JP2006267901A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device designed such that fixing failure is prevented while a sufficient nip length is ensured without increasing the size of this type of the device and durability is excellent, and to provide an image forming apparatus having the fixing device. <P>SOLUTION: The fixing device includes: an endless fixing belt 8 that is heated; a fixing means 51 disposed inside the fixing belt 8; a rotatable pressure roller 52 disposed opposite the fixing means 51 and forming a fixing nip N1 together with the fixing means 51 via the fixing belt 8; and a heat source 9 for directly heating the fixing belt 8 without being in contact with the fixing belt 8. An auxiliary guide member 10 is disposed inside the fixing belt 8 so that a paper guide path L by which the recording paper P is guided along the fixing belt 8 is formed upstream of the fixing nip N1. In addition, an auxiliary nip member 11 for pressing the fixing belt 8 to the pressure roller 52 is disposed inside the fixing belt 8 so that an extending nip area N2 is formed downstream of the fixing nip N1 so as to be continuous with the fixing nip N1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device that heats and fixes an unfixed toner image on a recording sheet using a fixing belt in an image forming apparatus such as a copying machine or a facsimile, and an image forming apparatus including the fixing device.

  In general, in an image forming apparatus such as a copying machine, a printer, or a facsimile, a recording sheet carrying an unfixed toner image is nipped and conveyed to a nip formed by a heating roller and a pressure roller of the fixing device. The unfixed toner image is fixed on the recording paper by heating and pressurizing. In such a fixing device, a heating unit is built in a middle space portion of the heating roller, and a nip portion formed by pressing the heating roller and the pressure roller is heated by the heating unit. Therefore, there is a disadvantage that it takes time for the fixing device to raise the temperature to a desired fixing temperature.

  On the other hand, in recent years, demands for power saving and shortening of the warm-up time have increased, and development of a fixing device suitable for colorization of an image has been desired. Various types of fixing devices have been proposed and put into practical use.

Conventionally, for example, in order to reduce the heat capacity of the heated portion and shorten the warm-up time, a pressure roller that sandwiches the recording paper via the fixing belt is provided facing the fixing roller, and the fixing belt is used as a heating source. There is one that is directly heated in a non-contact manner (see, for example, Patent Document 1).
Japanese Patent No. 2002-214953

  However, in the device described in Patent Document 1 described above, if the fixing roller, which is a heated member, is reduced in size as the heat capacity is reduced, the nip length for heating and pressurizing the recording paper is shortened, which may lead to poor fixing. There is. In order to avoid this, if the fixing roller has a large diameter in order to obtain a sufficient nip length, the fixing belt becomes longer accordingly, the heat capacity increases, and this type of apparatus increases in size. Also, if the pressure applied to the pressure roller is increased to ensure the nip length without increasing the size, a large bending force is applied to the fixing roller and the pressure roller, making it difficult to withstand long-term use. There was a problem in terms of durability.

  The present invention has been made in order to solve the above-described problems, and without increasing the size of this type of apparatus, a sufficient nip length is secured to prevent the occurrence of fixing failure, and the durability is excellent. Another object of the present invention is to provide a fixing device and an image forming apparatus including the fixing device.

  In order to achieve the above object, according to the present invention, an endless fixing belt to be heated, a fixing unit disposed inside the fixing belt, a fixing unit disposed opposite to the fixing unit, and in cooperation with the fixing unit. The fixing belt is directly heated in a non-contact manner in order to fix a rotatable pressure roller that forms a fixing nip via the fixing belt and an unfixed toner image carried on the recording paper that is nipped and conveyed by the fixing nip. In a fixing device having a heating source, a guide auxiliary member is disposed inside the fixing belt so as to form a paper guide path on the upstream side of the fixing nip so that the recording paper is guided along the fixing belt. In addition, a nip auxiliary member that presses the fixing belt toward the pressure roller is disposed on the inner side of the fixing belt so as to form a nip extension region continuously to the fixing nip on the downstream side of the fixing nip. This The features.

  According to this configuration, the recording paper is guided to the fixing nip along the fixing belt by the guide auxiliary member disposed on the upstream side of the fixing nip, and is pressed and heated. It is sufficiently pressurized and heated by the continuously formed nip extension region. Therefore, a sufficient nip length for fixing can be secured without increasing the size of the fixing means that is a member to be heated. As a result, without increasing the size of this type of apparatus, a sufficient nip length is ensured to prevent the occurrence of fixing failure, and the fixing apparatus having excellent durability, and an image forming apparatus including the fixing apparatus are provided. Obtainable.

