| 摘要 |
PURPOSE:To stably and accurately detect toner concentration though the quantity of a developer is changed, by providing a toner concentration sensor on the scraping-up face of a blade and detecting the toner concentration in a position where the density of the developer to the sensor is highe and fixed. CONSTITUTION:A blade 34 consists of a scraping-up face 34a and a catching part 34c in the front end, and a toner concentration sensor 35 is so provided that is detecting part is engaged with a hole 34d of the blade 34. The developer on a developing roll 33 is scraped from the developing roll 33 by the catching part 34c of the blade 34 and is raised along the scraping-up face 34a against its own weight. Since the blade 34 has not a horizontal face, the rising developer, when losing the rising force, is dropped to a flow control member 36. Consequently, the flow direction of the developer to the toner concentration sensor 35 is fixed and uniform, and the density is fixed. Thus, the toner concentration is kept stably and accurately because the toner concentration sensor 35 detects the change of permeability of the developer having the fixed density. |
