| 摘要 |
PURPOSE:To prevent contamination and fault by toner in the case of causing the secular change of the characteristic of a toner concentration sensor or using developer whose physical characteristic is somewhat different by setting the variation of output voltage to the variation of control voltage as sensitivity and controlling so that the recorder may be in a standby state without performing recording operation when the ratio of the set sensitivity to the sensitivity of a standard toner concentration sensor is not within a previously set range. CONSTITUTION:Output from the toner concentration sensor 28 is inputted in a replenishment decision circuit 34 and an arithmetic circuit 35 in a CPU 32 through an amplifier circuit 33. At the time of starting, the control voltage for controlling the strength of generated magnetic field in the sensor 28 is changed. The variation of the output voltage of the sensor 28 to the variation of the control voltage is set as the sensitivity Sy, and the ratio Sy/Ss of the sensitivity Sy to the sensitivity Ss of the standard toner concentration sensor is calculated, then whether or not the ratio M is within the range of 0.5<M<2 is discriminated. When it is within the range, ordinary recording operation is performed and when it is not within the range, the recording operation is waited and abnormality display is performed by a display part 42. |
