JP2024000884A - Image formation device - Google Patents

Abstract

To stably convey hard paper such as thick paper, even if paper with guidance surfaces that are largely curved.SOLUTION: An image formation device comprises a movable guide 7 that has a first guide part 71 forming a first guide surface S1 for guiding paper, and also that is elastically supported so that a posture can be changed. The first guide surface S1 constitutes the lower surface of a first conveyance path 13A for conveying the paper, and has a curved shape when viewed from the width direction perpendicular to the paper conveyance direction. When the movable guide 7 receives pressure by a certain amount or more on the downstream side in a conveyance direction A1, the movable guide rotates in a first rotation direction R1 around a rotation axis 72, and the posture is changed so that the curvature on the downstream side of the first guide surface S1 becomes smaller.SELECTED DRAWING: Figure 3

Description

The present invention relates to an image forming apparatus that forms an image on paper.

When conveying paper in image forming devices such as copying machines and multifunction devices, if a large load is applied to the leading edge of the paper, problems such as increased paper rubbing noise and paper jams may occur. becomes higher. In particular, in the case of stiff paper such as cardboard, the load applied to the tip tends to be large. Patent Document 1 listed below discloses that when a load of more than a certain amount is applied to a conveyance guide plate that conveys paper, such as when conveying cardboard, the conveyance guide plate is displaced to widen the gap between each conveyance guide plate. , it is described that the load applied to the paper should be reduced.

JP2004-279486A

2. Description of the Related Art Some image forming apparatuses include a guide section that forms a guide surface that guides paper. Due to constraints on the layout of the main body of the image forming apparatus, the guide surface may become more curved (curvature becomes larger) on the downstream side in the paper conveyance direction. In particular, where a plurality of conveyance paths meet, the layout is severely restricted and the bends are often tight.

If the guide surface has a sharp bend on the downstream side, the load applied to the paper, especially the leading edge of the paper, will increase, increasing the possibility of problems such as rubbing noise and jamming occurring. There is not much of a problem with thin paper, but with stiff paper such as thick paper, the load cannot be ignored. Although the above-mentioned Patent Document 1 describes a technique for reducing the load applied to the paper, this technique does not reduce the curvature of the guide surface.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to enable stable conveyance of stiff paper such as cardboard even on a paper guide surface with a large curvature.

An image forming apparatus according to one aspect of the present invention includes an image forming section that forms an image on a sheet of paper, and one surface of a first conveyance path that conveys the sheet, parallel to a width direction perpendicular to a conveyance direction of the sheet. a first guide portion that forms a first guide surface that rotates in a direction toward and away from the other surface of the first conveyance path about a rotation axis extending in the first conveyance path; a biasing part that biases the other surface of the road; and a biasing part that restricts movement of the first guide part due to the bias of the biasing part, so that the first guide surface is separated from the other surface by a certain distance. a movable guide including a regulating portion that allows the movable guide to remain at the initial position, the first guide surface having a curved shape when viewed from the width direction, and the first guide portion having a movable guide that When the paper being conveyed through the first conveyance path receives a pressure equal to or greater than a predetermined amount, the initial pressure is moved away from the other surface against the biasing force of the biasing section. It rotates from position.

According to the present invention, when the first guide part is pressed by a predetermined amount or more by the paper at the curved portion during paper conveyance, the first guide part resists the biasing force of the biasing part and moves toward the first conveyance path. Since it rotates in the direction away from the other surface, this rotation allows the pressure applied when the leading edge of the paper comes into contact with the first transport path to be released, thereby reducing the load applied to the leading edge of the paper at the time of contact. can also be made smaller.

Frequently changing the posture of the movable guide is not very desirable when considering the durability of the movable guide, but the first guide portion does not change its posture unless it receives a certain amount of pressure or more. Therefore, when the pressure is not strong, such as when thin paper is being conveyed, the first guide section does not change its posture.

