RECORDING MATERIAL DETERMINATION SENSOR AND IMAGE FORMING DEVICE

PROBLEM TO BE SOLVED: To provide a recording material determination sensor that performs appropriate calibration even if a light detection signal of a photodetector is reduced.SOLUTION: A recording material determination sensor 31 includes: a light-emitting device 3, a photodetector 5, a drive part 33, and a determination part 35. The amount of light emitted from the light-emitting device 3 increases as a direct current to be supplied increases. The determination part 35 includes a calibration part 53 that determines whether a light detection signal of the photoreceptor 5 has reached a predetermined magnitude during calibration where the amount of light emitted from the light-emitting device 3 is changed. When the calibration part 53 determines that the light detection signal of the photodetector 5 has not become a signal of the predetermined magnitude even if the direct current value is changed within a range of a predetermined DC current tolerance during calibration and the amount of light emitted from the light-emitting device 3 is changed by DC drive within a range of a predetermined, the drive part 33 changes, a pulse current value, frequency or a duty ratio, or combinations thereof within a range of a predetermined pulse current tolerance including a pulse current value larger than the DC current tolerance, to change the amount of light emitted from the light-emitting device 3 with pulse drive.