| 摘要 |
PURPOSE: To provide the seal part of a rotary shaft for excellently sealing carrier granules by providing a magnetic member provided with plural magnetic poles provided with a magnetization axis in a direction orthogonal to the axis of the member. CONSTITUTION: This multipolar developer seal 132 for a device 80 tightly sealing the shaft of a developer unit 60 is formed from a magnetic material and fitted to a seal housing bore 14 at the circumference 138. The seal 132 is provided with two outer side magnets 118 and one inner side magnet 119 along the length of a journal 90 so as to make a magnetic field 140 form one or more ropes 115. In order to help the formation of the magnetic field 140 of the seal 132, a shunt 142 in the shape of a magnetizable washer is provided on the surface 143 of the seal 132. By the constitution, the magnetic field 140 formed in a space 136 between the seal bore 126 and the journal 90 attracts the large amount of the carrier granules 141 to the space 136 so as to form the curtain of the carrier granules for suppressing the advance of a developer material 59 passed through the space 136. |
