JP2015001682A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of improving thermal efficiency in heating operation of a heating member to a fixing belt, and to provide an image forming apparatus including the fixing device.SOLUTION: A fixing device 6a comprises a heater 10 for heating a recording material and a pressurizer 20 for holding and conveying the heater and the recording material. The heater 10 includes: a first fixing belt 11 which can be turned; a second fixing belt which is arranged at the inside of the first fixing belt 11 and is configured so that a part of its outer peripheral surface abuts on an inner peripheral surface of the first fixing belt 11; a heating member 14 which is arranged at the inside of the first fixing belt 11 and at the outside of the second fixing belt 12; and a pressing member 13 for holding the first and second fixing belts 11, 12 between the member 13 and the heater 20 by pressing the first and second fixing belts 11, 12 to the heater 20 in a contact position of the first and second fixing belts 11, 12.

Description

  The present invention relates to a fixing device for fixing the toner image on the recording material by passing the recording material on which the toner image has been transferred through a fixing nip region formed between a heater and a pressure device. The present invention relates to an image forming apparatus comprising:

  Conventionally, in an image forming apparatus adopting an electrophotographic method, a recording paper on which an unfixed toner image is transferred is conveyed to a fixing nip region between a heater heated by a heat source and a pressurizer in contact with the heater. It is widely performed to fix an unfixed toner image on a recording sheet by heating and pressurizing. As a fixing device for fixing the toner on the recording paper, a fixing device that heats the fixing belt by a heating means such as a halogen heater or a ceramic heater and presses the recording paper simultaneously with the fixing belt is conventionally used. It is used. In the fixing device using the fixing belt as described above, an energy-saving and low-cost device is realized by using a thin belt having a small heat capacity as the fixing belt.

  In a fixing device having a configuration in which the fixing belt is heated by a heating member, a device provided with a reflecting member for reflecting radiant heat from a halogen heater as a heating member has been proposed in order to increase the heating efficiency of the heating member ( Patent Document 1). Similarly, in order to increase the heating efficiency of the heating member in the fixing device, a configuration has been proposed in which the heating member is coated to block heat from the pressing member that presses the fixing belt from the inside (Patent Document 2). reference).

Japanese Patent Laying-Open No. 2005-092080 JP 2008-145903 A

  However, although the fixing device in Patent Document 2 is configured to block the radiant heat to the pressing member, the radiant heat in the blocked region is not used for heating the fixing belt. The fixing device in Patent Document 1 is configured such that radiant heat from a region on the back side of the fixing belt reaches the fixing belt indirectly by the reflecting member, but the reflecting member slides on the fixing belt. Therefore, heat loss from the fixing belt to the reflecting member occurs.

  In view of such a problem, an object of the present invention is to provide a fixing device capable of improving the thermal efficiency in the heating operation of the fixing belt by the heating member, and an image forming apparatus including the fixing device.

  In order to achieve the above object, the fixing device of the present invention is a fixing device comprising a heater for heating a recording material, and a pressure device for sandwiching and conveying the heater and the recording material, A first fixing belt that is rotatable; and a second fixing belt that is disposed inside the first fixing belt, and a part of an outer peripheral surface of which is in contact with an inner peripheral surface of the first fixing belt; The pressing member is pressed against the pressure device at a contact position between the first fixing belt and a heating member disposed inside the first fixing belt and outside the second fixing belt. And a pressing member for sandwiching the first and second fixing belts with the pressurizer.

  In such a fixing device, a heating layer that absorbs heat from the heating member is provided on each of the inner peripheral surface of the first fixing belt and the outer peripheral surface of the second fixing belt. Further, a sliding layer having slidability is provided on the inner surface of the second fixing belt and the inner surface of the second fixing belt of the pressing member. Further, a release layer having slidability is provided on the outer peripheral surface of the first fixing belt.

  These fixing devices further include a first temperature detection unit that measures the temperature of the first fixing belt and a second temperature detection unit that measures the temperature of the second fixing belt. When at least one of the temperatures of the first and second fixing belts measured by the two temperature detectors exceeds a target temperature set for each of the first and second fixing belts, the heating operation by the heating member You may stop it.

  In the above-described fixing device, when the temperature of the second fixing belt is measured at a plurality of locations, and the temperature difference of the second fixing belt measured at the plurality of locations is greater than a predetermined value, the heating member The heating operation may be stopped.

  An image forming apparatus of the present invention is an image forming apparatus comprising: a transfer unit that transfers a toner image onto a recording paper; and a fixing unit that pressurizes the recording paper on which the toner image has been transferred by the transfer unit while heating. The fixing unit is constituted by any one of the fixing devices described above.

  According to the present invention, since the first and second fixing belts can absorb the radiant heat from the heating member, the heat from the heating member can be efficiently utilized without waste. Power consumption can be suppressed. Further, since the second fixing belt exists between the heating member and the pressing member, it is possible to prevent the heat from the heating member from being absorbed by the pressing member, so that the heating efficiency can be further increased. Further, since the heating layer of the second fixing belt is formed on the outer peripheral surface of the second fixing belt, the heating layer of the second fixing belt can be prevented from coming into contact with the pressing member.

FIG. 2 is an external perspective view of the image forming apparatus of the present invention. FIG. 2 is a schematic configuration diagram illustrating an internal configuration of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a schematic perspective view illustrating a configuration of a fixing device in the image forming apparatus according to the first exemplary embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of a heater in the fixing device of FIG. 3. FIG. 4 is a schematic diagram illustrating an example of a configuration of a pressing member in the fixing device of FIG. 3. FIG. 4 is a schematic view showing another example of the configuration of the pressing member in the fixing device of FIG. 3. FIG. 4 is a schematic sectional view showing an end configuration in the fixing device of FIG. 3. FIG. 4 is a diagram showing a configuration of an end regulating member used in the fixing device of FIG. 3. FIG. 4 is a schematic perspective view illustrating a configuration of a fixing device in an image forming apparatus according to a second embodiment of the present invention. These are the schematic sectional drawings which show the structure of the another example 1 of the support structure in the fixing device of this invention. These are figures which show the structure of the edge part limitation member in the support structure of FIG. These are the schematic sectional drawings which show the structure of the another example 2 of the support structure in the fixing device of this invention. These are figures which show the structure of the edge part limitation member in the support structure of FIG. These are the schematic sectional drawings which show the structure of the another example 3 of the support structure in the fixing device of this invention. These are figures which show the structure of the edge part control member in the support structure of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, when using terms indicating a specific direction or position (for example, “left / right”, “up / down”, etc.) as necessary, the direction orthogonal to the paper surface in FIG. I have to. These terms are used for convenience of explanation, and do not limit the technical scope of the present invention.

