JP3801603B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly, to a liquid recovery system suitable for an inkjet recording apparatus and other image forming apparatuses having an ejection head that ejects droplets from nozzles toward a recording medium.

  In Patent Document 1, in an ink jet printer having a line head in which a plurality of nozzles are arranged in a direction orthogonal to a paper transport direction, a paper transport region and a maintenance region are provided on an endless belt including a platen member, and a maintenance operation is performed. A configuration is disclosed in which a maintenance area of an endless belt is sometimes opposed to a nozzle surface of a line head and preliminary ejection (operation for forcibly ejecting ink to prevent nozzle clogging) is performed on the maintenance area on the belt. . The endless belt of the same document can temporarily hold the ink ejected to the maintenance area. After preliminary ejection, the endless belt is run to move the maintenance area to the position facing the maintenance unit and adhere to the maintenance area. The discharged ink is sucked by a suction pump and discarded.

Further, Patent Document 2 discloses an ink jet printing apparatus in which a support that supports a recording sheet during a printing process is made of a porous material (a porous film, a porous plate, or a porous band). According to this apparatus, the support is connected to a vacuum source, and excess ink deposited on the support is absorbed by the porous material and sucked and removed through the support.
JP 2002-356026 A JP 2000-168108 A

  However, in both structures disclosed in Patent Document 1 and Patent Document 2, since the ink is absorbed and held by the support member that directly supports the recording medium, the ink is dried in the support member and clogged and absorbed. As the performance deteriorates, the back surface of the recording medium becomes dirty. Further, in the above conventional structure, a large suction means is required to suck and exhaust ink from the support member holding the ink.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an image forming apparatus capable of improving the waste liquid property and preventing the backside contamination of the recording medium.

In order to achieve the above object, an image forming apparatus according to the first aspect of the present invention includes a discharge head on which nozzles for discharging liquid droplets are formed, and a recording head disposed at a position facing the nozzle surface of the discharge head. Medium support means for supporting a medium, liquid collecting means provided in the medium support means, an inclined surface that slides down the liquid that has entered from the ejection head side, and the medium formed at the bottom of the inclined surface A liquid collecting means having an opening communicating with the back surface of the supporting means, a suction means for sucking the liquid through the opening of the liquid collecting means, and a first cleaning means in contact with the nozzle surface of the discharge head; A second cleaning unit that contacts the medium support surface of the medium support unit; and a state in which the first cleaning unit is in contact with the nozzle surface and the second cleaning unit is in contact with the medium support surface. Said first cleaning means and Cleaning drive means for simultaneously moving the second cleaning means relative to the nozzle surface and the medium support surface, and the first cleaning means includes a first blade for wiping the nozzle surface. The second cleaning means includes a second blade for wiping the medium support surface, and the first blade and the second blade have a predetermined direction along a moving direction during cleaning by the cleaning driving means. The nozzle surface is wiped by the first blade that is arranged with an interval and precedes the moving direction at the time of the cleaning, and droplets are ejected from the nozzle in the nozzle region where the first blade has wiped, The area of the medium support surface to which the ejected liquid droplets adhere is wiped by the subsequent second blade .

According to the first aspect of the present invention, the medium support means disposed opposite to the nozzle surface (droplet discharge surface) of the discharge head has the inclined surface for liquid sliding and the liquid collected by the inclined surface as a medium. A liquid collecting means having an opening that allows passage to the back surface of the supporting means (the surface opposite to the medium supporting surface); and the liquid collecting means that opens the liquid collecting means on the medium supporting surface. Therefore, the liquid droplets can be easily recovered from the medium supporting means, and the waste liquid property can be improved.
Moreover, the cleaning process time can be shortened by the aspect provided with the cleaning means which cleans a nozzle surface and a medium support surface simultaneously. In the present invention, after the nozzle surface is wiped with the first blade, the droplets are discharged from the nozzle, thereby preventing the inflow of impurities to the nozzle and realizing stable discharge. In addition, it is easy to collect the droplets attached to the medium support surface by the second blade and the liquid discharged after the first blade.

  According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the liquid collecting means has a hole shape in which the opening on the discharge head side is relatively wide and the opening on the suction means side is relatively narrow. It is characterized by being a through-hole.

  In this aspect, by forming an inclined surface on the wall surface of the through hole extending from the opening on the discharge head side to the opening on the suction means side (back surface side), the liquid droplets can easily slide on the inclined surface. It is possible to efficiently collect the droplets that have entered the opening.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the periphery of the through hole on the discharge head side of the liquid collecting means has a ridge shape that supports the recording medium by line contact. It is characterized by that.

  According to the third aspect of the present invention, no liquid adheres to the back surface of the recording medium, and back surface contamination can be prevented.

  According to a fourth aspect of the present invention, there is provided the image forming apparatus according to the third aspect, wherein the liquid collecting means has a ridge shape that is not orthogonal to the conveyance direction of the recording medium. By supporting the recording medium by a ridge line that is not orthogonal to the conveyance direction of the recording medium, it is possible to stably hold the recording medium, and there is no problem such as the recording medium being caught on the ridge line, thereby improving the conveyance performance. it can.

  A fifth aspect of the present invention relates to the image forming apparatus according to the first aspect, wherein the liquid collecting means has a protrusion for supporting the recording medium by point contact, and a side surface of the protrusion forms the inclined surface. It is characterized by.

