JP2016114856A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove a sheet jammed between a heating unit 110 of a fixing device 100 and a separation body 116 opposite to the heating unit 110.SOLUTION: A fixing device 100 includes: a fixing roller pair 101 that holds a sheet on which a toner image is formed and conveys, while rotating to heat, the sheet to fix the toner image to the sheet; a separation body 116 that is arranged to be capable of approaching/separating from the peripheral surface of the heating unit 110 of the fixing roller pair 101 to guide a sheet passing through the fixing roller pair 101 to be separated from the heating unit 110; and a control part that, when abnormality in conveyance has occurred to the sheet to which the toner image is fixed while being conveyed by the fixing roller pair 101, detects the abnormality in conveyance and separates the separation body 116 from the fixing roller pair 101.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fixing device that fixes a toner image on a sheet, and an image forming apparatus including the fixing device in a main body of the apparatus.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copying machines, laser printers, and facsimiles using an electrophotographic process form a toner image on a sheet by an image forming unit, and fix the toner image on the sheet by a fixing device. . The fixing device is configured to fix the toner image on the sheet by sandwiching the sheet on which the toner image is formed with a pair of fixing rollers as a fixing rotating body pair, heating and conveying the sheet while rotating.

  However, when the sheet is heated, the toner of the toner image is somewhat dissolved, and the surface of the sheet on which the toner image is formed contacts a roller (hereinafter simply referred to as a roller) that is in contact with the toner image of the fixing roller pair. May stick. When these phenomena occur, the sheet causes sheet jamming. For this reason, there is a fixing device including a separator that separates the sheet from the roller and prevents the sheet from adhering to the roller (Patent Document 1). A slight gap is formed between the separator and the roller so that the separator does not contact the roller.

JP 2012-133201 A

  However, even if a conventional fixing device is provided with a separator, the sheet may stick to the roller and clog the gap between the separator and the roller. In this case, the user must remove the jammed sheet. However, when the sheet is removed from the gap between the separator and the roller, the roller may be damaged. In particular, when the roller is not a thick metal roller but a thin film-like fixing film is provided, the fixing film may be torn.

  The present invention removes a sheet without damaging the rotating member when the sheet is jammed between one rotating member of a fixing rotating member pair that fixes a toner image on the sheet and a separating member facing the rotating member. Another object of the present invention is to provide a fixing device that can be used, and an image forming apparatus including the fixing device.

  The fixing device according to the present invention includes a fixing rotator pair that fixes a toner image on the sheet by nipping and heating the sheet on which the toner image is formed, and separating the guided sheet from the fixing rotator pair. And when the conveyance abnormal state occurs in the sheet that is conveyed by fixing the toner image between the fixing rotating member pair and the fixing rotating member pair, and detecting the conveyance abnormal state and separating the separating member from the fixing rotating member pair Means.

  An image forming apparatus according to the present invention includes an image forming unit that forms a toner image on a sheet, and the fixing device that fixes the toner image on the sheet.

  In the fixing device of the present invention, when the detection unit detects an abnormal conveyance state of the sheet being fixed, it is assumed that the sheet is in an abnormal conveyance state. The sheet can be easily removed without damaging the body.

  In addition, the image forming apparatus of the present invention includes a fixing device that is less likely to be damaged when removing a sheet in an abnormal conveyance state, and thus can be used for a long time.

