Abstract: An image forming apparatus includes an image forming portion, a fixing device, an input portion, and a control portion. The fixing device includes a rotary member to be heated, a pressure-applying rotary member, a heat-applying portion, a pressure-applying mechanism, and a reference position detection mechanism. The control portion controls fixing processing, with the pressure-applying rotary member disposed at any of a plurality of pressure-applying positions and a pressure reduction position based on a type of the recording medium inputted through the input portion. The control portion performs control so that when a prescribed amount of time has elapsed or when a rotation amount of a shaft has reached a prescribed amount from timing at which a reference position detection sensor is brought to an on-state, the pressure-applying drive motor is stopped so as to dispose the pressure-applying rotary member at any of the plurality of pressure-applying positions.

Abstract: An image forming apparatus includes an image forming portion, a fixing device, an input portion, and a control portion. The fixing device includes a rotary member to be heated, a pressure-applying rotary member, a heat-applying portion, a pressure-applying mechanism, and a reference position detection mechanism. The control portion controls fixing processing, with the pressure-applying rotary member disposed at any of a plurality of pressure-applying positions and a pressure reduction position based on a type of the recording medium inputted through the input portion. The control portion performs control so that when a prescribed amount of time has elapsed or when a rotation amount of a shaft has reached a prescribed amount from timing at which a reference position detection sensor is brought to an on-state, the pressure-applying drive motor is stopped so as to dispose the pressure-applying rotary member at any of the plurality of pressure-applying positions.

Abstract: The fixing device (13) includes the fixing belt (20), the pressuring roller (21) and the pad (24). The pad (24) sandwiches the belt (20) with the roller (21) to form the fixing nip. The pad (24) is extended in the nip width direction, and the pressing face (40) has the first and second curved faces (41) and (42) at upstream and downstream sides in the sheet conveyance direction. The first and second curved faces (41) and (42) are formed arch-like curved to the roller (21) toward upstream and downstream sides. The first and second curved faces (41) and (42) continue at the inflection point (B) near the intersection point of the extending line (A) parallel to the pressuring direction and through the rotation center of the roller (21) on the pressing face (40). The first curved face (41) has the curvature radius (Ra) larger than the second curved face (42).

Abstract: A fixing device includes a pair of rotating members and a heating part. The pair of rotating members holds a recording medium, passes the recording medium and thermally fixes toner on the recording medium. The heating part heats one rotating member of the pair of rotating members to increases a temperature of the rotating member. The heating part is PID or PI controlled. When power consumption of an apparatus including the pair of rotating members is not higher than a predetermined value, a PID coefficient or a PI coefficient used in the PID control or the PI control is set to be smaller than when the power consumption is higher than the predetermined value.

Abstract: A fixing device includes an endless fixing belt, a belt guide, and a frame member. The belt guide has a fastening portion, an arc portion, and a contact portion. The fastening portion is fastened to the frame member. The arc portion extends from the fastening portion while curving in an arc shape along the inner circumferential face of the fixing belt and has an elastic force acting outward in the radial direction. The contact portion extends from one end of the arc portion in the circumferential direction toward the frame member and has a counter-face facing the inner circumferential face of the arc portion. The frame member has a regulating portion that extends toward the belt guide to make surface contact with, so as to overlap, the counter-face of the contact portion.

Abstract: The fixing device (13) includes the fixing belt (20), the pressuring roller (21) and the pad (24). The pad (24) sandwiches the belt (20) with the roller (21) to form the fixing nip. The pad (24) is extended in the nip width direction, and the pressing face (40) has the first and second curved faces (41) and (42) at upstream and downstream sides in the sheet conveyance direction. The first and second curved faces (41) and (42) are formed arch-like curved to the roller (21) toward upstream and downstream sides. The first and second curved faces (41) and (42) continue at the inflection point (B) near the intersection point of the extending line (A) parallel to the pressuring direction and through the rotation center of the roller (21) on the pressing face (40). The first curved face (41) has the curvature radius (Ra) larger than the second curved face (42).

