JP2012188210A - Ejected paper loading equipment and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a curl of a printed sheet of paper by using an image forming system, and to load a sufficient amount of sheets of paper.SOLUTION: This ejected paper loading equipment has: a paper output tray 21 which receives the bottom face of a printed sheet of paper 4P; and a pair of side fences 28a and 28b for guiding both ends in a crosswise direction perpendicular to an ejecting direction of the sheets of printed paper 4P. The pair of side fences 28a and 28b can move in the crosswise direction according to a paper size, and are provided with guiding and pressing members 30a that guide the printed sheet of paper which is newly ejected on the internal face opposing to the side fences 28a and 28b, respectively, while pressing top faces of the sheets of printed paper 4P which are ejected and loaded on the paper output tray 21 with a predetermined pressing force from above so as to hold the loaded sheets of printed paper 4P to be swung in a pressing direction.

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. Curling occurs because the image surface of the paper expands and expands 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. 7 and FIG. 8 schematically show how printed sheets are stacked when a conventional paper discharge stacking apparatus is used in a line-type inkjet image forming apparatus using water-based ink.
FIG. 7 shows the case where the image plane is lower, and FIG. 8 shows the case where the image plane is upper. 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, in an image forming apparatus in which an image-formed sheet is discharged onto a sheet mounting table that rises steeply, a flexible sheet is provided near the rear end of the sheet discharged by a pair of discharge rollers. It is disclosed that the sheet is pressed and held by a pressing member with a pressing member.

  Patent Document 2 discloses a sheet stacking apparatus that discharges a folded sheet, and includes a top surface of the folded sheet that is discharged and stacked on a lower tray, and a guide roller at a leading end. It is disclosed that a pressure arm biased by a spring is pressed and the load on the arm is lowered as the sheet stacking height is lower.

  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, the method described in Patent Document 1 is to prevent the sheet stacking order from being out of order and jamming even if the sheet discharged to the mounting table is once taken out and then returned to the mounting table. The one described in 2 improves the stackability of the folded sheets, and the one described in Patent Document 3 enables stable paper conveyance without causing a decrease in conveyance force due to paddle wear. Each of which is intended to suppress the curling of printed paper.

  In particular, as in the ink jet image forming apparatus, a sheet on which an image is formed on one surface with water-based ink is easily curled as described above, and the curled state varies depending on the orientation of the image surface when the printed sheet is discharged. A configuration that can effectively suppress such curling is not disclosed.

  In addition, various sizes of paper are used in the image forming apparatus. However, in the apparatuses described in each of the above-described patent documents, the arrangement of members that hold the discharged paper is fixed, so that the size varies depending on the paper size. Therefore, it was impossible to hold the optimal position for curling.

The present invention has been made in view of such a situation, and when printed sheets in an image forming apparatus are sequentially discharged and stacked on a mounting surface (discharge tray), they are discharged while curling. The printed paper to be printed is surely guided onto the paper discharge tray, and curling of the printed paper is prevented from proceeding on the paper discharge tray, so that it is hardly curled when the user removes it. For the purpose.
There are provided a paper discharge stacking apparatus and an image forming apparatus having the same.

A sheet discharge stacking apparatus according to the present invention is a sheet discharge stacking apparatus in which printed sheets in an image forming apparatus are sequentially discharged and stacked, and is configured as follows to achieve the above object.
That is, it has a mounting surface that receives the lower surface of the printed paper, and a pair of side fences that guide both ends in the width direction perpendicular to the direction in which the printed paper is discharged. The side fence can be moved in the width direction according to the paper size, and the upper surface of the side of the printed paper discharged and stacked on the placement surface is placed on each of the opposing inner surfaces of the pair of side fences. A guide / holding member that guides newly ejected printed paper while being pressed with a predetermined pressing force from above is provided so as to be swingable in the direction in which the stacked printed paper is pressed. And

A plurality of pairs of the guide / holding members may be provided on the inner surfaces of the pair of side fences facing each other at intervals in the discharge direction of the printed paper.
Each of the guide / holding members is preferably provided with a pressing force variable mechanism for changing a pressing force for pressing the stacked printed sheets from above.
The pressing force variable mechanism includes an arm member that is integrally fixed to the guide / holding member from the vicinity of the swinging fulcrum of the guide / holding member and extends in the discharge direction of the printed paper, and the arm member from the swinging fulcrum. It is good to consist of the weight member which provided the distance of variably.