FIG. 3 is a cross-sectional view of the image forming apparatus according to the embodiment of the present invention along the sheet conveying direction. FIG. 3 is a schematic cross-sectional view perpendicular to the sheet conveying direction of the fixing device according to the embodiment of the present invention. It is a figure for operation | movement description of a isolation | separation body. (A) is a figure in which the separator is in a normal position. (B) is a diagram in which the sheet is jammed (the sheet is in an abnormal conveyance state) and the separator is separated from the heating unit. It is a fixing film behavior explanatory view at the time of jam processing. It is a figure of a clearance adjustment mechanism, and is a figure seen from the edge part side of a fixing roller pair. (A) is EE arrow sectional drawing of FIG. (B) is a perspective view of the edge part of the moving member of a separation body. (C) is FF arrow sectional drawing of FIG. 5 (A). FIG. 6 is a diagram illustrating a state in which a fixing film is slackened when a sheet is removed. FIG. 3 is a perspective view of a fixing device showing a pressure release unit. FIG. 8 is a left side view of FIG. 7. It is a control block diagram.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention and a fixing device provided in the image forming apparatus will be described with reference to the drawings.

(Image forming device)
FIG. 1 is a cross-sectional view of the image forming apparatus 10 according to the embodiment of the present invention along the sheet conveyance direction.

  The image forming apparatus 10 converts, for example, image information from the document reading unit 24 or an external computer (not shown) into light modulation information by the laser emission writing unit 11. The laser emission writing unit 11 emits light modulation information to the rotating photosensitive drum 18 to form image information on the photosensitive drum 18 as an electrostatic latent image. The electrostatic latent image is visualized into a toner image by the developer (toner) from the toner bottle unit 16.

  On the other hand, a main paper feeding unit 12 that feeds the sheet P in the direction of arrow A is disposed below the apparatus main body 10a of the image forming apparatus. A box-shaped stacking cassette portion 7 constituting the main sheet feeding unit 12 is detachably attached to the apparatus main body 10a so that sheets are stored in a stacked manner. The sheet is stacked on the middle support plate 6 and pushed upward by the paper feed pressure spring 4. A paper feed roller 5 is provided at the feed outlet of the stacking cassette unit 7.

  When feeding the sheets, the main sheet feeding unit 12 pushes up the stacked sheets by the intermediate support plate 6, presses the uppermost sheet against the sheet feeding roller 5, and feeds the uppermost sheet to the sheet feeding roller 5. Is fed in the direction of arrow A and sent out to the paper feed passage 14.

  On the other hand, on the right side of the main sheet feeding unit 12, a multi-sheet feeding unit 30 is provided that can stack sheets different in size from the sheets stored in the stacking cassette unit 7 so as to be fed. The multi paper feed unit 30 includes a multi paper feed stacking tray 30a capable of opening and closing the apparatus main body 10a, a multi paper feed roller 30b, and the like. The multi paper feed unit 30 is configured to feed a sheet placed on the multi paper feed stacking tray 30a with the apparatus main body 10a opened to the paper feed path 14 side by a multi paper feed roller 30b.

  The sheet P fed from either the main sheet feeding unit 12 or the multi-sheet feeding unit 30 hits the nip between a pair of registration rollers 15a and 15b provided in the sheet feeding path 14 and stopped rotating. Hit. Thereafter, the sheet is fed between the photosensitive drum 18 and the transfer roller 17 by rotation of the pair of registration rollers 15a and 15b at an appropriate timing. A transfer bias is applied to the transfer roller 17. The above-described toner image formed on the photosensitive drum 18 is electrostatically transferred to the sheet by a transfer bias, and is conveyed to the fixing device 100 on the downstream side of the photosensitive drum 18. The photosensitive drum 18 and the transfer roller 17 form an image forming unit 25.

  The fixing device 100 includes a heating unit 110 and a pressure roller 120 that contacts the heating unit 110. The sheet is pressed and heated at the nip between the heating unit 110 and the pressure roller 120 to fix the toner image. Finally, the sheet is conveyed through the paper discharge path 20 and is discharged from the paper discharge roller 21 to the in-body discharge tray 23.

