JP2020166080A - Image formation apparatus and fixation device - Google Patents

Abstract

To provide a fixation device which can suppress such situations that a position of an end face of an endless belt subjected to skew control is unstable due to component variations in a unit, variations occur in scratches of the endless belt due to paper edges, the scratches become remarkable when the number of passed sheets is increased, and the image defect occurs.SOLUTION: A fixation device comprises: an upper belt assembly as a heating unit; and a lower belt assembly as a pressure unit. The upper belt assembly includes a fixation belt 105 and a belt skew control mechanism of the fixation belt 105. The belt skew control mechanism detects an end position of the fixation belt 105 by a sensor part as position detection means and controls steering means 132 for moving an endless belt 105 to one end side or the other end side in the width direction in accordance with the detection. At this time, the belt skew control mechanism is controlled such that a time-series waveform of the end position of the endless belt 105 becomes a target waveform.SELECTED DRAWING: Figure 6

Description

The present invention relates to a heat fixing device in an electrophotographic image forming device capable of forming an image on a recording material such as a multifunction device, a copying machine, a printer, and a fax machine, and more specifically to a belt fixing device.

In an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, an unfixed toner image is formed on a sheet-shaped recording material, and the toner image is heated and pressurized by the fixing apparatus to be fixed on the recording material. ing.
In order to increase the glossiness of the image and speed up the image formation, it is preferable to sufficiently melt the toner by lengthening the fixing nip. Therefore, in recent years, a belt fixing type fixing device capable of lengthening the fixing nip while reducing the size of the device has been put into practical use as compared with the conventional roll fixing method.

On the other hand, in the fixing device, since it is necessary to peel off the recording material adhered by the dissolved toner from the fixing member, a fixing device having a release layer on the surface layer is widely used. The release layer is generally formed by a tube or coating made of a material having excellent releasability such as fluororesin.

However, it is known that when the recording material passes through the fixing nip, the surface texture of the release layer is partially deteriorated due to rubbing between the fixing member and the end portion of the recording material. Since the surface texture of the toner image fixed on the recording material is affected by the surface texture of the surface layer of the fixing member, the deteriorated surface texture of the fixing member makes it impossible to obtain a uniform glossy state of the fixed toner image surface. There's a problem.

Therefore, in order to solve the above-mentioned problem, the endless belt is reciprocated in the width direction (longitudinal direction) orthogonal to the recording material transport direction to disperse the passing position of the recording material end portion, thereby using the recording material end portion. It is known to reduce the deterioration of the surface of the endless belt.

According to Patent Document 1, when the pressure belt is biased to one side, one of the rolls for suspending the belt is tilted, and the pressure belt is repeatedly controlled to be offset to the other, so that the pressure belt reciprocates within a certain range. A method of moving has been proposed.

JP-A-2015-59964

Generally, an image forming apparatus includes a transfer unit for transferring a toner image to a sheet, and a fixing unit having a heating / pressurizing roll pair arranged on the downstream side of the transfer unit in the sheet transport direction. Then, the sheet on which the toner image is transferred by the transfer unit is sandwiched by the heating / pressurizing roll pair, the image is fixed, and then the sheet is conveyed and discharged to the outside of the machine. Sheets used in this type of image forming apparatus are usually manufactured by cutting a long and wide base paper into a predetermined size. The cut sheet may have burrs on the cut surface of the sheet due to differences in the cutting method, cutting equipment, and cutting history of the cutter. The burrs on the cut surface of the sheet are caused by the sheet edge bending back to the punched side of the movable blade, and the amount, direction and shape of the burrs differ depending on the sheet size and the manufacturing lot, and are not always constant.

When a large number of sheets having burrs formed on the sheet edges are continuously conveyed to the transfer section or the fixing section, the transfer members such as the transfer roll and the fixing members such as the heating / pressurizing roll are damaged by the burrs on the sheet edge. It may be attached. Then, due to scratches on the pair of heated / pressurized rolls, streaks, scratches, or unevenness may occur in the fixed image of the sheet. For example, when a large number of small-sized sheets are fixed in succession by a pair of heating / pressurizing rolls and then a large-sized sheet is fixed, the scratches on the pair of heating / pressurizing rolls that are attached when the small-sized sheets are fixed are not present. Transferring to the fixed image of a large-sized sheet may cause streaks, scratches, or unevenness on the fixed image. As described above, if the heating / pressing roll pair is scratched, there is a problem that the image quality of the sheet is deteriorated.

As a countermeasure, instead of the heating / pressurizing roll pair, the endless belt shown in Patent Document 1 is used, and a fixing device for fixing the sheet-shaped toner is used to control the endless belt closer to damage the fixing member. A configuration has been proposed to reduce. Due to variations in alignment within the parts and assembled unit, the endless belt's leaning movement becomes unstable. Therefore, the position in the width direction of the endless belt is detected, and when the endless belt reaches a predetermined position, the alignment of the steering roll is controlled to control the deviation.

However, due to variations in the parts in the unit, the position of the end face of the endless belt that is controlled to be closer is not stable over time, and the scratches on the endless belt due to the paper edge are uneven. For example, when the endless belt is changed from one direction in the width direction to the other direction, the moving speed of the endless belt in the width direction becomes small. Further, when the endless belt moves from the right side to the left side, moves from the left side to the right side, or moves in one direction, the speed fluctuates, and the moving speed of the endless belt is small in some places. When the moving speed of the endless belt becomes low, a large number of sheets are continuously passed through the fixing device, so that burrs on the cut surface of the sheet cause many scratches on a part of the endless belt. Further, when the scratches on the endless belt are transferred to the fixed image of the sheet, streaks, scratches or unevenness may occur on a part or the whole of the fixed image. If the endless belt is scratched in this way, there is a risk that the image quality will deteriorate over a part or the whole of the sheet.

In order to solve the above problems, the fixing device according to the present invention is
The first and second rotating bodies 105 and 120, wherein at least one of the toner images t on the recording material S is fixed by the nip portion N as an endless belt, and the like.
The position detecting means 150 for detecting the position of the endless belts 105 and 120 in the width direction, and
Steering means 132 capable of moving the endless belts 105 and 120 to one end side and the other end side in the width direction, and
In the fixing device 100 having a control means for controlling the steering means 132,
The control means has the width direction of the endless belts 105 and 120 detected by the position detecting means 132 in order to cancel the fluctuation between the position and the target position in the width direction of the endless belts 105 and 120 detected by the position detecting means 150. In the width direction of the endless belts 105 and 120, the control amount of the steering means 150 is adjusted based on the difference from the position in the width direction of the endless belts 105 and 120 to the target position. It is characterized by reducing the difference between the position and the target position.

