Printing device, printing method, and program

Abstract

To provide a printing device configured so that ink discharge failures caused by moisture absorption by a cap can be reduced.SOLUTION: A printing device executes printing operation of making a nozzle discharge ink on the basis of image data in an un-capping state, first discharge-flushing operation of making the nozzle discharge ink, capping operation of bringing a head and a cap into a capping state, first time-measurement operation of measuring a first transitional period of time which is a transitional period of time which commences after the first discharge-flushing operation is executed and before the capping operation is executed; and when executing subsequent printing operation, executes first maintenance operation as maintenance operation and then executes the subsequent printing operation, when the first transitional period of time is longer than a first predetermined period of time, and executes second maintenance operation which enables ink whose amounts are more than discharge amounts of the ink in the first maintenance operation to be discharged, as maintenance operation, and then executes the subsequent printing operation, when the first transitional period of time is less than the first predetermined period of time.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a printing device, a printing method, and a program. [Background technology]

[0002] A known example of a conventional printing apparatus is the liquid ejection apparatus disclosed in Patent Document 1. This liquid ejection apparatus includes a liquid ejection head having nozzles for ejecting liquid, and a capping device. With the liquid ejection apparatus, a printing operation is performed by ejecting liquid from the liquid ejection head with the capping device open. After the printing operation, the nozzle openings of the liquid ejection head are sealed with the capping device, and liquid is ejected from the nozzle openings to prevent the liquid from drying out in the nozzle openings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-017543 Summary of the Invention [Problem to be solved by the invention]

[0004] In devices such as the liquid ejection device, if a printing operation is performed with the capping device open for an extended period of time, the liquid remaining in the capping device will dry out. Therefore, if the nozzle opening is sealed with the capping device, the dried remaining liquid acts as a moisture absorbent, absorbing the liquid from the nozzle opening, causing the viscosity of the liquid in the nozzle to increase. If the next printing operation is started in this state, the increased viscosity may prevent the liquid from being ejected from the nozzle opening. However, even if the viscosity of the liquid in the nozzle opening increases in this way, the increased viscosity of the liquid will diffuse over time, reducing the viscosity of the liquid in the nozzle, thereby reducing liquid ejection problems caused by the increased viscosity.

[0005] In contrast, the liquid ejection device described above ejects the liquid while the capping device is sealed. However, if the viscosity of the liquid increases, it takes time for the liquid to moisten the inside of the capping device, and during that time the liquid in the nozzle is absorbed by the remaining liquid. As a result, it is not possible to reduce ejection failures of the liquid caused by moisture absorption by the capping device.

[0006] In view of the above, it is an object of the present invention to provide a printing device, a printing method and a program that can reduce ink ejection defects caused by moisture absorption by the cap. [Means for solving the problem]

[0007] A printing device according to one aspect of the present invention comprises a head having nozzles opening to an ejection surface and drive elements that apply ejection pressure to ink; a cap capable of covering the ejection surface; a moving device that moves the head and the cap relatively between a capped state in which the ejection surface is covered by the cap and an uncapped state in which the ejection surface is separated from the cap; a maintenance unit that performs a maintenance operation to discharge the ink from the nozzles; and a control device, wherein the control device is configured to perform a printing operation in which the ink is ejected from the nozzles based on image data in the uncapped state; a first ejection flushing operation after the printing operation to eject the ink from the nozzles; a capping operation after the first ejection flushing operation to place the head and the cap in the capped state; and a maintenance unit that performs a maintenance operation to discharge the ink from the nozzles based on image data in the uncapped state. a first timing operation for timing a first elapsed period, which is an elapsed period starting from after the rushing operation and before the capping operation, and when the next printing operation is performed, if the first elapsed period is equal to or greater than a first predetermined period, a first maintenance operation is performed as the maintenance operation before the next printing operation; if the first elapsed period is less than the first predetermined period, a second maintenance operation is performed as the maintenance operation, which can discharge more ink than the amount of ink discharged in the first maintenance operation, before the next printing operation; the end point of the first predetermined period is the timing when the first elapsed period is reached in the capped state before the first maintenance operation or the second maintenance operation, or the timing when the first elapsed period is reached in the uncapping state.

[0008] A printing method according to one aspect of the present invention is a printing method for a printing device including: a head having nozzles opening to an ejection surface and drive elements that apply ejection pressure to ink; a cap capable of covering the ejection surface; a moving device that moves the head and the cap relatively between a capped state in which the ejection surface is covered by the cap and an uncapped state in which the ejection surface is separated from the cap; and a maintenance unit that performs a maintenance operation to discharge the ink from the nozzles, the printing method including the steps of: a printing operation in which the ink is ejected from the nozzles based on image data in the uncapped state; a first ejection flushing operation in which the ink is ejected from the nozzles after the printing operation; a capping operation in which the head and the cap are put into the capped state after the first ejection flushing operation; and a first timing operation that times a first elapsed period, which is an elapsed period starting from a time after the capping operation and before the capping operation, and when performing the next printing operation, if the first elapsed period is equal to or greater than a first predetermined period, a first maintenance operation is performed as the maintenance operation before the next printing operation, and if the first elapsed period is less than the first predetermined period, a second maintenance operation that can discharge more ink than the amount of ink discharged in the first maintenance operation is performed as the maintenance operation before the next printing operation, and the end point of the first predetermined period is the timing when the first elapsed period is reached in the capped state before the first maintenance operation or the second maintenance operation, or the timing when the first elapsed period is reached in the uncapping state.

[0009] A program according to an aspect of the present invention is a program for causing a computer including a head having nozzles that open to an ejection surface and drive elements that apply ejection pressure to ink, a cap that can cover the ejection surface, a moving device that moves the head and the cap relatively between a capped state in which the ejection surface is covered by the cap and an uncapped state in which the ejection surface is separated from the cap, and a maintenance unit that performs a maintenance operation to discharge the ink from the nozzles, the program including causing a computer to perform a printing operation in the uncapped state to eject the ink from the nozzles based on image data, a first ejection flushing operation after the printing operation to eject the ink from the nozzles, a capping operation after the first ejection flushing operation to place the head and the cap in the capped state, and a maintenance unit that performs a maintenance operation to discharge the ink from the nozzles. and a first timing operation for timing a first elapsed period, which is an elapsed period starting from the capping operation and before the capping operation, and when the next printing operation is performed, if the first elapsed period is equal to or greater than a first predetermined period, a first maintenance operation is performed as the maintenance operation before the next printing operation, and if the first elapsed period is less than the first predetermined period, a second maintenance operation is performed as the maintenance operation, which can discharge more ink than the amount of ink discharged in the first maintenance operation, before the next printing operation, and the end point of the first predetermined period is the timing when the first elapsed period is reached in the capped state before the first maintenance operation or the second maintenance operation, or the timing when the first elapsed period is reached in the uncapping state. [Effects of the Invention]

[0010] The present invention has an effect of providing a printing device, a printing method and a program that can reduce ink ejection defects caused by moisture absorption by the cap.

[0011] The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a top view of a printing device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view of a cap unit. [Figure 3] Figure 3(a) is a diagram of the head and cap in a capped state, and Figure 3(b) is a diagram of the head and cap in an uncapped state. [Figure 4] FIG. 2 is a functional block diagram of the printing device. [Figure 5] 10 is a flowchart illustrating an example of a printing method of the printing device according to the embodiment. [Figure 6] 10 is a graph showing changes in ink discharge amount over time. [Figure 7] 10 is a flowchart showing an example of a printing method of a printing device according to a first modification. [Figure 8] 10 is a flowchart showing an example of a printing method of a printing device according to a second modification. [Figure 9] 11 is a flowchart illustrating an example of a printing method of a printing device according to a third modification. [Figure 10] 1 is a graph showing the change in the amount of water evaporation with temperature. [Figure 11] Fig. 11(a) is a table showing correction numbers for the environmental temperature and the dryness of the cap, and Fig. 11(b) is a table showing the increase number for the environmental temperature and the corrected increase number. [Figure 12] 10 is a flowchart illustrating an example of a printing method of a printing device according to a fourth modification. [Figure 13] 13 is a flowchart illustrating an example of a printing method of a printing device according to a fifth modification. [Figure 14] 13 is a flowchart showing an example of a printing method of a printing device according to a sixth modification. [Figure 15] 13 is a flowchart illustrating an example of a printing method of a printing device according to a seventh modification. [Figure 16] FIG. 1 shows a cap equipped with a suction pump and a suction tube. [Figure 17] 13 is a flowchart illustrating an example of a printing method of a printing device according to an eighth modification. [Figure 18] FIG. 10 is a diagram showing a head to which a pressure pump is connected by a supply pipe. [Figure 19] 13 is a flowchart illustrating an example of a printing method of a printing device according to a ninth modification. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Embodiment) <Printing device configuration> As shown in Fig. 1, a printing device 10 according to an embodiment of the present invention is a device that ejects ink from nozzles 21 of a head 20 onto a printing medium A and prints an image on the printing medium A using the ink. Below, an example in which the printing device 10 is applied to an inkjet printer will be described, but the printing device 10 is not limited to this. The printing medium A is, for example, a sheet of paper, cloth, or the like.

