JP6098384B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection apparatus.

  Patent Document 1 discloses an ink jet printer as a liquid ejecting apparatus. This printer includes an inkjet head having a plurality of nozzles arranged in the width direction (main scanning direction) of the recording paper to be conveyed, paper dust and thickened ink attached to the ink ejection surface (nozzle surface) of the inkjet head, etc. Maintenance unit that removes foreign matter.

  The maintenance unit has a wiping member (wiper) that moves in contact with the ink ejection surface of the inkjet head. The maintenance unit removes foreign matters such as paper dust and thickened ink from the ink discharge surface by causing the wiping member to wipe the ink discharge surface of the inkjet head. Moreover, in this patent document 1, before wiping off by a wiping member, ink is discharged toward the wiping member from the nozzle of an inkjet head, and ink is made to adhere to a wiping member. As a result, the friction between the wiping member and the ink discharge surface when wiping the ink discharge surface is reduced, and the ink discharge surface is prevented from being damaged by the friction.

JP 2010-46815 A

  In Patent Document 1, the wiping member wipes the ink ejection surface during maintenance for eliminating nozzle ejection defects. Therefore, when wiping off, there is a high possibility that some nozzles have ejection failure. Therefore, before the ink discharge surface is wiped off, it is possible that a discharge failure has occurred sufficiently in the nozzle for wetting the wiping member with ink. In that case, it is conceivable that ink hardly adheres to the wiping member and the wiping member is not sufficiently wetted with ink. If wiping is performed in this state, the ink discharge surface may be damaged by friction. In addition, there is a problem that ink mist is scattered around due to ejection of ink from a defectively ejected nozzle.

  An object of the present invention is to prevent liquid from being ejected from a nozzle with poor ejection when the wiping member is wetted with liquid before wiping the liquid ejection surface.

According to a first aspect of the present invention, there is provided a liquid discharge apparatus having a liquid discharge surface on which a plurality of nozzles are formed, a wiping member for wiping the liquid discharge surface of the liquid discharge head, and the wiping member being the liquid discharge head Driving means for moving at least one of the wiping member and the liquid discharge head so as to move along a direction parallel to the liquid discharge surface, and control for controlling the liquid discharge head and the drive means Means, and
The control unit determines whether or not at least some of the plurality of nozzles are in a state in which ejection failure may occur, and controls the liquid ejection head to perform the determination process. In this case, liquid is discharged from the nozzle that is determined not to cause the discharge failure to the wiping member, and the wiping member is wetted. And a wiping process for wiping the liquid ejection surface with the wiping member in a wet state.

  In the present invention, “in a state where ejection failure can occur” is not limited to a state in which ejection failure occurs without fail when ink is ejected from a nozzle, and is ejected once every time. This includes a state where a defect may occur.

  According to the present invention, in the wetting process performed before the wiping process, the liquid is ejected from the nozzle of the liquid ejection head toward the wiping member, and the wiping member is wetted with the liquid, so that the ink at the time of wiping can be obtained. Friction between the discharge surface and the wiping member can be reduced. Further, in the wetting process, the liquid is ejected from the nozzles that are determined not to be in a state where ejection failure may occur in the determination process to the wiping member. Thereby, the wiping member can be reliably wetted with the liquid, and damage to the liquid discharge surface due to friction can be more effectively prevented. In addition, since liquid is not discharged from a nozzle with poor discharge, it is possible to prevent generation of liquid mist.

The liquid ejection apparatus according to a second aspect has a position changing means for changing a position of the wiping member relative to the liquid ejection head in a direction orthogonal to the liquid ejection surface in the first invention,
In the wetting process, the control means controls the position changing means and the driving means so that the wiping member is not in a state where the ejection failure may occur without contacting the liquid ejection surface. The liquid is discharged from the nozzle to the wiping member after moving to a position facing the determined nozzle, and in the wiping process, the position changing unit and the driving unit are controlled to control the wiping member. The liquid ejection surface is wiped by moving the liquid ejection surface in contact with the liquid ejection surface.

  In the present invention, during the wetting process, the wiping member moves with respect to the liquid ejection surface without contacting the liquid ejection surface. That is, since the wiping member in a state before being wet with the liquid does not rub against the liquid discharge surface, the liquid discharge surface is not damaged.

  The liquid ejection device according to a third aspect is the liquid ejection device according to the second aspect, wherein the control means includes the plurality of liquid ejection surfaces in a state where the wiping member is not in contact with the liquid ejection surface after the wetting process. The wiping process is performed after the nozzle is moved to a position outside the nozzle arrangement region.

  In the wetting process, after the liquid is discharged from the nozzle onto the wiping member and wetted, when the wiping member is brought into contact with the liquid discharge surface as it is, the wiping member is placed on the liquid discharge surface in the region where the nozzle is formed on the liquid discharge surface. It is conceivable that it is struck in the direction that intersects with. In that case, there is a possibility that the meniscus of the nozzle is broken and liquid flows out, or air is mixed into the nozzle. In the present invention, after wetting the wiping member in the wetting process, the wiping member is temporarily moved to the outside of the formation area of the plurality of nozzles without contacting the liquid ejection surface, and then brought into contact with the liquid ejection surface. Let it wipe. Therefore, the meniscus of the nozzle is not destroyed when the wiping member is brought into contact with the liquid discharge surface.

  Here, in the determination process, the determination as to whether or not a discharge failure may occur may be performed by actually inspecting whether a discharge failure has occurred using an inspection device or the like. As described above, the determination may be made by estimation based on the usage frequency of the nozzles. That is, in the determination process, the control unit may determine whether or not the nozzle is in a state in which a discharge failure may occur based on the number of times the liquid is discharged within a certain period of time (No. 1). Invention of 4). Alternatively, in the determination process, the control unit may determine whether or not the nozzle is in a state where an ejection failure may occur based on an elapsed time from the previous liquid ejection of each nozzle (first). 5 invention).

