JP5065073B2 - Paper discharge device - Google Patents

Description

  The present invention relates to a paper discharge device provided in an image forming apparatus such as a printing machine and a copying machine, which receives paper on which an image has been formed by an image forming unit such as a printing unit, and conveys the paper on a discharge path to form a paper tray. The present invention relates to a paper discharge device having a paper transport mechanism for discharging upward.

  Conventionally, a water-in-oil type emulsion ink containing an oil component has been mainly used as an ink for an image forming apparatus, for example, a stencil printing machine, but nowadays, an oil component is used instead of the water-in oil type ink. Has been proposed to use water-based inks having 0 or substantially 0 (for example, Patent Document 1). That is, by making the oil component substantially zero, the generation of odor is suppressed, the influence on the environment is reduced, and the drying efficiency is improved.

  However, when water-based ink is used, the above-described advantages can be obtained, but after printing, ink moisture rapidly infiltrates from the surface of the paper, so that a paper entrainment phenomenon, that is, a curling phenomenon occurs rapidly.

  FIG. 13 specifically shows the process of the curl phenomenon, and the paper P is in a flat state as shown in the uppermost stage (A1) during printing. As shown in the second step (A2), the left and right end portions are curled back to the opposite side to the printing surface (upper surface) Pa side as shown in the second step (A2), and further, the entire sheet P as shown in the third step (A3). Is deformed into an inverted U shape that is convex toward the printing surface Pa side. Note that, as shown in FIG. 13, the paper P whose left and right ends are curled is a paper mainly having paper fibers extending in the paper transport direction. Incidentally, the reverse U-shaped change of the paper P shown in (A1) to (A3) of FIG. 13 appears remarkably in a short time on a paper whose upper surface is lacquer-coated, for example, 1 second after printing. Deforms in a few seconds.

  When the paper P is discharged onto the paper tray in the deformed state or the deformed state as in the second stage (A2) or the third stage (A3) in FIG. 13, as shown in FIG. When the paper P is stacked, the left and right ends of the paper P are stacked inside, and the alignment of the paper P is deteriorated and the quality of the paper P is also deteriorated. Of course, it becomes difficult to keep the height of the stacking surface of the paper P constant.

  In order to prevent the occurrence of the curl, conventionally, a paper discharge device having several curl generation preventing functions has been developed (Patent Document 1, etc.). FIG. 12 shows an example of this, and a brief description will be given assuming that the paper width direction orthogonal to the paper transport direction F is the left-right direction. The paper discharge device conveys the printed paper P continuously supplied from a printing unit (not shown) on the side of reference A in the direction of arrow F on the discharge path by a pair of left and right conveying belts 110, thereby conveying the paper. It is configured to discharge from a downstream end portion to a paper cradle disposed on the reference B side. In order to stably and reliably convey the paper P, a plurality of air suction ports 111 are formed on the passage surface of the conveyance belt 110 in the discharge path, and a number of air suction holes 113 are also formed in each conveyance belt 110. In addition to this, in order to prevent the curling phenomenon of the paper P, the left and right ends of the paper P are pushed up further to the left and right sides of the conveyance belt 110 to push the paper P into a U shape. A guide 114 is arranged.

That is, after printing, the central portion of the left and right width of the paper P is adsorbed to the transport belt 110 by the air suction action of the suction port 110 with respect to the paper P conveyed on the discharge path of the paper discharge device, while being pushed up to the left and right By pushing up the left and right ends of the paper P with the guide 114, the paper P is bent into a U shape and discharged to the paper receiving portion. Thus, the paper stacking in the curled state as shown in FIGS. 13 and 14 can be prevented, and the paper P is stacked in an orderly manner.
JP 2001-58751 A

  However, in the paper discharge device of FIG. 12, during conveyance of the paper, the back surface (lower surface) of the central portion of the left and right width of the paper P moves while adsorbed to the conveyance belt 110, so that it does not get dirty. Since the back surface (bottom surface) of the paper moves while rubbing against the surface of the push-up guide 114, depending on the paper quality, the frictional resistance at the contact surface increases, and the smooth conveyance of the paper is impeded and the rubbing of the push-up guide due to the rubbing. In particular, in a double-sided printing machine that prints on both sides of the paper, the ink is not completely dried because the paper is transported on the discharge path in a state of being printed on the back side of the paper. A problem arises in that the left and right ends of the back surface rub against the push-up guide 11 and the image becomes dirty.

(Object of invention)
The object of the present invention is to prevent the curling phenomenon of the paper after printing, and to discharge the paper after printing to the paper receiving tray smoothly and without soiling the back surface even in double-sided printing work, and orderly A paper discharge device that can be loaded is provided.

In order to solve the above-described problems and achieve the object, the present invention provides a paper discharge mechanism having a paper transport mechanism that receives a paper image formed by an image forming unit, transports the paper on a discharge path, and discharges the paper onto a paper tray. In the apparatus, an air suction mechanism that includes a planar transport plate that forms the discharge path, and sucks a central portion of the left and right widths in the transport width direction of the paper being transported below the transport plate , and the paper being transported An air blowing mechanism that blows air to both left and right ends of the air suction mechanism, and an air suction port of the air suction mechanism is formed at the central portion of the left and right width of the transport plate so as to extend long in the paper transport direction, The air blowing port of the air blowing mechanism is arranged on the downstream side of the sheet conveyance from the end of the air suction port on the upstream side of the sheet conveyance, outside the left and right widths of the air suction port of the conveyance plate.

