| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent image density from decreasing in the second half part of a recording body such as a paper (the part developed after the first half part). <P>SOLUTION: A print rate detection section 51 recognizes the print rate of a document. Therefore, for instance, the signal of an image part in a digital image signal obtained by using a CCD or the like is divided by an effective print area, the obtained print rate is inputted to a CPU 53, and the CPU 53 derives a frequency change corresponding to the print rate from a frequency change lookup table 54. Further, the number of image formations is inputted to the CPU 53 from an image forming number counter 52 and the frequency of an alternating voltage applied to a magnetic roll 1 and a developing roll 2 (in the magnetic roll 1 and the developing roll 2, the frequencies are the same) is controlled through a frequency controller 55, based on the print rate and the number of image formations. The frequency of the alternating voltage is increased together with the increase of the number of image formations, when the number of image formations exceeds a predetermined number of times. <P>COPYRIGHT: (C)2007,JPO&INPIT |
