JP3509212B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly, to an image forming unit of an endless belt directly or on a transfer material held at the image forming portion. The present invention relates to an improvement in an image forming apparatus of a type that transfers an image formed by.

[0002]

2. Description of the Related Art Conventionally, as a color image forming apparatus, for example, an image bearing member such as a photosensitive drum is rotated a plurality of times, and toner images of respective colors are superimposed on the image bearing member to form a color image. It is already known that a toner image of each color is collectively transferred onto a transfer material. In this type of color image forming apparatus, in order to simultaneously create the entire color image on the image carrier, the peripheral dimension of the image carrier is set to be equal to or longer than the maximum size of the transfer materials used. There is a need. For example, in the case of a JIS A3 size transfer material, since the length is 420 mm, the necessary diameter dimension φ on the image carrier is 133.7 mm or more.

In such a color image forming apparatus, since the toner images of the respective colors adhere to the image carrier during the color image forming process, a peeling claw is used to prevent the toner images of the respective colors from being destroyed. Is difficult.

Therefore, the transfer material is conveyed / transferred by using an endless transfer belt, and the transfer material is electrostatically attracted to the transfer belt to prevent the transfer material from being caught on the image carrier. Has already been proposed (for example, Japanese Patent Laid-Open No. Sho 4).
9-89537). As such a transfer belt, a dielectric belt having a dielectric constant of 2.0 to 4.0 (Japanese Patent Laid-Open No. 55-55
-18633) and electric resistance 10 ¹⁰ to 10 ¹⁵ Ω · c
m semiconductor rubber (Japanese Patent Laid-Open No. 63-83762) and the like are disclosed.

[0005]

When such a transfer belt is used, a so-called walk in which the transfer belt shifts in the axial direction due to dimensional accuracy of the transfer belt itself, misalignment of the stretched support roll, and the like. May occur. If a walk occurs, the edges of the transfer belt may fall off the transfer belt support rolls, or wrinkles or kinks may occur on the transfer belt, preventing the transfer material from sticking to the image carrier and causing uneven transfer. It leads to the cause.

As a method for preventing such a walk, a method of attaching a flange to the transfer belt and guiding the transfer belt in the guide groove (Japanese Patent Laid-Open No. 62-1 / 1987)
No. 65676, No. 62-235146, No. 63-27.
7147 JP) and a method (Japanese Utility Model 59-173059 Patent providing a flange to support the roll end of the transfer belt, JP 59-184379, JP-A 4-42277 Patent Publication No.
Report ), and a method of changing the diameter of the supporting roll in the axial direction (Japanese Patent Laid-Open No. 6-242242).
No. 3-301084, Japanese Utility Model 63-162744 Patent, real-Open No. 3-35949 JP) have been proposed.

However, although the method of attaching the flange to the transfer belt and guiding it with the guide groove and the method of providing the flange at the end of the roll have the effect of regulating the walk, the deviating force acting on the transfer belt should be finely adjusted. However, if the thickness of the transfer belt is thin, for example, wrinkles and kinks are generated in the transfer belt, and there is a technical problem that uneven transfer occurs.

Further, in the method of changing the diameter of the support roll, the deviation force acting on the transfer belt is substantially determined by the shape of the support roller formed in advance, and the deviation force cannot be finely adjusted. However, there is a technical problem that the walk of the transfer belt cannot be sufficiently regulated due to, for example, a molding error of the support roll.

Such a technical problem is not limited to the above-mentioned type, but for example, a plurality of image forming units are arranged along the transfer belt, and the toner image formed by each image forming unit is transferred to the transfer belt. The same applies to a so-called tandem type image forming apparatus that transfers directly or sequentially to a transfer material held on a transfer belt.

The present invention has been made in order to solve the above technical problems, and the deviating force acting on a belt can be finely adjusted with a simple structure, so that a so-called walk can be effectively prevented. An image forming apparatus having such high reliability is provided.