According to the fixing device according to the present invention, by incorporating compensation control for reducing the difference between the position in the width direction of the belt and the target position in the belt approach control, it is possible to suppress the influence of component variation in the unit. .. Further, the waveform can be a target of the reciprocating movement speed in the width direction of the endless belt. As a result, deterioration of image quality due to burrs on the cut surface of the sheet can be suppressed.

Sectional drawing for explaining the image forming apparatus in Example 1. External perspective view of the fixing device according to the first embodiment Cross-sectional view of the fixing device according to the first embodiment (in a pressurized state) Cross-sectional view of the fixing device according to the first embodiment (in a separated state) Left side view of the fixing device according to the first embodiment The figure explaining the steering roll tilt control mechanism in Example 1. An explanatory diagram of (a) a sensor unit that detects the position of the end of the fixing belt in the first embodiment, and (b) a diagram showing a combination of ON / OFF signals of the first and second sensors and the positional relationship at that time. Explanatory drawing of steering roll tilt control in Example 1 (A) Flow chart of belt-side control in the first embodiment, (b) Block diagram of control system The figure explaining the belt end position and the flag logic in Example 1. A graph showing the temporal displacement of the endless belt in the first embodiment due to the vertical rotation of the endless belt. A block diagram illustrating compensation control in the second embodiment. A projection drawing illustrating the belt-side control system according to the second embodiment. The figure explaining the belt end position and the flag logic in Example 2. A graph showing the temporal displacement of the endless belt in the second embodiment due to the vertical rotation of the endless belt. Explanatory drawing explaining the belt-side control system of the external heating belt unit in Example 3. Explanatory drawing of the process of controlling the end position of the external heating belt in the external heating belt unit.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(1) Image Forming Device FIG. 1 is a schematic configuration diagram of an image forming device 1 in this embodiment, and is a schematic cross-sectional view of a recording material (hereinafter referred to as a sheet) S along a transport direction V.

The image forming apparatus 1 is a four-color full-color electrophotographic printer (hereinafter referred to as a printer) of an intermediate transfer in-line method.

In the printer 1, four first to fourth image forming portions U (UY, UM, UC, UK) are arranged side by side from the left side to the right side in the drawing. Each image forming unit U has the same configuration as each other except that the color of the toner, which is a developer contained in each developer 5, is different from yellow (Y), magenta (M), cyan (C), and black (K). It is an electrophotographic image forming mechanism.

That is, each image forming unit U has an electrophotographic photosensitive member drum (hereinafter referred to as a drum) 2 as a first image carrier, a charging roll 3 as a process means acting on the drum 2, and a laser scanner. It has 4, a developer 5, a primary transfer roll 6, and the like.

The drum 2 of each image forming unit U is rotationally driven at a predetermined speed in the counterclockwise direction of the arrow. Then, a Y-color toner image corresponding to the Y-color component image of the full-color image to be formed is formed on the drum 2 of the first image forming unit UY. An M color toner image corresponding to the M color component image is formed on the drum 2 of the second image forming unit UM. Further, a C color toner image corresponding to the C color component image is formed on the drum 2 of the third image forming unit UC. A K-color toner image corresponding to the K-color component image is formed on the drum 2 of the fourth image forming unit UK. Since the process and principle of forming a toner image for the drum 2 of each image forming unit U are known, the description thereof will be omitted.

An intermediate transfer belt unit 7 is arranged below each image forming portion U. The unit 7 has an endless intermediate transfer belt 8 having flexibility as a second image carrier. The intermediate transfer belt 8 is suspended between the three rolls of the intermediate transfer belt drive roll 11, the intermediate transfer belt tension roll 12, and the secondary transfer opposed roll 13. The intermediate transfer belt 8 is circulated in the clockwise direction of the arrow at a speed corresponding to the rotation speed of the drum 2 by driving the intermediate transfer belt drive roll 11. The secondary transfer roll 14 is in contact with the secondary transfer opposed roll 13 with a predetermined pressing force via the intermediate transfer belt 8. The contact portion between the intermediate transfer belt 8 and the secondary transfer roll 14 is the secondary transfer nip portion.

The primary transfer rolls 6 of the image forming portions U are arranged inside the intermediate transfer belt 8, and are in contact with the lower surface of the drum 2 via the intermediate transfer belt 8. In each image forming portion U, the contact portion between the drum 2 and the intermediate transfer belt 8 is the primary transfer nip portion. A predetermined primary transfer bias is applied to the primary transfer roll 6 at a predetermined control timing.

The Y-color toner, M-color toner, C-color toner, and K-color toner formed on the drum 2 of each image forming unit U are sequentially superimposed on the surface of the intermediate transfer belt 8 that circulates and moves in each primary transfer nip portion. Is primarily transferred. As a result, a full-color toner image that has not been fixed even when four colors are superimposed is synthetically formed on the intermediate transfer belt 8 and conveyed to the secondary transfer nip portion.

On the other hand, one sheet S housed in the first paper feed cassette 15 or the second paper feed cassette 16 is separately fed by the operation of the paper feed mechanism, and the resist roll pair 18 passes through the transport path 17. Will be sent to. The resist roll pair 18 once receives the sheet S, and if the sheet is skewed, straightens it. Then, the resist roll pair 18 conveys the sheet S to the secondary transfer nip portion in synchronization with the toner image on the belt 8.

A predetermined secondary transfer bias is applied to the secondary transfer roll 14 while the sheet S is sandwiched and conveyed by the secondary transfer nip portion. As a result, the full-color toner images on the belt 8 side are collectively and sequentially secondarily transferred to the sheet S. Then, the sheet S exiting the secondary transfer nip portion is separated from the surface of the belt 8 and introduced into the image heating fixing device 100 as an image processing device through the transport path 19. The sheet S is heated and pressurized by the fixing device 100, and the unfixed toner image is fixed as a fixed image. The sheet S that has left the fixing device 100 is conveyed to the discharge tray 21 by the discharge roll pair 20 as a full-color image forming product and discharged.

(2) Fixing device 100
FIG. 2 is an external perspective view of the fixing device 100 in this embodiment. FIG. 3 is a cross-sectional right side view of a main part of the device 100, and shows a pressurized state of the lower belt assembly B. FIG. 4 is a cross-sectional right side view of a main part of the device 100, and shows a state in which the lower belt assembly B is released from pressure. FIG. 5 is a left side view of a main part of the device 100, showing the time when the lower belt assembly B is separated. FIG. 6 is a perspective view of the belt-side control mechanism portion.

