Inkjet printer

A printer includes an ink head including a nozzle, a damper connected with the ink head, a pressure sensor to detect a damper pressure in the damper, a cap attachable to the ink head so as to cover the nozzle, an upward/downward moving mechanism to move the cap upward and downward with respect to the ink head, a suction pump connected with the cap, and a controller. The controller is configured or programmed to include a suction controller to execute a suction process to drive the suction pump in a state where the cap is attached to the ink head, a pressure acquisition controller to acquire the damper pressure from the pressure sensor during the suction process, and an upward/downward movement controller to control the cap to move upward toward the ink head when a change amount of the damper pressure is no larger than a reference change amount.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2021-111268 filed on Jul. 5, 2021. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an inkjet printer.

2. Description of the Related Art

For example, Japanese Laid-Open Patent Publication No. 2016-55478 discloses a printer including a liquid spray that includes nozzles through which ink is sprayed, and a cap attachable to the liquid spray. The cap is provided to maintain spray characteristics of ink to be sprayed from the nozzles.

The cap is attachable to, or separable from, the liquid spray by a moving mechanism. The cap is put into contact with, and is attached to, the liquid spray so as to cover a space on which the nozzles are located. In this state, the space on which the nozzles are located may be tightly closed. The cap is attached to the liquid spray in this manner, so that the ink is suppressed from being evaporated from the nozzles and the ink discharged from the nozzles is recovered.

The cap is connected with, for example, a suction pump. The suction pump is driven in a state where the cap is attached to the liquid spray, so that a suction process of suctioning the ink from the liquid spray is performed. The cap is formed of, for example, rubber, and may be expanded or contacted by an aging deterioration. Such a cap formed of rubber may cause an aging change, for example, may be inflated, expanded or contracted, hardened, or softened by a contact thereof with the ink.

Such an aging deterioration or aging change of the cap causes a situation where the cap attached to the liquid spray does not closely contact the liquid spray and as a result, the space on which the nozzles are located is not tightly closed. In such a case, the suction process, even if executed, may not be performed properly, namely, the ink may not be suctioned from the liquid spray.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide inkjet printers each capable of performing a suction process properly.

An inkjet printer according to a preferred embodiment of the present invention includes an ink head, a damper, a pressure sensor, a cap, an upward/downward moving mechanism, a suction pump, and a controller. The ink head includes a nozzle through which ink is injected. The damper is connected with the ink head. The pressure sensor is configured or programmed to detect a damper pressure in the damper. The cap is attachable to the ink head so as to cover the nozzle. The upward/downward moving mechanism is configured or programmed to move the cap upward and downward with respect to the ink head. The suction pump is connected with the cap. The controller is configured or programmed to include a suction controller, a pressure acquisition controller, a determination controller, and an upward/downward movement controller. The suction controller is configured or programmed to execute a suction process to drive the suction pump in a state where the cap is attached to the ink head. The pressure acquisition controller is configured or programmed to acquire the damper pressure detected by the pressure sensor during the suction process. The determination controller is configured or programmed to determine whether a change amount of the damper pressure is no larger than a reference change amount. The upward/downward movement controller is configured or programmed to control the cap to move upward toward the ink head when the change amount is no larger than the reference change amount.

According to the inkjet printer, when the change amount of the damper pressure is large during the suction process, the pressure in the cap is of a negative level. Thus, it is considered that the ink is suctioned properly from the ink head. By contrast, when the change amount of the damper pressure is small during the suction process, the cap is not attached to the ink head properly. In this case, it is considered that the ink is not suctioned properly from the ink head. When the change amount of the damper pressure is no larger than the reference change amount, it is determined that the suction process is not performed properly because the change amount is small. Therefore, the cap is moved upward. This moves the cap toward the ink head, and is put into in closer contact with the ink head. As a result, the pressure in the cap is decreased to a sufficiently negative level. This allows the suction process to be performed properly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of inkjet printers according to the present invention will be described with reference to the attached drawings. The preferred embodiments described herein are not provided with an intention to specifically limit the present invention, needless to say. Components and portions having the same functions will bear the same reference signs, and overlapping descriptions will be omitted or simplified when necessary.

Hereinafter, an inkjet printer (hereinafter, referred to as a “printer”)10according to a preferred embodiment of the present invention will be described.FIG.1is a front view showing the printer10according to the present preferred embodiment.FIG.2is a bottom view schematically showing a structure of bottom surfaces of a carriage17and ink heads40of the printer10.FIG.3is a block diagram of the printer10according to this preferred embodiment. In the figures, letters F, Rr, L, R, U and D respectively represent “front”, “rear”, “left”, “right”, “up” and “down” regarding the printer10. In the figures, letter Y represents a main scanning direction. In this preferred embodiment, the main scanning direction Y is a left-right direction. In the figures, letter X represents a sub scanning direction. In this preferred embodiment, the sub scanning direction X is a front-rear direction, and crosses (perpendicularly crosses in this example) the main scanning direction Y as seen in a plan view. In the figures, letter Z represents an up-down direction. It should be noted that these directions are defined for the sake of convenience, and do not limit the manner of installation of the printer10in any way, or does not limit the present invention in any way.

The printer10is an inkjet printer. The printer10performs printing on a medium5shown inFIG.1. The medium5is, for example, a roll-type recording sheet, namely, a so-called recording paper roll. The medium5is not limited to such a roll-type recording sheet. The medium5may be, for example, paper such as plain paper, inkjet printing paper or the like; a resin sheet or film of poly(vinylchloride), polyester or the like; a plate; cloth such as woven cloth, unwoven cloth or the like; or any other appropriate material.

