Patent ID: 6141509
Filing Date: 2000-10-31
Classification: G03G

Abstract:
A toner content control device for an electrophotographic apparatus, comprising:a toner content sensor for sensing a toner content of a developer existing in a developing unit in terms of a permeability of the developer;a pattern density sensor for sensing a density of a reference pattern formed on a photoconductive element; andcontrol means for determining, during usual operation, an amount of toner to be replenished on the basis of a difference between an output of said toner content sensor and a reference value, and for forming, at a preselected timing, the reference pattern on the photoconductive element, detecting a density of the reference pattern via said pattern density sensor, and correcting said reference value in accordance with the density detected;said control means driving the developing unit just after a replacement of the developer in order to detect a resulting output of said toner content sensor, determining an upper limit and a lower limit of said reference value on the basis of the output of said toner content sensor, and correcting said reference value in response to the output of said pattern density sensor within a range of from said upper limit to said lower limit up to a next replacement of the developer.