  According to the above configuration, after printing, the paper in the middle of the discharge path is bent into a U shape and seated, thereby preventing the paper from curling into a reverse U shape and discharging the paper to the paper tray. Paper can be stacked on the paper tray in an orderly manner.

  In addition, since the central portion in the width direction of the paper is sucked downward with air and both ends in the width direction of the paper are pushed up with blowing air, the back surface (lower surface) of the paper is not rubbed against the discharge path surface during conveyance. Further, the paper can be smoothly conveyed, and even when the paper on which both the front and back sides are printed is conveyed like a double-sided printing machine, it is possible to prevent the image from being stained due to rubbing.

Furthermore, the air suction port of the air suction mechanism is formed in the central portion of the left and right width of the transport plate so as to extend long in the paper transport direction, and the air blowout port of the air blow mechanism is configured to be the air suction port of the transport plate. Since the air suction port is disposed on the downstream side of the sheet conveyance upstream from the end of the air suction port on the upstream side of the sheet conveyance, first, in the sheet conveyance process, the air suction mechanism first uses the center of the sheet in the width direction of the sheet. After firmly adsorbing the part and stabilizing the posture of the paper, the paper can be bent and seated by pushing the both ends of the paper in the width direction with blowing air, so that the paper can be seated normally. Can sit in a certain U-shape with a simple posture.

  In the present invention, preferably, the shape of the outlet is formed so as to become wider toward the downstream side in the sheet conveying direction.

  According to the above configuration, the air blowing width can be gradually increased with respect to the paper on the discharge path as it goes to the downstream side of the paper conveyance, so that the paper is always bent in a U-shape stably and reliably. Can be attached.

In the present invention, preferably, the paper transport mechanism includes a rotation roller disposed on a paper transport upstream side and a paper transport downstream side, and a transport belt wound around the rotation roller,
The conveyor belt is constituted by a mesh member that passes through the upper surfaces of the air suction port and the air blowing port and through which air can pass.

  According to the above configuration, since a mesh member capable of air flow is used as the transport belt, a new suction hole is formed in the transport belt even if the transport belt is disposed on the air suction port or the air outlet. The sheet can be adsorbed without any trouble and placed in a U shape. In addition, since the mesh member has a smaller contact area with the paper as compared with a normal conveyance belt, it is possible to suppress the contamination of the paper due to the contact between the central portion in the width direction of the paper and the conveyance belt.

In the present invention, preferably, the paper transport mechanism includes a rotation roller disposed on a paper transport upstream side and a paper transport downstream side, and a transport belt wound around the rotation roller,
The conveyor belt is disposed between the air outlets at both ends in the sheet width direction, and a large number of minute protrusions are formed on the upper surface.

  According to the above configuration, even when a mesh member is not used as the transport belt, the contact area between the transport belt and the paper is reduced, so that paper contamination due to the contact between the central portion in the width direction of the paper and the transport belt is also suppressed. Can do.

  In the present invention, preferably, the air blowing mechanism is configured such that an air blowing direction from the air blowing port is inclined toward the sheet conveying direction with respect to the vertical direction, or in the sheet width direction toward the sheet conveying downstream side. Inclined to spread.

  According to the above configuration, when the air blowing direction is inclined toward the sheet conveyance direction with respect to the vertical direction, the resistance of the blowing air to the sheet being conveyed is reduced, and the component of the blowing air in the conveyance direction is reduced. As a result, the conveyance of the sheet can be assisted and the sheet can be conveyed smoothly. Further, if the air blowing direction is configured to spread in the paper width direction toward the downstream side in the paper conveyance direction, the blowing air gradually moves from the portion near the center in the paper width direction to the end in the width direction. It acts and can perform a stable U-shaped forming operation.

  In the present invention, preferably, the air suction mechanism and the air blowing mechanism are connected to a suction portion and a discharge portion of a common fan-type drive mechanism.

  According to the above configuration, it is possible to perform air suction and blowout only by providing one fan mechanism, and it is possible to reduce the number of parts and save energy.

  In the present invention, the opening area and the opening position of the air blowing port of the air blowing mechanism can be changed.

  According to the above configuration, by adjusting the opening area and opening position of the air outlet according to the size of the paper, the air is blown out in an amount and position optimal for U-shape formation on various sizes of paper. Can do.

  In the present invention, a control device is provided for controlling the air blowing amount by the air blowing mechanism as the ratio of the image data amount on the lower back surface to the image data amount on the upper surface of the paper on the discharge path increases. be able to.

  In the case of a duplex printer, the degree of curling of the paper after image formation and the direction of curling may differ depending on the ratio of the amount of image data on the front and back sides of the paper. Specifically, as the amount of image data, for example, when comparing the printing rates, if the printing rate on the front side of the paper is larger than the printing rate on the back side of the paper, the swelling due to ink is greater on the front side. Thus, both ends of the sheet curl to the back side, and the entire sheet bends in an inverted U shape on the discharge path. The degree of inverted U-shaped curl increases as the difference between the front and back surface print ratios (front surface print ratio−back surface print ratio) increases. On the other hand, when the printing rate on the front side of the paper is smaller than the printing rate on the back side of the paper, the swelling due to the ink is larger on the back side, so both ends of the paper curl to the front side, As a whole, it bends in a U shape on the discharge path. The degree of U-shaped curl increases as the difference between the front and back surface print ratios (back surface print ratio−front surface print ratio) increases.

