JP2012193042A - Image forming device and delivered paper sheet stacking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To load a sufficient quantity of paper sheets, and to obtain images of high quality by restraining a printed paper sheet from being curled by an image forming device.SOLUTION: This image forming device includes: an image forming section such as an image forming head unit 2 which forms an image with a water-based ink in a paper sheet 4 to be supplied; a conveying delivery section such as a pair of delivery rollers 19 and 20 which convey to deliver the printed paper sheet 4P formed with an image; a paper sheet loading table 21 which is loaded with the printed paper sheets 4P delivered by the conveying delivery section; and guide and presser members 30 and 31 which push the top surface of the paper sheets, are loaded on the paper sheet loading table 21 toward a loading surface 21a while guiding the printed paper sheet 4 which is newly delivered. The guide and presser members 30 and 31 are supported freely to swing in a direction for pushing the printed paper sheets 4P, and parts 30b and 31b thereof which are brought into contact with the top surface of the printed paper sheet 4P, has a shape to be brought into line-contact or point contact with the top surface of the printed paper sheet along the delivering direction of the paper sheet.

Description

  The present invention relates to various image forming apparatuses such as a printer, a plotter, a printing apparatus, a copying apparatus, a digital multifunction peripheral, and a facsimile apparatus, and more particularly to an ink jet image forming apparatus and a paper discharge stacking apparatus for stacking the printed sheets.

Various image forming apparatuses such as those described above have various methods such as an electrophotographic method, a wire dot method, an ink jet method, a thermal method, a thermal transfer method, and a stencil printing method, depending on the image forming method in the image forming unit (means). There are things.
In either case, in general, a sheet (recording medium) is supplied to the image forming unit, and after an image such as a character, a photograph, or a figure is formed there, the recording medium is conveyed and discharged out of the apparatus.

  Among them, an ink jet image forming apparatus forms an image by ejecting water-based ink onto the surface of a sheet using an ink jet head. As an ink-jet image forming apparatus capable of color printing, a conventional low-cost apparatus uses yellow (Y), magenta (M), cyan (C), and black (K) ink for each dot. Serial type inkjet heads that form serial inkjet heads for ejection in the direction (main scanning direction) perpendicular to the paper transport direction and form images on the paper transported in the sub-scanning direction while moving them in the main scanning direction A serial ink jet image forming apparatus provided with an image forming unit has been mainly used.

However, in recent years, in order to cope with higher speeds, a line-type inkjet head having a length corresponding to the entire length in the main scanning direction and capable of simultaneously forming an image for one line is conveyed by the number of colors (sub-direction). A line-type inkjet image forming apparatus provided with a line-type inkjet image forming unit arranged and fixed in the (scanning direction) has come to be frequently used.
This line type ink jet image forming apparatus is capable of overwhelmingly increasing the printing speed as compared with the serial type ink jet image forming apparatus, but also has some important problems.

One of them is that the use of water-based ink causes curling of printed matter after image formation. That is, curling occurs because the image surface of the paper expands and extends due to the moisture of the ink.
In the case of a conventional serial type ink jet image forming apparatus, since the speed is low, the printed paper is held in a horizontal state while forming an image, and the curl growth is suppressed to some extent and then discharged after that. Was possible.
However, in the case of a line-type ink jet image forming apparatus, printed paper is discharged and stacked on the discharge tray one after another in a short time for high-speed conveyance and high-speed discharge. become.

FIG. 15 and FIG. 16 schematically show how the printed sheets are stacked when a conventional paper discharge stacking apparatus is used in a line type ink jet image forming apparatus using water-based ink. FIG. 15 shows the case where the image plane is below, and FIG. 16 shows the case where the image plane is above. In either case, (a) shows a case when viewed from the side perpendicular to the transport direction, and (b) shows a case when viewed from the upstream side in the transport direction.
In these figures, 50 is a pair of discharge rollers (a pair of paper discharge rollers), 60 is a paper discharge tray, 61a and 61b are left and right side fences, 62 is an end fence, and 70 is a printed sheet.

In this way, the curled direction of the printed paper 70 is determined by the image surface, but when the printed paper 70 is curled on the paper discharge tray 60, the peripheral or central portion of the stacked paper becomes abnormally high. As a result, the next printed sheet 70 collides with the jammed paper and jams.
That is, before a sufficient number of printed sheets 70 are stacked on the sheet discharge tray 60, a curl of the stacked printed sheets grows so as to disturb the discharge of the next printed sheet. Will end up.

  In the ink jet image forming apparatus, there is no conventional technique for suppressing curling of printed paper discharged onto a paper discharge tray. However, as a technique for suppressing discharged paper (sheet) in a general image forming apparatus. Are described in Patent Documents 1 to 3.

  In Patent Document 1, the trailing edge of the sheet discharged onto the sheet discharge tray is pressed by the trailing edge pressing member so that the trailing edge of the curled discharged sheet does not block the sheet discharge port of the image forming apparatus. It is disclosed that the top end of the sheet is guided by a sheet end guide and the sheets are stacked on the sheet discharge tray in an orderly manner.

  Further, in Patent Document 2, in an image forming apparatus in which a sheet on which an image is formed is discharged to a sheet mounting table that rises steeply, the vicinity of the rear end of the sheet discharged by a pair of discharge rollers is flexible. It is disclosed that the sheet pressing member is held and pressed against the sheet mounting table.

  Further, in Patent Document 3, after a printed sheet is discharged onto a stack table by a pair of discharge rollers, a plurality of conveying force transmission units (paddles) configured by an elastic member and arranged in the sheet width direction are used. A paper discharge device that is transported until it hits the stopper and an improved structure of the transport force transmission unit are disclosed.

  In these patent documents, after a printed paper (sheet) on which an image is formed by an image forming apparatus is discharged onto a member corresponding to a paper discharge tray, the stacked paper is removed from above. Since it has a pressing function, it cannot be said that there is no curl pressing effect at the edge or center of the paper.

  However, in the device described in Patent Document 1, the trailing edge pressing member only presses the trailing edge portion of the sheet discharged onto the sheet discharge tray, and the curl at the intermediate portion or the leading end portion in the discharging direction of the stacked sheets. Can not be suppressed. Further, the sheet front end guide only guides the front end of the discharged paper, and does not have a function of pressing the stacked paper. Therefore, depending on these, the effect of suppressing curling of the paper stacked on the paper discharge tray can hardly be expected.

  The document described in Patent Document 2 is intended to prevent the sheet stacking order from being out of order and jamming even if the sheet discharged to the sheet mounting table is once taken out and then returned to the mounting table. This also only presses and holds the vicinity of the trailing edge of the discharged sheet against the sheet mounting table by the sheet pressing member, so that the middle part and the leading edge of the discharging direction of the sheets stacked on the sheet mounting table The curl of the part cannot be suppressed.

  The rear end pressing member and the sheet pressing member are both bent portions obtained by bending a belt-like member having a certain width in a direction perpendicular to the sheet (sheet) discharge direction into a V shape, or not bent. The top edge of the straight belt-like member holds down the upper surface of the discharged paper.

  However, when a sheet on which an image is formed with a liquid recording agent (generally referred to as “ink”) such as water-based ink or oil-based ink is discharged with the image surface facing upward, the sheet has an upward convex shape as shown in FIG. The ink on the upper surface image is discharged in a state where it is not sufficiently dry.

