JP2019189367A - Sheet conveying apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably convey various sheets while reducing the occurrence of sheet wrinkles. A sheet conveying device has a projecting portion (135) capable of contacting a sheet at a front end portion (P2) extending in the width direction with respect to a sheet (S) conveyed in a sheet conveying path (140). The projecting portion is arranged so as to project toward the first guide side with respect to the shortest path from the sheet conveying means (121) to the registration means (131) when viewed from the width direction, and toward the second guide side. It can be displaced toward. [Selection diagram] Fig. 6

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet and an image forming apparatus that forms an image on the sheet.

  Some sheet conveying apparatuses used in image forming apparatuses such as printers, copiers, and multifunction machines correct the skew of the sheet by bending the leading edge of the sheet against a pair of stopped registration rollers. is there. It has been known for some time that when a registration roller pair sandwiches and conveys a sheet while the sheet is wavy, the wavy portion is nipped by the roller pair and wrinkles may occur.

  Patent Document 1 describes a configuration in which a bent portion of a guide plate is provided on the upstream side of a registration roller pair, and a sheet pulled by the registration roller pair frictionally contacts the bent portion. According to this document, since the sheet is conveyed while being in frictional contact with the bent portion, the tensile force acting on the sheet is dispersed over a wide range in the width direction, so that the waviness of the sheet due to the uneven distribution of force is reduced. Is done.

JP-A-5-58500

  In recent years, sheets used as recording media have been diversified, and there is a demand for a sheet conveying apparatus that can handle various sheets including sheets having a large basis weight and sheets having a small basis weight. However, in the configuration of Patent Document 1, when a sheet having a large basis weight is conveyed, a large conveyance resistance may occur due to the bent portion coming into contact with the sheet, resulting in conveyance failure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet conveying apparatus and an image forming apparatus that can stably convey various sheets while reducing the occurrence of sheet wrinkles.

  A sheet conveying apparatus according to an aspect of the present invention is disposed downstream of the sheet conveying unit in the sheet conveying direction by sandwiching a sheet and conveying the sheet in the sheet conveying direction, and can correct skew of the sheet In addition, the sheet is curved when viewed from the width direction perpendicular to the sheet conveying direction, and the sheet is guided between the registration unit capable of nipping and conveying the sheet, and the sheet conveying unit and the registration unit. A sheet conveyance path having a first guide disposed so as to be positioned outside the curved sheet and a second guide disposed so as to be positioned inside the curved sheet. And can contact the sheet at the leading end extending in the width direction, and when viewed from the width direction, from the sheet conveying means, the first guide and the A projecting portion projecting from the second guide side to the first guide side in a crossing direction intersecting the shortest path with respect to the shortest path toward the registration means passing between the two guides. The projecting portion is displaceable toward the second guide in the intersecting direction.

  According to the present invention, it is possible to stably convey various sheets while reducing the generation of wrinkles on the sheets.

1 is a schematic diagram of an image forming apparatus according to the present disclosure. FIG. 2 is a schematic diagram (a) of a sheet conveying device according to a first embodiment, a schematic diagram (b) for illustrating arrangement of members, and a schematic diagram (c) illustrating a modification of the sheet conveying device. In Example 1, it is the schematic which shows the state which tension | tensile_strength has generate | occur | produced in the sheet | seat. FIG. 3 is a perspective view of the sheet conveying apparatus according to the first embodiment. In Example 1, it is a perspective view which shows the state which tension | tensile_strength has generate | occur | produced on the one side of the sheet | seat. FIG. 3 is a schematic diagram illustrating a state in which a highly rigid sheet is conveyed in the first embodiment. Schematic (a) which shows the state which tension | tensile_strength has generate | occur | produced about the sheet | seat conveying apparatus which concerns on Example 2, and schematic (b) which shows a mode that the sheet | seat with high rigidity is conveyed. Schematic diagram (a) showing a state where tension is generated in the sheet, schematic diagram (b) showing a state where a sheet having high rigidity is being conveyed, and a block diagram showing a control configuration for the sheet conveying apparatus according to the third embodiment. (C) and the flowchart (d) showing the position determination process of a guide plate.

  Hereinafter, an image forming apparatus according to the present disclosure will be described with reference to the drawings. The image forming apparatus includes a printer, a copier, a facsimile machine, and a multifunction machine, and forms an image on a sheet used as a recording medium based on image information input from an external computer or image information read from a document. Sheets used as recording media include paper such as plain paper and cardboard, plastic films such as overhead projector sheets, specially shaped sheets such as envelopes and index paper, and cloth.

  As shown in FIG. 1, the image forming apparatus 100 includes an apparatus main body 100A that houses an image forming unit 150, and an image reading apparatus 300 that is disposed above the apparatus main body 100A and reads image information from a document. An image forming unit 150 as an example of an image forming unit is an intermediate transfer tandem type electrophotographic system including four image forming units PY, PM, PC, and PK and an intermediate transfer belt 155. The image forming unit 150 transfers the toner images formed by the image forming units PY to PK to the sheet S via the intermediate transfer belt 155. The configuration of each of the image forming units PY to PK is basically the same except that the color of the toner used for development is different. Therefore, the configuration of the image forming unit and the toner image forming operation are exemplified by using the yellow image forming unit PY as an example. Will be described.

