JPS54153635A - Detecting and controlling method of toner contents in developer and device for said method - Google Patents

Abstract

PURPOSE:To improve reliability by providing an insulation characteristic function to the outside surface of a developer conveying means, etc. and specifying the material of carrier. CONSTITUTION:An insulation layer 104' is formed on the outside surface of the developer conveying means 104 disposed on the outside circumference of the magnet 102 group disposed on a support 101. The carrier of the developer d comprises the iron powder of 50 to 200 microns in grain size, 1.5 to 2.5 g/cm<3> in apparent density and 0.01 to 0.3 m<2>/g, preferably 0.03 to 0.20 m<2>/g in specific surface area with the outside surfaces having been covered with iron oxide. AS a result, at the time when the developer d is scraped off by a scraper 106 after it has turned the electrostatic latent image on the surface of a photosensitive drum 1 to a toner image by being sucked onto the outside surface of the developer conveying means 104 by the suction force of the magnet group 102, the friction charging characteristic, temperature resistance and mechanical and electrical durability of the carrier of the developer d are improved and the fatigue of the developer d is prevented by the insulation layer 104'. The amount of the toner is accurately detected by way of a counter electrode 12 and a comparator 14.