With respect to the fixing device 100 or the members constituting the fixing device 100, the longitudinal direction (longitudinal) or the width direction (width) is a direction orthogonal to the conveying direction V of the sheet S in the sheet conveying road surface. Parallel directions (or dimensions in that direction). With respect to the fixing device 100 or the members constituting the fixing device 100, the short side (short side) is a direction (or a dimension in that direction) parallel to the transport direction V of the sheet S in the sheet transport road surface. is there.

The front surface of the fixing device 100 is the surface on the seat entrance side. Further, the back surface of the fixing device 100 is the surface on the sheet outlet side. Further, the left and right in the fixing device 100 are left or right when the device is viewed from the front. In this embodiment, the left side is the front side and the right side is the back side. Up and down means up or down in the direction of gravity. The upstream or downstream is upstream or downstream with respect to the transport direction V of the sheet S. The width of the belt or the sheet is a dimension in the direction orthogonal to the sheet conveying direction.

The fixing device 100 as the image processing device of this embodiment is an image heating device of a belt nip type, an electromagnetic induction heating (IH) type, and an oilless fixing type.

The fixing device 100 has an upper belt assembly A as a heating unit and a lower belt assembly B as a pressurizing unit. It also has a pressurizing-separation mechanism (contact / detachment means) for the lower belt assembly B with respect to the upper belt assembly A. Further, it has an IH heater (magnetic flux generating means) 170 which is a heating means for heating the fixing belt 105 in the upper belt assembly A, a belt-side control mechanism for the fixing belt 105, and the like. Hereinafter, these will be described in order.

(2-1) Upper belt assembly A and IH heater 170
The upper belt assembly A is arranged between the left and right upper plates 140 of the device housing. The upper belt assembly A has an endless belt fixing belt 105 having a release layer on the surface and having flexibility as a rotating body (heating rotating body: belt-shaped fixing member) facing the image-carrying surface of the sheet S. Have.

The fixing belt 105 is stretched (suspended) on the drive roll 131, the steering roll 132, and the pad stay 137. Further, a predetermined tension (tension) is applied to the fixing belt 105 by the axial displacement of the tension spring 156 via the steering roll 132.
The drive roll 131 (driving rotating body: fixing roll) is arranged on the seat outlet side between the left and right upper plates 140, and the left and right shaft portions 131a are respectively bearings (not shown) between the left and right upper plates 140. ) Is rotatably supported.

Steering roll support arms 154 extending from the drive roll 131 side to the seat inlet side are arranged on the outside of the left and right upper plates 140, respectively. The steering roll support arm 154 (not shown) on the right side is fixed to the upper plate 140 (not shown) on the right side. The steering roll support arm 154 on the left side is supported on the shaft 131a on the left side of the drive roll 131 via a bearing 154a so as to be swingable in the vertical direction around the shaft 131a.

A pin 151 is planted at the free end of the steering roll support arm 154 on the left side. Further, on the outer surface of the upper plate 140 on the left side, a shaft 160 is planted on the seat entrance side.

A worm wheel (blade tooth gear) 152 integrally provided with a fork plate 161 having a U-shaped groove portion 161a is rotatably supported on the shaft 160. The pin 151 of the steering roll support arm 154 on the left side is engaged with the groove portion 161a of the fork plate 161. A stepping motor 155 is arranged on the upper plate 140. The worm 157 fixed to the rotating shaft of the stepping motor 155 meshes with the worm wheel 152.

In the stepping motor 155, the fork plate 161 rotates in the upward direction or the downward direction via the worm 157 and the worm wheel 152 by driving in the forward rotation or the reverse rotation. In conjunction with this, the steering roll support arm 154 on the left side rotates upward or downward with respect to the shaft 131a.

The steering roll (steering rotating body: steering roll) 132 is arranged on the seat entrance side between the left and right upper plates 140, and the left and right shaft portions 132a are respectively relative to the left and right steering roll support arms 154. It is rotatably supported via a bearing 153.

The bearing 153 is supported by the steering roll support arm 154 so as to be slidably movable in the belt tension direction, and is moved and urged by the tension spring 156 in the direction away from the drive roll 131.

The pad stay 137 (fixing pad) is, for example, a member made of stainless steel (SUS material). The pad stay 137 is supported by fixing the left and right end portions between the left and right upper plates 140 with the pad receiving surface facing downward toward the drive roll 131 between the drive roll 131 and the steering roll 132 inside the fixing belt 105. Has been done.

In this embodiment, a tension of 200 N is applied from the tension spring 156 to the fixing belt 105. The inner surface of the lower belt portion of the fixing belt 105 is in contact with the downward pad receiving surface of the pad stay 137.

The fixing belt 105 may be appropriately selected as long as it is generated by the IH heater 170 and has heat resistance. For example, a magnetic metal layer such as a nickel metal layer or a stainless steel layer having a thickness of 75 μm, a width of 380 mm, and a circumference of 200 mm is coated with a silicone rubber having a thickness of 300 μm, and a surface layer (release layer) is coated with a PFA tube. Used.

The drive roll 131 is, for example, a roll in which a heat-resistant silicone rubber elastic layer is formed on a core metal surface layer formed of solid stainless steel with an outer diameter of φ18. The drive roll 131 is arranged on the seat outlet side of the nip region of the fixing nip portion N formed by the fixing belt 105 and the pressure belt 120 as the second rotating body described later, and the pressure roll 121 described later. The elastic layer is elastically distorted by a predetermined amount due to pressure welding.

In this embodiment, the drive roll 131 and the pressure roll 121 form a nip shape formed by sandwiching the fixing belt 105 and the pressure belt 120 substantially straight. However, in order to control the buckling of the seat S due to the speed difference in the fixing nip portion N of the seat S, various rolls such as intentionally changing the crown shape of the drive roll 131 and the pressure roll 121 to an inverted crown shape. It is also possible to arrange the crown shape of.

The steering roll 132 is, for example, a hollow roll formed of stainless steel having an outer diameter of about φ20 and an inner diameter of about φ18. The steering roll 132 functions as a tension roll that stretches and applies tension to the fixing belt 105, and its inclination is controlled by a belt approach control mechanism described later to meander in the width direction orthogonal to the moving direction of the fixing belt 105. Acts as a steering roll to adjust.

The drive roll 131 is arranged with the drive input gear G coaxially fixed on the left end side of the roll shaft 131a. A drive input is made to the gear G from the drive motor 301 (FIG. 2) via a drive transmission means (not shown), and the drive roll 131 is rotationally driven at a predetermined speed in the clockwise direction of the arrow in FIG.