  As described above, even if the degree or direction of curl changes due to the change in the printing rate on the front and back sides of the paper, the air blowing rate increases as the printing rate on the front side becomes larger than the printing rate on the back side and the difference increases. If the air blowout amount from the mouth is increased and the print rate on the front side is decreased, the air blowout amount from the air blowout port is decreased, so that the paper The curl can be corrected and released onto the paper cradle.

  In the present invention, the amount of image data at both ends in the width direction of the upper surface of the paper on the discharge path is compared, and the amount of air blown from the air blowout port is individually controlled according to the amount of image data at each end. A control device can be provided.

  For example, when the printing rate (image data amount) at both ends in the width direction of the paper surface is different, the curl phenomenon causes the end of the side with the higher printing rate to curl greatly, depending on the degree of curl at each end. Since the amount of blown air is adjusted, both end portions in the paper width direction can be pushed up almost evenly and seated in a U shape symmetrically, and can be discharged in a stable flight posture on the paper cradle. it can. As a result, the alignment of the stacked sheets on the paper tray is improved.

  In short, according to the present invention, the curling phenomenon of the paper after printing is prevented, and even in double-sided printing work, the paper after printing is smoothly discharged to the paper cradle without getting the back surface dirty, and orderly. Can be loaded.

[Overall configuration of stencil duplex printing device]
1 to 8 show an example in which the paper discharge device according to the first embodiment of the present invention is provided in a stencil double-sided printing device (image forming device). Based on these drawings, the first embodiment of the present invention is shown. An embodiment will be described. FIG. 1 is a side view showing the stencil double-sided printing apparatus in a see-through state. An image reading device 2 is provided at the upper end of the apparatus main body 1, and a paper feeding apparatus 3 is arranged on the start end side in the paper conveyance direction F of the apparatus main body 1. The paper receiving device 4 is arranged on the paper discharge side. In the apparatus main body 1, the first and second printing units 11 and 12 are arranged in the above-described order with an interval in the paper transport direction F, and between the first printing unit 11 and the paper feeding device 3. A timing roller 5 is arranged, a paper discharge device 6 is arranged between the second printing unit 12 and the paper receiving device 4, and a movable feeding / discharging plate unit 8 is arranged above the printing units 11 and 12. Has been. Between the printing units 11 and 12, a straight (planar) straight path 23, a first reversing path 21 and a second reversing path 22 can be switched by a belt conveyance type switching mechanism 31. Is provided. For convenience of explanation, the sheet feeding device 3 side of the apparatus main body 1 is referred to as “rear side” and the paper receiving apparatus 4 side is referred to as “front side” of the apparatus main body 1 and will be described below.

[Configuration of Printing Units 11 and 12]
Each printing unit 11, 12 includes a plate cylinder 11 a, 12 a on which a pre-made stencil sheet N is mounted, and pressing rollers 11 b, 12 b that face the lower ends of the plate cylinders 11 a, 12 a so as to come into contact with each other from below. The sheet P is sandwiched between printing sections (image forming sections) A1 and A2 formed by contact portions between the plate cylinders 11a and 12a and the pressing rollers 11b and 12b, and stencil sheets of the plate cylinders 11a and 12a are formed. N images are printed (transferred) on the upper surface of the paper P.

[Configuration of Image Reading Device 2, Paper Feeding Device 3, Feeding and Discharging Unit 8]
In FIG. 1, an image reading device 2 reads an image of a document placed on a glass document table (not shown), generates image data, inputs it to a control device 32, and stores it. . The image data may be received from an external computer. The image reading device 2 is electrically connected to a control device 32, and an operation panel (not shown) is also electrically connected to the control device 32, and is manually connected to the control device 32 via the control device 32. The various printing specifications of the printing device can be set.

  The sheet feeding device 3 includes a sheet feeding table 15 on which a large number of sheets P are stacked, a sheet feeding roller 16, and the like. Each is sent to the timing roller 5. The timing roller 5 rotates at an appropriate timing in synchronism with the driving of the first printing unit 11 and feeds the paper P to the image forming unit A1 of the first printing unit 11.

  The supply / discharge plate unit 8 includes a plate making unit 8a and a discharge plate unit 8b, and is configured to be movable between an upper position of the first printing unit 11 and an upper position of the second printing unit 12, so that one supply unit is provided. The stencil sheet N can be supplied / discharged to any of the plate cylinders 11a, 12a by the evacuation unit 8. The plate making unit 8a includes a master roll (stencil sheet roll) 17, a thermal head 18, a cutter 19 and the like. Based on image data generated by the image reading device 2, the thermal head 18 removes the master roll 17 from the master roll 17. A stencil sheet N is made, cut into a predetermined length by a cutter 19, and mounted on the outer peripheral surfaces of the plate cylinders 11a and 12a. The plate discharging unit 8b is composed of a plate discharging roll 20a, a drawing roller 20b, and the like. The used stencil sheet N mounted on the plate cylinders 11a, 12a is removed, drawn inside by the drawing roller 20b, and wound up as a plate discharging roll 20a. It has become.