<Overall configuration of image forming apparatus>
An overall configuration of an image forming apparatus common to the following embodiments will be described with reference to the drawings. FIG. 1 is an external perspective view of an image forming apparatus according to the present invention, and FIG. 2 is a schematic diagram illustrating an internal configuration of the image forming apparatus.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 includes an image reading unit 3 that reads an image from a document P 1, a paper feed tray 4 that stores recording paper P 2 on which an image is formed, and a paper feed tray 4. A transfer unit 5 that transfers the toner image to the fed recording paper P2, a fixing unit 6 that fixes the toner image transferred by the transfer unit 5 to the recording paper P2, and a fixing unit 6 that fixes the image to form an image. A paper discharge tray 7 on which the recording paper P2 is discharged, and an operation panel 9 for receiving operations on the image forming apparatus 1. In the image forming apparatus 1, an image reading unit 3 is provided on the upper part of the apparatus main body 2, and a transfer unit 5 is provided below the image reading unit 3.

  A paper discharge tray 7 is provided on the upper side of the transfer unit 5 in the apparatus main body 2 to receive the recording paper P2 that has been image-recorded and discharged by the transfer unit 5 and the fixing unit 6, and the paper feed tray 4 However, it is configured to be insertable / removable below the transfer portion 5 in the apparatus main body 2. With such a configuration, as will be described later, the recording paper P2 stored in the paper feed tray 4 is fed into the apparatus main body 2 and then transported upward, whereby the upper portion of the paper feed tray 4 is After the image is transferred by the transfer unit 5 disposed in the image and fixed by the fixing unit 6, the image is discharged onto a discharge tray 7 provided in a space (a recessed space) between the image reading unit 3 and the transfer unit 5. Is done.

  The image reading unit 3 provided on the upper part of the apparatus main body 2 includes a scanner unit 31 that reads an image from the document P1, and an automatic document conveyance unit that is provided on the scanner unit 31 and conveys the document P1 to the scanner unit 31 one by one. (ADF: Auto Document Feeder) 32. An operation panel 9 is provided on the front side (front side) of the apparatus main body 2. Then, the user performs a key operation while looking at the display screen of the operation panel 9 to perform a setting operation for a function selected from the various functions of the image forming apparatus 1 or execute an operation on the image forming apparatus 1. Can be instructed.

  Next, the internal structure of the apparatus main body 2 will be described with reference to FIG. Of the image reading unit 3 in the upper part of the apparatus main body 2, the scanner unit 31 includes a document table 33 having a platen glass (not shown) on the upper surface side, a light source unit 34 that emits light to the document P1, and a document P1. The image sensor 35 that photoelectrically converts the reflected light from the image into image data, the imaging lens 36 that forms an image of the reflected light on the image sensor 35, and the reflected light from the original P1 are sequentially reflected and incident on the imaging lens 36. And a mirror group 37 to be operated. The light source unit 34, the image sensor 35, the imaging lens 36, and the mirror group 37 are provided inside the document table 33, and the light source unit 34 and the mirror group 37 are configured to be movable in the left-right direction with respect to the document table 33. .

  An ADF 32 is provided on the upper surface side of the scanner unit 31 so as to be openable and closable with respect to the document table 33. The ADF 32 also has a function of bringing the document P1 into close contact with the platen glass (not shown) by covering the document P1 on the platen glass (not shown) of the document table 33. The ADF 32 includes a document placement tray 38 and a document discharge tray 39.

  When the image reading unit 3 having such a configuration reads a document P1 on a platen glass (not shown) of the document table 33, light is irradiated to the document P1 from the light source unit 34 that moves in the right direction (sub-scanning direction). Is done. The reflected light reflected from the document P1 is sequentially reflected by a mirror group 37 that moves in the right direction as in the light source unit 34, enters the imaging lens 36, and forms an image on the image sensor 35. The image sensor 35 performs photoelectric conversion for each pixel according to the intensity of incident light, and generates an image signal (RGB signal) corresponding to the image of the document P1.

  On the other hand, when reading the document P1 placed on the document placement tray 38, the document P1 is transported to the reading position by the document transport mechanism 40 including a plurality of rollers or the like. At this time, the light source unit 34 and the mirror group 37 of the scanner unit 31 are fixed at predetermined positions inside the document table 33. Therefore, the light source unit 34 irradiates the reading position portion of the document P1 with light, and the reflected light is imaged on the image sensor 35 via the mirror group 37 and the imaging lens 36 of the scanner unit 31. Then, the image sensor 35 converts the image signal (RGB signal) corresponding to the image of the document P1. Thereafter, the document P1 is discharged to the document discharge tray 39.

  The transfer unit 5 that transfers the toner image to the recording paper P2 includes an image forming unit 51 that generates toner images of Y (Yellow), M (Magenta), C (Cyan), and K (Key tone) colors, and an image forming unit. 51, an intermediate transfer belt 53 to which a toner image of each color is transferred from the image forming unit 51 by contacting an exposure unit 52 provided below each of the image forming units 51, an image forming unit 51 of each color arranged in the horizontal direction, and an image forming unit. A primary transfer roller 54 provided at a position facing the upper side with respect to each image forming unit 51 of each color so as to sandwich the unit 51 and the intermediate transfer belt 53, a drive roller 55 for rotating the intermediate transfer belt 53, and A driven roller 56 that rotates when the rotation of the driving roller 55 is transmitted through the intermediate transfer belt 53, a secondary transfer roller 57 that is installed at a position facing the driving roller 55 across the intermediate transfer belt 53, and intermediate transfer And a cleaner unit 58 which is installed in a position facing the driven roller 56 across the belt 53, provided.

