JP3754746B2 - Curling apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a curling device having a pair of curling rollers for curling the sheet material to be conveyed in the direction opposite to the curling direction, and an image forming apparatus using the curling device.
[0002]
[Prior art]
In a curling apparatus having a pair of curling rollers for curling a sheet material in order to take the curl of the conventional sheet material, as shown in FIG. 10, an elastic material having a foamed urethane rubber portion as an elastic portion on the metal roller 401. The sponge roller 400 as a roller is pressed and rotated, and the sheet material S is conveyed between the press-contacted nips as shown in FIG. 10A, thereby moving downward in the figure (the circumferential direction of the metal roller 401). The curl is removed by curling.
[0003]
[Problems to be solved by the invention]
However, in the case of the above-described prior art, in order to maximize the effect of curling (curling removal), the penetration amount N (see FIG. 10A) is used as the amount of pressure contact of the metal roller 401 to the sponge roller 400. When the sheet material S is increased, wrinkles are generated when the sheet material S passes through the nip. Therefore, the intrusion amount N has to be 1 mm or less, and it is difficult to maximize curling.
[0004]
The present invention has been made to solve the above-described problems of the prior art. The object of the present invention is to prevent wrinkles from occurring during the conveyance of the sheet material and to curl the sheet to the maximum extent. It is an object of the present invention to provide a curling apparatus and an image forming apparatus having good sheet material conveyance performance using the curling apparatus.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, the first roller having an elastic portion and the second roller having higher hardness than the first roller are in pressure contact with each other and rotated to rotate the sheet material. In a curling apparatus having a pair of curling rollers that can transport and curl a sheet material in a circumferential direction of the second roller, the length of the elastic portion of the first roller is the maximum length of the sheet material to be transported. By making the width shorter than the conveying width, the restraining area of the sheet material by the curling roller pair is reduced.
[0006]
The first roller is divided into a plurality of parts in the longitudinal direction.
[0007]
Furthermore, the first roller or the second roller is shaped to have a reduced diameter from both axial ends toward the center.
[0008]
Furthermore, a guide roller smaller than the outer diameter of the first roller is provided at both ends in the longitudinal direction of the elastic portion of the first roller.
[0009]
The first roller is brought into pressure contact with the second and third rollers provided at a predetermined interval in the circumferential direction of the first roller, and the nip between the first and second rollers and the first and second rollers. In the curling apparatus having a pair of curling rollers capable of curling the sheet material in the circumferential direction of the first roller at the nip of the three rollers, the hardness of at least one of the second and third rollers is set as follows: The hardness of the first roller is lower than that of the first roller.
[0010]
Each of the curling devices is used as a pair of conveying rollers for conveying a sheet material of the image forming apparatus.
[0011]
In order to maximize curling when the length of the elastic portion of the first roller is equal to or greater than the maximum conveyance width of the sheet material, the amount of pressure contact between the first roller and the second roller is increased. However, if the number is simply increased, wrinkles occur when the sheet material is conveyed. This is because the constraining area of the sheet material by the curling roller pair is large.
[0012]
Therefore, in the curling device of the present invention, the length of the elastic portion of the first roller is made shorter than the maximum conveyance width, and the restraining area of the sheet material is reduced. Therefore, the first roller, the second roller, Even if the amount of pressure contact is increased, wrinkles are not generated during the conveyance of the sheet material. Further, since the amount of press contact is increased, curling can be performed to the maximum extent.
[0013]
By dividing the first roller into a plurality of parts in the longitudinal direction, it is possible to deal with various sheet materials, and it is possible to prevent wrinkles and maximize curling according to the size of each sheet material.
[0014]
Since the outer diameter of the second roller is reduced from the both axial ends toward the center, the circumferential speed for conveying the sheet material is increased at both axial ends having a large outer diameter. The material is pulled outward in the width direction. Thereby, the generation of wrinkles is further reduced.
[0015]
By providing guide rollers smaller than the outer diameter of the first roller at both ends in the longitudinal direction of the elastic portion of the first roller, both ends in the width direction of the sheet material are conveyed along the guide rollers. It will also prevent breakage.
[0016]
The first roller is brought into pressure contact with the second and third rollers provided at a predetermined interval in the circumferential direction of the first roller, and the nip between the first and second rollers and the first and second rollers. In the curling apparatus having a pair of curling rollers capable of curling the sheet material in the circumferential direction of the first roller at the nip of the three rollers, the hardness of at least one of the second and third rollers is set as follows: By lowering the hardness of the first roller, the sheet material is curled in the circumferential direction of the first roller at the nip of the first and second rollers and the nip of the first and third rollers. .
