Fixing device, fixing device control method, and image forming apparatus

A method for controlling a fixing device that fixes a toner image in place on a printed surface of a recording medium by subjecting the medium to a heating temperature and a pressure during conveyance at a conveyance speed,

• the method comprising:
• at least partially shearing toner from the fixed toner image, so as to create a shorn image area that exhibits a reduced, different image density than that of an intact, unshorn image area on the printed surface of the recording medium;
• measuring the image densities of the shorn and unshorn image areas;
• and
• adjusting one or more operational parameters including at least one of the heating temperature, the pressure, and the conveyance speed for processing the recording medium through the fixing unit according to a difference between the measured image densities indicative of an adhesion strength of toner to the recording medium.

An image forming apparatus, comprising:

• an imaging unit to form a toner image on a printed surface of a recording medium;
• a fixing unit to fix the toner image in place on the printed surface of the recording medium by subjecting the medium to a heating temperature and a pressure force during conveyance at a conveyance speed along a media conveyance path;
• a shearing unit disposed downstream from the fixing unit along the media conveyance path to at least partially shear toner from the fixed toner image, so as to create a shorn image area that exhibits a different image density than that of an intact, unshorn image area on the printed surface of the recording medium;
• a detection unit disposed at least partially downstream from the shearing unit along the media conveyance path to measure the image densities of the shorn and unshorn image areas;
• and
• a controller operatively connected to the fixing unit and the detection unit to adjust one or more operational parameters, including at least one of the heating temperature, the pressure force, and the conveyance speed for processing the recording medium through the fixing unit, according to a difference between the measured image densities indicative of an adhesion strength of toner to the recording medium.