Therefore, the operation of changing the posture of the first guide section is performed only when a stiff cardboard or the like is being conveyed and the pressure becomes strong. As a result, it is possible to stably convey even stiff paper such as cardboard without reducing the durability of the movable guide, reduce rubbing noise, and prevent problems such as jamming.

1 is a perspective view showing the appearance of an image forming apparatus according to an embodiment of the present invention. FIG. 1 is a front sectional view schematically showing the configuration of an image forming apparatus. FIG. 3 is a front cross-sectional view schematically showing the configuration of a paper feeding unit included in an upper paper feeding cassette and its surroundings. FIG. 3 is a front cross-sectional view schematically showing the configuration of a paper feeding unit included in an upper paper feeding cassette and its surroundings. (A) and (B) are diagrams showing a state when the trailing edge of the paper passes between the first guide surface and the second guide surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the appearance of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is a multifunction device that has multiple functions such as a copy function, a printer function, a scanner function, and a facsimile function. , an image forming section 12 , a paper feeding section 14 , and an operation section 47 .

The document feeding section 6 is configured to be openable and closable by a hinge (not shown) on the top surface of the document reading section 5, and the document feeding section 6 is configured to be able to open and close the document placed on a platen glass (not shown). Functions as a holding cover. The document feeder 6 is an automatic document feeder called ADF (Auto Document Feeder), and is equipped with a document placement tray 61 and transfers the document placed on the document placement tray 61 to the document reading section 5. Supply one by one.

A case where the image forming apparatus 1 performs a document reading operation will be described. The original reading unit 5 optically reads the image of the original supplied to the original reading unit 5 by the original feeding unit 6 or placed on the platen glass, and generates image data. The image data generated by the document reading section 5 is stored in an unillustrated image memory or the like.

A case where an image forming operation is performed in the image forming apparatus 1 will be described. Based on the image data generated by the document reading operation or the image data received from a computer as an external device (for example, a personal computer) connected to a network, the image forming section 12 generates a recording sheet fed from the paper feeding section 14. A toner image is formed on paper as a medium.

The sheet of paper on which the toner image has been formed by the image forming section 12 is then subjected to a fixing process and is discharged to the discharge tray 151. The paper feed section 14 includes a plurality of paper feed cassettes 141A and 141B.

The operation unit 47 receives instructions from an operator regarding various operations and processes that can be executed by the image forming apparatus 1, such as an instruction to execute an image forming operation. The operation unit 47 includes a display unit 473 that displays operation guidance for the operator.

FIG. 2 is a front sectional view schematically showing the configuration of the image forming apparatus 1. As shown in FIG. The image forming section 12 includes an intermediate transfer unit 120, photosensitive drums 121 for black, magenta, cyan, and yellow, and a secondary transfer roller 122.

The intermediate transfer unit 120 includes an intermediate transfer belt 1201 to which a toner image is transferred to the outer peripheral surface thereof, a driving roller 1202, a driven roller 1203, and a primary transfer roller 1204.

The secondary transfer roller 122 forms a nip portion 31 with the drive roller 1202, which transfers the toner image onto the paper P conveyed from the paper feed unit 14 via the conveyance path 13 indicated by a broken line.

The registration roller pair 131 is provided along the conveyance path 13 on the upstream side of the nip portion 31 (that is, the image forming position where an image is formed in the image forming portion 12) in the conveyance direction of the paper P, and is located near the paper feed portion. The paper P conveyed from 14 is stopped, and the timing for conveying the paper P to the nip portion 31 is adjusted.

The paper feed unit 14 is configured to be removably inserted into the apparatus main body 11 (FIG. 1), and includes a paper feed cassette 141A that stores paper P and can be pulled out from the back side to the front side of the apparatus main body 11. , 141B, and a paper feeding unit 142 for each paper feeding cassette 141A, 141B.

