Printing apparatus

Abstract

Provided is a printing device that suppresses a mixture of ink and cleaning liquid from remaining when cleaning a printhead. The relationship Ln < Lc < Lp is satisfied when Lp is the length in a first direction of a nozzle surface of the printhead that discharges the ink from a plurality of nozzles arranged on the nozzle surface, Ln is the length in the first direction of a liquid-repellent nozzle region of the nozzle surface, and Lc is the length in the first direction of a cleaning liquid holding surface of a cleaning liquid holding member that uses cleaning liquid applied onto the cleaning liquid holding surface to clean the nozzle surface facing the cleaning liquid holding surface.

Description

Technical Field

[0001] The present invention relates to a printing apparatus, and particularly to a technique for cleaning the nozzle surface of a print head.

Background Art

[0002] In an inkjet recording apparatus, when dirt occurs on the nozzle surface of a print head due to deteriorated ink, nozzles with abnormal ejection occur. In particular, when nozzles with abnormal ejection occur in a single-pass type print head, streaks occur in the recorded image, and the image quality is significantly deteriorated. For this reason, in an inkjet recording apparatus, maintenance of the print head such as preliminary ejection, pressure purge, wiping of the nozzle surface, and nozzle suction is performed in order to prevent the occurrence of abnormal ejection and quickly recover from abnormal ejection.

[0003] For example, Patent Document 1 describes a maintenance apparatus for a print head that is arranged close to the upper surface of a base so as to face the nozzle surface of the print head to form a liquid storage space, and supplies liquid to the liquid storage space.

[0004] Further, Patent Document 2 describes an inkjet recording apparatus provided with maintenance means for cleaning a nozzle forming surface with a cleaning liquid by bringing the nozzle forming surface of the print head into contact with a liquid film of the cleaning liquid formed on a cleaning liquid holding surface.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the devices described in Patent Document 1 and Patent Document 2, a mixture of ink and cleaning liquid may remain at the end of the print head or the like. If the remaining mixture adheres to the print head, there is a concern that it will be difficult to replace and adjust the print head.

[0007] Also, when wiping the nozzle surface of the print head so that the mixture does not adhere, if relatively hard pigments are contained in the ink, there is a risk of damaging the nozzle surface of the print head.

[0008] Furthermore, the mixture also remains on the cleaning device side that cleans the print head. When the remaining mixture accumulates on the cleaning device, the accumulated mixture comes into contact with the nozzle surface of the print head. As a result, the ejection performance of the print head is disturbed, and image defects occur in the printed matter.

[0009] The present invention has been made in view of such circumstances, and an object thereof is to provide a printing device that suppresses the remaining of a mixture of ink and cleaning liquid when cleaning a print head.

Means for Solving the Problems

[0010] One aspect of a printing device for achieving the above object includes a print head that ejects ink from a plurality of nozzles arranged on a nozzle surface, a cleaning liquid holding member having a cleaning liquid holding surface, a relative movement mechanism that relatively moves the print head and the cleaning liquid holding member to oppose the cleaning liquid holding surface and the nozzle surface, and a cleaning liquid applying mechanism that applies a cleaning liquid to the cleaning liquid holding surface to clean the nozzle surface facing the cleaning liquid holding surface. The nozzle surface has a liquid-repellent nozzle region where a plurality of nozzles are arranged and a non-nozzle region with relatively lower liquid repellency than the nozzle region. When the length of the nozzle surface in the first direction is Lp, the length of the nozzle region in the first direction is Ln, and the length of the cleaning liquid holding surface in the first direction is Lc, it is a printing device that satisfies the relationship Ln < Lc < Lp. According to this aspect, it is possible to suppress the remaining of a mixture of ink and cleaning liquid on the print head when cleaning the print head.

[0011] The relative movement mechanism preferably positions the entire first direction of the cleaning fluid holding surface to face the nozzle surface, and the entire first direction of the nozzle region to face the cleaning fluid holding surface. This helps to suppress the residue of the mixture at the edges of the print head.

[0012] In the relative movement mechanism, it is preferable to position the cleaning fluid holding surface and the nozzle surface opposite each other with the first direction inclined with respect to the horizontal plane. This allows the print head, which is inclined with respect to the horizontal plane, to be cleaned while maintaining its inclination.

[0013] The cleaning liquid holding member has a side surface that is continuous with the cleaning liquid holding surface, and it is preferable that the angle between the vertically downward side surface and the cleaning liquid holding surface is acute. This makes it easier for the mixture to flow vertically downward on the side surface, and prevents the mixture from remaining in the cleaning liquid holding member.

[0014] The sides preferably have liquid-repellent properties. This helps to prevent the mixture from remaining on the cleaning liquid-retaining member.

[0015] The cleaning fluid application mechanism preferably applies the cleaning fluid to the cleaning fluid holding surface from the vertical downward side to the upward side. This allows the flow velocity of the cleaning fluid to be relatively slowed down, and the amount of cleaning fluid used can be relatively reduced.

[0016] The cleaning fluid holding member preferably has a cleaning fluid supply port on its cleaning fluid holding surface, and the cleaning fluid application mechanism preferably sprays cleaning fluid from the cleaning fluid supply port. This allows cleaning fluid to be applied to the cleaning fluid holding surface with a simple configuration.

[0017] In the relative movement mechanism, it is preferable to position the cleaning fluid supply port and the non-nozzle area opposite each other. This allows the cleaning fluid to be ejected without affecting the ink inside the nozzle and applied to the cleaning fluid holding surface.

