Patent ID: 8831448

Claim:
A fixing device, comprising: a temperature rise characteristic acquisition unit that acquires a temperature rise characteristic of a recording medium, the recording medium being a cut sheet, based on temperature change information of the recording medium acquired on a temperature basis of the recording medium detected by a temperature detection unit that detects the temperature of the recording medium; and a heat generation unit that generates a heat amount provided to the recording medium in a fixing nip for fixing an image carried on the recording medium, that is adjusted on the basis of the temperature rise characteristic acquired by the temperature rise characteristic acquisition unit, wherein the temperature detection unit includes a plurality of sensors arranged downstream of the fixing device in a recording medium transport direction, the temperature rise characteristic acquisition unit acquires the temperature rise characteristic based on the temperature change information acquired on the basis of the temperature of the recording medium detected by the temperature detection unit before and after passing through the fixing nip, the temperature rise characteristic acquisition unit estimates a basis weight of the recording medium that passes through the fixing nip, based on a degree of the temperature drop of the recording medium that is a temperature difference between temperatures detected by at least two sensors among the plurality of sensors arranged downstream of the fixing nip, and a relational data of the degree of the temperature drop and the basis weight of the recording medium determined in advance, and the heat generation unit controls the heat amount provided to the recording medium in the fixing nip in accordance with the estimated basis weight.