Each guide / holding member is preferably provided with a push position variable mechanism that variably adjusts the protruding distance from one inner surface of the pair of side fences toward the other side fence.
Each of the guide / holding members may be held such that the length from the swinging fulcrum to the portion in contact with the printed paper is adjustable.

An image forming apparatus according to the present invention includes an image forming apparatus main body having an image forming unit that forms an image on a sheet, a discharge unit that discharges a printed sheet on which an image is formed by the image forming unit, and the discharge unit sequentially. One of the above-described paper discharge stacking devices for stacking printed paper to be discharged is provided.
The discharge unit preferably includes a discharge roller pair that discharges the printed paper on which the image is formed to the discharge stacking device while sitting on the sheet.
The pair of discharge rollers includes a lower discharge roller and an upper discharge roller, and a plurality of rollers are alternately shifted in the axial direction on each rotation shaft, and the roller of the lower discharge roller and the upper discharge roller It is preferable that the rollers are provided so as to partially overlap in the radial direction.

A plurality of rollers provided on the lower discharge roller and the upper discharge roller may be movable and fixed in the axial direction of each rotation shaft.
A holding member that can rotate relative to the rotation shaft is provided at the center of the rotation axis of the upper discharge roller, and the center in the width direction of the printed sheets stacked on the discharge stacking device is provided. It is more preferable that a central guide / holding member for pressing the sheet from above while being guided is provided integrally with the holding member.
This is particularly effective when the image forming unit is an ink jet head type image forming unit including one or more ink jet heads and the ink jet head is 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 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, etc. on a sheet by a recording agent such as ink.

The paper discharge stacking apparatus according to the present invention curls and stacks on a mounting surface (paper discharge tray) when printed sheets on which images are formed are sequentially discharged and stacked in the image forming apparatus. It becomes possible to guide the newly ejected printed paper while pressing the upper surface of the finished paper from above with a predetermined pressing force at an appropriate position according to the paper size.
As a result, the printed paper stacked on the paper discharge tray curls up abnormally at the edges and center of the paper, causing the trouble that the next printed paper hits and jams. Thus, a sufficient number of printed sheets can be discharged and stacked normally.
Therefore, it can sufficiently cope with a line-type inkjet image forming apparatus capable of high-speed printing.

1 is a schematic view showing a main part of an embodiment of an image forming apparatus according to the present invention. FIG. 2 is an enlarged view showing an upstream half of a discharged paper stacking apparatus in FIG. 1 in a printed paper discharge direction. FIG. 2 is an enlarged view of the paper discharge stacking device in FIG. 1 with the end fence removed from the end fence side. FIG. 4 is a schematic view of a discharge roller pair on the image forming apparatus main body side through a discharge stacking device from which a guide / holding member and related members are removed from the same side as FIG. 3. It is a figure similar to FIG. 3 of other embodiment of this invention. FIG. 5 is a plan view of the paper discharge stacking apparatus as viewed from above together with the discharge roller pair. 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.
FIG. 1 is a schematic diagram showing the main part of an embodiment of an image forming apparatus according to the present invention. The image forming apparatus shown in FIG. 1 includes an image forming apparatus main body 1 having an image forming unit that forms an image on a sheet, and a discharge unit that discharges a printed sheet on which an image has been formed by the image forming unit. A paper discharge stacking device 3 for stacking printed sheets sequentially discharged by the printing unit is 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 discharge stacking apparatus 3 is in a state where the front side fence and the like are removed. Is shown.