  By arranging a plurality of protrusions having a tip shape to support the recording medium on the medium support surface of the medium support means, the recording medium can be stably held and the side surface of the protrusion can be prevented while preventing the recording medium from being stained on the back surface. The liquid can be collected on the inclined surface, and the liquid can be recovered from the opening formed at the bottom of the inclined surface.

  A sixth aspect of the present invention relates to the image forming apparatus according to any one of the first to fifth aspects, wherein the liquid collecting means has liquid repellency.

  According to this aspect, the liquid collection in the form of liquid droplets can be performed by imparting liquid repellency to the surface of the liquid collecting means in contact with the liquid.

  A seventh aspect of the present invention relates to the image forming apparatus according to any one of the first to sixth aspects, wherein at least one of the medium support unit and the ejection head is moved in a droplet ejection direction of the ejection head. And a sealing means including an elastic member that covers the periphery of the nozzle face of the discharge head and seals the nozzle face by contacting the medium support means.

  If necessary, the medium support means is brought close to the ejection head, and the nozzle surface of the ejection head is sealed by the medium support surface of the medium support means and the elastic member of the sealing means, thereby preventing capping for preventing drying during non-ejection. It can be used as a means. Further, the medium support means having such a configuration can be utilized as a head liquid suction means for forcibly removing the liquid from the nozzle.

  The invention according to claim 8 relates to the image forming apparatus according to claim 7, wherein the medium support means functions as a capping means for sealing the nozzle surface of the ejection head when not ejecting, and the nozzle of the ejection head. It functions as a head liquid suction means for performing liquid suction from the head.

  According to this aspect, it is possible to realize the simplification of the mechanism necessary for the head recovery process, and to achieve downsizing and cost reduction.

  Note that as one aspect of the present invention, a full-line type recording head in which a plurality of nozzles are arranged over a length corresponding to the entire width of the recording medium, and at least one of the recording head and the recording medium is connected to the recording medium. There is an aspect in which the present invention is applied to an ink jet recording apparatus including transport means for transporting the recording head and the recording medium relative to each other in a direction substantially perpendicular to the width direction.

  A “full-line type recording head (ejection head)” is usually arranged along a direction orthogonal to the relative feeding direction (relative movement direction) of the recording medium, but with respect to the direction orthogonal to the relative movement direction. Thus, there may be a mode in which the recording head is arranged along an oblique direction having a certain predetermined angle. Further, the arrangement form of the nozzles (image recording elements) in the recording head is not limited to a single line arrangement, and may be a matrix arrangement including a plurality of columns. Furthermore, by combining a plurality of short recording head units having nozzle rows that are less than the length corresponding to the entire width of the recording medium, a nozzle row corresponding to the entire width of the recording medium may be configured as a whole of these units. .

The “recording medium” is a medium (which can be called a print medium, an image forming medium, a recording medium, an image receiving medium, or the like) that receives an image by the action of a recording head, and is a continuous sheet, a cut sheet, a seal sheet, It includes various media regardless of the material and shape, such as a resin sheet such as an OHP sheet, a film, a cloth, a printed board on which a wiring pattern or the like is printed and formed by an inkjet recording apparatus. In this specification, the term “printing” represents the concept of forming an image in a broad sense including characters.

  The moving means (conveying means) for moving the recording medium and the recording head relatively moves the recording medium relative to the stopped (fixed) recording head, and moves the recording head relative to the stopped recording medium. Either the aspect or the aspect in which both the recording head and the recording medium are moved is included.

According to the present invention, the medium supporting means for supporting the recording medium is provided with the liquid collecting means having the inclined surface for liquid sliding and the opening for passing the liquid, and the medium collected by the liquid collecting means Since the ink is sucked from the back side of the liquid collecting means through the opening of the liquid collecting means, it is possible to easily collect the ink by the preliminary discharge and the excess ink when printing the borderless image from the medium supporting surface of the medium supporting means. Can be improved.
Moreover, the cleaning process time can be shortened by providing the cleaning means for simultaneously cleaning the nozzle surface and the medium support surface.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. As shown in the figure, the ink jet recording apparatus 10 includes a print head 12, an ink storage / loading unit 14, a paper feeding unit 18 for supplying a recording paper 16 as a recording medium, and a curling of the recording paper 16. A decurling unit 20 to be removed, a support unit 22 which is disposed opposite to the nozzle surface (ink ejection surface) 13 of the print head 12 and supports the recording paper 16 while maintaining the flatness of the recording paper 16, and recording Conveying units 23 and 24 for conveying the paper 16 and a paper discharging unit 26 for discharging recorded recording paper (printed matter) to the outside are provided. For convenience of explanation, only one (one color) print head 12 is shown. However, when a color image is formed, a plurality of colors (for example, four colors of cyan, magenta, yellow, black, or light cyan) are used. A plurality of print heads corresponding to each color (multiple colors to which light-based ink such as light magenta is added) are installed.

  Also, a single print head having an ejection port for each color may be used. The support portion 22 is preferably provided for each color. With this configuration, ink is sent to the collection tank 40 for each color through an ink collection hole (not shown in FIG. 1, described as reference numeral 60 in FIG. 6) described later, and the ink divided for each color is reused. It becomes possible to do.

