Ink jet printer

Abstract

To normally perform a suction process.SOLUTION: A printer 10 includes: an ink head 40; a cap 71 attachable to the ink head 40; a suction channel 73 provided with a suction pump 74 and a downstream pressure sensor 75; and a control device 90. The control device 90 includes: a suction-pressure acquiring unit 94 that acquires a suction pressure value P1 detected by the downstream pressure sensor 75, while a suction process is performed, with the cap 71 attached to the ink head 40; a range determining unit 95 that determines whether the suction pressure value P1 is within a reference pressure range SR1 or not; and a pump adjusting unit 96 that adjusts a rotational speed of the suction pumps 74 so that a suction pressure value P1 falls within the reference pressure range SR1 when the range determining unit 95 determines that the suction pressure value P1 is outside the reference pressure range SR1.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an inkjet printer. [Background technology]

[0002] For example, Patent Document 1 discloses a printer equipped with a print head having nozzles for ejecting ink, a suction mechanism for sucking ink from the nozzles, and a pressure detection execution means for detecting abnormal pressure changes when the suction mechanism is activated when an index value related to the continued use of the suction mechanism reaches a predetermined value. The suction mechanism has a cap attached to the print head and a suction pump connected to the cap.

[0003] When the index value for the continued use of the suction mechanism reaches a predetermined value, abnormalities in pressure changes such as leaks can be detected when the suction mechanism is activated. This allows the suction mechanism to be used until the end of its life, preventing unnecessary replacement of the suction mechanism before its life expires. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-190244 Summary of the Invention [Problem to be solved by the invention]

[0005] In the suction mechanism, even when the suction pump connected to the cap is controlled to rotate at the same speed, the amount of ink suctioned during a given suction time can vary. For example, the amount of ink suctioned can vary depending on the room environment, such as the temperature and humidity, in which the printer is installed, even when the suction pump operates at the same suction speed. If the required amount of ink cannot be suctioned from the nozzles, the suction process may not be performed correctly.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an inkjet printer that can properly perform the suction process. [Means for solving the problem]

[0007] The inkjet printer according to the present invention includes an ink head having nozzles for ejecting ink, a cap attachable to the ink head to cover the nozzles, a moving mechanism configured to attach and detach the cap from the ink head, a suction flow path connected to the cap, a suction pump provided in the suction flow path, a downstream pressure sensor for detecting a suction pressure value in the suction flow path between the cap and the suction pump, and a control device. The control device includes a suction control unit, a memory unit, a suction pressure acquisition unit, a range determination unit, and a pump adjustment unit. The suction control unit executes a suction process by driving the suction pump with the cap attached to the ink head. The memory unit pre-sets a reference pressure value in the suction flow path corresponding to the elapsed suction time from the start time of the suction process, and pre-stores a reference pressure range between an upper limit pressure value and a lower limit pressure value based on the reference pressure value corresponding to the elapsed suction time. The suction pressure acquisition unit acquires the suction pressure value detected by the downstream pressure sensor during the suction process. The range determination unit determines whether the suction pressure value over the elapsed suction time is within the reference pressure range. When the range determination unit determines that the suction pressure value is outside the reference pressure range, the pump adjustment unit adjusts the rotation speed of the suction pump so that the suction pressure value falls within the reference pressure range.

[0008] According to the inkjet printer, the rotation speed of the suction pump is adjusted during the suction process so that the suction pressure value in the suction flow path falls within a reference pressure range. Therefore, even if the resistance of the suction flow path changes due to, for example, the indoor environment in which the inkjet printer is installed, the rotation speed of the suction pump is adjusted, so that only the amount of ink required for the suction process can be sucked in. Therefore, even if the resistance in the suction flow path changes, for example, the suction process can be performed normally, making it less likely that the ink head will malfunction. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an inkjet printer that can properly perform the suction process. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a front view showing a printer according to an embodiment. [Figure 2] FIG. 2 is a bottom view schematically illustrating the configuration of the bottom surface of the carriage and the ink head. [Figure 3] FIG. 1 is a block diagram of a printer according to an embodiment. [Figure 4] FIG. 2 is a conceptual diagram showing the relationship between an ink head and an ink supply unit. [Figure 5] FIG. 2 is a schematic diagram showing the configuration of an ink head and an ink supply unit. [Figure 6] FIG. 2 is a front view showing a carriage, an ink head, and a cap unit. [Figure 7] FIG. 2 is a front view showing a carriage, an ink head, and a cap unit. [Figure 8] FIG. 2 is a front view showing an ink head, an ink supply unit, and a cap, showing a state in which the cap is separated from the ink head. [Figure 9] FIG. 10 is a front view showing the ink head, the ink supply unit, and the cap during a suction process. [Figure 10] 10 is a flowchart showing a control procedure when a suction process is performed. [Figure 11] FIG. 10 is a diagram showing a reference pressure range depending on the elapsed suction time of the suction process. [Figure 12] 10A and 10B are diagrams showing ink consumption amounts over time during suction processing. [Figure 13] FIG. 12 is a diagram showing the suction pressure value over the suction elapsed time of the suction process, and corresponds to FIG. 11. [Figure 14] FIG. 13 is a diagram showing the amount of ink consumed over the elapsed suction time of the suction process, and corresponds to FIG. 12. [Figure 15] FIG. 10 is a diagram showing an abnormality location that may cause an abnormality in the suction process. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of an inkjet printer according to the present invention will be described with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any particular way. Furthermore, the same reference numerals are used to designate components and parts that perform the same functions, and redundant descriptions will be omitted or simplified as appropriate.

[0012] An inkjet printer (hereinafter simply referred to as the printer) 10 according to this embodiment will be described below. FIG. 1 is a front view of the printer 10 according to this embodiment. FIG. 2 is a bottom view schematically illustrating the configuration of the bottom of the carriage 17 and ink head 40 of the printer 10. FIG. 3 is a block diagram of the printer 10 according to this embodiment. In the following description, left, right, top, and bottom refer to the left, right, top, and bottom, respectively, as seen from a user standing in front of the printer 10. The side of the printer 10 approaching the user is referred to as the front, and the side away from the user is referred to as the rear. The symbols F, Rr, L, R, U, and D in the drawings respectively indicate the front, rear, left, right, top, and bottom of the printer 10. The symbol Y in the drawings indicates the main scanning direction. In this embodiment, the main scanning direction Y is the left-right direction. The symbol X in the drawings indicates the sub-scanning direction. In this embodiment, the sub-scanning direction X is the front-to-back direction, a direction that intersects (here, perpendicular to) the main scanning direction Y in a plan view. The symbol Z in the drawings indicates the up-down direction or height direction. However, these directions are merely defined for the convenience of explanation, and do not limit the installation mode of the printer 10 or the present invention in any way.

[0013] Printer 10 is an inkjet printer. Printer 10 prints on medium 5 as shown in FIG. 1. Medium 5 is, for example, rolled recording paper, commonly known as roll paper. However, medium 5 is not limited to rolled recording paper. For example, medium 5 may be paper such as plain paper or inkjet printing paper, or may be a sheet or film made of resin such as polyvinyl chloride or polyester, a board, a fabric such as woven fabric or nonwoven fabric, or other medium.

[0014] As shown in FIG. 1, the printer 10 includes a printer body 11, a platen 13, a transport mechanism 20, a guide rail 15, a carriage 17, a head moving mechanism 30, an ink head 40 (see FIG. 2), an ink supply unit 50 (see FIG. 5), a cap unit 70 (see FIG. 6), and a control device 90.

[0015] The printer body 11 has a casing that extends in the main scanning direction Y. The printer body 11 is supported by legs 12. The legs 12 are provided on the bottom surface of the printer body 11 and extend downward from the bottom surface of the printer body 11.

[0016] The platen 13 supports the medium 5. The platen 13 extends in the main scanning direction Y and the sub-scanning direction X. Here, the medium 5 is placed on the upper surface of the platen 13. Printing is performed on the medium 5 on the platen 13.

[0017] The medium 5 supported on the platen 13 is transported in the sub-scanning direction X by a transport mechanism 20. The configuration of the transport mechanism 20 is not particularly limited. In this embodiment, the transport mechanism 20 includes a pinch roller 21, a grit roller 22, and a feed motor 23. The pinch roller 21 is located above the platen 13 and below the guide rail 15, and presses down on the medium 5 from above. The pinch roller 21 is located behind the carriage 17 in a plan view. The grit roller 22 is located on the platen 13 and is a member with a cylindrical outer periphery. The grit roller 22 is embedded in the platen 13 with its upper surface exposed. The grit roller 22 faces the pinch roller 21. A feed motor 23 is connected to the grit roller 22. When the feed motor 23 is driven with the medium 5 sandwiched between the pinch roller 21 and the grit roller 22, the grit roller 22 rotates. As a result, the medium 5 on the platen 13 is transported in the sub-scanning direction X.

