| 摘要 |
PURPOSE:To increase image density and to improve fine line reproducibility and highlight gradation characteristic by specifying the spot size in the scanning direction of a beam spot and the grain size distribution of toner particles. CONSTITUTION:The spot size is specified to (1/e<2>)<picture element size X0.7 with respect to the recording picture element size in the scanning direction of the beam spot and the volume average diameter of the toner is 6 to 11mum. The toner particles having <=5mum grain size are incorporated at 8 to 40 pieces % into this toner, the toner particles having 12.7 to 16.0mum grain size at 0.1 to 15.0vol.% and the toner particles having >=16mum grain size at <=1.0vol.%. The toner particles of 6.35 to 10.1mum have the grain size distribution satisfying equation I. In the equation I, V denotes the vol.% of the toner particles having 6.35 to 10.1mum grain size; N denotes the pieces % of the toner particles having 6.35 to 10.1mum grain size; dV denotes the average volume diameter of the entire toner particles. The sharp images having the high density and resolution and excellent gradation characteristic are obtd. in this way. |