Abstract: A fixing device includes an endless fixing belt, a belt guide, and a frame member. The belt guide has a fastening portion, an arc portion, and a contact portion. The fastening portion is fastened to the frame member. The arc portion extends from the fastening portion while curving in an arc shape along the inner circumferential face of the fixing belt and has an elastic force acting outward in the radial direction. The contact portion extends from one end of the arc portion in the circumferential direction toward the frame member and has a counter-face facing the inner circumferential face of the arc portion. The frame member has a regulating portion that extends toward the belt guide to make surface contact with, so as to overlap, the counter-face of the contact portion.

Abstract: A fixing device includes a fixing belt, a belt guide, a pressuring member, a heat source and an excessive temperature rise preventing device. The guide contacts with the inside of the belt to assist the belt's rotation track. The heat source is located across the belt to the pressuring member to induction-heat the belt. The preventing device has first and second lead wires connected at one and another end sides in an axial direction of the belt and prevents excessive temperature rise of the guide in noncontact. The first lead wire is extended to one end side and pulled out from the inside to the outside via one end side in the belt. The second lead wire is extended to another end side, curved toward one end side, extended to one end side and pulled out from the inside to the outside via one end side in the belt.

Abstract: A frequency determining portion determines a driving frequency of an induction heater. A determination processing portion determines whether or not the driving frequency determined by the frequency determining portion is within a predetermined prohibited frequency band. A frequency changing portion, when the driving frequency determined by the frequency determining portion is within the prohibited frequency band and is lower than a predetermined threshold within the prohibited frequency band, changes the driving frequency to a frequency equal to or lower than a lower boundary frequency of the prohibited frequency band, and when the driving frequency is within the prohibited frequency band and is equal to or higher than the threshold, changes the driving frequency to a frequency equal to or higher than a higher boundary frequency of the prohibited frequency band. A heating control portion drives the induction heater by the driving frequency changed by the frequency changing portion.

Abstract: A frequency determining portion determines a driving frequency of an induction heater. A determination processing portion determines whether or not the driving frequency determined by the frequency determining portion is within a predetermined prohibited frequency band. A frequency changing portion, when the driving frequency determined by the frequency determining portion is within the prohibited frequency band and is lower than a predetermined threshold within the prohibited frequency band, changes the driving frequency to a frequency equal to or lower than a lower boundary frequency of the prohibited frequency band, and when the driving frequency is within the prohibited frequency band and is equal to or higher than the threshold, changes the driving frequency to a frequency equal to or higher than a higher boundary frequency of the prohibited frequency band. A heating control portion drives the induction heater by the driving frequency changed by the frequency changing portion.

Abstract: A fixing device includes a fixing belt, a pressuring member, an exciting coil and a belt guide. The pressuring member comes into pressure contact with the fixing belt to form a fixing nip. The exciting coil is provided at an outer diameter side of the fixing belt and configured to generate a magnetic flux to inductively heat the fixing belt. The belt guide supports the fixing belt from an inner diameter side. The belt guide includes a contact part which is in contact with an inner circumferential face of the fixing belt and a non-contact part which is not in contact with the inner circumferential face of the fixing belt. The non-contact part is provided with a slit configured to inhibit induction heating of the non-contact part due to the magnetic flux generated by the exciting coil.

Abstract: A fixing device includes a fixing belt, a belt guide, a pressuring member, a heat source and an excessive temperature rise preventing device. The guide contacts with the inside of the belt to assist the belt's rotation track. The heat source is located across the belt to the pressuring member to induction-heat the belt. The preventing device has first and second lead wires connected at one and another end sides in an axial direction of the belt and prevents excessive temperature rise of the guide in noncontact. The first lead wire is extended to one end side and pulled out from the inside to the outside via one end side in the belt. The second lead wire is extended to another end side, curved toward one end side, extended to one end side and pulled out from the inside to the outside via one end side in the belt.

