| 摘要 |
PROBLEM TO BE SOLVED: To reduce the handling time of a user and to save the cost by inhibiting the output of an internal pattern in an automatic gradation correcting function, when it is judged that satisfactory results are not obtained even if an automatic gradation correction is executed. SOLUTION: This device is provided with a toner end sensor for detecting toner remaining in a toner hopper housing the toner supplied to a developing unit, a T-sensor for detecting the concn. of the toner in the developing unit and a potential control means for setting a potential control value abnormality flag, even if one of a laser light quantity, a developing bias and a grid voltage exceeds a proper range. During the end or nearly end of the toner (YES in the step S2) or when the concn. of the toner in the developing unit is not within the proper range (NO in the step S3) or the potential control value abnormality flag is set (YES in the step S4), the output of a test internal pattern and the automatic gradation correction are inhibited (S6, S8 and S10) and a reason for the inhibition is warned and displayed on an operational display part. |
