JP3049345B2 - Paper curl correction 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 apparatus for correcting a curl generated in a copy in an image forming apparatus such as an electronic copying machine, and more particularly, to a method in which a sheet is pressed against a metal roller member using a film member. And a device for correcting curl by adjusting the angle at which the paper slides.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic system such as an electrocopier, a toner image formed on a photosensitive drum is transferred onto a sheet, and the sheet carrying the toner image is fixed through a fixing device. And means for discharging as a copy. Further, a post-processing device such as a sorter is arranged for the image forming apparatus, and the copies are sorted and stored in a tray of the sorter so that post-processing of the copy can be easily performed. . In the image forming apparatus as described above, as a general fixing device, a device configured as a heating roller type device is often used. In the fixing device, a heating roller that contacts a toner image bearing surface of a sheet is used. And a pressure roller that presses the back surface of the sheet toward the heating roller is used.

A copy fixed through the above-described heating roller type fixing device generally has a tendency to curve toward the side corresponding to the heating roller, and is discharged in a state where curl occurs in the sheet conveyance direction. Often. However, even with ordinary copy paper, the direction of curl generated in a copy (hereinafter, referred to as paper) may differ depending on the water content of the paper, and the direction of curl generated on the paper may vary depending on the paper quality and the like. . If the sheets are curled when storing the sheets in a sorter or the like, an obstacle may occur when the sheets are transported, or the number of sheets stored in the sorter tray may decrease. The problem occurs.

In order to solve the problem of paper curl as described above, for example, as shown in Japanese Patent Application Laid-Open No. 1-261162, a large-diameter soft roller and a small-diameter hard roller are used in combination. The curl is corrected by adding a function of bending the sheet between the rollers. Further, in addition to the curl correcting mechanism using the two rollers, a device combining a belt member and a metal roller has been conventionally used as disclosed in, for example, Japanese Patent Application Laid-Open No. Sho 60-31464. By incorporating the above-described curl correcting mechanism in the copy discharge path of the electronic copying machine, the curl generated in the copy when passing through the fixing device is corrected so that the post-processing is not hindered. Can be.

[0005]

Problems to be Solved by the Invention
As shown in Japanese Patent Application Publication No. 162/162, for example, in a curl correcting device provided with a combination of a driving roller member formed of an elastic roller and a metal roller, as shown in FIG. The curl correction device 1 is configured so that the roll 3 is strongly pressed and deformed while the metal roll 3 bites into the rubber roller 2. Then, the paper P is strongly curved in accordance with the nip shape at the nip portion of both rollers,
The curl correction is performed. However, in the conventional apparatus, in order to obtain a nip shape required for forcing a curled paper, it is necessary to apply a strong nip force between the two rollers. It is required to use a sponge-like rubber material having a low hardness.

For example, according to an experiment on the conventional example, according to an experiment, an elastic roller used as a driving roller has
When a 0 ° roller is used and a metal roller having a diameter of 6 mm is combined, a nip force of 6 kgf is required. For this reason, the frictional load of the drive shaft that supports the elastic roller and the bearing that respectively supports the metal roller increases, and an extra driving torque is required when the action of crushing the elastic roller is added. When using the elastic roller, 1 kgf
Since a driving torque of at least cm is required, it is necessary to configure a driving mechanism for the curl correcting device as having high performance.

Therefore, when using the curl correcting device having the above-described configuration, it is necessary to use a large-capacity drive motor and the like, and there are conditions such as using a thick roller shaft. Therefore, there is a problem that the curl correcting device becomes large. Further, in the curl correcting apparatus having the above-described configuration, the curl correcting performance varies depending on the thickness of the sheet. However, if a fixed nip pressure is set, the curl correcting apparatus is used as it is. Therefore, for example, even when it is not necessary to perform a curl correcting operation on thick paper, when the paper is passed through the curl correcting device, it is necessary to perform the curl correcting operation while applying a constant nip pressure. In addition, there arises a problem that an extra load is applied to the curl correcting device or the paper is curled in the opposite direction.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems of the conventional curl correcting device, to simplify the structure of the curl correcting device, and to improve the curl correcting effect in accordance with the paper thickness. It is another object of the present invention to provide a device which can be performed at a low driving load.

