Head cleaning device, head cleaning method, and image forming apparatus

Abstract

To reduce maintenance cost in a cleaning device of an ink discharge head.SOLUTION: A long-sized cleaning sheet which is brought into contact with nozzle surfaces of first and second discharge heads arranged at an interval and cleans the nozzle surface is moved by only a distance L3 shorter than a path length between a part where the nozzle surface of the first discharge head is cleaned and a part where the nozzle surface of the second discharge head is cleaned, up to the previous cleaning before start of the next cleaning after end of the previous cleaning.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a head cleaning device that cleans the nozzle surface of an ejection head such as an inkjet head, an image forming apparatus that includes the head cleaning device, and a head cleaning method. [Background technology]

[0002] 2. Description of the Related Art In recent years, inkjet printers that form images on a recording medium by ejecting ink from the nozzles of an inkjet head have been used in a wide range of fields.

[0003] Such inkjet printers are generally equipped with a head cleaning device that uses a sheet-like cleaning member to wipe away ink, dust, and other contaminants that have adhered to the nozzle surface of the inkjet head (the surface on which the nozzle openings of the inkjet head are located) to prevent deterioration of image quality and the adhesion of unnecessary contaminants to the recording medium.

[0004] Conventionally, when using a cleaning member to wipe the nozzle surfaces of multiple inkjet heads arranged at predetermined intervals in one direction, after cleaning of the multiple inkjet heads is performed at a predetermined timing, a winding device winds up the part of the cleaning member that has wiped the most upstream inkjet head in the movement direction of the cleaning member by a predetermined length (hereinafter referred to as "one revolution" for convenience) until it moves to a position immediately downstream of the most downstream inkjet head, and the nozzle surfaces of each inkjet head are cleaned with a new, unused part of the cleaning member (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-148173 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if the cleaning member is wound up one revolution for each head cleaning operation as described above, the portion between two adjacent inkjet heads that is not used for cleaning will be wound up unused, resulting in higher maintenance costs.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a head cleaning device that can reduce maintenance costs, an image forming apparatus equipped with such a head cleaning device, and a head cleaning method. [Means for solving the problem]

[0008] In order to achieve the above object, a head cleaning device according to one aspect of the present disclosure includes: , each of which is equipped with a first and a second head row. a moving means for moving the cleaning member by a distance shorter than the length of a path from a portion of the nozzle face of the first discharge head that was cleaned in the previous cleaning to a portion of the nozzle face of the second discharge head that was cleaned in the previous cleaning after the previous cleaning is completed and before the next cleaning is started; a pressing means provided corresponding to each of the first and second discharge heads; and a control unit for controlling each of the pressing means, In the above, the first head row and the second head row The cleaning member is disposed with a predetermined gap therebetween in the moving direction of the cleaning member. TeiThe control unit is characterized in that, during cleaning, while the cleaning member is stopped, it drives each of the pressing means to switch between a first pressing state in which a first portion of the cleaning member corresponding to the nozzle surface of the first head row in the corresponding ejection head is pressed against the nozzle surface, and a second pressing state in which a second portion of the cleaning member corresponding to the nozzle surface of the second head row in the corresponding ejection head is pressed against the nozzle surface.

[0009] In another aspect of the present disclosure, the direction in which the cleaning member is moved by the moving means is a direction that intersects with the direction in which the nozzle rows in the first and second ejection heads extend.

[0010] In another aspect of the present disclosure, a tension applying means is provided for applying tension to the cleaning member in the longitudinal direction thereof.

[0012] In another aspect of the present disclosure, the pressing means includes elastic means for biasing a contact portion that contacts the cleaning member toward the cleaning member.

[0013] In another aspect of the present disclosure, The first and second ejection heads are respectively The pressing means is capable of individually pressing the portions of the cleaning member that correspond to the nozzle faces of the first and second ejection heads.

[0014] In another aspect of the present disclosure, the first and second ejection heads are used to eject inks of different colors.

[0015] In another aspect of the present disclosure, the cleaning member is a strip-shaped sheet member, and the moving means includes a first roll on which the cleaning member is wound before use, a second roll for winding up the used cleaning member, and a driving means for driving the second roll to rotate.

[0016] In another aspect of the present disclosure, a detection means is provided for detecting the diameter of the cleaning member wound around the first roll or the diameter of the cleaning member wound around the second roll, and the driving means adjusts the amount of rotation of the second roll when the cleaning member is moved based on the diameter detected by the detection means.

[0017] In another aspect of the present disclosure, cleaning of the nozzle surfaces of the first and second ejection heads is performed simultaneously.

[0018] In another aspect of the present disclosure, the cleaning device further includes a guide means for guiding the cleaning member so that the path of movement of the cleaning member between the first and second ejection heads is V-shaped or W-shaped.

[0019] In another aspect of the present disclosure, the first ejection head is located upstream of the second ejection head in the direction of movement of the cleaning member, and the path length of the cleaning member between the first ejection head and the second ejection head is at least N times (N is an integer greater than or equal to 2) the width in the direction of movement of the cleaning member required to clean the nozzle surface of the second ejection head in one cleaning operation.

[0020] Furthermore, a head cleaning method according to another aspect of the present disclosure includes: , each of which is equipped with a first and a second head row. A head cleaning method for a head cleaning device having a long cleaning member that comes into contact with the nozzle faces of first and second ejection heads to clean the nozzle faces, wherein after the end of a previous cleaning and before the start of a next cleaning, the cleaning member is moved a distance shorter than the path length from a portion of the nozzle face of the first ejection head that was cleaned in the previous cleaning to a portion of the nozzle face of the second ejection head that was cleaned, and the head cleaning device further has pressing means provided corresponding to each of the first and second ejection heads, In the above, the first head row and the second head row The cleaning member is disposed with a predetermined gap therebetween in the moving direction of the cleaning member. TeiDuring cleaning, while the cleaning member is stopped, each of the pressing means is driven to switch between a first pressing state in which a first portion of the cleaning member corresponding to the nozzle surface of the first head row in the corresponding ejection head is pressed against the nozzle surface, and a second pressing state in which a second portion of the cleaning member corresponding to the nozzle surface of the second head row in the corresponding ejection head is pressed against the nozzle surface.

