Liquid discharge device, control method therefor, and program

Abstract

The present invention maintains good discharge performance while reducing deterioration of a wiper for wiping a nozzle surface. This printing device includes: a head having a nozzle surface; a wiper that wipes the nozzle surface; and a control unit. The nozzle surface has nozzles for discharging ink. The control unit can execute wiping determination processing that does not execute wiping by the wiper when first cumulative discharge amounts H1, C1 of ink discharged from the nozzles are equal to or greater than threshold values K1, K2, and that executes wiping by the wiper when the first cumulative discharge amounts H1, C1 are less than the threshold values K1, K2.

Description

Liquid ejecting apparatus, control method therefor, and program

[0001] The present disclosure relates to a liquid ejecting apparatus that ejects liquid from a nozzle, a control method therefor, and a program.

[0002] As an example of a liquid ejecting apparatus that ejects liquid from a nozzle, Patent Document 1 describes a recording apparatus that records an image on a recording medium by ejecting ink from ejection ports. This recording apparatus includes a wiping member that wipes off ink adhering to an ejection port surface having ejection ports. Further, in order to maintain favorable ink ejection performance from the ejection ports, the recording apparatus executes a wiping operation of wiping the ejection port surface with the wiping member after a predetermined number of recording operations are completed.

[0003] Japanese Patent Application Laid-Open No. 2024-086355

[0004] In the recording apparatus described in Patent Document 1, if the cumulative amount of ink ejected from the ejection ports is large when a predetermined number of recording operations are performed, a relatively large amount of ink adheres to the ejection port surface due to ink mist. For this reason, the ink adhering to the ejection port surface is less likely to dry and solidify, so the necessity of executing the wiping operation is low. However, in the recording apparatus described in Patent Document 1, the wiping operation is executed even after a predetermined number of recording operations, that is, even in a state where the ink adhering to the ejection port surface is difficult to dry. As a result, the number of times the wiping operation is executed increases, and the wiping member is prone to deterioration.

[0005] Accordingly, an object of the present disclosure is to provide a liquid ejecting apparatus, a control method therefor, and a program capable of maintaining favorable ejection performance while reducing deterioration of a wiper that wipes a nozzle surface.

[0006] The liquid ejecting apparatus of the present disclosure includes: a nozzle surface having nozzles that eject liquid; a wiper that wipes the nozzle surface; and a control unit. The control unit is capable of executing a wipe determination process in which wiping by the wiper is not executed when a first cumulative ejection amount of liquid ejected from the nozzles is equal to or greater than a threshold, and wiping by the wiper is executed when the first cumulative ejection amount is less than the threshold.

[0007] The control method of the present disclosure is a control method for a liquid dispensing device comprising a nozzle surface having a nozzle for dispensing liquid and a wiper for wiping the nozzle surface, wherein a wipe determination process can be performed in which wiping by the wiper is not performed when a first cumulative amount of liquid discharged from the nozzle is equal to or greater than a threshold, and wiping by the wiper is performed when it is less than the threshold.

[0008] The program of this disclosure provides a control unit used in a liquid dispensing device comprising a nozzle surface having a nozzle for dispensing liquid and a wiper for wiping the nozzle surface, which functions as a wipe determination means, which does not perform wiping with the wiper when the first cumulative amount of liquid discharged from the nozzle is equal to or greater than a threshold, and performs wiping with the wiper when it is less than the threshold.

[0009] In the liquid dispensing device and control method of this disclosure, when the first cumulative dispensing amount is above a threshold, a large amount of liquid adheres to the nozzle surface, and the liquid adhered to the nozzle surface does not dry easily. On the other hand, when the first cumulative dispensing amount is below a threshold, a small amount of liquid adheres to the nozzle surface, and the liquid adhered to the nozzle surface dries easily. In this configuration, wiping by the wiper is performed when the liquid adhered to the nozzle surface dries easily, and wiping by the wiper is not performed when the liquid adhered to the nozzle surface does not dry easily. By determining the execution of wiping according to the drying state of the liquid adhered to the nozzle surface in this way, it is possible to maintain good dispensing performance while reducing the deterioration of the wiper. In the program of this disclosure, by making the control unit used in the liquid dispensing device function as a wipe determination means, wiping by the wiper is performed when the liquid adhered to the nozzle surface dries easily, and wiping by the wiper is not performed when the liquid adhered to the nozzle surface does not dry easily. By determining the execution of wiping according to the drying state of the liquid adhered to the nozzle surface in this way, it is possible to maintain good dispensing performance while reducing the deterioration of the wiper.

[0010] This is a schematic perspective view of a printing apparatus according to an embodiment of the present disclosure. This is a plan view showing the internal structure of the printing apparatus shown in Figure 1. This is a front view of the printing apparatus shown in Figure 1. This is a cross-sectional view of the head shown in Figure 2. This is a schematic plan view of the head unit shown in Figure 2 when viewed from below. This is a schematic diagram showing the configuration of a part of the maintenance unit shown in Figure 2. This is a plan view showing the configuration of another part of the maintenance unit shown in Figure 2. This is a cross-sectional view along the line VIII-VIII shown in Figure 7. This is a block diagram showing the electrical configuration of the printing apparatus shown in Figure 1. This is a control flow diagram of the printing apparatus shown in Figure 1 during printing. This is a control flow diagram of the printing process shown in Figure 10. This is a cross-sectional view of a key part showing the situation when the nozzle surface of the head is wiped.

