JP2010176045A - Belt driving device, belt fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt driving device that prevents a belt from being broken and abnormal noises from occurring when preventing belt twist, and to provide a fixing device and image forming apparatus using the same. <P>SOLUTION: The belt driving device 25 includes: an endless belt 251; and a plurality of tension rollers 252 for stretching the endless belt 251, wherein at least one tension roller is rotated to make the endless belt 251 revolve. A stress for preventing the twist in a width direction of the endless belt 251 is applied in a region where the endless belt 251 is linearly conveyed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is applied to a belt driving device for fixing a toner image by heating using a fixing belt, a fixing device, and a copying machine, a facsimile, a printer using the same, and the like of an electrophotographic system for forming an image using toner. The present invention relates to an image forming apparatus.

A method of visualizing image information through an electrostatic latent image by using an image forming apparatus using an electrophotographic method or an electrostatic recording method is currently used in various fields. For example, in electrophotography, image information is formed into an electrostatic latent image on a photoreceptor by an exposure process subsequent to a charging process, visualized with a developer, and then passed through a transfer process and a fixing process. Is played.
In an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a printing machine, in the above-described fixing process, an unfixed image that is transferred and carried on a recording medium such as paper is fixed to copy or print output. There are things to do.
A fixing device used for fixing has a configuration in which a pair of rollers are arranged to face each other, one roller is used as a heating roller, and the other roller is used as a pressure roller for a recording medium to form a nip portion. Alternatively, there is a configuration in which a plurality of belts are similarly arranged opposite to form a nip portion. In this configuration, an unfixed image is fused and fixed while applying heat and pressure while the recording medium is nipped and conveyed in the nip portion between the heating roller and the pressure roller.

  Conventionally, in the above-described fixing device, securing the nip time for passing through the nip portion for heating the image has been an important issue. For example, when the rubber roller is pressed against the fixing roller, the rubber is soft and thick, and the rubber is deformed by strongly pressing the rubber roller and buckled toward the fixing roller, so-called nip width. Has been secured. However, even if the pressing pressure on the rubber is increased, there are limits to the softness and pressing pressure of the rubber. Further, when the rubber is softened, it becomes difficult to maintain the shape, and when the pressing pressure is increased, the rubber roller itself is deformed. For this reason, by using very soft foamed rubber (hereinafter referred to as “sponge rubber”) instead of rubber, a sufficient nip width can be secured even with an appropriate pressing pressure. However, sponge rubber has a short life, and repeated compression and release caused the rubber sponge to fatigue and brittle fracture of the sponge, making it difficult to maintain the initial performance.

On the other hand, recently, in order to secure a nip time, a fixing device using a combination of a fixing roller and an endless fixing belt, and a fixing device in which a plurality of belts are used to increase the nip time are proposed.
For example, in a fixing device in which a fixing roller and a fixing belt are combined, the nip time can be increased by winding the fixing belt around a circular arc of a cylindrical fixing roller.
Further, in the fixing device using a plurality of belts, the nip portion is formed by sandwiching the fixing belt, so that the nip time can be extended by lengthening the fixing belt. In this case, a plurality of thin belts are used, and each fixing belt moves to the left or right. As a solution to this problem, there is a method in which a stopper member is disposed at the end of the belt and the belt is forcibly pressed down. However, as a compensation for increasing the nip width by deforming the belt, the rotation of the belt is not a perfect circle, and when the belt end is pressed by a stop member, a force in a direction perpendicular to the belt circumference due to belt trajectory variation is generated. Addition causes the belt to be broken and a large abnormal noise to occur, and wear of the belt end due to friction with the stopper member occurs.

With respect to the above-described problems such as abnormal noise due to belt breakage and wear on the stop member, Patent Document 1 discloses a fixing member and a lubricant holding portion that holds the lubricant at one or both ends of the belt body. An endless belt, and a pressing member that is disposed inside the endless belt and presses the endless belt against the fixing member to form a contact portion between the fixing member and the endless belt, and A fixing device having a meander-preventing member that contacts the end face of the endless belt and prevents meandering of the endless belt is disclosed.
In Patent Document 2, 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 outer peripheral surface facing an uncarrying surface of an unfixed image of the transfer material. An endless pressure belt, and a plurality of guide members on the inner surface of each of the fixing belt and the pressure belt for guiding belt travel, in a contact region between the fixing belt and the pressure belt In the fixing device for fixing the image on the transfer material by passing the transfer material, provided outside the fixing nip region in the transport direction of the transfer material, at least one on the extension line in the axial direction of the guide member, A fixing device provided with a regulating member that regulates both end edges of the fixing belt and the pressure belt is disclosed.