[0018] The guide rail 15 is disposed above the platen 13. The guide rail 15 is disposed parallel to the upper surface of the platen 13 and extends in the main scanning direction Y. A carriage 17 is engaged with the guide rail 15. The carriage 17 is slidably provided on the guide rail 15 and is configured to be movable in the main scanning direction Y.

[0019] The head moving mechanism 30 is a mechanism that moves the carriage 17 and the ink head 40 (see FIG. 2) relative to the medium 5 supported by the platen 13 in the main scanning direction Y. Here, the head moving mechanism 30 moves the carriage 17 and the ink head 40 in the main scanning direction Y. The configuration of the head moving mechanism 30 is not particularly limited.

[0020] In this embodiment, as shown in FIG. 1, the head moving mechanism 30 includes left and right pulleys 31a and 31b, a belt 32, and a scan motor 33. The left pulley 31a is provided around the left end of the guide rail 15. The right pulley 31b is provided around the right end of the guide rail 15. The belt 32 is, for example, an endless belt, and is wound around the left and right pulleys 31a and 31b. The carriage 17 is fixedly attached to the belt 32. A scan motor 33 is connected to the right pulley 31b. Here, when the scan motor 33 is driven, the right pulley 31b rotates and the belt 32 moves. As a result, the carriage 17 and the ink head 40 move along the guide rail 15 in the main scanning direction Y.

[0021] As shown in FIG. 2, the ink heads 40 are provided on the carriage 17. The ink heads 40 are supported by the carriage 17 so that their bottom surfaces are exposed downward. There is no particular limitation on the number of ink heads 40. In this embodiment, there are four ink heads 40. The four ink heads 40 are arranged side by side in the main scanning direction Y.

[0022] In the following description, the four ink heads 40 will also be referred to, from left to right, as the first ink head 41, the second ink head 42, the third ink head 43, and the fourth ink head 44. The ink heads 40 include the first ink head 41, the second ink head 42, the third ink head 43, and the fourth ink head 44. In the following description, when describing all of the first ink head 41 to the fourth ink head 44 in common, the term "ink head 40" will be used as appropriate.

[0023] As shown in FIG. 2, each of the ink heads 40 (specifically, each of the first ink head 41 to the fourth ink head 44) has a nozzle surface 45. The nozzle surface 45 forms the bottom surface of the ink head 40. Nozzles 46 are formed in each nozzle surface 45. The nozzles 46 include first nozzles 46a and second nozzles 46b. A plurality of the first nozzles 46a are formed in the nozzle surface 45, and the plurality of first nozzles 46a are arranged side by side in the sub-scanning direction X. A plurality of the second nozzles 46b are also formed in the nozzle surface 45, and the plurality of second nozzles 46b are arranged side by side in the sub-scanning direction X.

[0024] Here, in each nozzle surface 45, the row of the multiple first nozzles 46a is referred to as the first nozzle row 48, and the row of the multiple second nozzles 46b is referred to as the second nozzle row 49. The nozzle rows 48, 49 are aligned in the main scanning direction Y. Each of the first ink head 41 to the fourth ink head 44 has two nozzle rows 48, 49. Here, the total number of nozzle rows, including the first nozzle row 48 and the second nozzle row 49, is eight. Note that the number of nozzle rows provided in one ink head 40 is not limited to two, and may be one, or three or more.

[0025] FIG. 4 is a conceptual diagram showing the relationship between the ink head 40 and the ink supply unit 50. In this embodiment, as shown in FIG. 4, the ink supply unit 50 is a unit that supplies ink to the ink head 40 (e.g., nozzles 46). The ink supply unit 50 is connected to the nozzles 46 of the ink head 40. Here, the ink supply unit 50 has a first ink supply unit 51 that supplies ink to the first nozzles 46a of the ink head 40 and a second ink supply unit 52 that supplies ink to the second nozzles 46b of the ink head 40. The ink supply unit 50 (here, the first ink supply unit 51 and the second ink supply unit 52) are connected to the first ink head 41 to the fourth ink head 44. The number of first ink supply units 51 is four, which is the same as the number of first nozzle rows 48 (see FIG. 2) composed of the first nozzles 46a. The number of second ink supply units 52 is four, which is the same as the number of second nozzle rows 49 (see FIG. 2) composed of the second nozzles 46b. Therefore, the number of ink supply units 50 here is eight.

[0026] 5 is a schematic diagram showing the configuration of the ink head 40 and the ink supply unit 50. The ink supply unit 50 has an ink tank 55, an ink supply path 56, a liquid feed pump 57, a damper 58, and an upstream pressure sensor 59. The ink tank 55 is a container that stores ink. The ink tank 55 may be, for example, an ink cartridge or a pouch-like bag.

[0027] The ink contained in the ink tank 55 is, for example, one of a process color ink and a spot color ink. Here, process color inks include, for example, cyan ink, magenta ink, yellow ink, and black ink. Spot color inks are inks of colors other than the process color inks. Spot color inks include, for example, white ink, clear ink, gloss ink, primer ink, fluorescent ink, metallic ink, orange ink, red ink, violet ink, blue ink, and green ink. However, the color of the ink contained in the ink tank 55 is not particularly limited. Furthermore, the ink material is also not particularly limited, and various materials conventionally used as ink materials for inkjet printers can be used. The ink may be, for example, a solvent-based pigment ink or an aqueous pigment ink. Alternatively, the ink may be an aqueous dye ink or an ultraviolet-curable ink that cures when exposed to ultraviolet light.

[0028] 5, the ink tank 55 has a first ink tank 55a and a second ink tank 55b. The first ink tank 55a constitutes part of the first ink supply unit 51 and is connected to the first nozzles 46a (here, the first nozzle row 48 (see FIG. 2)). The second ink tank 55b constitutes part of the second ink supply unit 52 and is connected to the second nozzles 46b (here, the second nozzle row 49 (see FIG. 2)).

[0029] The ink supply path 56 is a flow path that connects the ink tank 55 and the ink head 40 (in other words, the nozzle 46). The ink supply path 56 supplies the ink stored in the ink tank 55 to the ink head 40. One end of the ink supply path 56 is connected to the ink tank 55. The other end of the ink supply path 56 is connected to the ink head 40 (in other words, the nozzle 46). The configuration of the ink supply path 56 is not particularly limited. Here, the ink supply path 56 is configured by a flexible tube.

[0030] In this embodiment, the ink supply path 56 has a first ink supply path 56a and a second ink supply path 56b. The first ink supply path 56a constitutes a part of the first ink supply unit 51, and the second ink supply path 56b constitutes a part of the second ink supply unit 52. One end of the first ink supply path 56a is connected to the first ink tank 55a, and the other end is connected to the first nozzle 46a of the ink head 40. Ink stored in the first ink tank 55a is supplied to the first nozzle 46a through the first ink supply path 56a. One end of the second ink supply path 56b is connected to the second ink tank 55b, and the other end is connected to the second nozzle 46b of the ink head 40. Ink stored in the second ink tank 55b is supplied to the second nozzle 46b through the second ink supply path 56b.

[0031] The liquid feed pump 57 is provided in the ink supply path 56 (for example, in a middle portion of the ink supply path 56). The liquid feed pump 57 is a pump that supplies ink stored in the ink tank 55 to the ink head 40 and adjusts the pressure to a level suitable for ejecting ink from the nozzles 46. When driven, the liquid feed pump 57 feeds ink from the ink tank 55 toward the ink head 40. Note that there are no particular limitations on the type of liquid feed pump 57. Here, the liquid feed pump 57 is realized by, for example, a diaphragm pump or a tube pump.

[0032] 5, the liquid feed pump 57 includes a first liquid feed pump 57a and a second liquid feed pump 57b. The first liquid feed pump 57a constitutes part of the first ink supply unit 51. The first liquid feed pump 57a is provided in the first ink supply path 56a and feeds ink from the first ink tank 55a toward the first nozzles 46a of the ink head 40. The second liquid feed pump 57b constitutes part of the second ink supply unit 52. The second liquid feed pump 57b is provided in the second ink supply path 56b and feeds ink from the second ink tank 55b toward the second nozzles 46b of the ink head 40.