[0011] <Embodiment> A printing apparatus 1 according to one embodiment of the present disclosure will be described with reference to the drawings. In the following description, the vertical and horizontal directions are defined based on the state in which the printing apparatus 1 is installed for use, as shown in Figure 1. The left and right directions are defined when viewing the printing apparatus 1 from the front, based on the state in which the printing apparatus 1 is installed for use. In the following description, the left and right directions may also be referred to as the main scanning direction, and the front and rear directions as the sub-scanning direction. In this embodiment, the printing apparatus 1 corresponds to the "liquid dispensing apparatus" of the present disclosure.

[0012] The printing device 1 shown in Figure 1 is an inkjet printer that prints by ejecting ink onto a printing medium. The printing device 1 uses seven colors of ink—white, black, yellow, cyan, magenta, green, and orange—to print a color image onto the printing medium. The printing medium is not particularly limited as long as it is capable of ejecting ink to form an image; for example, it could be fabric, paper, etc.

[0013] Hereinafter, the white ink among the seven inks will be referred to as "white ink." The six inks excluding the white ink will be referred to collectively as "color inks" when neither is specified. The six inks are black, cyan, yellow, magenta, green, and orange. The color inks in this embodiment dry more slowly than the white ink. When referring to both the white ink and the color inks collectively, or when neither is specified, they will simply be referred to as "ink." The white ink is used in printing to represent the white areas of an image or as a base for the color inks. The color inks are ejected onto the white ink base and used to print color images.

[0014] The external configuration of the printing apparatus 1 will be described with reference to Figures 1 to 3. As shown in Figure 1, the printing apparatus 1 includes a housing 8, a platen 12, a transport mechanism 14, an operating unit 15, and a touch panel 16. Furthermore, the printing apparatus 1 includes an ejector 40 and a maintenance unit 50 as shown in Figure 2, and a control unit 80 as shown in Figure 9.

[0015] As shown in Figure 1, the housing 8 has a substantially rectangular parallelepiped shape. As shown in Figures 2 and 3, the housing 8 has a frame 2 and a cover 3. The frame 2 is constructed in a grid pattern by a plurality of shafts extending in the front-to-back, left-to-right, or up-to-down directions. The cover 3 is made up of a plurality of plate-like members fixed to the frame 2 so as to cover the outer circumference of the frame 2. The cover 3 of the housing 8 has a platen opening 13 approximately in the center of the front surface in the left-to-right and up-to-down directions. As shown in Figures 1 and 2, the platen 12 is made up of a plate-like member having a substantially rectangular planar shape. The upper surface of the platen 12 is a support surface 12A that supports the printing medium. The support surface 12A has a square shape.

[0016] Furthermore, the housing 8 has a discharger cover 8A. The discharger cover 8A is located in the front part of the cover 3 and above the platen opening 13. The discharger cover 8A has a roughly rectangular parallelepiped shape with an open bottom and covers the discharger 40. The discharger 40 is connected to the processing liquid tank via piping and discharges the processing liquid downward under the control of the control unit 80.

[0017] As shown in Figures 1 and 2, the housing 8 contains seven ink tanks 10, each storing seven colors of ink. The seven ink tanks 10, from rear to front, contain white, magenta, cyan, yellow, black, green, and orange inks. The housing 8 also contains a cleaning solution tank 11 for storing cleaning solution. The cleaning solution tank 11 is located in front of the seven ink tanks 10 and is positioned alongside them in the front-to-back direction.

[0018] As shown in Figure 1, the two operating units 15 are located in front of the platen opening 13. Furthermore, the two operating units 15 are positioned to sandwich the platen support 37 (described later) from the left and right. Each operating unit 15 outputs information to the control unit 80 in response to the operator's operation. By operating the operating units 15, the operator inputs a print command to the control unit 80 to start printing by the printing device 1. The print command includes print data. The print data includes image data of the image to be formed on the printing medium.

[0019] The touch panel 16 is located on the upper right side of the front surface of the cover 3, above the platen opening 13. The touch panel 16 can input and display various types of information.

[0020] The transport mechanism 14 transports the platen 12 on which the printing medium is placed, through the platen opening 13, between the inside and outside of the housing 8. When the platen 12 is placed in the printing transport area P3, shown by the dashed line in Figure 2, inside the housing 8, ink is ejected from the head 30 (described later) and printing is performed. When the platen 12 is placed in the processing liquid ejection area P4, shown in Figure 2, processing liquid is ejected from the ejector 40 and applied to the printing medium. The processing liquid ejected from the ejector 40 is, for example, a pre-treatment liquid that forms a base coat before printing.

[0021] As shown in Figures 2 and 3, the conveying mechanism 14 includes a support base 36, a platen support section 37, two rails 38, and a transmission member 39. The platen support section 37 includes a tray 37A and a support section 37B. The platen support section 37 is positioned above the support base 36.

[0022] As shown in Figure 3, the support portion 37B extends vertically and supports the platen 12 from below. The lower end of the support portion 37B is fixed to the tray 37A, connecting the tray 37A and the platen 12.