JP 2008-185661 A JP 2007-240739 A

However, with the disclosed technique described above, it is difficult to prevent the belt from slipping and to suppress the breakage of the belt or the generation of abnormal noise.
Accordingly, the present invention has been made in view of the above-described problems, and the problem is that a belt driving device that suppresses belt breakage and abnormal noise in preventing belt slippage, a fixing device using the belt driving device, and image formation. Is to provide a device.
In addition, the belt is subject to breakage and noise due to the force applied in a direction perpendicular to the circumferential direction of the belt due to the fluctuation of the track, and the damage and noise caused by friction between the belt and the locking member such as a fixed stop member. And a fixing device and an image forming apparatus using the belt driving device.

The features of the present invention, which is a means for solving the above problems, are listed below.
The belt driving device of the present invention includes an endless belt and a plurality of stretching rollers that stretch the endless belt, and rotates the at least one stretching roller to rotate the endless belt as a driving roller. In the belt driving device, a stress is applied to prevent the endless belt from shifting in the width direction in a region where the endless belt is linearly conveyed.
The belt driving device of the present invention further includes two endless belts that come into contact with each other, and a nip portion formed in a region where the two endless belts are linearly conveyed. It is characterized by applying a stress to prevent the deviation in the width direction.
The belt drive device of the present invention further includes a detent member that applies pressure to prevent the endless belt from shifting in the width direction, and the detent member is movable in accordance with the movement of the endless belt. It is characterized by being.
The belt driving device of the present invention is further characterized in that a portion of the detent member that contacts the endless belt is formed of a softer resin or rubber than the belt base material.
Moreover, the belt drive device of the present invention is further characterized in that the detent member is driven.
Moreover, the belt drive device of the present invention is further characterized in that the stopper member is pressed by a pressing member.
Further, in the belt driving device according to the present invention, the stopper member has a roller shape.
Moreover, the belt drive device of the present invention is further characterized in that the stopper member has a belt shape.
The belt driving device according to the present invention is further characterized in that the detent member is a chain.

The fixing device of the present invention includes two endless belts that are stretched by a plurality of stretching rollers and rotated around the at least one stretching roller so that the two endless belts face each other. A fixing device for fixing a toner image formed on a recording member by heat and pressure at a nip portion to be formed is provided with any of the belt driving devices described above.
The image forming apparatus of the present invention includes an image carrier that forms a latent image, a charging device that uniformly charges the surface of the image carrier, an exposure device that exposes the surface of the charged image carrier and writes a latent image, and an image A developing device that supplies toner to the latent image formed on the surface of the carrier to visualize it, a cleaning device that cleans residual toner on the surface of the image carrier, and a visible image on the surface of the image carrier directly or intermediately. An image forming apparatus comprising: a transfer device that transfers to a recording medium after transferring to a body; and a fixing device that fixes a toner image on the recording medium.
A fixing device as described above is provided.

The present invention, which is a means for solving the above problems, has the following specific effects.
In the belt driving device of the present invention and the fixing device and image forming apparatus using the belt driving device, the belt may be damaged or generate abnormal noise due to a force applied in a direction perpendicular to the circumferential direction of the belt due to orbital fluctuations. It is possible to prevent the occurrence of damage and abnormal noise due to friction with the stopper member such as the stopper member.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 is an overall configuration diagram showing an image forming apparatus for carrying out the image forming method of the present invention. Here, a color image forming apparatus is shown as an example. This color image forming apparatus 1 is a tandem type electrophotographic apparatus using an intermediate transfer belt 11, a paper feed table 2 at the bottom, an image forming apparatus main body 1 above it, and a scanner 3 and a document at the top. An automatic feeding device (ADF) 4 is provided.
In the image forming method of the invention, an electrostatic latent image forming step, a developing step, a transfer step, a cleaning step, a fixing step, and the like are performed by the image forming apparatus 1 shown in FIG. The configuration of the image forming apparatus 1 for that purpose will be described in detail below.
The image forming apparatus main body 1 is provided with a transfer device 9 provided with an endless intermediate transfer belt 11 at substantially the center. The intermediate transfer belt 11 is stretched by a driving roller 14 and driven rollers 15 and 16 and is driven to rotate. Is done. To the left of the driven roller 15, residual toner remaining on the surface after image transfer is removed by a belt cleaning device (not shown) to prepare for the next image formation.
Photosensitive members 5Y, 5C, 5M, and 5K (hereinafter, colors are specified) along the moving direction above the linear intermediate transfer belt 11 that is stretched between the driving roller 14 and the driven roller 15. When it is not necessary, the photosensitive member 5 is simply provided), and a developing device 7, a charging device 6, and a photosensitive member cleaning device 8 are provided around it. The image forming unit 10 is formed using these as one unit. A developing process is performed by the developing device 7 of the image forming unit 10.
Further, the photosensitive member 5 is provided with a known exposure device 21 that irradiates laser light. The exposure device 21 performs an electrostatic latent image forming process.
Primary transfer rollers 9Y, 9C, 9M and 9K constituting the primary transfer means are provided. Image density detection means 29 are provided in the vicinity of the photoreceptor 5. Further, around the photosensitive member 5, a static elimination device and a lubricant coating device (not shown) are provided, respectively, which constitute one image forming unit 10.
On the other hand, a secondary transfer device 22 constituting secondary transfer means is provided below the intermediate transfer belt 11. The secondary transfer device 22 is in pressure contact with the driven roller 16 via the intermediate transfer belt 11. The secondary transfer device 22 collectively transfers the toner images on the intermediate transfer belt 11 onto the paper P as a recording medium fed between the secondary transfer device 22 and the intermediate transfer belt 11.
A fixing device 25 that heats and presses the toner image formed on the paper P to an endless fixing belt with a pressure roller is provided on the downstream side of the secondary transfer device 22 in the paper conveyance direction. The sheet P after the image transfer is transported to the fixing device 25 by an endless transport belt 24 that spans between the pair of rollers 23 and 23. The secondary transfer device 22 may be a transfer system using a transfer roller or a non-contact charger. A transfer process is performed by the transfer device 9 including the intermediate transfer belt 11.
A paper reversing device 28 for reversing the paper P when an image is formed on both the front and back sides of the paper is provided below the secondary transfer device 22.

