JPH0826517A - Belt conveyer - Google Patents

Abstract

PURPOSE:To prevent a walk of a belt member, so that edge force can be reduced, by forming partly a plurality of rollers, winding the belt member linked, into an elastic roller working an external diameter of an elastic fin to provide fixed directivity, and setting a working direction of elastic fin of at least the one elastic roller to a reverse direction to the other. CONSTITUTION:In a color electrophotographic copying machine, a belt member 8 of conveying a recording sheet 3 is linked around over a drive roller 4, which is a metal-made roller, edge guide roller 5 and driven rollers 6, 7. Here is used an elastic roller 20 in the edge guide roller 5 and the driven rollers 6, 7. This elastic roller 20 is formed into diskshaped elastic fins 22 along an axial direction of a rotary shaft 21, that is, the fins 22 vertically providing a plurality of disk fins, and a working direction of the elastic fin 22 of the elastic roller 20, used in the driven rollers 6, 7, is set to the direction toward a front side from a rear side of the copying machine, to set that of the elastic roller 20 as the edge guide roller 5 to the reverse direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt conveying device for rotating an endless belt member such as a recording sheet conveying belt or a photoconductor belt in a color image forming apparatus or the like. The present invention relates to an improvement of a belt conveyance device having a meandering prevention means.

[0002]

2. Description of the Related Art As a belt conveying device equipped with an endless belt member meandering preventing means, one disclosed in Japanese Patent Laid-Open No. 5-319611 is known.

In this belt conveying device, the belt member is wound around a driving roll and a plurality of driven rolls, and is configured to circulate at a predetermined speed as the driving roll rotates. One of the driven rolls is an edge guide roll that guides the end of the belt member, and the edge guide roll prevents the belt member from meandering.

FIG. 12 shows the edge guide roll and its peripheral equipment. In the figure, reference numeral 50 is an edge guide roll, reference numeral 51 is a belt member that moves in the direction of arrow A, and reference numeral 52 is an edge guide attached to one end of the edge guide roll 50 in the axial direction. The edge guide 52 is arranged so as to be movable back and forth along the axial direction of the edge guide roll 50 (direction of arrow B), and is biased toward the belt member 51 by a spring 53. An adjuster mechanism 54 is attached to the spring 53 so that the biasing force of the spring 53 can be freely adjusted.

On the other hand, as shown in FIGS. 12 and 13, the edge guide roll 50 is an elastic roll in which elastic fins 50a surrounding the rotary shaft 50b are repeatedly erected in the axial direction of the rotary shaft 50b. Is divided into a plurality along the circumferential direction. Further, the edge guide roll 50 is arranged with a slight angle difference with respect to the drive roll, and the belt member 51 constantly moves on the edge guide roll 50 along with the rotation thereof.
It is designed so as to cause a deviation in two directions (hereinafter referred to as a belt walk).

Therefore, the belt member 51 has its end portion 5
The 1a is always rotated while slidingly contacting the edge guide 52. At this time, the biasing force of the edge guide 52 is applied to the force (hereinafter, walk force) of the belt member 51 approaching in the edge guide direction. By balancing
The belt walk generated on the belt member 51 could be completely eliminated.

Further, when the belt walk of the belt member 51 is forcibly locked by the edge guide 52 as described above, the reaction force of the above-mentioned walk force with respect to the end portion 51a of the belt member which is in sliding contact with the edge guide 52 (hereinafter, Edge force) may cause damage to the end portion 51a of the belt member, such as buckling or cracking. However, since the above-described elastic roll is used as the edge guide roll 50 in this belt conveyance device, the belt member When the edge force acts on the end portion 51a of the sheet, the elastic fin 50a of the edge guide roll 50 is bent in the axial direction, and the edge force can be reduced. Therefore, the edge guide 52
Therefore, even if the belt walk of the belt member 51 is forcibly locked, the end portion 51a of the belt member can be prevented from being damaged.

The publication also discloses an embodiment in which a pair of edge guides are arranged at both ends of the belt member without providing a difference in arrangement angle between the edge guide roll and the drive roll.

Further, as the elastic roll, conventionally, there are proposed one in which the elastic fins 50a adjacent to each other are formed in an independent disk shape, and one in which the elastic fins 50a adjacent to each other are formed in a continuous spiral shape. Has been done.