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.
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. As the ink is conveyed, yellow (Y), magenta (M), cyan (C), and black (K) water-based inks are sequentially ejected from the nozzles at the tips of the inkjet heads 13 to 16 to the surface of the paper 4. To form a full-color image. 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 paper is discharged toward the paper discharge tray 21 of the paper discharge stacking device 3. Thus, a discharge unit that discharges printed paper on which an image is formed by the image forming unit is configured.
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 reverse roller pair 23 and 24 and the second reverse roller pair 25 and 26 in the reverse direction, 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 give a discharge force, and is discharged toward the discharge tray 21 of the discharge stacking device 3.

This is a stacking method necessary when the printed sheets 4P printed in page order are arranged in page order when stacked. That is, the printed paper 4P is sequentially stacked on the paper discharge tray 21 of the paper discharge stacking device 3 with the image surface facing downward.
In addition to this, there is a case in which the paper 4 is printed on both sides and then discharged to the paper discharge stacking device 3. However, in FIG. 1, the illustration of the conveyance path for double-sided printing for that purpose is omitted, and the description thereof is also omitted. .

Next, the paper discharge stacking device 3 will be described with reference to FIGS. These are one embodiment of the paper discharge stacking apparatus according to the present invention.
The paper discharge tray 21 of the paper discharge stacking device 3 is a plate-like member having a mounting surface, on which a direction (in the direction of arrow B) orthogonal to the direction (arrow B direction) in which the printed paper 4P is discharged. A pair of side fences 28a and 28b for positioning in the width direction and the front end of the printed paper 4P are guided by guiding both ends (both ends) of the width direction) and positioned in the discharge direction. An end fence 29 is provided.

  The pair of side fences 28a and 28b slide in the width direction (left and right direction in FIG. 3) so that the dimension of the distance H between the opposed inner surfaces a and b shown in FIG. 3 can be adjusted to the optimum value according to the paper size. It is possible. Similarly, the position of the end fence 29 in the paper discharge direction is slidable in the paper discharge direction so that it can be adjusted to the optimum position according to the paper size. Since these slide structures are the same as in the prior art, the description thereof is omitted.

  On the inner surface side of one side fence 28a, the printed paper 4P to be newly discharged is pressed while pressing the upper surface of the side of the printed paper 4P discharged and stacked on the paper discharge tray 21 from above with a predetermined pressing force. The guide / holding member 30a is provided so as to be swingable in the direction in which the stacked printed sheets 4P are pressed. In this embodiment, two guide / holding members 30a are provided at intervals in the discharge direction of the printed paper 4P.

  Each guide / holding member 30a is swingably held around a shaft 32a rotatably provided on the side fence 28a, and a predetermined pressing force acts clockwise in FIG. It is energized.

Two similar guide / holding members are also provided on the inner surface of the other side fence 28b facing the side fence 28a. FIG. 3 shows the guide / holding members 30a, 30b and the shaft 32a, 32b is shown. Two sets of the guide / holding members 30a and 30b and the shafts 32a and 32b are also provided at intervals in the discharge direction of the printed paper 4P.
Accordingly, a plurality of pairs (two pairs in this example) of the guide / holding members 30a and 30b are provided on the inner surfaces of the pair of side fences 28a and 28b facing each other at intervals in the discharge direction of the printed paper 4P. Yes. Three or more pairs of the guide / holding members 30a and 30b may be provided.

  FIG. 2 is an enlarged view of the upstream portion of the discharged paper stacking apparatus 3 in FIG. 1 in the printed paper discharge direction. FIG. 3 is an enlarged view of the paper discharge stacking device 3 in FIG. 1 as viewed from the end fence 29 side. The end fence 29 is removed and indicated by a virtual line. The printed paper 4P is stacked with the image surface facing downward, and the image surface side is expanded by water-based ink and is curled so that both ends in the width direction are lifted.

