Method and apparatus for reducing sheet material curl induced in a fusing operation

A method of reducing substrate curl as one or more substrates are conveyed through a fuser assembly having a heating member and a pressure member cooperating with the heating member to fuse images onto the one or more substrates, the method comprising:

• determining a fuser assembly temperature;
• determining a voltage applied to a toner image transfer roller if the fuser assembly temperature is less than a predefined value;
• determining relative humidity based on the determined voltage applied to the toner image transfer roller;
• determining a required curl reduction based on the determined relative humidity, if the determined relative humidity is greater than a predefined value;
• determining a minimum backup member temperature based on the required curl reduction;
• determining a current backup member temperature;
• conveying one or more substrates through the fuser assembly;
• and
• increasing an interpage gap between the conveyed one or more substrates if the current backup member temperature is less than the minimum backup member temperature.

A fuser assembly within an image forming apparatus having a paper path along which substrates travel through the image forming apparatus comprising:

• a heating member;
• a backup member cooperating with the heating member to form a nip therebetween for fusing images onto substrates passing through said nip;
• structure for conveying substrates along the paper path to said nip;
• and
• a processor for determining a relative humidity, determining if the relative humidity is above a predefined value corresponding to undesirable substrate curl;
• setting an interpage gap between conveyed substrates to a nominal value if the relative humidity is below said predefined value;
• and determining if the interpage gap should be increased beyond the nominal value if the relative humidity is above said predefined value, wherein:
• said processor determines if the interpage gap should be increased beyond the nominal value by determining a minimum backup member temperature corresponding to an acceptable level of substrate curl, and increasing the interpage gap if a current backup member temperature is less than the minimum backup member temperature.