| 摘要 |
PURPOSE:To reduce the cost and size of a developing device by providing a developing sleeve, a toner supply means that developing toner held on the surface of a magnetic brush contacts when the thickness exceeds a specific value, and a developing toner hopper which is provided with the toner supply means at an opening part. CONSTITUTION:When nonmagnetic or weakly magnetic developing toner 4 is consumed for development, the quantity of magnetism of a two-component developer 2 sticking on the surface of a developing sleeve 1 increases, so the formed magnetic brush of the two-component developer 2 becomes thicker, and consequently the magnetic brush contacts the developing toner 4 held on the surface of a toner supply roll 3, so that the developing toner 3 is moved as shown by an arrow (c). The developing toner 4 supplied into the two-component developer 2 is mixed and agitated with the two- component developer 2 with an alternating magnetic field produced on the surface of the developing sleeve 1 by the rotation of a magnet roll 10. Thus, the developing toner 4 is supplied and the quantity of magnetism of the two-component developer 2 sticking on the surface of the developing sleeve 1 decreases, so the thickness of the formed magnetic brush decreases. Consequently, the constitution is simplified and the cost and size are also reduced. |
