Heating device, fixing device, and image forming apparatus

Abstract

The heating device is designed to suppress temperature drops at its longitudinal ends and prevent overheating in non-paper-passing sections while ensuring a uniform heat output along its longitudinal direction. [Solution] A heating device (heater 23) through which a sheet-like heating member is passed, wherein when the direction of passing paper in the nip portion is the short direction and the direction perpendicular to the short direction is the long direction, a first strip-shaped resistor 51a and a second strip-shaped resistor 51b are arranged inside the heating member, extending in two rows in the long direction, a gap 60 having a constant width in the short direction is formed between the first strip-shaped resistor 51a and the second strip-shaped resistor 51b, the first strip-shaped resistor 51a and the second strip-shaped resistor 51b have a central region L2 having a constant width in the short direction at the center in the long direction, and an end region L1 at the end in the long direction adjacent to the central region L2 where the width in the short direction changes, and the sum of the widths of the first strip-shaped resistor 51a and the second strip-shaped resistor 51b in the short direction is constant in the long direction.

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