JP2013133179A - Sheet transfer device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease a sound of impact generated by a sheet colliding against various guides each of which guides a sheet upon transferring a sheet delivered from a sheet delivery member via a pair of rollers.SOLUTION: Upon guiding a sheet S supplied from a sheet feeding cassette 11 to between a sheet feeding roller 14 and a separation roller 15 by virtue of an upstream outer guide 16 to deliver the sheet S from between the sheet feeding roller 14 and the separation roller 15 to between a downstream inner guide 16 and a downstream outer guide 17, a direction of a tangential line L on a contact part between the sheet feeding roller 14 and the separation roller 15 is controlled by a controller 100.

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet and an image forming apparatus using such a sheet conveying apparatus. In particular, when the paper fed from the paper carry-out unit is guided between a pair of rollers and the paper is conveyed through the pair of rollers, the paper collides with various guides that guide the paper and an impact sound is generated. It is characterized in that it can be reduced.

  In an image forming apparatus including a copying machine, a printer, a facsimile machine, and a combination of these, a sheet stored in a sheet storage unit such as a sheet feeding cassette is fed, and the fed sheet is conveyed through various paths. Image formation is performed.

  Here, when transporting the paper in this way, generally, the paper is guided between the pair of rollers through the guide member, and sequentially from the pair of rollers to the next pair of rollers through the next guide member. To guide you to.

  For example, when a sheet stored in the sheet storage unit is fed and transported, generally, the sheet stored in the sheet storage unit is fed by a pickup roller, and the fed sheet is fed by a guide member to a feed roller. If the paper is guided to the separation roller and double fed, the paper fed between the paper feeding roller and the separation roller is separated, and one sheet of paper is separated from this paper feeding roller. It guides to the next guide member from between the separation rollers.

  Here, when the paper is transported as described above, since the paper is generally transported in a curved state along the transport path, for example, the rear end of the paper is the above-described feed roller and separation roller. When moving away from the space, the return force of the bent paper acts on the trailing edge of the paper, the trailing edge of the paper collides with the next guide member, and a collision sound is generated. Even when the trailing edge of the paper guided between the paper feed roller and the separation roller from the storage section is separated from the paper storage section, the force to return the folded paper acts on the trailing edge of the paper. There is a problem in that the rear end of the paper collides with the previous guide member to generate a collision sound. In particular, when the device is downsized and the curvature of the transport path becomes large, or when stiff paper such as cardboard is transported, the force to return the folded paper becomes stronger, and the greater There was a problem that a collision sound was generated.

  And in what is shown by patent document 1, wind is blown with the ventilation fan on the curved outer peripheral part of the curved sheet conveyed, and the force in which the curved sheet returns is weakened, It has been proposed to reduce the collision noise when the end collides with the guide member.

  However, simply blowing the wind around the curved outer periphery of the paper in this way is a curved state when the curvature of the transport path increases or when stiff paper such as cardboard is transported It is difficult to sufficiently reduce the force for returning the paper, and in order to sufficiently reduce the force for returning the paper, a large blower fan is required, which increases costs and increases the size of the device. In addition, there was a problem such as increased noise from the blower fan.

  Moreover, in what is shown by patent document 2, in supplying the paper fed with the 1st roller from the tray to a pair of 2nd roller, this pair of 2nd roller is moved, The direction of the paper transport vector defined by the tangent line at the contact position of the pair of second rollers is changed, and when the rear end of the paper leaves the tray, the direction of the paper transport vector is loaded on the tray. It has been proposed to prevent the rear end of the sheet away from the tray from colliding with the sheet guide on the upstream side of the pair of second rollers in the sheet conveyance direction so as to face downward with respect to the sheet surface. Yes.

  However, in the one disclosed in Patent Document 2, the rear end of the sheet fed from the pair of second rollers collides with the sheet guide on the downstream side in the sheet transport direction from the pair of second rollers. The trailing edge of the paper carried out from the pair of second rollers collides with the paper guide on the downstream side in the paper transport direction from the pair of second rollers, and the There was still the problem of collision noise.

JP 2010-42910 A Japanese Patent Laid-Open No. 2007-31080

  In the present invention, when a sheet fed from a sheet carry-out unit is guided between a pair of rollers and the sheet is conveyed through the pair of rollers, the sheet collides with various guides for guiding the sheet, and an impact sound is generated. It is an object to be able to reduce this.