[0021] Furthermore, an image forming apparatus according to another aspect of the present disclosure is an image forming apparatus having an image forming unit that forms an image by ejecting ink from first and second ejection heads onto a recording sheet, and a head cleaning unit that cleans the nozzle surfaces of each of the first and second ejection heads, and is characterized in that the head cleaning device described above is used as the head cleaning unit. [Effects of the Invention]

[0022] According to the above disclosed aspects, when performing a cleaning operation on the nozzle surfaces of a plurality of ejection heads, it is possible to minimize unused portions of the cleaning member, thereby reducing maintenance costs. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a diagram illustrating a main configuration of an image forming apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2(a) is a perspective view showing the configuration of a head unit, and FIG. 2(b) is a schematic view of the head unit as seen from below. [Figure 3] FIG. 2 is a diagram illustrating a main configuration of a head maintenance unit in the image forming apparatus. [Figure 4] 10A to 10C are diagrams showing the procedure for head maintenance of the head unit by the head maintenance section. [Figure 5]10(a) to 10(c) are schematic diagrams illustrating how the cleaning sheet is pressed by the pressing mechanism in the nozzle surface cleaning unit. [Figure 6] FIG. 2 is an overall perspective view of a nozzle surface cleaning unit. [Figure 7] FIG. 2 is a perspective view showing the configuration of a pressing mechanism. [Figure 8] 5A and 5B are diagrams illustrating the pressing operation of the pressing mechanism. [Figure 9] FIG. 2 is a block diagram showing a configuration of a control unit in the image forming apparatus. [Figure 10] 10 is a flowchart showing a control procedure for a head maintenance process executed by the control unit. [Figure 11] 10(a) to 10(c) are diagrams illustrating the amount of movement of the cleaning sheet during the nozzle surface cleaning operation according to the present embodiment. [Figure 12] FIG. 10 is a schematic diagram showing a modified example of the nozzle surface cleaning unit. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a head cleaning device, a head cleaning method, and an image forming apparatus according to the present disclosure will be described with reference to the accompanying drawings.

[0025] <Embodiment> (1) Overall configuration of the image forming device First, the configuration of the image forming apparatus according to this embodiment will be described.

[0026] As shown in FIG. 1, the image forming apparatus 1 according to this embodiment is a so-called inkjet printer, and includes a paper feed section 110, an image forming section 120, a paper discharge section 140, a control section 150, and an operation panel 160.

[0027] The paper feed unit 110 has a paper feed tray 111 and a conveying unit 112. The paper feed tray 111 is a tray for placing a stack of recording sheets S (sheet-like recording media) used for image formation. As the recording sheets S, various media can be used, such as paper such as plain paper or coated paper, as well as fabric or sheet-like resin, on whose surface ink can be fixed.

[0028] The sheet feed tray 111 moves up and down depending on the number of sheets in the sheet stack, and moves to a position where the topmost recording sheet S in the sheet stack is fed out by the conveying section 112.

[0029] The conveying unit 112 uses a pickup roller (not shown) to feed the recording sheets S one by one from the top of the sheet stack placed on the paper feed tray 111. The conveying unit 112 has a sheet conveying mechanism in which an endless conveying belt 114 is wound around rollers 113 and 115.

[0030] The conveying unit 112 places the recording sheet S sent out by the pickup roller on the conveying belt 114, and then rotates and drives the rollers 113 and 115 to rotate the conveying belt 114 in the direction of arrow A, thereby conveying the recording sheet S to the image forming unit 120.

[0031] The image forming section 120 includes a transport drum 121, a delivery unit 122, a sheet heating section 123, a head unit (ejection head section) 124, a fixing section 125, a delivery section 126, etc., and forms an image on a recording sheet S by inkjet printing.

[0032] The delivery unit 122 has a swing arm portion 127 and a delivery drum 128. The delivery unit 122 uses the swing arm portion 127 to hold one end of the recording sheet S conveyed by the conveying portion 112, thereby picking up the recording sheet S and delivering the recording sheet S to the delivery drum 128.

[0033] The delivery drum 128 delivers the recording sheet S to the transport drum 121 by guiding the recording sheet S along the outer circumferential surface of the transport drum 121 .

[0034] Upon receiving the recording sheet S from the delivery unit 122, the transport drum 121 transports the recording sheet S by being rotated in the direction of arrow B with the recording sheet S held on the outer peripheral surface of the cylindrical shape.

[0035] The conveying drum 121 may have, for example, an air intake hole on its outer peripheral surface, and may suck in outside air through the air intake hole to adsorb the recording sheet S onto the outer peripheral surface. Also, a claw for holding the edge of the recording sheet S may be provided on the outer peripheral surface.

[0036] The transport drum 121 is rotated by a transport drum rotation drive motor (not shown). During this rotation, the rotation angle of the transport drum 121 is adjusted so that ink ejected from the inkjet head lands at a desired location on the recording sheet S.

[0037] The sheet heating section 123 heats the recording sheet S carried on the outer peripheral surface of the transport drum 121 on the transport path of the recording sheet S from the delivery unit 122 to the head unit 124 so that the temperature of the recording sheet S reaches a predetermined range.

[0038] For this reason, the sheet heating unit 123 is disposed opposite the outer peripheral surface of the conveying drum 121, and supplies power to an infrared heater or the like to radiate heat and raise the temperature of the recording sheet S. The temperature of the recording sheet S is adjusted to a predetermined range by controlling the amount of power supplied to the infrared heater or the like.

[0039] The head unit 124 is disposed downstream of the sheet heating unit 123 in the rotation direction of the transport drum 121. The head unit 124 includes a plurality of inkjet heads, and forms an image on the recording sheet S by ejecting ink from the nozzles of the inkjet heads in synchronization with the state of transport of the recording sheet S by the transport drum 121.

[0040] The head unit 124 may be a single-pass type in which nozzles are arranged across the entire effective image area of ​​the recording sheet S along the axial direction of the transport drum 121, or may be a scan type in which nozzles are arranged on a carriage that moves back and forth along the axial direction of the transport drum 121 and ink is ejected while the carriage is moved.

[0041] When the scanning method is adopted, a carriage moving mechanism 170 (not shown in Figure 1; see Figure 3) that moves the carriage moves the nozzle surface of the inkjet head to a position (printing area) facing the outer surface of the conveying drum 121 during image formation.

[0042] In addition, in order to land ink at appropriate positions on the recording sheet S, a plurality of head units 124 are arranged at positions where the distance from the ink ejection surface of the inkjet head to the outer circumferential surface of the transport drum 121 is appropriate.

[0043] In this embodiment, five colors of ink are used to form a color image: yellow (Y), magenta (M), cyan (C), black (K), and white (W). Therefore, five head units 124 corresponding to the five colors of ink, YMCKW, are arranged in a predetermined order along the outer circumferential surface of the transport drum 121 from the upstream side to the downstream side in the rotation direction of the transport drum 121 at equal intervals.

[0044] Each head unit 124 has the same configuration except for the color of ink that it supplies.

[0045] FIG. 2(a) is a perspective view that schematically shows the configuration of one head unit 124. As shown in FIG.

[0046] As shown in the figure, the head unit 124 is configured by mounting eight inkjet heads 1241 to 1248 on a carriage 1240 formed long in a direction (Y direction) perpendicular to the conveyance direction of the sheet S.

[0047] FIG. 2(b) is a schematic diagram of the head unit 124 as seen from the side of the sheet S being transported by the transport drum 121.

[0048] As shown in the figure, for example, the inkjet head 1241 is made up of two inkjet head modules 1241a and 1241b, and the nozzle rows thereof are arranged in parallel in the Y direction.