When making a color copy with the color image forming apparatus 1 configured as described above, a document is usually set on the document table 30 of the automatic document feeder 4, but when a document is manually set, Then, the automatic document feeder 4 is opened, a document is set on the contact glass 32 of the scanner 3, and the document is pressed against the contact glass 32 by closing the automatic document feeder 4.
Next, when a start switch (not shown) is pressed, when the document is set on the automatic document feeder 4, the document is automatically fed onto the contact glass 32. When the document is manually set on the contact glass 32, the scanner is immediately scanned. 3 operates, and the first traveling body 33 and the second traveling body 34 start traveling. As a result, light from the light source of the first traveling body 33 is irradiated toward the original, and further, the direction is changed by 180 degrees by the pair of mirrors of the second traveling body 34 and enters the reading sensor 36 through the joint lens 35. The contents of the original are read.
When the start switch is pressed, the intermediate transfer belt 11 starts rotating, and at the same time, the photosensitive members 5Y, 5C, 5M, and 5K also start rotating, and yellow, cyan, magenta, Each black monochrome image is formed. Each single-color image formed on each photoconductor in this way is superimposed and sequentially transferred onto the intermediate transfer belt 11 that rotates in the clockwise direction in FIG. 1 to form a full-color composite color image.

On the other hand, the paper feed roller 42 of the selected paper feed stage in the paper feed table 2 rotates and the paper P is fed out from the selected paper feed tray 44 in the paper feed unit 43 and is separated into one sheet by the separation roller 45. It is separated and conveyed to the conveyance guide plate 48. The fed paper P is conveyed to the copying machine main body 1 by the conveying roller 47 and comes into contact with the registration roller 49 to be temporarily stopped. The registration roller 49 starts to rotate at an accurate timing in accordance with the color image on the intermediate transfer belt 11 and feeds the paper P that has been stopped between the intermediate transfer belt 11 and the secondary transfer roller 22. A color image is transferred on the secondary transfer device 22 above. The sheet P on which the color image has been transferred is conveyed to the fixing device 25 by the secondary transfer device 22 having a conveyance function, and the transferred image is fixed by being heated and pressurized. A fixing process is performed by the fixing device 25.
After that, it is guided to the discharge side, and is discharged onto the discharge tray 57 by the discharge roller 56 and stacked.
When the double-sided copy mode is selected, the paper P on which the image is formed on the front surface is conveyed to the paper reversing device 28 side, reversed and guided again to the secondary transfer position 22, and an image is formed on the back surface. After that, the paper is discharged onto the paper discharge tray by the discharge roller 56 and stacked. When a black single color image is formed on the intermediate transfer belt 11, the driven rollers 15 and 16 other than the driving roller 14 are moved to place the yellow, cyan, and magenta photoconductors 5 Y, 5 C, and 5 M on the intermediate transfer belt 11. It is trying to keep away from. In the so-called 1-drum type image forming apparatus 1 having only one photoconductor 5 instead of the tandem type shown in FIG. 1, black is first formed in order to increase the first copy speed. After that, the remaining colors are imaged only when the original is in color.

