JPH11189363A - Sheet curl smoothing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost and simple-structured sheet curl smoothing device that is capable of realizing an easy and safe removal of any jamming sheet, maintaining improved sheet feeding and image qualities and suppressing noise to the most. SOLUTION: A sheet curl smoothing device comprises one through feed roller 18c for delivering sheets ahead, and a pair of cylindrical rollers 18a and 18b to which the through feed roller 18c applies a predetermined pressing force to produce nip parts 20a and 20b, which two cylindrical rollers are each constituted of a shaft part 18f and a plurality of short cylindrical roller parts 18g all molded integrally or fixed together and are arranged so that their roller parts 18g are staggered against mutual contact of their periphery. Any sheet with a curl is passed through the nip parts 20a and 20b for curl smoothing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet curl removing device for removing a curl on a sheet to which an image has been transferred in an electrophotographic image forming apparatus used in a copying machine or the like.

[0002]

2. Description of the Related Art Generally, in an apparatus having an electrophotographic image forming apparatus, for example, in a copying machine, an electrostatic latent image is formed on a transfer sheet (hereinafter referred to as a sheet) sent from a sheet feeding section. After the image is transferred at the transfer section of the image carrier,
The toner image passes through the fixing device and is fixed, and is discharged outside the apparatus.

[0003] When the sheet passes through the transfer section and the fixing device, it passes between a plurality of rollers, so that the sheet often becomes curled, that is, bent. This curl may be attached to the sheet from the beginning due to the manufacturing method of the sheet, but it has been found that the curl is different for all the sheets in the sheet feeding unit used in the copying machine.

[0004] This curl on the sheet causes problems when the sheet is processed in the machine. Sheets fed in a curled state tend not to be aligned with the alignment mechanism of the copier, and curled sheets tend to cause jams (paper jams) and erroneous feeding in the machine.

In Japanese Patent Application Laid-Open No. 56-83755, two pairs of rigid contact areas, such as two nips formed by three rollers, are provided continuously.
The curled sheet is passed through these contact areas, first bent in a first direction, then bent in a second direction opposite to the first direction, deforming the sheet in opposite directions A sheet curl removing device that removes curl by removing the curl is disclosed.

[0006]

However, in the conventional sheet decurling apparatus, since the curl is removed by passing between a plurality of rigid rollers, the jam sheet is removed when a jam occurs. Is a very difficult configuration. In particular, when removing an accordion-shaped jam sheet, the sheet is likely to be torn or a torn piece of paper will remain in the machine, which is likely to be an obstacle to subsequent sheet conveyance, and the user cannot process the sheet. There was a problem that sometimes there was no situation.

In the sheet curl removing device, the curled sheet is bent very sharply once or twice, so that when the sheet is thick paper, a conveyance failure occurs and jams occur. In this case, there are problems such as bending marks and roller marks remaining on the sheet, contamination of the sheet due to slippage of the roller, and generation of noise when the sheet passes. In addition, there is a problem that the configuration is complicated, a considerable space is required, and the cost is high.

The present invention solves the above-mentioned conventional problems, and can easily and safely remove a jam sheet even if a jam occurs, thereby improving sheet transportability and image quality. It is an object of the present invention to provide a low-cost, simple configuration of a sheet curl removing device that can be maintained and minimize noise.

[0009]

The gist of the present invention is that at least one through-conveying roller for feeding a sheet and two through-conveying rollers which are pressed by a predetermined urging force. A pair of rollers forming a nip portion, each of which has a plurality of short cylindrical roller portions formed on each shaft portion, and a portion of the shaft portion of one of the rollers so that the peripheral surfaces thereof do not contact each other. And two frame-cut rollers arranged so that the roller portion of the other roller enters.
In a sheet decurling apparatus for removing a curl by passing a curled sheet through the nip portion, the sheet curl is covered from above and guides the conveyance of the sheet, and one end of which forms an image. An upper guide plate which is pivotally supported on the apparatus side and is openable and closable on the upper side about the fulcrum is provided, and at least a portion of the through-conveying roller which comes into contact with the sheet is made of a material having low thermal conductivity. It is formed by.