As shown inFIG.1, the printer10includes a printer main body11, a platen13, a transportation mechanism20, a guide rail15, the carriage17, a head moving mechanism30, the ink heads (seeFIG.2), ink supply units50(seeFIG.4), a cap unit70(seeFIG.6), and a controller90.

The printer main body11includes a casing extending in the main scanning direction Y. The printer main body11is supported by legs12. The legs12are provided on a bottom surface of the printer main body11, and extend downward from the bottom surface.

The platen13supports the medium5. In this preferred embodiment, the medium5is placed on the platen13. On the platen13, the printing is performed on the medium5. The platen13spreads in the main scanning direction Y and the sub scanning direction X.

The medium5supported by the platen13is transported in the sub scanning direction X by the transportation mechanism20. There is no specific limitation on the structure of the transportation mechanism20. In this preferred embodiment, the transportation mechanism20includes pinch rollers21, grit rollers22, and feed motors23. The pinch rollers21are provided above the platen13and below the guide rail15, and press the medium5from above. The pinch rollers21are located to the rear of the carriage17as seen in a plan view. The grit rollers22are provided in the platen13, and each have a cylindrical outer shape. The grit rollers22are buried in the platen13with top surfaces thereof being exposed. The grit rollers22respectively face the pinch rollers21. The grit rollers22are respectively connected with the feed motors23.

When the feed motors23are driven in a state where the medium5is held between the pinch rollers21and the grit rollers22, the grit rollers22rotate. As a result, the medium5on the platen13is transported in the sub scanning direction X.

The guide rail15is located above the platen13. The guide rail15is located parallel to the platen13, and extends in the main scanning direction Y. The guide rail15is in engagement with the carriage17. The carriage17is provided to be slidable along the guide rail15, and is movable in the main scanning direction Y.

The head moving mechanism30moves the carriage17and the ink heads40(seeFIG.2) in the main scanning direction Y with respect to the medium5supported by the platen13. In this preferred embodiment, the head moving mechanism30moves the carriage17and the ink heads40in the main scanning direction Y. There is no specific limitation on the structure of the head moving mechanism30.

In this preferred embodiment, as shown inFIG.1, the head moving mechanism30includes left and right pulleys31aand31b, a belt32, and a scan motor33. The left pulley31ais provided around a left end portion of the guide rail15. The right pulley31bis provided around a right end portion of the guide rail15. The belt32is an endless belt, and is wound around the left and right pulleys31aand31b. The carriage17is attached and fixed to the belt32. The right pulley31bis connected with the scan motor33.

In this preferred embodiment, the scan motor33is driven to rotate the right pulley31b, and thus the belt32runs. As a result, the carriage17and the ink heads40move in the main scanning direction Y along the guide rail15.

As shown inFIG.2, the ink heads40are provided in the carriage17. The ink heads40are supported by the carriage17, such that bottom surfaces thereof are exposed. There is no specific limitation on the number of the ink heads40. In this preferred embodiment, there are four ink heads40, for example. The four ink heads40are located in a line in the main scanning direction Y.

In the following description, the four ink heads40may also be referred to as a first ink head41, a second ink head42, a third ink head43and a fourth ink head44from the left to the right. The ink heads40include the first ink head41, the second ink head42, the third ink head43and the fourth ink head44. In the following description, the expression the “ink head40” or the “ink heads40” will be used for an explanation common to all the first through fourth ink heads41through44.

The ink heads40(more specifically, the first through fourth ink heads41through44) respectively have nozzle surfaces45. The nozzle surfaces45each define a bottom surface of the ink head40. Nozzles46are provided in each of the nozzle surfaces45. The nozzles46include a plurality of first nozzles46aand a plurality of second nozzles46b. The plurality of first nozzles46aare provided in the nozzle surface45and located in a line in the sub scanning direction X. The plurality of second nozzles46bare also provided in the nozzle surface45and located in a line in the sub scanning direction X.

Regarding each nozzle surface45, the line of the plurality of first nozzles46awill be referred to as a “first nozzle line48”, and the line of the plurality of second nozzles46bwill be referred to as a “second nozzle line49”. The nozzle lines48and49are located in a line in the main scanning direction Y. The first through fourth ink heads41through44each include the two nozzle lines48and49. In this preferred embodiment, there are eight nozzle lines in total (the sum of the first nozzle lines48and the second nozzle lines49), for example.

FIG.4is a conceptual view showing the relationship between the ink heads40and the ink supply units50. In this preferred embodiment, the ink supply units50shown inFIG.4supply ink to the ink heads40(for example, the nozzles46). The ink supply units50are connected with the nozzles46of the ink heads40. In this preferred embodiment, the ink supply units50include first ink supply units51supplying ink to the first nozzles46aof the ink heads40and second ink supply units52supplying ink to the second nozzles46bof the ink heads40. The ink supply units51and52are connected with the first through fourth ink heads41through44. The number of the first ink supply units51is equal to the number of the first nozzle lines48(seeFIG.2) including the first nozzles46a, namely, four. The number of the second ink supply units52is equal to the number of the second nozzle lines49(seeFIG.2) including the second nozzles46b, namely, four. Therefore, there are eight ink supply units50in this preferred embodiment, for example.

FIG.5is a schematic front view showing a structure of one ink head40and the ink supply units50corresponding thereto. The ink supply units50include ink tanks55, ink supply paths56, liquid transmission pumps57, dampers58, and pressure sensors59. The ink tanks55are each a container accommodating ink. The ink tanks55may each be, for example, a cartridge or a pouch-shaped item.

