JP2007240739A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent bias of a belt in an upper and lower belt fixing device. <P>SOLUTION: The fixing device has: an endless fixing belt 1 whose outer circumferential surface faces an unfixed image carrying surface of a transfer material to which an image is transferred; an endless pressurizing belt whose outer circumferential surface faces a non-carrying surface of an unfixed image of the transfer material; and a plurality of guide members which are provided in the inner surfaces of each of the fixing belt and the pressurizing belt and guide belt run. The fixing device fixes the image on the transfer material by passing the transfer material through a contact area between the fixing belt and the pressurization belt, wherein the guide member is provided outside a fixing nip area in the conveyance direction of the transfer material which passes through the guide member and a regulation member which regulates both edges of the fixing belt and the pressurization belt is provided on at least one extended line in the axial direction of the guide member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device for heating and pressure-fixing an unfixed toner image in an image forming apparatus using an electrophotographic system such as a copying machine, a printer, and a facsimile, and in particular, two endless belts are arranged in pressure contact with each other. The upper and lower belt fixing device.

  Conventionally, as a fixing device used in an image forming apparatus, a heat roller system in which a fixing roller and a pressure roller are arranged in pressure-contact manner has been widely used. However, in the heat roller system, since the heat capacity of the fixing roller is large, in order to shorten the first print time, the roller has to be preheated in a standby state at all times, and wasteful energy is consumed.

  In recent years, a fixing device using an endless belt instead of a fixing roller or a pressure roller has been proposed and put into practical use (for example, see Patent Documents 1 to 3).

  The fixing device using the endless belt has an advantage that the belt itself has a smaller heat capacity than the fixing roller or the pressure roller. In addition, a wide fixing nip can be secured as compared with the conventional heat roller system, and the pressure applied at the fixing nip can be made relatively low. Accordingly, since it is not necessary to increase the rigidity and strength of the members constituting the fixing device and increase the heat capacity of the entire fixing device, it is possible to realize rapid heating of the fixing device even when the speed of the image forming apparatus is increased. . As a result, it is possible to cope with energy saving and high speed. Among these, the form that can achieve the above-described reduction in heat capacity is an upper and lower belt fixing device configured by opposing two endless belts (see, for example, Patent Document 1).

  Here, the fixing device using the endless belt has a technical problem that the belt is shifted (a phenomenon in which the belt moves toward one of the belt axial directions during traveling). The cause of this is due to the difference in circumferential length at both ends of the belt, the load difference in the axial direction at the fixing nip, or the non-parallelism of the belt guide member and the fixing nip forming member due to component accuracy and device assembly accuracy. When the belt is deviated, there is a possibility that an image defect may occur.

  In order to prevent the deviation of the belt, a mechanism for controlling the deviation of the belt by displacing at least one of the rollers that stretch the belt has been proposed and put into practical use (for example, Patent Documents 1 and 2). reference). Further, in a fixing device in which a roller and an endless belt are combined in pairs, there is a configuration in which a belt regulating member is disposed on a roller shaft (see, for example, Patent Document 3). According to this configuration, the belt edge is regulated by abutting the belt edge on the extension line of the fixing nip against the regulating member.

JP-A-11-174878 JP 05-150679 A JP 10-020691

  However, as in Patent Document 1 and Patent Document 2, a method having a mechanism for controlling the deviation of the belt increases the number of members and is expensive because a special mechanism is provided. Therefore, as shown in FIG. 9, a low-cost configuration is proposed and put into practical use in which a flange member is provided on the same axis as the roller that stretches the belt, and the belt edge is abutted against the flange member to regulate the deviation of the belt. ing.

  However, when this method is applied to the previous upper and lower belt fixing device, it is necessary to arrange the flange members provided on the stretching roller so as not to interfere with each other. For this reason, as shown in FIG. 9, it is necessary to make the width W (axial length) of the belt different from the length L (inner circumferential length) when stretched between the upper and lower belts. As a result, there is a problem that the fixing device main body is increased in size.

