JP2012035950A - Sheet conveying device, and image forming apparatus - Google Patents

Abstract

To provide a sheet conveying apparatus and an image forming apparatus that are configured so that impact noise is not generated at the step of a merging portion of a conveyance path at the trailing edge of the sheet and that does not affect the posture of the sheet during conveyance.
SOLUTION: Projection guide portions 51a and 51a projecting downstream in the transport direction from a symmetrical position in the width direction perpendicular to the sheet transport direction are provided at the downstream end of the first transport path. Furthermore, the downstream end portion of the merging guide member 52 has a protruding guide portion 52a that protrudes downstream in the transport direction from a position facing the central portion of the protruding guide portions 51a and 51a. For this reason, in a state where both end portions of the sheet are supported by the protruding guide portions 51a and 51a, the center portion of the sheet is bent and brought into contact with the protruding guide portion 52a, and both ends of the sheet are supported in the state where the central portion is supported by the protruding guide portion 52a. The abutment portion can be brought into contact with the upper end portion of the merging guide member 52 to suppress the impact sound.
[Selection] Figure 3

Description

  The present invention relates to a sheet conveying apparatus in an image forming apparatus including an electrophotographic system, and more particularly to a sheet conveying apparatus that improves noise during sheet conveyance and an image forming apparatus including the same.

In recent years, there has been a strong demand for miniaturization and space saving of office automation equipment such as copying machines and laser printers. In that case, since the external dimensions of the apparatus are reduced, the conveyance path tends to be curved as compared with the conventional apparatus, and the radius of the curved path tends to be small. On the other hand, the user's needs are diversified, and a sheet having a larger basis weight (for example, 120 g / m ² or more) than the conventional sheet is often used. Such a sheet having a large basis weight has high rigidity (rigidity) (stretching is strong), and when bent by a curved conveyance path, the sheet is stretched at the high rigidity. For this reason, when the trailing edge of the sheet passes through the step at the joining portion of the conveyance path, there arises a problem that the trailing edge of the sheet comes into contact with the guide and generates an impact sound.

  As a countermeasure against such noise, an image forming apparatus having the following transport mechanism is known. This image forming apparatus includes a main feeding path that guides a sheet fed from one paper feeding cassette to the registration roller inlet end, and a branch feeding that leads a sheet fed from the other paper feeding cassette to the registration roller inlet end. And a transmission path. Further, the image forming apparatus has an outlet opening that opens the outlet end of the branch feeding path to a position midway along the main feeding path. And the thin-layer elastic body which adhere | attached the base end side to the upstream bank part of the main feeding path is extended to the downstream bank part along the surface on the exit opening surface. This thin-layer elastic body is formed in a straight line with a base end side bonded to the upstream bank along a direction perpendicular to the sheet conveying direction, and a free end on the opposite side to the orthogonal direction in the central portion. Is formed to be concave or convex. As a result, in the structure in which the branch feeding path is joined to the main feeding path, it is possible to prevent the occurrence of a jam at the outlet opening or the generation of abnormal noise when the sheet rear end side passes through the outlet opening. (See Patent Document 1).

  On the other hand, another image forming apparatus is also known. This image forming apparatus includes a cassette for stacking and storing sheets, a feeding roller for feeding sheets one by one from the cassette to the conveyance path, and a U-turn guide for reversing the conveyance direction of the sheet fed from the cassette. A feeding device is provided. In this feeding device, the U-turn guide has a plurality of ribs having a sheet guide surface curved in a concave shape, and the convex shape of the rib protruding from the cassette tip is the highest at one end of the U-turn guide. The other ribs are low. Thereby, since only a part of the rear end of the sheet hits the highest rib, the generation of abnormal noise is reduced (see Patent Document 2).

Utility Model Registration No. 2556245 JP-A-8-169589

  However, in the technique described in Patent Document 1, since the thin-layer elastic body is attached to the upstream shore portion with a double-sided tape or the like, there is a risk that the thin-layer elastic body may be deformed or peeled off due to jam processing or the like. It was. In addition, there has been a problem that adding a thin-layer elastic body causes an increase in cost.

  In the technique described in Patent Document 2, since the guide shape of the U-turn guide is not symmetrical in the width direction orthogonal to the sheet conveyance direction, the sheet conveyance resistance may vary in the width direction, which affects the sheet posture during conveyance. There is a problem that printing accuracy is impaired.

