| 摘要 |
PURPOSE: To provide a color image farming device constituted so that a density sensor is easily and always precisely calibrated. CONSTITUTION: An output VMES is obtained by winding a transfer paper round a transfer drum 5, turning on the switch of the density sensor 21 in timing that the leading edge of the transfer paper is passed through the sensor 21 and measuring the transfer paper. Then, a calibration coefficient (k) is calculated by dividing the output VDEF of an initial state by VMES and superscribed on the original data of an EPROM 25. Then, the sensor 21 is calibrated by using the coefficient (k) until the next calibration thereof is executed. However, when VMES is equal to or under or over the prescribed proportion of the VDEF, the abnormality of the sensor 21 is displayed and a sensor abnormality flag in the EPROM 25 is erected. Then, the density of an image is not controlled on and after it. After the calibration is executed, a density sensor calibration flag is lowered and a normal image forming action is executed in timing that the leading edge of the transfer paper is brought into contact with a photoreceptive drum again. |