The ink accommodated in each of the ink tanks55is, for example, one of process color ink and special color ink. Process color ink includes, for example, cyan ink, magenta ink, yellow ink, black ink, and the like. The special color ink includes ink of colors other than those of the process color ink. The special color ink includes, for example, white ink, clear ink, gloss ink, primer ink, fluorescent ink, metallic ink, orange ink, red ink, violet ink, blue ink, green ink, and the like. It should be noted that there is no specific limitation on the color of the ink accommodated in each of the ink tanks55. There is no specific limitation on the material of the ink. The ink may be formed of any of various materials conventionally used as a material of the ink for an inkjet printer. The ink may be, for example, solvent-based pigment ink or aqueous pigment ink. Alternatively, the ink may be aqueous dye ink, ultraviolet-curable ink, which is cured by being irradiated with ultraviolet rays, or the like.

In this preferred embodiment, the ink tanks55include a first ink tank55aand a second ink tank55b, for example. The first ink tank55ais included in the first ink supply unit51, and is connected with the first nozzles46a. The second ink tank55bis included in the second ink supply unit52, and is connected with the second nozzles46b.

The ink supply paths56are each a flow path connecting the ink tank55and the ink head40. One end of each ink supply path56is connected with the ink tank55, and the other end of each ink supply path56is connected with the ink head40. There is no specific limitation on the structure of the ink supply paths56. The ink supply paths56are each formed of, for example, a flexible tube. The ink in the ink tanks55flows in the ink supply paths56and is supplied to the ink head40.

In this preferred embodiment, the ink supply paths56include a first ink supply path56aand a second ink supply path56b. The first ink supply path56ais included in the first ink supply unit51, and the second ink supply path56bis included in the second ink supply unit52. One end of the first ink supply path56ais connected with the first ink tank55a, and the other end of the first ink supply path56ais connected with the first nozzles46aof the ink head40. The ink accommodated in the first ink tank55ais supplied to the first nozzles46avia the first ink supply path56a. One end of the second ink supply path56bis connected with the second ink tank55b, and the other end of the second ink supply path56bis connected with the second nozzles46bof the ink head40. The ink accommodated in the second ink tank55bis supplied to the second nozzles46bvia the second ink supply path56b.

The liquid transmission pumps57are provided in the ink supply paths56. The liquid transmission pumps57are each a pump supplying the ink accommodated in the ink tank55to the ink head40and adjusting the pressure of the ink to a pressure suitable to the injection thereof from the ink head40. When being driven, the liquid transmission pumps57transmit the ink from the ink tanks55toward the ink head40. There is no specific limitation on the type of the liquid transmission pumps57. The liquid transmission pumps57are each, for example, a diaphragm pump, a tube pump, or the like.

In this preferred embodiment, the liquid transmission pumps57include a first liquid transmission pump57aand a second liquid transmission pump57b. The first liquid transmission pump57ais included in the first ink supply unit51. The first liquid transmission pump57ais provided in the first ink supply path56a, and transmits the ink from the first ink tank55atoward the first nozzles46aof the ink head40. The second liquid transmission pump57bis included in the second ink supply unit52. The second liquid transmission pump57bis provided in the second ink supply path56b, and transmits the ink from the second ink tank55btoward the second nozzles46bof the ink head40.

The dampers58alleviate a change in the pressure of the ink to stabilize the injection of the ink from the ink head40. The driving of the liquid transmission pumps57is controlled in accordance with, for example, the flow rate of the ink flowing into the dampers58(in other words, in accordance with the pressures in the dampers58). The dampers58are connected with the ink head40(in this preferred embodiment, the nozzles46). In this preferred embodiment, the dampers58are provided above the ink head40.

In this preferred embodiment, the dampers58include a first damper58aand a second damper58b. The first damper58ais included in the first ink supply unit51, and is connected with the first nozzles46aof the ink head40. The second damper58bis included in the second ink supply unit52, and is connected with the second nozzles46bof the ink head40. The first damper58aand the second damper58bare located in a line above the ink head40.

There is no specific limitation on the structure of the dampers58(more specifically, the first damper58aand the second damper58b). In this preferred embodiment, the dampers58each include an ink chamber60temporarily storing the ink. The ink chamber60expands or contracts in accordance with the amount of the ink stored therein. In this preferred embodiment, the pressure in the ink chamber60changes in accordance with the amount of the ink stored therein. When, for example, the amount of ink in the ink chamber60is increased, the ink chamber60expands and the pressure therein is increased. By contrast, when the amount of the ink in the ink chamber60is decreased, the ink chamber60contracts and the pressure therein is decreased. The ink chamber60is in communication with the ink supply path56and the ink head40. Although not shown, the ink chamber60has an inlet and an outlet formed therein. The ink chamber60is connected with the ink supply path56via the inlet, and is connected with the ink head40via the outlet.

In this preferred embodiment, the ink chamber60of the first damper58ais in communication with the first ink supply path56aand the first nozzles46aof the ink head40. The ink chamber60of the second damper58bis in communication with the second ink supply path56band the second nozzles46bof the ink head40.

The pressure sensors59detect the pressures in the dampers58. The expression the “pressures in the dampers58” refers to the pressures in the ink chambers60included in the dampers58. The pressure sensors59each detect the pressure in the corresponding damper58based on, for example, the size of the ink chamber60(e.g., the degree at which the ink chamber60expands or contracts).

In this preferred embodiment, the pressure sensors59include a first pressure sensor59aand a second pressure sensor59b. The first pressure sensor59ais included in the first ink supply unit51, and detects the pressure in the first damper58a. The second pressure sensor59bis included in the second ink supply unit52, and detects the pressure in the second damper58b.