  Here, in the present invention, the pressure roller further includes an elastic layer, and the nip auxiliary member is formed so as to strongly press the fixing belt locally toward the pressure roller near the exit of the nip extension region. It is characterized by that. According to this configuration, the elastic layer of the pressure roller is strongly pressed locally, so that a large strain is generated in the portion, and the moving speed of the recording paper and the elastic layer are generated in the portion where the strain is generated. There is a slight difference in the moving speed of the pressure roller having As a result, the adhesive force between the recording paper and the surface of the fixing belt is reduced, and the recording paper is easily separated from the fixing belt, which is convenient.

  In the present invention, the paper guide path is disposed close to the recording paper carry-in path, and is configured to form a preheating region for preheating the recording paper by the fixing belt. Features. According to this configuration, since preheating is effectively performed with a longer low load nip pressure in the preheating region, fixing unevenness and image roughness can be prevented, and image quality can be further improved. convenient.

  In the present invention, a reflection plate for reflecting the radiant heat from the heating source to the fixing belt side is disposed between the heating source and the fixing unit. According to this configuration, it is possible to prevent the radiant heat from the heating source from being irradiated to the part other than the fixing belt, so that the fixing belt can be effectively heated. As a result, energy saving can be achieved, which is convenient.

  In the present invention, the guide assisting member and / or the nip assisting member is formed of a resin, and the fixing belt slides on the surface of the guide assisting member and / or the nip assisting member facing the fixing belt. A rib that extends and slides while contacting the fixing belt is provided. According to this configuration, since the heat capacity of the guide auxiliary member and / or the nip auxiliary member is extremely small, there is little energy loss. Further, since the sliding area between the guide auxiliary member and / or the nip auxiliary member and the fixing belt is small, the conveyance property of the fixing belt is improved and the durability of the fixing belt is improved. In addition, the rib of the nip assisting member is further advantageous in that the elastic layer of the pressure roller can be further distorted and the separation of the recording paper can be improved.

  In the present invention, the guide auxiliary member and / or the nip auxiliary member is formed of a rotating body that is sufficiently smaller than the pressure roller. According to this configuration, since the heat capacity of the guide auxiliary member and / or the nip auxiliary member is extremely small, there is little energy loss. Further, since the guide assisting member and / or the nip assisting member rotate as the fixing belt slides, the transportability of the fixing belt is further facilitated, and the durability of the fixing belt is further improved, which is convenient. .

  In the present invention, the fixing means, the nip auxiliary member, and the guide auxiliary member are integrally formed. According to this configuration, since the fixing unit, the nip auxiliary member, and the guide auxiliary member are integrally formed, the number of parts is reduced, and the handling is facilitated, which is convenient.

  In the present invention, the fixing means is formed of a non-rotating pressure pad. According to this configuration, when the fixing unit is a non-rotating pressure pad, the heat capacity can be reduced and the warm-up can be further shortened. Further, it is possible to form a pressure distribution from the upstream side to the downstream side before and after the fixing nip, a strong pressure on the downstream side, and a flat pressure distribution from the upstream side to the fixing nip, thereby improving the fixing property and the separation property. In addition, it is convenient because space can be saved.

  Furthermore, in the present invention, there is provided an image forming apparatus comprising a fixing device having any one of the above-described configurations. Therefore, according to this configuration, it is possible to obtain an image forming apparatus that exhibits the same action as the fixing device having any one of the above-described configurations.

  According to the present invention, without increasing the size of this type of device, a sufficient nip length is secured to prevent the occurrence of fixing failure, and the fixing device is excellent in durability, and an image provided with this fixing device. A forming device can be obtained.

(First embodiment)
A specific first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic configuration diagram showing a schematic configuration when applied to a copying machine as an image forming apparatus using the fixing device according to the first embodiment of the present invention.