[0018] The relative movement mechanism preferably moves the print head in a second direction orthogonal to the first direction and parallel to the cleaning liquid holding surface with the cleaning liquid holding surface and the nozzle surface facing each other. Thereby, even when the length of the cleaning liquid holding surface in the second direction is shorter than the length of the nozzle surface in the second direction, the entire nozzle surface can be cleaned.

[0019] Preferably, a plurality of print heads are arranged in the second direction. Even when a plurality of print heads are arranged in the second direction, the entire nozzle surface can be cleaned.

[0020] Preferably, a wiping device is provided for wiping the cleaned nozzle surface with a wiping member. Thereby, the cleaning liquid remaining on the nozzle surface after cleaning can be removed.

Advantages of the Invention

[0021] According to the present invention, it is possible to suppress the residue of a mixture of ink and cleaning liquid when cleaning the print head.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a perspective view of a print bar. [Figure 2] FIG. 2 is a plan view of a nozzle plate. [Figure 3] FIG. 3 is a schematic configuration diagram of a print head cleaning device. [Figure 4] FIG. 4 is a perspective view of a cleaning liquid applying head. [Figure 5] FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4. [Figure 6] FIG. 6 is a side view of a print head cleaning device. [Figure 7] FIG. 7 is a side view of a print head cleaning device according to the first embodiment. [Figure 8] FIG. 8 is a side view of a print head cleaning device according to the second embodiment. [Figure 9]Figure 9 is a side view of a print head cleaning device according to the third embodiment. [Figure 10] Figure 10 is a side view showing a schematic configuration of the image recording section of an inkjet recording device. [Figure 11] Figure 11 is a front view showing a schematic configuration of the image recording section of an inkjet recording device. [Figure 12] Figure 12 is a side view of the cleaning fluid application unit as seen from the maintenance position side. [Figure 13] Figure 13 is a block diagram showing the electrical configuration of the image recording unit. [Modes for carrying out the invention]

[0023] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0024] <Print bar configuration> Figure 1 is a perspective view of a print bar equipped with print heads to be cleaned by a print head cleaning device. The print bar 116 has 17 inkjet heads 117 (an example of a "print head") arranged in the X direction (an example of a "second direction").

[0025] The nozzle surface 130 of the inkjet head 117 consists of a nozzle plate 132, a wing portion 134, and an end cap portion 136. The nozzle plate 132 (an example of a "nozzle area") is treated with a liquid-repellent coating and has liquid-repellent properties. The wing portion 134 (an example of a "non-nozzle area") and the end cap portion 136 have relatively lower liquid-repellent properties than the nozzle plate 132.

[0026] Figure 2 is a plan view of the nozzle plate 132 on the nozzle surface 130, showing one inkjet head 117. Multiple nozzles 138 are arranged in a matrix on the nozzle plate 132 in the V direction, which has an inclination of angle β with respect to the X direction parallel to the horizontal plane, and in the W direction, which has an inclination of angle α with respect to the Y1 direction perpendicular to the X direction. Note that the Y1 direction is the Y direction perpendicular to the X direction, and is inclined by angle γ with respect to the Y direction parallel to the horizontal plane, with respect to the X direction as the axis.

[0027] The inkjet head 117 ejects ink droplets from the nozzles 138 using a so-called piezoelectric method. Each nozzle 138 is connected to a pressure chamber, and ink droplets are ejected from the nozzles 138 by vibrating the wall of this pressure chamber with a piezo element. The ink may be, for example, water-based ink. Water-based ink refers to ink in which colorants such as dyes and pigments are dissolved or dispersed in water and a water-soluble solvent.

[0028] <Configuration of the print head cleaning device> Figure 3 is a schematic diagram of the print head cleaning device 10, showing the configuration as viewed from the Y1 direction. As shown in Figure 3, the print head cleaning device 10 comprises a cleaning fluid application head 12, a cleaning fluid tank 14, a supply channel 16, a supply pump 18, a collection tray 20, a collection channel 22, and a collection tank 24. The cleaning fluid application head 12 is erected vertically upward (+Z direction).

[0029] The cleaning solution tank 14 stores a cleaning solution for cleaning the nozzle surface 130 of the inkjet head 117. For example, a cleaning solution mainly composed of diethylene monobutyl ether is used. By applying this type of cleaning solution to the nozzle surface 130, ink-derived mixtures adhering to the nozzle surface 130 can be dissolved and made easier to remove.

[0030] The cleaning fluid tank 14 is connected to the cleaning fluid dispensing head 12 via a supply channel 16. A supply pump 18 is also provided in the supply channel 16. The supply pump 18 (an example of a "cleaning fluid dispensing mechanism") supplies the cleaning fluid stored in the cleaning fluid tank 14 to the cleaning fluid dispensing head 12.

[0031] The collection tray 20 is positioned vertically below (-Z direction) the cleaning fluid dispensing head 12. The collection tray 20 has an open top. The bottom of the collection tray 20 is inclined with respect to the horizontal plane, and a collection hole (not shown) is provided at the lower end in the direction of the inclination. The collection hole is connected to the collection tank 24 via a collection channel 22.

