Developing device, image forming device equipped therewith, and developing density adjusting method

An image forming device using an electrophotographic printing method, the image forming device comprising a developing device,

• said developing device, including:
• a magnetic permeability detecting section for measuring magnetic permeability of developer containing toner and carriers, in order to obtain a magnetic permeability detection value;
• a toner supplying section for supplying the toner according to comparison of the magnetic permeability detection value and a magnetic permeability reference value;
• a developing section for developing, by using the toner, an electrostatic latent image formed on an image carrier;
• a developing density correcting section for correcting a developing density by correcting, according to the density of a test image formed by using the developing section, a developing bias of the developing section and/or a potential charged on the image carrier;
• a magnetic permeability reference value adjusting section for adjusting the magnetic permeability reference value in cases where a correction amount by the developing density correcting section exceeds a predetermined ordinary range;
• and
• a developing density correction reference setting section for setting a correction reference of the developing density in the developing density correcting section according to the magnetic permeability reference value thus adjusted.

A developing density adjusting method, including the steps of:

• (i) measuring magnetic permeability of developer containing toner and carriers, in order to obtain a magnetic permeability detection value,
• (ii) supplying the toner according to comparison of the magnetic permeability detection value and a magnetic permeability reference value,
• (iii) developing, by using the toner, an electrostatic latent image formed on an image carrier,
• (iv) correcting a developing density of development in step (iii) according to the density of a test image,
• said developing density adjusting method, comprising the steps of:
• (v) adjusting the magnetic permeability reference value in cases where a correction amount in step (iv) exceeds a predetermined ordinary range, and
• (vi) adjusting a correction reference of the developing density in step (iv) according to the magnetic permeability reference value.