Abstract: A fixing device includes a fixing belt, a pressuring member, an exciting coil and a belt guide. The pressuring member comes into pressure contact with the fixing belt to form a fixing nip. The exciting coil is provided at an outer diameter side of the fixing belt and configured to generate a magnetic flux to inductively heat the fixing belt. The belt guide supports the fixing belt from an inner diameter side. The belt guide includes a contact part which is in contact with an inner circumferential face of the fixing belt and a non-contact part which is not in contact with the inner circumferential face of the fixing belt. A magnetic flux blocking member configured to block the magnetic flux that passes through the fixing belt is provided between the fixing belt and the non-contact part.

Abstract: A fixing device includes a fixing member and an induction heating section. The fixing member fixes an image onto a sheet. The induction heating section inductively heats the fixing member. The induction heating section includes an annular coil and a cover. The annular coil is elongated in a direction perpendicular to a conveyance direction of the sheet. The cover has first, second, and third opening rows. The annular coil includes first and second linear sections. Both the first and second opening rows are located at a side closer to the first linear section than a center line of the annular coil in the longitudinal direction. The second opening row is located closer to the second linear section than the first opening row. The third opening row is located at a side closer to the second linear section than the center line.

Abstract: A fixing device includes a fixing belt, a pressuring member, an exciting coil and a belt guide. The pressuring member comes into pressure contact with the fixing belt to form a fixing nip. The exciting coil is provided at an outer diameter side of the fixing belt and configured to generate a magnetic flux to inductively heat the fixing belt. The belt guide supports the fixing belt from an inner diameter side. The belt guide includes a contact part which is in contact with an inner circumferential face of the fixing belt and a non-contact part which is not in contact with the inner circumferential face of the fixing belt. The non-contact part is provided with a slit configured to inhibit induction heating of the non-contact part due to the magnetic flux generated by the exciting coil.

Abstract: A fixing device includes a fixing belt, a pressuring member, an exciting coil and a belt guide. The pressuring member comes into pressure contact with the fixing belt to form a fixing nip. The exciting coil is provided at an outer diameter side of the fixing belt and configured to generate a magnetic flux to inductively heat the fixing belt. The belt guide supports the fixing belt from an inner diameter side. The belt guide includes a contact part which is in contact with an inner circumferential face of the fixing belt and a non-contact part which is not in contact with the inner circumferential face of the fixing belt. A magnetic flux blocking member configured to block the magnetic flux that passes through the fixing belt is provided between the fixing belt and the non-contact part.

Abstract: A fixing device includes a fixing member and an induction heating section. The fixing member fixes an image onto a sheet. The induction heating section inductively heats the fixing member. The induction heating section includes an annular coil and a cover. The annular coil is elongated in a direction perpendicular to a conveyance direction of the sheet. The cover has first, second, and third opening rows. The annular coil includes first and second linear sections. Both the first and second opening rows are located at a side closer to the first linear section than a center line of the annular coil in the longitudinal direction. The second opening row is located closer to the second linear section than the first opening row. The third opening row is located at a side closer to the second linear section than the center line.

Abstract: Provided is a belt member used in a fixing device of an electromagnetic induction heating system. The belt member includes an endless resin base layer, heat layers, and an insulating resin layer. The heat layers are two or more layers including a non-magnetic metal stacked on the resin base layer. The insulating resin layer is an insulating layer stacked between the heating layers.

Abstract: A fixing device is provided with a fixing belt, a fixing roller inserted inside the fixing belt, a pressure roller that is pressed against the fixing belt, a coil that generates magnetic flux for induction heating of the fixing belt, and a belt regulating plate that is disposed at a side of an end surface of the fixing roller in a predetermined direction and regulates movement of the fixing belt in the predetermined direction. The belt regulating plate has a multi-layer structure including a resin plate disposed at a fixing belt side and a nonmagnetic metal plate disposed at a side opposite to the fixing belt side.

Abstract: A fixing device is provided with a fixing belt, a fixing roller inserted inside the fixing belt, a pressure roller that is pressed against the fixing belt, a coil that generates magnetic flux for induction heating of the fixing belt, and a belt regulating plate that is disposed at a side of an end surface of the fixing roller in a predetermined direction and regulates movement of the fixing belt in the predetermined direction. The belt regulating plate has a multi-layer structure including a resin plate disposed at a fixing belt side and a nonmagnetic metal plate disposed at a side opposite to the fixing belt side.