Therefore, in order to suppress curling when such printed paper is stacked on the paper discharge tray, it is necessary to press the intermediate portion in the paper discharge direction against the placement surface. I can't expect that.
In addition, as described above, the upper surface of the paper that is being discharged on the paper discharge tray is pressed by the belt-shaped pressing member having a width in the direction perpendicular to the discharge direction, so that the image on the upper surface of the paper is displayed. If the paper is not completely dry and unfixed, the paper surface may be rubbed against it, and the ink transferred to the pressing member may be retransferred to the paper surface and image quality may be impaired.

  Japanese Patent Application Laid-Open No. 2003-260260 shows a diagram in which the paper discharged on the stack table is held by a paddle. The paddle is made of an elastic member such as rubber, and is a conveying force transmission member for conveying the paper. Therefore, it naturally has a width in a direction perpendicular to the conveying direction, and rotates in frictional contact with the upper surface of the paper. Therefore, as described above, if the image on the top surface of the discharged paper is not completely dry and unfixed, it will be rubbed with a paddle to soil the paper surface, and the ink transferred to the paddle will be reapplied to the paper surface. The image quality is impaired due to the transfer.

  The present invention has been made in view of such a situation, and printed sheets in the image forming apparatus are discharged while curling when sequentially discharged and stacked on the mounting surface of the sheet stacking table. The printed sheet is surely guided onto the placement surface, curling of the printed sheet is prevented from proceeding on the placement surface, and the image surface of the sheet is facing upward, so that the image recording agent is completely fixed. The object is to prevent the image quality from deteriorating even when it is not done, and to make the image quality good with almost no curl when the user takes out the stacked paper. For this purpose, an image forming apparatus and a paper discharge stacking apparatus are provided.

In order to achieve the above object, an image forming apparatus according to the present invention conveys an image forming unit that forms an image on a sequentially fed sheet with a liquid recording agent, and a printed sheet on which an image is formed in the image forming unit. A paper discharge table, a paper stacking table on which printed paper discharged by the transport discharge unit is stacked, and an upper surface of the paper stacked on the paper stacking table as a mounting surface of the paper stacking table. And a guide / holding member for guiding the printed paper to be newly ejected while being pressed.
The guide / holding member is supported so as to be able to swing in the direction in which the printed paper is pressed, and the portion in contact with the top surface of the printed paper is in line contact or point along the top surface of the paper and the discharge direction of the paper. It has a shape to contact.

  The guide / holding member is an arm-like member whose base end is pivotally supported by the fixed portion of the apparatus main body, and the lower edge of the arm-like member is formed on a linear edge parallel to the discharge direction of the printed paper. The leading end portion of the edge can be configured to be in line contact or point contact with the upper surface of the printed paper along the paper discharge direction.

  Alternatively, the guide / holding member is rotated by an arm-like member whose base end portion is pivotally supported by the fixing portion of the apparatus main body and a shaft in a direction perpendicular to the discharge direction of the printed paper at the distal end portion of the arm-like member. The disk-shaped member freely pivotally supported, and a large number of sharp protrusions are formed radially along the outer periphery of the disk-shaped member, and the tips of the protrusions are connected to the top surface of the printed paper. More preferably, it is configured to make point contact.

  The transport discharge unit includes a discharge roller pair that discharges the printed paper on which an image has been formed to the paper stacking base, while the guide / holding member is an upper discharge roller of the discharge roller pair. It may be pivotally supported by a rotating shaft supported by the apparatus main body.

It is preferable that the sheet stacking table is lowered in accordance with an increase in the number of printed sheets stacked on the sheet stacking table.
In these image forming apparatuses, a pressing release member that rotates the guide and pressing member to a position that does not press the upper surface of the printed paper discharged and stacked on the paper stacking base may be provided.

A sheet discharge stacking apparatus according to the present invention is a sheet discharge stacking apparatus in which printed sheets are sequentially discharged from an image forming apparatus and stacked. The sheet stacking apparatus is configured as follows to achieve the above object.
And a pair of side fences that guide both ends of the printed sheet in the width direction perpendicular to the direction in which the printed sheet is discharged. The side fence is movable in the width direction according to the paper size, and the upper surface of the printed paper discharged and stacked on the placement surface is placed on the opposing inner surface side of the pair of side fences. A guide / holding member that guides the printed paper that is newly discharged while being pressed toward the placement surface is provided so as to be pivotable in a direction in which the paper is pressed. The guide / holding member has a shape in which a portion in contact with the upper surface of the printed sheet is in line contact or point contact with the upper surface of the sheet along the discharge direction of the sheet.

It is desirable that a plurality of pairs of the guide / holding members are provided on the inner surfaces of the pair of side fences facing each other at intervals in the discharge direction of the printed paper.
The guide / holding member is rotatably supported by an arm-shaped member whose base end is pivotally supported by the side fence, and an axis in a direction perpendicular to the discharge direction of the printed paper. A large number of protrusions having sharp tips along the outer periphery of the disk-shaped member, and the tips of the protrusions are in point contact with the top surface of the printed paper. It is good to configure.

The paper discharge stacking apparatus according to the present invention further includes an end fence for stopping the paper by contacting the leading end of the printed paper discharged to the paper stacking base, and the end fence is printed according to the paper size. It is possible to move in the paper discharge direction, and press the upper surface of the printed paper discharged and stacked on the mounting surface of the paper stacking table toward the inner surface of the end fence toward the mounting surface. A guide / holding member that guides the printed paper discharged to the paper may be provided so as to be swingable in the direction in which the paper is pressed.
The guide / holding member has a shape in which a portion in contact with the upper surface of the printed sheet is in line contact or point contact with the upper surface of the sheet along the discharge direction of the sheet.

The guide and pressing member may be pivotally supported at a base end portion by a support member that extends from the end fence to the upstream side in the discharge direction of the printed paper.
The guide / holding member is rotatably supported by an arm-like member whose base end is pivotally supported by the support member, and an axis in a direction orthogonal to the discharge direction of the printed paper at the distal end of the arm-like member. A large number of protrusions having sharp tips along the outer periphery of the disk-shaped member, and the tips of the protrusions are in point contact with the top surface of the printed paper. More preferably, the configuration is as follows.

In these paper discharge stacking apparatuses, a pressing release member for rotating the guide / pressing member to a position where the upper surface of the printed paper discharged and stacked on the paper stacking base is not pressed may be provided.
The guide / holding member may be provided on a plate-like member that is detachably attached to at least one of the side fence and the end fence.

The image forming apparatus according to the present invention also includes an image forming apparatus main body including an image forming unit that forms an image on a sheet, and a transport and discharge unit that transports and discharges a printed sheet on which an image is formed by the image forming unit. The apparatus may include any one of the paper discharge stacking devices for stacking printed sheets sequentially discharged by the transport discharge unit.
The image forming unit may be an ink jet head type image forming unit including one or more ink jet heads.
The ink jet head may be a line type ink jet head.

The “paper” includes plain paper, recording paper, recording sheet, transfer paper, and the like. Further, the sheet is not limited to paper, and includes sheets such as resin sheets, films, cloth, leather, and the like that can form an image with a liquid recording agent such as ink.
The “printing” includes image formation, recording, printing, printing, drawing, and the like, and refers to the formation of characters, photographs, graphics, and the like on a sheet with a liquid recording agent such as ink.