The first conveyance path 13A that conveys the paper P is formed by the paper feed unit 142 included in the upper paper feed cassette 141A, and the second conveyance path 13B that conveys the paper P is formed by the paper feed unit 142 provided in the lower paper feed cassette 141B. It is formed by unit 142. Further, the first conveyance path 13A and the second conveyance path 13B merge on the upstream side of the pair of registration rollers 131.

The paper feed unit 142 includes an upper guide unit 21 that forms the upper surface of the first transport path 13A or the second transport path 13B for the paper P, and a lower surface of the first transport path 13A or the second transport path 13B for the paper P. It includes a guide unit 22, a pickup roller 23, a feed roller 24, and a retard roller 25.

The pickup roller 23 and the feed roller 24 are rotatably held by the upper guide unit 21 about rotating shafts 231 and 241, respectively. The retard roller 25 is rotatably held by the guide unit 22 around a rotating shaft 251.

The pickup roller 23 is provided to face the upper surface of the uppermost sheet P stored in the paper feed cassettes 141A, 141B, and picks up and sends out the sheet P by rotating in contact with the upper surface. The feed roller 24 transports the paper P sent out by the pickup roller 23. The retard roller 25 forms nip portions 32A and 32B that sandwich the paper P with the feed roller 24, and conveys the paper P while handling it.

The feed roller 24 rotates around a rotating shaft 241 connected to an unillustrated drive motor (drive source). A drive source transmission gear (not shown) is disposed between the pickup roller 23 and the feed roller 24, and when the feed roller 24 rotates, the pickup roller 23 is rotated about the rotating shaft 231 via the drive source transmission gear. and rotates in the same direction as the feed roller 24. The retard roller 25 is pressed against the feed roller 24 and rotates around the rotating shaft 251 .

3 and 4 are front sectional views schematically showing the structure of the paper feed unit 142 included in the upper paper feed cassette 141A and its surroundings. The movable guide 7 is a first guide that is disposed downstream of the guide unit 22 in the transport direction A1 of the paper P and forms a first guide surface S1 that guides the paper P that is transported from the paper feed unit 142. 71 (shown in gray in FIGS. 3 and 4).

The first guide surface S1 constitutes the lower surface of the first conveyance path 13A, and has a curved shape when viewed from the width direction perpendicular to the conveyance direction A1 (as viewed from the side from the direction).

The guide unit 22 includes a second guide portion 26 that forms a second guide surface S2 that guides the paper P sent out by the pickup roller 23 and the paper P separated by the nip portion 32A. The second guide part 26 is arranged upstream of the first guide part 71 in the transport direction A1, and the second guide surface S2 forms the lower surface of the first transport path 13A, like the first guide surface S1.

The movable guide 7 is arranged such that the first guide surface S1 is connected to the second guide surface S2 in the transport direction A1.

Furthermore, the movable guide 7 further includes a third guide portion 73 forming a third guide surface S3 that guides the paper P, and the third guide surface S3 is conveyed from the lower paper feed cassette 141B (FIG. 2). It constitutes the other surface (lower surface in FIG. 3) of the second conveyance path 13B that conveys the paper P that has arrived. The fixed guide 8 constitutes one surface (the upper surface in FIG. 3) of the second conveyance path 13B.

The first guide portion 71 has its downstream end disposed at a position where the first conveyance path 13A and the second conveyance path 13B merge. One surface of the downstream end of the first guide section 71 constitutes one surface (the lower surface in FIG. 3, the first guide surface S1) of the first conveyance path 13A, and the other surface constitutes the second conveyance path 13A. It constitutes the other side of the passage 13B.

