JP2011164165A - Fixing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device provided in an image forming device such as a copying machine, a facsimile, a printer, having a member for preventing a fixation belt from moving to one side, and capable of suppressing or preventing the fixation belt from being deteriorated by virtue of the installation of the member for preventing it from moving to one side; and to provide the image forming device equipped with this fixing device. <P>SOLUTION: The fixing device 6 includes: the endless fixation belt 64; a winding roller 65 having the fixation belt 64 wound around it; a pressurizing roller 63 for pressurizing the fixation belt 64 between the winding roller 65 and it; and the member 69, provided on a face on the reverse side to the pressurizing roller 63 of the fixation belt 64, for preventing the fixation belt 64 from moving to one side. The member 69 for preventing the fixation belt 64 from moving to one side is abutted on a small diameter part 65a of the winding roller 65, having smaller diameter than that of a winding part 65b around which the fixation belt 64 is wound, and is sandwiched together with the fixation belt 64 in between the small diameter part 65a and it by virtue of the pressurizing roller 63. The image forming device is equipped with this fixing device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device having a fixing belt provided in an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and such an image forming apparatus having the same.

2. Description of the Related Art Conventionally, a fixing device that is provided in an image forming apparatus such as a copying machine, a facsimile machine, or a printer and fixes an image carried on a recording medium such as paper on the recording medium, and includes an endless fixing belt. There are known fixing devices (see, for example, [Patent Document 1] to [Patent Document 7]).
In such a fixing device, a phenomenon of so-called belt deviation occurs in which the fixing belt moves in the width direction orthogonal to the rotation direction by rotation. When this belt deviation becomes large, there arises a problem that the fixing belt is detached from the roller-like member around which the fixing belt is wound.
In view of this, a technique for providing a fixing member on the fixing belt has been proposed in order to regulate the belt deviation (see, for example, [Patent Document 1] to [Patent Document 4]).

  However, in such a conventionally proposed technology, when such a detent member is provided, there is a problem that the fixing belt deteriorates at a boundary portion between a portion where the detent member is provided and a portion where the detent member is not provided. is there. In other words, in the conventional configuration, when the fixing belt rotates while the detent member is in contact with the end face of the roller-shaped member and a force is applied to increase the belt deviation, the fixing belt is bent at the boundary portion. It takes power. Further, in the conventional configuration, when the fixing belt is pressed by a pressure roller generally provided in the fixing device, a force for bending the fixing belt is applied to the boundary portion by the pressing. When such a force is repeatedly applied over a long period of time, the fixing belt deteriorates, eventually cracking the fixing belt and causing damage.

  The present invention is a fixing device having a fixing belt offset member provided in an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and suppressing or preventing deterioration of the fixing belt due to the provision of the offset member. It is an object of the present invention to provide a fixing device that can be used, and such an image forming apparatus having the same.

  In order to achieve the above object, the invention described in claim 1 is directed to an endless fixing belt, a winding roller around which the fixing belt is wound, and pressurization for pressurizing the fixing belt between the winding rollers. A fixing member provided on a surface opposite to the pressure roller of the fixing belt and restricting the shifting of the fixing belt, and the locking member includes the fixing belt of the winding roller. The fixing device is in contact with the small-diameter portion having a smaller diameter than the winding portion around which the wire is wound, and is sandwiched between the pressure belt and the fixing belt together with the fixing belt.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, the winding roller has a rotating member that is rotatable relative to the winding roller body, and the rotating member is provided as the small-diameter portion. It is characterized by being.

  According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the winding roller includes the small-diameter portion as a groove-shaped portion.

  According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, an amount of biting of the small diameter portion with respect to the detent member is 0.2 to 1.0 mm. To do.

  According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, the detent member is an elastic body.

  A sixth aspect of the present invention is an image forming apparatus having the fixing device according to any one of the first to fifth aspects.

  The present invention relates to an endless fixing belt, a winding roller around which the fixing belt is wound, a pressure roller for pressing the fixing belt between the winding rollers, and the pressure roller of the fixing belt. And a detent member that restricts the displacement of the fixing belt, and the detent member is smaller in diameter than the winding portion of the winding roller around which the fixing belt is wound. Since the fixing device is in contact with a portion and sandwiched between the fixing belt and the small diameter portion by the pressure roller, it is possible to suppress or prevent deterioration of the fixing belt due to the provision of a detent member. It is possible to improve the durability of the fixing belt, reduce failures such as failures, reduce running costs and service costs, and perform stable fixing operations over a long period of time. , It is possible to provide a fixing device which can contribute to stable image formation over productivity improvement and long-term image-formed product.

  The winding roller has a rotating member that is rotatable with respect to the winding roller main body. If the rotating member is provided as the small diameter portion, the detent member abuts on the small diameter portion. It is possible to suppress or prevent deterioration, and the rotation of the detent member can be matched with the rotation of the fixing belt, and the deterioration of the fixing belt due to the provision of the detent member can be suppressed or prevented to a higher degree. The durability of the fixing belt is further improved, failures such as failures are further reduced, running costs and service costs can be further reduced, and more stable fixing operation can be performed over a long period of time. Therefore, it is possible to provide a fixing device that can contribute to further improvement in productivity and stable image formation over a long period of time.

  If the winding roller is provided with the small diameter portion as a groove-shaped portion, it is possible to enhance the belt shift prevention function by the shift stop member, and to prevent the fixing belt from being deteriorated by providing the shift stop member. It can be suppressed or prevented, the durability of the fixing belt is improved, failures such as failures are reduced, running costs and service costs can be reduced, and more stable fixing operation can be performed over a long period of time, thereby forming an image. It is possible to provide a fixing device that can contribute to further improvement in productivity of products and more stable image formation over a long period of time.

  If the amount of biting of the small diameter portion with respect to the stopper member is 0.2 to 1.0 mm, the fixing belt rotation stability is improved by optimizing the amount of biting, and a stopper member is provided. It is possible to suppress or prevent deterioration of the fixing belt due to the failure, improve the durability of the fixing belt, reduce failures such as failure, reduce running cost and service cost, and stable fixing operation for a long time Therefore, it is possible to provide a fixing device that can be performed and contribute to improvement of productivity of an image formed product and stable image formation over a long period of time.

  If the detent member is an elastic body, the stability of rotation of the fixing belt is improved by elastic deformation of the detent member, and deterioration of the fixing belt due to the provision of the detent member can be suppressed or prevented. As a result, the durability of the fixing belt is improved, failures such as breakdowns are reduced, running costs and service costs can be reduced, and stable fixing operation can be performed over a long period of time, thereby improving the productivity of image formations. Further, it is possible to provide a fixing device that can contribute to stable image formation over a long period of time.

  Since the present invention is in an image forming apparatus having such a fixing device, it is possible to suppress or prevent deterioration of the fixing belt due to the provision of a detent member, and the durability of the fixing belt is improved, and troubles such as failure are prevented. Image formation assumption that can reduce the running cost and service cost, and can perform a stable fixing operation over a long period of time, and can improve the productivity of the image formation and stable image formation over a long period of time. Can be provided.

1 is a schematic front view of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic front view showing a configuration around one image carrier among a plurality of image carriers provided in the image forming apparatus shown in FIG. 1. FIG. 2 is a schematic front sectional view of a fixing device provided in the image forming apparatus shown in FIG. 1. FIG. 2 is a schematic right side sectional view of a fixing device provided in the image forming apparatus shown in FIG. 1. FIG. 5 is a schematic perspective view showing a fixing belt and a detent member provided in the fixing device shown in FIGS. 3 and 4. FIG. 5 is a schematic diagram illustrating how the fixing belt stably travels in the fixing device illustrated in FIGS. 3 and 4. FIG. 3 is a schematic diagram illustrating another configuration example of a fixing device provided in the image forming apparatus illustrated in FIG. 1. FIG. 10 is a schematic diagram illustrating still another configuration example of the fixing device provided in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a schematic diagram illustrating a problem that may occur in a fixing device having a configuration different from that of the fixing device provided in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a schematic diagram illustrating another problem that may occur in a fixing device having a configuration different from that of the fixing device provided in the image forming apparatus illustrated in FIG. 1.