[0049] The inkjet head 1241 is mounted with the surface (nozzle surface) on which the multiple nozzles 1241c arranged in a row at a predetermined pitch in the Y-axis direction are opening, facing the sheet S transported by the transport drum 121 and slightly protruding and exposed from the underside of the carriage 1240.

[0050] Each nozzle 1241c is provided with an actuator consisting of a piezoelectric element and a vibration plate (not shown), and when a voltage is applied to the electrodes of the piezoelectric element, the actuator deforms and ink is ejected from each nozzle 1241c.

[0051] The other inkjet heads 1242 to 1248 have the same configuration as the inkjet head 1241, so their explanation will be omitted.

[0052] A head row HL1 consisting of inkjet heads 1241, 1243, 1245, and 1247 arranged in a row, and a head row HL2 consisting of inkjet heads 1242, 1244, 1246, and 1248 arranged in a row are arranged parallel to the Y direction with a predetermined gap G1 in the X direction.

[0053] In this embodiment, if the length of the nozzle row in each of the inkjet heads 1241 to 1248 in the Y-axis direction is L11, then the inkjet heads in head row HL1 and head row HL2 are arranged offset by L11 in the Y-axis direction, so that when viewed from the X-axis direction, the multiple nozzles in the inkjet heads in each of head row HL1 and head row HL2 are lined up consecutively at equal pitches.

[0054] By arranging a plurality of inkjet heads in this manner, the printing range in the Y-axis direction (main scanning direction) by the head unit 124 can be lengthened, and the printing speed can be improved.

[0055] In addition, there is a gap G1 between the head row HL1 and the head row HL2 of the head unit 124 in the X direction.

[0056] However, the configuration of the head unit 124 is not limited to that shown in FIG. 2(b).

[0057] The nozzle surfaces of the inkjet heads 1241 to 1248 of the head unit 124 become dirty due to the ejection of ink, and therefore require maintenance at predetermined intervals, and for this purpose a head maintenance unit 200 is provided in parallel with the transport drum 121 on the front side of the paper (Y direction) in FIG. 1 (not shown in FIG. 1; see FIG. 3). Details will be described later.

[0058] The fixing section 125 is disposed downstream of the head unit 124 in the rotation direction of the conveying drum 121, and uses, for example, a mercury lamp to irradiate ultraviolet rays across the entire width of the recording sheet S in the main scanning direction, thereby hardening the ink that has landed on the recording sheet S and fixing it to the recording sheet S.

[0059] It should be noted that the energy rays suitable for curing ink differ depending on the characteristics of the ink, so it is desirable to use an energy ray source that is not limited to a mercury lamp but that is suited to the characteristics of the ink.

[0060] The delivery unit 126 includes a sheet transport mechanism in which an endless belt 131 is wound around rollers 129 and 132, and a delivery drum 130. The delivery drum 130 is disposed so as to face the outer circumferential surface of the transport drum 121 downstream of the fixing unit 125 in the rotation direction of the transport drum 121, and delivers the recording sheet S carried on the outer circumferential surface of the transport drum 121 to the sheet transport mechanism of the delivery unit 126.

[0061] The sheet transport mechanism rotates rollers 129 and 132 to make belt 131 travel in the direction of arrow C, and transports the recording sheet S received from delivery drum 130 to paper discharge unit 140.

[0062] The paper discharge unit 140 has a paper discharge tray 141, and sequentially stacks the recording sheets S transported from the image forming unit 120 by the delivery unit 126 onto the paper discharge tray 141. The stack of recording sheets S stacked on the paper discharge tray 141 is then collected by the user.

[0063] The control unit 150 monitors and controls the status and operation of each unit of the image forming apparatus 1. The control unit 150 also accepts print jobs from external devices such as personal computers (PCs) and sends notifications related to print jobs.

[0064] The operation panel 160 presents information to the user of the image forming apparatus 1 and receives instructions input from the user under the control of the control unit 150. For this reason, the operation panel 160 includes a display unit such as a liquid crystal panel and an operation unit such as a touch panel or hard keys.

[0065] (2) Head maintenance unit 200 In an inkjet type image forming device, there is a risk that dust or other foreign matter may become stuck inside the nozzles of the head unit 124, or that the ink may solidify and cause clogging. In addition, when ink is ejected from the nozzles, the ink may adhere to the nozzle surface, causing deterioration in image quality or staining of the recording sheet S.

[0066] Therefore, in this embodiment, a head maintenance unit 200 is provided that cleans the inkjet heads of the head units 124 at predetermined timings.

[0067] FIG. 3 is a schematic diagram showing the configuration of the head maintenance unit 200 according to this embodiment.

[0068] As shown in the figure, the head maintenance unit 200 is located in the Y direction (on the front side of the apparatus) of the transport drum 121 in the image forming unit 120, and includes an ink ejection unit 20, an ink scraping unit 25, and a nozzle surface cleaning unit 30.

[0069] The ink ejection section 20 includes a funnel-shaped ink receiver 21 and an ink tank 22 that collects and stores the ink ejected into the ink receiver 21.

[0070] For example, when the power switch of the image forming apparatus is turned on, each head unit 124 is moved by the carriage movement mechanism 170 from the circumferential surface of the transport drum 121 in the recording area to above the ink receiver 21 of the ink ejection unit 20 in the maintenance area. As the carriage movement mechanism 170, for example, a wire drive or a ball screw mechanism is used.

[0071] Then, a predetermined amount of ink is ejected from all the nozzles of the head unit 124 toward the ink receiver 21 to remove foreign matter and ink coagulation from inside the nozzles (hereinafter referred to as "inside the nozzles cleaning"). This prevents the nozzles from clogging.

[0072] The ink discharged into the ink receiver 21 is collected in the ink tank 22 below and periodically disposed of. A liquid level sensor may be provided in the ink tank 22 so that when the ink level reaches a predetermined height, a message to that effect is displayed on the display screen of the operation panel 160, prompting the user to discard the ink in the ink tank 22 or replace the entire ink tank 22.

[0073] The ink scraping unit 25 includes a wiper blade 251 and an actuator 252 that drives the wiper blade 251 up and down. The actuator 252 may be, for example, an air cylinder, but is not limited to this.

[0074] The wiper blade 251 is moved upward by an actuator 252 as needed, and scrapes off ink adhering to the nozzle surface of each inkjet head of the head unit 124 by the above-mentioned internal nozzle cleaning.

[0075] The nozzle surface cleaning unit 30 brings a sheet-like cleaning member (hereinafter referred to as "cleaning sheet") into contact with the nozzle surface of the head unit 124, and removes any remaining ink that has not been scraped off by the ink scraping unit 25 by having the cleaning sheet absorb it (hereinafter referred to as "nozzle surface cleaning").

[0076] 4(a) to 4(c) show a schematic diagram of the procedure for head maintenance in the head maintenance unit 200. FIG.

[0077] First, the head unit 124 is moved in the Y1 direction from the recording area and positioned above the ink receiver 21 of the ink ejection section 20, and a predetermined amount of ink is ejected to perform cleaning inside the nozzles (FIG. 4(a)).