[0009]

According to the present invention, a plurality of elastic rollers are mounted on a drive shaft at a predetermined interval, and a rigid roller is disposed so as to face the elastic roller. The present invention relates to a sheet curl correcting device that performs conveyance while nipping a sheet between the sheets and corrects the curl of the sheet. The invention according to claim 1 of the present invention provides a paper guide having elasticity for contacting the rigid roller and guiding the paper passing through a nip between the elastic roller and the rigid roller toward the rigid roller; A pressing member for applying a pressing force between the guide and the rigid roller is provided.

According to a second aspect of the present invention, there is provided a swingable paper guide which contacts the rigid roller and guides the paper passing through a nip portion between the elastic roller and the rigid roller toward the rigid roller. A pressing member for applying a pressing force between a paper guide and the rigid roller is provided.

According to a third aspect of the present invention, there is provided a film member having elasticity for contacting the rigid roller and guiding a sheet passing through a nip between the elastic roller and the rigid roller toward the rigid roller; A member is wound around the rigid roller at a predetermined angle, and tension applying means for applying tension to the film member is provided.

As described above, in the apparatus of the present invention, a means for performing a curl correcting operation on a sheet by passing the sheet between a metal roll as a rigid roller and a sheet-like guide member or a film member is provided. Thereby, the drive mechanism of the device can be simplified. And since it is not necessary to perform the action of crushing the rubber roller as the elastic roller as in the case of the conventional curl correcting device,
The curl correcting action on the paper can be satisfactorily exhibited without requiring an extra driving force. Further, in the apparatus of the present invention, the force for pressing the sheet-shaped guide member against the metal roll and the angle at which the sheet contacts the metal roll can be appropriately regulated. Further, in the present invention, when a mechanism for pressing the film member against the metal roll by a spring is provided, the curl correction performance of the paper can be adjusted to an arbitrary strength, and other members can be adjusted. It does not affect the strength. Therefore, by providing the above-described mechanism, the apparatus can be configured to be small without imposing a particularly large load on the drive roller.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A paper curl correcting apparatus according to the present invention will be described with reference to the illustrated example. As shown in FIG. 1, a curl correcting device 10 of the present invention is disposed between a paper path 6 connected to a fixing device 5 and a discharge path 8, and includes an elastic roller 11 and a metal roll 13. Are provided facing each other. The roll member constituting the curl correcting device 10 includes:
As shown in FIG. 2, the roller members 11a, 11b,... Are skewered at a predetermined distance from the drive shaft 12 with respect to a metal roll 13 composed of a long metal rod.
Is provided. Then, by driving the drive shaft 12 of the elastic roller 11,
The roller member 11a, 11b,... Of the elastic roller 11 drives the metal roll 13 in contact with the roller member 11 so that the sheet is conveyed between the two rollers.

In the curl correcting device 10, the second
The sheet-like guide 15 is arranged in a state where the leading end portion enters the nip portion of one roll member. As shown in FIG. 1, the sheet guide member 15 fixes the base 16 to the upper guide plate 8a of the discharge path 8 and presses the metal roller by using the elasticity of the sheet member. Is composed. In addition, the sheet-like guide 15
As shown in FIG. 2, the distal end of the sheet-shaped guide is formed in a strip shape, and the strip-shaped protrusions 15a, 1
5b are inserted between the roller members 11a, 11b, and the protruding portions 15a, 15b are pressed against the metal roll 13 or are held in a state in which a gap is slightly formed.