  FIG. 1 shows an outline of an image forming apparatus to which the present invention is applied. The image forming apparatus 100 is a multifunction peripheral of a copying machine, a printer, and a facsimile machine, and can perform full-color image formation. Other image forming apparatuses, that is, a monochrome machine, a copying machine, a printer, It may be a single facsimile, or another multifunction device such as a multifunction device of a copying machine and a printer. When used as a printer, the image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside. This is the same when the image forming apparatus 100 is used as a facsimile.

  The image forming apparatus 100 can form an image on a sheet-like recording medium using not only plain paper generally used for copying, but also OHP sheets, cardboard, cardboard, cardboard, and envelopes. It is. The image forming apparatus 100 is also a double-sided image forming apparatus capable of forming an image on both sides of a transfer sheet as a recording medium as a recording medium.

  The image forming apparatus 100 includes a main body 101 that occupies a central position in the vertical direction and functions as a printer unit, a reading device 21 that is positioned above the main body 101 and that reads a document, and a document on which a document is stacked and loaded. An automatic document feeder 22 which is an automatic document feeder called ADF which is sent out toward 21, and the photosensitive drums 20 </ b> Y, 20 </ b> M, 20 </ b> C, 20 </ b> BK located below the main body 101 and the transfer belt 11. A sheet feeding device 23 serving as a paper feeding device serving as a paper feeding table on which the transfer paper to be conveyed is stacked.

  The image forming apparatus 100 includes a plurality of photosensitive drums 20Y, 20M, 20C, and 20BK that can form images as images corresponding to colors separated into yellow, magenta, cyan, and black, respectively. 1 is a tandem type image forming apparatus that employs a tandem structure in which the two are arranged side by side. The photosensitive drums 20Y, 20M, 20C, and 20BK have the same diameter, and are transfer belts as intermediate transfer belts that are intermediate transfer members that are endless belts disposed almost at the center inside the main body 101 of the image forming apparatus 100. 11 are arranged at equal intervals on the outer peripheral surface side, that is, on the image forming surface side.

  The transfer belt 11 is movable in the arrow A1 direction, which is the clockwise direction in the figure, while facing the respective photosensitive drums 20Y, 20M, 20C, and 20BK. The visible image, that is, the toner image formed on each of the photoconductive drums 20Y, 20M, 20C, and 20BK is superimposed and transferred onto the transfer belt 11 that moves in the direction of the arrow A1, and is then collectively transferred onto the transfer paper. It has become. As described above, the image forming apparatus 100 employs the indirect transfer method. Accordingly, the image forming apparatus 100 is a tandem indirect transfer type electrophotographic apparatus.

  In the superimposing transfer to the transfer belt 11, the toner images formed on the photosensitive drums 20Y, 20M, 20C, and 20BK are transferred to the same position on the transfer belt 11 while the transfer belt 11 moves in the A1 direction. As described above, a primary transfer device as a transfer charger that is disposed at a position facing each of the photosensitive drums 20Y, 20M, 20C, and 20BK across the transfer belt 11 and that is in contact with the inner peripheral surface of the transfer belt 11. As a result of voltage application by the primary transfer rollers 12Y, 12M, 12C, and 12BK, the timing is shifted from the upstream side toward the downstream side in the A1 direction, and the positions immediately below the photosensitive drums 20Y, 20M, 20C, and 20BK, that is, 1 It is performed at the transfer position which is the next transfer position. Since the transfer belt 11 also contributes to this transfer, it can be said that it constitutes a primary transfer device.

  The photosensitive drums 20Y, 20M, 20C, and 20BK are arranged in this order from the upstream side in the A1 direction. The photosensitive drums 20Y, 20M, 20C, and 20BK are provided in image stations 60Y, 60M, 60C, and 60BK, respectively, for forming yellow, magenta, cyan, and black images.

  The image forming apparatus 100 includes an image forming unit 60 which is an image forming unit as an image forming unit configured by four image stations 60Y, 60M, 60C, and 60BK, and below the photosensitive drums 20Y, 20M, 20C, and 20BK. The transfer belt unit 10 is an intermediate transfer unit provided with the transfer belt 11, and faces the transfer belt 11 on the side opposite to the image forming unit 60 with the transfer belt 11 in between. The secondary transfer belt serving as a conveyance belt, which is a paper conveyance belt as a transfer member that is disposed in contact with the transfer belt 11 and rotates in the same direction as the transfer belt 11 and moves endlessly at the contact position with the transfer belt 11. 5 is a secondary transfer unit as a secondary transfer device that transfers the toner image on the transfer belt 11 to transfer paper and conveys the toner image on the transfer belt 11. And a copy unit 76.

  The image forming apparatus 100 also includes an optical scanning device 8 serving as an exposure device serving as an optical writing unit serving as an optical writing device serving as an optical writing device disposed above the image stations 60Y, 60M, 60C, and 60BK, and a sheet. The transfer paper conveyed from the feeding device 23 comes into contact with the transfer paper to temporarily stop the toner image formation timing by the image stations 60Y, 60M, 60C, and 60BK. In other words, the position of the toner image on the transfer belt 11 The registration roller pair 13 that rotates at a predetermined timing in accordance with the transfer belt 11 and feeds out toward the transfer portion between the transfer belt 11 and the secondary transfer belt 5, and that the leading edge of the transfer paper has reached the registration roller pair 13. And a sensor (not shown) for detection.

  The image forming apparatus 100 also serves as a belt-fixing type fixing unit for transferring the toner image on the transfer belt 11 transferred by the secondary transfer unit 76 and fixing the toner image on the transfer paper. A fixing device 6 as a belt fixing device, a paper discharge path for discharging the fixed transfer paper to the outside of the main body 101, and a reverse path for conveying the transfer paper toward the registration roller pair 13 again. The paper discharge unit 79 is disposed below the secondary transfer unit 76 and the fixing device 6 in parallel with the image forming unit 60. The paper discharge unit 79 has one side for recording images on both the front and back sides of the transfer paper. A re-feeding unit that, when the transfer paper on which the image is formed is conveyed to the reversing path, switches the transfer paper to reverse and conveys the transfer paper again toward the registration roller pair 13; A sheet reversing apparatus for Te and a sheet reversing device serving duplex unit 96.

  The image forming apparatus 100 also includes a paper discharge tray 75 as a stack unit that is disposed outside the main body 101 and stacks transfer sheets on which image formation has been performed, and a manual sheet feeding device disposed on the right side surface of the main body 101 in FIG. 33, an operation panel (not shown) that operates the image forming apparatus 100, and a control unit (not shown) as a control unit that controls the operation of the entire image forming apparatus 100.

  In addition to the transfer belt 11, the transfer belt unit 10 includes primary transfer rollers 12Y, 12M, 12C, and 12BK as primary transfer means, and first to third belts wound around the transfer belt 11 and stretched. The transfer belt 11 is interposed between the tension roller 74 and a driving roller 72 as a rotation driving roller that rotationally drives the transfer belt 11 as a support roller, a transfer inlet roller 73 as a driven roller, a tension roller 74 as a driven roller, and the tension roller 74. An intermediate transfer belt cleaning device 14 as a belt cleaning device for cleaning the surface of the sandwiching transfer belt 11, a belt driving motor (not shown) that moves the transfer belt 11 endlessly in the A1 direction by rotationally driving the driving roller 72, and image formation. This is done with multicolor images of two or more colors, or a single color image with black only KazuSatoshi and a transfer belt unit driving means (not shown) for displacing the transfer belt 11 or the like depending on whether carried out in a monochrome image. The rotation driving roller may be constituted by a tension roller 74 or a transfer entrance roller 73. In this case, the other rollers are driven to rotate.