[Configuration of Direct Path 23 and Inversion Paths 21 and 22]
The switching mechanism 31 has a horizontal posture that forms a part of the direct passage 23 as shown by a solid line, an inclined posture that forms a part of the first reversing path 21 as shown by a virtual line, The two reversing paths 22 can be switched in three stages with an inclined posture that forms a part.

  The direct path 23 is a path that connects the printing unit A1 of the first printing unit 11 and the printing unit A2 of the second printing unit 12 in a substantially flat shape (straight line), and the horizontal posture switching mechanism 31 The upper suction surface of the air suction type transport belt mechanism 33 is configured.

  The first reversing path 21 is configured by an air suction type conveying belt mechanism arranged in an I shape, and the sheet P on which one side is printed by the printing unit A1 of the first printing unit 11 passes the switching mechanism 31. After passing through and into the first reversing path 21, the paper moving direction is reversed, and the printing unit A <b> 2 of the second printing unit 12 passes through the reversing path outlet 34 from the lower transport surface of the transport belt mechanism 33. To be supplied.

  The second reversing path 22 is composed of a plurality of air suction type conveying belt mechanisms arranged in a U shape so as to surround the first reversing path 21, and the second reversing path 22 has two A conveyor belt mechanism is disposed heavily, and has a path length approximately twice that of the first reversing path 21 as a whole. The sheet P on which one side is printed by the printing unit A1 of the first printing unit 11 is carried into the second reversing path 22 through the switching mechanism 31 and conveyed at the foremost end through the lower conveying belt mechanism. The belt movement mechanism is reached, where the paper movement direction is reversed and supplied to the printing section A2 of the second printing unit 12 through the second conveying belt mechanism and the reverse path outlet 34 from the front.

  During double-sided printing, printed paper P is alternately supplied from the printing unit A1 of the first printing unit 11 to the first reversing path 21 and the second reversing path 22, and the sheets are reversed at different timings. P is alternately supplied to the printing unit A2 of the second printing unit 12.

[Configuration of the paper tray 4]
The paper receiving tray 4 includes a loading table 35, a contact plate 36 erected at the front end of the loading table 35, and side guides 37 disposed at the left and right ends of the loading table 35.

[Configuration of the paper discharge device 6]
The paper discharge device 6 includes a planar conveyance plate 40 that forms a discharge path, a drive roller 41 that is disposed near the rear end of the paper receiving tray 4, and the vicinity of the front side of the printing unit A 2 of the second printing unit 12. A driven roller 42 disposed in the section, an auxiliary roller 43 and a tension roller 44 disposed at a certain distance below the drive roller 41 and the driven roller 42, and the rollers 41, 42, 43, and 44, respectively. A conveyor belt (mesh belt) 45 made of a mesh member, and an air suction mechanism 51 and an air blowing mechanism 52 disposed on the lower surface of the conveyor plate 40 are provided.

  2 is an enlarged vertical side view of the paper discharge device 6, FIG. 3 is a plan view of the paper discharge device 6, FIG. 4 is a front view of the paper discharge device 6, and FIG. 5 shows an initial state of paper conveyance on the discharge path. FIG. 6 is a front view of the paper discharge device 6 showing a state in the middle of paper conveyance on the discharge path, FIG. 7 is an enlarged plan view of the conveyance belt 45 made of a mesh member, and FIG. FIG. 7 is a sectional view taken along line VIII-VIII. In FIG. 2, the conveying plate 40 is arranged in a state inclined slightly forward and downward, and correspondingly, the driving roller 41 is arranged at a position slightly lower than the driven roller 42, and the driving roller 41 and the driven roller 42. The intermediate conveying belt 45 is moved along the upper surface (conveying path surface) of the conveying plate 40 in a state of being slightly lowered forward. Although not shown, the tension roller 44 is urged rearward and downward by an urging means such as a spring, thereby applying tension to the conveyor belt 45.

  The air suction mechanism 51 includes a suction box 55 coupled to the lower surface of the transport plate 40 and a suction fan 56 coupled to the lower side of the suction box 55. A plurality of air suction ports 57 are formed in the region. The air blowing mechanism 52 includes a blower fan 60 and an air duct 61 connected to an air outlet 60a on the front side of the blower fan 60. As shown in FIG. The front side of the fan 56 extends upward and branches left and right, and is connected to an air outlet 63 formed in a pair of left and right at the front end of the transport plate 40.

  The drive part (electric motor or the like) of the suction fan 56 of the air suction mechanism 51 and the drive part (electric motor or the like) of the air blowing mechanism 60 of the air blowing mechanism 52 are both electrically connected to the control device 32. The air suction strength and the air blowing strength are adjusted by adjusting the rotational speed of each drive unit according to a command from the control device 32.