According to the image forming apparatus and the discharge stacking apparatus of the present invention, when printed sheets on which images are formed are sequentially discharged and stacked, the upper surface of the sheet is directed from the upper side to the mounting surface by the guide and pressing member. It is possible to guide the newly ejected printed paper while pressing. Moreover, the contact between the guide / holding member and the upper surface of the paper is almost point contact.
Thereby, curling of the printed paper placed on the placement surface is suppressed, and even when the image surface of the paper is facing upward and the image recording agent is not completely fixed, the guide / holding member There is almost no risk that the unfixed recording material is rubbed or retransferred to deteriorate the image quality. Therefore, when the user removes the stacked sheets, there is almost no curling and the image quality can be improved.

1 is a schematic view showing a main part of a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is an enlarged view showing an upstream half of a printed paper discharge direction on a paper stacking base side in FIG. 1 together with a discharge roller pair. FIG. 3 is an enlarged view of the vicinity of a distal end portion of a guide / holding member surrounded by a circle X in FIG. 2. FIG. 3 is a schematic explanatory diagram illustrating an example in which a sheet stacking table is lowered as the number of printed sheets stacked is increased in the embodiment illustrated in FIG. 2. FIG. 3 is a view similar to FIG. 2 of the second embodiment of the image forming apparatus according to the present invention. Similarly, it is a schematic view of the discharge roller pair on the image forming apparatus main body side with the end fence and the guide / holding member provided on the end fence removed from the downstream side in the paper discharge direction. FIG. 6 is a view similar to FIG. 2 of the third embodiment of the image forming apparatus according to the present invention. It is the top view similarly which abbreviate | omitted the discharge roller pair and was seen from the upper direction. It is a principal part perspective view which shows the example which provided the pressing release member.

FIG. 8 is a view similar to FIG. 7 showing a first embodiment of the paper discharge stacking apparatus according to the present invention. It is the same top view. Similarly, it is the figure which removed the end fence from the downstream of the printed paper discharge direction, and removed only the discharge stacking apparatus. It is a figure which shows the downstream half part of the printed paper discharge | emission direction in 2nd Embodiment of the paper discharge stacking apparatus by this invention. It is the figure which looked at 3rd Embodiment of the paper discharge | stacking stacking device by this invention, removing the front side fence. 6 is a schematic diagram showing a stacked state of printed sheets when an image surface using a conventional paper discharge stacking apparatus is below. 6 is a schematic diagram showing a stacked state of printed sheets when an image surface using a conventional paper discharge stacking apparatus is on top.

Hereinafter, embodiments for carrying out the present invention will be specifically described with reference to the drawings.
[First Embodiment of Image Forming Apparatus]
A first embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of the main part on the main body side and the sheet stacking side of the image forming apparatus.

The image forming apparatus shown in FIG. 1 includes an image forming apparatus main body 1 having an image forming section that forms an image on a sheet and a transport and discharge section that transports and discharges a printed sheet on which an image is formed by the image forming section. , And a sheet stacking base 21 on which printed sheets sequentially discharged by the transport discharge unit and a portion related thereto (corresponding to a sheet discharge stacking device 3 described later) are provided.
In FIG. 1, the image forming apparatus main body 1 schematically shows only the configuration of the parts necessary for the following description, and the paper loading table 21 side is in a state where the front side fence is removed. Show.

In the image forming apparatus main body 1, an image forming head unit 2 having line-type inkjet heads 13 to 16 of four colors of yellow (Y), magenta (M), cyan (C), and black (K) is provided. It is provided as the main unit of the image forming unit. In this figure, members for preventing the ink from drying in the inkjet heads 13 to 16 are omitted.
Then, the sheets 4 sequentially fed from a sheet feeding device (not shown) are transported by the transport roller pairs 5 and 6, and further transported to the image forming position facing the image forming head unit 2 by the endless wide belt 7.

The endless wide belt 7 is wound around a driving roller 8, two driven rollers 9, 10 and a tension roller 11, is given a predetermined tension, and is rotated in the direction of arrow A.
A large number of holes are formed in the endless wide belt 7, and air is sucked by the air suction duct 12 through the holes to suck and convey the back surface of the paper 4. The air suction duct 12 generates an air suction force by a suction blower device (not shown).

The image forming head unit 2 drives the ink-jet heads 13 to 16 of the respective colors by a head driving device (not shown) at a timing from the time of detection of the paper leading edge by the paper leading edge detection sensor 33, and moves in the direction indicated by the arrow on the paper 4. Along with the transfer of the ink, water-based ink, which is a liquid recording agent of yellow (Y), magenta (M), cyan (C), and black (K), is supplied from the nozzles at the tips of the inkjet heads 13 to 16 to the paper 4. A full color image is formed by sequentially ejecting the ink on the surface. Meanwhile, the endless wide belt 7 is driven so as not to fluctuate in speed, and stably conveys the paper 4.
These constitute an ink jet head type image forming unit. In this embodiment, the image forming unit is a full-color line type ink jet head system.

  The printed paper 4P on which an image is formed by the image forming head unit 2 is transported by the transport roller pairs 17 and 18, and when the image surfaces are stacked upward, both the path switching claw members 22 and 27 are transport rollers. Retracted to a position below the horizontal conveyance path between the pair 17 and 18 and the discharge roller pair 19 and 20, is conveyed straight as it is, is seated by the discharge roller pair 19 and 20 and is given a discharge force, The sheet is discharged toward the placement surface 21 a of the sheet stacking table 21. The conveyance roller 18 and the discharge roller 20 that are in contact with the image surface side of the printed paper 4P may be point contact rollers such as an abrasive roller in order to prevent ink transfer contamination.

  On the other hand, when the image plane is loaded downward, the path switching claw member 22 is moved to the position indicated by the dotted line, and the path switching claw member 27 is moved to the position indicated by the solid line. Accordingly, the printed paper 4P conveyed by the conveying roller pair 17 and 18 is guided in the upward direction by being guided by the path switching claw member 22, and is conveyed in the vertical direction by the first reverse roller pair 23 and 24. After the leading edge is detected by the sheet leading edge detection sensor 35, the leading edge is further conveyed to the second reversing roller pair 25 and 26 and temporarily stopped.

Thereafter, by rotating the first reversing roller pair 23, 24 and the second reversing roller pair 25, 26, the printed paper 4P is conveyed downward, but is guided by the path switching claw member 27 in the discharge direction. The direction is changed, and the sheet is seated by the pair of discharge rollers 19 and 20 to be discharged, and discharged toward the sheet stacking table 21.
Thus, a conveyance discharge unit that conveys and discharges the printed paper on which the image is formed by the image forming unit is configured.

Stacking the printed sheets 4P with the image surface facing downward is a stacking method necessary when the printed sheets 4P printed in page order are arranged in page order when stacked.
In addition to this, there is a case in which printing is performed on both sides of the sheet 4 and then the sheet 4 is discharged to the sheet stacking table 21. However, since the illustration of the conveyance path for duplex printing for that purpose is omitted in FIG.

On the other hand, the paper stacking table 21 is also referred to as a paper discharge tray, and guides both side edges in the width direction perpendicular to the discharge direction (arrow B direction) of the printed paper 4P discharged onto the placement surface 21a. A pair of side fences 28 for positioning in the direction (the front side fence 28 is not shown) and the front end of the printed paper 4P discharged onto the paper stacking base 21 are brought into contact with each other to stop the paper. An end fence 29 for positioning in the discharge direction is provided.
The pair of side fences 28 are slidable in the width direction (direction perpendicular to the paper surface in FIG. 1) so that the distance between them can be adjusted to an optimum value according to the paper size. Similarly, the end fence 29 is slidable in the paper discharge direction so that it can be adjusted to an optimum position according to the paper size.