[0014] The printing device 10 is a serial head type and includes a head 20, a platen 11, a transport device 30, a scanning device 40, a storage tank 12, a cap 50, a moving device 14 (FIG. 3), a receiving unit 13, a housing 15, and a control device 60. The direction in which the head 20 and the cap 50 are moved by the moving device 14 is referred to as the up-down direction. Directions that intersect (e.g., perpendicular to) the up-down direction and intersect (e.g., perpendicular to) each other are referred to as the left-right direction and the front-rear direction. However, the arrangement of the printing device 10 is not limited to this.

[0015] The housing 15 houses the head 20, platen 11, transport device 30, scanning device 40, storage tank 12, cap 50, moving device 14, receiving unit 13, and control device 60. The head 20 has a plurality of nozzles 21, which are arranged in a row at intervals in the front-to-rear direction. The platen 11 has a flat upper surface and defines the distance between the printing medium A placed on the upper surface and the lower surface of the head 20, which is provided opposite to it. The storage tank 12 is in communication with the head 20 by a tube 12a. The storage tank 12 stores ink and supplies ink to the head 20 via the tube 12a.

[0016] The transport device 30 has, for example, two transport rollers 31 and a transport motor 32 (FIG. 4). The two transport rollers 31 are arranged parallel to each other in the front-to-rear direction, with the platen 11 sandwiched between them. The transport roller 31 has a central axis extending in the left-to-right direction and is connected to the transport motor 32. The transport roller 31 is rotated by the drive of the transport motor 32, transporting the print medium A in the front-to-rear direction on the platen 11.

[0017] The scanning device 40 has a carriage 41, two guide rails 42, a scanning motor 43 (FIG. 2), and an endless belt 44. The carriage 41 carries the head 20 and is supported by the two guide rails 42 so as to be movable in the left-right direction. The two guide rails 42 extend in the left-right direction above the platen 11 so as to sandwich the underside of the head 20 between them in the front-rear direction. The endless belt 44 extends in the left-right direction and is attached to the carriage 41 and the scanning motor 43. When the scanning motor 43 is driven, the endless belt 44 runs, and the carriage 41 moves back and forth in the left-right direction along the guide rails 42. As a result, the carriage 41 moves the head 20 in the left-right direction.

[0018] <head> As shown in Fig. 2, the head 20 has a flow path forming body 22 and a driving element 23. The flow path forming body 22 has, for example, a laminate of multiple plates 24 and a vibration plate 25, and the multiple plates are stacked in the vertical direction. The flow path forming body 22 has, for example, a rectangular parallelepiped shape, and has a lower surface as an ejection surface 22a. Holes and grooves of various sizes are formed in each plate by etching or the like, and the holes and grooves are combined inside the laminate to form multiple nozzles 21, multiple individual flow paths 26, and a manifold 27.

[0019] The manifold 27 communicates with the storage tank 12 (FIG. 1) and is also connected to a plurality of individual flow paths 26. The individual flow paths 26 are connected to the nozzles 21 and the manifold 27, and have pressure chambers 26a. The nozzles 21 extend downward from the individual flow paths 26 and open to the ejection surface 22a. The pressure chambers 26a of the individual flow paths 26 are covered by a vibration plate 25, and the pressure chambers 26a are connected to the nozzles 21.

[0020] The driving element 23 is, for example, a piezoelectric element, and is arranged on the vibration plate 25. The driving element 23 has a common electrode 23a, a piezoelectric layer 23b, and an individual electrode 23c. The common electrode 23a is laminated on the vibration plate 25, and the piezoelectric layer 23b is laminated on the common electrode 23a. The individual electrode 23c is laminated on the common electrode 23a so that it overlaps the corresponding pressure chamber 26a when viewed from above but does not overlap other pressure chambers 26a. The piezoelectric layer 23b expands and contracts between the common electrode 23a and the individual electrode 23c, and the vibration plate 25 deforms accordingly, applying pressure to the ink in the pressure chamber 26a. Note that a heat generating element, an electrostatic actuator, or the like may be used as the driving element 23, as long as it is capable of applying pressure to the ink in the pressure chamber 26a.

[0021] <Receiving part> As shown in FIG. 1 , the receiving portion 13 is located outside the printing range of the head 20 within the movement range of the head 20 in the left-right direction, for example, in a left maintenance range to the left of the platen 11. The receiving portion 13 is a container that receives ink ejected from the head 20 in the first ejection flushing operation and the second ejection flushing operation of the maintenance operation. The receiving portion 13 has an upper opening that faces the ejection surface 22a of the head 20 that is located in the left maintenance range. Note that a cap 50 may also be used as the receiving portion 13. Alternatively, an absorbent such as a porous material that can absorb ink may also be used as the receiving portion 13.

[0022] <Cap, moving device> 1, the cap 50 is located outside the printing range of the head 20 within the movement range of the head 20 in the left-right direction, for example, in a right maintenance range to the right of the platen 11. As shown in FIG. 3(a), the cap 50 is made of an elastic material such as rubber, and is a member that can cover the ejection surface 22a of the head 20. The cap 50 has an upper opening that is larger than the opening range of the nozzles 21 on the ejection surface 22a and faces the ejection surface 22a located in the right maintenance range.

[0023] The cap 50 has a rectangular, flat first bottom wall 51, an annular first side wall 52 rising upward from the edge of the first bottom wall 51, and an annular lip 53 protruding upward from the upper end of the first side wall 52. The lip 53 comes into contact with the ejection surface 22a to close a cap space defined by the first bottom wall 51, the first side wall 52, the lip 53, and the ejection surface 22a. An absorber that absorbs ink may be accommodated inside the cap 50.

[0024] A cap tip 54 is housed within the cap 50. The cap tip 54 is made of resin and has a rectangular flat plate shape, and is the same size as or slightly smaller than the size surrounded by the annular first side wall 52. The lower surface of the cap tip 54 contacts the first bottom wall 51, and the side surface of the cap tip 54 contacts the inner surface of the first side wall 52, so that the cap tip 54 supports the cap 50 from the inside so as to maintain the shape of the cap 50. Note that if the cap 50 can maintain its shape by itself, the cap tip 54 does not need to be housed within the cap 50.

[0025] The cap 50 is housed in a cap holder 55. The cap holder 55 is a container that is open at the top and has a rectangular, flat second bottom wall 56 and an annular second side wall 57 that rises upward from the edge of the second bottom wall 56. The upper surface of the second bottom wall 56 of the cap holder 55 contacts the lower surface of the first bottom wall 51 of the cap 50, and the inner surface of the second side wall 57 contacts the outer surface of the first side wall 52, so that the cap holder 55 supports the cap 50 from the outside so as to maintain the shape of the cap 50. Note that if the cap 50 can maintain its shape by itself, the cap 50 does not have to be housed in the cap holder 55.

[0026] The moving device 14 has a moving motor 14a. When the moving motor 14a is driven, the moving device 14 moves the cap 50 in the up and down direction. The moving device 14 moves the cap 50, which is positioned below the ejection surface 22a, upward, bringing the cap 50 closer to the ejection surface 22a. When the lip 53 comes into contact with the ejection surface 22a, the moving device 14 stops moving the cap 50. This brings the ejection surface 22a into a capping state in which the cap 50 covers the ejection surface 22a. In this capping state, a cap space is closed between the ejection surface 22a and the inner surface of the cap 50, reducing drying of ink from the nozzles 21 that open to the ejection surface 22a.

[0027] 3(b), the moving device 14 moves the cap 50 downward, away from the ejection surface 22a, and stops the movement of the cap 50. This causes the ejection surface 22a to enter an uncapping state where it is separated from the cap 50. In the uncapping state, a cap space is opened between the ejection surface 22a and the inner surface of the cap 50, and the ejection surface 22a appears to the outside.

[0028] <Control device> As shown in Fig. 4, the control device 60 is, for example, a computer and includes an interface 61, a calculation unit 62, and a storage unit 63. The interface 61 receives various data such as image data from external devices such as computers, cameras, networks, and recording media. The image data is, for example, raster data that represents the image to be printed on the print medium A. The control device 60 may be configured as a single device, or may be configured as multiple devices distributed in a distributed arrangement that work together to perform the operations of the printing device 10.