  As shown in these drawings, the side fence 28a is provided with a pivotable shaft 32a penetrating the side fence 28a, and has a diameter near the end of the portion of the shaft 32a protruding inside the side fence 28a. The guide / holding member 30a is held through the through hole formed in the direction.

  The guide / holding member 30a is made of, for example, a stainless steel rod having a diameter of about 1 to 3 mm, and extends in a substantially straight line from the shaft 32a obliquely downward in the discharge direction of printed paper (arrow B direction). The portion in contact with the printed paper 4P is bent upward. The bent portion c is preferably bent in an arc shape.

  The effective length L from the center of the shaft 32a, which is the swing fulcrum of the guide / holding member 30a, to the bent portion c that contacts the printed paper can be adjusted. That is, the guide / holding member 30a penetrates the through hole of the shaft 32a so as to be slidable, and the shaft 32a is provided with a knob screw 34a screwed in a radial direction perpendicular to the through hole. After adjusting 30a to slide into the through hole of the shaft 32a to the optimum position, the knob screw 34a can be screwed in and fixed.

  An arm member 36a that extends obliquely upward in the discharge direction (arrow B direction) of the printed paper 4P is fixed near the end of the portion of the shaft 32a that protrudes outside the side fence 28a. A weight member 37a is movably pierced through the shaft, and the pressing force of the guide / holding member 30a can be varied by shifting the position of the weight member 37a. The gravity of the weight member 37a has an action of urging the guide / holding member 30a clockwise in FIG.

When the operator moves the weight member 37a, the distance from the center of the shaft 32a, which is the swing fulcrum of the arm member 36a, to the center of gravity of the weight member 37a changes, whereby the rotational moment of the shaft 32a changes, The pressing force indicated by the arrow D in FIG. 2 of the guide / holding member 30a changes.
For example, if the weight member 37a is moved from the position indicated by the broken line to the position indicated by the phantom line in FIG. 2, the rotational moment of the shaft 32a is reduced, and the pressing force of the guide / holding member 30a is weakened.

  Therefore, the shaft 32a, the arm member 36a, and the weight member 37a provide a pressing force variable mechanism that changes the pressing force that the guide and pressing member 30a presses the printed sheets 4P stacked on the paper discharge tray 21 from above. It is composed. If click mechanisms are provided at a plurality of positions in the sliding direction of the sliding portion between the arm member 36a and the weight member 37a, the weight member 37a can be fixed to the arm member 36a at a plurality of positions. The power can be adjusted in multiple stages.

  Further, as shown in FIG. 3, the shaft 32a slidably passes through a bearing portion 38a fixed to the side fence 28a, and a knob screw 39a screwed in the radial direction is provided in the bearing portion 38a, and the knob screw 39a is provided. By screwing, the shaft 32a can be fixed to the side fence 28a at an arbitrary sliding position.

Therefore, the amount of protrusion of the shaft 32a to the inside can be adjusted, thereby variably adjusting the protrusion distance M (FIG. 3) from the inner surface of the side fence 28a of the guide / holding member 30a toward the other side fence 28b. be able to.
That is, the shaft 32a, the bearing portion 38a, and the knob screw 39a constitute a push position variable mechanism that variably adjusts the protrusion distance M.

The left side fence 28b shown in FIG. 3 is also provided symmetrically with the same members as the guide / holding member 30a and the related members.
That is, a pivotable shaft 32b is provided through the side fence 28b, and a through hole formed in the radial direction near the end of the shaft 32b protruding inside the side fence 28b is guided and pressed. The member 30b is held through.
The effective length (corresponding to L shown in FIG. 2) from the center of the shaft 32b, which is the swing fulcrum of the guide / holding member 30b, to the bent portion that contacts the printed paper is adjusted by loosening the knob screw 39b. Is possible.