The belt driving device of the present invention includes an endless belt and a plurality of stretching rollers that stretch the endless belt, and rotates at least one stretching roller to rotate the endless belt. In the apparatus, in the region where the endless belt is linearly conveyed, stress is applied to prevent the endless belt from shifting in the width direction. This belt driving apparatus is an image forming apparatus and can be applied to an intermediate transfer belt driving apparatus and a belt fixing type fixing apparatus. Here, description will be made using a belt fixing type fixing device.
FIG. 2 is a schematic diagram showing a configuration of a fixing device using the baltic driving device of the present invention. FIG. 3 is a cross-sectional view of the fixing device.
As shown in FIGS. 1 and 2, an upper first belt 251a, which is an endless belt, and a second belt 251b, which are placed below, are arranged to face each other. These drive roller shafts are pressurized by a first drive roller 252a and a second drive roller 252b provided inside the first belt 251a and the second belt 251b, respectively. The first drive roller 252a and the second drive roller 252b are each driven at a constant speed from a drive source (not shown) via gears. As shown in FIG. 1, both ends of the first belt 251a and the second belt 251b are fixed by being abutted against the side plates 258a and 258b.
In addition, a first guide roller 253a and a second guide roller 253b are provided inside the first belt 251a and the second belt 251b, respectively, together with the first drive roller 252a and the second drive roller 252b, whereby a straight line is provided. A region L that is being conveyed is formed. Note that a guide for forming a linearly transported region (straight transport portion) L is sufficient, and a flat plate having a smooth and curved shape, not a roller, is provided inside the first belt 251a and the second belt 251b. It may be.

In the conventional thermal fixing method, in order to secure a nip time for heating the toner image, for example, when the rubber roller is pressed against the fixing roller, the rubber is softened and the rubber wall thickness is increased, and the rubber roller is pressed strongly. As a result, the rubber is deformed and buckled toward the fixing roller, thereby ensuring a contact width, so-called nip width. However, even if the rubber is soft and the pressing pressure is increased, there is a limit to the softness and pressing pressure of the rubber. If the rubber is too soft, it is difficult to maintain the shape, and if the pressing pressure is increased, the roller will vent.
For this reason, it has been considered to use sponge rubber instead of rubber, and it has become possible to secure a sufficient nip width by using a very soft sponge with an appropriate pressing pressure. However, the sponge had a short life, and the rubber sponge was fatigued by repeated compression and release, causing brittle fracture of the sponge, and it was difficult to maintain the initial performance.
In contrast, there are a method using a combination of a roller and a belt, and a method in which a plurality of belts are sandwiched to increase the nip time. However, in the combination of a roller and a belt, the nip time is earned by winding the belt around the roller arc.
The other is pinching by a plurality of belts, and the length of the nip due to close contact is arbitrary as long as the circumference of the belt allows. In this case, a plurality of thin belts are used, and each may move to the left or right.

  Therefore, in the fixing device 25 of the present invention, the stopper member 254 is disposed at the end of the fixing belts 251a and 251b, thereby forcibly pressing down the fixing belts 251a and 251b. However, the rotation of the fixing belts 251a and 251b is not a perfect circle as a compensation for increasing the linearly conveyed region L that is a nip region by deforming the fixing belts 251a and 251b. With such a fixing device 21, the end of the fixing belt 251a, 251b is pressed by the stopper member 254, and a force in a direction perpendicular to the circumferential direction is applied due to the orbital fluctuation of the fixing belt 251a, 251b. The destruction of the fixing belts 251a and 251b and the generation of a large abnormal noise are suppressed, and the wear of the ends of the fixing belts 251a and 251b due to friction with the stopper member 254 is prevented.

The stopper member of the present invention may be movable instead of fixed, and a pressing member can be provided on the back side, which is effective as a reaction force assist when the shifting force is very strong. In this case, the pressing member may be a fixed member, or may be a rotating member such as a roller or a belt.
Further, an auxiliary detent mechanism can be provided outside the linearly conveyed region of the fixing belt 251. The present invention is to apply a stopper member 254 to the linearly conveyed region L of the fixing belt 251 to prevent the fixing belt 251 from being broken or abnormal noise due to the orbital fluctuation of the fixing belt 251. Accordingly, in this case, if the contacting portion is narrowed and the limit value is taken, it can be considered as a straight line. Therefore, it is desirable to reduce the width contacting the end surface of the fixing belt 251 as much as possible in consideration of the influence of the track fluctuation. Specifically, a small-diameter roller, belt, chain, or the like can be used.
As the movable member, a roller, a belt, a chain, and the like are conceivable and can be appropriately selected according to the configuration and shape of the apparatus. In addition, all heat-resistant metals, resins, and rubbers can be used.
From the above, it is clear that the fixing device 25 according to the present invention is very useful. Further, in the case of a copying machine or printer using the fixing device of the present invention, it is possible to form an appropriate nip with a margin using the fixing belt 251, thereby increasing the size and cost of the roller for expanding the nip portion. It became possible to hold down. Further, since the load applied to the end portion of the fixing belt 251 is greatly reduced, the service life is remarkably increased as compared with the conventional belt system.