The fixing belt 105 is circulated and conveyed in the clockwise direction of the arrow at a speed corresponding to the speed of the drive roll 131 by the rotation of the drive roll 131. The steering roll 132 rotates in accordance with the circulation transportation of the belt 105. The inner surface of the descending belt portion of the fixing belt 105 slides and moves with respect to the downward pad receiving surface of the pad stay 137. In order to stably convey the sheet S by the fixing nip portion N described later, the drive is reliably transmitted between the fixing belt 105 and the drive roll 131.

The IH heater 170 is composed of an exciting coil (not shown), a magnetic core (not shown), a holder (not shown) for holding the exciting coil and the magnetic core, and the like as a heating means for heating the fixing belt 105. It is an induction heating coil unit. The IH heater 170 is arranged on the upper side of the upper belt assembly A, and faces the fixing belt 105 in a non-contact manner with a predetermined interval over the upper surface portion of the fixing belt 105 and the portion of the steering roll 132 on the left and right sides. It is fixedly arranged between the upper plates 140.

The exciting coil (not shown) of the IH heater 170 generates an alternating magnetic flux when an alternating current is supplied, and the alternating current magnetic flux is guided by a magnetic core (not shown) to magnetize the fixing belt 105 which is an induction heating element. Generates an eddy current in the metal layer. Further, the eddy current in the magnetic metal layer of the fixing belt 105 generates Joule heat due to the intrinsic resistance of the induction heating element. The alternating current supplied to the exciting coil (not shown) has a surface temperature of about 140 to 200 ° C. (target temperature) of the fixing belt 105 based on the temperature information from the thermistor 220 for detecting the surface temperature of the fixing belt 105. ) To control the temperature.

(2-2) Lower Belt Assembly B and Pressurization-Separation Mechanism The lower belt assembly B is arranged below the upper belt assembly A. The assembly B is a lower frame (pressurized frame) 306 that is rotatably supported in the vertical direction about a hinge shaft 304 fixed to the left and right lower plates 303 on the seat outlet side of the fixing device 100. It is assembled against.

The lower belt assembly B is an endless pressure belt (endless) having flexibility as an opposing member (pressurizing rotating body: pressurizing member) forming the fixing belt 105 on the upper belt assembly A side and the nip portion N. It has a belt) 120.

The left and right shaft portions 121a of the pressure roll 121 are rotatably supported between the left and right side plates of the lower frame 306 via bearings 159. The left and right shaft portions 122a of the tension roll 122 are rotatably supported by the left and right side plates of the lower frame 306 via bearings 158.

The bearing 158 is supported so as to be slidably movable in the belt tension direction with respect to the lower frame 306, and is moved and urged by the tension spring 127 in a direction away from the pressure roll 121.

The pressure pad 125 is, for example, a member made of silicone rubber, and both left and right end portions are fixed and supported between the left and right side plates of the lower frame 306. The pressure roll 121 is located on the seat outlet side between the left and right side plates of the lower frame 306. The tension roll 122 is located on the seat inlet side between the left and right side plates of the lower frame 306. The pressurizing pad 125 is arranged inside the pressurizing belt 120 so as to be non-rotatingly supported with the pad surface facing upward near the pressurizing roll 121 between the pressurizing roll 121 and the tension roll 122.

The pressure belt 120 is stretched (suspended) by a plurality of tension members of a pressure roll (pressure roll) 121, a tension roll 122, and a pressure pad 125. Further, the pressure belt 120 is subjected to a predetermined tension (tension) by moving the tension roll 122 in the belt tension direction by the urging force of the tension spring 127.

In this embodiment, a tension of 200 N is applied to the pressure belt 120 by the urging force of the tension spring 127. The inner surface of the belt portion on the ascending side of the pressure belt 120 is in contact with the upward pad surface of the pressure pad 125.

The pressure belt 120 may be appropriately selected as long as it has heat resistance. For example, a nickel metal layer having a thickness of 50 μm, a width of 380 mm, and a circumference of 200 mm is coated with a silicone rubber having a thickness of 300 μm, and a surface layer (release layer) coated with a PFA tube is used. The pressure roll 121 is, for example, a roll formed of solid stainless steel with an outer diameter of φ20. Further, the tension roll 122 is, for example, a hollow roll formed of stainless steel having an outer diameter of about φ20 and an inner diameter of about φ18.

The lower belt assembly B is rotationally controlled around the hinge shaft 304 by a pressurizing-separating mechanism as a releasing means. That is, the lower belt assembly B is lifted and rotated by the pressure-separation mechanism to move to the pressurizing position as shown in FIG. Further, the lower belt assembly B is moved to a separated position as shown in FIG. 4 by being lowered and rotated.

By moving the lower belt assembly B to the pressurizing position, the pressurizing roll 121 and the pressurizing pad 125 move the pressurizing belt 120 with respect to the drive roll 131 and the pad stay 137 of the upper belt assembly A. , And the fixing belt 105 is sandwiched between them and pressed with a predetermined pressing force. Due to pressure welding between the pressure roll 121 and the pressure pad 125, a fixing nip having a predetermined width in the transport direction V of the sheet S between the fixing belt 105 of the upper belt assembly A and the pressure belt 120 of the lower belt assembly B. Part N is formed. Further, the lower belt assembly B is moved to the separation position, so that the pressure on the upper belt assembly A is released and the lower belt assembly B is separated from each other in a non-contact manner.

The above-mentioned pressurization-separation mechanism in this embodiment will be described. The lower frame 306 is provided with a pressure spring unit having a pressure spring 305 for elastically pressing the lower belt assembly B against the upper belt assembly A on the side opposite to the hinge shaft 304 side. ing.

A pressure cam shaft 307 is rotatably supported and arranged in the lower portion between the left and right lower plates 303. A pair of eccentric pressure cams 308 having the same shape and phase supporting the lower surface of the lower frame 306 are fixedly arranged on the left and right sides of the pressure cam shaft 307, respectively. A pressure gear 309 (FIG. 2) is coaxially fixed and arranged on the right end side of the pressure cam shaft 307. When a driving force is input from the pressurizing motor 302 to the pressurizing gear 309 via a drive transmitting means (not shown), the pressurizing camshaft 307 is rotationally driven.

The pressure cam shaft 307 has a first rotation angle position of the eccentric pressure cam 308 with the large ridge facing up as shown in FIGS. 3 and 5, and a second rotation angle position with the large ridge facing down as shown in FIG. The rotation is controlled to the rotation angle position of.