[0033] The damper 58 reduces pressure fluctuations in the ink, stabilizing the ejection of ink from the nozzles 46. For example, the operation of the liquid feed pump 57 is controlled according to the flow rate of ink flowing into the damper 58 (in other words, the pressure inside the damper 58). The damper 58 is connected to the ink head 40 (here, the nozzles 46). The damper 58 is connected to the ink supply channel 56, and the ink supply channel 56 is connected to the ink head 40 via the damper 58. Here, the damper 58 is provided above the ink head 40.

[0034] In this embodiment, the damper 58 has a first damper 58a and a second damper 58b. The first damper 58a constitutes part of the first ink supply unit 51 and is connected to the first nozzle 46a of the ink head 40. The second damper 58b constitutes part of the second ink supply unit 52 and is connected to the second nozzle 46b of the ink head 40. The first damper 58a and the second damper 58b are arranged side by side above the ink head 40.

[0035] The configuration of the damper 58 (specifically, the first damper 58a and the second damper 58b) is not particularly limited. In this embodiment, the damper 58 has an ink chamber 60 in which ink is temporarily stored. The ink chamber 60 expands and contracts depending on the amount of ink stored therein. Here, the pressure in the ink chamber 60 changes depending on the amount of ink stored therein. For example, when the amount of ink in the ink chamber 60 increases, the ink chamber 60 becomes larger and the pressure increases. On the other hand, when the amount of ink in the ink chamber 60 decreases, the ink chamber 60 becomes smaller and the pressure decreases. In the following description, the pressure in the ink chamber 60 will also be referred to as the pressure inside the damper 58 or the pressure of the damper 58. The ink chamber 60 is connected to the ink supply channel 56 and the ink head 40. Although not shown, the ink chamber 60 has an inlet connected to the ink supply channel 56 and an outlet connected to the ink head 40.

[0036] In this embodiment, the ink chamber 60 of the first damper 58a communicates with the first ink supply path 56a and the first nozzle 46a of the ink head 40. The ink chamber 60 of the second damper 58b communicates with the second ink supply path 56b and the second nozzle 46b of the ink head 40.

[0037] The upstream pressure sensor 59 detects the pressure inside the damper 58. Here, as described above, "the pressure inside the damper 58" means the pressure inside the ink chamber 60 that constitutes the damper 58. The upstream pressure sensor 59 detects the pressure inside the damper 58 based on, for example, the size of the ink chamber 60 (for example, the degree of expansion and contraction).

[0038] In this embodiment, the upstream pressure sensor 59 has a first upstream pressure sensor 59a and a second upstream pressure sensor 59b. The first upstream pressure sensor 59a constitutes part of the first ink supply unit 51 and detects the pressure inside the first damper 58a. The second upstream pressure sensor 59b constitutes part of the second ink supply unit 52 and detects the pressure inside the second damper 58b.

[0039] Next, the cap unit 70 will be described. Figures 6 and 7 are front views showing the carriage 17, ink head 40, and cap unit 70. Figures 8 and 9 are front views showing the ink head 40, ink supply unit 50, and cap 71. As shown in Figure 6, the cap unit 70 has a cap 71, a movement mechanism 72, a suction flow path 73, a suction pump 74, and a downstream pressure sensor 75.

[0040] As shown in FIG. 9, the caps 71 can be attached to the ink heads 40 so as to cover the nozzles 46. As shown in FIG. 7, one cap 71 is attached to one ink head 40. Therefore, the number of caps 71 is four, the same as the number of ink heads 40. In this embodiment, the caps 71 include a first cap 71A, a second cap 71B, a third cap 71C, and a fourth cap 71D. The first cap 71A, the second cap 71B, the third cap 71C, and the fourth cap 71D are attached to the first ink head 41, the second ink head 42, the third ink head 43, and the fourth ink head 44, respectively. In the following description, the term "cap 71" will be used appropriately when describing all of the first cap 71A to the fourth cap 71D in common.

[0041] In this embodiment, as shown in FIG. 8, the cap 71 has a lip portion 76. The lip portion 76 forms the upper end of the cap 71. As shown in FIG. 9, when the cap 71 is attached to the ink head 40, the lip portion 76 is the portion that comes into contact with the nozzle surface 45. The lip portion 76 is annular. The width of the lip portion 76 decreases toward the upper end. Here, the "width of the lip portion 76" refers to the length in a direction perpendicular to the circumferential direction of the lip portion 76 in a plan view. The lip portion 76 has a tapered shape.

[0042] The lip portion 76 is elastically deformable. Therefore, when the lip portion 76 comes into contact with the nozzle surface 45 of the ink head 40, it may be elastically deformed. The specific material from which the lip portion 76 is formed is not particularly limited. In this embodiment, the lip portion 76 is made of rubber. Specifically, the lip portion 76 is formed of ethylene propylene diene rubber (EPDM) or butyl rubber. Here, the portions of the cap 71 other than the lip portion 76 are also made of rubber.

[0043] An absorber 77 is provided inside the cap 71. The absorber 77 is housed in the cap 71. The absorber 77 is a member that receives ink when the ink is ejected (or discharged, or sucked) from the ink head 40 into the cap 71. The ink received by the absorber 77 is absorbed by the absorber 77. The absorber 77 is positioned below the upper end of the lip portion 76. The lip portion 76 protrudes upward from the absorber 77. The material from which the absorber 77 is made is not particularly limited as long as it absorbs ink. Here, the absorber 77 is made of a porous material. For example, the absorber 77 is a sponge made of polyvinyl alcohol (PVA sponge).

[0044] As shown in Figures 6 and 7, the movement mechanism 72 is a mechanism that attaches and detaches the cap 71 to and from the ink head 40. The movement mechanism 72 is a mechanism that raises and lowers the cap 71 relative to the ink head 40. As shown in Figure 7, for example, the cap 71 is attached to the ink head 40 by raising it. On the other hand, as shown in Figure 6, the cap 71 is separated from the ink head 40 by lowering it.

[0045] The configuration of the movement mechanism 72 is not particularly limited. In this embodiment, the movement mechanism 72 has a support member 78 and a lifting motor 79. The support member 78 is, for example, a plate-like member that extends in the main scanning direction Y and the sub-scanning direction X, and supports the first cap 71A to the fourth cap 71D. The lifting motor 79 is connected to the support member 78. Here, the support member 78 is raised and lowered by driving the lifting motor 79. As the support member 78 is raised and lowered, the first cap 71A to the fourth cap 71D are raised and lowered simultaneously. Then, as the first cap 71A to the fourth cap 71D are raised and lowered, the caps 71 can be attached to or separated from the nozzle surface 45 collectively.

[0046] As shown in FIG. 7 , the suction channel 73 is a channel through which ink passes when ink is discharged from the cap 71. The suction channel 73 is connected to the cap 71. Here, one end of the suction channel 73 is connected to the cap 71, and the other end of the suction channel 73 is connected to a waste tank (not shown). Therefore, ink discharged from the cap 71 passes through the suction channel 73 and is discharged to the waste tank. Here, the suction channel 73 has a first suction channel 73A, a second suction channel 73B, a third suction channel 73C, and a fourth suction channel 73D. The first suction channel 73A, the second suction channel 73B, the third suction channel 73C, and the fourth suction channel 73D are connected to the first cap 71A, the second cap 71B, the third cap 71C, and the fourth cap 71D, respectively. In the following description, the term suction channel 73 will be used appropriately when describing all of the first suction channel 73A to the fourth suction channel 73D in common. There is no particular limitation on the type of suction channel 73. Here, suction channel 73 is configured by a flexible tube.

[0047] The suction pump 74 is provided in the suction flow path 73. The suction pump 74 sucks ink from the cap 71 to which it is connected and from the ink head 40 attached to the cap 71 to which it is connected. Here, one suction pump 74 is provided for each cap 71. In this embodiment, the suction pump 74 includes a first suction pump 74A, a second suction pump 74B, a third suction pump 74C, and a fourth suction pump 74D. The first suction pump 74A, the second suction pump 74B, the third suction pump 74C, and the fourth suction pump 74D are provided in the first suction flow path 73A, the second suction flow path 73B, the third suction flow path 73C, and the fourth suction flow path 73D, respectively. In the following description, the term "suction pump 74" will be used appropriately when describing all of the first suction pump 74A to the fourth suction pump 74D in common.