The first guide section 71 and the third guide section 73 are supported by the apparatus main body 11 so as to be rotatable about a rotation shaft 72 that extends parallel to the width direction orthogonal to the conveyance direction A1. The first guide part 71 and the third guide part 73 are arranged in a first rotation direction R1 (clockwise direction in FIGS. 3 and 4) with the rotation axis 72 as the center; the other side of the first conveyance path 13A (in FIG. When it reaches one side (a part of the fixed guide 8) of the second transport path 13B, the rotation is stopped. That is, the fixed guide 8 serves as a stopper that restricts the rotation of the first guide part 71 and the third guide part 73 in the first rotation direction R1. The fixed guide 8 prevents the rotation of the first guide part 71 in the direction away from the other surface of the first transport path 13A by bringing the tip of the first guide part 71 into contact with one surface of the second transport path 13B. regulate.

Further, the first guide portion 71 and the third guide portion 73 are restricted by the restriction portion 92 from rotating in a direction toward the other surface of the first conveyance path 13A. Further, a biasing portion 91 is provided that biases the first guide portion 71 toward the other surface of the first conveyance path 13A. The biasing section 91 and the regulating section 92 are arranged outside the area in which the paper P is conveyed in the width direction of the paper P, and do not interfere with the conveyance of the paper P.

That is, the movable guide 7 includes a first guide section 71, a biasing section 91 that biases the first guide section 71 toward the other side of the first conveyance path 13A, and a first guide section 91 biased by the biasing section 91. A regulating section 92 is provided that regulates the movement of the section 71 and causes the first guide surface S1 to remain at an initial position (the position shown in FIG. 3) a certain distance away from the other surface.

The biasing portion 91 is, for example, a tension spring, and the first guide portion 71 is rotated in a second rotation direction R2 opposite to the first rotation direction R1 (counterclockwise direction in FIGS. 3 and 4). (a direction approaching the other surface of the first conveyance path 13A). The regulating part 92 comes into contact with the first guide part 71, regulates the rotation of the first guide part 71 in the second rotation direction R2, and functions as a stopper.

When the first guide portion 71 is pressed by a predetermined amount T or more as a force exceeding the biasing force of the biasing portion 91 in the curved portion, the biasing portion 91 extends and rotates the rotating shaft 72. It rotates around the center in the first rotation direction R1. At this time, the first guide portion 71 changes its attitude so that the curvature on the downstream side of the first guide surface S1 becomes smaller, as shown in FIG. On the other hand, when the first guide portion 71 is not pressed by a certain amount T or more at the curved portion of the first guide surface S1 on the downstream side in the conveyance direction A1, the first guide portion 71 assumes a posture as shown in FIG. keep. In this way, the movable guide 7 is supported so that its posture can be changed.

Further, in the state shown in FIG. 3, the first guide portion 717 is located at a position where the first guide surface S1 is lower in FIG. 3 than flush with the second guide surface S2, that is, the second guide surface The position extends in the transport direction from a position farther from the other surface of the first transport path 13A than S2. That is, when the first guide portion 71 is not pressed by a certain amount T or more in the curved portion, the upstream end of the first guide surface S1 is in contact with the downstream end of the second guide surface S2. The position extends in the transport direction A1 from the flush position. On the other hand, in the state shown in FIG. 4, the first guide portion 71 is located at a position above where the first guide surface S1 is flush with the second guide surface S2, that is, from the second guide surface S2. also changes from a position close to the other surface of the first conveyance path 13A to a posture extending in the conveyance direction A1.

Further, when the first guide portion 71 is not pressed by the predetermined amount T or more by the sheet P conveyed through the first conveyance path 13A in the curved portion, the first guide portion 71 is moved to the second guide portion at the downstream end in the conveyance direction A1. The surface on the conveyance path 13B side is arranged flush with the downstream end of the third guide surface S3 in the conveyance direction A1.

According to the above embodiment, when the first guide part 71 receives a pressure of a certain amount T or more from the paper P on the downstream side in the transport direction A1 when the paper P is transported, the downstream curvature of the first guide surface S1 Since the rotation is performed to change the posture so that The load applied to the leading edge of the paper upon contact can also be reduced.

