JP2002308504A - Curl amount correcting device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable device by achieving improvement in both of curl amount correcting efficiency and saving space efficiency without increasing an installation space. SOLUTION: This device is equipped with a pair of rollers 1a for correcting an upper curl, a pair of rollers 1b for correcting a lower curl, an approach path 10 forming a feeding path of a sheet, an air blasting means 15 for blasting air to the sheet, and a control circuit 16 for controlling the air blasting means 15. The approach path 10 diverges to an upper curl correcting path 11a and a lower curl correcting path 11b at a halfway. The upper curl correcting path 11a forms a path for feeding the sheet to the pair of the rollers 1a and the lower curl correcting path 11b forms a path for feeding the sheet to the pair of the rollers 1b. A vent hole 10a is formed on the approach path 10 near a diverging point 12 of the upper curl correcting path 11a and the lower curl correcting path 11b. The air blasting means 15 is disposed so that the air flow by the air blasting means 15 passes the vent hole 10a and the air flow is vertical with respect a sheet surface or the air flow makes an acute angle with a feeding direction. The air flow near the diverging point 12 is controlled so that the sheet is fed to the curl correcting path 11a or the lower curl correcting path 11b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curl amount correcting device for correcting a curl amount of a sheet material and an image forming apparatus such as a copying machine or a printer provided with the same.

[0002]

2. Description of the Related Art Conventionally, in a copying machine, for example, when a sheet material after fixing is curled and there is a problem in stacking a sheet material or passing a sheet through a downstream paper path, or when transferring toner to the sheet material, transfer is performed. For example, when it is desired to curl the sheet material in advance, the curl amount of the sheet material is corrected by using a curl amount correcting unit as shown in FIG. The curl correction means includes a flapper 50, an approach path 60, an upper curl correction path 61a, a lower curl correction path 61b, a pair of rollers 51a, and a pair of rollers 51b.
8, the curl amount of the sheet material 70 that has passed through the fixing device 118 is corrected, and then the sheet material 70 is discharged out of the apparatus through a discharge roller 119.

The curl includes an upper curl in which the sheet material 70 curls upward and a lower curl in which the sheet material 70 curls downward. When both curl amounts are to be corrected, the paper path is moved upward by the operation of the flapper 50. If the curl sheet material is corrected, the upper curl correction path 61a is changed. If the lower curl sheet material is corrected, the lower curl correction path 61b is changed. The curl amount is corrected through the pair of rollers 51a and 51b corresponding to the upper and lower curl amount corrections. It is common to do.

[0004]

However, the curl amount correcting means shown in the above conventional example has the following problems.

The curl amount correcting ability of the roller pair 51a, 51b shown in FIG. 6 is determined by the curvature and the nip amount of the roller. However, there is a limit to the curl amount correcting ability that can be exerted on the structure thereof. In an image forming apparatus such as a remarkable copying machine, the curl amount correcting ability of the roller pair 51a and 51b is insufficient due to an increase in the curl amount due to an increase in the fixing temperature due to an increase in speed and an increase in the sheet passing speed of the sheet material 70. Has been occurring. In order to improve the curl amount correction ability, for example, as shown in FIG.
It is necessary to provide additional means for reducing the curl amount in addition to the roller pairs 51a and 51b, such as reducing the curl amount by cooling the sheet material 70 by the airflow of 5, but it is necessary to secure space for the additional device. In addition, there is a problem that the apparatus is increased in size in order to improve curl amount correction capability.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to improve the curl amount correcting capability and save space without increasing the installation space, and to achieve a highly reliable curl amount correction. It is an object to provide an apparatus and an image forming apparatus.

[0007]

In order to achieve the above object, the present invention provides an upper curl correcting means for correcting upward curl of a sheet material, and correcting a downward curl of the sheet material. Lower curl correction means, guide means for sandwiching the sheet material with a predetermined space therebetween to form a conveyance path, blowing means for blowing air to the sheet material, and control means for controlling the blowing means, The guide means branches in the middle into a first branch guide means and a second branch guide means in two directions,
The first branch guide means forms a path for conveying the sheet material to the upper curl correction means, and the second branch guide means forms a path for conveying the sheet material to the lower curl correction means. The first branch guide means and the second branch guide means Forming an opening in the guide means in the vicinity of the branch point, and arranging the air blowing means so that the airflow from the air blowing means passes through the opening and is perpendicular to the sheet surface or at an acute angle with respect to the conveying direction; The sheet material is conveyed to the first branch guide unit or the second branch guide unit by controlling an airflow near a point.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However,
The dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments should be appropriately changed depending on the configuration of the apparatus to which the present invention is applied and various conditions, and in particular, Unless otherwise described, the scope of the present invention is not intended to be limited to them.

