JP2002193471A - Sheet carrying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the slippage and meandering of an endless belt and the deterioration and breakage of the endless belt. SOLUTION: A prescribed driven roller 9b having belt slippage regulating members 18a and 18b is arranged so that the winding angle of the endless belt 9a of the driven roller 9b is the largest of the rollers of a belt driving means 100B, and a tension roller 9e is arranged on the moving directional upstream side of the endless belt 9a of the driven roller 9b so that the winding angle of the endless belt 9a is the smallest of the rollers of the belt driving means 100B. When the endless belt 9a slips and meanders, and a belt slippage regulating guide 19a is about to run over the belt slippage regulating members 18a and 18b, the tension roller 9e is tilted to cancel the slippage and meandering of the endless belt 9a.

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, and more particularly, to driving an endless belt that conveys a sheet to an image forming section, while suppressing a deviation in a belt width direction and uniformly applying a belt tension. Related to the configuration of the force.

[0002]

2. Description of the Related Art A conventional image forming apparatus employs an electrophotographic method or an electrostatic recording method as an image forming process for forming an image. Such an image forming apparatus has a cylindrical shape as an image carrier. A photosensitive drum is used, and peripheral devices such as a charger, an exposure unit, a developing unit, and a cleaning unit, a recording material transport mechanism (recording material transport unit), and the like are arranged around the photosensitive drum. Well known.

In recent years, in order to further improve the functions of a photosensitive drum, a recording material conveying mechanism, and the like, an endless belt, which is an endless belt using a photosensitive member instead of a photosensitive drum, has been used. An image forming apparatus employing an endless belt as a material transport mechanism has been developed.

In an image forming apparatus employing such an endless belt, many functions can be improved, but, on the other hand, the endless belt may be shifted or meandered relative to a reference trajectory during driving. Means for suppressing the occurrence are indispensable.

[0005] Here, the cause of the positional deviation due to the one-sided movement of the endless belt includes torsion between members on which the endless belt is stretched. However, there is a limit in increasing the accuracy of such torsion. Further, if the accuracy is further improved, the cost of the apparatus itself may be increased.

In order to correct the deviation or meandering of the endless belt, a belt deviation regulating guide 119a provided at both ends of the inner peripheral surface of the endless belt 109a as shown in FIG. In some cases, the endless belt 109a is arranged so as to be brought into contact with belt deviation regulating members 118a and 118b provided at side ends of a driven roller 109b on which an endless belt 109a is stretched.

The endless belt 10
When the endless belt 109a rotates, the deviation of the endless belt 109a is regulated by contacting the belt deviation regulating guides 119a and 119b of 9a with the belt deviation regulating members 118a and 118b of the driven roller 9b. It should be noted that the belt shift regulating member 119
a and 119b are bonded to both ends of the inner peripheral surface of the endless belt 109a by bonding and sewing.

[0008]

However, in an image forming apparatus having such a configuration, for example, as shown in FIG. 9, winding of an endless belt 109a around a driven roller 109b for restricting deviation during belt running. When the angle is small, the guides 119a, 11
9b and the area where the belt shift regulating members 118a and 118b contact each other is reduced.

Further, as shown in FIG. 1, a driven roller 109 provided with belt shift regulating members 118a and 118b.
the tension roller 109 on the upstream side in the transport direction adjacent to
e, instead of the tension roller, if a fixed roller other than the tension roller is disposed, the belt deviation regulating members 118a and 118b are controlled by the belt deviation regulating members 118a and 118b in the vicinity of the driven roller 109b that regulates the deviation. Since the contact area between the endless belt 109a and the roller other than the area where the endless belt 109a is in contact with the guides 119a and 119b is increased, a greater force is required when regulating the bias of the endless belt 109a.

As a result, the belt deviation regulating guide 119 is provided.
a, 119b and belt deviation regulating members 118a, 118b
Between the endless belt 109a
There is a problem that the durability near the joining surface of the belt deviation regulating guides 119a and 119b, the belt deviation regulating members 118a and 118b, and the belt deviation regulating guides 119a and 119b suddenly decreases.