  The ink storage / loading unit 14 includes an ink tank that stores ink to be supplied to the print head 12, and the ink tank is communicated with the print head 12 via a conduit 27. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  In the case of an apparatus configuration that uses roll paper, as shown in FIG. 1, a cutter (first cutter) 28 is provided, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. Then, the round blade 28B is arranged on the printing surface side across the conveyance path. Note that the cutter 28 is not necessary when cut paper is used.

  After the decurling process, the cut recording paper 16 is sent to the transport unit 23. The transport unit 23 has a structure in which an endless belt 33 is wound around the rollers 31 and 32. The power of a motor (not shown) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, so that the belt 33 is driven in the clockwise direction in FIG. The recording paper 16 is conveyed from left to right in FIG. The transport unit 24 installed on the downstream side of the support unit 22 has the same configuration as the transport unit 23.

  The support portion 22 includes a platen 36 and a liquid receiving portion 38. That is, a platen 36 having a large number of ink collecting holes (not shown in FIG. 1, and denoted by reference numeral 60 in FIG. 6) serving also as suction holes is disposed on the upper surface of the support portion 22 (the support surface that supports the recording paper 16). A liquid receiving portion 38 is connected to the back side of the platen 36.

  Further, a suction pump (negative pressure generating means) 39 as a means for generating a suction force is communicated with the liquid receiving portion 38, and by sucking the support portion 22 with the suction pump 39 to make a negative pressure, Adsorption of the recording paper 16 and nozzle suction of the print head 12 can be performed. The ink collected in the liquid receiver 38 is sent to the collection tank 40 via the suction pump 39. Each color may be the same collection tank 40, but preferably each color has a separate collection tank. By adopting such a configuration, the recovered ink can be reused. Details of the support portion 22 will be described later.

  A heating fan 41 is provided upstream of the print head 12 on the paper conveyance path. The heating fan 41 heats the recording paper 16 by blowing heated air onto the recording paper 16 before printing. Heating the recording paper 16 immediately before printing makes it easier for the ink to dry after landing.

  A post-drying unit 42 is provided downstream of the print head 12. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the print surface until the ink after printing is dried, a method of blowing hot air is preferred.

  When printing on porous paper with dye-based ink, the weather resistance of the image is improved by preventing contact with ozone or other things that cause dye molecules to break by blocking the paper holes by pressurization. There is an effect to.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined surface uneven shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with a sorting means (not shown) that switches the paper discharge path so as to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. Yes.

  Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B.

  Although not shown in FIG. 1, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

[Print head structure]
FIG. 2 (a) is a plan perspective view showing an example of the structure of the print head 12, and FIG. 2 (b) is an enlarged view of a part thereof. 3 is a perspective plan view showing another example of the structure of the print head 12, and FIG. 4 is a cross-sectional view (cross-sectional view taken along line 4-4 in FIG. 2) showing the three-dimensional configuration of the ink chamber unit. In order to increase the dot pitch printed on the recording paper surface, it is necessary to increase the nozzle pitch in the print head 12. As shown in FIGS. 2 to 4, the print head 12 of this example includes a plurality of ink chamber units (droplet discharge elements) including nozzles 51 that discharge ink droplets, pressure chambers 52 corresponding to the nozzles 51, and the like. ) 53 is arranged in a staggered matrix pattern, thereby achieving an apparent high nozzle pitch density.

  That is, in the print head 12 according to the present embodiment, as shown in FIG. 2, the plurality of nozzles 51 that eject ink correspond to the entire width of the recording paper 16 in a direction substantially orthogonal to the feeding direction of the recording medium (recording paper 16). This is a full line head having one or more nozzle rows arranged over a length of the same.

  Further, instead of the configuration of FIG. 2, as shown in FIG. 3, a short head unit 12 ′ in which a plurality of nozzles 51 are two-dimensionally arranged is arranged in a staggered manner and joined together to connect the entire width of the recording paper 16. You may comprise the full line head which has a nozzle row of the length corresponding to.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and has an outlet to the nozzle 51 and an inlet (supply port) for supplying ink at both diagonal corners. 54 is provided. As shown in FIG. 4, each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54. The common flow channel 55 communicates with an ink tank as an ink supply source, and the ink supplied from the ink tank is distributed and supplied to each pressure chamber 52 via the common flow channel 55. A configuration in which a sub tank (not shown) is provided in the vicinity of the print head 12 or integrally with the print head 12 between the ink tank and the common flow channel 55 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  An actuator 58 having an individual electrode 57 is joined to the pressure plate 56 constituting the top surface of the pressure chamber 52, and the actuator 58 is deformed by applying a driving voltage to the individual electrode 57, and the nozzle 51 Ink is ejected. When ink is ejected, new ink is supplied from the common channel 55 to the pressure chamber 52 through the supply port 54.

  As shown in FIG. 5, a large number of ink chamber units 53 having such a structure are arranged in a row direction along the main scanning direction and an oblique column direction having a constant angle θ that is not orthogonal to the main scanning direction. The structure is arranged in a lattice pattern. With a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along a certain angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ. .

  That is, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, it is possible to realize a high-density nozzle configuration in which 2400 nozzle rows are projected per inch (2400 nozzles / inch) so as to be aligned in the main scanning direction.

