This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2020-054753 filed on Mar. 25, 2020, the entire contents of which are incorporated herein by reference.
The present disclosure relates to an inkjet recording apparatus.
There is known an inkjet recording apparatus in which a sheet is sucked and conveyed by a conveyance belt, and ink is discharged onto the sheet from a line type inkjet head including a plurality of nozzles arranged in a direction intersecting with a conveyance direction. The conveyance belt is provided with a plurality of through holes, and the sheet is sucked by absorption of air from the through holes. In this method, when ink adheres to the vicinity of the nozzles, there is a concern that the discharge direction and the discharge amount of the ink may change. Therefore, a function of cleaning the lower surface of the inkjet, head using a cleaning member having flexibility has been proposed.
For example, it has been proposed that a lower surface of an end portion thereinafter, referred to as a head end portion) of the inkjet head in a direction intersecting with the conveyance direction is inclined so as to become higher as a distance from a center of the inkjet head increases, thereby making recovery of deflection of the cleaning member gentle and suppressing scattering of ink. It has been proposed to supply a cleaning liquid to the cleaning member through the holes provided on the lower surface of the head end portion.
So as to solve the above-stated problem, according to the present disclosure, there is provided an ink jet, recording apparatus including: an endless conveyance belt including a plurality of through holes and wo und around a plurality of rollers; a conveyance plate including a plurality of recessed portions formed in an upper surface thereof and a plurality of through holes formed in bottom portions of the plurality of recessed portions, the upper surface being in contact with an inner peripheral surface of the conveyance belt; and a suction unit that sucks air from the plurality of through holes of the conveyance plate to suck a sheet to the conveyance belt. The inkjet recording apparatus also includes an inkjet head including a head main body having a lower surface on which a plurality of nozzles arranged in a width direction of the conveyance belt, intersecting the conveyance direction of the conveyance belt are formed, and a head end portion adjacent to one end or both ends of the head main body in the width direction, the inkjet head facing an upper surface of the conveyance plate via the conveyance belt; and a cleaning unit that removes ink attached to a lower surface of the head main body by bringing a cleaning member into contact with the lower surface of the head main body and sliding the cleaning member in the width direction, where a depth of the recessed portion in a facing region of the conveyance plate facing the head end portion is shallower than a depth of the recessed portion in a region other than the facing region.
Hereinafter, a printer 1 (inkjet recording apparatus) according to an embodiment of the present invention will be described with reference to the drawings.
First, the overall configuration of the printer 1 will be described with reference to
As shown in
An image forming unit 39 that forms an image on a sheet S is provided in a central portion inside the housing 10, a print conveyance unit 44 that conveys the sheet S on which an image is formed is provided below the image forming unit 33, and a drying conveyance unit 50 that dries the sheet S on which an image has been formed while conveying the sheet S is provided on the left side of the print conveyance unit 44.
A first conveyance path 21 extending from the sheet feeding cassette 15 to the print conveyance unit 44 and a manual feed conveyance path 24 extending from the manual feed tray 16 to the first conveyance path 21 are formed in a right side portion in the housing 10. A second conveyance path 22 extending from the drying conveyance unit 50 to the sheet discharge tray 17 is formed in a left side portion in the housing 10.
In the first conveyance path 21, a sheet feeding unit 18 and a pair of registration rollers 25 are provided in this order from the upstream side of the conveyance direction Y1. The sheet feeding unit 18 includes a roller to feed the sheets S accommodated in the sheet, feeding cassette 15 one by one to the first conveyance path 21.
The manual feed conveyance path 24 merges with the first conveyance path 21 between the sheet feeding unit 18 and the registration roller pair 25. The manual feed unit 19 includes rollers that feed the sheets S stacked on the manual feed tray 16 one by one to the manual feed conveyance path 24.
In the image forming unit 39, line-type inkjet heads 40Y, 40Bk, 40C, and 40M that eject inks of different colors are arranged in the conveyance direction Y2 of the sheet S. On the lower surfaces of the inkjet heads 40Y, 40Bk, 40C, and 40M, a large number of nozzles 41N arranged in the width direction X of the sheet 5 intersecting with the conveyance direction Y2 are formed. Inkjet heads 40Y, 40Bk, 40C, and 40M are arranged in this order from the upstream side of the Y2 in the conveyance direction, and eject yellow, black, cyan, and magenta inks, respectively.