[0011]

That is, the present invention is
As shown in FIGS. 1A and 1B, a plurality of support rolls 2,
3 has an endless belt 1 which is stretched between 3 and circulates and rotates,
In the image forming apparatus for transferring the image formed by the image forming unit 4 directly to the image forming portion of the endless belt 1 or to the transfer material held at the image forming portion, a support roll for the endless belt 1 is provided. Of 2, 3 at least one of the driven rolls (for example, 2) is divided into a plurality in the axial direction, and the divided roll divided bodies 5 (for example, 5)
a, 5b, 5c) whose end position is fixed and which corresponds to at least one of the roll divisions 5, for example 5b
Endless shape corresponding to other roll divisions 5a, 5c in one part
Tension tension different from the belt 1 part given variable unit 6
Is provided.

In such technical means, at least one pair of support rolls 2 and 3 on which the endless belt 1 is stretched may be used, but three or more may be used depending on the length and layout of the endless belt 1. Of course. In the present invention, the image forming unit 4 includes, for example, a plurality of rotations of the image carrier to form a plurality of color toner images on the image carrier, and then the image carrier is held on the transfer material held by the endless belt 1. The toner images of the respective colors are collectively transferred, or individually provided for each of a plurality of color components, and the individually formed toner images are held directly on the endless belt 1 or on the belt 1. The target is the one that is sequentially transferred to the transfer material. Further, the structure of the roll divided body 5 may be at least one of the support rolls 2 and 3, but normally it is necessary to enable the roll divided body 5 to rotate independently and independently. , Support roll 2,
Of the three, the structure of the roll divided body 5 may be applied to the driven roll.

The number of divisions of the roll division body 5 may be appropriately selected as an odd number or an even number, but for example, due to the balance of the rotational load of the roll division body 5, the portion divided from the central portion of the endless belt 1 is shifted. When the biasing force of the belt 1 acts, the belt 1
It is necessary to forcibly regulate the leaning of people. On the other hand, from the viewpoint of effectively preventing the walk of the belt 1 without using an edge guide or the like, for example, when the number of divisions of the roll disassembling body 5 is 3, the support roll 2 is located at the center. It is preferable to set the rotational load of the roll divided body 5b to be larger than that of the other roll divided bodies 5a and 5b, and to set the rotational load of the support roll 2 symmetrically.

Further, the axial dimensions of the roll divided bodies 5 may be set to be the same or may be partially different. Furthermore, the gap size between the roll divided bodies 5 may be appropriately selected as long as the surface of the belt 1 is not recessed at a position corresponding to the gap (for example, 0.3 mm or less). Further, from the viewpoint of reducing damage to the belt 1 due to the end portion of the roll divided body 5, the surface of the roll divided body 5 may be formed of an elastic body,
It is preferable that the end portion of the roll divided body 5 has an R shape.

Further, regarding the tension varying means 6, each low
If the tension of the endless belt 1 portion corresponding to the roll division body 5 can be variably set, for example, a sliding member is slidably contacted to the roll division body 5 for which a large rotational load is to be set via a spring member or the like. Or roll division body 5
The diameter of the roll may be changed, or the frictional resistance of the surface portion of the roll division body 5 may be changed, or these may be appropriately combined and appropriately selected.
Particularly, from the viewpoint of more finely correcting the walk of the belt 1, for example, in the type in which the sliding member is slidably contacted with the roll divided body 5 by a spring member or the like,
Allow the fine adjustment of the pressing force of the spring member beforehand,
It is preferable that the rotational load of the roll divided body 5 can be finely adjusted.

[0016]

According to the technical means as described above, at least one (for example, 2) of the support rolls 2 and 3 of the endless belt 1 is divided into a plurality (for example, 3) in the axial direction and stretched.
For example, the force varying means 6 uses at least one (for example, 5b) of the divided roll divided bodies 5 to other roll divided bodies 5a,
And 5c and the different rotational load. At this time, if the rotational load of the roll split body 5b is set to be larger than that of the other roll divided body 5a, 5c, roll divided bodies 5b
The tension acting on the central portion of the endless belt 1 corresponding to is larger than that of the other portions, and the belt 1 is circulated and rotated while being pulled toward the higher tension, but a walk that is biased in one direction occurs. There is no.

Further, by finely adjusting the rotational load acting on the roll divided body 5 by the tension varying means 6, the magnitude of the tension acting on the endless belt 1 is finely adjusted. Accordingly, the walk correction of the belt 1 is performed more finely.