[First Embodiment] A first embodiment of an image forming apparatus provided with a curl amount correcting device to which the present invention is applied will be described in detail with reference to the drawings. FIG. 8 is an operation explanatory diagram of the image forming apparatus according to the first embodiment of the present invention.

Here, as an order of explanation, first, the entire configuration of the image forming apparatus will be described with reference to FIG. 8, and then the configuration of the curl amount correcting means in the image forming apparatus will be described with reference to FIGS. This will be described in detail.

In FIG. 8, reference numeral 1000 denotes a printer, and sheet materials in the upper cassette 100 are separated and fed one by one by the action of a separation claw and a feed roller 101 and guided to a registration roller 106. The sheet material in the lower cassette 102 is removed by the action of the separation claw and the paper feed roller 103.
The sheets are separated and fed one by one and guided to the registration roller 106.

Reference numeral 111 denotes laser modulation (laser scanner); 112, a photosensitive drum; 113, an image writing optical system; 120, a primary charger for charging the photosensitive drum 112 in advance before writing an image; 114, a developing device; And 116, a separation charger, which constitutes an image forming unit.

Reference numeral 117 denotes a conveyance belt for conveying the sheet material on which an image is formed, 118 denotes a fixing device, 119 denotes a discharge roller, and 121 denotes a curl amount correction unit. The sheet material on which the image is formed is fixed by the fixing device 118, the curl is corrected by the curl amount correction unit 121, and then discharged to the sorter 3000 by the discharge roller 119.

Reference numeral 2000 denotes a scanner, 201 denotes a scanning optical system light source, 202 denotes a platen glass, 203 denotes a document pressure plate that opens and closes, 204 denotes a lens, 205 denotes a light receiving element (photoelectric conversion), and 206 denotes an image processing unit.

The original image read by the scanning optical system light source 201 is processed by the image processing unit 206, converted into an electric signal 207, and transmitted to the laser modulation 111.

Next, the configuration and operation of the curl amount correcting means in the image forming apparatus will be described. FIG. 1 is an explanatory view of a main part of a curl amount correcting unit of the image forming apparatus according to the first embodiment of the present invention.

The curl amount correcting means 121 includes a pair of rollers 1a as an upper curl correcting means for correcting the upward curl of the sheet material, and a pair of rollers as a lower curl correcting means for correcting the downward curl of the sheet material. 1b, an approach path 10, which constitutes a guide means for forming a sheet material conveyance path,
Upper curl correction path 11a as branch guide means, second
A lower curl correction path 11b as a branch guide means, and a blowing means 15 for blowing air to the sheet material, and the operation of the blowing means 15 are controlled by a control circuit (control means) 16. The blowing means 15 is a vent (opening) 1 opened so that there is no problem in passing the sheet material 20 through the approach path 10.
Air can be sent through Oa. As shown in the figure, the blower 15 is arranged such that the airflow from the blower 15 passes through the vent 10a and is perpendicular to the sheet surface or at an acute angle to the conveying direction.

Sheet material 20 that has passed through fixing device 118
Curling occurs due to the action of heat and pressure of the fixing device 118. There are two types of curls: an upper curl that curls upward and a lower curl that curls downward. The curl state differs depending on the type of the sheet material 20 and the surrounding environment. The roller pair 1a is provided for correcting upper curl, and the roller pair 1b is provided for correcting lower curl.

The operation for correcting the curl amount of the curled sheet material 20 will be described below.

As shown in FIG. 1, the sheet material 20 extends upward.
When the sheet is curled, the air is blown to the sheet material 20 by the blowing means 15 so as to float the sheet material 20 and guide the sheet material 20 to the upper curl correction path 11a. Lumber 2
The curl amount of 0 is reduced. Here, the sheet material 20
The blowing means 15 blows the sheet material 20 slightly obliquely rather than perpendicularly to the sheet material 20 in order to blow more air onto the sheet material. Sheet material 2
0 indicates a pair of rollers 1a with the curl amount reduced to some extent.
Then, the curl amount is corrected and discharged from the discharge roller 119 to the outside of the apparatus.

As shown in FIG. 2, the sheet material 20 extends downward.
1 is curled, the blowing means 15 attracts the sheet material 20 in the opposite direction of FIG.
The curl amount of the sheet material 20 is reduced by the effect of exhausting the heat of the sheet material 20 while guiding the sheet material 20 to 1b. The curl amount of the sheet material 20 is corrected by the pair of rollers 1b in a state where the curl amount is reduced to some extent, and the sheet material 20 is discharged from the discharge roller 119 to the outside of the apparatus.