[0078] Thereafter, the wiper blade 251 is moved upward, the head unit 124 is moved in the Y2 direction, and the ink that has adhered to the nozzle surface due to the ink ejection is scraped off by the wiper blade 251 (FIG. 4(b)).

[0079] In this embodiment, the wiper blade 251 is formed from a rigid material such as metal, and the amount of upward movement of the wiper blade 251 is regulated so that a small gap (for example, about 0.5 mm) is created between the tip of the blade and the nozzle surface of the head unit 124, so that the nozzle surface is not worn or damaged by the ink scraping process of the wiper blade 251.

[0080] Once the ink scraping process on the nozzle surface has been completed over the entire longitudinal length of the head unit 124, the wiper blade 251 is lowered, and the movement of the head unit 124 in the Y2 direction is reversed and it is moved intermittently in the Y1 direction, while the nozzle surface cleaning unit 30 performs nozzle surface cleaning to remove any ink remaining on the nozzle surface of the head unit 124 (Figure 4(c)).

[0081] Although Figures 3 and 4 provide an overview of the maintenance process for one head unit 124, it is rational to perform maintenance processes for five color head units 124 simultaneously, as this shortens the processing time and reduces the waiting time for workers.

[0082] For this reason, the ink ejection unit 20 and the ink scraping unit 25 are provided corresponding to each head unit 124, and as will be explained next, the nozzle surface cleaning unit 30 is also configured to be able to perform nozzle surface cleaning of five head units 124 simultaneously.

[0083] (3) Configuration of the nozzle surface cleaning unit 30 FIG. 5(a) is a schematic diagram of the nozzle surface cleaning unit 30 as viewed from the left side in the Y axis direction in FIG.

[0084] As shown in FIG. 5( a), the nozzle surface cleaning unit 30 includes a support frame 31 whose upper edge is semicircular with a radius of curvature substantially the same as that of the transport drum 121, a supply roll 33 (first roll) on which an unused strip-shaped cleaning sheet 32 ​​(cleaning member) is wound, a take-up roll 34 (second roll) on which the used cleaning sheet 32 ​​is wound, a drive unit 35 including a motor and gears for driving the take-up roll 34 to rotate, and a moving path of the cleaning sheet 32 ​​from the supply roll 33 to the take-up roll 34, which is defined by the support frame 31. the supply roll 33; and five pressing mechanisms 36 (pressing means) that are provided corresponding to each head unit 124 that has been moved above the nozzle surface cleaning section 30 by the carriage movement mechanism 170 (FIG. 3) and that push up the cleaning sheet 32 ​​and press it against the nozzle faces of the inkjet heads of the head units 124. The supply roll 33 also includes a distance sensor (diameter detection means) 37 that measures the diameter of the cleaning sheet 32 ​​wound around the supply roll 33.

[0085] The control unit 150 adjusts the amount of rotation of the winding roll 34 by the drive unit 35 while referring to the detection result of the distance sensor 37. Details will be described later.

[0086] The cleaning sheet 32 ​​is a long, strip-shaped sheet made of a highly absorbent fabric material such as microfiber, and by pressing the cleaning sheet 32 ​​against the nozzle surface of the head unit 124 using the pressing mechanism 36, it absorbs and cleans the ink remaining on the nozzle surface.

[0087] FIG. 5(a) shows a state when the pressing mechanism 36 is in the initial position (home position), and the cleaning sheet 32 ​​is not in contact with the nozzle surface of the head unit 124.

[0088] When cleaning the nozzle surface of the inkjet head in head row HL1 (see Figure 2) of head unit 124, as shown in Figure 5(b), the pressing mechanism 36 shifts slightly to the left and pushes up the cleaning sheet 32 ​​at a position corresponding to the nozzle surface of head row HL1, bringing the cleaning sheet 32 ​​into contact with the nozzle surface of head row HL1 to clean the nozzle surface (first pressing state).

[0089] Furthermore, when cleaning the nozzle surface of the inkjet head in head row HL2 of head unit 124, the pressing mechanism 36 shifts slightly to the right as shown in Figure 5(c) and pushes up the cleaning sheet 32 ​​at a position corresponding to the nozzle surface of head row HL2, bringing the cleaning sheet 32 ​​into contact with the nozzle surface of head row HL2 to clean the nozzle surface (second pressing state).

[0090] FIG. 6 is a perspective view showing the appearance of the nozzle surface cleaning unit 30. As shown in FIG.

[0091] As shown in the figure, multiple shaft members 321 to 326 (guiding means) are arranged parallel to the Y axis at predetermined intervals along the approximately semicircular upper edges of support frames 31 and 31', which are arranged opposite each other at a predetermined interval, and the cleaning sheet 32 ​​pulled out from the supply roll 33 is guided by these shaft members 321 to 326 and taken up around the take-up roll 34.

[0092] In this way, the shaft members 321 to 326 of the cleaning sheet 32 ​​are arranged along the upper edges of the upwardly curved support frames 31, 31', so that the underside of the cleaning sheet 32 ​​can be reliably brought into contact with each of the shaft members 321 to 326, making the cleaning sheet 32 ​​less likely to twist. Furthermore, the shaft members 321 to 326 support the cleaning sheet 32 ​​from below and do not come into contact with parts of the cleaning sheet 32 ​​that are stained with ink, so the shaft members 321 to 326 do not become stained with ink, making maintenance easier.

[0093] The means for guiding the moving path of the cleaning sheet 32 ​​is not necessarily limited to a shaft member, but may be a roller or the like.

[0094] In addition, a drive motor 361 of the pressing mechanism 36 is attached to the support frame 31 on the front side.

[0095] FIG. 7 is a perspective view showing an example of the configuration of the pressing mechanism 36. As shown in FIG.

[0096] As shown in the figure, the pressing mechanism 36 includes a movable part 367 in which a holding member 3671 extending horizontally is attached to the upper ends of a pair of arm members 365, 366 arranged in parallel and facing each other, and a plate-shaped abutting member 3672 is held above the holding member 3671 via a compression spring 3675, and a crank mechanism 368 for vertically moving the movable part 367. Note that instead of the compression spring 3675, other elastic means, for example, a leaf spring or a rubber plate, may be used.

[0097] In the crank mechanism 368, cranks 3632 and 3642 are fixed to rotating shafts 3631 and 3641 of gears 363 and 364 which mesh with a gear 362 attached to the drive shaft of the motor 361 and rotate synchronously in the same direction when driven by the motor 361. On the arm member 366 side, cranks 3634 and 3644 having the same shape as the cranks 3632 and 3642 are supported on the support frame 31 by shafts 3635 and 3645 arranged coaxially with the rotating shafts 3631 and 3641.

[0098] The tips of cranks 3632, 3634 and cranks 3642, 3644 are connected via rods 3633, 3643 that pass through arm members 365, 366, respectively. When driven by motor 361, the cranks rotate in sync, driving arm members 365, 366 up and down.