In the lower belt assembly B, the pressure cam shaft 307 is rotated to the first rotation angle position and stopped, so that the large ridge portion of the eccentric pressure cam 308 mounts the lower belt assembly B on the lower frame. The lower frame 306 is lifted upward in contact with the 306. Then, the lower belt assembly B abuts against the upper belt assembly A while compressing the pressure spring 305 of the pressure spring unit. As a result, the lower belt assembly B is elastically pressed and urged against the upper belt assembly A by the compressive reaction force of the pressure spring 305 at a predetermined pressure (for example, 400 N) to reach the pressure position shown in FIG. Be retained.

The drive roll 131 at the pressurizing position is warped and deformed by several hundred microns in the direction opposite to the direction in which the pressurizing roll 121 is in contact due to the pressure contact by the pressurizing roll 121. The warp deformation of the drive roll 131 causes pressure release at the central portion of the fixing nip portion N in the longitudinal direction. In order to eliminate the pressure release of the fixing nip portion N, the drive roll 131, the drive roll 131, and the pressure roll 121 are provided with a crown shape to form a nip shape by the drive roll 131 and the pressure roll 121. It is formed almost straight. In this embodiment, the drive roll 131 is provided with a positive crown shape of 300 μm.

In the lower belt assembly B, the pressure cam shaft 307 is rotated to the second rotation angle position and stopped, so that the large ridge portion of the eccentric pressure cam 308 mounts the lower belt assembly B on the lower frame. Lift down. That is, the lower belt assembly B is released from the pressure on the upper belt assembly A and is held at the separated position shown in FIG. 4 which is non-contact and predeterminedly separated.

(2-3) Belt leaning control mechanism In the rotation process of the fixing belt 105, the fixing belt 105 is offset to one side or the other side in the width direction W (FIGS. 7A and 8) orthogonal to the sheet transporting direction V. The phenomenon of moving to (belt movement) occurs. The pressure belt 120, which presses against the fixing belt 105 to form the fixing nip portion N, also moves closer to the fixing belt 105 in the same manner as the fixing belt 105.

In this embodiment, the leaning movement of the fixing belt 105 is stabilized within a predetermined leaning range by swing type leaning control. The swing type leaning control is a method of tilting the steering roll 132 in the direction opposite to the leaning movement direction of the fixing belt 105 when it is detected that the belt position has moved by a predetermined amount or more from the central portion in the width direction.

By repeating this swing-type shift control, the fixing belt 105 periodically moves from one side in the width direction (one direction in the width direction) to the other side (the other direction in the width direction), so that the belt shift movement is performed. It can be controlled stably. That is, the fixing belt 105 is configured to be reciprocally movable in the direction W orthogonal to the conveying direction V of the seat S.

In the upper belt assembly A, a sensor unit 150 ((a) in FIG. 7), which is a position detecting means for detecting the position of the end portion of the fixing belt 105, is located on the left side (front side) of the fixing belt 105 near the steering roll 132. ) Is provided. The CPU 10 detects the end position (moving position toward the belt) of the fixing belt 105 by the sensor unit 150, and uses the end position of the fixing belt 105 for compensation control described later.

The CPU 10 detects the position of the end of the fixing belt 105 by the sensor unit 150, and rotates the stepping motor 155 in the forward rotation direction (CW) or the reverse rotation direction (CCW) at the rotation speed calculated by compensation control accordingly. Let me. By rotating the stepping motor 155, the left steering roll support arm 154 is centered on the shaft 131a via the worm 157, the worm wheel 152, the fork plate 161 and the pin 151, which are the mechanisms of FIGS. 5 and 6 described above. It rotates upward or downward by the control amount calculated by compensation control. In conjunction with the control of the shaft 131a, the inclination of the steering roll 132 changes (FIG. 8), and the fixing belt 105 is controlled toward the belt.

(2-4) Sensor logic for belt-side control The sensor unit 150 is a sensor flag that can rotate in the forward or reverse direction around the first sensor 150a, the second sensor 150b, and the shaft 150f. It has 150c. By rotating the sensor flag 150c in the forward rotation direction or the reverse rotation direction, the first sensor 150a and the second sensor 150b each output ON and OFF signals in a predetermined relationship. Further, the sensor unit 150 has a sensor arm 150d that can rotate in the forward rotation direction or the reverse rotation direction about the shaft 150h.

The sensor arm 150d is rotationally urged about the shaft 150h in the direction of contact with the right end surface of the fixing belt 105 by the sensor spring 150e. In this embodiment, the sensor arm 150d is constantly pressed and contacted with the right end surface of the fixing belt 105 by the sensor spring 150e with a force of 3 gf. Therefore, the sensor arm 150d rotates about the shaft 150h in the forward rotation direction or the reverse rotation direction following the lateral movement of the fixing belt 105.

The sensor flag 150c and the sensor arm 150d are connected by a connecting mechanism 150i using a pin and an elongated hole. Therefore, the sensor arm 150d rotates in the forward rotation direction or the reverse rotation direction following the lateral movement of the fixing belt 105, and at the same time, the sensor flag 150c rotates in the forward rotation direction or in conjunction with the rotation of the sensor arm 150d. , Rotates in the reverse direction. When the sensor flag 150c rotates, the first sensor 150a and the second sensor 150b output ON and OFF signals in a predetermined relationship with each other. The CPU 10 detects the closer position of the fixing belt 105 by combining the ON / OFF signals of the first sensor 150a and the second sensor 150b.

FIG. 7 (b) shows the positional relationship related to the combination of the ON / OFF signals of the first sensor 150a and the second sensor 150b. FIG. 10 shows the relationship between the end face positions of the fixing belt 105 in the combination of the ON / OFF signals of the first sensor 150a and the second sensor 150b. Further, FIG. 9 shows a flowchart of belt-side control. The signal is turned off when the sensor flag 150c shields the first sensor 150a and the second sensor 150b from light, and becomes an ON signal when the first sensor 150a and the second sensor 150b are not shielded (flooded). The left side of the fixing belt 105 is the front side, and the right side is the back side.

The signal obtained by the sensor unit 150 is passed to the CPU 10 and used as a steering roll angle. The steering roll angle is a variable (for example, the variable a and the variable b in FIG. 10) determined by the compensation control described later, and is input to the motor driver 150D described later as the steering angle.

(2-5) Belt-side control First, when the power of the printer 1 is turned on, the CPU 10 starts the rotation of the drive motor 301 via the motor driver 302D <S09-002>. The rotation of the drive motor 301 causes the fixing belt 105 and the pressure belt 120 to rotate.