According to a second aspect of the present invention, in response to opening of the upper guide plate, pressurization of the pair of frame-cutting rollers of the feed-through roller is released, and re-opening in conjunction with closing of the upper guide plate. That is, a pressure releasing means for applying pressure is provided.

According to a third aspect of the present invention, the pressurizing force of the through-conveying roller is set to be weaker than the stiffness of the cardboard, and the oscillating conveying roller can swing in a direction away from the frame-cutting roller according to the stiffness of the stiffness. It is provided.

According to a fourth aspect of the present invention, the pair of frame-cutting rollers have the same outer diameter and are set slightly smaller than the outer diameter of the through-conveying roller. It is driven by the same drive mechanism.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a copying machine provided with a sheet curl removing device according to the present invention is provided with a sheet feeding device 3 including four sheet feeding trays 10 and respective sheet feeding rollers 11, and disposed above the sheet feeding device 3. The image forming apparatus 1 includes an image forming apparatus 1 and an automatic document feeding and exposing device 4 disposed above the image forming apparatus 1 for capturing image information from a document.

In the image forming apparatus 1, a transfer means 14 is disposed so as to be able to contact the photosensitive drum 13, and a transfer timing of the sheet is set upstream of the photosensitive drum 13 in the sheet conveying direction. A fixing unit 15 for fixing an image on the transferred sheet is provided downstream of the registration roller 12 in the sheet conveying direction. The sheet reversing unit 5 and the sheet discharge port 37 are provided in the sheet conveying direction of the fixing unit 15.

As shown in FIG. 2, the paper discharge reversing unit 5
Feed-through roller 18c, frame-cut rollers 18a, 18b
In the vicinity of the sheet discharge port 37, the image forming apparatus 1 is rotatably supported at a fulcrum 19a, and a through-transport roller 18c is rotatably supported to guide the transport of the sheet and open and close upward. Sheet curling device 18 comprising an upper guide plate 19 and frame cut rollers 18a, 1
8b, a reversing switching claw 16, which switches between sheet discharge and reversal, and a discharge roller 3 disposed at a discharge port.
2a, 32b, guide plate 4 for forming sheet reversal path
4, 45, 35, the inner discharge roller 17 disposed on the guide plate 45, the branch claw 22, the reversing roller 21, and the guide plate 35
, An interlocking roller 31 provided opposite the inner discharge roller 17, an outer discharge roller 30 disposed on a guide plate 35, and a double-sided branching claw 27 for forming a reverse discharge path 28 and the like. And so on. The reversing unit 2 (see FIG. 7) is constituted by members such as the above-mentioned branching pawl 22, the reversing roller 21, and the double-sided branching pawl 27.

As shown in FIG. 3, the sheet curl removing device 18 includes a through-transport roller 18c and two frame-cut rollers 18a,
The frame cutting rollers 18a and 18b each have a shaft portion 18f and a plurality of roller portions 18g formed in or fixed to the shaft portion 18f at substantially equal intervals in a short columnar shape having a diameter larger than the shaft portion 18f. Roller 1 consisting of
Roller portion 18 of frame break roller 18b is attached to shaft portion 18f of 8a.
g, so that the roller portion 18g of the frame-cutting roller 18a slightly enters the shaft portion 18f of the frame-cutting roller 18b, that is, so that the peripheral surfaces thereof do not contact each other. 18 g are arranged so as to penetrate each other. Frame cut rollers 18a, 18
The plurality of roller portions 18g excluding the shaft portion 18f of b are made of a material having relatively low thermal conductivity (rubbers such as EP rubber, urethane, silicon rubber, or resins such as polyacetal, polyethylene terephthalate, and polycarbonate). This prevents abnormally high temperatures on the surfaces of the frame break rollers 18a and 18b.

