JP2006076144A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of eliminating troubles occurring due to changes of the positional relationship between a sheet and the tip of a jet nozzle for discharging ink near the jet nozzle by making the positional relationship constant. <P>SOLUTION: An image and/or an inkjet image are/is formed on the sheet 2, which is transferred on a sheet transfer path 29 arranged oppositely to the jet nozzle, with a first image printing part 3 and a second image printing part 2 for discharging the ink from the jet nozzle 28 in the image forming device. A guide means 100, which regulates the sheet 2 from the tip side 26A of the jet nozzle to a prescribed distance L1, is provided between the tip side 26A of the jet nozzle 28 and the sheet transfer path 29. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of performing both image formation by a stencil printing method and image formation by an ink jet recording method.

  Using a plate cylinder composed of a porous support cylindrical body and a master of laminate training in which a porous support was bonded to a thermoplastic resin film, the thermoplastic resin film surface of the master was heated and melt perforated with a thermal head. Wrapped around the plate cylinder later, an appropriate amount of ink is supplied to the inner surface of the plate cylinder by the ink supply means provided inside the plate cylinder, and the paper is pressed against the outer surface of the plate cylinder by a pressing means such as a press roller or an impression cylinder. Thus, there is known a digital heat-sensitive stencil printing apparatus that performs printing by transferring ink oozed from a plate cylinder opening part and a master punching part to a sheet. Such a stencil printing apparatus is mainly used when a large number of tens or more of the same image is required. This is because the cost per printed material is low and high-speed printing is possible, so that a large number of printed materials can be obtained in a short time.

  However, stencil printing always requires a plate (master) for printing, so if you want to print a small amount of one or several sheets, or if you want to print only a few different images for each of several tens of identical images. Cannot handle when you want to print. In addition, when printing corresponding to a plurality of originals and making them into a booklet, a collation operation is required after the printing operation, and an image like a copying apparatus capable of repeatedly outputting different original images in page order. There is a problem that it cannot respond to formation.

  Therefore, an image forming apparatus using a plateless image forming method such as an electrophotographic method or a discharge method is more suitable for forming a small amount of various images. An image forming apparatus using a stencil printing method is more suitable. As described above, since the image forming apparatus has advantages and disadvantages according to the required image, it is necessary for the user who performs image formation to use them separately. However, if each type of image forming apparatus is held, cost and installation are different. Since each space is doubled, it is usually necessary to use only an image forming apparatus corresponding to image formation that is frequently used. Thus, for example, Patent Documents 1, 2, and 3 describe hybrid type image forming apparatuses that include an image printing unit using a stencil printing method and an image printing unit using an ink ejection method.

  In such a hybrid type image forming apparatus, image formation is performed at two printing units of different formats, so that there is a problem of misalignment of images printed by the first printing unit and later printing unit. In order to prevent such image misregistration, Japanese Patent Application Laid-Open No. 2004-26883 discloses that between the first image printing unit and the second image printing unit in order to ensure the stability of the paper and prevent image misalignment. There is provided a pressing means for preventing the sheet from being lifted by pressing the sheet against the sheet conveying belt located at the position.

JP 2002-137514 A JP 2002-137515 A JP 2002-225410 A JP 2003-334993 A

  Among these image forming apparatuses having a plurality of image printing units having different printing formats, those having an ink ejection type image printing unit have the following problems. That is, in the ink ejection type image printing unit, ink is ejected from the ejection nozzle that is not in contact with the paper and the ink adheres to the paper. . If this cockling phenomenon becomes strong, the paper will wave and partially lift from the conveyor belt (conveying surface). Such lifting causes deviation of the landing position of the ink ejected from the ejection nozzle toward the paper, ejection bending due to dirt due to contact with the tip side of the ejection nozzle, contamination of the paper itself, and the like, resulting in image quality. May decrease.

  In particular, in the hybrid image forming apparatus of the type that performs stencil printing first, ink adheres to the paper soaked with ink by printing in the stencil printing unit, and printing due to printing in the ink jet printing unit. It tends to be easy to do.

  In Japanese Patent Laid-Open No. 2004-260, an attempt is made to eliminate the floating of the sheet by pressing the sheet against the conveying belt by the pressing unit while the sheet is being conveyed from the first image printing unit to the second image printing unit. If the paper is pressed against the conveying belt that does not change, there is a risk of further increasing waviness and lifting due to cockling. Even if the paper is pressed by the pressing means, there is a risk that the paper will rise again when the paper passes through the pressing position, and it is difficult to provide a mechanism like the pressing means in the vicinity of the ejection nozzle. There is a demand for a new method for preventing the sheet from being lifted in the vicinity of the portion.

  It is an object of the present invention to provide an image forming apparatus that fixes a positional relationship between the paper and the tip of the ejection nozzle in the vicinity of the ejection nozzle that ejects ink and eliminates problems caused by the change in the positional relationship. That is the purpose.

  In order to achieve the above object, according to the present invention, a first image printing unit and a second image printing unit that discharges ink from ejection nozzles are used for paper conveyed on a paper conveyance path disposed opposite to the ejection nozzles. In contrast, in an image forming apparatus that forms an image and / or an inkjet image, a guide unit is provided between the front end side of the ejection nozzle and the paper transport path to regulate the paper at a predetermined distance from the front end side of the ejection nozzle. It is a feature.