  The present invention provides a small and inexpensive sheet conveying apparatus that prevents the rear end of a conveyed sheet from generating an impact sound at the level difference of the merging portion of the conveying path and does not affect the posture of the sheet during conveyance. An object of the present invention is to provide an image forming apparatus provided with the same.

  The present invention provides a sheet conveying apparatus including a curved first conveying path that conveys a sheet and a second conveying path that merges with the first conveying path, and the merge of the first conveying path and the second conveying path. Provided with a conveyance guide member between the first conveyance path and the second conveyance path in the section, and provided with a merging guide member extending downstream from the conveyance guide member and constituting the second conveyance path, A pair of first guides projecting downstream in the transport direction from a symmetrical position in the width direction orthogonal to the transport direction of the sheet to be transported to either one of the transport guide member and the extended portion of the merging guide member A portion is provided, and protrudes toward the one from the center position in the width direction orthogonal to the conveyance direction of the sheet to be conveyed, on the other of the conveyance guide member and the extended portion of the merging guide member Second Provided id portion, characterized in that.

  According to the present invention, from a state where the conveyed sheet is supported by being brought into contact with the pair of first guide parts or the second guide part, the sheet is brought into contact with the second guide part or the pair of first guide parts. It can be shifted sequentially. Accordingly, it is possible to provide a small and inexpensive sheet conveying apparatus that does not affect the posture of the sheet at the time of conveyance while suppressing the impact sound generated at the step of the joining portion of the conveyance path at the trailing edge of the sheet.

1 is a longitudinal sectional view showing an overall configuration of a full-color laser beam printer which is an embodiment of a color image forming apparatus according to the present invention. Sectional drawing which shows the confluence | merging conveyance part in 1st Embodiment which concerns on this invention. The perspective view which shows the confluence | merging conveyance part in 1st Embodiment. The perspective view which shows the confluence | merging guide member in 1st Embodiment. The perspective view which shows the confluence | merging conveyance part in 1st Embodiment. The cross-sectional shape of the confluence | merging conveyance part in 1st Embodiment is shown, (a) is a sheet | seat rear end reaching one protrusion guide part, (b) is a sheet | seat rear end passing one protrusion guide part. The state which reached | attained the other protrusion guide part is shown. The perspective view which shows the confluence | merging conveyance part in 2nd Embodiment which concerns on this invention. Sectional drawing which shows the confluence | merging conveyance part in 3rd Embodiment which concerns on this invention. The perspective view which shows the confluence | merging conveyance part in 3rd Embodiment. The perspective view which shows the confluence | merging guide member in 3rd Embodiment. The cross-sectional shape of the confluence | merging conveyance part in 3rd Embodiment is shown, (a) when a sheet | seat rear end reaches one protrusion guide part, (b) is a sheet | seat rear end passing one protrusion guide part. The state which reached | attained the other protrusion guide part is shown. The perspective view which shows the conveyance guide member in 4th Embodiment which concerns on this invention. The side view which shows the conveyance guide member in 4th Embodiment.

[First Embodiment]
First, the overall configuration of the image forming apparatus according to the present invention will be schematically described with reference to FIG. FIG. 1 is a longitudinal sectional view showing the entire configuration of a full-color laser beam printer which is an aspect of the image forming apparatus according to the present invention.

  As shown in FIG. 1, the laser beam printer includes a sheet feeding unit 1 at the lowest level. Further, the laser beam printer has a registration roller pair 2 (2a, 2b) that conveys the registration of the sheet S on the upper part of the sheet feeding unit 1, position detection of the sheet S, and jamming of the sheet feeding unit 1. And a top sensor 3 for detection.

  A scanner unit 4 is disposed above the sheet feeding unit 1, and four process cartridges 10 (10Y, 10M, 10C, and 10Bk) are disposed above the scanner unit 4. The process cartridges 10Y, 10M, 10C, and 10Bk are provided with photosensitive drums 20Y, 20M, 20C, and 20Bk, respectively. Above the process cartridge 10, the intermediate transfer unit 5 is arranged so as to face the process cartridge 10 (10Y, 10M, 10C, 10Bk).

