PURPOSE: To simply detect the flowability of a developer and to execute control for presenting the degradation of image quality based on the result of the detection in an image forming device performing toner development.
CONSTITUTION: A flowability sensor 144 detecting the flowability of the developer is provided in a developing unit 14. The flowability sensor 144 brings the developer into contact with a surface in parallel with the vibrating direction of a thickness slippage vibrator 145 generating a transverse ultrasonic wave and detects the flowability (viscous resistance) of the developer by a change in the vibrating properties of the vibrator 145. When the deterioration of the flowability of the developer is detected by the flowability sensor 144, the result of the detection is displayed to urge the exchange and replenishment of the developer, the potential by electrification of a photosensitive drum and a toner concentration are increased to compensate the degradation of the image quality caused by the deterioration of the flowability and the developer is dried, stirred and excited to eliminate the flocculating state of the developer.
KOMATSU KATSUAKI
NISHI SHINICHI
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