The present invention is characterized in that the guide means is provided so as to be movable in a direction away from the paper transport path. The present invention is characterized in that the guide means is arranged in the vicinity of both ends of the ejection nozzle located in the paper width direction. This is effective when a plurality of ejection nozzles are arranged in the paper width direction. The present invention is also characterized in that the guide means is arranged immediately upstream of the ejection nozzle in the paper transport direction.

  The present invention is characterized in that the portion of the guide means facing the paper is formed so as to be in line contact with the paper, the surface is uneven, and the surface is water-repellent.

  The present invention is characterized in that the guide means is a plate-like member extending in the paper conveyance direction and a roller member that faces the paper conveyance path and is rotatably supported.

  The present invention is characterized in that the guide means has a roller member that faces the paper conveyance path and is rotatable.

  In the present invention, when the guide means is provided so as to be movable in a direction away from the paper transport path, it is inadvertent to have a biasing means for correcting movement in a direction in contact with the paper transport path. Can be suppressed.

  According to the present invention, since the guide means for regulating the paper at a predetermined distance from the front end side of the injection nozzle is provided between the front end side of the injection nozzle and the paper conveyance path disposed opposite thereto, the predetermined distance from the injection nozzle. The paper is transported under the regulation of the ink, and even if the paper rises from the transport surface due to cockling or warping of the paper, the deviation of the ink landing position, the discharge bend due to the dirt due to contact with the tip side of the ejection nozzle, It is possible to prevent the paper itself from being stained and the like, and to prevent the image quality from being lowered.

  According to the present invention, since the guide means is arranged in the vicinity of both ends of the ejection nozzle positioned in the paper width direction, the ejection nozzle and the paper are displaced in the paper width direction in which displacement increases from the front end side of the ejection nozzle due to warpage of the paper. Since the distance can be regulated to a predetermined distance, it is effective in preventing a decrease in image quality.

  According to the present invention, since the guide means is arranged immediately upstream of the ejection nozzle in the paper transport direction, the paper is transported while being regulated to a predetermined distance from the ejection nozzle immediately before facing the front end of the ejection nozzle. Therefore, it is possible to prevent the deterioration of the image quality more reliably.

  In the present invention, the portion of the guide means that faces the paper is formed so as to be in line contact with the paper or has an uneven surface, thereby reducing the contact area between the guide member and the paper and reducing the resistance. Can prevent the sheet from being bent and the ink from being transferred from the sheet, and can prevent the deterioration of the image quality more reliably.

  According to the present invention, since the portion of the guide means facing the paper has water repellency, the contact resistance between the guide member and the paper is reduced, curling of the paper and transfer of ink from the paper can be suppressed, A decrease in image quality can be prevented more reliably.

  According to the present invention, since the guide means is constituted by a plate-like member extending in the paper conveyance direction, the positional relationship between the ejection nozzle tip side and the paper during conveyance before and after printing can be stabilized, and image quality is deteriorated. Can be prevented more reliably.

  According to the present invention, since the guide member is provided with a rotatable roller member facing the paper conveyance path, or the guide member is provided with the roller member, the contact area between the guide member and the paper is reduced and the resistance is reduced. Can prevent the sheet from being bent and the ink from being transferred from the sheet, and can prevent the deterioration of the image quality more reliably.

  According to the present invention, the guide means is provided so as to be movable away from the paper conveyance path. Therefore, when performing a head maintenance operation such as mounting a drying prevention member at the nozzle tip or in the paper conveyance path. Since the guide means can be moved during a paper jam, maintenance can be improved.

  FIG. 1 shows an image forming apparatus according to an embodiment of the present invention. In the figure, an image forming apparatus includes a paper feeding unit 3 that feeds paper 2 and a stencil printing unit 4 as a first image printing unit that performs stencil printing on paper 2 fed from the paper feeding unit 3. The inkjet printing unit 5 as a second image printing unit that forms an inkjet image on the paper 2, the image processing device 37, and the like. The stencil printing unit 4 and the inkjet printing unit 5 are arranged side by side in the paper conveyance direction indicated by the arrow X.

  The paper feed unit 3 includes a paper feed tray 10 on which a large number of papers 2 are stacked, a paper feed roller 11 that feeds the paper 2 on the paper feed tray 10 from the uppermost one by one, and a paper feed roller 11. A pair of registration rollers 12 and the like are provided, which temporarily stops the fed paper 2 and then feeds the paper 2 toward the stencil printing unit 4 at a predetermined timing.

  A plate making unit 7 is disposed on the upper right side of the stencil printing unit 4. The plate making section 7 cuts a master accommodating section 14 that accommodates a master 13 wound in a roll shape, a thermal head 15 and a platen roller 16 that are disposed downstream of the master accommodating section 14 in the master transport direction, and the master 13. A master cutting means 17, a master conveying roller pair 18 for nipping and conveying the master, and the like. The plate making unit 7 forms a perforated plate making image on the master 13, and then conveys the plate making master 19 toward the stencil printing unit 4.

  The stencil printing unit 4 is detachable from the plate cylinder 20 made of a porous cylinder that winds the master-making master 19 made by the plate-making unit 7 on the outer peripheral surface thereof, and the outer peripheral surface of the plate cylinder 20. And a press roller 22 as a printing pressure member provided. The printing member is not limited to the press roller 22 and may be a form using a known impression cylinder.

  Between the stencil printing unit 4 and the ink jet printing unit 5, the paper 2 that has passed through the stencil printing unit 4 and is peeled off from the outer peripheral surface of the plate cylinder 20 by the peeling claw 23 is sucked to the belt surface by the suction fan 24. A belt conveyance unit 25 is disposed as a conveyance unit that conveys the ink jet printing unit 5 toward the inkjet printing unit 5. In this embodiment, the belt conveyance unit 25 is disposed in the apparatus main body 1.

