JP6467894B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection apparatus.

  Patent Document 1 discloses an ink jet printer that ejects a plurality of types of ink and records an image on a recording sheet as a liquid ejecting apparatus that ejects liquid from a nozzle. The printer of Patent Document 1 includes an inkjet head that can eject six colors of ink toward a recording sheet while reciprocating in the width direction (also referred to as a scanning direction) of the recording sheet.

  The inkjet head includes six head units arranged side by side in the scanning direction. Each head unit has two nozzle rows that extend in the conveyance direction of the recording paper and eject ink of different colors. Specifically, each of the two head units on the center side has two nozzle rows that respectively eject black and yellow inks. Each of the two head units arranged on the outside has two nozzle rows that respectively discharge cyan and magenta inks. Each of the two head units located on the outermost side has two nozzle rows that respectively eject light magenta and light cyan inks.

  In addition, a total of 12 nozzle rows that eject six colors of ink are arranged symmetrically in the scanning direction in the entire six head units. That is, six color nozzle rows are arranged in the order of black, yellow, cyan, magenta, light magenta, and light cyan from the center in the scanning direction to both sides. With this configuration, it is possible to make the landing order of the six colors of ink the same when the inkjet head moves to one side in the scanning direction and when it moves to the other side in the scanning direction.

JP2013-215915A (FIG. 2)

  By the way, in general ink jet printers, a cap for performing a suction purge is often provided for the purpose of eliminating defective ejection of nozzles of an ink jet head. The cap is configured to be movable between a cap position that covers a plurality of nozzles of the inkjet head and an uncap position that is spaced apart from the inkjet head. A suction pump is connected to the cap. When the cap is in the cap position and the nozzle of the inkjet head is covered with the cap, operating the suction pump to depressurize the space in the cap forces ink from the multiple nozzles covered with the cap. Discharged.

  In the inkjet printer having the configuration as described in Patent Document 1, when a cap for suction purge is provided, it is conceivable to adopt a configuration in which the nozzles of a plurality of head units are commonly covered with a single cap. However, in this case, all types of ink are discharged into one cap and mixed with each other, and the mixed ink may flow backward to some nozzles, resulting in color mixing in the nozzles. Further, even when it is desired to perform suction purge only for a specific nozzle row, such as when ejection failure occurs only in a specific nozzle row, inevitably, suction purge is performed for all nozzle rows at the same time. As a result, the amount of waste ink increases unnecessarily.

  On the other hand, it is also conceivable to employ a cap having a configuration in which the capping region is divided with the boundary between two nozzle arrays that eject different inks. However, Patent Document 1 has a configuration in which one head unit has two nozzle arrays that respectively eject two different colors of ink. In this case, when the capping region is divided with the boundary between two nozzle rows of one head unit, it is necessary to abut the partition wall portion for dividing the region between the two nozzle rows. is there. For this purpose, in order to secure an area where the partition wall abuts, it is necessary to increase the distance between the two nozzle rows to a certain value or more. However, when this is done, the size of one head unit increases, and the size of the entire inkjet head Will also increase in size.

  An object of the present invention is a liquid ejection apparatus having a plurality of head units for ejecting two types of liquids, suppressing liquid mixture in a cap during suction purge and reducing the amount of waste liquid without increasing the overall size. Is to plan.

Means for Solving the Problems and Effects of the Invention

A liquid ejection apparatus according to a first aspect of the present invention includes a first head unit including a first nozzle that ejects a first liquid and a second nozzle that ejects a second liquid different from the first liquid. A second head that has a third nozzle that discharges the first liquid and a fourth nozzle that discharges the second liquid, and is arranged alongside the first head unit in a predetermined unit arrangement direction. A second nozzle unit that has a unit and a fifth nozzle that discharges a third liquid different from the first liquid and the second liquid, the second head unit relative to the first head unit in the unit arrangement direction; A third head unit disposed on the opposite side of the first liquid and a sixth nozzle that discharges a fourth liquid different from the first liquid and the second liquid, and in the unit arrangement direction, 2 head units And movable to a fourth head unit disposed on the opposite side of the first head unit, a cap position covering the nozzles of the four head units, and an uncapping position spaced from the four head units. A configured cap, and
The cap includes the first nozzle of the first head unit, the second nozzle of the first head unit, and the third nozzle of the second head unit when the cap is in the cap position. A third recess that covers the fourth nozzle of the second head unit in common, and is separated by the first recess and the first partition, and when the cap is in the cap position, The sixth nozzle of the fourth head unit is separated by a second recess that covers the fifth nozzle of the head unit, the first recess and the second partition wall, and the cap is at the cap position. cover, and a third recess, defines a first partition wall portion, and the second partition wall, the first recess with the first partition wall portion and the second partition wall, extending in the unit arrangement direction Has a wall portion, when said cap is in said capping position, by the first partition wall and the second partition wall, and the space of the first recess, the space and the said second inner recess are cut off and the space within the third recess, the side wall portion, and is characterized in Rukoto one rib is formed.

  In the present invention, the first head unit and the second head unit that discharge the first liquid and the second liquid, the third head unit that discharges the third liquid, and the fourth head that discharges the fourth liquid. The structure is sandwiched between units in the unit arrangement direction. In addition, when the cap is at the cap position, the first recess covers the nozzles of the first head unit and the second head unit in common. Further, the second recess covers the nozzle of the third head unit, and the third recess covers the nozzle of the fourth head unit. Furthermore, the space in the first recess, the space in the second recess, and the space in the third recess are blocked by the first partition and the second partition.