  In FIG. 3, the plurality of air suction ports 57 are symmetrically arranged in a predetermined left and right width W1 centered on the width center line C1 at the center portion of the left and right width of the transport plate 40. It is long in the front-rear direction (paper conveyance direction F) from the rear end portion to the front end portion. In this embodiment, a total of 10 air suction ports 57 are formed, and four trapezoidal air suction ports 57 are arranged on the most rear end (upstream conveyance end) side in the front-rear direction. Four air suction ports 57 having a parallelogram shape are disposed in the intermediate portion, and two air suction ports 57 having a large trapezoidal area are disposed in the front end portion (downstream transport end portion). Opposing end edges of the air suction ports 57 adjacent to each other in front and rear are inclined so as to come forward as the distance from the width center line C1 increases.

  As described above, the pair of left and right air outlets 63 are the front end portion (downstream end portion of the transport) of the transport plate 40, and the width center line C1 is centered outside the left and right width W1 of the air suction port 57. It is arranged in the symmetrical position. The air outlet 63 is formed in a rectangular shape that is long in the left-right direction, and its opening area can be changed by a sliding shutter 65 that slides in the left-right direction. The sliding shutter 65 can be manually operated, but can be automatically controlled by being connected to a drive mechanism such as a link mechanism or a rack and pinion mechanism, and the drive mechanism being connected to the control device 32.

  The air blowing direction from the air blowing port 63 is a center line C1 at a predetermined angle β1 toward the front with respect to a line parallel to the width center line C1, as shown by a white arrow in plan view (FIG. 3). It is inclined in the direction away from each. Further, the air blowing direction from the air blowing port 63 is inclined so as to fall forward at a predetermined angle α1 with respect to the vertical line as shown by a white arrow in a side view (see FIGS. 1 and 2). ing.

  The drive roller 41 is linked to a drive motor 68 via a timing belt mechanism 67 and has an outer peripheral surface formed in a right cylindrical shape to prevent the conveyance belt 45 from slipping. In order to correct the lateral displacement of the conveyor belt 45, the outer peripheral surface of the belt is formed in a barrel or drum shape where the width center line O1 portion has the maximum diameter, and the diameter gradually decreases toward the left and right. . Also, the auxiliary roller 43 and the tension roller 44 in FIG. 2 are formed in a barrel shape or a drum shape like the driven roller 42. Although not shown, a side guide plate that restricts left and right movement of the paper P can be disposed on the discharge path.

  In FIG. 7, a plain weave cloth is used for the conveyor belt 45 made of the mesh member of the embodiment, and the mesh pitch D1 is set between 100 μm and 170 μm. As the vertical and horizontal fibers 45a and 45b used in the conveyor belt 45 made of the mesh member, both metal fibers and synthetic fibers can be used. However, when considering durability, metal fibers are used, and the pressing force is used. In order to improve the uniformity of the fiber, it is preferable to use a synthetic fiber. Further, in order to bring the mesh belt made of mesh members into point contact as much as possible, the fibers 45a and 45b are preferably single wires rather than twisted wires.

  Furthermore, the surface of the fibers 45a and 45b of the conveyor belt 45 made of a mesh member is preferably a water-repellent or oil-repellent coating made of a silicone compound or a fluorine compound such as dimethyl silicone, polytetrafluoroethylene or fluoroalkylsilane. As a result, it is possible to suppress the adhesion of ink to the conveyor belt 45 made of a mesh member.

  In FIG. 8, the minimum height difference h in the cross section of the conveyor belt 45 made of mesh member, that is, the difference h between the upper end of the upper fiber 45a and the upper end of the lower fiber 45b in the fiber crossing portion is preferably 20 μm or more and 100 μm. Set as follows. As a result, even if ink adheres to the conveyor belt 45 made of a mesh member, the ink is stored at a position near the intersection of the vertical fibers 45a and the horizontal fibers 45b to the extent that the ink is not retransferred from the conveyor belt 45 to the paper. Can do.

[Operation of the entire printing device]
The overall operation when both sides of the paper P are printed using the first and second inversion paths 21 and 22 will be described.

(1) In FIG. 1, the sheets P stacked on the sheet feeding table 15 of the sheet feeding device 3 are supplied to the timing roller 5 one by one from the top by the sheet feeding roller 16. The paper P is fed into the image forming unit A1 of the first printing unit 11 in accordance with the rotation angle (print start position) of the first plate cylinder 11a.

(2) In the first printing unit 11, the paper P is sandwiched from above and below by the printing unit A 1, one side of the paper P on the plate cylinder 11 a side is printed, and sent to the switching mechanism 31.

(3) The switching mechanism 31 alternately distributes the paper P sent from the printing unit A1 of the first printing unit 11 into the first reversing path 21 and the second reversing path 22. The sheets P reversed in the reversing paths 21 and 22 are alternately supplied from the reversing path outlet 34 to the printing unit A2 of the second printing unit 12 while adjusting the discharge timing of each sheet, and the remaining surfaces are transferred. After printing, it is sent out to the discharge path of the paper discharge device 6.

(4) In the paper discharge device 6, as will be described in detail later, the paper P is transported forward on the transport plate (discharge path) 40 while being attracted to the transport belt 45 made of a mesh member, The air blowing mechanism 52 is seated in a U shape and discharged to the paper receiving tray 4.

(5) In the paper receiving tray 4, the sheet P is brought into contact with the abutting plate 36 to align the position in the front-rear direction, and the left and right side guide plates 37 are aligned to the left and right to be stacked on the stacking table 35.