  When the image forming unit PY is requested to form a toner image, the photosensitive drum 151 as a photosensitive member is rotationally driven, and the charging device uniformly charges the surface of the photosensitive drum 151. The exposure device 152 provided in the lower part of the apparatus main body 100A irradiates the photosensitive drum 151 with laser light based on image information to expose the drum surface, and forms an electrostatic latent image on the photosensitive drum 151. Then, the electrostatic latent image is visualized (developed) by the toner supplied from the developing device 153, whereby a toner image is formed on the surface of the photosensitive drum 151.

  Similarly, in the image forming units PM, PC, and PK, a corresponding color toner image is formed on the photosensitive drum. The toner images formed by the image forming units PY to PK are primarily transferred by the primary transfer roller 154 from the photosensitive drum 151 to the intermediate transfer belt 155 that is an intermediate transfer member. Deposits such as toner remaining on the photosensitive drum 151 are removed by a cleaning device provided in each of the image forming units PY to PK.

  The intermediate transfer belt 155 is wound around the secondary transfer inner roller 156, the tension roller 157, and the stretching roller 158, and is driven to rotate counterclockwise in the drawing. The toner image carried on the intermediate transfer belt 155 is secondarily transferred to the sheet S at a secondary transfer portion formed between the secondary transfer roller 159 and the intermediate transfer belt 155 facing the secondary transfer inner roller 156. The Deposits such as toner remaining on the intermediate transfer belt 155 are removed by a belt cleaning device. The sheet S to which the toner image is transferred is transferred to the fixing device 160. The fixing device 160 includes a pair of fixing rollers that sandwich and convey the sheet S and a heat source that heats the sheet S, and applies heat and pressure to the toner image while conveying the sheet S. Thereby, an image in which the toner is melted and fixed and fixed on the sheet S is obtained.

  In parallel with such an image forming process, a feeding operation for feeding the sheet S from the cassette feeding unit 110 or the manual feed unit 115 toward the sheet S is executed. The cassette feeding unit 110 includes a feeding cassette 111 as a sheet supporting unit, and a feeding unit 112 that feeds the sheet S from the feeding cassette 111. The manual feeding unit 115 includes a manual tray 116 which is another example of the sheet supporting unit, and a feeding unit 117 which feeds the sheet S set on the manual tray 116. The feeding units 112 and 117 include feeding rollers 112a and 117a that feed the sheet S, and separation rollers 112b and 117b that separate the sheet S conveyed by the feeding rollers 112a and 117b from other sheets. The feeding units 112 and 117 are an example of a sheet feeding unit that feeds the sheet S, and may be replaced with another feeding mechanism such as a separation pad method or an air feeding method.

  The sheet S fed by the feeding units 112 and 117 is conveyed to the pre-transfer conveying unit 101 via the drawing roller pairs 113 and 118. As will be described in detail later, the pre-transfer conveyance unit 101 corrects the skew of the sheet S and sends the sheet S to the secondary transfer unit at a timing that matches the progress of the image forming process by the image forming unit 150.

  The sheet S on which an image has been formed by passing through the secondary transfer unit and the fixing device 160 is transferred to a discharge path 172 of the sheet discharge unit 170, and the discharge roller pair 171 causes the apparatus main body 100A and the image reading apparatus 300 to move. The paper is discharged to a discharge tray 180 provided therebetween. When duplex printing is performed, the sheet S is switchback conveyed by the discharge roller pair 171 that is a pair of reversing rollers and is transferred to the duplex conveyance unit 190, and is conveyed via the duplex path 192 by the conveyance roller pair 193. The sheet S that has reached the pre-transfer conveyance unit 101 is again formed on the back surface by the image forming unit 150 and then discharged to the discharge tray 180 by the discharge roller pair 171.

  The image forming unit 150 is an example of an image forming unit, and a direct transfer type electrophotographic unit or an ink jet type image forming unit may be used.

  Next, the pre-transfer conveying unit 101 as the sheet conveying apparatus according to the first example (Example 1) will be described. As shown in FIG. 1, the pre-transfer conveyance unit 101 includes a registration roller pair (hereinafter referred to as a registration roller pair) 131 and a pre-registration conveyance roller pair (hereinafter referred to as a conveyance roller pair) arranged upstream thereof. 121. The registration roller pair 131 is a registration unit that can correct the skew of the sheet in the present embodiment and can convey the sheet while sandwiching the sheet. The conveying roller pair 121 is a sheet conveying unit in this embodiment. Hereinafter, the direction along the path in which the sheet sequentially moves through the conveying roller pair 121 and the registration roller pair 131 is referred to as a sheet conveying direction.

