JP2008076908A - Fixing device and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of preventing the occurrence of an image defect caused by the shaving of a heating roller and the lowering of the durability of the heating roller due to contact of an excessive temperature-rise preventing member without causing response delay of the excessive temperature-rise preventing member. <P>SOLUTION: The fixing device 4 is equipped with the heating roller 28 heated by a halogen heater (heat source) 36 arranged inside, and the excessive temperature-rise preventing member 37 abutting on the outer surface of the heating roller 28 and interrupting the application of power to the halogen heater 36 when temperature excessively rises. In the fixing device 4, a cylindrical film 41 is interposed between the heating roller 28 and the excessive temperature-rise preventing member 37, and is submissively rotated with the rotation of the heating roller 28. The cylindrical film 41 is composed of fluororesin having high sliding property or the surface of the cylindrical film 41 is coated with fluororesin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing device for fixing a toner image transferred to a transfer material and an image forming apparatus including the same.

  2. Description of the Related Art Image forming apparatuses such as copying machines, printers, and facsimile machines that employ an electrophotographic system are provided with a fixing device for fixing a toner image transferred onto a transfer material such as paper.

  This type of fixing device includes a heating roller that is heated by a heat source disposed therein, and the surface temperature of the heating roller is controlled to an optimum value for fixing. Specifically, the surface temperature of the heating roller is detected by a temperature detection means such as a thermistor, and the current supply to the heat source is feedback-controlled by the control means based on the surface temperature of the heating roller detected by the temperature detection means. The roller surface temperature is maintained at an optimum value for fixing.

  By the way, in the fixing device, since the current supply to the heat source is not properly controlled due to a malfunction of the control means or the like, the heating roller may reach an excessive temperature rise state. A temperature rise prevention means is provided. This excessive temperature rise prevention means cuts off the power supply to the heat source when the heating roller reaches an excessive temperature rise state. This is because the surface temperature of the heating roller reaches a predetermined temperature and cuts off the power supply to the heat source. It is required that the thermal response time until the time is short.

Therefore, Patent Document 1 proposes that an excessive temperature rise prevention member is brought into contact with and pressed by a heating roller to shorten the thermal response time so that no response delay occurs.
Japanese Patent Laid-Open No. 5-107963

  By the way, the contact-type excessive temperature rise prevention member that directly contacts the heating roller as described in Patent Document 1 is made of a metal such as aluminum having high thermal conductivity so that the temperature can be detected quickly. Yes. In addition, the base tube of the heating roller is made of a metal such as aluminum in consideration of heat transfer, and the surface of the base tube that comes into contact with the image surface is highly slidable such as PTFE or PFA. A release layer made of a fluororesin is formed.

  Therefore, in the configuration in which the excessive temperature rise prevention member is in direct contact with the heating roller as in Patent Document 1, the release layer of the portion of the heating roller that contacts the excessive temperature rise prevention member is shaved and image defects such as uneven gloss occur. There is a problem of doing.

  In addition, as described above, when the release layer on the surface of the heating roller is scraped, the cored bar is exposed, and a problem arises in that abnormal noise is generated due to rubbing between metals such as aluminum.

  The present invention has been made in view of the above problems, and the object of the present invention is to prevent image defects due to scraping of the heating roller due to contact with the excessive temperature rise prevention member without incurring a response delay of the excessive temperature rise prevention member. It is an object of the present invention to provide a fixing device that can prevent generation and a decrease in durability of the heating roller, and an image forming apparatus including the fixing device.

  In order to achieve the above object, the invention described in claim 1 is a heating roller that is heated by a heat source disposed therein, and shuts off energization to the heat source in contact with the outer surface of the heating roller and overheating. A fixing device including an over-temperature prevention member that sandwiches a cylindrical film between the heating roller and the over-temperature prevention member, and the cylindrical film is driven to rotate as the heating roller rotates. Features.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the cylindrical film is made of a fluorine resin having a high sliding property, or the surface of the cylindrical film is coated with a fluorine resin. To do.

  A third aspect of the invention is characterized in that, in the first or second aspect of the invention, the cylindrical film is made of a thermoplastic resin that melts or softens when the temperature rises excessively.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, a guide member for assisting the driven rotation of the cylindrical film is provided.

