Fixing device and image forming apparatus
A fixing device is disclosed that has a heating rotating member configured to be rotatable and to heat the unfixed toner image; a pressing rotating member configured to be rotatable and to form a fixing nip portion by coming in contact with the heating rotating member; and a separating member configured to separate the recording material having passed through the fixing nip portion from the heating rotating member, the separating member being provided downstream of the fixing nip portion in a conveying direction of the recording material to be opposed to the heating rotating member with a gap in a non-contact state, wherein the pressing rotating member comes in contact with the heating rotating member to form the fixing nip portion that nips and conveys the recording material with a first pressure or a second pressure that is lower than the first pressure, and wherein the separating member moves more downstream in the conveying direction when the pressure of the fixing nip portion is the second pressure than when the pressure of the fixing nip portion is the first pressure.
1 . A fixing device that fixes an unfixed toner image formed on a recording material onto the recording material, comprising:
a heating rotating member configured to be rotatable endless belt and to heat the unfixed toner image;
a pressing rotating member configured to be rotatable and to form a fixing nip portion by coming in contact with the heating rotating member;
a separating member configured to separate the recording material having passed through the fixing nip portion from the heating rotating member, the separating member being provided downstream of the fixing nip portion in a conveying direction of the recording material to be opposed to an outer surface of the endless belt with a gap in a non-contact state; and
a drive mechanism,
wherein in response to a rotation of the drive mechanism, the pressing rotating member moves from a first pressure state, in which the pressing rotating member contacts the heating rotating member to form the fixing nip portion that nips and conveys the recording material with a first pressure, to a second pressure state, in which the pressing rotating member contacts the heating rotating member to form the fixing nip portion that nips and conveys the recording material with a second pressure that is lower than the first pressure,
wherein the separating member moves, relative to a fixed position of the fixing nip portion, more downstream in the conveying direction when the pressure of the fixing nip portion is the second pressure than when the pressure of the fixing nip portion is the first pressure, and
wherein as the pressing rotating member moves from the first pressure state to the second pressure state in response to the rotation of the drive mechanism, the separating member moves downstream in the conveying direction.
2 . The fixing device according to claim 1 ,
wherein the separating member moves in a region on a side of the heating rotating member from a discharging locus of the recording material discharged from the fixing nip portion.
3 . The fixing device according to claim 1 , further comprising:
a nip portion forming member that forms the fixing nip portion,
wherein the nip portion forming member has a curved portion at an end portion on a downstream side in the conveying direction in the fixing nip portion, the curved portion is configured to separate the recording material from the endless belt by curving the endless belt, and the nip portion forming member forms the fixing nip portion by pressing the pressing rotating member via the endless belt inside the endless belt.
4 . The fixing device according to claim 1 , further comprising:
a pressing member that presses the pressing rotating member to the heating rotating member to form the fixing nip portion of the first pressure or the second pressure,
wherein the separating member moves interlocked with a pressing operation of the pressing member.
5 . The fixing device according to claim 1 , further comprising:
a positioning member configured to be able to move together with the separating member, and
a restricting member configured to movably hold the positioning member and to set a position of the separating member with respect to the heating rotating member by restricting a movement of the positioning member.
6 . An image forming apparatus comprising:
the fixing device according to claim 1 , and
a toner image forming portion configured to form an unfixed toner image on the recording material and to convey the recording material on which the unfixed toner image is formed to the fixing device.
7 . The fixing device according to claim 1 ,
wherein the endless belt has a first side and a second side opposite across a thickness of the endless belt from the first side,
wherein the pressing rotating member contacts the first side of the heating rotating member to form the fixing nip portion, and
wherein the separating member is provided downstream of the fixing nip portion in the conveying direction of the recording material to be opposed to the first side of the heating rotating member with the gap in the non-contact state.
8 . The fixing device according to claim 1 ,
wherein when the pressure of the fixing nip portion is the first pressure, the separating member is disposed at a first location such that a first gap exists between the separating member and the heating rotating member, and
wherein when the pressure of the fixing nip portion is the second pressure, the separating member is disposed at a second location different from the first location such that a second gap larger than the first gap exists between the separating member and the heating rotating member.