  In the paper transport device according to the present invention, in order to solve the above-described problem, the paper carried out from the paper carry-out unit for carrying out the paper is guided between the pair of rollers, and the paper is guided through the pair of rollers to the downstream side inner guide. And a downstream outer guide, a first state in which the sheet is guided between the pair of rollers from the sheet unloading unit, and the downstream inner guide and the downstream side between the pair of rollers. A line connecting the first point where the sheet contacts the downstream inner guide and the contact portion between the pair of rollers and the contact portion between the pair of rollers in the second state where the sheet is carried out between the outer guide and the outer guide The direction of the tangent at the contact portion between the pair of rollers is controlled by the control means so that the angle between the tangent and the second state is smaller than the first state.

  As described above, in the second state in which the paper is carried out between the pair of rollers and between the downstream inner guide and the downstream outer guide, the first point where the paper contacts the downstream inner guide and the pair of rollers. When the angle formed between the line connecting the contact portions and the tangent line at the contact portion between the pair of rollers is reduced, the paper is conveyed from between the pair of rollers toward the downstream inner guide, The bending of the sheet between the guide and the downstream outer guide is alleviated, and in this state, the trailing edge of the sheet is carried out between the pair of rollers and between the downstream inner guide and the downstream outer guide. This prevents the trailing edge of the paper from strongly colliding with the downstream outer guide.

  In the paper transport device of the present invention, an upstream outer guide is provided for guiding the paper carried out from the paper carry-out section between the pair of rollers, and the paper is fed from the paper carry-out section to the upstream outside. In the first state guided between the pair of rollers via the guide and the third state in which the rear end of the paper carried out from the paper carry-out unit is detached from the paper carry-out unit, the paper is carried out from the paper carry-out unit. The angle formed by the line connecting the second point and the contact portion between the pair of rollers and the tangent line at the contact portion between the pair of rollers is smaller in the third state than in the first state, The direction of the tangent at the contact portion between the pair of rollers can be controlled by the control means.

  Thus, the angle formed by the line connecting the second point where the paper is carried out from the paper carry-out portion and the contact portion between the pair of rollers and the tangent line at the contact portion between the pair of rollers is determined from the paper carry-out portion to the paper. If the trailing edge of the sheet is smaller in the third state where the trailing edge of the sheet is separated from the sheet unloading unit than the first state in which the sheet is guided between the pair of rollers via the upstream outer guide, the sheet is unloaded from the sheet unloading unit. The paper is conveyed linearly along the tangent line at the contact portion between the pair of rollers from the second point to be carried out toward the contact portion between the pair of rollers. Thus, the rear end of the sheet is prevented from strongly colliding with the upstream outer guide.

  Here, in the paper transport device, when the direction of the tangent at the contact portion between the pair of rollers is controlled by the control unit, at least one roller between the pair of rollers is moved, or the pair of rollers is moved. It is possible to change the contact state of the pair of rollers by changing the rotational speed of at least one of the pair of rollers.

  Further, as described above, in order to appropriately set the timing for controlling the direction of the tangent at the contact portion between the pair of rollers by the control means, a paper detection means for detecting the position of the paper to be conveyed may be provided. it can.

  In the image forming apparatus of the present invention, the paper is transported using the paper transport device as described above. By using such a paper transport device, for example, the paper stored in the paper storage unit can be fed and transported.

  In the paper transport device of the present invention, as described above, in the second state in which the paper is carried out between the pair of rollers and between the downstream inner guide and the downstream outer guide, the downstream inner guide and the downstream outer In a state where the curvature of the paper between the guide and the guide is relaxed, the rear end of the paper is carried out between the pair of rollers between the downstream inner guide and the downstream outer guide, and the rear end of the paper is on the downstream side. A strong collision with the outer guide is prevented, and an impact noise when the sheet is carried out between the pair of rollers between the downstream inner guide and the downstream outer guide is reduced.

  Further, in the third state in which the rear end of the paper carried out from the paper carry-out unit is detached from the paper carry-out unit, a line connecting the second point where the paper is carried out from the paper carry-out unit and the contact portion between the pair of rollers When the angle formed by the tangent at the contact portion between the pair of rollers is reduced, the pair of sheets of paper is moved from the second point where the sheet is unloaded from the sheet unloading section toward the contact section between the pair of rollers. It is conveyed in a straight line along the tangent line at the contact portion between the rollers. In this state, the trailing edge of the paper is separated from the paper carry-out portion, and the trailing edge of the paper is prevented from strongly colliding with the upstream outer guide. The impact sound when the trailing edge of the paper is removed from the paper carry-out portion is reduced.