Frequently changing the posture of the first guide section 71 is not very desirable when considering the durability of the first guide section 71, but unless the first guide section 71 receives a certain amount of pressure or more, the posture do not change. Therefore, when the pressure is not strong, such as when thin paper is being conveyed, the first guide portion 71 does not change its posture.

Therefore, the operation of changing the posture of the first guide section 71 is performed only when a stiff cardboard or the like is being conveyed and the pressure becomes strong. As a result, it is possible to stably convey even stiff paper such as cardboard without reducing the durability of the first guide section 71, reduce rubbing noise, and prevent problems such as jamming. .

According to this embodiment, even stiff paper such as cardboard can be stably conveyed on the paper guide surface with a large curvature.

Furthermore, if the amount of rotation of the movable guide 7 in the first rotation direction R1 becomes too large, there will be no level difference margin for transferring the paper P to the guide on the downstream side in the conveyance direction, and the transfer may not be performed properly. Since the fixed guide 8 serves as a stopper to restrict the rotation of the movable guide 7 in the first rotation direction R1, the level difference between the first guide surface S1 and the second guide surface S2 can be suppressed to an expected value. Therefore, it is possible to prevent the above-mentioned step difference tolerance from disappearing. Further, since there is no need to provide a member dedicated to the above-mentioned regulation, it is possible to prevent the device from becoming complicated.

Further, since the movable guide 7 has the third guide portion 73 that forms the other surface (third guide surface S3) of the second conveyance path 13B, it is possible to reduce the number of parts in the same way as described above, and the number of parts can be reduced. Complications can be prevented.

FIGS. 5A and 5B are diagrams showing a state when the trailing edge of the sheet P passes between the first guide surface S1 and the second guide surface S2. As shown in FIG. 5(A), when the first guide surface S1 extends in the transport direction A1 from a position lower than that in FIG. 5(A) than is flush with the second guide surface S2, the first guide surface When the trailing edge of the paper P, which has a strong stiffness, passes between the surface S1 and the second guide surface S2, the trailing edge of the paper P bounces and collides with nearby members, causing impact noise, etc. Problems may occur.

On the other hand, as shown in FIG. 5(B), when the first guide surface S1 extends in the conveying direction A1 from a position above the second guide surface S2 so as to be flush with the second guide surface S2, the paper P as described above is Bouncing of the rear end is less likely to occur.

According to the embodiment described above, when the first guide portion 71 receives a pressure of a certain amount T or more at the curved portion on the downstream side in the conveyance direction A1, the first guide portion 71 rotates in the first rotation direction R1 about the rotation shaft 72. Then, as shown in FIGS. 4 and 5(B), the first guide surface S1 changes from a position above the second guide surface S2 to extend in the transport direction A1. That is, when the first guide portion 71 receives a pressure of the certain amount or more in the curved portion, the upstream end of the first guide surface S1 becomes flush with the downstream end of the second guide surface S2. It assumes a posture extending in the transport direction A1 from the position where .

Therefore, when paper P with strong stiffness such as thick paper is transported, the first guide surface S1 extends in the transport direction A1 from a position above the second guide surface S2 so that it is flush with the second guide surface S2. It is possible to suppress the bouncing of the rear end.

In the above embodiment, when the first guide part 71 is not pressed by a certain amount T or more, as shown in FIG. Although a case has been described in which the first guide section 71 maintains a posture extending in the conveying direction A1 from a position lower than flush with S2, as another embodiment, the first guide section 71 has a position in which the first guide surface S1 is It is also possible to maintain a posture extending in the transport direction A1 from a position flush with the second guide surface S2, rather than from a position below it.

Furthermore, in the above embodiment, when the first guide part 71 receives a pressure of a certain amount T or more, as shown in FIG. However, in another embodiment, the first guide section 71 has a position where the first guide surface S1 is in the second direction. It may be configured such that the posture changes from a position flush with the guide surface S2, rather than from a position above the guide surface S2, to a posture extending in the conveyance direction A1.