  When the image formation is performed with two or more multi-color images, the transfer belt unit driving means places the transfer belt 11 in a state where the transfer belt 11 is stretched substantially horizontally as shown in FIG. When image formation is performed with a monochrome image by contacting with 20Y, 20M, 20C, and 20BK, the tension roller 74 is displaced and the left side of the drawing is displaced downward, so that the transfer belt 11 is displaced to the photosensitive drums 20Y, 20M. , 20C so that the transfer belt 11 contacts only the photosensitive drums 20BK. When the image formation is performed with a monochrome image, the operations of the image stations 60Y, 60M, and 60C are stopped, including the rotation of the photosensitive drums 20Y, 20M, and 20C. In such a configuration, the four image stations 60Y, 60M, 60C, and 60BK are arranged side by side in the order of the image stations 60C, 60M, 60Y, and 60BK from the upstream in the A1 direction, and development as described below is performed. In any case, the image forming unit 60 is disposed on the linear transfer belt 11 stretched between the tension roller 74 and the driving roller 72. As described above, the order of colors for forming an image varies depending on the aim and characteristics of the image forming apparatus 100 and is not limited.

  In addition to the secondary transfer belt 5, the secondary transfer unit 76 is a tension roller around which the secondary transfer belt 5 is wound. A transfer entrance roller 73 as a backup roller that is provided and pressed against and pressed through the transfer belt 11; and a power supply (not shown) that applies a secondary transfer bias having a polarity opposite to that of the toner to the drive roller 15. ing.

  The driving roller 15 and the transfer entrance roller 73 sandwich the transfer belt 11 and the secondary transfer belt 5 between them, and the secondary transfer belt 11 and the secondary transfer belt 5 come into contact with each other by the sandwiching. A nip is formed. In the secondary transfer nip, by applying a secondary transfer bias, a toner image carried on the transfer belt 11 is electrostatically moved from the transfer belt 11 side toward the drive roller 15 side as described later. A next transfer electric field is formed. Such a toner image is transferred to a transfer sheet conveyed between the transfer belt 11 and the secondary transfer roller 5 by the registration roller 13 by a secondary transfer electric field and a nip pressure as will be described later.

  The secondary transfer unit 76 also has a sheet conveyance function for conveying the transfer paper onto which the toner image has been transferred from the transfer belt 11 to the fixing device 6. The secondary transfer unit 76 includes a transfer roller or a non-contact type. A configuration employing a charger may be used. In this case, another member for transporting the transfer paper toward the fixing device 6 is required.

  The optical scanning device 8 scans and exposes the surfaces to be scanned formed by the surfaces of the photosensitive drums 20Y, 20M, 20C, and 20BK, and forms a laser beam based on an image signal for forming an electrostatic latent image. Scanning with a light source (not shown) that emits the laser light L shown in FIG. 2, a polygon mirror (not shown) that scans the laser light emitted by the light source by its rotation, a polygon motor (not shown) that drives the polygon mirror to rotate, and a polygon mirror The laser beam is imaged on the photosensitive drums 20Y, 20M, 20C, and 20B, and has a large number of optical elements (not shown) such as an f-θ lens (not shown) and a reflection mirror that scan. An LED may be used as the light source.

  The fixing device 6 includes an endless fixing belt 64, a fixing roller 65 as a winding roller around which the fixing belt 64 is wound, a stretching roller 62 around which the fixing belt 64 is wound together with the fixing roller 65, and a fixing roller 65. And a pressure roller 63 that presses against the fixing belt 64 and presses the fixing belt 64 to form a fixing nip as a fixing portion that is a pressure-contact portion. As described above, since the fixing belt 6 includes the fixing belt 64 having a very short temperature increase time, energy consumption is reduced, and after the power is turned on, the user waits until image formation can be started. Time has been reduced.

The tension roller 62, the fixing belt 64, and the fixing roller 65 constitute a belt unit in which the fixing belt 64 moves endlessly. The fixing device 6 performs a fixing process for fixing the supported toner image on the surface of the transfer paper by the action of heat and pressure by passing the transfer paper carrying the toner image through the fixing nip.
Details of the fixing device 6 will be described later.

  A paper discharge unit 79 transports the fixed transfer paper transported from the fixing device 6 toward the duplex unit 96, a paper discharge roller 98 that discharges the paper to the outside of the main body 101, and a fixed transfer. There is provided a switching claw 94 for switching whether the paper is guided to the paper discharge path with the conveying roller 97 and discharged out of the main body 101 or the paper is guided to the reverse path with the paper discharge roller 98 to enter the duplex unit 96.

  The duplex unit 96 is a tray 92 on which transfer paper having an image formed on one side, which has been conveyed from the paper discharge unit 79, is temporarily stacked, a reverse roller 93 that switches back the transfer paper on the tray 92, and a reverse roller. The sheet feeding roller 95 and the like for feeding the transfer sheet switched back by 93 to the registration roller 13 are provided.

  The sheet feeding device 23 includes a paper bank 26 in which a plurality of sheet feeding cassettes 25 that can store a plurality of transfer sheets in a bundle of sheets are arranged in a vertical direction, and a plurality of transfer sheets stacked on the sheet feeding cassette 25. Among them, a feeding roller 24 as a sheet feeding roller that contacts the upper surface of the uppermost transfer sheet, a separation roller 27 that separates the transfer sheets fed by the feeding roller 24 one by one, a sheet feeding roller 24 and a separation roller And a paper feed path 29 through which the transfer paper fed by the roller 27 passes.

  A paper feed path 29 is provided at a downstream end in the transport direction of the transfer paper, and a transport guide plate 37 and a transport roller 28 for transporting the transfer paper fed by the paper feed roller 24 and the separation roller 27 toward the registration roller pair 13. The transfer roller sheet feeding device 23 transported by the transport roller 28 is provided so as to continue into the main body 101. The transport roller 28 is also provided in the paper feed path 29 in the main body 101. Is arranged.

  In the sheet feeding device 23, the feeding roller 24 is rotated in the counterclockwise direction in the drawing, and the separation roller 27 acts to guide the uppermost transfer paper into the paper feeding path 29, so that the conveying roller 28 The sheet is fed toward the registration roller pair 13 by rotation, and the transferred transfer paper is abutted against the registration roller pair 13 and stopped.

  The manual paper feed device 33 includes a manual feed tray 34 on which transfer paper is stacked, a feed roller 35 as a paper feed roller that contacts the upper surface of the uppermost transfer paper among the transfer papers stacked on the manual feed tray 34, It has a separation roller 36 for separating the transfer paper fed by the feed roller 35 one by one, and a paper sensor for detecting that the transfer paper is placed on the manual feed tray 34.

  In the manual sheet feeding device 33, the feeding roller 35 is driven to rotate in the clockwise direction in the drawing, and the separation roller 36 acts to guide the uppermost transfer sheet into the sheet feeding path 29 on the main body 101 side and to register the sheet. The transfer paper fed to the roller pair 13 is transported against the registration roller pair 13 and stopped.

  The reading device 21 includes a contact glass 21a on which a document is placed, a light source (not shown) that irradiates light on the document placed on the contact glass 21a, and a first light source (not shown) that reflects light reflected from the light source. A first traveling body 21b that has a reflector and travels in the left-right direction in FIG. 1, a pair of second reflectors (not shown) that changes the direction by 180 degrees by reflecting light reflected by the reflector of the first traveling body 21b. A second traveling body 21c provided, an imaging lens 21d for imaging the light from the second traveling body 21c, a reading sensor 21e for receiving the light passing through the imaging lens 21d and reading the contents of the document are provided.

  The automatic document feeder 22 has a document table 22a on which a document is placed. The automatic document feeder 22 is rotatable with respect to the reading device 21, and the contact glass 21a is exposed when the automatic document feeder 22 is rotated upward.