[0099] 8(a) and (b) are diagrams showing how the abutment member 3672 is driven up and down via the arm member 365 when the pressing mechanism 36 in FIG. 7 is viewed from the direction of arrow Y1, and the motor 361 and the like are not shown.

[0100] As shown in FIG. 8(a), when the gears 363 and 364 are rotated clockwise by the driving of the motor 361, the arm member 365 is rotated upward from the left side (first pressing state: see FIG. 5(b)).

[0101] Furthermore, as shown in FIG. 8(b), when the gears 363 and 364 are rotated leftward by the driving of the motor 361, the arm member 365 is moved upward from the right side (second pressing state: see FIG. 5(c)).

[0102] As described above, the abutment member 3672 is supported by the holding member 3671 via the compression spring 3675, so that when the movable part 367 is moved upward, it comes into contact with the rear surface of the cleaning sheet 32 ​​and pushes up the cleaning sheet 32 ​​with an appropriate force, thereby firmly adhering the cleaning sheet 32 ​​to the nozzle surface of the head unit 124 and allowing it to sufficiently absorb ink.

[0103] Furthermore, a top 3673 is pivotally supported by a support piece 3674 at each of the four corners of the holding member 3671. The length of the holding member 3671 in the longitudinal direction is greater than the width of the cleaning sheet 32, and when the movable part 367 rises and the abutting member 3672 presses the back surface of the cleaning sheet 32, a part of the top of the top 3673 protrudes slightly upward outside the width direction of the cleaning sheet 32 ​​and abuts against the back surface of the carriage 1240 of the head unit 124, thereby regulating the distance from the nozzle surface of the head unit 124 and preventing the pressing force of the abutting member 3672 on the cleaning sheet 32 ​​from becoming excessive.

[0104] Furthermore, the rotation of the top 3673 also acts to smoothly move the head unit 124 in the longitudinal direction (the Y-axis direction in FIG. 6: the direction perpendicular to the moving direction of the cleaning sheet 32).

[0105] (4) Configuration of the control unit 150 FIG. 9 is a block diagram showing the configuration of the control unit 150 of the image forming apparatus 1. As shown in FIG.

[0106] As shown in the figure, the control unit 150 includes a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, a HDD (Hard Disk Drive) 404, a timer 405, and a NIC (Network Interface Card) 406.

[0107] The CPU 401, ROM 402, etc. are connected via an internal bus 407 so as to be able to communicate with each other.

[0108] When the image forming apparatus 1 is reset, for example, by powering on, the CPU 401 reads and starts up a boot program from the ROM 402, and reads and executes an OS (Operating System), control programs, etc. from the HDD 404 using the RAM 403 as a working storage area.

[0109] This allows the control unit 150 to monitor and control the operating state of each unit of the image forming apparatus 1.

[0110] Note that a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used instead of the ROM 402. The RAM 403 may also be a nonvolatile memory.

[0111] The timer 405 performs timing processing required when the CPU 401 executes programs such as a control program. In particular, the timer 405 records the elapsed time after the execution of an image forming job, and notifies the CPU 401 when a predetermined time has elapsed. Upon receiving this notification, the CPU 401 controls, for example, the head maintenance unit 200 to execute head maintenance processing.

[0112] The NIC 406 executes communication processing for the control unit 150 to receive a print job including image data from an external device such as a PC, etc. The NIC 406 may perform communication via a LAN (Local Area Network) or the Internet.

[0113] The NIC 406 may be a serial interface such as a USB (Universal Serial Bus) or a parallel interface.

[0114] The control unit 150 controls a drive signal input to a transport drum drive motor (not shown) to rotate the transport drum 121 at a predetermined speed and timing, and also controls the operation of the paper feed unit 110 and the delivery unit 122 to supply the recording sheet S to the transport drum 121, and controls the operation of the delivery unit 126 to discharge the recording sheet S onto the transport drum 121. The control unit 150 energizes and deforms piezoelectric elements corresponding to the nozzles of the inkjet head constituting the head unit 124 of the image forming unit 120 so that an appropriate amount of ink is ejected from the nozzles at an appropriate timing according to image data, thereby forming an image on the recording sheet S.

[0115] Furthermore, at a predetermined timing, it controls each part of the head maintenance section 200 to perform maintenance of the head unit 124 (head maintenance processing).

[0116] (5) Head maintenance control by the control unit 150 FIG. 10 is a flowchart for explaining the control of the head maintenance process executed by the control unit 150.

[0117] This control of the head maintenance process is executed when the head maintenance process is required, for example, when the image forming apparatus 1 is turned on, when a long time has passed since the previous image forming job was executed (for example, three hours), or when the user notices a deterioration in image quality and inputs an instruction to execute head maintenance via the operation panel 160.

[0118] First, the carriage moving mechanism 170 moves the head unit 124 to the maintenance area (step S11).

[0119] A predetermined amount of ink is ejected from the inkjet heads 1241 to 1248 of the head unit 124 into the ink receiver 21 to perform cleaning inside the nozzles (step S12: FIG. 4(a)).

[0120] Then, the wiper blade 251 is raised, and the head unit 124 is moved toward the recording area, and the wiper blade 251 scrapes off excess ink adhering to the nozzle surface (steps S13 and S14: FIG. 4(b)).

[0121] When the ink scraping process by the wiper blade 251 is completed as a result of the movement of the head unit 124 to the recording area, the movement of the head unit 124 is stopped at a predetermined position, and the wiper blade 251 is lowered (step S15). At this time, the stopping position of the head unit 124 is set to a position where the nozzle surface, which is the first target of the nozzle surface cleaning process, is positioned above the cleaning sheet 32, thereby enabling an efficient transition to the subsequent nozzle surface cleaning process.

[0122] Next, the cleaning sheet 32 ​​is wound up (step S16) by a path length corresponding to the position immediately upstream of the head unit 124 located at the most upstream side in the direction of movement of the cleaning sheet 32, from the position immediately downstream of the head unit 124 located at the most downstream side, i.e., the path length ("one revolution") until the portion that has cleaned the nozzle surface of the most upstream head unit 124 moves to a position immediately downstream of the head unit 124 located at the most downstream side, and then the nozzle surface cleaning process of steps S17 to S21 begins.

[0123] In this embodiment, as one example, the width W11 of the cleaning sheet 32 ​​(see FIG. 11(a)) is set to be slightly larger than L12, which is twice the nozzle row length L11 of one inkjet head, and the area to be cleaned of the head unit 124 (the total distance (L11×8) of the nozzle faces of the inkjet heads 1241l to 1248) is divided into four equal parts, for example, and four cleaning processes are performed.