1 is a schematic explanatory diagram illustrating an example of an image forming apparatus that uses a paper conveyance device according to an embodiment of the present invention. In the paper transport device according to the embodiment of the present invention, the control device moves the paper feed roller in the paper transport direction in contact with the separation roller based on the paper position detected by the paper detection means. FIG. 5 is a schematic explanatory view showing a state in which the direction of a tangent at a contact portion where a paper feed roller and a separation roller are in contact is controlled. In the paper transport device according to the above embodiment, the direction of the tangent at the contact portion where the paper feed roller and the separation roller contact is changed by moving the paper feed roller in the state of contact with the separation roller in the paper transport direction. 4A is a schematic explanatory diagram illustrating a state in which the paper feeding roller and the separation roller are in a first state, and FIG. 5B is a position of the paper feeding roller and the separation roller in a third state. (C) shows the positional relationship between the paper feed roller and the separation roller in the second state. FIG. 5 is a schematic explanatory view showing a first state in which a sheet fed from a sheet feeding cassette is guided between a sheet feeding roller and a separation roller via an upstream outer guide in the sheet conveying apparatus according to the embodiment. is there. FIG. 6 is a schematic explanatory view showing a third state in which the rear end of the paper guided between the paper feed roller and the separation roller from the paper feed cassette is separated from the paper feed cassette in the paper transport device according to the embodiment. is there. In the paper transport device according to the above-described embodiment, the rear end of the paper guided between the paper feed roller and the separation roller has a downstream inner guide and a downstream outer guide between the paper feed roller and the separation roller. It is the schematic explanatory drawing which showed the 2nd state carried out between. In the paper conveying apparatus which concerns on embodiment of this invention, it is the schematic explanatory drawing which showed the example of a change in the case of controlling the direction of the tangent in the contact part which a pair of roller contacts with a control apparatus.

  Next, a sheet conveying apparatus according to an embodiment of the present invention and an image forming apparatus using the sheet conveying apparatus will be specifically described with reference to the accompanying drawings. The sheet conveying device and the image forming apparatus according to the present invention are not limited to those shown in the following embodiments, and can be implemented with appropriate modifications within a range that does not change the gist thereof.

  In the image forming apparatus 1 of this embodiment, as shown in FIG. 1, a paper feed cassette 11 is used as a paper storage portion for storing the paper S, and the paper S is placed on the push-up plate 11 b in the paper feed cassette 11. I try to load it.

  Then, the push-up plate 11b is pushed upward by the spring 11a so that the sheets S stacked on the push-up plate 11b are pressed against the pickup roller 12. In this state, the pickup roller 12 is rotated to rotate the paper feed cassette 11 A pair of rollers including a sheet feeding roller 14 and a separation roller 15 are fed from the sheet feeding cassette 11 through the upstream outer guide 13. It is led to be carried out between.

  Further, when a plurality of sheets S fed by the pickup roller 12 are fed between the sheet feeding roller 14 and the separation roller 15, the sheet S is overlapped between the sheet feeding roller 14 and the separation roller 15. The fed paper S is separated, and the single paper S is conveyed between the downstream inner guide 16 and the downstream outer guide 17 through the paper feed roller 14 and the separation roller 15.

  Here, when separating the paper S that has been fed between the paper feed roller 14 and the separation roller 15 as described above, a torque limiter (not shown) is provided on the rotation shaft of the separation roller 15, The rotation limit force of the torque limiter is set to be larger than the friction force between the sheets S, and is set to be smaller than the friction force between the sheet S and the separation roller 15.

  In this way, when a single sheet S is fed between the paper feed roller 14 and the separation roller 15, the frictional force between the single sheet S and the separation roller 15 is as described above. The rotation limit force of the torque limiter is exceeded, and the separation roller 15 also rotates, so that one sheet S is conveyed between the paper feed roller 14 and the separation roller 15. Further, when two or more sheets S are fed between the sheet feeding roller 14 and the separation roller 15, since the frictional force between the sheets S is less than the rotation limiting force of the torque limiter, the separation roller 15 is Only one sheet S that does not rotate and is in contact with the paper feed roller 14 is conveyed between the paper feed roller 14 and the separation roller 15.