The operation panel is an operation display unit having a liquid crystal display, a start button that functions as a copy start switch for starting copying, and various key buttons such as a numeric keypad for inputting the number of copies. On the operation panel, it is possible to specify whether image formation is performed with a multicolor image or a monochrome image, and it is possible to set a single-sided print mode, which is a mode for forming an image only on one side of a transfer sheet. Yes. The single-sided print mode includes a direct discharge mode, a reverse discharge mode, and a reverse decal discharge mode, and one of these is selected.
The control means includes a CPU, a memory as a storage means, and the like.

  Regarding the image stations 60Y, 60C, 60M, and 60BK, the configuration will be described as a representative of the configuration of the image station 60Y including the photosensitive drum 20Y. Since the configuration of other image stations is substantially the same, in the following description, for the sake of convenience, reference numerals corresponding to the reference numerals assigned to the configuration of the image station including the photosensitive drum 20Y are used for other image stations. A detailed description will be omitted as appropriate for the station configuration, and those with Y, C, M, and K at the end of the reference numerals are used to form yellow, cyan, magenta, and black images, respectively. It is assumed that this is the configuration.

  As shown in FIG. 2, the image station 60Y including the photosensitive drum 20Y has a primary transfer roller 12Y and an image around the photosensitive drum 20Y along the rotation direction B1 that is counterclockwise in the drawing. Density detection means 17Y, cleaning device 70Y as a primary transfer cleaning device as a photosensitive member cleaning device as a cleaning means, charge removal device 90Y as a charge removal means, charging device 30Y as a charging unit as a charging means, and development A developing device 80Y, which is a developing unit as means, and a cartridge case 59Y in which these are integrated are provided.

  The photosensitive drum 20Y, the cleaning device 70Y, the charge eliminating device 90Y, the charging device 30Y, the developing device 80Y, and the image density detecting means 17Y are integrated by a cartridge case 59Y, and an image station 60Y as a process cartridge is integrated. Is configured. The image station 60Y as a process cartridge can draw out the cartridge case 59Y from the main body 101 along a guide rail (not shown) fixed to the main body 101, and can push the cartridge case 59Y into the main body 101. Is detachably installed.

  When pushed into the main body 101, the image station 60Y as a process cartridge is loaded and positioned at a predetermined position suitable for image formation. Making a process cartridge in this way is very preferable because it can be handled as a replacement part, so that the maintainability is remarkably improved. In addition, since the life of each part, which is an element of the process cartridge, is equal, unnecessary replacement is prevented and suppressed, and the structure is further preferable.

  The image station 60Y as a process cartridge includes at least the photosensitive drum 20Y among the photosensitive drum 20Y, the cleaning device 70Y, the charge eliminating device 90Y, the charging device 30Y, the developing device 80Y, and the image density detecting unit 17Y. Another unit is a unit that is configured by being integrated and is detachably installed on the main body 101.

  A primary transfer nip formed by the primary transfer roller 12Y pressing the transfer belt 11 toward the photosensitive drum 20Y is a contact position between the transfer belt 11 and the photosensitive drum 20Y. Constitutes a transfer position NP at which the toner image is transferred to the transfer belt 11. The primary transfer device is not limited to the roller shape as in the present embodiment, but may be configured by a conductive brush shape, a non-contact corona charger, or the like.

  The photosensitive drum 20Y has a linear velocity of 200 mm / s, a diameter of 50 mm, and a thickness of 30 μm.

  The static eliminator 90Y includes a static elimination lamp (not shown) disposed in the vicinity of the surface of the photoconductor drum 20Y, and the surface of the photoconductor drum 20Y is neutralized by making it electrically clean. The static elimination process which initializes the electric potential of this is performed.

  The charging device 30Y includes a charging roller 31Y that rotates in contact with the surface of the photosensitive drum 20Y, and a cleaning roller 32Y as a charging cleaning member that rotates in contact with the charging roller 31Y.

  The charging roller 31Y is connected to a voltage applying means (not shown) for applying a bias of an alternating current component to a direct current, and in the charging region facing the photosensitive drum 20Y, the charging drum 31Y is charged by the discharging device 90Y. A charging step for uniformly charging the surface to a predetermined polarity is performed. The charging potential of the photosensitive drum 20Y by the charging roller 31Y, that is, the pre-exposure potential V0 is −700V.

The cleaning roller 32Y cleans the charging roller 31Y by rotating following the charging roller 31Y.
As described above, in this embodiment, a charging system using a contact roller is adopted. However, the charging system may use a proximity roller or a non-contact scorotron charger. There may be.

  The optical scanning device 8 shown in FIG. 1 applies the laser light L modulated and deflected to a region between a charging region where the charging device 30Y faces the photosensitive drum 20Y and a developing region where the developing device 80Y faces. Image information that is irradiated while scanning and the surface to be scanned on the surface of the photosensitive drum 20Y after being charged by the charging device 30Y is exposed by spot irradiation and visualized as a yellow toner image by the developing device 80Y. An electrostatic latent image forming step of writing an electrostatic latent image according to the above is performed. The beam spot diameter on the surface of the photosensitive drum 20Y by the optical scanning device 8 is 50 × 60 μm, and the light quantity is 0.47 mW. The charged potential of the photosensitive drum 20Y after the exposure by the optical scanning device 8, that is, the post-exposure potential VL is −120V.

  As shown in FIG. 2, the developing device 80Y includes a developing roller 81Y carrying a two-component developer (hereinafter referred to as developer) including a toner and a carrier disposed in close proximity to the photosensitive drum 20Y, and a developing roller 81Y. A doctor blade 82Y that regulates the developer on the roller 81Y to a certain height, and a first conveying screw that is arranged in parallel with each other and agitates the developer and supplies the developer to the developing roller 81Y. 83Y and the second transport screw 84Y, a partition wall 87Y that is a partition plate provided between the first transport screw 83Y and the second transport screw 84Y, and a part of the cartridge case 59Y that houses them. And a developing case 85Y.

  The developing device 80Y also develops a toner concentration sensor 86Y as a toner concentration detecting unit attached to the developing case 85Y below the first conveying screw 83Y, a toner bottle 88Y containing yellow toner, and a developing bias of a DC component. A bias applying unit (not shown) for applying to the roller 81Y and a developing driving unit as a driving unit (not shown) for driving the developing roller 81Y, the first conveying screw 83Y, the second conveying screw 84Y, and the like are included.

The first conveying screw 83Y, the second conveying screw 84Y, and the partition wall 87Y constitute an agitating unit 38Y that conveys the developer while stirring and supplies the developer to the developing roller 81Y.
The developing roller 81Y and the doctor blade 82Y occupy a position higher than the agitating unit 38Y, and constitute a developing unit 39Y that transfers the toner of the developer attached to the developing roller 81Y to the photosensitive drum 20Y.

  The developing roller 81Y has a developing sleeve (not shown) that is a developer carrying member that carries the developer on the surface thereof, and a plurality of magnets (not shown) fixed inside the developing sleeve.

The doctor blade 82Y is disposed so that the tip thereof is close to the developing sleeve.
The bias applying means applies a developing bias having an appropriate size between the exposed portion and the non-exposed portion of the photosensitive drum 20Y to the developing sleeve.

  In the developing device 80Y, a partition wall 87Y forms a first supply unit that accommodates the developing roller 81Y and the first conveyance screw 83Y and a second supply unit that accommodates the second conveyance screw 84Y. Has been.

  The developer in the developing case 85Y is a two-component developer including a magnetic carrier and a yellow toner that is a negatively charged color toner. The developer is supplied with yellow toner from a toner bottle 88Y. The supplied yellow toner and developer are agitated and mixed while being agitated and conveyed by the first conveying screw 83Y and the second conveying screw 84Y, frictionally charged, supplied to the developing roller 81Y, and pumped up by the magnet roller. Is held by the developing sleeve, and is carried in such a manner that a magnetic brush is formed on the developing sleeve.