(Fixing device)
FIG. 2 is a schematic cross-sectional view perpendicular to the sheet conveying direction of the fixing device 100 according to the embodiment of the present invention. FIG. 3 is a diagram for explaining the operation of the separator 116. FIG. 3A is a diagram in which the separator 116 is in a normal position. FIG. 3B is a diagram in which the sheet is jammed (the sheet is in an abnormal conveyance state), and the separator 116 is separated from the heating unit 110. In FIG. 3, the pressure roller 120 bites into the heating unit 110. This is to emphasize that the pressure roller 120 and the heating unit 110 are pressed against each other. Actually, as shown in FIG. 2, the pressure roller 120 is slightly elastically deformed, as shown in FIG. I won't bite into it.

  The fixing device 100 includes a pair of fixing rollers 101 as a pair of fixing rotators, a conveyance guide 115, a separator 116, an exit sensor S2, a retracting operation unit 102 as a retracting unit, and the like.

  The fixing roller pair 101 sandwiches a sheet on which a toner image is formed, conveys the sheet while heating and rotating it, and fixes the toner image on the sheet. The fixing roller pair 101 includes a heating unit 110 as a rotating body that comes into contact with the toner image, and a pressure roller 120.

  The heating unit 110 is formed in a bowl shape in cross section, and is fixed to a heater holding member 112 having heat resistance and rigidity, and a concave groove 119 formed on a surface of the heater holding member 112 facing the pressure roller 120. And a thin heater (ceramic heater) 113 having a low heat capacity. The heating unit 110 also includes a fixing stay 114 having a U-shaped cross section provided in the heater holding member 112 and a cylindrical fixing film 111 loosely mounted on the outer periphery of the heater holding member 112. The fixing stay 114 has a U-shaped opening facing the heater 113 side.

  The pressure roller 120 includes a shaft 121 and an elastic cylinder 122 made of a cylindrical heat-resistant elastic material concentrically and integrally provided on the outer periphery of the shaft 121. On the outer periphery of the elastic cylinder 122, a release film 123 made of fluororesin such as PFA, PTFE, FEP and the like having excellent releasability is formed. The pressure roller 120 is rotatably supported on the frame 100A by supporting both ends of the shaft 121 on bearings (not shown) provided on the frame 100A (FIG. 8) of the fixing device. The pressure roller 120 is rotated when the shaft 121 is rotated by the drive motor M.

  The heating unit 110 and the pressure roller 120 are arranged in parallel. The heating unit 110 urges both ends of the fixing stay 114 toward the pressure roller 120 by a pressure urging mechanism (not shown), and presses the heater 113 against the pressure roller 120 via the fixing film 111. I am letting. As a result, a nip N is formed between the heating unit 110 and the pressure roller 120.

  The pressure roller 120 is rotated in the direction of arrow C by the drive motor M. Then, the fixing film 111 in pressure contact with the pressure roller 120 rotates following the arrow D direction with the heater holding member 112 as a guide. At this time, when the sheet is sandwiched in the nip N, the toner image is fixed to the sheet by the heating of the heater 113 and the pressure contact pressure between the heating unit 110 and the pressure roller 120. In general, the sheet P is conveyed with the surface Pa on which the toner image is formed facing the heating unit 110.

  The separating body 116 is formed by an integral moving member 116A and a guide plate 116B. The separator 116 is disposed so as to be able to approach and separate from the rotating body that contacts the toner image and the peripheral surface of the heating unit 110 as a heating rotating body, and separates and guides the sheet passing through the nip N from the heating unit 110. It has become. That is, the separator 116 is disposed on the downstream side of the pair of fixing rollers 101 in order to prevent the sheet having the toner image fixed at the nip N from being wound around the fixing film 111 and causing the sheet to be jammed. .

  The fixing film 111 is formed of a film member in a cylindrical shape. For this reason, when the fixing film 111 is guided by the heater holding member 112 and is driven to rotate by the pressure roller 120, the portion downstream from the nip N tends to be loosened, and is driven so as to float from the heater holding member 112. May rotate. In order to prevent the separator 116 from coming into contact with the fixing film 111 and tearing the fixing film 111, a gap G is formed between the tip 116 c and the peripheral surface 111 a of the fixing film 111. However, if the gap G is too wide, the separator 116 cannot prevent the sheet from being wound around the fixing film 111.