  Further, as in Patent Document 3, a fixing device in which a roller and an endless belt are combined in pairs includes a configuration as shown in FIG. That is, the belt regulating member 115 is disposed on the shaft of the roller 111, and the edge of the belt 113 on the fixing nip extension line is abutted against the regulating member 115 to regulate the deviation of the belt 113. As shown in FIG. 11, this method is characterized in that the shifting force of the pressure belt 113 generated at the fixing nip is canceled out by the restriction force on the extension of the fixing nip.

  However, in this configuration, since the edge of the pressure belt 113 constrained by the fixing nip and the regulating member 115 are rubbed strongly, the edge of the pressure belt 113 is easily worn. As the wear progresses, the end of the pressure belt 113 may be broken due to durability or the like. In addition, a roller having a rotation shaft while forming a fixing nip is indispensable for this configuration, and is not suitable for the above-described upper and lower belt fixing devices most suitable for energy saving and speeding up.

  An object of the present invention is to effectively prevent the belt from shifting in an upper and lower belt fixing device.

  To achieve the above object, a typical configuration according to the present invention includes an endless fixing belt having an outer peripheral surface facing an unfixed image carrying surface of a transfer material onto which an image is transferred, and an unfixed image of the transfer material. An endless pressure belt having an outer peripheral surface facing the non-carrying surface, and a plurality of guide members on the inner surfaces of the fixing belt and the pressure belt for guiding belt travel, and the fixing In a fixing device that fixes an image on the transfer material by passing the transfer material through a contact area between the belt and the pressure belt, the fixing device is provided outside the fixing nip region in the conveyance direction of the transfer material passing through the guide member. A restriction member for restricting both end edges of the fixing belt and the pressure belt is provided on at least one of the extension lines in the axial direction of the guide member.

  With the above configuration, it is possible to effectively prevent the belt from shifting in the upper and lower belt fixing device.

[First Embodiment]
A first embodiment of the present invention will be described with reference to the drawings.

(Image forming device 50)
A schematic configuration of an image forming apparatus 50 using the fixing device 21 of the present embodiment will be described with reference to FIG. FIG. 8 is a schematic sectional view of the image forming apparatus.

  The image forming apparatus 50 forms one image by sequentially transferring toner images of four colors of yellow Y, magenta M, cyan C, and black K onto the transfer material P carried on the recording material conveyance belt 59. To do.

  On the peripheral surface of the photosensitive drum 51 as an image carrier, a charger 52, an exposure device 53 for irradiating the photosensitive drum 51 with a laser beam, a developing device 55, and a recording in order along the rotation direction (arrow R1 direction). A transfer roller 60 and a photosensitive drum cleaner 66 are disposed via a material conveying belt 59. Except for these exposure devices 53, they are integrally disposed in the developing cartridge 70.

  The surface of the photosensitive drum 51 is charged to a negative polarity by the charger 52. An electrostatic latent image is formed on the surface of the charged photosensitive drum 51 by the exposure L of the exposure device 53 (the surface potential of the exposed portion is increased). The developer 55 containing the first color yellow toner attaches toner to the electrostatic latent image portion on the photosensitive drum 51 to form a toner image.

  On the other hand, the recording material transport belt 59 is supported by two support shafts (a driving roller 62 and a tension roller 64), and is rotated in the direction of the arrow R3 by the driving roller 62 that rotates in the direction of the arrow R4 in the drawing. When the transfer material P is fed by the feed roller 54, the transfer material P is charged by the suction roller 56 to which a positive polarity bias is applied, electrostatically attracted onto the recording material transport belt 59, and transported.

  When the transfer material P is conveyed to the transfer nip N0, a positive transfer bias is applied from a power source (not shown) to the transfer roller 60 that is driven to rotate by the recording material conveyance belt 59. Then, the yellow toner image on the photosensitive drum 51 is transferred onto the transfer material P at the transfer nip N0. The transfer residual toner on the surface of the photosensitive drum 51 after the transfer is removed by a photosensitive drum cleaner 66 having an elastic blade.

  The series of image forming processes of charging, exposing, developing, transferring, and cleaning are sequentially performed on the developing cartridges 70 of magenta M for the second color, cyan C for the third color, and black K for the fourth color. The four color toner images overlap the transfer material P on the recording material conveyance belt 59. The transfer material P carrying the four color toner images is conveyed to the fixing device 21 and the toner image on the surface is fixed.