Now, the cap unit70will be described.FIG.6andFIG.7are each a front view showing the carriage17, the ink heads40and the cap unit70.FIG.8andFIG.9are each a schematic front view showing one ink head40, the ink supply units50corresponding thereto, and one cap71corresponding thereto. As shown inFIG.6, the cap unit70includes a plurality of caps71, an upward/downward moving mechanism72, and a plurality of suction pumps73.

The caps71are attachable to the ink heads40so as to cover the nozzles46(seeFIG.2). One cap41is attachable to one ink head40. Therefore, the number of the caps71is equal to the number of the ink heads40, namely, four. In this preferred embodiment, the caps71include a first cap71A, a second cap71B, a third cap71C, and a fourth cap71D. As shown inFIG.7, the first cap71A, the second cap71B, the third cap71C and the fourth cap71D are respectively attachable to the first ink head41, the second ink head42, the third ink head43and the fourth ink head44. In the following description, the expression “the cap71” or “the caps71” will be used for an explanation common to all the first through fourth caps71A through71D.

In this preferred embodiment, as shown inFIG.8, the caps71each include a lip portion74. The lip portion74forms a top end portion of the cap71. As shown inFIG.9, the lip portion74is in contact with the nozzle surface45in a state where the cap71is attached to the ink head40. The lip portion74is ring-shaped. The lip portion74has a width decreasing as being closer to a top end thereof. The “width of the lip portion74” is a length of the lip portion74in a direction perpendicular to a circumferential direction thereof. The lip portion74tapers off toward the top end thereof.

The lip portion74is elastically deformable. Therefore, the lip portion74may be elastically deformed when contacting the nozzle surface45of the ink head40. There is no specific limitation on the material of the lip portion74. In this preferred embodiment, the lip portion74is formed of rubber. Specifically, the lip portion74is formed of ethylene propylene diene monomer (EPDM) or butyl rubber. In this preferred embodiment, the portion of the cap71except for the lip portion74is also formed of rubber.

In the cap71, an absorber75is provided. The absorber75is accommodated in the cap71. The absorber75receives the ink injected (or discharged) from the ink head40into the cap71. The ink received by the absorber75is absorbed into the absorber75. The absorber75is located below the top end of the lip portion74, and the lip portion74protrudes upward from the absorber75. The absorber75may be formed of any material that absorbs ink with no specific limitation. In this preferred embodiment, the absorber75is formed of a porous material. The absorber75is formed of, for example, sponge formed of poly(vinylalcohol) (i.e., PVA sponge).

As shown inFIG.6andFIG.7, the upward/downward moving mechanism72moves the cap71upward and downward with respect to the ink head40. In this preferred embodiment, the upward/downward moving mechanism72moves the caps71(more specifically, the first through fourth caps71A through71D) upward and downward. The upward/downward moving mechanism72attaches the caps71to the ink heads40or separates the caps71from the ink heads40. For example, the upward/downward moving mechanism72moves the caps71upward as represented by the arrow inFIG.6to attach the caps71to the ink heads40as shown inFIG.7. The upward/downward moving mechanism72moves the caps71downward to separate the caps71from the ink heads40as shown inFIG.6.

There is no specific limitation on the structure of the upward/downward moving mechanism72. In this preferred embodiment, the upward/downward moving mechanism72includes a support member77and an upward/downward moving motor78. The support member77is, for example, a plate-shaped member extending in the main scanning direction Y and the sub scanning direction X, and supports the first through fourth caps71A through71D. The upward/downward moving motor78is connected with the support member77. In this preferred embodiment, the upward/downward moving motor78is driven, and as a result, the support member77moves upward or downward. Along with the upward or downward movement of the support member77, the first through fourth caps71A through71D move upward or downward collectively at the same time. The upward or downward movement of the first through fourth caps71A through71D allows the caps71to be attached to the nozzle surfaces45collectively or to be separated from the nozzle surfaces45collectively.

The suction pumps73are respectively connected with the caps71. The suction pumps73each suction the ink in the cap71connected therewith, or the ink in the ink head40to which the cap71connected therewith is attached. In this preferred embodiment, one suction pump73is connected with one cap71. Therefore, the number of the suction pumps73is equal to the number of the caps71, namely, four. In this preferred embodiment, the suction pumps73include a first suction pump73A, a second suction pump73B, a third suction pump73C, and a fourth suction pump73D. The first suction pump73A, the second suction pump73B, the third suction pump73C and the fourth suction pump73D are respectively connected with the first cap71A, the second cap71B, the third cap71C and the fourth cap71D. In the following description, the expression the “suction pump73” or the “suction pumps73” will be used for an explanation common to all the first through fourth suction pumps73A through73D.

In this preferred embodiment, there is no specific limitation on the type of the suction pumps73. The suction pumps73are each, for example, a vacuum pump. The suction pumps73are respectively provided in the middle of tubes79. One end of each of the tubes79is connected with the cap71corresponding thereto, and the other end of each of the tubes79is connected with a waste liquid tank (not shown). The waste liquid tank is provided in the number of, for example, one, and is connected with the first through fourth caps71A through71D via the four tubes79.

When, for example, any one suction pump73is driven in a state where the cap71is attached to the ink head40, the pressure in the cap71becomes lower than a negative pressure in the ink supply path56connected with the ink head40as shown inFIG.9. As a result, the ink is suctioned out of the nozzles46(in this preferred embodiment, the first nozzles46aand the second nozzles46b), and the ink in the ink head40is discharged into the cap71. The ink in the cap71suctioned by the suction pump73is discharged into the waste liquid tank via the tube79.