  As described above, the sheet S conveyed between the downstream inner guide 16 and the downstream outer guide 17 through the paper feed roller 14 and the separation roller 15 is transferred to the downstream inner guide 16 and the downstream outer guide. The paper S is guided to the pair of transport rollers 21 through the guide 17, and the paper S is sent from the transport rollers 21 to the pair of registration rollers 22. The paper is synchronized with the timing of image formation in the image forming unit 30 by the registration rollers 22. S is guided to the image forming unit 30.

  The image forming unit 30 includes an image forming unit 30Y for yellow, an image forming unit 30M for magenta, an image forming unit 30C for cyan, an image forming unit 30K for black, and an intermediate transfer. A belt 33 and a secondary transfer roller 34 are provided. Each of the image forming units 30Y, 30M, 30C, and 30K is provided with a photosensitive drum 31 on which a toner image is formed. Although not shown, a charging device, an exposure device, a developing device, a primary transfer roller, a cleaning device, and the like are provided around the periphery.

  The image forming unit 30 forms a toner image of each color on each photoconductive drum 31 in each image forming unit 30Y, 30M, 30C, and 30K based on the image information, and forms it on each photoconductive drum 31. The toner images of the respective colors are primarily transferred sequentially on the intermediate transfer belt 33 so that a full-color toner image is formed on the intermediate transfer belt 33.

  Then, the sheet S is transferred to the intermediate transfer belt 33 by the registration roller 22 in accordance with the timing when the full-color toner image formed on the intermediate transfer belt 33 is guided to the position facing the secondary transfer roller 34 in this way. The toner image formed between the intermediate transfer belt 33 and the secondary transfer roller 34 is transferred to one surface of the sheet S.

  Next, the sheet S on which the toner image is transferred to one side in this way is guided to the fixing unit 40 provided with the heating roller 41 and the pressure roller 42, and between the heating roller 41 and the pressure roller 42. Then, the sheet S on which the toner image is formed is heated and pressed to fix the toner image transferred on one side of the sheet S to the sheet S.

  When the sheet S having the toner image fixed on one side in this way is guided to the position of the switching claw 24 and single-sided printing is performed on the sheet S, the toner image is fixed on the one side by the switching claw 24. The discharged paper S is guided to the paper discharge roller 25, and the paper discharge roller 25 is rotated in the forward direction to discharge the paper S to the paper discharge unit 50.

  On the other hand, when performing double-sided printing on the paper S, the switching claw 24 is rotated to guide the paper S on which the toner image is fixed on one side to the reversing roller 26. After rotating in the forward direction, the sheet S is rotated in the reverse direction to guide the paper S to the reverse conveyance path 27, and the paper S is reversed to the registration roller 22 through the reverse conveyance path 27. Thereafter, a toner image is formed on the opposite surface of the sheet as described above.

  Here, in the paper transport device according to the embodiment of the present invention, the paper S fed from the paper feed cassette 11 by the pickup roller 12 as described above is separated from the paper feed roller 14 via the upstream outer guide 13. The paper S is guided between a pair of rollers composed of the rollers 15 to be carried out from the paper feed cassette 11 serving as a paper carry-out section, and the paper S guided between the paper feed roller 14 and the separation roller 15 is fed into the paper feed roller 14. And the separation roller 15 between the downstream inner guide 16 and the downstream outer guide 17.

  In this paper transport apparatus, as shown in FIG. 2, the paper detection means 18 composed of a detection sensor for detecting the position of the paper S transported from the paper feed cassette 11 is provided with the paper S rather than the pickup roller 12. The control unit 100 transports the sheet S in a state where the sheet feeding roller 14 is in contact with the separation roller 15 based on the position of the sheet S detected by the sheet detection unit 18. The direction of the tangent L at the contact portion where the paper feed roller 14 and the separation roller 15 are in contact with each other is controlled.

  Here, in this paper transport device, as shown in FIGS. 3 (A) to 3 (C), the control device 100 supplies the paper S based on the position of the paper S detected by the paper detection means 18 as described above. The paper roller 14 is moved in the conveyance direction of the paper S in a state where the paper roller 14 is in contact with the separation roller 15.

  In the first state in which the sheet S fed from the sheet cassette 11 by the pickup roller 12 is guided between the sheet feed roller 14 and the separation roller 15 via the upstream side outer guide 13, FIG. As shown in A), the paper feed roller 14 is positioned between the position shown in FIG. 3B and the position shown in FIG.