  As shown in FIG. 1, a copying machine 1, which is an image forming apparatus, includes a document conveying unit 3 that automatically conveys a document to an image reading unit 2, an image reading unit 2 that reads image information of a document, and a recording target. An image forming unit 4 that forms an image read by the image reading unit 2 on a sheet P, a fixing device 5 to be described later, and a sheet feeding unit 6 in which the recording sheet P is stored are provided. Further, a paper transport path 7 is formed for transporting the recording paper P to the paper discharge section 71 via the image forming means 4 and the fixing device 5.

  As is well known, the image reading unit 2 irradiates light from an exposure lamp to an original that has been conveyed from the original conveying unit 3 on the contact glass, and reflects the light through a reflecting mirror. By guiding the light to a photoelectric conversion unit comprising a CCD sensor or the like, the image information of the document is read and read.

  The document conveying means 3 includes a document placing table 31 for placing a document, a document feeding unit that feeds a document loaded on the document placing table 31, and a document feeding unit for transporting the fed document. A paper conveyance path and a document discharge section 32 for discharging the document that has been read are provided.

  The paper feeding means 6 includes a plurality of paper feeding cassettes 61 in which recording paper P is accommodated, and a paper feeding cassette 61 selected from among the plurality of paper feeding cassettes 61 by the rotation operation of the paper feeding roller 62. The recording paper P is sent out to the paper conveyance path 7 side. With this configuration, the recording paper P is reliably fed to the paper transport path 7 one by one. These paper feed cassettes 61 are configured to be detachable from the copying machine 1.

  The recording paper P fed to the paper transport path 7 is transported toward the image forming unit 4 via the paper transport path 7. The image forming means 4 forms a predetermined toner image on the recording paper P by an electrophotographic process, and is an image end holder that is rotatably supported in a predetermined direction (the arrow direction in the figure). And a charging device 42, an exposure device 43, a developing device 44, a transfer device 45, a cleaning device 46, and a charge eliminating device 47 are provided around the photoconductor 41 in the rotation direction.

  The charging device 42 includes a charging wire to which a high voltage is applied. By applying a predetermined potential to the surface of the photoconductor 41 by corona discharge from the charging wire, the surface of the photoconductor 41 is uniformly charged. It is done. Then, the exposure device 43 irradiates the photoconductor 41 with light based on the image data of the original read by the image reading unit 2, whereby the surface potential of the photoconductor 41 is selectively attenuated, and this photosensitivity. An electrostatic latent image is formed on the surface of the body 41. Next, toner is attached to the electrostatic latent image by the developing device 44 to form a toner image on the surface of the photoconductor 41, and the toner image on the surface of the photoconductor 41 is transferred from the photoconductor 41 to the transfer device by the transfer device 45. 45 is transferred onto the recording paper P supplied between the two.

  The recording paper P to which the toner image is transferred is conveyed from the image forming unit 4 to the fixing device 5. The fixing device 5 is disposed on the downstream side of the image forming unit 4 in the paper conveyance direction, and the recording paper P on which the toner image is transferred by the image forming unit 4 is heated and pressed by the fixing device 5 described later. Then, the toner image is fixed on the recording paper P. Next, the recording paper P on which the image is formed in the fixing device 5 from the image forming unit 4 is discharged onto the paper discharge unit 71. On the other hand, after the transfer, the toner remaining on the surface of the photoconductor 41 is removed by the cleaning device 46, and the residual charge on the surface of the photoconductor 41 is removed by the charge eliminating device 47. The photosensitive member 41 is charged again by the charging device 42, and image formation is performed in the same manner.

  Next, a specific configuration of the fixing device according to the characteristic part of the present invention will be described with reference to FIGS. FIG. 2 is a conceptual diagram showing a schematic configuration of the fixing device shown in FIG. 1, and FIG. 3 is an enlarged sectional view showing an example of a fixing belt of the fixing device shown in FIG.

  In the present embodiment, as shown in FIG. 2, the fixing device 5 includes an endless fixing belt 8 to be heated, a fixing unit 51 disposed inside the fixing belt 8, and a fixing unit 51. A rotatable pressure roller 52 that is disposed and forms a fixing nip N1 through the fixing belt 8 in cooperation with the fixing unit 51 is provided. Further, in order to fix the unfixed toner image carried on the recording paper P held and conveyed by the fixing nip N1, the fixing belt 8 is directly heated in a non-contact manner inside the fixing belt 8, for example, from a halogen heater or the like. The heating source 9 is provided. With this configuration, as described above, the fixing device 5 has the fixing nip N1 in which the recording paper P carrying the unfixed toner image is formed by the fixing means 51 and the pressure roller 52 via the fixing belt 8. And has a function of fixing the unfixed toner image onto the recording paper P.

