Image recording apparatus with toner concentration detecting circuit.

摘要

A toner concentration detecting circuit for detecting a toner concentration of two-component developer composed of toner and carrier by detecting a change of magnetic permeability of the two-component developer, for use in a developing device of an image recording apparatus. The toner concentration detecting circuit includes a sensor by which a change of magnetic permeability of the two-component developer is detected, a waveform corrector, a counter connected to a control CPU and a gate signal generating circuit connected to the control CPU by which a gate signal is sent to the counter.