  The image forming unit 51 includes a photosensitive drum 61 that is in contact with the outer circumferential surface of the intermediate transfer belt 53, a charger 62 that charges the outer circumferential surface of the photosensitive drum 61 by corona discharge, and a toner that is charged by stirring. A developing unit 63 that adheres to the outer peripheral surface of the drum 61 and a cleaner unit 64 that removes toner remaining on the outer peripheral surface of the photosensitive drum 61 after the toner image is transferred to the intermediate transfer belt 53 are provided. At this time, the photosensitive drum 61 is installed at a position facing the primary transfer roller 54 with the intermediate transfer belt 53 interposed therebetween, and rotates in the clockwise direction in FIG. Around the photosensitive drum 61, a primary transfer roller 54, a cleaner unit 64, a charger 62, an exposure unit 52, and a developing unit 63 are sequentially arranged along the rotation direction of the photosensitive drum 61. Yes.

  Further, the intermediate transfer belt 53 is composed of an endless belt member having conductivity, for example, and is wound around the drive roller 55 and the driven roller 56 without loosening, so that the intermediate transfer belt 53 is rotated according to the rotation of the drive roller 55 as shown in FIG. In the counterclockwise direction. Around the intermediate transfer belt 53, the secondary transfer roller 57, the cleaner unit 58, and the image forming units 51 for each color of YMCK are arranged in order along the rotation direction of the intermediate transfer belt 53.

  Further, the fixing unit 6 that fixes the toner image transferred to the recording paper P2 includes a heater 59 that heats the toner image on the recording paper P2 and fixes the recording paper P2 together with the heater 59. And a pressurizer 60 that pressurizes P2.

  The paper feed mechanism 8 is separated by a feed roller 81 that feeds the recording paper P2 stored in the paper feed tray 4 from the uppermost layer, and a paper feed roller 82 and a separation roller 83 that separate the fed recording paper P2 one by one. A pair of rollers. The recording paper P2 in each paper feed tray 4 is rotated one by one from the top layer by the rotation of the corresponding feed roller 81, paper feed roller 82 and paper roller 83, and the main transport path R0 via the paper feed path R1. It is sent out toward. The main transport path R0 is the main path of the recording paper P2 that has undergone the image forming (printing) process. In addition, a paper feed path R1 is provided for each paper feed tray 4, and each paper feed path R1 joins the main transport path R0.

  A manual feed tray 93 capable of feeding a predetermined size of recording paper P2 from the outside is provided on one side portion (right side portion in the embodiment) of the apparatus main body 2 in the left-right direction. The manual feed tray 93 is supplementarily provided separately from the normal paper feed tray 4 in the apparatus main body 2, and is attached to the left and right sides of the apparatus main body 2 so as to be openable and closable. ing. The recording paper P2 on the manual feed tray 93 is sent one by one from the uppermost layer toward the main transport path R0 via the manual feed path R2 by rotation driving of a feed roller or the like.

  A discharge roller pair 91 for discharging the printed recording paper P2 is disposed in the main transport path R0 on the downstream side of the fixing unit 6 by the heater 59 and the pressure device 60. The printed recording paper P <b> 2 is discharged to the paper discharge tray 7 by the rotational drive of the paper discharge roller pair 91.

  Further, in the apparatus main body 2 of the image forming apparatus 1 configured as described above, there is further provided a circulation conveyance unit 92 for performing double-sided printing by reversing the recording paper P2 after single-sided printing. . The circulation conveyance unit 92 includes a pair of reversing rollers for reversing the recording paper P2 after single-sided printing, and a plurality of pairs of double-sided conveyance rollers. In the circulation conveyance unit 92, the recording paper P2 after single-sided printing is turned upside down and conveyed again to the main conveyance path R0 via the circulation conveyance path R3. In this case, the discharge roller pair 91 is configured to be capable of rotating in the forward and reverse directions, so that the discharge roller pair 91 also functions as a reverse roller pair. The recording paper P2 can be discharged out of the image forming apparatus 1 by the forward / reverse rotation of the paper discharge roller pair 91, or returned to the image forming apparatus 1 by switching back (reverse feeding). The upstream side of the circulation conveyance path R3 branches from between the fixing unit 6 and the paper discharge roller pair 91 in the main conveyance path R0. The downstream side of the circulation conveyance path R3 joins the upstream side of the transfer unit 5.

  A printing operation by the image forming apparatus 1 will be briefly described. The image forming apparatus 1 receives a start signal, an image signal, and the like and starts a printing operation. When the printing operation starts, the recording paper P2 fed from the paper feed tray 4 by the paper feed mechanism 8 is transported to the transfer unit 5 along the main transport path R0. The transfer unit 5 and the fixing unit 6 transfer and fix an image on the recording paper P2 based on the color electrophotographic method, respectively, and an intermediate transfer method using an intermediate belt 53 is used as an image transfer method to the recording paper P2. adopt.

  At this time, in the transfer unit 5, the Y, M, C, and K color image forming unit 51 irradiates the surface of the photosensitive drum 61 charged by the charger 62 with laser light from the exposure unit 52. An electrostatic latent image corresponding to each color image is formed. The toner charged by the developing device 63 is transferred to the surface of the photosensitive drum 61 on which the electrostatic latent image is formed, and a toner image is formed on the photosensitive drum 61. The toner image carried on the surface of the photosensitive drum 61 is transferred to the intermediate transfer belt 53 by the electrostatic force of the primary transfer roller 54 when coming into contact with the intermediate transfer belt 53. In addition, a toner image in which the colors Y, M, C, and K are overlapped is formed. On the other hand, the untransferred toner remaining on the photosensitive drum 61 having the toner image transferred to the intermediate transfer belt 53 is scraped off by the cleaner unit 64 and removed from the photosensitive drum 61.

  The toner image transferred to the intermediate transfer belt 53 is moved to the transfer position where the intermediate transfer belt 53 contacts the secondary transfer roller 57 by the rotation of the intermediate transfer belt 53 by the driving roller 55 and the driven roller 56, and on the main transport path R0. It is transferred to the recording paper P2 conveyed to the transfer position. Untransferred toner remaining on the intermediate transfer belt 53 that has transferred the toner image onto the recording paper P <b> 2 is scraped off by the cleaner unit 58 and removed from the intermediate transfer belt 53. In addition, the recording paper P2 on which the toner image is transferred at the contact position with the secondary transfer roller 57 is conveyed to the fixing unit 6 by the heater 59 and the pressurizer 60.