In order to properly correct the curl amount, the curl direction and curl amount of the sheet material 20 are detected, and the roller pair 1a,
A curl amount detecting means (not shown) is provided to select which of the pair of rollers 1b to pass the paper, and the blower means 15 is controlled by the control circuit 16 in accordance with the detection signal of the curl amount detecting means to control the sheet material 20. However, in the present embodiment, the curl direction of the sheet material 20 can be predicted according to environmental conditions such as the type, temperature, and humidity of the sheet material 20. Therefore, the curl direction is predicted in advance. By determining the correction direction and controlling the blowing means 15, the curl amount detecting means is abolished, giving priority to space saving.

In this embodiment, the environment detecting means 17 for detecting the temperature and humidity of the surrounding environment, the storage means 18 for storing the type of sheet material, and the information of the environment detecting means 17 and the storage means 18 are used. Calculating means 19 for estimating the curl direction of the sheet material; and controlling the blowing means 15 using the control circuit 16 based on the result of the calculating means 19. This configuration is shown in FIG.
Is shown only in FIG.

In the present embodiment, at least one blowing means 15 is required, but a plurality of blowing means may be provided.

In this embodiment, the blowing means 1
5 was rotated in the normal and reverse directions to change the air flow. However, when the blowing means 15 having different blowing capabilities between the normal rotation and the reverse rotation is used, the air flow is changed in the longitudinal direction (width direction orthogonal to the sheet material conveyance direction). The same operation can be performed by switching the air blowing means 15 that operates as needed, with one acting in the direction of blowing air to the sheet material 20 and the other acting in the direction of attracting the sheet material. is there. This eliminates the necessity of rotating the blower 15 in the normal and reverse directions, thereby preventing the performance from deteriorating. There is also a method in which the blowing direction is only sprayed by arranging the blowing means 15 and 15 'up and down via a transport path as shown in FIG. 3 without disposing the blowing means 15 in the longitudinal direction. Benefits are reduced.

In the present embodiment, the blowing means 1
Reference numeral 5 uses an axial fan, but any means capable of blowing air, such as a sirocco fan or a cross flow fan, may be used.

The curl amount correcting means according to the structure of the present embodiment is most effective when arranged downstream of the fixing device 118, but is used as a curl amount correcting means for improving toner transferability and drum separability, for example. It does not matter.

As described above, according to the present embodiment, the blowing means 15 is connected to the sheet material 20 by the upper curl correction path 11a.
Alternatively, it is possible to provide a high-quality apparatus by improving the curl amount correction ability without increasing the space by switching the sheet conveyance to the lower curl correction path 11b and reducing the curl by cooling the sheet material. it can.

[Second Embodiment] A second embodiment of an image forming apparatus provided with a curl amount correction device to which the present invention is applied will be described in detail with reference to the drawings. FIG. 4 is an explanatory view of a main part of a curl amount correcting unit of the image forming apparatus according to the second embodiment of the present invention.

In the second embodiment, the upper curl correction path 11
a, by moving the branch point 12 of the lower curl correction path 11b upward from the center line 13 to secure the entrance width of the lower curl correction path 11b wider than the entrance width of the upper curl correction path 11a, for example, as shown in FIG. In the case of a sheet material 20 having an upper curl, as shown in FIG. 5, the blowing means 15 blows the air vigorously to lift the sheet material 20 and guide the sheet material 20 to the upper curl correction path 11a, while cooling the sheet material 20 by the blown air. The effect reduces the curl amount of the sheet material 20. The curl amount of the sheet material 20 is corrected by the roller pair 1a in a state where the curl amount is reduced to some extent, and the sheet material 20 is discharged outside the apparatus from the discharge roller 119.

The sheet material 20 having a lower curl as shown in FIG.
In the case of, the sheet material 20 is restrained from rising by weakening the momentum of the air blowing means 15 to guide the sheet material 20 to the lower curl correction path 11b, and the sheet material 20 is cooled by the blowing air so that the sheet material 20 is cooled. Curl amount is reduced. The curl amount of the sheet material 20 is corrected by the pair of rollers 1b in a state where the curl amount is reduced to some extent, and the sheet material 20 is discharged from the discharge roller 119 to the outside of the apparatus.

The second embodiment is particularly effective when the sheet material 20 is apt to curl upward, and only by changing the air volume of the blowing means 15 without using a forward / reverse rotation circuit as in the first embodiment. Therefore, there is also an advantage that the control circuit can be relatively small.

[0033]

As described above, according to the present invention,
By using the air blowing means for switching the conveyance of the sheet material for guiding the sheet material to the first branch guide means or the second branch guide means and for reducing the curl due to the cooling of the sheet material, the curl amount correction ability can be improved in a small space. As a result, it is possible to provide a high-quality curl amount correction apparatus and an image forming apparatus.

