PURPOSE: To obtain a copy having less ground staining and roughness by detecting the quantity of photodetection of a photoelectric converting element during the staying of a developer when a liquid repellent is precipitated, and detecting the remaining amount of the liquid repellent.
CONSTITUTION: A photosensor unit 4 consists principally of a hollow case 4a, and on its lower bottom, a CdS photoelectric converting element 4b is placed with the photodetection surface upward. Further, a projection lamp 4c is provided over the element 4b. A developer is supplied into the case 4a by a pump P through a tube 5. While the pump P supplies the developer into the unit 4, the developer consisting of a dispersant and a liquid repellent mixed is supplied into the case 4a. When the pump P stops, the separation of the repellent starts in the case 4a and only the repellent is left in the optical path between the element 4b and lamp 4c. At the time, the element 4b increases in the quantity of photodetection. Those conditions are detected through the sequence operation of a detection controller to detect the remaining amount of the repellent and toner density, thereby supplementing the toner.
TATSUMI SUSUMU
MOCHIZUKI MANABU
KUROTORI TSUNEO
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