Example 1
The fixing device using the belt driving device of the present invention suppresses the destruction of the fixing belt 251 and the generation of a large abnormal noise even when a plurality of two belts are used, including the use of a single belt. In addition, wear of the end portion of the fixing belt 251 due to friction with the stopper member 254 is prevented.
FIG. 4 is a diagram showing a configuration of an embodiment of a fixing device using the belt driving device of the present invention. FIG. 5 is an enlarged view of the fixing belt and the stopper member.
In the fixing device using the belt driving device of the present invention, as shown in FIG. 4, an upper end first belt 251 a that is an endless belt and a second belt 251 b placed below are disposed to face each other. . These drive roller shafts are pressurized by a first drive roller 252a and a second drive roller 252b provided inside the first belt 251a and the second belt 251b, respectively. Inside the first belt 251a, a track in the circumferential direction of the first belt 251a is formed by the first guide roller 253a, the second guide roller 253a ′, and the third guide roller 253a ″. A region L that is linearly conveyed on the track is formed, and similarly, the first belt 251b has a first guide roller 253b, a second guide roller 253b ′, and a third guide roller 253b ″. A track in the circumferential direction of one belt 251b is formed. And the area | region L currently conveyed linearly in the track | orbit of this circulation direction is formed.
By applying stress to prevent the deviation of the fixing belt 251 in the linearly conveyed region L where the trajectory does not change even when the fixing belt 251 rotates, the fixing belt 251 rotates as shown by an arrow A in FIG. By traveling in the direction, it is possible to prevent a large shift force from being applied to the force in the direction perpendicular to the arrow B in the width direction, which is the direction in which the stopper member 254 is located, and to prevent destruction.
FIG. 5 shows the positional relationship between the stopper member 254 and the fixing belt 251, and the stopper member 254 serving as a stopper member that applies pressure to prevent the endless fixing belt 251 from shifting in the width direction. The stopper member 254 is movable according to the movement of the fixing belt 251. At this time, by making the stopper member 254 movable at the belt end in accordance with the movement of the fixing belt 251, it is possible to prevent the belt end from being broken due to friction and the generation of abnormal noise. If the surface of the stopper member 254 is made of a member softer than a belt base material such as resin or rubber, it is possible to significantly prevent the generation of sound compared to the case of contact between hard objects. Further, the friction can be further reduced by actively driving the stopper member 254.
By using such a fixing device 25, it was rotated for 50 hours, but almost no damage was observed. Regarding the sound, although it was not so unusual, a light rubbing sound was heard, but there was no problem in practical use. However, at the 60th hour, the end of the fixing belt 251 was cracked.

(Example 2)
FIG. 6 is a diagram showing a configuration of an embodiment of a fixing device using the belt driving device of the present invention. In the fixing device 25 using the belt driving device of the present invention, a region L that is linearly conveyed is formed at the nip portion formed by the two endless fixing belts 251a and 251b, and the region L stops. A member 254 is provided. As shown in FIG. 5, the stopper member 254 applies a stress that prevents the fixing belts 251a and 251b from shifting in the width direction. Applying stress to prevent the fixing belts 251a and 251b from shifting at the nip portion of the fixing belts 251a and 251b that is the linearly conveyed region L means that the shifting force of the fixing belts 251a and 251b is the fixing belt 251a and 251b. It is generated by the frictional force of the peripheral surface in the nip portion of the nip portion. Therefore, in the region L that is linearly conveyed, it is actually possible to suppress the deviation of the fixing belts 251a and 251b by the stopper member 254 in the nip portion. It was effective.
Although the fixing device 25 of Example 2 was rotated for 100 hours, the fixing belts 251a and 251b were hardly damaged. However, it was observed that the end of the fixing belt 251 was slightly worn.
Regarding the sound, although it was not an unusual noise, it was only enough to hear a light rubbing sound, and there was no problem in practical use. The nip portion is more effective than the nip portion because a shifting force is generated in the nip portion, and it is effective to push back in the vicinity of the stress generation point. On the other hand, when the stopper member 254 is simply installed at the end portion of the fixing belt 251 outside the linearly transported region, abnormal noise and damage at the end portion are observed in 10 hours. It became unusable.
FIG. 7 is a diagram showing a configuration of an embodiment of a fixing device using the belt driving device of the present invention.
As shown in FIG. 7, the guide rollers 253a ′ and 253a ″ of the first fixing belt 251a are omitted, and similarly, the guide rollers 253b ′ and 253b ″ of the first fixing belt 251a are omitted and the guide rollers 253a and 253b. As a result, even when the fixing belts 251a and 251b are in free tension, the stopper member 254 is provided at the nip portion in the region L where the fixing belts 251a and 251b are linearly conveyed. .