  That is, the nozzles of the first and second head units arranged on the inner side are covered with the concave portions different from those of the third and fourth head units on the outer side. Therefore, the first liquid and the second liquid discharged from the first and second head units are the third liquid discharged from the third head unit and the fourth liquid discharged from the fourth head unit. Do not mix in one recess. The first and second head units are covered with the common first recess, so that the first liquid and the second liquid discharged from the two head units are mixed in the first recess. However, compared to a configuration in which all the head units are covered with a single cap and all four types of liquids are mixed together, there are fewer types of mixed liquids, so the adverse effects thereof are small.

  Further, the nozzles of the first and second head units on the inner side are covered with one first recess, so that the first and second partition walls that divide the first recess, the second recess, and the third recess are defined as 1 There is no need to make contact between the two nozzle rows of one head unit. Therefore, the size of each head unit in the unit arrangement direction does not increase. In addition, a negative pressure can be applied by the suction device only to the recess that covers the nozzle in which the ejection failure occurs. That is, since the suction purge is not performed simultaneously for all the nozzles, the amount of waste liquid can be reduced.

  In the liquid ejection device according to a second aspect, in the first aspect, the second recess and the third recess are separated by the first recess, the first recess of the cap, and the second recess A suction device connected to each of the concave portion and the third concave portion, and a flow path resistance of a connection channel connecting the first concave portion and the suction device is the second concave portion, the third concave portion, and the It is characterized by being smaller than the channel resistance of the connecting channel connecting the suction devices.

  The first concave portion of the cap covers the nozzles of the two head units in common, whereas the second concave portion and the third concave portion each cover only the nozzle of one head unit. Therefore, when all of the four head units are simultaneously subjected to suction purge by one suction device connected to the cap, the amount of liquid discharged into the first recess is reduced to the second recess and the third recess. Each will be larger than the amount of liquid to be discharged. When the pressure loss between the first recess and the suction device increases due to the difference in the amount of waste liquid, there is a difference between the negative pressure in the first recess and the negative pressure in the second recess and the third recess. As a result, the amount of liquid discharged from the individual nozzles varies, resulting in a difference in the purging effect. In this regard, in the present invention, the channel resistance of the connection channel connecting the first recess and the suction device is smaller than the channel resistance of the connection channel connecting the second recess and the third recess and the suction device, respectively. Yes. Therefore, it becomes easy to discharge the liquid from the first recess having a large amount of waste liquid to the suction device, and the variation in the amount of liquid discharged from each nozzle is reduced.

  According to a third aspect of the present invention, in the first or second aspect, the liquid ejecting apparatus ejects the first head unit and the nozzles of the second head unit into the first recess of the cap. An absorber capable of absorbing one liquid and the second liquid is accommodated.

  Since the absorber is disposed in the first concave portion of the cap, flushing is performed from the nozzle of the first head unit and the nozzle of the second head unit toward the inside of the cap for the purpose of preventing drying. Can do. The absorber in the first recess absorbs the first liquid and the second liquid discharged from each of the first and second head units, and is common to the first and second head units. It is. Therefore, compared with the case where an absorber is provided for each of the two head units, it is possible to reduce the number of parts by reducing the number of absorbers, thereby reducing the cost. In addition, the number of man-hours for attaching the absorber can be reduced. Furthermore, there is an effect that the size of the absorbent body per head unit is increased and the amount of waste liquid that can be absorbed is increased.

  According to a fourth aspect of the present invention, in any one of the first to third aspects of the invention, the liquid discharge device is discharged from the first nozzle of the first head unit and the third nozzle of the second head unit. The first liquid is black ink, and the third liquid discharged from the fifth nozzle of the third head unit is yellow ink.

  When the black ink and the yellow ink are mixed in the cap during the suction purge, and the mixed ink enters the yellow nozzle, the influence on the color tone of the printed image is particularly large. In the present invention, black ink is ejected from the inner first and second head units, and yellow ink is ejected from the outer third head unit. That is, since the nozzle for ejecting black ink and the nozzle for ejecting yellow ink are respectively covered by different recesses of the cap, the black ink and the yellow ink are within one recess during the suction purge. Will not mix and flow back into the nozzle.

According to a fifth aspect of the present invention, in any one of the first to fourth inventions, when the cap is at the cap position, the first concave portion causes the space in the second concave portion to be separated from the second concave portion. 3 The space in the recess is cut off.
According to a sixth aspect of the present invention, in the first to fourth aspects of the invention, the third head unit includes the fourth nozzle in addition to the fifth nozzle that discharges the third liquid. The fourth head unit includes an eighth nozzle that discharges the third liquid in addition to the sixth nozzle that discharges the fourth liquid; The cap has a communication portion that communicates the space in the second recess and the space in the third recess when the cap is in the cap position .

  When both the third head unit and the fourth head unit are to discharge the third liquid and the fourth liquid, the third liquid and the fourth liquid are respectively formed in the second concave portion and the third concave portion. Both liquids are drained. That is, whether the second recess and the third recess are separated or communicated with each other, the third liquid and the fourth liquid are mixed in each recess. Therefore, a configuration in which the second concave portion and the third concave portion are connected by the communication portion may be employed.

1 is a schematic plan view of a printer according to an embodiment. It is sectional drawing of the carriage with which four head units were attached. It is a top view of one head unit of an inkjet head. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is a top view of a cap. It is sectional drawing of a carriage in the state which has a cap in a cap position. It is sectional drawing of a carriage in the state which has a cap in a cap position in the modification. It is a top view of the cap in another modification. It is a top view of the cap in another modification. It is sectional drawing of the inkjet head of another modification.

  Next, an embodiment of the present invention will be described. FIG. 1 is a schematic top view of the printer according to the present embodiment. First, a schematic configuration of the inkjet printer 1 will be described with reference to FIG. 1 are defined as “front”, “rear”, “left”, and “right” of the printer. Also, the front side of the page is defined as “up”, and the other side of the page is defined as “down”. Below, it demonstrates using each direction word of front, back, left, right, up and down suitably.