[0048] 7, for example, when the suction pump 74 is driven with the cap 71 attached to the ink head 40, as shown in FIG. 9, a negative pressure lower than the negative pressure in the ink supply channel 56 connected to the ink head 40 is created in the cap 71. This causes ink to be sucked from the nozzles 46 (first nozzle 46a and second nozzle 46b in this case), and the ink in the ink head 40 is discharged into the cap 71. The ink and other materials in the cap 71 that have been sucked into the suction pump 74 are discharged into a waste tank via the suction channel 73.

[0049] As shown in FIG. 6 , the downstream pressure sensor 75 is provided in the suction flow path 73. The downstream pressure sensor 75 detects the suction pressure value in the portion of the suction flow path 73 between the cap 71 and the suction pump 74. Here, the downstream pressure sensor 75 is provided in the middle of the suction flow path 73, between the cap 71 and the suction pump 74. The type of downstream pressure sensor 75 is not particularly limited, and in this embodiment, the downstream pressure sensor 75 is an optical sensor. Here, the downstream pressure sensor 75 includes a first downstream pressure sensor 75A, a second downstream pressure sensor 75B, a third downstream pressure sensor 75C, and a fourth downstream pressure sensor 75D. The first downstream pressure sensor 75A, the second downstream pressure sensor 75B, the third downstream pressure sensor 75C, and the fourth downstream pressure sensor 75D detect the suction pressure values in the first suction flow path 73A, the second suction flow path 73B, the third suction flow path 73C, and the fourth suction flow path 73D, respectively. In the following description, when describing all of the first to fourth downstream pressure sensors 75A to 75D in common, the term downstream pressure sensor 75 will be used as appropriate.

[0050] 1, an operation panel 80 is provided on the right end of the printer body 11 of the printer 10. The operation panel 80 is provided with a display screen 81 that displays the status of the printer 10, operation keys 82 that are operated by the user, and the like.

[0051] Next, the control device 90 will be described. The control device 90 is a device that performs control related to printing and control of suctioning ink from the ink head 40. The configuration of the control device 90 is not particularly limited. The control device 90 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited. The control device 90 includes, for example, an I / F, a CPU, a ROM, and a RAM. The control device 90 is provided inside the printer main body 11. However, the control device 90 may also be realized by a computer or the like installed outside the printer main body 11. In this case, the control device 90 is connected to a control board (not shown) of the printer 10 via wired or wireless communication so as to be able to communicate with it.

[0052] 3, the control device 90 is communicatively connected to the transport mechanism 20 (more specifically, the feed motor 23), the head moving mechanism 30 (more specifically, the scan motor 33), the ink heads 40 (more specifically, the first ink head 41 to the fourth ink head 44 (see FIG. 2)), the liquid feed pump 57, the upstream pressure sensor 59, the movement mechanism 72 of the cap unit 70 (more specifically, the lift motor 79), the suction pump 74 of the cap unit 70, the downstream pressure sensor 75, and the operation panel 80. The control device 90 controls the transport mechanism 20, the head moving mechanism 30, the ink heads 40, the liquid feed pump 57, the upstream pressure sensor 59, the movement mechanism 72, the suction pump 74, the downstream pressure sensor 75, and the operation panel 80.

[0053] In the printer 10 according to this embodiment, a cleaning process is performed on the ink head 40 to prevent ejection abnormalities from occurring in the nozzles 46 of the ink head 40. Here, ejection abnormalities in the nozzles 46 refer to abnormalities such as distortion of ink ejected from the nozzles 46 or missing nozzles where ink is not ejected, which degrade print quality.

[0054] The cleaning process includes a suction process, which is a process of suctioning ink from the nozzles 46 with the caps 71 attached to the ink heads 40, as shown in Figure 9. In the suction process, the rotation speed of the suction pump 74 is controlled so that a predetermined amount of ink is sucked from one ink head 40, for example, within a predetermined suction time.

[0055] However, variations in the amount of ink consumed over a given suction time can occur even at the same rotation speed of the suction pump 74. The causes of variations in the amount of ink consumed are thought to be changes in the resistance within the suction flow path 73 due to factors such as the indoor environment (particularly temperature) such as the temperature and humidity of the room in which the printer 10 is installed, individual differences in the nozzles 46 of the ink head 40 (for example, variations in the size of the nozzles 46), and the viscosity of the ink ejected from the nozzles 46.

[0056] Therefore, in this embodiment, the suction process is performed so that there is little difference in the time required to suck a predetermined amount of ink. To perform the suction process, as shown in FIG. 3, the control device 90 includes a memory unit 91, a capping control unit 92, a suction control unit 93, a suction pressure acquisition unit 94, a range determination unit 95, a pump adjustment unit 96, a time extension unit 97, and an error processing unit 98. The error processing unit 98 includes a damper pressure acquisition unit 98A, a first determination unit 98B, a second determination unit 98C, and a third determination unit 98D. Each of the above-described components of the control device 90 may be implemented by software or hardware. For example, each component of the control device 90 may be implemented by one or more processors, or may be incorporated into a circuit.

[0057] Next, the control procedure for executing the suction process in the printer 10 according to this embodiment will be described with reference to the flowchart in Figure 10. Here, the suction process is performed on the first ink head 41 to the fourth ink head 44.

[0058] FIG. 11 is a diagram showing the reference pressure range SR1 associated with the elapsed suction time T1 of the suction process. FIG. 12 is a diagram showing the ink consumption amount V1 associated with the elapsed suction time T1 of the suction process. As shown in FIG. 11, the storage unit 91 in FIG. 3 pre-stores the reference pressure range SR1 associated with the elapsed suction time T1 from the start time t11 when the suction process is started. The reference pressure range SR1 is the allowable range of the suction pressure value P1 in the suction flow path 73 associated with the elapsed suction time T1. The specific range within the reference pressure range SR1 changes depending on the specific time of the elapsed suction time T1.

[0059] Here, a reference pressure value SP1 in the suction flow path 73 corresponding to the suction elapsed time T1 from the start time t11 when the suction process is started is preset. For example, in this embodiment, the suction process is a process in which ink is suctioned from one ink head 40 by a predetermined reference ink consumption amount SV1 during a predetermined reference elapsed time ST1, as shown in FIG. 12. The reference pressure value SP1 shown in FIG. 11 is the magnitude of the pressure in the suction flow path 73 corresponding to the suction elapsed time T1 when the suction process is performed so that ink is suctioned by the reference ink consumption amount SV1 during the reference elapsed time ST1. Here, because the suction pump 74 continues to rotate (in other words, continues to be driven) during the suction process, the pressure (here, negative pressure) in the suction flow path 73 gradually decreases over time during the suction process.

[0060] As shown in FIG. 11, the reference pressure range SR1 is determined based on the reference pressure value SP1. An upper limit pressure value SP11 and a lower limit pressure value SP12 are set in the reference pressure range SR1. The upper limit pressure value SP11 indicates the upper limit value of the reference pressure range SR1, and the lower limit pressure value SP12 indicates the lower limit value of the reference pressure range SR1. The reference pressure value SP1 is a value within the reference pressure range SR1 and is located between the upper limit pressure value SP11 and the lower limit pressure value SP12. Here, the reference pressure value SP1 is an intermediate value between the upper limit pressure value SP11 and the lower limit pressure value SP12. In other words, at a certain elapsed time within the suction elapsed time T1, the difference between the upper limit pressure value SP11 and the reference pressure value SP1 is the same as the difference between the reference pressure value SP1 and the lower limit pressure value SP12.

[0061] In controlling the suction process, first, in step S101 of FIG. 10, the capping control unit 92 of FIG. 3 controls the moving mechanism 72 (see FIG. 6) to attach the caps 71 to the ink heads 40, as shown in FIG. 9. Here, the capping control unit 92 controls the head moving mechanism 30 (see FIG. 1) to position the first ink head 41 to the fourth ink head 44 directly above the first cap 71A to the fourth cap 71D, respectively, as shown in FIG. 6. Thereafter, the capping control unit 92 drives the lift motor 79 of the moving mechanism 72 to lift the first cap 71A to the fourth cap 71D. As a result, the first cap 71A to the fourth cap 71D are attached to the first ink head 41 to the fourth ink head 44, respectively, as shown in FIG. 7.