  The intermediate transfer unit 5 includes an intermediate transfer belt 6 wound between a driving roller 8 and a tension roller 9, and a primary transfer roller 7 (7Y, 7M, 7C, 7Bk) disposed inside the intermediate transfer belt 6. ). A paper discharge tray 25 is disposed above the intermediate transfer unit 5. A secondary transfer roller 12 is disposed at a position facing the driving roller 8 to constitute a secondary transfer portion T2. A cleaning device 11 is disposed at a position facing the tension roller 9.

  A fixing unit 13 is disposed above the secondary transfer roller 12. The fixing unit 13 includes a pressure roller 13a connected to a drive mechanism (not shown) capable of changing a rotation speed, a heater as a heating source, and is rotatable with respect to the pressure roller 13a. The heating roller 13b is in contact with the pressure.

  In the upper left part of the fixing unit 13, a paper discharge roller pair 14 (14 a, 14 b) and a double-side reversing unit 15 are disposed. The double-side reversing unit 15 includes a reversing roller pair 16 and a double-sided flapper 17 that is a branching unit. A conveyance roller pair 30 is disposed in the reverse conveyance path H in which the sheet S reversed by the double-side reversing unit 15 is conveyed. In the present embodiment, the intermediate transfer unit 5, the photosensitive drum 20 (20Y to 20Bk), and the like constitute an image forming unit for forming an image on the sheet S conveyed by the sheet conveying device.

  A pickup roller 21 is disposed at the front upper portion of the sheet feeding unit 1, and a feed roller 22 and a retard roller 23 facing each other are disposed downstream of the pickup roller 21 in the feeding direction. The sheet S fed from the sheet feeding unit 1 by the pickup roller 21, the feed roller 22 and the retard roller 23 transports the sheet S downstream in the transport direction via the third transport path C and the registration roller pair 2. It is sent out to the common conveyance path G.

  The common conveyance path G on which the sheet S sent by the registration roller pair 2 is conveyed is connected to the fixing unit 13 via the secondary transfer portion T2. A loop detection unit 40 is disposed slightly upstream of the fixing unit 13. The loop detection unit 40 includes a rotatable sensor flag and a photo sensor. The loop detection unit 40 is a sheet conveyed between a nip formed by the driving roller 8, the intermediate transfer belt 6, and the secondary transfer roller 12 and a fixing roller nip 13n formed by the pressure roller 13a and the heating roller 13b. This is detected when the amount of the loop is greater than or equal to a predetermined amount.

  The first transport path A for feeding the sheet S fed from the multi-feed to the common transport path G is composed of a transport guide member 51 and an upper guide 50 facing the transport guide member 51. A pair of transport rollers 34 is disposed in the first transport path A, and a pickup roller 32 and a separation pad 33 are disposed upstream of the pair of transport rollers 34. The first conveyance path A conveys the sheet S to the common conveyance path G and is curved from the downstream side of the conveyance roller pair 34, and joins the second conveyance path B from the sheet feeding option in the middle of the curved portion. However, it is joined to the third conveyance path C from the sheet feeding unit 1 slightly downstream of this joining unit.

  The second conveyance path B joins the downstream end of the first conveyance path A in the conveyance direction and conveys the sheet S to the common conveyance path G, and is disposed between the first conveyance path A and the second conveyance path B. It is comprised by the conveyance guide member 51 currently made and the confluence | merging guide member 52 which opposes this with a clearance gap. The merging guide member 52 extends further to the downstream side in the sheet conveying direction than the conveying guide member 51. The third conveyance path C includes a merging guide member 52 and a feeding guide 36 that faces the merging guide member 52 with a gap therebetween. The merging guide member 52 constitutes a part of the first and second conveying paths A and B at the merging portion of the first and second conveying paths A and B. Then, the sheet conveyed along the first conveyance path A is guided along the conveyance guide member 51 of the first conveyance path A, and is delivered to the extended portion of the second conveyance path B. In this embodiment, the conveyance reference for conveying the sheet employs a so-called central reference in which the center in the direction orthogonal to the sheet conveyance direction of the conveyance path coincides with the center in the width direction of the sheet. is doing.

  Next, the operation of the laser beam printer will be described. First, single-sided printing will be described.

  As shown in FIG. 1, in a laser beam printer, each color toner formed by a scanner unit 4, a photosensitive drum 20 (20Y to 20Bk), etc. on an intermediate transfer belt 6 rotating counterclockwise (in the direction of arrow a). Images are sequentially transferred (primary transfer). Then, a full-color toner image is formed on the intermediate transfer belt 6 by superimposing the toner images of the respective colors.