In the former elastic roll, its elastic fins 50 are
Since a is formed parallel to the conveyance direction of the belt member 51, if the belt member 51 is used for a long period of time while being strongly pressed against the elastic roll, the surface of the belt member 51 becomes uneven due to the pressing marks of the elastic fins 50a. However, when a toner image is transferred from the photoconductor drum to the recording sheet conveyed by the belt member 51, there is a problem that the transfer omission occurs. On the other hand, in the latter elastic roll, since the elastic fin 50a is formed in a spiral shape, the elastic fin 50a uniformly abuts on the surface of the belt member 51 as the elastic roll rotates, so that the belt member 51 There is an advantage that unevenness is unlikely to occur on the surface of the toner and the transfer failure of the toner image can be prevented even in the case described above.

[0011]

In the conventional method of manufacturing the elastic roll, first, the elastic fin 50a is erected around the rotary shaft 50b by injection molding of a flexible material such as rubber or synthetic resin. Then, the outer peripheral surface of the injection-molded roll is polished or cut from one end to the other end to finish the outer diameter of the elastic fin 50a to a predetermined diameter. Such a manufacturing method includes a disk-shaped elastic fin (hereinafter referred to as a disk fin) or a spiral elastic fin (hereinafter, referred to as a disk-shaped elastic fin).
(This is referred to as a spiral fin)

However, in this manufacturing method, the elastic fin 50 is used.
In the finishing process of the outer diameter of a, since the outer peripheral surface of the roll is polished or cut from one end to the other end, each elastic fin 50a is deformed in the same traveling direction of the tool during the machining. 14 is processed in the state shown in FIG.
As shown in (4), there is a drawback that the outer peripheral surface of each elastic fin 50a is tapered.

Therefore, the belt member 5 is attached to the elastic roll.
When the belt transporting device is constructed by wrapping around 1, the elastic fins 50a are pressed by the belt member 51 and deformed into the state shown in FIG. 15, and the belt member 51 is attempted to be transported in a direction to cancel this deformation. That is, the elastic fins 5
The walk force in the direction of arrow C, which is opposite to the direction of the outer diameter machining of 0a, acts on the belt member 51, and the belt walk occurs. As a result, the edge guide 52
Therefore, the edge force acting on the end portion of the belt member 51 is increased, and there is a problem that the effect of the elastic roll provided for reducing the edge force is reduced by half.

Further, as described above, the elastic roll having the spiral fin is superior to the elastic roll having the disc fin from the viewpoint of preventing the deformation of the belt member 51, but the spiral on the elastic roll. Due to the winding direction of the fins, a walking force is likely to act on the belt member 51, and there is a problem that the edge force is increased as compared with the case where an elastic roll having disk fins is used.

The present invention has been made in view of such an object, and an object thereof is to prevent a walk of a belt member due to incomplete molding of an elastic roll around which the belt member is wound. An object of the present invention is to provide a belt conveying device capable of reducing the edge force acting on the end portion of the belt member.

Another object of the present invention is to reduce the walk force applied to the belt member by the elastic roll having the spiral fins, and thus to reduce the edge force acting on the end portion of the belt member. It is to provide a belt transport device.

[0017]

In order to achieve the above-mentioned object, the inventor of the present invention includes a plurality of elastic rolls in which elastic fins surrounding a rotary shaft are erected repeatedly along the axial direction, and these elastic rolls are included. The invention according to each of the claims is provided on the premise of a belt conveying device including a belt member that is circulated around a plurality of rolls and moves circularly.

First, according to the first aspect of the invention, as the elastic roll, a roll in which the outer diameter of the elastic fin has a certain directionality is processed, that is, an elastic roll obtained by the above-mentioned conventional manufacturing method. It is characterized in that at least one elastic roll is arranged so that its processing direction is opposite to that of the other elastic rolls.

The invention according to claim 2 is characterized in that as the elastic roll, a roll is used in which the outer diameter of the elastic fin is processed in opposite directions with the axial center as a boundary. Is.

Further, the invention according to claim 3 is characterized in that, as the elastic roll, a roll formed by forming a plurality of annular grooves at predetermined intervals on the outer peripheral surface of a cylindrical roll having an outer diameter processed is used. It is what

Further, the invention according to claim 4 is a spiral fin in which the elastic fins of the elastic roll are spirally formed, and the spiral fin is composed of at least two spiral groups having different winding directions. It is what

Further, the invention according to claim 5 is characterized in that, in the fourth technical means, spiral fins are formed symmetrically with a substantially central portion in the axial direction of the elastic roll as a boundary. .

