| 摘要 |
PURPOSE:To obtain a pressing force of a layer thickness controlling member which has less variance and is stable to be suitable for forming a thin layer of a developer, by setting the frequency of a fluctuating magnetic field to a value higher than the dynamic resonance frequency of the lowest order of the layer thickness controlling member. CONSTITUTION:A cylindrical sleeve 5 and a magnet roll 6 are supported coaxially and drivably and are rotated in the same direction. On the circumferential face of the roll 6, 8 magnetic poles are magnetized with different polarities alternately. A blade 7 consisting of an elastic magnetic material is so arranged that its tip part is pressed to a proper position on the circumferential face of the sleeve 5 by the magnetic force of the roll 6. A weight 8 is attached to the blade 7 to reduce the natural oscillation frequency, and a resonance frequency R1 of the lowest order is reduced. Then, a frequency omega of a pressing force N is within a proper range Z, and the stable and weak pressing force N is obtained. Since a vertical component F1 to the blade 7 of a gravity F of the weight 8 gets off the blade 7 from the surface of the sleeve 5, the DC component is reduced, and the pressing force N is weakened. |
