| 摘要 |
PURPOSE:To make possible the simpler correction of a change in the detection sensitivity of a potential sensor which measures the potential electrostatically charged on the surface of a photosensitive drum by utilizing the change in the difference between the detected values of the potential sensor to be caused by an environmental change. CONSTITUTION:The difference DELTAVS between the detected values S VS1, VS2 of the potential sensor is proportional to a change in the sensitivity of the potential sensor if two grid voltages VG1, VG2 are respectively assumed to be -300(V), -700(V) and the difference DELTAV0 between the potentials V01, V02 electrostatically charged on the surface of the photosensitive drum is assumed to be a specified value. The difference DELTAV'S between the detected values of the potential sensor for the two grid voltages VG1=-300(V), VG2=-700(V) is detected and the ratio to the difference DELTAVS of the detected value under the ideal environmental conditions is determined. This ratio is determined as the correction factor A of the detected values of the potential sensor. The correction quantity DELTAVG of the grid voltages is thereafter determined by using this correction factor A and the max. light quantity of the laser beam outputted from a semiconductor laser is corrected. |
