Patent ID: 8590372

Claim:
A device for measuring adhesion of toner to carrier containing a magnetic component, the toner and the carrier being contained in a two-component developer, the device comprising: a developer holding section including: a first magnet for holding the two-component developer by a magnetic force, a holding surface of the first magnet being one of a south pole and a north pole, and a second magnet positioned to face the holding surface of the first magnet, a surface of the second magnet which faces the first magnet having a polarity opposite to that of the holding surface of the first magnet; an airflow supply section for supplying airflow to the two-component developer held by the first magnet; a separated toner detecting section for detecting the number of toner particles separated from the carrier by the airflow; and an adhesion calculating section for calculating the adhesion of the toner to the carrier or an index of the adhesion, based on wind speed of the airflow and the detected number of the separated toner particles; wherein the first magnet includes a plurality of first protrusions protruding toward the second magnet, and the second magnet includes a plurality of second protrusions positioned to face the first protrusions, respectively, and protruding toward the first magnet, the first protrusions and second protrusions being made of a magnetic material, and wherein the first protrusions and the second protrusions form a magnetic force therebetween which holds the two-component developer.