  An ink supply means 9 having an ink roller 21 and a doctor roller 8 is disposed inside the plate cylinder 20 disposed in the apparatus main body 1. The stencil printing unit 4 supplies the paper 2 fed from the paper feeding unit 3 to the pre-printed master 19 wound on the outer peripheral surface of the plate cylinder 20 by the press roller 22, thereby supplying from the ink supply unit 9. The ink thus transferred is transferred to the paper 2 to form a stencil image on the paper 2. On the upper left side of the plate cylinder 20, a well-known plate discharge device (not shown) for separating and discarding the used plate-making master 19 from the outer peripheral surface of the plate cylinder 20 is disposed.

  As shown in FIG. 2, the ink jet printing unit 5 is movable in a paper width direction Y orthogonal to the paper transport direction X in plan view, and an ink jet recording head as an ink head that ejects ink from an ink ejection port (not shown). 26 and moving means 36 for moving the ink jet recording head 26 in the paper width direction Y.

  The ink jet recording head 26 is a line-shaped head in which a plurality of ejection nozzles 28 serving as ink discharge ports are arranged in parallel in the paper width direction Y, and includes a replaceable ink cartridge 26A containing a single color ink. The ink jet recording head 26 is not limited to one provided with a single color ink cartridge, and may be an ink jet recording head provided with ink cartridges of a plurality of colors such as black, magenta, cyan, and yellow.

  The type of the ink jet recording head 26 may be a supply method in which ink is supplied / replenished from an ink supply unit (not shown) instead of an exchange method in which the cartridge is replaced.

  As shown in FIG. 2, the moving means 36 includes a frame 75 extending in the paper width direction, a guide rail 70 provided on the common frame 75 to which a part of the inkjet recording head 26 is attached, A lead screw 73 rotatably supported by the frame 75 and screwed into the ink jet recording head 26 and a stepping motor 72 as a drive source for rotating the lead screw 73 are provided. When the stepping motor 72 is driven and the lead screw 73 is rotationally driven, the inkjet recording head 26 moves in the paper width direction Y according to the rotational direction and the rotational amount. The position of the inkjet recording head 26 is detected by a home position sensor 74 that detects the initial position of the inkjet recording head 26 and the number of steps of the stepping motor 72.

  Below the ink jet recording head 26, as shown in FIG. 1, the paper 2 conveyed by the belt conveying unit 25 is fed to a paper discharge unit 6 disposed downstream of the ink jet printing unit 5 in the paper conveying direction X. A belt conveyance unit 33 is provided as a conveyance means for conveying toward the vehicle. In the belt conveyance unit 33, a conveyance belt 34 that is applied with a voltage by the voltage application unit 27 and electrostatically attracts the paper 2 is wound around a plurality of rollers 77. Between the ink jet recording head 26 and the belt 34 facing the same, a sheet conveyance path 29 having a belt surface 34A as a conveyance surface is configured. The conveying belt 34 is rotated by any one of a plurality of rollers 77... By a drive motor (not shown), so that the electrostatically attracted paper 2 is discharged to a paper discharge tray 35 provided in the paper discharge unit 6. Transport. In this embodiment, the well-known electrostatic attraction method is used for the belt conveyance unit 33. However, as with the belt conveyance unit 25, an adsorption method for conveying the image-formed paper 2 while sucking the belt surface with a suction fan is used. Also good. The conveyance belt 34 conveys the paper 2 at a predetermined inkjet printing speed by rotating a roller 77 by a drive motor (not shown). The conveyance speed at this time is set to be equal to or higher than the discharge conveyance speed of the stencil printing unit 4.

  An ink cap 31 for receiving ink during a purge operation for ejecting ink regardless of inkjet image formation from the inkjet recording head 26 and covering the tip of the ejection nozzle 28 of the inkjet recording head 26 is received inside the belt conveyance unit 33. Is provided. The ink cap 31 can be brought into contact with and separated from the ink jet recording head 26 by an elevating mechanism (not shown), and is configured to be listed when the ink cap is operated to cover the ejection nozzle from below.

  A paper detection sensor 32 for detecting the leading end of the paper 2 in the paper conveyance direction and setting a start reference for ink jet printing on the paper 2 is disposed upstream of the ink jet recording head 26 in the paper conveyance direction X.

  In this embodiment, as shown in FIG. 1, the inkjet printing unit 5, the belt conveyance unit 33, its drive source, and the paper discharge tray 35 are provided on the inkjet unit 90 side. The inkjet unit 90 is detachably provided to the apparatus main body 1 and can be selectively connected to the apparatus main body 1 as necessary. Thereby, the ink jet unit 90 can be detached from the apparatus main body 1 when printing by the ink jet printing unit 5 is not performed. For this reason, when only the printing with the stencil printing unit 4 is performed, the sheet can be discharged without passing through the ink jet unit 90, so that the transport load can be reduced, high-speed printing is possible, and the apparatus is occupied. Space is reduced. In consideration of the case where the ink jet unit 90 is detached from the apparatus main body 1, the paper discharge tray 35 can be attached to and detached from the ink jet unit 90 and the apparatus main body 1.