(Schematic configuration of the printer)
As shown in FIG. 1, the ink jet printer 1 includes a platen 2, a carriage 3, an ink jet head 4, a transport mechanism 5, a maintenance device 6, a control device 7, and the like.

  On the upper surface of the platen 2, a recording sheet 100 as a recording medium is placed. The carriage 3 is configured to be capable of reciprocating in the left-right direction (hereinafter also referred to as the scanning direction) along the two guide rails 10 and 11 in a region facing the platen 2. An endless belt 14 is connected to the carriage 3, and the endless belt 14 is driven by a carriage drive motor 15, whereby the carriage 3 moves in the scanning direction.

  The inkjet head 4 is attached to the carriage 3 and moves in the scanning direction together with the carriage 3. The inkjet head 4 includes four head units 20 (a first head unit 201, a second head unit 202, a third head unit 203, and a fourth head unit 204) arranged in the scanning direction. The four head units 20 (201 to 204) are respectively connected to a cartridge holder 8 on which ink cartridges 17 of four colors (black, yellow, cyan, magenta) are mounted by tubes (not shown). Each head unit 20 has a plurality of nozzles 30 (see FIGS. 3 and 4) formed on the lower surface (the surface on the opposite side of the paper surface of FIG. 1). The nozzle 30 of each head unit 20 discharges the ink supplied from the ink cartridge 17 toward the recording paper 100 placed on the platen 2.

  In the following description, among the components of the printer 1, those corresponding to the black (K), yellow (Y), cyan (C), and magenta (M) inks are indicated by the reference numerals indicating the components. After that, in order to identify which ink corresponds to, any symbol of “k” indicating black, “y” indicating yellow, “c” indicating cyan, and “m” indicating magenta is appropriately attached. . For example, the ink cartridge 17k refers to an ink cartridge that stores black ink.

  The transport mechanism 5 includes two transport rollers 18 and 19 disposed so as to sandwich the platen 2 in the front-rear direction. The transport mechanism 5 transports the recording paper 100 placed on the platen 2 forward (hereinafter also referred to as a transport direction) by two transport rollers 18 and 19.

  The maintenance device 6 is for carrying out suction purge for the purpose of maintaining and recovering the ejection performance of the inkjet head 4, and is disposed at a position on the right side of the platen in the moving range of the carriage in the scanning direction. . The maintenance device 6 includes a cap 21 and a suction pump 24. The cap 21 is made of a soft material such as rubber or synthetic resin. The cap 21 is configured to be movable in the vertical direction (perpendicular to the plane of FIG. 1) by a cap drive mechanism having an appropriate configuration including the cap drive motor 22. Then, the cap 21 is driven up and down by a cap driving mechanism, and thereby moves to a cap position that covers the nozzles 30 of the four head units 20 of the inkjet head 4 and an uncap position that is separated from the four head units 20. Is possible. The suction pump 24 is connected to the cap 21 via the switching device 23.

  The operation of the maintenance device 6 during the suction purge is as follows. When the carriage 3 is at a position facing the cap 21, the cap 21 is driven upward by the cap driving mechanism. As a result, the cap 21 moves to the cap position and comes into close contact with the lower surfaces of the four head units 20 to cover the nozzles 30. In this state, when the space in the cap 21 is depressurized by the suction pump 24, the ink is forcibly discharged from each nozzle 30. At this time, dust, bubbles, or thickened ink existing in the ink flow path in the head unit 20 are discharged together.

  The cap 21 has three recesses 25 formed therein. The switching device 23 is for switching the communication state between the suction pump 24 and the three recesses 25. Details of the maintenance device 6 such as the specific configuration of the cap 21 and the operation of the switching device 23 will be described later.

  The control device 7 includes a ROM (Read Only Memory), a RAM (Random Access Memory), an ASIC (Application Specific Integrated Circuit) including various control circuits, and the like. The control device 7 executes various processes such as printing on the recording paper 100 and maintenance of the inkjet head 4 by the ASIC according to the program stored in the ROM.

  For example, in the printing process, the control device 7 controls the inkjet head 4, the carriage drive motor 15, and the like based on a print command input from an external device such as a PC, and prints an image or the like on the recording paper 100. . Specifically, an ink discharge operation for discharging ink while moving the inkjet head 4 in the scanning direction together with the carriage 3 and a transport operation for transporting the recording paper 100 in the transport direction by the transport rollers 18 and 19 alternately. To do. In the maintenance process, the control device 7 controls the cap drive motor 22, the suction pump 24, the switching device 23, and the like to perform the above-described suction purge.

(Details of inkjet head 4)
Next, the detailed configuration of the inkjet head 4 will be described. FIG. 2 is a sectional view of the carriage 3 to which the four head units 20 are attached. FIG. 3 is a top view of one head unit 20 of the inkjet head 4.

  As shown in FIGS. 1 and 2, a plate-like unit holder 33 is provided at the lower portion of the carriage 3, and four head units 20 (201 to 204) are arranged side by side in the scanning direction on the upper surface of the unit holder 33. It has been. As shown in FIG. 3, a plurality of nozzles 30 are formed on the lower surface of one head unit 20. The plurality of nozzles 30 of each head unit 20 are exposed from an opening formed in the unit holder 33. The plurality of nozzles 30 are arranged along the transport direction to form two nozzle rows 31. In addition, the position of the nozzle 30 has shifted | deviated to the conveyance direction between the two nozzle rows 31, and the several nozzle 30 is arrange | positioned in what is called a zigzag form.