  Therefore, the gap G is an optimum gap G that prevents the separator 116 from coming into contact with the fixing film 111 and prevents the sheet from being wound around the fixing film 111, and a gap adjusting mechanism 140 (see FIG. 4). , FIG. 5).

  FIG. 4 is a view of the gap adjusting mechanism 140 as seen from the end side of the fixing roller pair. FIG. 5A is a cross-sectional view taken along the line E-E in FIG. FIG. 5B is a perspective view of the end of the moving member of the separator. FIG. 5C is a cross-sectional view taken along the line FF in FIG.

  The gap adjusting mechanism 140 is located at both ends of the fixing roller pair 101. The gap adjusting mechanism 140 located at one end will be described, and the description of the gap adjusting mechanism 140 located at the other end will be omitted.

  A fixing film flange 143 provided on the frame 100A (FIG. 8) of the fixing device is located at the end of the fixing roller pair 101. A slope 143 b is formed on the fixing film flange 143. Further, a clearance adjusting screw 141 is provided on the fixing film flange 143 so that the position thereof can be adjusted in the directions of arrows J and K. The gap adjusting piece 142 is in contact with the slope 143b.

  The end of the separator 116 is engaged with the gap adjusting piece 142. The end of the separator 116 (FIG. 5B) is formed in an L shape by a guide piece 116d and a receiving piece 116e. A guide groove 143a into which the guide piece 116d enters is formed in the fixing film flange 143 (FIG. 5C).

  In the separator 116, the guide piece 116 e is inserted into the guide groove 143 a of the fixing film flange 143. A clearance adjustment piece 142 is provided on the receiving piece 116e by a bolt 146. The gap adjusting piece 142 is supported by the concave portion 142 a across the slope 143 b of the fixing film flange 143. A tension spring 144 is provided between the separator 116 and a fixing member (not shown). Accordingly, the separator 116 is urged toward the fixing film flange 143 and is supported by the fixing film flange 143.

  The adjustment operation of the gap G by the gap adjustment mechanism 140 will be described.

  The clearance adjustment screw 141 is screwed in the left direction (J direction) in FIG. Then, the gap adjusting screw 141 pushes the gap adjusting piece 142 leftward at the tip. The gap adjusting piece 142 is pushed by the gap adjusting screw 141 and moves in the direction of the arrow J and the direction of the arrow Q (upwardly to the left) while climbing the slope 143b.

  While moving in the arrow Q direction, the gap adjustment piece 142 pushes up the receiving piece 116e of the separator 116 and moves the separator 116 in the Q direction against the tension spring 144. As a result, the gap G between the tip 116c of the separator 116 and the peripheral surface 111a of the fixing film 111 is widened.

  When the clearance adjusting screw 141 rotates in the reverse direction, the clearance adjusting screw 141 moves in the right direction (K direction) in FIG. Separator 116 is pulled in the direction of arrow R by tension spring 144. The tension spring 144 presses the gap adjusting piece 142 with the receiving piece 116e of the separator 116, slides the gap adjusting piece 142 along the inclined surface 143b, and moves the gap adjusting piece 142 to the right (K direction). Accordingly, the separating body 116 is pulled by the tension spring 144 and moves in the R direction approaching the fixing roller pair 101. As a result, the gap G between the tip 116c of the separator 116 and the peripheral surface 111a of the fixing film 111 is narrowed.

  In this manner, the gap adjusting mechanism 140 separates the sheet from the fixing film 111 through the gap G between the leading end 116c of the separator and the peripheral surface 111a of the fixing film, depending on the rotation direction of the gap adjusting screw 141 by the user's operation. It can be adjusted to the most suitable gap. Incidentally, the optimum gap is about 0.2 mm. This numerical value is a reference numerical value and is not a numerical value that limits the present invention.