  In the developing roller 81Y, the developer carrying amount is regulated by the doctor blade 82Y by the rotation of the developing sleeve, the layer thickness is regulated, the magnetic brush is trimmed to an appropriate amount, and the developer that has been cut off enters the stirring unit 38Y. Returned. The developing roller 81Y also carries an appropriate amount of developer by the doctor blade 82Y to the developing area between the developing roller 81Y and the photosensitive drum 20Y by the rotation and the developing bias by the bias applying means. The yellow toner is electrostatically transferred to an electrostatic latent image formed on the surface of the photoreceptor drum 20Y, and a developing process is performed in which the electrostatic latent image is made visible as a yellow toner image and visualized as an image. It is like that.

The developer that has consumed the yellow toner by the development leaves the developing sleeve at the position where the magnetic force of the magnet roller has decreased with the rotation of the developing roller 81Y, and returns to the stirring unit 38Y.
By repeating this, the toner concentration in the agitating unit 38Y becomes low, and when this is detected by the toner concentration sensor 86Y, the toner concentration sensor 86Y detects that the toner concentration has reached a predetermined concentration from the toner bottle 88Y. Toner is replenished and supplied.

  In this embodiment, the DC component developing bias is applied by the bias applying means. However, the developing bias may be an AC component, or an AC component superimposed on the DC component.

  The cleaning device 70Y includes a cleaning case 71Y configured by a part of the cartridge case 59Y that forms a housing thereof, and is housed in the cleaning case 71Y. The tip of the cleaning device 70Y comes into contact with the photosensitive drum 20Y and is on the photosensitive drum 20Y. A cleaning blade 78Y as a cleaning member for performing a cleaning process for scraping off and collecting foreign matters such as transfer residual toner, carrier, paper dust, and the like, which are transfer residues, and a cleaning blade 78Y supported by a cleaning case 71Y The blade support 73Y, a support shaft 77Y that rotatably supports the blade support 73Y on the cleaning case 71Y, and a predetermined elasticity on the photosensitive drum 20Y so that the edge of the cleaning blade 78Y is pressed against the photosensitive drum 20Y. Push with force And a Rubane 79Y.

  The cleaning device 70Y is also rotatably supported by the cleaning case 71Y, and the cleaning blade 78Y scrapes off the transfer residual toner and the like from the photosensitive drum 20Y, and also removes unnecessary items such as waste toner generated by the removal. The photosensitive drum is provided with a discharge screw 18Y that is a recovery screw as a waste toner conveying screw that is discharged toward one side of the paper in FIG. 2 and a protective agent 42Y as a lubricant that is a lubricant protecting the photosensitive drum 20Y. And a protective film forming device 40Y as a lubricant coating device which is a lubricant coating device which is a protective film forming means to be applied to 20Y.

  The protective film forming apparatus 40Y includes an image carrier protecting agent which is a solid lubricant formed in a bar shape, a protective agent 42Y as an image carrier protecting agent, and a direction opposite to the rotation direction B1 of the photosensitive drum 20Y, that is, Lubricant application member as a scraping member that rotates in the counter direction D1 and scrapes off the protective agent 42Y to supply the photosensitive drum 20Y and apply it to protect the photosensitive drum 20Y. A brush roller 47Y as a lubricant application brush roller, which is a fur brush application brush as a lubricant application brush.

  The protective film forming apparatus 40Y also holds the protective agent 42Y and supports it with respect to the cleaning case 71Y, and supports 49Y as a lubricant holding member that supports the protective agent 42Y in the direction of contacting and separating from the brush roller 47Y. It has a spring 48Y as a spring member as a lubricant pressurizing spring, which is a pressurizing spring as an elastic member as a pressing means for pressing the protective agent 42Y against the brush roller 47Y via the support 49Y.

  The protective film forming apparatus 40Y also includes a cleaning blade 78Y, a voltage applying unit, and a lubricant application driving unit as a driving unit configured to rotate and drive the brush roller 47Y.

  The brush roller 47Y contacts the photosensitive drum 20Y at a position TP downstream of the transfer position NP and upstream of a later-described cleaning position CP in the B1 direction, and at this position TP, the protective agent 42Y contacts the photosensitive drum 20Y. It can be applied. This position TP is a lubricant application position.

  The brush roller 47Y rotates in the direction D1 by the transmission of the rotational driving force from the lubricant application driving means. By this rotation, after the protective agent 42Y is scraped and adhered to the fiber portion of the brush roller 47Y, the surface of the photosensitive drum 20Y at the lubricant application position TP when the brush roller 47Y is in contact with the photosensitive drum 20Y. To be applied.

  The cleaning blade 78Y is made of polyurethane rubber, and is in contact with the photosensitive drum 20Y at an angle similar to a so-called counter type, that is, a reading type. The cleaning position CP is a position where the cleaning blade 78Y contacts the photosensitive drum 20Y and unnecessary materials such as transfer residual toner on the photosensitive drum 20Y are cleaned.

  At the cleaning position CP, the cleaning blade 78Y applies a protective agent 42Y applied or supplied to the photosensitive drum 20Y at the lubricant application position TP by the brush roller 47Y on the photosensitive drum 20Y, and forms a film on the surface of the photosensitive drum 20Y. It functions as a coating blade for forming a protective film as a protective layer. The cleaning blade 78Y leveles the protective agent 42Y on the photosensitive drum 20Y so as to eliminate even a slight distribution unevenness in the protective agent 42Y on the photosensitive drum 20Y.

  Thus, when the brush roller 47Y is rotationally driven, the cleaning device 70Y is driven as the protective film forming device 40Y. The rotation direction of the brush roller 47Y may be the forward direction instead of the reverse direction to the B1 direction.

  The film formed on the surface of the photoconductive drum 20Y by the protective agent 42Y has a function of preventing the surface of the photoconductive drum 20Y from being deteriorated due to proximity discharge, and the protective film forming apparatus 40Y functions as a discharge deterioration preventing means. It is. The deterioration here refers to both wear of the photosensitive drum 20Y due to discharge, acceleration of the wear, and activation of the surface of the photosensitive drum 20Y.

In addition, the coating prevents deterioration such as wear caused by friction between the photosensitive drum 20Y and the cleaning blade 78Y, and the protective film forming apparatus 40Y functions as a friction deterioration preventing unit.
As described above, the protective film forming apparatus 40Y suppresses the deterioration by applying the protective agent 42Y to the surface of the photosensitive drum 20Y.

  Further, the protective film forming apparatus 40Y is a contact brush in which the brush roller 47Y is in contact with the photosensitive drum 20Y, and cleans unnecessary materials such as transfer residual toner on the photosensitive drum 20Y, like the cleaning blade 78. It functions as a cleaning brush as a cleaning member.

  In the image forming apparatus 100 having such a configuration, when copying is performed, a document is set on the document table 22a of the automatic document feeder 22 or the automatic document feeder 22 is rotated upward to be on the contact glass 21a. After the document is placed on the automatic document feeder 22, the automatic document feeder 22 is rotated downward to close the document and press the document, and then the start button on the operation panel is pressed. The document set on the automatic document feeder 22 is, for example, a bundle-shaped sheet document, and the document set on the contact glass 21a is, for example, a single-bound document that is bound in a main shape. When the image forming apparatus 100 is used as a printer, an image forming start operation is performed after image data to be formed is selected and input by an external input device such as a PC connected to the image forming apparatus 100.

  When copying is performed and the document is set on the document table 22a, the document is read by the reading device 21 after the set document is sent onto the contact glass 21a. When the document is placed on 21a, the reading device 21 reads the document when the start button is pressed, and image data is generated.

  Based on the generated image data or the input image data, the image stations 60Y, 60M, 60C, and 60BK having the above-described configuration operate. In addition, when the start button is pressed, in parallel with the document reading operation, each device in the image stations 60Y, 60M, 60C, and 60BK, which are each process cartridge, the transfer belt unit 10, the secondary transfer unit 76, and the fixing device. 6 etc. start driving each. For example, the rotation of the photosensitive drums 20Y, 20C, 20M, 20BK, the transfer belt 11, and the fixing belt 64 is started.