When the tension of the endless belt 109a is increased, or when the rigidity of the endless belt 109a is high, the generated deviation force is also increased, so that the belt deviation regulating guides 119a and 119b are used by the belt deviation regulating members 118a and 119b. It ’s easier to get over 118b,
As a result, running of the endless belt 109a becomes unstable.

In addition, the belt circumference changes due to the contraction and expansion of the belt due to the temperature rise in the machine, and the belt tension changes in the environment. Deviation occurs.

Accordingly, the present invention has been made in view of such a situation, and provides an image forming apparatus capable of preventing the endless belt from shifting or meandering and preventing the endless belt from being deteriorated or damaged. The purpose is to do so.

[0014]

According to the present invention, there is provided an endless belt for conveying a sheet to an image forming section, a driving roller for driving the endless belt, a plurality of driven rollers, and a tension roller for urging the endless belt. An endless belt formed at a side end of an inner peripheral surface of the endless belt.
Two belt deviation regulating guides, provided at the side ends of the predetermined driven roller, and during rotation of the endless belt,
At least one belt shift restricting member that abuts the belt shift restricting guide to prevent the endless belt from shifting in the width direction, and a predetermined driven roller provided with the belt shift restricting member, The winding angle of the endless belt of the driven roller is arranged to be the largest among the rollers of the belt driving means, and the tension roller is located on the upstream side in the moving direction of the endless belt of the driven roller, and The winding angle of the endless belt is set to be the smallest among the rollers of the belt driving means.

Further, in the present invention, the belt biasing direction of the tension roller may be a bisector of a bending angle of the endless belt formed by a tangent to a roller of the belt driving means adjacent to the tension roller. On the other hand, it is a direction inclined toward the upstream side in the endless belt conveyance direction.

Further, the present invention provides the tension roller,
The two ends of the tension roller are independently held by arm type holding members.

Further, the present invention is characterized in that a cutout portion having an inclined surface is formed on a surface of the belt deviation regulating member which contacts the belt deviation regulating guide.

[0018] The present invention also relates to a method of manufacturing the endless belt,
The distance between the driven roller provided with the belt deviation regulating member and the tension roller is set according to the circumference.

The present invention also provides an endless belt for conveying a sheet, and a belt driving means for driving the endless belt while stretching the endless belt with a driving roller, a plurality of driven rollers, and a tension roller for urging the endless belt. And a belt shift regulating guide formed at both ends of the inner peripheral surface of the endless belt so as to protrude in the circumferential direction, and a predetermined driven roller of the plurality of driven rollers. A belt deviation regulating member provided on both side ends of the roller and abutting on the belt deviation regulating guide during rotation of the endless belt to prevent lateral deviation of the endless belt. A roller is disposed on the upstream side in the moving direction of the endless belt of a predetermined driven roller provided with the belt deviation regulating member, and the belt deviation regulating guide is And supporting means for supporting the tension roller such that the direction of the rotation axis of the tension roller is inclined with respect to the direction of the rotation axis of the predetermined driven roller when riding on the deviation regulating member. .

Further, as in the present invention, the endless belt for conveying the sheet to the image forming section is stretched by belt driving means having a driving roller, a plurality of driven rollers and a tension roller for urging the endless belt. On the other hand, at least one belt deviation regulating guide is formed at a side end of the inner peripheral surface of the endless belt, and both ends of the endless belt come into contact with the belt deviation regulating guide during rotation of the endless belt. A belt shift regulating member is provided to prevent the endless belt from shifting in the width direction.

Further, a predetermined driven roller provided with a belt deviation regulating member is arranged such that the winding angle of the endless belt of the driven roller is the largest among the rollers of the belt driving means, and the tension roller is provided. By arranging the driven roller on the upstream side in the moving direction of the endless belt and in such a manner that the winding angle of the endless belt is the smallest among the rollers of the belt driving means, the endless belt may be shifted or meandering. When the belt deviation regulating guide tries to get over the belt deviation regulating member, the tension roller is inclined to cancel the deviation and meandering of the endless belt.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a color laser beam printer as an example of the image forming apparatus according to the first embodiment of the present invention.