[0032] The print bar 116 is positioned by a relative movement mechanism (for example, the transport control unit 202 shown in Figure 13) so that the nozzle surface 130 of the inkjet head 117 is parallel to and facing the cleaning fluid application head 12. The cleaning fluid application head 12 cleans the nozzle surface 130 with cleaning fluid supplied from the cleaning fluid tank 14. In the example shown in Figure 3, the relative movement mechanism moves the print bar 116 in the X direction, causing the cleaning fluid application head 12 to sequentially clean the nozzle surface 130 of each inkjet head 117.

[0033] The cleaning solution used to clean the nozzle surface 130 is collected in the recovery tray 20 along with the ink removed from the nozzle surface 130. The mixture of cleaning solution and ink collected in the recovery tray 20 is then collected in the recovery tank 24 via the recovery channel 22.

[0034] <Conventional cleaning solution dispensing head> FIG. 4 is a perspective view of the cleaning liquid application head 12. FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4. As shown in FIGS. 4 and 5, the cleaning liquid application head 12 (an example of a "cleaning liquid holding member") includes a cleaning liquid holding surface 30 and a cleaning liquid supply port 32. The cleaning liquid holding surface 30 is a rectangular flat surface. The cleaning liquid holding surface 30 is provided parallel to the XY1 plane that is inclined by an angle γ about the X direction with respect to the XY plane, which is a horizontal plane. The cleaning liquid supply port 32 (an example of a "cleaning liquid application mechanism") is a hole that partially opens in the cleaning liquid holding surface 30. The cleaning liquid supply port 32 ejects the cleaning liquid supplied from the cleaning liquid tank 14 and supplies it to the cleaning liquid holding surface 30.

[0035] FIG. 6 is a schematic diagram showing a cross-section of the print head cleaning device 10 and is a schematic diagram showing a state of cleaning the nozzle surface 130 of the inkjet head 117. As shown in FIG. 6, the nozzle surface 130 and the cleaning liquid holding surface 30 are arranged parallel to each other and facing each other. Also, the entire nozzle plate 132 and the nozzle surface 130 in the Y1 direction are arranged at positions facing the cleaning liquid holding surface 30. Further, the cleaning liquid supply port 32 is arranged at a position facing the wing portion 134.

[0036] In this state, the cleaning liquid is supplied from the cleaning liquid supply port 32 to the cleaning liquid holding surface 30 in an amount that fills the space between the nozzle surface 130 and the cleaning liquid holding surface 30 and more. The cleaning liquid supplied from the cleaning liquid supply port 32 to the cleaning liquid holding surface 30 fills the space between the nozzle surface 130 and the cleaning liquid holding surface 30, flows along the cleaning liquid holding surface 30 according to gravity, cleans the nozzle surface 130, and removes the ink adhering to the nozzle surface 130. Then, the cleaning liquid mixed with the ink removed from the nozzle surface 130 flows down from the end portion on the lower side in the vertical direction of the cleaning liquid holding surface 30 (here, the end portion on the +Y1 direction side) and is collected in the collection tray 20 (see FIG. 3).

[0037] For the print head cleaning device 10 shown in FIG. 6, when the length of the nozzle surface 130 in the Y1 direction (an example of a "first direction") is Lp, the length of the nozzle plate 132 in the Y1 direction is Ln, and the length of the cleaning liquid holding surface 30 in the Y1 direction is Lc, the following relationship of Equation 1 is satisfied. Ln < Lp < Lc …(Equation 1)

[0038] The printing head cleaning device 10 configured as described above had a problem that a mixture of ink and cleaning liquid adhered to and remained on the side surface on the lower side in the vertical direction of the inkjet head 117 (side surface 117A on the +Y1 direction side in FIG. 6). Also, there was a problem that a part of the mixture of ink and cleaning liquid did not flow down and remained on the side surface on the lower side in the vertical direction of the cleaning liquid application head 12 (side surface 34A on the +Y1 direction side in FIG. 6).

[0039] <First Embodiment> The printing head cleaning device according to the first embodiment will be described. Parts common to the printing head cleaning device 10 are denoted by common reference numerals, and detailed descriptions thereof are omitted.

[0040] FIG. 7 is a side view of a printing head cleaning device 40 according to the first embodiment, and is a schematic diagram showing a state of cleaning the nozzle surface 130 of the inkjet head 117.

[0041] The printing head cleaning device 40 includes a cleaning liquid application head 42. The cleaning liquid application head 12 and the cleaning liquid application head 42 differ only in the length in the Y1 direction of the cleaning liquid holding surface 30, and the other configurations are the same. As shown in FIG. 7, the nozzle surface 130 and the cleaning liquid holding surface 30 are arranged to face each other in parallel. Also, the entire length of the cleaning liquid holding surface 30 in the Y1 direction is arranged at a position facing the nozzle surface 130, and the entire length of the nozzle plate 132 in the Y1 direction is arranged at a position facing the cleaning liquid holding surface 30.

[0042] When the length of the nozzle surface 130 in the Y1 direction of the printing head cleaning device 40 is Lp, the length of the nozzle plate 132 in the Y1 direction is Ln, and the length of the cleaning liquid holding surface 30 in the Y direction is Lc, the following relationship of Equation 2 is satisfied. Ln < Lc < Lp …(Equation 2)

[0043] In this state, an amount of cleaning liquid greater than or equal to the amount that fills the space between the nozzle surface 130 and the cleaning liquid holding surface 30 is supplied from the cleaning liquid supply port 32 to the cleaning liquid holding surface 30. The cleaning liquid supplied from the cleaning liquid supply port 32 to the cleaning liquid holding surface 30 fills the space between the nozzle surface 130 and the cleaning liquid holding surface 30, flows across the cleaning liquid holding surface 30 due to gravity, cleans the nozzle surface 130, and removes the ink adhering to the nozzle surface 130. After that, the cleaning liquid mixed with the ink removed from the nozzle surface 130 flows down from the vertically lower end of the cleaning liquid holding surface 30 and is collected in the collection tray 20 (see Figure 3).