  For this reason, when the inkjet unit 90 and the apparatus main body 1 are separated from each other, if the discharge tray 35 is attached to the side surface 1A of the apparatus main body 1 serving as a connection surface with the inkjet unit 90, printing is performed independently on the apparatus main body 1 side. Yes. Further, by making the ink jet unit 90 detachable from the apparatus main body 1, the ink jet unit 90 can be made an option of the apparatus main body 1, and the user can select the apparatus main body 1 separately from the existing one. This can be retrofitted to the stencil printing apparatus, and can meet the needs of existing apparatus users. The ink jet unit 90 and the apparatus main body 100 are provided with connectors 101 and 102 that can be connected to each other and communicated when they are connected. The connector 101 is connected to an image processing device 37 provided inside the apparatus main body 1, and the connector 102 is connected to a recording head positioning drive control device 49 provided on the ink jet unit 90 side.

  An image reading unit 40 is disposed on the upper part of the apparatus main body 1. The image reading unit 40 has a known configuration including a movable scanning unit 41 that reads an image on the document 42, an image sensor 43 such as a CCD to which image data scanned by the scanning unit 41 is input, and the like.

  FIG. 3 shows an operation panel provided in the image forming apparatus. In the figure, the operation panel 50 is disposed on the upper front surface of the apparatus main body of the image forming apparatus 1. The operation panel 50 is provided with a plate making start key 51, a print start key 52, a counter display unit 57, a display device 58 including an LCD, a four-way key 59, a print switching key 60, and the like. Various numerical values are entered in the counter display unit 57, and the display device 58 has a hierarchical structure and displays various information. The four-way key 59 has an up key 59a, a down key 59b, a left key 59c, and a right key 59d, and is used for various settings. The print switching key 60 is a select switch, and image formation by the image forming apparatus can be any of image formation by only the stencil printing unit 4, image formation by only the ink jet printing unit 5, and image formation by the stencil printing unit 4 and the ink jet printing unit 5. Change over selectively.

  FIG. 4 is a control block diagram of the image forming apparatus. In this embodiment, the image forming apparatus includes an image processing device 37 inside the apparatus main body 1, and common image data that is read by the image reading unit 40 and formed by the stencil printing unit 4 is the image processing device 37. After the predetermined image processing is performed in the common image data processing device 38, the image data is sent to the thermal head drive control device 44 via the image forming unit selection means 39 in the image processing device 37, and based on this data. Then, each heating element of the thermal head 15 selectively generates heat, and the master 13 is punched.

  On the other hand, the variable image data sent out from the personal computer 45 or the like and subjected to image formation in the ink jet printing unit 5 is subjected to predetermined image processing in the variable image data processing device 46 and then passed through the image forming unit selection means 39. The ink-jet recording head 26 selectively ejects ink based on this data to form an image. Alternatively, variable image data sent from the variable data storage memory 48 in which necessary image data is recorded in advance is sent to the ink jet head driving device 47 via the image forming unit selecting means 39, and ink jet printing is performed based on this data. The recording head 26 selectively ejects ink to form an image.

  The positioning operation of the inkjet recording head 26 with respect to the conveyed paper 2 is controlled by a recording head positioning drive control device 49 as a control means. The recording head positioning drive control device 49 is a well-known computer having a configuration such as a CPU, ROM, RAM, and timer, and controls the drive of the step pin motor 72 in accordance with parameters that are input as control conditions. A function of adjusting the distance L by displacing the position of the inkjet recording head 26 is provided.

A basic operation of the image forming apparatus will be described.
An operation when forming a stencil print image and an ink jet print image on the paper 2 using the image forming apparatus will be described. The operator switches the print switching key 60 on the operation panel 50 to the “inkjet + stencil” position, sets the document 42 in the image reading unit 40, and presses the plate making start key 51. When the plate making start key 51 is pressed, the scanning unit 41 scans the image of the document 42 and sends this data to the image sensor 43, and a plate discharging device (not shown) is activated to be used from the outer peripheral surface of the plate cylinder 20. The master-making master 19 is peeled off. After completion of the plate removal operation, the plate cylinder 20 rotates to a predetermined plate supply standby position and stops, and a clamper (not shown) provided on the outer peripheral surface is opened to enter a plate supply standby state.

  When the plate cylinder 20 enters a plate feed standby state, the platen roller 16 and the master transport roller pair 18 are operated to send out the master 13. The delivered master 13 is punched and made based on the image data sent to the image sensor 43 when passing through the thermal head 15. The master 13, which has been subjected to plate making and becomes a plate-made master 19, is clamped by a clamper of the plate cylinder 20, and then the plate cylinder 20 is driven to rotate at the same peripheral speed as the conveying speed of the master 13. It is wound on the outer peripheral surface. When the master 13 for one plate is conveyed, the master cutting means 17 is actuated to cut the master 13 and the winding operation is completed.

  After the winding operation is completed, the paper feed roller 11 is operated to feed one sheet 2 from the paper feed tray 10, and the plate cylinder 20 is rotated at a low speed. The fed paper 2 is temporarily stopped by the registration roller pair 12 and then fed between the plate cylinder 20 and the press roller 22 at a predetermined timing. Then, the press roller 22 swings at a predetermined timing, and the sheet 2 is pressed against the master 19 having been made on the outer peripheral surface of the plate cylinder 20. The ink supplied to the inner peripheral surface of the plate cylinder 20 by the ink roller 21 by this pressure contact is transferred to the paper 2 through the opening portion of the plate cylinder 20 and the perforated portion of the master 19 and the so-called printing operation is performed. Done. The sheet 2 to which the stencil printing image, which is the printing image, is transferred by the printing operation is peeled off from the plate-making master 19 on the plate cylinder 20 by the peeling claw 23 and then sent to the belt transport unit 25 and further downstream. It is conveyed.