  In the determination process, the control unit refers to the temperature detected by the temperature detection unit to determine whether or not ejection failure may occur in each of the at least some of the nozzles. It is also possible (sixth invention). Alternatively, the control unit may determine whether or not ejection failure occurs in each of the at least some of the nozzles with reference to the humidity detected by the humidity detection unit in the determination process. Good (seventh invention).

  Thus, in the determination process, the determination accuracy is increased by referring to the temperature information or the humidity information around the liquid ejection head. For example, it is possible to prevent erroneous determination that the nozzle is not in a state in which ejection failure may occur even though the liquid is thickened.

  According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the control means controls the liquid discharge head after the wiping process, so that the liquid is discharged from the plurality of nozzles. In addition, the control unit is not in a state in which the ejection failure may occur in the nozzle that is determined in the determination process to be in a state where the ejection failure may occur. The flushing amount is larger than that of the nozzle determined to be.

  In the present invention, it is possible to reliably eliminate the ejection failure by increasing the flushing amount for the nozzle that is determined to be in a state where the ejection failure may occur in the determination process.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the liquid discharge device on which the liquid discharged from the liquid discharge head lands is disposed on the liquid discharge head. A transport unit configured to transport in a transport direction parallel to the discharge surface, wherein the plurality of nozzles of the liquid discharge head are arranged along a nozzle arrangement direction intersecting the transport direction on the liquid discharge surface; A plurality of nozzle rows extending in the nozzle arrangement direction and arranged along the transport direction are formed on the liquid ejection surface,
In the determination process, the control means determines whether or not ejection failure may occur only for nozzles belonging to a part of the plurality of nozzle rows, and for nozzles belonging to the remaining nozzle rows Is characterized in that it is estimated whether or not the ejection failure is likely to occur based on the determination result for the nozzles belonging to the partial nozzle row.

  When the liquid ejection head has a plurality of nozzle rows, nozzles that are close to each other in the nozzle arrangement direction between different nozzle rows are likely to have the same conditions regarding ejection failure. That is, in a group of nozzles present at positions close to each other in the nozzle arrangement direction, the nozzle discharge timing, the discharge frequency, and the like are often similar, and the temperature and humidity conditions around the nozzles are also close. Therefore, in the present invention, in the determination process, only the nozzles belonging to a part of the nozzle arrays are determined, and whether the nozzles belonging to the other nozzle arrays are in a state where ejection failure may occur based on the determination result. presume. As described above, the determination process can be simplified by determining the ejection failure only for a part of the nozzle rows.

According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the liquid discharge device on which the liquid discharged from the liquid discharge head lands is disposed on the liquid discharge head. A transport unit configured to transport in a transport direction parallel to the discharge surface, wherein the plurality of nozzles of the liquid discharge head are arranged along a nozzle arrangement direction intersecting the transport direction on the liquid discharge surface; A nozzle array extending in the nozzle array direction is formed on the liquid discharge surface, and among the nozzles belonging to the nozzle array, the end side nozzle located on the end side of the nozzle array is the nozzle array of the discharge target body A nozzle that discharges liquid toward an edge in a direction,
The control means controls the liquid discharge head and the transport means, and discharges liquid from only the nozzles of the nozzle row except the end-side nozzles toward the discharge target body. And a second liquid ejection process in which liquid is ejected from all nozzles of the nozzle row including the end-side nozzles toward the body to be ejected.
Furthermore, the control means is characterized in that, in the determination process, the end side nozzle is set to a nozzle in a state where the ejection failure may occur.

  Since the end side nozzle that discharges the liquid to the edge of the discharge target body is used only in the second liquid discharge process, discharge failure is more likely to occur than the other nozzles. Therefore, in the present invention, the end-side nozzles are set to nozzles that are in a state where unsatisfactory ejection failure may occur unconditionally, without determining ejection failure individually. Therefore, the end nozzle is not always used during the wetting process. Thus, the determination process can be simplified by omitting the determination of the ejection failure for the end nozzle.

  According to the present invention, in the wetting process executed before the wiping process, the liquid is ejected from the nozzle that is determined not to be in a state where ejection failure may occur in the determination process to the wiping member. Thereby, the wiping member can be reliably wetted with the liquid, and damage to the liquid discharge surface due to friction can be more effectively prevented. In addition, since liquid is not discharged from a nozzle with poor discharge, it is possible to prevent occurrence of liquid mist.

1 is a plan view illustrating a schematic configuration of a printer according to an embodiment. It is the II-II arrow directional view of FIG. FIG. 2 is a block diagram schematically illustrating an electrical configuration of a printer. It is a figure which shows the printer at the time of purge or flushing. It is a figure which shows the printer at the time of wiping off the ink discharge surface by a wiping apparatus. It is a flowchart of a series of processes including the wiping process for a foreign material removal. It is a figure explaining a judgment process and a wetting process. It is a figure explaining the wiping off process for a foreign material removal. It is a top view of the printer which concerns on a change form. It is a top view of the printer which concerns on another modification. It is a perspective view of the front-end | tip part of a wiping off member.

  Next, an embodiment of the present invention will be described. The present embodiment is an example in which the present invention is applied to an ink jet printer that records an image or the like by ejecting ink onto a recording sheet conveyed in a predetermined conveyance direction. FIG. 1 is a schematic plan view of the printer of this embodiment. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 is a block diagram schematically showing an electrical configuration of the printer. 1 is defined as the front-rear direction of the printer 1, the left-right direction in FIG. 1 is defined as the left-right direction of the printer 1, and the vertical direction in FIG. 1 is defined as the up-down direction of the printer 1 (the front side of the page is upward). In the following, description will be made using direction words such as front and rear, left and right, and up and down as appropriate.

