JP2010217457A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device that addresses image sift and belt deviation to the right and left due to generation of circumferential speed difference. <P>SOLUTION: In the fixing device, a belt 251a provided with a heater 255, a belt 251b which forms a nip section together with the belt 251a, a driving roller 252a disposed inside the belt 251a at the nip section A, and a driven roller 252b disposed inside the belt 251b, opposed to the driving roller 252a are arranged. A plurality of holes with regular intervals and arrays of the holes which are provided with regular intervals so that the holes of the belts 251a and 251b are overlapped at the nip section are formed at both the ends of the belts 251a and 251b. In the rollers 252a and 252b, convex portions 252a2 and 252b2 and concave portions 252a3 and 252b3 are alternately provided at positions corresponding to the holes of the belts 251a and 251b so that the convex portions of the driving roller and the concave portions of the driven roller and the concave portions of the driving roller and the convex portions of the driven roller are engaged when the driving roller is rotated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus that is applied to a copying machine, a facsimile, a printer, and the like and forms an image using toner, and more particularly to a toner image fixing apparatus that heats and fixes a toner image.

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.

In contrast, there is a method in which a plurality of belts are used to increase the nip time. This method is a method of sandwiching with a belt, and the length of the nip by contact is arbitrary as long as the circumference of the belt allows. However, there is slippage between the roller and the inner surface of the belt in driving the belt, and slipping between the opposite belts around the belt, especially when the image is nipped, the contact between the belts is lost and the slippage increases, and the fixing belt and the pressure belt There was a difference in peripheral speed between the opposing portions, causing a problem of image misalignment. In addition, since a plurality of thin belts are used and each of them moves to the left or right, an immediate solution has been desired.
Patent Document 1 proposes a technique for aligning a pair of belts by providing an alignment mechanism in a laminating apparatus. This is because the gears are engaged with the rollers facing each other, and the rollers and belts are also meshed with gears, etc., and if there is a difference in the circumferential length of the rollers, slipping is forcibly caused by the gear driving between the rollers. There was a bug that it was.
Patent Document 2 proposes a fixing device that is driven while a pin of a driving roller is fitted in a hole of a belt. In this fixing device, the driving of the belt is stable, but since the belt is one belt, the nip width is narrow, so that there is a limit to the image quality at the time of cardboard and high speed.
In Patent Document 3, a fixing device is proposed in which a pin of a heating roller is driven in engagement with a hole of a pressure belt. In this fixing device, the speed of the heating roller and the pressure belt is kept the same, but since the belt is one belt, the nip width is narrow, so that there is a limit to the image quality at the time of cardboard and high speed.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a fixing device that simultaneously solves image misalignment due to the occurrence of a peripheral speed difference and belt shift to the left and right.

That is, the above-described problems are solved by the following inventions 1 to 6.
1. An endless first belt having a heater therein, an endless second belt forming a nip portion with the first belt, and a rotatable drive roller disposed inside the first belt at the nip portion And a fixing device in which a rotatable driven roller that sandwiches and presses the first belt and the second belt is disposed inside the second belt so as to face the driving roller.
At both ends of the first belt and the second belt, a plurality of holes are equally spaced along the moving direction, and at the same interval so that the holes of the first belt and the second belt overlap at the nip portion. The provided row of holes is formed, and the driving roller and the driven roller are provided with convex portions and concave portions alternately at positions corresponding to the holes of the belt, and when the driving roller rotates, the driving roller and the driven roller are driven with the convex portion of the driving roller. The fixing device is characterized in that the concave portion of the roller is fitted, and the concave portion of the driving roller and the convex portion of the driven roller are fitted.
2. 2. The belt fixing device according to 1 above, wherein the first belt and the second belt are alternately provided with two types of holes having different sizes, and the first belt and the second belt are arranged so that holes having different diameters overlap each other. When the driving roller and the first belt are rotationally driven and the convex portion of the driving roller is inserted into the holes of the first belt and the second belt, the hole of the first belt contacting the driving roller is more than the hole of the second belt. Further, the fixing device is arranged to be larger.
3. In the belt fixing device according to 2 above, at least one of the hole rows at both ends of the first belt and the second belt is a hole row made of circular holes, and the unevenness portion of the driving roller and the driven roller The fixing device is characterized in that the concavo-convex portion is a circle having substantially the same diameter as the circular hole.
4). 4. The fixing device according to claim 3, wherein the hole row at least one end of the hole rows at both ends of the first belt and the second belt is a hole row made of oval holes. .
5). The fixing device is characterized in that the concave and convex portions of the driving roller and the concave and convex portions of the driven roller are formed of a resin or an elastic body, and the other portions are formed of metal.
6). 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 charged image carrier surface to write a latent image, and a latent image formed on the surface of the image carrier. A developing device for supplying toner to the image to make a visible image; a cleaning device for cleaning residual toner on the surface of the image carrier; and a visible image on the surface of the image carrier directly or after being transferred to an intermediate transfer member An image forming apparatus comprising a transfer device for transferring and a fixing device for fixing a toner image on a recording medium, wherein the fixing device is the belt fixing device according to any one of 1 to 5. An image forming apparatus.