  The sheet 2 sent by the belt conveying unit 25 is further conveyed by the sheet conveying roller pair 27, and when the leading end is detected by the sheet detection sensor 32, the ink jet recording head 26 is activated, and an ink jet print image is formed on the sheet 2. Is done. The ink-jet print image formed at this time is different from the image data sent from the personal computer 45 or the variable data storage memory 48 as in normal image formation, and is stored in advance in the variable data storage memory 48. It is an image based on the image data for discharge. The idle ejection image data is data for ejecting old ink accumulated in the nozzles of the inkjet recording head 26. When the idle ejection image data is sent out, the inkjet head driving device 47 performs inkjet recording. The ink jet recording head 26 is driven so that ink is ejected from all nozzles provided in the head 26. As the operation of the ink jet recording head 26 at this time, there are total ejection for ejecting ink from all nozzles at once and partial ejection for ejecting ink from all nozzles by performing ejection from some nozzles a plurality of times. is there. At the time of forming the image data for empty ejection, a solid image, a character image, a graphic image, or the like is formed on the sheet 2. The format of this image is stored in advance in the variable data storage memory 48.

  After the printing image is formed in the stencil printing unit 4, the paper 2 on which the image for idle ejection is formed in the ink jet printing unit 5 is further conveyed downstream by the conveying belt 34 via the sheet conveying path 29. The paper is discharged onto the paper discharge tray 35.

  After the plate printing operation in the stencil printing unit 4 and the idle ejection operation in the ink jet printing unit 5 are completed, when the test printing key 53 is pressed by the operator, the paper feed roller 11 is actuated and one sheet is fed from the paper feed tray 10. Sheet 2 is fed, and the plate cylinder 20 is rotationally driven at a rotational peripheral speed corresponding to the set printing speed. The fed paper 2 is timed by the registration roller pair 12 and then sent between the plate cylinder 20 and the press roller 22, and the stencil printing image is transferred by the press roller 22 swinging. . Thereafter, the sheet 2 is conveyed by the belt conveying unit 25 and the sheet conveying roller pair 27, and when the leading end is detected by the sheet detection sensor 32, the inkjet is performed based on the image data sent from the personal computer 45 or the variable data storage memory 48. The recording head 26 operates and an ink jet print image is formed on the upper surface thereof. The sheet 2 on which the stencil printing image and the ink jet printing image are formed is electrostatically attracted to the conveying belt 34 and conveyed, and is discharged onto the paper discharge tray 35.

  After the position or density of each image is confirmed by the above-described test printing operation, when the print start key 52 is pressed after the number of images formed on the display device 57 is set by the operator, the paper feed roller 11 is activated. Then, the paper 2 is continuously fed from the paper feed tray 10 and the plate cylinder 20 is rotationally driven at a rotational peripheral speed corresponding to the set printing speed, and the image forming operation is performed in the same manner as in the trial printing operation. Is done. When the set number of image forming sheets is consumed, the operation of the image forming apparatus 1 is stopped, and the image forming apparatus 1 again enters the image forming standby state.

Next, the configuration in the vicinity of the ink jet recording head 26 which is a characteristic configuration of the present invention will be described.
(First embodiment)
In this embodiment, as shown in FIGS. 5 and 6, the paper 2 and the front end 28 </ b> A side of the ejection nozzle 28 are placed a predetermined distance in the paper transport path 29 located between the paper 2 and the front end 28 </ b> A side of the ejection nozzle 28. A guide plate 100 is provided as guide means for restricting to L. The guide plate 100 is a plate-like member that extends in the paper transport direction X around the tip 28A of the ejection nozzle 28, and is arranged from the upstream side to the downstream side in the paper transport direction X with respect to the ejection nozzle 28. In the guide plate 100, an ink passage hole 101 for allowing the ink ejected from the nozzle to pass through a portion facing the tip 28 </ b> A of the ejection nozzle 28 extends in the paper width direction Y. One end 101A of the guide plate located on the upstream side in the paper transport direction X from the ejection nozzle 28 is bent in an upwardly inclined direction toward the upstream side, and the paper 2 is placed between the guide plate 100 and the belt surface 34A. A guide portion is formed for guiding to. Accordingly, the sheet 2 conveyed from the upstream side in the sheet conveying direction can be surely introduced between the guide plate 100 and the belt surface 34A even if there is some undulation or warpage.

  The ink passage hole 101 may be a hole formed independently to face each nozzle tip. In this embodiment, the ink passage hole 101 is formed as a long hole continuous in the sheet width direction Y. This is because the ink passage holes 101 can be formed more easily than when they are individually formed. In general, when a hole is formed in a plate-like member, press working is performed, but the periphery of the pressed portion is slightly recessed and deformed by the pressing pressure as compared with other portions. In the ink head 26, the finer the ink landing point formed when the ink is attached to the paper 2, the higher the image resolution. Therefore, the pitch between adjacent nozzles is very narrow. For this reason, when the ink passage hole 101 is formed corresponding to each nozzle, the deformation of the hole due to a slight depression due to the press pressure also affects the image resolution. This is because it becomes easier to manage than in the case of forming them.