  The recording paper P2 on which the unfixed toner image is placed on one side is heated by the heater 59 and pressurized by the pressurizer 60 when passing through the fixing position of the fixing unit 6, and the unfixed toner image is applied to the paper surface. It is fixed. In the case of single-sided printing, the recording paper P <b> 2 after toner image fixing (after single-sided printing) is discharged to the paper discharge tray 7 by the paper discharge roller pair 91. On the other hand, in the case of duplex printing, the recording sheet P2 after single-sided printing is conveyed to the circulation conveyance path R3 for duplex printing, turned over, and returned to the main conveyance path R0, so that each of the transfer unit 5 and the fixing unit 6 is restored. After the toner image is transferred and fixed on the other surface of the recording paper P2 that passes, the toner image is discharged to the paper discharge tray 7.

  The image forming apparatus according to each of the following embodiments has the configuration of the above-described image forming apparatus 1 in common, and the configuration of the fixing device serving as the fixing unit 6 in the image forming apparatus 1 is different. . Accordingly, in each of the following embodiments, the configuration of the fixing device used as the fixing unit 6 in the image forming apparatus 1 will be described in detail.

<First Embodiment>
The image forming apparatus according to the first embodiment of the present invention will be described below with reference to the drawings, focusing on the configuration of the fixing unit. FIG. 3 is a schematic cross-sectional view illustrating a configuration of a fixing device that serves as a fixing unit in the image forming apparatus according to the present exemplary embodiment.

  As shown in FIG. 3, the fixing device 6 a in the present embodiment functions as a fixing unit 6 (see FIG. 2) of the image forming apparatus 1, and is a double endless belt first and second fixing belt. 11 and 12 and a pressing member 13 that presses the first and second fixing belts 11 and 12, and a pressure that presses the pressing member 13 via the first and second fixing belts 11 and 12. A pressurizer 20 including a roller 21. That is, when the fixing device 6 a functions as the fixing unit 6, the fixing device 6 a heats the recording paper P <b> 2 in the fixing nip region where the first fixing belt 11 on the outer peripheral side of the heater 10 contacts the outer peripheral surface of the pressure roller 21. Pressurize to fix the transferred toner image. The heater 10 and the pressurizer 20 correspond to the heater 59 and the pressurizer 60 (see FIG. 2) in the image forming apparatus 1 described above, respectively.

  In the heater 10 of the fixing device 6 a, the inner peripheral surface of the inner second fixing belt 12 contacts the pressing member 13, and the inner peripheral surface of the first fixing belt 11 contacts the inner side at a position contacting the pressing member 13. The second fixing belt 12 comes into contact with the outer peripheral surface. As a result, the first and second fixing belts 11 and 12 are held in the fixing nip region by the pressing member 13 inside the second fixing belt 12 and the pressure roller 21 outside the first fixing belt 11. .

  In addition, the inner diameter of the first fixing belt 11 is larger than the outer diameter of the second fixing belt 12, and there is a sufficient space inside the first fixing belt 11 and outside the second fixing belt 12. Further, a heating member 14 such as a halogen heater or a ceramic heater is installed. That is, the heating member 14 is disposed inside the first fixing belt 11 on the opposite side of the pressing member 13 with the second fixing belt 12 interposed therebetween. Accordingly, the heating member 14 heats the first fixing belt 11 from the inner peripheral surface thereof, and simultaneously heats the second fixing belt 12 from the outer peripheral surface thereof.

  As shown in the enlarged sectional view of FIG. 4, the first fixing belt 11 has an elastic layer 112 and a release layer on the outer peripheral surface of a cylindrical base material 111 made of a metal or resin material having heat resistance, strength and flexibility. While the layers 113 are sequentially stacked, the heating layer 114 is stacked on the inner peripheral surface of the base material 111. As the material of the base material 111, for example, a metal material such as nickel, aluminum, or SUS, or a heat resistant resin such as polyimide (PI) resin or polyphenylene sulfide (PPS) resin is desirable. And it is preferable that the thickness of the base material 111 shall be about 30-100 micrometers according to the material intensity | strength.

  The elastic layer 112 is made of a rubber material having high heat resistance such as silicone rubber or fluororubber. For example, the elastic layers made of different materials may be made up of three or more layers. At this time, the elastic layer 112 preferably has an elastic modulus of about 0.03 to 100 MPa, and preferably has a thickness of 50 to 100 μm. The release layer 113 laminated on the outer peripheral side of the elastic layer 112 is, for example, PFA (tetrafluoroethylene / perfluoroalkoxyethylene copolymer), PTFE (tetrafluoroethylene), FEP (tetrafluoroethylene · It is constituted by a fluorine-based tube or a fluorine-based coating with a fluorine resin such as hexafluoroethylene copolymer) or PFEP (tetrafluoroethylene / hexafluoropropylene copolymer). At this time, the release layer 113 preferably has a thickness of 10 to 70 μm.

  Furthermore, the heating layer 114 is preferably a material that easily absorbs light in the range from infrared to visible light and has a high friction coefficient. For example, graphite, carbon nanotubes, or these materials are dispersed and mixed. It is composed of a heat resistant resin such as a polyimide resin. The heating layer 114 is preferably applied to the inner peripheral surface of the base material 111 so that the surface thereof is not glossy in order to easily absorb visible light and radiant heat from the heating member 14. The thickness is preferably 5 to 70 μm.

  As shown in the enlarged sectional view of FIG. 4, the second fixing belt 12 has a sliding layer 122 on the inner peripheral surface of a cylindrical base material 121 made of a metal or resin material having heat resistance, strength, and flexibility. On the other hand, the heating layer 123 is laminated on the outer peripheral surface of the substrate 121. That is, the heating layer 123 of the second fixing belt 12 is in contact with the heating layer 114 of the first fixing belt 11 in the fixing nip region. At this time, the substrate 121 is similar to the substrate 111 of the first fixing belt 11, such as a metal material such as nickel, aluminum, or SUS, or a heat-resistant resin such as polyimide (PI) resin or polyphenylene sulfide (PPS) resin. For example, the thickness of nickel is 40 μm.