According to the fixing device of the present invention, image misalignment due to belt swing prevention, wrinkling of the transfer paper, and jitter are prevented, and belt misalignment, belt wrinkling, belt cracking, and rubbing with the side plate against the belt end. Is prevented.
Further, when the fixing device of the present invention is mounted on an image forming apparatus, a good image can be obtained.

1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. 1 is a schematic perspective view illustrating an example of a fixing device of the present invention. 1 is a schematic cross-sectional view illustrating an example of a fixing device of the present invention. FIG. 2 is a partial cross-sectional schematic diagram illustrating an example of a fixing device of the present invention. FIG. 4 is a schematic perspective view and a side view of a belt according to the fixing device of the present invention. FIG. 4 is a schematic perspective view and a side view of a belt according to the fixing device of the present invention. FIG. 4 is a schematic perspective view and a side view of a belt according to the fixing device of the present invention. FIG. 4 is a schematic perspective view and a side view of a belt according to the fixing device of the present invention. FIG. 3 is a schematic perspective view of a driving roller according to the fixing device of the present invention. FIG. 2 is a partial cross-sectional schematic diagram illustrating an example of a fixing device of the present invention.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated based on drawing. 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 an embodiment 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 belt fixing device 25 that heats and presses a toner image formed on the paper P to an endless fixing belt with a pressure roller is provided downstream of the secondary transfer device 22 in the paper conveyance direction. The sheet P after the image transfer is transported to the belt fixing device 25 by an endless transport belt 24 spanned 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 this 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 belt fixing device 25 by the secondary transfer device 22 having a conveyance function, and the transferred image is fixed by being heated and pressurized. The belt fixing device 25 performs a fixing process.
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 fixing device of the present invention includes an endless first belt (hereinafter referred to as “first belt”) having a heater therein, and an endless second belt (hereinafter referred to as “first belt”) that forms a nip portion with the first belt. A "second belt"), a rotatable driving roller disposed inside the first belt at the nip portion, and a first belt and a second belt facing the driving roller inside the second belt. In the fixing device having a rotatable driven roller that sandwiches and presses, a plurality of holes are formed at equal intervals along the moving direction at both ends of the first belt and the second belt, and the first belt The hole and the hole of the second belt are provided at the same interval so as to overlap with each other at the nip portion, and the driving roller and the driven roller are provided with a convex portion and a concave portion alternately at a position corresponding to the hole of the belt. The drive low when Projections and fitted with the recess of the driven roller, and is a convex portion of the concave portion and the driven roller of the drive rollers are arranged to fit the.
FIG. 2 is a perspective view showing the entire belt fixing device. FIG. 3 is a cross-sectional view showing a front configuration of the belt fixing device of the present invention. FIG. 4 is a partially enlarged view of FIG.
As shown in FIGS. 2 and 3, an upper first belt 251 a, which is an endless belt, and a second belt 251 b placed below are arranged to face each other. A driving roller 252a and a driven roller 252b provided inside the first belt 251a and the second belt 251b respectively press the gap between the nip roller shafts by a pressing member such as a compression spring (not shown). The driving roller 252a and the driven roller 252b are driven at a constant speed from a driving source (not shown) through gears (not shown). The driving roller 252a and the driven roller 252b have a configuration in which rubber is wound around the outer periphery of a metal core.
Further, the first guide roller 253a and the second guide roller 253b, as well as the driving roller 252a and the driven roller 252b, are respectively provided in the first belt 251a and the second belt 251b. The nip portion A is provided upstream of the nip portion A, so that the first belt 251a located above and the second belt 251b located below are in contact with each other in the region where the sheet is linearly conveyed. It plays a guiding role for forming (A in FIG. 3). A space between these guide roller shafts is pressurized by a pressure member such as a compression spring (not shown).
The first guide roller 253a and the second guide roller 253b are also provided with an elastic body of soft rubber or rubber sponge on a metal core. Here, in the nip portion A, a certain nip pressure is obtained by the reaction force of the circular tubular belt returning to the circle.
Driving members such as both ends of the first belt 251a and the second belt 251b, the driving roller 252a and the driven roller 252b, and the first guide roller 253a and the second guide roller 253b, as shown in FIG. It is supported by a bearing provided on the rear side plate 258b and constitutes the fixing device driving section 26. In FIG. 2, 257 is a stopper plate and 259 is a stay.