  The ejection nozzle 28 is in a fixed state when mounted on the inkjet recording head 26. The nozzle tip 28 </ b> A is often located on the inner side of the head from the viewpoint of protecting the tip than the lower surface 26 </ b> A of the inkjet recording head 26. In addition, since the present invention solves the problem when the sheet 2 is lifted, the portion located when the sheet 2 is most lifted is a guide surface. For this reason, in this embodiment, the predetermined distance L is from the guide surface 102, which is a flat surface of the guide member 101 facing the paper 2, to the lower surface (hereinafter referred to as “head lower surface”) 26A of the inkjet recording head 26. And the distance.

According to such a configuration, the maximum rising position of the paper 2 at a predetermined distance L from the head lower surface 26A on the front side of the ejection nozzle between the front end 28A side of the ejection nozzle 28 and the paper conveyance path 29 disposed opposite thereto. Therefore, the paper 2 is ejected from the ejection nozzle 28 even if the paper 2 is lifted from the belt surface 34 </ b> A serving as the transportation surface due to cockling or warping of the paper 2. Ink landing points are stabilized and image quality can be maintained. Further, contact between the tip 28A of the ejection nozzle 28 and the paper 2 and contact between the head lower surface 26A to which the ink adheres due to splashes at the time of ink ejection and the paper 2 can be avoided. Therefore, it is possible to further prevent the deterioration of the image quality.
(Second Embodiment)
The guide plate 100 may have a width in the paper width direction Y and cover the entire head lower surface 26A. However, this increases the contact surface with the paper 2 and causes the transport resistance and the paper 2 to be stenciled. The ink transfer area of the image printed by the printing unit 4 is increased. In this embodiment, as shown in FIGS. 7 and 8, the tip of the paper 2 and the tip 28 </ b> A of the ejection nozzle 28 when passing through the paper transport path 29 of the ink jet printing unit 5 while reducing the contact surface with the paper 2. In order to further stabilize the positional relationship, the guide plates 100A and 100B are arranged in the vicinity of both ends of the ejection nozzle 28 located in the paper width direction Y. The configuration of the guide plates 100A and 100B is the same as that of the guide plate 100 except that the width in the paper width direction Y and the ink passage hole 101 are not provided.

  In this embodiment, the guide plates 100A and 100B are mounted on the side surfaces 26B and 26C of the inkjet recording head 26 located in the paper width direction Y so that the distance between the head lower surface 26A and each guide surface 102 is a predetermined distance L. Yes. The reason why the ink jet recording head 26 is provided with the guide plates 100A and 100B is that the ink jet recording head 26 moves in the paper width direction Y. The guide plates 100A and 100B are arranged at intervals in the paper width direction Y, and the guide surfaces 102 and 102 are flat surfaces.

  According to such a configuration, the maximum rising position of the paper 2 at a predetermined distance L from the head lower surface 26A on the front side of the ejection nozzle between the front end 28A side of the ejection nozzle 28 and the paper conveyance path 29 disposed opposite thereto. Therefore, the sheet 2 is ejected from the ejection nozzle 28 even if the sheet 2 is lifted from the belt surface 34 </ b> A serving as the conveyance surface due to cockling or warping of the sheet 2. In addition, the landing point of the ink is stable and the image quality can be maintained. Further, contact between the tip 28A of the ejection nozzle 28 and the paper 2 and contact between the temporary surface 26A of the ink jet recording head 26 and the paper 2 due to splashes at the time of ink ejection can be avoided. As a result, the paper is not soiled and the image quality is prevented from being deteriorated.

In this embodiment, since the distance between the ejection nozzle 28A and the sheet 2 can be regulated to the predetermined distance L in the sheet width direction Y in which the displacement is increased from the ejection nozzle tip side due to the warp of the sheet 2, the deterioration of the image quality is prevented. be able to. Compared with the first embodiment, the contact area with the paper 2 is reduced, so that the contact resistance at the time of conveyance is reduced, the bending of the paper 2 due to the contact resistance and the transfer of ink from the paper 2 can be suppressed, and the image quality is improved. The decrease can be prevented more reliably.
(Third embodiment)
The guide plates 100, 100A, and 100B are arranged from the upstream side to the downstream side in the paper transport direction X with respect to the ejection nozzle 28. The relationship between the paper 2 and the ejection nozzle 28 is that ink is ejected and adheres to the paper 2. The state of time is important. Therefore, in this embodiment, as shown in FIGS. 9 and 10, the guide plate 100 </ b> C having the guide portion 103 is disposed as a guide member only on the upstream side in the paper transport direction X from the ejection nozzle 28. For this reason, the sheet 2 conveyed to the sheet conveyance path 29 has a guide surface whose maximum rising position of the sheet 2 is a predetermined distance L from the head lower surface 26A on the tip side of the ejection nozzle immediately before facing the tip end 28A of the ejection nozzle 28. 102, the ink is ejected from the ejection nozzle 28 even if the paper 2 is lifted from the belt surface 34A as the transport surface due to cockling or warping of the paper 2. Image quality can be maintained. The sheet is transported while being restricted to the predetermined distance L, and it is possible to more reliably prevent the image quality from being deteriorated.
(Fourth embodiment)
In this embodiment, in order to reduce the contact resistance between the guide member and the paper 2, the portion of the guide member facing the paper is formed so as to be in line contact with the paper. For example, as shown in FIGS. 11 and 12, angle members having a U-shaped cross section as guide members are directed to guide members 110 and 111, and the openings thereof are directed to the belt surface 34A. It arrange | positioned in the vicinity of the both ends of the injection nozzle 28 located in each. The guide members 110 and 111 extend from the upstream side to the downstream side in the paper transport direction X with respect to the ejection nozzle 28 and are mounted on the head lower surface 26A.