The present invention is not limited to the configuration of the embodiments described above, and various modifications are possible. For example, in the above embodiment, an example is shown in which the movable guide 7 is disposed on the conveyance path that is downstream in the conveyance direction of the paper P of the paper feed unit 142, but the movable guide 7 is disposed in a limited location. Instead, it may be placed on another sheet or document conveyance path that has a large curvature. Further, a case is described in which the first guide portion 71 is arranged such that the downstream end in the conveyance direction A1 becomes a confluence point of a plurality of conveyance paths (first conveyance path 13A, second conveyance path 13B). However, the first guide portion 71 may be arranged at a location other than the merging point.

Furthermore, in the embodiment described above, the configuration and processing shown in the embodiment using FIGS. 1 to 5 are merely one embodiment of the present invention, and the present invention is not intended to be limited to the configuration and processing.

1 Image forming device 7 Movable guide 8 Fixed guide 13A First conveyance path 13B Second conveyance path 26 Second guide section 71 First guide section 73 Third guide section 91 Biasing section 92 Regulating section

Claims (4)

an image forming unit that forms an image on paper;
A direction of approaching and separating from the other surface of the first conveyance path, with a rotating shaft that constitutes one side of the first conveyance path that conveys the paper and extends parallel to the width direction orthogonal to the conveyance direction of the paper as a fulcrum; a first guide part that forms a first guide surface that rotates; a biasing part that biases the first guide part toward the other surface of the first conveyance path; and a biasing part that is biased by the biasing part. a movable guide comprising a regulating part that regulates movement of the first guide part and causes the first guide surface to remain at an initial position a certain distance away from the other surface;
The first guide surface has a curved shape when viewed from the width direction,
The first guide section is configured to resist the biasing force of the biasing section when the curved portion is pressed by a predetermined amount or more by the paper conveyed through the first conveyance path. , an image forming apparatus that rotates from the initial position in a direction away from the other surface; Further comprising a guide unit having a second guide portion forming a second guide surface for guiding the paper,
The second guide part is arranged upstream of the first guide part in the conveyance direction,
The second guide surface constitutes the one surface of the first conveyance path,
The movable guide is arranged downstream of the guide unit at a position where the first guide surface is connected to the second guide surface in the conveyance direction,
Furthermore, the first guide part is
a position where the upstream end of the first guide surface is flush with the downstream end of the second guide surface when the curved portion is not pressed by the paper by the predetermined amount or more; or in a posture extending in the conveying direction from a position further away from the other surface than the surface,
When the curved portion is pressed by the paper by the predetermined amount or more, the upstream end of the first guide surface is flush with the downstream end of the second guide surface, or The image forming apparatus according to claim 1, wherein the image forming apparatus assumes a posture extending in the conveying direction from a position closer to the other surface than flush with the other surface. further comprising a fixed guide that faces the third guide surface of the movable guide and configures one side of a second conveyance path that conveys the paper;
The movable guide further includes a third guide portion forming a third guide surface constituting the other surface of the second conveyance path,
The first guide part has a downstream end in the transport direction forming a confluence point of the first transport path and the second transport path,
One surface of the downstream end of the first guide portion constitutes the one surface of the first conveyance path, and the other surface constitutes the other surface of the second conveyance path,
The fixed guide restricts rotation of the first guide part in a direction away from the other surface of the first transport path by bringing the tip of the first guide part into contact with one surface of the two transport paths. The image forming apparatus according to claim 2. When the first guide portion is not pressed by the predetermined amount or more by the sheet conveyed through the first conveyance path in the curved portion, the first guide portion is configured to move the tip of the downstream end toward the second conveyance path in the conveyance direction. 4. The image forming apparatus according to claim 3, wherein the surface is disposed flush with the downstream end of the third guide surface in the conveying direction.