[0029] The storage unit 63 is a memory accessible from the calculation unit 62 and includes RAM and ROM. The RAM temporarily stores various data such as image data and data converted by the calculation unit 62. The ROM stores programs and tables for performing various data processing. The calculation unit 62 includes, for example, a processor such as a CPU, an integrated circuit such as an ASIC, or both, and controls each unit by executing programs stored in the ROM, thereby performing a printing operation, a first ejection flushing operation, a capping operation, a first timing operation, and a maintenance operation.

[0030] The control device 60 is electrically connected to the transport motor 32 of the transport device 30 via a transport drive circuit 65, and controls the driving of the transport motor 32. This controls the transport of the print medium A by the transport device 30. Furthermore, the control device 60 is electrically connected to the scan motor 43 of the scanning device 40 via a scan drive circuit 66, and controls the driving of the scan motor 43. This controls the movement of the head 20 by the scanning device 40.

[0031] The control device 60 is also electrically connected to the movement motor 14a of the movement device 14 via a movement drive circuit 67 and controls the driving of the movement motor 14a. As a result, the control device 60 drives the movement motor 14a to move the cap 50 in a direction approaching the ejection surface 22a, and when the cap 50 comes into contact with the ejection surface 22a, stops the movement motor 14a, establishing a capping state in which the cap 50 covers the ejection surface 22a. On the other hand, the control device 60 drives the movement motor 14a to move the cap 50 in a direction away from the ejection surface 22a, and stops the movement motor 14a at a predetermined position where the cap 50 is away from the ejection surface 22a, establishing an uncapping state in which the cap 50 is separated from the ejection surface 22a.

[0032] The control device 60 is also electrically connected to the drive elements 23 of the head 20 via a head drive circuit 64. The control device 60 outputs a control signal for the drive elements 23 to the head drive circuit 64, and the head drive circuit 64 generates a drive signal based on the control signal and outputs it to the drive elements 23. The drive elements 23 are driven in response to the drive signal to apply ejection pressure to the ink.

[0033] Here, for the printing operation, the control device 60 selects one type of waveform signal from multiple types of waveform signals for each region in accordance with the ink ejection amount based on the image data, and generates waveform selection data. Furthermore, for the first ejection flushing operation and the second ejection flushing operation of the maintenance operation, the control device 60 generates waveform selection data of a predetermined waveform signal for ejection. The control device 60 then outputs control data including the waveform selection data for the printing operation, the first ejection flushing operation, or the second ejection flushing operation, as well as multiple types of waveform signals, to the head drive circuit 64. The head drive circuit 64 selects one type of waveform signal based on the waveform selection data in the control data, and applies a voltage signal corresponding to the waveform of the selected waveform signal as a drive signal to the drive element 23. This drives the drive element 23 in accordance with the drive signal, changing the volume of the pressure chamber 26a, applying an ejection pressure to the ink, and ejecting the ink from the nozzle 21.

[0034] <Printing operation> In this printing device 10, the control device 60 executes a printing operation in which ink is ejected from the nozzles 21 based on image data in an uncapped state. Specifically, in the printing operation, the control device 60 ejects ink from the head 20 onto the printing medium A while moving the head 20 in a forward pass, which is one of the left and right directions within the printing range. After this forward pass, the control device 60 transports the printing medium A forward. Then, after the control device 60 transports the printing medium A, the control device 60 ejects ink from the head 20 onto the printing medium A while moving the head 20 in a forward pass, which is the other of the left and right directions within the printing range. After this return pass, the control device 60 transports the printing medium A forward.

[0035] In this way, the printing device 10 alternates between forward and backward passes during the pass, repeating the alternate passes and the transport of the print medium A to perform bidirectional printing. In this pass, ink ejected from the head 20 lands on the print medium A on the platen 11, which faces the underside of the head 20. Ink dots are formed at these impact positions, and an image made up of the dots is printed on the print medium A. Note that the printing device 10 may also perform unidirectional printing, in which ink is not ejected during one of the forward and backward passes, but is ejected during the other pass.

[0036] <Printing method> The printing method of the printer 10 is executed by the control device 60 in accordance with the flowchart of an example of a printing method shown in FIG. 5. First, the control device 60 acquires image data from an external device (step S1). Here, the ejection surface 22a of the head 20 is covered by the cap 50 in the right maintenance range. The control device 60 executes an uncapping operation to change the head 20 and the cap 50 from this capped state to an uncapped state (step S2). This causes the ejection surface 22a of the head 20 to appear outside.

[0037] Then, the control device 60 executes a printing operation in which ink is ejected from the nozzles 21 based on the image data in the uncapped state (step S3). In this printing operation, the control device 60 moves the head 20 from the right maintenance range to the printing range, and while moving the head 20 left and right in the printing range, drives the drive elements 23 with a drive signal that is a waveform signal based on the image data, causing ink to be ejected from the nozzles 21 of the head 20. However, during this time, the ejection surface 22a is exposed, and therefore the ink dries from the nozzles 21 that open to the ejection surface 22a.

[0038] For this reason, after the printing operation, the control device 60 executes a first ejection flushing operation in which ink is ejected from the nozzles 21 (step S4). In the first ejection flushing operation, the control device 60 moves the head 20 from the printing range to the left maintenance range, positions the head 20 on the receiving part 13, and positions the ejection surface 22a facing the upper opening of the receiving part 13. Then, the control device 60 drives the driving elements 23 with a driving signal based on a predetermined waveform signal, causing the ink to be ejected from the nozzles 21 to the receiving part 13. As a result, the ink, whose viscosity has increased due to drying, is expelled from the nozzles 21, and the fluidity of the ink in the nozzles 21 is restored.

[0039] After the first ejection flushing operation, the control device 60 then performs a capping operation to cap the head 20 and the cap 50 (step S5). In this capping operation, the control device 60 moves the head 20 from the left maintenance range to the right maintenance range, and then moves the cap 50 onto the head 20 to cover the ejection surface 22a of the head 20 with the cap 50. This closes the cap space between the ejection surface 22a and the cap 50, reducing drying of ink from the nozzles 21.

[0040] The control device 60 also executes a first timing operation to measure a first elapsed period, which is a period of time elapsed from the first ejection flushing operation (step S6). Ink is ejected from the nozzles 21 by the first ejection flushing operation in step S4, and after new ink is supplied to the nozzles 21, the liquid (e.g., moisture) in the ink evaporates from the nozzles 21, causing the ink to dry. Therefore, the time when the ink is ejected is set as the ink drying start time, and the time elapsed from this time is measured as the first elapsed period. The first timing operation may be executed simultaneously with the first ejection flushing operation, or may be executed before the first ejection flushing operation. If the first timing operation is executed before the first ejection flushing operation, the time difference between the start of the first timing operation and the start of the first ejection flushing operation may be a predetermined time difference, for example, within one second.

[0041] The control device 60 then determines whether to acquire image data for the printing operation following the printing operation of step S3 (step S7). When the control device 60 acquires image data for the next printing operation (step S7: YES), it determines whether the first elapsed period is a first predetermined period, for example, 5 minutes or more (step S8). In the capped state, the ejection surface 22a is covered by the cap 50. However, when the cap 50 dries, the liquid (e.g., water) in the ink evaporates, causing the ink to absorb moisture. Furthermore, if ink remains on the cap 50, the ink pigment dries and absorbs moisture from the ink in the nozzles 21. This moisture absorption by the cap 50 includes ink absorption by the cap 50 itself and / or the ink pigment remaining on the cap 50.

[0042] 6, the viscosity of the ink in the nozzles 21 increases over time due to moisture absorption by the cap 50, and the amount of ink discharged to restore the fluidity of the ink increases. However, as evaporation of the liquid progresses, the evaporated liquid reduces the dryness of the cap space and the cap 50, and the ink diffuses in the nozzles 21. As a result, the viscosity of the ink in the nozzles 21 decreases over time, and the amount of ink discharged to restore the fluidity decreases, and for example, the amount of change becomes small, below a predetermined amount, after the end of the first predetermined period.

[0043] Therefore, if the first elapsed period is equal to or greater than the first predetermined period (step S8: YES), the control device 60 performs an uncapping operation (step S9). Then, the control device 60 determines that the viscosity of the ink in the nozzles 21 has decreased, and performs a first maintenance operation as a maintenance operation (step S10), before performing the next printing operation (step S3). The maintenance operation includes a second ejection flushing operation that drives the drive elements 23 to eject ink from the nozzles 21. In this case, the maintenance unit that performs the maintenance operation to discharge ink from the nozzles 21 is the drive elements 23.

