| 摘要 |
PURPOSE:To precisely detect an abnormal condition of a potential sensor at a site, even when an inclination and a level of a sensor output is changed, or when the sensor output is in an oscillating condition. CONSTITUTION:In an image forming device provided with a potential sensor 23 detecting surface potential of a photoreceptor 20, a means impressing at least two kinds of voltages, a means measuring a measurement potential face plural times by the potential sensor 23, a means calculating an average value on the basis of the plural measured values, a means calculating the maximum value and the minimum value or the difference between them on the basis of the plural measured values, a means determining whether the average value based on two kinds of voltages is in the predetermined range or not, and a means determining whether the maximum value and the minimum value or the difference between them are in the predetermined range are provided on the measurement potential face 31 of the potential sensor 23, and an abnormal condition of the potential sensor 23 is detected by the determining means. |