[0017]
In addition, by making the hardness of at least one of the second and third rollers lower than the hardness of the first roller having, for example, an elastic portion, the amount of pressure contact can be increased, and the circumferential direction of the first roller can be further increased. Can be curled, and the curling effect is further improved.
[0018]
By using each of the curling devices as a pair of conveying rollers for conveying the sheet material of the image forming apparatus, the image forming apparatus can have a good sheet material conveying performance.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
The present invention will be described below based on the illustrated embodiments.
[0020]
FIG. 1 is a diagram that best represents the characteristics of the curling apparatus according to Embodiment 1 of the present invention, and shows a conveying roller pair 103 as a curling roller pair, and 103a is a foam made of foamed urethane rubber as an elastic portion. An elastic roller as a first roller having a urethane part 103d, 103b is a metal roller as a second roller having a higher hardness than the elastic roller 103a.
[0021]
First, an overall configuration of an image forming apparatus provided with a curling device along the flow of a sheet material will be described with reference to FIG.
[0022]
The sheet material S in the cassette disposed at a predetermined position in the lower half of the image forming apparatus main body 150 of 151, 152, 153, 154 shown in FIG. 2 is picked up by the pick-up rollers 155, 159, and the separating means 156 , 160 are separated into one sheet, and conveyed upward in the figure by a pair of conveying rollers 157.
[0023]
Further, the image of the original 174 is exposed to the photosensitive drum 161 by the optical means 175, and a toner image is formed on the photosensitive drum 161. The toner image on the photosensitive drum 161 and the sheet material S described above are conveyed in the direction of the photosensitive drum 161 in synchronization with the registration roller pair 158.
[0024]
Next, the toner image on the photosensitive drum 161 is transferred to the sheet material S by the transfer charger 162. The transferred sheet material S passes through the fixing device 164, and the toner on the sheet material S is fixed.
[0025]
Next, the double-sided image mode or the multiple image forming mode will be described with reference to FIGS. 3 and 4 showing detailed views of the intermediate sheet material stacking apparatus 100. FIG.
[0026]
The sheet material S that has completed the first image formation described above is guided to the intermediate tray conveyance path 102 via the entrance guide 101. Then, the sheet material guided to the intermediate tray conveyance path 102 is sent to the discharge roller pair 104 by the conveyance roller pair 103 as a curling roller pair, and is discharged onto the intermediate tray 105 by the discharge roller pair 104.
[0027]
The sheet material discharged onto the intermediate tray 105 is positioned at the end of the sheet material in the direction orthogonal to the conveying direction by the left and right regulating members 109A and 109B (see FIG. 4) installed on the intermediate tray 105. Be regulated.
[0028]
Since the right and left regulating members 109A and 109B convey the sheet material with a central reference, both regulating members 109A and 109B are orthogonal to the sheet material conveying direction by the driving force of the stepping motor 110 (in FIG. 4). When the sheet material is discharged onto the intermediate tray 105, the sheet material is moved to a position corresponding to the sheet material size and the positions of both end portions of the sheet material are regulated.
[0029]
When this regulation is finished, the left and right regulating members 109A and 109B return to a position away from the end of the sheet material by a predetermined distance (for example, 1 mm) and wait for discharge of the next sheet material.
[0030]
As described above, when the position of the end portion of the sheet material discharged onto the intermediate tray 105 is regulated by the left and right regulating members 109A and 109B, the trailing edge regulation placed on the intermediate tray 105 is regulated. The member 111 moves in the direction of arrow A in FIG. 3 by a driving force of a motor (not shown), so that the front end (the rear end when ejected) reaches a refeedable position (a lower end position from the feeding roller 112). Move on the intermediate tray 105 until
[0031]
When the sheet material is discharged onto the intermediate tray 105, the trailing edge regulating member 111 is a predetermined distance (for example, 30 mm) from the position where the leading edge of the sheet material that falls on the intermediate tray 105 (the trailing edge when dropped) is located. ) Waiting at a remote location.
[0032]
Then, after the position is regulated by the left and right regulating members 109A and 109B, the trailing edge regulating member 111 moves on the intermediate tray 105 in the direction of arrow A in FIG. 3 by a distance corresponding to the sheet material size.
[0033]
The rear end regulating member 111 moves along a guide 105A formed in the sheet material conveyance direction.
[0034]
When a predetermined number of sheet materials that have undergone the first image formation have been stacked on the intermediate tray 105, a feeding roller 112 that rotates counterclockwise causes the leading edge of the sheet material stacked on the intermediate tray 105 to be viewed from above. A feeding assist force is applied to the feeding roller 112 so that the sheet material can be reliably fed by pressing.
