JP5921820B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device that fixes a developer image on a sheet by heating and pressurizing the sheet passing through a nip portion, and an image forming apparatus including the same.

  An electrophotographic image forming apparatus includes a process unit and a fixing device. The process unit forms a developer image and transfers it to a sheet. The sheet onto which the developer image has been transferred is conveyed to a fixing device. The fixing device includes a pair of fixing rollers, and heats the sheet at the nip portion of the pair of fixing rollers to fix the developer image to the sheet. Further, the fixing device includes a paper guide member on the upstream side of the pair of fixing rollers in the paper transport direction. The paper guide member has a guide portion that guides the paper that has passed through the process portion to the nip portion.

  When the paper guide member was formed of a metal thin plate, the paper guide member was easily heated by the heat propagated from the fixing roller pair. When the paper guide member is heated, the temperature of the process part is increased by the heat propagated from the paper guide member, which may cause problems such as deterioration of the process part and deterioration of image quality.

  Therefore, in order to cut off the propagation of heat from the fixing roller pair to the process unit, the paper guide member has a two-part structure of the first guide unit and the second guide unit along the sheet conveyance direction, and the first guide unit and the first guide unit 2. Description of the Related Art A fixing device in which a heat insulating material is interposed at a connecting portion with a guide portion is known (see, for example, Patent Document 1).

JP 60-63556 A

  However, in the conventional fixing device described in Patent Document 1, heat conduction due to contact between the first guide portion and the second guide portion is only suppressed, and the first heat is radiated from the pair of fixing rollers. Not only the guide part but also the second guide part is heated. The second guide part is also heated by radiant heat from the first guide part. For this reason, the conventional fixing device cannot suppress the propagation of heat due to radiation from the fixing roller pair to the process unit.

  An object of the present invention is to provide a fixing device and an image forming apparatus that can suppress the propagation of heat due to radiation from a fixing roller pair to a process section.

  The fixing device of the present invention includes a pair of fixing rollers and a paper guide member. The fixing roller pair fixes the developer image onto the sheet by heating the sheet conveyed through the nip portion of the pair. The paper guide member has a guide body and a heat insulating part. The guide main body is disposed between the fixing roller pair and the process unit that transfers the developer image to the paper, and includes a guide unit that guides the paper carrying the developer image to the nip portion. The heat insulating part is disposed on the back surface of the sheet conveying surface of the guide part.

  In this configuration, heat is radiated from the fixing roller pair, but is blocked by the heat insulating portion, thereby suppressing the propagation of heat from the fixing roller pair to the guide portion. As a result, the temperature rise of the guide part is suppressed, so that the propagation of heat due to radiation from the guide part to the process part is also suppressed.

  In the above-described configuration, the guide main body has a support portion that is arranged in a direction orthogonal to the sheet conveyance direction between the fixing roller pair and the process portion and supports the guide portion, and the heat insulating portion is on the same side as the back surface. It is preferable to arrange also on the surface of the support part.

  By disposing the heat insulating portion on the surface of the support portion on the same side as the back surface of the paper conveying surface of the guide portion, heat propagation due to radiation from the fixing roller pair to the support portion is also suppressed. As a result, the temperature rise of the support part is also suppressed, so that the propagation of heat due to radiation from the support part to the process part is also suppressed.

  As an example of a specific configuration of the heat insulating portion, a configuration including a heat insulating material can be given. Since the heat radiated from the pair of fixing rollers is blocked by the heat insulating material, the temperature rise of the guide body is suppressed. Therefore, the propagation of heat due to radiation from the guide body to the process part is also suppressed.

  Moreover, a heat insulation part can be comprised so that the partition member which forms an air layer may be included. Due to the presence of the air layer, the heat radiated from the fixing roller pair is hardly transmitted to the guide body. For this reason, the temperature rise of a guide main body is suppressed. Therefore, the propagation of heat due to radiation from the guide body to the process part is also suppressed.

  Furthermore, it is preferable that the partition member further includes a blowing unit that forms a duct and generates an air flow in the duct. Since airflow is generated in the air layer in the duct, the heat insulating effect by the heat insulating portion is further increased. For this reason, the temperature rise of a guide main body is suppressed more. Therefore, the propagation of heat due to radiation from the guide body to the process part is further suppressed.

  More preferably, at least one of the guide main body and the partition member has one or more fins protruding toward the air layer side. The heat exchange efficiency between the guide body and the partition member and the air layer is enhanced, and the heat of the guide body and the partition member is radiated to the air layer, so that the temperature rise of the guide body and the partition member is further suppressed. Therefore, the propagation of heat due to radiation from the guide body to the process part is further suppressed.