  As shown in FIG. 2A, the pre-transfer conveying unit 101 includes an in-loop guide 132 and an out-loop guide 133. The outer loop guide 133 and the inner loop guide 132 are arranged to face each other, and constitute a sheet conveyance path 140 that guides the sheet S fed from the conveyance roller pair 121 toward the registration roller pair 131. The loop outer guide 133 is the first guide of this embodiment, and the loop inner guide 132 is the second guide of this embodiment.

  The conveying roller pair 121 includes a driving roller 121a that is driven by a conveying motor and a driven roller 121b that is pressed against the driving roller 121a by a biasing member such as a spring. The registration roller pair 131 includes a driving roller 131a that is driven by a registration motor and a driven roller 131b that is pressed against the driving roller by a biasing member such as a spring.

  The outer loop guide 133 and the inner loop guide 132 form a space between the conveying roller pair 121 and the registration roller pair 131 that allows the sheet S to be curved as viewed from the width direction. Hereinafter, the curvature of the sheet S in the pre-transfer conveyance unit 101 is referred to as “loop”.

  The loop outer guide 133 has a shape that swells in a direction away from a straight line L0 (left in the drawing) connecting the nip portion N1 of the conveying roller pair 121 and the nip portion N2 of the registration roller pair 131 (see FIG. 2B). . Further, at least a part of the in-loop guide 132 protrudes on the same side as the outer loop guide 133 with respect to the straight line L0. Therefore, the outer loop guide 133 is outside the loop shape of the sheet S, and the inner loop guide 132 is inside the loop shape. In other words, when the surface of the sheet S facing the outer loop guide 133 is the first surface and the surface of the sheet S facing the inner loop guide 132 is the second surface, the sheet passing through the sheet conveying path 140 is: A loop is formed in which the first surface of the sheet S is convex when viewed from the width direction.

  Here, a resin sheet 135 is affixed to the in-loop guide 132. The resin sheet 135 is a protruding portion that can contact the sheet at the tip portion in this embodiment. A part of the guide 132 in the loop is provided with a flat surface 134 for sticking, and one end of the resin sheet 135 viewed from the width direction is fixed to the flat surface 134 by a double-sided tape, an adhesive, or the like. The other end (tip portion P <b> 2) of the resin sheet 135 protrudes into the internal space of the sheet conveyance path 140 at an angle along the plane 134, and a gap is provided between the resin sheet 135 and the loop outer guide 133.

  As shown in FIG. 3, the front end position of the resin sheet 135 is such that the second surface of the sheet S contacts the resin sheet 135 when the sheet S is pulled between the registration roller pair 131 and the conveyance roller pair 121. Is set to Specifically, when viewed from the width direction, the front end portion P2 of the resin sheet 135 protrudes toward the outer loop guide 133 in the thickness direction V1 of the sheet S with respect to the shortest path L1 of the sheet conveyance path 140. . However, the shortest path of the sheet conveyance path 140 is a nip portion between the conveyance roller pair 121 and the registration roller pair 131 in the cross section viewed from the width direction, ignoring the resin sheet 135 and passing through the inside of the sheet conveyance path 140. It indicates the shortest virtual line connecting N1 and N2. Further, the thickness direction V1 of the sheet S indicates a direction (crossing direction) orthogonal to the shortest path L1 at a position where the shortest path L1 intersects the resin sheet 135 when viewed from the width direction. The in-loop guide 132 has a convex portion P1 in contact with the shortest path L1, and the resin sheet 135 is located downstream of the convex portion P1 in the sheet conveying direction.

  As shown in FIG. 4, the resin sheet 135 is divided into two sheet materials 135a and 135b at the center in the width direction. Each sheet material 135a, 135b extends in the width direction so as to cover the end of each sheet S in the width direction for a plurality of sheets S having different sizes in the width direction. Specifically, it is preferable to extend the sheet materials 135a and 135b so that the end portions 135c and 135c on the outer side in the width direction of the sheet materials 135a and 135b are located at the same position as the maximum sheet width or on the outer side. is there. Further, it is preferable that the total length of the resin sheet 135 (distance between the end portions 135c and 135c) is approximately the same as or slightly larger than the total length of the registration roller pair 131.

  In the illustrated configuration example, the registration roller pair 131 is a so-called through roller having the same outer diameter over substantially the entire length in the width direction, and the transport roller pair 121 is provided only in a part of the range in which the registration roller pair 131 is provided in the width direction. It has been. End portions 135d and 135d on the inner side in the width direction of the sheet materials 135a and 135b overlap with a range in which the conveyance roller pair 121 is provided in the width direction. Accordingly, the resin sheet 135 is provided over a wider range in the width direction than at least a region where the conveying roller pair 121 contacts the sheet S (a contact region between the rollers in the nip portion N1).

