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:
Dec. 16, 2003
Filed:
Mar. 29, 2002
Noboru Sawayama, Tokyo, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A permeability detection apparatus configured to stably execute a permeability detection operation for toner concentration and characterized by improved sensitivity. The permeability detection apparatus includes: a detection circuit ; an oscillation circuit that oscillates a natural frequency to drive the detection circuit; and a phase comparison circuit that extracts signals at an input side of the detection circuit and an end side of the circuit element to perform phase comparison. The detection circuit includes a coil L , a capacitor C connected to the coil in series or in parallel, and a resistance R connected to the coil in series or in parallel, and a resistance R connected to the coil and the capacitor. The resistance R allows the oscillation circuit to eliminate influence from the detection circuit and to oscillate the natural frequency continuously. The coil and the capacitor form a resonant circuit, and a resonant frequency circuit is set approximately equal to the natural frequency.