In this preferred embodiment, as shown inFIG.1, an operation panel80is provided at a right end of the printer main body11of the printer10. The operation panel80includes a display screen81displaying the state of the printer10, input keys82operable by a user, and the like.

Now, the controller90will be described. The controller90is configured or programmed to perform controls on the printing and a control of suctioning the ink in the ink heads40, and the like. There is no specific limitation on the structure of the controller90. The controller90is, for example, a microcomputer. There is no specific limitation on the hardware structure of the microcomputer. The controller90includes, for example, an I/F, a CPU, a ROM, and a RAM. The controller90is provided in the printer main body11. It should be noted that the controller90may be realized by, for example, a computer installed outside the printer main body11. In this case, the controller90is communicably connected with a control board (not shown) of the printer10in a wired or wireless manner.

In this preferred embodiment, as shown inFIG.3, the controller90is communicably connected with the transportation mechanism20(more specifically, the feed motors23), the head moving mechanism30(more specifically, the scan motor33), the ink heads40(more specifically, the first through fourth ink heads41through44(seeFIG.2)), the liquid transmission pumps57(more specifically, the first liquid transmission pumps57aand the second liquid transmission pumps57b(seeFIG.5)), the pressure sensors59(more specifically, the first pressure sensors59aand the second pressure sensors59b(seeFIG.5)), the upward/downward moving mechanism72of the camp unit70(more specifically, the upward/downward moving motor78), the suction pumps73of the camp unit70(more specifically, the first through fourth suction pumps73A through73D (seeFIG.6)), and the operation panel80. The controller90is configured or programmed to control the transportation mechanism20, the head moving mechanism30, the ink heads40, the liquid transmission pumps57, the pressure sensors59, the upward/downward moving mechanism72, the suction pumps73and the operation panel80.

In the printer10according to this preferred embodiment, a cleaning process is executed on the ink heads40in order to suppress generation of abnormal injection from the nozzles46in the ink heads40. The “abnormal injection from the nozzles46” refers abnormalities such that the ink injected from the nozzles46frays, that the ink is not injected from the nozzles46, and the like; namely, abnormalities that deteriorate the quality of the printing.

The cleaning process includes a suction process. The suction process refers to a process of suctioning the ink from the nozzles46in a state where the cap71is attached to the ink head40as shown inFIG.9.

In this preferred embodiment, as shown inFIG.3, the controller90includes a storage91, a capping controller92, a suction controller93, a pressure acquisition controller94, a determination controller95, an upward/downward movement controller96, and an error controller97in order to execute the suction process. The controllers and the like91through97of the controller90may be realized by software or hardware. The controllers and the like91through97of the controller90may be realized by one or a plurality of processors or may be incorporated into a circuit.

Now, a control procedure to execute the suction process by the printer10according to this preferred embodiment will be described with reference to the flowchart shown inFIG.10.

Referring toFIG.10, in step S101, the capping controller92shown inFIG.3controls the upward/downward moving mechanism72such that the caps71are attached to the ink heads40. In this preferred embodiment, the capping controller92controls the head moving mechanism30(seeFIG.1) such that as shown inFIG.6, the first through fourth ink heads41through44are located just above the first through fourth caps71A through71D respectively. Then, the capping controller92controls the upward/downward moving motor78of the upward/downward moving mechanism72to be driven such that the first through fourth caps71A through71D are moved upward. As a result, as shown inFIG.7, the first through fourth caps71A through71D are respectively attached to the first through fourth ink heads41through44.

Next, in step S103inFIG.10, the suction process is started. The suction controller93shown inFIG.3controls the suction pumps73to be driven in a state where the caps71are attached to the ink heads40. In this preferred embodiment, the first through fourth suction pumps73A through73D are driven at the same time in a state where the first through fourth caps71A through71D are respectively attached to the first through fourth ink heads41through44. Therefore, the suction process is started at the same time on the first through ink heads41through44.

In step S103, the suction controller93acquires pressures (in this preferred embodiment, referred to as “damper pressures P1”) detected by the pressure sensors59before the suction process is started, namely, before the suction pumps73are driven. In step S103, the damper pressures P1detected by the pressure sensors59are set as “reference pressures P2”. As shown inFIG.3, the suction controller93stores the reference pressures P2on the storage91. One reference pressure P2is acquired for each of the dampers58. In this preferred embodiment, eight reference pressures P2are stored on the storage91.

The reference pressures P2do not need to be acquired in step S103. For example, the reference pressures P2may be constant and stored in advance on the storage91.

Next, in step S105inFIG.10, the pressure acquisition controller94shown inFIG.3acquires the damper pressure P1in each damper58during the suction process. In this preferred embodiment, the pressure acquisition controller94acquires the damper pressure P1detected by each pressure sensor59. For example, the pressure acquisition controller94transmits a pressure signal to each pressure sensor59. Upon receipt of the pressure signal, the pressure sensor59detects the damper pressure P1in the damper58and transmits the damper pressure P1to the pressure acquisition controller94. The pressure acquisition controller94receives the damper pressure P1transmitted from the pressure sensor59, and thus acquires the damper pressure P1.

In this preferred embodiment, among the damper pressures P1, the damper pressure P1in the first damper58aacquired by the first pressure sensor59a(seeFIG.9) is referred to also as a “first damper pressure”. The damper pressure P1in the second damper58bacquired by the second pressure sensor59b(seeFIG.9) is referred to also as a “second damper pressure”. The damper pressures P1acquired by the pressure acquisition controller94are stored on the storage91.