(Operation of resin sheet)
The operation of the resin sheet 135 when the sheet S is conveyed will be described. As shown in FIG. 2A, the leading edge of the sheet S that is nipped and conveyed by the conveying roller pair 121 (downstream end in the sheet conveying direction) is guided by the outer loop guide 133 and the inner loop guide 132 to stop. It hits the registration roller pair 131 in the state. In this state, when the conveyance roller pair 121 further rotates by a certain amount, a loop of the sheet S is formed in the sheet conveyance path 140. The conveyance roller pair 121 stops rotating after rotating a certain amount.

  Thereafter, the driving of the registration roller pair 131 and the conveyance roller pair 121 is resumed at the timing when the image is transferred to an appropriate position on the sheet S according to the progress of the image forming process by the image forming unit 150. The conveyance speed of the registration roller pair 131 and the conveyance roller pair 121 is set so as to avoid the tension of the sheet S as much as possible in order to stabilize the posture of the leading edge of the sheet S. That is, the peripheral speed of the driving roller 121a of the conveying roller pair 121 is set to a value that is equal to or slightly faster than the peripheral speed of the driving roller 131a of the registration roller pair 131. After the trailing edge of the sheet S has passed through the nip portion N2 of the registration roller pair 131, the registration roller pair 131 stops again, and the next sheet S can be received.

  Here, the operation when the sheet S is carried in a skewed posture, that is, when the sheet leading edge reaches the conveyance roller pair 121 in a state where the sheet leading edge is inclined with respect to the width direction will be described. Such skew is caused by the inclination of the sheet S set on the feeding cassette 111 or the manual feed tray 116, the misalignment of the roller members on the conveyance path, and the like.

  When the skewed sheet S reaches the conveying roller pair 121 and is sent out by the conveying roller pair 121, the skew of the sheet is corrected by abutting the front end of the sheet against the nip portion N2 of the registration roller pair 131 in the stopped state. . At this time, the size of the loop formed on the sheet S after the skew correction varies depending on the position in the width direction. Specifically, referring to FIG. 5, the target loop amount is the loop at the side end (hereinafter, referred to as the advancing side end a <b> 2) where the tip end a <b> 12 precedes in the state before skew correction. Become bigger. Further, the loop at the side end where the tip end a13 is delayed (hereinafter referred to as the delayed side end a3) becomes smaller than the target loop amount (see FIG. 5). However, the leading end portions a12 and a13 are corners between the leading end a1 and the side ends a2 and a3 of the sheet S. The target loop amount is the conveyance distance of the conveyance roller pair 121 from when the leading edge a1 of the sheet S reaches the registration roller pair 131 to when the conveyance roller pair 121 is stopped when the sheet S is not skewed. Point to.

  After the skew correction, while the sheet S is conveyed by rotating the registration roller pair 131 and the conveying roller pair 121, the difference in the loop amount between the side edges a2 and a3 tends to increase. This is because the position of the sheet S in the portion that is carried into the conveyance roller pair 121 is inclined, so that the position where the conveyance roller pair 121 holds the sheet S is the side edge a3 on the delay side in the width direction. This is because the position gradually shifts in the direction (back side in FIG. 5) toward the side end a2 on the advance side from the side. On the other hand, since the skew of the sheet S sent from the registration roller pair 131 has already been corrected, the position where the registration roller pair 131 holds the sheet is substantially constant. Accordingly, as the conveyance of the sheet S proceeds, the loop amount at the advancing side end a2 tends to increase, and the loop amount at the lagging side end a3 tends to decrease.

  Due to such a change in the loop amount, as shown in FIG. 5, the loop at the side edge a2 on the delay side disappears, and between the registration roller pair 131 and the conveyance roller pair 121, the sheet S has a side edge a2 on the delay side. Tension may occur in the near area. If the resin sheet 135 does not exist, a large tension (broken arrow) between the holding position of the side end a2 by the registration roller pair 131 and the conveying roller pair 121 with the disappearance of the loop at the side end a2 on the delay side. Can occur. Then, the sheet S may be wavy due to the tension, and the wrinkled sheet S may be pinched by the registration roller pair 131 to cause wrinkling of the sheet S.

  Here, as described above, the resin sheet 135 of this embodiment is disposed so as to protrude toward the loop outer guide 133 with respect to the shortest path L1 of the sheet conveyance path 140 (see FIG. 2B). . Accordingly, as shown in FIG. 3, the sheet S is brought into frictional contact with the resin sheet 135 in the process of decreasing the loop of the delayed side end a <b> 2. As a result, the sheet position in the thickness direction is regulated by the tip portion of the resin sheet 135 over the range in the width direction where the resin sheet 135 is provided, and the undulation of the sheet S is suppressed.

  Further, the registration roller pair 131 conveys the sheet S against the frictional force that the sheet S receives from the resin sheet 135 at least in the range in the width direction where the sheet S is in contact with the resin sheet 135. That is, the tension (solid line arrow) generated between the resin sheet 135 and the registration roller pair 131 acts in a distributed manner over the range in the width direction where the resin sheet 135 is provided. Thereby, the waviness of the sheet S can be further suppressed, and the possibility that wrinkles will occur can be reduced.