(Schematic configuration of the fixing device 21)
FIG. 1 is a cross-sectional view of the fixing device according to the first embodiment, and FIG. 2 is a perspective view of the fixing device according to the first embodiment.

  As shown in FIGS. 1 and 2, the fixing device 21 is an upper and lower belt fixing device configured by opposing two endless belts. The endless belt located in the upper part is the fixing belt 1, and the endless belt located in the lower part is the pressure belt 2.

  The fixing belt 1 is stretched by two roller-shaped fixing belt guides (guide members) 4 that guide the traveling of the fixing belt 1. The pressure belt 2 is stretched by two roller-shaped pressure belt guides (guide members) 3 on the inner surface of the pressure belt for guiding the travel of the pressure belt. It is provided outside the fixing nip region in the conveyance direction of the transfer material P passing through the guide member,

  A ceramic heater 5 as a heating source is disposed on the inner surface of the fixing belt 1. The ceramic heater 5 is disposed from the inner surface on the contact surface of the fixing belt 1 with the pressure belt 2. A pressure member 6 is disposed on the inner surface of the pressure belt 2 at a position facing the ceramic heater 5. The pressing member 6 is pressed by a pressing mechanism (not shown) in the direction D in the drawing.

  On the extension of the fixing belt guide 4 in the axial direction, a regulating flange (regulating member) 7 that regulates the edges of the fixing belt 1 and the pressure belt 2 is disposed.

(Detailed configuration of fixing device 21)
The fixing belt 1 and the pressure belt 2 are endless belts based on a heat-resistant resin such as polyimide having a thickness of 50 μm to 100 μm, or a metal such as Ni or SUS, for example. On the base layer, an elastic layer such as Si rubber and a release layer such as PFA are laminated with a thickness of 300 μm and 30 μm, respectively. In this embodiment, a configuration in which the same endless belt is used for the fixing belt 1 and the pressure belt 2 is illustrated.

  The pressure belt guide 3 and the fixing belt guide 4 are rollers that are rotatably provided on the inner surface of each belt. In the present embodiment, the fixing belt 1 and the pressure belt 2 are stretched.

  One of the fixing belt guides 4 (in this embodiment, the fixing belt guide 4 on the downstream side in the transfer material conveyance direction) is a driving roller that is driven in the E direction in FIG. 2 by a driving source of the image forming apparatus main body. . The driving roller drives the fixing belt 1 by friction between the fixing belt guide 4 and the inner surface of the fixing belt 1.

  The ceramic heater 5 is a plate-like heater in which a heat generation pattern in which an electric resistance material is applied on an insulating substrate is formed and coated thereon with an insulating layer. The material is, for example, alumina as the insulating substrate, Ag / Pd (silver palladium) as the electric resistance material, and is applied by screen printing to a thickness of about 10 μm and a width of 1 to 3 mm, and the insulating layer is made of glass or fluorine. Resin or the like can be used. The ceramic heater 5 contacts the inner surface of the fixing belt 1 to heat the fixing belt 1 to a predetermined fixing temperature.

  A temperature detection element (not shown) contacts the surface of the fixing belt 1. The surface temperature of the fixing belt 1 is detected by the temperature detection element.

  The fixing device control circuit of the image forming apparatus main body compares the detected temperature of the temperature detecting element with a preset fixing temperature. When the detected temperature is low, the ceramic heater 5 is energized to generate heat, and when the detected temperature is high, the energization to the ceramic heater 5 is interrupted. Thereby, the surface temperature of the fixing belt 1 is kept at the fixing temperature.

The pressure member 6 facing the ceramic heater 5 is made of, for example, a metal such as aluminum, and is composed of an elastic layer such as Si rubber and a release layer such as PFA. The pressure member 6 presses the pressure belt 2 toward the fixing belt 1 from the inner surface of the pressure belt 2, thereby pressing the fixing belt 1 and the pressure belt 2 against the ceramic heater 5. Here, the applied pressure is, for example, about 30 kgf (2.9 × 10 ² N). As a result, the pressure belt 2 is pressed against the fixing belt 1 to form a fixing nip N as a contact area where pressure (for example, about 1.0 kgf / cm ² (9.8 × 10 ⁴ N / m ² )) acts uniformly. .