  In the case of feeding from the sheet feeding unit 1, the sheet S is picked up by the pickup roller 21, separated by the feed roller 22 and the retard roller 23, and the registration roller pair 2 (2 a, 2 a, 2) via the third conveyance path C. 2b). On the other hand, in the case of multi-feeding, the sheet S is picked up by the pickup roller 32, separated by the separation pad 33, and conveyed to the registration roller pair 2 (2a, 2b) via the first conveyance path A.

  The top sensor 3 on the downstream side of the sheet conveyance of the registration roller pair 2 detects the leading edge of the sheet S, and the secondary transfer portion T2 aligns the position of the full color toner image on the intermediate transfer belt 6 with the sheet S. S is conveyed to the secondary transfer portion T2. Further, the sheet S on which the full color toner image is transferred by the secondary transfer portion T2 is conveyed to the fixing unit 13.

  By varying the speed of the pressure roller 13a of the fixing unit 13 based on the detection information of the loop detection unit 40, the sheet S is conveyed in a state in which a loop of a predetermined amount or more is secured. Accordingly, the fixing unit 13 does not affect the conveyance speed of the sheet S at the secondary transfer portion T2, and thus does not affect the image forming operation.

  The full color toner image is fixed on the sheet S by the pressure roller 13a and the heating roller 13b provided in the fixing unit 13, and the sheet S is discharged to the discharge tray 25 at the upper part of the apparatus by the discharge roller pair 14 (14a, 14b). .

  Next, detailed configurations of main components will be described in detail. As described with reference to FIG. 1, each photosensitive drum 20 is provided in the process cartridge 10, and each photosensitive drum 20 is rotationally driven in a clockwise direction in the drawing by a driving mechanism (not shown). The

  Each photoconductor drum 20 (20Y, 20M, 20C, 20Bk) is configured by applying an organic photoconductive layer (OPC photoconductor) to an outer peripheral surface of an aluminum cylinder having a diameter of 20 to 30 mm, for example. Each photosensitive drum 20 is rotatably supported at both ends by a support member, and is driven to rotate clockwise by transmitting a driving force from a drive motor (not shown) to one end. The

  The intermediate transfer belt 6 is composed of a film-like member, and is disposed so as to be opposed to and contact with the photosensitive drums 20 (20Y, 20M, 20C, 20Bk) of the respective colors, and circulates. The intermediate transfer belt 6 is supported by two roller shafts (a driving roller 8 and a tension roller 9), and rotates in the direction of arrow a in the figure. The driving roller 8 and the tension roller 9 which are two roller shafts are supported by bearings (not shown) (drive roller bearings and tension roller bearings) and supported by an intermediate transfer unit frame (not shown).

  Primary transfer rollers 7 (7Y, 7M, 7C, 7Bk) are arranged in parallel at positions that are in contact with the inner side of the intermediate transfer belt 6 and face the four photosensitive drums 20 (20Y, 20M, 20C, 20Bk). Has been. A positive charge is applied from the primary transfer roller 7 to the intermediate transfer belt 6, and an electric field due to the charge causes the intermediate transfer belt 6 in contact with each photosensitive drum 20 to be negatively charged on each photosensitive drum 20. Each color of the toner image having is transferred. Similarly, each primary transfer roller 7 (7Y, 7M, 7C, 7Bk) is also supported by a bearing (not shown) and supported by an intermediate transfer unit frame (not shown).

  In addition to the configuration described above, a color laser beam printer having a configuration using the electrostatic transfer conveyance unit mentioned in the background art can be used instead of the intermediate transfer unit 5.

  Next, with reference to FIG. 2, the sheet conveying apparatus in the present embodiment will be described. Here, when the sheet S is fed from the multi-feed, the sheet S is placed in a portion where the first transport path A from the multi-feed and the second transport path B from the feed option merge. A configuration for suppressing a collision sound generated when the end passes will be described.

  FIG. 2 is a cross-sectional view illustrating a merging / conveying unit of the sheet conveying apparatus according to the present embodiment, and FIGS. 3, 4 and 5 are perspective views illustrating the merging / conveying unit, respectively. FIG. 6 shows a cross-sectional shape in the sheet conveyance direction of the merge conveyance unit. 6A shows a state in which the rear end of the sheet S has reached the protruding guide portions 51a and 51a. FIG. 6B shows a state in which the rear end of the sheet S passes through the protruding guide portions 51a and 51a. The state which reached | attained the convex-shaped protrusion guide part 52a is shown. In FIG. 6, the conveying direction of the sheet S is from the near side to the far side.