An arm member 36b is fixed in the vicinity of the end of the portion of the shaft 32b that protrudes outside the side fence 28b. A weight member 37b is movably penetrated through the arm member 36b. By shifting the position, the pressing force of the guide and pressing member 30b can be varied.
Further, the shaft 32b, the bearing portion 38b, and the knob screw 39b constitute a mechanism for variably adjusting the protrusion distance M from the inner surface of the side fence 28b of the guide / holding member 30b toward the other side fence 28a.

  In the pair of side fences 28a and 28b, the pair of guide / holding members 30a and 30b and the same members as those described above are spaced apart from each other in the discharge direction (arrow B direction) of the printed paper 4P. One set is provided. In FIG. 1, only the guide / holding member 30a and the shaft 32a on the side fence 28a side are shown.

As described above, in the paper discharge stacking device 3 of this embodiment, a total of four guide / holding members are pressed from above to prevent curling while guiding the discharge and conveyance of the printed paper 4P.
The printed paper 4P is discharged onto the paper discharge tray 21 while being guided by two pairs of guide / holding members 30a and 30b in the direction of arrow B in FIGS. 1 and 2, and further curl formation is suppressed from above. Pressed down.

  In this example, the printed paper 4P is sequentially stacked on the paper discharge tray 21 with the image surface facing downward, so that it is easy to curl so that the vicinity of both ends in the width direction is lifted as shown in FIG. For this reason, it is desirable to suppress the vicinity of both ends in the width direction of the printed paper 4P by the guide / holding members 30a and 30b in order to suppress curling.

The pair of side fences 28a and 28b on the paper discharge tray 21 are held so as to be slidable in the left-right direction in FIG. 3 so that the distance between them can be changed according to the paper size. Therefore, the inner span dimension H, which is the distance between the inner surfaces a and b of the side fences 28a and 28b, is optimally set according to the paper size.
Further, the distance M (the protrusion distance described above) M from the inner surfaces a, b of the side fences 28a, 28b to the guide / holding members 30a, 30b is also optimal as described above according to the thickness of the printed paper and the curled state. Can be adjusted to a value.

Since the guide / holding members 30a, 30b are held by the pair of side fences 28a, 28b as described above, the positions where the guide / holding members 30a, 30b are pressed from the widthwise ends of the printed paper 4P. The distance between the side fences 28a and 28b can be adjusted in accordance with the paper size while keeping the above-mentioned distance M corresponding to the distance up to.
Accordingly, the distance M from the end in the width direction to the pressing position can be made constant regardless of the paper size.

When the printed paper 4P stacked on the paper discharge tray 21 is taken out, the end fence 29 is tilted and pulled to the right in FIG. It can be easily taken out without
When the printed paper is taken out, the guide / holding members 30a and 30b naturally escape upward so that they do not interfere.

Next, details of the discharge roller pair on the ink jet image forming apparatus main body 1 side shown in FIG. 1 will be described with reference to FIGS.
FIG. 4 is a schematic view of the discharge roller pair on the image forming apparatus main body side through the discharge stacking apparatus from which the guide / holding member and related members are removed from the same side as FIG.

  A pair of discharge rollers constituting a main part of the paper discharge unit includes a lower discharge roller 19 as a driving roller and an upper discharge roller 20 as a driven roller, and the rotation shafts 191 and 201 are provided in the image forming apparatus main body 1. Are rotatably supported by a pair of support members 100a and 100b provided on the fixed frame, and are arranged in parallel to the width direction orthogonal to the discharge direction of the printed paper 4P.

The rotating 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 knob screw 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. 2 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 members 30a and 30b, 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 surely discharged onto the paper discharge tray 21 of the paper discharge stacking device 3 without 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 from the inner surfaces of the side fences 28a and 28b of the paper discharge stacking device 3. Can be optimally adjusted. 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.