[0044] That is, in the uncapping operation, the control device 60 separates the cap 50 from the ejection surface 22a in the right maintenance range, changing the state from the capped state to the uncapped state. Then, in the second ejection flushing operation of the first maintenance operation, the control device 60 moves the head 20 from the right maintenance range to the left maintenance range, places the head 20 on the receiving part 13, and drives the drive element 23 a predetermined first number of times with a drive signal based on a predetermined waveform signal. This driving causes ink to be ejected from the nozzles 21, so that ink whose viscosity has increased due to drying is discharged from the nozzles 21, and the fluidity of the ink in the nozzles 21 is restored.

[0045] If the first elapsed period is less than the first predetermined period (step S8: NO), the control device 60 performs an uncapping operation (step S11). Then, the control device 60 determines that the viscosity of the ink in the nozzles 21 is higher than when the first elapsed period is equal to or greater than the first predetermined period, and performs a second maintenance operation (step S12) that can discharge more ink than the amount of ink discharged in the first maintenance operation, and then performs the next printing operation (step S3). The second maintenance operation includes a second ejection flushing operation that is performed a number of times greater than the number of times the drive element 23 is driven in the first maintenance operation. In this case, the maintenance unit is the drive element 23.

[0046] That is, in the uncapping operation, the control device 60 separates the cap 50 from the ejection surface 22a in the right maintenance range. Then, in the second ejection flushing operation of the second maintenance operation, the control device 60 moves the head 20 from the right maintenance range to the left maintenance range and drives the drive element 23 a second number of times using a drive signal based on a predetermined waveform signal. This second number of times is the first number of times plus a predetermined increment. Because the predetermined increment is an integer greater than or equal to 0, the second number of times is equal to or greater than the first number of times. Therefore, more ink may be discharged than in the first maintenance operation, and the second maintenance operation may restore ink fluidity to a greater extent than the first maintenance operation. This reduces ink ejection defects caused by moisture absorption by the cap 50. Note that, in the above example, the second number of times is obtained by adding the increment to the first number of times. However, the method of obtaining the second number of times is not limited thereto. For example, the second number of times may be obtained by multiplying the first number of times by the increment.

[0047] <Variation 1> 5, when the first elapsed period reaches the first predetermined period, the ejection surface 22a is in a capped state where it is covered by the cap 50. Then, after the first elapsed period reaches the first predetermined period, the first maintenance operation or the second maintenance operation is performed. Therefore, the end point of the first predetermined period is the timing when the first elapsed period reaches the capped state before the first maintenance operation or the second maintenance operation.

[0048] However, in the printer 10 according to Variation 1, the end point of the first predetermined period may be the timing when the first elapsed period is reached in the uncapping state before the first maintenance operation or the second maintenance operation. In this case, the printing method of the printer 10 is executed, for example, according to the flowchart shown in Fig. 7. In the flowchart of Fig. 7, the control device 60 executes the process of step S13 between the process of step S7 and the process of step S8, instead of the processes of steps S9 and S11 in Fig. 5. The rest of the process in Fig. 7 is the same as the process in Fig. 5.

[0049] In this case, when the control device 60 acquires image data for the next printing operation (step S7: YES), it performs an uncapping operation (step S13). The control device 60 also determines whether the first elapsed period is equal to or greater than a first predetermined period (step S8). If the first elapsed period is equal to or greater than the first predetermined period (step S8: YES), the control device 60 performs a first maintenance operation (step S10) and then performs the next printing operation (step S3). On the other hand, if the first elapsed period is less than the first predetermined period (step S8: NO), the control device 60 performs a second maintenance operation (step S12) and then performs the next printing operation (step S3). This restores the fluidity of the ink in the nozzles 21, thereby reducing ink ejection problems caused by moisture absorption by the cap 50.

[0050] <Variation 2> The printing device 10 according to the second modification is the same as in the above embodiment and first modification, but includes a housing 15 that houses the head 20 and a temperature sensor 16 that detects the ambient temperature inside the housing 15. During the maintenance operation, if the first elapsed period is less than the first predetermined period, the control device 60 executes the second ejection flushing operation a greater number of times when the ambient temperature is less than the first predetermined temperature than when the ambient temperature is equal to or greater than the first predetermined temperature.

[0051] 1, the housing 15 is a container having an internal space, and the head 20 and the temperature sensor 16 are disposed in this internal space. The temperature sensor 16 is a sensor that detects temperature, such as a thermistor, and is disposed in a position where it can detect the temperature of the ink in the head 20, for example, on or near the head 20 within the housing 15. As shown in FIG. 4, the temperature sensor 16 is connected to the control device 60, and outputs the detected temperature to the control device 60 as the environmental temperature.

[0052] The printing method of such a printer 10 is executed by the control device 60, for example, according to the flowchart of Fig. 8. In the flowchart of Fig. 8, the control device 60 executes the processes of steps S11a and S11b instead of the process of step S11 in Fig. 5, executes the processes of steps S12a and S12b instead of the process of step S12 in Fig. 5, and executes the process of step S14 between the process of step S8 and the process of step S11a or S11b. Other processes in Fig. 8 are the same as those in Fig. 5.

[0053] In the flowchart of FIG. 8 , if the first elapsed period is less than the first predetermined period (step S8: NO), the control device 60 acquires the environmental temperature from the temperature sensor 16 and determines whether the environmental temperature is equal to or higher than a first predetermined temperature, for example, 36° C. (step S14). The lower the environmental temperature, the lower the temperature of the ink in the head 20 and the higher the viscosity of the ink, resulting in a greater increase in ink viscosity due to evaporation of the liquid. This increases the likelihood of ink ejection failure due to moisture absorption by the cap 50. Therefore, the number of times the drive element 23 is driven in the second ejection flushing operation is increased when the environmental temperature is below the first predetermined temperature compared to when the environmental temperature is equal to or higher than the first predetermined temperature. This allows for the ejection of more ink than in the first maintenance operation, and the second maintenance operation can restore the fluidity of the ink more effectively than the first maintenance operation.

[0054] That is, when the environmental temperature is equal to or higher than the first predetermined temperature (step S14: YES), the ink has a low viscosity, so an increase in the ink viscosity due to evaporation is suppressed. Therefore, after performing the uncapping operation (step S11a), the control device 60 performs a second ejection flushing operation according to the first increment as a second maintenance operation (step S12a), and then performs the next printing operation (step S3).

[0055] In the second ejection flushing operation of the second maintenance operation, the control device 60 places the head 20 on the receiving portion 13 and drives the drive element 23 a second number of times using a drive signal based on a predetermined waveform signal. This second number of times is a number obtained by adding a predetermined first increment to the first number of times, where the first increment is, for example, 0. In this way, even if the first elapsed period is less than the first predetermined period and the viscosity of the ink in the nozzles 21 has increased due to moisture absorption by the cap 50, the increase in ink viscosity is kept low when the environmental temperature is high. Therefore, by not increasing the number of times the drive element 23 is driven in the second maintenance operation from the first number of times in the first maintenance operation, it is possible to reduce the amount of wasted ink ejection and the maintenance operation time while reducing ink ejection defects caused by moisture absorption by the cap 50.

[0056] On the other hand, if the environmental temperature is lower than the first predetermined temperature (step S14: NO), the increase in ink viscosity is large. Therefore, after performing the uncapping operation (step S11b), the control device 60 performs a second ejection flushing operation according to the second increment as a second maintenance operation (step S12b), and then performs the next printing operation (step S3).

[0057] In the second flushing operation of the second maintenance operation, the control device 60 places the head 20 on the receiving portion 13 and drives the drive element 23 a second number of times using a drive signal based on a predetermined waveform signal. This second number of times is a number obtained by adding a predetermined second increment to the first number of times, and the second increment is greater than the first increment, for example, 5. In this way, the viscosity of the ink in the nozzles 21 increases due to moisture absorption by the cap 50, and the increase in ink viscosity is greater when the ambient temperature is low. Therefore, by increasing the number of times the drive element 23 is driven in the second maintenance operation from the first number of times in the first maintenance operation, it is possible to reduce ink ejection defects caused by moisture absorption by the cap 50.

[0058] <Variation 3> In the printing device 10 according to the third modification, in the second modification, when the first elapsed period is less than the first predetermined period and the ambient temperature is less than the first predetermined temperature, the control device 60 performs the second ejection flushing operation more times when the ambient temperature is less than the second predetermined temperature than when the ambient temperature is equal to or higher than a second predetermined temperature that is lower than the first predetermined temperature during the maintenance operation.