  According to a fifth aspect of the present invention, there is provided an image carrier for forming a latent image, developing means for developing the latent image formed on the image carrier as a toner image, and a toner image on the image carrier as a transfer material. 5. An image forming apparatus comprising: a transfer unit that transfers the toner image; and a fixing unit that heats and pressurizes the toner image transferred onto the transfer material by the transfer unit. It is characterized by comprising the above fixing device.

  According to the first aspect of the present invention, since the cylindrical film is interposed between the heating roller and the overheating prevention member, direct contact of the overheating prevention member with the heating roller is avoided, and the overheating prevention member This prevents the surface of the heating roller from being scraped. For this reason, generation | occurrence | production of the image defect resulting from the abrasion of a heating roller by contact of an excessive temperature rise prevention member, and the durable fall of a heating roller are prevented. Further, since only a thin cylindrical film having a small heat capacity is interposed between the heating roller and the excessive temperature rise prevention member, the heat transfer to the excessive temperature rise prevention member is hardly hindered by the cylindrical film. The overheat prevention member has a high thermal responsiveness and a short thermal response time. When the temperature rises excessively, the energization to the heat source is interrupted without delay in response, and the occurrence of problems such as smoke and ignition is ensured. It is prevented.

  According to the second aspect of the present invention, the cylindrical film is made of a highly slidable fluororesin or the surface of the cylindrical film is coated with the fluororesin. The generated frictional force can be suppressed to a small level, and the surface of the heating roller can be more reliably prevented from being scraped by the excessive temperature rise prevention member.

  According to the third aspect of the present invention, the cylindrical film melts or softens at the time of excessive temperature rise, and the excessive temperature rise prevention member comes into contact with or approaches the heating roller to quickly receive heat from the heating roller. The time is further shortened, and energization to the heat source is interrupted without delay in response.

  According to the fourth aspect of the present invention, the driven rotation of the cylindrical film is smoothly performed with the assistance of the guide member. Therefore, the cylindrical film is uniformly distributed over the entire circumference of the heating roller and the overheat prevention member. The durability of the contact is increased.

  According to the invention described in claim 5, in the image forming apparatus including the fixing device, the effects of the invention described in claims 1-4 can be obtained, and the toner image transferred onto the transfer material can be stably fixed. It is possible to obtain a high quality image.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Image forming apparatus]
FIG. 1 is a front sectional view of a laser beam printer 1 as an embodiment of an image forming apparatus according to the present invention. The laser beam printer 1 is a transfer material along a conveyance path L provided in the apparatus main body 1a. An image is formed on a sheet based on image data transmitted from a terminal (not shown) while a certain sheet is conveyed, and the conveyance path L passes through the apparatus main body 1a from the front to the rear (in FIG. 1). A horizontal portion L1 extending substantially horizontally (from right to left) and a vertical portion L2 rising substantially vertically from the end of the horizontal portion L1 are formed in a substantially L shape in side view.

  Further, the laser beam printer 1 includes a paper feeding unit 2 provided at a lower portion of the apparatus main body 1a, an image forming unit 3 provided at a substantially central portion in the apparatus main body 1a above the paper feeding unit 2, The fixing device 4 disposed behind the image forming unit 3, the concave paper discharge unit 5 provided on the upper surface of the apparatus main body 1 a above the fixing device 4, the horizontal part L 1 of the transport path L and the paper feed A switchback portion 6 provided between the cassette 7 and the cassette 7 is provided.

  The paper feed unit 2 stores paper and feeds the paper toward the image forming unit 3 and includes the paper feed cassette 7 and the manual feed tray 8.

  Here, the paper feed cassette 7 has a rectangular box shape with an open upper surface, and fulfills the function of feeding sheets (not shown) stacked and accommodated therein one by one. As shown, in the state where it is mounted in the apparatus main body 1a, it is located below the horizontal portion L1 of the transport path L as shown.

  The paper feed cassette 7 includes a lift plate 9 that contacts and separates from the inner bottom surface, a lift plate 10 that moves up and down in conjunction with the contact and separation operation of the lift plate 9, and a front end of the lift plate 9 (paper feeding direction). A lift drive shaft 11 that is attached in the vicinity of the downstream end) and rotates the lift plate 9 in the direction of the arrow in FIG. 1 and a shaft that can rotate in the vicinity of the rear end (upstream end in the sheet feeding direction) of the lift plate 10. A supporting shaft 12 is provided.