[0023] As shown in Figure 2, the two rails 38 are spaced apart from each other in the left-right direction. Each rail 38 extends in the front-rear direction and supports the platen support 37 so that it can move in the front-rear direction. The two rails 38 are positioned on a support base 36. The support base 36 also extends in the front-rear direction. The support base 36 and the two rails 38 extend from the rear to the front of the housing 8 and protrude outside the housing 8.

[0024] The transport mechanism 14 has a sub-scanning motor 14M as shown in Figure 9. The sub-scanning motor 14M is connected to the platen support 37 via a transmission member 39. The transmission member 39 moves the platen support 37 in the forward and backward direction, i.e., in the sub-scanning direction, in response to the drive of the sub-scanning motor 14M.

[0025] The operator places the printing medium on the support surface 12A of the platen 12 when the platen 12 is positioned in front of the front of the housing 8, that is, outside the housing 8. The position of the platen 12 shown in Figure 2 is the set position P1 where the platen 12 supports the printing medium. The processing liquid discharge area P4 described above is located in the middle of the transport path of the platen 12 and is the area where the processing liquid is discharged from the discharger 40, and is located below the discharger 40. In addition, before printing on the printing medium, the platen 12 moves from the set position P1 to the pre-printing standby position P2 shown by the dashed line in Figure 2. The pre-printing standby position P2 is behind the processing liquid discharge area P4 and the printing transport area P3, and is at the rear end of the transport path of the platen 12. The printing transport area P3 is the area in the transport path of the platen 12 that overlaps vertically with the movement path of the head 30 in the main scanning direction, which will be described later. The movement path of the head 30 in the main scanning direction is the path between the rear end of the rear head 30, which is the white head 31 described later, and the front end of the front head 30, which is the color head 32 described later.

[0026] The internal structure of the printing apparatus 1 will now be described. As shown in Figure 2, the printing apparatus 1 includes a head unit 100 and a moving mechanism 7 inside the housing 8. The moving mechanism 7 includes a guide shaft 20 and a carriage 6 fixed to the frame 2. As shown in Figure 2, the guide shaft 20 is composed of a front shaft 21, a rear shaft 22, a left shaft 23, and a right shaft 24.

[0027] As shown in Figure 2, the front shaft 21 is positioned at the front end of the frame 2 and extends horizontally from the left end to the right end of the frame 2. The rear shaft 22 is positioned approximately in the center of the frame 2 in the front-to-back direction and extends horizontally from the left end to the right end of the frame 2. The left shaft 23 is positioned at the left end of the frame 2 and extends horizontally from the left end of the front shaft 21 to the left end of the rear shaft 22. The right shaft 24 is positioned at the right end of the frame 2 and extends horizontally from the right end of the front shaft 21 to the right end of the rear shaft 22. The conveying mechanism 14 is fixed to the frame 2.

[0028] As shown in Figure 2, the carriage 6 is supported on the front shaft 21 and the rear shaft 22 so as to be movable in the main scanning direction. The carriage 6 is plate-shaped and extends in the front, rear, left, and right directions. The carriage 6 extends from the front shaft 21 to the rear shaft 22. As shown in Figure 2, the carriage 6 supports the white head 31 and the color head 32. The white head 31 and the color head 32 constitute one head unit 100. The head unit 100 in this embodiment corresponds to the "liquid discharge head" of this disclosure.

[0029] The white head 31 and the color head 32 each have the same structure and, in this embodiment, are rectangular parallelepipeds. Hereinafter, when the white head 31 and the color head 32 are referred to collectively, or when neither is specified, they will be referred to as "head 30".

[0030] As shown in Figure 4, the head 30 includes a flow path unit 33 and an actuator unit 34. Multiple nozzles N are formed on the nozzle surface 30A, which is the lower surface of the flow path unit 33. The nozzle surface 30A is a surface that extends in the front-rear direction and the left-right direction. A liquid-repellent film may be formed on the nozzle surface 30A. Inside the flow path unit 33, a common flow path 33A that communicates with the ink tank 10 and individual flow paths 33B, each for each nozzle N, are formed. The individual flow paths 33B are flow paths that go from the outlet of the common flow path 33A through the pressure chamber 33P to the nozzle N. Multiple pressure chambers 33P are open on the upper surface of the flow path unit 33.

[0031] The actuator unit 34 includes a metal diaphragm 34A, a piezoelectric layer 34B, and a plurality of individual electrodes 34C. The diaphragm 34A is positioned on the upper surface of the flow channel unit 33 so as to cover a plurality of pressure chambers 33P. The piezoelectric layer 34B is positioned on the upper surface of the diaphragm 34A. The plurality of individual electrodes 34C are positioned on the upper surface of the piezoelectric layer 34B and face the plurality of pressure chambers 33P.

[0032] The diaphragm 34A and the multiple individual electrodes 34C are electrically connected to the driver IC 35. The driver IC 35 maintains the potential of the diaphragm 34A at ground potential, while changing the potential of the individual electrodes 34C between ground potential and drive potential. Specifically, the driver IC 35 generates a drive signal based on a control signal from the control unit 80 and supplies the generated drive signal to the individual electrodes 34C. As a result, the potential of the individual electrodes 34C changes between drive potential and ground potential. At this time, the portion of the diaphragm 34A and piezoelectric layer 34B sandwiched between the individual electrodes 34C and the pressure chamber 33P deforms, causing the volume of the pressure chamber 33P to change. This sandwiched portion functions as an actuator 34X, applying pressure to the ink in the pressure chamber 33P, and causing ink to be ejected from the nozzle N. An actuator 34X is provided for each individual electrode 34C, i.e., for each nozzle N, and can be independently deformed according to the potential supplied to the individual electrode 34C.

