JPH06115791A - Curl reduction device for paper sheet - Google Patents

Abstract

PURPOSE:To carry out curl correction work in an image forming device such as an electronic copying machine, by disposing a curl correction device for a copy which is discharged from a fixing device, and coping with the feed direction, the sort of paper sheet, image density and the like at the time of correcting a curl generated in the paper sheet. CONSTITUTION:This curl correction device 1 is constituted of a means which presses a pressure roll 5 to a belt 2, and curl correction is carried out by applying sudden bending effect to a paper sheet which runs through between both the members. A mechanism which adjusts a pressure amount through a cam driven member 7 with a cam member 10 is mounted on the pressure roll 5, and the rotational angle of the cam member 10 is controlled based on information, such as the feed direction, size, sort of the paper sheet, and image density to set the pressure amount of the pressure roll to the belt, thus exhibiting a control action to the paper sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reducing the curl generated in a copy made by an image forming apparatus such as an electronic copying machine, and more particularly, it presses a roll member having a small diameter against a belt to form a sheet. Curl is reduced by adding the action of forcibly bending the curl in the opposite direction.
The present invention relates to a device that can control the curl reduction operation according to the type of paper and the like.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic system such as an electronic copying machine, when making a copy, a sheet carrying a toner image is fixed through a fixing device under heat and pressure. The method is used. When a copy is made using the above-described method, a large curl may occur depending on the density of the toner image carried on the sheet, the type of the sheet, the thickness of the sheet, and the like. Then, when the curled copy is directly discharged to the normal discharge tray, the paper may be caught by another member in the paper path, and the paper may be jammed. Further, even when a post-processing device such as a sorter is provided in the discharge section of the image forming apparatus, if the paper is curled, the number of copies that can be stored in the tray of the sorter is reduced or the storage property of the copy is deteriorated. As a result, problems such as the above occur, and special post-processing such as binding work becomes difficult. Furthermore, in an apparatus such as an automatic double-sided copying machine, when a single-sided copy sheet is sent for copying on the back side, a paper jam may occur in the middle of the conveyance path or the paper may not be correctly stored in the intermediate tray and Problems such as trouble in the copying of are likely to occur.

Therefore, in order to eliminate the curl of the paper as described above, for example, as shown in Japanese Utility Model Laid-Open No. 2-97352, a one-side copied paper is sent in the middle of the paper path toward the intermediate tray. It has been proposed to arrange a curl removal device. In the above-described conventional curl removing device, the paper path is sharply curved, and a small-diameter metal roller and a large-diameter elastic roller are arranged to face each other at the curved portion, and the paper is sharply curved between both rollers. The action and the action of sliding the curved portion of the guide plate are added. By arranging two sets of the above-mentioned curl removing means and applying the action of curving the paper in the opposite directions, the curl of the one-side copied paper can be corrected.

In addition to the above-mentioned conventional example, as a means for removing the curl generated in the copy, for example, a curl correcting device as disclosed in JP-A-60-31464 may be used. . In the curl correcting device, the pressing roll is arranged on the belt for conveying the copy, the curved portion is formed on the belt pressed by the pressing roll, and the paper passing through the curved portion is forcibly curved. Is added to act to remove the curl. In addition, the pressure roll is held at a fixed position or is configured to be rotatable, and the pressure roll is pressed toward the belt against the end of the curled paper discharged from the fixing device, and the pressure roll is rapidly pressed against the paper. The curl can be corrected by adding a bending effect.

[0005]

In the curl correcting device constructed as described above, a mechanism for adjusting the pressing amount of the pressing roll is provided in accordance with the information on the thickness of the paper. The curl correction amount is adjusted by inputting the detection information of the thickness of the paper such as plain paper to the control device. However, in a copy made by a general image forming apparatus, the curl generated on the paper has a characteristic that it changes depending on the image density, the direction in which the paper is conveyed, or the conditions such as the image density and the paper size. However, in the curl correcting device in which the belt and the pressing roll are combined, since only the information on the thickness of the paper is used, it is not possible to correspond to the state of curl actually occurring in the paper, and the curl correcting device can be used. There is a problem that curl remains on the paper even after passing through.