When the tension of a portion of the endless belt 1 which is deviated from the central portion thereof is larger than that of the other portion due to the balance of the rotational load of the roll divided body 5, the belt 1 walks in one direction. However, the walk is effectively restricted by the edge guide. At this time, if the tension distribution difference of the belt 1 is too large, since there is no possibility that deviation force acting on the belt 1 is extremely large, it wrinkles or kinks occur in the belt 1 effectively suppressed <br /> Yes.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the accompanying drawings. Example 1 FIG. 2 is a schematic diagram of Example 1 of a color image forming apparatus to which the present invention is applied. In the figure, reference numeral 10 is an image carrier such as a photosensitive drum, 20 is a charger for charging the image carrier 10, 30 is a laser light generator incorporating a semiconductor laser (not shown) and a polygon rotary mirror 31, The laser light 32 from the laser light generator 30 forms a latent image of each color component (in this embodiment, the laser light irradiation portion is an image portion).

Reference numerals 40a to 40d denote the image carrier 10.
There are four developing devices, for example, for yellow, magenta, cyan, and black, which develop the latent images of the respective color components formed with the corresponding color toners, and each developing device carries an image bearing charged by a charger 20. The image portion of the latent image is reversely developed with color toner having the same polarity charge as the surface potential polarity of the body 10. Then, the developing devices 40b to 40 in the second and subsequent stages
In order to prevent the toner image on the image carrier 10 developed by the previous developing process from being disturbed or the toner image on the image carrier 10 from being reversely transferred to the developing devices 40b to 40d side, for example, Japanese Unexamined Patent Publication No. It has been devised as described in No. 113474.

Further, reference numeral 50 is a transfer device for collectively transferring each color toner image on the image carrier 10 onto a transfer material 60. In this embodiment, a transfer belt 53 is provided between a pair of drive rolls 51 and driven rolls 52. And a transfer charger 54 disposed inside the transfer belt 53 facing the image carrier 10. And this transfer device 5
For example, 0 is configured to come into contact with or retract from the image carrier 10 by the eccentric cam mechanism 55. In this embodiment, at the timing when the toner image being formed passes through the transfer area before the transfer process. It is in a retracted state separated from the image carrier 10 and is 4 after the trailing edge of the third color toner image passes the transfer area.
By the time the leading edge of the color toner image reaches the transfer area, it abuts on the image carrier 10.

Further, reference numeral 70 is a cleaning device for removing the residual toner on the image carrier 10, 71 is a static eliminator for neutralizing the image carrier 10 before cleaning the residual toner, and 72 is a cleaning device for the image carrier 10. This is a charge-removing exposure device that performs charge-removing exposure later. The cleaning device 70 is configured to contact or retract with respect to the image carrier 10 by, for example, an eccentric cam mechanism 73. In this embodiment,
At the timing when the toner image during image formation passes through the cleaning area before the transfer process, the toner image is in the retracted state separated from the image carrier 10, and the trailing edge of the third-color toner image has passed the cleaning area and the fourth-color toner image has passed. The leading end of the sheet comes into contact with the image carrier 10 until it reaches the cleaning area.

Next, the image forming process of the color image forming apparatus according to this embodiment will be described. First, as the first image forming cycle, the image carrier 10 is charged by the charger 20, and the laser beam 32 from the laser beam generator 30 forms a latent image corresponding to a yellow at a predetermined position of the image carrier 10. The latent image is developed by the yellow developing device 40a.

Next, as the second image forming cycle,
The image carrier 10 is recharged by the charger 20, and the portion where the potential is lowered by the irradiation of the laser beam 32 in the previous step is restored to the original potential again. Then, the laser light generator 30
Image by the laser beam 32 corresponding to magenta from is irradiated again to a predetermined position of the image carrier 10, the laser beam irradiation unit is developed by magenta toner of the magenta developing device 40 b.

Thereafter, similarly, as the third image forming cycle, recharging by the charger 20, irradiation of a cyan image by the laser beam 32 from the laser beam generator 30, development of a cyan image by the cyan developing device 40c, 4 As the second image forming cycle, the steps of recharging by the charger 20, irradiation of the black image by the laser beam 32 from the laser beam generator 30, and development of the black image by the black developing device 40d are performed.