[0062] Next, in step S103 of FIG. 10, the suction process is started. In step S103, the suction control unit 93 of FIG. 3 drives the suction pump 74 with the caps 71 attached to the ink heads 40, as shown in FIG. 7. In this embodiment, the first suction pump 74A to the fourth suction pump 74D are simultaneously driven with the first cap 71A to the fourth cap 71D attached to the first ink head 41 to the fourth ink head 44, respectively. Therefore, the suction process is simultaneously started for the first ink head 41 to the fourth ink head 44. Note that in this embodiment, the suction process is simultaneously started for the first ink head 41 to the fourth ink head 44, but specific control during the suction process from step S103 onward of FIG. 10 is performed individually, i.e., independently, for the first ink head 41 to the fourth ink head 44. Here, the suction process is controlled in the same way for the first ink head 41 to the fourth ink head 44. Therefore, in the following description, the suction processes for the first ink head 41 to the fourth ink head 44 will not be distinguished from each other, and will be described simply as control of the suction process for the ink head 40.

[0063] In this embodiment, the time when the suction process is started in step S103 (i.e., the time when the suction pump 74 is driven) is the start time t11 shown in Fig. 11. The time that has elapsed since the start time t11 during the suction process is the suction elapsed time T1.

[0064] Next, in step S105 of FIG. 10, a suction pressure value P1 is acquired. Here, the suction pressure acquisition unit 94 of FIG. 3 acquires the suction pressure value P1 detected by the downstream pressure sensor 75 (see FIG. 7). The suction pressure acquisition unit 94 transmits an acquisition signal to, for example, the downstream pressure sensor 75. After receiving the acquisition signal, the downstream pressure sensor 75 detects the suction pressure value P1 in the suction flow path 73 and then transmits the suction pressure value P1 to the suction pressure acquisition unit 94. As a result, the suction pressure acquisition unit 94 acquires the suction pressure value P1 from the downstream pressure sensor 75. The suction pressure value P1 acquired by the suction pressure acquisition unit 94 is stored in the memory unit 91 of FIG. 3.

[0065] Next, in step S107 of FIG. 10, the range determination unit 95 of FIG. 3 determines whether the suction pressure value P1 is within the reference pressure range SR1. Here, the reference pressure range SR1 is the allowable range of pressure (here, negative pressure) that occurs over the course of the suction elapsed time T1, as shown in FIG. 11. For example, as shown in FIG. 11, if the time at which the suction pressure value P1 is acquired is time t12, the suction elapsed time T1 is the time from time t11 to time t12. In this case, the range determination unit 95 determines whether the suction pressure value P1 is within the reference pressure range SR1 at time t12.

[0066] If the suction pressure value P1 is within the reference pressure range SR1, the process proceeds to step S109 in FIG. 10. On the other hand, if the suction pressure value P1 is outside the reference pressure range SR1, the process proceeds to step S115 in FIG. 10. In this embodiment, the range determination unit 95 performs a determination for each suction process for each ink head 40. That is, the range determination unit 95 determines whether the suction pressure value P1 is within the reference pressure range SR1 for each of the first through fourth suction paths 73A through 73D. Then, for the suction process for an ink head 40 whose suction pressure value P1 is determined to be within the reference pressure range SR1 among the suction processes for the first through fourth ink heads 41 through 44, the process proceeds to step S109. On the other hand, for the suction process for an ink head 40 whose suction pressure value P1 is determined to be outside the reference pressure range SR1 among the suction processes for the first through fourth ink heads 41 through 44, the process proceeds to step S115.

[0067] If it is determined in step S107 that the suction pressure value P1 is within the reference pressure range SR1, it is determined that the suction process is being performed normally. This "suction process is being performed normally" state refers to a state in which the amount of ink suctioned during the suction process (hereinafter referred to as ink consumption amount V1) becomes equal to the reference ink consumption amount SV1 when the suction elapsed time T1 reaches the reference elapsed time ST1, or at a time around that time, as shown in FIG. 12. If the suction process is being performed normally in this manner, the process proceeds to step S109. In the control from step S109 onwards, the time extension unit 97 in FIG. 3 ends the suction process when the ink consumption amount V1 due to the suction process (in other words, the ink consumption amount V1 from the start time t11) is equal to or exceeds the reference ink consumption amount SV1 when the suction elapsed time T1 reaches the reference elapsed time ST1. On the other hand, as in pattern PT11 in Figure 12, when the suction elapsed time T1 is the standard elapsed time ST1, if the ink consumption amount V1 due to the suction process is less than the standard ink consumption amount SV1, the time extension unit 97 extends the suction process until the ink consumption amount V1 becomes equal to or greater than the standard ink consumption amount SV1 (until time t13 in Figure 12).

[0068] Here, in step S109 of FIG. 10, the time extension unit 97 determines whether the suction elapsed time T1 from the start time t11 is equal to or greater than the reference elapsed time ST1. If the suction elapsed time T1 is less than the reference elapsed time ST1, the suction process is still in progress. In this case, the process returns to step S105 of FIG. 10, and the suction pressure acquisition unit 94 of FIG. 3 acquires the suction pressure value P1. On the other hand, if the suction elapsed time T1 is equal to or greater than the reference elapsed time ST1 in step S109, the process proceeds to step S111 of FIG. 10.

[0069] In step S111, the time extension unit 97 determines whether the ink consumption amount V1 is equal to or greater than the reference ink consumption amount SV1. Here, the ink consumption amount V1 is calculated based on the elapsed suction time T1 and the rotational speed of the suction pump 74. However, the ink consumption amount V1 may also be measured by a quantity measurement sensor (not shown) that is provided in the suction flow path 73 (see FIG. 7) and measures the amount of ink flowing through the suction flow path 73. In this embodiment, for example, when the rotational speed of the suction pump 74 is S1, the ink consumption amount V1 is calculated by the formula: ink consumption amount V1 = rotational speed S1 × elapsed suction time T1. Note that if the rotational speed S1 has been adjusted in the past, the ink consumption amount V1 for the entire suction process is calculated by calculating and adding up the ink consumption amount V1 for each rotational speed S1.

[0070] If it is determined in step S111 of Fig. 10 that the ink consumption amount V1 is equal to or greater than the reference ink consumption amount SV1, then the ink required for the suction process has been sucked out in the amount V1. In this case, the process proceeds to step S113 of Fig. 10, where the suction control unit 93 of Fig. 3 stops the suction pump 74 and ends the suction process.

[0071] On the other hand, if it is determined in step S111 that the ink consumption rate V1 is less than the reference ink consumption rate SV1, then, as shown in pattern PT11 in Fig. 12, even though the suction process has been performed for the reference elapsed time ST1, ink equivalent to the reference ink consumption rate SV1 has not been suctioned. In this case, the time extension unit 97 in Fig. 3 continues the suction process until the ink consumption rate V1 becomes equal to or greater than the reference ink consumption rate SV1, that is, extends the suction process beyond the reference elapsed time ST1 until time t13. In this case, the process returns to step S105, and the suction pressure acquisition unit 94 in Fig. 3 acquires the suction pressure value P1.

[0072] In this embodiment, if it is determined in step S107 of FIG. 10 that the suction pressure value P1 is outside the reference pressure range SR1, the rotation speed of the suction pump 74 is adjusted. First, in step S115 of FIG. 10, the error processing unit 98 of FIG. 3 determines whether the abnormality occurrence time T2 is equal to or greater than a predetermined reference error time ST2. This abnormality occurrence time T2 refers to the time during which the suction pressure value P1 continuously falls outside the reference pressure range SR1. The longer the abnormality occurrence time T2, the longer the suction pressure value P1 has remained outside the reference pressure range SR1, even after the rotation speed of the suction pump 74 has been adjusted. The abnormality occurrence time T2 is measured, for example, by a timer (not shown) provided in the control device 90. The reference error time ST2 is, for example, a fixed value, and is the reference time for determining that the suction process is not being performed normally. The reference error time ST2 is an appropriately set value and is pre-stored in the storage unit 91 of FIG. 3.

[0073] If it is determined in step S115 that the abnormality occurrence time T2 is less than the reference error time ST2, the process proceeds to step S117 in FIG. 10. In step S117, the pump adjustment unit 96 in FIG. 3 adjusts the rotation speed of the suction pump 74 so that the suction pressure value P1 falls within the reference pressure range SR1. For example, if the range determination unit 95 determines that the suction pressure value P1 is smaller than the lower limit pressure value SP12 of the reference pressure range SR1, the pump adjustment unit 96 adjusts the rotation speed of the suction pump 74 to decrease the rotation speed of the suction pump 74. On the other hand, if the range determination unit 95 determines that the suction pressure value P1 is greater than the upper limit pressure value SP11 of the reference pressure range SR1, the pump adjustment unit 96 adjusts the rotation speed of the suction pump 74 to increase the rotation speed of the suction pump 74. In this embodiment, an adjustment value S2 used in one adjustment of the rotation speed of the suction pump 74 is pre-stored in the storage unit 91 in FIG. 3. The pump adjustment unit 96 adjusts the rotation speed of the suction pump 74 to decrease by an adjustment value S2 when the suction pressure value P1 is smaller than the lower limit pressure value SP12, and adjusts the rotation speed of the suction pump 74 to increase by an adjustment value S2 when the suction pressure value P1 is larger than the upper limit pressure value SP11.