  The restriction flange 7 is formed of a heat resistant resin such as LCP or PPS, and is configured coaxially with the fixing belt guide 4. The outer periphery of the restriction flange 7 is larger than the outer diameter of the fixing belt guide 4 and has a restriction surface orthogonal to the axis of the fixing belt guide 4. As shown in FIG. 1, the outer periphery of the restriction flange 7 is large enough to cover the periphery of the pressure belt guide 3 when viewed from the side of the fixing device 21. For this reason, the restriction flange 7 guides not only the fixing belt 1 but also the pressure belt 2 stretched around the pressure belt guide 3.

(Operation of fixing device 21)
The operation during operation of the fixing device 21 will be described. When the driving force is transmitted from the fixing belt guide 4 to the fixing belt 1 and the fixing belt 1 is rotated and conveyed, the pressure belt 2 that is in pressure contact with the fixing belt 1 at the fixing nip N is driven and rotated by the frictional force with the fixing belt 1. To do.

  In this state, the transfer material P is conveyed from the image forming apparatus transfer unit (not shown) to the fixing nip N of the fixing device 21 from the direction F in FIG. Here, the transfer material P is in a state where an unfixed image is transferred to the fixing belt 1 side. The transfer material P passes through the fixing nip N together with the fixing belt 1 and the pressure belt 2 and is heated and pressed by the fixing belt 1 and the pressure belt 2 to fix the unfixed image. The

(Mechanism to prevent belt slippage)
As shown in FIG. 1, the pressure belt guide 3 and the fixing belt guide 4 are arranged with a gap C therebetween. For this reason, the fixing belt 1 and the pressure belt 2 do not come into contact with other than the fixing nip N.

  The restriction flange 7 is coaxial with the fixing belt guide 4 and is larger than the outer diameter of the fixing belt guide 4. Since it is such a form, first, the edge of the fixing belt 1 is regulated by the regulation flange 7.

  In the present embodiment, the edge of the pressure belt 2 by the restriction flange 7 is also restricted. This configuration will be described below with reference to FIG. FIG. 3 is a top view of the pressure belt 2 that passes through the fixing nip N and is conveyed in the G direction in the drawing.

  In FIG. 3, a state where a belt shift occurs in the pressure belt 2 driven by the fixing belt 1 is shown as a pressure belt 2 a. As a factor of the belt shift, there are a circumferential length difference at both ends of the belt, a pressure difference at both ends of the fixing nip, a temperature difference, and the like.

  The pressure belt 2a in a state where the belt is shifted travels with an inclination angle α as shown in FIG. Therefore, in the fixing nip N, the conveying force F received by the pressure belt 2a from the fixing belt 1 is decomposed into a rotational force Fr and an axial force Fa of the pressure belt 2a. In other words, the pressure belt 2a is offset by the axial force Fa.

  The regulating flange 7 regulates the edge of the pressure belt 2 at a distance L from the fixing nip, and moves the edge of the pressure belt 2 a toward the inside of the axis of the pressure belt guide 3 with the regulation force Na. In this manner, by returning the pressure belt 2a to the normal posture of the pressure belt 2, the deviation of the belt is suppressed. Here, if the pressure belt 2 has a buckling proof strength against the regulating force Na, the regulating method shown in FIG. 3 does not cause wrinkles or breakage due to buckling of the edge of the pressure belt.

  Further, according to this configuration, the posture of the pressure belt 2 is changed by the moment (L · Na · cos α) about the fixing nip N. For this reason, by increasing the distance L from the center of the fixing nip N to the edge of the pressure belt 2, the regulation force Na applied to the edge of the pressure belt can be reduced. As a result, wear on the edge of the pressure belt due to durability or the like can be reduced.

  This embodiment has the following effects.

  In the present embodiment, a restriction flange 7 that restricts the fixing belt 1 and the pressure belt 2 on the same surface is provided on the axial extension line of the pressure belt guide 3 that guides the travel of the fixing belt 1. As a result, the width and length of the fixing belt 1 and the pressure belt 2 can be made the same. As a result, the same component can be used for both the fixing belt 1 and the pressure belt 2, and the cost for component management can be reduced. Further, by using the same parts, it is possible to prevent erroneous assembly of the belt.