  By the way, when the surface on which the toner image is formed comes into contact with the fixing film 111 and passes through the nip N of the fixing roller pair 101, the sheet is separated from the fixing film and guided to the separator 116 due to the rigidity of the sheet itself. And conveyed downstream. However, if the sheet is curled or the toner image is formed close to the leading edge of the sheet, the timing of separating from the fixing film 111 may be delayed or may not be separated.

  In such a case, even if the gap G is adjusted to the optimum gap by the gap adjusting mechanism 140, the sheet may be jammed or intrude into the gap G. When such a situation occurs, it is necessary to stop the conveyance of the sheet and remove the sheet. Further, when the sheet is removed, the fixing film 111 may be pulled by the sheet and loosen as shown by a broken line in FIG. 6 to come into contact with the front end 116c of the separator 116 and be damaged. FIG. 6 is a diagram illustrating a state in which the fixing film 111 is loosened when the sheet is removed.

  Therefore, it is necessary to widen the gap G. For this reason, the fixing device 100 of the present embodiment separates the separator 116 from the heating unit 110 when the exit sensor S2 provided on the downstream side of the fixing roller pair 101 does not detect a sheet even after a predetermined time has elapsed. The retraction operation unit 102 that widens the gap G is provided.

  The retreat operation unit 102 includes a plunger 103 as an operation unit that separates the separator 116 from the heating unit 110, a CPU 104 that operates the plunger 103 when the outlet sensor S2 does not detect the sheet for a predetermined time, and the like. The exit sensor S2 is arranged on the downstream side in the sheet conveyance direction B from the position where the separator 116 and the heating unit 110 are opposed to each other, and detects the sheet passing through the fixing roller pair 101. The entrance sensor S1 is arranged on the upstream side of the fixing roller pair 101, and detects the leading edge of the sheet P conveyed to the fixing device 100 from the image forming unit 25 (FIG. 1). The CPU 104 and the exit sensor S2 as detection means constitute a control unit (control means) 107.

  An operation in which the retracting operation unit 102 moves the separator 116 away from the heating unit 110 to the retracted position will be described.

  When the sheet is conveyed from the image forming unit 25 (FIG. 1) to the fixing device 100, the entrance sensor S1 detects the leading edge of the sheet. Then, the counter 105 of the CPU 104 in FIG. 9 starts counting time. At this time, since the drive motor M is already rotating and the pressure roller 120 and the fixing film 111 are rotating, the fixing roller pair 101 conveys the sheet while heating and pressing.

  The leading edge of the sheet that has passed through the fixing device 100 is detected by the entrance sensor S1. At this time, the CPU 104 causes the counter 105 to start counting time. Then, if the exit sensor S2 detects the sheet within a predetermined time set in advance, the CPU 104 determines that the sheet is not jammed, and performs heating, pressurization, and conveyance of the sheet by the fixing roller pair 101. Continue (FIG. 3A).

  However, when the exit sensor S2 does not detect the sheet for a predetermined time, the CPU 104 determines that the sheet is jammed in the fixing device 100, stops the rotation of the drive motor M, and then reverses the rotation, and the plunger 103 Is activated. The reason why the drive motor M is reversely rotated will be described in the explanation of the operation of the pressure release unit 130.

  The plunger 103 moves the separator 116 away from the fixing film 111 against the tension spring 144 and retracts it to the retracted position via the operation link 106 that rotates about the fulcrum 106a. The gap G widens as shown in FIG.

  In this way, the gap G widens, so that the user can easily remove the sheet jammed in the gap G. Further, as shown in FIG. 3B, when the sheet is removed due to the gap G being widened, the fixing film 111 does not come into contact with the separator 116 even if the fixing film 111 is loosened as shown in FIG. . For this reason, it is possible to prevent the fixing film 111 from being damaged.

  When the sheet jam is released, the operation of the plunger 103 is released, the separating body 116 is pulled by the tension spring 144 and returns to the original position, and the gap automatically becomes the original gap.