[0124] During the ink scraping process in step S14, the head unit 124 is stopped so that the head units 1241 and 1242 are on the cleaning sheet 32, and the pressing mechanism 36 is driven to alternately raise the abutment member 3672 left and right to execute the first and second pressing states (Figures 5(b) and 5(c)), cleaning the nozzle faces of the inkjet heads belonging to the head rows HL1 and HL2 of the head unit 124 (step S17). Thereafter, the abutment member 3672 is lowered to the home position (step S18: Figure 5(a)), and the cleaning sheet 32 ​​is wound up by the width of the cleaned portion (distance L3: see Figure 11(a)) (step S19).

[0125] Note that, depending on the state of winding of the cleaning sheet 32 ​​by the winding roll 34, differences in the winding amount may occur even when the winding roll 34 is rotated the same number of times. To address this, the winding diameter of the winding roll 34 may be detected, and the control unit 150 may adjust the number of rotations of the winding roll 34 required to wind up a target amount of cleaning sheet 32 ​​according to the size of the diameter.

[0126] Since the winding diameter of the winding roll 34 and the winding diameter of the supply roll 33 are correlated, in this embodiment, the distance sensor 37 measures the distance to the surface of the cleaning sheet 32 ​​wound on the supply roll 33, and the control unit 150 controls the winding amount of the winding roll 34 based on this measurement value.

[0127] This type of control is performed, for example, by storing in advance in ROM 402 a table showing the relationship between the diameter value of supply roll 33 and the amount of rotation of take-up roll 34 required to move cleaning sheet 32 ​​by the required length, and by having CPU 401 refer to this table to control the rotation of take-up roll 34. Of course, it is also possible to directly detect and control the winding diameter of take-up roll 34.

[0128] In this embodiment, an optical distance sensor is used as the distance sensor 37, but other known sensors may be used as long as they can detect the winding diameter of the cleaning sheet 32 ​​on the supply roll 33 or winding roll 34.

[0129] Next, in step S20, it is determined whether cleaning of all nozzle surfaces of head unit 124 has been completed (step S20). If not completed (NO in step S20), head unit 124 is moved in the Y1 direction (FIG. 4(c)) by a predetermined amount (in this embodiment, this is a length L12 (=L11×2) that is one-fourth of the total length of the nozzle row of head unit 124) by carriage movement mechanism 170 (step S21), and the process returns to step S17 to clean the next nozzle surface.

[0130] The determination in step S20 can be made, for example, by having the control unit 150 count how many times the routine of steps S17 to S20 has been repeated (in this embodiment, it is determined that cleaning of all nozzle surfaces has been completed when the routine has been repeated four times).

[0131] When cleaning of all nozzle surfaces in the head unit 124 is completed (YES in step S20), the nozzle surface cleaning process of the head unit 124 is completed, and the carriage movement mechanism 170 moves the carriage 1240 to the recording area on the transport drum 121 (step S22), thereby completing the head maintenance process.

[0132] The position where the winding process of the cleaning sheet 32 ​​in step S19 is performed may be between steps S20 and S21, or between steps S21 and S17.

[0133] The above head maintenance process is executed simultaneously for all five color head units 124 .

[0134] 11(a) to 11(c) are diagrams that schematically show the effect of controlling the movement amount (take-up amount) of the cleaning sheet 32 ​​in the nozzle surface cleaning unit 30 according to the present embodiment (step S19).

[0135] In the same figure, 124(R) and 124(Y) respectively indicate the area where the nozzle surface to be cleaned of the head unit 124 for ejecting R color ink exists, and the area where the nozzle surface to be cleaned of the head unit 124 for ejecting Y color ink exists.

[0136] L1 indicates the path length from the upstream edge of the region 124(R) in the moving direction X1 of the cleaning sheet to the downstream edge of the region 124(Y) in the X1 direction.

[0137] Furthermore, L2 indicates the path length of the cleaning sheet 32 ​​in the X1 direction between the region 124(R) and the region 124(Y), and L3 indicates the width of the region 124(R) and the region 124(Y) in the X1 direction.

[0138] In this example, after the first nozzle surface cleaning, the nozzle surface is moved in the X1 direction by L3 for each of the second and third nozzle surface cleanings (see FIGS. 11(b) and 11(c). Note that 411, 421, etc. in FIGS. 11(b) and 11(c) respectively indicate rectangular areas on the cleaning sheet 32 ​​that include the area that was cleaned the previous time). Although not shown in the figure, the fourth time also operates in the same way.

[0139] In the prior art, when there are two inkjet heads, as shown in Figure 11(a), the path length L1 is moved for each nozzle cleaning, so the portion of path length L2 between area 124(R) and area 124(Y) is wound up completely unused, resulting in a lot of waste and requiring frequent replacement of cleaning sheet 32. However, in the present embodiment, the unused portion can be reduced, making it possible to reduce maintenance costs.

[0140] In the present embodiment, the cleaning sheet 32 ​​is moved by a width L3 in the X1 direction of the regions 124(R) and 124(Y). However, even if the movement amount of the cleaning sheet 32 ​​is greater than the width L3, if the cleaning sheet 32 ​​is moved by a distance shorter than the path length between the cleaning area of ​​the nozzle face of the upstream head unit 124 in the previous cleaning operation and the cleaning area of ​​the nozzle face of the adjacent head unit 124 on the downstream side (that is, the path length from the cleaned portion of the nozzle face of the upstream head unit 124 (first ejection head) to the cleaned portion of the nozzle face of the downstream head unit 124 (second ejection head). Hereinafter, this is abbreviated as the “length between cleaned areas.” Specifically, this corresponds to L2 in FIG. 11(a), L4 in FIG. 11(b), and L5 in FIG. 11(c)), it is possible to reduce the unused portion of the cleaning sheet 32 ​​compared to conventional movement control of the cleaning sheet 32, which contributes to reducing maintenance costs.

[0141] In this case, it is desirable that the distance be shorter than the length between the cleaned regions, and that at least the nozzle surface cleaning region of the upstream head unit 124 does not overlap with the nozzle surface region of the downstream head unit 124. However, even if there is some overlap, the unused portion will always be in the next region to be cleaned, so a certain degree of cleaning effect can be ensured (for example, in FIG. 11(c) , it is acceptable for the cleaned regions 411 and 412, and 421 and 422, to overlap slightly). However, it is desirable that the cleaned regions of different ink colors on the cleaning sheet 32 ​​do not overlap (for example, in FIG. 11(c) , the cleaned region 411 for R and the cleaned region 422 for Y partially overlap). This is because there is a risk of the nozzle surface for a specific color ink being soiled with the ink of another color, degrading image quality.

[0142] (6) Other examples of nozzle surface cleaning processing In the example of the nozzle surface cleaning process described above (steps S17 to S21 in FIG. 10), as an example, the total nozzle length in the longitudinal direction of the head unit 124 (the sum of the longitudinal lengths of all nozzle surfaces) is divided into four equal parts, and the head unit 124 is moved in the Y1 direction by L12 (= 2 × L11) while the cleaning process is repeated four times to clean all nozzle surfaces of the head unit 124. By dividing it into multiple parts in this way, the width W11 of the cleaning sheet 32 ​​can be further reduced, which contributes to making the device more compact and reducing costs.