Further, the invention according to claim 6 relates to the plurality of elastic rolls around the belt member in the fourth technical means, wherein the boundary portion between two spiral groups adjacent to each other is the belt member. It is characterized in that it corresponds to different positions in the width direction.

Further, in the seventh aspect of the present invention, in the sixth technical means, among a plurality of elastic rolls around the belt member, a contact angle with the belt member (as shown in FIG. 11, The elastic roll having the maximum angle θ) indicating the contact length with the belt member in the circumferential direction of the elastic roll has a feature that a boundary portion of the spiral group is provided at a substantially central portion in the axial direction thereof. is there.

In these technical means, the plurality of rolls around the belt member may be all elastic rolls, but from the viewpoint of stabilizing the moving speed of the belt member, It is preferable that only the drive roll that transmits the rotational force of the motor to the belt member is a rigid roll (for example, a metal roll or a roll in which this is covered with a rubber coating) having a small variation in outer diameter.

[0026]

According to the invention described in claim 1, since the plurality of elastic rolls around which the belt member is stretched are processed so that the outer diameters of the elastic fins have a certain directionality, each elastic roll is elastic. An attempt is made to walk the belt member in a direction opposite to the fin processing direction. At this time, since at least one elastic roll is arranged such that its processing direction is opposite to that of the other elastic rolls, the elastic roll causes a belt walk in a direction opposite to the other elastic rolls. As a result, the belt walk caused by the incomplete molding of the elastic roll is canceled out as a whole of the belt conveying device, and the edge force acting on the end portion of the belt member can be reduced.

Further, according to the second aspect of the present invention, the plurality of elastic rolls around the belt member are processed so that the outer diameters of the elastic fins are opposite to each other with the center in the axial direction as a boundary. Therefore, the elastic roll tries to cause a belt walk in a direction in which the elastic fin located in the right half and the elastic fin located in the left half along the axial direction are opposite to each other. Accordingly, the belt walk caused by the incomplete molding of the elastic rolls is canceled by the individual elastic rolls, and the edge force acting on the end portion of the belt member can be reduced.

Further, according to the third aspect of the present invention, since each elastic roll is processed by forming annular grooves at a predetermined interval on the outer peripheral surface of the cylindrical roll having the outer diameter processed, the elastic roll is processed. It is not necessary to perform outer diameter processing on the outer peripheral surface of the fin after it is formed. Therefore, the outer diameter of the elastic fin is not formed in a taper shape, and the belt walk does not occur in the belt member due to the incomplete molding of the elastic roll. Therefore, the edge force acting on the end portion of the belt member can be reduced.

Further, according to the invention of claim 4, a spiral fin is formed on the elastic roll around which the belt member is wound, so that a walk force is easily applied to the belt member. However, since such a spiral fin is composed of at least two spiral groups having different winding directions, the spiral fins belonging to each spiral group exert walking forces in different directions on the belt member. As a result, the walk forces exerted by the spiral groups on the belt member are canceled by each other, and the edge force acting on the end portion of the belt member can be reduced.

In addition to the invention described in claim 4 which achieves such an action, in the invention described in claim 5, since the spiral fins are formed symmetrically with the substantially center in the axial direction of the elastic roll as a boundary, the elastic roll is formed. The walk force exerted by the spiral fins on the belt member balances with each other with the axial center of the elastic roll as a boundary.
Belt walk due to the spiral fin is prevented as much as possible.

However, if the invention according to claim 5 is applied to all of the plurality of elastic rolls around which the belt member is wound, the boundary part of the spiral group in all the elastic rolls is substantially in the axial direction of the elastic rolls. Since it is located in the center, the specific area on the belt member always passes through the boundary portion on any elastic roll, so that unevenness occurs on the belt member corresponding to the boundary portion. I have a concern.

From this point of view, in the invention according to claim 6, the boundary portions of the spiral groups of the plurality of elastic rolls are made to correspond to different positions in the width direction of the belt member. It is possible to prevent unevenness from occurring as much as possible.