Next, in step S107inFIG.10, it is determined whether or not to move the caps71upward during the suction process. In this preferred embodiment, the caps71are moved upward in the case where the suction of the ink in the ink heads40is not performed properly during the suction process. In this preferred embodiment, it is determined whether or not the suction process is performed properly based on a change amount C1of the damper pressure P1in each damper58between before the start of the suction process and after the start of the suction process.

In step S107, the determination controller95determines whether the change amount C1of the damper pressure P1is no larger than a reference change amount C2. The “change amount C1of the damper pressure P1” is calculated based on the reference pressure P2stored on the storage91and the damper pressure P1acquired by the pressure acquisition controller94in step S105. In this preferred embodiment, the change amount C1of the damper pressure P1is a difference between the reference pressure P2and the damper pressure P1.

In this preferred embodiment, among the change amounts C1of the damper pressures P1, the change amount C1of the first damper pressure is referred to as a “first change amount”. The change amount C1of the second damper pressure is referred to as a “second change amount”. As shown inFIG.3, the reference change amount C2is stored in advance on the storage91.

In this preferred embodiment, in the case where the suction process is performed properly, the ink in the ink head40is suctioned, and thus the change amount C1of the damper pressure P1is large. Therefore, when the change amount C1of the damper pressure P1is larger than the reference change amount C2, the determination controller95determines that the suction process is performed properly.

By contrast, in the case where the suction process is not performed properly, the ink in the ink head40is not suctioned properly, and thus the change amount C1of the damper pressure P1is small. Therefore, when the change amount C1of the damper pressure P1is no larger than the reference change amount C2, the determination controller95determines that the suction process is not performed properly.

In the case where, as in this preferred embodiment, two dampers58(in this example, the first damper58aand the second damper58b) are connected with one ink head40as shown inFIG.9, when the change amount C1of at least one of the damper pressures P1is large, it is determined that the suction process is performed properly. Therefore, the determination controller95determines whether neither the first change amount of the first damper pressure nor the second change amount of the second damper pressure regarding the one ink head40is larger than the reference change amount C2. When at least one of the first change amount of the first damper pressure and the second change amount of the second damper pressure is larger than the reference change amount C2, the determination controller95determines that the suction process is performed properly.

By contrast, when the change amounts C1of the damper pressures P1in both of the two dampers58connected with the one ink head40are small, it is determined that the suction process is not performed properly. Therefore, when neither the first change amount of the first damper pressure nor the second change amount of the second damper pressure regarding the one ink head40is larger than the reference change amount C2, the determination controller95determines that the suction process is not performed properly.

In the case where, as in this preferred embodiment, there are a plurality of ink heads40as shown inFIG.2, for example, in the case where there are four ink heads40, specifically, the first through fourth ink heads41through44, when the change amounts C1of the damper pressures P1regarding all the four ink heads40are large, it is determined that the suction process is performed properly. Therefore, the determination controller95determines whether the change amount C1of the damper pressure P1regarding at least one of the first through fourth ink heads41through44is no larger than the reference change amount C2. When the change amounts C1of the damper pressures P1regarding all the first through fourth ink heads41through44are larger than the reference change amount C2, the determination controller95determines that the suction process is performed properly.

By contrast, when the change amount C1of the damper pressure P1regarding at least one of the first through fourth ink heads41through44is small, it is determined that the suction process is not performed properly. Therefore, when the change amount C1of the damper pressure P1regarding at least one of the first through fourth ink heads41through44is no larger than the reference change amount C2, the determination controller95determines that the suction process is not performed properly.

In this preferred embodiment, when it is determined that the suction process is performed properly, the caps71are not moved upward during the suction process, and the procedure in the flowchart shown inFIG.10is finished. By contrast, when it is determined that the suction process is not performed properly, the procedure advances to step S109inFIG.10in order to perform the suction process properly.

In step S109, the upward/downward movement controller96shown inFIG.3controls the upward/downward moving mechanism72such that the caps71are moved upward toward the ink heads40. In this preferred embodiment, the upward/downward movement controller96controls the caps71to move upward by a predetermined reference distance L5. As shown inFIG.3, the reference distance L5is stored in advance on the storage91. There is no specific limitation on the numerical value of the reference distance L5. For example, the reference distance L5is a minimum possible distance by which the upward/downward moving mechanism72may move the caps71. The reference distance L5is, for example, about 0.1 mm.

Next, in step S111inFIG.10, the error controller97shown inFIG.3determines whether or not an upward moving distance L1of the caps71controlled by the upward/downward movement controller96is no shorter than an error distance L2. The “upward moving distance L1” is a distance by which the caps71have been moved upward during one cycle of the suction process. The “upward moving distance L1” is a distance by which the upward/downward movement controller96has controlled the caps71to move upward in step S109. In this preferred embodiment, the upward moving distance L1is calculated by multiplying the reference distance L5by the number of times the operation in step S109is executed.

The “error distance L2” is, for example, a distance by which the caps71are is moved upward until the absorbers75accommodated in the caps71are put into contact with the nozzle surfaces45. As shown inFIG.3, the error distance L2is stored in advance on the storage91.

In step S111, when the upward moving distance L1of the caps71controlled by the upward/downward movement controller96is shorter than the error distance L2, the procedure returns to step S105, and the pressure acquisition controller94acquires the damper pressure P1in each damper58. By contrast, when the upward moving distance L1of the caps71controlled by the upward/downward movement controller96is no shorter than the error distance L2in step S111, the procedure advances to step S113inFIG.10.

