| 摘要 |
PROBLEM TO BE SOLVED: To obtain an image forming device with which high-quality clean and white images having black image parts of an adequate density free of fogging in white ground parts are obtainable even if the developing capacity of a developing device changes according to the use environment and use conditions. SOLUTION: Development is executed by externally adding >=0.5 pts.wt. strontium titanate to toners, using such toners and impressing rectangular wave voltages having specified gaps between an image carrying member and a developing sleeve. The electric field between the peak voltage V(-) on the side where the toners are made to fly from above the developing sleeve to the image carrying member among the peak voltages of the rectangular waves and the bright part potential V1 part on the image carrying member is specified to >=4.1 V/μm and likewise the electric field between the peak voltage V(-) and the dark part potential Vd part on the image carrying member is specified to <=3.5 V/μm. The electric field between the peak voltage V(+) on the side where the toners are pulled back to the developing sleeve and the dark part potential Vd part is specified to <=2.9 V/μm. The density change of the images is executed by changing the duty ratio of the rectangular waves between 20 and 50% on the peak voltage V(-) side. |
