| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device which accurately detects that toner has been completely consumed. SOLUTION: This device is provided with a quantitative patch-toner-detection means for detecting an amount of patch toner on an image carrier 20, a change- rate calculation means 50 for calculating the rate of change in the inclination of a line of correlation between the amount of patch toner and a developing bias, and a toner-deterioration-degree judge means. Based on a voltage outputted from the quantitative patch-toner detection means 40, the change-rate calculation means 50 calculates the inclination of the line of the correlation for development, and from the result of the calculation, the toner-deterioration-degree judge means 60 judges toner deterioration. |