[0035]
The sheet material fed by the feeding roller 112 is separated and fed one by one by a separation feeding device 115 including a feeding roller 113 that rotates counterclockwise and a separation belt 114 that rotates counterclockwise.
[0036]
In the double-sided image forming mode, the flapper 116 is set at the position 116a, and the lowermost sheet material separated and fed by the separation feeding device 115 is regenerated by the registration roller pair 117 whose rotation is stopped. It is sent to the feeding path 118.
[0037]
In the multiple image forming mode, the flapper 116 is set at the position 116b, and the lowermost sheet material separated and fed by the separation feeding device 115 is sent to the multiple path 119 and is fed to the rear of the sheet material. It is conveyed to the conveyance roller pair 120 until the end passes through the flapper 116.
[0038]
Then, the sheet material rear end passes through the flapper 116 and is fed back to the registration roller pair 117 whose rotation is stopped by the reverse rotation pair 120 to correct the skew state. Then, the registration roller pair 117 refeeds the sheet. 118.
[0039]
In such a flow of the sheet material, as shown in FIG. 2, the sheet material passes through the fixing device 164 and is then conveyed downward in the figure (on the intermediate sheet material stacking apparatus 100 side), and then the intermediate tray conveyance path 102 is passed. As described above, the sheet material S that has passed through the intermediate tray conveyance path 102 is curled in the upward direction when loaded on the intermediate tray 105. Further, when the sheet material is moved by the rear end regulating member 111 or the like, the sheet material is curled, so that the case where the sheet material cannot be moved occurs.
[0040]
Therefore, in this embodiment, in order to take the curl, in the conveying roller pair 103 shown in FIG. 3 as the curling roller pair, as described above, the first roller 103a is made of foamed urethane rubber. A φ20 mm elastic roller having a urethane portion 103d is passed through, and a φ8 metal shaft 103c is passed through the center, that is, the thickness of the foamed urethane portion 103d as an elastic portion is 12 mm.
[0041]
Further, the second roller 103b is a φ9 metal roller, the shafts are fixed, and the elastic roller 103a is driven by a drive source (not shown), so that the elastic roller 103a is shown in FIG. Since the foamed urethane portion 103d is sufficiently thick, the sheet material S is conveyed along the outer diameter of the metal roller 103b and is curled in the circumferential direction (downward in the figure). The curl will be removed.
[0042]
Further, the smaller the outer diameter of the metal roller 103b is, the larger the curvature is, so that the curl removing effect is improved. Although the curl removing effect is improved, if the intrusion amount N is simply increased, the sheet material will be wrinkled when it passes.
[0043]
Therefore, in the present embodiment, the length of the foaming urethane portion 103d of the elastic roller 103a is set to 200 mm as shown in FIG.
[0044]
In this numerical value, the size for conveying the sheet material S is a fixed size, A size {A3 (297 × 420), A4 (210 × 297), A5 (148 × 210)}, B size {B4 (257 × 364). ), B5 (182 × 257)}, leisure (431.8 × 279.9), letter (279.4 × 215.9), statement, wrinkles are particularly wide and long Occurs when the sheet material is A3 and the leisure size (long sheet material conveyance direction).
[0045]
In general, the conveyance roller pair 103 constrains the entire width of the sheet material and conveys the sheet material for a long time in this state (the area where the sheet material S is constrained by the conveyance roller pair 103 (restraint region). Therefore, wrinkles are likely to occur in the sheet material.
[0046]
Further, according to experiments, it is known from experiments that the curl removal effect is effective when the intrusion amount N of the foamed urethane portion 103d of the metal roller 103b and the elastic roller 103a is 2 mm or more. When the relationship between the length of the foamed urethane portion 103d of the elastic roller 103a (φ20 mm) and the wrinkle when the diameter of the metal roller 103b is φ9 mm is experimentally obtained in the leisure size, it is as shown in FIG. In the drawing, white circles indicate wrinkles that appear at the center of the sheet as the sheet material, and black circles indicate wrinkles that protrude at the edges of the paper.
[0047]
That is, it can be seen from FIG. 7 that if the length of the foamed urethane portion 103d is 200 mm, wrinkles will not occur even in leisure-size paper. Further, the curl removing effect is sufficiently effective if the length of the elastic roller 103a is 200 mm.
[0048]
From the above, in this embodiment, the length of the foaming urethane portion 103d of the elastic roller 103a is set to 200 mm.