  The image forming apparatus of the present invention includes the fixing device having any one of the above-described configurations. In this configuration, heat is radiated from the fixing roller pair, but is blocked by the heat insulating portion, thereby suppressing the propagation of heat from the fixing roller pair to the guide portion. As a result, the temperature rise of the guide part is suppressed, so that the propagation of heat due to radiation from the guide part to the process part is also suppressed.

  According to this invention, the propagation of heat due to radiation from the fixing roller pair to the process section can be suppressed.

1 is a front view illustrating a schematic configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention. FIG. 6 is a front view of a paper guide member provided in the fixing device. It is a front view of the paper guide member concerning other embodiments. It is a front view of the paper guide member concerning other embodiments. It is a front view of the paper guide member concerning other embodiments.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated based on drawing. As shown in FIG. 1, the image forming apparatus 1 includes a fixing device 10 and a process unit 20, and forms an image on a sheet through an electrophotographic image forming process.

  The process unit 20 includes a photosensitive drum 21, and further includes a charger 22, an exposure device 23, a developing device 24, a transfer device 25, and a cleaning unit 26 around the photosensitive drum 21.

  In the process unit 20, the peripheral surface of the photosensitive drum 21 is charged to a predetermined potential by the charger 22, and laser light modulated based on the image data is irradiated to the peripheral surface of the photosensitive drum 21 by the exposure device 23. As a result, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 21. Further, the developer (toner) is supplied to the peripheral surface of the photosensitive drum 21 by the developing unit 24, whereby the electrostatic latent image is visualized as a toner image (developer image).

  A sheet is supplied one by one from a sheet tray (not shown) to the transfer region where the photosensitive drum 21 and the transfer unit 25 face each other. By applying a predetermined potential to the transfer unit 25, the toner image carried on the peripheral surface of the photosensitive drum 21 is transferred to a sheet. The toner remaining on the peripheral surface of the photosensitive drum 21 is collected by the cleaning unit 26.

  The sheet carrying the toner image is conveyed toward the fixing device 10. Guide members 31 and 32 for guiding the paper are arranged in the paper conveyance path 30 passing through the transfer area and the fixing device 10.

  The fixing device 10 includes a pair of fixing rollers including a first fixing roller 11 and a second fixing roller 12, a cleaning roller 13, a web roller 14, and a paper guide member 40. The first fixing roller 11 is disposed on the second fixing roller 12.

  The first fixing roller 11 has heater lamps 111 and 112 as heating means, and is heated from the inside. The second fixing roller 12 has a heater lamp 121 as a heating unit and is heated from the inside. The first fixing roller 11 and the second fixing roller 12 are in pressure contact with each other. The first fixing roller 11 and the second fixing roller 12 firmly fix the toner image on the paper by heating and pressing the paper conveyed through the nip portion 15 between the first fixing roller 11 and the second fixing roller 12. Let The paper on which the toner image is fixed is discharged to a paper discharge tray (not shown).

  The cleaning roller 13 collects the toner attached to the peripheral surface of the first fixing roller 11. The web roller 14 collects the toner adhering to the peripheral surface of the cleaning roller 13, thereby maintaining the toner collecting ability of the cleaning roller 13 high.

  The paper guide member 40 is disposed between the process unit 20 and the fixing device 10 and in the vicinity of the upstream side of the second fixing roller 12 in the paper conveyance direction 91. The paper guide member 40 guides the paper, which has been transferred along the guide member 32 after the toner image is transferred from the photosensitive drum 21 in the transfer region, to the nip portion 15.

  As shown in FIG. 2, the paper guide member 40 includes a guide main body 60 and a heat insulating part 70, and is disposed between the second fixing roller 12 and the process part 20. As an example, the guide body 60 is made of aluminum. In addition, as the guide body 60, a carbon steel plate that has been subjected to a surface treatment for rust prevention such as galvanization can also be used.

  The guide body 60 has a guide part 61, a support part 62, and a base part 63. The base portion 63 extends in a direction along the paper transport direction 91 and supports the lower end of the support portion 42. The support unit 62 is erected in a direction orthogonal to the paper transport direction 91 between the second fixing roller 12 and the process unit 20 to support the upstream end 612 of the guide unit 61 in the paper transport direction 91. Yes.

  A downstream end 611 of the guide 61 in the sheet conveyance direction 91 is disposed in the vicinity of the nip 15 in order to guide the sheet to the nip 15. The guide portion 61 is inclined in a direction away from the paper transport path 30 toward the upstream end 612. Therefore, the sheet conveyance surface 613 of the guide unit 61 is inclined in the direction facing the process unit 20 with respect to the sheet conveyance path 30, and the back surface 614 of the sheet conveyance surface 613 is opposed to the second fixing roller 12. Inclined in the direction.

  The sheet conveyance surface 613 of the guide unit 61 and the first surface 621 of the support unit 62 on the same side as the sheet conveyance surface 613 are preferably non-glossy surfaces. Since the surface of the guide body 60 facing the process unit 20 is non-glossy, heat radiation from the guide body 60 to the process unit 20 side is suppressed.