On the other hand, of the plurality of elastic rolls around which the belt member is wound, the elastic roll having the maximum contact angle with the belt member, in other words, the elastic roll having the maximum pressure contact force of the belt member is The walk force exerted on the member is larger than that of other elastic rolls. With respect to this point, in the invention according to claim 7, the elastic roll having the maximum contact angle with the belt member is provided with the boundary portion of the spiral group at substantially the center in the axial direction. The invention according to claim 6 can prevent the belt member from being deformed as much as possible while preventing the walk force from acting on it.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The belt conveyor of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an example of a color electrophotographic copying machine in which the belt conveying device of the present invention is used to convey a recording sheet. Specifically, an endless belt member 8 is stretched by a drive roll 4, an edge guide roll 5, and driven rolls 6 and 7 in a conveyance path of the recording sheet 3 that connects the recording sheet supply tray 1 and the fixing device 2. , Toner image (visible image) corresponding to each color of black BK, yellow Y, magenta M, and cyan C by electrophotographic process
The four sets of image forming units 9 forming the above are arranged on one side of the belt member 8 at appropriate intervals.

Each image forming unit 9 includes a photosensitive drum 1.
Charger 11 and laser beam scanning unit 1 around 0
2, developing device 13, transfer corotron 14 and cleaner 15
The toner images corresponding to the image information of each color are formed on the photosensitive drum 10, and the toner images are transferred to the recording sheet 3 conveyed by the belt member 9.

Therefore, the recording sheet 3 carried out from the supply tray 1 is held by the belt member 8 at a predetermined timing, and then sequentially from the image forming units 9, 9, ... As the belt member 8 moves. It receives the transfer of each color toner image and carries a full-color toner image. Then, the recording sheet 3 on which the transfer of the toner image is completed is peeled from the belt member 8 and then sent out onto the discharge tray 16 via the fixing device 2.
The formation of the color recorded image is completed.

Next, the specific structure of the belt conveying device for conveying the recording sheet in this color electrophotographic copying machine will be described.

First Embodiment In this color electrophotographic copying machine, the toner image is sequentially transferred to the recording sheet 3 conveyed by the belt member 8. Therefore, when a belt walk occurs on the belt member 8, the recording is performed. Subtle color misregistration occurs between the toner images of the respective colors that have been multi-transferred onto the sheet 3. For this reason,
An edge guide 18 is provided at the shaft end of the edge guide roll, and the belt member 8 circulates while the end portion of the belt member 8 is in sliding contact with the edge guide 18, thereby preventing a belt walk. Since the detailed structure of the edge guide 18 is the same as that of the conventional technique described with reference to FIG. 11, the description thereof is omitted here.

Further, in order to prevent the moving speed of the belt member 8 from varying, the drive roll 4 connected to a motor (not shown) is made of a metal which is ground or ground to a predetermined outer diameter. Uses rolls.

On the other hand, in order to reduce the edge force exerted by the edge guide 18 on the end portion of the belt member 8, among the plurality of rolls around the belt member 8, rolls other than the drive rolls, that is, the edge guide rolls 5 and As the driven rolls 6 and 7, elastic rolls whose structure has been described in the prior art are used. Further, in order to apply a constant tension to the belt member 8, the edge guide roll 5 is fixed to the spring 17
The belt member 8 was urged from the inside to the outside.

FIG. 2 shows the elastic roll 20 used in this embodiment. The elastic roll 20 includes a disk-shaped elastic fin 22 along the axial direction of the rotating shaft 21,
That is, a plurality of disc fins are provided upright, and each disc fin 22 is equally divided into a plurality along the circumferential direction. In the processing, injection molding is used around the rotary shaft 21 to erect the disk fins 22 made of rubber or flexible synthetic resin, and after the completion of this molding step, the outer peripheral surface of each disk fin 22 has a predetermined outer diameter. It is done by polishing or grinding.

This polishing or grinding process is carried out by feeding the tool in the direction of the arrow from one end to the other end of the elastic roll 20, and the outer peripheral surface of each disk fin is as shown in FIG. 13 according to the processing direction. Will be processed into a tapered shape. When the belt member 8 is stretched around the elastic roll that has been processed into such a shape, a belt walk occurs in a direction opposite to the processing direction (see FIG. 14), and the taper angle becomes large. Depending on the size of the belt walk. Therefore, it can be said that each elastic roll 20 has a certain processing directionality that causes a belt walk, and the strength of the character also differs for each elastic roll.

Therefore, in this embodiment, when assembling a belt conveying device using such elastic rolls, at least one of the plurality of elastic rolls around which the belt member is stretched has a different processing direction. The elastic roll was arranged in the opposite direction to the processing direction. For example, as shown in FIG. 3, elastic rolls 2 used as driven rolls 6 and 7
When 0 has a processing direction from the rear side to the front side of the copying machine, the elastic roll 20 used as the edge guide roll 5 is arranged so that the processing direction goes from the front side to the rear side.