  The portions of the guide members 110 and 111 facing the sheet are configured by the opening-side lower surfaces 110A and 111A, and the width thereof is regulated by the plate thickness. When the guide members 110 and 111 are made of metal, a plate thickness of about 0.3 to 0.5 mm has sufficient strength. For this reason, since the contact width with the sheet 2 is a very narrow width of the plate thickness × 4, the contact with the sheet 2 while keeping a predetermined distance L between the sheet 2 and the head lower surface 26A on the tip side of the ejection nozzle constant. Resistance can be effectively reduced by the opening-side lower surfaces 110A and 111A. Resin may be used for the material of the guide members 110 and 111.

  The shape of the opening-side lower surfaces 110A and 111A may be a flat surface because the width is narrow, but the contact pressure in the unit area of the paper 2 is higher than that of the wide paper due to the narrow width and the edge, and the image surface It may be a cause of the generation of streaks. Therefore, the shape of the opening-side lower surfaces 110A and 111A may be formed in an arc shape, or a plurality of hemispherical resin caps may be mounted on the opening lower surfaces 110A and 111A, respectively.

In this way, even if the contact surface with the paper 2 is formed into an arc or a sphere, the contact surface with the paper 2 can be effectively reduced, and a predetermined distance L between the paper 2 and the head lower surface 26A on the tip side of the ejection nozzle is set. The contact resistance with the sheet 2 can be effectively reduced while keeping constant, and the occurrence of streaks due to edges can be prevented. When the cap is mounted, the predetermined distance L is the distance from the head lower surface 26A to the tip of the cap.
(Fifth embodiment)
In this embodiment, rollers 120 and 121 serving as roller members are provided on the guide member 100 as shown in FIGS. The rollers 120 and 121 are rotatably mounted on the side surfaces 26B and 26C of the ink jet recording head 26 so that the rollers 120 and 121 are arranged in the vicinity of both ends of the ejection nozzle 28 positioned in the paper width direction Y, respectively, and the outer peripheral surface thereof is a guide surface 102. More protrude toward the belt surface 34A. That is, it is mounted on the head 26 so as to face the paper transport path 29.

  As described above, the roller members 120 and 121 that are rotatable are provided on the guide plate 100, and the outer peripheral surface that protrudes from the guide surface 102 to the paper conveyance path 29 is used as the contact surface with the paper 2. The surface can be effectively reduced, and the contact resistance with the paper 2 can be effectively reduced while the predetermined distance L between the paper 2 and the head lower surface 26A on the tip side of the ejection nozzle is kept constant. .

The guide member 100 may be attached to the head lower surface 26A and the side surfaces 26B and 26C instead of the roller members 120 and 121 instead of the roller members 120 and 121. In this embodiment, the predetermined distance L is the distance from the head lower surface 26A to the outer peripheral surfaces 120A, 121A of the roller members 120, 121. In this embodiment, the roller members 120, 121 are provided on the guide plate 100. 15 and 16, the roller members 120 and 121 may be used. Of course, the predetermined distance L is a distance from the head lower surface 26A to the outer peripheral surfaces 120A and 121A of the roller members 120 and 121.
(Sixth embodiment)
As shown in FIG. 2, in order to prevent the ink of the ink jet recording head 26 from drying, the ink cap 31 is raised from below the belt 34 by an elevating mechanism (not shown) at the end of printing, for example, on the head lower surface 26A. Although it is mounted, it is difficult to mount because the guide portion is located in front of the head lower surface 26A. This is particularly noticeable when the head lower surface 26 </ b> A is covered except for the ink passage portion 102 as in the guide member 100. Further, when viewed from the paper conveyance path 29 side, it is assumed that each guide member is caught and becomes an obstacle when the jammed paper 2 is removed.

  Therefore, in this embodiment, the guide member can be moved in the direction away from the paper transport path 29. This moving mechanism will be described with reference to FIGS. 17 and 18 by taking the case where the guide plate 100 is used as a guide member as an example.

  The moving mechanism 130 includes an arm 134 that is provided integrally with the guide plate 100, a long hole 131 that extends in the separation direction of the arm 134, and a portion that serves as a support for the guide plate 100, such as the inkjet recording head 26. A guide pin 132 provided so as to be inserted into the hole 131 and a coil spring 133 as a biasing means for biasing the guide plate 100 to a position where the guide plate 100 occupies a predetermined distance L are provided. With this mechanism, the guide plate 100 is urged toward the paper transport path 29 by the coil spring 133 spring force during normal times, and the distance from the head lower surface 26A is set to a predetermined distance L. Further, the biasing force by the coil spring 133 is a spring force that does not displace the position of the guide plate 100 as long as the sheet 2 contacts the guide surface 102 during conveyance.

  According to such a configuration, when the paper 2 that has passed through the stencil printing unit 4 is conveyed, the paper is introduced between the belt surface 34 </ b> A and the guide surface 102 by the guide unit 103. At this time, even if the sheet 2 is conveyed in a state of being lifted from the belt surface 34A, the maximum rising position of the sheet 2 is regulated by the guide surface 102 at a predetermined distance L from the head lower surface 26A on the tip side of the ejection nozzle and conveyed. It will be. For this reason, even if the paper 2 is lifted from the belt surface 34A as a conveyance surface due to cockling or warping of the paper 2, the landing point of the ink ejected from the ejection nozzle 28 is stabilized, and the image quality can be maintained.