30 and 31 shown in FIG. 1 are printed newly discharged while pressing the upper surface of the printed sheet 4P stacked on the sheet stacking table 21 toward the mounting surface 21a of the sheet stacking table 21. A guide / holding member for guiding the paper.
The upstream guide / holding member 30 in the sheet discharge direction is attached to a side of the image forming apparatus main body 1 that is a fixing portion of the apparatus main body, for example, in a direction perpendicular to the arrow B direction (a direction perpendicular to the paper surface). A base end portion 30a is pivotally supported on the shaft 32, and is supported so as to be swingable in a direction in which the printed paper 4P is pressed. A portion 30b of the guide / holding member 30 that contacts the upper surface of the printed paper 4P has a shape that makes line contact or point contact with the upper surface of the paper along the discharge direction of the paper.

  The guide / holding member 31 on the downstream side in the paper discharge direction has a base end portion 31a that is rotatable on a shaft 34 attached to the inner surface of the end fence 29 in a direction perpendicular to the arrow B direction (a direction perpendicular to the paper surface). Is supported so as to be able to swing in the direction in which the printed paper 4P is pressed. A portion 31b of the guide / holding member 31 that contacts the upper surface of the printed paper 4P also has a shape that makes line contact or point contact with the upper surface of the paper along the paper discharge direction.

The guide / holding members 30 and 31 are configured so that a predetermined pressing force is applied to the printed paper 4P in the direction of the mounting surface 21a of the paper stacking base 21 by its own weight. It is light enough not to interfere with paper transport. However, the guide / holding members 30 and 31 may be made of an extremely light material such as resin, and if the pressing force is insufficient, the urging force may be increased by a spring or the like.
In this example, the base end portions 30a and 31a of the guide / holding members 30 and 31 are directly supported by the shafts 32 and 34. However, a holding member is provided on the shafts 32 and 34 so as to be relatively rotatable. The base end portions 30a and 31a of the guide / holding members 30 and 31 may be fixed to the holding members.

These configurations will be described in more detail with reference to FIGS.
FIG. 2 is an enlarged view of the upstream half of the printed sheet discharge direction on the sheet stacking side in FIG. 1 together with the discharge roller pair. FIG. 3 is an enlarged view of the vicinity of the tip of the guide / holding member surrounded by a circle X in FIG. FIG. 4 is a schematic explanatory diagram illustrating an example in which the paper stacking table descends as the number of printed papers stacked is increased.

  The pair of discharge rollers on the image forming apparatus main body 1 side includes discharge rollers 19 and 20. In the discharge roller 19, a plurality of sets of lower discharge rollers 192 and waisting rollers 194 having a larger diameter than that of the lower discharge rollers 192 are spaced on both sides in the axial direction of the rotation shaft 191. In the discharge roller 20, a plurality of upper discharge rollers 202 rotatingly driven by rolling contact with the lower discharge rollers 192 are fixed to the rotary shaft 201.

When the discharge roller 19 is rotated by a drive mechanism (not shown) and the lower discharge roller 192 is driven to rotate in the direction of arrow E, the upper discharge roller 202 is driven to rotate in the direction of arrow F. The printed paper 4P is nipped and conveyed by the lower discharge roller 192 and the upper discharge roller 202, and is discharged in the direction indicated by the arrow B.
At this time, the printed paper 4P is bent and wavy in the width direction by the upper discharge roller 202 and the back roller 194, and discharged in the direction indicated by the arrow B while increasing the rigidity.
The discharge rollers 19 and 20 will be described in detail with reference to FIG. 6 of the next embodiment.

  As described above, the guide / holding member 30 is an arm-like member in which the base end portion 30a is rotatably supported on the shaft 32 attached to the apparatus fixing portion such as the side surface of the image forming apparatus main body 1. . In this example, the arm-shaped member is a triangular prism having an inverted triangular cross section as shown in FIG. 3, and the lower edge thereof is a straight edge 30c parallel to the paper discharge direction (the arrow B direction in FIG. 2). The tip of the linear edge 30c is a portion 30b in line contact or point contact with the upper surface of the printed paper 4P along the paper discharge direction.

  The guide / holding member 30 is urged in the direction indicated by the arrow C by its own weight, and the upper surface of the printed paper 4P to be discharged and the portion 30b are in line contact or point contact along the discharge direction to discharge and stack them. Guide in the direction of the mounting surface 21a of the table 21. At this time, the lightweight guide / holding member 30 is swung like a pendulum by the conveying force for discharging the printed paper 4P, so that it does not interfere with the paper discharge.

The sliding contact between the guide / holding member 30 and the upper surface of the sheet is a line contact or a point contact along the sheet discharge direction by the portion 30b of the linear edge 30c, and the contact area with the upper surface of the printed sheet 4P is small. Even when the printed paper 4P is discharged with the image surface facing upward, the unfixed ink is rubbed and soiled by contact with the guide / holding member 30, or the ink is transferred to the guide / holding member 30; It is greatly reduced that the image quality deteriorates due to the retransfer of the image onto the paper.
The shape of the guide / holding member 30 may be a round bar having a small diameter or a thin plate.

The guide / holding member 31 on the downstream side in the paper discharge direction shown in FIG. 1 is also an arm-like member having a triangular prism with a transverse cross section similar to the guide / holding member 30, and its lower edge is from above. It is formed in a linear edge parallel to the paper discharge direction (the direction indicated by the arrow B in FIG. 2), and the leading end is curved upward so as not to hinder the conveyance of the printed paper 4P to be discharged. .
Therefore, the portion 31b that is in sliding contact with the upper surface of the printed paper 4P makes line contact or point contact along the paper discharge direction. Its function is the same as that of the guide / holding member 30.
The guide / holding member 31 may also be formed in a round bar shape or a thin plate shape with a small diameter.

  The guide / holding member 30 is slidable along the shaft 32, and the guide / holding member 31 is slidable along the shaft 34 in the direction (width direction) perpendicular to the paper discharge direction. The position can be changed so that the most effective position can be held. The end fence 29 is slidable in the paper discharge direction, and its position is adjusted according to the paper size, so that the optimum position according to the paper size can always be pressed by the guide / holding members 30 and 31. it can.

Further, one or both of the guide / holding members 30 and 31 may be provided at intervals in the width direction. When one guide / holding member 30, 31 is provided, the central portion in the width direction of the printed paper 4P can be pressed, so that the central portion of the paper width as shown in FIG. It is suitable for suppressing curling (which occurs when the image surface is facing upward).
When two guide / holding members 30, 31 are provided, both sides in the width direction of the printed paper 4P can be pressed, so that both sides of the paper width are high as shown in FIG. It is suitable for suppressing curling that occurs (occurs when the image surface is facing down).

  As shown in FIG. 4, if the sheet stacking table 21 is lowered in accordance with the increase in the number of printed sheets 4P stacked on the mounting surface 21a, the stacked printed sheets 4P are stacked. The height position of the uppermost surface can be made constant as shown by the alternate long and short dash line. As a result, the contact position, angle, and pressing force of the guide / holding members 30 and 31 with the paper become constant, and the predetermined position of the printed paper 4P can always be optimally pressed.

  The guide / holding member 30 shown in FIG. 1 can be made longer and the guide / holding member 31 can be omitted. Alternatively, instead of the guide / holding member 31, a guide / holding member that is swingably supported by at least one of the pair of side fences 28 may be provided downstream of the guide / holding member 30 in the sheet conveyance direction. Good.