Further, in a general electrophotographic copying machine, in addition to plain paper, paper thicker than a postcard is used, or OHP is used.
There are cases where a film for use is used. However,
In the case of such cardboard or film, there is almost no curl and it is not necessary to activate the curl correction device. In particular, in the case of an OHP film, in a state where it has heat immediately after it is discharged from the fixing device, when it is passed through the curl correcting device and a curving action is given, an extra curving state occurs in that direction. There are also problems. Further, the curl generated in the copy is related to the size of the paper and the conveyance direction such as the vertical and horizontal directions of the paper, but the conventional curl correcting device does not take such a condition into consideration. However, there is also a problem that it is not possible to sufficiently cope with the curl that occurs in copying.

[0007]

It is an object of the present invention to solve the above-mentioned drawbacks of the conventional curl correcting device, and to curl in accordance with information such as paper quality and thickness, image density, or paper feeding direction. It is an object of the present invention to provide a device capable of controlling a correction amount.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a device for correcting a curl by applying an action of sharply curving a curled sheet in a direction opposite to the curl direction. In the curl correcting device of the present invention, the belt driven in the moving direction of the paper and the pressing roll pressed by the pressing force against the belt are arranged, and the guiding means for arranging the belt at a short interval is used. A supporting mechanism is provided, a pressing force adjusting means by a cam device is provided for the pressing roll, and the pressing force adjusting means is operated by a signal from the control device. Then, with respect to the control device attached to the pressing force adjusting means, information about the type of paper, image density, paper size,
Further, it is possible to input information such as the paper feed direction and control the curl correction amount for the paper based on the control information input to the control device. Further, in the device of the present invention, for a strong paper or sheet, a mode in which the curl reducing action is not exhibited is set, and information such as a plastic film or special thick paper is input to the control device. In this case, it is possible to configure a mechanism for performing control so that the pressing roll is not pressed against the belt.

As described above, the curl correcting device of the present invention is arranged so that the belt and the pressing roll are opposed to each other, and the degree to which the belt is bent by the pressing roll can be adjusted, so that the curl generated on the paper can be prevented. The curl can be corrected according to the degree. Further, the curl correcting device of the present invention can use information such as the paper size, the direction in which the paper is conveyed, the thickness of the paper, and the image density as the control information input to the control device. The amount of curl correction due to can be appropriately adjusted according to the properties of the paper. Further, in the present invention, a control mode for not operating the curl correction device can be set for the plastic film, so that it is possible to correspond to the operation of making a copy using the OHP film. it can.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sheet curl reducing apparatus of the present invention will be described with reference to the illustrated example. As shown in FIG. 1, the curl correcting device 1 of the present invention presses a pressing roll 5 against a belt 2 to rapidly bend the belt 2,
Means is used to allow the paper to pass between the two members. The belt 2 is supported by a drive shaft 3 and a support shaft 4 which are arranged at a narrow interval, and the pressing roller 5 presses the intermediate portion of the belt 2. The pressing roll 5
A cam follower member 7 is provided at the end of the link member 6 that supports the cam follower member 7, and a pressing mechanism by a cam member 10 is provided for the cam follower member 7. Further, the pressing roll 5 is provided so as to project to the top of the cover member 8 formed in a substantially mountain shape, and curls the paper conveyed in the arrow X direction through between the belt 2 and the cover member 8. It is guided to the nip portion of the correction device 1 so that the curl removing action is performed. In the curl correcting device of the present invention configured as described above, the cam member 10 is rotated by driving the shaft 11, and the amount of protrusion of the pressing roll 5 toward the belt 2 is adjusted by the cam member. By doing so, the degree of curvature of the belt can be set.

The curl correcting device 1 is constructed as shown in the perspective view of FIG. 2 and the side view of FIG. 1, in which the large-diameter drive shaft 3 and the small-diameter support shaft 4 rotate for a long time. The shaft member is used. The two shafts use support shafts having a thickness of about ½ of the drive shaft, and a large number of narrow belts are arranged parallel to each other. ...... are simultaneously driven in the same direction. In the curl correcting device of the present invention, the image bearing surface of the paper is set on the side corresponding to the belt 2, and the back surface of the paper is pressed by the pressing roll 5 to
The paper is configured to be bent sharply.

The pressing roll 5 pressed against the belt 2
Is a long rod-shaped member having a small diameter, and has a diameter about half that of the support shaft 4, and both ends of the pressing roll 5 are supported by bearing members of the link members 6 and 6a for rotation. It is possible. Further, the link members 6b ... Are arranged at arbitrary positions with respect to the pressing roll 5, and are supported in a state of being pressed toward the belt via the shaft supporting portion having the concave surface of the intermediate portion of the pressing roll. Each of the link members has a cam driven member 7, 7a, 7b at its end.
The cam member 1 for each cam follower member.
0, 10a, 10b ... are arranged respectively. By driving the cam shaft 11, the cam member adjusts the amount of movement of the pressing roll 5 via the cam follower member 7 so that the degree to which the belt is bent can be arbitrarily adjusted.