  Further, the two nozzle rows 31 of one head unit 20 each eject ink of different colors. In addition, four types of nozzle arrays 31 that respectively eject four colors of ink are arranged symmetrically in the four head units 20 as a whole. Specifically, among the four head units 20, each of the first head unit 201 and the second head unit 202 disposed on the inner side in the scanning direction includes the black nozzle row 31 k positioned on the inner side and the outer side positioned on the outer side. A magenta nozzle row 31m. In addition, the third head unit 203 disposed on the left side of the first head unit 201 and the fourth head unit 204 disposed on the right side of the second head unit 202, that is, each of the two outer head units 203 and 204 are , A cyan nozzle row 31c located inside, and a yellow nozzle row 31y located outside.

  That is, in the entire four head units 20, there are two nozzle rows 31 for one color ink, for a total of eight nozzle rows 31. The eight nozzle rows 31 are arranged in the order of the black nozzle row 31k, the magenta nozzle row 31m, the cyan nozzle row 31c, and the yellow nozzle row 31y from the inside toward the left and right sides. In FIG. 5, for the nozzles 30 and nozzle rows 31 of the respective colors, those arranged on the left side are denoted by reference numeral “1”, and those disposed on the right side are denoted by reference numeral “2”. doing. For example, the nozzle 30c1 is a nozzle 30 that is disposed on the left side and that discharges cyan ink.

  That is, four color nozzle rows 31 are arranged symmetrically in the order of black, magenta, cyan, and yellow from the center side. In the above configuration, the landing order of the four colors of ink on the recording paper 100 can be made the same when the carriage 3 moves to the left and when it moves to the right. Thereby, in bidirectional printing, the difference in color between the image portion formed when the carriage 3 moves to the left and the image portion formed when the carriage 3 moves to the right can be suppressed to be small. It becomes possible.

(Head unit configuration)
Next, a specific configuration of the head unit 20 will be described. In addition, since all the four head units 20 of the inkjet head 4 of this embodiment have the same configuration, only one of them will be described. 4 is a cross-sectional view taken along line IV-IV in FIG.

  As shown in FIG. 3, the head unit 20 has an outer shape that is long in the transport direction and has a substantially rectangular shape in plan view. As shown in FIG. 4, the head unit 20 includes a holder member 40 and a head main body 43 held by the holder member 40. The holder member 40 is made of synthetic resin, metal, or the like. An ink supply channel 44 is formed in the holder member 40. The ink supply channel 44 of the holder member 40 is connected to the cartridge holder 8 via a tube (not shown). Then, the inks of the ink cartridges 17 of two colors (black and magenta or cyan and yellow) mounted on the cartridge holder 8 are respectively supplied to the head main body 43 through the ink supply channel 44.

  The head main body 43 includes a first flow path substrate 46, a second flow path substrate 47, a nozzle plate 48, a piezoelectric actuator 49, a protection member 50, and the like. The materials of the first flow path substrate 46, the second flow path substrate 47, the nozzle plate 48, and the protection member 50 are not particularly limited, but for example, those formed of silicon can be suitably used. .

  A plurality of pressure chambers 51 are formed in the first flow path substrate 46. The plurality of pressure chambers 51 are arranged in the transport direction corresponding to the plurality of nozzles 30. Further, the first flow path substrate 46 has a vibration film 55 that covers the plurality of pressure chambers 51.

  The second flow path substrate 47 is bonded to the lower surface of the first flow path substrate 46. The second flow path substrate 47 is formed with two manifolds 52 communicating with the two ink supply flow paths 44 of the holder member 40. The two manifolds 52 respectively extend in the transport direction (in the direction perpendicular to the plane of FIG. 4) in the region overlapping the plurality of pressure chambers 51 of the first flow path substrate 46. The lower side of each manifold 52 is covered with a synthetic resin film 56. A unit holder 33 that holds the head unit 20 is disposed below the film 56. The second flow path substrate 47 is formed with a plurality of communication holes 53 that allow the manifold 52 and the plurality of pressure chambers 51 to communicate with each other. Further, the second flow path substrate 47 is also formed with a plurality of communication holes 54 for communicating the plurality of pressure chambers 51 with the plurality of nozzles 30 formed in the nozzle plate 48 described below.

  The nozzle plate 48 is bonded to the lower surface of the second flow path substrate 47. The nozzle plate 48 is formed with a plurality of nozzles 30 arranged in the transport direction. As described above, the plurality of nozzles 30 constitute two nozzle rows 31. Each nozzle 30 communicates with the pressure chamber 51 of the first flow path substrate 46 through a communication hole 54 formed in the second flow path substrate 47.

  The piezoelectric actuator 49 is disposed in a region of the vibration film 55 of the first flow path substrate 46 that overlaps the plurality of pressure chambers 51 in the vertical direction. The piezoelectric actuator 49 has a piezoelectric film made of a piezoelectric material, and ejects energy into the ink in the pressure chamber 51 by vibrating the vibration film 55 using piezoelectric strain generated when a voltage is applied to the piezoelectric film. Is given.

  The protection member 50 is disposed on the upper surface of the first flow path substrate 46 so as to cover the piezoelectric actuator 49. The protective member 50 is provided for the purpose of blocking the piezoelectric film of the piezoelectric actuator 49 from outside air and preventing it from coming into contact with moisture.

(Details of maintenance equipment)
Next, details of the maintenance device 6 will be described. FIG. 5 is a plan view of the cap 21. FIG. 6 is a cross-sectional view of the carriage 3 with the cap 21 in the cap position. As described earlier, as shown in FIG. 6, the cap 21 is driven up and down by a cap drive mechanism including a cap drive motor 22 (see FIG. 1), so that the four head units of the ink-jet head 4. It is possible to move between a cap position (solid line position) covering 20 nozzles 30 and an uncapping position (two-dot chain line position) separated from the four head units 20.