  By the way, when the sheet jammed in the fixing device 100 is removed as described above, the heating unit 110 and the pressure roller 120 are separated from each other, and the nip N is released when the heating unit 110 and the pressure roller are released. It is easy to remove the sheet from between 120.

  Therefore, in the fixing device 100 of the present invention, when the exit sensor S2 does not detect the sheet for a predetermined time, the pressure release unit 130 (see FIG. 5) as a pressure release unit that separates the heating unit 110 and the pressure roller 120 (rotators) from each other. 7 and FIG. 8).

  FIG. 7 is a perspective view of the fixing device 100 showing the pressure release unit 130. 8 is a left side view of FIG.

  The pressure release unit 130 includes a drive motor M, a gear train 135 rotated by the drive motor M, a pressure release cam 133, and the like. The gear train 135 includes a drive gear 136, a pressure contact release gear 131, an idler gear 132, and a driven gear 137 that are sequentially meshed with each other. A one-way clutch 125 is provided between the pressure release gear 131 and the release gear shaft 124. Further, the release gear shaft 124 is integrally provided with a pressure release cam 133. Further, a one-way clutch 126 is also provided between the driven gear 137 and the shaft 121 of the pressure roller 120. The idler gear 132 is formed by an integral large-diameter gear 132a and a small-diameter gear 132b. The large diameter gear 132a meshes with the pressure release gear 131. The small-diameter gear 132b meshes with the driven gear 137.

  When the fixing roller pair 101 of the fixing device 100 is conveying a sheet, the pressure release gear 131 is rotated clockwise in FIG. 8 by the drive motor M, the idler gear 132 is rotated counterclockwise, and the driven gear 137 is rotated clockwise. At this time, the rotation of the pressure release gear 131 is not transmitted to the release gear shaft 124 by the one-way clutch 125. However, the rotation of the driven gear 137 is transmitted to the pressure roller shaft 121 by the one-way clutch 126. As a result, in FIG. 2, the pressure roller 120 rotates to the right (rotates in the direction of arrow C), the fixing film 111 rotates to the left (rotates in the direction of arrow D), and the fixing roller pair 101 conveys the sheet. Yes.

  When the CPU 104 determines that the sheet is jammed in the fixing device 100, the CPU 104 stops the rotation of the drive motor M and reverses the rotation. Then, the pressure release gear 131 rotates counterclockwise in FIG. 8, the idler gear 132 rotates clockwise, and the driven gear 137 rotates counterclockwise. In this case, the rotation of the pressure release gear 131 is transmitted to the release gear shaft 124 by the one-way clutch 125. However, the rotation of the driven gear 137 is not transmitted to the pressure roller shaft 121 by the one-way clutch 126. As a result, in FIG. 2, the rotation of the pressure roller 120 to the right (rotation in the direction of arrow C) stops and the rotation of the fixing film 111 to the left (rotation in the direction of arrow D) also stops. Stop conveyance.

  However, since the release gear shaft 124 receives the rotation of the pressure contact release gear 131 counterclockwise by the one-way clutch 125, the pressure contact release cam 133 integrated with the release gear shaft 124 also rotates counterclockwise. The pressure release cam 133 presses the pressure plate 134 to the left in FIG. 8 against a spring (not shown) while rotating counterclockwise. Since the pressure plate 134 is engaged with the frame 100A of the fixing device 100 so that the lower end portion 134a can be tilted, the pressure plate 134 is inclined leftward with the lower end portion 134a as a center. For this reason, the pressure plate 134 presses the heating unit 110 to the right so far and releases the state where the heating unit 110 is pressed against the pressure roller 120.

  As a result, the pressure contact between the heating unit 110 and the pressure roller 120 is released, and the jammed sheet can be removed from between the heating unit 110 and the pressure roller 120 without damaging the fixing film 111. .