[0059] Specifically, the printing method of the printer 10 is executed by the control device 60, for example, according to the flowchart of Fig. 9. In the flowchart of Fig. 9, the control device 60 executes the process of step S15 between the process of step S14 and the process of step S11b in Fig. 8, and executes the processes of steps S11c and S12c if step S15: YES. Other processes in Fig. 9 are the same as those in Fig. 8.

[0060] In the flowchart of FIG. 9, if the environmental temperature is less than the first predetermined temperature (step S14: NO), the control device 60 determines whether the environmental temperature is a second predetermined temperature (step S15). The second predetermined temperature is a temperature lower than the first predetermined temperature, for example, 18°C. The lower the environmental temperature, the greater the increase in viscosity of the ink in the nozzles 21. For this reason, the number of times the drive element 23 is driven in the second ejection flushing operation is increased when the environmental temperature is less than the second predetermined temperature compared to when the environmental temperature is equal to or higher than the second predetermined temperature. This allows more ink to be discharged than in the first maintenance operation, and the second maintenance operation can restore the fluidity of the ink more effectively than the first maintenance operation.

[0061] That is, if the environmental temperature is lower than the first predetermined temperature and higher than or equal to the second predetermined temperature (step S14: NO, S15: YES), the control device 60 performs an uncapping operation (step S11b), then performs a second ejection flushing operation according to the second increment as a second maintenance operation (step S12b), and then performs the next printing operation (step S3). This makes it possible to reduce ink ejection failures caused by moisture absorption by the cap 50 while suppressing the amount of wasted ink ejection and the maintenance operation time.

[0062] On the other hand, if the environmental temperature is lower than the second predetermined temperature (step S15: NO), the increase in ink viscosity is large. Therefore, after performing the uncapping operation (step S11c), the control device 60 performs a second ejection flushing operation according to the third increase number as a second maintenance operation (step S12c), and then performs the next printing operation (step S3).

[0063] In the second flushing operation of the second maintenance operation, the control device 60 places the head 20 on the receiving portion 13 and drives the drive element 23 a second number of times using a drive signal based on a predetermined waveform signal. This second number of times is a number obtained by adding a predetermined third increment to the first number of times, and the third increment is greater than the second increment, e.g., 10. In this manner, the viscosity of the ink in the nozzles 21 increases due to moisture absorption by the cap 50, and the increase in ink viscosity is greater when the environmental temperature is low. By increasing the number of times the drive element 23 is driven in the second maintenance operation when the environmental temperature is below the second predetermined temperature compared to when the environmental temperature is equal to or higher than the second predetermined temperature, poor ink ejection caused by moisture absorption by the cap 50 can be reduced.

[0064] <Variation 4> In the printing device 10 according to the fourth modification, the control device 60 in the above-described embodiment and modifications 1 to 3 executes a correction operation to correct the number of times of driving in accordance with the degree of dryness of the cap 50 before the capping operation.

[0065] For example, the printing device 10 includes a temperature sensor 16 that detects the environmental temperature within the housing 15, and a humidity sensor 17 that detects the environmental humidity within the housing 15. Before the capping operation, the control device 60 executes an uncapping operation that puts the head 20 and the cap 50 into an uncapping state, and a second timing operation that measures a second elapsed period, which is the period elapsed from the uncapping operation to the capping operation. In addition, in the correction operation, the control device 60 corrects the number of drives in accordance with the degree of dryness based on the environmental temperature, environmental humidity, and the second elapsed period.

[0066] Specifically, as shown in FIG. 1, the humidity sensor 17 is a sensor that detects humidity, and may be, for example, a resistive or capacitive sensor. The humidity sensor 17 is disposed within the housing 15, and is preferably disposed at a position where it can detect the humidity of the cap 50, for example, on or near the cap 50. As shown in FIG. 4, the humidity sensor 17 is connected to the control device 60 and outputs the detected humidity to the control device 60 as the environmental humidity within the housing 15. The temperature sensor 16 also obtains the temperature of the cap 50 as well as the temperature of the ink in the head 20, and is therefore disposed at a position where it can detect these temperatures. Note that, although one temperature sensor 16 is used here to obtain the temperatures of the ink and the cap 50, separate temperature sensors may be used for obtaining the temperature of the ink and the temperature of the cap 50.

[0067] As shown in Figure 10, the amount of water evaporation (kg / m 2 / h) increases as the environmental temperature (°C) increases, decreases as the environmental humidity (%) increases, and increases as the second elapsed period (h) increases. The greater the amount of water evaporation, the drier the cap 50 becomes, and therefore the degree of dryness of the cap 50 increases. For example, the degree of dryness of the cap 50 is proportional to the amount of water evaporation and can be expressed as k × the amount of water evaporation, where k is a predetermined coefficient. The relationship between the degree of dryness of the cap 50 and the environmental temperature, environmental humidity, and second elapsed period is predetermined and stored in the memory unit 63.

[0068] Note that the dryness degree of the cap 50 represents the degree of dryness of the cap 50 in the uncapping state, and therefore the environmental temperature and humidity on which the dryness degree is based are detected in the uncapping state before the capping operation. However, because the environmental temperature and humidity do not change drastically due to the capping operation, they may be detected after the capping operation. Furthermore, the dryness degree of the cap 50 may be based on, for example, at least one of the environmental temperature, the environmental humidity, and the second elapsed period. Alternatively, the dryness degree of the cap 50 may be a predetermined value, or may be a value input into the control device 60 by a user or an external device. Furthermore, the dryness degree of the cap 50 represents the degree of dryness of the ink remaining on the cap 50. However, the dryness degree of the cap 50 may represent the degree of dryness of at least one of the cap 50 itself and the ink remaining on the cap 50.

[0069] The greater the dryness of the cap 50, the greater the amount of moisture absorbed by the cap 50 from the ink in the nozzles 21, resulting in a higher viscosity of the ink. Therefore, the control device 60 executes a correction operation to correct the number of times the drive element 23 is driven in the second ejection flushing operation of the maintenance operation. In this correction operation, the control device 60 corrects the number of times the drive element 23 is driven in the second ejection flushing operation of the maintenance operation so that the greater the dryness of the cap 50, the greater the number of times the drive element 23 is driven in the second ejection flushing operation of the maintenance operation.

[0070] For example, as shown in the table of FIG. 11(a), the dryness degree of the cap 50, the ambient temperature, and the correction number for the number of times the drive element 23 is driven during the second ejection flushing operation are predetermined and stored in the memory unit 63. This ambient temperature is the temperature that serves as the basis for calculating the ink temperature and is detected by the temperature sensor 16 during the correction operation. In the table of FIG. 11(a), the greater the dryness degree of the cap 50, the greater the increase in ink viscosity due to moisture absorption by the cap 50. Therefore, when the dryness degree is equal to or greater than a predetermined level, the correction number is larger than when the dryness degree is less than the predetermined level. Furthermore, the higher the ambient temperature, the higher the ink temperature and the lower the ink viscosity, resulting in a smaller correction number. Therefore, the second correction number, which is the correction number when the ambient temperature is less than the first predetermined temperature and equal to or greater than the second predetermined temperature, is larger than the first correction number, which is the correction number when the ambient temperature is equal to or greater than the first predetermined temperature, and is smaller than the third correction number, which is the correction number when the ambient temperature is less than the second predetermined temperature. This correction number is a number used to correct the increase number and is, for example, added to or multiplied by the increase number.

[0071] For example, as shown in the table of FIG. 11(b), the first increment is predefined as 0, the second increment as 5, and the third increment as 10. A correction number corresponding to the dryness level is added to each increment to correct the increment, and the corrected increment is added to the first count to obtain the second count. Here, when the environmental temperature is equal to or higher than a first predetermined temperature and the dryness level is less than a predetermined level, the corrected first increment is the sum of the first increment (0) and the first correction number (0), which is 0, and the second count is the sum of the first increment (0) and the corrected first increment (0). When the environmental temperature is equal to or higher than the first predetermined temperature and the dryness level is greater than a predetermined level, the corrected first increment is the sum of the first increment (0) and the first correction number (5), which is 5, and the second count is the sum of the first increment (0) and the corrected first increment (5).

[0072] In this case, the printing method of the printer 10 is executed, for example, according to the flowchart of Fig. 12. In the flowchart of Fig. 12, the control device 60 executes the process of step S16 between the process of step S2 and the process of step S3 of Fig. 9, executes the process of step S17 between the process of step S5 and the process of step S6 of Fig. 9, and executes the processes of steps S12a', S12b', and S12c' instead of the processes of steps S12a, S12b, and S12c of Fig. 9. In addition, the control device 60 executes the process of step S18a between the process of step S11a and the process of step S12a', executes the process of step S18b between the process of step S11b and the process of step S12b', and executes the process of step S18c between the process of step S11c and the process of step S12c'. The rest of the process of Fig. 12 is the same as the process of Fig. 9.