[0033] As shown in Figures 2 and 5, the white print head 31 is located at the rear of the carriage 6. The white print head 31 is connected to an ink tank 10 that stores white ink via piping, and white ink is supplied from the ink tank 10.

[0034] As shown in Figures 2 and 5, the color head 32 is located in front of the white head 31. The color head 32 is connected to six ink tanks 10 that store color ink via piping, and color ink is supplied from these ink tanks 10.

[0035] The multiple nozzles N of the color head 32 are arranged so that there are six rows of nozzles extending in the front-to-back direction, arranged in the left-to-right direction. Each of the six rows of nozzles on the color head 32 corresponds to a different color of ink. In other words, the color head 32 ejects color ink of the color corresponding to each nozzle row downwards from the multiple nozzles N.

[0036] In this embodiment, the multiple nozzles N of the white head 31 are also arranged so that the nozzle rows extending in the front-to-back direction are arranged in six rows in the left-to-right direction. However, the white head 31 may have only one row of nozzles. In other words, the configurations of the white head 31 and the color head 32 may be different from each other. The white head 31 ejects white ink downward from the multiple nozzles N. The multiple nozzles N of the white head 31 correspond to the "first nozzles" of this disclosure, and the nozzle surface 30A of the white head 31 corresponds to the "first nozzle surface" of this disclosure. The multiple nozzles N of the color head 32 correspond to the "second nozzles" of this disclosure, and the nozzle surface 30A of the color head 32 corresponds to the "second nozzle surface" of this disclosure.

[0037] Alternatively, the color head 32 may have four nozzle rows, and magenta, cyan, yellow, and black inks may be ejected from the four nozzle rows of the color head 32. In this case, green and orange inks do not need to be ejected from the color head 32. Also, an ink tank 10 for storing green and orange inks does not need to be provided.

[0038] As shown in Figure 2, the moving mechanism 7 includes a drive belt 7A and a main scanning motor 7M. The drive belt 7A is connected to the rear end of the carriage 6. The drive belt 7A is mounted on the rear shaft 22 and extends in the left-right direction. The left end of the drive belt 7A is connected to the main scanning motor 7M. When the main scanning motor 7M is driven, the drive belt 7A moves the carriage 6 in the left-right direction along the front shaft 21 and the rear shaft 22. In other words, the moving mechanism 7 moves the head unit 100 in the main scanning direction. Figure 2 shows the state where the carriage 6 is located at the right end of the movement range R.

[0039] The head 30 is positioned primarily in one of the following locations by the movement of the carriage 6: cap position B1, discharge area B2, and head standby position B3. Cap position B1 is the position of the head 30 when the carriage 6 is located at the left end of the movement range R. Cap position B1 is the position when the nozzle surface 30A of the head 30 is covered by the cap 51, which will be described later.

[0040] The ejection area B2 is located between the cap position B1 and the head standby position B3 in the main scanning direction. Furthermore, the ejection area B2 is the area in the movement path of the head 30 that overlaps vertically with the print transport area P3, which is the transport path of the platen 12. During printing on the printing medium, as the carriage 6 moves, the head 30 ejects ink from the nozzle N based on the image data as it passes through the ejection area B2. This allows printing to be performed on the printing medium on the platen 12. The head standby position B3 is the position of the head 30 when the carriage 6 is at the right end of the movement range R. The head standby position B3 is the position where the head 30 is positioned when an operator performs tasks such as cleaning the head 30.

[0041] The printing apparatus 1 moves the platen 12 in the sub-scanning direction in the printing transport area P3. The printing apparatus 1 moves the carriage 6 in the main scanning direction in the ejection area B2. As a result, the printing medium moves relative to the head 30 in both the sub-scanning direction and the main scanning direction.

[0042] The operation of moving the head unit 100 in the main scanning direction and ejecting ink onto a print medium when the head 30 faces the print medium is referred to as "ejection scanning". The printing apparatus 1 performs printing on a print medium by repeating ejection scanning and movement of the platen 12 in the sub-scanning direction. For example, in ejection scanning, the printing apparatus 1 ejects white ink from the white head 31 to form an underlayer for color ink on the print medium. In ejection scanning, the printing apparatus 1 ejects color ink from the color head 32 onto the underlayer formed on the print medium to print a color image.

[0043] Further, as shown in FIG. 1, the housing 8 has a protruding portion 8B protruding forward. The protruding portion 8B is a front portion of the cover 3 and is disposed below the platen opening 13. As shown in FIG. 3, the protruding portion 8B has a door 8B1 on a front surface thereof. With the door 8B1 opened, the processing liquid tank that stores processing liquid is exposed.

[0044] Next, the maintenance unit 50 will be described. As shown in FIGS. 2 and 6 to 8, the maintenance unit 50 includes two caps 51, a cleaning liquid tank 52, two wipers 53, a wiper moving mechanism 54, a suction pump 55, and a waste liquid tank 56.