  The sheet guided by the guide member 32 disposed between the process unit 20 and the fixing device 10 is guided to the nip unit 15 while being rubbed against the downstream end 611 of the guide unit 61.

  The heat insulating portion 70 is disposed so as to cover the back surface 614 of the guide portion 61 and the second surface 622 of the support portion 62 on the same side as the back surface 614. In this embodiment, the heat insulation part 70 is comprised with the heat insulating material. Examples of the heat insulating material include glass wool, rock wool, and ceramic fiber.

  The heat radiated from the second fixing roller 12 is blocked by the heat insulating portion 70, so that the propagation of heat from the second fixing roller 12 to the guide portion 61 and the support portion 62 is suppressed. As a result, the temperature rise of the guide part 61 and the support part 62 is suppressed, so that the propagation of heat due to radiation from the guide part 61 and the support part 62 to the process part 20 is also suppressed. Therefore, the propagation of heat due to radiation from the second fixing roller 12 to the process unit 20 can be suppressed, and the life of the process unit 20 can be extended and the image quality can be improved.

  FIG. 3 shows a configuration of a paper guide member 40A according to another embodiment. In the paper guide member 40 </ b> A, the heat insulating portion 70 </ b> A includes a heat insulating material 71 and a partition member 72 that forms an air layer 92.

  The partition member 72 has a substantially L-shaped cross section, and includes a side wall portion 721 that faces the support portion 62 and a bottom portion 722 that faces the guide portion 61. The bottom portion 722 is configured by two plates facing each other with a predetermined gap therebetween, and the base portion 63 of the guide body 60 is sandwiched between the two plates. An air layer 92 is formed between the partition member 72 and the guide body 60.

  A surface of the side wall portion 721 on the second fixing roller 12 side and a back surface 614 of the guide portion 61 are covered with a heat insulating material 71. The heat insulating material 71 suppresses the temperature rise of the partition member 72 due to the heat radiated from the second fixing roller 12.

  In addition, since the air layer 92 is interposed between the second fixing roller 12 and the guide body 60, the heat radiated from the second fixing roller 12 is less likely to be transmitted to the guide body 60. For this reason, the temperature rise of the guide main body 60 is further suppressed. Therefore, heat propagation due to radiation from the guide body 60 to the process unit 20 is also suppressed.

  FIG. 4 shows a configuration of a paper guide member 40B according to still another embodiment. In the paper guide member 40 </ b> B, the heat insulating portion 70 </ b> B includes a heat insulating material 71 and a partition member 72 that forms a duct 93.

  As an example, the guide main body 60 and the partition member 72 are integrally configured by die casting. A duct 93 is formed by the guide main body 60, the partition member 72, and the shielding plate 73.

  The duct 93 extends in the same direction as the rotation axis of the second fixing roller 12 along the back surface 614 of the guide portion 61 and the second surface 622 of the support portion 62.

  The back surface 614 of the portion of the guide portion 61 that extends further to the second fixing roller 12 side than the partition member 72 and the surface of the partition member 72 on the second fixing roller 12 side are covered with a heat insulating material 71.

  In addition, the fixing device 10 includes a blower 94 that generates an air current in the duct 93. The blower 94 sucks air from the outside of the image forming apparatus 1 and supplies the air into the duct 93, and discharges the air that has passed through the duct 93 to the outside of the image forming apparatus 1.

  Since the air flow is generated in the duct 93 by the blower 94, the air whose temperature has increased in the duct 93 is discharged to the outside of the image forming apparatus 1, and cooler air is taken into the duct 93 from the outside of the image forming apparatus 1. It is. For this reason, the heat insulation effect by the heat insulation part 70B increases more. For this reason, the temperature rise of the guide main body 60 is further suppressed. Therefore, the propagation of heat due to radiation from the guide body 60 to the process unit 20 is further suppressed.

  The sheet conveying surface 613 of the downstream end 611 of the guide 61 is provided with a highly conductive metal plating 64. Since the downstream end portion 611 of the guide portion 41 has high conductivity, static electricity due to rubbing with the paper is less likely to accumulate at the downstream end portion 611. For this reason, the adsorption | suction by the static electricity of the paper to the downstream edge part 611 is suppressed. Therefore, the paper transportability is improved. The metal plating 64 is preferably electrically grounded.

  The duct 93 is not limited to being configured by the guide body 60, the partition member 72, and the shielding plate 73. The duct 93 can also be configured by forming the partition member 72 in a cylindrical shape.

  FIG. 5 shows a configuration of a paper guide member 40C according to still another embodiment. The paper guide member 40C is configured in the same manner as the paper guide member 40B except that at least one of the guide main body 60 and the partition member 72 has one or more fins 74 protruding to the air layer 92 side. As an example, a plurality of fins 74 are provided on both the guide body 60 and the partition member 72.