  The sliding layer 122 laminated on the inner peripheral surface of the base material 121 is made of a material having high slidability such as a fluorine-based coating with a fluorine resin similar to the release layer 113. At this time, for example, the sliding layer 122 is formed on the inner peripheral surface of the substrate 121 by a fluororesin such as PTFE having a thickness of 30 μm. Further, like the heating layer 114, the heating layer 123 is preferably a material that easily absorbs light in the range from infrared rays to visible light and has a high friction coefficient, and the surface of the substrate 121 is not glossy on its surface. It is applied to the outer peripheral surface. At this time, for example, a heat-resistant resin such as a polyimide resin in which graphite fibers are dispersed and mixed is applied to the outer peripheral surface of the base 121 to form a heating layer 123 having a thickness of 10 μm.

  As shown in FIG. 3, the pressing member 13 disposed inside the second fixing belt 12 having the above-described configuration includes a pad base layer 131 that is in contact with the inner peripheral surface of the second fixing belt 12, and the pad base layer 131 is used as a pressurizer. It is comprised by the press part holding member 132 hold | maintained so that it may press to 20 side. Then, as shown in FIG. 4, the pad base layer 131 is a slide having heat resistance and slidability on the surface of the base material 133 on the second fixing belt 12 side made of a metal or resin material having heat resistance. The layer 134 is provided. In such a pressing member 13, for example, polyphenylene sulfide (PPS) resin having heat resistance is used as a constituent material of the base material 133 and the pressing portion holding member 132 of the pad base layer 131.

  Further, as shown in FIG. 5, the sliding layer 134 may be configured by coating the surface of the pad base layer 131 on the second fixing belt 12 side with a fluorine resin such as PFA or PTFE. At this time, for example, the sliding layer 134 is formed by coating 30 μm of PTFE on the surface of the pad base layer 131. In addition to the above fluororesin coating, as shown in FIG. 6, a sliding sheet 134 a in which a sliding material is applied or impregnated on the surface is attached to the outer peripheral surface of the pad base layer 131. The sliding layer 134 may be configured.

  Then, in order to control the heating temperature by the heater 10 to an optimum value, as shown in FIG. 3, the heater 10 notifies the first and second fixing belts 11 and 12 of the respective temperatures. 2 A temperature control unit 25 is provided that includes the temperature detection units 15 and 16 and controls the heating operation by the heating member 14. At this time, the first temperature detecting unit 15 is disposed outside the first fixing belt 11 and upstream of the fixing nip region along the conveyance direction of the recording paper P2, and the temperature of the outer peripheral surface of the first fixing belt 11 is set. Is detected. On the other hand, the second temperature detection unit 16 is disposed inside the second fixing belt 12 at a position facing the heating member 14 and detects the temperature of the inner peripheral surface of the second fixing belt 12. That is, the second temperature detection unit 16 is placed on the surface of the pressing member holding member 132 on the heating member 14 side, and detects the temperature of the inner peripheral surface of the second fixing belt 12 facing the second temperature detection unit 16.

  With this configuration, the first temperature detection unit 15 measures the temperature of the outer peripheral surface of the first fixing belt 11 upstream of the fixing nip region in the conveyance direction, and the second temperature detection unit 16 performs heating. The temperature of the inner peripheral surface of the second fixing belt at the position facing the member 14 is measured. When the temperatures of the first and second fixing belts 11 and 12 detected by the temperature detectors 15 and 16 are given to the temperature controller 25, the temperature controller 25 causes the first and second fixing belts 11 and The heating operation of the heating member 14 is controlled so that the temperature of each of the 12 is within a predetermined range. Each of the first and second temperature detection units 15 and 16 is configured by a non-contact temperature sensor such as a thermistor, a thermopile, or a multi-array thermopile.

  As shown in FIGS. 3 and 4, the pressure roller 21 that constitutes the pressure device 20 includes a configuration in which an outer peripheral surface of a cored bar 22 is covered with an elastic layer 23 and a release layer 24 in order. The cored bar 22 is made of a metal material such as aluminum or iron, and the thickness is preferably about 0.1 mm to 5 mm. The elastic layer 23 is made of an elastic material having heat resistance such as silicone rubber or silicone sponge, and the thickness thereof is preferably in the range of 1 mm to 20 mm. Furthermore, the release layer 24 is made of a material having release properties, heat resistance, and gas barrier properties, such as a fluororesin, and the thickness is preferably in the range of 5 μm to 100 μm. Since the pressure hardness of the pressure roller 21 is larger than the surface hardness of the pressing member 13, the pressing member 13 has a concave shape in the fixing nip region N1, while the pressure roller 21 has a convex shape.

  The support structures of the heater 10 and the pressurizer 20 will be described below with reference to FIGS. 7 and 8. As shown in FIG. 7, the heater 10 includes the first and second fixing belts 11, 12 in order to restrict the positions of the both ends of the first and second fixing belts 11, 12. The second fixing belts 11 and 12 are in contact with the respective end portions. The end regulating member 151 has a ring shape as shown in FIG. 8, and abuts against both the first and second fixing belts 11 and 12 in an area X1 sandwiching the fixing nip area, while other than the area X1. In the region, only the first fixing belt 11 contacts. With such a configuration of the end regulating member 151, the axial displacement of the first and second fixing belts 11 and 12 is regulated.

  In addition, the end regulating member 151 protrudes toward the first and second fixing belts 11 and 12 along the axial direction on the contact surface with the first and second fixing belts 11 and 12 along the axial direction. With this shape, the inner side of the protrusion 150 comes into contact with the outer peripheral surface of the first fixing belt. That is, since the protrusion 150 of the end regulating member 151 regulates the position of the outer peripheral surface of the first fixing belt 11, each of the first and second fixing belts 11, 12 is moved outward by the end regulating member 151. It is regulated so as not to spread.

