JP2015132859A5 - - Google Patents

Description

In order to solve the above problems, the present invention provides a rotatable fixing member, a heating source that heats the fixing member by radiant heat , an opposing member that abuts an outer peripheral surface of the fixing member to form a nip portion, rotatably provided around the heat source, a shielding member for shielding the radiant heat of the fixing member from the heating source, temperature measurement means for measuring the temperature of the fixing member or the opposing member, the shielding member In the fixing device including a control unit that controls a rotation angle, the shielding member is adjacent to a shielding part provided in a region covering a part of the heating source in the axial direction and one axial direction of the shielding part. An opening portion provided, the shielding portion having an end shape in the circumferential direction, and when performing continuous printing on a plurality of sheets, the control unit includes at least a sheet size and a first sheet. after but began to pass through the nip And adjusting the rotation angle of the shielding member based on the temperature measured by serial temperature measuring means.

In addition, in the above fixing device, the rotation angle of the shielding member 27 is determined based on the paper size and the printing time. Accordingly, even when the rotation angle of the shielding member 27 cannot be determined by the temperature of the fixing belt 21 during printing, the rotation angle of the shielding member 27 is appropriately determined by estimating the heating state of the fixing belt 21 from the printing time. can do.

Claims (9)

A rotatable fixing member; a heating source that heats the fixing member by radiant heat ; an opposing member that contacts the outer peripheral surface of the fixing member to form a nip portion; and a rotatable around the heating source. comprising a shield member for shielding the radiant heat of the fixing member from the heating source, temperature measurement means for measuring the temperature of the fixing member or the opposing member, and a control unit for controlling the rotation angle of the shielding member In the fixing device,
The shielding member has a shielding part provided in a region covering a part of the heating source in the axial direction, and an opening provided adjacent to one axial direction of the shielding part. Ended shape in the direction,
In performing continuous printing on a plurality of sheets, the control unit is configured to control the shielding member based on at least the sheet size and the temperature measured by the temperature measuring unit after the first sheet starts to pass through the nip portion. A fixing device that adjusts a rotation angle of the fixing device.   The control unit selects one rotation angle based on the temperature measured by the temperature measuring means from a plurality of rotation angles set according to the paper size, and arranges the shielding member at the selected rotation angle. The fixing device according to claim 1. The fixing device according to claim 1, wherein the control unit further adjusts a rotation angle of the shielding member based on a printing time. The fixing device according to claim 1, wherein the control unit further adjusts the rotation angle of the shielding member based on the number of printed sheets.   5. The fixing device according to claim 1, wherein a linear portion extending along the axial direction is provided at one circumferential edge of the shielding portion. 6.   The fixing device according to claim 1, wherein an inclined portion that is inclined with respect to a circumferential direction is provided on one edge in the axial direction of the shielding portion. The fixing device according to claim 6 , wherein the inclined portion is provided at a position straddling an end of a standard size sheet in an axial direction. The fixing member is an endless fixing belt;
8. The fixing device according to claim 1, further comprising a nip forming member that forms the nip portion in contact with the facing member via the fixing belt. 9.   An image forming apparatus comprising the fixing device according to claim 1.