In FIG. 1, reference numeral 100 denotes a color laser beam printer (hereinafter, referred to as a printer). The printer 100 includes four photosensitive drums 1a, 1b, 1c, 1
d, an image forming unit 100A having four scanner units 3a, 3b, 3c, 3d and the like constituted by a rotating polygon mirror and a reflecting mirror.

In the image forming section 100A, four photosensitive drums 1a, 1b, 1c, 1d whose surfaces are uniformly charged by charging rollers 2a, 2b, 2c, 2d are provided with scanner units 3a, 3b, 3c. , And 3d, a latent image is formed on the surface of the photosensitive drum by irradiating light corresponding to the image information.
Developing sleeves 4a, 4b provided on 7b, 7c, 7d
b, 4c, 4d to develop yellow,
A visible image of each color of cyan, magenta and black is formed on the photosensitive drum.

Note that 12a, 12b, 12c, 12d
Reference numeral denotes a transfer roller which presses the photosensitive drums 1a, 1b, 1c and 1d via an endless belt 9a which is an endless belt to be described later to form a transfer portion. 6a, 6
b, 6c and 6d are cleaning means.

On the other hand, in FIG. 1, reference numeral 13 denotes a paper feed cassette for storing a recording material P which is a sheet. The recording paper P stored in the paper feed cassette 13 is fed out by a paper feed roller 18 and then retarded. The sheet is conveyed after being separated into one sheet by the roller pair 16. Reference numeral 14 denotes a manual paper feed unit, and the recording paper manually fed from the manual paper feed unit 14 is conveyed by conveyance rollers 19.

Reference numeral 9a denotes an endless belt which is an endless belt for conveying the recording material P to each transfer section. The recording paper P conveyed from the paper feed cassette 13 or the manual paper feed section 14 is an endless belt. After being placed on 9a
They are sequentially conveyed to each transfer section.

In this embodiment, the endless belt 9a is formed of a film-like member having a volume resistivity of, for example, 10 ¹² Ωcm or less and a thickness of about 150 μm. Here, this volume resistivity was measured using an ADVAN using a measurement probe conforming to JIS method K6911.
This is a value obtained by applying 100 V with a high resistance meter R8340 manufactured by TEST.

Incidentally, this endless belt 9a is
As shown in the drawing, a driving roller 9c, a belt-side regulating driven roller 9b (hereinafter referred to as a regulating roller) provided upstream of the driving roller 9c, a driven roller 9d provided downstream of the driving roller 9c, and a tension roller. 9e is driven while being stretched by the belt driving means 100B provided with the belt driving means 9e and rotates in the direction of the arrow (counterclockwise).

Incidentally, these rollers 9b, 9c, 9d,
9e is a belt drive means 100
B is rotatably held by a bearing provided on a body frame (not shown) of FIG.

Here, the driving roller 9c is formed of a metal roller having a rubber layer having a large friction coefficient on the surface layer and has a diameter of about 30 mm, and is driven at a predetermined speed in a direction indicated by an arrow in FIG. It is designed to be driven to rotate. The driven roller 9d is formed of a metal roller such as SUS, for example, and the bearings at both ends are fixed at predetermined positions.

On the other hand, as shown in FIG. 2, the regulating roller 9b has, at both ends thereof, a belt deviation regulating member (hereinafter referred to as a regulating member) for regulating a problem such as deviation or meandering which has occurred in the endless belt 9a. ) 18a and 18b are arranged.

Here, the regulating members 18a and 18b are
As shown in the figure, a regulating roller 9b and a bearing (not shown) that supports a shaft 9g of the regulating roller 9b are rotatably provided concentrically, and the inner end surface thereof is regulated by the regulating roller 9b.
And is formed to have substantially the same diameter as the regulating roller 9b.

When the endless belt 9a is shifted or meandering, the regulating guides 19a, 19b provided on both side ends of the inner peripheral surface of the endless belt 9a abut on the side surfaces of the regulating members 18a, 18b ( Locking).

It is desirable that the regulating members 18a and 18b have a low friction coefficient.
A material having good slidability is used. Further, the material of the regulation guides 19a and 19b has a low frictional stress,
And each of the rollers 9b, 9c, 9 which is a belt hanging tension member
A rubber material is used that can withstand the bending stress received when it is wound around d and 9e.