  In addition, when multi-color (two colors) printing is performed on the same side of the paper, the paper P on which one side is printed by the first printing unit 11 while keeping the switching mechanism 31 in a horizontal posture in FIG. Are supplied to the second printing unit 12 without being inverted, and the same surface is printed in another color even in the printing unit A2 of the second printing unit 12.

[Specific Actions and Effects in Paper Discharge Device 6]
The operation of the paper discharge device 6 in the duplex printing operation will be described in detail. As shown in FIG. 2, the surface Pa facing upward on the transport plate 40 is expressed as “sheet front surface”, and the surface Pb facing down is expressed as “sheet back surface”. To do. Incidentally, the paper surface Pa is a surface printed by the second printing unit 12 of FIG. 1, and the paper back surface Pb is a surface printed by the first printing unit 11 of FIG.

  FIG. 5 shows an initial state of conveyance on the discharge path. The front end portion of the paper P is adsorbed to the upper surface of the mesh-made conveyance belt 45 by the air suction action of the air suction port 57, and is conveyed by the conveyance belt 45. It is conveyed forward. As a result, the paper P is transported in a state where no skew or positional deviation occurs.

  FIG. 6 shows a state in the middle of conveyance on the discharge path. When the front end portion of the sheet P approaches the left and right air outlets 63, the central portion of the left and right width of the sheet P is still the air. Although it is adsorbed to the conveyor belt 45 by the suction action of the suction port 57, the left and right ends of the paper P are pushed upward by the air blown out from the air blowing port 63 (white arrows). As a whole, the paper P is bent into a U-shape with an open top and is seated. At the time of the pushing-up action, the left and right end portions of the paper back surface Pb are not rubbed. The floating height of the left and right ends of the paper P is approximately 3 cm.

  Thereafter, the paper P is discharged to the paper receiving tray 4 in FIG. 1 in a state where the paper P is continuously seated in a U shape up to the rear end of the paper. As a result, the paper P is neatly stacked on the stacking table 35 without curling as shown in FIG.

  Although the operation is as described above, in the present embodiment, as shown in FIG. 3, the position of the air outlet 63 is positioned forward of the rear end portion of the air suction port 57, and Specifically, since it is arranged at the front end portion of the transport plate 40, first, in the paper transport process on the discharge path, the air suction mechanism 51 securely sucks the central portion in the width direction of the paper P and transports the paper P. After stabilizing the posture, both ends in the width direction of the paper P are pushed up with air by the air blowing mechanism 52, so that the paper can be bent and seated in a U-shape. It can be seated in a certain U-shape.

  Further, in the present embodiment, as shown in FIG. 2, the air blowing direction from the air blowing port 63 is frontward at a predetermined angle α1 with respect to the vertical line as shown by a white arrow in a side view. Since it is inclined so as to fall down, the resistance of the blown air to the sheet P being conveyed is reduced, and the component of the blown air forward (conveying direction) helps the conveyance of the sheet P and makes the sheet conveyance smooth. be able to. Further, as shown in FIG. 3, since the air blowing direction is inclined so as to spread in the left-right direction toward the front (downstream side in the paper transport direction) in a plan view, Gradually acting from the portion near the width center to the left and right ends, a stable U-shaped forming operation can be performed.

  In the present embodiment, as shown in FIG. 7, a mesh member capable of air circulation is used as the transport belt 45, so that the transport belt 45 is placed on the air suction port 57 and the air blowing port 63. Even if it is arranged, the sheet can be adsorbed and seated in a U shape without forming a new suction hole in the conveyor belt 45. In addition, since the mesh member has a smaller contact area with the paper as compared with a normal conveyance belt, it is possible to suppress the contamination of the paper due to the contact between the central portion in the width direction of the paper P and the conveyance belt 45.

[Various adjustments and controls]
(1) In FIG. 3, the area of the air outlet 63 is changed by moving the sliding shutter 65 in accordance with the size of the paper P, particularly the left-right width. For example, when the left-right width of the paper P is increased, the sliding shutters 65 are moved outward in the width direction to increase the opening area of the air outlet 63. At the same time, the fan rotation speed of the blower fan 60 of the air blowing mechanism 52 is increased through the operation panel and the control device 32 shown in FIG. 5 to increase the amount and strength of the air blowing from the air blowing port 63.

(2) The image reading device 2 in FIG. 1 reads an image of a document, and controls the rotational speed of the drive unit of the air blowing mechanism 52 based on the difference in the printing rate (image data amount) between the front and back surfaces input to the control device 32. Then, the air blowing amount from the air blowing port 63 is changed. When performing double-sided printing, the degree of curling of the paper P after printing and the direction of curling may differ depending on the change in the difference in image data amount (printing rate) between the paper front surface Pa and the paper back surface Pb. More specifically, when the printing rate of the paper surface Pa is larger than the printing rate of the paper back surface Pb, the swelling due to the ink is larger on the paper surface Pa, and the left and right ends of the paper P are on the paper back surface Pb side. And bends in an inverted U shape on the discharge path as a whole sheet. As the difference between the front and back surface print ratios (the front surface print ratio minus the back surface print ratio) increases, the degree of inverted U-shaped curl increases. On the other hand, when the printing rate of the paper surface Pa is smaller than the printing rate of the paper back surface Pb, the swelling due to the ink is larger on the paper back surface Pa side, so the left and right ends of the paper P curl to the front surface Pa side. Thereby, the entire sheet bends in a U-shape on the discharge path. The degree of U-shaped curl increases as the difference between the front and back surface print ratios (back surface print ratio−front surface print ratio) increases. In the case of double-sided printing, the paper back surface pb is printed first on the discharge path, the paper surface Pa is printed after a certain period of time, and the paper back surface Pb is supplied to the discharge path with some dryness. Curls in an inverted U shape.