In step S113, the error controller97shown inFIG.3performs an error control. The “error control” refers to a control of notifying a user that the suction process was not performed properly. There is no specific limitation on the particulars of the error control. The error controller97, for example, displays an error message on the display screen81(seeFIG.1) of the operation panel80as an error control. The “error message” refers to a message indicating that, for example, the suction process was not performed properly. The user may see the error message displayed on the display screen81to learn that the suction process was not performed properly. In this case, the user may, for example, inquire with the customer service center.

When the error control is performed as described above, the procedure in the flowchart shown inFIG.10is finished. In this preferred embodiment, after the error control is performed, the suction pumps73are stopped to finish the suction process.

As described above, in this preferred embodiment, as shown inFIG.9, the printer10includes the ink heads40, the dampers58, the pressure sensors59, the caps71, the upward/downward moving mechanism72(seeFIG.6), the suction pumps73(seeFIG.6), and the controller90(seeFIG.3). The ink heads40each include the nozzles46through which the ink is injected. The dampers58are connected with the corresponding ink head40. The pressure sensors59each detect the damper pressure in the corresponding damper58. The caps71are each attached to the corresponding ink head40so as to cover the nozzles46. As shown inFIG.6andFIG.7, the upward/downward moving mechanism72moves the caps71upward and downward with respect to the ink heads40. The suction pumps73are each connected with the corresponding cap71. As shown inFIG.3, the controller90is configured or programmed to include the suction controller93, the pressure acquisition controller94, the determination controller95, and the upward/downward movement controller96. As shown in step S103inFIG.10, the suction controller93executes the suction process of driving the suction pumps73in a state where the caps71are attached to the ink heads40. As shown in step S105inFIG.10, the pressure acquisition controller94acquires the damper pressure P1detected by each of the pressure sensors59during the suction process. As shown in step S107inFIG.10, the determination controller95determines whether the change amount C1of each damper pressure P1is no larger than the reference change amount C2. When the change amount C1of the damper pressure P1is no larger than the reference change amount C2, the upward/downward movement controller96controls the caps71to move upward toward the ink heads40as shown in step S109inFIG.10.

According to this preferred embodiment, when the change amount C1of a particular damper pressure P1is large during the suction process, the pressure in the cap71is of a negative level. Thus, it is considered that the ink is suctioned properly from the ink head40. By contrast, when the change amount C1of the damper pressure P1is small during the suction process, the cap71is not attached to the ink head40properly, and the pressure in the cap71is not at a sufficiently negative level. In this case, it is considered that the ink is not suctioned properly from the ink head40. In this preferred embodiment, when the change amount C1of the damper pressure P1is no larger than the reference change amount C2, it is determined that the suction process is not performed properly because the change amount C1is small. Therefore, the caps71are moved upward. This moves the caps71toward the ink heads40, and are put into in closer contact with the ink heads40. As a result, the pressure in the cap71is decreased to a sufficiently negative level. This allows the suction process to be performed properly.

In this preferred embodiment, the caps71are formed of rubber. There are a variety of types of rubber. For example, there are soft rubber and hard rubber. Some types of rubber may exhibit an aging change when being in contact with ink. Therefore, there are types of rubber suitable to be used with ink and types of rubber not suitable to be used with ink. In this preferred embodiment, in the case where the suction process is not performed properly due to an aging change of the rubber forming the caps71, the caps71are moved upward to be put into closer contact with the ink heads40. Therefore, even in the case where the caps71are formed of rubber that may exhibit an aging change, the suction process is performed properly. This broadens the range of types of rubber that are usable to form the caps71.

In this preferred embodiment, in the case where the suction process is not performed properly due to the aging deterioration of the rubber forming the caps71, the caps71are moved upward to be put into closer contact with the ink heads40during the suction process. Therefore, the suction process is performed properly even if the rubber forming the caps71exhibits an aging deterioration.

In this preferred embodiment, the controller90includes the storage91. On the storage91, the reference pressure P2(seeFIG.3) is stored, which is the damper pressure P1in a state where the corresponding cap71is attached to the ink head40and the suction pump73is not driven. The determination controller95shown inFIG.3sets, as the change amount C1of the damper pressure P1, a difference between the reference pressure P2and the damper pressure P1acquired by the pressure acquisition controller94in step S107inFIG.10. Namely, the change amount C1of the damper pressure P1is set as the difference between the damper pressure P1during the suction process and the reference pressure P2, which is the pressure in a state where the suction process it not performed. Therefore, the determination controller95may determine whether or not the suction process is performed properly based on the change amount C1from the reference pressure P2.

In this preferred embodiment, in step S103inFIG.10, the suction controller93stores the damper pressure P1, detected by the pressure sensor59before driving the suction pump73, on the storage91as the reference pressure P2. This sets, as the change amount C1, the difference between the pre-suction process damper pressure P1(reference pressure P2) and the damper pressure P1during the suction process. Therefore, the change amount C1may be calculated more accurately.

In this preferred embodiment, as shown inFIG.9, the nozzles46include the first nozzles46aand the second nozzles46b. The dampers58include the first damper58aconnected with the first nozzles46aand the second damper58bconnected with the second nozzles46b. The pressure sensors59include the first pressure sensor59adetecting the first damper pressure in the first damper58aand the second pressure sensor59bdetecting the second damper pressure in the second damper58b. In step S105inFIG.10, the pressure acquisition controller94shown inFIG.3acquires the first damper pressure and the second damper pressure during the suction process. In step S107inFIG.10, the determination controller95shown inFIG.3determines whether neither the first change amount of the first damper pressure nor the second change amount of the second damper pressure is larger than the reference change amount C2. When neither the first change amount nor the second change amount is larger than the reference change amount C2, the upward/downward movement controller96shown inFIG.3moves the caps71toward the ink heads40in step S109inFIG.10.