  When the nozzles are driven by a full line head having a nozzle row corresponding to the entire width of the paper (recording paper 16), (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and each block is sequentially driven from one side to the other, etc., and one line or one in the sheet width direction (direction perpendicular to the sheet conveyance direction) Nozzle driving for printing individual strips is defined as main scanning.

  In particular, when driving the nozzles 51 arranged in a matrix as shown in FIG. 5, the main scanning as described in (3) above is preferable. That is, nozzles 51-11, 51-12, 51-13, 51-14, 51-15, 51-16 are made into one block (other nozzles 51-21,..., 51-26 are made into one block, Nozzles 51-31,..., 51-36 as one block,...), And the nozzles 51-11, 51-12,. One line is printed in 16 width directions.

  On the other hand, repetitively moving the above-described full line head and the paper to repeatedly perform one line or one band-like printing formed by the above-described main scanning is defined as sub-scanning.

  If the nozzle 51 of the print head 12 is not ejected for a certain period of time, the ink solvent in the vicinity of the nozzle evaporates and the viscosity of the ink in the vicinity of the nozzle becomes high. It becomes impossible to discharge from. Accordingly, “preliminary discharge” in which the actuator 58 is operated toward the ink receiver and ink in the vicinity of the nozzle whose viscosity has increased is discharged before this state is reached (within the range of viscosity that can be discharged by the actuator 58). Is done. Further, after cleaning the nozzle surface by wiping operation (wiping) with a blade or the like provided as a means for cleaning the nozzle surface 13, in order to prevent foreign matter from being mixed into the nozzle by the sliding operation of the blade. Also, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  Further, if the increase in the viscosity of the ink in the nozzle 51 exceeds a certain level, the ink cannot be ejected by the preliminary ejection, and the suction operation described below is performed.

  That is, when the ink viscosity in the nozzle 51 rises above a certain level, ink cannot be ejected from the nozzle 51 even if the actuator 58 is operated. Further, when bubbles are mixed in the nozzle 51 and the ink in the pressure chamber 52, the ink cannot be ejected from the nozzle 51 even if the actuator 58 is operated. In such a case, the suction means is brought into contact with the nozzle surface of the print head 12, the ink in the pressure chamber 52 is sucked with a pump or the like, and the operation of sucking and removing the ink mixed with bubbles or the thickened ink is performed.

  However, since the above suction operation is performed on the entire ink in the pressure chamber 52, the ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible.

  In implementing the present invention, the nozzle arrangement structure is not limited to the illustrated example. In the present embodiment, a method of ejecting ink droplets by deformation of an actuator 58 typified by a piezo element (piezoelectric element) is adopted. However, in the practice of the present invention, the method of ejecting ink is not particularly limited. Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

[Structure of support part]
6 is a perspective view showing the structure of the support portion 22 described in FIG. 1, and FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. As shown in FIG. 6, a large number of ink collecting holes 60 are formed on the entire surface of the platen 36 disposed on the upper surface of the support portion 22. The surface of the platen 36 including the ink collecting hole 60 has liquid repellency that repels ink. “Liquid repellency” as used herein refers to a surface state where the contact angle of the ink droplet is greater than 90 degrees, and more preferably a surface state where the contact angle is 120 degrees or more. In order to give the platen 36 liquid repellency, there are an aspect in which the platen 36 is made of a liquid repellant material, or an aspect in which the surface of the platen 36 is subjected to liquid repellency treatment. The liquid repellent treatment is a surface treatment that has the effect of repelling ink, and a liquid repellent layer (ink repellent layer) 65 is formed in the target region by this treatment. For example, a method of applying a fluorine compound by spray coating or the like is used.

  As shown in FIG. 7, the ink collection hole 60 penetrates in the thickness direction of the platen 36, and the discharge side opening 61 (opposite to the nozzle surface 13 of the print head 12 so that the liquid easily aggregates ( The opening 62 on the back side (collection side) of the platen 36 is narrower than the opening 61 on the discharge side. Since there is an inclined surface (slope) 63 on which ink droplets slide from the edge of the discharge-side opening 61 to the edge of the collection-side (lower) opening, the ink droplets that fall on the inclined surface 63 are repellent. The inclined surface 63 having a liquid property slides down and moves to the lower opening 62. In FIG. 7, the linear inclined surface 63 whose plane is inclined is shown, but the inclined surface 63 may be formed of a curved surface when the present invention is implemented.

  The ink collecting hole 60 also functions as a suction hole for sucking the recording paper 16, and the recording paper 16 is sucked onto the platen 36 by the negative pressure of the suction pump 39 shown in FIG. 6. At this time, the recording paper 16 is contacted and supported by a ridge 64 around the ink collecting hole 60 on the platen 36.

  In this example, the shape defined by the ridgeline around the ink collection hole 60 is a hexagon. However, the present invention is not limited to this example, and any shape (polygon, circle, ellipse, etc.) is used. Is possible. Further, the form in which the plurality of ink collecting holes 60 are arranged in a plane (two-dimensionally arranged) is not limited to the illustrated honeycomb-like arrangement, and is a square matrix arrangement in which the row direction and the column direction are orthogonal to each other, A staggered arrangement in which the column direction is not orthogonal is also possible.