  Further, the paper feed unit 2 includes a pickup roller 13 that takes out the paper in the paper feed cassette 7 one by one, a feed roller 14 that sends out the taken paper to the horizontal part L1 of the transport path L, a retard roller 15, and a plurality of rollers. Pick-up rollers 16, 17, and 18, and a pickup that picks up the paper placed on the manual feed tray 8 in addition to the registration rollers 19 that supply the image forming unit 3 to the image forming unit 3 at a predetermined timing after temporarily waiting the fed paper. A roller 20 is provided.

  The image forming unit 3 forms an image on a sheet supplied from the sheet feeding unit 2, and is an image carrier that is rotatably disposed at a substantially central portion in the front-rear direction of the horizontal portion L 1 of the transport path L. Photosensitive drum 21, a primary charger 22 disposed around the photosensitive drum 21, a developing device 23 serving as a developing unit, a transfer roller 24 serving as a transfer unit, and a cleaning device 25, and a laser scanner unit (LSU) disposed above them. ) 26, a toner hopper 27, and the like.

  The fixing device 4 is for fixing the toner image transferred onto the paper in the image forming unit 3 to the paper, and the details of the configuration will be described later.

  Further, the paper discharge unit 5 is for discharging the paper on which the toner image has been fixed in the fixing device 4 to the outside of the main body 1a, and is provided in the middle of the vertical portion L2 of the transport path L. And a paper discharge roller 31 provided at the end of the vertical portion L2 and a paper discharge tray 32 for stacking paper discharged outside the apparatus main body 1a.

  The switchback unit 6 is used when an image is formed on both sides of a sheet. The switchback unit 6 is provided at another position on another conveyance path L ′ disposed below the vertical portion L1 of the conveyance path L and its proper position. A plurality of transport rollers 33 are provided.

  Next, an image forming operation of the laser beam printer 1 having the above configuration will be described.

  For example, when a print start signal is transmitted to the laser beam printer 1 from a terminal such as a personal computer (personal computer), in the image forming unit 3, the photosensitive drum 21 is driven in the direction indicated by the arrow (clockwise) in FIG. ) And the surface thereof is uniformly charged to a predetermined potential by the primary charger 22. When a laser beam based on the image data transmitted from the terminal is output from the laser scanner unit 26 and irradiated onto the photosensitive drum 21, an electrostatic latent image is formed on the photosensitive drum 21. Then, the electrostatic latent image on the photosensitive drum 21 is developed by the developing device 23 using toner as a developer to be visualized as a toner image.

  At the same time, in the paper feeding unit 5, for example, the sheets stored in the paper feeding cassette 7 are picked up one by one from the uppermost one by the pickup roller 13, and the feed roller 14, the retard roller 15, and the paper feeding rollers 16, 17. , 18 are sent to the horizontal portion L1 of the conveying path L, and after being temporarily put into a standby state by the registration roller 19, are supplied to the image forming portion 3 at a predetermined timing synchronized with the toner image on the photosensitive drum 21. . In the paper feed cassette 7, the lift plate 9 is rotated in a direction away from the inner bottom surface, thereby raising the elevating plate 10 to a predetermined height position corresponding to the number of sheets stacked thereon, The uppermost one of the sheets stacked on the elevating plate 10 is picked up by the pickup roller 13. Further, when an image is formed on the paper loaded on the manual feed tray 8, the paper is taken out one by one by the pickup roller 20, and sent to the horizontal portion L1 of the transport path L by the paper feed rollers 16 and 18. .

  In the image forming unit 3, the sheet supplied to the transfer nip between the photosensitive drum 21 and the transfer roller 24 is conveyed while being pressed against the photosensitive drum 21 by the transfer roller 24, thereby its surface (transfer surface). ) Is transferred to the toner image on the photosensitive drum 21. Then, the sheet onto which the toner image has been transferred is conveyed to the fixing device 4 where the toner image is fixed by being heated and pressed by the fixing device 4. Note that the toner remaining on the surface of the photosensitive drum 21 (transfer residual toner) after the transfer of the toner image onto the paper is removed by the cleaning device 25.