[0074] FIG. 13 is a diagram equivalent to FIG. 11, showing the suction pressure value P1 over time T1 of the suction process. FIG. 14 is a diagram equivalent to FIG. 12, showing the ink consumption amount V1 over time T1 of the suction process. For example, in the suction process pattern PT12 of FIG. 13, at time t21, the suction pressure value P1 becomes smaller than the lower limit pressure value SP12 of the reference pressure range SR1. Therefore, in the suction process pattern PT12, the rotation speed of the suction pump 74 is reduced at time t21, so that the slope of the suction pressure value P1 over time T1 becomes gentler after time t21, and the suction pressure value P1 falls within the reference pressure range SR1. As shown in FIG. 14, in the suction process pattern PT12, the rotation speed of the suction pump 74 is reduced at time t21, so that the slope of the ink consumption amount V1 over time T1 becomes gentler. Therefore, when the suction elapsed time T1 reaches the reference elapsed time ST1, the ink consumption amount V1 tends to be equal to or close to the reference ink consumption amount SV1.

[0075] On the other hand, as shown in FIG. 13, in suction process pattern PT13, at time t22, the suction pressure value P1 exceeds the upper limit pressure value SP11 of the reference pressure range SR1. Therefore, in pattern PT13, the rotation speed of the suction pump 74 is increased at time t22. From time t22 onward, the slope of the suction pressure value P1 as the suction elapsed time T1 elapses becomes steeper, and the suction pressure value P1 falls within the reference pressure range SR1. As shown in FIG. 14, in suction process pattern PT13, the rotation speed of the suction pump 74 is increased at time t22. Therefore, the slope of the ink consumption amount V1 as the suction elapsed time T1 elapses becomes steeper. Therefore, when the suction elapsed time T1 reaches the reference elapsed time ST1, the ink consumption amount V1 is likely to be at or near the reference ink consumption amount SV1. After adjusting the rotation speed of the suction pump 74 in this way, the process returns to step S105 in FIG. 10, and the suction pressure acquisition unit 94 in FIG. 3 acquires the suction pressure value P1.

[0076] If it is determined in step S115 of FIG. 10 that the abnormality occurrence time T2 is equal to or greater than the reference error time ST2, the process proceeds to step S119 of FIG. 10. In step S119, the error processing unit 98 of FIG. 3 executes a predetermined error process. Here, because the suction pressure value P1 has remained outside the reference pressure range SR1 for equal to or greater than the reference error time ST2, it is determined that an abnormality has occurred in the suction process, and the error processing is executed. Note that the specific error processing is not particularly limited, and may be, for example, processing to notify the user that an abnormality has occurred in the suction process. As the error processing, the error processing unit 98 displays an error message, for example, on the display screen 81 of the operation panel 80 (see FIG. 1). The error message is, for example, a message indicating that an abnormality has occurred in the suction process. By viewing the error message displayed on the display screen 81, the user can know that an abnormality has occurred in the suction process, and can make an inquiry to a customer center, for example.

[0077] In this embodiment, the error processing unit 98 can identify the location of the problem (hereinafter simply referred to as the abnormal location) that is causing the abnormality in the suction process. FIG. 15 is a diagram showing the abnormal location that is causing the abnormality in the suction process. Here, the abnormal location can be identified based on the damper pressure value P2 (see FIG. 15) acquired from the upstream pressure sensor 59 (see FIG. 5) provided in the damper 58 and the suction pressure value P1 (see FIG. 15) acquired from the downstream pressure sensor 75 (see FIG. 6) provided in the suction flow path 73.

[0078] In this embodiment, the error processing unit 98 acquires the suction pressure value P1 or the change amount C1 of the suction pressure value P1, and the damper pressure value P2 or the change amount C2 of the damper pressure value P2. Here, the suction pressure acquisition unit 94 in FIG. 3 acquires the suction pressure value P1 in the suction flow path 73 from the downstream pressure sensor 75 and calculates the change amount C1 of the suction pressure value P1 based on the acquired suction pressure value P1. The damper pressure acquisition unit 98A in the error processing unit 98 in FIG. 3 acquires the damper pressure value P2 of the ink chamber 60 of the damper 58 from the upstream pressure sensor 59 and calculates the change amount C2 of the damper pressure value P2 based on the acquired damper pressure value P2. Here, the change amount C1 of the suction pressure value P1 refers to the difference between the maximum and minimum values of the suction pressure value P1 obtained over a predetermined determination time. Similarly, the change amount C2 of the damper pressure value P2 refers to the difference between the maximum and minimum values of the damper pressure value P2 obtained over a predetermined determination time.

[0079] In this embodiment, as shown in Fig. 9, when the cap 71 is attached to the ink head 40, the first determination unit 98B determines that an abnormality has occurred between the damper 58 and the suction flow path 73, in this case, in the nozzle 46 or the cap 71, if the suction pressure value P1 is less than a predetermined error suction pressure value SV2 and the change C2 in the damper pressure value P2 is less than a predetermined error damper change SC2, as shown in Fig. 15. Note that, as shown in Fig. 9, if two dampers 58, such as the first damper 58a and the second damper 58b, are connected to one ink head 40, the above phrase "the change C2 in the damper pressure value P2 is less than the predetermined error damper change SC2" can be rephrased as "the change C2 in the damper pressure value P2 for both dampers 58a, 58b is less than the predetermined error damper change SC2."

[0080] Here, when the suction pressure value P1 is less than the error suction pressure value SV2, it means that the pressure in the suction flow path 73 is too negative, and the suction flow path 73 is in a state of abnormal negative pressure. The error suction pressure value SV2 is a reference value for determining whether the suction flow path 73 is in a state of abnormal negative pressure, and is pre-stored in the storage unit 91 of FIG. 3. When the change amount C2 in the damper pressure value P2 is less than the error damper change amount SC2, it means that there is no pressure fluctuation in the damper 58. The error damper change amount SC2 is a reference value for determining whether there is pressure fluctuation in the damper 58, and is pre-stored in the storage unit 91 of FIG. 3.

[0081] If it is determined that an abnormality has occurred in the nozzle 46 or the cap 71, the first determination unit 98B may determine whether the suction pressure value P1 when the cap 71 is separated from the ink head 40 (hereinafter also referred to as the suction pressure value P1 during separation) is less than the error suction pressure value SV2, as shown in FIG. 8. If the suction pressure value P1 during separation is less than the error suction pressure value SV2, the first determination unit 98B determines that an abnormality has occurred in the cap 71. An abnormality in the cap 71 may be, for example, ink clogging in the portion where ink flows from the cap 71 to the suction flow path 73. On the other hand, if the suction pressure value P1 during separation is equal to or greater than the error suction pressure value SV2, the first determination unit 98B determines that an abnormality has occurred in the nozzle 46. An abnormality in the nozzle 46 may be, for example, ink clogging in the nozzle 46.

[0082] When the cap 71 is attached to the ink head 40, the second determination unit 98C of the error processing unit 98 in FIG. 3 determines that an abnormality has occurred on the ink tank 55 side of the damper 58, in this case, upstream of the damper 58, when the suction pressure value P1 is less than the error suction pressure value SV2 (so-called negative pressure abnormality in the suction flow path 73) and the damper pressure value P2 is less than the error damper pressure value SV3, as shown in FIG. 15 . Here, when the damper pressure value P2 is less than the error damper pressure value SV3, the pressure of the damper 58 is too negative, meaning that the damper 58 is in a negative pressure abnormality state. The error damper pressure value SV3 is a reference value for determining whether the damper 58 is experiencing a negative pressure abnormality, and is stored in advance in the memory unit 91 in FIG. 3 . In this embodiment, an abnormality upstream of the damper 58 is, for example, an abnormality in the ink supply path 56, the liquid feed pump 57, or the ink tank 55. As shown in Figure 9, when two dampers 58, such as a first damper 58a and a second damper 58b, are connected to one ink head 40, the second judgment unit 98C may determine that an abnormality has occurred upstream of the target damper 58 whose damper pressure value P2 is less than the error damper pressure value SV3.