[0044] The print head cleaning device 40 is configured such that the length of the cleaning fluid holding surface 30 of the cleaning fluid application head 42 in the Y1 direction does not reach the side surface 117A of the inkjet head 117, thereby preventing the mixture from adhering to the side surface 117A.

[0045] <Second Embodiment> A print head cleaning device according to the second embodiment will now be described. Parts common to the print head cleaning device 40 are denoted by the same reference numerals, and detailed descriptions are omitted.

[0046] Figure 8 is a side view of the print head cleaning device 50 according to the second embodiment, and is a schematic diagram showing how the nozzle surface 130 of the inkjet head 117 is cleaned.

[0047] The print head cleaning device 50 includes a cleaning fluid dispensing head 52. The cleaning fluid dispensing head 52, like the cleaning fluid dispensing head 42, includes a cleaning fluid holding surface 30 and a cleaning fluid supply port 32. As shown in Figure 8, they are arranged parallel to each other. Furthermore, the entire Y1 direction of the cleaning fluid holding surface 30 is positioned to face the nozzle surface 130, and the entire Y1 direction of the nozzle plate 132 is positioned to face the cleaning fluid holding surface 30.

[0048] The print head cleaning device 50 satisfies the relationship in Equation 2, where Lp is the length of the nozzle surface 130 in the Y1 direction, Ln is the length of the nozzle plate 132 in the Y1 direction, and Lc is the length of the cleaning liquid holding surface 30 in the Y direction.

[0049] Furthermore, the cleaning fluid dispensing head 52 has a side surface 54A that is continuous with the cleaning fluid holding surface 30, and comprises a side surface 54A on the vertically downward side (the +Y1 direction side in Figure 8) and a back surface 56 on the opposite side from the cleaning fluid holding surface 30. The end of the cleaning fluid dispensing head 52 is tapered, and the length of the back surface 56 in the Y1 direction is shorter than the length of the cleaning fluid holding surface 30 in the Y1 direction. That is, the angle θa formed by the cleaning fluid holding surface 30 and the side surface 54A is acute. The angle θa is preferably 60 degrees or less, and more preferably 45 degrees or less, depending on the angle γ. Also, the angle θa is preferably 20 degrees or more, and more preferably 30 degrees or more.

[0050] In this state, an amount of cleaning liquid greater than or equal to the amount that fills the space between the nozzle surface 130 and the cleaning liquid holding surface 30 is supplied from the cleaning liquid supply port 32 to the cleaning liquid holding surface 30. The cleaning liquid supplied from the cleaning liquid supply port 32 to the cleaning liquid holding surface 30 fills the space between the nozzle surface 130 and the cleaning liquid holding surface 30, flows across the cleaning liquid holding surface 30 due to gravity, cleans the nozzle surface 130, and removes the ink adhering to the nozzle surface 130. After that, the cleaning liquid mixed with the ink removed from the nozzle surface 130 flows down from the vertically lower end of the cleaning liquid holding surface 30 and is collected in the collection tray 20 (see Figure 3).

[0051] In the print head cleaning device 50, the end of the cleaning fluid application head 52 is tapered, which allows the mixture of cleaning fluid and ink to flow more easily to the vertically downward side of the side surface 54A, preventing the mixture from adhering to the side surface 54A.

[0052] <Third Embodiment> A print head cleaning device according to the third embodiment will now be described. Parts common to the print head cleaning device 50 are denoted by the same reference numerals, and detailed descriptions are omitted.

[0053] Figure 9 is a side view of the print head cleaning device 60 according to the third embodiment, and is a schematic diagram showing how the nozzle surface 130 of the inkjet head 117 is cleaned.

[0054] The print head cleaning device 60 includes a cleaning fluid dispensing head 62. The cleaning fluid dispensing head 62, like the cleaning fluid dispensing head 52, includes a cleaning fluid holding surface 30. However, the cleaning fluid dispensing head 62 does not have a cleaning fluid supply port 32. As shown in Figure 9, the nozzle surface 130 and the cleaning fluid holding surface 30 are arranged parallel to each other. Furthermore, the entire Y1 direction of the cleaning fluid holding surface 30 is positioned opposite the nozzle surface 130, and the entire Y1 direction of the nozzle plate 132 is positioned opposite the cleaning fluid holding surface 30.

[0055] The print head cleaning device 60 satisfies the relationship in Equation 2, where Lp is the length of the nozzle surface 130 in the Y1 direction, Ln is the length of the nozzle plate 132 in the Y1 direction, and Lc is the length of the cleaning fluid holding surface 30 in the Y direction.

[0056] Furthermore, the cleaning fluid dispensing head 62 has a tapered end, and the length of the back surface 56 in the Y1 direction is shorter than the length of the cleaning fluid holding surface 30 in the Y1 direction.