  The guide plate 100 is movable in the separating direction, but is biased to the opposite side by the coil spring 133, and the spring force is set so as not to be displaced even when the paper 2 being conveyed contacts the guide surface 102. Therefore, the image quality can be maintained without fluctuation of the predetermined distance L due to contact with the paper 2.

When it is time for the ink cap 31 to rise, as shown in FIG. 18, the guide plate 100 is pushed by the ink cap 31 in the direction away from the paper transport path 29, that is, in FIG. Since it is pushed toward the ink jet recording head 26 located in the upper part of the drawing, it is retracted from the paper transport path 29. For this reason, the mounting operation of the ink cap 31 can be performed satisfactorily.
(Seventh embodiment)
Since each of the above-mentioned guide members faces the sheet conveyance path 29 from above and comes into contact with the sheet that has been lifted, the adhesion of the ink on the sheet cannot be denied. Therefore, in the present embodiment, water repellency is imparted to the portion of the guiding means that faces the paper. As a form for imparting water repellency, the surface of the guide surface 102, the opening lower surfaces 110A and 111A, and the outer peripheral surfaces 120A and 121A, which are portions facing the paper in each form, is subjected to water repellency treatment by silicon or fluorine coating, respectively. Can be mentioned.

  By performing such processing, the contact resistance between each guide member and the paper 2 is reduced, the bending of the paper 2 and the transfer of ink from the paper 2 can be suppressed, and the deterioration of image quality can be prevented more reliably. Can do.

  As a means for reducing the adhesion of ink to the guide surface 102, the opening lower surfaces 110A and 111A, the outer peripheral surfaces 120A and 121A and the contact resistance with the paper 2, as shown in FIG. , 111A, and outer peripheral surfaces 120A and 121A, respectively. As a method for forming irregularities, fine ceramic abrasive grains, glass beads or the like are coated on the surfaces of the guide surface 102, the opening lower surfaces 110A and 111A, and the outer peripheral surfaces 120A and 121A, or a material in which these members are mixed. Each guide member may be formed by the above. Alternatively, fine ceramic abrasive grains, glass beads, and the like are mixed to form a thin film, and the guide surface 102, the opening lower surfaces 110A and 111A, and the outer peripheral surfaces 120A and 121A may be attached to this film. . Even in this case, the contact resistance between the guide member and the paper 2 is reduced, the transfer of ink from the paper 2 can be suppressed, and the deterioration of the image quality can be more reliably prevented.

  In each of the above embodiments, the ink jet printing unit 5 and the belt conveyance unit 33 are provided in the ink jet unit 90 to be detachable from the apparatus main body 1, but may be provided in the apparatus main body 1.

1 is a schematic front view of an image forming apparatus according to an embodiment of the present invention. FIG. 4 is a plan view showing a configuration of an ink head and a moving unit that moves the ink head in a paper width direction and a relationship with the paper. 2 is a schematic diagram of an operation panel provided in the image forming apparatus. FIG. 2 is a block diagram of a control system provided in the image forming apparatus. FIG. It is a side view which shows 1st Embodiment of the guide means used as the principal part of this invention. It is a perspective view which shows the structure of 1st Embodiment. It is a side view which shows 2nd Embodiment of a guide means. It is a perspective view which shows the structure of 2nd Embodiment. It is a side view which shows 3rd Embodiment of a guide means. It is a perspective view which shows the structure of 3rd Embodiment. It is a side view which shows 4th Embodiment of a guide means. It is the figure which looked at the structure of 4th Embodiment from the paper conveyance direction. It is a side view which shows 5th Embodiment of a guide means. It is the figure which looked at the structure of 5th Embodiment from the paper conveyance direction. It is a side view which shows another embodiment of a guide means. It is the figure which looked at the structure of embodiment shown in FIG. 15 from the paper conveyance direction. It is a side view which shows 6th Embodiment of a guide means. It is a side view which shows the displacement state of a guide means.

Explanation of symbols

2 Paper 4 First image printing unit 5 Second image printing unit 26A Front end side of ejection nozzle 28 Injection nozzle 29 Paper transport path 100, 100A, 100B, 100C Guide means 104 Guide surface (part facing paper)
110 Guide means (roller member)
110A, 110B Opening bottom surface (part facing the paper)
120, 121 Guide means 120A, 121A Outer peripheral surface (part facing the paper)
L Predetermined distance
X Paper width direction

Claims (10)

The first image printing unit and the second image printing unit that ejects ink from the ejection nozzles form an image and / or an inkjet image on a sheet that is conveyed on a sheet conveyance path disposed to face the ejection nozzle. In the image forming apparatus to
An image forming apparatus, characterized in that a guide unit is provided between the front end side of the ejection nozzle and the paper transport path to regulate the paper at a predetermined distance from the front end side of the ejection nozzle. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the guide unit is provided so as to be movable in a direction away from the sheet conveyance path. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the guide unit is disposed in the vicinity of both ends of the ejection nozzle located in the paper width direction. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the guide unit is disposed immediately upstream of the ejection nozzle in the sheet conveyance direction. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein a portion of the guiding unit facing the sheet is formed so as to be in line contact with the sheet. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein a portion of the guide unit facing the sheet is an uneven surface. The image forming apparatus according to any one of claims 1 to 6,
The image forming apparatus according to claim 1, wherein a portion of the guide unit facing the paper has water repellency. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein the guide means is a plate-like member extending in a paper conveyance direction. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein the guide unit includes a rotatable roller member facing the paper conveyance path. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein the guide means is a rotatable roller member facing the paper conveyance path.

Images