Fixing device, image forming apparatus incorporating same, and fixing method

A fixing device that performs a fixing operation of fixing a toner image on a recording medium, comprising:

• a fixing rotary body heated by a heater;
• a pressing rotary body separatably pressed against the fixing rotary body to form a nip therebetween through which the recording medium bearing the toner image passes;
• a temperature detector disposed opposite the fixing rotary body to detect a temperature of the fixing rotary body;
• and
• a temperature controller connected to the temperature detector, the heater, and the pressing rotary body to control the temperature of the fixing rotary body based on the temperature of the fixing rotary body detected by the temperature detector so as to heat the fixing rotary body to a plurality of preset target temperatures including a first target standby temperature, a target fixing temperature, a target idle temperature, and a second target standby temperature,
• wherein, when the target fixing temperature is lower than the first target standby temperature, the temperature controller separates the pressing rotary body from the fixing rotary body to idle the fixing rotary body for a predetermined idle time period before the fixing operation starts, and
• wherein, after the fixing operation, the temperature controller controls the heater to change the temperature of the fixing rotary body to the second target standby temperature.