| 摘要 |
PURPOSE:To stabilize the electrostatic charging capacity of toner and to form an excellent image by setting up a time constant indicating the product of the toner resistance of non-magnetic one-component toner and toner charging capacity to a value smaller than a minimum friction time. CONSTITUTION:Toner is applied by an elastic blade 26 press-contacted against the surface of a developing roll 24 and reverse charge is applied and transferred to a photosensitive body 12 by friction between the roll 24 and the blade 26. The time constant tau indicating the product of the toner resistance of the non- magnetic one-component toner (a) and toner charging capacity is set up to a value smaller than the minimum friction time (tf) indicating the product of the peripheral speed of the roll 24, and the contact width of the blade 26 and the roll 24. Consequently, toner can be frictionally charged between the roll 24 and the blade 26 for a period longer than the time required for sufficiently charging the toner, so that the rise of toner charging capacity can be improved and a sufficiently stable and excellent image can be obtained. Provided that toner specific resistance is >=1X10<9>OMEGA.cm. |