  The heat exchange efficiency between the guide main body 60 and the partition member 72 and the air layer 92 is enhanced by the fins 74, and the heat of the guide main body 60 and the partition member 72 is efficiently radiated to the air layer 92, so that the heat insulating effect by the heat insulating portion 70C. And the temperature rise of the guide body 60 and the partition member 72 is further suppressed. Therefore, the propagation of heat due to radiation from the guide body 60 to the process unit 20 is further suppressed.

  The heat insulating portion 70 is not limited to be disposed so as to cover the back surface 614 of the guide portion 61 and the second surface 622 of the support portion 62, and is disposed on a part of the back surface 614 and the second surface 622. Even in this case, the effect of suppressing the propagation of heat due to the radiation from the second fixing roller 12 to the guide part 61 and the support part 62 can be obtained according to the area covering the back surface 614 and the second surface 622.

  Further, the heat insulating portions 70, 70 </ b> A, 70 </ b> B, 70 </ b> C are not limited to being disposed on both the back surface 614 of the guide portion 61 and the second surface 622 of the support portion 62. For example, even when the heat insulating portion 70 is disposed only on the back surface 614 of the guide portion 61, by suppressing the propagation of heat from the second fixing roller 12 to the guide portion 61, the heat due to radiation to the process portion 20 can be reduced. The effect that propagation can be suppressed is produced.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Fixing apparatus 11 1st fixing roller 12 2nd fixing roller 15 Nip part 20 Process part 30 Paper conveyance path 40, 40A, 40B, 40C Paper guide member 60 Guide main body 61 Guide part 613 Paper conveyance surface 614 Back surface 62 Support part 63 Base part 70, 70A, 70B, 70C Heat insulation part 71 Heat insulation material 72 Partition member 74 Fin 91 Paper transport direction 92 Air layer 93 Duct 94 Blower

Claims (10)

A pair of fixing rollers for fixing the developer image on the paper by heating the paper conveyed through the nip portion of each other;
Arranged between the fixing roller pair and a process unit for transferring a developer image to a sheet, and arranged in a direction perpendicular to the sheet conveyance direction and a guide unit for guiding the sheet carrying the developer image to the nip unit. guide body having a support portion for supporting the guide portion, and provided with a paper guide member having a heat insulating portion provided on the rear face of the sheet conveyance surface of the guide portion,
The paper conveying surface is a non-glossy surface,
The heat insulating part includes a partition member arranged to form an air layer between the support part and
The guide body further includes a base portion extending from a lower end of the support portion toward the partition member;
The partition member has a side wall portion facing the support portion and a bottom portion facing the base portion,
The fixing device , wherein the base and the bottom are engaged with each other . The fixing device according to claim 1 , wherein at least a part of the base portion and the bottom portion overlap each other . The fixing device according to claim 1 , wherein the bottom portion includes two plates facing each other with a predetermined gap therebetween, and the base portion is sandwiched between the two plates . The fixing device according to claim 1 , wherein the heat insulating portion includes a heat insulating material . 5. The fixing device according to claim 1, further comprising a blowing unit that generates an air flow in a duct formed between the guide body and the partition member . 6. The fixing device according to claim 1, wherein at least one of the guide main body and the partition member has one or more fins protruding toward the air layer. The first surface of the supporting portion of the same side as the front Symbol sheet conveying surface, a non-glossy surface, the fixing device according to any one of claims 1 to 6.   The fixing device according to claim 1, wherein highly conductive metal plating is applied to a downstream end portion of the sheet conveying surface in the sheet conveying direction. A pair of fixing rollers for fixing the developer image on the paper by heating the paper conveyed through the nip portion of each other;
A guide body that is disposed between the fixing roller pair and a process unit that transfers a developer image to a sheet and has a guide unit that guides the sheet carrying the developer image to the nip unit, and sheet conveyance of the guide unit A paper guide member having a heat insulating portion disposed on the back surface of the surface,
The paper conveying surface is a non-glossy surface,
The guide body is disposed between the fixing roller pair and the process unit in a direction orthogonal to the sheet conveyance direction and supports the guide unit, and supports the lower end of the support unit and supports the sheet conveyance direction. A base portion extending in a direction along
The heat insulating portion includes a partition member that forms an air layer,
The partition member has a side wall portion that faces the support portion and a bottom portion that faces the guide portion, and is formed so that a cross section of the side wall portion and the bottom portion is L-shaped.
The fixing device according to claim 1, wherein the bottom portion includes two plates facing each other with a predetermined gap therebetween, and the base portion is sandwiched between the two plates.   An image forming apparatus comprising the fixing device according to claim 1.

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