  In the third state in which the paper S fed by the paper feed roller 14 and the separation roller 15 is conveyed and the rear end of the fed paper S is detached from the paper feed cassette 11, FIG. ), The paper feed roller 14 is moved to the upstream side in the transport direction of the paper S from the position shown in FIG.

  In addition, the paper S is conveyed between the paper feed roller 14 and the separation roller 15, and the trailing edge of the paper S extends between the paper feed roller 14 and the separation roller 15 from the downstream inner guide 16 and the downstream outer side. In the second state where the paper is carried out between the guide 17 and the guide 17, as shown in FIG. 3C, the paper feed roller 14 is moved to the downstream side in the transport direction of the paper S from the position shown in FIG. I try to let them.

  When the paper feed roller 14 is moved from the first state shown in FIG. 3A to the third state shown in FIG. 3B, the trailing edge of the fed paper S is detached from the paper feed cassette 11. The angle θ2 formed by the second point P2 that is formed, the line Lb connecting the contact portion between the paper feed roller 14 and the separation roller 15, and the tangent line L at the contact portion where the paper feed roller 14 and the separation roller 15 contact each other is It will decrease.

  Further, when the paper feed roller 14 is moved from the first state shown in FIG. 3A to the second state shown in FIG. 3C, it is guided between the downstream inner guide 16 and the downstream outer guide 17. The line La connecting the first point P1 at which the sheet S is in contact with the downstream inner guide 16, the contact portion between the paper feed roller 14 and the separation roller 15, and the paper feed roller 14 and the separation roller 15 are in contact. The angle θ1 formed with the tangent L at the contact portion is reduced.

  In this sheet conveying apparatus, in the first state shown in FIG. 3A, as shown in FIG. 4, the sheet S fed from the sheet feeding cassette 11 is passed through the upstream outer guide 13. After being guided between the paper feed roller 14 and the separation roller 15, the paper feed roller 14 is moved upstream in the transport direction of the paper S before the rear end of the paper S is detached from the paper feed cassette 11. As shown in FIG. 3B, the angle θ2 is decreased. In this way, as shown in FIG. 5, the paper S fed from the paper feed cassette 11 is conveyed linearly along the tangent L at the contact portion where the paper feed roller 14 and the separation roller 15 come into contact. In this state, the rear end of the sheet S is detached from the paper feed cassette 11, and the rear end of the paper S is prevented from strongly colliding with the upstream side outer guide 13. The impact sound at the time of separation is reduced.

  In addition, after the trailing edge of the sheet S is detached from the sheet feeding cassette 11 in this way, the sheet feeding roller 14 is moved downstream in the conveyance direction of the sheet S, and the first state shown in FIG. After the sheet S is returned to the position before the trailing edge of the sheet S is unloaded between the sheet feeding roller 14 and the separation roller 15 between the downstream inner guide 16 and the downstream outer guide 17, the sheet feeding roller 14 is moved to the sheet. As shown in FIG. 3C, the angle θ1 is decreased by moving the sheet S downstream in the transport direction. In this way, as shown in FIG. 6, the trailing edge of the sheet S is in contact with the sheet feed roller 14 in a state where the curvature of the sheet S between the downstream inner guide 16 and the downstream outer guide 17 is relaxed. The sheet S is conveyed between the separation roller 15 and the downstream inner guide 16 and the downstream outer guide 17 so that the rear end of the sheet S is prevented from strongly colliding with the downstream outer guide 17. Impact noise when being carried out between the paper roller 14 and the separation roller 15 between the downstream inner guide 16 and the downstream outer guide 17 is reduced.

  In this embodiment, the paper S fed from the paper feed cassette 11 is guided between the paper feed roller 14 and the separation roller 15 via the upstream outer guide 13 and then fed. Although the paper transport device has been described as being carried out between the paper roller 14 and the separation roller 15 and between the downstream inner guide 16 and the downstream outer guide 17, the place where the paper transport device is used is particularly like this. The present invention is not limited to a specific paper feeding place, and can be used in various places where paper is transported.

  Further, in the paper transport device in this embodiment, the control device 100 moves the paper feed roller 14 in the transport direction of the paper S in a state where the paper feed roller 14 is in contact with the separation roller 15. Although the direction of the tangent line L in the contact portion in contact with 15 is controlled, the method of controlling the direction of the tangent line in the contact portion in contact with the pair of rollers is not limited to this.