[0057] Furthermore, the cleaning fluid dispensing head 62 has a side surface 54B on the vertically upward side (the -Y1 direction side in Figure 9), and the angle θb formed by the cleaning fluid holding surface 30 and the side surface 54B is acute. The angle θb is preferably 60 degrees or less, and more preferably 45 degrees or less, depending on the angle γ. Also, the angle θb is preferably 20 degrees or more, and more preferably 30 degrees or more.

[0058] The print head cleaning device 60 also includes a cleaning fluid supply nozzle 64. The cleaning fluid supply nozzle 64 is located on the vertically downward side of the cleaning fluid holding surface 30 (the +Y direction in Figure 9) and is positioned opposite the wing portion 134 when facing the inkjet head 117. The cleaning fluid supply nozzle 64 may be provided as a hole opening in the cleaning fluid holding surface 30, similar to the cleaning fluid supply port 32.

[0059] The cleaning fluid supply nozzle 64 sprays cleaning fluid supplied from the cleaning fluid tank 14 by the supply pump 18 and supplies it to the cleaning fluid holding surface 30. The cleaning fluid supply nozzle 64 supplies an amount of cleaning fluid that is greater than or equal to the amount that fills the space between the nozzle surface 130 and the cleaning fluid holding surface 30.

[0060] The cleaning fluid supplied from the cleaning fluid supply nozzle 64 to the cleaning fluid holding surface 30 fills the space between the nozzle surface 130 and the cleaning fluid holding surface 30, and flows across the cleaning fluid holding surface 30 from the bottom to the top in the vertical direction against gravity, cleaning the nozzle surface 130 and removing the ink adhering to the nozzle surface 130. In this embodiment, the flow velocity of the cleaning fluid is slower than the flow velocity of the cleaning fluid flowing across the cleaning fluid holding surface 30 in response to gravity.

[0061] Subsequently, the cleaning solution mixed with the ink removed from the nozzle surface 130 by cleaning flows down from the vertically upper end (in this case, the -Y direction end) of the cleaning solution holding surface 30 and is collected in the collection tray 20. In addition, a portion of the cleaning solution supplied from the cleaning solution supply nozzle 64 to the cleaning solution holding surface 30 flows down from the vertically lower end of the cleaning solution holding surface 30 and is collected in the collection tray 20.

[0062] The print head cleaning device 60 reduces the amount of cleaning fluid that flows between the nozzle surface 130 and the cleaning fluid holding surface 30 by compensating for the flow rate of cleaning fluid that flows against gravity with the force (flow rate) of the cleaning fluid that flows against gravity. Therefore, the amount of cleaning fluid used for the same amount of cleaning time can be relatively reduced compared to the print head cleaning devices 40 and 50.

[0063] Furthermore, since the end of the cleaning fluid application head 52 of the print head cleaning device 60 is tapered, the mixture of cleaning fluid and ink flows more easily to the vertically downward side of side 54A and side 54B, preventing the mixture from adhering to side 54A and side 54B.

[0064] <Configuration of an inkjet recording device> This section describes an inkjet recording device (an example of a "printing device") to which a printhead cleaning device is applied.

[0065] Figure 10 is a schematic side view showing the image recording section of an inkjet recording device that records images on a sheet of paper using a single-pass method. As shown in Figure 10, the image recording section 110 transports the sheet of paper 112 using an image recording drum 114. During the transport process by the image recording drum 114, the image recording section 110 ejects ink droplets of C (cyan), M (magenta), Y (yellow), and K (black) from print bars 116C, 116M, 116Y, and 116K arranged around the image recording drum 114, respectively, to record a color image on the surface of the sheet of paper 112.

[0066] The image recording drum 114 has a rotating shaft 118, and both ends of the rotating shaft 118 are supported by a pair of bearings 122 (see Figure 11), allowing it to rotate freely. The pair of bearings 122 are provided on the main frame 120 (see Figure 11) of the inkjet recording device. The image recording drum 114 is mounted horizontally by the pair of bearings 122, with both ends of the rotating shaft 118 supported parallel to the horizontal mounting surface.

[0067] A motor (not shown) is connected to the rotating shaft 118 via a rotation transmission mechanism (not shown). The image recording drum 114 rotates when driven by the motor.

[0068] The image recording drum 114 has grippers 124 that grip the leading edge of the sheet paper 112. The grippers 124 are provided at two locations on the outer surface of the image recording drum 114. The sheet paper 112 is held on the outer surface of the image recording drum 114 by its leading edge being gripped by the grippers 124.

[0069] The image recording drum 114 has an adsorption holding mechanism, such as electrostatic adsorption or vacuum adsorption (not shown). The sheet paper 112, whose tip is gripped by the gripper 124 and wrapped around the outer surface of the image recording drum 114, is held on the outer surface of the image recording drum 114 by the adsorption holding mechanism on its back side.

[0070] The sheets of paper 112 before image recording are transferred from the transport drum 126 to the image recording drum 114. The transport drum 126 is positioned parallel to the image recording drum 114, and the sheets of paper 112 are transferred to the image recording drum 114 at the appropriate time.

[0071] Furthermore, the sheets 112 after image recording are transferred from the image recording drum 114 to the transport drum 128. The transport drum 128 is positioned parallel to the image recording drum 114 and receives the sheets 112 from the image recording drum 114 at the appropriate time.

[0072] The four print bars 116C, 116M, 116Y, and 116K are line heads corresponding to the X-direction length of the sheet paper 112. Print bars 116C, 116M, 116Y, and 116K are each the same print bar 116 shown in Figure 1. That is, each print bar 116C, 116M, 116Y, and 116K is equipped with multiple inkjet heads 117.