  When the trailing edge of the sheet S passes the conveying roller pair 121, the trailing edge of the sheet S becomes a free edge and can be displaced relatively freely so as to reduce stress. For this reason, the contact pressure between the sheet S and the resin sheet 135 is reduced, and the tension of the sheet S between the registration roller pair 131 and the conveyance roller pair 121 is also eliminated. That is, after the trailing edge of the sheet S passes through the conveying roller pair 121, the possibility that the sheet S is wavy or wrinkled is reduced regardless of the posture of the sheet S before skew correction.

(For highly rigid sheets)
Next, the operation of the resin sheet 135 when conveying a highly rigid sheet will be described. When a sheet having high rigidity is conveyed, there is a concern that the frictional force generated between the resin sheet 135 and the sheet S increases and the conveyance resistance of the sheet S increases.

  In particular, in this embodiment, before the leading end of the sheet reaches the registration roller pair 131, the resin sheet 135 and the loop outer guide 133 can come into contact with both surfaces of the sheet S, and thus the sheet S may be in a bridge state. Concerned. In the bridge state, an object such as a conveyance guide comes into contact with one surface and the other surface of the highly rigid sheet S, and a force to bend the sheet S acts on the sheet S and the object. A state in which a large frictional force is generated between the two. When the sheet S enters the bridge state, the conveyance resistance of the sheet S exceeds the conveyance capability of the conveyance roller pair 121, and the sheet leading end cannot reach the registration roller pair 131.

  In this embodiment, as shown in FIG. 2B, a straight line L2 connecting the position of the convex portion P1 of the in-loop guide 132 (first position) and the position of the front end portion P2 of the resin sheet 135 (second position). Intersects the outer loop guide 133 upstream of the registration roller pair 131 (point Q1). Therefore, when conveying a sheet having high rigidity such as paper having a large basis weight (thick paper) or coated paper, as shown in FIG. 6, before the leading end of the sheet reaches the registration roller pair 131, the sheet S is The resin sheet 135 is in contact with both.

  Here, in order to avoid wrinkling during conveyance of the sheet S by the registration roller pair 131, for example, the in-loop guide 132 protrudes to the position of the resin sheet 135, or a hard metal plate is used instead of the resin sheet 135. Conceivable. However, in these configurations, when a highly rigid sheet is conveyed, the sheet may be in a bridge state, and the leading edge of the sheet may not reach the registration roller pair 131.

  The resin sheet 135 of the present embodiment is a sheet member formed of a synthetic resin that is an elastic material. For this reason, as shown in FIG. 6, when the sheet S comes into contact with both the loop outer guide 133 and the resin sheet 135, the resin sheet 135 is deformed by being pressed by the sheet S, and the leading end portion P2 has a thickness. Displacement toward the in-loop guide 132 in the direction V1. That is, the resin sheet 135 is displaced in the direction of retreating from the sheet S, so that the curvature of the sheet S in the vicinity of the resin sheet 135 is loosened. Thereby, compared with the case where a non-movable member is provided at the same position as the resin sheet 135, the vertical drag acting on the contact portion between the sheet S and the resin sheet 135 and the loop outer guide 133 is reduced. The conveyance resistance is reduced. Accordingly, it is possible to reduce the possibility of a conveyance failure when conveying a highly rigid sheet.

  When a sheet having low rigidity is conveyed, even if the sheet S abuts on the resin sheet 135 before the leading edge of the sheet abuts on the registration roller pair 131, the resin sheet 135 is hardly displaced. However, in this case, since the rigidity of the sheet S is low, the vertical drag generated between the sheet S and the outer loop guide 133 and the resin sheet 135 is also small, and it is unlikely that a large conveyance resistance leading to conveyance failure occurs. .

  As described above, in this embodiment, the resin sheet 135 is placed in a section between the conveying roller pair 121 and the registration roller pair 131 at a position where the sheet S abuts at least under the condition that tension is generated on the sheet S. It is arranged. In other words, when viewed from the width direction, the second guide side from the second guide side in the direction intersecting the shortest path with respect to the shortest path (L1) from the sheet transport means to the registration means through the inside of the sheet transport path. The protrusion part which protrudes to the 1 guide side is arrange | positioned. Thereby, it can suppress that a sheet | seat and a wrinkle arise in a sheet | seat. Then, the protruding portion is configured to be displaceable toward the second guide when pressed by the sheet S, so that a sheet having high rigidity can be conveyed without impairing the action of suppressing the wavy and wrinkle of the sheet. In this case, it is possible to reduce the possibility that a conveyance failure will occur.

(Configuration example)
A preferred configuration example of this embodiment will be described. As the resin material constituting the resin sheet 135, polyester or polyphenylene ether can be used, but other synthetic resins that can be elastically deformed may be used.