[0083] When the cap 71 is attached to the ink head 40, the third determination unit 98D of the error processing unit 98 in FIG. 3 determines that air is leaking between the ink head 40 and the cap 71 or that the suction pump 74 is malfunctioning if the change C1 in the suction pressure value P1 is less than the predetermined error suction change SC1 and the change C2 in the damper pressure value P2 is less than the predetermined error damper change SC2 (i.e., there is no pressure fluctuation in the damper 58), as shown in FIG. 15. In this case, it is considered that a gap has formed between the nozzle surface 45 of the ink head 40 and the lip portion 76 of the cap 71, causing air to leak through the gap, or that the suction pump 74 is not operating properly, preventing ink from being properly sucked. Here, when the change C1 in the suction pressure value P1 is less than the error suction change SC1, it means that there is no pressure fluctuation in the suction flow path 73. The error suction change SC1 is a reference value used to determine whether there is pressure fluctuation in the suction flow path 73 and is pre-stored in the memory unit 91 in FIG. 3.

[0084] As shown in Figure 9, when two dampers 58, such as a first damper 58a and a second damper 58b, are connected to one ink head 40, the above statement "the change amount C2 in the damper pressure value P2 is less than the predetermined error damper change amount SC2" can be rephrased as "the change amount C2 in the damper pressure value P2 in both dampers 58a and 58b is less than the predetermined error damper change amount SC2."

[0085] In this way, if the error processing unit 98 is able to determine the location that is causing the abnormality in the suction process, the user may be notified of information regarding the location that is determined to be the cause of the abnormality in the suction process during error processing.

[0086] As described above, in this embodiment, the inkjet printer 10 includes an ink head 40 having nozzles 46 that eject ink, a cap 71 that can be attached to the ink head 40 to cover the nozzles 46, a suction flow path 73 connected to the cap 71, a suction pump 74 provided in the suction flow path 73, a downstream pressure sensor 75, a movement mechanism 72, and a control device 90 (see FIG. 1), as shown in FIGS. 6 and 7. The downstream pressure sensor 75 detects a suction pressure value P1 in the suction flow path 73 between the cap 71 and the suction pump 74. The movement mechanism 72 is configured to attach and detach the cap 71 to and from the ink head 40. As shown in FIG. 3, the control device 90 includes a suction control unit 93, a memory unit 91, a suction pressure acquisition unit 94, a range determination unit 95, and a pump adjustment unit 96. In step S103 of FIG. 10, the suction control unit 93 executes a suction process by driving the suction pump 74 with the cap 71 attached to the ink head 40. As shown in FIG. 11 , a reference pressure value SP1 in the suction flow path 73 corresponding to the suction elapsed time T1 from the start time t11 when the suction process is started is preset. The memory unit 91 shown in FIG. 3 pre-stores a reference pressure range SR1 between an upper limit pressure value SP11 and a lower limit pressure value SP12 based on the reference pressure value SP1 corresponding to the suction elapsed time T1. In step S105 of FIG. 10 , the suction pressure acquisition unit 94 acquires the suction pressure value P1 detected by the downstream pressure sensor 75 during the suction process. In step S107 of FIG. 10 , the range determination unit 95 determines whether the suction pressure value P1 corresponding to the suction elapsed time T1 is within the reference pressure range SR1. When the range determination unit 95 determines that the suction pressure value P1 is outside the reference pressure range SR1, the pump adjustment unit 96 adjusts the rotation speed of the suction pump 74 so that the suction pressure value P1 falls within the reference pressure range SR1 in step S117 of FIG. 10 .

[0087] In this manner, in this embodiment, during the suction process, the rotation speed of the suction pump 74 is adjusted so that the suction pressure value P1 in the suction flow path 73 falls within the reference pressure range SR1. Therefore, even if the resistance in the suction flow path 73 changes due to, for example, the indoor environment of the room in which the printer 10 is installed, individual differences in the nozzles 46, or the viscosity of the ink, the rotation speed is adjusted, so that only the amount of ink required for the suction process can be sucked in. Therefore, even if the resistance in the suction flow path 73 changes, the suction process can be performed normally, making it less likely that ejection problems will occur in the ink head 40.

[0088] In this embodiment, if the range determination unit 95 determines that the suction pressure value P1 is smaller than the lower limit pressure value SP12, the pump adjustment unit 96 decreases the rotation speed of the suction pump 74, and if the range determination unit 95 determines that the suction pressure value P1 is greater than the upper limit pressure value SP11, the pump adjustment unit 96 increases the rotation speed of the suction pump 74. In this way, by increasing or decreasing the rotation speed of the suction pump 74 depending on the level of negative pressure in the suction flow path 73, i.e., whether the suction pressure value P1 is greater than the upper limit pressure value SP11 or less than the lower limit pressure value SP12, it is possible to make it easier to keep the suction pressure value P1 within the reference pressure range SR1.

[0089] In this embodiment, the pump adjustment unit 96 reduces the rotation speed of the suction pump 74 by a predetermined adjustment value S2 (see FIG. 3) when the suction pressure value P1 is smaller than the lower limit pressure value SP12, and increases the rotation speed of the suction pump 74 by the adjustment value S2 when the suction pressure value P1 is greater than the upper limit pressure value SP11. This gradually increases (or decreases) the rotation speed of the suction pump 74 when the suction pressure value P1 is outside the reference pressure range SR1, making it difficult for the amount of ink suctioned during the suction process to suddenly increase or decrease. This makes it easier to perform a suction process that sucks in only the required ink consumption amount V1.

[0090] In this embodiment, as shown in FIG. 12, the suction process is a process in which ink is suctioned by a predetermined reference ink consumption amount SV1 during a predetermined reference elapsed time ST1. As shown in FIG. 3, the control device 90 includes a time extension unit 97. When the suction elapsed time T1 has passed the reference elapsed time ST1 in step S109 of FIG. 10, if the ink consumption amount V1 resulting from the suction process from start time t11 is less than the reference ink consumption amount SV1 in step S111 of FIG. 10, the time extension unit 97 extends the suction process until the ink consumption amount V1 becomes equal to or greater than the reference ink consumption amount SV1, as shown in suction process pattern PT11 of FIG. 12. This allows the suction process to continue until the ink consumption amount V1 becomes equal to or greater than the reference ink consumption amount SV1, even if the suction elapsed time T1 exceeds the reference elapsed time ST1. Therefore, even if the resistance within the suction flow path 73 changes, the suction process can be reliably performed to suction the required ink consumption amount V1 (here, the reference ink consumption amount SV1).

[0091] In this embodiment, as shown in FIG. 3, the control device 90 includes an error processor 98. When, in step S115 of FIG. 10, the abnormality occurrence time T2, which is the time during which the suction pressure value P1 continuously deviates from the reference pressure range SR1, is equal to or greater than a predetermined reference error time ST2, the error processor 98 executes a predetermined error process in step S119 of FIG. 10. When the abnormality occurrence time T2 is equal to or greater than the reference error time ST2, it is considered that simply adjusting the rotation speed of the suction pump 74 will not bring the suction pressure value P1 back into the reference pressure range SR1. In this case, it is considered that an abnormality has occurred somewhere other than the suction pump 74. In this case, by executing the error process, it is possible to prevent the suction process in which the abnormality occurred from continuing.

[0092] In this embodiment, as shown in FIG. 8, the inkjet printer 10 includes a damper 58 connected to the ink head 40 and an upstream pressure sensor 59 that detects a damper pressure value P2 within the damper 58. As shown in FIG. 3, the error processing unit 98 includes a damper pressure acquisition unit 98A and a first determination unit 98B. The damper pressure acquisition unit 98A acquires the damper pressure value P2 from the upstream pressure sensor 59. As shown in FIG. 15, the first determination unit 98B determines that an abnormality has occurred in the nozzle 46 or the cap 71 when the suction pressure value P1 is less than a predetermined error suction pressure value SV2 and the change amount C2 in the damper pressure value P2 is less than a predetermined error damper change amount SC2. In such a case, the suction flow path 73, where the suction pressure value P1 is detected, is in an abnormal negative pressure state, and there is no pressure fluctuation in the damper 58, where the damper pressure value P2 is detected. This means that ink is not being sucked from the damper 58. In such a case, it can be assumed that an abnormality has occurred in the nozzle 46 or the cap 71 disposed between the suction flow path 73 and the damper 58. Therefore, it can be determined that an abnormality has occurred in the nozzle 46 or the cap 71 depending on the states of the suction pressure value P1 and the damper pressure value P2.