[0034]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part of a curl amount correction unit according to a first embodiment.

FIG. 2 is an explanatory diagram of a main part of a curl amount correction unit according to the first embodiment.

FIG. 3 is an explanatory diagram of a main part of a curl amount correction unit according to the first embodiment.

FIG. 4 is an explanatory view of a main part of a curl amount correction unit according to a second embodiment.

FIG. 5 is an explanatory view of a main part of a curl amount correction unit according to a second embodiment.

FIG. 6 is an explanatory view of a main part of a conventional curl amount correction unit.

FIG. 7 is an explanatory view of a main part of a conventional curl amount correction unit.

FIG. 8 is a configuration explanatory view of an image forming apparatus including a curl amount correcting unit according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Entry path 10a ... Vent 11a ... Upper curl correction path 11b ... Lower curl correction path 12 ... Branch point 13 ... Center line 15 ... Blowing means 16 ... Control circuit 17 ... Environment detection means 18 ... Storage means 19 ... Calculation means 1a ... roller pair 1b ... roller pair 20 ... sheet material 100 ... upper cassette 101 ... paper feed roller 102 ... lower cassette 103 ... paper feed roller 106 ... registration roller 111 ... laser modulation 112 ... photosensitive drum 113 ... image writing optical system 114 ... development Device 115 transfer charger 116 separation charger 117 transport belt 118 fixing device 119 discharge roller 120 primary charger 121 curl amount correction means 201 scanning optical system light source 202 platen glass 203 document platen 205 Light receiving element 206: Image processing Part 207 ... electrical signal 1000 ... printer 2000 ... scanner 3000 ... sorter

Claims (11)

[Claims] An upper curl correcting means for correcting an upward curl of the sheet material; a lower curl correcting means for correcting a downward curl of the sheet material; and a sheet material interposed and separated by a predetermined space. A guide means for forming a path, a blowing means for blowing air to the sheet material, and a control means for controlling the blowing means, wherein the guiding means is a first branch guide means in two directions in the middle,
The first branch guide unit forms a path for conveying the sheet material to the upper curl correction unit, and the second branch guide unit forms a path for conveying the sheet material to the lower curl correction unit. An opening is formed in the guide means and the guide means in the vicinity of a branch point of the second branch guide means, and the airflow by the air blowing means passes through the opening and is perpendicular to the sheet surface or at an acute angle to the conveyance direction. A curling amount correcting device, wherein the air blowing means is disposed in the first branch guide means and the sheet material is conveyed to the first branch guide means or the second branch guide means by controlling an air flow near a branch point. 2. When the first branch guide means is arranged on the upper side and the second branch guide means is arranged on the lower side, the entrance width of the second branch guide means is made larger than the entrance width of the first branch guide means. 2. The curl amount correcting device according to claim 1, wherein the curl amount correcting device is widened. 3. The curl amount correction device according to claim 1, wherein an air flow near a branch point is controlled by an air blowing operation and a suction operation of the air blowing unit. 4. The curl amount correction device according to claim 1, wherein the airflow control by the air blowing means is performed only for the intensity of the air volume. 5. A plurality of the air blowing means are arranged, one of which operates when conveying a sheet material to the first branch guide means, and the other which operates when conveying a sheet material to the second branch guide means. The curl amount correction device according to any one of claims 1 to 4, wherein: 6. The curl amount correcting device according to claim 5, wherein the plurality of blowing units are arranged in a direction orthogonal to a conveying direction of the guide unit. 7. An opening is formed on both sides of a guide surface of said guide means, and said plurality of air blowing means are provided on both sides such that an airflow passing through said opening is perpendicular to a sheet surface or at an acute angle with respect to a conveying direction. The curl amount correction device according to claim 5, wherein at least one device is provided. 8. The apparatus according to claim 1, further comprising detecting means for detecting a curl amount of the sheet material, wherein the control means controls the air blowing means based on a detection signal of the detecting means. 2. The curl amount correction device according to claim 1. 9. An environment detecting means for detecting the temperature and humidity of the surrounding environment, a storage means for storing the type of sheet material, and a calculation for predicting a curl direction of the sheet material from information of the environment detecting means and the storage means. The curl amount correction apparatus according to any one of claims 1 to 7, further comprising: means for controlling the blowing means using the control means based on a result of the calculation means. 10. An image forming apparatus, comprising: an image forming unit for forming an image on a sheet material; and the curl amount correcting device according to claim 1. Description: 11. The image forming apparatus according to claim 10, wherein the curl amount correction device is disposed downstream of a fixing device that fixes an image on a sheet material in a sheet material conveyance direction.