As shown in FIG. 4, the through-conveying roller 18c has a rigid shaft center 18e at the center thereof and a material having relatively low thermal conductivity (e.g., rubber such as EP rubber, urethane, silicon rubber) around the center thereof. Or a resin such as polyacetal, polyethylene terephthalate, or polycarbonate). and,
As shown in FIGS. 2 and 5, both ends of the through transport roller 18 c are provided with bearings 38 movably supported by the upper guide plate 19.
One end of the spring 38 supported on the upper guide plate 19 is in contact with the bearing 38, and is biased toward the frame cutting rollers 18a and 18b. When the guide plate 19 is closed, the feed transport roller 18c is pressed onto the frame cutting rollers 18a, 18b by the urging force of the spring 39, and the nip portions 20a, 20
b is formed. The pressure of this spring 39 is
The cardboard sheet P1 is set to be relatively weaker than the stiffness of the cardboard sheet P1.
a, 18b so as to be able to swing away from the upper guide plate 19.
It is supported by. Therefore, in this embodiment, the feed roller 18 c is connected to the upper guide plate 19 by the spring 39.
The pressure release means according to claim 2 is a structure attached via the pressure release means.

In the sheet curl removing device, the outer diameter of the frame cut rollers 18a and 18b
c is slightly smaller than the outer diameter of
The outside diameters of b are set equal to each other. As shown in FIG. 6, the timing drive rollers 40a and 41a fixed to the shafts of the frame break rollers 18a and 18b are driven by one drive source (not shown) and the drive sources of the frame break rollers 18a and 18b. By driving with the timing belt 42, the rotation speeds are made equal to each other. Flange 40 of timing pulleys 40 and 41
Reference numerals a and 41a are formed on opposite sides to prevent the timing belt 42 from shifting.

The structure of the reversing unit 2 will be described. In FIG. 7, an arrow D which is always the sheet conveying direction
To the reversing roller 21 rotating in the direction shown in FIG.
2 are provided so as to overlap. This reversing roller 21
As shown in FIG. 8, a plurality of roller portions 21 are attached to the shaft portion 21a.
b are provided at substantially equal intervals, while the branch claws 22
A plurality of claw portions 22a are provided on the shaft portion 22c at substantially equal intervals, and as shown in FIG.
The pivot 22 is pivotally supported by the apparatus main body side at a fulcrum 22d so that the claw portion 22a of the branch claw 22 enters from below. An action member 22e is fixed to a predetermined position of a shaft portion 22c of the branch claw 22, and the other end of a spring 23, one end of which is fixed to the apparatus main body side, is attached to the tip of the action member 22e. Are urged in the direction of the shaft 21a of the reversing roller 21. A switchback driven roller 24 rotatable in the direction of arrow E and a switchback roller 25 constantly rotating in the direction of arrow B are provided in the sheet conveying direction of the reversing roller 21. The roller 26 and the lower guide plate 43 are provided. In the vicinity of the double-sided roller 26, the double-sided branch claw 27
Are arranged, and by the switching, the reverse discharge path 28,
Alternatively, a double-sided refeed path 29 is formed.