By the way, such regulating members 18a, 1
As shown in FIG. 1, the restriction roller 9b provided with the endless belt 9a has the winding angle of the endless belt 9a.
It is arranged to be the largest as compared with d and 9e. By maximizing the winding angle in this way, the regulating members 18a, 18b and the regulating guides 19a, 1
The contact area of the endless belt 9a having a large biasing force can be restricted.

The tension roller 9e is always urged by a spring 9f in the direction in which the endless belt 9a is stretched, and is arranged so that the winding angle of the endless belt 9a is minimized as compared with the other rollers 9b, 9c, 9d. Have been. In the present embodiment, the tension roller 9e is disposed upstream of the regulating roller 9b in the transport direction.

The tension roller 9e is held by a holding member (not shown) slidable along a belt urging direction in a slide groove provided in a main body frame (not shown) of the belt driving means 100B. At the same time, the endless belt 9a is urged by a compression coil spring 9f as urging means.

When the driving roller 9c is driven to rotate in the direction of the arrow (counterclockwise) by a driving source (not shown) in the belt driving means 100B thus configured, the outer peripheral surface of the driving roller 9c and the endless belt are driven. The driving force is transmitted to the endless belt 9a by the frictional force of the inner peripheral surface of the 9a, and the endless belt 9a is rotated counterclockwise between the driving roller 9c, the driven roller 9d, the tension roller 9e, and the regulating roller 9b. You.

As a result, after being conveyed from the paper feed cassette 13 or the manual paper feed unit 14, the endless belt 9a
After that, the recording paper P placed on the photosensitive drum is sequentially conveyed to each transfer unit, and yellow, cyan,
Magenta and black visible images (toner images)
Are sequentially transferred.

The recording paper P on which the visible images have been sequentially transferred in this manner is thereafter heated by the heating roller 21a of the transfer section 21.
Then, the transferred toner image is permanently fixed by being heated and pressed by the pressing roller 21b. Then, the recording paper P on which the toner image has been fixed as described above is discharged to the discharge tray 23 by the discharge rollers 22.

By the way, as described above, the endless belt 9
When the recording paper P is conveyed by the endless belt 9a
And meandering may occur. Next, the restricting member 1 for leaning and meandering on such an endless belt 9a.
The regulation operation of 8a and 18b will be described.

For example, during the rotation driving process of the endless belt 9a, as shown in FIG.
When a moves in the longitudinal direction A of the regulating roller 9b, the regulating guide 19a provided on the endless belt 9a contacts the regulating member 18a of the regulating roller 9b and is regulated. At this time, since the length in the width direction of the rollers 9c, 9d, and 9e, which are belt suspension stretching members other than the deviation regulating roller, is shorter than the regulating roller 9b, the regulating guide 19a does not abut.

When the tension of the endless belt 9a is set to be large or when the rigidity is high, the force in the longitudinal direction A applied to the regulating roller 9b, that is, the so-called deviation force is increased, and the regulation guide 19a is moved by the deviation regulating member 18a. Try to get over.

When the regulating guide 19a tries to climb over the regulating member 18a in this way, the peripheral length of the endless belt 9a on the side to be climbed becomes shorter by the thickness of the regulating guide 19a. The tension of the endless belt on the side to be increased becomes stronger and the tension becomes uneven in the width direction, and the tension roller 9e, which is a roller adjacent to the regulating roller 9b and arranged upstream in the transport direction, is moved in the biasing direction. Is pushed in the opposite direction (the direction moving away from the endless belt) and is greatly inclined with respect to the other stretching rollers 9b, 9c, 9d.

In this embodiment, since the tension roller 9e is arranged so that the belt winding angle is the smallest as compared with the other stretching rollers 9b, 9c and 9d, the tension roller 9e is attached with good response. It is pushed in the direction opposite to the urging direction, and is greatly inclined with respect to the other stretching rollers 9b, 9c, 9d.

Here, the tension roller 9e
Is inclined, the compression coil spring 9 is attached to the tension roller 9e.
f, the tension roller 9e acts in a direction to cancel the bias of the endless belt 9a, and the regulating guide 19a, which is about to ride, returns to the regular guide position.
The regulation guide 19a can be prevented from getting over the regulation member 18a.