By changing the rotation angle of the cam member 10,
In order to adjust the effect of correcting the curl on the paper, it is possible to use means for adjusting the rotation angle of the cam member as shown in FIG. In the device shown in FIG. 3,
A plurality of claw members 14, 14a, 14b are provided around the indexing disk 13 provided on the cam shaft 11, and an engaging claw operated by a solenoid 15 is provided for the indexing disk 13. The locking means provided with 16 is arranged. Further, the claw member provided on the index disc 13 is set according to the distance that the pressing roll 5 presses the belt, and the claw member provided on the index disc 13 is set by the engaging claw 16. The amount of pressing can be set arbitrarily at the locked position. In the curl correcting device 1 shown in FIG. 3, the motor 12 drives the cam shaft 11 to stop the cam member 10 at a position where the specified pressing amount is reached, and the pressing roll 5 is pressed.
It is possible to regulate the pressing amount of the belt. For driving the motor, paper information input to the control device 20 can be used. By processing the paper information as will be described later, it is optimal for copying. It is possible to add a curl correcting effect.

The image forming apparatus equipped with the curl correcting device 1 is provided with a means for inputting the information on the quality of the paper accommodated in the paper feed tray or the like to the control device through, for example, the control panel, or the photosensitive device. A means for estimating the curl state of the sheet can be used by using the density detection information of the toner image formed on the body drum.
Then, as will be described later, the state of the curl that occurs on the paper is estimated according to the information such as the paper size, the paper quality, the paper feeding direction, and the image density, and the optimum pressing amount for the curl correction is set. The amount of pressing by the pressing roll can be set by rotating the member. Further, in the curl correction device shown in FIG. 3, three claw members are arranged on the indexing disc 13 provided on the shaft of the cam member, but the pressing amount is set more finely. When trying to do so, it goes without saying that the pressing amount can be arbitrarily set by disposing a large number of claw members.

However, in the case of general thick paper, since the copy does not greatly curl, it is often unnecessary to add a curl correcting action to a copy using relatively thick paper. On the other hand, when an image with a high density is transferred onto a relatively thin paper, a relatively large curl tends to occur. Especially, in the case of a color copy, the image density is very high. Therefore, there is a problem in that the curl largely occurs. Therefore, it can be seen that it is effective to use the curl correcting device of the present invention for a copy having a large image density as described above.

Further, in the curl correcting device of the present invention, the information on the type of the paper loaded in the paper feeding section is input through the control panel or the image density of the image formed on the photosensitive drum is changed. The information is used so that a means for adjusting the pressing amount of the pressing roll against the belt can be used. However, as described above, when it is troublesome for the operator to input the information of the paper by using the set button etc. of the control panel,
It is also possible to preset the numerical value of the basic pressing amount according to the type of paper most frequently used in the electronic copying machine. Further, when the electronic copying machine is a color copying machine, the pressing amount can be set corresponding to the curl amount generated in a general color copy.
In addition to the operation of setting the pressing amount, it is also possible to set the pressing amount in a plurality of stages in advance by limiting the two modes of monochrome and color and the case of manually feeding thin paper.

(Information Input to Control Device) In contrast to the curl correction device shown in FIG. 3, the control device 20 is used.
Can be arranged, and the amount of pressing of the pressing roll 5 can be controlled according to the program set in the control device by using the information on the property of the paper input to the control device 20. As shown in the flowchart of FIG. 4, the control device 20 can input information about a sheet and set the pressing amount (correction amount) of the pressing roll with respect to the belt. As shown in the flow chart shown in FIG. 4, the first information to be input is information on the type of paper (a-1) (thin paper, plain paper, thick paper, etc.) and image density information on a-2. In accordance with such information, the control device determines the basic curl correction amount in step b-1 with reference to an A4 size sheet in accordance with a preset program.

In the step b-1, the curl correction amount can be set by the curl correction device with reference to the lateral feed state of A4 size paper, and among various kinds of output information. The type of paper can be set by the operator by pressing the set button provided on the control panel, but in addition to this, information from the paper thickness detection device arranged in the paper transport path can also be used. . Further, as the image density information of a-2, information of image density from the image forming apparatus of the copying machine can be used.

