| 摘要 |
PURPOSE:To obtain images which are bright and have high quality over a long period of time by forming alternating electric fields as specific waveforms consisting of a DC voltage and asymmetrical alternating voltages and using a specific toner for a magnetic toner at the time of making development by applying the alternating electric fields to the toner. CONSTITUTION:The alternating electric fields are formed of the DC voltage and the asymmetrical alternating voltages and the development side voltage component of the alternating bias voltage contg. the DC bias voltage is made the same or larger than the reverse development side voltage component. The time for impressing the development side voltage is set smaller than the time for impressing the reverse development side voltage. The magnetic toner is formed of >=12piece% of magnetic toner particles having <=5mum grain size, <=33piece% of magnetic toner particles having 8 to 12.7mum grain size, and <=2.0vol.% magnetic toner particles having >=16mum grain size and has the grain size distribution of 4 to 10mum volume average grain size of the magnetic toner. The toner contains the binder resin and magnetic iron oxide (FeO content is 25 to 30wt.%). The binder resin has 2 to 100mgKOH/g total acid value (A) of the entire part when the acid anhydride group contained therein is hydrolyzed and <6mgKOH/g total acid value (B) derived from the acid anhydride and has <=60% ((B)/(A))X100. |