  As described above, the first conveyance path A from the multi-feed is formed by one surface of the upper guide 50 and the conveyance guide member 51. Further, the second conveyance path B from the paper feed option is formed by the other surface of the conveyance guide member 51 and the merging guide member 52. The first conveyance path A is curved upward from the downstream of the conveyance roller pair 34. The sheet conveyance direction in the first conveyance path A and the second conveyance path B is a direction in which the sheet is conveyed toward the registration roller pair 2 (2a, 2b) as indicated by arrows D and E, respectively.

  As shown in FIG. 3, the conveyance guide member 51 is provided with convex protruding guide portions 51 a and 51 a that protrude downstream from the center in the conveyance direction at both ends in the width direction orthogonal to the sheet conveyance direction. Yes. The protruding guide parts 51a and 51a are provided at least at a position where the conveyed sheet S can be supported.

  In addition, a convex protruding guide portion 52 a that protrudes in the sheet thickness direction is provided at the center of the extending portion of the merging guide member 52 that faces the conveyance guide member 51. The protruding guide portion 52 a is positioned at the center in the width direction of the sheet conveyed at the central portion of the protruding guide portions 51 a and 51 a at both ends of the conveying guide member 51 facing the merging guide member 52.

  As shown in FIG. 5, the protruding guide portion 52a is positioned between at least a section L where the protruding guide portions 51a and 51a of the conveying guide member 51 are located and a section L ′ further downstream in the sheet conveying direction. Is provided. As described above, in the present embodiment, the protruding length of the protruding guide portions 51a and 51a as the pair of first guide portions in the conveying direction is the length of the protruding portion of the protruding guide portion 52a as the second guide portion in the conveying direction. Is set shorter. The protruding guide portion 52a protrudes in the sheet thickness direction from between the protruding guide portions 51a and 51a in the width direction orthogonal to the sheet conveying direction. The protruding guide portion 52a constitutes a second guide portion that protrudes toward the conveyance guide member 51 from the center position in the width direction orthogonal to the conveyance direction of the conveyed sheet.

  Here, with reference to FIG. 5 and FIGS. 6A and 6B, the sheet S is formed on the step portion of the second conveyance path B (see FIG. 2) between the conveyance guide member 51 and the merging guide member 52. The situation when it arrives will be described.

  When the trailing edge of the sheet S reaches the protruding guide portions 51a and 51a of the conveying guide member 51, the sheet S is supported by the protruding guide portions 51a and 51a in the width direction orthogonal to the sheet conveying direction, but at the center. The part is not supported. For this reason, as shown to Fig.6 (a), the center part of the rear end of the sheet | seat S bends to the merging guide member 52 side, and contact | abuts to the convex-shaped protrusion guide part 52a of the merging guide member 52. FIG. Thus, since the sheet S is supported at the both ends by the protruding guide portions 51a and 51a, the central portion is bent and comes into contact with the protruding guide portion 52a, the impact during passage is suppressed.

  When the sheet S is further conveyed, the rear end of the sheet S passes through the protruding guide parts 51a and 51a of the conveying guide member 51 and the center part is supported by the protruding guide part 52a as shown in FIG. 6B. Thus, both end portions are brought into contact with the upper end portion of the merging guide member 52. Thus, the sheet S is released from the projecting guide parts 51a and 51a while the center part is supported by the projecting guide part 52a. Therefore, the impact sound at the time of contact of the sheet both end parts with the merging guide member 52 is released. Is suppressed.

  As described above, in the present embodiment, the downstream end portion (one of the downstream end portions) of the first transport path A protrudes downstream in the transport direction from the symmetrical position in the width direction orthogonal to the transport direction of the sheet S to be transported. Protruding guide portions 51a and 51a which are a pair of first guide portions are provided. Further, a protruding guide portion 52a which is a second guide portion protruding from the position facing the central portion of the protruding guide portions 51a and 51a to the downstream end portion (the other of the downstream end portions) of the merging guide member 52 on the downstream side in the transport direction. Is provided. Accordingly, the center portion of the sheet S can be bent and brought into contact with the protruding guide portion 52a of the merging guide member 52 in a state where both ends of the sheet S are supported by the protruding guide portions 51a and 51a. Thereafter, both end portions of the sheet S can be brought into contact with the upper end portion of the merging guide member 52 in a state where the central portion is supported by the protruding guide portion 52a. For this reason, the sheet rear end suppresses an impact sound generated at the step of the joining portion between the first conveyance path A and the second conveyance path B, and does not affect the posture of the sheet during conveyance, and is small and inexpensive. A sheet conveying apparatus can be provided.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described. Since the basic configuration of the laser beam printer is the same as that of the first embodiment described above, the description thereof will be omitted, and only the constituent parts that are characteristic of this embodiment will be described here.