Next, another embodiment of the present invention will be described with reference to FIGS.
FIG. 5 is a view similar to FIG. 3 in the above-described embodiment of this embodiment, but shows an example in which the printed paper 4P is discharged with the image surface facing upward. FIG. 6 is a plan view of the paper discharge stacking device 3 viewed from above with the discharge roller pair. In these drawings, portions corresponding to those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 6, all of the four guide / holding members 30a and 30b provided on the side fences 28a and 28b and their related members are shown. These are the same as in the previous embodiment.

  When the printed paper 4P is curled and ejected upward as viewed in the width direction, the distance M from the side fences 28a, 28b to the guide / holding members 30a, 30b is increased to suppress the curl. I need to do it. It is desirable to provide a central guide / holding member 40.

  FIG. 5 shows the central guide / holding member 40, but the lower discharge roller 19 and the upper discharge roller 20 are not shown. FIG. 6 shows the lower discharge roller 19 and the upper discharge roller 20, but the rotation shaft 191 of the lower discharge roller 19 overlaps the lower side of the rotation shaft 201 of the upper discharge roller 20 and is not visible.

  As shown in FIG. 6, the central guide / holding member 40 in the paper discharge stacking apparatus 3 of this embodiment can be rotated relative to the rotary shaft 201 at the center in the axial direction of the rotary shaft 201 of the upper discharge roller 20. Is provided integrally with the holding member 41 and extends in the discharge direction of the printed paper 4P. Accordingly, the central guide / holding member 40 does not rotate regardless of the rotation of the rotary shaft 201, and has a function of pressing from the top by its own weight while guiding the central portion of the printed paper 4P to be discharged. As a result, curling of the central portion of the printed paper 4P on the paper discharge tray 21 is suppressed.

  The printed paper 4P discharged by the lower discharge roller 19 and the upper discharge roller 20 from the left side to the right side in FIG. 6 is guided by the pair of side fences 28a and 28b and stops by colliding with the end fence 29. . At that time, the center guide / holding member 40 and the left and right guide / holding members 30a and 30b are guided while curling upward from the upper surface.

  Further, even after being stacked on the paper discharge tray 21, these guide / holding members 30a, 30b, and 40 serve to prevent subsequent increase in curl. In the paper discharge stacking device 3, the printed paper 4P is guided and curled by a total of four guide / holding members 30a and 30b provided on the side fences 28a and 28b. The values of the pressing force P, the effective length L (see FIG. 2) of each guide / holding member 30a, 30b, and the distance M from the side end surface of the paper are the direction of curl formation and the printing rate by the image surface of the printed paper 4P. It is desirable to optimally variably adjust according to (ink discharge amount), the type and thickness of the paper, and the like.

An example is shown in Table 1. When the image surface is on the top, if the printing rate is high, the printed material curls in the direction in which the central portion rises. Therefore, it is effective if the central guide / holding member 40 is operated effectively, and the guide / pressing members 30a, 30b of the side fences 28a, 28b are also set to operate with a large dimension M (60 mm).
When the image surface is below and the printing rate is large, the printed material curls in a direction in which both ends rise. Therefore, the guide / holding members 30a, 30b of the side fences 28a, 28b that hold both ends are effectively operated. In this case, it is effective to set the dimension M to be small (30 mm).

In either case, if the paper is thin, the pushing force P of the guide / holding members 30a and 30b is small (10 gf), but if the paper is thick, the pushing force P is not large (30 gf), and there is no effect. However, it should be noted that if it is pressed with too much force, rubbing stains will be generated, or it will become a brake of the conveying force of the printed paper 4P and stop in the middle.
In the case of thin paper, it is better to make the effective length L of the guide / holding members 30a, 30b longer (100 mm), and in the case of thick paper, it is better to make the effective length L shorter (60 mm). . Here, the thin paper is a paper up to 80 g / m ² , and the thick paper is a paper of 81 g / m ² or more.