  Further, both the fixing belt 1 and the pressure belt 2 can be regulated on the same surface. For this reason, the accuracy of the upper and lower belt regulating positions can be improved, and the above-described image defects can be reduced.

  In this embodiment, the pressure belt edge is regulated by a regulation flange provided outside the fixing nip N area. For this reason, the regulating force to the pressure belt edge can be reduced. Further, it is possible to receive the regulating force in a state where the pressure belt 2 is not restrained by the fixing nip N, that is, in a state having a degree of freedom in the axial direction. Accordingly, it is possible to reduce wear due to the regulating force of the end edge of the pressure belt 2. As a result, the life of the pressure belt 2 can be extended.

  In this embodiment, the configuration in which the restriction flanges are provided at both ends on the axial extension line of the fixing belt guide is exemplified, but the present invention is not limited to this. The same effect can be obtained when the same restriction flange 7 is provided for the pressure belt guide 3 or when it is provided only at one end of the belt guide. Furthermore, in the present embodiment, the fixing belt guide 4 and the restriction flange 7 are illustrated as separate bodies, but they may be configured integrally. In this case, the same effect can be obtained.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to the drawings. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 4 is a perspective view and a side view of the fixing device according to the second embodiment.

  As shown in FIG. 4, the fixing device 22 of the present embodiment is also an upper and lower belt fixing device configured by opposing two endless belts of the fixing belt 1 and the pressure belt 2. In the present embodiment, two fixing belt guides (guide members) 9 that stretch the fixing belt 1 are disposed on the inner surface of the fixing belt 1, and the pressure belt 2 is disposed on the inner surface of the pressure belt 2. Two pressure belt guides (guide members) 8 are provided.

  The pressure belt guide 8 and the fixing belt guide 9 in the present embodiment are fixed guides formed of a heat resistant resin such as PPS or polyamide, for example. In each belt guide, in order to reduce the contact area with the inner peripheral surface of the belt, a rib is provided in the circumferential direction on the outer peripheral surface that rubs against the inner surface of each belt.

  In the present embodiment, a restriction flange (restriction member) 10 is provided at each of both axial ends of one of the two pressure belt guides 8 and one of the two fixing belt guides 9. It is done. Further, as shown in FIG. 4, a regulating flange 10 is disposed on one belt guide edge of the pressure belt guide 8 and the fixing belt guide 9 that are in contact with each other via the belt. When arranged alternately in this way, the regulating flanges 10 provided on the pressure belt guide 8 and the fixing belt guide 9 do not interfere with each other.

  Even with such a configuration, the belt can be prevented from shifting as in the first embodiment.

[Third Embodiment]
A third embodiment of the present invention will be described with reference to the drawings. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 5 is a perspective view of a fixing device according to the third embodiment.

  As shown in FIG. 5, the fixing device 23 of the present embodiment is also an upper and lower belt fixing device configured by opposing two endless belts of the fixing belt 1 and the pressure belt 2. In the present embodiment, two fixing belt guides (guide members) 11 that stretch the fixing belt 1 are disposed on the inner surface of the fixing belt 1, and the pressure belt 2 is disposed on the inner surface of the pressure belt 2. Two pressure belt guides (guide members) 12 are provided.

  The fixing belt guide 11 and the pressure belt guide 12 are rollers rotatably provided as in the embodiment, but the rotation axis directions are non-parallel. Specifically, as shown in FIG. 5, the upstream belt guide is disposed at an angle θ with respect to the downstream belt guide. That is, when the fixing device 23 is viewed from above, the belt guide is disposed so as to have a substantially C shape.

  According to the present embodiment, as shown in FIG. 5, the belt that is guided by the inclined belt guide travels only in the direction of one end portion (H direction in the drawing) of the belt guide having a narrow interval. Thus, since the direction in which the belt approaches is constant, the regulating flange (regulating member) 13 is disposed only at the end portion in the H direction among the belt guide shaft end portions.

  Also in the configuration of the present embodiment, the regulation surface of the regulation flange 13 is a configuration that regulates the fixing belt 1 and the pressure bell 2 with the same regulation surface. In the present embodiment, the restriction surface also restricts the edge of the transfer material P. For this reason, the regulation surface also serves as a conveyance reference surface.