[0073] In the flowchart of FIG. 12, after the control device 60 performs the uncapping operation (steps S2, S11a, S11b, and S11c), it performs a second timing operation (step S16). In the second timing operation, the control device 60 starts timing a second elapsed period, which is the time elapsed since the uncapping operation. Then, after the control device 60 performs the capping operation (step S5), it ends the elapsed period and acquires the second elapsed period. This second elapsed period is a period in the uncapping state during which the inner surface of the cap 50 covering the ejection surface 22a is exposed to the outside and dries. Note that the second timing operation may be performed simultaneously with the uncapping operation, or may be performed before the uncapping operation. When the second timing operation is performed before the uncapping operation, the time difference between the start of the second timing operation and the start of the uncapping operation may be a predetermined time difference, for example, within one second.

[0074] The control device 60 also acquires the dryness degree of the cap 50 (step S17). Here, the control device 60 acquires the environmental temperature from the temperature sensor 16 and the environmental humidity from the humidity sensor 17. Then, the control device 60 acquires the dryness degree of the cap 50 from a predetermined correspondence relationship based on the environmental temperature, the environmental humidity, and the second elapsed period.

[0075] The control device 60 also performs a first timing operation to measure a first elapsed period, which is a period elapsed from the first ejection flushing operation (step S6). The control device 60 then acquires image data for the next printing operation (step S7: YES). If the first elapsed period is less than a first predetermined period (step S8: NO) and the ambient temperature is equal to or higher than a first predetermined temperature (step S14: YES), the control device 60 performs an uncapping operation (step S11a). The control device 60 also performs a correction operation (step S18a) to correct the first increment by the first correction number determined according to the dryness level of step S17. The control device 60 then performs a second ejection flushing operation according to the corrected first increment as a second maintenance operation (step S12a'), and then performs the next printing operation (step S3). In this second ejection flushing operation, the drive element 23 is driven a second number of times, which is the first number of times plus the corrected first increase number, thereby reducing the amount of wasted ink ejection and the maintenance operation time while reducing ink ejection failure caused by moisture absorption by the cap 50.

[0076] On the other hand, if the environmental temperature is below the first predetermined temperature (step S14: NO) but is equal to or higher than the second predetermined temperature (step S15: YES), the control device 60 performs an uncapping operation (step S11b). The control device 60 also performs a correction operation (step S18b) to correct the second increment by the second correction number determined in step S17 according to the dryness level. The control device 60 then performs a second flushing operation according to the corrected second increment as the second maintenance operation (step S12b'), and then performs the next printing operation (step S3). In this second flushing operation, the drive element 23 is driven a second number of times, which is the first number plus the corrected second increment, thereby reducing the amount of wasted ink ejection and the maintenance operation time, while also reducing ink ejection defects due to moisture absorption by the cap 50.

[0077] On the other hand, if the environmental temperature is lower than the second predetermined temperature (step S15: NO), the control device 60 performs an uncapping operation (step S11c). The control device 60 also performs a correction operation (step S18c), correcting the third increment by a third correction number determined based on the dryness level determined in step S17. The control device 60 then performs a second flushing operation based on the corrected third increment as the second maintenance operation (step S12c'), and then performs the next printing operation (step S3). In this second flushing operation, the drive element 23 is driven a second number of times, which is the first number of times plus the corrected third increment, thereby reducing ink ejection defects caused by moisture absorption by the cap 50.

[0078] <Variation 5> The printing device 10 according to the fifth modification executes a non-ejection flushing operation in which ink in the nozzles 21 is vibrated without ejecting ink from the nozzles 21 in the capped state in the above-described embodiment and modifications 1 to 4.

[0079] For example, the printing method of the printer 10 is performed according to the flowchart of Fig. 13. In the flowchart of Fig. 13, the control device 60 performs the process of step S19 between the process of step S6 and the process of step S7 of Fig. 5. Other processes in Fig. 13 are the same as those in Fig. 5.

[0080] In the flowchart of FIG. 13, the control device 60 performs the capping operation (step S5) and the first timing operation (step S6) after the uncapping operation (steps S2, S9, S11), the printing operation (step S3), and the ejection maintenance operation (step S4). In the uncapping state before the capping operation, residual ink and the like in the cap 50 dries. Therefore, when the ejection surface 22a is covered with the cap 50 that has dried during the capping operation, the ink in the nozzles 21 that open to the ejection surface 22a through the cap 50 dries, and the viscosity of the ink increases. Therefore, the control device 60 performs the non-ejection flushing operation after the capping operation (step S19). The non-ejection flushing operation is performed for a predetermined period, for example, five minutes.

[0081] During the non-ejection flushing operation, the control device 60 generates waveform selection data for a predetermined non-ejection waveform signal and outputs control data including the waveform selection data and multiple waveform signals to the head drive circuit 64. The head drive circuit 64 selects a non-ejection waveform signal based on the waveform selection data in the control data and applies a voltage signal corresponding to the waveform of the selected waveform signal to the drive element 23 as a drive signal. This causes the drive element 23 to operate in response to the drive signal, changing the volume of the pressure chamber 26a and applying a non-ejection pressure to the ink, causing the ink to vibrate without being ejected from the nozzle 21. This vibration diffuses the ink, which has increased in viscosity, reducing the viscosity of the ink in the nozzle 21. Therefore, as shown by the dashed line in FIG. 6, the maximum amount of ink discharged to restore fluidity is lower than when the non-ejection flushing operation is not performed, as shown by the solid line in FIG. 6. This reduces ink ejection problems caused by moisture absorption by the cap 50.

[0082] <Variation 6> In the printing device 10 according to the sixth modification, the control device 60 in the fifth modification executes a third timing operation to measure a third elapsed period, which is the period that has elapsed since the capping operation. The control device 60 starts the non-ejection flushing operation after the capping operation, and ends the operation when the third elapsed period reaches a third predetermined period.

[0083] For example, the printing method of the printer 10 is performed according to the flowchart of Fig. 14. In the flowchart of Fig. 14, the control device 60 performs the process of step S20 between the process of step S6 and the process of step S19 in Fig. 13, and performs the processes of steps S21 and S22 between the process of step S19 and the process of step S7. Other processes in Fig. 14 are the same as those in Fig. 13.

[0084] In the flowchart of FIG. 14, the control device 60 executes a first timing operation (step S6) after the uncapping operation (steps S2, S9, S11), the printing operation (step S3), and the ejection maintenance operation (step S4). After executing the capping operation (step S5), the control device 60 executes a third timing operation (step S20) and a non-ejection flushing operation (step S19). In the third timing operation, the control device 60 times a third elapsed period starting from the capping operation. The third timing operation may be executed simultaneously with the capping operation, or may be executed before the capping operation. When the third timing operation is executed before the capping operation, the time difference between the start of the third timing operation and the start of the capping operation may be a predetermined time difference, for example, within one second.

[0085] Furthermore, during the non-ejection maintenance operation, the control device 60 drives the drive elements 23 to vibrate without ejecting ink from the nozzles 21, thereby diffusing the ink in the nozzles 21 and suppressing an increase in viscosity. For example, in the example of FIG. 6, the ink discharge amount for fluidity recovery, as indicated by the dashed line with the non-ejection maintenance operation, becomes lower than the solid line without the non-ejection maintenance operation after its peak. In this case, the discharge amount indicated by the dashed line becomes smaller than the predetermined amount earlier than the discharge amount indicated by the solid line. This point in time is, for example, the end point of the third predetermined period, which is before the end point of the first predetermined period. Therefore, the control device 60 starts the non-ejection flushing operation (step S19) immediately after the capping operation (step S5). When the third elapsed period reaches the third predetermined period (step S21: YES), the control device 60 ends the non-ejection maintenance operation (step S22) and executes the processes from step S7 onward. This reduces ink discharge problems caused by moisture absorption by the cap 50.

[0086] <Variation 7> In the printing device 10 according to variant 7, when the control device 60 acquires image data for the next printing operation before the third elapsed period reaches the third predetermined period, it terminates the non-ejection flushing operation, then performs a third maintenance operation that can eject more ink than the first maintenance operation as a maintenance operation, before performing the next printing operation.

[0087] For example, the printing method of the printer 10 is performed according to the flowchart of Fig. 15. In the flowchart of Fig. 15, the control device 60 performs the processes of steps S23 to S26 after the process of step S21 of Fig. 14. Other processes in Fig. 15 are the same as the processes in Fig. 14.