  Thus, the sheet on which the toner image is fixed on the surface by the fixing device 4 is conveyed upward by the conveying roller 30 along the vertical portion L2 of the conveying path L, and is provided on the upper portion of the apparatus main body 1a by the paper discharge roller 31. The paper is discharged and stacked on the discharged paper discharge tray 32.

  The above is a series of operations when an image is formed on one side of a sheet. When an image is formed on both sides of a sheet, a sheet on which a toner image is fixed on one side by a fixing device 4 is conveyed by a conveyance roller 30. After the sheet is fed to the vertical portion L2 of the conveyance path L, the sheet is switched back by feeding the conveyance roller 30 in the reverse direction to be fed to another conveyance path L ′. Then, the paper is transported forward (to the right in FIG. 1) along the transport path L ′ by a plurality of transport rollers 33 provided in the transport path L ′, and the paper is transported by the paper feed rollers 16, 17, 18. When the sheet is fed again to the horizontal portion L1 of the conveyance path L, the front and back of the sheet are reversed, and thereafter, the toner image on the photosensitive drum 21 is transferred to the surface of the sheet (the other side on which no image is formed) by the same operation as described above. ) And the toner image is fixed on the paper in the fixing device 4, images are formed on both sides of the paper. The sheet on which images are formed on both sides in this way is conveyed upward along the vertical portion L2 of the conveyance path L by the conveyance roller 30 and is discharged to the discharge tray 32 by the discharge roller 31 as described above.

[Fixing device]
Next, an embodiment of the fixing device 4 according to the present invention will be described.

<Embodiment 1>
2 is a cross-sectional view of the fixing device according to the first embodiment of the present invention, and FIG. 3 is a perspective view of a heating roller portion of the identification fixing device.

  As shown in FIG. 2, the fixing device 4 is stretched between a hollow heating roller 28, a fixing roller 29 disposed opposite to the heating roller 28, and the heating roller 28 and the fixing roller 29. The endless fixing belt 34 and the pressure roller 35 are arranged in the vertical direction by being pressed by the fixing roller 29 with the fixing belt 34 interposed therebetween.

  Here, the heating roller 28 is configured by subjecting the outer surface of an aluminum cylindrical tube shaft 28a rotatably supported at both axial ends thereof to fluorine resin processing such as PFA. A halogen heater 36 as a heat source is arranged in parallel along the axial direction (perpendicular to the plane of FIG. 2) at the center of the internal shaft.

  The fixing roller 29 is formed by forming a cylindrical elastic layer 29b made of foamed silicon rubber on the outer surface of a cylindrical cored bar 29a made of a metal such as an aluminum alloy. It is rotatably supported.

  Further, as described above, the fixing belt 34 is stretched between the heating roller 28 and the fixing roller 29 while maintaining a predetermined tension state. In this embodiment, a nickel electroformed belt is used as a core material. A silicon rubber layer is laminated on the front and back surfaces of the core material, and a PFA film layer is formed on the surface.

  Further, as described above, the pressure roller 35 is pressed by the fixing roller 29 with the fixing belt 34 interposed therebetween to form a fixing nip N between the pressure roller 35 and the fixing roller 29. The pressure roller 35 is configured by forming a cylindrical elastic layer 35b made of silicon rubber on the outer surface of an aluminum alloy cored bar 35a and further forming a PFA film layer on the outer surface thereof. Both ends in the axial direction are rotatably supported.

  By the way, in the present embodiment, an excessive temperature rise prevention member 37 such as a thermostat as a safety device is in contact with the lower part of the outer surface of the heating roller 28. The excessive temperature rise prevention member 37 cuts off the energization to the halogen heater 36 when the heating roller 28 reaches an excessive temperature rise state, and as shown in FIG. The outer surface of the heating roller 28 is provided by four springs 39 (only three are shown in FIG. 3) that are compressed between the shafts 38 made of carbon steel (STMK) that are long in the axial direction. Is pressed with a predetermined force (about 50 to 200 g). Two lead wires 40 extend from the overheat prevention member 37 along the shaft 38.