The print conveyance unit 44 includes a driving roller 46a, a plurality of driven rollers 46b, 46c, 46d, and 46e, and a conveyance belt 45 wound around the driving roller 46a The driving roller 46a is driven by a driving source (not shown) such as a motor, so that the conveyance belt 45 is driven in the direction. A plurality of through holes are formed in the conveyance belt 45. A suction unit 47 that generates negative pressure in the through holes of the conveyance belt 45 by sucking air is provided an a position facing the image forming unit 35 inside the conveyance belt 45.
The drying conveyance unit 50 includes a driving roller 52a, a driven roller 52b, and a conveyance belt 51 wound around the driving roller 52a and the driven roller 52b. The conveyance belt 51 is driven in the direction Y3 by driving the driving roller 52a by a driving source such as a motor (not shown). Many through holes are formed in the conveyance belt 51. A suction unit 53 that generates a negative pressure in the through holes of the conveyance belt 51 by sucking art is provided in an upper portion on the inner side of the conveyance belt 51.
In the second conveyance path 22, a decurling device 54 and a sheet discharge unit 55 are provided in this order from the upstream side of the conveyance direction Y4. The decurling device 54 includes a belt wound around a plurality of rollers and a roller in contact with the belt, and is driven by a drive source (not illustrated) such as a motor. The sheet discharge unit 55 includes a roller for discharging a sheet S onto the sheet discharge tray 17 from the second conveyance path 22.
Each unit of the printer 1 is controlled by a control unit 2. The control unit 2 may be realized by software using a processor, or may be realized by a logic circuit (hardware) formed in an integrated circuit or the like. In the case of using a processor, various processes are performed by the processor reading and executing a program stored in a memory. As the processor, a central processing unit (CPU) is used, for example. The memory includes a storage medium such as a read only memory (ROM), a random access memory (RAM), and an electrically erasable programmable read only memory (EEPROM), and a control program used to control each unit of the printer 1 is stored in the memory.
Next, an outline of an image forming operation of the printer 1 will be described. When an image forming instruction is input to the printer 1, the sheet S is fed from the sheet feeding cassette 15 or the manual feed tray 16 and is conveyed in the Y1 direction along the first conveyance path 21. When the sheet S reaches the registration roller pair 25, the leading end portion (the end portion on the downstream side of the conveyance direction Y1) of the sheet 5 abuts against the nip region of the registration roller pair 25 that has stopped rotating, thereby correcting the skew of the sheet S, and the sheet S is sent to the print conveyance unit 44 in synchronization with the ink ejection timing of the image forming unit 39. The sheet S is attracted to the conveyance belt 45 by the negative pressure of the through holes of the conveyance belt 45, and is conveyed in the Y2 direction. Then, an image is formed on the sheet S by ejecting ink toward the sheet S from the inkjet heads 40Y, 40Bk, 40C, and 40M.
The sheet S on which the image has been formed is conveyed to the drying conveyance unit 30, is attracted to the conveyance belt 51 by the negative pressure of the through holes of the conveyance belt 51, and is conveyed in the Y3 direction, whereby the drying of the ink is promoted. Subsequently, the sheet S is conveyed to the decurling device 54, and is nipped and conveyed by the decurling device 54, whereby the curl is corrected. The sheet S is conveyed in the Y4 direction along the second conveyance path 22, and is discharged to the sheet discharge tray 37 by the sheet discharge unit 55.