In the case where the two dampers58aand58bare provided for one ink head40as described above, when the change amount C1of at least one of the damper pressures P1is large, it may be determined that the suction process is performed properly on the one ink head40. By contrast, when the change amounts C1of both of the damper pressures P1are small, it may be determined that the suction process is not performed properly on the one ink head40.

In this preferred embodiment, as shown inFIG.2, the printer10includes the plurality of ink heads40(in this example, the first through fourth ink heads41through44). As shown inFIG.9, the dampers58, the pressure sensors59, the cap71and the suction pump73are provided for each of the ink heads40. As shown inFIG.6andFIG.7, the upward/downward moving mechanism72moves the plurality of caps71(in this example, the first through fourth caps71A through71D) collectively. In step S105inFIG.10, the pressure acquisition controller94shown inFIG.3acquires the damper pressures P1detected by the pressure sensors59corresponding to each ink head40during the suction process. In step S107inFIG.10, the determination controller95shown inFIG.3determines whether the change amount C1of at least one of the damper pressures P1corresponding to each ink head40is no larger than the reference change amount C2. When the change amount C1of at least one of the damper pressures P1corresponding to each ink head40is no larger than the reference change amount C2, the upward/downward movement controller96shown inFIG.3moves the plurality of caps71upward in step S109inFIG.10. As described above, with the structure where the plurality of caps71are moved upward collectively (i.e., at the same time), in the case where the suction process is not performed properly on one of the plurality of ink heads40, the caps71are moved upward collectively. Therefore, the suction process may be performed properly on all the ink heads40.

In this preferred embodiment, for example, the second ink head42corresponds to “another ink head”. At least one of the dampers58connected with the second ink head42corresponds to “another damper”. At least one of the pressure sensors59detecting the pressures of the dampers58connected with the second ink head42corresponds to “another pressure sensor”. The second cap71B corresponds to “another cap”, and the second suction pump73B corresponds to “another suction pump”.

In this preferred embodiment, in step S109inFIG.10, the upward/downward movement controller96moves the caps71upward by the reference distance L5. After the caps71are controlled by the upward/downward movement controller96to move upward by the reference distance L5, the pressure acquisition controller94acquires the damper pressures P1in step S105inFIG.10. This allows the caps71to be moved upward gradually by the reference distance L5until the change amount C1of each damper pressure P1is increased to be larger than the reference change amount C2. Therefore, the caps71are suppressed from being moved upward excessively.

In this preferred embodiment, the controller90includes the error controller97(seeFIG.3). When, in step S111inFIG.10, the upward moving distance L1, by which the caps71are controlled by the upward/downward movement controller96to move upward, is no shorter than the error distance L2, the error controller97performs the error control in step S113inFIG.10. In the case where, for example, the upward moving distance L1of the caps71is too long, the absorbers75of the caps71may, for example, contact the nozzle surfaces45. When the absorbers75contact the nozzle surfaces45, there is an undesirable possibility that the meniscus of each of the nozzles46is not adjusted properly. Therefore, it is preferred that the absorbers75do not contact the nozzle surfaces45. For this reason, in this preferred embodiment, when the upward moving distance L1of the caps71is no shorter than the error distance L2, the error control is performed and the suction process is finished. In this manner, such a situation may be prevented that the upward moving distance L1of the caps71is too long and as a result, the absorbers75in the caps71contact the nozzle surfaces45.

In this preferred embodiment, the two dampers58(in this example, the first damper58aand the second damper58b) are provided for one ink head40. Alternatively, one damper58may be provided for one ink head40, or, for example, three or more dampers58may be provided for one ink head40.

In this preferred embodiment, the pressure sensors59each detect the damper pressure P1in the corresponding damper58at a predetermined time point. The pressure sensor59detects the damper pressure P1with a numerical value. The pressure sensor59is not limited to detecting the damper pressure P1with a numerical value. For example, the pressure sensor59may detect whether the damper pressure P1in the damper58is no smaller than a predetermined pressure (e.g., lower-limit pressure). The pressure sensor59may be, for example, a filler sensor disclosed in Japanese Laid-Open Patent Publication No. 2019-107852. In this case, the filler sensor detects whether the damper pressure P1during the suction process is no smaller than the predetermined pressure. When, for example, the filler sensor hits to detect that the damper pressure P1during the suction process is changed to a level smaller than the predetermined pressure, the determination controller95determines that the suction process is performed properly. By contrast, when a state where the filler sensor does not hit is continued even though the suction process is performed and thus it is detected that the damper pressure P1is still no smaller than the predetermined pressure, the determination controller95determines that the suction process is not proper, and thus the upward/downward movement controller96moves the caps71upward toward the ink heads40.

The terms and expressions used herein are for description only and are not to be interpreted in a limited sense. These terms and expressions should be recognized as not excluding any equivalents to the elements shown and described herein and as allowing any modification encompassed in the scope of the claims. The present invention may be embodied in many various forms. This disclosure should be regarded as providing preferred embodiments of the principles of the present invention. These preferred embodiments are provided with the understanding that they are not intended to limit the present invention to the preferred embodiments described in the specification and/or shown in the drawings. The present invention is not limited to the preferred embodiments described herein. The present invention encompasses any of preferred embodiments including equivalent elements, modifications, deletions, combinations, improvements and/or alterations which can be recognized by a person of ordinary skill in the art based on the disclosure. The elements of each claim should be interpreted broadly based on the terms used in the claim, and should not be limited to any of the preferred embodiments described in this specification or referred to during the prosecution of the present application.