As described in the above-described embodiments, the paper discharge stacking apparatus according to the present invention guides the paper discharge tray 21 having the placement surface for receiving the lower surface of the printed paper and both ends in the width direction of the printed paper. A pair of side fences 28a and 28b are provided, and the side fences 28a and 28b are movable in a direction (width direction) perpendicular to the discharge direction of the printed paper according to the paper size.
Then, while holding the upper surface of the printed paper discharged and stacked on the paper discharge tray 21 on the pair of side fences 28a and 28b from above with a predetermined pressing force, the upper surface edge of the newly discharged printed paper. Guide / holding members 30a and 30b formed so as to guide the sheet are provided so as to be swingable in the direction of pressing the paper.

Therefore, the image forming apparatus provided with the paper discharge stacking device 3 curls the printed paper by the image surface when the printed paper on which the image is formed by the image forming unit is sequentially discharged and stacked. Even if this occurs, it is possible to guide the printed paper onto the paper output tray while holding down the curl, and the printed paper on the paper output tray will curl up abnormally at the edges and center of the paper. Thus, it is possible to prevent the trouble that the next printed paper collides with the paper and jams it, and to discharge and stack a sufficient number of printed papers normally.
Therefore, it is particularly effective for an ink jet image forming apparatus, and can sufficiently cope with a line type ink jet image forming apparatus capable of high-speed printing.

Further, by providing a plurality of guide / holding members 30a, 30b on the side fences 28a, 28b side by side from the leading side in the discharge direction of the printed paper to the downstream side,
Even if the paper size of the printed material is large, jamming occurs while guiding the paper while curling the paper not only on both ends in the width direction of the printed paper but also on the leading and trailing sides of the paper. In addition, it is possible to prevent the curling from increasing and obtain a flat printed matter by pressing the paper at many points on the paper discharge tray.

  By providing a pressing force variable mechanism that variably adjusts the pressing force of the guide / holding members 30a, 30b from above in multiple stages, depending on the degree of curl depending on the printing rate, paper type, thickness, etc. It is possible to press the guide / holding member against the printed paper with the optimum pressing force, and while exhibiting the curl pressing effect, the occurrence of scratches on the image surface, which is a concern when the pressing force is large, An increase in conveyance resistance can be minimized.

  Further, the guide / holding members 30a and 30b are provided with a push position variable mechanism that variably adjusts the protruding distance from the inner surface of each of the left and right side fences 28a and 28b. Regardless of the curl or the concave curl when the image surface is below, the curl of the paper can be effectively curled by adjusting the distances from the inner surfaces of the side fences 28a and 28b of the guide / holding members 30a and 30b. It is possible to normally stack printed sheets without causing jamming.

The ink jet image forming apparatus according to the above-described embodiment includes the full color image forming head unit 2 in which the four color line ink jet heads are provided in the image forming unit, but the full color image in which the serial ink jet head is provided. A forming unit may be provided, or an image forming unit provided with a line-type or serial-type two-color or single-color inkjet head may be provided.
Furthermore, even if the paper discharge stacking apparatus and the image forming apparatus according to the present invention are applied to other types of image forming apparatuses, they can discharge and stack paper while curling the printed paper. it can.

  Moreover, although each embodiment mentioned above demonstrated the best form, since all the structures are not essential, each member other than the member described in Claim 1 may be abbreviate | omitted suitably according to a use. it can. Furthermore, the shape and structure of the members and mechanisms described in each embodiment can be changed as appropriate, and it is needless to say that other members can be added.