At the time when the black image developing process by the black developing device 40d is completed, four color toner images of yellow, magenta, cyan and black corresponding to the irradiation image are present on the image carrier 10. On the other hand, the transfer material 60 delivered from the paper guide 61 is electrostatically held by the transfer belt 53 of the transfer device 50 and advances to the transfer area.
At the time of passing through the transfer area, the yellow on the image carrier 10,
The toner images in which four colors of magenta, cyan, and black are superposed are collectively transferred onto the transfer material 60 by the transfer charger 54.

After the transfer step is completed, the transfer material 60 is separated from the transfer belt 53 and is conveyed to a fixing device (not shown) by the conveyor belt 62 to be subjected to the fixing step. Also,
After the transfer process is completed, the residual toner on the image carrier 10 is discharged by the static eliminator 71 and then cleaned by the cleaning device 70, and subsequently exposed by the static eliminator / exposure device 72, and the charging process by the charger 20 again starts. , All the above steps are repeated to output a plurality of continuous prints.

Next, the details of the transfer device 50 according to this embodiment are shown in FIG. 3, and the driven roll sectional view of the transfer device 50 is shown in FIG. In the figure, the drive roll 51 is rotationally driven by a drive system (not shown), and the transfer belt 53 laid between the drive roll 51 and the driven roll 52 is rotating in the direction of arrow A. In this embodiment, the driven roll 52 is divided into three (91, 92, 93) in the axial direction, and each of the roll divided bodies 91 to 93 has the same axial dimension and is a fixed shaft. Bearing 9 to 94
They are mounted independently of each other with an interval L therebetween via 5.

Further, in this embodiment, a rotating load varying device 100 is attached to the roll division body 92 located at the center. In this rotation load varying device 100, for example, a sliding member 101 made of elastic rubber having a predetermined friction coefficient is pressed and urged against a roll peripheral surface of a roll divided body 92 by a spring member 102 whose urging force is variably set. It is made to rub.

For this reason, the roll division body 9 located at the center
The rotation load of 2 is applied to the roll divided bodies 9 located on the other sides.
1 and 93, the tension of the transfer belt 53 region corresponding to the roll divided body 92 having a large rotational load is set to be larger than that of the other regions as shown in FIG. Become. At this time, the transfer belt 53 tries to move in the direction of higher tension, but since the tension of the central portion of the transfer belt 53 is high, the transfer belt 53 receives a force in the directions of arrows B and C while rotating. Therefore, even if the dimensional accuracy of the transfer belt 53, the alignment error of the driven roll 52, or the like, the so-called walk does not occur on the transfer belt 53.

Further, in this embodiment, as shown in FIG. 4, since the peripheral edges of the roll divided bodies 91 to 93 are formed in the R-shaped portion 96, the end portions of the roll divided bodies 91 to 93 are formed. Damage caused by rubbing against the transfer belt 53 can be suppressed to an extremely small amount, and the life of the transfer belt 53 can be extended accordingly.

Next, a modification of the first embodiment will be described with reference to FIG. In the figure, the driven roll 52 of the transfer device 50 according to the modified example is divided into two (91, 92) in the axial direction, and the rotation load varying device 100 is attached to one roll divided body 92. Has been done. Then, the edge guide 110 is mounted on the fixed shaft 94 and the bearing 111 in the vicinity of the end portion of the driven roll 52 located on the roll divided body 92 side.
It is provided through.

According to this modification, since the rotational load of the roll divided body 92 increases, the tension of the portion of the transfer belt 53 of the transfer device 50 corresponding to the roll divided body 92 increases. At this time, since the transfer belt 53 receives a force in the direction of arrow D while rotating, the transfer belt 53 tries to walk in the direction of arrow D, but the end portion of the transfer belt 53 has an edge guide 110. , And the walk of the transfer belt 53 is effectively regulated. Further, since the magnitude of the rotational load on the roll divided body 92 is easily and finely adjusted by finely adjusting the biasing force of the spring member 102 of the rotational load varying device 100, the transfer belt 5
The tension distribution acting on 3 can be easily fine-tuned. Therefore, the contact force of the transfer belt 53 with respect to the edge guide 110 is adjusted to be sufficiently small, and even if the transfer belt 53 comes into contact with the edge guide 110, the transfer belt 53 is not wrinkled or twisted.

