Toner density control method for image recording apparatus and apparatus for the same

A toner density control method for an image recording apparatus which uses a toner density sensor for generating a magnetic field, causing the magnetic field to act on a two-component developing agent consisting of a toner and a carrier, and detecting a change in magnetic permeability of the developing agent, thereby detecting a toner density of the developing agent, and controls a toner density on the basis of an output voltage of said toner density sensor, comprising the steps of:

• obtaining, as a sensitivity of said toner density sensor, a change amount in output voltage of said toner density sensor with respect to a change amount in control voltage for controlling a strength of the magnetic field generated by said toner density sensor mounted in said image recording apparatus;
• calculating a ratio of the sensitivity of said toner density sensor to a sensitivity of a standard toner density sensor, thus obtaining a correction value;
• discriminating which one of a plurality of ranges bounded in accordance with operational results of a value of the output voltage of said standard toner density sensor and the correction value the value of the output voltage of said toner density sensor mounted in said image recording apparatus belongs to;
• and
• changing a replenishing amount of the toner on the basis of a discrimination result.