  In this way, when the printing rate on the front and back sides of the paper changes, the printing rate on the front side Pa of the paper is greater than the printing rate on the back side Pb of the paper, and if the difference becomes larger, the air flow is correspondingly adjusted. By increasing the rotational speed of the blower fan 60 of the blowing mechanism 52, the amount of air blown from the air blowing port 63 is increased. On the contrary, when the printing rate on the paper surface Pa side decreases, the air blowing port 63. Reduce the amount of air blown from

(3) As described above, similarly to the adjustment of the air blowing amount based on the change in the printing rate difference between the front and back surfaces of the paper, the left and right ends of the paper surface Pa read by the image reading device 2 and input to the control device 32 Based on the difference in the printing rate (image data amount), the left and right end portions of the paper P are pushed up substantially evenly by individually controlling the opening areas of the left and right air outlets 63. That is, when the printing rate (image data amount) at the left and right ends of the paper surface Pa is different, the curl phenomenon causes the end on the side with the higher printing rate to curl greatly, depending on the degree of curl at each end. Since the air blowing amount is adjusted by adjusting the opening area of the air blowing port 63, the left and right ends of the paper P can be pushed up substantially evenly, and can be seated in a substantially U shape.

[Second Embodiment]
FIG. 9 shows a second embodiment of the present invention, in which the shape (planar shape) of the left and right air outlets 63 is formed in a right triangle shape that is long in the front-rear direction (paper conveyance direction F). The oblique side 63a of the air outlet 63 is inclined in a direction away from the width stop line C1 as it goes forward (conveying direction F) from the middle part in the front-rear direction of the discharge path. That is, the left and right widths of the air outlet 63 gradually increase toward the front (conveying direction F). Other configurations are the same as those in the first embodiment, and the same components are denoted by the same reference numerals (numbers).

  If the air outlet 63 having the shape as shown in FIG. 9 is provided, the air blowing width can be gradually increased toward the front (paper conveyance downstream side) with respect to the paper P on the discharge path. The sheet P can be bent and seated in a U-shape stably and reliably.

[Third Embodiment]
FIG. 10 shows a third embodiment of the present invention, in which the shape (planar shape) of the left and right air outlets 63 is an isosceles triangle that is long in the front-rear direction (paper conveyance direction F). The left-right width of the air outlet 63 gradually increases toward the front (conveying direction F). Other configurations are the same as those in the first embodiment, and the same components are denoted by the same reference numerals (numbers).

  When the air outlet 63 having a shape as shown in FIG. 10 is provided, the air blowing width gradually increases toward the front (paper conveyance downstream side) with respect to the paper P on the discharge path, as in FIG. Therefore, it is possible to always stably and reliably bend the sheet into a U-shape and sit down.

Fourth Embodiment
FIG. 11 shows a fourth embodiment of the present invention, in which a member such as rubber having no air permeability is used as the conveying belt 65 in the conveying mechanism of the paper discharge device 6 instead of a mesh member having air permeability. ing. Three conveying belts 65 are arranged in parallel to each other so as to extend in the front-rear direction at the center of the left and right width of the conveying plate 40, and a large number of circular air suction ports 57 are provided between each conveying belt 65. Arranged in columns. On the surface of the conveyor belt 65, a large number of minute protrusions 65a for preventing slipping of paper are provided. Other configurations are the same as those of the first embodiment, and the same components are denoted by the same reference numerals (numbers).

[Other embodiments]
(1) In the first embodiment, the opening area of the air outlet 63 can be adjusted by the slide type shutter 65. However, a plurality of air outlets 63 are formed on the left and right sides, respectively. By individually providing shutters 63 and opening the air outlet 63 at a desired position, the air outlet 63 can be configured to change its position. Thereby, according to the dimension of the paper P, the air outlet 63 at an appropriate position can be selected and opened.

(2) In the sheet discharge device 6 in which the air suction port 57 and the air blowing port 63 are arranged as shown in FIG. 3, a slit-like air blowing port extending in the front-rear direction on the width center line C1 of the transport plate 40. Can also be added. According to this configuration, the sheet P on the discharge path can be bent in a W shape when viewed from the front, and can be more firmly seated and can also prevent wrinkles.

(3) By arranging wind direction control means that are driven manually or automatically in the left and right air ducts 61 of the air blowing mechanism 52 as shown in FIG. 4 and adjusting the wind direction control means, FIG. 2 and FIG. It is also possible to change the air blowing angles α1 and β1 from the air blowing port 63 as shown to a desired angle according to the size of the paper.

(4) In the paper discharge device 6 including the rubber-made conveyance belt 65 as shown in FIG. 11, a number of air suction holes are formed in the conveyance belt 65, and the conveyance belt 65 is an air suction port 57 of the conveyance plate 40. It can also be arranged to pass over.