  For example, the fixing unit 51 rotatably supports a fixing roller provided with a foamed silicone rubber layer as an elastic body on a mandrel on a rotating shaft (not shown). Similarly, the pressure roller 52 is provided with a foamed silicone rubber layer as an elastic body on a metal core, is rotatably supported by a rotating shaft (not shown), and is fixed by a pressing spring (not shown). It is pressed to the side.

  As shown in FIG. 3, the endless fixing belt 8 has, for example, a release layer 81 on the surface in contact with the pressure roller 52 and a base layer 82 made of resin on the back surface, and the release layer 81, the base layer 82, In between, it is formed as a multilayer structure in which an elastic layer 83 is provided. The inner surface 82b of the fixing belt 8 facing the heating source 9 is preferably black so that the radiant heat from the heating source 9 can be easily absorbed. As the release layer 81, for example, a fluororesin can be used, and examples thereof include polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane resin (PFA). Examples of the base layer 82 include a belt base material made of polyimide resin or nickel having a thickness of about 30 μm to 100 μm. Examples of the elastic layer 83 include silicone rubber having a thickness of about 100 μm to 500 μm.

  A guide assisting member 10 is arranged inside the fixing belt 8 and upstream of the fixing nip N1 so as to form a paper guide path L along which the recording paper P is guided along the fixing belt 8. It is installed. Further, on the inner side of the fixing belt 8 and on the downstream side of the fixing nip N1, the fixing belt 8 is pressed continuously to the fixing nip N1, and the nip extension region N2 is formed by pressing the pressing belt 52 side. A nip auxiliary member 11 is disposed.

  The auxiliary guide member 10 and the auxiliary nip member 11 are formed of resin in a desired shape, and a protective layer is provided on the surface of the auxiliary belt 10 where the fixing belt 8 comes into contact and slides. It is preferable to reduce it. Further, the protective layer may be provided on the inner surface 82b of the fixing belt 8, and in this case, the protective layer is preferably black. Examples of the guide auxiliary member 10 and the nip auxiliary member 11 include heat resistant resins such as polyimide, polyamideimide, polybenzimidazole, polybenzoxazole, and polyphenylene sulfide. Examples of the protective layer include polyimide, glass fiber, polyimide amide, polyethersulfone (PES), and fluororesin.

  The pressure roller 52 having an elastic layer as described above is used, and the fixing belt 8 is locally pressed by the nip auxiliary member 11 near the exit of the nip extension region N2 (point T in FIG. 2). It is formed so as to press strongly toward the 52 side. With this configuration, the elastic layer of the pressure roller 52 is strongly pressed locally at the point T, so that a large strain is generated in the portion. There is a slight difference between the moving speed and the moving speed of the pressure roller 52 having an elastic layer. As a result, the adhesive force between the recording paper P and the surface of the fixing belt 8 is reduced, and the recording paper P is easily separated from the fixing belt 8, which is convenient.

  In addition, the paper guide path L formed by the fixing belt 8 that circulates along the auxiliary guide member 10 is disposed close to the carry-in path of the recording paper P. That is, the fixing belt 8 is disposed so as to approach the carry-in path side of the recording paper P, and a preheating region for preheating the recording paper P is formed by the fixing belt 8. If configured in this manner, preheating can be effectively performed with a longer low load nip pressure in the paper guide path L serving as a preheating region, so that uneven fixing and image roughness can be prevented, and image quality can be improved. Since improvement can be aimed at, it is convenient.

  Further, a reflector 12 that reflects the radiant heat from the heating source 9 toward the fixing belt 8 may be disposed between the heating source 9 and the fixing unit 51. For example, the reflecting plate 12 is supported by a support 13 that also serves as a guide for the fixing belt 8. With such a configuration, it is possible to prevent the radiant heat from the heating source 9 from being irradiated to the part other than the fixing belt 8, so that the fixing belt 8 can be effectively heated and energy saving can be achieved. Is convenient. Further, a heat insulating member 14 may be disposed between the reflecting plate 12 and the fixing belt 8 to further save energy. Further, a heating source 15 made of, for example, a halogen heater may be provided inside the pressure roller 52 to shorten the heating time.