  At this time, as shown in FIG. 6, it is preferable that the ink collecting hole 60 has a shape that does not have a ridge line perpendicular to the paper feeding direction. That is, in the case of the ink collecting hole 60 having the hexagonal shape shown in FIG. 6, the ink collecting hole 60 is arranged so that all sides of the hexagon are not orthogonal to the paper feed direction. Thereby, the supportability and transportability of the recording paper 16 can be improved.

  Also, there is an aspect in which the nozzle arrangement pattern of the print head 12 and the arrangement pattern of the ink collection holes 60 facing the print head 12 are made to coincide with each other so that the positions of the nozzles 51 and the ink collection holes 60 correspond to each other. Further preferred. With this configuration, the ink can be reliably collected in the collection hole.

  The inside of the liquid receiving portion 38 is divided into a plurality of regions (three portions in FIG. 6) along the longitudinal direction of the print head 12, and each of the partition regions 38A, 38B, and 38C functions as a suction chamber. A suction pump 39 is individually connected to each of the partition regions 38A to 38C. By independently controlling each suction pump 39, it is possible to selectively suck desired partition regions 38A to 38C of the liquid receiving portion 38. Of course, it is also possible to suck all the partition regions 38A to 38C at the same time.

  With this configuration, the apparatus can be realized using a relatively small (small capacity) suction pump 39. Further, the drive of the suction pump 39 corresponding to an unnecessary suction area can be stopped according to the size of the recording paper 16 to be used.

  According to the embodiment of the present invention, ink that is not used for image recording (ink mist that has been ejected to the outer region of the recording paper 16 and dropped onto the platen 36) out of ink ejected from the print head 12 is a suction pump. The negative pressure action of 39 enters the liquid receiving portion 38 via the ink collecting hole 60 of the platen 36, and is sent to the recovery tank 40 via the suction pump 39.

  Therefore, for example, the ink mist at the edge during borderless printing (ink ejected to the outside area of the recording paper 16) or the meniscus of the nozzle 51 (interface between ink and outside air) is prevented from drying. It is possible to collect pre-discharged ink mist (purge mist).

  Further, according to the present embodiment, the negative pressure generating means (suction pump 39) used as the ink mist collecting means also serves as a means for generating the negative pressure necessary for the adsorption of the recording paper 16, so that the apparatus This mechanism can be simplified, and downsizing and cost reduction can be realized.

  The support portion 22 in the present embodiment is supported by a lifting mechanism (not shown), and is movable in the ink ejection direction of the print head 12 (normal direction of the nozzle surface 13). That is, the support portion 22 can be moved up and down with respect to the nozzle surface 13 of the print head 12 and can be stopped at each of the “normal position”, “cleaning position”, and “capping position” as necessary. it can. The “normal position” realizes a platen position that maintains the clearance between the nozzle surface 13 and the recording paper 16 at a predetermined distance suitable for printing. The “cleaning position” is a position that is set during a cleaning operation that will be described later, and is set below the normal position. The “capping position” is a position that is set during a capping operation (including a suction operation), which will be described later, and is set above the normal position.

  In addition, the inkjet recording apparatus 10 of this example includes a blade 70 that simultaneously cleans the nozzle surface 13 of the print head 12 and the upper surface of the platen 36 (referred to as a support surface of the recording paper 16, hereinafter referred to as “platen surface 37”). A blade traveling mechanism 80 that moves the blade 70 along the longitudinal direction of the print head 12 (a direction orthogonal to the conveyance direction of the recording paper 16) is provided. In the blade 70, a first blade 71 that rubs the nozzle surface 13 and a second blade 72 that rubs the platen surface 37 are vertically combined in the head longitudinal direction and separated from each other by a predetermined distance. Both the first blade 71 and the second blade 72 have a blade width substantially equal to the width of the print head 12 in the short direction. Note that the blade width is preferably equal to or greater than the nozzle arrangement range in the short direction of the print head 12 and need only be equal to the width of the print head 12 in the short direction.

  The connecting portion 74 that connects the first blade 71 and the second blade 72 has an ink passage hole 75 that penetrates in the ink discharge direction.

The blade traveling mechanism 80 of this example includes a ball screw 81 and a slider 82 screwed to the ball screw 81. The ball screw 81 is disposed such that its axial direction is along the longitudinal direction of the print head 12, and is connected to the rotating shaft of the motor 86 via the coupling 84. The other end of the ball screw 81 is supported by a bearing (not shown).

  The blade 70 is attached to the arm 88, and the base end portion of the arm 88 is fixed to the slider 82. When the ball screw 81 is rotated by the motor 86, the slider 82 moves on the ball screw 81, and accordingly, the blade 70 travels between the print head 12 and the platen 36.

  The blade travel mechanism 80 is not limited to the illustrated ball screw / nut system, and a linear drive mechanism such as a belt drive system or a linear motor system may be employed.

  FIG. 8 is a side view of the main part showing a state during the cleaning operation. This figure is a view when the print head 12 is viewed from the downstream side to the upstream side of the print head 12. In FIG. 8, the direction from the back to the front in the direction perpendicular to the paper surface is the recording paper 16 (not shown in FIG. 8). ), And the horizontal direction on the paper surface represents the longitudinal direction of the print head 12.