  This embodiment has the following specific effects.

  The fixing belt 1, the pressure belt 2, and the transfer material P can be regulated on the same surface of the regulation flange. For this reason, the three members can be transported as one body while improving the positional accuracy during transport of the upper and lower belts and the transfer material P, and image defects due to the deviation of the belt can be further reduced.

  In the present embodiment, one of the fixing belt guide and the pressure belt guide is inclined with respect to the other so that the belt approaches only in one direction, but the present invention is not limited to this configuration. For example, one of the belt guides may be tapered so that the outer diameter increases in the direction of travel, and the other belt guide and the central axis may be arranged in parallel. In the present embodiment, the configuration in which the belt approaches only in one direction is not limited, and various devices can be applied.

[Fourth Embodiment]
A fourth embodiment of the present invention will be described with reference to the drawings. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 6 is a perspective view of a fixing device according to the fourth embodiment.

  As shown in FIG. 6, the fixing device 24 according to the present embodiment is also an upper and lower belt fixing device configured by opposing two endless belts of the fixing belt 1 and the pressure belt 2. In the present embodiment, two fixing belt guides 4 for stretching the fixing belt 1 are disposed on the inner surface of the fixing belt 1, and the pressure belt 2 is stretched on the inner surface of the pressure belt 2. Two pressure belt guides 3 are provided.

  Further, a regulating flange (regulating member) 14 is disposed at one end of the two pressure belt guides 3 in the axial direction, and a regulating flange (regulating member) 15 is disposed at the other end. Here, the restricting flange 14 is fixedly disposed as in the first embodiment. On the other hand, the restriction flange 15 is disposed so as to be swingable in the direction of the rotation axis of the pressure belt guide 3. Then, it is pressed in the axial direction (J direction in the figure) of the fixing belt 1 by a pressure mechanism (not shown).

  Therefore, the both end edges of the fixing belt 1 and the both end edges of the pressure belt 2 are always in contact with the restricting flanges 14 and 15 by pressing from the restricting flange 15 and the posture is restricted.

  In this embodiment, the present embodiment is also characterized in that the belt edge regulating surface of the regulating flange 14 also serves as the conveyance reference surface of the transfer material P, as in the third embodiment. This embodiment has the same effect as the third embodiment.

[Fifth Embodiment]
A fifth embodiment of the present invention will be described with reference to the drawings. The same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 7 is a cross-sectional view of a fixing device according to the fifth embodiment.

  As shown in FIG. 7, the fixing device 25 of the present embodiment is also an upper and lower belt fixing device configured by opposing two endless belts of the fixing belt 1 and the pressure belt 2. In the present embodiment, two fixing belt guides 4 for stretching the fixing belt 1 are disposed on the inner surface of the fixing belt 1, and the pressure belt 2 is stretched on the inner surface of the pressure belt 2. Two pressure belt guides 3 are provided.

  In the fixing device 25 according to the present embodiment, the restriction flange (regulation member) 7 and the base layers of the fixing belt 1 and the pressure belt 2 are formed of a conductive material. Then, the outermost surfaces of the fixing belt 1 and the pressure belt 2 are formed with the amount of electrical insulating material. On the inner surfaces of the fixing belt 1 and the pressure belt 2, that is, the base layer surface, an electrical contact portion K and an electrical contact portion M shown in FIG. 7 are provided. Moreover, it has the detection means 16 which detects the conduction | electrical_connection state of the electric current of the electrical contact part K and the electrical contact part M, and alert | reports a detection state to the control circuit not shown.

  In such a configuration, when the fixing belt 1 and the pressure belt 2 are simultaneously restricted by the restriction flange 7, between K and M, that is, the electrical contact portion K, the base layer of the fixing belt 1, the restriction flange 7, and the pressure belt. An electrical conduction path from the second base layer to the electrical contact portion M is formed. On the other hand, in a state where both the fixing belt 1 and the pressure belt 2 are not regulated by the regulation flange 7, the conduction path is blocked.