[0045] As shown in FIG. 2, the two caps 51 are individually provided for the two heads 30. The two caps 51 are located below the two heads 30. The two caps 51 vertically overlap the two heads 30 located at the cap position B1. The two caps 51 can be lifted and lowered by a lifting mechanism.

[0046] The lifting mechanism comes into contact with the carriage 6 immediately before the head unit 100 reaches the cap position B1. Thereafter, the lifting mechanism lifts the two caps 51 by utilizing the force pressed by the carriage 6 which moves leftward until the head unit 100 reaches the cap position B1. Then, when the head unit 100 reaches the cap position B1, as shown in FIG. 6, the nozzle surface 30A of each head 30 comes into contact with and is covered by the corresponding cap 51. FIG. 6 shows one cap 51 corresponding to one head 30.

[0047] When the carriage 6 is moved rightward from a state where the nozzle surface 30A of each head 30 is covered by the corresponding cap 51, the lifting mechanism lowers the cap 51. In this way, the cap 51 is separated from the nozzle surface 30A, resulting in an uncapped state where the nozzle surface 30A is not covered. Note that the lifting mechanism may be connected to a motor and operate by driving of the motor to lift and lower the cap 51.

[0048] As shown in FIG. 2, the cleaning liquid tank 52 is located between the cap position B1 and the ejection region B2 in the main scanning direction. When the head unit 100 is moved rightward from the cap position B1 by the movement of the carriage 6, the head 30 passes above the cleaning liquid tank 52.

[0049] As shown in FIG. 7 and FIG. 8, the cleaning liquid tank 52 includes a housing 52A and a lid 52B. The housing 52A is a substantially rectangular parallelepiped member that is open at the upper end and extends in the front-rear direction. As shown in FIG. 7, the housing 52A has two cleaning liquid chambers 52C and 52D inside. The two cleaning liquid chambers 52C and 52D are arranged in the front-rear direction and partitioned by a wall portion 52G extending in the left-right direction and the vertical direction.

[0050] The cleaning liquid chamber 52C is arranged rearward of the cleaning liquid chamber 52D, and corresponds to the wiper 53 corresponding to the white head 31. The wiper 53 corresponding to the white head 31 wipes the nozzle surface 30A of the white head 31, and corresponds to "the first wiper" in the present disclosure. The cleaning liquid chamber 52D corresponds to the wiper 53 corresponding to the color head 32. The wiper 53 corresponding to the color head 32 wipes the nozzle surface 30A of the color head 32, and corresponds to "the second wiper" in the present disclosure. Cleaning liquid is stored in the two cleaning liquid chambers 52C and 52D. The two cleaning liquid chambers 52C and 52D are connected to the cleaning liquid tank 11 via a pipe.

[0051] The lid 52B has two openings 52E and two openings 52F. The two openings 52E are arranged corresponding to the two wipers 53. Each opening 52E is provided so that the wiper 53 can move in and out. Among the two openings 52E, the rear opening 52E faces the cleaning liquid chamber 52C, and the front opening 52E faces the cleaning liquid chamber 52D.

[0052] The two openings 52F are arranged side by side in the front-to-back direction. Each opening 52F overlaps with opening 52E in the left-to-right direction. Of the two openings 52F, the rear opening 52F is large enough for ink ejected from the white head 31 to pass through and faces the cleaning fluid chamber 52C. The front opening 52F is large enough for ink ejected from the color head 32 to pass through and faces the cleaning fluid chamber 52D.

[0053] As shown in Figure 7, the lid 52B is provided with two ink receiving plates 59. As shown in Figure 8, each ink receiving plate 59 is positioned to cover the opening 52F from below. Each ink receiving plate 59 has a plurality of through holes 59A. After receiving the ink ejected from the head 30, the ink receiving plates 59 allow the ink to flow through the through holes 59A to the cleaning fluid chambers 52C and 52D. In this embodiment, the ink receiving plates 59 correspond to the "receiving members" of this disclosure.

[0054] As shown in Figures 7 and 8, the two wipers 53 are plate-shaped members extending in the front-rear direction and are arranged to correspond to the two heads 30. Of the two wipers 53, the rear wiper 53 corresponds to the white head 31. The rear wiper 53 is positioned to enter and exit the cleaning fluid chamber 52C through the rear opening 52E of the two openings 52E.

[0055] Of the two wipers 53, the front wiper 53 corresponds to the color head 32. The front wiper 53 is positioned to enter and exit the cleaning fluid chamber 52D through the front opening 52E of the two openings 52E.

[0056] Each wiper 53 is made of an elastically deformable elastic member. In this embodiment, each wiper 53 is made of urethane foam, but it may be made of an elastic material such as rubber.

[0057] The wiper moving mechanism 54 has two wiper support sections 54A and two wiper motors 54M. One wiper support section 54A supports one wiper 53. Figure 8 shows one wiper support section 54A, but the wiper moving mechanism 54 has two wiper support sections 54A that support two wipers 53.

[0058] Of the two wiper support sections 54A, the wiper support section 54A that supports the wiper 53 corresponding to the white head 31 is located within the cleaning fluid chamber 52C. The wiper support section 54A that supports the wiper 53 corresponding to the color head 32 is located within the cleaning fluid chamber 52D. As shown in Figure 8, the two wiper support sections 54A are positioned above the cleaning fluid surface.