Next, the configuration of each unit of the printer 1 will be described in detail with reference to
The printer 1 includes a conveyance belt 45, a conveyance plate 30, a suction unit 47, inkjet heads 40Y, 40Bk, 40C, and 40M, and a cleaning unit 60. The conveyance belt 45 is an endless belt having a plurality of through holes 45H and wound around a plurality of rollers. The conveyance plate 30 includes a plurality of recessed portions 31 formed in an upper surface thereof and a plurality of through holes 32 formed in bottom portions of the plurality of recessed portions 31, and the upper surface of the conveyance plate 30 contacts an inner peripheral surface of the conveyance belt 45. The suction unit 47 sucks air from the plurality of through holes 32 of the conveyance plate 30 to cause the conveyance belt 45 to suck the sheet S. Each of the inkjet heads 40Y, 40Bk, 40C, and 40M includes a head main body 41 having a lower surface formed with a plurality of nozzles 41N arranged in the width direction X of the conveyance belt 45 intersecting the conveyance direction Y2 of the conveyance belt 45, a head rear end 42 (an example of a head end) adjacent to a rear end of the head main body 41, and a head front end 43 (an example of a head end) adjacent to a front end of the head main body 41. The inkjet heads 40Y, 40Bk, 40C, and 40M face the upper surface of the conveyance plate 30 via the conveyance belt 45. The cleaning unit 60 removes the ink adhering to the lower surface of the head main body 41 by bringing a wiping blade 65 (an example of a cleaning member) into contact with the lower surface of the head main body 41 and sliding the wiping blade 65 in the width direction X. The depth of the recessed portion 31 in a facing region 33 facing the head rear end 42 and the head front end 43 of the conveying plate 30 is shallower than the depth of the recessed portion 31 in the region other than the facing region 33. A supply port 42N through which the cleaning liquid is supplied to the wiping blade 65 is provided on the lower surface of the head rear end 42. The lower surface of the head front end 43 is provided with an inclined portion 43S which is inclined so as to become higher as it goes away from the head main body 41. The conveyance belt 45, the conveyance plate 30, and the suction unit 47 are included in the print conveyance unit 44 described above.
[Conveyance Belt]
The conveyance belt 45 (see
[Conveyance Plate]
The conveyance plate 30 (see
[Suction Unit]
A suction unit 47 is provided below the conveyance plate 30 (see
[Elevating Mechanism]
The print conveyance unit 44 is provided with an elevating mechanism (not shown), which includes a rack and pinion, for example, and elevates the print conveyance unit 44 between a print conveyance position shown in
(Inkjet Head)
The inkjet heads 40Y, 40Bk, 40C, and 40M (see
The inkjet heads 40Y, 40Bk, 40C, and 40M (see
[Head Main Body]
The lower surface of the head mam body 41 includes a plurality of nozzle 41N arranged in the width direction X. The head main body 41 is connected to an ink container by a pipe, and ink contained in the ink container is supplied to the head main body 41 by a pump (not shown). The nozzle 41N includes, for example, a piezoelectric element (not shown), and the piezoelectric element, is deformed by application of a voltage, thereby to eject an ink.
The head rear end 42 includes a pipe 42P whose one end is connected to a tank (not shown) that stores the cleaning liquid, a storage portion 42R connected to the other end of the pipe 42P, and a supply port 42N that supplies the cleaning liquid. The lower surface of the head rear end 42 includes a bottom portion 42B and an inclined portion 42S formed on the rear side of the bottom portion 42B and inclined such that the rear side is higher than the front side. The bottom portion 42B is formed at substantially the same height as the lower surface of the head main body 41. The cleaning liquid is, for example, a liquid obtained by removing the coloring material from the ink, and is a liquid containing water and a solvent as main components. The storage portion 42R includes a porous member that stores the cleaning liquid. The supply port 42N is formed on the bottom portion 42B and is connected to the storage portion 42R.
The lower surface of the head front end 43 includes a bottom portion 43B and an inclined portion 43S formed on the front side of the bottom portion 43B and inclined such that the front side is higher than the rear side. The bottom portion 43B is formed at substantially the same height as the lower surface of the head main body 41.
The cleaning unit 60 (see
The first support member 63 is a rod-shaped member whose longitudinal direction is the conveyance direction Y2, and the second support member 64 is a rod-shaped member whose longitudinal direction is the width direction X. The three first support members 63 are disposed at the same interval as the interval of the head rear end 42 in the width direction X. Both end portions of the three first support members 63 are fixed to the two second support members 64. The wiping blades 65 are formed in four portions corresponding to the head rear ends 42 of the first support member 63. The wiping blade 65 is formed of urethane rubber, silicone rubber, or the like, has flexibility, and is provided so as to protrude upward from the upper surface of the first support member 63. The second support member 64 is connected to a drive mechanism (not illustrated) such as a rack and pinion, and the wiping unit 62 is driven in the width direction X by the drive mechanism.