(Schematic configuration of the printer)
As shown in FIGS. 1 to 3, the printer 1 includes a platen 2, an inkjet head 3, two transport rollers 4, 5, a purge pump 6, an ink receiving member 7, a wiping unit 8, and a control device. 9 etc.

  The platen 2 has two plate-like members 2a and 2b arranged in the front-rear direction. The two plate-like members 2a and 2b are respectively driven by an opening / closing mechanism (not shown) so as to be able to take a horizontal posture and a turning posture that is rotated downward with respect to the horizontal posture such as a double opening. It is configured. As shown in FIGS. 1 and 2, when the two plate-like members 2a and 2b are respectively in a horizontal position, the ink is discharged from the inkjet head 3 described below onto the upper surfaces of the two plate-like members 2a and 2b. The recording paper 100 (the ejected body of the present invention) on which the ink thus deposited is placed is placed. The wiping unit 8 and the ink receiving member 7 are accommodated in the space below the platen 2.

  The inkjet head 3 (the liquid discharge head of the present invention) is a line-type head that is long in the paper width direction. The ink jet head 3 is connected to an ink tank (not shown), and ink is supplied from the ink tank. A plurality of nozzles 10 arranged along the longitudinal direction (paper width direction) of the inkjet head 3 are formed on the lower surface of the inkjet head 3. The plurality of nozzles 10 constitute two nozzle rows 11 a and 11 b that extend in the paper width direction and are arranged in a direction perpendicular to the paper width direction (the conveyance direction of the recording paper 100). Hereinafter, the lower surface of the inkjet head 3 on which the plurality of nozzles 10 are formed is referred to as an ink ejection surface 3a (liquid ejection surface of the present invention). The ink jet head 3 can be moved up and down with respect to the platen 2 by being driven by a head lifting mechanism (not shown). In this embodiment, the arrangement direction of the nozzles 10 is parallel to the paper width direction and is orthogonal to the conveyance direction of the recording paper 100, but the arrangement direction of the nozzles 10 and the conveyance direction are different from 90 degrees. You may cross at an angle.

  The two transport rollers 4 and 5 are arranged so as to sandwich the inkjet head 3 in the transport direction. These two transport rollers 4 and 5 are rotationally driven in synchronization by a transport motor 12 (see FIG. 3), and transport the recording paper 100 in the transport direction.

  The inkjet head 3 ejects ink from the plurality of nozzles 10 on the ink ejection surface 3a to the recording paper 100 conveyed in the conveyance direction by the two conveyance rollers 4 and 5, respectively. Print text and images.

  As shown in FIG. 2, the purge pump 6 is disposed between the inkjet head 3 and an ink tank (not shown). The purge pump 6 pressurizes the ink from the ink tank and supplies the ink to the inkjet head 3, thereby forcibly discharging the ink by pushing it out from the plurality of nozzles 10 of the inkjet head 3. The operation of discharging ink from the plurality of nozzles 10 by the purge pump 6 is hereinafter referred to as purge. By performing this purge, foreign matter or air mixed in the ink jet head 3 or ink thickened by drying is discharged from the nozzle 10, so that the ejection failure of the nozzle 10 is resolved or the ejection failure. Occurrence prevention is possible.

  The ink receiving member 7 is for receiving the waste ink discharged from the inkjet head 3 by the flushing that discharges ink from a plurality of nozzles for the purpose of purging or preventing drying. The ink receiving member 7 is a plate-like member made of glass or the like. The ink receiving member 7 is driven by an ink receiving elevating mechanism (not shown) and can be moved up and down.

  FIG. 4 is a diagram illustrating the printer at the time of purging or flushing. In the state of FIG. 2 in which the two plate-like members 2 a and 2 b are in a horizontal posture, the ink receiving member 7 stands by at a position further below the wiping unit 8 in a space below the platen 2. When purging or flushing is performed, first, the two plate-like members 2a and 2b of the platen 2 are rotated in a double-open manner, and the ink receiving member 7 is exposed. Next, the ink receiving member 7 is driven upward by an ink receiving elevating mechanism (not shown), and moves from the position shown in FIG. 2 to a position above the wiping unit 8 shown in FIG. At this time, as shown in FIG. 4, the inkjet head 3 is driven downward by a head lifting mechanism (not shown) and lowered. As a result, the ink receiving member 7 is positioned directly below the ink ejection surface 3 a of the inkjet head 3. In this state, purging and flushing are performed, and the ink discharged from the plurality of nozzles 10 of the inkjet head 3 is collected by the ink receiving member 7.

  As shown in FIGS. 1 and 2, the wiping unit 8 includes a wiping device 13 and a wiping drive mechanism 14 that moves the wiping device 13 in the paper width direction parallel to the ink discharge surface 3a. As shown in FIG. 2, the wiping unit 8 is disposed below the platen 2. Unlike the inkjet head 3 and the ink receiving member 7, the wiping unit 8 is fixedly provided on the casing 1a (see FIG. 1) of the printer 1 and does not move in the vertical direction.

  The wiping device 13 wipes the ink ejection surface 3a of the inkjet head 3 while moving in the paper width direction. When the purge is performed by the purge pump 6 in order to eliminate the ejection failure of the nozzle 10 or prevent the ejection failure, a part of the ink discharged from the nozzle 10 adheres to the ink ejection surface 3a. Therefore, the ink discharge surface 3a is wiped by the wiping device 13 to remove the ink. In addition, when foreign matter is attached near the nozzle 10, this foreign matter also causes ejection failure of the nozzle 10. Examples of the foreign matter adhering to the ink discharge surface 3a include paper dust (paper fiber) stuck into the nozzle 10 of the ink discharge surface 3a, solidified ink fixed to the ink discharge surface 3a, and the like. By wiping the ink discharge surface 3a by the wiping device 13, the foreign matter as described above is removed from the ink discharge surface 3a.

