| 摘要 |
PURPOSE:To reproduce the half tone faithfully, by turning on and off switch groups, which are connected to coil taps of a magnetic head, selectively in accordance with the variable density of an image to control the developing capability of a magnetic latent image. CONSTITUTION:Switch groups S1-S4 and S1'-S4' are connected to coil taps of a magnetic head 5, and the tap at the middle point of the half of the number of turns is connected to a power source potential +V1, and respective taps are connected to switch groups in positions by which the whole of the number of turns is divided equally. A decode logic 4 operates switches selectively in accordance with the level of the image density on a basis of outputs A1 and A2 of an A-D converter 3. Thus, the magnitude of the magnetomotive force induced in the head 5 is changed. The attraction for the magnetic toner is strong on a magnetic face where magnetization is much changed, and the magnetic toner is much stuck there. The magnetic toner is less stuck on a magnetic face where magnetization is less changed, and the magnetic toner is stuck intermediately on a magnetic face where magnetization is changed intermediately, and thus, an image read signal is reproduced faithfully in the developing density distribution. |