[0049]
Further, in the present embodiment, the shape of the metal roller 103b is an inverted crown shape in which the outer diameter decreases from both axial ends toward the center as shown in FIG. This is because, when the outer diameter is large, the peripheral speed for transporting the sheet material is increased, so that the sheet material is pulled outward in the width direction, thereby further reducing the occurrence of wrinkles.
[0050]
Further, as shown in FIG. 8, the sheet material may move freely in the direction of the shaft 103c (the direction of the arrow A in the figure) in the portion of the elastic roller 103a where the foaming urethane portion 103d is not provided. Since the corners of the sheet material may be caught, as shown in FIG. 1, the sheet material conveyance width region W is in contact with the metal roller 103b in the portion without the foaming urethane portion 103d of the elastic roller 103a. Guide rollers 301 smaller than the outer diameter of the elastic roller 103a are provided on both sides in the axial direction.
[0051]
In this manner, the upper curled sheet material S is decurled and the sheet material is stacked on the intermediate tray 105.
[0052]
(Embodiment 2)
This embodiment in which the elastic roller 103a described in the first embodiment has a different shape from the shape of the elastic roller 103a will be described with reference to FIG.
[0053]
FIG. 9 shows the shape of the elastic roller in the longitudinal direction, which is referred to as an elastic roller 103a ′ as the first roller.
[0054]
A foamed urethane portion 305 made of foamed urethane rubber is divided in the longitudinal direction as an elastic portion of the elastic roller 103a ′, and has a skewered shape. The divided foaming urethane portion 305 is disposed so as to escape the width direction end portions of all the sheet materials to be conveyed (width dimension) as shown in FIG.
[0055]
A guide roller 302 having an outer diameter that is smaller than the outer diameter of the elastic roller 103a ′ and does not contact the opposing metal roller 103b is provided between the foaming urethane portions 305.
[0056]
As described above, by providing the guide roller 302 for guiding the sheet material without providing the nip between the elastic roller 103a ′ and the metal roller 103b at the end portion in the width direction of the sheet material, the sheet material can be prevented from being bent or the like. It also becomes.
[0057]
Further, by sufficiently reducing the diameter of the metal shaft 103c of the metal roller 103a ′, the thickness of the foamed urethane portion 305 can be sufficiently increased, and the curl removing effect described in the first embodiment can be sufficiently achieved.
[0058]
Further, by setting the amount of penetration N of the elastic roller 103a ′ into the metal roller 103b to 2.0 mm, the curl removing effect is sufficiently performed, and as described above, the skewered elastic roller 103a ′ is formed. As a result, the constraining area of the sheet material conveying roller pair 103 is also reduced, so that the curl removing effect can be maximized without causing the sheet material to be wrinkled.
[0059]
Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.
[0060]
In the first embodiment and the present embodiment, the elastic portions of the elastic rollers 103 and 103a ′ are made of foamed urethane rubber and have a hardness of 15 ° (ASKER-A). Any material can be used as long as it is elastic, such as rubber. At this time, the amount of penetration and the length of the elastic portion of the elastic roller need to be changed by changing the material and hardness of the rubber. It becomes. This also applies to the third embodiment shown below.
[0061]
(Embodiment 3)
In the image forming apparatus that conveys a sheet material similar to that described in the first embodiment, as shown in FIG. 8, the discharge roller 104a is made of a rubber material, and the discharge roller 104a includes second and second discharge rollers 104a. As the third roller, two rollers 104b and 104c are in pressure contact.
[0062]
Here, since the two rollers 104b and 104c are in pressure contact with the discharge roller 104a at an angle θ, when the sheet material passes through the roller pair 104a, 104b and 104c, the sheet material curls downward. It is attached. That is, the discharge roller pair 104 is a curling roller pair.
[0063]
In the present embodiment, the roller 104b as the second roller is an elastic roller having a foamed urethane portion 104e as an elastic portion (the roller 104c as the first roller may be an elastic roller). Both of them may be elastic rollers.) In the same manner as in the first embodiment, the lower curl can be further decurled at the nip between the discharge roller 104a and the elastic roller 104b, so that the curl removing effect is improved. .
[0064]
Further, the length of the elastic roller 104b is set to 200 mm as in the first embodiment, so that wrinkles are not generated, and the curl is removed.
[0065]
In the above embodiment, the conveyance roller pair and the discharge roller pair in the intermediate sheet material stacking apparatus 100 of the image forming apparatus are described as an example of the curling roller pair, but the sheet material conveyance roller pairs in other portions are also exemplified. The same can be applied.