  The end regulating member 151 is fixed to the holding metal plate 153 together with the heating unit holding member 152 that holds the heating member 14 of the heater 10 and the pressing unit holding member 132 of the pressing unit 13. That is, the end regulating member 151 is fixed to the surface of the holding metal plate 153 on the heater 10 side, and the holding metal plate 153 is installed outside both ends of the first and second fixing belts 11 and 12. As a result, the first and second fixing belts 11 and 12 are held between the end regulating members 151 fixed to the holding metal plate 153 outside the both ends. The holding metal plate 153 has a bearing 154 into which the core metal 22 of the pressure roller 21 is inserted, and rotatably supports the pressure roller 21.

  When the heating roller 10 and the pressurizer 20 are supported in this manner and the pressure roller 21 of the pressurizer 20 is rotated, the end portion regulating member 151 is regulated in conjunction with the rotation of the pressure roller 21. The first fixing belt 11 rotates at the position. In the heater 10, the second fixing belt 12 rotates following the rotation of the first fixing belt 11 based on the rotation of the pressure roller 21. As a result, the heating layer 114 on the inner peripheral surface of the first fixing belt 11 heated by the heater 10 moves to the fixing nip region, and at the same time, the inner peripheral surface of the second fixing belt 12 similarly heated by the heater 10. The heating layer 123 moves to the fixing nip region. Therefore, in the fixing nip region, the heated layers 114 and 123 of the heated fixing belts 11 and 12 pass while being sandwiched between the pressing member 13 and the heating roller 22.

  The temperature control operation of the heater 10 in the fixing device 6a configured as described above will be described below. As shown in FIG. 3, the temperature control unit 25 turns on the switch SW1, supplies power from the power source 26 to the heating member 14, starts the heating operation by the heating member 14, and then performs first and second temperature detections. The measurement signals from the units 15 and 16 are received. Accordingly, the temperature control unit 25 confirms the temperatures Ta and Tb of the first and second fixing belts 11 and 12 detected by the first and second temperature detection units 15 and 16, respectively.

  While the heating operation by the heating member 14 is being performed, the temperature control unit 25 determines that the recognized temperatures of the first and second fixing belts 11 and 12 are different from those of the first and second fixing belts 11 and 12, respectively. It is determined whether or not the set temperatures T1 and T2 have been exceeded. Then, when the temperature T1 of the first fixing belt 11 exceeds the set temperature Ta, or when the temperature T2 of the second fixing belt 12 exceeds the set temperature Ta, the temperature control unit 25 switches the switch SW1. Is turned OFF, the power supply from the power supply 26 to the heating member 14 is stopped, and the heating operation of the heating member 14 is stopped.

  After stopping the heating operation of the heating member 14, it is confirmed whether or not both the temperatures Ta and Tb of the first and second fixing belts 11 and 12 are lower than the set temperatures T1 and T2, respectively. When the temperature Ta of the first fixing belt 11 falls below the set temperature T1 and the temperature Tb of the second fixing belt 12 falls below the set temperature T2, the temperature control unit 25 turns on the switch SW1 and turns on the power supply 26. Power supply to the heating member 14 is started, and the heating operation of the heating member 14 is restarted.

  As described above, the temperature control unit 25 controls the contact / separation of the switch SW1, thereby controlling the heating operation of the heating member 14, and the temperatures of the first and second fixing belts 11 and 12 are set to the set temperatures T1 and T2. The heating temperature by the heater 10 can be controlled so as not to exceed the higher heat resistant temperature T. At this time, when the heat resistance temperature T of each of the first and second fixing belts 11 and 12 is 240 ° C., for example, the set temperature T 1 of the first fixing belt 11 is 180 ° C. and the set temperature T 2 of the second fixing belt 12 is set. The set temperatures T1 and T2 are set to a temperature lower than the heat resistant temperature T so as to be 200 ° C.

  As in the present embodiment, the heater 10 of the fixing device 6 a includes the first and second fixing belts 11 and 12, so that the radiant heat from the heating member 10 is converted into the first and second fixing belts 11. 12 can be used for heating operation of the recording paper P2 in the fixing nip region. Therefore, since the heat from the heating member 10 can be utilized efficiently, the heating operation of the heating member 10 can be performed without waste, and the power consumption in the heating operation can be suppressed.

  Further, since the heating member 14 is disposed outside the second fixing belt 12 and the pressing member 13 is disposed inside the second fixing belt 12, the pressing member 13 is directly heated by the heating member 14. Can be prevented. Accordingly, the heat resistance of the pressing member 13 is reduced. Furthermore, in each of the first and second fixing belts 11 and 12, the release layer 113, the sliding layer 122, and the heating layers 114 and 123 can be separated, so that the material of each part of the heater 10 can be selected. The degree of freedom increases and the most suitable material can be selected for the function of each layer.

<Second Embodiment>
An image forming apparatus according to a second embodiment of the present invention will be described below with reference to the drawings, focusing on the configuration of the fixing unit. FIG. 9 is a schematic cross-sectional view illustrating a configuration of a fixing device serving as a fixing unit in the image forming apparatus according to the present exemplary embodiment. In the configuration shown in FIG. 9, parts that are the same as those in FIG. 3 are given the same reference numerals, and detailed descriptions thereof are omitted.

  The fixing device 6b in the present embodiment has a configuration in which a third temperature detection unit 17 that detects the temperature of the inner peripheral surface of the second fixing belt 12 is further added to the configuration of the fixing device 6a in the first embodiment. The third temperature detection unit 17 is disposed inside the second fixing belt 12 and upstream of the fixing nip region along the conveyance direction of the recording paper P2, and detects the temperature of the inner peripheral surface of the second fixing belt 12. Detect. That is, the second temperature detection unit 16 is placed on the surface of the pressing member holding member 132 on the heating member 14 side, while the third temperature detection unit 17 is on the second fixing belt 12 upstream of the fixing nip region. It is mounted on the surface of the pressing portion holding member 132 facing the inner peripheral surface.

  With this configuration, the second fixing belt 12 is heated in the vicinity of the heating member 14, and the second temperature detection unit 16 measures the temperature Tb of the inner peripheral surface thereof. When the belt 12 moves to the upstream side of the fixing nip region by the rotation operation of the belt 12, the temperature Tc of the inner peripheral surface is measured by the third temperature detection unit 17. That is, the temperature Tb on the surface of the heating layer 123 immediately after being heated by the heating member 14 in the second fixing belt 12 is measured by the second temperature detection unit 16. On the other hand, the temperature Tc of the surface of the heating layer 123 of the second fixing belt 12 at the position moved from the heating position by the heating member 14 is measured by the third temperature detection unit 17.