When the winding angle of the regulating roller 9b is not large, or when the winding angle of the tension roller 9e is large, or when the tension roller 9e is not disposed adjacent to the regulating roller 9b in the transport direction upstream. In this case, it is impossible to obtain the inclination of the tension roller 9e enough to cancel the bias of the endless belt 9a.

For this reason, the regulation guides 19a, 19
When b tries to get over the deviation regulating members 18a, 18b, the regulating guides 19a, 19b are immediately worn or peeled off,
The endless belt 9a is broken due to slippage or overcoming.

However, as in the present embodiment, the winding angle of the endless belt of the regulating roller 9b is set to the largest winding angle among the tension rollers, and the belt winding angle of the tension roller 9e is minimized. Accordingly, it is possible to restrict the deviation of the endless belt 9a having a large deviation force with a low-cost and simple configuration, and it is possible to prevent the endless belt 9e from being deteriorated or damaged.

The larger the angle of the endless belt winding of the regulating roller 9b, the larger the regulating member 18
Since the contact area between the control guides 19a and 18b and the restriction guides 19a and 19b increases, the deviation of the endless belt 9a can be more reliably canceled.

The following table shows the relationship between the winding angle of the regulating roller belt and the degree of parallelism between the driving roller and the driven roller.

[0054]

[Table 1]

As is apparent from this table, the larger the winding angle of the regulating roller belt is, the higher the accuracy of the driving to the deviation of the driven roller is. Can be prevented, and the assembly and the like of the belt driving means 100B can be simplified.

For example, as shown in FIG. 9 described above, when the winding angle of the endless belt of the regulating roller 9b does not have the largest winding angle among the tension rollers, when the regulating guides 19a and 19b ride on, The degree of shortening of the circumference becomes small, and it is impossible to secure the inclination of the tension roller 9e enough to cancel the deviation of the endless belt 9a.

However, as described above, the greater the belt winding angle of the regulating roller 9b, the greater the rate of change in the circumference when the regulating guides 19a and 19b try to ride on the belt. As a result, the endless belt 9a can be more surely canceled.

On the other hand, if the winding angle of the endless belt of the tension roller 9e does not have the minimum winding angle of the tension roller, the inclination enough to cancel the deviation of the endless belt 9a according to the change in the circumferential length is secured. I can't do it. In other words, the smaller the winding angle, the more the tension roller 9 e
The roller position greatly changes with respect to the change in the circumference of a, and the roller tilts in the direction b to cancel the deviation (see FIG. 3).

From the above, by arranging the regulating roller 9b and the tension roller 9e so that the relationship of the regulating roller belt winding angle> the other stretching roller belt winding angle> the tension roller belt winding angle is established, The shift of the endless belt 9a can be surely canceled.

Further, by arranging the tension roller 9e at a position upstream of and adjacent to the regulating roller 9b in the transport direction, the belt regulating guides 19a and 19b can regulate the regulating member 1a.
8a, 18b and the tension roller 9
Experiments have shown that a synergistic effect of the inclination due to the change in the circumference of the endless belt e causes the effect of canceling the bias of the endless belt 9a to be noticeable.

On the other hand, this effect is achieved by the tension roller 9e.
If a fixed position roller is arranged instead of, the data will be greatly reduced as shown in the following data.

The data is obtained by using the belt driving device of the present embodiment shown in FIG. 1 and the belt driving device having a fixed roller disposed at the tension roller position shown in FIG. This is an experimental result on how much the parallelism can be regulated by the regulation guide by intentionally breaking the parallelism.

As a result, the allowable roller parallelism between the driving roller and the regulating roller is as follows: Tension roller: 2.6 ° or more (Higher parallelism is not possible due to the apparatus). Fixed roller: 0.9 °.

In other words, if the tension roller 9e is arranged at a position upstream of and adjacent to the regulating roller 9b in the transport direction, the endless belt 9a can be driven with a high degree of accuracy even if the parallelism between the driven roller and the driven roller is not offset. It has become clear that the occurrence of offset can be prevented.