[0073] The print bars 116C, 116M, 116Y, and 116K are mounted on the print bar support frame 140 and arranged radially at regular intervals on concentric circles around the rotation axis 118 of the image recording drum 114, and are arranged symmetrically on either side of the image recording drum 114. That is, the cyan print bar 116C and the black print bar 116K are arranged symmetrically with respect to a vertical line segment passing through the center of the image recording drum 114, and the magenta print bar 116M and the yellow print bar 116Y are also arranged symmetrically.

[0074] The print bars 116C, 116M, 116Y, and 116K each have nozzle surfaces 130C, 130M, 130Y, and 130K of an inkjet head 117, each having a nozzle 138 (see Figure 2) positioned at its bottom. The print bars 116C, 116M, 116Y, and 116K are each positioned perpendicular to the Y direction, which is the transport direction of the sheet paper 112, and with the nozzle surfaces 130C, 130M, 130Y, and 130K of each inkjet head 117 facing the outer circumferential surface of the image recording drum 114. The print bars 116C, 116M, 116Y, and 116K are each positioned with the same distance between the outer circumferential surface of the image recording drum 114 and the nozzle surfaces 130C, 130M, 130Y, and 130K of each inkjet head 117.

[0075] The print bars 116C, 116M, 116Y, and 116K eject ink droplets perpendicularly toward the outer surface of the image recording drum 114 from nozzles 138 located on the nozzle surfaces 130C, 130M, 130Y, and 130K of each inkjet head 117.

[0076] Figure 11 is a front view showing a schematic configuration of the image recording section of an inkjet recording device. The print bar support frame 140, to which the print bars 116C, 116M, 116Y, and 116K are attached, consists of a pair of side plates 142L and 142R provided perpendicular to the rotation axis 118 of the image recording drum 114, and a connecting frame 144 that connects the pair of side plates 142L and 142R at their upper ends.

[0077] The pair of side plates 142L and 142R are plate-shaped and are arranged facing each other with the image recording drum 114 in between. On the inside of the pair of side plates 142L and 142R are mounting sections 146C, 146M, 146Y, and 146K for mounting the print bars 116C, 116M, 116Y, and 116K. Note that in Figure 11, only the mounting section 146Y is shown for convenience.

[0078] The mounting sections 146C, 146M, 146Y, and 146K are arranged radially at regular intervals on concentric circles centered on the rotation axis 118 of the image recording drum 114. The print bars 116C, 116M, 116Y, and 116K are attached to the print bar support frame 140 by fixing the mounting sections 148C, 148M, 148Y, and 148K (only mounting section 148Y is shown in Figure 11 for convenience) provided at both ends to the mounting sections 146C, 146M, 146Y, and 146K.

[0079] The print bar support frame 140 is guided by a guide rail (not shown) and is slidably mounted parallel to the rotation axis 118 of the image recording drum 114. The print bar support frame 140 is driven by a linear drive mechanism (not shown) (for example, a lead screw mechanism) and moves at a predetermined speed between the "image recording position" shown by a solid line in Figure 11 and the "maintenance position" shown by a dashed line in Figure 11.

[0080] When the print bar support frame 140 is positioned in the image recording position, the print bars 116C, 116M, 116Y, and 116K are positioned around the image recording drum 114 and become ready for image recording.

[0081] The maintenance position is set to a position where the print bars 116C, 116M, 116Y, and 116K are retracted from the image recording drum 114. A moisturizing unit 150 is provided at the maintenance position to moisturize the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of print bars 116C, 116M, 116Y, and 116K, respectively.

[0082] The moisturizing unit 150 is equipped with caps 152C, 152M, 152Y, and 152K (only cap 152Y is shown in Figure 11 for convenience) that cover the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of print bars 116C, 116M, 116Y, and 116K, respectively. When the device is stopped for an extended period, the nozzle surfaces 130C, 130M, 130Y, and 130K are covered by caps 152C, 152M, 152Y, and 152K. This prevents the nozzles 138 from drying out and failing to eject ink.

[0083] Caps 152C, 152M, 152Y, and 152K are equipped with a pressurizing mechanism and a suction mechanism (not shown), which can pressurize and suction the nozzle 138. Caps 152C, 152M, 152Y, and 152K are also equipped with a cleaning fluid supply mechanism (not shown), which can supply cleaning fluid to the inside.

[0084] A waste liquid tray 154 is positioned below caps 152C, 152M, 152Y, and 152K. The cleaning liquid supplied to caps 152C, 152M, 152Y, and 152K is discarded into the waste liquid tray 154 and recovered into the waste liquid tank 158 via the waste liquid recovery piping 156.

[0085] Between the image recording position and the maintenance position, a nozzle surface cleaning device 160 is provided for cleaning the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of print bars 116C, 116M, 116Y, and 116K. The nozzle surface cleaning device 160 consists of a cleaning fluid application unit 162 that applies cleaning fluid to the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of print bars 116C, 116M, 116Y, and 116K and cleans them, and a wiping unit 164 that wipes the nozzle surfaces 130C, 130M, 130Y, and 130K to which the cleaning fluid has been applied.

[0086] The cleaning fluid application unit 162 applies cleaning fluid to the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of print bars 116C, 116M, 116Y, and 116K, respectively. The wiping unit 164 (an example of a "wiping device") wipes the nozzle surfaces 130C, 130M, 130Y, and 130K to which the cleaning fluid has been applied using a strip-shaped wiping web (an example of a "wiping member"), which is not shown.