  In the first embodiment, the protruding guide portions 51a and 51a are provided at both end portions of the conveying guide member 51 so as to be more convex in the conveying direction than the central portion. The protruding guide portions 51a and 51a are at least conveyed. It was provided in the position which can support the sheet | seat S made.

  On the other hand, in the present embodiment, as shown in FIG. 7, the convex protrusion guide portions 61 a and 61 a provided on the conveyance guide member 61 corresponding to the conveyance guide member 51 are not both ends of the conveyance guide member 61. It is formed in two symmetrical positions between the end and the center. Other configurations are the same as those of the first embodiment.

  In the present embodiment, the support position of the sheet S is positioned on the center side as compared with the case of the first embodiment. For this reason, when the rear end of the sheet S reaches the protruding guide portions 61a and 61a of the conveyance guide member 61, and the central portion of the rear end of the sheet S is bent toward the joining guide member 62 corresponding to the joining guide member 52, The amount of bending can be further reduced by supporting the sheet S on the center side. In this state, the rear end of the sheet S abuts on the projecting protruding guide portion 62a of the merging guide member 62. Therefore, even when the sheet has extremely high rigidity (rigidity), the impact is reliably suppressed and the sheet is conveyed. It is possible not to affect the posture of the seat.

  Further, the positions and widths of the protruding guide portions 61a and 61a provided on the conveyance guide member 61 are optimal by changing according to the waist of the sheet S to be passed, the size in the sheet width direction, and the level difference of the sheet conveyance device. Can be

  As described above, in the present embodiment, the pair of first guide portions projecting downstream in the transport direction from the symmetrical position in the width direction orthogonal to the transport direction of the sheet S to be transported at the downstream end of the first transport path A. Certain protruding guide portions 61a and 61a are provided. Furthermore, the downstream end portion of the merging guide member 62 is provided with a protruding guide portion 62a that is a second guide portion that protrudes downstream in the transport direction from a position facing the central portion of the protruding guide portions 61a and 61a. Thereby, the same effects as those of the first embodiment described above can be obtained.

[Third Embodiment]
Next, a third embodiment according to the present invention will be described with reference to FIGS. Since the basic configuration of the image forming apparatus is the same as that of the first embodiment described above, the description thereof will be omitted, and only the constituent parts that characterize the present embodiment will be described here. FIG. 8 is a cross-sectional view showing the merging / conveying portion in the present embodiment, FIG. 9 is a perspective view showing the merging / conveying portion in the present embodiment, and FIG. 10 is a perspective view showing the merging guide member 72 in the present embodiment. 11A and 11B are cross-sectional shapes in the sheet conveyance direction of the merging conveyance unit. FIG. 11A illustrates a case where the trailing end of the sheet S reaches the protruding guide portion 71a, and FIG. The state which passed and reached the convex-shaped protrusion guide part 72a of the confluence | merging guide member 72 is shown. In FIG. 11, the conveyance direction of the sheet S is from the front side to the back side.

  As shown in FIG. 8, the first transport path A from the multi-feed is formed by the upper guide 50 and the upper surface of the transport guide member 71 corresponding to the transport guide member 51 of the first embodiment. Further, the second conveyance path B from the paper feed option is formed by the lower surface of the conveyance guide member 71 and a merging guide member 72 corresponding to the merging guide member 52 of the first embodiment.

  The first conveyance path A is curved upward from the downstream of the conveyance roller pair 34. The sheet conveyance direction of the first conveyance path A and the second conveyance path B is a direction in which the sheet is conveyed to the registration roller pair 2 (2a, 2b) as indicated by arrows D and E, respectively.