Next, in a-3, the paper size information is input to the control device, and the steps of b-2 and b-3 are performed to set the curl correction amount corresponding to the paper size. In that case, the standard size paper (A5, A3, B4, B
With reference to the control information for (5, etc.), the correction coefficient can be set according to the input information of the paper. If the input paper size information is A4 size, the processing operation in b-2 and 3 is not required, and the process proceeds to the next step b-4. And
In the step b-4, the feeding direction of the paper a-4 (vertical,
Lateral feed information) is input to set the correction strength corresponding to the paper feed direction, and the correction amount in step b-5 is set. In step b-4, for example,
In the case of vertical feeding of A4 size paper in the first control step, if the information of a-4 is vertical feeding of A4 size paper, it is not necessary to perform the signal processing operation and b- The signal of the correction amount in step 5 is output.

In addition to performing the control shown in the flow chart of FIG. 4, in the present invention, as shown in the flow chart of FIG. 5, a mode in which the curl correction operation is not performed on the OHP film Can be controlled. In the flow chart of FIG. 5, in step c-1, information as to whether to use paper or film is input to the control device. When the copy target is paper, the curl correction amount is set in step c-2 according to the image density information and the like as shown in the flowchart of FIG. On the other hand, when the object to be used for copying is an OHP film, the curl correcting device is set in a mode in which the curl is not corrected, and control is performed so that the copy passes through during that time.

As shown in the flow chart of FIG. 5, the control information in step c-2 is to set a mode having a large curl correction effect, or to make the curl correction effect small, or It is said that it is possible to output three types of control information indicating that the curl correction operation is not performed. The operation of processing such information can be made to correspond to the claw member provided on the indexing disk 13 shown in FIG. 3, and is driven by the motor 12 using the indexing disk 13. However, the position where the pawl member is locked and held by the solenoid can be set.
Further, in the curl correcting device of the present invention, as shown in FIG. 3, a large number of locking claw members are arranged on the indexing disk 13 arranged on the cam member 10, When a means for arbitrarily controlling the rotation angle of the cam member 10 is used, it is possible to perform a finer control operation according to a combination of control information such as the type of paper, the feeding direction, and the image density. it can.

[0022]

As described above, in the paper curl reducing device of the present invention, the belt and the pressing roll are arranged so as to face each other to form a curl correcting device, and the degree to which the belt is bent by the pressing roll is adjusted. With this configuration, the amount of curl can be corrected according to the degree of curl generated on the paper. Further, the curl correcting device of the present invention can use information such as the paper size, the direction in which the paper is conveyed, the thickness of the paper, and the image density as the control information input to the control device. The amount of curl correction due to can be appropriately adjusted according to the properties of the paper. Further, in the present invention, a control mode for not operating the curl correction device can be set for the plastic film, so that it is possible to correspond to the operation of making a copy using the OHP film. it can.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of a curl correction device used in a curl reduction device of the present invention.

FIG. 2 is a side view showing the relationship between the belt and the pressing roll of the curl correcting device of the present invention.

FIG. 3 is an explanatory diagram of a case where a mechanism for controlling rotation of a cam member is provided in the curl correction device.

FIG. 4 is a flowchart showing a control operation in the control device of the present invention.

FIG. 5 is a flowchart showing a control operation for an OHP sheet.

[Explanation of symbols]

1 curl correction device, 2 belt, 5 pressing roll, 6 link member, 7 cam driven member,
8 cover member, 10 cam member, 11 cam shaft, 13 disc for indexing, 15 solenoid,
20 Control device.

Claims (2)

[Claims] 1. A curled sheet is subjected to an action of sharply curving in a direction opposite to the curling direction,
In a device for correcting curl, a belt driven in a moving direction of a sheet and a pressure roll pressed by the belt with a constant pressing force are arranged.
A mechanism for supporting the belt by guide means arranged at short intervals is provided, a pressing force adjusting means by a cam device is provided for the pressing roll, and the pressing force adjusting means is operated by a signal from a control device, Information about the type of paper, image density, paper size, paper feed direction, and other information is input to a control device that is attached to the pressing force adjusting means, and the control input to the control device is input. A curl reducing device for a paper, which controls a curl correction amount for the paper based on information. 2. The device is set to a mode that does not exhibit a curl reducing action for strong paper or sheets, and the control device is provided with information such as a plastic film or special cardboard information. 2. The paper curl reducing device according to claim 1, wherein when the pressure is input, control is performed so that the pressing roll is not pressed against the belt.