  The open / close information of the conduction path can be detected by measuring the electrical resistance between K and M, for example. The control circuit of the image forming apparatus main body performs transfer material conveyance control to the fixing device based on the detection information of the detection means 16. That is, the image forming apparatus can convey the transfer material to the fixing device only when the fixing belt 1 and the pressure belt 2 are simultaneously in the edge regulation position, that is, when the conduction path is formed. Become.

  This embodiment has the following specific effects.

  When the retention of the transfer material (JAM) occurs in the fixing device, the fixing belt 1 and the pressure belt 2 are moved by the retained transfer material P depending on the discharging process of the retained transfer material P. Then, the position of the belt may shift in the axial direction.

  By using the control for conveying the transfer material P by detecting the regulation state of both belts as in this embodiment, it is possible to prevent the transfer material from being conveyed to the fixing device 25 in the above state. As a result, the above-mentioned image defect can be avoided.

  In this embodiment, the resistance detection of the electrical conduction path is exemplified as described above as a method of detecting the regulation state of the fixing belt and the pressure belt, but the present invention is not limited to this. For example, the design can be changed as appropriate, such as detecting the regulation state of the belt edge using an optical sensor or the like.

FIG. 3 is a cross-sectional view of the fixing device according to the first embodiment. 1 is a perspective view of a fixing device according to a first embodiment. The figure which looked at the pressure belt in a 1st embodiment from the upper part. The perspective view and side view of the fixing device in 2nd Embodiment. The perspective view of the fixing device in 3rd Embodiment. FIG. 10 is a perspective view of a fixing device according to a fourth embodiment. Sectional drawing of the fixing device in 5th Embodiment. 1 is a schematic sectional view of an image forming apparatus. The figure which shows the structure of the conventional fixing device. The figure which shows the structure of the conventional fixing device. The figure which shows the structure of the conventional fixing device.

Explanation of symbols

K: electrical contact portion, L: exposure, M: electrical contact portion, N: fixing nip, N0: transfer nip, P: transfer material, 1 ... fixing belt, 2 ... pressure belt, 2a ... pressure belt, 3 ... Pressure belt guide, 4 ... Fixing belt guide, 5 ... Ceramic heater, 6 ... Pressure member, 7 ... Regulation flange, 8 ... Pressure belt guide, 9 ... Fixing belt guide, 10 ... Regulation flange, 11 ... Fixing belt guide , 12 ... pressure belt guide, 14 ... regulating flange, 15 ... regulating flange, 21 ... fixing device, 22 ... fixing device, 23 ... fixing device, 24 ... fixing device, 25 ... fixing device, 50 ... image forming device, 51 ... photosensitive drum, 52 ... charger, 53 ... exposure device, 54 ... feed roller, 55 ... developer, 56 ... adsorption roller, 59 ... recording material conveying belt, 60 ... transfer roller, 62 ... drive roller, 64 ... Tension roller, 66 ... photosensitive drum cleaner, 70 ... developing cartridge

Claims (6)

An endless fixing belt having an outer peripheral surface facing an unfixed image carrying surface of a transfer material onto which an image has been transferred; and an endless pressure belt having an outer peripheral surface facing an unfixed surface of an unfixed image of the transfer material; A plurality of guide members for guiding belt running on the inner surfaces of the fixing belt and the pressure belt, and allowing the transfer material to pass through a contact area between the fixing belt and the pressure belt. In the fixing device for fixing the image on the transfer material by:
Provided outside the fixing nip region in the conveyance direction of the transfer material,
At least one of the guide member in the axial extension line is provided with a regulating member that regulates both end edges of the fixing belt and the pressure belt.   The fixing device according to claim 1, wherein the guide member and the regulating member are integrally formed.   The fixing device according to claim 1, wherein the regulating member also regulates an edge of the transfer material. Of the plurality of guide members that guide the fixing belt or the pressure belt, the axes of the two guide members that guide the same belt are non-parallel to each other,
The fixing device according to claim 1, wherein the regulating member is disposed at an end portion in a direction in which a distance between the two guide members that guide the same belt is narrow.   The fixing device according to claim 1, wherein the regulating member is swingable in the axial direction of the guide member and is pressed.   The fixing device according to claim 1, further comprising a detecting unit configured to detect that the fixing belt and the pressure belt are in a state of being regulated by the regulating member.

Images