[0059] Each wiper support section 54A extends in the front-rear direction. As shown in Figure 8, each wiper support section 54A is rotatably supported on the housing 52A around a rotation axis 54X. The wiper moving mechanism 54 has two transmission mechanisms. Each transmission mechanism transmits the driving force of the wiper motor 54M to the corresponding wiper support section 54A, thereby rotating the wiper support section 54A.

[0060] There may be only one wiper motor 54M. In this case, the transmission mechanism may be configured to selectively transmit the driving force of the wiper motor 54M to one of the two wiper support parts 54A.

[0061] The wiper movement mechanism 54 selectively positions the wiper 53 between a wiping position and a contact position by driving the wiper motor 54M. The contact position is the position of the wiper 53 shown by the dashed line in Figure 8, where the wiper 53 comes into contact with the cleaning fluid in the cleaning fluid chambers 52C and 52D. The contact position is the position where the wiper 53 is positioned to extend vertically downward from the wiper support part 54A. The cleaning fluid adheres to the wiper 53 when it is in the contact position.

[0062] The wipe position is the position of the wiper 53 shown by the solid line in Figure 8, where the wiper 53 is positioned above the cleaning fluid in the cleaning fluid chambers 52C and 52D. The wipe position is where the wiper 53 is positioned to extend vertically upward from the wiper support part 54A. Furthermore, the wipe position is where the tip of the wiper 53 is positioned above the nozzle surface 30A of the head 30. Cleaning fluid adheres to the wiper 53 when it has been displaced from the contact position to the wipe position. Therefore, when the wiper 53 wipes the nozzle surface 30A, the ink adhering to the nozzle surface 30A can be effectively removed.

[0063] The suction pump 55 is connected to two caps 51 and piping 55A as shown in Figure 2. Although only one cap 51 is shown in Figure 6, the suction pump 55 is connected to both caps 51. The suction pump 55 is also connected to the waste liquid tank 56 via piping 55A.

[0064] When the cap 51 covers the nozzle surface 30A of the head 30, the suction pump 55 is driven by the control unit 80. At this time, the sealed space between the cap 51 and the head 30 is depressurized, and purging is performed, in which ink is forcibly discharged from the nozzle N. The purged ink is received by the cap 51 and flows to the waste liquid tank 56.

[0065] The purging process is performed when the user operates the touch panel 16 and inputs a purge command. Purging is also performed when a predetermined number of print media have been printed, or when a predetermined period of time has elapsed.

[0066] Referring to Figure 9, the electrical configuration of the printing device 1 will be explained. The control unit 80 is equipped with a CPU 81, ROM 82, RAM 83, and flash memory 84. The CPU 81 controls the printing device 1 and is electrically connected to the ROM 82, RAM 83, and flash memory 84. The ROM 82 stores control programs for the CPU 81 to control the operation of the printing device 1, and information necessary for the CPU 81 when executing various programs. The ROM 82 stores each position of the carriage 6 based on the rotation angle of the main scanning motor 7M and each position of the platen 12 based on the rotation angle of the sub-scanning motor 14M. The RAM 83 temporarily stores various data such as flashing data used in the control program.

[0067] The flash memory 84 is non-volatile and stores the print data, the first cumulative ejection amount H1 of white ink from the white head 31, and the second cumulative ejection amount H2 of white ink. The flash memory 84 also stores the first cumulative ejection amount C1 of color ink from the color head 32 and the second cumulative ejection amount C2 of color ink.

[0068] The first cumulative ejection amount H1 and the second cumulative ejection amount H2 of white ink are cumulative values ​​that are updated each time an ejection scan is performed, representing the amount of ink ejected from the white head 31. In a single ejection scan, the head unit 100 ejects ink onto the printing medium while moving in one or the other direction of the main scanning direction. In other words, an ejection scan is defined as the operation in which ink is ejected from one or both heads 30 while the head unit 100 moves to the right or left. One of the main scanning directions corresponds to "one direction" in this disclosure. The other of the main scanning directions also corresponds to "one direction" in this disclosure.

[0069] The amount of ink ejected from the white head 31 in one ejection scan is derived by the control unit 80 based on the image data included in the print data. The first cumulative ejection amount H1 is the cumulative amount of white ink ejected during a predetermined number of ejection scans MA during printing. The second cumulative ejection amount H2 is the cumulative amount of white ink ejected from the nozzle surface 30A of the white head 31 from one wipe to the next wipe. In this embodiment, the first cumulative ejection amount H1 corresponds to the "first liquid cumulative ejection amount" in this disclosure.

[0070] The first cumulative ejection amount C1 and the second cumulative ejection amount C2 of the color ink are cumulative values ​​that are updated each time an ejection scan is performed, representing the amount of ink ejected from the color head 32. The amount of ink ejected from the color head 32 in one ejection scan is derived by the control unit 80 based on image data. The first cumulative ejection amount C1 is the cumulative ejection amount of color ink during a predetermined number of ejection scans MA during printing. The second cumulative ejection amount C2 is the cumulative ejection amount of color ink from the time the nozzle surface 30A of the color head 32 is wiped until it is wiped again. In this embodiment, the first cumulative ejection amount C1 corresponds to the "second liquid cumulative ejection amount" in this disclosure.

