| 摘要 |
PURPOSE:To prevent image fogging, image nonuniformity, the lowering of picture density, and void from occurring, by specifying the peak position of flux density held by a permanent magnet confronting with a photosensitive drum, the peak value of the flux density, the width of the flux density value of 90% of the peak value, and the peak position of the flux density held by an adjacent permanent magnet. CONSTITUTION:When a line connecting between the central point of the photosensitive drum 1 and that of a magnet roll 2 is set as a reference line, and a position on the line is set at 0 deg., the aberration from the reference line of the peak position point (a) of the flux density held by the permanent magnet 4a confronting with the photosensitive drum 1 is set within a range of + or -2 deg.. Also, the peak value (b) of the flux density is set at 700-1,400G on the surface of a nonmagnetic sleeve 5, and furthermore, the width of the flux density value of 90% of the peak value is set within a range of + or -8 deg.-+ or -18 deg. from the reference line, and the flux density peak positions (d) and (d') held by the adjacent permanent magnet is constituted so that it exceeds + or -45 deg. from the reference line. In such way, the problem of the image fogging, the image nonuniformity, the lowering of the picture density, or the void, etc., can be evaded, and the image with high quality can be obtained.
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