[0143] To pursue this advantage, the entire nozzle length of the head unit 124 is divided into eight equal parts, and the cleaning procedure for moving the head unit 124 in the Y1 direction by L11 steps will be described below in correspondence with steps S14 and S17 to S21 in FIG.

[0144] (A) First, in step S14, the nozzle surface of the inkjet head 1241 of the head unit 124 is positioned directly above the cleaning sheet 32 ​​when the wiper blade 251 has finished scraping off the ink.

[0145] (a) Then, in step S17, the contact member 3672 of the pressing mechanism 36 is raised to the first pressing state, and cleaning of the nozzle surface of the inkjet head 1241 (head HL1) is carried out.

[0146] (c) Thereafter, the contact member 3672 is lowered (step S18), and the cleaning sheet 32 ​​is wound up by a predetermined distance (step S19).

[0147] As described in FIG. 2(b), there is a gap G1 in the X direction between head array HL1 and head array HL2 of head unit 124 according to this embodiment, and this gap G1 is equal to the width in the X direction of the nozzle surface of each inkjet head (strictly speaking, the nozzle surface including nozzle arrays 1241a and 1241b of the inkjet head). Therefore, in this example, the take-up amount of cleaning sheet 32 ​​is set to the size of the gap G1 between head arrays HL1 and HL2.

[0148] By doing so, the portion of the cleaning sheet 32 ​​corresponding to the gap G1 can also be used to clean the nozzle surface, so the cleaning sheet 32 ​​can be used even more efficiently, contributing to further cost reductions.

[0149] (d) Next, in step S20, it is determined whether cleaning of all nozzle surfaces of the head unit 124 has been completed (step S20). If not completed (NO in step S20), the head unit 124 is moved by L11 in the Y1 direction (Figure 4(c)) from the carriage movement mechanism 170 (step S21), and the process returns to step S17, where the next nozzle surface (here, the nozzle surface of the inkjet head 1242 of head HL2: Figure 2(b)) is cleaned by setting the pressing mechanism 36 to the second pressing state.

[0150] (O) The operations of steps S17 to S21 are repeated until cleaning of all nozzle surfaces of all inkjet heads 1241 to 1248 of head unit 124 is completed, and when cleaning of all nozzle surfaces of head unit 124 is completed (YES in step S20), cleaning of the eight nozzle surfaces of head unit 124 is completed.

[0151] In this example, the position where the cleaning sheet 32 ​​is wound up in step S19 may also be between steps S20 and S21, or between steps S21 and S17.

[0152] In this example, the cleaning sheet 32 ​​is wound up and moved over a distance G1 that is smaller than the width L3 of the head unit 124. Therefore, for example, in FIG. 11(b), areas 411, 412 and areas 421, 422 overlap each other in the X-axis direction, and all nozzle surfaces of the inkjet heads 1241 to 1248 of the head unit 124 can be sufficiently cleaned within the range of L3+L2 in FIG. 11(a).

[0153] Furthermore, in this example, the width W11 (Figure 11(a)) of the cleaning sheet 32 ​​can be narrowed to approximately the same size as the length L11 of the nozzle row in one inkjet head, thereby enabling further compactness and cost reduction.

[0154] <Modification> The present disclosure has been described above based on the embodiments, but it goes without saying that the present disclosure is not limited to the above-described embodiments, and the following modified examples can be implemented.

[0155] (1) In the above embodiment, the example of using energy beam irradiation ink has been described. However, it goes without saying that the present disclosure is not limited to this, and other types of ink or liquids other than ink may be used instead.

[0156] (2) In the above embodiment, microfiber is used as an example of the material of the cleaning sheet 32, but any suitable material may be used depending on the quality of the ink used.

[0157] (3) It is desirable to make the path length of the cleaning sheet 32 ​​between the portions corresponding to the nozzle faces of the head units 124 adjacent to each other in the direction of movement of the cleaning sheet 32 ​​(corresponding to path length L1 in Figure 11) as long as possible, as this increases the number of times cleaning can be performed between them.

[0158] In particular, when there are multiple inkjet heads in the longitudinal direction of one head unit 124 and the head unit 124 is cleaned multiple times (at least twice), it is desirable to determine the spacing between adjacent head units 124 so that the path length L1 required to clean the head unit 124 that many times is secured.

[0159] However, since it may be difficult to increase the gap between adjacent head units 124 in terms of design, for example, shaft members (guide means) 381 to 384 may be provided to make the movement path of the cleaning sheet 32 ​​between adjacent head units 124 V-shaped, as shown in Fig. 12. Furthermore, the number of shaft members may be increased to make the movement path W-shaped.

[0160] (4) Furthermore, if the path length of the cleaning sheet 32 ​​in the portion corresponding to the nozzle surface of the adjacent head unit 124 is set to be exactly a natural number multiple of the amount of take-up (movement) of the cleaning sheet 32 ​​required for each nozzle surface cleaning operation ("L3" or "G1" in Figure 11(a)), the unused portion of the cleaning sheet 32 ​​can be minimized, further contributing to reducing maintenance costs.

[0161] (5) Furthermore, a tension applying means may be provided to apply tension in the longitudinal direction to the cleaning sheet 32 ​​guided by the shaft members 321 to 326. This makes it difficult for kinks or wrinkles to occur in the portion of the cleaning sheet 32 ​​pressed against the nozzle surface of the head unit 124, increasing adhesion and improving the cleaning effect.

[0162] Such tension applying means may include a torque limiter attached to the rotation shaft of the supply roll 33 so that the supply roll 33 will not rotate unless a certain torque is applied, or a tension roller may be provided somewhere along the path of movement of the cleaning sheet 32 ​​and biased by an elastic material such as a spring in a direction that generates tension in the cleaning sheet 32.

[0163] Alternatively, a torque may be applied to the supply roll 33 by a motor in a rotation direction opposite to the direction in which the cleaning sheet 32 ​​is pulled out.

[0164] (6) In the above embodiment, the extension direction of the nozzle row in the head unit 124 and the movement direction of the cleaning sheet 32 ​​are perpendicular to each other. However, the directions do not necessarily have to be perpendicular to each other, and if they intersect, the width of the cleaning sheet 32 ​​used in one cleaning operation can be reduced to some extent.

[0165] (7) In the above embodiment, the corresponding nozzle surfaces of five head units 124 are simultaneously cleaned in a single cleaning operation. However, the head maintenance unit 200 may be configured to have separate drive sources for each part, so that the nozzle surfaces of each head unit 124 can be cleaned individually.

[0166] For example, if the operator determines that the image quality of a particular color has deteriorated, he or she can issue an instruction via the operation panel 160 or the like to perform cleaning of only the head unit 124 of that particular color, thereby avoiding unnecessary deep cleaning of the head units 124 of other colors, thereby saving ink and cleaning sheets.