[0093] In this embodiment, the first determination unit 98B determines that an abnormality has occurred in the cap 71 when the suction pressure value P1 when the cap 71 is separated from the ink head 40 is less than the error suction pressure value SV2. Furthermore, the first determination unit 98B determines that an abnormality has occurred in the nozzle 46 or that the suction pump 74 is malfunctioning when the suction pressure value P1 when the cap 71 is separated from the ink head 40 is equal to or greater than the error suction pressure value SV2. Thus, when the suction pressure value P1 during separation is less than the error suction pressure value SV2, the suction pump 74 is unable to suck ink from the cap 71, and it can be assumed that an abnormality such as a clog has occurred in the cap 71. On the other hand, when the suction pressure value P1 during separation is equal to or greater than the error suction pressure value SV2, it can be assumed that the suction pump 74 is able to suck ink from the cap 71, and it can be assumed that an abnormality such as a clog has occurred in the nozzle 46. Therefore, it is possible to determine whether the abnormality has occurred in the nozzle 46 or the cap 71 based on the suction pressure value P1 during separation.

[0094] In this embodiment, as shown in FIG. 3, the error processing unit 98 includes a second determination unit 98C. As shown in FIG. 15, when the suction pressure value P1 is less than a predetermined error suction pressure value SV2 and the damper pressure value P2 is less than a predetermined error damper pressure value SV3, the second determination unit 98C determines that an abnormality has occurred on the ink tank 55 side of the damper 58. In this case, it can be said that an abnormal negative pressure state exists in the suction flow path 73 where the suction pressure value P1 is detected and in the damper 58 (more specifically, the ink chamber 60) where the damper pressure value P2 is detected. This is presumably caused by ink not being supplied normally toward the damper 58, which has caused an abnormal negative pressure state in the suction flow path 73 and the damper 58, due to an abnormality occurring upstream of the damper 58. Therefore, based on the suction pressure value P1 and the damper pressure value P2, it can be determined that an abnormality has occurred on the ink tank 55 side of the damper 58, i.e., upstream.

[0095] In this embodiment, as shown in FIG. 3, the error processing unit 98 includes a third determination unit 98D. As shown in FIG. 15, when the change C1 in the suction pressure value P1 is less than a predetermined error suction change SC1 and the change C2 in the damper pressure value P2 is less than a predetermined error damper change SC2, the third determination unit 98D determines that air is leaking between the ink head 40 and the cap 71 or that the suction pump 74 is malfunctioning. In this case, the pressure fluctuations in the suction flow path 73 and the damper 58 are small. Therefore, it is estimated that the small pressure fluctuations are due to factors such as the cap 71 not being tightly attached to the ink head 40, causing air to leak from the gap between the cap 71 and the ink head 40, or the suction pump 74 not operating properly and preventing ink from being properly sucked. Therefore, it is possible to determine that air is leaking between the ink head 40 and the cap 71 based on the suction pressure value P1 and the damper pressure value P2.

[0096] In this embodiment, the upstream pressure sensor 59 detects the damper pressure value P2 of the damper 58. The upstream pressure sensor 59 detects the damper pressure value P2 as a numerical value. However, the upstream pressure sensor 59 is not limited to detecting the damper pressure value P2 as a numerical value. For example, the upstream pressure sensor 59 may detect whether the damper pressure value P2 of the damper 58 is equal to or greater than a predetermined pressure. For example, the filler sensor disclosed in Japanese Patent Application Laid-Open No. 2019-107852 may be used as the upstream pressure sensor 59. [Explanation of symbols]

[0097] 10 Printer (inkjet printer) 40 Ink head 46 nozzles 55 Ink Tank 56 Ink supply path 58 Damper 59 Upstream pressure sensor 71 Cap 72 Moving mechanism 73 Suction channel 74 Suction Pump 75 Downstream Pressure Sensor 90 Control device 91 Memory section 93 Suction control unit 94 Suction pressure acquisition unit 95 Range determination section 96 Pump adjustment section 97 Hour extension 98 Error processing section 98A Damper pressure acquisition unit 98B 1st Judgment Department 98C 2nd Judgment Department 98D Third Judgment Department

Claims

1. an ink head having nozzles for ejecting ink; a cap that can be attached to the ink head so as to cover the nozzles; a moving mechanism configured to attach and detach the cap to and from the ink head; a suction channel connected to the cap; a suction pump provided in the suction flow path; a downstream pressure sensor for detecting a suction pressure value in the suction flow path between the cap and the suction pump; a control device; Equipped with The control device a suction control unit that executes a suction process by driving the suction pump with the cap attached to the ink head; a storage unit in which a reference pressure value in the suction flow path corresponding to an elapsed time of suction from a start time of the suction process is set in advance, and a reference pressure range between an upper limit pressure value and a lower limit pressure value based on the reference pressure value corresponding to the elapsed time of suction is stored in advance; a suction pressure acquisition unit that acquires the suction pressure value detected by the downstream pressure sensor during the suction process; a range determination unit that determines whether the suction pressure value over the elapsed suction time is within the reference pressure range; a pump adjusting unit that adjusts a rotation speed of the suction pump when the range determining unit determines that the suction pressure value is outside the reference pressure range so that the suction pressure value falls within the reference pressure range; An inkjet printer equipped with

2. 2. The inkjet printer according to claim 1, wherein the pump adjustment unit reduces the rotation speed of the suction pump when the range determination unit determines that the suction pressure value is smaller than the lower limit pressure value, and increases the rotation speed of the suction pump when the range determination unit determines that the suction pressure value is greater than the upper limit pressure value.

3. 3. The inkjet printer according to claim 2, wherein the pump adjustment unit reduces the rotation speed of the suction pump by a predetermined adjustment value when the suction pressure value is smaller than the lower limit pressure value, and increases the rotation speed of the suction pump by the adjustment value when the suction pressure value is greater than the upper limit pressure value.

4. the suction process is a process of suctioning a predetermined reference ink consumption amount during a predetermined reference elapsed time, 2. The inkjet printer according to claim 1, wherein the control device further comprises a time extension unit that, when the suction elapsed time exceeds the reference elapsed time, if the amount of ink consumed by the suction process from the start time is less than the reference ink consumption amount, extends the suction process until the amount of ink consumed becomes equal to or greater than the reference ink consumption amount.

5. 2. The inkjet printer according to claim 1, wherein the control device further comprises an error processing unit that executes a predetermined error process when an abnormality occurrence time, which is the time during which the suction pressure value continuously deviates from the reference pressure range, is equal to or longer than a predetermined reference error time.

6. a damper connected to the ink head; an upstream pressure sensor that detects a damper pressure value in the damper; Equipped with The error processing unit a damper pressure acquisition unit that acquires the damper pressure value from the upstream pressure sensor; a first determination unit that determines that an abnormality has occurred in the nozzle or the cap when the suction pressure value is less than a predetermined error suction pressure value and the amount of change in the damper pressure value is less than a predetermined error damper change amount; 6. The inkjet printer according to claim 5, comprising:

7. the first determination unit determines that an abnormality has occurred in the cap when the suction pressure value in a state in which the cap is separated from the ink head is less than the error suction pressure value; 7. The inkjet printer according to claim 6, wherein the first determination unit determines that an abnormality has occurred in the nozzle when the suction pressure value in a state in which the cap is separated from the ink head is equal to or greater than the error suction pressure value.

8. a damper connected to the ink head; an upstream pressure sensor that detects a damper pressure value in the damper; an ink tank containing ink; an ink supply path connecting the ink tank and the damper; Equipped with The error processing unit a damper pressure acquisition unit that acquires the damper pressure value from the upstream pressure sensor; a second determination unit that determines that an abnormality has occurred on the ink tank side rather than the damper when the suction pressure value is less than a predetermined error suction pressure value and the damper pressure value is less than a predetermined error damper pressure value; 6. The inkjet printer according to claim 5, comprising:

9. a damper connected to the ink head; an upstream pressure sensor that detects a damper pressure value in the damper; Equipped with The error processing unit a damper pressure acquisition unit that acquires the damper pressure value from the upstream pressure sensor; a third determination unit that determines that air is leaking between the ink head and the cap or that the suction pump is malfunctioning when the change in the suction pressure value is less than a predetermined error suction change amount and the change in the damper pressure value is less than a predetermined error damper change amount; 6. The inkjet printer according to claim 5, comprising:

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