| 摘要 |
<p>PROBLEM TO BE SOLVED: To stabilize performance in the circumferential direction of a roller by setting difference of the maximum value and the minimum value of hardness in the circumferential direction of the roller to a specific ratio or under to the average hardness. SOLUTION: Difference of the maximum value and the minimum value of hardness in the circumferential direction of a roller is set to be 12% or under of the average hardness. When the difference exceeds 12% of the average hardness, performance in the circumferential direction of the roller is not stabilized particularly in the case of a developer carry roller, an image of high quality without density unevenness cannot be obtained. In the viewpoint of image quality, difference of the maximum value and the minimum value of hardness in the circumferential direction of the roller is favorable to be under 8% of the average hardness in particular. Concrete difference of hardness is different by the hardness of the roller to be unable to univocally decide, but for difference of the maximum value and the minimum value of hardness in the circumferential direction of the roller is about 15 gf or under, favorably 10 gf or under. Hereby, performance in the circumferential direction of the roller becomes stable, particularly in the developer carry roller, and an image of high quality without density unevenness can be given.</p> |