[Second Embodiment of Image Forming Apparatus]
Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 5 is a view similar to FIG. 2 of the second embodiment of the image forming apparatus according to the present invention. FIG. 6 is a schematic view of the discharge roller pair on the image forming apparatus main body side with the end fence and the guide / holding member provided on the end fence removed from the downstream side in the paper discharge direction. In these drawings, portions corresponding to those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.

The second embodiment is almost the same as the first embodiment described above, except that the upstream guide / holding member 30 in the paper discharge direction is arranged on the upper side of the discharge roller pair of the image forming apparatus main body 1. The only difference is that the rotary shaft 201 of the discharge roller 20 is pivotally supported.
Although the first embodiment described above is also briefly described with reference to FIG. 2, the configuration of the discharge roller pair will be described in detail with reference to FIG.

  The pair of discharge rollers includes a lower discharge roller 19 that is a driving roller and an upper discharge roller 20 that is a driven roller, and each of the rotation shafts 191 and 201 is a pair of fixed frames provided in the image forming apparatus main body 1. The support members 100a and 100b are rotatably supported, and are arranged in parallel to the width direction perpendicular to the discharge direction of the printed paper 4P.

The rotation shaft 191 of the lower discharge roller 19 has at least two lower discharge rollers 192 at positions symmetrical with respect to the center in the axial direction in FIG. A pair of waist rollers 193 and 194 are provided at intervals.
The diameters of the lowering rollers 193 and 194 are the same, but the diameter of the lower discharge roller 192 is smaller. Each of the lower discharge rollers 192 and the lowering rollers 193 and 194 rotate integrally with the rotating shaft 191, but can be moved (slid) and fixed in the axial direction, for example, a spline fitting and a strong click mechanism, It is attached by a thumbscrew mechanism or the like.

  On the other hand, the rotation shaft 201 of the upper discharge roller 20 is provided with at least two upper discharge rollers 202 at positions corresponding to the lower discharge rollers 192 symmetrically with respect to the center in the axial direction in FIG. . The upper discharge roller 202 and the lower discharge roller 192 of the lower discharge roller 19 form a conveyance nip.

  The upper discharge roller 202 has the same diameter as the lowering rollers 193 and 194 of the lower discharge roller 19, and the radius of each roller is larger than ½ of the interval between the pair of rotating shafts 191 and 201. The discharge roller 202 and the seating rollers 193 and 194 are provided on the rotary shafts 191 and 201 so as to be partially overlapped in the radial direction by alternately shifting their axial positions.

When the lower discharge roller 192 is rotationally driven in the direction of arrow E in FIG. 5 by a drive mechanism (not shown), the upper discharge roller 202 is driven to rotate in the direction of arrow F. The printed paper 4P is nipped and conveyed by the lower discharge roller 192 and the upper discharge roller 202, and is discharged in the direction indicated by the arrow B.
At this time, the printed paper 4P is bent and waved in the width direction by the upper discharge roller 202 and the back roller 193, 194, and discharged while increasing the rigidity.

This is because in order to transport the printed paper 4P against the pressing force of the guide / holding member 30, it is necessary to increase the rigidity in the paper transport direction.
By placing the printed paper 4P in this way, the printed paper 4P is reliably discharged onto the paper stacking base 21 without causing drooping.

Further, the upper discharge roller 202 can be moved (slid) in the axial direction of the rotary shaft 201 to be adjusted and fixed at an optimum position according to the paper size, and can be fixed from the inner surface of each side fence 28 of the discharge stacking device 3. The distance M can be adjusted optimally. In FIG. 6, H is the distance between the inner surfaces of the pair of side fences 28 according to the paper width.
As described above, the lower discharge roller 192 and the seating rollers 193 and 194 can also be slid in the axial direction of the rotary shaft 191 and adjusted and fixed at optimum positions according to the paper size.

These configurations and functions are the same for the lower discharge roller 19 and the upper discharge roller 20 shown in FIG.
In the second embodiment, the discharge roller 20 is also provided at the center in the axial direction of the rotary shaft 201 rotatably supported by a pair of support members 100a and 100b fixed in the image forming apparatus main body 1. The base end portion 30a of the guide / holding member 30 is held so as to be relatively rotatable, and the guide / holding member 30 is pivotally supported to be swingable. Therefore, in this embodiment, it is not necessary to separately provide a shaft for pivotally supporting the guide / holding member 30.

In this case, the upper surface of the printed paper 4P newly discharged by the lower discharge roller 19 and the upper discharge roller 20 is in line contact with the portion 30b of the linear edge 30c of the guide / holding member 30 along the paper discharge direction. Then, it is guided and discharged onto the paper stacking table 21. However, since the contact area is extremely small, even when the printed paper 4P is discharged with the image surface facing upward, unfixed ink is rubbed and becomes dirty, or the ink is transferred to the guide / holding member 30, It is greatly reduced that the image quality deteriorates due to the retransfer of the image onto the paper.
Other configurations and modifications thereof are the same as those in the first embodiment described above.

[Third Embodiment of Image Forming Apparatus]
Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 7 is a view similar to FIG. 2 of the third embodiment of the image forming apparatus according to the present invention, and FIG. 8 is a plan view seen from above with the discharge roller pair omitted. FIG. 9 is a main part perspective view showing an example in which a pressing release member is provided. Also in these drawings, portions corresponding to those in FIGS. 1 to 6 are denoted by the same reference numerals, and description thereof is omitted.

The third embodiment differs from the first embodiment described above only in the configuration of the guide / holding member.
As shown in FIGS. 7 and 8, the guide / holding member 40 in this embodiment includes an arm-like member 41 whose base end portion 41 a is pivotally supported by a shaft 32 provided in the image forming apparatus main body 1 so as to be relatively rotatable. And a disk-like member 45 rotatably supported by a shaft 43 in a direction orthogonal to the discharge direction of the printed paper 4P at the distal end portion 41b of the arm-like member 41. The disk-like member 45 is formed in a spur shape such that a large number of protrusions 45a having sharp tips are formed radially along the outer periphery, and the tips of the protrusions 45a are in point contact with the upper surface of the printed paper 4P. Has been. The base end portion 41a of the arm-like member 41 may be fixed with a separate holding member.

  The guide / holding member 40 is also urged by its own weight in the direction indicated by the arrow C in FIG. 7, but the printed paper 4P is seated by the lower discharge roller 19 and the upper discharge roller 20 to give rigidity, as shown in FIG. When the sheet is discharged in the direction indicated by arrow G, its upper surface and the protrusion 45a of the disk-like member 45 come into contact with each other and are pushed up somewhat, and the printed portion is rotated along with the direction indicated by arrow D in FIG. The paper 4P is guided onto the placement surface 21a of the paper stacking base 21.

  At this time, even when the printed paper 4P is discharged with the image surface facing upward and the ink of the image is unfixed, the contact between the guide / holding member 40 and the upper surface of the printed paper 4P is a point contact, Moreover, since the disk-shaped member 45 is rotated in accordance with the movement of the printed paper 4P, the paper surface is not rubbed, so that the transfer of ink can be greatly reduced, and no rubbing smear occurs. Therefore, the guide / holding member 40 is more advantageous for maintaining the image quality than the guide / holding member 30 in each of the above-described embodiments. Instead of the guide / holding member 31 shown in FIG. 1, a guide / holding member similar to the guide / holding member 40 may be provided inside the end fence.