  As illustrated, at the time of cleaning, the support portion 22 is moved to the cleaning position, and the blade 70 is inserted between the print head 12 and the support portion 22. The first blade 71 and the second blade 72 travel from the left to the right in FIG. 8 while sliding on the nozzle surface 13 and the platen surface 37, respectively.

  During this blade travel, preliminary ejection is performed to eject ink from the nozzles 51 of the print head 12 corresponding to the position of the blade 70. This preliminary ejection is sequentially executed for the nozzles 51 that fall within the opening range of the ink passage hole 75 of the blade 70.

  That is, with respect to the traveling direction of the blade 70, first, the first blade 71 precedes and wipes the nozzle surface 13, and preliminary ejection is performed from the nozzle 51 immediately after the wiping. The ink 77 ejected by this preliminary ejection operation falls on the platen 36 through the ink passage hole 75. The ink that has fallen on the platen 36 is collected in the liquid receiving portion 38 by the negative pressure of the suction pump 39, and the platen 36 is wiped off by the subsequent second blade 72. Such a series of operations is performed for the entire longitudinal range of the print head 12 as the blade 70 travels. Therefore, the nozzle surface 13 and the platen surface 37 can be cleaned simultaneously by one (one-way) blade travel.

  FIG. 9 is a block diagram of a control system related to the cleaning operation, and FIG. 10 is a flowchart showing the control procedure. As shown in FIG. 9, the ink jet recording apparatus 10 includes a controller (control unit) 90 that controls the entire system, a head driver 92, a blade drive unit 94, a support unit drive unit 96, and a pump drive unit 98. A first sensor 101 that detects the position of the support portion 22 at the cleaning position indicated by middle A, a second sensor 102 that detects the home position of the blade 70, a third sensor 103 that detects the travel limit position of the blade 70, A fourth sensor 104 that detects the position of the support portion 22 at the normal position indicated by B is provided.

  The controller 90 includes a central processing unit (CPU) and its peripheral circuits, and is a control means that generates a control signal for controlling each unit. The controller 90 has a signal processing function for generating a discharge control signal (dot data), and supplies the generated dot data to the head driver 92.

  The head driver 92 drives the actuator 58 of the corresponding nozzle 51 based on the dot data given from the controller 90. That is, the ink ejection amount and ejection timing of each nozzle 51 are controlled via the head driver 92 based on the dot data, thereby realizing a desired dot size and dot arrangement. The head driver 92 may include a feedback control system for keeping the head driving condition constant.

  The blade drive unit 94 includes a motor 86 that drives the blade 70 and its drive circuit, and moves the blade 70 in accordance with a command from the controller 90. The support unit drive unit 96 is configured to include a motor (not shown) that moves the support unit 22 up and down and its drive circuit, and moves the support unit 22 in accordance with instructions from the controller 90. The pump drive unit 98 includes a drive circuit that operates the suction pump 39 that communicates with the liquid receiving unit 38 of the support unit 22, and operates the suction pump 39 in accordance with a command from the controller 90.

  The first sensor 101 is means for detecting whether or not the support portion 22 has reached the cleaning position. The second sensor 102 is means for detecting whether or not the blade 70 has reached a predetermined home position outside the print head 12. The third sensor 103 is means for detecting whether or not the support portion 22 has reached the normal position. The fourth sensor 104 is means for detecting whether or not the blade 70 has reached the travel limit (end) in the longitudinal direction of the print head 12. Detection signals of these sensors (101 to 104) are input to the controller 90 and used for controlling the operation.

  In the above configuration, the following operation is performed during cleaning.

  As shown in FIG. 10, when the cleaning sequence starts (step S210), first, in order to move the support portion 22 in the normal position to the cleaning position, the support portion drive portion 96 is instructed to turn on the downward drive. Then, the support portion 22 is lowered (step S212). Next, the controller 90 monitors the detection signal from the first sensor 101 and determines whether a detection signal is obtained from the first sensor 101 (step S214).

  If the support part 22 has not reached the cleaning position, a NO determination is made in step S214, and the process returns to step S212 to continue the downward drive.

  When the support unit 22 reaches the cleaning position, a YES determination is made in step S214. In this case, the controller 90 instructs the support unit drive unit 96 to turn downward driving OFF and stops the support unit 22 (step S216). Thereafter, the suction pump 39 is operated to make the inside of the support portion 22 have a negative pressure (step S218).

  Next, the blade drive unit 94 is instructed to turn on the positive drive for causing the blade 70 to travel in the cleaning direction (step S220). This blade driving is performed by inputting a pulse to the motor 86.

  Further, in synchronism with the driving of the blade 70, the nozzle 51 is driven corresponding to the pulse of the motor 86, and the preliminary discharge described in FIG. 8 is performed (step S222 in FIG. 10). This nozzle drive is performed based on a data map prepared in advance.

  During the cleaning operation, the controller 90 determines whether a detection signal is obtained from the third sensor 103 (step S224). If the blade 70 has not reached the travel limit, a NO determination is made in step S224, the process returns to step S222, and the cleaning operation is continued.

On the other hand, when the blade 70 reaches the travel limit at the end of the print head 12, a YES determination is made in step S224. In this case, the controller 90 instructs the blade drive unit 94 to turn off the blade normal drive and stops the blade 70 (step S226).