  The cap 21 is a member having a rectangular planar shape that is long in the transport direction. 5 and 6, the cap 21 includes a bottom wall portion 60, a rectangular frame-shaped lip portion 63 formed on the outer edge portion of the bottom wall portion 60, and a lip portion. In 63, it has the 1st partition part 61 and the 2nd partition part 62 which are each extended in a conveyance direction. A portion surrounded by the lip 63 of the cap 21 is partitioned into three recesses 25 by the first partition wall 61 and the second partition wall 62. That is, the cap 21 includes a first recess 251 positioned in the center in the left-right direction, a second recess 252 positioned on the left side of the first recess 251, and a third recess 253 positioned on the right side of the first recess 251. Have The first recess 251 and the second recess 252 are separated by the first partition wall 61, and the first recess 251 and the third recess 253 are separated by the second partition wall 62. Moreover, the 2nd recessed part 252 and the 3rd recessed part 253 are isolate | separated by the 1st recessed part 251 located between both.

  The first recess 251 covers the two head units 20 in common, and covers not only the lower surfaces of the two head units 20 but also the area between the two head units 20. Therefore, the width of the first recess 251 in the scanning direction exceeds twice the width of the second recesses 252 and 253 that cover only one head unit 20. Here, if the heights of the bottom surfaces of the first recesses 251 and the bottom surfaces of the second recesses 252 and the third recesses 253 are the same, the volume of the space in the first recesses 251 becomes the second recesses 252 and the third recesses. Compared to H.253, the volume in the recess is too large with respect to the amount of ink discharged from the head unit 20. The large volume in the recesses is disadvantageous for drying the ink in the nozzles 30 during capping. Therefore, in this embodiment, in order to reduce the volume of the first recess 251, the position of the bottom surface of the first recess 251 is higher than the bottom surfaces of the second recess 252 and the third recess 253 as shown in FIG. 6. It has become. Further, in the bottom wall portion 60 of the cap 21, a portion serving as the bottom surface of the first recess 251, a portion serving as the bottom surface of the second recess 252, and a portion serving as the bottom surface of the third recess 253 are respectively provided in the discharge port 251 a. , 252a, 253a.

  As shown in FIG. 6, when the cap 21 is in the cap position, the lip portion 63 and the two partition wall portions 61 and 62 of the cap 21 abut against the lower surface of the unit holder 33 that holds the four head units 20. More specifically, the first partition wall 61 abuts on the region of the unit holder 33 between the first head unit 201 and the third head unit 203. The second partition wall 62 abuts on a region between the second head unit 202 and the fourth head unit 204. Further, the left side portion of the lip portion 63 having a rectangular frame shape is in contact with the region on the left side of the fourth head unit 204 of the unit holder 33, and the right side portion of the lip portion 63 is the third head unit of the unit holder 33. It contacts the region on the right side of 203. The space in the first recess 251 and the space in the second recess 252 of the cap 21 are blocked by the first partition wall 61. The space in the first recess 251 and the space in the third recess 253 are blocked by the second partition wall 62.

  The first concave portion 251 of the cap 21 covers the nozzle rows 31k1 and 31k2 that eject black ink and the nozzle rows 31m1 and 31m2 that eject magenta ink in the first head unit 201 and the second head unit 202 in common. . Further, the second concave portion 252 of the cap 21 covers the nozzle row 31c1 that discharges cyan ink and the nozzle row 31y1 that discharges yellow ink of the third head unit 203. Further, the third concave portion 253 of the cap 21 covers the nozzle row 31c2 that discharges cyan ink and the nozzle row 31y2 that discharges yellow ink of the fourth head unit 204.

  As shown in FIGS. 5 and 6, the first concave portion 251, the second concave portion 252, and the third concave portion 253 of the cap 21 are each formed of a porous material or the like and can absorb ink. 71, 72, 73 are accommodated. Note that the width of the absorber 71 accommodated in the first recess 251 is larger than the width of the absorbers 72 and 73 accommodated in the second recess 252 and the third recess 253. The width of the absorber 71 is larger than twice the width of the absorbers 72 and 73, for example, about 2.3 times.

  As shown in FIG. 6, the discharge port 251 a of the first recess 251, the discharge port 252 a of the second recess 252, and the discharge port 253 a of the third recess 253 are respectively connected to the switching device 23 by tubes 64, 65, 66. It is connected. The switching device 23 is connected to a suction pump 24, and the suction pump 24 is further connected to a waste liquid box 27 (see FIG. 1). The switching device 23 switches the communication state between the suction pump 24 and the first recess 251, the second recess 252, and the third recess 253, respectively. By making the suction pump 24 communicate with all of the first concave portion 251, the second concave portion 252, and the third concave portion 253, the pressure is simultaneously reduced in all of the first concave portion 251, the second concave portion 252, and the third concave portion 253. The suction purge can be simultaneously performed on all the four head units 20. Alternatively, the head unit 20 that needs to recover the ejection characteristics by communicating only one of the first recess 251, the second recess 252, and the third recess 253 with the suction pump 24. It is also possible to perform the suction purge only for the above.

(About suction purge)
Next, the flow of suction purge performed by the maintenance device 6 will be described. The suction purge is performed when there is a high possibility that an ejection failure will occur in any of the nozzles 30. The timing is not particularly limited. For example, when the user inputs a suction purge execution instruction from an external device such as a PC or the operation panel (not shown) of the printer 1, or the previous suction purge is executed. The suction purge is executed when a predetermined time has elapsed since then.

  When performing the suction purge, the carriage 3 is moved to the position of the maintenance device 6 by the carriage drive motor 15, and the lower surfaces of the four head units 20 of the inkjet head 4 are made to face the cap 21. Next, the cap 21 is raised by the cap driving mechanism including the cap driving motor 22 and brought into contact with the inkjet head 4 to be positioned at a cap position that covers the nozzles 30 of the four head units 20.