  In the image station 60Y, as described above, the surface of the photosensitive drum 20Y is uniformly charged by the charging device 30Y along with the rotation in the B1 direction, and an electrostatic latent image is formed by the optical scanning device 8, The electrostatic latent image is developed with yellow toner by the developing device 80Y, and the yellow toner image is primarily transferred to the transfer belt 11 by the primary transfer roller 12Y to perform a first transfer process, and after the transfer. Unnecessary substances including the remaining toner are removed by the cleaning device 70Y and used for the next charge removal and charging by the charge removal device 90Y and the charging device 30Y. At this time, the lubricant 42Y is applied to the photosensitive drum 20Y with a suitable particle diameter while suppressing or preventing the unevenness of the surface thereof, and the state of the photosensitive drum 20Y is kept good. A toner image is satisfactorily formed.

  In the other photosensitive drums 20C, 20M, and 20BK, the toner images of the respective colors are similarly formed while maintaining the good state, and the formed toner images of the respective colors, that is, single-color images, are transferred to the primary transfer roller 12C. , 12M, and 12BK, primary transfer is sequentially performed sequentially at the same position on the transfer belt 11 that moves in the A1 direction. A four-color superimposed toner image composed of toner images superimposed on the transfer belt 11, that is, a full-color composite color image that is a four-color toner image, is transferred to the secondary transfer belt 5 as the transfer belt 11 rotates in the A1 direction. To the secondary transfer nip, which is a position opposite to the second transfer nip, is secondarily transferred onto the transfer paper, and a second transfer process is performed, and a full-color image is carried on the transfer paper.

  As for the transfer paper conveyed between the transfer belt 11 and the secondary transfer belt 5, one feed roller 24 of the sheet feeding device 23 is selected by pressing the start button, and the corresponding paper feed cassette is rotated by this rotation. 25, fed from the manual feed tray 33 by the rotation of the feed roller 35 of the manual paper feed device 33, or fed from the duplex unit 96. The toner image on the transfer belt 11 is transferred to the secondary transfer belt by the registration roller pair 13 based on the detection signal from the sensor. 5 is sent out at a timing facing 5. Such a feed operation is started substantially simultaneously with the document reading operation described above.

  When the toner image of all colors is transferred and carried on the transfer paper, it enters the fixing device 6 and passes through the fixing portion between the fixing belt 64 and the pressure roller 63 due to the action of heat and pressure. The carried toner image is fixed, and a good color image is formed on the transfer paper by this fixing process. The fixed transfer paper that has passed through the fixing device 6 is stacked on the paper discharge tray 75 via the paper discharge roller 98 according to the position of the switching claw 94, or when the duplex copying mode is selected. Then, the sheet enters the duplex unit 96 through the transport roller 97 and prepares for duplex image formation. On the other hand, the transfer belt 11 that has finished the secondary transfer is cleaned by removing residual toner and the like remaining on the intermediate transfer belt cleaning device 14 to prepare for the next image formation.

  When such image formation is performed, the fixing belt 64 is driven to rotate and receives pressure from the pressure roller 63. However, in order to perform good fixing and image formation with high image quality, the fixing belt 64 is deteriorated with time. It is important to suppress or prevent. Therefore, in the fixing device 6, measures against deterioration with time of the fixing belt 64 are taken. Details of the fixing device 6 including this point will be described.

  As shown in FIG. 3, the fixing device 6 is wound around the inside of the fixing belt 64, that is, the fixing roller 65 and the stretching roller 62 in addition to the fixing belt 64, the fixing roller 65, the pressure roller 63, and the stretching roller 62. As a configuration disposed inside the inner surface which is the surface in contact with the heater, a heater 66 which is a halogen heater as a heating means for heating the fixing belt 44, and a fixing roller 65 and a stretching roller 62 by the heater 66 are provided. Reflecting plates 67 and 68 are provided for minimizing heating and improving the heating efficiency of the fixing belt 44.

  4 and 5, the fixing device 6 is provided on the inner surface of the fixing belt 64, that is, the surface opposite to the pressure roller 63 of the fixing belt 64, and is a so-called belt when the fixing belt 64 rotates. A detent member 69 that is a deviating restriction member that restricts the deviating movement, that is, the movement of the fixing belt 64 in the width direction, which is the horizontal direction in FIG. 4, is provided. In FIG. 5, the fixing belt 64 and the detent member 69 are released from the state in which the fixing belt 64 is wound around the fixing roller 65 and the stretching roller 62, and the state viewed from the width direction is circular. Only one end side in the width direction is shown. The detent member 69 is a ring-shaped member provided on both sides in the width direction of the fixing belt 64 along the end of the fixing belt 64, specifically, along the edge.

  As shown in FIG. 4, the fixing device 6 also includes a pair of side plates 51 that support both ends of the fixing roller 65 and the pressure roller 63, and a pair of rollers that rotatably support both ends of the fixing roller 65 on the side plate 51. A bearing 52 and a pair of bearings 53 that rotatably support both end portions of the pressure roller 63 on the side plate 51 are provided. The tension roller 62 is also supported by the side plate 51, and the fixing device 6 has a bearing (not shown) in which both ends of the tension roller 62 are rotatably supported by the side plate 51.

  Although not shown in the drawings, the fixing device 6 includes a driving unit that rotationally drives the pressure roller 63, a pressure unit that pressurizes the pressure roller 63 toward the fixing roller 65, and a fixing roller across the fixing belt 64. A temperature sensor as a temperature detecting means disposed at a position facing the fixing belt 65 for detecting the temperature of the outer peripheral surface of the fixing belt 65, and a detection signal of the temperature sensor are inputted, and the outer peripheral surface of the fixing belt 65 is received in response to the detection signal A temperature control device as temperature control means for controlling the operation of the heater 66 so that the temperature becomes a predetermined temperature, and a pressure roller 63 which is disposed downstream of the fixing nip, that is, on the left side in FIG. A separation claw for sliding the tip of the transfer paper from the pressure roller 63 and a transfer paper provided on the surface side of the fixing belt 64, which is also provided on the downstream side of the fixing nip and on the image side. And a separation plate for separating from the belt 64.

  As shown in FIG. 3 or FIG. 4, the fixing roller 65 includes a metal cored bar 65a, an elastic layer 65b provided to be wound around the outer periphery of the cored bar 65a, and an end surface in the width direction of the cored bar 65a. And a rotating shaft 65c that is provided integrally with the core metal 65a so as to protrude from the shaft and is rotatably supported by the bearing 52 at the end, and has an outer diameter of 30 mm. . The core metal 65 a and the rotation shaft 65 c constitute the shaft portion of the fixing roller 65.

  The elastic layer 65b is formed of an elastic body. The elastic body is made of a material selected from a sponge such as a rubber sponge, a soft rubber, and the like. When the elastic body is made of a sponge, it is advantageous in that the temperature rises well due to high heat insulation, a large amount of deformation can be obtained, and a large nip width is secured along the rotation direction of the fixing roller 65. However, the problem is a decrease in elastic force over time.

  The arrangement area of the elastic layer 65b is positioned at the center of the arrangement area of the cored bar 65a in the width direction, and both ends of the cored bar 65a are exposed. The elastic layer 65b is a winding portion around which the fixing belt 64 is wound. The exposed portions of both ends of the cored bar 65a are small-diameter portions having a smaller diameter than the elastic layer 65b serving as a winding portion. The width in the width direction of each of the small diameter portions constituted by the core metal 65a is 4 to 8 mm.