With respect to all the elastic rolls 20 used in the belt conveying device, the total strength of the processing direction from the front side to the rear side and the strength of the processing direction from the rear side to the front side. Is very different from the sum of
As a result, the belt member 8 causes a belt walk in either direction. Therefore, the belt conveying device is assembled so that the sum of these processing directions becomes substantially equal.

Since the processing direction of each elastic roll 20 and the strength of its character cannot be judged from the outside, the processing direction of the elastic roll 20 to be used in advance is measured at the time of assembling the belt conveyor, and the measurement result is obtained. The device was assembled based on the above. As shown in FIG. 4, the elastic roll 20 is rolled on the surface plate 23, the processing direction is determined according to the rolling direction, and the strength of the character is determined according to the amount of axial movement at that time. I saw it. That is, the elastic roll 2
When 0 rolls straight in the direction of the broken line in the figure, belt walk does not occur in the belt member 8, but when the elastic roll 20 rolls by bending in either the left or right direction, the same direction as the rolling direction. The belt walk will occur on the belt member 8. Further, if the elastic roll 20 largely moves in the axial direction on the surface plate, the belt walk generated on the belt member 8 also becomes large.

The measurement result depends on the rolling direction and the amount of movement in the axial direction. For example, in the case of right turn, L ₁ , L ₂ , L ₃
And if it is a left turn, R ₁ , R ₂ , R ₃ and each elastic roll 2
Recorded every 0.

Therefore, in assembling the belt conveying device of this embodiment, the contradictory strengths of the working directions are substantially equal to each other on the basis of the measurement results recorded for each elastic roll 20. Further, the elastic roll 20 used for the edge guide roll 5 and the driven rolls 6 and 7 is selected. For example, the driven rolls 6 and 7 are L ₁ and
If the L ₂ elastic roll is used, the R ₃ elastic roll 20 is used as the edge guide roll 5. As a result, the walk force given to the belt member by the driven rolls 6 and 7 and the walk force given to the belt member by the edge guide roll 5 are counterbalanced with each other, which is caused by the imperfect formation of the elastic roll. It is possible to prevent the occurrence of belt walk.

In this embodiment, the processing direction of the manufactured elastic roll 20 and the strength of its character are measured, and the elasticity used for the edge guide roll 5 and the driven rolls 6 and 7 is based on the measurement result. I decided the role,
The processing conditions of the edge guide roll 5 and the driven rolls 6 and 7 are determined in advance and the rolls 5 and 6 are
It is also possible to give a specific processing direction and strength to the characters 7 and 7.

That is, as described above, the processing direction of the elastic roll 20 is determined by the direction of polishing or grinding of the disk fins, and the strength of the character is also determined by parameters such as the feed rate of the tool in the processing. Will end up. Therefore, unique processing parameters are set for each of the edge guide roll 5 and the driven rolls 6 and 7, and the edge guide roll 5 is set based on these parameters.
By processing the elastic roll 2 used for the driven rolls 6 and 7, it is possible to give each of the rolls 5, 6 and 7 a specific processing direction and strength of its character.

Therefore, in this way, the edge guide roll 5
By giving unique processing parameters to each of the driven rolls 6 and 7, it is possible to immediately assemble the belt conveying device of this embodiment without measuring the above-mentioned processing direction. The first embodiment can be similarly applied even when the elastic roll is provided with the spiral fin.

Second Embodiment The belt conveyor shown in this embodiment has the same appearance as the belt conveyor explained in the first embodiment, but is illustrated as an edge guide roll 5 and driven rolls 6 and 7. The elastic roll 30 shown in FIG.

The elastic roll 30 has a rotary shaft 31.
A plurality of disk fins 32 are provided upright along the axial direction of the disk fin 32, and each disk fin 32 is equally divided into a plurality along the circumferential direction. In the processing, the disk fins 32 made of rubber or soft synthetic resin are erected around the rotary shaft 31 by using injection molding, and after the completion of this molding step, the outer peripheral surfaces of the respective disk fins 32 have a predetermined outer diameter. It is done by polishing or grinding.

At this time, the above-mentioned polishing or grinding is carried out by feeding the tools in mutually opposite directions with the axial center of the elastic roll 30 as a boundary. For example, if the right half of the elastic roll 30 is processed from the center toward the shaft end as indicated by the arrow, the left half is also processed from the center toward the shaft end as indicated by the arrow. On the contrary, the right half and the left half may be machined from the shaft end toward the center.