  Next, the recess 25 corresponding to the head unit 20 that needs to perform the suction purge and the suction pump 24 are communicated by the switching device 23. For example, when the suction purge of the first head unit 201 is particularly necessary, the first recess 251 and the suction pump 24 are communicated. On the other hand, when suction purging of all the head units 20 is necessary, all of the first recess 251, the second recess 252, and the third recess 253 are respectively communicated with the suction pump 24.

  After that, the suction pump 24 is operated, and the inside of the recess 25 communicating with the suction pump 24 is decompressed. Thereby, the inside of the recessed part 25 connected with the suction pump 24 becomes a negative pressure, and the ink is forcibly discharged from the nozzles 30 of the head unit 20 covered by the recessed part 25. Accordingly, it is possible to maintain and recover the ejection performance by discharging dust or bubbles mixed in the ink flow path in the head unit 20 or ink thickened by drying in the nozzle 30. The waste ink discharged from each head unit 20 by suction purge is sent to the waste liquid box 27.

  Here, in the present embodiment, the nozzles 30 of the two head units 201 and 202 arranged on the inner side in the scanning direction are covered with the concave portions 25 different from the two head units 203 and 204 arranged on the outer side. . Therefore, the black ink and the magenta ink ejected from the inner two head units 201 and 202 do not mix with the cyan ink and the yellow ink ejected from the outer head units 203 and 204 in one recess 25. The two inner head units 201 and 202 are covered with the first recess 251 so that the black ink and the magenta ink are mixed in the first recess 251. Further, the yellow ink and the cyan ink are mixed in the second recess 252 and the third recess 253. However, since the nozzles 30 of all four head units 20 are covered with one cap and all the four colors of ink are mixed together, there are fewer types of mixed inks, so the adverse effects caused thereby, For example, the color tone change of the image is also reduced.

  In addition, it is preferable that the two color inks mixed in one concave portion 25 be a combination of inks that hardly cause adverse effects such as a change in color tone even if mixed. For example, yellow ink causes a large change in color tone even if black ink is mixed a little. Therefore, if black ink and yellow ink are mixed in one concave portion 25 and the mixed ink enters the yellow nozzle 30y, the influence of the printed image is particularly great. Therefore, in this embodiment, black ink is ejected from the two inner head units 201 and 202, and yellow ink is ejected from the two outer head units 203 and 204. In this configuration, the nozzle 30k that discharges the black ink and the nozzle 30y that discharges the yellow ink are respectively covered with the different recesses 25 of the cap 21, so that the black ink and the yellow ink are within one recess 25. Are mixed together and do not flow back into the nozzle 30.

  In the present embodiment, the first recess 251 of the cap 21 covers the nozzles 30 of the two inner head units 201 and 202 in common, whereas the second recess 252 and the third recess 253 are each one. Only the nozzles 30 of the head unit 203 (204) are covered. Therefore, when all the four head units 20 are simultaneously subjected to suction purge, the amount of ink discharged into the first recess 251 is the amount of ink discharged into the second recess 252 and the third recess 253, respectively. More than. When the pressure loss between the first concave portion 251 and the suction pump 24 increases due to the difference in the amount of waste ink, the negative pressure in the first concave portion 251 and the negative pressure in the second concave portion 252 and the third concave portion 253 are obtained. This causes a difference in the amount of ink discharged from the individual nozzles 30, resulting in a difference in purge effect. Therefore, the flow resistance of the flow path in the tube 64 that connects the first recess 251 and the suction pump 24 is the resistance of the flow path in the tubes 65 and 66 that connects the second recess 252 and the third recess 253 and the suction pump 24, respectively. It is preferably smaller than the channel resistance.

  In addition, said flow-path resistance means the difficulty of the flow of a liquid when flowing the liquid of the same flow volume. Specifically, the flow path resistance depends on the length of the tube, the diameter of the tube, the roughness of the inner surface of the tube, the bending of the tube, and the like. For example, the tube 64 connecting the first recess 251 and the suction pump 24 has a shorter tube diameter than the tubes 65 and 66 connecting the second recess 252 and the third recess 253 and the suction pump 24. What is necessary is just to devise such as enlarging, reducing the inner surface roughness of the tube, or reducing the bending of the tube. Thus, the flow path resistance of the flow path connecting the first recess 251 and the suction pump 24 is made smaller than the flow path resistance of the flow path connecting the second recess 252 and the third recess 253 and the suction pump 24. Accordingly, the waste ink is easily discharged from the first concave portion 251 having a large amount of waste ink to the suction pump 24. Thereby, the variation in the amount of ink discharged from each nozzle 30 is reduced.

(About flushing)
In the present embodiment, absorbers 71, 72, and 73 are accommodated in the first recess 251, the second recess 252, and the third recess 253 of the cap 21, respectively. That is, in the printer 1 of the present embodiment, the cap 21 is not only used at the time of suction purge, but also as an ink receiving member when performing flushing from the nozzles 30 of each head unit 20 for the purpose of preventing drying and the like. Can be used.

  The timing of performing the flushing of each head unit 20 is not particularly limited. However, when the purpose is to prevent ejection failure due to drying in the nozzles 30, the flushing may be performed immediately before printing on the recording paper 100. Many. In some cases, the inkjet head 4 may perform printing while printing on the recording paper 100.

  When performing the flushing, the carriage 3 is moved to the position of the maintenance device 6 by the carriage drive motor 15, and the lower surfaces of the four head units 20 of the inkjet head 4 are opposed to the cap 21. In this state, the ink is continuously ejected from the nozzles 30 of the four head units 20 toward the first concave portion 251, the second concave portion 252, and the third concave portion 253 of the cap 21 a predetermined number of times. The ink ejected by the flushing is absorbed by the absorbers 71, 72, 73 accommodated in the three recesses 25, respectively.