  The tension roller 62 includes a metal cored bar 62a, an elastic layer 62b provided so as to be wound around the outer periphery of the cored bar 62a, and a cored bar 62a so as to protrude from an end face in the width direction of the cored bar 62a. A rotating shaft (not shown) serving as a rotation center of the stretching roller 62 is provided integrally and rotatably supported by a bearing (not shown). The elastic layer 62 b is made of rubber as an elastic body and ensures friction with the inner surface of the fixing belt 64. Thereby, wear of the fixing belt 64 due to sliding between the stretching roller 62 and the fixing belt 64 is reduced.

  The pressure roller 63 includes a metal cored bar 63a, an elastic layer 63b provided so as to be wound around the outer periphery of the cored bar 63a, and a cored bar 63a so as to protrude from an end surface in the width direction of the cored bar 63a. The rotating shaft 63c, which is provided integrally and is rotatably supported by the bearing 53, serves as a rotation center of the pressure roller 63, and a surface layer (not shown) provided on the surface of the elastic layer 63b. Is 30 mm. The elastic layer 63b is made of rubber as an elastic body. The surface layer is a release layer and is formed by a fluororesin coat.

  Although not shown, the fixing belt 64 has an endless, in other words, a support as a belt-like base material, and a surface layer provided on the surface of the support. The support is made of a material selected from a heat resistant resin, a metal, and the like. Examples of the material of the heat-resistant resin that forms the support include polyimide, polyamideimide, and polyether ether ketone. Examples of the material of the metal that forms the support include nickel, aluminum, and stainless steel. In this embodiment, stainless steel is used. The support may be formed as a multilayer of resin and metal. In particular, a belt obtained by electroforming nickel on a polyimide resin is preferable because it has strength and elasticity and is durable. The thickness of the support is desirably 100 μm or less from the viewpoint of suppressing the heat capacity, and in this embodiment is 30 to 80 μm. Since the surface layer is in pressure contact with transfer paper and toner, the surface layer is formed of an elastic layer having a thickness of 100 to 300 μm made of a highly releasable silicone rubber and the like, and a highly releasable resin covering the surface of the elastic layer. And an outermost layer having a thickness of 5 to 50 μm. Examples of such resins include silicone resins, fluororesins, specifically, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer ( FEP) is used, and in this embodiment, the elastic layer is formed by coating PFA. The length of the fixing belt 64 in the rotation direction is 40 mm in diameter before being stretched over the fixing roller 65 and the stretching roller 62 shown in FIG.

  The heater 66 and the reflection plates 67 and 68 are provided inside the fixing belt 64, in other words, inside. The reflection plates 67 and 68 are provided so as to reflect light traveling from the heater 66 toward the stretching roller 62 and the fixing roller 65 so as not to heat the stretching roller 62 and the fixing roller 65 as much as possible. Since the heater 66 concentrates and heats only the fixing belt 64 as much as possible, the temperature raising efficiency of the fixing belt 64 is improved.

The pressurizing unit pressurizes the pressure roller 63 toward the fixing roller 65 by pressing with a spring and a lever, and forms a fixing nip between the fixing belt 64 and the pressure roller 63.
A temperature sensor selected from a thermocouple, a thermistor, or the like is used.

  The driving means has a gear or the like driven by a driving unit provided on the main body 101 side, rotationally drives the pressure roller 63, and moves the fixing belt 64 at 100 to 300 mm / sec by friction in the fixing nip. The belt is driven at a linear speed by driven rotation, and the fixing roller 65 and the stretching roller 62 are driven to rotate by the fixing belt 64. In this way, by driving the fixing belt 64 around, the displacement of the peripheral speed with the pressure roller 63 when the fixing belt 64 is rotationally driven by a gear, for example, is prevented or suppressed, and as a result, the fixing belt. 64 is driven at the same speed as the pressure roller 63. Such a difference in peripheral speed between the fixing roller 65 and the pressure roller 63 is due to differences in the thickness and hardness of the elastic layers 65b and 63b, and the degree of crushing of these elastic layers 65b and 63b is different. This is due to the fact that a difference in the circumferential length between the roller 65 and the pressure roller 63 tends to occur. For this reason, the fixing belt 64, the fixing roller 65, and the stretching roller 62 are rotated together with the pressure roller 63. If a minute slip due to this rotation becomes a problem, the fixing roller 65 is moved in one way. Driving from the drive unit is transmitted through a clutch or the like, and the fixing roller 65 is only when the rotation speed of the fixing belt 64, the fixing roller 65, and the stretching roller 62 becomes lower than the rotation speed of the pressure roller 63 due to slip or the like. May be driven.

  The width of the fixing nip, that is, the nip width along the rotation direction of the fixing roller 65 is set to a desired value by adjusting the diameters of the fixing roller 65 and the pressure roller 63, and the thickness and hardness of the elastic layers 65b and 63b. The temperature and surface pressure of the fixing nip are adjusted by a temperature control device and a pressurizing unit so that image defects such as so-called cocoon skin with fine unevenness as image misalignment, insufficient glossiness, and poor graininess occur. And pressure are set under the conditions to be applied.

  As shown in FIG. 4, the detent member 69 has a quadrangular cross-sectional shape perpendicular to the rotational direction, a width in the width direction of 3 to 6 mm, and a thickness of 1 mm or more. The detent member 69 is made of rubber which is an elastic member as an elastic body. Such a rubber is a heat-resistant rubber, and in this embodiment is a silicone rubber. The cross-sectional shape may be trapezoidal.

  The stopper member 69 is fixed to the fixing belt 64 by bonding with an adhesive that is easy to manufacture. When the support member of the fixing belt 64 is made of polyimide resin, the detent member 69 may be molded and fixed by a press mold heated to a high temperature. In this case, an adhesive process is not required and the cost is low. Excellent heat resistance, sufficient strength and excellent durability.

  The belt shift is a phenomenon in which, when the fixing belt 64 is rotated, it approaches one of the axial directions of the fixing roller 65, the pressure roller 63, and the stretching roller 62, which coincides with the width direction of the fixing belt 64. This is caused by the difference in pressure balance in the axial direction. Since the pressurization balance changes due to the deterioration of the elastic layers 65b, 63b, and 62b over time, the belt shift is not completely prevented only by adjusting the initial pressurizing means. The belt misalignment is a cause of the meandering of the fixing belt 64, and thus is also a cause of image misalignment and paper wrinkles due to the meandering of the fixing belt 64.

  Therefore, when the belt shift occurs, if there is no shift stop member 69 in the scale, image misalignment or paper wrinkles due to the meandering of the fixing belt 64 may occur, and in addition to this, if the belt shift is left unattended, eventually. May be damaged when the fixing belt 64 hits the side plate 51 or the like. In order to prevent this, the stopper member 69 is provided so as to regulate the belt offset, and the end surface in the width direction is an elastic portion in which the fixing roller 65 is wound around the fixing belt 64. By striking against the end face of the layer 65b, further belt slippage is prevented, and excessive belt slippage where the fixing belt 64 strikes the side plate 51 or the like is prevented. Thereby, image misalignment and paper wrinkles due to meandering of the fixing belt 64 are prevented or suppressed, and the possibility of the fixing belt 64 being damaged due to the fixing belt 64 hitting the side plate 51 or the like is reduced.