Next, the CPU 10 confirms the temperature of the fixing device 100 <S09-003>.

If the temperature of the fixing device 100 is equal to or higher than the predetermined temperature, the CPU 10 starts the belt-side control <S09-007>.

If the temperature of the fixing device 100 is equal to or lower than the predetermined temperature, the CPU 10 confirms the logic of the first sensor 150a and the second sensor 150b <S09-004>. The predetermined temperature in this example is 100 ° C.

When the CPU 10 confirms the logic of the first sensor 150a and the second sensor 150b, and the first sensor 150a is ON and the second sensor 150b is ON (state S3 in FIG. 10), the CPU 10 is a motor driver. <S09-005> that outputs a predetermined drive pulse in the CW direction of the stepping motor 155 via the 155D.

The steering roll 132 is driven by the stepping motor 155, tilts <S09-006> by an angle (variable a in FIG. 10) calculated by compensation control described later with respect to the drive roll 131, and the fixing belt 105 is from the back side to the front side. Start moving to.

After moving the fixing belt from the back side to the front side, the belt shift control <S09-007> shifts to 0, and the fixing belt 105 is controlled to lean.

In the belt-side control, the fixing belt 105 has the position <S09-011> where the first sensor 150a is ON and the second sensor 150b is OFF, the first sensor 150a is OFF, and the second sensor 150b is ON. It reciprocates between the positions <S09-014>. In this embodiment, the end face of the fixing belt 105 is between about -1.5 mm (state S4 in FIG. 10, variable b) and about +1.5 mm (state S2 in FIG. 10, variable a) from the center position. It is assumed that 105 is reciprocating.

The CPU 10 calculates using the position of the fixing belt 105 detected by the sensor unit 150, and calculates the angle (variable a and b in FIG. 10) calculated by the compensation control on the stepping motor 155 via the motor driver 155D. .. By inputting the calculated angle to the motor driver 150D, the motor driver 150D outputs a drive pulse <S09-012> <S09-015>.

The steering roll 132 is driven by the stepping motor 155 and controls by tilting the drive roll 131 by an angle calculated by the compensation control <S09-013> <S09-016>. In this embodiment, the steering roll 132 is driven by the stepping motor 155 and is controlled by tilting it by about ± 2 ° with respect to the drive roll 131.

Further, in the state where the belt-side control becomes impossible, when the end face of the fixing belt 105 moves to the positions of -3 mm (state S1) and +3 mm (state S5) from the center position, the first sensor 150a and the second sensor <S09-008> where both 150b and 150b are turned off. When both the first sensor 150a and the second sensor 150b are turned off, the CPU 10 determines that an abnormality has occurred in the configuration related to the fixing belt 105 <S09-009>, and performs the printing operation (image forming operation) of the printer 1. Make an emergency stop. Regarding the fixing device 100, the power supply to the IH heater 170 is turned off to stop the heating of the fixing belt 105, and the drive motor 301 is turned off to stop the rotation of the fixing belt 105 and the pressure belt 120. S09-010>.

Further, the CPU 10 displays information indicating that an abnormality has occurred in the fixing device 100 on the display unit of the printer operation unit 24 (FIG. 1), and prompts the user to contact the service person. In the case of a remote monitoring system, the CPU 10 notifies the service company of the occurrence of an abnormality.

While the drive motor 301 is rotating, the fixing device 100 executes the above-described series of belt-oriented controls <S09-007> to <S09-014> regardless of the standby state (standby state) or the fixing operation. ..

The pressure belt 120 moves together with the fixing belt 105 as the fixing belt 105 is controlled toward the belt. Since the pressure belt 120 has the same configuration as the belt-side control of the fixing belt 105 described above, the description of the belt-side control related to the pressure belt 120 will be omitted.

(2-6) Measurement position and target position of belt-side control In belt-side control, the position of the end face of the fixing belt 105 is detected by the sensor unit 150 (FIG. 11, solid line), and the target position of the end surface of the fixing belt 105 (FIG. 11. There is a dotted line part).

By controlling the fixing belt 105 or the pressure belt 120 with the sensor unit 150 using the detection of the end of the belt as a trigger, the belt speed as shown in the solid line portion of FIG. 11 can be obtained. Distortion occurs. This distortion of the belt speed is caused by the fact that the position of the end face of the endless belt, which is controlled to be closer, is not stable over time due to the variation of parts in the unit. For example, when the endless belt is changed from one direction in the width direction to the other direction, the moving speed of the endless belt in the width direction becomes small. Further, when the endless belt moves from the right side to the left side, moves from the left side to the right side, or moves in one direction, the speed fluctuates, and the moving speed of the endless belt is small in some places. When the moving speed of the endless belt becomes low, a large number of sheets are continuously passed through the fixing device, so that burrs on the cut surface of the sheet cause many scratches on a part of the endless belt. Further, when the scratches on the endless belt are transferred to the fixed image of the sheet, streaks, scratches or unevenness (hereinafter referred to as scratches) may occur on a part or the whole of the fixed image. If the endless belt is scratched in this way, there is a risk that the image quality will deteriorate over a part or the whole of the sheet.

On the other hand, with respect to the fixing belt 105 or the pressure belt 120, the position of the belt end face detected by the sensor unit 150 is used for compensation control described later, and the strain of the belt speed is adjusted to adjust the dotted line in FIG. It is possible to approach the belt speed without distortion like a part.

For example, the position of the end surface of the fixing belt 105 is detected by the sensor unit 150, and the sensor unit 150 detects the difference between the position detection (FIG. 11, solid line portion) and the target position of the end surface of the fixing belt 105 (FIG. 11, dotted line portion). It is input to the vessel (Fig. 12). The difference detector inputs the residual (hereinafter, residual) between the target value and the detection position, which is the calculation result, to the CPU 10. The CPU 10 stores an integration constant Ki, a proportionality constant Kp, or a differential constant Kd, which is previously determined by a transfer function (FIG. 12) that functions the frequency response related to the movement of the fixing belt 105 in the width direction. I will do it. The correction angle to the steering roll 132 that brings the residual close to 0 by multiplying and adding up the value input to the CPU 10 by the integration constant Ki, the proportionality constant Kp, or the differential constant Kd (variable a in FIG. 10). , Corresponds to the variable b). By inputting the correction angle to the motor driver 150D, the motor driver 150D generates a pulse. That is, by calculating the correction angle for bringing the angle of the steering roll 132 closer to the target angle by the CPU 10, a belt speed (control position in FIG. 11) with less distortion as in the alternate long and short dash line portion in FIG. 11 can be obtained. Can be done.