Further, since the guide / holding member 40 is slidable in the axial direction of the shaft 32 (the direction indicated by the arrow J in FIG. 8), the guide / holding member 40 is positioned so that the optimum position in the width direction of the printed paper 4P can be pressed. Can be changed.
Further, a plurality of the guide / holding members 40 may be provided in the paper width direction. By providing a plurality, it is possible to hold down an appropriate position according to the curl shape of the printed paper 4P as described in the first embodiment.

Further, as described above with reference to FIG. 4, if the sheet stacking base 21 is lowered in accordance with the increase in the number of stacked sheets of printed sheets 4P, the pressing position, angle, and pressing force of the guide / holding member 40 are always set. Can be kept constant.
In place of the spur-shaped disk-like member 45, contact with the upper surface of the printed paper 4P can be achieved by using an abrasive roller having abrasive particles attached to the outer peripheral surface or a knurling roller having knurling. It can be in a state close to point contact.

  FIG. 9 shows an example of a pressing release member that releases the pressing of the guide / holding member 40. A pressing release member 37 that projects in a radial direction and extends parallel to the axial direction is fixed to the lower side of the arm-like member 41 of the guide / holding member 40 on the shaft 32 that pivotally supports the guide / holding member 40. And a release knob 38 is fixed to one end of the shaft 32.

  In this way, when the release knob 38 is manually rotated in the direction indicated by the arrow K in FIG. 9, the shaft 32 and the pressing release member 37 fixed thereto rotate integrally in the direction indicated by the arrow K. Although the guide / holding member 40 does not rotate by the rotation of the shaft 32, the pressing release member 37 contacts the lower surface of the arm-like member 41 by the rotation, and lifts the guide / holding member 40 in the rotation direction. Therefore, the guide / holding member 40 can be rotated to a position where the upper surface of the printed paper 4P discharged and stacked on the placement surface 21a of the paper stacking base 21 is not pressed. Accordingly, it is easy to take out the paper stacked on the paper stacking table 21 after the paper discharge is completed. A click or lock mechanism for holding the shaft 32 from rotating at the pressing release position may be provided.

  This release mechanism has been described in the example in which the shaft 32 is manually rotated to release the guide / holding member 40. However, instead of the release knob, a gear or a pulley is fixed to the shaft 32 so that the gear transmission mechanism or The shaft 32 may be rotated by a motor via a belt transmission mechanism so that the releasing operation can be performed.

  In addition, when the guide / holding member similar to the guide / holding member 31 shown in FIG. 1 or the guide / holding member 40 instead of the guide / holding member 40 is provided on the end fence 29, the guide / holding member is supported by the end fence 29. A pressing release member 37 and a release knob 38 similar to those shown in FIG. 9 are also provided on the shaft 34 that supports the shaft, and pressing of the printed paper 4P discharged and stacked on the paper stacking table 21 is also performed. It should be possible to cancel.

[First embodiment of paper discharge stacking apparatus]
In each of the embodiments so far, a guide / holding member that presses the rear end side of the printed paper is supported by the shaft on the image forming apparatus main body side, and a paper stacking base or the like serves as a part of the image forming apparatus. It was assembled to the main body.
Hereinafter, an embodiment of the paper discharge stacking apparatus according to the present invention configured independently of the image forming apparatus main body will be described.

  First, the first embodiment will be described with reference to FIGS. FIG. 10 is a view similar to FIG. 7 showing the latter half of the paper discharge stacking device together with the discharge roller pair. FIG. 11 is a plan view thereof, and FIG. 12 is a view of only the paper discharge stacking device viewed from the downstream side in the printed paper discharge direction, with the end fence removed. Also in these drawings, portions corresponding to those in FIGS. 1 to 9 are denoted by the same reference numerals, and description thereof is omitted.

  The guide / holding member 40 in the paper discharge stacking apparatus 3 has a slightly shorter arm-like member 41 than the guide / holding member 40 described with reference to FIGS. It consists of a spur-shaped disc-like member 45 that is rotatably supported by a shaft 43 and has substantially the same configuration, and therefore the same reference numerals are used for convenience. However, in the guide / holding member 40 of this embodiment, the base end portion 41a (which may be a holding member) of the arm-like member 41 protrudes on the inner surface side of the side fence 28 in a direction perpendicular to the paper discharge direction. The shaft 42 is pivotally supported so as to be relatively rotatable, and is supported so as to be swingable.

In this embodiment, as clearly shown in FIG. 11, two guide / holding members 40 are symmetrically arranged in the paper width direction at intervals facing each other on the inner surface side of the pair of side fences 28 at intervals in the paper discharge direction. Therefore, each of them is supported by a shaft 42 so as to be swingable.
If this paper discharge stacking device 3 is used, the printed paper 4P that is seated and given rigidity by the lower discharge roller 19 and the upper discharge roller 20 on the image forming apparatus main body side is discharged to both sides and the front end. It can be guided on the side and the rear end side, and can be pressed in the direction of the loading surface of the sheet stacking table 21. The function of each guide / holding member 40 is the same as that of the above-described embodiment.

Each guide / holding member 40 is attached to the side fence 28, and the inner surface to the disc-like member 45 are held at a predetermined distance. Therefore, as shown in FIG. 11 and FIG. An optimum distance L can be maintained from both ends in the width direction.
Thereby, as shown in FIG. 12, in order to suppress the curl generated in the vicinity of both side edges in the width direction of the printed paper 4P, the paper can be pressed at an optimum distance L from the side edge of the paper. Effective for curling suppression.

  Since the side fence 28 is moved as shown by the double-directional arrow in FIG. 11 according to the paper size, the guide / holding members 40 are also moved accordingly. Therefore, even if the paper sizes are different, the upper surface of the printed paper 4P can be pressed by the guide / holding members 40 at a predetermined distance L from the paper side end.

  Further, a shaft 42 that pivotally supports each guide / holding member 40 is provided so as to be slidable in the axial direction with respect to the side fence 28, and the disk-like member 45 of each guide / holding member 40 is provided from the inner surface of the side fence 28. The distance may be variably adjusted. Accordingly, the position of each guide / holding member 40 can be adjusted so that the optimum position can be pressed according to the thickness of the paper and the curled state.

In this embodiment, an example in which two guide / holding members 40 are attached to each side fence 28 is shown, but at least one guide / holding member 40 is attached to one of the side fences 28, One guide / holding member 40 may be attached to each of the pair of side fences 28. Alternatively, three or more sets of guide / holding members 40 may be provided.
Thus, by providing a plurality of guide / holding members 40 symmetrically on the inner surface side of the pair of side fences 28, the guide / holding member 40 curls while guiding the discharge and conveyance of the printed paper 4P. As a result, the effect of pressing from above is further increased.

  Further, when the paper discharge stacking device 3 is mounted on the image forming apparatus main body and used, as described with reference to FIG. 4, according to an increase in the number of printed sheets 4P stacked on the paper discharge stacking base 21. Thus, if the sheet stacking base 21 is lowered, the pressing position, angle, and pressing force by the guide / pressing member 40 can always be kept constant.

The printed paper 4P stacked on the paper stacking base 21 can be easily taken out without the guide / holding member 40 getting in the way if the end fence 29 is tilted and pulled out from the end fence 29 side. . At this time, each guide / holding member 40 naturally escapes upward, so that it does not interfere with the removal.
A shaft 42 for supporting each guide / holding member 40 is also provided so as to be able to rotate by projecting also to the outside of the end fence 29, and the pressing release member 37 and the release knob 38 are fixed to each other in the same manner as the shaft 32 shown in FIG. And a release mechanism may be provided.