  Here, the absorber 71 accommodated in the first recess 251 has two head units 201 and 202 capable of absorbing black ink and magenta ink discharged from the first head unit 201 and the second head unit 202. Is a common absorber. Therefore, compared with the case where an absorber is individually provided for each of these two head units 201 and 202, the number of absorbers can be reduced, the number of parts can be reduced, and the cost can be reduced. In addition, the number of man-hours for attaching the absorber can be reduced. Furthermore, the size of the absorbent body per head unit 201 (202) is increased, and the amount of waste liquid that can be absorbed is increased. For example, the width of the absorber 71 corresponding to the two head units 201 and 202 is more than twice the width of the absorber 72 (73) corresponding to the one head unit 203 (204).

  In the embodiment described above, the ink jet printer 1 corresponds to the “liquid ejecting apparatus” of the invention. The suction pump 24 corresponds to the “suction device” of the present invention. The black ink corresponds to the “first liquid” of the present invention, the magenta ink corresponds to the “second liquid” of the present invention, the yellow ink corresponds to the “third liquid” of the present invention, and the cyan ink. Corresponds to the “fourth liquid” of the present invention. The nozzle 30k1 for discharging the black ink of the first head unit 201 corresponds to the “first nozzle” of the present invention, and the nozzle 30m1 of the first head unit 201 for discharging the magenta ink is the “second nozzle” of the present invention. Corresponds to “nozzle”. The nozzle 30k2 for discharging the black ink of the second head unit 202 corresponds to the “third nozzle” of the present invention, and the nozzle 30m2 for discharging the magenta ink of the second head unit 202 is the “fourth nozzle” of the present invention. It corresponds to. The nozzle 30y1 that discharges yellow ink of the third head unit 203 corresponds to the “fifth nozzle 30” of the present invention, and the nozzle 30c1 that discharges cyan ink corresponds to the “seventh nozzle” of the present invention. Furthermore, the nozzle 30c2 that discharges cyan ink of the fourth head unit 204 corresponds to the “sixth nozzle” of the present invention, and the nozzle 30y2 that discharges yellow ink corresponds to the “eighth nozzle” of the present invention.

  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 embodiment, the switching device 23 is configured to allow the suction pump 24 and the two or more recesses 25 to communicate with each other at the same time. However, the switching device 23 replaces the suction pump 24 with the three recesses 25. You may make it connect only with one recessed part 25 of them. In this case, when the suction purge is performed for two or more recesses 25, the suction purge for these two or more recesses 25 may be performed one by one in order.

2] In the above-described embodiment, the absorbers 71, 72, and 73 are accommodated in the first concave portion 251, the second concave portion 252, and the third concave portion 253 of the cap 21, respectively. The present invention can also be applied to the cap 21 in which no is accommodated.

3] In the above-described embodiment, the nozzle rows 31 that respectively eject the four colors of ink are arranged symmetrically, but the present invention can be applied to other forms. For example, as shown in FIG. 7, in both the first head unit 201 and the second head unit 202, the black ink nozzle row 31k may be arranged on the left side, and the magenta ink nozzle row 31m may be arranged on the right side. . That is, in the two head units 201 and 202, the black nozzle rows 31k1 and 31k2 and the magenta nozzle rows 31m1 and 31m2 may be alternately arranged in the scanning direction. The same applies to the third head unit 203 and the fourth head unit 204. For example, as shown in FIG. 7, the yellow nozzle row 31y is arranged on the left side, and the cyan nozzle row 31c is arranged on the right side. May be.

4] The width in the scanning direction of the first recess 251 that commonly covers the nozzles 30 of the two head units 20 is larger than that of the second recess 252 and the third recess 253. For this reason, in particular, in the first recess 251, portions of the lip portion 63 located on the upstream side and the downstream side in the transport direction are likely to fall inward due to the negative pressure acting during the suction purge. Therefore, as shown in FIG. 8, in the first recess 251, reinforcing ribs 80 may be formed in the upstream portion 631 and the downstream portion 632 of the lip portion 63, respectively. The number of ribs 80 is not limited to one, and a plurality of ribs may be provided. Further, instead of providing the rib 80, the upstream portion 631 and the downstream portion 632 of the lip portion 63 may be thicker than the other portions.

5] In the embodiment, the second recess 252 and the third recess 253 of the cap 21 are separated by the first recess 251. However, when both the third head unit 203 and the fourth head unit 204 eject cyan ink and yellow ink, cyan ink and yellow ink are respectively formed in the second recess 252 and the third recess 253. Both inks are discharged. In other words, whether the second recess 252 and the third recess 253 are separated or communicated with each other, the cyan ink and the yellow ink are mixed in the recesses 252 and 235. Therefore, a configuration in which the second recess 252 and the third recess 253 are connected may be employed. For example, as shown in FIG. 9, a communication recess 254 that connects the second recess 252 and the third recess 253 may be formed in the upstream portion of the cap 21 in the transport direction.

  In addition, when the absorber for flushing is accommodated in the cap 21, it is preferable that the absorber 74 is accommodated also in the communication recessed part 254, as shown in FIG. Furthermore, it is preferable that the absorber 74 in the communication recess 254 is connected and integrated with the absorber 72 in the second recess 252 and the absorber 73 in the third recess 253. Thereby, the size of one absorber can be enlarged for each of the head units 203 and 204.

