| 摘要 |
PURPOSE: To control the quality of a magnetic image with high reliability by providing an optical density detector, so as to detect a magnetic field strength effect arising from marking grains and generate a response signal. CONSTITUTION: When a MICR mode so excited and magnetic toner grains are used, a switch 96 is closed and a reading head 100 is connected to a control circuit 98. Then, the head 100 transmits an AC control signal to the circuit 98 and an AC reference signal is transmitted to the circuit 98 from the optical density detector 102. At this time, the magnetic field strength effect generated by the marking grains after development on a recording member is detected and the above-mentioned AC reference signal is generated by a photodiode. Then, the circuit 98 processes the AC reference and control signals, to generate control signals as the functions of the AC reference and control signals, so that a voltage source 104 and a corona generator 22 are controlled. Therefore, the generator 22 can be regulated to generate an electric charge sufficient for always holding a photoconductive belt 10 at a fixed potential. Thus, the quality of the magnetic image can be controlled over wide latitude with reliability. |
