Patent ID: 7787789

Claim:
A fixing device for an image forming apparatus comprising: a fixing member configured to nip and convey a recording medium in a predetermined direction with a first rotating member and a second rotating member and configured to fix the recording medium; a plurality of heat generating means that are respectively supplied with electric power and configured to cause the fixing member to generate heat; a temperature sensor configured to detect a temperature of the fixing member; a third current detector configured to detect an input current to a first switch power supply before current input to a door switch of the image forming apparatus; and a fourth current detector configured to detect an input current to a second switch power supply after current input to the door switch of the image forming apparatus, and a microcomputer configured to calculate an electric power that can be supplied to the heat generating means, from a detection result of the third current detector and a detection result of the fourth current detector, and to control a supply of electric power to the heat generating means according to a detection result of the temperature sensor.