  With the above configuration, when the fixing unit 51 is rotated clockwise in FIG. 2 by a drive source such as an electric motor (not shown), the pressure roller 52 is driven to rotate counterclockwise. Along with this, the fixing belt 8 is continuously circulated in the clockwise direction. At this time, the heating source 9 is turned on to irradiate the inner surface of the fixing belt 8, and the fixing belt 8 is heated by the radiant heat. The heating source 9 is controlled by a control means (not shown) so that the fixing belt 8 is in a predetermined fixing temperature range. When the fixing belt 8 reaches a predetermined fixing temperature range, a recording sheet P carrying an unfixed toner image is formed on the fixing nip N1 formed by the fixing means 51 and the pressure roller 52 via the fixing belt 8. It is nipped and conveyed in the nip extension region N2, heated and pressurized, and the unfixed toner image is fixed on the recording paper P.

  According to the present embodiment having the above configuration, the recording paper P is in the paper guide path L formed by the fixing belt 8 that circulates along the auxiliary guide member 10 disposed on the upstream side of the fixing nip N1. Then, it is guided along the fixing belt 8 to the fixing nip N1, and is pressurized and heated, and further, is sufficiently pressurized and heated by a nip extension region N2 formed continuously to the fixing nip N1. Therefore, a sufficient nip length for fixing can be ensured without increasing the size of the fixing means 51 that is a member to be heated.

  As a result, without increasing the size of this type of apparatus, a sufficient nip length is ensured to prevent the occurrence of fixing failure, and the fixing apparatus having excellent durability, and an image forming apparatus including the fixing apparatus are provided. Obtainable.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 4 is a conceptual diagram showing a schematic configuration of a fixing device according to a second embodiment of the present invention, FIG. 5 is a schematic perspective view showing an example of a guide assisting member of the fixing device shown in FIG. 4, and FIG. 5 is a schematic perspective view illustrating an example of a nip auxiliary member of the fixing device illustrated in FIG. 7 is a cross-sectional view showing an example of the rib portion of the guide assisting member shown in FIG. 5, and FIG. 8 is a cross-sectional view showing another example of the rib portion of the guide assisting member shown in FIG. 4 to 8, the portions denoted by the same reference numerals as those in FIGS. 1 to 3 described above are substantially the same, and thus detailed description thereof is omitted here. Hereinafter, the difference from the above-described embodiment will be mainly described.

  In the present embodiment, as shown in FIGS. 5 and 6, the guide auxiliary member 10 and the nip auxiliary member 11 are formed of resin, and on the surface of the guide auxiliary member 10 and the nip auxiliary member 11 facing the fixing belt 8, A rib 16 is provided that extends in the direction in which the fixing belt 8 slides and slides while the fixing belt 8 contacts. For example, as shown in FIG. 7, the rib 16 may be formed in a circular shape on the surface that the inner surface 82b of the fixing belt 8 slides while contacting, or in a trapezoidal shape as shown in FIG. You may do it.

  Further, rollers 17 for guiding the fixing belt 8 are provided in the vicinity of both end portions of the reflecting plate 12 to form a stable circulation path of the fixing belt 8 in the vicinity of the heating source 9. This configuration is preferable because non-uniform heating due to the deflection of the fixing belt 8 and the like can be prevented.

  According to the present embodiment having the above configuration, the recording paper P is circulated by the fixing belt 8 that circulates along the auxiliary guide member 10 disposed on the upstream side of the fixing nip N1, as in the above-described embodiment. In the formed sheet guide path L, the sheet is guided along the fixing belt 8 to the fixing nip N1, is pressurized and heated, and is further sufficiently provided by the nip extension region N2 formed continuously to the fixing nip N1. Pressurized and heated. Therefore, a sufficient nip length for fixing can be ensured without increasing the size of the fixing means 51 that is a member to be heated.