In a state where the sheet discharged from the fixing device 5 and conveyed in the sheet path 6 is nipped between the elastic roll 11 and the metal roll 13, the conveying operation and the curl correcting operation are performed. It is performed in the same manner as in the case of the conventional curl correcting device. In addition to the curl correcting action between the two rolls, in the curl correcting device of the present invention, when the paper is passed between the sheet-like guide member 15 and the metal roll 13, the paper is A pressing action is applied to the metal roll 13. Then, the sheet is pressed against the metal roll 13 by the guide member 15 so that the sheet is curved with a small curvature, thereby performing a curl correcting operation. In the curl correcting device of the present invention configured as described above, a force that bends with a small radius of curvature acts on the sheet passing through the curl correcting device 10 along the surface of the small-diameter metal roll, An operation of correcting the upward curl of the sheet is performed.

As shown in FIG. 1, the sheet-shaped guide 15 of the present invention is bent from the base fixed to the upper guide plate of the discharge path 8 to the leading end between the rollers. In addition to the protrusion, an arrangement relationship as shown in FIG. 3 can be set. In the example shown in FIG. 3, it is assumed that the upper guide plate 8a of the discharge path 8 is arranged to be inclined, and the sheet-shaped guide 15 is extended linearly from the base 16 attached to the upper guide plate 8a. Can be configured. The leading end of the sheet-shaped guide 15 is disposed so as to set a predetermined gap S with respect to the metal roll 13, and the gap S is 0 to 3 mm.
Can be set to Then, by passing the sheet between the metal roll and the sheet guide 15, the sheet is pressed toward the metal roll by the elasticity of the sheet guide, and the sheet is formed with a small radius of curvature along the periphery of the metal roll. A curving force acts to correct the curl.

As the curl correcting device of the present invention, in addition to using the sheet-like guide 15 as shown in FIG. 3, a plate member 20 can be used as shown in FIG. In the example shown in FIG. 4, a plate member made of plastic or the like or a plate member 20 having elasticity is used.
To the nip. Then, as in the case of FIG. 2, the tip is pressed against the metal roller member 13 in a state where the tip is inserted between the roller members.

The plate member 20 has a shaft support 22 at a predetermined position and a spring 23 at a rear end thereof. The spring 23 presses the front end 21 against a metal roller. The force for pressing the distal end portion 21 of the plate member 20 against the metal roller 13 can be set to 50 gf to 1 kgf, but is preferably 200 to 300 gf.
f can be set. That is, the pressing force is 50 gf
If it is less than the above, it is difficult to exhibit the effect of correcting the curl, and if the pressing force is set to 1 kgf or more, there is a problem that a paper jam is likely to occur. Therefore, when the pressing force is set to 200 to 300 gf, as shown in a graph of FIG.
The effect of curl correction can be exerted even on plain paper and relatively thin paper.

When the curl of the sheet is corrected by using the curl correcting device 10, the angle θ at which the sheet guide 15 contacts the metal roll 13 is set for the thin paper P as shown in FIG. The thin paper P is pressed against the metal roll 13 between the points t1 and t2. Then, in a state where a bending action corresponding to the curvature of the metal roll is applied as a force for bending the sheet downward, an action of correcting the curl of the sheet is performed. In the example shown in FIG. 5, the curl correction performance can be defined by arbitrarily adjusting the angle θ at which the sheet guide 15 is brought into contact with the metal roll 13.

As shown in FIG. 6, when the thick paper Pa is passed, the sheet guide 15 is separated from the metal roll according to the stiffness of the paper. Therefore, as shown in FIG. 6, the radius of curvature of the sheet becomes larger than the radius of curvature of the metal roller member 13 due to the stiffness of the sheet. On the other hand, the angle θ1 from the point t1 to t2
Therefore, the curl correcting action on the thick paper Pa is not greatly added. As shown in FIGS. 5 and 6, in the curl correcting device of the present invention, the elasticity of the sheet-shaped guide 15 or the force of the spring 23 disposed on the pressing plate member 20 is appropriately set. It can correspond to the thickness of the paper and the like, and the curl correction performance can be specified to an arbitrary value.