The cleaning unit 60 includes a moving mechanism (not illustrated). The moving mechanism includes, for example, a frame that supports the ink receiving unit 61 and a rack and pinion that moves the frame in the horizontal direction. The frame supports the ink receiving unit 61 by a structure in which the ink receiving unit 61 can move up and down. The moving mechanism moves the cleaning unit 60 between a storage position illustrated in
Here, the operation of the cleaning unit 60 will be described with reference to
Next, the control unit 2 causes the drive mechanism to move the wiping unit 62 forward (in the X1 direction), whereupon the upper end portion of the wiping blade 65 comes into contact with the 42S of the inclined portion of the head rear end 42, and the wiping blade 65 slides forward while gradually flexing rearward Subsequently, the wiping blade 65 scrapes off the cleaning liquid hanging down in a dome shape from the supply port 42N at the bottom portion 42B of the head rear end 42 and slides forward.
Droplets of ink ejected from the nozzle 41N adhere to the lower surface of the head main body 41. The adhering ink is diluted by the cleaning liquid adhering to the wiping blade 65, and the wiping blade 65 slides forward while scraping off the diluted ink (see
Subsequently, the control unit 2 lowers the cleaning unit 60 to the facing position by lowering the print conveyance unit 44 by the elevating mechanism, returns the wiping unit 62 to the initial position by moving the wiping unit 62 rearward (in the X2 direction) by the driving mechanism, and moves the cleaning unit 60 to the storage position by the moving mechanism. Finally, the control unit 2 raises the print conveyance unit 44 to the print conveyance position by the elevating mechanism.
In the printer 1, in order to eliminate the clogging of the nozzle 41N which is clogged with the fixed ink or foreign matter, the ink may be pressurized by a pump or the like from the outside of the inkjet head 40Y, 40Bk, 40C, or 40M. In such a case, the pressurized ink is pushed out from the nozzle 41N and is accumulated on the lower surface of the head main body 41. The cleaning unit 60 not only scrapes off the droplets of the adhered ink but also scrapes off the ink thus accumulated.
Here, referring to
Hereinafter, the facing region 133 means a region facing the head rear end 42 and the head front end 43 on the upper surface of the conveyance plate 130. The upper surface of the conveyance plate 130 does not face the head rear end 42 and the head front end 43 except in the facing region 133. In the conventional conveyance plate 130, the ratio of the recessed portions 131 per unit area in the facing region 133 is equal to the ratio of the recessed portions 131 per unit area in the region other than the facing region 133.
Since the sheet S is conveyed to the conveyance belt 45 after its posture and timing are adjusted by the registration roller pair 25, the sheets S are conveyed with a gap between the sheets S. In a region on the conveyance belt 45 where the sheet S is placed, the sheet S is attracted to the conveyance belt 45 to close the through hole 45K. However, in the gap between the sheets S, an air flow passes through the through hole 45H downward, and thus the speed and direction of the air flow periodically change in a space between the inkjet heads 40Y, 40Bk, 40C, and 40M and the conveyance belt 45.
However, in the inkjet heads 40Y, 40Bk, 40C, and 40M, some of the cleaning liquid scraped off from the supply port 42N by the wiping blade 65 may adhere to the bottom portion 42B, and some of the ink scraped off from the lower surface of the head main body 41 by the wiping blade 65 or the mixture of the ink and the cleaning liquid that does not fall onto the ink receiving unit 61 but remains on the wiping blade 65 may adhere to the bottom portion 43B or the inclined portion 43S of the head front end 43. As the cleaning as repeated, the cleaning liquid, the ink, and the mixture thereof are gradually accumulated in the head rear end 42 and the head front end 43. Then, when the gap between the sheets S passes below the head rear end 42 and the head front end 43, the accumulated cleaning liquid, the ink, and the mixture thereof may fail onto the conveyance belt 45 due to the influence of the change in the airflow.