[Second Embodiment of Paper Discharge Stacking Device]
Next, a second embodiment of the paper discharge stacking apparatus according to the present invention will be described with reference to FIG. FIG. 13 is a diagram showing the downstream half of the paper discharge stacking device in the direction of discharging printed paper. Also in FIG. 13, the same reference numerals are given to the portions corresponding to the respective drawings so far, and the description thereof is omitted.

  In the paper discharge stacking device 3 ′, a support member 46 is extended from the inner surface of the end fence 29 to the upstream side in the discharge direction of the printed paper 4 </ b> P in parallel with the placement surface 21 a of the paper stacking base 21. A base end portion 41 a of the arm-like member 41 of the guide / holding member 40 is pivotally supported by the support member 46 so as to be swingable by a shaft 47. The guide / holding member 40 rotatably supports a spur-like disc-like member 45 by a shaft 43 at the tip end portion 41b of the arm-like member 41, as described with reference to FIG.

The guide / holding member 40 is lightweight, and the printed paper 4P discharged onto the paper stacking base 21 is transported so as to slide under the guide / holding member 40 and stacked. At this time, the disk-like member 45 of the guide / holding member 40 and the upper surface of the printed paper 4P are in point contact, and the disk-like member 45 is rotated in the direction indicated by the arrow. And the front-end | tip part of the printed paper 4P is pressed in the mounting surface 21a direction with the dead weight of the guide and pressing member 40. FIG.
Since the guide / holding member 40 is swingable, it can be pressed by its own weight without being affected by the number of printed sheets 4P on the sheet stacking table 21.

  In the paper discharge stacking device 3 ′, the guide / holding member 40 is supported by the end fence 29 at a certain distance from the inner surface. This is because it is effective to press the sheet at a predetermined distance N from the front end of the stacked printed sheets 4P in order to suppress the vertical curl that occurs perpendicular to the transport direction. The end fence 29 is moved as indicated by a double-headed arrow in FIG. 13 according to the size of the printed sheet 4P in the discharge direction. However, the guide / holding member 40 also moves accordingly. The upper surface of the printed paper 4P can be pressed while maintaining a predetermined distance N from the front end of the paper.

  Further, when the sheet discharge stacking device 3 'is used by being mounted on the image forming apparatus main body, as described with reference to FIG. 4, according to the increase in the number of printed sheets 4P stacked on the sheet stacking table 21. Thus, if the sheet stacking base 21 is lowered, the pressing position, angle, and pressing force by the guide / pressing member 40 can always be kept constant.

  Further, a pair of support members 46 are extended in parallel from the inner surface of the end fence 29 with a gap in the paper width direction, and a shaft 47 is supported between the pair of support members 46, and a guide / holding member is supported on the shaft. The base end portion 41a of the 40 arm-like members 41 may be pivotally supported so as to be slidable in the axial direction. By doing so, the position of the guide / holding member 40 can be moved in the paper width direction so that the optimum position of the printed paper 4P can be adjusted. Thereby, it is possible to exert a pressing effect according to the paper size and the curl state of the paper.

A plurality of guide / holding members 40 may be provided at intervals in the paper width direction.
Further, a guide / holding member 40 attached to the inner surface side of the side fence 28 according to the embodiment described above with reference to FIGS. 10 to 12 may be provided on the upstream side in the paper discharge direction. A pressing release member and a release knob may be fixed to the shaft 47 as well.

[Third embodiment of the paper discharge stacking apparatus]
A third embodiment of the paper discharge stacking apparatus according to the present invention will be described with reference to FIG. FIG. 14 is a view of a third embodiment of the paper discharge stacking apparatus according to the present invention, with the front side fence removed. Also in FIG. 14, the same reference numerals are given to portions corresponding to the respective drawings so far, and description thereof will be omitted.

  In the sheet discharge stacking apparatus 3 ″, a plurality of protrusions 281 are provided on the upper surface of the pair of side fences 28, and one or more protrusions 291 are provided on the upper surface of the end fence 29. On the other hand, the plate-like member 48 is provided. Holes into which the projections 281 and 291 can be inserted are provided in the contact portion between the lower side fence 28 and the end fence 29. Then, the projections 281 and 291 and the holes of the plate-like member 48 are fitted. By combining them, the plate-like member 48 can be detachably attached to the side fence 28 and the end fence 29 in parallel with the placement surface 21 a of the paper stacking base 21.

  A plurality of shafts 52 are supported on the lower surface side of the plate-like member 48 in parallel with the paper width direction orthogonal to the discharge direction of the printed paper 4P, and the arm-like members 41 of the guide / holding member 40 are supported on the respective shafts 52. The base end portion 41a is pivotally supported so as to be relatively rotatable, and each guide and pressing member 40 is supported so as to be swingable. The number of the guide / holding members 40 is not limited to two, and may be one or three or more.

  In this embodiment, since the plate-like member 48 that supports each guide / holding member 40 is held by the side fence 28 and the end fence 29, the guide / holding member 40 on the front end side of the paper is a predetermined amount from the front end of the paper. It is attached to hold the position of distance N. Further, as shown in FIG. 12, each guide / holding member 40 is attached so as to hold the position at the optimum distance L from the side edge of the sheet.

  If the plate-like member 48 is held only by one side fence 28, or if the pair of side fences 28 hold the individual plate-like members 48, the side fence 28 according to the size in the width direction of the paper. Accordingly, the guide / holding member 40 supported by the plate-like member 48 is also moved. Therefore, even when the paper size changes, the position of the optimum distance L is always pressed from the side edge of the paper. Can do.

  Further, if the plate-like member 48 is held only by the end fence 29, the end fence 29 can be moved in accordance with the size in the paper discharge direction, and accordingly the guide supported by the plate-like member 48. Since the holding member 40 also moves, the position at a predetermined distance N from the leading edge of the paper can always be pressed even if the paper size changes.

  Since the plate-like member 48 is detachably attached to the side fence 28 and / or the end fence 29, the plate-like member 48 can be removed after the discharge stacking is completed, and thereby all the guide / holding members 40. Is removed from the sheet stacking table 21, it is easy to take out the printed sheets stacked on the sheet stacking table 21.

[Embodiment of Image Forming Apparatus]
As in the image forming apparatus main body 1 shown in FIG. 1, an image having an image forming unit that forms an image on a sheet, and a transport discharge unit that transports and discharges a printed sheet on which an image has been formed by the image forming unit. As the paper discharge stacking device for stacking the printed sheets sequentially discharged by the conveyance discharge unit, the sheet discharge stacking device according to any of the first to third embodiments described above is provided. An image forming apparatus can be configured.

The paper discharge stacking device can be configured by combining or changing the configurations of the embodiments and the configurations described in the first to third embodiments of the image forming apparatus.
The image forming apparatus main body is not limited to the one shown in FIG. 1, and even in the case of an ink jet image forming apparatus, the image forming apparatus main body is not limited to a full color image forming head unit in which four line type ink jet heads are provided in the image forming unit. Alternatively, a full-color image forming unit provided with a serial type ink jet head may be provided, or an image forming unit provided with a line type or serial type two-color or single color ink jet head may be provided.
Furthermore, the present invention is also effective when applied to an image forming apparatus that forms an image using another liquid recording agent, such as stencil printing.

  The present invention is applicable to various image forming apparatuses such as a printer, a plotter, a printing apparatus, a copying apparatus, a digital multifunction peripheral, and a facsimile apparatus, which correspond to an image forming apparatus that forms an image on paper using a liquid recording agent such as ink. In particular, it is suitable for an ink jet image forming apparatus and a stencil printing apparatus, and can also be applied to a line type ink jet image forming apparatus capable of high-speed printing.