The drive roller 252a has a first drive ring 252a1, a pin 252a2, and a hole 252a3, and the drive roller 252b has a second drive ring 252b1, a pin 252b2, and a hole 252b3. The pin 252a2 and the hole 252b3, and the pin 252b2 and the hole 252a3 are fitted through holes provided in the first belt 251a and the second belt 251b. In FIG. 4, the pin 252a2 and the hole 252b3 are fitted.
5, 6, 7 and 8 are a schematic perspective view and a side view showing the configuration of the belt. FIG. 9 is a perspective view of the drive roller and an enlarged view of the uneven portion of the drive roller.
As shown in FIGS. 5 (a), 6 (a), 7 (a), and 8 (a), a plurality of holes are provided at regular intervals at both ends in the longitudinal direction of the belt 251a. Is formed. A hole row 251a5 shown in FIG. 5B is formed by providing holes having the same diameter at both ends of the belt. A hole row 251a6 shown in FIG. 6B is obtained by alternately providing two types of circular holes having different diameters, and holes having the same diameter face each other. The hole row 251a7 shown in FIG. 7B is provided with two oval holes having the same major axis and different minor axes, but both the major axis and minor axis may be different. Here, the ellipse means a shape obtained by connecting two semicircles with a straight line. The hole row 251a8 shown in FIG. 8B is provided with a hole row similar to the hole row 251a6 shown in FIG. 6B at one end of the belt, and the hole row similar to the hole row 251a7 shown in FIG. 7B. Is provided at the other end of the belt. In this case, the diameter of the circle and the minor axis of the ellipse are the same.
The second belt 251b is also provided with a hole row similar to the hole row provided in the first belt 251a.

On the other hand, as shown in FIG. 9A, first drive rings 252a1 are attached to both ends in the axial direction of the drive roller 252a, and the first drive ring 252a1 is attached to the first drive ring 252a1 as shown in FIG. 9B. A plurality of pins 252a2 and a plurality of holes 252a3 are alternately provided. The center distance between the pin 252a2 and the hole 252a3 of the first drive ring 252a1 is the same as the center distance between the holes in the belt 251a. The driven roller 252b is similar to the drive roller 252a.
The hole diameter of the driven roller 252b and the hole diameter of the belt 251b are designed to be slightly larger than about 0.01 to 0.5 mm with respect to the pin diameter of the driving roller 252a, and the belt 251a has two driving roller pins. And 251b through holes provided in the driven roller. The same applies to the pin of the driven roller and the hole of the driving roller.
When the driving roller is rotated, the driving roller 252a, the first belt 251a, the second belt 251b, and the driven roller 252b are fed at a constant speed by feeding the pins of the driving roller and the driven roller inserted alternately into the hole of the belt. Move with.

In FIG. 4, at the moment when the pin 252b2 is about to be removed from the hole 252a4 of the first belt 251a, the pin and the belt may be rubbed or bitten. As a result, the belt hole may be cracked and damaged during long-term use.
Therefore, as shown in FIG. 6, the hole diameter of the belt is alternately changed, that is, a hole opened with a tolerance of, for example, +0.05 to +0.1 mm with respect to the pin diameter, and, for example, +0.2 with respect to the pin diameter. It is preferable to provide alternately about 0.5 mm. When such holes are provided in both the first belt 251a and the second belt 251b and the holes 251a9 and 251b9 of the two belts are assembled so that the small holes and the large holes face each other as shown in FIG. In FIG. 4, when the pin 252b2 is about to be removed from the hole 251a4, the pin biting into the belt hole is eliminated, and the problem of belt breakage with time is eliminated.
Furthermore, as shown in FIG. 7, the holes are oblong, the holes having the same long diameter and different short diameters are alternately provided, and the small and large holes of the first belt 251a and the second belt 251b are opposed to each other. As a result, the displacement in the longitudinal direction can be eliminated at the same time, which is more effective. Further, as shown in FIG. 8, the hole row at one end is a round hole and the row at one end is a long hole, so that it is possible to prevent the belt from shifting in addition to the displacement in the longitudinal direction, which is more effective.

