Fixing device and image forming apparatus

An image forming apparatus comprising:

• a heating rotary member configured to heat a recording material;
• a pressing rotary member configured to press the heating rotary member, and to form a nip portion with the heating rotary member, and to fix a toner image on the recording material with the heating rotary member;
• an acquisition unit configured to acquire grammage information about the recording material;
• and
• a temperature control unit configured to control a temperature of the heating rotary member based on the grammage information,
• wherein the temperature control unit controls the temperature of the heating rotary member based on the grammage information corresponding to a predetermined number of sheets of recording materials, when the acquisition unit completes the acquisition of grammage information the grammage information corresponding to the predetermined number of sheets of recording materials within a predetermined time period after a printing start signal for a job to form the images on the predetermined number of sheets of recording materials is input, and
• wherein the temperature control unit controls the temperature of the heating rotary member based on the grammage information corresponding to a smaller number of sheets of recording materials than the predetermined number of sheets of recording materials without waiting for completion of the acquisition of the grammage information corresponding to the predetermined number of sheets of recording materials, when the acquisition unit has not completed the acquisition of the grammage information corresponding to the predetermined number of sheets of recording materials within the predetermined time period after the printing start signal is input.