[0071] As shown in Figure 9, the control unit 80 is electrically connected to the main scanning motor 7M, the sub-scanning motor 14M, six wiper motors 54M, two driver ICs 35, the operation unit 15, the touch panel 16, the suction pump 55, and the temperature sensor 57. The main scanning motor 7M, the sub-scanning motor 14M, the two wiper motors 54M, the two driver ICs 35, and the suction pump 55 are driven by the control unit 80.

[0072] The temperature sensor 57 is located inside the housing 8 and detects the ambient temperature of the nozzle surface 30A of the head unit 100. The temperature sensor 57 outputs the detected temperature to the control unit 80.

[0073] The flash memory 84 stores a first threshold, a first upper threshold, a second threshold, a second upper threshold, a first upper limit value U1, and a second upper limit value U2. The first threshold and the first upper threshold are thresholds corresponding to the first cumulative ejection amount of white ink. The first threshold is set when the temperature detected by the temperature sensor 57 is below a predetermined temperature. The first threshold is set to an ink amount that prevents the white ink adhering to the nozzle surface 30A from drying out easily, even when the ambient temperature around the nozzle surface 30A is at a predetermined temperature.

[0074] The first upper threshold is a threshold set when the temperature detected by the temperature sensor 57 exceeds a predetermined temperature. The first upper threshold is a higher value than the first threshold, and is set to an ink amount that prevents the white ink adhering to the nozzle surface 30A from drying out even when the ambient temperature around the nozzle surface 30A exceeds a predetermined temperature.

[0075] In this embodiment, the first threshold corresponds to the "first set value" in this disclosure, and the first upper threshold corresponds to the "second set value" in this disclosure. Furthermore, the first threshold and the first upper threshold also correspond to the "first threshold" and "threshold" in this disclosure.

[0076] The second threshold and the second upper threshold are thresholds corresponding to the first cumulative ejection amount of color ink. The second threshold is set when the temperature detected by the temperature sensor 57 is below a predetermined temperature. The second threshold is smaller than the first threshold and is set to an ink amount that prevents the color ink adhering to the nozzle surface 30A from drying out, even when the ambient temperature around the nozzle surface 30A is at a predetermined temperature.

[0077] The second upper threshold is set when the temperature detected by the temperature sensor 57 exceeds a predetermined temperature. The second upper threshold is a higher value than the second threshold, and is set to an ink amount that prevents the color ink adhering to the nozzle surface 30A from drying out even when the ambient temperature around the nozzle surface 30A exceeds a predetermined temperature.

[0078] In this embodiment, the second threshold corresponds to the "first set value" in this disclosure, and the first upper threshold corresponds to the "second set value" in this disclosure. Furthermore, the second threshold and the second upper threshold also correspond to the "second threshold" and "threshold" in this disclosure.

[0079] The first upper limit value U1 is a threshold corresponding to the second cumulative discharge amount H2 of white ink. The second upper limit value U2 is a threshold corresponding to the second cumulative discharge amount C2 of color ink. In this embodiment, the first upper limit value U1 and the second upper limit value U2 correspond to the "upper limit value" in this disclosure.

[0080] <Control during printing> Referring to Figures 10 and 11, the control by the control unit 80 when printing an image on a printing medium will be explained. The operator operates the operation unit 15 to input a print command to the printing device 1. The control unit 80 then reads the control program from the ROM 82 and operates, executing the flow shown in Figure 10. The flow shown in Figure 10 will be explained below.

[0081] The control unit 80 first determines whether or not a print command has been input (S1). Before the operator operates the operation unit 15 to input a print command, the operator places the printing medium, which has not been coated with processing liquid, on the support surface 12A of the platen 12. The platen 12 is positioned at the set position P1 when not printing. In this embodiment, a T-shirt is used as the printing medium. When not printing, the printing device 1 normally has the head unit 100 positioned at the cap position B1, and the nozzle surface 30A of the head 30 is covered by the cap 51.

[0082] If no print command is entered (S1: NO), S1 is repeated until a print command is entered. On the other hand, when a print command is entered (S1: YES), the control unit 80 executes the processing liquid coating process (S2).

[0083] In the coating process of S2, the control unit 80 first controls the sub-scanning motor 14M to start transporting the platen 12 from the set position P1 toward the processing liquid discharge area P4. Next, the control unit 80 controls the discharger 40 to discharge the processing liquid from the discharger 40. As a result, the processing liquid is applied to the printing medium passing through the processing liquid discharge area P4, and a base coat with the processing liquid applied is formed on the printing medium.

[0084] Next, the control unit 80 controls the ejector 40 to stop the ejection of the processing liquid from the ejector 40 when the platen 12 has passed through the processing liquid ejection area P4. The control unit 80 also controls the sub-scanning motor 14M to stop platen transport when the platen 12 reaches the pre-printing standby position P2. Then, the control unit 80 controls the sub-scanning motor 14M to move the platen 12 from the pre-printing standby position P2 to the printing transport area P3 and stop it at a predetermined position. This predetermined position is the position for ejecting ink onto the printing medium by the initial ejection scan performed during printing.

[0085] Next, the control unit 80 executes the printing process (S3). The printing process follows the flow shown in Figure 11. First, the control unit 80 executes a setting process (S31). In the setting process, the control unit 80 sets a first setting threshold K1 and a second setting threshold K2 as thresholds based on the temperature detected by the temperature sensor 57. The first setting threshold K1 is the threshold corresponding to the first cumulative ejection amount H1 of white ink. The second setting threshold K2 is the threshold corresponding to the first cumulative ejection amount C1 of color ink.