As a result, the elastic roll 30 has both opposite directionalities with the center in the axial direction as a boundary, and the elastic roll 30 tries to displace the belt member 8 from the front side to the rear side. The walking force that tries to be displaced from the rear side to the front side is balanced. That is, even if the belt member 8 is stretched around the elastic roll 30 and conveyed, the belt walk does not occur in the belt member 8.

Therefore, if the elastic roll 30 thus processed is used as the edge guide roll 5 and the driven rolls 6 and 7, the belt walk of the belt member 8 due to the incomplete molding of the elastic roll 30 can be prevented. can do. The second embodiment can also be applied in the same manner even when the elastic roll is provided with a spiral fin.

Third Embodiment The belt conveyor shown in this embodiment has the same appearance as the belt conveyor explained in the first embodiment, but is illustrated as an edge guide roll 5 and driven rolls 6 and 7. The elastic roll 40 shown in 6 was used.

This elastic roll 40 also has a rotary shaft 41.
A plurality of disk-shaped disc fins 42 are erected in the axial direction of the disk fin, and each disk fin 42 is equally divided into a plurality along the circumferential direction. However, the processing is different from the above-mentioned embodiment, after the rubber or the flexible synthetic resin is attached to the periphery of the rotary shaft 41 to form the cylindrical roll 43, and then the outer peripheral surface of the cylindrical roll 43 has a predetermined outer diameter. A plurality of annular grooves 4 at a predetermined interval on the outer peripheral surface of the cylindrical roll 43 by grinding or grinding into
4 is formed. That is, the disc fin 42 is erected on the rotating shaft 41 by cutting it out from the cylindrical roll 43.

According to such a processing method, the outer diameter of the disk fin 42 is the cylindrical roll 43 before it is cut out.
Since the outer peripheral surface of the cylindrical roll 43 does not bend in the axial direction during polishing or grinding unlike the disk fin 42, it can be accurately processed with a predetermined outer diameter. Therefore, the outer peripheral surface of the disk fin 42 is not formed in a tapered shape as shown in FIG. 9, and the belt member 8 wound around the elastic roll 40 is not formed.
Neither is a walk force applied in either direction.

Therefore, since the disk fin 42 of the elastic roll 40 manufactured by such a processing method is formed in an ideal shape, this elastic roll 40 is used for the edge guide roll 5 and the driven rolls 6 and 7. In the belt conveying device of this embodiment, the belt walk does not occur due to the incomplete molding of the elastic roll. In the third embodiment, the cylindrical roll 43 having an outer diameter processed is used.
It is also possible to form spiral fins instead of disk fins by subjecting the same to spiral cutting.

Fourth Embodiment In this embodiment, elastic rolls in which spiral so-called spiral fins are erected as elastic fins are used as the edge guide rolls 5 and the driven rolls 6 and 7, and the belt conveyance shown in FIG. Configured the device. A metal roll was used as the drive roll 4 for the same reason as in the first embodiment.

First, FIG. 7 shows an elastic roll 25 used as the driven rolls 6, 7. The elastic roll 25 is formed by arranging spiral elastic fins 27, that is, spiral fins, along the axial direction of the rotating shaft 26. The spiral fin 27 is composed of two spiral groups G ₁ and G _{2 having} different winding directions around the rotary shaft 26, and an elastic fin 27 is formed at a boundary portion 28 between these spiral groups G ₁ and G _2. Without a slight gap.

Further, the boundary portion 28 is provided at a position displaced from the axial center of the elastic roll 25 toward the axial end direction. In the example shown in FIG. 7, the area of the spiral group G ₁ is the spiral group G ₂ . It is set shorter than the area. However, both ends 29, 29 of the rotary shaft 26 of the elastic roll 25 are processed into the same shape, and when assembling the belt conveying device, which one of the shaft ends 29 is on the front side (front side of the plane of FIG. 1). ) Is configured so that it does not matter.

On the other hand, FIG. 8 shows an elastic roll 35 used as the edge guide roll 5. This elastic roll 35 is also one in which a spiral fin 37 composed of two spiral groups G ₃ and G ₄ is erected on the rotating shaft 36, but unlike the case of the driven rolls 6 and 7 described above, the spiral group G ₃ , G ₄ is formed at the center of the elastic roll 35 in the axial direction.

