| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the residual amount of developer regardless of the driving speed, for example, of a stirring means by providing plural developer residual amount detecting thresholds in accordance with the driving of a stirring means which is made variable as a developer residual amount detecting threshold. SOLUTION: Whether the rotating speed of the stirring means is ordinary rotating speed α set previously is judged (S1). When the rotating speed of the stirring means is α, whether or not light transmitting time per unit time is longer than the threshold X (residual amount detecting threshold) of the light transmitting time set previously is judged (S2). When it is longer than the threshold X, a user is informed that the developer does not exist (S3), and when it is shorter, the detection of the residual amount of the developer is finished. Meanwhile, when the rotating speed of the stirring means is β(>α), whether or not the light transmitting time per unit time is longer than the threshold Y (developer residual amount detecting threshold) set previously with respect to the speed β is judged (S4). When it is longer than the threshold Y, the user is informed that the developer does not exist (S5), and when it is shorter, the detection of the residual amount of the developer is finished. |