[0088] 15, after the non-ejection flushing operation is started (step S19), the control device 60 determines whether the third elapsed period has reached the third predetermined period (step S21). If the third elapsed period has reached the third predetermined period (step S21: YES), the control device 60 ends the non-ejection maintenance operation (step S22) and executes the processes from step S7 onwards. On the other hand, if the image data for the next print is acquired (step S23) before the third elapsed period has reached the third predetermined period (step S21: NO), the control device 60 ends the non-ejection flushing operation (step S24).

[0089] After the uncapping operation (step S25), the control device 60 performs a third maintenance operation (step S26) that can discharge more ink than the amount of ink discharged in the first maintenance operation, and then performs the next printing operation (step S3). The third maintenance operation includes, for example, a second ejection flushing operation that is performed a number of times greater than the number of times the drive element 23 is driven in the first maintenance operation. In this case, the maintenance unit is the drive element 23.

[0090] In the second ejection flushing operation of the third maintenance operation, the control device 60 drives the drive element 23 a third number of times using a drive signal based on a predetermined waveform signal. This driving causes ink to be ejected from the nozzle 21. This third number of times is the first number plus a predetermined increment. Furthermore, as shown in FIG. 6 , because the non-ejection flushing operation reduces the maximum amount of ink discharged, the third number of times may be less than the second number of times when the non-ejection flushing operation is not performed. This third maintenance operation can restore ink fluidity more effectively than the first maintenance operation. Therefore, even if the duration of the non-ejection flushing operation is shorter than the third predetermined period, the fluidity of the ink in the nozzle 21 is restored, and ink ejection defects caused by moisture absorption by the cap 50 can be reduced.

[0091] <Variation 8> In the above-described embodiment and modifications 1 to 7, the control device 60 uses the drive element 23 as the maintenance unit and executes the second ejection flushing operation as the maintenance operation. However, the maintenance operation is not limited to this as long as it discharges ink from the nozzles 21, and may include, for example, a suction purge operation.

[0092] In this case, as shown in FIG. 16 , the printing device 10 is equipped with a suction pump 18 as a maintenance unit. The suction pump 18 is connected to the cap 50 by a suction tube 18a. The suction tube 18a penetrates the cap 50, the cap holder 55, and the cap tip 54, and opens to the inner surface of the cap tip 54. The suction pump 18 is connected to the suction tube 18a and communicates with the cap space between the cap 50 and the ejection surface 22a via the suction tube 18a. The suction pump 18 is also connected to a control device 60 ( FIG. 4 ), and its drive is controlled by the control device 60 to perform a suction purge operation. In the suction purge operation, when the suction pump 18 is driven in the capping state, air is sucked from the cap space, the cap space is depressurized, and ink is discharged from the nozzles 21.

[0093] For example, the printing method of the printing device 10 is performed according to the flowchart of Fig. 17. In the flowchart of Fig. 17, the control device 60 performs a suction purge operation as a maintenance operation in S10' and S12' instead of the second ejection flushing operation as a maintenance operation in steps S10 and S12 of Fig. 5. Also, instead of the uncapping operation in steps S9 and S11 after the processing of step S8 of Fig. 5, the control device 60 performs an uncapping operation in S27 after the processing of S10' and S12'. Other processing in Fig. 17 is the same as the processing in Fig. 5.

[0094] 17, the control device 60 acquires image data for the next printing operation (step S7: YES) and determines whether the first elapsed period is equal to or greater than the first predetermined period (step S8). If the first elapsed period is equal to or greater than the first predetermined period (step S8: YES), the control device 60 executes a suction purge operation as a first maintenance operation in the capped state (step S10'), executes an uncapping operation (step S27), and then executes the next printing operation (step S3).

[0095] On the other hand, if the first elapsed period is less than the first predetermined period (step S8: NO), the control device 60 performs a suction purge operation as a second maintenance operation in the capped state (step S12'), performs an uncapping operation (step S27), and then performs the next printing operation (step S3). The suction time of the suction purge operation of this second maintenance operation is longer than the suction time of the suction purge operation of the first maintenance operation. This second maintenance operation can discharge more ink than the amount discharged in the first maintenance operation, thereby restoring the fluidity of the ink in the nozzles 21 and reducing ink discharge problems caused by moisture absorption by the cap 50.

[0096] In the printing device 10 of Variation 8, in Variation 2, the control device 60 performs a suction purge operation of the suction pump 18 for a longer drive time when the environmental temperature is below a first predetermined temperature than when the environmental temperature is above a first predetermined temperature. Furthermore, in Variation 3, the control device 60 performs a suction purge operation of the suction pump 18 for a longer drive time when the environmental temperature is below a second predetermined temperature than when the environmental temperature is above a second predetermined temperature. Furthermore, in Variation 4, the control device 60 performs a suction purge operation of the suction pump 18 for a longer drive time when the degree of dryness is above a predetermined level than when the degree of dryness is below a predetermined level.

[0097] <Variation 9> In the above-described embodiment and modifications 1 to 7, the control device 60 uses the drive element 23 as the maintenance unit and executes the second ejection flushing operation as the maintenance operation. However, the maintenance operation is not limited to this as long as it causes ink to be discharged from the nozzles 21, and may include, for example, a pressurized purge operation.

[0098] In this case, as shown in FIG. 18 , the printing apparatus 10 includes a pressure pump 19 as a maintenance unit. The pressure pump 19 is connected to the head 20 and the sub-tank 28 via a supply pipe 28a. The sub-tank 28 is mounted on the head 20, connected to the storage tank 12 via a tube 12a, and connected to a manifold 27 ( FIG. 2 ) of the head 20 via the supply pipe 28a. The pressure pump 19 is connected to the supply pipe 28a and applies pressure to the ink so as to supply the ink from the sub-tank 28 to the head 20. The pressure pump 19 is connected to a control device 60 ( FIG. 4 ), and the control device 60 controls its operation to perform a pressure purge operation. In the pressure purge operation, when the head 20 is placed on the receiving portion 13 or the cap 50 and the pressure pump 19 is driven in an uncapped state, pressure is applied to the ink in the nozzles 21, causing the ink to be discharged from the nozzles 21. Note that the pressure purge operation may also be performed in a capped state, causing the ink to be discharged from the nozzles 21.

[0099] For example, the printing method of the printing device 10 is performed according to the flowchart of Fig. 19. In the flowchart of Fig. 19, the control device 60 performs a pressurized purge operation as a maintenance operation in steps S10" and S12" instead of the second ejection flushing operation as a maintenance operation in steps S10 and S12 of Fig. 5. Other processes in Fig. 19 are the same as those in Fig. 5.

[0100] In the flowchart of FIG. 19, the control device 60 acquires image data for the next printing operation (step S7: YES), and determines whether the first elapsed period is equal to or greater than the first predetermined period (step S8). If the first elapsed period is equal to or greater than the first predetermined period (step S8: YES), the control device 60 executes an uncapping operation (step S9), and in the uncapping state executes a pressurized purge operation as a first maintenance operation (step S10), and then executes the next printing operation (step S3).

[0101] On the other hand, if the first elapsed period is less than the first predetermined period (step S8: NO), the control device 60 performs an uncapping operation (step S11), and then performs a pressurized purge operation as a second maintenance operation in the uncapping state (step S12"), before performing the next printing operation (step S3). The pressurization time of the pressurized purge operation of this second maintenance operation is longer than the pressurization time of the pressurized purge operation of the first maintenance operation. This second maintenance operation makes it possible to discharge more ink than the amount of ink discharged in the first maintenance operation, thereby recovering the fluidity of the ink in the nozzles 21 and reducing ink discharge problems caused by moisture absorption by the cap 50.

[0102] In the printing device 10 of Variation 9, in Variation 2, the control device 60 performs a pressurized purge operation of the pressurizing pump 19 for a longer drive time when the environmental temperature is below a first predetermined temperature than when the environmental temperature is above a first predetermined temperature. Furthermore, in Variation 32, the control device 60 performs a pressurized purge operation of the pressurizing pump 19 for a longer drive time when the environmental temperature is below a second predetermined temperature than when the environmental temperature is above a second predetermined temperature. Furthermore, in Variation 42, the control device 60 performs a pressurized purge operation of the pressurizing pump 19 for a longer drive time when the degree of dryness is above a predetermined level than when the degree of dryness is below a predetermined level.

[0103] <Other variations> In all of the above embodiments and modifications, the moving device 14 moves the cap 50 without moving the head 20 in the vertical direction. However, the moving device 14 only needs to move the head 20 and the cap 50 relative to each other between the capped state and the uncapped state. Therefore, the moving device 14 may move the head 20 without moving the cap 50 in the vertical direction. Alternatively, the moving device 14 may move the head 20 and the cap 50 in the vertical direction.