Example 2 FIG. 7 is a cross sectional explanatory view showing a driven roll structure of a transfer device according to Example 2. In the figure, the driven roll 52 is
Similar to the first embodiment, three (91, 92,
93), each of the roll divisions 91 to 93 has the same axial dimension, and has a fixed shaft 94.
Are independently rotatably mounted via bearings 95. However, unlike the first embodiment, the diameter of the roll divided body 92 located at the center is different from that of the other roll divided bodies 9.
The radius dimension is Δr (0.2 in this embodiment) than 1,93.
mm) is set larger.

[0035] Therefore, according to this embodiment, since the diameter of the roll split body 92 is set larger than the other roll divided bodies 91 and 93, to roll divided body 92 of the transfer belt 53 of the transfer device 50 The tension of the corresponding portion is set to be higher than that of the other portions. Therefore, as in the first embodiment, the transfer belt 53 receives a force in the directions of the arrows B and C while rotating, and there are dimensional accuracy of the transfer belt 53, misalignment of the driven roll 52, and the like. Even
A so-called walk does not occur on the transfer belt 53.

Next, a modification of the second embodiment will be described with reference to FIG. In the second embodiment, a step due to a difference in diameter is formed between the roll divided body 92 and the other roll divided bodies 91 and 93, and when the step becomes large to some extent, the surface of the transfer belt 53 of the transfer device 50. There is a concern that a step may be formed in the portion and cause poor holding of the transfer material 60 (or poor transfer of the toner image). In order to avoid such a situation, in the modified example shown in FIG. 8, the peripheral surface shapes of the roll divided bodies 91 and 93 located on both sides of the roll divided body 92 located in the center are tapered with respect to the axial direction. A shaped surface (in this embodiment, means a shaped surface in which the roll diameter dimension gradually decreases toward the outside in the axial direction) 97, and the end of the roll divided body 92 and other roll divided bodies 91, 93 are formed. There is no step formed between the end and the end, and they are connected smoothly.

[Embodiment 3] FIG. 9 is a sectional explanatory view showing a driven roll structure of a transfer apparatus according to Embodiment 3. In the figure, the driven roll 52 is
Similar to the first and second embodiments, there are three (91, 9) in the axial direction.
2, 93) and each roll divided body 91 to 9
3 have the same axial size, and are independently rotatably mounted on a fixed shaft 94 via bearings 95. However, unlike Examples 1 and 2, the elastic coating layer 103 is provided on the surface of the roll division body 92 located at the center, and the roll division bodies 9 located on both sides are provided.
The surfaces of Nos. 1 and 93 are coated with elastic coating layers 104, respectively, but in this embodiment, the coefficient of friction of the elastic coating layers 103 is set to be larger than that of the elastic coating layers 104.

Therefore, according to this embodiment, the coefficient of friction of the roll divided body 92 is set to be larger than that of the other roll divided bodies 91 and 93, so that the transfer belt 53 of the transfer device 50.
The tension of the portion corresponding to the roll divided body 92 is set to be larger than that of the other portions. Therefore, as in the first embodiment, the transfer belt 53 receives a force in the directions of the arrows B and C while rotating, and there are dimensional accuracy of the transfer belt 53, misalignment of the driven roll 52, and the like. Even
A so-called walk does not occur on the transfer belt 53.

Example 4 FIG. 10 shows another mode of a color image forming apparatus to which the present invention is applied. In the figure, reference numerals 120a to 120d
Reference numeral 120 denotes an image forming unit for forming cyan, magenta, yellow, and black toner images in an electrophotographic process, and each image forming unit 120 is an image of a photosensitive drum or the like. Carrier 121
A charger 122 for charging the image carrier 121, a laser light generator 123 for writing an electrostatic latent image on the charged image carrier 121, and toners of cyan, magenta, yellow and black color systems. And a cleaning device 125 for removing the residual toner on the image carrier 121 are main components. Further, reference numeral 130 is a transfer device according to this embodiment, and the transfer device 130 is provided between a drive roll 131 and a driven roll 132 and is provided in each of the image forming units 120a-12.
The transfer belt 133 has a transfer belt 133 at a position facing 0d and corresponds to each of the image forming units 120a to 120d.
The transfer chargers 134 are provided inside the respective 33.
The driven roll 132 has a divided structure similar to that of the first embodiment, for example. Incidentally, reference numeral 141 is a supply device of the transfer material 140, 142 is a fixing device, and 143 is the transfer material 1.
40 discharge trays.