Further, by continuously passing the sheet through the belt having a belt speed without distortion, the influence of scratches caused by the burrs on the cut surface of the sheet can be reduced, and the deterioration of the image quality of the sheet can be suppressed.

(2-7) Compensation control in belt-side control A model of compensation control is shown in FIG. First, the compensation control has a target position (FIG. 11, dotted line) related to the end position of the fixing belt 105. Next, the compensation control outputs a control signal from the CPU 10 based on the target position, and controls the fixing belt 105 via a transfer function described later. The transfer function transmits the mechanical behavior when passing through the motor driver 150D, the stepping motor 155, the worm 157, the worm wheel 152, the fork plate 161 and the pin 151, the steering roll support arm 154, the shaft 131a, and the steering roll 132 in the frequency space. It is a function explained in.

Subsequently, when the fixing belt 105 moves, the sensor unit 150 in contact with the end position of the fixing belt outputs a detection position (FIG. 11, solid line portion) related to the end position of the fixing belt 105. Then, the detection position (FIG. 11, solid line), which is the end position of the fixing belt 105, is subtracted from the target position (FIG. 11, dotted line) related to the end position of the fixing belt 105, and the position is set to the end position of the fixing belt 105. A control signal is sent from the CPU 10 to the motor driver 150D using the difference between the target position and the detection position involved.

The CPU 10 has a value obtained by multiplying the difference between the target position and the detection position related to the end position of the fixing belt 105 by a predetermined proportional constant Kp, or the target position and the detection position related to the end position of the fixing belt 105. A value obtained by multiplying the difference between the above by a predetermined integration constant Ki and separately integrating for a predetermined time, or a predetermined differential constant Kd for the difference between the target position and the detection position related to the end position of the fixing belt 105. The sum of the values multiplied and differentiated is used as a control signal for the motor driver 150D. Further, the proportional constant Kp, the integral constant Ki, and the differential constant Kd are defined to satisfy the stability, the quick response, and the steady-state characteristics by substantially matching the detection position related to the end position of the fixing belt 105 with the target position.

As shown in the compensation control model (FIG. 12), the control signal output to the motor driver 150D is a control amount characterized by the proportional constant Kp, the integral constant Ki, and the differential constant Kd, so that the fixing belt in a specific period can be used. It enables stability related to the belt-side control of 105, and enables more robust control even if a disturbance is superimposed on any control path of the compensation control model (FIG. 12). Compensation control defines the frequency characteristics including the position, speed, and acceleration of the fixing belt 105 by the proportionality constant Kp, the integration constant Ki, and the differential constant Kd, so that the fixing belt 105 can be adjusted according to the position, speed, and acceleration. The number of times the steering roll 132 tilts with respect to the drive roll 131 can be automatically calculated as the variables a and b in FIG. As the compensation control calculates the variable a and the variable b, the position of the end face of the fixing belt 105, which is controlled closer to the belt, is not stable with respect to time as shown in FIG. It is possible to solve the problem that the scratches on the fixing belt 105 are uneven due to the above.

For example, as shown in FIG. 11, when the fixing belt 105 is changed from one direction in the width direction to the other direction, the moving speed of the fixing belt 105 in the width direction becomes small. Further, when the fixing belt 105 moves from the right side to the left side, moves from the left side to the right side, or moves in one direction, the speed fluctuates, and the moving speed of the endless belt is small in some places. When the moving speed of the fixing belt 105 becomes low, a large number of sheets S are continuously passed through the fixing device 100, so that burrs on the cut surface of the sheet S cause many scratches on a part of the endless belt. ..

However, since the compensation control automatically calculates the angle of the steering roll 132, the difference between the end position of the fixing belt 105 and the target position can be made substantially zero, and as a result, the steering roll 132 is targeted. Can be controlled to the waveform of.

For example, assuming that the moving speed is within a certain range with respect to the target waveform and the triangular wave is a periodic waveform, a large number of sheets S are continuously formed except for the end of the fixing belt. By passing the paper through the fixing device 100, the burrs on the cut surface of the sheet S evenly scratch the endless belt. As a result, even if the scratches on the endless belt are transferred to the fixed image of the sheet, it is possible to take measures so that streaks, scratches or unevenness do not occur on a part or the whole of the fixed image. By preventing the endless belt from being scratched, it is possible to suppress the problem that the image quality is deteriorated over a part or the whole of the sheet.

Further, it does not have to be the fixing device 100 that forms the nip N by the upper belt assembly A and the lower belt assembly B as in the first embodiment. For example, a fixing device that forms a nip N with at least one roll in the lower part of the upper belt assembly A and the upper belt assembly A, or a fixing device that forms a nip N with at least one roll in the lower part of the lower belt assembly B. It may be a device.

Next, Example 2 will be described. In this embodiment, in addition to the first embodiment, a third sensor 150j is inserted between the first sensor 150a and the second sensor 150b, and the third sensor 150j is inserted between the first sensor 150a and the second sensor 150b. The resolution related to the detection of the end position of the fixing belt 105 of the above is increased. Members having the same functions as the members described in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted unless necessary. Further, with respect to the image forming apparatus, the fixing apparatus and the like, those overlapping with the first embodiment will not be described.

In the upper belt assembly A, a sensor unit 150 (FIG. 13), which is a position detecting means for detecting the position of the end portion of the fixing belt 105, is provided on the left side (front side) of the fixing belt 105 at a position closer to the steering roll 132. ing. The sensor unit 150 has a first sensor 150a, a third sensor 150j, a second sensor 150b, and a sensor flag 150c that can rotate in the forward rotation direction or the reverse rotation direction about the axis 150f. The CPU 10 detects the end position (moving position toward the belt) of the fixing belt 105 by the sensor unit 150, and uses the end position of the fixing belt 105 for compensation control.

By rotating the sensor flag 150c in the forward rotation direction or the reverse rotation direction, the first sensor 150a, the third sensor 150j, and the second sensor 150b output ON and OFF signals in a predetermined relationship, respectively. .. As the sensor flag 150c rotates, the first sensor 150a, the third sensor 150j, and the second sensor 150b output ON and OFF signals in a predetermined relationship, respectively. The CPU 10 detects the closer position of the fixing belt 105 by combining the ON / OFF signals of the first sensor 150a, the third sensor 150j, and the second sensor 150b, respectively.