  The hardness of the resin sheet 135 is set in consideration of the rigidity of the sheet S used as a recording material so that both the action of suppressing waviness and wrinkles and the action of avoiding poor conveyance of a highly rigid sheet can be achieved. . When the resin sheet 135 is too hard, there is a concern that a sheet having high rigidity will be in a bridge state, as in the case where a non-movable guide is disposed at the position of the resin sheet 135. In addition, when the resin sheet 135 is too soft, there is a concern that the wrinkle generation cannot be effectively reduced because the resin sheet 135 is deformed following the sheet waviness with respect to the sheet having low rigidity that is likely to be wavy.

  Specifically, it is preferable to use a resin sheet 135 having a length of a cross section viewed from the width direction of about 11.8 mm using a sheet member having a Young's modulus of about 4.4 GPa and a thickness of 188 μm. there were. As a preferable setting of the resin sheet 135, the material has a Young's modulus of 4.0 GPa to 4.8 GPa, a thickness of 100 μm to 500 μm, and a cross-sectional length of 11.3 mm to 12.3 mm.

  The hardness of the resin sheet 135 is the ratio of the magnitude of the external force to the displacement amount of the front end portion P2 when an external force directed toward the in-loop guide 132 is applied to the front end portion P2 of the resin sheet 135 in the thickness direction. (That is, the spring constant when the resin sheet is regarded as a spring) may be set. This ratio is preferably 0.022 N / mm or more and 0.027 N / mm or less, for example.

  In the above configuration example, the stroke of the resin sheet 135 is about 2.8 mm. However, the stroke refers to the position from the front end position of the resin sheet 135 when the sheet is not conveyed to the position where the front end of the resin sheet 135 is pushed by the sheet when conveying the most rigid sheet used as a recording material. Refers to the distance. The stroke of the resin sheet 135 is preferably 2 mm or more, and for example, a range of 2.3 mm or more and 3.3 mm or less is desirable.

(Modification)
In the present embodiment, the resin sheet 135 has been described as being divided into two sheet materials 135a and 135b (see FIG. 4), but one sheet material covers the ends of both sides of the sheet S in the width direction. It does not matter as a configuration. In this case, it is preferable that the length in the width direction of one sheet material is equal to or greater than that of the registration roller pair 131.

  In the present embodiment, the case where the convex portion P1 in contact with the shortest path L1 exists upstream of the resin sheet 135 in the in-loop guide 132 has been described (see FIG. 2B). The inner guide 132 may be separated. That is, as shown in FIG. 2C, the in-loop guide 132 is separated from the shortest path L1 connecting the nip portions N1 and N2 of the conveying roller pair 121 and the registration roller pair 131. In this case, when the illustrated straight line L2 intersects the outer loop guide 133 upstream of the registration roller pair 131 (point Q2), the possibility that the highly rigid sheet S will be in a bridge state should be considered. By using the resin sheet 135 of the present embodiment, it is possible to avoid the sheet S from being bridged even in such a case. However, the straight line L2 is drawn from the position (third position) of the nip portion N1 of the conveying roller pair toward the position (fourth position) of the front end portion P2 of the resin sheet 135 in a state where the sheet S is not conveyed. It is a straight line.

  Next, the configuration of the sheet conveying apparatus according to the second example (Example 2) will be described. The sheet conveying apparatus of the present embodiment is different from that of the first embodiment in that the rotation guide used as the protruding portion is configured to be displaceable by the elasticity of a spring connected thereto. Hereinafter, elements common to the first embodiment are denoted by the same reference numerals as those of the first embodiment and description thereof is omitted.

  As shown in FIGS. 7A and 7B, the rotation guide 201 that is the protruding portion of the present embodiment is a plate-like member that is rotatably supported by the in-loop guide 132. A spring 202 is disposed between the rotation guide 201 and the in-loop guide 132 as a biasing member that biases the rotation guide 201 so that the tip of the rotation guide 201 protrudes toward the outer loop guide 133. Has been. The length of the rotation guide 201 in the width direction and the length of the cross section viewed from the width direction are the same as those of the resin sheet 135 of the first embodiment.

  In a state where the sheet is not conveyed, the leading end portion P2 of the rotation guide 201 protrudes toward the loop outer guide 133 at V2 in the thickness direction with respect to the shortest path L1 of the sheet conveying path 140. When the sheet S is conveyed, the rotation guide 201 is rotated against the urging force of the spring 202 from the position where the sheet is not conveyed (protrusion position), so that the rotation guide 201 moves toward the guide 132 in the loop. It is possible to move to the retracted position (retracted position) (FIG. 7B).

  As shown in FIG. 7A, when the tension is generated in the sheet S conveyed by the registration roller pair 131 and the conveyance roller pair 121, the rotation guide 201 at the protruding position makes frictional contact with the sheet S. . The elastic force of the spring 202 is set so that the rotation guide 201 can be maintained at the protruding position even when the sheet S having a basis weight equal to or less than the threshold is pulled. As a result, even when the skewed sheet S is carried into the conveying roller pair 121, the occurrence of undulation and wrinkling of the sheet S can be suppressed.