(Example 3)
FIG. 8 is a view showing a configuration of an embodiment of a fixing device using the belt driving device of the present invention, and is an enlarged view of a stopper member. As shown in FIG. 8, the stopper member 254 includes a stopper member belt 254c between the first guide 254d ′ and the second guide 254d ″, and the stopper member belt 254c is linearly connected. In the transported region L, the fixing belt 251 is pressed against the fixing belt 251 to apply a stress for preventing the fixing belt 251 from being displaced, so that the fixing belt 251 travels in the circumferential direction as indicated by an arrow A in FIG. Further, it is possible to prevent a large shift force from being applied to the force in the direction perpendicular to the arrow B in the width direction, which is the direction in which the stopper member belt 254c is located, and prevent the breakage.
FIG. 8 shows the positional relationship between the stopper member belt 254c and the fixing belt 251. The stopper member belt 254c that applies pressure to prevent the endless fixing belt 251 from shifting in the width direction is shown. Then, it is made movable according to the movement of the fixing belt 251. At this time, by making the stopper member 254 movable at the belt end in accordance with the movement of the fixing belt 251, it is possible to prevent the belt end from being broken due to friction and the generation of abnormal noise.
The stopper member belt 254c is made of a stainless film and has a thickness t = 0.1 mm. Thus, the belt was rotated for 200 hours, but the fixing belt 251 was hardly damaged. There was almost no wear at the end of the fixing belt 251. Regarding the sound, although it was not unusual, a light contact sound could be heard faintly, but there was no practical problem.
In addition, when this fixing device is used in a copying machine or a printer, it is possible to form an appropriate nip with a margin using a belt, and it is possible to suppress the enlargement of rollers and the cost increase to widen the nip width. It became. In addition, since the burden on the belt end portion is greatly reduced, the service life is also doubled compared to the conventional belt system.

Example 4
The stopper member 254 covered with 0.1 mm of silicone rubber was provided on the surface of the stopper member belt 254c shown in Example 3. Thus, the belt was rotated for 200 hours, but the fixing belt 251 was hardly damaged. There was no wear at the end of the fixing belt 251. Regarding the sound, no abnormal noise was generated.

(Example 5)
The stopper member 254 having the thickness t = 0.04 mm and the surface covered with 0.1 mm of silicon rubber was provided on the stainless member film of the stopper member belt 254c shown in Example 3. Although the buckling member belt 254c buckled and was not stable, the buckling was eliminated by attaching a pressing block to the center of the buckling member belt 254c from the back side, although not shown. Thus, the belt was rotated for 200 hours, but the fixing belt 251 was hardly damaged. There was no wear at the end of the fixing belt 251. Regarding the sound, no abnormal noise was generated.

(Example 6)
FIG. 9 is a view showing a configuration of an embodiment of a fixing device using the belt driving device of the present invention, and is an enlarged view of a stopper member.
Similar effects can be obtained by arranging mini rollers 255e ′ and 255e ″ in the nip portion of the linearly transported region L as shown in FIG. 6 instead of the stopper member belt 254c shown in FIG. Here, two mini-rollers 255e are shown, but three or more may be used, so that they were rotated for 200 hours but almost no damage was observed, and there was almost no wear on the belt end. Regarding the sound, although it was not unusual, a light contact sound could be heard faintly, but there was no practical problem.

(Example 7)
When a chain (not shown) is arranged in the nip portion of the linearly transported region L as shown in FIG. 6 instead of the stopper member belt 254c shown in FIG. 8, the same effect is obtained. It was. As a result, it was rotated for 200 hours, but almost no damage was observed. There was almost no wear at the belt end. Regarding the sound, although it was not unusual, a light contact sound could be heard faintly, but there was no practical problem.

(Example 8)
FIG. 10 is a diagram showing a configuration of an embodiment of a fixing device using the belt driving device of the present invention.
The fixing device 25 includes an endless first fixing belt 251a and a second fixing belt 251b that rotate in pressure contact with each other. In the fixing device 25, the fixing unit disposed above has an endless (endless) first fixing belt 251 a, a first driving roller 252 a, a first guide roller 253 a as a support member, and induction heating inside a casing. An assembly incorporating a coil 255 and the like. The first drive roller 252a (belt suspension member) has a function of suspending the fixing belt 251a and rotationally driving it. The first drive roller 252a is disposed with its left and right end shafts rotatably supported via bearings between the left and right side plates of the casing. The first guide roller 253a (support member) has a function of rotatably supporting the fixing belt 251a and controlling the position in the width direction thereof. The first guide roller 253a is disposed with its left and right end shafts rotatably supported via bearings between the left and right side plates of the casing. Further, the first guide roller 253a is configured such that its inclination (posture) can be changed by displacing the other end side around the one end side in the longitudinal direction. The first guide roller 253a also functions as a tension roller that applies tension to the first fixing belt 251a by urging the left and right bearings in a direction away from the first drive roller 252a by spring members.
The first fixing belt 251a is heated by electromagnetic induction by an induction heating coil heater 255a as a heating source. For example, a magnetic metal layer such as a nickel metal layer or a stainless steel layer having a thickness of 75 μm, a width of 380 mm, and a circumferential length of 200 mm is used as a belt base layer, and a silicon rubber layer having a thickness of 300 μm is coated on the outer surface. The induction heating coil 255 is a combination of a litz wire coil flattened in an oval shape and a plate-like magnetic core, and is opposed to the outer surface of the first fixing belt 251a with a gap therebetween. It is supported by the casing.
In the fixing device 25, the pressure unit disposed below includes an endless (endless) second fixing belt 251b, a second driving roller 252b, a second guide roller 253b as a support member, and the like inside the casing. It is an assembled assembly.
As described above, the fixing unit and the pressure unit are in a pressure-bonded state in the state of FIG. 10, and the first fixing belt 251a and the second fixing belt 251b form a linearly conveyed region L. A stop member 254 is provided at that portion.