Assuming that the belt tension is a value obtained by converting the belt biasing load C to the belt surface direction load B as shown in FIG. 4 and dividing the belt tension by the endless belt width, the phenomenon is as follows. It was visually confirmed that a tremendous effect was exhibited in a state of 14 N / mm or less.

In the present embodiment, as shown in the drawing, the belt urging direction of the tension roller 9e is changed to a tension roller (a regulating roller 9) adjacent to the tension roller 9e.
b and the driven roller 9d), the direction of the endless belt 9a is set to a direction inclined to the upstream side in the traveling direction of the endless belt with respect to the direction of the bisector L of the bending angle of the endless belt 9a. With such a configuration, the inclination of the tension roller 9e due to the difference in the left and right peripheral lengths of the endless belt can be inclined in a direction to cancel the belt shift.

Further, a comparative experiment was also conducted on the durability of the belt driving device. As a result, the belt driving device of the present embodiment achieved stable running for 300 hours or more, while the conventional belt driving device did not. In about 168 hours, the belt was damaged.

Further, the endless belt 9a has a thickness of the base material of 50 to 200 μm, a peripheral length of 300 mm or more,
mm, the distance between the pitches of the regulating roller 9b and the tension roller 9e is 5 as shown in FIG.
By setting it to 0 mm or more, the endless belt 9a can be used without increasing the accuracy of the belt deviation allowable roller parallelism.
It was found that the effect of canceling the approach was increased.

As described above, according to this embodiment, the endless belt 9a can be prevented from shifting or meandering, and the endless belt 9 can have high durability and stable running properties.

In the above description, the case where the holding member for holding the tension roller 9e is slidable only in the belt urging direction and the belt is urged via the tension roller 9e by the compression coil spring 9f is taken as an example. The present invention is not limited to this,
One side independent arm type holding member may be used as a holding member for holding the tension roller 9e.

FIG. 6 is a schematic sectional view of a color laser beam printer which is an example of such an image forming apparatus according to the second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

In the figure, reference numeral 13B denotes an arm-type holding member for holding the tension roller 9e. The arm-type holding member 13B is formed by the holding member of the first embodiment described above, which slides on the contact surface with the tension roller. 9e is moved while the tension roller 9 is
e is moved.

By moving the tension roller 9e about the shaft 13A as a fulcrum, the arm-type holding member 13B can further change its circumferential length due to the deviation of the regulating guides 19a and 19b as compared with the sliding-type holding member. , The tension roller 9e can be tilted with good responsiveness, and the effect can be further enhanced.

By the way, the regulating members 18a, 1
The shape of the inner roller 8b and the outer roller 9b are both regulated rollers 9b.
An example is shown in which the inner end face is formed to have substantially the same diameter as the regulating roller 9b, and the outer end face is formed into a tapered shape having an outer diameter smaller than the diameter of the regulating roller 9b. Alternatively, a member that has been used may be used.

FIGS. 7A and 7B are views showing the structure of such a regulating member 18A.
The inner end face has a diameter substantially the same as that of the regulating roller 9b, and notches 18c and 18d are formed at the end of the outer end face. Although not shown, a regulating member 18A having a similar configuration is provided at the other end of the regulating roller 9b.

By providing such a notch 18d, the endless belt 9a is shifted during traveling, and the circumferential length changes when the belt regulating guides 19a and 19b try to get over the regulating member 18A. Becomes gradual. As a result, it is possible to reduce the abrasion of the regulation guides 19a and 19b as compared to a case where both the inner end face and the outer end face are formed to have substantially the same diameter as the regulation roller 9b.

[0077]

As described above, according to the present invention, the endless belt winding angle of the predetermined driven roller provided with the belt deviation regulating member is set to be the largest among the rollers of the belt driving means. In addition, by making the winding angle of the endless belt of the tension roller the smallest among the rollers of the belt driving means, when the belt deviation regulating guide tries to get over the belt deviation regulating member, the tension roller moves toward the belt. -It becomes mechanically inclined in the direction to cancel the meandering, and it is possible to prevent the deviation regulating guide member from going over the deviation regulating member. As a result, it is possible to prevent the endless belt from shifting or meandering, and to deteriorate the endless belt,
Damage can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a color laser beam printer as an example of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a driven roller of a belt driving device provided in the color laser beam printer.