  Thus, in the present embodiment, the cylindrical film 41 is sandwiched between the heating roller 28 and the excessive temperature rise prevention member 37 as shown in the figure, and this cylindrical film 41 is driven to rotate as the heating roller 28 rotates. It is characterized by making it. Here, as the cylindrical film 41, a film made of a fluorine resin having a high slidability, or a film formed by coating the surface with a fluorine resin is used.

  In the fixing device 4 configured as described above, when the pressure roller 35 is rotationally driven in the direction of the arrow (counterclockwise) in FIG. 2 by a drive motor (not shown), the pressure roller 35 causes the fixing roller 29 to move. The fixing belt 34, the fixing roller 29, and the heating roller 28 that are pressed rotate in the direction of the arrow (clockwise) in FIG. When the heating roller 28 rotates, the cylindrical film 41 sandwiched between the heating roller 28 and the excessive temperature rise prevention member 37 rotates following the rotation of the heating roller 28.

  As described above, when the heating roller 28 and the fixing roller 29 are rotated, the fixing film 34 stretched between them is circulated between the heating roller 28 and the fixing roller 29 and from a halogen heater 36 disposed therein. The whole is heated by the heating roller 28 heated by the radiated heat.

  Thus, when the sheet on which the toner image is transferred is supplied to the fixing device 4, the toner image is transferred in the process of passing through the fixing nip N formed between the fixing belt 34 and the pressure roller 35. The toner image is fixed on the paper by being heated and pressurized.

  As described above, in the fixing device 4 according to the present embodiment, since the cylindrical film 41 is interposed between the heating roller 28 and the overheat prevention member 37, the overheat prevention member 37 is directly applied to the heating roller 28. Contact is avoided, and the surface of the heating roller 28 by the excessive temperature rise prevention member 37 is prevented from being scraped. For this reason, it is possible to prevent the occurrence of image defects due to the abrasion of the heating roller 28 due to the contact with the excessive temperature rise prevention member 37 and the deterioration of the durability of the heating roller 28.

  Further, since only a thin cylindrical film 41 having a small heat capacity is interposed between the heating roller 28 and the excessive temperature rise prevention member 37, heat transfer from the heating roller 28 to the excessive temperature rise prevention member 37 is performed by the cylindrical film. 41 is hardly obstructed, and the high temperature rise prevention member 37 has a high thermal response and its thermal response time is short. When the temperature rises excessively, the energization to the halogen heater 36 is interrupted without a delay in response. Therefore, the occurrence of defects such as smoke and fire is reliably prevented.

  Furthermore, in the present embodiment, the cylindrical film 41 is made of a highly slidable fluorine-based resin, or the surface of the cylindrical film 41 is coated with the fluorine-based resin. The frictional force generated between them can be kept small, and the surface of the heating roller 28 can be more reliably prevented from being scraped by the excessive temperature rise prevention member 37. In addition, you may comprise the cylindrical film 41 with the thing of a tube shape where thickness is a little thick.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIG.

  FIG. 4 is a perspective view of the heating roller portion of the fixing device according to the present embodiment. In FIG. 4, the same elements as those shown in FIG. 3 are denoted by the same reference numerals. Description of is omitted.

  The present embodiment is characterized in that a guide member 42 for assisting the driven rotation of the cylindrical film 41 is attached to the lower portion of the shaft 38, and the other configuration is the same as that of the first embodiment. Here, the guide member 42 does not need to be in contact with the cylindrical film 41 in order to positively apply tension to the cylindrical film 41, and may be of a level that prevents a change in the shape of the cylindrical film 41.

  Thus, in this embodiment, the same effect as in the first embodiment can be obtained. However, since the driven rotation of the cylindrical film 41 is smoothly performed with the assistance of the guide member 42, the cylindrical film 41. Is uniformly brought into contact with the heating roller 28 and the excessive temperature rise prevention member 37 over the entire circumference, and its durability is enhanced. A guide member 42 may be added to the guide member 42 to prevent the cylindrical film 41 from shifting. Further, in order to protect the lead wire 40, the shaft 38 may be covered with a heat resistant cover.

<Embodiment 3>
Next, a third embodiment of the present invention will be described.