The first guide roller 253a and the second guide roller 253b serve as guides for the first belt 251a and the second belt 251b to form a large nip portion A (FIG. 3). Here, in the nip portion A, the nip pressure is obtained by the reaction force of the circular belts 251a and 251b returning to the circle.
As shown in FIG. 3, the halogen heater 255 and the reflection plate 256 are also provided in the belt, and by centrally heating the upper part of the first belt 251a from the inside, the space for the heat to escape becomes very small, and the first belt The temperature rising efficiency of 251a is improved.

The first guide 254a is configured to regulate most of the inner surface of the belt other than the nip portion A in the circumferential direction of the first belt 251a (the same applies to the second guide 254b and the second belt 251b). ). In the longitudinal direction of the first belt 251a, first guides 254a are provided only at both end portions, that is, non-image portions, so that sliding resistance and heat capacity are minimized. The first guide 254a prevents shaking when the belt is driven. The first belt 251a and the first belt 251b are driven by the first drive ring 252a1 and the second drive ring 252b1 formed at both ends of the drive roller 252a and both ends of the driven roller 252b so as not to deviate from the respective rollers. The deviation between the opposed first belt 251a and second belt 241b is restricted. Then, the paper on which the toner image is transferred by a conventionally known electrophotographic process is conveyed from the direction B in the drawing, heated and pressurized by the nip portion A, and the toner image is fixed on the paper.
The belt swing will be described. When the belt is driven, it receives a force in the C direction in FIG. 3 due to the inertial force of the substantially linear nip portion at the nip portion outlet, and the entire belt tries to move in the C direction except for the nip portion A. However, when the belt is deformed to some extent, the force to return to the stationary state becomes strong, and the vibrations are generated by both of these forces. By providing the first belt 251a and the first belt 251b, this shaking can be suppressed.

In order to have both driving and speed regulation accuracy at the same time, the base of the pin is vertically rising, and the height of the pin is the same height as the combined thickness of the first belt 251a and the second belt 251b. It is preferable that it is ± (height of one belt) with respect to this height. More preferably, the shape of the pin and hole forms a relaxation curve.
As described above, the present invention controls the speed of the first belt, the second belt, and the driven roller and regulates the speed, so that when the recording medium passes through the nip portion, the speed difference between the image surface and the fixing surface is prevented. This is a technology that suppresses the occurrence of a belt to a level that does not cause a problem and also suppresses the occurrence of a belt shift.
The driving roller and the driven roller used in the present invention can be produced by a method in which a pin provided on a driving ring or a holed hole is inserted into the roller. This method facilitates drilling and pinning, and can particularly increase the accuracy of drilling. Further, the roller is a relatively heavy material, and it is preferable to process it separately in terms of cost in consideration of handling for processing this and troubles such as prevention of scratches on the surface processing of the roller. When fitting into the roller, a notch such as D-cut may be made in the roller or ring, or fine adjustment may be made and fixed with a set screw or the like. From the viewpoint of reducing the number of parts, it may be manufactured integrally.

Example 1
Configuration 1
Belt support thickness 40μm
Belt elastic layer 200μm
Belt surface layer 30μm
Fixing belt diameter 60mm
Pressure belt diameter 60mm
Drive roller diameter 20mm
Followed roller diameter 20mm
Guide roller diameter 12mm
Number of convex pins at the drive roller end 6 Number of concave holes at the drive roller end 6 Number of convex pins at the driven roller end 6 Number of concave pins at the driven roller end 6 Convex pin diameter 2.5 mm
Concave hole diameter 2.5mm
Belt hole diameter 2.5mm
Pin rise vertical part 500μm
Pin length 1mm
Hole depth 1mm
After pin vertical part Relaxation curve (involute approximation)
Pins and holes are arranged at both ends of the roller, the holes are round holes, and the side walls are formed in approximate involute.
Driving force between driven roller and driven roller 5-9kg
Pressure between guide roller and roller shaft 1-4kg

As a result of the experiment with the above configuration 1, no problems such as image misalignment were detected.
In this configuration 1, the belt hole spacing must match the pin spacing, the pins should correspond to the positions where the roller circumference is evenly divided, and the belt holes should be in the uniform position over the entire belt circumference. If there is an unequal portion, in Example 1, the roller outer peripheral length is 62.8 mm, and 1/12 of the peripheral length is 5.23 mm. Since the outer peripheral length of the belt was 188.4 mm, there was no contradiction regarding the arrangement of the split holes at 5.23 mm.
Further, it is convenient if the convex pin concave holes are −tolerance or + tolerance, respectively, and there is no occurrence of biting due to appropriate play. If it is a reverse tolerance, it is naturally possible that the bite or pin does not enter the hole. However, this is not the essence of the present invention, but a common-sense design adjustment item, and there is no particular problem unless so-called common sense is removed. Of course, this is also true for the belt hole, and it is a tolerance because it is a hole.
Also, if the same period overlap is considered as a problem for the rollers, the number of belt holes is set to an odd number for the even number of roller pins and vice versa to prevent problems due to the coincidence of the periods. It becomes possible. Furthermore, the length of the pin, the depth and the diameter of the hole, etc. are also design matters within the common sense.