  As shown in FIG. 9, the conveyance guide member 71 corresponding to the conveyance guide member 51 of the first embodiment is formed in a convex shape toward the conveyance direction from both ends at the center in the conveyance path width direction. A protruding guide portion 71a is provided. Further, as shown in FIGS. 9 and 10, convex portions projecting in the downstream side in the conveying direction and in the sheet thickness direction are formed at both ends of the opposite confluence guide member 72 corresponding to the confluence guide member 52 of the first embodiment. Projecting guide portions 72a and 72a are provided. As shown in FIG. 9, the protruding guide portions 72a and 72a are positioned between at least a section M where the protruding guide portion 71a of the conveying guide member 71 is positioned in the sheet conveying direction and a section M ′ further downstream thereof. Is provided. As described above, the protruding guide portions 72a and 72a that are the pair of first guide portions are provided in the second transport path B, and the protruding length thereof is longer than the protruding length of the protruding guide portion 71a that is the second guide portion. Is set. These projecting guide portions 72a and 72a are formed so as to project in the sheet thickness direction from both ends in the width direction orthogonal to the sheet conveying direction of the merging guide member 72.

  Here, with reference to FIG.9 and FIG.11, the case where the level | step-difference part of the 2nd conveyance path B between the conveyance guide member 71 and the confluence | merging guide member 72 is reached is demonstrated.

  When the trailing edge of the sheet S reaches the protruding guide portion 71a of the conveyance guide member 71, the sheet S is supported at the center in the sheet width direction, but not at both ends. For this reason, as shown in FIG. 11A, both end portions of the rear end of the sheet S are bent toward the joining guide member 72 and come into contact with the protruding guide portions 72a and 72a.

  When the sheet S is further conveyed, as shown in FIG. 11B, the sheet S is in a state in which the rear end passes through the protruding guide part 71a of the conveying guide member 71 and the both end parts are supported by the protruding guide parts 72a and 72a. Thus, the merging guide member 72 is brought into contact with the whole. Since the center part of the sheet S is released from the projecting guide part 71a in a state where both ends are supported, the impact sound at the time of contact with the joining guide member 72 at both ends is suppressed.

  As described above, in the present embodiment, the downstream end portion of the merging guide member 72 is a pair of first guide portions projecting downstream in the conveyance direction from the symmetrical position in the width direction orthogonal to the conveyance direction of the sheet S to be conveyed. Protruding guide portions 72a and 72a are provided. Further, the transport guide member 71 is provided with a projecting guide portion 71a which is a second guide portion projecting downstream from the position facing the central portion of the projecting guide portions 72a and 72a in the transport direction.

  Accordingly, the central portion of the sheet S is bent from the state in which the central portion of the sheet S is supported by the protruding guide portion 71 a of the conveyance guide member 71 and is brought into contact with the protruding guide portions 72 a and 72 a of the merging guide member 72. . Thereafter, with the both ends of the sheet S supported by the protruding guide portions 72 a and 72 a of the merging guide member 72, the center portion of the sheet S is brought into contact with the central portion of the merging guide member 72, so that the rear end of the sheet is Suppresses the impact sound generated at the level difference at the junction of the conveyance path. Accordingly, it is possible to provide a small and inexpensive sheet conveying apparatus that does not affect the posture of the sheet during conveyance.

[Fourth Embodiment]
Next, a fourth embodiment according to the present invention will be described. FIG. 12 is a perspective view showing the configuration of the present embodiment, and FIG. 13 is a cross-sectional view showing the configuration of the present embodiment. Since the configuration other than the conveyance guide member 81 is the same as that of the first embodiment, the description thereof is omitted.

  The conveyance guide member 81 is provided with protruding guide portions 81a and 81a that are convex downstream in the conveyance direction from the central portion at both ends in the width direction (conveyance path width direction) orthogonal to the sheet conveyance direction. . The protruding guide portions 81a and 81a are provided at least at positions where the conveyed sheet S can be supported. The protruding guide portions 81a and 81a have flexibility by providing slits (cuts) 81s, respectively, and in the direction indicated by the arrow F in FIG. The structure is flexible. After the sheet passes, it is configured to return to its original position with elasticity.