  For example, as shown in FIG. 7, the rotating shafts 114a and 115a of the pair of rollers 114 and 115 are moved in the paper transport direction by biasing members 118 and 119 made of springs provided on the roller supports 116 and 117, respectively. In a state of being biased, the pair of rollers 114 and 115 are held by the roller supports 116 and 117 so as to be able to move in the paper transport direction, and the rotation speed of the rollers 114 and 115 is controlled by the control device 100. It is also possible to control the direction of the tangent L at the contact portion where the pair of rollers 114 and 115 are in contact with each other.

  In this case, when the pair of rollers 114 and 115 are rotated at a predetermined rotation speed and the pair of rollers 114 and 115 are in the first state, for example, When the rotation speed is decreased, the frictional force between the upper roller 114 and the paper increases, the upper roller 114 moves downstream in the paper conveyance direction, and the pair of rollers 114 and 115 are The third state is entered. On the other hand, when the rotation speed of the lower roller 115 is decreased, the frictional force between the lower roller 115 and the paper increases, and the lower roller 115 moves to the downstream side in the paper transport direction. The pair of rollers 114 and 115 are in the second state. And the direction of the tangent L in the contact part which a pair of roller 114,115 contacts can be appropriately controlled by controlling the rotational speed of a pair of roller 114,115 by the control apparatus 100 in this way.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Paper feed cassette (A paper storage part and a paper carry-out part)
12 Pickup roller 13 Upstream outer guide 14 Paper feed roller 15 Separating roller 16 Downstream inner guide 17 Downstream outer guide 18 Paper detection means 21 Transport roller 22 Registration roller 24 Switching claw 25 Paper discharge roller 26 Reverse roller 27 Reverse transport path 30 Image forming unit 40 Fixing unit 50 Paper discharge unit 100 Control devices 114, 115 Rollers 116, 117 Roller supports 118, 119 Biasing member P1 The sheet guided between the downstream inner guide and the downstream outer guide is downstream. First point P2 that comes into contact with the inner guide Second point L at which the rear end of the fed paper is removed from the paper feed cassette Tan line La at the contact portion where the paper feed roller and the separation roller make contact The first point P1 And a line Lb connecting the contact portion between the paper feed roller and the separation roller, and the second point P2 and the paper feed roller A line θ1 connecting the contact portion with the separation roller An angle θ2 formed by the La and the tangent L The angle S formed by the Lb and the tangent L

Claims (7)

  In a paper transport device that guides paper transported from a paper transporting section that transports paper to a pair of rollers, and transports the paper between the downstream inner guide and the downstream outer guide through the pair of rollers, the paper is paper In the first state where the paper is guided from the carry-out portion between the pair of rollers and the second state where the paper is carried out from the pair of rollers between the downstream inner guide and the downstream outer guide, the paper is in the downstream side. The angle formed by the line connecting the first point that contacts the side guide and the contact portion between the pair of rollers and the tangent line at the contact portion between the pair of rollers is in the second state rather than the first state. The sheet conveying apparatus is characterized in that the direction of the tangent at the contact portion between the pair of rollers is controlled by the control means so as to be small.   2. The paper conveying apparatus according to claim 1, wherein an upstream outer guide is provided for guiding the paper carried out from the paper carry-out unit between the pair of rollers, and the paper is provided from the paper carry-out unit to the upstream outside. In the first state guided between the pair of rollers via the guide and the third state in which the rear end of the paper carried out from the paper carry-out unit is detached from the paper carry-out unit, the paper is carried out from the paper carry-out unit. The angle formed by the line connecting the second point and the contact portion between the pair of rollers and the tangent line at the contact portion between the pair of rollers is smaller in the third state than in the first state, A sheet conveying apparatus, wherein the direction of a tangent at a contact portion between a pair of rollers is controlled by the control means.   3. The paper transport apparatus according to claim 1, wherein the control unit moves at least one of the pair of rollers to change a contact state of the pair of rollers. 4. apparatus.   The paper conveyance device according to any one of claims 1 to 3, wherein the pair of rollers are movably provided, and the control unit is configured to control a rotation speed of at least one of the pair of rollers. A sheet conveying apparatus characterized by changing the contact state of a pair of rollers.   5. The paper transport apparatus according to claim 1, further comprising a paper detection unit configured to detect a position of the paper to be transported.   6. An image forming apparatus comprising a sheet conveying apparatus for conveying a sheet, wherein the sheet conveying apparatus according to claim 1 is used.   7. The image forming apparatus according to claim 6, wherein the paper transporting device is used to feed and transport the paper stored in the paper storage unit.

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