  Further, a sheet guide surface 116f (FIG. 3A) of the separator 116 is formed substantially along the sheet conveying direction B. For this reason, when the jammed sheet is removed from between the heating unit 110 and the pressure roller 120, the jammed sheet can be easily removed while being guided by the sheet guide surface 116f.

  In the above description, since the image forming apparatus 10 includes the fixing device 100 that is less likely to be damaged when removing a jammed sheet, it can be used for a long time.

  In the above description, the plunger 103 is used to separate the separator 116 from the heating unit 110. However, a rack and pinion, an eccentric cam, or the like may be used instead of the plunger 103. Therefore, the operating part is not limited to the plunger 103.

  Further, the pair of fixing rollers in the above description includes a heating unit 110 having a fixing film 111 and a pressure roller 120. However, instead of the heating unit 110, a cylindrical roller having a heater inside may be used. Therefore, the heating rotator is not limited to the heating unit.

  Further, the sheet is configured such that the surface on which the toner image is formed is in contact with the heating unit 110 having a heater, but may be in contact with the pressure roller 120. In addition, in a fixing roller pair including a cylindrical roller having a heater inside and a pressure roller, the surface on which the toner image is formed may be in contact with the pressure roller. Thus, the sheet may be positioned on the opposite side without positioning the surface on which the toner image is formed on the side where the heater is present. Accordingly, the rotating body that contacts the toner image may be a pressure roller, not a cylindrical roller having a heating unit or a heater, and is not limited to a cylindrical roller having a heating unit or a heater. .

  DESCRIPTION OF SYMBOLS 100: Fixing apparatus, 101: Fixing roller pair (fixing rotary body pair), 102: Retraction operation part (retraction means), 103: Plunger (operation part), 104: CPU (control part), 105: Counter, 107: Control (Control means), 110: heating unit (rotating body, heating rotating body), 111: fixing film, 111a: peripheral surface, 113: heater, 114: fixing stay, 115: transport guide, 116: separation body, 116A: Moving member, 116B: guide plate, 116c: tip of the separating body, 116e: receiving piece, 116f: sheet guide surface, 120: pressure roller, 121: shaft of the pressure roller, 130: pressure contact release unit (pressure contact release means) 133: Pressure contact release cam, 134: Pressure plate, 135: Gear train, 140: Gap adjustment mechanism (gap adjustment means), 141: Gap adjustment screw, 142: Gap adjustment piece 144: tension spring, B: a sheet conveying direction, G: gap, M: drive motor, N: fixing roller pair nip, P: sheet, S1: inlet sensor, S2: exit sensor.

Claims (7)

A pair of fixing rotators for fixing the toner image on the sheet by nipping and heating the sheet on which the toner image is formed;
A separator for separating and guiding the fixed sheet from the fixing rotating body pair;
Control means for detecting an abnormal conveyance state and separating the separating member from the fixing rotary member pair when an abnormal conveyance state occurs in the sheet on which the fixing rotary member fixes and conveys a toner image; With
A fixing device. An operating portion for separating the separating member from the fixing rotating member pair;
The fixing device according to claim 1. A gap adjusting means for adjusting the gap between the separating body and the fixing rotating body pair by moving the separating body close to and away from the fixing rotating body pair;
The fixing device according to claim 1, wherein When the control unit detects an abnormal conveyance state of the sheet, the control unit includes a pressure release unit that separates the rotating members of the fixing rotating member pair.
The fixing device according to any one of claims 1 to 3, wherein The one rotating body of the fixing rotating body pair is a heating rotating body that heats the sheet.
The fixing device according to claim 4. The separator has a sheet guide surface for guiding a sheet in a sheet conveyance direction by the fixing rotating body pair.
The fixing device according to claim 1, wherein An image forming unit for forming a toner image on a sheet;
A fixing device according to any one of claims 1 to 6, which fixes a toner image on a sheet.
An image forming apparatus.

Images