  The present embodiment is characterized in that the cylindrical film 41 is made of a thermoplastic resin that does not melt and soften during normal operation but has a melting point or softening point that melts or softens when overheated. The configuration is the same as that of the first or second embodiment.

  Thus, according to the present embodiment, the cylindrical film 41 is melted or softened at the time of excessive temperature rise, and the excessive temperature rise prevention member 37 comes into contact with or approaches the heating roller 28 so that the heat from the heating roller 28 is quickly supplied. As a result, the thermal response time is further shortened, and the energization of the halogen heater 36 is cut off without a delay in response. Of course, in this embodiment, the same effects as those obtained in the first and second embodiments can be obtained.

  Here, if the melting point or softening point of the thermoplastic resin constituting the cylindrical film 41 is too high, the thermoplastic resin is poorly melted or softened at the time of overheating, and the above effect cannot be obtained. On the other hand, if the temperature is too low, the cylindrical film 41 is deformed during normal operation. Therefore, the melting point or softening point of the thermoplastic resin is preferably a value that is appropriately higher than the fixing temperature, and is generally 200 ° C to 300 ° C. The range of is preferable. Any thermoplastic resin can be used as long as it has a melting point or a softening point in this temperature range, but in general, polyamide resin, polyethersulfone with glass fiber, polyethylene terephthalate with glass fiber, polyolefin resin Polyester resin, polycarbonate resin, etc. are used.

  In the above description, the present invention has been described with respect to a laser beam printer and a fixing device provided in the laser beam printer. However, the present invention is not limited to a printer, and any other image forming apparatus such as a copying machine or a facsimile machine. Of course, the present invention can also be applied to a fixing device provided in the same.

1 is a front sectional view of an image forming apparatus (laser beam printer) according to the present invention. 1 is a cross-sectional view of a fixing device according to Embodiment 1 of the present invention. FIG. 3 is a perspective view of a heating roller portion of the fixing device according to the first embodiment of the present invention. FIG. 6 is a perspective view of a heating roller portion of a fixing device according to Embodiment 2 of the present invention.

Explanation of symbols

1 Laser beam printer (image forming device)
2 Paper feeding unit 3 Image forming unit 4 Fixing device (fixing means)
DESCRIPTION OF SYMBOLS 5 Paper discharge part 6 Switch back part 7 Paper feed tray 8 Manual feed tray 9 Lift board 10 Lifting board 11 Lift drive shaft 12 Shaft 13 Pickup roller 14 Feed roller 15 Retard roller 16-18 Paper feed roller 19 Registration roller 20 Pickup roller 21 Photosensitive Drum (image carrier)
22 Primary charger 23 Developing device (developing means)
24 Transfer roller (transfer means)
25 Cleaning device 26 Laser scanner unit (LSU)
27 Toner hopper 28 Heating roller 29 Fixing roller 30 Conveying roller 31 Discharging roller 32 Discharging tray 33 Conveying roller 34 Fixing belt 35 Pressure roller 36 Halogen heater (heat source)
37 Overheating prevention member 38 Shaft 39 Spring 40 Lead wire 41 Cylindrical film 42 Guide member N Fixing nip

Claims (5)

In a fixing device comprising a heating roller that is heated by a heat source disposed therein, and an excessive temperature rise prevention member that abuts the outer surface of the heating roller and interrupts energization to the heat source when the temperature rises excessively.
A fixing device, wherein a cylindrical film is sandwiched between the heating roller and the excessive temperature rise prevention member, and the cylindrical film is driven to rotate as the heating roller rotates.   2. The fixing device according to claim 1, wherein the cylindrical film is made of a fluorine resin having a high sliding property, or the surface of the cylindrical film is coated with a fluorine resin.   3. The fixing device according to claim 1, wherein the cylindrical film is made of a thermoplastic resin that melts or softens when the temperature rises excessively.   The fixing device according to claim 1, further comprising a guide member that assists in the driven rotation of the cylindrical film. An image carrier that forms a latent image, a developing unit that develops the latent image formed on the image carrier as a toner image, a transfer unit that transfers the toner image on the image carrier onto a transfer material, In an image forming apparatus including a fixing unit that fixes a toner image transferred onto a transfer material by the transfer unit by heating and pressing.
An image forming apparatus comprising the fixing device according to claim 1.

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