Next, the operation of the above configuration will be described. As shown in FIG. 1, a sheet P separated and conveyed by a sheet supply roller 11 from the top of a sheet bundle stored in a sheet supply tray 10 is subjected to predetermined timing adjustment by a registration roller 12, The toner image is conveyed in the circumferential direction of the drum 13 and the toner image on the photosensitive drum 13 is transferred by the transfer unit 14 to form an image. After that, the image on the sheet P is fixed by the fixing means 15 and, as shown in FIG.
Is removed, and the sheet P is discharged from the sheet discharge port 37 to the outside of the apparatus by the operation of the reversing switching claw 16 or conveyed into the reversing unit 2 through the inner discharge roller 17. As shown in FIG. 7, when the sheet P is conveyed along the guide in the direction of arrow A between the reversing roller 21 and the branch claw 22, as the sheet P advances in the rotation direction of the reversing roller 21, the branch claw is Due to the urging force and the shape of the claw portion 22a of 22, the sheet P is deformed inward from the outer peripheral surface of the roller portion 21b, and at the same time, the branch claw 22 is rotated by the propulsive force of the sheet P, The sheet P is pinched between the branching pawl 22 and the reversing roller 21, and the sheet P is stiffened by the propulsive force of the seated sheet P.
Is transported to the rear end. The sheet P that has passed through the branch claw 22
When the switchback roller 24 is lowered in the direction of the arrow E, the sheet P is sandwiched between the switchback roller 25 and is reversely conveyed by the conveyance force of the switchback roller 25 constantly rotating in the direction of the arrow B. After being guided by the rear side 22b of the branching pawl 22 and passing through the two-sided roller 26, the sheet is conveyed toward the reverse discharge path 28 or the two-sided refeeding path 29 depending on the switching method of the two-sided branching pawl 27. . If the reverse discharge path 28 is selected,
The sheet is discharged to the outside of the apparatus via the outer sheet discharging roller 30 and the sheet discharging outlet rollers 32a and 32b. As a result, the holding force between the rollers with respect to the sheet P is reduced, so that the sheet P is conveyed favorably without deteriorating the image quality, and noise is suppressed.

Next, the operation of the sheet curl removing device 18 will be described in detail. When the sheet having the curl generated by passing through the fixing unit 15 enters the sheet curl removing device 18, as shown in FIG. 5, the sheet P is nipped by the pressing force of the spring 39 of the through transport roller 18c. Roller 18 at the sections 20a and 20b
a, 18b, that is, through-conveyance rollers 18c
To remove curls.

If the sheet is thick paper, as shown in FIG. 9, when the thick paper sheet P1 enters the nip portion between the feed roller 18c and the cut-out roller 18a, the pressing force of the spring 39 is set to be weak. Since the stiffness of the sheet P1 is strong, the pressing force of the spring 39 is lower than the stiffness of the sheet P1, and the feed conveyance roller 18c causes the frame cutting rollers 18a, 18b to
The sheet is pushed further away, and conveys the sheet slightly away.

When a jam or a remaining sheet occurs in the sheet curl removing device 18, as shown in FIG. 2, after opening a front cover (not shown) of the copying machine main body, the upper guide plate 19 is opened.
Is opened in the direction of arrow C with the fulcrum 19a as the center, as in the case of the upper guide plate 19 ', the pressurization of the through-transport rollers 18c against the frame cutting rollers 18a and 18b is released, and the transport path is completely opened. Put your hand there and remove the remaining jam sheet. Thereafter, when the upper guide plate 19 'is closed to form the upper guide plate 19 and locked by a lock mechanism (not shown), the frame cutting rollers 18a and 18b are rotatably supported by the through-conveying roller 18c supported by the upper cover plate 19.
Is repressurized.

In this embodiment, the pressure releasing means of the second aspect is configured such that the through-conveying roller 18c is attached to the upper guide plate 19 via the spring 39. However, the present invention is not limited to this. Other structures such as providing an elastic member may be used as long as the mechanism is a simple mechanism in which the pressing of the through-conveying roller 18c against the frame cutting rollers 18a and 18b is released in conjunction with the opening of the plate 19.

In addition, since the earlier the curl is removed after the sheet is curled, the easier it is to remove the curl, the sheet curl removing device 18 is generally equipped with the fixing means 15.
It is preferable to dispose it immediately after the downstream side in the sheet conveyance direction. In this case, if the roller member 18d forming the surface of the through-conveying roller 18c and the roller portions 18c of the frame cutting rollers 18a, 18b are made of a material having a relatively low thermal conductivity as described above, the sheet decurling device can be used. 18 is prevented from receiving heat from the sheet and causing the rollers to become abnormally high in temperature.