  However, when the detent member 69 is provided, the fixing belt 64 may deteriorate at the boundary portion between the portion where the detent member 69 is provided and the portion where the detent member 69 is not provided. That is, for example, as shown in FIG. 9, if the detent member 69 is located in the non-arrangement region of the pressure roller 63 in the width direction, the fixing belt is in contact with the end surface of the fixing roller 65. When a force is applied in such a direction that the belt 64 rotates and the belt becomes larger, a force for bending the fixing belt 64 is applied to the boundary portion. Further, as shown in FIG. 10, the fixing belt 64 is pressed by the pressure roller 63 even when the detent member 69 is located in the arrangement region of the pressure roller 63 in the width direction. By this pressurization, a force for bending the fixing belt 64 is applied to the boundary portion. In particular, as shown in FIG. 5B, in the pressure roller 63 having the elastic layer 63a, the fixing belt 64 is deformed so as to be bent inward by the elastic deformation of the elastic layer 63a. When the fixing device 6 is driven for a long time in this state, the bent portion becomes weak. Furthermore, if the bent portion vibrates due to slight fluctuations when the fixing roller 65 or the pressure roller 63 rotates in such a state or slight variations in the hardness of the elastic layers 63a and 65a, the fixing belt 64 is repeatedly applied. It will give fatigue. As described above, when the boundary portion where the force that bends the fixing belt 64 is applied repeatedly for a long period of time, the fixing belt 64 deteriorates, the strength is lowered, and the fixing belt eventually cracks, causing damage. End up. This tendency becomes more conspicuous when the fixing belt 64 is a metal belt than when the fixing belt 64 is a resin belt. Also, when the fixing belt 64 rotates with the stopper member 69 in contact with the end surface of the fixing roller 65 and a force is applied to increase the belt offset, the stopper member 69 gets over the fixing roller 65 and the side plate 51. The fixing belt 64 may be damaged.

  In the fixing device 6, countermeasures against such problems as deterioration with time of the fixing belt 64 are taken. That is, the detent member 69 is sandwiched and pressed together with the fixing belt 64 between the cored bar 65a, which is the small diameter portion of the fixing roller 65, and the pressure roller 63, and as shown in FIG. As described above, the posture of the fixing belt 64 is stabilized, the bending of the boundary portion is suppressed or prevented, and the detent member 69 is prevented from getting over the fixing roller 65. Thus, the fixing member 64 is niped from the inner side of the fixing belt 64 with the cored bar 65a and pressurized from the inner side, that is, the side of the cored bar 65a and the outer side, that is, the fixing belt, and the pressure roller 63 side. By substantially suppressing or preventing the deformation, vibration, etc., the deterioration of the fixing belt 64 over time and the damage resulting therefrom are reduced or prevented.

  In particular, in this embodiment, since the stopper member 69 is an elastic body, it is easy to sandwich and press-contact the stopper member 69 so that the core metal 65a, which is a small diameter portion, is bitten. At the same time, even if there is a part processing tolerance, a slight vibration when the fixing roller 65 or the pressure roller 63 rotates, and a slight variation in the hardness of the elastic layers 63a and 65a due to such bite, the posture of the fixing belt 64 is further increased. As a result, the deterioration and the like of the fixing belt 64 can be suppressed or prevented more highly, and the fixing roller 65 can be prevented from getting over. Such an effect is exhibited particularly well when the amount of biting is 0.2 to 1.0 mm. The width of the cored bar 65a, which is the small diameter portion, is slightly larger than the width of the detent member 69, so that the belt is prevented from being largely deviated.

  In order to better regulate the belt deviation by the detent member 69, as shown in FIGS. 7 and 8, the fixing roller 65 may include a small-diameter portion as a groove-shaped portion 54 formed of a concave groove. . By providing the groove-shaped portion 54, the movement of the detent member 69 is regulated on both sides in the width direction, so that the deviation of the belt is better regulated.

  The groove-shaped portion 54 shown in FIG. 7 is formed by the core metal 65a having the flange 65d. The width of the groove-shaped portion 54 is slightly larger than the width of the detent member 69 in the same manner as in the above-described configuration example, thereby preventing the belt from being largely deviated. In other respects, the configuration example shown in FIG. 7 is the same as the configuration example described above.

  The groove-shaped portion 54 shown in FIG. 8 has a bearing 65e as a rotating member that is rotatable with respect to the rotation shaft 65c. This bearing 65e is formed by having a flange 65f. The bearing 65e is a rolling bearing or a sliding bearing, and when it is a rolling bearing, any of balls, rollers, and cones may be used as the rolling element. Since the portion of the bearing 65e where the detent member 69 is in contact with the rotation shaft 65c freely rotates as the rotation member, the peripheral speed of the rotation shaft 65c and the peripheral speed of the detent member 69 are slightly different. Even in such a case, the fixing belt 64 moves smoothly. Such a difference in peripheral speed is caused by deformation of the stopper member 69 due to biting, bending deformation of the stopper member 69 when the diameter of the fixing roller 65 is small, or the like. Reference numeral 55 denotes a stopper ring. The width of the groove-shaped portion 54 is slightly larger than the width of the detent member 69 in the same manner as in the above-described configuration example, thereby preventing the belt from being largely deviated. In other respects, the configuration example shown in FIG. 7 is the same as the configuration example described above. Note that the bearing 65e does not necessarily include the groove-shaped portion 54, and even if the groove-shaped portion 54 is not included, the peripheral speed of the rotating shaft 65c and the peripheral speed of the detent member 69 are delicate. The effect is that the fixing belt 64 moves smoothly in different cases.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, the winding roller is not limited to the fixing roller as long as it is a roller-shaped member that presses the fixing belt around the pressure roller around which the fixing belt is wound. It may be.

  Even if the image forming apparatus is a tandem type, a direct transfer system can be adopted instead of the indirect transfer system described above. The direct transfer type image forming apparatus includes a sheet conveyance belt which is a recording medium conveyance body as an image carrier instead of the transfer belt 11 described above, and an image station on a transfer paper in the process of being conveyed by the sheet conveyance belt. The toner images of the respective colors formed with 60BK, 60C, 60M, and 60Y are sequentially transferred in an overlapping manner.

  The image forming apparatus is not a so-called tandem type image forming apparatus, but a so-called one-drum type image forming apparatus that sequentially forms toner images of respective colors on a single photosensitive drum and sequentially superimposes the color toner images to obtain a color image. The present invention can be similarly applied to an image forming apparatus. In this case, in order to increase the first copy speed, it is preferable to perform black image formation first, and then perform image formation for the remaining colors only when the original is in color.

  In addition, in recent years, in accordance with demands from the market, color image forming apparatuses, such as color copiers and color printers, have increased in number, but image forming apparatuses can only form monocolor images. It may be.

  The developer used in such an image forming apparatus is not limited to a two-component developer but may be a one-component developer. Furthermore, the image to be fixed on the recording medium by the fixing device is not limited to that formed with toner, but may be formed with ink or the like, and the image forming apparatus forms an image with ink or the like in this way. It may be what you do.

  The image forming apparatus may not be a copier, a printer, and a facsimile machine, but may be a single unit thereof, or may be a multi-function machine of another combination such as a copier and printer. .

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

54 groove-shaped portion 63 pressure roller 64 fixing belt 65 winding roller 65a, 65e small diameter portion 65b winding portion 65e rotating member 69 detent member 100 image forming apparatus

JP 2005-017482 A JP 2008-169008 A JP 2009-151260 A JP 2005-258341 A JP 2001-083822 A JP 2005-234294 A Japanese Patent No. 4298542

Claims (6)

An endless fixing belt, a winding roller around which the fixing belt is wound, a pressure roller for pressing the fixing belt between the winding rollers, and a pressure roller on the opposite side of the pressure roller to the pressure roller. A detent member provided on the surface for regulating the displacement of the fixing belt,
The detent member is in contact with a small diameter portion of the winding roller that is smaller in diameter than the winding portion around which the fixing belt is wound, and is sandwiched between the fixing belt and the small diameter portion by the pressure roller. Fixing device. The fixing device according to claim 1.
The fixing device, wherein the winding roller includes a rotating member that is rotatable with respect to the winding roller body, and the rotating member is provided as the small-diameter portion. The fixing device according to claim 1 or 2,
The fixing device, wherein the winding roller includes the small-diameter portion as a groove-shaped portion. In the fixing device according to any one of claims 1 to 3,
The fixing device according to claim 1, wherein an amount of biting of the small diameter portion with respect to the detent member is 0.2 to 1.0 mm. In the fixing device according to any one of claims 1 to 4,
The fixing device according to claim 1, wherein the stopper member is an elastic body.   An image forming apparatus comprising the fixing device according to claim 1.

Images