[0104] In all of the above embodiments and modifications, the control device 60, in the first timing operation, times the first elapsed period, which is an elapsed period starting from the first ejection flushing operation. However, the first elapsed period in the first timing operation is not limited to this, as long as it starts from a time after the first ejection flushing operation and before the capping operation. For example, the first elapsed period may be timed starting from the capping operation. Alternatively, the first elapsed period may be timed starting from a predetermined timing between the first ejection flushing operation and the capping operation.

[0105] In all of the above embodiments and modifications, the first ejection flushing operation and the second ejection flushing operation of the maintenance operation are performed on the receiving unit 13 in an uncapping state. However, the first ejection flushing operation and the second ejection flushing operation may be performed in a capping state. In this case, the printing device 10 may use the cap 50 as the receiving unit 13, and a moisture-absorbing material may be provided inside the cap 50. Also, in the printing method, the control device 60 performs the uncapping operation after the second ejection flushing operation as a maintenance operation. As a result, ink discharged from the nozzles 21 by the second ejection flushing operation is discharged into the cap 50 and absorbed by the moisture-absorbing material.

[0106] It should be noted that all of the above embodiments may be combined with one another as long as they do not exclude one another. Furthermore, many improvements and other embodiments of the present invention will be apparent to those skilled in the art from the above description. Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function of the present invention may be substantially changed without departing from the spirit of the present invention. [Industrial Applicability]

[0107] The present invention can be applied to a printing apparatus that can reduce ink ejection defects caused by moisture absorption by the cap, a printing method thereof, and a program. [Explanation of symbols]

[0108] 10:Printing device 14: Mobile device 15: Housing 16: Temperature sensor 17: Humidity sensor 18: Suction pump (maintenance section) 19: Pressure pump (maintenance section) 20: Head 21: Nozzle 22a:Discharge surface 23: Drive element (maintenance part) 50: Cap 60: Control device

Claims

1. a head having nozzles opening on an ejection surface and a drive element that applies ejection pressure to ink; a cap capable of covering the ejection surface; a moving device that moves the head and the cap relative to each other between a capped state in which the ejection surface is covered by the cap and an uncapped state in which the ejection surface is separated from the cap; a maintenance unit that performs a maintenance operation to discharge the ink from the nozzles; a control device; The control device a printing operation in which the ink is ejected from the nozzles based on image data in the uncapped state; a first ejection flushing operation for ejecting the ink from the nozzles after the printing operation; a capping operation for placing the head and the cap in the capped state after the first ejection flushing operation; a first timing operation for timing a first elapsed period that starts after the first flushing operation and before the capping operation and ends after the image data for the next printing operation is acquired; When the following printing operation is performed: If the first elapsed period is a period longer than the period from the starting point to the point at which the viscosity of the ink in the nozzle changes from increasing to decreasing and is equal to or longer than a first predetermined period whose end point is the point at which the amount of change in the viscosity becomes equal to or less than a predetermined amount, a first maintenance operation is performed as the maintenance operation, and then the next printing operation is performed; If the first elapsed period is longer than the period from the starting point to the point at which the viscosity of the ink in the nozzle changes from increasing to decreasing and is shorter than the first predetermined period, a printing device performs a second maintenance operation as the maintenance operation, which can discharge an amount of ink that exceeds the amount of ink discharged in the first maintenance operation, and then performs the next printing operation.

2. the maintenance operation includes a second ejection flushing operation in which the drive elements are driven to eject the ink from the nozzles, The printing apparatus according to claim 1 , wherein the second maintenance operation includes the second ejection flushing operation the number of times of driving the drive element being equal to or greater than the number of times of driving the drive element in the first maintenance operation.

3. a housing that houses the head; a temperature sensor for detecting an environmental temperature inside the housing; The control device 3. The printing device according to claim 2, wherein, in the maintenance operation, if the first elapsed period is less than the first predetermined period, the second ejection flushing operation is performed a greater number of times when the environmental temperature is less than the first predetermined temperature than when the environmental temperature is equal to or higher than the first predetermined temperature.

4. 4. The printing device according to claim 3, wherein, during the maintenance operation, when the first elapsed period is less than the first predetermined period and the environmental temperature is less than the first predetermined temperature, the control device performs the second ejection flushing operation a greater number of times when the environmental temperature is less than the second predetermined temperature than when the environmental temperature is equal to or greater than a second predetermined temperature that is lower than the first predetermined temperature.

5. The printing apparatus according to claim 2 , wherein the control device executes a correction operation to correct the number of times the cap is driven depending on the degree of dryness of the cap before the capping operation.

6. a temperature sensor for detecting an environmental temperature inside the housing; a humidity sensor for detecting the environmental humidity inside the housing; The control device an uncapping operation for placing the head and the cap in the uncapping state before the capping operation; a second timing operation for timing a second elapsed period that is an elapsed period from the uncapping operation to the capping operation; The printing apparatus according to claim 5 , wherein the correcting operation corrects the number of times of driving in accordance with the degree of dryness based on the environmental temperature, the environmental humidity, and the second elapsed period.

7. The printing apparatus according to claim 1 , wherein the control device, in the capping state, executes a non-ejection flushing operation in which the ink in the nozzles is vibrated without ejecting the ink from the nozzles.

8. The control device performing a third timing operation for timing a third elapsed period that is an elapsed period from the capping operation; The printing apparatus according to claim 7 , wherein the non-ejection flushing operation is started after the capping operation and is ended when the third elapsed period reaches a third predetermined period.

9. The printing device of claim 8, wherein when the control device acquires the image data for the next printing operation before the third elapsed period reaches the third predetermined period, the control device terminates the non-ejection flushing operation, then performs a third maintenance operation as the maintenance operation, which can eject more ink than the first maintenance operation, before performing the next printing operation.

10. a head having nozzles opening on an ejection surface and a drive element that applies ejection pressure to ink; a cap capable of covering the ejection surface; a moving device that moves the head and the cap relative to each other between a capped state in which the ejection surface is covered by the cap and an uncapped state in which the ejection surface is separated from the cap; a maintenance unit that performs a maintenance operation to discharge the ink from the nozzles, a printing operation in which the ink is ejected from the nozzles based on image data in the uncapped state; a first ejection flushing operation for ejecting the ink from the nozzles after the printing operation; a capping operation for placing the head and the cap in the capped state after the first ejection flushing operation; a first timing operation that times a first elapsed period that starts after the first flushing operation and before the capping operation and ends after the image data for the next printing operation is acquired; When the following printing operation is performed: If the first elapsed period is longer than the period from the starting point to the point at which the viscosity of the ink in the nozzle changes from increasing to decreasing and is equal to or longer than a first predetermined period whose end point is the point at which the amount of change in the viscosity becomes equal to or less than a predetermined amount, a first maintenance operation is performed as the maintenance operation, and then the next printing operation is performed; A printing method for a printing device, in which, if the first elapsed period is longer than the period from the starting point to the point at which the viscosity of the ink in the nozzle changes from increasing to decreasing and is shorter than the first predetermined period, a second maintenance operation is performed as the maintenance operation, which can discharge an amount of ink that exceeds the amount of ink discharged in the first maintenance operation, and then the next printing operation is performed.

11. a head having nozzles opening on an ejection surface and a drive element that applies ejection pressure to ink; a cap capable of covering the ejection surface; a moving device that moves the head and the cap relative to each other between a capped state in which the ejection surface is covered by the cap and an uncapped state in which the ejection surface is separated from the cap; a maintenance unit that performs a maintenance operation to discharge the ink from the nozzles, a printing operation in which the ink is ejected from the nozzles based on image data in the uncapped state; a first ejection flushing operation for ejecting the ink from the nozzles after the printing operation; a capping operation for placing the head and the cap in the capped state after the first ejection flushing operation; a first timing operation that times a first elapsed period that starts after the first flushing operation and before the capping operation and ends after the image data for the next printing operation is acquired; When the following printing operation is performed: If the first elapsed period is longer than the period from the starting point to the point at which the viscosity of the ink in the nozzle changes from increasing to decreasing and is equal to or longer than a first predetermined period whose end point is the point at which the amount of change in the viscosity becomes equal to or less than a predetermined amount, a first maintenance operation is performed as the maintenance operation, and then the next printing operation is performed; If the first elapsed period is longer than the period from the starting point to the point at which the viscosity of the ink in the nozzle changes from increasing to decreasing and is shorter than the first predetermined period, a program is provided which performs a second maintenance operation as the maintenance operation, which can discharge an amount of ink that exceeds the amount of ink discharged in the first maintenance operation, and then performs the next printing operation.

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