  FIG. 5 is a diagram illustrating the printer when the ink discharge surface is wiped by the wiping device 13. When the ink discharge surface 3a is wiped by the wiping device 13 after the purging shown in FIG. 4, the ink receiving member 7 is driven downward by an ink receiving drive mechanism (not shown) as shown in FIG. Return to a position below the wiping unit 8.

  The wiping device 13 includes a wiping member 15, a holding member 16 that holds the wiping member 15, and an elevating motor 17 that moves the wiping member 15 up and down (position changing means of the present invention).

  The wiping member 15 is a plate-like member formed of a material having elasticity such as rubber. The holding member 16 holds the wiping member 15 in a posture inclined at a predetermined angle to the right with respect to the vertical direction. The elevating motor 17 is accommodated in the holding member 16. The lift motor 17 drives the wiping member 15 up and down. The position of the wiping member 15 relative to the inkjet head 3 in the vertical direction orthogonal to the ink discharge surface 3a can be changed by the lifting motor 17.

  In addition, as a configuration for changing the position of the wiping member 15 in the vertical direction with respect to the ink ejection surface 3a, in addition to the configuration in which the wiping member 15 is moved up and down by the lifting motor 17 described above, a configuration in which the wiping device 13 is moved up and down, A configuration in which the entire wiping unit 8 is moved up and down can also be employed. Further, the wiping member 15 may be moved up and down relatively with respect to the ink ejection surface 3a by moving the inkjet head 3 up and down by a head lifting mechanism (not shown).

  As shown in FIGS. 1, 2, 5, etc., the wiping drive mechanism 14 includes a wiping drive motor 19 (driving means of the present invention), and a belt 22 connected to the wiping drive motor 19 via pulleys 20 and 21. And two guide rails 23 extending in the paper width direction. The belt 22 is connected to the holding member 16. As shown in FIG. 1, the two guide rails 23 are disposed on both front and rear sides of the holding member 16, and the front end portion and the rear end portion of the holding member 16 can slide on the two guide rails 23, respectively. Is attached. When the belt 22 is driven by the wiping drive motor 19, the wiping device 13 moves in the paper width direction while being guided by the two guide rails 23. Further, by switching the rotation direction of the wiping drive motor 19, the wiping device 13 can be moved in two directions, left and right.

  In addition, the structure which moves the wiping apparatus 13 is not restricted to the structure of FIG. For example, a screw shaft extending in the paper width direction is screwed to the holding member 16, and the screw shaft is rotationally driven by a wiping drive motor 19 so that the wiping device 13 moves in the paper width direction. Also good.

  As shown in FIGS. 1 and 2, the wiping device 13 stands by at a position on the right side of the ink jet head 3 when the ink ejection surface 3 a is not wiped. On the other hand, when wiping the ink discharge surface 3a, the wiping device 13 is driven in the paper width direction by being driven by the wiping drive mechanism 14 with the plate-like members 2a and 2b of the platen 2 opened as shown in FIG. Moving. At this time, the wiping member 15 moves with respect to the ink ejection surface 3a in a state where the tip of the wiping member 15 is in contact with the ink ejection surface 3a, thereby wiping off ink and foreign matter adhering to the ink ejection surface 3a.

  As shown in FIG. 3, the control device 9 includes a CPU (Central Processing Unit) 30, a ROM (Read Only Memory) 31, a RAM (Random Access Memory) 32, and an ASIC (Application Specific Integrated Circuit) including various control circuits. 33 etc. are provided. The control device 9 is connected to the inkjet head 3, the transport motor 12, the purge pump 6, the wiping drive motor 19, the lifting motor 17, and the like. Further, the control device 9 includes a temperature sensor 37 (temperature detecting means of the present invention) for detecting the temperature (environmental temperature) in the casing 1a of the printer 1, and the humidity (environmental humidity) in the casing 1a of the printer 1. Is connected to a humidity sensor 38 (humidity detection means of the present invention). Further, an operation panel 34, an external device PC 35, and the like are connected to the control device 9.

  The control device 9 (the control means of the present invention) causes the CPU 30 and the ASIC 33 to execute various processes according to the program stored in the ROM 31. For example, the control device 9 controls the inkjet head 3 and the conveyance motor 12 based on the print command transmitted from the PC 35 to print an image or the like on the recording paper 100. Further, the purge pump 6 is controlled to purge the inkjet head 3. Further, the wiping drive motor 19 and the lifting / lowering motor 17 are controlled to cause the wiping device 13 to wipe the ink discharge surface 3a of the inkjet head 3, thereby removing ink and foreign matter adhering to the ink discharge surface 3a. Although not shown, the control device 9 opens and closes an opening / closing mechanism that rotates the plate-like members 2a and 2b (see FIG. 1) of the platen 2, a head lifting mechanism that lifts and lowers the inkjet head 3, and an ink receiving member 7. The operation of the operation unit such as a motor is also controlled for each of the ink receiving and raising mechanisms to be moved.

  In the above description, the control device 9 performs various processing by the CPU 30 and the ASIC 33. However, the present invention is not limited to this, and the control device 9 may be realized by any hardware configuration. For example, the processing may be performed by only the CPU or only the ASIC. The functions may be shared by two or more CPUs or two or more ASICs.

  Next, the wiping of the ink discharge surface 3a by the wiping device 13 will be described in detail. The wiping of the ink discharge surface 3a of the wiping device 13 is mainly performed when removing ink adhering to the ink discharge surface 3a after purging and when removing foreign matter adhering to the ink discharge surface 3a. .

(1) Wiping off ink after purging First, wiping off ink adhering to the ink ejection surface 3a after purging will be briefly described. After purging, some of the ink discharged from the plurality of nozzles 10 adheres to the ink discharge surface 3a. Therefore, the control device 9 controls the wiping drive motor 19 to cause the wiping device 13 to wipe off ink adhering to the ink discharge surface 3a. Specifically, as shown in FIG. 5, the wiping drive motor 19 is controlled so that the wiping device 13 is in a state where the position of the tip of the wiping member 15 is above the plane including the ink discharge surface 3 a. Move to the left. As a result, the tip of the wiping member 15 is pressed against the ink ejection surface 3a while being bent, and the ink adhering to the ink ejection surface 3a is wiped off.