1: Image forming apparatus main body 2: Image forming head units 3, 3 ', 3 ": Paper discharge stacking device 4: Paper 4P: Printed paper 5, 6: Pair of conveying rollers 7: Endless wide belt 12: Air suction duct 17, 18: Conveyance roller pair 19: Lower discharge roller pair 20: Upper discharge roller pair 20: Discharge roller pair upper discharge roller 21: Paper stacking base 21a: Placement surface 22, 27: Path switching claw member 23, 24: First reversal Roller pair 25, 26: second reversing roller pair 28: side fence 29: end fence 30, 31: guide and pressing member 30a, 31a: base end portion 30b, 31b: portion in contact with upper surface of printed paper 30c: straight line Edge 32, 34: shaft 33, 35: paper leading edge detection sensor 37: pressing release member 38: release knob 40: guide and pressing member 41: arm-like member 41a: base end Portion 41b: Tip portion 42, 43: Shaft 45: Disk-like member 45a: Protrusion 46: Support member 47: Shaft 48: Plate-like member 100a, 100b: Support member 191: Rotating shaft 192 of the lower discharge roller: Lower discharge roller 193, 194: Rolling roller 201: Rotating shaft of upper discharge roller 202: Upper discharge roller 281, 291: Projection

JP-A-2005-350182 JP-A-11-79519 Japanese Patent Laid-Open No. 2002-20024

Claims (17)

An image forming unit that forms an image on a sequentially fed paper with a liquid recording agent, a transport discharge unit that transports and discharges the printed paper on which an image has been formed by the image forming unit, and a discharge by the transport discharge unit A sheet stacking table on which printed sheets to be printed are stacked, and a printed sheet to be newly discharged is guided while pressing the upper surface of the sheet stacked on the sheet stacking table against the mounting surface of the sheet stacking table. A guide and holding member,
The guide / holding member is supported so as to be swingable in a direction in which the printed paper is pressed, and a portion in contact with the top surface of the printed paper is in line contact or a point along the top surface of the paper and the discharge direction of the paper. An image forming apparatus having a contact shape.   The guide / holding member is an arm-shaped member having a base end pivotally supported by a fixed portion of the apparatus main body, and a lower edge of the arm-shaped member is a linear edge parallel to the discharge direction of the printed paper. 2. The image forming apparatus according to claim 1, wherein the edge of the edge is in line contact or point contact with an upper surface of the printed sheet along a discharge direction of the sheet.   The guide / holding member is freely rotatable by an arm-like member whose base end is pivotally supported by a fixed portion of the apparatus main body, and a shaft in a direction perpendicular to the discharge direction of the printed paper at the tip of the arm-like member. A plurality of protrusions having sharp tips along the outer periphery of the disk-shaped member, and the tips of the protrusions are formed on the upper surface of the printed paper. The image forming apparatus according to claim 1, wherein the image forming apparatus is in point contact. The transport and discharge unit includes a pair of discharge rollers that discharges the printed paper on which the image is formed to the paper stacking table while sitting down,
4. The guide / holding member is pivotally supported by a rotation shaft supported by an apparatus main body of a discharge roller on the upper side of the discharge roller pair. The image forming apparatus described in 1.   5. The image forming apparatus according to claim 1, wherein the sheet stacking table is lowered in accordance with an increase in the number of printed sheets stacked on the sheet stacking table. In the image forming apparatus according to any one of claims 1 to 5,
An image forming apparatus, comprising: a pressing release member that rotates the guide and pressing member to a position where the upper surface of the printed paper discharged and stacked on the paper stacking table is not pressed. A paper discharge stacking device in which printed sheets are sequentially discharged from the image forming apparatus and stacked.
A sheet stacking table having a mounting surface for receiving the lower surface of the printed paper, and a pair of side fences for guiding both ends in the width direction perpendicular to the direction in which the printed paper is discharged,
The pair of side fences is movable in the width direction according to the paper size,
The printed sheets to be newly discharged are guided to the inner surfaces of the pair of side fences facing each other while pressing the upper surface of the printed sheets discharged and stacked on the placement surface toward the placement surface. A guide / holding member that is pivotally supported in a direction to press the paper,
The discharge and stacking apparatus according to claim 1, wherein the guide / holding member has a shape in which a portion in contact with the upper surface of the printed sheet is in line contact or point contact with the upper surface of the sheet along the discharge direction of the sheet.   8. The paper discharge stack according to claim 7, wherein a plurality of pairs of the guide / holding members are provided on the inner surface of each of the pair of side fences facing each other at an interval in the discharge direction of the printed paper. apparatus.   The guide / holding member is rotatably supported by an arm-like member whose base end is pivotally supported by the side fence and an axis in a direction perpendicular to the discharge direction of the printed paper at the distal end of the member. A large number of protrusions having sharp tips along the outer periphery of the disk-shaped member, and the tips of the protrusions are in point contact with the upper surface of the printed paper. 9. The paper discharge stacking apparatus according to claim 7 or 8, wherein A paper discharge stacking device in which printed sheets are sequentially discharged from the image forming apparatus and stacked.
A paper stacking base having a placement surface for receiving a lower surface of the printed paper, and an end fence for stopping the paper by contacting a tip of the printed paper discharged to the paper stacking base,
The end fence is movable in the discharge direction of the printed paper according to the paper size,
A guide / holding member for guiding the newly printed paper to be discharged while pressing the upper surface of the printed paper discharged and stacked on the placement surface on the inner surface side of the end fence toward the placement surface. Is provided so as to be swingable in the direction of pressing the paper,
The discharge and stacking apparatus according to claim 1, wherein the guide / holding member has a shape in which a portion in contact with the upper surface of the printed sheet is in line contact or point contact with the upper surface of the sheet along the discharge direction of the sheet.   11. The paper discharge according to claim 10, wherein a base end portion of the guide / holding member is pivotally supported by a support member that extends from the end fence to an upstream side in a discharge direction of the printed paper. Loading device.   The guide / holding member is rotatably supported by an arm-like member whose base end portion is pivotally supported by the support member, and an axis in a direction perpendicular to the discharge direction of the printed paper at the distal end portion of the arm-like member. A large number of protrusions having a sharp tip along the outer periphery of the disk-shaped member, and the tips of the protrusions are in point contact with the top surface of the printed paper. The paper discharge stacking apparatus according to claim 11, wherein In the paper discharge stacking device according to any one of claims 7 to 12,
A paper discharge stacking apparatus, comprising: a pressing release member that rotates the guide and pressing member to a position where the upper surface of the printed paper discharged and stacked on the paper stacking base is not pressed.   The said guide and pressing member was provided in the plate-shaped member attached to at least one of the said side fence and the said end fence so that attachment or detachment was possible, It is characterized by the above-mentioned. Paper discharge stacking device.   An image forming apparatus main body having an image forming unit that forms an image on a sheet, a transport discharge unit that transports and discharges a printed sheet on which an image has been formed by the image forming unit, and the transport discharge unit sequentially discharges the sheet. 15. An image forming apparatus comprising: the paper discharge stacking device according to claim 7 for stacking printed sheets.   The image forming apparatus according to claim 1, wherein the image forming unit is an inkjet head type image forming unit including one or more inkjet heads.   The image forming apparatus according to claim 16, wherein the inkjet head is a line-type inkjet head.

Images