(Example 2)
In the configuration 1, an experiment was performed in the same manner as in Example 1 except that the fixing belt diameter and the pressure belt diameter were set to 40 mm. As a result, no image misalignment or belt misalignment occurred.
Example 3
In the configuration 1, an experiment was performed in the same manner as in Example 1 except that the concave hole and the belt hole were made to have a long circular diameter (long diameter 3.5 mm, short diameter 2.5 mm). (± 0.4 mm).
Example 4
In the configuration 1, an experiment was performed in the same manner as in Example 1 except that the number of pins was increased to 12 and the division was made fine. As a result, finer jitter was not observed.

(Comparative example)
In the configuration 1, when the experiment was performed in the same manner as in Example 1 except that the pin and the hole were provided on one side instead of both ends, the frequency of wrinkling of the belt increased and the stress applied to the hole increased. It became easier to crack.
(Comparative Example 2)
When the experiment was performed in the same manner as in Example 1 except that the pin and the hole were not provided in the configuration 1, the image was greatly displaced and the side plate was rubbed against the side plate.

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 Belt fixing device 251a First belt 251a5, 251a6, 251a7, 251a8 hole row 251a4, 251a9 hole 251b second belt 251b4, 251b9 hole 252a driving roller 252a1 first driving ring 252a2 pin 252a3 hole 252b driven roller 252b1 second driving ring 252b3 pin 2 Roller 254a First guide 254b Second guide 255 Heater 256 Reflector plate 258a Front side plate 258b Rear side plate 259 Stay 26 Belt fixing device drive unit 41 Guide unit 42 Paper feed low La 43 Side plate 44 Paper feed tray 45 Separating section 46 Holding member 47 Conveying roller 48 Conveying guide plate 49 Registration roller 50 Rotating member 56 Discharge roller 57 Discharge tray A Nip section B Force direction C Recording paper conveyance direction

Japanese Patent Laid-Open No. 2006-7693 JP-A-4-305675 Japanese Patent No. 3128100

Claims (6)

An endless first belt having a heater therein, an endless second belt forming a nip portion with the first belt,
A rotatable drive roller disposed inside the first belt at the nip portion;
A fixing device in which a rotatable driven roller that sandwiches and presses the first belt and the second belt is disposed inside the second belt so as to face the driving roller.
At both ends of the first belt and the second belt, a plurality of holes are equally spaced along the moving direction, and at the same interval so that the holes of the first belt and the second belt overlap at the nip portion. The hole array provided is formed,
The driving roller and the driven roller are provided with convex portions and concave portions alternately at positions corresponding to the holes of the belt, and when the driving roller rotates, the convex portions of the driving roller and the concave portions of the driven roller are fitted, The fixing device is characterized in that the concave portion of the driving roller and the convex portion of the driven roller are fitted to each other. The belt fixing device according to claim 1.
Two kinds of holes having different sizes are provided alternately in the first belt and the second belt, and the first belt and the second belt are arranged so that holes having different diameters overlap each other.
When the driving roller and the first belt are rotationally driven and the convex portions of the driving roller are inserted into the holes of the first belt and the second belt, the hole of the first belt contacting the driving roller is larger than the hole of the second belt. A fixing device characterized by being arranged as follows. The belt fixing device according to claim 2,
The hole row at least one end of the hole rows at both ends of the first belt and the second belt is a hole row made of circular holes, and the uneven portion of the driving roller and the uneven portion of the driven roller are the holes of the circular diameter. A fixing device characterized by a circular shape having substantially the same diameter. The belt fixing device according to claim 3.
The fixing device, wherein the hole row at least one end of the hole rows at both ends of the first belt and the second belt is a hole row made of oval holes. A fixing device, wherein the concave and convex portions of the driving roller and the concave and convex portions of the driven roller are formed of a resin or an elastic body, and the other portions are formed of metal. 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, wherein the fixing device is a belt fixing device according to any one of claims 1 to 5.

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