(2) Wiping for removing foreign matter Next, wiping for removing the foreign matter attached to the ink ejection surface 3a will be described in detail. FIG. 6 is a flowchart of a series of processes including a wiping process for removing foreign substances. In FIG. 6, Si (i = 10, 11, 12,...) Indicates a step number.

  The flow of FIG. 6 is always executed while the power of the printer 1 is turned on, and is waiting in a state waiting for input of a wiping command (S10). When the image printed on the recording paper 100 is faint or the like, a command for wiping off the foreign matter on the ink ejection surface 3a in order to eliminate the ejection failure by the user operating the operation panel 34 is given to the control device 9. When input (S10: Yes), the control device 9 executes various processes including a wiping process (S13) for removing foreign matter.

  Although FIG. 6 shows an example in which the wiping process is executed when a wiping command is input by the user, the wiping process may be executed at a timing other than this. For example, the foreign substance may be wiped off periodically after a certain period of time. That is, when a predetermined period has elapsed since the previous wiping process was performed, the control device 9 determines that the nozzle 10 is in a situation where ejection failure may occur, and executes the wiping process. In addition, the purge is performed because the user has input a command for eliminating the discharge failure. However, even if the purge is performed, the discharge failure is not resolved, and the user may repeatedly input the same command. In such a case, the control device 9 may determine that the ejection failure is caused by a foreign matter such as paper dust attached to the ink ejection surface 3a, and execute a wiping process for removing the foreign matter. .

  By the way, in the wiping for removing the foreign matter, unlike the wiping after the purging described above, the ink does not adhere to the ink discharge surface 3a. Therefore, if the ink discharge surface 3a is wiped as it is with the dry wiping member 15, the ink discharge surface 3a may be damaged due to the large friction between them. Therefore, in this embodiment, in order to reduce friction, the wiping member 15 is reliably wetted with ink in advance, and then the ink discharge surface 3a is wiped off.

  Specifically, as illustrated in FIG. 6, the control device 9 performs a determination process (S11) and a wetting process (S12) before the wiping process (S13). FIG. 7 is a diagram illustrating the determination process and the wetting process. In the wetting process of S <b> 12, the wiping member 15 is wetted with ink by ejecting ink from the nozzle 10 of the inkjet head 3 toward the wiping member 15.

  However, if the nozzle 10 that discharges ink in the wetting process is a nozzle that has failed to discharge, no ink is discharged from the nozzle 10 or the discharge direction is bent even if ink is discharged. Sometimes. In that case, ink droplets hardly land on the wiping member 15, and the wiping member 15 may not be sufficiently wetted with ink. Further, in the nozzle 10 in which ejection failure has occurred, the ink may be dispersed and ejected in a fine mist form. In this case, the ink mist is scattered around the inkjet head 3 by performing the wetting process. Therefore, as shown in FIG. 6, in order to avoid using the defective nozzle 10 in the wetting process, prior to the wetting process (S <b> 12), it is determined whether or not there is a possibility of defective ejection for each nozzle 10 of the inkjet head 3. A determination process (S11) is performed.

(Determination process)
As described above, in the determination process, it is individually determined whether or not each nozzle 10 is in a state where ejection failure can occur. Although determination may be performed for all the nozzles 10 of the inkjet head 3, determination may be performed only for some of the nozzles 10 that can be used in the subsequent wetting process. Specifically, as shown in FIG. 7, among the plurality of nozzles 10 of the inkjet head 3, the determination regarding ejection failure is performed individually for the nozzles 10 located in the range A in the paper width direction (nozzle arrangement direction). .

  In the present embodiment, whether or not ejection failure is likely to occur is determined as follows. There is a possibility that the viscosity of the ink in the nozzle 10 is increased as the use frequency (ejection frequency) of the nozzle 10 is lower or as the time during which ink is not ejected is longer. In addition, there is a high possibility that air and foreign matter stay in the nozzle 10 and the ink flow path communicating with the nozzle 10. That is, it can be said that there is a high possibility that the nozzle 10 that is not used frequently and has a long time during which ink is not ejected is defective in ejection. Therefore, it is estimated whether or not each nozzle 10 is in a state where ejection failure may occur based on the usage frequency or the like.

  For example, the ejection failure may be determined for each nozzle 10 based on the number of ink ejections within a certain period. The control device 9 counts the number of ejections of each nozzle 10 during printing on a predetermined number of recording sheets 100, and the nozzles whose ejection number is less than a predetermined threshold are in a state where ejection failure may occur. 10 is determined.

  Alternatively, the ejection failure may be determined for each nozzle 10 based on the elapsed time since the previous ink ejection (that is, the time during which no ink is ejected). For example, the control device 9 measures the elapsed time from the previous ink discharge for each nozzle 10, and the nozzle 10 whose elapsed time exceeds a predetermined threshold is a nozzle that is in a state where ejection failure may occur. Judge that there is.

  Further, in this determination processing, the ambient temperature around the inkjet head 3 detected by the temperature sensor 37 (see FIG. 3) and the ambient humidity around the inkjet head 3 detected by the humidity sensor 38 (see FIG. 3). The above determination may be made with reference to at least one of them. The higher the environmental temperature and the lower the environmental humidity, the easier the ink thickening in each nozzle 10 proceeds. Therefore, for example, the determination threshold based on the number of ejections or the determination threshold based on elapsed time may be changed according to the temperature detected by the temperature sensor 37 or the humidity detected by the humidity sensor 38. . Thus, in the determination process, the determination accuracy is increased by referring to the temperature information or the humidity information around the inkjet head 3. For example, it is possible to prevent erroneous determination that the ink is not thick enough to cause an ejection failure even though the thickening of the ink in the nozzle 10 has progressed considerably because the environmental temperature is considerably high.