  The temperature control unit 25 receives the measurement signal from the first temperature detection unit 15, recognizes the temperature Ta of the heating layer 114 surface of the first fixing belt 11 measured by the first temperature detection unit 15, and The temperature signals Tb and Tc on the surface of the heating layer 123 of the second fixing belt 12 measured by the second and third temperature detectors 16 and 17 are recognized by receiving measurement signals from the third temperature detectors 16 and 17. . When the temperature control unit 25 controls the contact / separation of the switch SW1 to control the heating operation of the heating member 14, it is detected by the first and second temperature detection units 15 and 16 as in the first embodiment. The temperatures Ta and Tb of the heating layers 114 and 123 of the first and second fixing belts 11 and 12 are compared with the set temperatures T1 and T2. Further, the temperature controller 25 sets the temperature difference ΔT (= Tb−Tc) between the temperatures Tb and Tc of the heating layer 123 of the second fixing belt 12 detected by the second and third temperature detectors 16 and 17. Compare with temperature difference T3.

  The temperature control operation of the heater 10 in the fixing device 6b configured as described above will be described below. While performing the heating operation by the heating member 14, the temperature control unit 25 determines whether or not the recognized temperatures Ta and Tb of the first and second fixing belts 11 and 12 exceed the set temperatures T1 and T2. At the same time, it is determined whether or not the temperature difference ΔT of the second fixing belt 12 exceeds the set temperature difference T3. At this time, when one of the temperatures Ta and Tb of the first and second fixing belts 11 and 12 exceeds the set temperatures T1 and T2, or the temperature difference ΔT of the second fixing belt 12 is set. When the temperature T3 is exceeded, the temperature control unit 25 turns off the switch SW1 and stops the heating operation of the heating member 14.

  At this time, when the heating operation of the heating member 14 is stopped based on the results of the detected temperatures Ta and Tb of the first and second temperature detectors 15 and 16, as in the first embodiment, the first and second It is confirmed whether both the temperatures Ta and Tb of the fixing belts 11 and 12 are lower than the respective set temperatures T1 and T2. When the temperature Ta of the first fixing belt 11 falls below the set temperature T1 and the temperature Tb of the second fixing belt 12 falls below the set temperature T2, the temperature control unit 25 turns on the switch SW1 and turns on the power supply 26. Power supply to the heating member 14 is started, and the heating operation of the heating member 14 is restarted.

  On the other hand, when the heating operation is stopped based on the result of the temperature difference ΔT due to the detected temperatures Tb and Tc of the second and third temperature detectors 16 and 17, the temperature controller 25 is a part of the second fixing belt 12. It is determined that an abnormality has occurred in the temperature rise in the region, and the heating operation by the heating member 14 is stopped. That is, when the second fixing belt 12 is not driven to rotate with respect to the first fixing belt 11, a partial region of the second fixing belt 12 does not move for a longer time than usual at a position facing the heating member 14. When this happens, the temperature of the region will rise more than necessary. On the other hand, for example, by setting the set temperature difference T3 to 20 ° C., the heating operation of the heating member 14 can be stopped before the abnormal temperature rise in the second fixing belt 12 occurs. The occurrence of abnormal temperature rise can be suppressed.

  In the first and second embodiments, based on the temperatures of the first and second fixing belts 11 and 12 measured by the first to third temperature detectors 15 to 17 in the fixing devices 6a and 6b, respectively. It is assumed that the heating operation of the heating member 14 is controlled. For example, the first and second fixing belts 11 are provided from an installation region other than the first to third temperature detection units 15 to 17 such as a downstream side of the fixing nip region. , 12 may be detected. Further, as with the second fixing belt 12, the temperature of the first fixing belt 11 facing the heating member 14 is detected, and based on the difference from the temperature detected by the first temperature detection unit 15. The heating operation of the heating member 14 may be controlled.

  The fixing devices 6a and 6b in the first and second embodiments have been described as having structures based on the configuration examples shown in FIGS. 7 and 8 as the support structures of the heater 10 and the pressurizer 20, respectively. However, the present invention is not limited to the configuration example, and may have a structure different from the configuration example. Hereinafter, another example of the support structure of the heater 10 and the pressurizer 20 will be described with reference to the drawings.

<Another example 1 of support structure>
As shown in FIGS. 10 and 11, the support structure of the heater 10 and the pressurizer 20 in this example is different from the configuration example according to FIGS. 7 and 8, and rotates with the fixing member 161 instead of the end regulating member 151. The end portion restricting member 160 is constituted by the member 162. The fixing member 161 has a cylindrical shape in which the inner side protrudes toward the first and second fixing belts 11 and 12, and a flat end surface without the protrusion is fixed to the holding metal plate 153. On the other hand, the rotating member 162 has a ring shape with an L-shaped cross section, and is fitted to the fixing member 161 so that the inner peripheral surface of the opening portion is in contact with the outer peripheral surface of the protruding portion of the fixing member 161. As a result, the fixed member 161 is pivotally supported.

  At this time, both ends of the first and second fixing belts 11 and 12 are regulated with respect to the axial direction by contacting the end surfaces of the rotating member 162. The rotating member 162 has a shape in which the outer peripheral side protrudes toward the first and second fixing belts 11 and 12, and the outer peripheral surface of the first fixing belt 11 is in contact with the inner peripheral surface of the protruding portion. Thus, the first and second fixing belts 11 and 12 are restricted with respect to the radial direction. The rotating member 162 rotates around the fixed member 161 following the rotation of the first and second fixing belts 11 and 12. Accordingly, the first and second fixing belts 11 and 12 can be smoothly rotated by improving the sliding property between the fixing member 161 and the rotating member 162.