[0087] The print bars 116C, 116M, 116Y, and 116K move between a maintenance position and an image recording position, allowing the nozzle surface cleaning device 160 to clean the nozzle surfaces 130C, 130M, 130Y, and 130K of each inkjet head 117.

[0088] In the example shown in Figure 11, the wiping unit 164 is positioned on the image recording side relative to the cleaning fluid application unit 162, but it may also be positioned on the maintenance side relative to the cleaning fluid application unit 162.

[0089] <Configuration of the cleaning solution dispensing unit> Figure 12 is a side view of the cleaning fluid dispensing unit 162 as seen from the maintenance position side. The cleaning fluid dispensing unit 162 is installed inside the waste liquid tray 154 provided in the moisturizing unit 150 (see Figure 11). The cleaning fluid dispensing unit 162 comprises cleaning fluid dispensing units 170C, 170M, 170Y, and 170K, which are provided corresponding to the print bars 116C, 116M, 116Y, and 116K, respectively, and a main body 172 on which the cleaning fluid dispensing units 170C, 170M, 170Y, and 170K are mounted.

[0090] The main body 172 is installed horizontally and is provided to be able to move up and down by a lifting device (not shown). The main body 172 has cleaning fluid dispensing unit mounting sections 172C, 172M, 172Y, and 172K on its upper surface. The cleaning fluid dispensing units 170C, 170M, 170Y, and 170K are fixed to the cleaning fluid dispensing unit mounting sections 172C, 172M, 172Y, and 172K provided on the main body 172 with bolts or the like, and are positioned on the movement paths of the corresponding print bars 116C, 116M, 116Y, and 116K, respectively.

[0091] The cleaning fluid dispensing units 170C, 170M, 170Y, and 170K are each fitted with a print head cleaning device 40, a print head cleaning device 50, or a print head cleaning device 60, respectively. That is, the cleaning fluid dispensing units 170C, 170M, 170Y, and 170K are each equipped with a cleaning fluid holding surface 30 and a cleaning fluid supply port 32.

[0092] The cleaning fluid holding surfaces 30 of the cleaning fluid application units 170C, 170M, 170Y, and 170K have the same inclination angle as the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of the print bars 116C, 116M, 116Y, and 116K. This inclination angle corresponds to the angle γ described above.

[0093] <Electrical configuration of an inkjet recording device> Figure 13 is a block diagram showing the electrical configuration of the image recording unit 110. The image recording unit 110 comprises a movement control unit 200, a transport control unit 202, an image recording control unit 206, a moisturizing unit control unit 208, a cleaning liquid control unit 210, a wiping control unit 212, and a back pressure control unit 214.

[0094] The movement control unit 200 controls the movement of the print bars 116C, 116M, 116Y, and 116K (an example of "relative movement"). The movement control unit 200 drives a linear drive mechanism (not shown) to move the print bars 116C, 116M, 116Y, and 116K, which are supported by the print bar support frame 140, between the image recording position and the maintenance position (see Figure 11).

[0095] The transport control unit 202 controls the transport of the sheets 112. The transport control unit 202 controls the gripper 124 (see Figure 10) to grip the leading edge of the sheets 112. The transport control unit 202 also controls a suction holding mechanism (not shown) to hold the sheets 112 on the outer surface of the image recording drum 114. Furthermore, the transport control unit 202 drives a motor (not shown) to rotate the image recording drum 114, holding the sheets 112 on the image recording drum 114 for transport.

[0096] Furthermore, the transport control unit 202 drives the transport drums 126 and 128 (see Figure 10) to transport the sheets 112 from the transport drum 126 to the image recording drum 114, and then from the image recording drum 114 to the transport drum 128.

[0097] The image recording control unit 206 controls the print bars 116C, 116M, 116Y, and 116K. The image recording control unit 206 ejects ink droplets from the nozzles 138 of each inkjet head 117 of the print bars 116C, 116M, 116Y, and 116K, thereby recording a color image on the surface of the sheet paper 112 being transported by the image recording drum 114.

[0098] The moisturizing unit control unit 208 controls the moisturizing unit 150 to moisturize the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of the print bars 116C, 116M, 116Y, and 116K. The moisturizing unit control unit 208 controls a pressurizing mechanism and a suction mechanism (not shown) to pressurize and suction the nozzles 138 of the inkjet heads 117 of the print bars 116C, 116M, 116Y, and 116K from the caps 152C, 152M, 152Y, and 152K. The moisturizing unit control unit 208 controls a cleaning fluid supply mechanism (not shown) to supply cleaning fluid into the caps 152C, 152M, 152Y, and 152K.

[0099] The cleaning fluid control unit 210 controls the cleaning fluid supply unit 162 to supply cleaning fluid to the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of print bars 116C, 116M, 116Y, and 116K, respectively. The cleaning fluid control unit 210 moves the main body 172 (see Figure 12) from the standby position by a predetermined amount to the operating position. The cleaning fluid control unit 210 also drives the supply pumps 18 of the cleaning fluid supply units 170C, 170M, 170Y, and 170K to spray cleaning fluid from the cleaning fluid supply port 32 (see Figure 4).

[0100] The wiping control unit 212 controls the wiping unit 164 to wipe the nozzle surfaces 130C, 130M, 130Y, and 130K of the inkjet heads 117 of print bars 116C, 116M, 116Y, and 116K with the wiping web.

