Fixing device with nip forming member having guide portions

A fixing device, comprising:

• a pressing structure;
• an endless tubular fixing structure disposed opposite to the pressing structure;
• a heating source configured to heat the fixing structure;
• a nip forming structure disposed opposite to the pressing structure via the fixing structure to form a nip portion;
• and
• a supplier configured to supply lubricant to a portion of an inner surface of the fixing structure, the portion facing the nip forming structure, wherein
• the nip forming structure includes a contact portion that contacts the inner surface of the fixing structure, the contact portion includes a guide portion for guiding lubricant, and the guide portion is formed by extending obliquely from opposite ends in a width direction toward a center of the fixing structure as the contact portion moves from upstream to downstream in a rotational direction of the fixing structure,
• the contact portion is made of woven fabric, and
• the woven fabric includes a warp as the guide portion, and a weft that is curved upward toward the downstream,
• the woven fabric includes a plurality of wefts, the plurality of wefts includes differing colors to facilitate recognition of shapes of the wefts and measurement of curvature of the wefts, and
• an amount of curvature from the center in the width direction toward opposite ends of the weft is 8 to 40% of a dimension of the contact portion in the rotational direction.