[0026]

As described above, according to the first aspect, the sheet conveyance is guided by covering the through conveyance roller from the upper side, and one end thereof is pivotally supported by the apparatus main body. An upper guide plate that can be opened and closed is provided on the upper side around the fulcrum, and at least the portion of the through-conveying roller that contacts the sheet is formed of a material having low thermal conductivity. Accordingly, the state of the jam sheet can be easily visually checked, and the jam sheet can be easily removed.

Also, since the portion of the through-conveying roller that comes into contact with the sheet does not become abnormally high in temperature, even if the user touches the through-conveying roller, burns or injuries may occur if the user suddenly pulls his hand. Can be prevented.

According to the second aspect, the pressurization of the pair of frame-cutting rollers by the through transport roller is released in conjunction with the opening of the upper guide plate, and the pressurization is re-pressed in conjunction with the closing. Since the pressure releasing means is provided, the jam sheet can be removed more easily than the configuration of the first aspect.

According to the third aspect of the present invention, the pressurizing force of the through-conveying roller is set to be smaller than that of the cardboard.
According to the strength of the waist, it is provided so as to be swingable in a direction away from the cut-out roller, so that even a thick sheet is softly sandwiched between the through transport roller and the cut-out roller. Therefore, it is possible to maintain good transportability and image quality, and to minimize noise.

According to the fourth aspect, the pair of frame-cut rollers have the same outer diameter and are set slightly smaller than the outer diameter of the feed-through roller, and the rotation speeds thereof are equal to each other. In addition, since the sheet is conveyed while being driven by the same drive mechanism, the sheet curl removing device can be realized with a minimum necessary space, at low cost, and with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a copying machine having a sheet curl removing device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a reversing discharge unit of the copying machine of FIG. 1;

FIG. 3 is a plan view showing an arrangement configuration of a pair of through-conveying rollers and frame break rollers.

FIG. 4 is a plan view illustrating a through transport roller.

FIG. 5 is a side view of the sheet decurling apparatus showing a schematic configuration of the embodiment of the present invention.

FIG. 6 is a perspective view showing a driving method of a pair of frame break rollers.

FIG. 7 is a schematic configuration diagram illustrating a reversing unit of the copying machine of FIG. 1;

FIG. 8 is a plan view showing a positional relationship between a reversing roller and a branch claw.

FIG. 9 is a side view showing a state in which thick paper is passed through the sheet curl removing device of the present invention.

[Explanation of symbols]

 18 Sheet curl removing device 18a, 18b Frame break roller 18c Through transport roller 18d Roller member 18f Shaft portion 18g Roller portion 19 Upper guide plate 19a Support point

Claims (4)

[Claims] At least one through-conveying roller for feeding out a sheet, and a pair of rollers that form two nip portions by pressing the through-conveying roller with a predetermined urging force. A plurality of short cylindrical rollers are formed in the roller, and the rollers are arranged such that the roller of the other roller enters the shaft of one roller so that the peripheral surfaces of the rollers do not contact each other. A sheet curl removing device for removing a curl by passing a curled sheet through the nip portion, and covering the through transport roller from above to guide the transport of the sheet. One end of which is pivotally supported on the image forming apparatus side, and an upper guide plate that is openable and closable upward is provided around the fulcrum, and at least the through-conveyance roller A sheet curl removing device characterized in that a portion in contact with the sheet is formed of a material having low thermal conductivity. 2. A pressurizing device which releases the pressurization of the pair of frame-cutting rollers of the feed-through roller in conjunction with the opening of the upper guide plate and re-presses in conjunction with the closing of the guide plate. 2. A release means is provided.
The sheet curl removing device according to the above. 3. The through-conveying roller has a pressing force set to be weaker than the waist of the cardboard, and is provided so as to be swingable in a direction away from the frame-cutting roller in accordance with the strength of the waist. The sheet decurling apparatus according to claim 1, wherein 4. The pair of frame-cut rollers have the same outer diameter and are set slightly smaller than the outer diameters of the feed-through rollers, and are driven in the same manner so that their rotation speeds are equal to each other. 2. The sheet decurling apparatus according to claim 1, wherein the apparatus is driven by a mechanism.