  As illustrated in FIG. 7B, when the highly rigid sheet S is conveyed toward the registration roller pair 131, the rotation guide 201 is pressed by the sheet S and rotates from the protruding position toward the retracted position. . Thereby, the possibility that the sheet S becomes a bridge state and a conveyance failure occurs is reduced. The elastic force of the spring 202 is set so as to allow the rotation guide 201 pressed by the sheet S having a basis weight equal to or greater than the threshold to rotate toward the retracted position. Accordingly, it is possible to reduce an increase in the conveyance resistance when conveying a sheet having a high configuration while suppressing the occurrence of wrinkles on the sheet, and to reduce the possibility of a conveyance failure.

  It was preferable to use a spring 202 having a spring constant of about 0.0254 N / mm. A preferable range of the spring constant is a range of 0.022 N / mm or more and 0.027 N / mm or less.

  In this embodiment, the form in which the rotation guide 201 is urged to the protruding position using the spring 202 is illustrated, but the rotation guide 201 may be urged by other methods. For example, an elastic member such as a sponge may be disposed between the rotation guide 201 and the in-loop guide 132, and the rotation guide 201 may be configured to be biased to the protruding position by its own weight.

  Further, the movement mode of the protruding portion is not limited to the rotation operation as in the rotation guide 201, and may be any configuration that can be displaced in the thickness direction of the sheet S. For example, a protrusion that can reciprocate (slide) in the thickness direction of the sheet S with respect to the in-loop guide 132 may be provided.

  Next, the configuration of the sheet conveying apparatus according to the third example (Example 3) will be described. The sheet conveying apparatus according to the present embodiment is different from the first embodiment in that the guide plate used as the protruding portion is configured such that the protruding amount can be controlled by a driving source such as a solenoid. Hereinafter, elements common to the first embodiment are denoted by the same reference numerals as those of the first embodiment and description thereof is omitted.

  As shown in FIGS. 8A and 8B, the guide plate 301 is movable from the in-loop guide 132 in the thickness direction V1 of the sheet S between a protruding position and a retracted position. However, the protruding position is a position where the leading end P2 protrudes on the same side as the outer guide 133 with respect to the shortest path L1 of the sheet conveying path 140, and the retracted position has a protruding amount with respect to the shortest path L1 compared to the protruding position. It is a position that is retreated to a region that is small or does not cross the shortest route L1. The guide plate 301 is fixed to an operation member 302 that is moved by a solenoid D1 that is a drive source, and moves together with the operation member 302. The length of the guide plate 301 in the width direction and the length of the cross section viewed from the width direction are the same as those of the resin sheet 135 of the first embodiment.

  As shown in FIG. 8C, the operation of the solenoid D <b> 1 is controlled by the control unit 145 mounted on the image forming apparatus 100. The control unit 145 as control means includes a memory 147 that stores a program and various data, and a CPU (central processing unit) 146 that reads the program from the memory 147 and executes the program. Further, the control unit 145 is connected to an operation unit 148 that is a user interface of the image forming apparatus 100, and information on a sheet to be conveyed (for example, basis weight, surface treatment, etc.) according to a user operation content on the operation unit 148. Presence / absence, whether it is a special sheet such as an envelope).

  FIG. 8D shows a flowchart for switching the position of the guide plate 301 according to the basis weight as an example of control according to the type of sheet. When the CPU 146 receives a signal (job) requesting the start of the image forming operation (S1: Y), the CPU 146 acquires sheet information (S2). Based on the acquired information, a control signal is sent to the solenoid D1 to control the position of the guide plate 301 (S3 to S5). When the basis weight is equal to or greater than the threshold, the guide plate 301 is set to the retracted position (S4), and when the basis weight is less than the threshold, the guide plate 301 is set to the protruding position (S5). Then, by driving the conveyance motor M1 and the registration motor (registration motor) M2 at an appropriate timing, the skew of the sheet S is corrected and sent to the secondary transfer unit.

  In the case of a sheet having a small basis weight, the sheet S is conveyed in a state where the guide plate 301 is in the protruding position, as shown in FIG. In this case, when tension is applied to the sheet S on one side in the width direction, the guide plate 301 waiting at the protruding position and the sheet S are brought into frictional contact, thereby suppressing the generation of wrinkles.

  In the case of a sheet having a large basis weight, as shown in FIG. 8B, the sheet S is conveyed in a state where the guide plate 301 is in the retracted position. In this case, since the guide plate 301 is retracted from the passing position of the sheet S, the sheet S is prevented from being in a bridge state. Therefore, as in the first and second embodiments, there is a possibility that a conveyance failure may occur by reducing the conveyance resistance when conveying a sheet having a large basis weight while suppressing the occurrence of wrinkles on the sheet S having a small basis weight. Can be reduced.

  In this embodiment, the solenoid D1 is used as a drive source for moving the guide plate 301. However, for example, a motor may be used as the drive source.