FIG. 3 is a perspective view illustrating the operation of the belt driving device for restricting belt deviation.

FIG. 4 is a view for explaining how to apply belt tension of an endless belt of the belt driving device.

FIG. 5 is a diagram showing the relationship between the distance between the pitches of the driven roller and the tension roller and the allowable parallelism of the drive roller and the driven roller toward the belt.

FIG. 6 is a schematic sectional view of a color laser beam printer as an example of an image forming apparatus according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration of a regulating member provided in a belt driving mechanism of the color laser beam printer.

FIG. 8 is a perspective view of a main part showing a configuration of an endless belt and a belt driving mechanism of a conventional image forming apparatus.

FIG. 9 is a diagram illustrating a configuration of a conventional image forming apparatus.

DESCRIPTION OF SYMBOLS 9a Endless belt 9c Drive roller 9b Restriction roller 9e Tension roller 13B Arm type holding member 18a, 18b Restriction member 18c Notch 18A Restriction members 19a, 19b Restriction guide 100 Printer 100A Image forming part 100B Belt driving means P Recording material

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kenji Watanabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Riki Imaizumi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term in the company (reference) 2H032 AA05 AA15 BA18 BA19 BA23 3F049 AA01 AA02 BA03 BB06 BB11 LA04 LB03

Claims (7)

[Claims] An endless belt that conveys a sheet to an image forming unit; a belt drive that drives the endless belt while stretching the endless belt with a driving roller, a plurality of driven rollers, and a tension roller that urges the endless belt. And at least one belt deviation regulating guide formed at a side end of an inner peripheral surface of the endless belt; provided at a side end of a predetermined driven roller; At least one belt deviation regulating member that abuts the belt deviation regulating guide during rotation of the belt to prevent the widthwise deviation of the endless belt, and wherein the belt deviation regulating member is provided. The driven roller is arranged such that the winding angle of the endless belt of the driven roller is the largest among the rollers of the belt driving means, and Forming an endless belt on the upstream side in the moving direction of the endless belt of the driven roller, and so that the winding angle of the endless belt is the smallest among the rollers of the belt driving means. apparatus. 2. A belt urging direction of the tension roller is defined by a bisecting direction of a bending angle of the endless belt formed by a tangent line between the tension roller and a roller of the belt driving means adjacent to the tension roller. The image forming apparatus according to claim 1, wherein the direction is set to a direction inclined toward the upstream side in the endless belt conveyance direction. 3. The tension roller according to claim 1, wherein both ends of the tension roller are held independently by arm type holding members.
Or the image forming apparatus according to 2. 4. The image forming apparatus according to claim 1, wherein a cutout portion of an inclined surface is formed on a surface of the belt deviation regulating member that contacts the belt deviation regulating guide. apparatus. 5. The distance between the driven roller provided with the belt deviation regulating member and the tension roller is set in accordance with the thickness and the circumference of the endless belt. 2. The image forming apparatus according to claim 1. 6. An endless belt for conveying a sheet, and belt driving means for driving the endless belt while stretching the endless belt with a driving roller, a plurality of driven rollers, and a tension roller for urging the endless belt. In the sheet conveying device, a belt deviation regulating guide formed so as to protrude along both sides of the inner peripheral surface of the endless belt along the circumferential direction; A belt deviation regulating member that is provided at an end and abuts on the belt deviation regulating guide during rotation of the endless belt to prevent a deviation in the width direction of the endless belt. A predetermined follower roller provided with a belt shift regulating member is disposed on the upstream side in the moving direction of the endless belt, and the belt shift regulating guide is arranged to regulate the belt shift. Sheet conveying apparatus characterized by having a support means for supporting said tension roller to tilt the rotational axis of the tension roller with respect to the rotation axis direction of the predetermined driven roller when riding on wood. 7. An image forming apparatus, comprising: the sheet conveying apparatus according to claim 6; and image forming means for forming an image on a sheet conveyed by the endless belt.