[0066]
【The invention's effect】
As described above, according to the present invention, the first roller having the elastic portion and the second roller having higher hardness than the first roller are brought into pressure contact with each other, and are rotated. In the curling apparatus having a pair of curling rollers capable of curling the sheet material in the direction, the length of the elastic portion of the first roller is made shorter than the maximum conveying width of the sheet material, and the restraining area of the sheet material is reduced. The amount of pressure contact between the first roller and the second roller can be increased, wrinkles are not generated, and the sheet material before conveyance is curled opposite to the curl direction (before conveyance) The curl removal effect of the sheet material can be improved.
[0067]
Further, by dividing the first roller into a plurality in the longitudinal direction, it is possible to cope with various sheet materials, and it is possible to prevent the generation of wrinkles and maximize curling according to the size of each sheet material.
[0068]
Furthermore, by making the outer diameter of the second roller a reduced diameter from both axial ends toward the center, both axial ends having a large outer diameter increase the peripheral speed for conveying the sheet material. Since the sheet material is pulled outward in the width direction, the generation of wrinkles can be further reduced.
[0069]
Furthermore, by providing a guide roller smaller than the outer diameter of the first roller at both ends in the longitudinal direction of the elastic portion of the first roller, both ends in the width direction of the sheet material are conveyed along the guide roller. It will also prevent corner breakage.
[0070]
Then, the second roller and the third roller provided at a predetermined interval in the circumferential direction of the first roller are pressed against the first roller, and the nip between the first and second rollers and the first roller And a curling apparatus having a pair of curling rollers capable of curling the sheet material in the circumferential direction of the first roller at the nip between the third roller and the hardness of at least one of the second and third rollers Is lower than the hardness of the first roller, so that the sheet material can be securely placed in the circumferential direction of the first roller at the nip of the first and second rollers and the nip of the first and third rollers. Can be curled.
[0071]
In addition, by making the hardness of at least one of the second and third rollers lower than the hardness of the first roller having, for example, an elastic portion, the amount of pressure contact can be increased, and the circumferential direction of the first roller can be further increased. Can be curled, and the curling effect is further improved.
[0072]
By using each of the curling devices as a pair of conveying rollers for conveying the sheet material of the image forming apparatus, the image forming apparatus can have a good sheet material conveying performance.
[Brief description of the drawings]
FIG. 1 is a plan view of a curling roller pair of a curling device according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of an image forming apparatus in which the curling apparatus according to Embodiment 1 of the present invention is used.
FIG. 3 is a detailed sectional view of the intermediate sheet material stacking apparatus of FIG. 2;
4 is a plan view of FIG. 3. FIG.
FIG. 5 is a side view of a curling roller pair of the curling device according to the first embodiment of the present invention.
FIG. 6 is a plan view of a metal roller.
FIG. 7 is a diagram showing the relationship between the length of the foamed urethane portion of the elastic roller and the number of paper wrinkles.
FIG. 8 is a partial cross-sectional view of the intermediate sheet material stacking apparatus of FIG.
FIG. 9 is a plan view of a curling roller pair of the curling device according to the second embodiment of the present invention, and shows the width dimension of each sheet material.
FIG. 10 is an explanatory view of a curling roller pair of a conventional curling device.
[Explanation of symbols]
103 Conveyor roller pair (curling roller)
103a, 103a ′ Elastic roller (first roller)
103b Metal roller (second roller)
103c Shaft 103d, 104e, 305 Foam urethane part (elastic part)
104 Discharge roller pair (curling roller)
104a Discharge roller (first roller)
104b Roller (second roller)
104c Roller (third roller)
301, 302 Guide roller

Claims (5)

A first roller having an elastic portion and a second roller having higher hardness than the first roller are pressed against each other and rotated to convey the sheet material, and the sheet material is arranged in the circumferential direction of the second roller. A curling apparatus having a pair of curling rollers capable of curling
The curling device according to claim 1, wherein the length of the elastic portion of the first roller is shorter than the maximum conveyance width of the sheet material to be conveyed, thereby reducing a constraining area of the sheet material by the curling roller pair.   The curling apparatus according to claim 1, wherein the first roller is divided into a plurality of parts in the longitudinal direction.   The curling apparatus according to claim 1, wherein the first roller or the second roller has a shape whose diameter is reduced from both axial ends toward the center.   The curling apparatus according to claim 1 or 2, wherein guide rollers smaller than the outer diameter of the first roller are provided at both ends in the longitudinal direction of the elastic portion of the first roller. 5. An image forming apparatus, wherein the curling device according to claim 1 is used for a pair of conveying rollers for conveying a sheet material.

Images