[0101] <Other> The residue of the mixture on the sides of the cleaning solution dispensing head 12 may be suppressed by applying a liquid-repellent treatment to the sides (for example, side 34A) to impart liquid-repellent properties. However, this is more costly than forming the ends in a tapered shape.

[0102] The technical scope of the present invention is not limited to the scope described in the embodiments above. The configurations and other elements in each embodiment can be appropriately combined with those in each embodiment without departing from the spirit of the present invention. [Explanation of symbols]

[0103] 10…Print head cleaning device 12…Cleaning solution dispensing head 14…Cleaning solution tank 16… Supply channel 18…Supply pump 20…Collection trays 22… Recovery channel 24… Recovery Tank 30… Cleaning solution retention surface 32... Cleaning fluid supply port 34A…Side 40…Print head cleaning device 42... Cleaning solution dispensing head 50…Print head cleaning device 52... Cleaning solution dispensing head 54A... Side view 54B…Side 56…Back side 60…Print head cleaning device 62... Cleaning solution dispensing head 64…Cleaning fluid supply nozzle 110...Image recording unit 112…sheets 114...Image recording drum 116... Print bar 116C... Print bar 116K... Print bar 116M…Print bar 116Y…Print bar 117... Inkjet head 117A…Side 118... Rotation axis 120...Main frame 122... Bearings 124... Grippa 126... Conveyor drum 128... Conveyor Drum 130... Nozzle surface 130C... Nozzle surface 130K... Nozzle surface 130M…Nozzle surface 130Y…Nozzle surface 132…Nozzle plate 134...Wing section 136... End cap section 138… Nozzle 140... Print bar support frame 142L... Side plate 142R... Side Plate 144... Connecting frame 146C... Mounting part 146K... Mounting part 146M…Mounting part 146Y…Mounting part 148C…Attachment part 148K...Mounted part 148M…Attachment part 148Y...Mounted part 150… Moisturizing Unit 152C... Cap 152K...cap 152M…Cap 152Y…Cap 154...Waste liquid tray 156...Waste liquid recovery piping 158...Waste liquid tank 160... Nozzle surface cleaning device 162... Cleaning solution application section 164... Wiping section 170C... Cleaning fluid dispensing unit 170K... Cleaning fluid dispensing unit 170M... Cleaning fluid dispensing unit 170Y... Cleaning fluid dispensing unit 172...Main unit 172C... Cleaning fluid application unit mounting section 172K... Cleaning fluid application unit mounting section 172M... Cleaning fluid application unit mounting section 172Y... Cleaning fluid application unit mounting section 200...Movement Control Unit 202... Transport Control Unit 206...Image Recording Control Unit 208... Moisturizing Unit Control Unit 210... Cleaning fluid control unit 212... Wiping Control Unit 214...Back pressure control unit

Claims

1. A print head that ejects ink from multiple nozzles arranged on the nozzle surface, A cleaning liquid holding member having a cleaning liquid holding surface, A relative movement mechanism that moves the print head and the cleaning fluid holding member relative to each other to bring the cleaning fluid holding surface and the nozzle surface facing each other, A cleaning liquid application mechanism that applies cleaning liquid to the cleaning liquid holding surface to clean the nozzle surface facing the cleaning liquid holding surface, Equipped with, The nozzle surface has a nozzle region having liquid-repellent properties where the plurality of nozzles are arranged, and a non-nozzle region having relatively lower liquid-repellent properties than the nozzle region. If the length of the nozzle surface in the first direction is Lp, the length of the nozzle region in the first direction is Ln, and the length of the cleaning liquid holding surface in the first direction is Lc, Ln < Lc < Lp Satisfying the relationship, The relative movement mechanism brings the cleaning liquid holding surface and the nozzle surface opposite each other with the first direction inclined with respect to the horizontal plane. Printing device.

2. The relative movement mechanism brings the entire first direction of the cleaning liquid holding surface to face the nozzle surface, and the entire first direction of the nozzle region to face the cleaning liquid holding surface. The printing apparatus according to claim 1.

3. The cleaning fluid holding member has a side surface that is continuous with the cleaning fluid holding surface, and the angle between the vertically downward side surface and the cleaning fluid holding surface is acute. The printing apparatus according to claim 1.

4. The aforementioned side surface has liquid-repellent properties. The printing apparatus according to claim 3.

5. The cleaning fluid application mechanism applies the cleaning fluid to the cleaning fluid holding surface from the lower side in the vertical direction toward the upper side. The printing apparatus according to claim 1.

6. The cleaning fluid holding member has a cleaning fluid supply port on the cleaning fluid holding surface, The printing apparatus according to claim 1, wherein the cleaning liquid supply mechanism ejects the cleaning liquid from the cleaning liquid supply port.

7. The printing apparatus according to claim 6, wherein the relative movement mechanism is configured to face the cleaning liquid supply port and the non-nozzle region.

8. The relative movement mechanism moves the print head relative to the cleaning fluid holding surface in a second direction that is perpendicular to the first direction and parallel to the cleaning fluid holding surface, with the cleaning fluid holding surface and the nozzle surface facing each other. The printing apparatus according to claim 1.

9. The printing apparatus according to claim 8, wherein a plurality of print heads are arranged in the second direction.

10. The printing apparatus according to any one of claims 1 to 9, further comprising a wiping device for wiping the cleaned nozzle surface with a wiping member.

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