  Note that, as described above, in the determination process, whether each nozzle 10 is likely to cause a discharge failure is determined by estimation based on the usage frequency and the like. It is not determined whether or not ejection failure occurs. In other words, in the present embodiment, the “state in which the nozzle 10 may cause a discharge failure” is not limited to a state in which a discharge failure always occurs when ink is discharged from the nozzle 10. In addition, it includes a state where a discharge failure may occur once.

(Wetting treatment)
In the wetting process, ink is ejected from the nozzle 10 of the inkjet head 3 toward the wiping member 15, and the wiping member 15 is wetted with ink. First, as shown in FIG. 7, the control device 9 controls the elevating motor 17 to lower the wiping member 15 so that the tip of the wiping member 15 is located below the plane including the ink ejection surface 3 a. Let Next, the control device 9 controls the wiping drive motor 19 to cause the wiping device 13 to move the nozzle 10 within the range A of the inkjet head 3 (particularly in a state where ejection failure may occur in the previous determination process). The nozzle is moved to a position facing the nozzle determined not to be present. At this time, the wiping member 15 moves with respect to the ink ejection surface 3a in a state where the tip portion thereof does not contact the ink ejection surface 3a. That is, since the wiping member 15 in a state before being wet with ink does not rub against the ink ejection surface 3a, the ink ejection surface 3a is not damaged.

  In this state, ink is ejected from the nozzles 10 in the range A, and the wiping member 15 is wetted with ink. At this time, ink is ejected only from the nozzles 10 that are determined not to be nozzles 10 that are in a state in which ejection failure may occur in the determination process, among the plurality of nozzles 10 positioned within the range A. For example, in the determination process, when it is determined that one nozzle 10A located within the range A in FIG. 7 is in a state where ejection failure may occur, ink is ejected from the nozzle 10A in the wetting process. I won't let you.

  As described above, since the ink is ejected from the nozzle 10 that is determined not to cause ejection failure in the determination process to the wiping member 15, the wiping member 15 can be reliably wetted with ink. Further, since ink is not ejected from the ejection failure nozzle 10, the occurrence of ink mist is prevented.

  In FIG. 7, the ink is ejected from the plurality of nozzles 10 in the range A to the wiping member 15 while moving the wiping device 13 in the range A. On the other hand, the ink may be ejected from the nozzle 10 while the wiping device 13 is stopped within the range A. In that case, the wiping member 15 is positioned directly below the nozzle 10 in the range A, which is determined not to be in a state where ejection failure may occur.

(Wiping process)
FIG. 8 is a diagram illustrating a wiping process for removing foreign matter. After the wiping member 15 is wetted with ink by the wetting process, if the wiping member 15 is brought into contact with the ink ejection surface 3a for wiping the ink ejection surface 3a, depending on the position at the end of the wetting process, the wiping member 15 may be abutted in the vertical direction with respect to the region where the nozzle 10 of the ink ejection surface is formed. At this time, there is a possibility that the meniscus of the nozzle 10 is destroyed and ink flows out, or air is mixed into the nozzle 10.

  Therefore, before starting wiping by the wiping member 15, the control device 9 controls the wiping drive motor 19 to move the wiping device 13 to the right. Accordingly, the wiping member 15 is temporarily moved to a position outside the arrangement region of the plurality of nozzles 10 on the ink ejection surface 3a without being in contact with the ink ejection surface 3a. Thereafter, the control device 9 controls the elevating motor 17 to raise the wiping member 15 and press the tip of the wiping member 15 against the ink ejection surface 3a. Thus, when the wiping member 15 is brought into contact with the ink discharge surface 3a, the tip of the wiping member 15 is not abutted against the portion where the nozzle 10 is formed, and the wiping member 15 causes the nozzle 10 to The meniscus is not destroyed.

  Once the wiping member 15 is brought into contact with the ink ejection surface 3a, the control device 9 then controls the wiping drive motor 19 to move the wiping device 13 to the left. As a result, the wiping member 15 wet with ink moves to the left in a state where the tip of the wiping member 15 is in contact with the ink discharge surface 3a, and foreign matters such as paper dust adhering to the ink discharge surface 3a are removed. It is wiped off by the tip.

(Flushing process)
As shown in FIG. 6, the control apparatus 9 performs a flushing process after the wiping process (S14). That is, the control device 9 controls an ink receiving drive mechanism (not shown) to raise the ink receiving member 7 as shown in FIG. Ink is ejected from each nozzle 10. As a result, it is possible to surely eliminate the ejection failure by discharging the foreign matter, air, or thickened ink in the nozzle 10 together with the ink, which causes the ejection failure. Even if the meniscus in some of the nozzles 10 is disturbed by wiping the ink discharge surface 3a by the wiping member 15, the meniscus can be re-formed by this flushing.

  Further, in this flushing process, the control device 9 determines that the nozzle 10 determined in the determination process is in a state where a discharge failure may occur, rather than the nozzle 10 determined as not being in a state where a discharge failure may occur. The flushing amount (the amount of ink ejected from each nozzle 10 during flushing) may be increased. Thereby, the discharge failure of the nozzle 10 can be solved more reliably.

  As described above, in the present embodiment, in the wetting process before the wiping process, ink is ejected from the nozzle 10 of the inkjet head 3 toward the wiping member 15, and the wiping member 15 is wetted with ink. The friction between the ink discharge surface 3a and the wiping member 15 at the time of wiping can be reduced.

