Fixing device

A fixing device comprising:

• a heating unit including:
• a belt having a tubular shape;
• a heater disposed in an internal space of the belt;
• a holder configured to hold the heater;
• a stay that is disposed to be in contact with the holder and that is configured to reinforce the holder, the stay including a first end and a second end arranged along the longitudinal direction;
• and
• a transmission member that is disposed, when viewed from a direction orthogonal to a longitudinal direction of the belt, at a position overlapping with the first end and the second end of the stay, and that is configured to apply, to the stay, pressure in a direction from the stay toward the heater;
• a pressure roller that is in contact with an outer peripheral surface of the belt, wherein the belt is sandwiched between the pressure roller and the heater, forming a fixing nip portion between the pressure roller and the belt;
• a frame configured to hold the heating unit by holding the pressure roller so as to allow the pressure roller to rotate and to hold the transmission member;
• and
• a pressure arm that is pivotably provided in the frame and that is configured to apply the pressure to the transmission member mounted on the frame,
• wherein the fixing device is configured to fix a toner image to the recording material while nipping and conveying the recording material in the fixing nip portion,
• wherein a material of the frame is resin,
• wherein the frame includes a pivot central axis to support pivoting of the pressure arm,
• wherein, when viewed from the longitudinal direction, the pivot central axis is located on an upstream side of the fixing nip portion in a recording material conveying direction and between, in a first direction orthogonal to the longitudinal direction and the recording material conveying direction, a rotation center of the pressure roller and an end of the holder positioned away from the rotation center of the pressure roller in the first direction,
• wherein the holder includes, at a position at which the transmission member is provided in the longitudinal direction, a first surface located on the upstream side of the fixing nip portion in the recording material conveying direction and a second surface located on a downstream side of the fixing nip portion in the recording material conveying direction,
• wherein the transmission member includes a first facing portion provided on the upstream side of the first surface in the recording material conveying direction and facing the first surface, and a second facing portion provided on the downstream side of the second surface in the recording material conveying direction and facing the second surface, and
• wherein the first facing portion and the second facing portion are provided so that a distance in the recording material conveying direction between the first facing portion and the second facing portion is greater than a distance in the recording material conveying direction between the first surface and the second surface by 0.02 to 0.16 mm.