[0167] (8) In the above embodiment, the width of the cleaning sheet 32 ​​is slightly larger than the length in the longitudinal direction of the head unit 124 that can be cleaned in one cleaning operation (see FIG. 11(a)).

[0168] However, by moving the head unit 124 in its longitudinal direction while the cleaning sheet 32 ​​is pressed by the pressing mechanism 36, it is also possible to clean the ink on the nozzle surface by wiping it off with the cleaning sheet 32, so in such cases it is not necessarily necessary to make the width of the cleaning sheet 32 ​​larger than the longitudinal length of the head unit 124 that can be cleaned in one cleaning operation.

[0169] (9) In the above embodiment, the nozzle surface cleaning unit 30 has been described as being installed in an inkjet image forming apparatus 1, but the present disclosure is not limited to this. If the apparatus is equipped with an ejection head that ejects liquid from a nozzle, applying the present disclosure will contribute to reducing maintenance costs associated with cleaning the nozzle surface of the ejection head.

[0170] (10) In the above embodiment, five head units 124 are provided to eject five colors of ink, but the number of colors is not limited to this and may be six or more, or in some cases, may be only one color.

[0171] Furthermore, if there are at least two head units 124 to be cleaned and they are arranged at an interval in the direction of movement of the cleaning sheet 32, the effect of reducing maintenance costs by the nozzle surface cleaning according to the present disclosure can be obtained.

[0172] (11) The above-described embodiments and modifications are merely examples of specific embodiments of the present disclosure, and should not be construed as limiting the technical scope of the present disclosure. The present disclosure can be embodied in various forms without departing from its gist or main features. [Industrial Applicability]

[0173] The present disclosure contributes to reducing the maintenance costs involved in head cleaning of devices that use ejection heads. [Explanation of symbols]

[0174] 1. Image forming device 20 Ink ejection section 25 Ink scraping unit 30 Nozzle surface cleaning unit (head cleaning device) 32 cleaning sheets 33 Supply roll (first roll) 34 Winding roll (second roll) 35 Drive unit 36 Pressing mechanism (pressing means) 37 Distance sensor (diameter detection means) 120 Image forming unit 124 Head unit (ejection head) 124c nozzle 150 control section 160 Operation Panel 170 Carriage movement mechanism 200 Head Maintenance Department 251 wiper blade 252 Actuator 321-326, 381-384 Shaft members (guide means) 1240 Carriage 1241~1248 Inkjet head 3672 Contact member 3675 compression spring

Claims

1. a long cleaning member that is disposed at an interval and that comes into contact with the nozzle surfaces of the first and second ejection heads, each of which has the first and second head arrays mounted thereon, and cleans the nozzle surfaces; a moving means for moving the cleaning member by a distance shorter than the length of a path from a portion of the nozzle surface of the first ejection head that has been cleaned in the previous cleaning to a portion of the nozzle surface of the second ejection head that has been cleaned in the previous cleaning, after the end of the previous cleaning and before the start of the next cleaning; a pressing means provided corresponding to each of the first and second ejection heads; a control unit for controlling each of the pressing means; Equipped with In each of the first and second ejection heads, the first head row and the second head row are arranged with a predetermined gap in the moving direction of the cleaning member, During cleaning, the control unit, while the cleaning member is stopped, drives each of the pressing means to switch between a first pressing state in which a first portion of the cleaning member corresponding to the nozzle face of the first head row of the corresponding ejection head is pressed against the nozzle face, and a second pressing state in which a second portion of the cleaning member corresponding to the nozzle face of the second head row of the corresponding ejection head is pressed against the nozzle face. A head cleaning device characterized by:

2. The direction in which the cleaning member is moved by the moving means is a direction that intersects with the direction in which the nozzle rows of the first and second ejection heads extend.

2. The head cleaning device according to claim 1.

3. 3. The head cleaning device according to claim 1, further comprising a tension applying means for applying tension to the cleaning member in the longitudinal direction thereof.

4. The pressing means is and elastic means for biasing the contact portion that contacts the cleaning member toward the cleaning member.

4. The head cleaning device according to claim 1, wherein the cleaning head is a cleaning head.

5. The pressing means corresponding to each of the first and second ejection heads can individually press the portions of the cleaning member corresponding to the nozzle faces of the first and second ejection heads.

5. The head cleaning device according to claim 1, wherein the head cleaning device is a head cleaning device.

6. The first and second ejection heads are used to eject inks of different colors.

6. The head cleaning device according to claim 1, wherein the head cleaning device is a head cleaning device.

7. The cleaning member is a strip-shaped sheet member, The moving means is a first roll around which a cleaning member is wound before use, a second roll for winding up a used cleaning member, and a driving means for driving the second roll to rotate; 7. The head cleaning device according to claim 1, further comprising:

8. a detection means for detecting the diameter of the cleaning member wound around the first roll or the diameter of the cleaning member wound around the second roll, The driving means adjusts the rotation amount of the second roll when the cleaning member is moved based on the diameter detected by the detecting means.

8. The head cleaning device according to claim 7.

9. The cleaning of the nozzle surfaces of the first and second ejection heads is performed simultaneously.

9. The head cleaning device according to claim 1, wherein the ink is a liquid.

10. a guide means for guiding the cleaning member so that the path of movement of the cleaning member between the first and second ejection heads is V-shaped or W-shaped; 10. The head cleaning device according to claim 1.

11. the first ejection head is located upstream of the second ejection head in the moving direction of the cleaning member, The length of the path of the cleaning member between the first discharge head and the second discharge head is at least N times (N is an integer of 2 or more) the width in the movement direction of the cleaning member required to clean the nozzle surface of the second discharge head in one cleaning operation.

11. The head cleaning device according to claim 1.

12. A head cleaning method for a head cleaning device including a long cleaning member that contacts and cleans nozzle surfaces of first and second ejection heads that are arranged at an interval and that each include a first and second head array, the method comprising: After the previous cleaning is completed and before the next cleaning is started, the cleaning member is moved by a distance shorter than the path length from the portion of the nozzle surface of the first ejection head that has been cleaned in the previous cleaning to the portion of the nozzle surface of the second ejection head that has been cleaned; the head cleaning device further includes a pressing means provided corresponding to each of the first and second ejection heads, In each of the first and second ejection heads, the first head row and the second head row are arranged with a predetermined gap in the moving direction of the cleaning member, During cleaning, while the cleaning member is stopped, each of the pressing means is driven to switch between a first pressing state in which a first portion of the cleaning member corresponding to the nozzle surface of the first head row in the corresponding ejection head is pressed against the nozzle surface, and a second pressing state in which a second portion of the cleaning member corresponding to the nozzle surface of the second head row in the corresponding ejection head is pressed against the nozzle surface. A head cleaning method comprising:

13. An image forming apparatus having an image forming unit that forms an image by ejecting ink from first and second ejection heads onto a recording sheet, and a head cleaning unit that cleans the nozzle surfaces of the first and second ejection heads, 12. An image forming apparatus, comprising the head cleaning device according to claim 1 as the head cleaning section.

Images