  Further, in the wetting process, ink is ejected from the nozzle 10 that is determined not to be in a state where ejection failure may occur in the determination process to the wiping member 15. Thereby, the wiping member 15 can be reliably wetted with ink, and damage to the ink discharge surface 3a due to friction can be more effectively prevented. Further, since ink is not ejected from the ejection failure nozzle 10, it is possible to prevent occurrence of ink mist during the wetting process.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

1] In the above-described embodiment, in the determination process, each nozzle 10 used for the wetting process is individually determined for ejection failure. On the other hand, only a part of the nozzles 10 is individually determined for ejection failure, and the other nozzles 10 are simply determined as to whether or not ejection failure can occur without making a complicated determination. In some cases, the determination process can be simplified. Two specific examples of this are given below.

(1) When the inkjet head 3 has a plurality of nozzle rows, the nozzles 10 that are close to each other in the nozzle arrangement direction between different nozzle rows are likely to have the same conditions with respect to the likelihood of occurrence of ejection failure. For example, when an image on the recording paper 100 is printed, a group of nozzles 10 located at close positions in the nozzle arrangement direction are simultaneously used to form the image. As described above, the discharge timing, the discharge frequency, and the like are often similar between the group of nozzles 10 that are close to each other in the nozzle arrangement direction. In the group of nozzles 10, the temperature and humidity conditions around the nozzles 10 are also close. Therefore, in the determination process, only the nozzles 10 belonging to a part of the nozzle arrays among the plurality of nozzle arrays are determined, and the determination results for the part of the nozzle arrays about the nozzles 10 belonging to the other nozzle arrays are determined. Based on the above, it may be estimated whether or not ejection failure may occur.

  For example, in FIG. 9, when the nozzles 10 within the range A in the paper width direction are used in the wetting process, the determination regarding ejection failure is individually performed for the four nozzles 10 positioned within the range A of the one nozzle row 11a. To do. However, the above determination is not performed individually for the four nozzles 10 positioned within the range A of the other nozzle row 11b, and ejection failure may occur using the determination result for the one nozzle row 11a. Estimate whether the state.

  More specifically, in the determination for one nozzle row 11a, it is determined that one nozzle 10x (filled nozzle in FIG. 9) of the four nozzles 10 is in a state where ejection failure may occur. . At this time, of the four nozzles 10 in the range A of the other nozzle row 11b, the two nozzles 10y and 10z whose positions are closest to the nozzle 10 are the nozzles 10 in a state where ejection failure may occur. It is assumed that the other two nozzles 10 are nozzles 10 that are not in a state where ejection failure may occur. As described above, the determination process can be simplified by determining the ejection failure only for a part of the nozzle rows.

(2) Among the plurality of nozzles 10 of the inkjet head 3, the nozzle 10 that is rarely used may be regarded as a nozzle 10 that is unconditionally in a state where ejection failure may occur.

  As shown in FIG. 10, the nozzle 10 a 1 located at the right end of the nozzle row 11 a is an end-side nozzle that ejects ink toward the right edge of the recording paper 100. The nozzle 10b1 located at the left end of the nozzle row 11b is an end-side nozzle that ejects ink toward the left edge of the recording paper. In addition, the control device 9 controls the inkjet head 3 to perform printing processing with a border (first liquid ejection processing of the present invention) that does not print an image or the like on the left and right edges of the recording paper 100, and the recording paper 100. It is possible to execute borderless printing processing (second liquid ejection processing of the present invention) for recording an image or the like on the left and right edge portions.

  In the bordered printing process, the control device 9 causes ink to be ejected from the nozzles 10 excluding the two end side nozzles 10a1 and 10b1 among the plurality of nozzles 10 of the inkjet head 3. In the borderless printing process, ink is ejected from all the nozzles 10 including the two end-side nozzles 10a1 and 10b1 of the inkjet head 3. Here, “to eject ink from the nozzle 10” means that the nozzle 10 can be used according to the image to be printed, and that ink is always ejected from the nozzle 10 during printing. It doesn't mean that.

  In this configuration, the two end-side nozzles 10a1 and 10b1 that can be used only in the borderless printing process are less frequently used than the other nozzles 10 that can also be used in the bordered printing process and do not eject ink. Therefore, it can be said that ejection failure is likely to occur. Therefore, in the determination process, the control device 9 sets the two end-side nozzles 10a1 and 10b1 to nozzles that are unconditionally in a state where a discharge failure can occur without making a determination regarding discharge failure, and in the wetting process, These two end-side nozzles 10a1 and 10b1 are not always used. Thus, the determination process can be simplified by omitting the determination of ejection failure for the end-side nozzles 10a1 and 10b1.

2] In the above-described embodiment, in the determination process, it is determined whether or not each nozzle 10 is in a state in which ejection failure may occur by estimation based on the usage frequency or the like. On the other hand, when the printer 1 includes a device that actually detects the ejection failure of each nozzle 10, a determination regarding ejection failure is performed for each nozzle 10 based on the detection result of the detection device. Also good. As an apparatus for inspecting the ejection failure of the nozzle 10, devices having various configurations have been conventionally known. For example, a device configured to detect a droplet ejected from the nozzle 10 with a laser sensor may be employed. it can.

3] In the wetting process, the shape of the wiping member 15 may be devised so that the ink ejected from the nozzle 10 is likely to stay on the surface of the wiping member 15. For example, as shown in FIG. 11A, a groove 15 a may be formed at the tip of the wiping member 15. Alternatively, as shown in FIG. 11 (b), a recess 15 b may be formed at the tip of the wiping member 15.

4] In the above embodiment, the configuration in which the wiping device 13 is moved relative to the inkjet head 3 and the ink ejection surface 3a is wiped is illustrated, but the inkjet head 3 may be moved relative to the wiping device 13. Good. Moreover, the structure which both the inkjet head 3 and the wiping apparatus 13 move may be sufficient.

