| 摘要 |
PURPOSE:To accurately detect density by detecting the cycle of a read value in the effective read width by a photosensor and controlling so that the read value by the photosensor may be stabilized. CONSTITUTION:An input signal from the photosensor 5 is digitized by an A/D converter 129, and the read of the photosensor 5 is controlled by the control program of a CPU 130. Namely, the read value of the half-cycle is averaged by judging that waving occurs when a difference between a maximum value and a minimum value which constitute the half-cycle of the read value is equal to or above a specified value in the effective read width of a density pattern by the photosensor 5(data on the first part and the last part of the pattern is neglected by considering the rising and falling characteristic of an eraser in the width in the rotating direction of a photosensitive drum). In such a case, the read value of one cycle is averaged as a whole when the maximum value and the minimum value which constitute the half-cycle succeeding the above half-cycle exist besides. |