6] The number of head units 20 of the inkjet head 4 is not limited to four, and the inkjet head 4 may be configured to have five or more head units 20. For example, when ejecting ink of another color such as light magenta and light cyan in addition to black, magenta, cyan and yellow, two colors of light magenta and light cyan are provided on both sides of the four head units 20 in the scanning direction. Two head units 20 that discharge the ink may be respectively disposed. Further, the head unit 20 that ejects another ink (for example, white ink) may be disposed between the first head unit 201 and the second head unit 202.

7] In the above embodiment, each of the four head units 20 ejects two colors of ink, but the outer two head units 203 and 204 eject only one color of ink. May be. For example, in FIG. 6, the third head unit 203 on the left side has only the nozzle row 31y that discharges yellow ink, and the fourth head unit 204 located on the right side has only the nozzle row 31c that discharges cyan ink. It may have.

8] In the above embodiment, the four head units 20 are separated from each other, but at least a part of the members constituting the head unit 20 may be integrated. That is, one inkjet head may have a configuration including a plurality of first members individually provided in a plurality of head units and a common second member provided over the plurality of head units. More specifically, at least one type of flow path member of the first flow path substrate 46, the second flow path substrate 47, and the nozzle plate 48 shown in FIG. The common 2nd member provided over the head unit 20 to perform may be sufficient.

  For example, in the inkjet head 84 of FIG. 10, the first flow path substrate 46 in which the pressure chambers 51 are formed and the nozzle plate 48 in which the nozzles 30 are formed are individually provided in each of the four head units 90. . That is, the first flow path substrate 46 and the nozzle plate 48 correspond to the first member. On the other hand, the second flow path substrate 87 on which the manifold 52 is formed is shared among the four head units 90. That is, the second flow path substrate 87 corresponds to the second member. In other words, one head unit 90 includes a portion of the first flow path substrate 46 and the nozzle plate 48 and the second flow path substrate 87 that are separated by the two two-dot chain lines in FIG. Including. In addition, the ink supply flow path 44 and the holder member 91 that holds the head unit 90 may be shared by the four head units 90.

  Alternatively, only the first flow path substrate 46 may be individually provided in each of the four head units 90, and the second flow path substrate and the nozzle plate may be shared by the four head units. Alternatively, only the nozzle plate 48 may be individually provided in each of the four head units 90, and the first flow path substrate and the second flow path substrate may be shared by the four head units.

  The embodiments described above and modifications thereof apply the present invention to an ink jet head 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 apparatus that ejects a conductive liquid onto a substrate to form a conductive pattern on the surface of the substrate.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 4 Inkjet head 20 Head unit 251 First head unit 252 Second head unit 253 Third head unit 254 Fourth head unit 21 Cap 24 Suction pump 25 Recess 251 First recess 252 Second recess 253 Third recess 61 First 1 partition wall portion 62 second partition wall portions 64, 65, 66 Tubes 71, 72, 73 Absorber 84 Inkjet head 90 Head unit 254 Communication recess

Claims (6)

A first head unit comprising: a first nozzle that discharges a first liquid; and a second nozzle that discharges a second liquid different from the first liquid;
A second head that has a third nozzle that discharges the first liquid and a fourth nozzle that discharges the second liquid, and is arranged alongside the first head unit in a predetermined unit arrangement direction. Unit,
A fifth nozzle that discharges a third liquid different from the first liquid and the second liquid, and is opposite to the second head unit with respect to the first head unit in the unit arrangement direction; A third head unit arranged on the side,
A sixth nozzle that discharges a fourth liquid different from the first liquid and the second liquid, and is opposite to the first head unit with respect to the second head unit in the unit arrangement direction; A fourth head unit arranged on the side,
A cap position that covers the nozzles of the four head units, and a cap configured to be movable to an uncap position that is separated from the four head units,
The cap is
When the cap is in the cap position, the first nozzle of the first head unit, the second nozzle of the first head unit, the third nozzle of the second head unit, and the second A first recess that covers the fourth nozzle of the head unit in common;
A second recess, which is separated by the first recess and the first partition, and covers the fifth nozzle of the third head unit when the cap is in the cap position;
A third recess that is separated by the first recess and the second partition wall and covers the sixth nozzle of the fourth head unit when the cap is in the cap position;
The first partition wall;
The second partition wall;
A side wall portion that defines the first recess together with the first partition wall portion and the second partition wall portion and extends in the unit arrangement direction ;
When the cap is in the cap position, the first partition wall and the second partition wall cause a space in the first recess, a space in the second recess, and a space in the third recess. Is blocked ,
The side wall portion, a liquid discharge apparatus according to claim Rukoto one rib is formed. The second recess and the third recess are arranged separated by the first recess,
One suction device connected to each of the first recess, the second recess, and the third recess of the cap;
The flow path resistance of the connection channel connecting the first recess and the suction device is smaller than the channel resistance of the connection channel connecting the second recess and the third recess and the suction device, respectively. The liquid ejection device according to claim 1.   An absorber that can absorb the first liquid and the second liquid discharged from the nozzles of the first head unit and the second head unit is accommodated in the first recess of the cap. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The first liquid discharged from the first nozzle of the first head unit and the third nozzle of the second head unit is black ink;
The liquid ejecting apparatus according to claim 1, wherein the third liquid ejected from the fifth nozzle of the third head unit is yellow ink.   The space in the second recess and the space in the third recess are blocked by the first recess when the cap is in the cap position. The liquid discharge apparatus according to 1. The third head unit has a seventh nozzle that discharges the fourth liquid in addition to the fifth nozzle that discharges the third liquid.
The fourth head unit has an eighth nozzle that discharges the third liquid in addition to the sixth nozzle that discharges the fourth liquid,
The cap is
5. The communication device according to claim 1, further comprising a communication portion that communicates the space in the second recess and the space in the third recess when the cap is in the cap position. Liquid discharge device .

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