  For example, when the inkjet head is a so-called serial head that is mounted on a carriage that moves in the paper width direction and discharges ink while moving in the paper width direction, a wiping device that is fixedly provided in the printer 1 It is possible to move the ink jet head 3 to the wiping device 13 by moving the ink jet head 3 relative to the wiping device 13.

  In the above-described embodiment and its modifications, the present invention is applied to an ink jet printer that prints an image or the like by ejecting ink onto a recording sheet, but is used for various purposes other than printing an image or the like. The present invention can also be applied to a liquid ejecting apparatus. For example, the present invention can also be applied to a liquid ejection device that ejects a conductive liquid onto a substrate to form a conductive pattern on the substrate surface.

DESCRIPTION OF SYMBOLS 1 Printer 3 Inkjet head 3a Ink discharge surface 9 Control apparatus 10 Nozzle 10a1, 10b1 End side nozzle 11a, 11b Nozzle row 15 Wiping member 17 Lifting motor 19 Wiping drive motor 37 Temperature sensor 38 Humidity sensor 100 Recording paper

Claims (10)

A liquid discharge head having a liquid discharge surface on which a plurality of nozzles are formed;
A wiping member for wiping the liquid discharge surface of the liquid discharge head;
Drive means for moving at least one of the wiping member and the liquid ejection head so that the wiping member moves along a direction parallel to the liquid ejection surface with respect to the liquid ejection head;
Control means for controlling the liquid discharge head and the driving means,
The control means includes
A determination process for determining whether at least some of the plurality of nozzles are in a state where ejection failure may occur;
A wetting process in which the liquid ejection head is controlled to cause the liquid to be ejected toward the wiping member from a nozzle that is determined not to cause the ejection failure in the determination process, and to wet the wiping member; ,
A wiping process for controlling the driving means to wipe the liquid discharge surface by the wiping member in a wet state with liquid;
A liquid ejecting apparatus characterized in that: A position changing means for changing a position of the wiping member relative to the liquid discharge head in a direction perpendicular to the liquid discharge surface;
The control means includes
In the wetting process, the position changing means and the driving means are controlled, and the wiping member is determined not to be in a state where the ejection failure may occur without contacting the liquid ejection surface. After moving to the opposite position, liquid is discharged from the nozzle to the wiping member,
In the wiping process, the position changing unit and the driving unit are controlled, and the wiping member is moved with respect to the liquid ejection surface in contact with the liquid ejection surface, so that the liquid ejection surface is moved. The liquid ejection device according to claim 1, wherein the liquid ejection device is wiped off. The control means includes
After the wetting process, the wiping member is moved to a position outside the arrangement area of the plurality of nozzles on the liquid ejection surface without contacting the liquid ejection surface, and then the wiping process is executed. The liquid discharge apparatus according to claim 2, wherein In the determination process, the control means
4. The liquid according to claim 1, wherein it is determined whether or not the nozzle is in a state in which ejection failure may occur based on the number of times of ejection of the liquid within a predetermined period of each nozzle. Discharge device. In the determination process, the control means
5. The liquid according to claim 1, wherein it is determined whether or not the nozzle is in a state in which ejection failure may occur based on an elapsed time from the previous liquid ejection of each nozzle. Discharge device. Comprising a temperature detecting means for detecting the temperature around the liquid discharge head;
In the determination process, the control means
The temperature detected by the temperature detection unit is referred to determine whether or not each of the at least some of the nozzles is in a state where ejection failure can occur. Liquid discharge device. Comprising humidity detecting means for detecting the humidity around the liquid discharge head;
In the determination process, the control means
7. The apparatus according to claim 4, wherein, with reference to the humidity detected by the humidity detection unit, it is determined whether or not ejection failure occurs for each of the at least some of the nozzles. The liquid discharge apparatus according to 1. The control means, after the wiping process, controls the liquid ejection head to perform a flushing process for ejecting liquid from each of the plurality of nozzles,
Furthermore, the control means in the flushing process,
The nozzle that is determined to be in a state in which the ejection failure can occur in the determination process has a flushing amount greater than that of a nozzle that is determined not to be in a state in which the ejection failure can occur. The liquid ejection device according to any one of 1 to 7. Transporting means for transporting a target to which liquid discharged from the liquid discharge head lands in a transport direction parallel to the liquid discharge surface with respect to the liquid discharge head;
The plurality of nozzles of the liquid ejection head are arranged along the nozzle arrangement direction intersecting the transport direction on the liquid ejection surface, thereby extending on the liquid ejection surface in the nozzle arrangement direction, and A plurality of nozzle rows arranged along the transport direction are formed,
In the determination process, the control means
Only for nozzles belonging to some of the plurality of nozzle rows, it is determined whether or not ejection failure can occur,
The nozzles belonging to the remaining nozzle rows are estimated based on the determination results for the nozzles belonging to the partial nozzle rows as to whether or not the ejection failure can occur. The liquid ejection apparatus according to any one of the above. Transporting means for transporting a target to which liquid discharged from the liquid discharge head lands in a transport direction parallel to the liquid discharge surface with respect to the liquid discharge head;
The plurality of nozzles of the liquid discharge head are arranged along the nozzle arrangement direction intersecting the transport direction on the liquid discharge surface, so that a nozzle row extending in the nozzle arrangement direction is formed on the liquid discharge surface. Formed,
Of the nozzles belonging to the nozzle row, the end nozzle located on the end side of the nozzle row is a nozzle that discharges liquid toward the edge of the discharge target body in the nozzle arrangement direction,
The control means controls the liquid discharge head and the transport means,
A first liquid ejection process in which liquid is ejected from only the nozzles of the nozzle row other than the end side nozzles toward the ejection target;
A second liquid ejection process in which liquid is ejected from all nozzles of the nozzle row including the end-side nozzles toward the body to be ejected.
Further, the control means includes
The liquid ejecting apparatus according to claim 1, wherein, in the determination process, the end-side nozzle is set to a nozzle in a state where the ejection failure may occur.

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