  Furthermore, since the heat capacities of the guide auxiliary member 10 and the nip auxiliary member 11 are extremely small, there is little energy loss. Further, since the sliding area between the guide assisting member 10 and the nip assisting member 11 and the fixing belt 8 is small, the transportability of the fixing belt 8 is improved, and the durability of the fixing belt 8 is further improved, which is convenient. . Further, the rib 16 of the nip assisting member 11 is further advantageous in that the elastic layer of the pressure roller 52 can be further distorted and the separation of the recording paper P can be improved.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 9 is a conceptual diagram showing a schematic configuration of a fixing device according to the third embodiment of the present invention. Note that, in FIG. 9, portions denoted by the same reference numerals as those in FIGS. 1 to 8 described above indicate substantially the same components, and thus detailed description thereof is omitted here. Hereinafter, the difference from the above-described embodiment will be mainly described.

  In the present embodiment, as shown in FIG. 9, the guide auxiliary member 10 and the nip auxiliary member 11 are composed of sufficiently small rollers having a diameter of about 1/5 to 1/20 of the diameter of the pressure roller 52. It is formed of a rotating body. The guidance assisting member 10 made of a rotating body forms a paper guide path L through which the recording paper P is guided along the fixing belt 8 inside the fixing belt 8 and upstream of the fixing nip N1. It is arranged. Further, the nip auxiliary member 11 made of a rotating body presses the fixing belt 8 to the pressure roller 52 side continuously to the fixing nip N1 inside the fixing belt 8 and downstream of the fixing nip N1. It arrange | positions so that nip extension area | region N2 may be formed.

  According to the present embodiment having the above configuration, the recording paper P is circulated by the fixing belt 8 that circulates along the auxiliary guide member 10 disposed on the upstream side of the fixing nip N1, as in the above-described embodiment. In the formed sheet guide path L, the sheet is guided along the fixing belt 8 to the fixing nip N1, is pressurized and heated, and is further sufficiently provided by the nip extension region N2 formed continuously to the fixing nip N1. Pressurized and heated. Therefore, a nip length sufficient for fixing can be secured without particularly increasing the size of the fixing means 51 which is a member to be heated.

  Furthermore, since the heat capacities of the guide auxiliary member 10 and the nip auxiliary member 11 are extremely small, there is little energy loss. Further, since the guide assisting member 10 and the nip assisting member 11 rotate as the fixing belt 8 slides, the transportability of the fixing belt 8 is further facilitated, and the durability of the fixing belt 8 is further improved. convenient.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a conceptual diagram showing a schematic configuration of a fixing device according to the fourth embodiment of the present invention. Note that, in FIG. 10, portions denoted by the same reference numerals as those in FIGS. 1 to 9 described above indicate substantially the same parts, and thus detailed description thereof is omitted here. Hereinafter, the difference from the above-described embodiment will be mainly described.

  In the present embodiment, as shown in FIG. 10, the fixing unit 51 is formed of a pressure pad made of a non-rotating elastic body or the like, and the fixing unit 51 made of the pressure pad and the pressure roller 52 A fixing nip N <b> 1 is formed via the fixing belt 8. The fixing means 51, the guide auxiliary member 10 that forms the paper guide path L, and the nip auxiliary member 11 that forms the nip extension region N2 are integrally formed by molding or the like.

  According to the present embodiment having the above configuration, the recording paper P is circulated by the fixing belt 8 that circulates along the auxiliary guide member 10 disposed on the upstream side of the fixing nip N1, as in the above-described embodiment. In the formed sheet guide path L, the sheet is guided along the fixing belt 8 to the fixing nip N1, is pressurized and heated, and is further sufficiently provided by the nip extension region N2 formed continuously to the fixing nip N1. Pressurized and heated. Therefore, a nip length sufficient for fixing can be secured without particularly increasing the size of the fixing means 51 which is a member to be heated.

  Furthermore, the fixing means 51 is a non-rotating pressure pad, so that the heat capacity can be reduced and the warm-up can be further shortened. Further, the pressure distribution from the upstream side to the downstream side before and after the fixing nip N1, the downstream side is strong, and a flat pressure distribution can be formed from the upstream side to the fixing nip N1, thereby improving the fixing property and the separation property. In addition, it can save space. Further, since the fixing means 51, the guide assisting member 10 and the nip assisting member 11 are integrally formed, the number of parts is reduced and the handling thereof is facilitated, which is convenient.

The above-described embodiment is a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.
For example, in the above-described embodiment, the copying machine has been described as an example. However, the present invention is not limited to, for example, a facsimile machine or a multifunction machine having various functions such as a copying function, a printer function, a scanner function, and a facsimile function. Is applicable.

