Fixing device and image forming apparatus

摘要

A fixing device includes a pressure rotator pressed against a fixing rotator to form a fixing nip therebetween, through which a recording medium bearing a toner image is conveyed. A first heater is disposed opposite and heats a first heated span on the fixing rotator spanning in an axial direction thereof. A second heater is disposed opposite and heats a second heated span on the fixing rotator spanning in the axial direction thereof. A temperature sensor unit is disposed opposite an outer circumferential surface of the fixing rotator and includes a first temperature detection element to detect a first temperature of the first heated span on the outer circumferential surface of the fixing rotator and a second temperature detection element to detect a second temperature of the second heated span on the outer circumferential surface of the fixing rotator.

主权项

1. A fixing device comprising:
a fixing rotator; a pressure rotator pressed against the fixing rotator to form a fixing nip therebetween, through which a recording medium bearing a toner image is conveyed; a first heater disposed opposite of and heating a first heated span on the fixing rotator spanning in an axial direction thereof; a second heater disposed opposite of and heating a second heated span on the fixing rotator spanning in the axial direction thereof; a temperature sensor unit disposed opposite of an outer circumferential surface of the fixing rotator, the temperature sensor unit including:
a first temperature detection element to detect a first temperature of the first heated span on the outer circumferential surface of the fixing rotator; anda second temperature detection element to detect a second temperature of the second heated span on the outer circumferential surface of the fixing rotator; a calculator connectable to at least one of the first temperature detection element and the second temperature detection element to calculate output of the at least one of the first temperature detection element and the second temperature detection element; a connection switch to connect the calculator to the at least one of the first temperature detection element and the second temperature detection element; an abnormality monitor operatively connected to the calculator to detect an abnormality that at least one of the first temperature and the second temperature of the fixing rotator exceeds a predetermined upper limit temperature based on a calculation result provided by the calculator; and a breaker operatively connected to the abnormality monitor, the first heater, and the second heater to break power supply to the first heater while maintaining power supply to the second heater when the abnormality monitor detects the abnormality.