(Other embodiments)
In addition to the configurations described in the first to third embodiments, the present technology can be variously changed and modified. For example, instead of a configuration in which the present technology is applied to a sheet conveying apparatus that conveys a sheet toward an image forming unit, the sheet is conveyed inside a sheet processing apparatus that performs processing such as binding processing on the image formed sheet. The present technology may be applied to a sheet conveying device.

  In the first to third embodiments, the case where the method of abutting the leading end of the sheet against the nip portion N2 of the roller pair is used as the registration unit. However, for example, a shutter type registration unit may be used. In the case of the shutter system, apart from the roller pair that sandwiches and conveys the sheet S, a shutter member with which the leading end of the sheet abuts on the upstream side from the nip portion of the roller pair is provided. Then, after the leading edge of the sheet comes into contact with the shutter member and the loop of the sheet S is formed, the shutter member is retracted, so that the leading edge of the sheet is held in the nip portion.

  The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus / 121 ... Sheet conveyance means (conveying roller pair) / 131 ... Registration means (registration roller pair) / 132 ... Second guide (in-loop guide) / 133 ... First guide (out-loop guide) / 135, 201, 301 ... Projection (resin sheet, rotation guide, guide plate) / 150 ... Image forming means (image forming part) / 202 ... Biasing member (spring) / D1 ... Drive source (solenoid) / L1 ... Shortest path / P2 ... Projection tip / V1 ... Intersection direction

Claims (14)

Sheet conveying means for nipping and conveying the sheet in the sheet conveying direction;
A registration means disposed downstream of the sheet conveying means in the sheet conveying direction, capable of correcting skewing of the sheet, and capable of nipping and conveying the sheet;
A sheet conveyance path that guides a sheet between the sheet conveyance unit and the registration unit, and allows the sheet to be bent when viewed from a width direction orthogonal to the sheet conveyance direction, and outside the curved sheet A sheet conveying path having a first guide disposed so as to be positioned on the inner side of the curved sheet, and a second guide disposed so as to be positioned on the inner side of the curved sheet,
The front end extending in the width direction can contact the sheet, and when viewed from the width direction, the shortest direction from the sheet conveying means to the registration means passes between the first guide and the second guide. A projecting portion projecting from the second guide side to the first guide side in a crossing direction intersecting the shortest path with respect to the path,
The protrusion is displaceable toward the second guide in the intersecting direction.
A sheet conveying apparatus. The protrusion is made of an elastic material that can be deformed in the intersecting direction by being pressed by a sheet.
The sheet conveying apparatus according to claim 1. The protrusion is a sheet member made of a synthetic resin, which is fixed to the second guide at one end and can contact the sheet at the other end when viewed from the width direction.
The sheet conveying apparatus according to claim 2. The sheet member is made of a material having a Young's modulus of 4.0 GPa or more and 4.8 GPa or less, and has a thickness of 100 μm or more and 500 μm or less.
The sheet conveying apparatus according to claim 3. Provided between the second guide and the projecting portion, urging the projecting portion toward the first guide in the intersecting direction, and the projecting portion is displaced when the projecting portion is pressed against the sheet. A biasing member that allows the
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The ratio of the magnitude of the external force to the amount of displacement of the tip when the external force toward the second guide in the intersecting direction is applied to the tip of the protrusion is 0.022 N / mm or more and 0.027 N / Mm or less,
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. A drive source capable of moving the protrusion;
Control means for moving the protrusion to the drive source according to the type of the sheet conveyed by the sheet conveying device,
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The protrusion is displaceable by at least 2 mm in the intersecting direction,
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. As viewed from the width direction, a position where the shortest path is in contact with the second guide on the upstream side of the protrusion in the sheet conveying direction is a first position that is the most downstream position in the sheet conveying direction. When the position of the tip of the protruding portion in a state protruding with respect to the shortest path is the second position,
A straight line drawn from the first position toward the second position intersects the first guide between the second position and the registration means in the sheet conveying direction;
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. When viewed from the width direction, the shortest path is not in contact with the second guide on the upstream side of the protrusion in the sheet conveying direction, and the position where the sheet conveying means holds the sheet is a third position, When the position of the tip of the protruding portion in a state protruding with respect to the shortest path is the fourth position,
A straight line drawn from the third position toward the fourth position intersects the first guide between the fourth position and the registration means in the sheet conveying direction.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. A gap is provided between the first guide and the tip of the protruding portion in a state of protruding with respect to the shortest path;
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The outer end of the protruding portion in the width direction is located outside of the width direction of the sheet that can be conveyed by the sheet conveying device, than the passing position of the sheet having the largest length in the width direction.
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. The area where the sheet conveying means holds the sheet is narrower than the area where the registration means holds the sheet in the width direction,
The tip portion of the protruding portion extends in the width direction over a range wider than the region in which the sheet conveying unit sandwiches the sheet,
The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is a sheet conveying apparatus. A sheet conveying device according to any one of claims 1 to 13,
Image forming means for forming an image on a sheet conveyed by the sheet conveying apparatus,
An image forming apparatus.

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