<Another example 2 of support structure>
As shown in FIGS. 12 and 13, the support structure of the heater 10 and the pressurizer 20 in this example is different from the configuration example shown in FIGS. 7 and 8, and the end restriction member having the same shape as the end restriction member 151. The configuration is such that 170 is a rotatable rotating member. That is, in the support structure of this example, the end regulating member 170 is rotatably supported by the plurality of rotation support members 171 fixed to the holding metal plate 153. The rotation support members 171 are provided at equal intervals along the circumferential direction on the outer peripheral side of the end regulating member 170, and support portions 172 serving as bearings are fixed to the holding metal plate 153 and inserted into the rotation shaft 172. The end regulating member 170 is supported on the outer peripheral surface of the rotating rotating shaft 173.

  The end restricting member 170 has the same configuration as the end restricting member 151, thereby restricting the first and second fixing belts 11 and 12 with respect to the axial direction and the radial direction. With this configuration, the end regulating member 170 has its outer peripheral surface in contact with the rotation shaft 173 of the rotation support member 171 and is rotatably supported, so that the first fixing belt 11 is rotated. Rotate. Accordingly, in this example as well, as in the support structure of the above-described alternative example 1, the first and second fixing belts 11, 11 can be improved by improving the slidability between the end regulating member 170 and the rotation support member 171. 12 can be smoothly rotated.

<Another example 3 of support structure>
As shown in FIGS. 14 and 15, the support structure of the heater 10 and the pressurizer 20 in this example is different from the configuration examples shown in FIGS. 7 and 8, and the first end portion for meandering regulation of the first fixing belt 11. A restriction member 181 and a second end restriction member 182 for restricting meandering of the second fixing belt 12 are provided. In the heater 10 of this example, the first and second fixing belts 11 and 12 are configured such that the axial length of the first fixing belt 11 is shorter than the axial length of the second fixing belt 12. ing.

  In the support structure of this example, the first end restricting member 181 extends from the holding metal plate 153 toward the end of the first fixing belt 11 so as to restrict the first fixing belt 11 in the axial direction. 183 is supported. The first end regulating member 181 has a horseshoe shape in which a region overlapping the second fixing belt 12 is cut out from a ring shape having the same cross section as the end regulating member 151. In other words, the first end regulating member 181 covers the end of the first fixing belt 11 in a region other than the region including the front and rear of the fixing nip region centered on the fixing nip region. The second end regulating member 182 has a ring shape with an L-shaped cross section and is fixed to the holding metal plate 153 to regulate the second fixing belt 12 in the radial direction and the axial direction.

  As shown in the above-mentioned other examples 1 to 3, the first and second fixing belts 11 and 12 have a pressure roller 21 with respect to the fixing device support structure in the first and second embodiments. It may be configured to be driven, and may be configured other than the above example. Moreover, although the structure by the pad base layer 131 and the press part holding member 132 as shown in FIG. 3 was mentioned as an example as the press member 13 in the heater 10, it is not restricted to such a structure, For example, a metal core Other configurations such as a roller structure in which an elastic layer is provided on the outer periphery may be used.

  An MFP (Multifunction Peripheral) having a copy function, a scanner function, a printer function, and a fax function is acceptable as long as the image forming apparatus according to the present invention includes the fixing device as a fixing unit in each of the above-described embodiments. It may be a printer, a copier, a facsimile, or the like. In addition, the structure of each part is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 3 Image reading part 4 Paper feed tray 5 Transfer part 6 Fixing part 6a, 6b Fixing device 7 Paper discharge tray 8 Paper feed mechanism 9 Operation panel 10 Heater 11 First fixing belt 12 Second fixing belt DESCRIPTION OF SYMBOLS 13 Press member 14 Heating member 15 1st temperature detection part 16 2nd temperature detection part 17 3rd temperature detection part 17a Rotating member 17b Fixing member 19 Bearing 20 Pressurizer 21 Pressure roller 22 Core metal 23 Elastic layer 24 Release layer 25 Temperature controller 26 Power source 59 Heater 60 Pressurizer 111 Base material 112 Elastic layer 113 Release layer 114 Heating layer 121 Base material 122 Sliding layer 123 Heating layer 131 Pad base layer 132 Pressing portion holding member 133 Base material 134 Sliding layer 134a Sliding sheet 151 End regulating member 152 Heating portion holding member 153 Holding sheet metal 154 Bearing 160 End Regulating member 161 fixing member 162 rotating member 170 end portion regulating member 171 rotates the support member 172 rotating shaft 173 supporting portion 181 first end regulating member 182 second end regulating member 183 support member

Claims (7)

A fixing device comprising: a heater for heating the recording material; and a pressurizer for nipping and conveying the heater and the recording material,
The heater is
A rotatable first fixing belt;
A second fixing belt disposed inside the first fixing belt, a part of the outer peripheral surface of which is in contact with the inner peripheral surface of the first fixing belt;
A heating member disposed inside the first fixing belt and outside the second fixing belt;
A pressing member that clamps the first and second fixing belts with the pressurizer by pressing against the pressurizer at the contact position of the first and second fixing belts;
A fixing device.   2. The fixing according to claim 1, wherein a heating layer that absorbs heat from the heating member is provided on a surface layer of each of an inner peripheral surface of the first fixing belt and an outer peripheral surface of the second fixing belt. apparatus.   3. A sliding layer having slidability is provided on a surface of the pressing member on an inner peripheral surface side of the second fixing belt and an inner peripheral surface of the second fixing belt. The fixing device described.   The fixing device according to claim 1, wherein a release layer having slidability is provided on an outer peripheral surface of the first fixing belt. A first temperature detector for measuring the temperature of the first fixing belt;
A second temperature detector for measuring the temperature of the second fixing belt;
And further comprising
When at least one of the temperatures of the first and second fixing belts measured by the first and second temperature detecting units exceeds a target temperature set for each of the first and second fixing belts, The fixing device according to claim 1, wherein the heating operation by the heating member is stopped.   The temperature of the second fixing belt is measured at a plurality of locations, and when the temperature difference of the second fixing belt measured at the plurality of locations becomes larger than a predetermined value, the heating operation by the heating member is stopped. The fixing device according to claim 1, wherein the fixing device is characterized in that: An image forming apparatus comprising: a transfer unit that transfers a toner image to a recording paper; and a fixing unit that pressurizes the recording paper on which the toner image has been transferred by the transfer unit while heating.
An image forming apparatus, wherein the fixing unit includes the fixing device according to claim 1.

Images