In the curl correcting device as described above,
The relationship between the curl of the sheet and the winding angle with respect to the metal roller and the relationship between the diameter of the metal roller are set based on the experimental values shown in the graph of FIG. In the graph of FIG. 7, the vertical axis represents the height of the residual curl of the paper (mm).
And the horizontal axis sets the winding angle θ of the sheet around the metal roller. In the graph, the case where the curl height is 60 mm is shown, the curve A1 is the case where the diameter of the metal roller is 20 mm, and the curves A2 to A5 are
The case where the diameter d of the metal roller is 10 mm, 8 mm, 6 mm, and 4 mm is shown.

As can be seen from the above graph, in the curl correcting apparatus of the present invention, if the angle θ at which the sheet comes into contact with the metal roller is set to 20 to 60 °, the curl correcting action can be relatively well exhibited. It can be seen that when the diameter of the metal roller is 4 mm to 10 mm, a good curling correction effect can be exhibited. However, even when the diameter of the metal roller is 4 mm or less, it falls within the allowable range for curl correction, and even within the range of 10 mm to 20 mm, the allowable range may be reduced to the allowable range. Therefore, in the present invention, it is considered that the diameter of the metal roller is appropriately set in a range of 3 to 14 mm, and the angle θ at which the paper is wound around the roller can be set to 20 to 60 °.

(Another embodiment of the curl correcting device) In the curl correcting device 10 shown in the above embodiment, the sheet guide 15 or the pressing plate member 20 is arranged between the roller members of the elastic roller 11. In the present invention, as shown in FIGS. 8 and 9, the film member 2 is provided with a tension by a spring.
5 can be used. As shown in FIG. 8, the film member is provided with means for fixing the base 26 to the upper guide plate 8a of the discharge path 8 and applying tension by a spring 27 at the upstream part. Then, the paper discharged from the fixing device 5 and moving in the paper transport path 6 passes between the film member 25 and the metal roll 13, and is transported by the film member 25 while pressing the paper against the metal roll 13. To perform the action. Then, a force that bends the sheet passing through the curl correcting device with a small radius of curvature along the metal roll 13 acts to perform the curl correcting operation.

In the curl correcting device 10,
As shown in FIG. 9, when performing the curl correcting operation on the sheet, the elastic roller 11 is driven, and the roller members 11a, 11b,... Then, for the sheet passing through the curl correcting device 10, along the surface of the small-diameter metal roll,
A force that bends with a small radius of curvature acts to correct the upward curl of the sheet.

Further, in the curl correcting device 10, as shown in FIG. 10, the angle θ at which the film member 25 contacts the metal roll 13 is set for the thin paper P. Point t1 for roll 13
And the action of pressing between t2 is added. Then, in a state where a bending action corresponding to the curvature of the metal roll is applied as a force for bending the sheet downward, an action of correcting the curl of the sheet is performed. Further, in the example shown in FIG. 10, the curl correction performance can be defined by arbitrarily adjusting the angle θ at which the film member 25 comes into contact with the metal roll 13.

On the other hand, in the case of the thick paper Pa, as in the example occupied in FIG. 6, the film member 15 is separated from the metal roll in accordance with the stiffness of the paper. Becomes Therefore, the radius of curvature at which the paper is curved becomes large, a very small wrapping angle is set for the thick paper, and the pressing force of the film member against the metal roller is not set to be large. It will not be added. FIG. 10
As shown in FIG.
By appropriately setting the force of the spring 27 disposed with respect to the sheet No. 5, it is possible to correspond to the thickness of the paper and the like, and the curl correcting performance can be specified to an arbitrary value.

In the curl correcting device 10 of the present invention configured as described above, the roller members 11a, 11b,... Of the elastic roller 11 are replaced by rubber rollers used as a conveying roller device of an ordinary electronic copying machine or the like. And the diameter is larger than that of the metal roll. In the embodiment of the present invention, since an action of strongly pressing the elastic roller against the metal roll is not added, a material having high hardness can be used for the rubber roller member constituting the elastic roller.

The metal roll 13 is made of a round rod-shaped member such as iron, and can have a diameter of about 3 to 14 mm. Further, as the film member 25 shown in FIG. 8, a plastic sheet member or the like having relatively high tension can be used.
Use a film or the like. Then, the coefficient of friction between the metal roll 13 and the film member 25 becomes a small value of about 0.1 to 0.2, and the resistance between the two members is small. The effect is also very small.