FIG. 9 is a plan view of the belt conveying device of this embodiment constructed by using the edge guide roll 5 and the driven rolls 6 and 7. In the figure, the edge guide 18 attached to one end of the edge guide roll 5 is omitted.

As already mentioned, the edge guide roll 5
8 is used for the driven rolls 6 and 7, and the elastic roll 25 shown in FIG. 7 is used for the driven rolls 6 and 7, but the driven rolls 6 and 7 are of the spiral groups G ₁ and G ₂ with respect to the belt member 8. It was arranged so that the positional relationship was upside down. That is, the driven rolls 6 and 7 are arranged such that the boundary portion 28 provided on the elastic roll 25 is laterally distributed with respect to the center of the belt member 8 in the width direction.

As a result, the walk force applied to the belt member 8 by the spiral fin 27 of the driven roll 6 as the driven roll 6 rotates, and the spiral fin 27 of the driven roll 7 as the belt rolls as the driven roll 7 rotates. Since it is balanced with that given to the member 8, belt walk due to the rotation of these driven rolls 6 and 7 can be prevented.

Regarding the edge guide roll 5,
Since the spiral groups G ₃ and G ₄ are evenly arranged on the left and right with respect to the center of the belt member 8 in the width direction, the walking force applied to the belt member 8 by the spiral fins 37 of the edge guide roll 5 is as shown in FIG. They are in balance with each other in the left-right direction on the paper surface. Therefore, it is possible to prevent a belt walk due to the rotation of the edge guide roll 5.

Here, in this embodiment, the boundary portion 38 is formed at the center in the axial direction of the elastic roll 35 only for the edge guide roll 5, as is apparent from FIG. Contact angle θ
Is set to be larger than that of the other driven rolls 6 and 7, and the edge guide roll 5 and the belt member 8 are correspondingly set.
This is because the pressure contact force with That is, since the pressure contact force between the edge guide roll 5 and the belt member 8 is large,
The spiral fin 37 of the edge guide roll 5 gives a large walk force to the belt member 8, and if the spiral groups G ₃ and G ₄ are not formed symmetrically with respect to the boundary portion 38, the belt member 8 will be described. This is because there is a high possibility that a belt walk will occur in No. 8.

The contact angle θ of the belt member 8 with respect to the edge guide roll 5 is set larger than that of the other driven rolls 6 and 7 because the pressure contact force between the edge guide roll 5 and the belt member 8 is set. This is because if it is small, the walking force in the direction of the edge guide 18 (not shown in FIG. 9) does not sufficiently act on the belt member 8 and the belt member 8 is separated from the edge guide 18 that serves as a conveyance reference.

Further, regarding the driven rolls 6 and 7,
Walk that the spiral fin 27 exerts on the belt member 8
From the perspective of reducing power, spiral glue
G ₁, G₂The boundary 28 of the belt member 8 in the widthwise center
It is good to correspond to
Boundary 38 of the guide roll 5, boundary of the driven roll 6
28 and the boundary portion 28 between the driven roll 7 and the belt member 8 respectively.
Since it corresponds to the center of the width direction of
At this time, a concave portion is formed in the belt member 8, and each image forming unit is
White spots appear on the toner image transferred from recording sheet 9 to recording sheet 3.
There is a concern.

On the other hand, in the belt conveying device of this embodiment shown in FIG. 9, the boundary portion 3 of the edge guide roll 5 is
8. Since the boundary portion 28 of the driven roll 6 and the boundary portion 28 of the driven roll 7 correspond to different positions in the width direction of the belt member 8, there is no concern that a concave portion may be formed at a specific position of the belt member 8. It is possible to prevent white spots from occurring in the toner image transferred to the recording sheet 3.

In the fourth embodiment, the elastic roll used as the edge guide roll 5 may be that shown in FIG. That is, as shown in the figure, the boundary portion 46 is provided at the center of the elastic roll 45 in the axial direction, and the spiral groups g ₁ , g ₂ , g ₃ , g ₄ are symmetrically formed with respect to the boundary portion 46. There can be any number of spiral groups provided that they are formed.

[0073]

As described above, according to the belt conveying device of the first to third aspects, in any of the technical means, due to the incomplete molding of the elastic roll, the belt walks to the belt member. It is possible to reduce the edge force acting on the end portion of the belt member and prevent the belt member from being damaged as much as possible.

Further, according to the belt transporting device of the fourth and fifth aspects, in constructing the belt transporting device using the elastic roll having the spiral fin, the walk force applied to the belt member by the spiral fin is reduced. As a result, the edge force acting on the end portion of the belt member can be reduced.