  In the above-described embodiment, the drum-shaped photoconductor 41 is used. However, the shape of the photoconductor 41 is not limited, and a known shape other than the above-described drum shape can be used. Examples of the shape include a sheet shape, a belt shape, and a web shape.

  In the embodiment described above, the release layer 81 made of fluororesin is provided on the fixing belt 8, but this is not necessarily provided. For example, the elastic layer 83 made of silicone rubber may be used as the surface layer. Of course.

  In order to improve the releasability with the toner, a mechanism for applying a release agent made of, for example, silicone oil or the like may be separately provided on the surface of the fixing belt 8 in the circulation path of the fixing belt 8. Of course.

  Examples of the use of the present invention include a fixing device that heat-fixes an unfixed toner image carried on a recording paper using a fixing belt, and an image forming apparatus including the fixing device.

FIG. 1 is a schematic configuration diagram showing a schematic configuration when applied to a copying machine as an image forming apparatus using a fixing device according to a first embodiment of the present invention. FIG. 2 is a conceptual diagram illustrating a schematic configuration of the fixing device illustrated in FIG. 1. FIG. 3 is an enlarged cross-sectional view illustrating an example of a fixing belt of the fixing device illustrated in FIG. 2. FIG. 6 is a conceptual diagram illustrating a schematic configuration of a fixing device according to a second embodiment of the present invention. FIG. 5 is a schematic perspective view illustrating an example of a guide assisting member of the fixing device illustrated in FIG. 4. FIG. 5 is a schematic perspective view illustrating an example of a nip auxiliary member of the fixing device illustrated in FIG. 4. It is sectional drawing which shows an example of the rib part of the guidance auxiliary member shown in FIG. It is sectional drawing which shows the other example of the rib part of the guidance assistance member shown in FIG. FIG. 10 is a conceptual diagram illustrating a schematic configuration of a fixing device according to a third embodiment of the present invention. FIG. 10 is a conceptual diagram illustrating a schematic configuration of a fixing device according to a fourth embodiment of the present invention.

Explanation of symbols

L ... paper guide path, P ... recording paper, N1 ... fixing nip, N2 ... nip extension region, 5 ... fixing device, 8 ... fixing belt, 9 ... heating source, 10 ... guide auxiliary member, 11 ... nip auxiliary member, 12 ... reflector, 16 ... rib, 51 ... fixing means, 52 ... pressure roller

Claims (9)

An endless fixing belt to be heated, a fixing unit disposed inside the fixing belt, a fixing nip disposed in opposition to the fixing unit and in cooperation with the fixing unit via the fixing belt. And a heating source that directly heats the fixing belt in a non-contact manner in order to fix an unfixed toner image carried on a recording paper held and conveyed by the fixing nip. In the fixing device
A guide auxiliary member is disposed on the inner side of the fixing belt so as to form a paper guide path along which the recording paper is guided along the fixing belt on the upstream side of the fixing nip. On the downstream side, a nip auxiliary member that presses the fixing belt toward the pressure roller is disposed inside the fixing belt so as to form a nip extension region continuously with the fixing nip. A fixing device characterized.   The pressure roller further includes an elastic layer, and the nip auxiliary member is formed to strongly press the fixing belt locally toward the pressure roller near the exit of the nip extension region. The fixing device according to claim 1.   The paper guide path is disposed close to the recording paper carry-in path, and is configured to form a preheating region for preheating the recording paper by the fixing belt. The fixing device according to claim 1.   4. The reflector plate for reflecting radiant heat from the heating source to the fixing belt side is disposed between the heating source and the fixing unit. 5. The fixing device described.   The guide auxiliary member and / or the nip auxiliary member are made of resin and extend in a direction in which the fixing belt slides on a surface of the guide auxiliary member and / or nip auxiliary member facing the fixing belt. 5. The fixing device according to claim 1, further comprising a rib that slides while the fixing belt is in contact with the fixing belt.   5. The fixing device according to claim 1, wherein the guide assisting member and / or the nip assisting member is formed of a rotating body that is sufficiently smaller than a pressure roller.   The fixing device according to claim 1, wherein the fixing unit, the guide auxiliary member, and the nip auxiliary member are integrally formed.   The fixing device according to claim 1, wherein the fixing unit is formed of a non-rotating pressure pad.   An image forming apparatus comprising the fixing device according to claim 1.

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