(5) In the embodiment shown in FIGS. 1 and 2, the air suction mechanism 51 and the air blowing mechanism 52 are individually provided with a suction fan 56 and a blower fan 60. By using the discharge ports in the air suction mechanism 51 and the air blowing mechanism 52, respectively, it is possible to reduce the number of fans and thereby reduce the cost.

(6) Although not an embodiment of the present invention, the applicant of the present application is a sheet having a pair of left and right push-up guides 114 as shown in FIG. In the discharge device, a configuration in which a large number of minute protrusions are formed on the surface of the push-up guide 114 has been developed.

  The paper discharge device according to the present invention is most suitable for a double-sided stencil printing machine, but can also be applied to other printing machines, copying machines, printers, and the like.

It is a side view which shows the stencil duplex printing apparatus provided with the paper discharge apparatus of the first embodiment of the present invention in a see-through state. FIG. 2 is an enlarged vertical side view of the paper discharge device of FIG. 1. FIG. 2 is a plan view of the paper discharge device in FIG. 1. FIG. 2 is a front view of the paper discharge device of FIG. 1. FIG. 5 is a front view of the paper discharge device showing an initial state of paper conveyance on the discharge path. FIG. 6 is a front view of the paper discharge device showing a state in the middle of paper conveyance on the discharge path. It is an enlarged plan view of the conveyance belt made from a mesh member. It is VIII-VIII sectional drawing of FIG. It is a top view of the paper discharge apparatus of the 2nd Embodiment of this invention. It is a top view of the paper discharge apparatus of the 3rd Embodiment of this invention. It is a perspective view of the paper discharge apparatus of the 4th Embodiment of this invention. It is a perspective view of the conventional paper discharge device. It is sectional drawing which shows the process of the curl phenomenon of the paper after printing. It is sectional drawing which shows the state with which the paper curled on the paper receiving stand was loaded.

Explanation of symbols

6 Paper discharge device 32 Control device 40 Conveyance plate (discharge route)
41 Driving roller 42 Followed roller 45 Conveyor belt made of mesh member 51 Air suction mechanism 52 Air blowing mechanism 56 Suction fan of air suction mechanism 57 Air suction port 60 Blower fan of air blowing mechanism 61 Air duct 63 Air blowing port 65 Made of rubber or the like Conveyor belt

Claims (11)

In a paper discharge device having a paper transport mechanism that receives paper on which an image is formed by an image forming unit, transports the paper on a discharge path, and discharges the paper onto a paper tray.
A planar transport plate (40) that forms the discharge path,
An air suction mechanism (51) that sucks the left and right width central portions of the paper being conveyed in the conveyance width direction below the conveyance plate (40) , and air that blows air to the left and right ends of the paper being conveyed A blowing mechanism (52),
The air suction port (57) of the air suction mechanism (51) is formed in the middle portion of the left and right width of the transport plate (40) so as to extend long in the paper transport direction, and the air blowout mechanism of the air blow mechanism (52). The mouth (63) is located outside the left and right width (W1) of the air suction port (57) of the transport plate (40), and transports paper more than the end of the air suction port (57) on the upstream side of paper transport. A paper discharge device arranged on the downstream side . The paper discharge device according to claim 1, wherein the shape of the air outlet becomes wider toward the downstream side in the paper conveyance direction. The paper transport mechanism includes a rotation roller disposed on a paper transport upstream side and a paper transport downstream side, and a transport belt wound around the rotation roller,
3. The sheet discharge device according to claim 1 , wherein the conveyor belt is configured by a mesh member that passes through the upper surfaces of the air suction port and the air blowing port and through which air can pass. The paper transport mechanism includes a rotation roller disposed on a paper transport upstream side and a paper transport downstream side, and a transport belt wound around the rotation roller,
3. The paper discharge device according to claim 1 , wherein the conveyor belt is disposed between both air outlets at both ends in the paper width direction, and a plurality of minute protrusions are formed on the upper surface. 5. The sheet discharge device according to claim 1 , wherein the air blowing mechanism is configured such that an air blowing direction from the air blowing port is inclined toward a sheet conveying direction with respect to a vertical direction. The paper according to any one of claims 1 to 5, wherein the air blowing mechanism is inclined so that an air blowing direction from both the air blowing ports spreads in the paper width direction toward the downstream side of the paper conveyance. Discharging device. The paper discharge device according to any one of claims 1 to 6, wherein the air suction mechanism and the air blowing mechanism are connected to a suction portion and a discharge portion of a common fan-type drive mechanism. The paper discharge device according to any one of claims 1 to 7, wherein an opening area of the air outlet of the air outlet mechanism is changeable. The paper discharge device according to any one of claims 1 to 8, wherein an opening position of an air outlet of the air outlet mechanism is changeable. According the ratio of the image data amount of the lower back side becomes larger with respect to the image data of the upper surface of the sheet on the discharge route, the claims and a control controlling device so as to reduce the amount of blow-out air by the air blowing device The paper discharge device according to any one of 1 to 9 . A control device for comparing the amount of image data at both ends in the width direction of the upper surface of the sheet on the discharge path, and individually controlling the amount of air blown from the air blowout port according to the amount of image data at each end; The paper discharge device according to any one of claims 1 to 10, further comprising:

Images