  Thereafter, the blade drive unit 94 is commanded to turn on the blade reverse drive to move the blade 70 toward the original position (home position) (step S228). At the time of this reverse travel (reverse travel), the first blade 71 can be raised and lowered by an actuator (not shown) so that the first blade 71 does not contact the nozzle surface 13 of the print head 12. 71 is run in a state of being separated from the nozzle surface 13. Alternatively, they may be separated by driving the support portion downward.

  The controller 90 determines whether or not a detection signal has been obtained from the second sensor 102 during the return travel drive (step S230). If the blade 70 has not reached the home position, a NO determination is made in step S230, the process returns to step S228, and the return travel of the blade 70 is continued.

  When the blade 70 reaches the home position, a YES determination is made in step S230. In this case, the controller 90 instructs the blade drive unit 94 to turn off the blade reverse drive to stop the blade 70 (step S232) and stop the suction pump 39 (step S234).

  Thereafter, the upper drive ON is commanded to the support drive unit 96 to raise the support unit 22 (step S236). After starting upward driving, the controller 90 determines whether or not a detection signal is obtained from the fourth sensor 104 (step S238).

  If the support part 22 has not reached the normal position, a NO determination is made in step S238, and the process returns to step S236 to continue the upward drive.

  When the support unit 22 reaches the normal position, a YES determination is made in step S238. In this case, the controller 90 instructs the support unit drive unit 96 to turn off the upper drive, stops the support unit 22 (step S240), and ends the cleaning sequence (step S242).

  6 to 10, an example in which the blade 70 travels in the longitudinal direction of the print head 12 has been described. However, in implementing the present invention, a blade having a length corresponding to the width in the longitudinal direction of the print head 12 is used. A mode in which the print head 12 is moved in the short direction is also possible.

[Supporting part capping function and ink suction function]
FIG. 11 is a side view of the print head 12 in the short direction. As shown in the figure, a brush-like elastic member 132 is provided on the entire periphery of the nozzle surface 13 of the print head 12. By raising the support portion 22 so as to approach the nozzle surface 13 and stopping at a predetermined capping position, the elastic member 132 is brought into close contact with the platen 36 as shown in FIG. Thus, the entire nozzle surface 13 of the print head 12 (at least the entire area where the nozzles 51 are formed) is sealed. During the above-described cleaning operation, the first blade 71 that can be raised and lowered by an actuator (not shown) avoids the elastic member and performs the cleaning operation.

  When the power is turned off or during printing standby, the nozzle surface 13 is covered with the support portion 22 as shown in FIG. 12, thereby preventing the nozzle 51 from drying and preventing the ink viscosity from increasing near the nozzle. That is, the support portion 22 functions as a storage cap for the print head 12 together with the elastic member 132.

  Further, by driving the suction pump 39 in the state shown in FIG. 12, ink suction from the nozzle 51 is possible. That is, the support part 22 functions as an ink suction means during the nozzle suction operation.

  At this time, the suction range can be controlled by selectively controlling the suction pump 39 (selecting the liquid receiving portions 38A, 38B, and 38C) according to the frequency of use of the nozzle 51 and the like. Thereby, useless ink suction can be avoided and ink consumption can be suppressed.

[Example of shape of ink collecting means]
FIG. 13 is an enlarged view of the ink collecting hole 60 described in FIG. In the embodiment described with reference to FIG. 6, as an example of the ink collecting unit, the ink collecting hole 60 in which the peripheral ridge line defines a hexagon as illustrated in FIG. 13 has been described. In the case of the ink collecting hole 60, the ink 138 falling along the arrow from the upper side of FIG. 13 slides down on the inclined surface 63 and is aggregated and collected by suction through the opening 62 at the bottom. The recording paper 16 is supported by line contact at the ridge 64 of the ink collecting hole 60.

  In the practice of the present invention, the structure of the ink collecting means is not limited to the example of FIG. 13, and for example, a support structure of the recording paper 16 by point contact as shown in FIG. 14 is possible.

  The ink collecting means shown in FIG. 14 includes a protrusion 140 that supports the recording paper 16 by point contact, and an opening 142 formed at the bottom of the protrusion 140. The opening 142 is a through hole communicating with the back surface of the platen 36.

  In addition, although the substantially cone-shaped protrusion 140 was shown in the same figure, a protrusion shape is not limited to this, A pyramid shape may be sufficient.

  In order to ensure the flatness of the recording paper 16 point-supported by the tip portions 144 of the plurality of protrusions 140, the heights of the protrusions 140 are equal. Further, the side surface of the protrusion 140 forms an inclined surface 146 connected to the opening 142, and the ink 138 that falls along the arrow from above in FIG. 14 is slid down and aggregated through the inclined surface 146. It is collected by suction.

  Also with the configuration shown in FIG. 14, the recording paper 16 can be stably held and the back surface of the recording paper 16 can be prevented from being stained.

  In the platen 36 of the support portion 22 described with reference to FIG. 6, the ink collection holes 60 are arranged in a matrix form parallel to the longitudinal direction of the support portion 22 as shown in FIG. The arrangement form of the ink collecting holes 60 is not limited to this. For example, as shown in FIG. 15 (b), it is also possible to arrange the elements side by side along an oblique array line having an angle with respect to the longitudinal direction of the support portion 22.

