Patent ID: 8285182
Filing Date: 2012-10-09
Classification: G03G

Abstract:
1. A fixing device, comprising: a frame; a heating roller provided to the frame to produce heat, the heating roller having a roller rotation axis and a cylindrical surface; a press roller pressed against the cylindrical surface to feed a recording medium together with the heating roller along a feeding path; a peeler provided to the frame and having a peeling surface having a leading edge, the leading edge facing the cylindrical surface to peel off the recording medium on the cylindrical surface, the peeling surface facing the feeding path; a guide member positioned facing the peeling surface to guide the recording medium which has passed through between the heating roller and the press roller to downstream of the feeding path, the guide member configure to be movable between a near position and a far position during operation of the fixing device, the near position being closer to the peeling surface than the far position; a first bias unit that biases the guide member to the near position; a wheel supported to the frame and having a wheel rotation axis and a circumferential edge, the wheel rotation axis being parallel to the roller rotation axis, the wheel being positioned in a manner that a part of the circumferential edge protrudes from the peeling surface toward the guiding member and returns to the peeling surface in a virtual perpendicular to the wheel rotation axis; a remove assistance member provided to the frame; a rib provided to the frame and protruding from the peeling surface to the guide member in the virtual plane; a detection member supported by the guide member on a downstream side with respect to the heating roller in the feeding path, the detection member being displaceable when contacting with the recording medium; an optical sensor fixed to the frame, and having a light emitter for emitting a light beam and a light receiver for receiving the light beam traveling from the light emitter to the light receiver; a blocking member that interlocks with the detection member, the blocking member moving between a light block state and a light passing state in accordance with the displacement of at least one of the detecting member and the guide member; and a controller that determines whether a jam of the recording medium has occurred based on a movement of the blocking member, wherein the leading edge of the peeling surface is removed in a first direction away from the heating roller when a force having a predetermined value or more is exerted on the peeling surface, wherein the peeler has a back surface opposite to the peeling surface and a distal edge opposite to the leading edge, the distal edge being movably supported by a shaft which is movable in a second direction away from the guide member, wherein the remove assistance member is brought into contact with the back surface of the peeler to remove the leading edge of the peeler away from the heating roller when the peeler removes away from the guide member together with the shaft in the second direction; wherein the rib is positioned on the downstream side with respect to the wheel in the feeding path; and wherein the blocking member is in the light blocking state when the guide member is at the near position, and in the light passing state when the guide member is at the far position.