Therefore, according to this embodiment, the toner images formed on the image carriers 121 by the image forming units 120a to 120d are transferred to the transfer material 140 held on the transfer belt 133 by the transfer charger 134. Then, the transfer material 140 is peeled off from the transfer belt 133, passes through the fixing device 142, and then is discharged to the discharge tray 143.
Is discharged to. At this time, since the transfer belt 133 circulates and rotates without a walk as in the first embodiment, it is effective that the transfer position of each color toner image onto the transfer material 140 is shifted in the width direction of the transfer belt 133. Avoided.

[0041]

As described above, according to the present invention, among the supporting rolls for supporting the endless belt, at least one of the driven rolls has a divided structure in the axial direction, and the divided rolls are divided. The axial position of the body is fixed, and the belt portion corresponding to at least one of the roll divisions is given a different tension from the belt portion corresponding to the other roll divisions so that the axial tension distribution of the belt is made variable. Therefore, the biasing force acting on the belt can be finely adjusted with a simple configuration, so that the occurrence of the belt walk can be effectively avoided, and the reliability of image formation can be improved. In particular, if the tension in the center of the belt is set to a large value, it is possible to offset the bias force of the belt toward the center of the belt to cancel it, so that you can walk the belt without using an edge guide. Can be avoided.

Further, each roll division by the tension varying means
If the tension of the belt portion corresponding to can be finely adjusted, the tension distribution of the belt can be finely adjusted, so that the walk correction of the belt can be performed more finely.

[Brief description of drawings]

1A is a front explanatory view of an image forming apparatus according to the present invention, and FIG. 1B is a plan view thereof.

FIG. 2 is an explanatory diagram showing an outline of a first embodiment of a color image forming apparatus to which the invention is applied.

FIG. 3 is a plan view illustrating the transfer device according to the first embodiment.

FIG. 4 is a cross-sectional explanatory view showing a driven roll structure of the transfer device according to the first embodiment.

FIG. 5 is a graph showing the distribution of tension acting on the transfer belt of the transfer device according to the first embodiment.

FIG. 6 is an explanatory diagram showing a modified example of the driven roll structure of the transfer device according to the first embodiment.

FIG. 7 is a cross-sectional explanatory view showing a driven roll structure of the transfer device according to the second embodiment.

FIG. 8 is a cross-sectional explanatory view showing a modified example of the driven roll structure of the transfer device according to the second embodiment.

FIG. 9 is a cross-sectional explanatory view showing a driven roll structure of the transfer device according to the third embodiment.

FIG. 10 is an explanatory diagram showing an outline of a fourth embodiment of a color image forming apparatus to which the invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Endless belt, 2, 3 ... Support roll, 4 ... Image forming unit, 5 (5a, 5b, 5c) ... Roll division body, 6
... Tension changing means

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) B65H 5/02 G03G 13/14-13/16 G03G 15/14-15/16 G03G 21/00

Claims (2)

(57) [Claims] 1. An endless belt (1) which is stretched between a plurality of support rolls (2, 3) and circulates and rotates. The endless belt (1) is directly or at an image forming portion of the endless belt (1). In an image forming apparatus for transferring an image formed by an image forming unit (4) onto a transfer material held on a part, a supporting roll (2, 3) for the endless belt (1)
Of these, at least one of the driven rolls (2) is divided into a plurality in the axial direction, and the divided roll divided bodies (5: 5
a, 5b, the shaft position is fixed and the roll split body 5c) (5: 5a, 5b , at least one (5b) of 5c)
The corresponding endless belt (1) part is provided with a tension varying means (6) for giving a different tension from the endless belt (1) part corresponding to the other roll divided bodies (5a, 5c). Image forming apparatus. 2. A one of claim 1, wherein, the tension varying means (6) Zhang endless belt (1) part corresponding to the roll split body (5b) located in the center of the support roll (2)
A force other roles divided body (5a, 5c) endless corresponding to
An image forming apparatus characterized by being set to be larger than the belt (1) portion .