JP;
Kazuhiko Umemura, Shizuoka, JP;
Shinya Nakayama, Shizuoka, JP;
Yasuo Asahina, Shizuoka, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
An external additive for a toner for electrophotography which contains oxide fine particles which contain silicon, in which the oxide fine particles have a primary particle diameter of 30 nm to 300 nm in number average, a standard deviation σ of a particle size distribution of the primary particle diameter satisfies a relation of: R/4≦σ≦R, in which the R expresses the primary particle diameter, the oxide fine particles are substantially spherical having a circularity SF1 defined as equation (1) of 100 to 130 and a circularity SF2 defined as equation (2) of 100 to 125;1=()×(π/4)×100  equation (1)2=()×(1/4π)×100  equation (2),in the equations, 'L' expresses the absolute maximum length of the oxide fine particles; 'A' expresses a projected area of the oxide fine particles; and “P” expresses a maximum perimeter of the oxide fine particles.