Therefore, in the conveyance plate 30 according to the present embodiment, the depth of the recessed portion 31 in a facing region 33 facing the head rear end 42 and the head front end 43 of the conveying plate 30 is shallower than the depth, of the recessed portion 31 in the region, other than the facing region 33.
To be more specific, as shown in
According to this configuration, in the facing region 33, the air flow flowing into the through hole 32 is smaller than that in the region other than the facing region 33, and thus a change in the air flow when the gap between the sheets S pauses below the head rear end 42 and the head front end 43 is suppressed. As a result, the cleaning liquid is suppressed from falling off from the head rear end 42 in the gap between the conveyed sheets S to the conveyance belt 45. In addition, ink is suppressed from falling off from the head front end 43 in the gap between the conveyed sheets S to the conveyance belt 45.
According to the printer 1 according to the embodiment described above, the liquid is suppressed from falling from the head end portions (the head rear end 42 and the head front end 43) to the conveyance belt 45 in the gap between the conveyed sheets S. According to the printer 1 according to the embodiment, since the inclined portion 41S which as inclined so as to become higher as it goes away from the head main body 41 is provided on the lower surface of the heed front end 43, scattering of the ink from the wiping blade 65 is suppressed. According to the printer 1 according to the present embodiment, since the supply port 42N which supplies the cleaning liquid to the wiping blade 65 is provided on the lower surface of the head rear end 42, removal of the ink adhered to the lower surface of the head main body 41 is promoted.
The above-described embodiment may be modified as follows.
In the example illustrated in
For convenience of description,
In the example shown in
In the example shown in
For convenience of explanation,
In the example illustrated in
In the example shown in
In the example shown in
In the example shown in
According to this configuration, in the facing region 33, the air flow flowing into the through hole 32 is smaller than that in the region other than the facing region 33, and thus a change in the air flow when the gap between the sheets S passes below the head rear end 42 and the head front end 43 is suppressed. As a result, the cleaning liquid is suppressed from falling off from the head rear end 42 in the gap between the conveyed sheets S to the conveyance belt 45. In addition, ink is suppressed from falling off from the head front end 43 in the gap between the conveyed sheets S to the conveyance belt 45.
In the examples shown in
In the embodiment described above, an example in which the pipe 42P, the storage portion 42R, and the supply port 42N are provided in the head rear end 42 is shown, but similar configurations may be provided in the head front end 43. In addition, similar configurations may be provided in both the head rear end 42 and the head front, end 43. According to this configuration, since the cleaning liquid can be supplied from both the head rear end 42 and the head front end 43, it is possible to remove the ink in both back and forth processes in the reciprocating strokes of the wiping blade 65.
In addition, in the above-described embodiment, since the mixture of the ink and the cleaning liquid adheres to the wiping blade 63 slid from the head rear end 42 to the head front end 43, the cleaning liquid may be supplied from the head front end 43 to remove the mixture. In any case, supplying the cleaning liquid from both the head rear end 42 and the head front end 43 increases the possibility that the ink, the cleaning liquid, or the mixture thereof drops from both the head rear end 42 and the head front end 43. Therefore, it is more necessary to make the ratio of the recessed portion 31 per unit area in the facing region 33 smaller than the ratio of the recessed portion 31 per unit area in the region other than the facing region 33.
In the embodiment described above, an example is shown in which the bottom portion 42B and the inclined portion 42S are provided on the lower surface of the head rear end 42, but the inclined portion 42S may not be provided on the lower surface of the head front end 43. In the embodiment described above, an example is shown in which the bottom portion 43B and the inclined portion 43S are provided on the lower surface of the head rear end 42, but the inclined portion 43S may not be provided on the lower surface of the head front end 43.
In the above-described embodiment, an example in which the recessed portion 31 has a groove shape whose longitudinal direction is the conveyance direction Y2 has been described. However, the shape of the recessed portion 31 may be any shape such as a rectangle or an ellipse when viewed from above.
Number | Date | Country | Kind |
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2020-054753 | Mar 2020 | JP | national |