  In the above embodiment, an inkjet recording apparatus using a page-wide full-line head having a nozzle row having a length corresponding to the entire width of the recording medium has been described. However, the scope of application of the present invention is not limited to this, and the short length The present invention can also be applied to an ink jet recording apparatus using a shuttle head that records an image while reciprocating the recording head.

In the above description, an ink jet recording apparatus is illustrated as an example of an image forming apparatus, but the scope of application of the present invention is not limited to this. For example, the present invention can be applied to a photographic image forming apparatus that applies a developing solution to a photographic paper in a non-contact manner. That is, the present invention can be widely applied not only to ink but also to other image forming apparatuses including a droplet discharge process in which a processing liquid, a functional liquid, or other liquid is applied to a medium. Other than the inkjet method, the present invention is applied to various types of image forming apparatuses such as an optical photographic print production apparatus, a thermal transfer recording apparatus having a line head, an LED electrophotographic printer, and a silver salt photographic printer having an LED line exposure head. It is possible.

1 is an overall configuration diagram of an inkjet recording apparatus according to an embodiment of the present invention. Plane perspective view showing structural example of print head Plane perspective view showing another structural example of the print head Sectional drawing which follows the 4-4 line in FIG. Enlarged view showing the nozzle arrangement of the print head shown in FIG. The perspective view which shows the structure of the support part 22 which supports a recording paper in the position facing the nozzle surface of a print head. Sectional drawing which follows the 7-7 line in FIG. Side view showing the cleaning operation Configuration diagram of control system for cleaning operation Flow chart showing control procedure of cleaning operation Schematic side view showing an example of means for sealing the nozzle surface of the print head Schematic side view showing an example of means for sealing the nozzle surface of the print head The perspective view which shows the example of a shape of an ink collection means The perspective view which shows the other example of a shape of an ink collection means Plan view showing an example of arrangement of ink collecting holes

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 12 ... Print head, 12 '... Head unit, 13 ... Nozzle surface, 14 ... Ink storage / loading part, 16 ... Recording paper, 22 ... Support part, 36 ... Platen, 37 ... Platen surface, 39 DESCRIPTION OF SYMBOLS ... Suction pump, 60 ... Ink collection hole, 61 ... Opening, 62 ... Opening, 63 ... Inclined surface, 64 ... Ridge, 65 ... Liquid-repellent layer, 70 ... Blade, 71 ... First blade, 72 ... Second blade, 77 ... Ink, 80 ... Blade traveling mechanism, 81 ... Ball screw, 82 ... Slider, 86 ... Motor, 90 ... Controller, 94 ... Blade drive unit, 96 ... Support unit drive unit, 132 ... Elastic member, 138 ... Ink, 140 ... Projection, 142 ... Open, 146 ... Inclined surface

Claims (8)

An ejection head in which nozzles for ejecting liquid droplets are formed;
Medium support means disposed at a position facing the nozzle surface of the ejection head and supporting a recording medium;
Liquid collecting means provided in the medium support means, an inclined surface that slides down the liquid that has entered from the ejection head side, and an opening that is formed at the bottom of the inclined surface and communicates with the back surface of the medium support means A liquid collecting means having
Suction means for sucking liquid through an opening of the liquid collecting means;
First cleaning means in contact with the nozzle surface of the ejection head;
A second cleaning means that contacts a medium support surface of the medium support means;
While the first cleaning means is in contact with the nozzle surface and the second cleaning means is in contact with the medium support surface, the first cleaning means and the second cleaning means are simultaneously connected to the nozzle surface and Cleaning drive means for moving relative to the medium support surface,
The first cleaning means includes a first blade that wipes the nozzle surface, while the second cleaning means includes a second blade that wipes the medium support surface,
The first blade and the second blade are arranged at a predetermined interval along a moving direction during cleaning by the cleaning drive means, and the first blade preceding the moving direction during the cleaning The nozzle surface is wiped by the nozzle, droplets are ejected from the nozzles in the nozzle region where the first blade has been wiped, and the region of the medium support surface to which the ejected droplets adhere is moved by the subsequent second blade. An image forming apparatus for wiping .   2. The image forming apparatus according to claim 1, wherein the liquid collecting means is a through-hole having a hole shape having a relatively wide opening on the discharge head side and a relatively narrow opening on the suction means side. .   The image forming apparatus according to claim 2, wherein a periphery of the through hole on the discharge head side of the liquid collecting unit has a ridge shape that supports the recording medium by line contact.   The image forming apparatus according to claim 3, wherein the liquid collecting unit has a ridge shape that is not orthogonal to a conveyance direction of the recording medium.   The image forming apparatus according to claim 1, wherein the liquid collecting unit includes a protrusion that supports the recording medium by point contact, and a side surface of the protrusion forms the inclined surface.   The image forming apparatus according to claim 1, wherein the liquid collecting unit has liquid repellency. Relative movement means for moving at least one of the medium support means and the ejection head in the droplet ejection direction of the ejection head;
Sealing means including an elastic member that covers the periphery of the nozzle surface of the discharge head and seals the nozzle surface by contacting the medium support means;
The image forming apparatus according to claim 1, further comprising:   The medium support unit functions as a capping unit that seals a nozzle surface of the ejection head during non-ejection, and also functions as a head liquid suction unit that performs liquid suction from the nozzle of the ejection head. 8. The image forming apparatus according to 7.

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