(Case of Curling Correction Mechanism Combined with Curling Correction Device) In the example shown in FIG. 11, two curl correction devices configured as described above are combined and arranged on the paper transport path, and curl correction is performed. The case where the mechanism 30 is configured is shown. The curl correcting mechanism 30 shown in FIG. 11 can be arranged at an arbitrary position on the paper transport path, and is provided between the transport roller devices 31 and 48 via a branch gate 32 via two paper paths 35. , 36,
For each paper path 35, 36, the upper curl correcting device 40
And the lower curl correcting device 40a.

The two curl correcting devices are the same as those shown in FIG.
In this configuration, two elastic members and a metal roll are opposed to each other. In the upper curl correcting device 40,
The upper elastic roller 41 and the lower metal roll 42 are provided to face each other with the paper path therebetween, and the film member 45 is pressed against the metal roll 42.

The downstream end of the film member 45 is fixed, and a spring 46 is disposed at the upstream end to apply tension. Further, in the upper curl correcting device 40, the metal roll 42 is
And the arm 43 is supported by a spring 44
Is provided so that the force for pressing the metal roll 42 against the elastic roller 41 can be adjusted. In contrast to the upper curl correcting device 40, in the lower curl correcting device 40a, the respective components are arranged symmetrically up and down via a branch gate 32 of the paper transport path, and a metal roll 42a is provided on an upper portion and an elastic member is provided on a lower portion. The rollers 41a are arranged respectively. In the two curl correcting devices 40 and 40a, the upper curl correcting device 40 has an operation of curving the sheet downward with a small radius of curvature in order to correct the upward curl of the sheet (the state where the curved concave surface faces upward). By doing so, a curl correcting action is performed. Further, the lower curl correcting device 40a performs an operation of correcting a downward curl (a state in which a curved concave surface faces downward).

In the curl correcting mechanism 30 configured as described above, the sheet guided to the curl correcting mechanism by the transport roller device 31 is branched by the branch gate 32 toward the upper and lower paper paths 35 and 36. . For example, when the sheet has an upward curl, the sheet is guided to the upper sheet path 35, and the curl correcting operation is performed by the upper curl correcting device 40. If the sheet is curled downward, the sheet is guided to the lower sheet path 36, and the curl correcting action is given by the lower curl correcting device 40a. The curl correcting mechanism 30 can be provided, for example, corresponding to a copy discharge unit of a fixing device. Then, the sheet that has passed through one of the two curl correcting devices is, with its curl removed,
The sheet is conveyed by the conveying roller device 48 to the next step.

It is necessary that the above-described bending action on the sheet is performed in the plastic deformation area of the sheet as shown in the graph of FIG. That is, by generating the distortion ε1 or ε2 remaining on the paper,
It is necessary to set the diameter of the metal roll of the curl correcting device and the pressing range by the film member so that the curl can be corrected.

In the present invention, a pressing force is applied to the metal roll by a film member toward the metal roll, and the paper is directed toward the curved surface of the metal roll, and a predetermined angle is applied to the paper other than the thick paper. By applying the pressing action, the curl of the sheet can be eliminated. Therefore, for a copy curled through the fixing device,
By providing the curl correcting function of the curl correcting device, it is possible to prevent the occurrence of a jam due to the curl of the sheet and other troubles in the post-processing. The curl correcting device of the present invention can be provided at any position on the conveyance path of the single-sided copied paper in an automatic duplex copying machine, in addition to being provided between the fixing device and the post-processing device. is there.

[0035]

Since the paper curl correcting device of the present invention is constructed as described above, the structure of the paper guiding member in the curl correcting member can be simplified, and the paper guiding action can be improved. Can be performed well. Also,
As described above, the paper is passed between the metal roll and the sheet-shaped guide or other pressing member to constitute the means for performing the curl correcting operation, thereby crushing the rubber roller as in the case of the conventional curl correcting device. Since there is no need to perform the operation, no extra driving force is required, and the driving mechanism can be simplified. Furthermore, the curl correcting device of the present invention can adjust the curl correcting performance of the paper to an arbitrary strength when pressing the sheet-like guide or the like against the metal roll, which affects the strength of other members. Has no effect. Then, the apparatus can be configured to be small without applying a particularly large load to the drive roller.