Example 9
FIG. 11 is a diagram illustrating a configuration of an embodiment of a fixing device using the belt driving device of the present invention. The fixing device 25 includes a first fixing belt 251a that heats the toner image on the transfer paper, and a heat pipe that is disposed on the inner side of the first fixing belt 251a and reduces the temperature distribution difference in the longitudinal direction of the first fixing belt 251a. 255b.
Further, the fixing device 25 includes a second fixing belt 251b that pressurizes the transfer paper with the first fixing belt 251a. The first fixing belt 251a and the second fixing belt 251b are assembled so as to be able to be pressed / separated, and are linked and circulated in a pressed state when the transfer paper passes, but are separated while waiting for the transfer paper, It circulates individually. The heating unit of the fixing device 25 includes a coil unit 255a as a magnetic flux generating unit and a first fixing belt 251a as a heat generating member that generates heat by induction with magnetic flux from the coil unit 255a. Further, it has a first drive roller 252a and a first guide roller 253a as suspension members wound around the first fixing belt 251a and tensioning the first fixing belt 251a with a predetermined tension.
The coil unit 255a includes an exciting coil that generates a magnetic flux when energized, a magnetic core that collects the generated magnetic flux, an excitation coil, a holder that supports the magnetic core, and the like.
The first fixing belt 251a uses nickel having a thickness of 75 μm as a base layer, and an elastic layer having a thickness of 300 μm is provided on the outer periphery of the base layer. As the material of the elastic layer, silicon rubber is used, the hardness is JIS-A 20 degrees, and the thermal conductivity is 0.8 W / mK. At the exit of the nip between the first fixing belt 251a and the second fixing belt 251b, the elastic layer is deformed, so that the transfer paper is well separated from the belt and the transfer paper is prevented from being wrapped around the first fixing belt 251a. Has been. In addition to this, a known elastic material can be used as the material of the elastic layer. For example, fluororubber or the like can be used. On the outer periphery of the elastic layer, a fluororesin layer (for example, PFA or PTFE) is provided with a thickness of 30 μm as a surface release layer.
The second fixing belt 251b uses Ni having a thickness of 75 μm as a base layer, and an elastic layer having a thickness of 300 μm is provided on the outer periphery of the base layer. On the surface of the elastic layer of the second fixing belt 251b, a fluororesin layer (PFA) is provided with a thickness of 30 μm as a release layer.
The first guide roller 253a has a single heat pipe 255b inserted therein as a heat transfer means inside an iron hollow roller having an outer diameter of 20 mm, an inner diameter of 18 mm, and a thickness of 1 mm. The pipe material of the heat pipe 255b is copper, and a small amount of pure water is sealed inside as a heat medium.
The first drive roller 252a is rotationally driven by a drive mechanism (motor and drive gear train) (not shown). The first driving roller 252a is an elastic roller in which a silicon rubber layer as an elastic layer is provided on the surface of an iron-based alloy core bar having an outer diameter of 20 mm and an inner diameter of 18 mm. The silicon rubber layer has a hardness of JIS-A 15 degrees and a thermal conductivity of 0.8 W / mK. The silicon rubber layer reduces heat conduction to the core metal and has the effect of shortening the warm-up time. By providing the silicon rubber layer on the first driving roller 252a, a frictional transmission force is generated between the first driving roller 252a and the first fixing belt 251a following the rotation of the first driving roller 252a. Can be performed well.
Further, the second fixing belt 251b is pressed against the first fixing belt 251a to deform the flexible silicone rubber layer, thereby forming a nip outlet that ensures separation of the sheet from the first fixing belt 251a. The second fixing belt 251b is a ferrous alloy roller having an outer diameter of 23 mm and an inner diameter of 20 mm. The halogen heater 255c is disposed on the central axis and rotates outside the halogen heater 255c.
The second fixing belt 251b is stretched between a second drive roller 252b and a second guide roller 253b. The second guide roller 253b is made of an iron alloy having an outer diameter of 20 mm and an inner diameter of 16 mm.
Although not shown, the fixing device 25 is provided with a pressing mechanism that presses the fixing device 25 with a predetermined pressure. The second fixing belt 251b rotates and a straight line is formed between the first fixing belt 251a and the second fixing belt 251b. A region L to be conveyed is formed, and a stopper member 254 is provided in that region.