By disposing the third sensor 150j between the first sensor 150a and the second sensor 150b, it is possible to increase the resolution related to the position of the end face of the fixing belt 105 in the shift control. it can. For example, by disposing the third sensor 150j at a position where the first sensor 150a and the second sensor 150b are equally divided into equal angles, the third sensor 150j can be moved when the fixing belt is located substantially in the center. Outputs ON and OFF signals. With the addition of the third sensor 150j, the chances of the near control observing the position of the end face of the fixing belt 105 will increase, and the chances of performing compensation control will increase. In addition to the substantially angle change position (states S2 and S4 in FIG. 10), the compensation control automatically calculates the angle of the steering roll 132 (variable c in FIG. 14), as shown by the dotted line in FIG. A belt speed with less distortion (control position in FIG. 14) can be obtained.
Further, in addition to the third sensor 150j, a sensor may be added between the first sensor 150a and the second sensor 150b to increase the resolution related to compensation control.

(3-1) External Heating Belt Unit Next, the external heating belt unit of Example 3 will be described with reference to FIG. An external heating belt unit 600 for heating the fixing roll 601 from the outer circumference in order to maintain the surface temperature of the fixing roll 601 even during continuous paper passing is provided on the upper portion of the fixing roll 601.

The external heating belt unit 600, which is an external heating member, includes a frame body 604. The frame body 604 is rotated from the fixing roll 601 by rotating the pressure arm (606) around the pressure arm rotation shaft (623) fixed to the fixing device by rotating the pressure cam 605. It is configured so that it can be touched or evacuated. The rotation of the pressurizing cam 605 is performed by controlling the motor 608 connected to the pressurizing cam 605 based on the control unit 607.

The frame body 604 includes an intermediate frame 624. The intermediate frame 624 includes a first support roll 602 and a second support roll 603. The first support roll 602 and the second support roll 603 are rotatably supported by an intermediate frame 624 on which an external heating belt 610 is stretched. Further, the external heating belt 610 is driven by the rotation of the fixing roll 601 when the external heating belt 610 is pressed against the fixing roll 601 by applying a tension at a predetermined pressure by the pressure spring 609. As a result, the external heating belt 610 is arranged so as to rotate.

In this embodiment, the first support roll 602 and the second support roll 603 are provided with a core metal made of cylindrical metal having an outer diameter of 30 mm, a thickness of 2 mm, and a length of 360 mm, for example, aluminum.

The external heating belt 610 has, for example, a layer of a resin base material such as polyimide having an outer diameter of 60 mm, a thickness of 100 μm, and a width of 350 mm, and fluorine is used as a heat-resistant sliding layer in order to prevent adhesion to toner. The based resin (PFA tube in this example) is coated with a thickness of 20 μm.

Inside the core metal of the first support roll 602 and the second support roll 603, for example, a halogen heater 611 having a rated power of 1000 W or a halogen heater 612 is arranged as a heating element, respectively. The halogen heater 611 or the halogen heater 612 is light-distributed so as to heat the first support roll 602 and the second support roll 603.

The external heating belt 610 is heated by the first support roll 602 and the second support roll 603, and comes into contact with the fixing roll 601 to heat the surface layer of the fixing roll 601.

(3-2) Belt leaning control in the external heating belt unit With reference to FIG. 17, a process of leaning control of the end position of the external heating belt 610 in the external heating belt unit 600 will be described.

The first support roll 602 and the second support roll 603 on which the external heating belt 610 is stretched are integrally tilted together with the frame body 604 around the rotation shaft 613 to form the fixing roll 601 and the frame body 604. The crossing angle θ is intentionally set between them to control the lateral movement amount of the external heating belt 610. The rotation shaft 613 is a rotation center that changes the intersection angle θ between the external heating belt 610 and the fixing roll 601.

The fan-shaped worm wheel 615 is rotatable about the center of the rotating shaft 614 and meshes with the worm gear 616. When the motor 617 rotates in the forward direction to rotate the worm wheel 615 in the direction of arrow L, the support shaft 618 fixed to the end of the frame 604 moves in the direction of arrow C to follow the rotation of the fixing roll 601. Therefore, a leaning force acts on the external heating belt unit 600 in the Q direction to move in that direction. On the contrary, when the motor 617 rotates in the opposite direction and the worm wheel 615 is rotated in the direction of the arrow M, the support shaft 618 moves in the direction of the arrow P, and the external heating belt unit 600 acts on the external heating belt unit 600 in the F direction. Move in that direction.

In the external heating belt unit 600, a sensor unit 620 which is a position detecting means for detecting the end position of the external heating belt 610 is provided at a position on the left side (front side) of the external heating belt 610. The control unit 607 detects the end position (moving position toward the belt) of the external heating belt 610 by the sensor unit 620, and uses the end position of the external heating belt 610 for compensation control.

Further, the sensor unit 620 is the same as that of the first or second embodiment described above. By this repetitive operation, the external heating belt 610 in the external heating belt unit 600 can be reciprocated within a predetermined range.

100 fixing device, 105 fixing belt, 120 pressure belt, 121 pressure roll,
122 tension roll, 125 pressure pad, 131 drive roll,
131a shaft, 132 steering roll, 132a shaft,
137 pad stay, 140 upper plate, 150 sensor part,
150c sensor flag, 150d sensor arm, 150e sensor spring,
150f axis, 150h axis, 150i connection mechanism, 150j third sensor,
151 pin, 152 worm wheel,
154 Steering roll support arm, 155 stepping motor,
156 tension springs, 157 worms, 158 bearings, 160 shafts,
161 fork plate, 161a U-shaped groove, 170 IH heater,
A upper belt assembly, B lower belt assembly, C lower belt unit,
G drive input gear, N fixing nip, S sheet, t unfixed toner image

Claims (2)

The first and second rotating bodies 105 and 120, wherein at least one of the toner images t on the recording material S is fixed by the nip portion N as an endless belt, and the like.
The position detecting means 150 for detecting the position of the endless belts 105 and 120 in the width direction, and
Steering means 132 capable of moving the endless belts 105 and 120 to one end side and the other end side in the width direction, and
In the fixing device 100 having a control means for controlling the steering means 132,
The control means has the width direction of the endless belts 105 and 120 detected by the position detecting means 132 in order to cancel the fluctuation between the position and the target position in the width direction of the endless belts 105 and 120 detected by the position detecting means 150. In the width direction of the endless belts 105 and 120, the control amount of the steering means 150 is adjusted based on the difference from the position in the width direction of the endless belts 105 and 120 to the target position. A fixing device 100 characterized by reducing the difference between a position, a target position, and a target position. The fixing device according to claim 1, wherein the position detecting means 150 is an optical sensor whose output signal changes according to the position of the endless belts 105 and 120 in the width direction.