Patent ID: 6542704
Filing Date: 2003-04-01
Classification: G03G

Abstract:
A liquid developing device comprising:a storage tank which stores an ink, including a toner and a carrier, for developing an electrostatic latent image formed on a photoconductor; an ink supply pump which sends an ink from said storage tank to the photoconductor; a concentration sensor which measures a toner concentration of the ink to be sent to the photoconductor; a storage-amount sensor which measures an amount of ink stored in said storage tank; a concentrated-ink supply pump which sends a concentrated ink from an ink cartridge for storing an concentrated ink to said storage tank; a carrier supply pump which sends a carrier from a carrier cartridge for storing a carrier to said storage tank; an ink discharge pump which discharges excessive ink from said storage tank to a discharge cartridge; and a controller which includes a control mode that simultaneously controls and drives said concentrated-ink supply pump, said carrier supply pump, and said ink discharge pump, so as to maintain a predetermined level of the toner concentration of the ink stored in said storage tank and a predetermined amount of the ink, based on a measurement value from said concentration sensor and a measurement amount from said storage-amount sensor; wherein said controller supplements said storage tank with a concentrated ink using said concentrated-ink supply pump, supplements said storage tank with a carrier using said carrier supply pump, and discharges an excessive ink from said storage tank using said ink discharge pump, based on an error between a measurement value from said concentration sensor and a predetermined value of the concentration and an error between a measurement amount from said storage-amount sensor and a predetermined amount, so that the toner concentration of the ink stored in said storage tank and the amount of the ink approach the predetermined value of the concentration and the predetermined amount, respectively.