  As described above, in the present embodiment, the pair of first guide portions projecting downstream in the transport direction from the symmetrical position in the width direction orthogonal to the transport direction of the sheet S to be transported at the downstream end of the first transport path A. Certain protruding guide portions 81a and 81a are provided. Further, a confluence guide member 52 similar to that of the first embodiment is provided with a projecting guide portion 52a which is a second guide portion projecting downstream from the position facing the central portion of the projecting guide portions 81a and 81a in the transport direction. ing. The protruding guide portions 81a and 81a have flexibility and are configured to bend toward the joining guide member 52 side (see FIG. 3) by being pushed by the sheet S conveyed to the common conveyance path G side.

  As a result, the protruding guide portions 81a and 81a are pushed and bent by the rigidity of the sheet S, so that the rear end of the sheet is received from the protruding guide portions 81a and 81a by the protruding guide portion 52a (see FIG. 5) of the merging guide member 52. The level difference when handing over can be reduced. For this reason, a small and inexpensive sheet conveying apparatus that does not affect the posture of the sheet at the time of conveyance while suppressing the impact sound generated at the step of the merging portion of the conveyance path more effectively at the trailing edge of the sheet is provided. be able to.

  The configuration of the present embodiment can also be applied to the third embodiment described above. In this case, the protruding guide portion 71a that is the second guide portion has flexibility and the common transport path G. The sheet S is pushed by the sheet S and is bent toward the joining guide member 72. Also in this case, it is possible to more effectively suppress the impact sound generated at the step of the joining portion of the conveyance path at the trailing edge of the sheet.

  As described above, in the first to fourth embodiments according to the present invention, one of the conveyance guide member (51, 61, 71, 81) and the extended portion of the merging guide member (52, 62, 72). In addition, projecting guide portions (51a, 61a, 72a, 81a) which are a pair of first guide portions are provided. The protruding guide portions (51a, 61a, 72a, 81a) protrude downstream in the conveying direction from symmetrical positions in the width direction orthogonal to the conveying direction of the conveyed sheet. Further, a projecting guide portion (second guide portion) projecting toward the one from the center position in the width direction orthogonal to the sheet transport direction is provided on the other of the transport guide member and the extended portion of the merging guide member. 52a, 62a, 71a). As a result, a small and inexpensive sheet conveying apparatus that does not affect the posture of the sheet at the time of conveyance while suppressing the impact sound generated at the step of the merging portion of the conveyance path at the trailing edge of the sheet is provided.

5, 20 ... Image forming section (intermediate transfer unit, photosensitive drum), 51, 61, 71, 81 ... Conveying guide member, 51a, 61a, 72a, 81a ... First guide section (protruding guide section), 52, 62 , 72 ... Confluence guide member, 52a, 62a, 71a ... 2nd guide part (protruding guide part), A ... 1st conveyance path, B ... 2nd conveyance path, G ... Common conveyance path, S ... Sheet

Claims (6)

In a sheet conveying apparatus comprising a curved first conveying path that conveys a sheet, and a second conveying path that merges with the first conveying path,
A conveyance guide member is provided between the first conveyance path and the second conveyance path at a junction of the first conveyance path and the second conveyance path;
A merging guide member extending downstream from the transport guide member and constituting the second transport path;
A pair of first protrusions projecting downstream in the conveying direction from a symmetrical position in the width direction perpendicular to the conveying direction of the sheet to be conveyed to either one of the conveying guide member and the extended portion of the merging guide member. A guide portion is provided, and protrudes toward the one from the center position in the width direction orthogonal to the conveyance direction of the sheet to be conveyed, on one of the conveyance guide member and the extended portion of the merging guide member. A sheet conveying apparatus, characterized in that a second guide portion is provided.   2. The pair of first guide portions is provided in the first transport path, and a protruding length thereof is set to be shorter than a length of the second guide portion in the sheet transport direction. The sheet conveying apparatus according to 1.   The pair of first guide portions have flexibility, and are configured to be bent toward the merging guide member side by being pushed by a sheet conveyed to the first conveyance path side. The sheet conveying apparatus according to claim 2.   The pair of first guide portions are provided in the second conveyance path, and a protruding length thereof is set to be longer than a length of the second guide portion in the sheet conveyance direction. The sheet conveying apparatus according to 1.   The said 2nd guide part has flexibility, and it is comprised so that it may be pressed by the sheet | seat conveyed to the said 1st conveyance path side, and may bend to the said merging guide member side. The sheet conveying apparatus according to 4. A sheet conveying device according to any one of claims 1 to 5,
An image forming apparatus comprising: an image forming unit configured to form an image on a sheet conveyed by the sheet conveying apparatus.

Images