Further, according to the belt transporting device of the sixth and seventh aspects, in addition to the effects of the belt transporting device of the fourth and fifth aspects, it is possible to prevent unevenness in a specific region of the belt member. Therefore, it is possible to prevent the occurrence of a transfer failure when the toner image is transferred using this belt conveying device.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a color electrophotographic copying machine in which a belt carrying device of the present invention is used for carrying a recording sheet.

FIG. 2 is a front view showing an elastic roll used in the first embodiment of the belt conveyance device of the present invention.

FIG. 3 is a perspective perspective view illustrating an arrangement state of elastic rolls in the belt transport device according to the first embodiment.

FIG. 4 is a schematic view showing a method of measuring the processing direction of the elastic roll according to the first embodiment.

FIG. 5 is a front view showing an elastic roll used in a second embodiment of the belt conveyor according to the present invention.

FIG. 6 is a front view showing an elastic roll used in a third embodiment of the belt conveyor according to the present invention.

FIG. 7 is a front view showing an elastic roll used as a driven roll of the belt conveyor according to the fourth embodiment.

FIG. 8 is a front view showing an elastic roll used as an edge guide roll of a belt conveyor according to a fourth embodiment.

FIG. 9 is a plan view showing a belt conveyance device according to a fourth embodiment.

FIG. 10 is a front view showing another example of the edge guide roll according to the fourth embodiment.

FIG. 11 is a diagram illustrating a contact angle θ between a belt member and an elastic roll.

FIG. 12 is a front view showing the structure of a conventionally known edge guide roll.

FIG. 13 is a side view of a conventionally known elastic roll.

FIG. 14 is a partially enlarged view showing the shape of an elastic fin of a conventionally known elastic roll.

FIG. 15 is a partially enlarged view showing a state in which an elastic fin of a conventionally known elastic roll applies a walking force to a belt member.

[Explanation of symbols]

4 ... drive roll, 5 ... edge guide roll, 6, 7 ... driven roll, 8 ... belt member, 20, 30, 40 ... elastic roll, 22, 32, 42 ... disk fin, 27, 37
... Spiral fins, 28, 38 ... Boundary, 43 ... Cylindrical roll, 44 ... Annular groove

Claims (7)

[Claims] 1. An elastic fin surrounding a rotating shaft is constituted by a plurality of elastic rolls repeatedly erected in the axial direction, and a belt member circulated around a plurality of rolls including these elastic rolls. In the belt transport device according to claim 1, the elastic roll is a roll in which the outer diameter of the elastic fin is processed with a certain directionality, and at least one elastic roll has a processing direction opposite to that of the other elastic rolls. A belt conveying device, which is arranged so as to face. 2. An elastic fin that surrounds a rotating shaft is constituted by a plurality of elastic rolls that are repeatedly erected in the axial direction, and a belt member that circulates around the plurality of rolls including these elastic rolls. In the belt conveying device according to the present invention, the elastic roll is processed such that the outer diameters of the elastic fins are processed in opposite directions with the axial center as a boundary. 3. An elastic fin surrounding a rotating shaft is constituted by a plurality of elastic rolls standing upright along the axial direction, and a belt member circulated around the plurality of rolls including these elastic rolls. In the belt conveying device according to the present invention, the elastic roll is formed by forming a plurality of annular grooves at predetermined intervals on the outer peripheral surface of a cylindrical roll having an outer diameter processed. 4. An elastic fin surrounding a rotating shaft is constituted by a plurality of elastic rolls which are erected repeatedly along the axial direction, and a belt member which circulates around a plurality of rolls including these elastic rolls. In the belt conveying device according to the present invention, the elastic fin of the elastic roll is a spiral fin formed in a spiral shape, and the spiral fin is composed of at least two spiral groups having different winding directions. . 5. The belt conveying device according to claim 4, wherein the elastic roll is formed with spiral fins symmetrically with respect to a substantially central portion in the axial direction as a boundary. 6. A plurality of elastic rolls around which a belt member is stretched, wherein the boundary portions of two spiral groups adjacent to each other correspond to different positions in the width direction of the belt member. The belt conveyor described. 7. An elastic roll having a maximum contact angle with the belt member among a plurality of elastic rolls around which a belt member is wound is provided with a boundary portion of a spiral group at a substantially central portion in the axial direction thereof. The belt conveyor according to claim 6, wherein