Also, as in the curl correcting mechanism of the present invention,
In a case where a means for vertically arranging two opposite curls is provided via a branch gate, even if the paper introduced into the curl correcting apparatus has a curl in the opposite direction, the curl is not applied to the paper. The curl correcting action can be performed favorably. Then, the curled paper is
Since the leading end can be guided in the direction of curl by the gate member, the paper can be moved along the upper and lower paper paths, and the function of automatically eliminating the curl of each paper can be achieved. Can be granted. Further, the curl correcting device of the present invention does not require a drive mechanism or the like provided in a portion for guiding a sheet, so that the mechanism of the device can be simplified.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a curl correcting device of the present invention.

FIG. 2 is a perspective view of the curl correcting device of the present invention.

FIG. 3 is an explanatory view of another embodiment of the curl correcting device of the present invention.

FIG. 4 is an explanatory view of another embodiment of the curl correcting device of the present invention.

FIG. 5 is an explanatory diagram showing the effect of curl correction on thin paper.

FIG. 6 is an explanatory diagram of an action on thick paper.

FIG. 7 is a graph showing a relationship between a diameter of a metal roller and a winding angle of a sheet.

FIG. 8 is a side view of another embodiment of the present invention.

9 is a perspective view of the curl correcting device shown in FIG.

FIG. 10 is an explanatory diagram of a curl correcting operation in the curl correcting device shown in FIG. 8;

FIG. 11 is a side view showing a configuration of a curl correcting mechanism.

FIG. 12 is a graph showing a deformable range of a sheet.

FIG. 13 is a side view showing a configuration of a conventional curl correcting device.

[Explanation of symbols]

1 curl correcting device, 2 rubber roller, 3
Metal roll, 6 paper transport path, 10 curl correcting device, 11 elastic roller, 13 metal roll,
15 sheet guide, 20 pressing plate, 25
Film member, 27 spring, 30 curl correcting mechanism, 32 branch gate, 35 paper path, 3
6 lower paper path, 40 / 40a curl correcting device,
45 / 45a film member, 48 transport roller device.

Claims (3)

(57) [Claims] 1. A state in which a plurality of elastic rollers are attached to a drive shaft at a predetermined interval, a rigid roller is arranged to face the elastic roller, and a sheet is nipped between the elastic roller and the rigid roller. In the paper curl correcting device for correcting the curl of the paper by transporting the paper, the elastic roller which contacts the rigid roller and guides the paper passing through the nip between the elastic roller and the rigid roller toward the rigid roller. And a pressing member for applying a pressing force between the paper guide and the rigid roller. 2. A method according to claim 1, wherein a plurality of elastic rollers are attached to the drive shaft at predetermined intervals, and a rigid roller is disposed to face the elastic roller, and a sheet is nipped between the elastic roller and the rigid roller. In a paper curl correction device for performing conveyance and correcting paper curl, a rocking device that contacts the rigid roller and guides the paper passing through a nip between the elastic roller and the rigid roller toward the rigid roller. A paper curl correcting device, comprising: a paper guide that can be used; and a pressing member that applies a pressing force between the paper guide and the rigid roller. 3. A method in which a plurality of elastic rollers are attached to a drive shaft at predetermined intervals, a rigid roller is disposed opposite to the elastic roller, and a sheet is nipped between the elastic roller and the rigid roller. In the paper curl correcting device for performing the conveyance and correcting the curl of the paper, the elasticity that guides the paper, which comes into contact with the rigid roller and passes through the nip portion between the elastic roller and the rigid roller, toward the rigid roller, A curl correction device for a paper, comprising: a film member having the film member; and a tension applying means for applying a tension to the film member while winding the film member around the rigid roller at a predetermined angle.