1 is an overall configuration diagram illustrating an image forming apparatus that performs an image forming method of the present invention, and here, a color image forming apparatus is shown as an example. FIG. 3 is a schematic diagram illustrating a configuration of a fixing device using the belt driving device of the present invention. It is sectional drawing of this fixing device. 1 is a diagram illustrating a configuration of an embodiment of a fixing device using a belt driving device of the present invention. It is a figure which expands and shows a fixing belt and a stopper member. 1 is a diagram illustrating a configuration of an embodiment of a fixing device using a belt driving device of the present invention. 1 is a diagram illustrating a configuration of an embodiment of a fixing device using a belt driving device of the present invention. It is a figure which shows the structure of one Embodiment of the fixing device using the belt drive device of this invention, and is a figure which expands and shows a stopper member. It is a figure which shows the structure of one Embodiment of the fixing device using the belt drive device of this invention, and is a figure which expands and shows a stopper member. 1 is a diagram illustrating a configuration of an embodiment of a fixing device using a belt driving device of the present invention. 1 is a diagram illustrating a configuration of an embodiment of a fixing device using a belt driving device of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper feed table 3 Scanner 4 Automatic document feeder (ADF)
5 Photoconductor 6 Charging device 7 Developing device 8 Cleaning device 9 Primary transfer device 10 Image forming unit 11 Intermediate transfer member 21 Exposure device 22 Secondary transfer device 24 Secondary transfer belt 25 Fixing device 251 Fixing belt 251a First belt 251b First Two belts 252a First drive roller 252b Second drive roller 253 Guide roller 253a, 253a ′, 253a ″ First belt guide roller 253b, 253b ′, 253b ″ Second belt guide roller 254 Stopping member 254a First stop Member 254b Second stop member 254c Stopper member belt 254d ′ First guide 254d ″ Second guide 255e, 255e ′, 255e ″ Mini roller 255 Heater 255a Coil heater 255b Heat pipe 255c Halogen heater 258a, 258b side 29 the image density detecting means 41 guide unit 42 the paper feed roller 43 side plate 44 the paper feed tray 45 separating portion 46 holding member 47 conveying rollers 48 conveying guide plate 49 registration rollers 50 rotating member 56 the discharge roller 57 discharge tray P Paper

Claims (11)

An endless belt,
A plurality of stretching rollers that stretch the endless belt;
In a belt driving device for rotating at least one tension roller and rotating the endless belt as a driving roller,
A belt driving device characterized by applying a stress to prevent the endless belt from shifting in the width direction in a region where the endless belt is linearly conveyed. In the belt drive device according to claim 1,
The belt driving device includes two endless belts that come into contact with each other, and a nip portion formed in a region where the two endless belts are linearly conveyed, and offsets the width of the endless belt. A belt driving device characterized by applying stress to prevent. In the belt drive device according to claim 1 or 2,
The belt driving device includes a detent member that applies pressure to prevent the endless belt from shifting in the width direction,
The belt drive device, wherein the detent member is movable according to the movement of the endless belt. In the belt drive unit according to any one of claims 1 to 3,
The belt driving device according to claim 1, wherein a portion of the stopper member that contacts the endless belt is formed of a softer resin or rubber than the belt base material. In the belt drive device according to any one of claims 1 to 4,
The belt drive device, wherein the detent member is driven. In the belt drive device according to any one of claims 1 to 5,
The belt drive device, wherein the stopper member is pressed by a pressing member. In the belt drive device according to any one of claims 1 to 6,
The belt driving device according to claim 1, wherein the stopper member has a roller shape. In the belt drive device according to any one of claims 1 to 6,
The belt drive device according to claim 1, wherein the stopper member has a belt shape. In the belt drive device according to any one of claims 1 to 6,
The belt stopping device, wherein the stopper member is a chain. Two endless belts that are stretched by a plurality of stretching rollers and rotated around the at least one stretching roller are provided opposite to each other,
In a fixing device for fixing a toner image formed on a recording member with heat and pressure at a nip formed by the two endless belts,
The fixing device includes the belt driving device according to claim 1. An image carrier for forming a latent image;
A charging device for uniformly charging the surface of the image carrier;
An exposure device that exposes a charged image carrier surface and writes a latent image; and
A developing device that supplies toner to the latent image formed on the surface of the image carrier to make a visible image;
A cleaning device for cleaning residual toner on the surface of the image carrier;
A transfer device for transferring a visible image on the surface of the image bearing member directly or onto an intermediate transfer member and then transferring it to a recording medium;
An image forming apparatus including a fixing device that fixes a toner image on a recording medium.
The image forming apparatus is a belt driving device according to any one of claims 1 to 9, or
An image forming apparatus comprising the fixing device according to claim 10.

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