| 摘要 |
PURPOSE:To precisely reproduce a low image density part by sufficiently minimizing the size of a spot which irradiates a scanned surface in relation to a recording density, and setting the grain diameter distribution of used toner at a prescribed value. CONSTITUTION:A laser beam scanner is composed of semiconductor laser part 102, polygon merror 105, ftheta lens 106, etc., the semiconductor laser part 102 receives the input of a time series digital image signal, which is operated and outputted by an image reader, a computer, etc., a laser beam whose pulse width is modulated (PWM) corresponding to the signal is oscillated; consequently a drum surface is exposed. The spot size of the beam spot in the scanning direction is in the relation of spot size (1/e<2>)<(picture element size X 0.7) to a recording picture element size in the scanning direction; as for developer including toner used to develop a latent image, 90 vol.% or more toner is includ ed in a range of (1/2)M<r<(3/2)M in the toner volume distribution, and 99 vol.% toner is included in the range of 0<r<2M where M is a volumetric average grain diameter of toner and (r) is a grain diameter of toner grains. |