  The present invention can be applied 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 recording agent such as ink. In particular, it is suitable for an ink jet image forming 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 unit 3: Paper discharge stacking device 4: Paper 4P: Printed paper 5, 6: Conveying roller pair 7: Endless wide belt 12: Air suction duct 17, 18: Conveying roller Pair 19: Lower discharge roller pair of discharge roller 20: Upper discharge roller pair of discharge roller 21: Paper discharge tray (having a mounting surface) 22, 27: Path switching claw members 23, 24: First reverse roller pair 25, 26: second reversing roller pair 28a, 28b: side fence 29: end fence 30a, 30b: guide and pressing member 32a, 32b: shaft 33, 35: paper leading edge detection sensor 34a, 34b: knob screw 36a, 36b: arm member 37a , 37b: Weight member
38a, 38b: Bearing portions 39a, 39b: Knob screw 40: Center guide / holding member 41: Holding members 100a, 100b: Support member 191: Rotating shaft of lower discharge roller 192: Lower discharge roller 193, 194: Rolling roller 201: Rotating shaft of upper discharge roller 202: Upper discharge roller

JP-A-11-79519 JP 2006-137571 A Japanese Patent Laid-Open No. 2002-20024

Claims (13)

A paper discharge stacking device in which printed sheets in an image forming apparatus are sequentially discharged and stacked,
A mounting surface that receives the lower surface of the printed paper, and a pair of side fences that guide 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,
On the inner surfaces facing each other of the pair of side fences, the printed paper is newly discharged while pressing the upper surface of the side of the printed paper discharged and stacked on the mounting surface from above with a predetermined pressing force. A paper discharge stacking device, characterized in that a guide and pressing member for guiding paper is provided so as to be swingable in a direction in which the stacked printed paper is pressed.   2. The exhaust according to claim 1, wherein a plurality of pairs of the guide / holding members are provided on the inner surfaces facing each other of the pair of side fences at intervals in the discharge direction of the printed paper. Paper loading device.   3. The paper discharge stack according to claim 1, wherein each of the guide / holding members is provided with a pressing force variable mechanism that changes a pressing force for pressing the stacked printed sheets from above. apparatus.   The variable pressing force mechanism includes an arm member that is integrally fixed to the guide / holding member from the vicinity of the swinging fulcrum of the guide / holding member and extends in the discharge direction of the printed paper, and the swinging fulcrum on the arm member. The paper discharge stacking apparatus according to claim 3, comprising a weight member variably provided at a distance from the paper discharge unit.   Each of the guide / holding members is provided with a pressing position variable mechanism that variably adjusts a protruding distance from one inner surface of the pair of side fences toward the other side fence. 5. The paper discharge stacking apparatus according to any one of 4 above.   The said each guide and pressing member is hold | maintained so that adjustment of the length from the rocking | fluctuation fulcrum to the part contact | abutted with the said printed paper is possible. Paper output stacking device.   An image forming apparatus main body having an image forming unit that forms an image on a sheet and a discharge unit that discharges a printed sheet on which an image is formed by the image forming unit, and stacked printed sheets sequentially discharged by the discharge unit An image forming apparatus comprising: the paper discharge stacking device according to claim 1.   The image forming apparatus according to claim 7, wherein the discharge unit includes a discharge roller pair that discharges the printed paper on which the image is formed to the discharge stacking device while sitting down.   The pair of discharge rollers includes a lower discharge roller and an upper discharge roller, and a plurality of rollers are alternately shifted on the respective rotation shafts so that the positions of the lower discharge roller and the upper discharge roller are alternately shifted. The image forming apparatus according to claim 8, wherein the roller is provided so as to partially overlap with the roller.   The image forming apparatus according to claim 9, wherein the plurality of rollers provided on the lower discharge roller and the upper discharge roller are movable and fixed in an axial direction of each rotation shaft. The image forming apparatus according to claim 9 or 10, wherein:
A holding member capable of rotating relative to the rotation shaft is provided at a central portion in the axial direction of the rotation shaft of the upper discharge roller,
A central guide / holding member for pressing the paper from above while guiding the central portion in the width direction of the printed paper stacked on the paper discharge stacking device is provided integrally with the holding member. An image forming apparatus.   The image forming apparatus according to claim 7, wherein the image forming unit is an ink jet head type image forming unit including one or more ink jet heads.   The image forming apparatus according to claim 12, wherein the ink jet head is a line type ink jet head.

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