[0086] More specifically, when the temperature detected by the temperature sensor 57 is below a predetermined temperature, the control unit 80 sets a first threshold as the first setting threshold K1 and a second threshold as the second setting threshold K2. On the other hand, when the temperature detected by the temperature sensor 57 exceeds a predetermined temperature, the control unit 80 sets a first upper threshold as the first setting threshold K1 and a second upper threshold as the second setting threshold K2.

[0087] Next, the control unit 80 performs a scanning process (S32). At this time, the control unit 80 controls the driver IC 35 and the main scanning motor 7M based on the print data and performs one ejection scan.

[0088] The printing medium is transported from back to front during printing. The white head 31 is located at the rear, and the color head 32 is located in front of the white head 31. As a result, during a single ejection scan, the printing medium and the white head 31 may face each other in the vertical direction, while the printing medium and the color head 32 may not face each other in the vertical direction. In this case, the movement in the main scanning direction during a single ejection scan may cause ink to be ejected from the nozzles N of the white head 31, but not from the nozzles N of the color head 32, causing the head unit 100 to move to the right or left.

[0089] Furthermore, during a single ejection scan, the printing medium and the two heads 30 may face each other in the vertical direction. In this case, the movement in the main scanning direction during a single ejection scan may cause the head unit 100 to move to the right or left while ejecting ink from the two heads 30.

[0090] Furthermore, during a single ejection scan, the print medium and the white head 31 may not face each other in the vertical direction, while the print medium and the color head 32 may face each other in the vertical direction. In this case, the movement in the main scanning direction during a single ejection scan may cause ink to be ejected from the nozzle N of the white head 31, but not from the nozzle N of the color head 32, and the head unit 100 may move to the right or left.

[0091] When scanning is started with the head unit 100 positioned at the cap position B1, the head unit 100 is moved from the cap position B1 to the discharge area B2. This causes the cap 51 to separate from the nozzle surface 30A of the head 30 and be uncapped.

[0092] When the head unit 100 moves from the cap position B1 to the ejection area B2, each head 30 faces the ink receiving plate 59. The control unit 80 performs flushing when each head 30 faces the ink receiving plate 59. During flushing, the control unit 80 controls the driver IC 35 based on the flushing data and ejects ink from the nozzles N to the ink receiving plate 59 at the timing when the heads 30 face the ink receiving plate 59. The flushing data is data for ejecting several ink droplets from each nozzle N. After this, the head unit 100 reaches the ejection area B2 and ejection scanning is performed.

[0093] Next, the control unit 80 increments the variable M by 1 (S33). The variable M corresponds to the number of movements of the head unit 100 in the main scanning direction during ejection scanning. After this, the control unit 80 determines whether or not printing on the printing medium is complete (S34). The determination of whether or not printing is complete in S34 is made by checking whether the cumulative number of movements of the head unit 100 in the main scanning direction during the current printing process has reached the print completion count. The print completion count is the number of movements of the head unit 100 in the main scanning direction until the current printing is completed. The control unit 80 derives and sets the print completion count based on the print command. The control unit 80 also resets the cumulative number of movements to 0 when the printing process is completed.

[0094] In S34, if printing is not yet complete (S34: NO), the control unit 80 executes a transport process (S35). In the transport process, the control unit 80 controls the sub-scanning motor 14M based on the print data to move the platen 12 forward by a predetermined distance.

[0095] Next, the control unit 80 determines whether the variable M has reached a predetermined number of times MA (S36). In this embodiment, the predetermined number of times MA is 5. As a result, in S36, the process proceeds from S36 to S37 every 5 times the head unit 100 moves in the main scanning direction during ejection scanning. Note that the predetermined number of times MA may be other than 5 and can be set as appropriate.

[0096] In S36, when the variable M reaches a predetermined number of times MA (S36: YES), the control unit 80 determines whether the first cumulative ejection amount H1 is equal to or greater than the first set threshold K1 (S37). When the first cumulative ejection amount H1 is equal to or greater than the first set threshold K1 (S37: YES), a relatively large amount of ink is ejected from the white head 31. In other words, a large amount of ink mist generated during ink ejection adheres to the nozzle surface 30A of the white head 31. As a result, the ink adhering to the nozzle surface 30A of the white head 31 is difficult to dry and does not solidify easily. When the adhering ink is in such a state that it does not dry easily, the control unit 80 proceeds to S38.

[0097] In S38, the control unit 80 determines whether the first cumulative ejection amount C1 is equal to or greater than the second setting threshold K2. When the first cumulative ejection amount C1 is equal to or greater than the second setting threshold K2 (S38: YES), a relatively large amount of ink is ejected from the color head 32. In other words, a large amount of ink mist generated during ink ejection adheres to the nozzle surface 30A of the color head 32. As a result, the ink adhering to the nozzle surface 30A of the color head 32 is difficult to dry and does not solidify easily. When the adhering ink is in such a state that it does not dry easily, the control unit 80 proceeds to S39.

[0098] In S39, the control unit 80 resets the first cumulative discharge amounts H1 and C1 and the variable M to 0.

[0099] Next, the control unit 80 performs a flushing process (S40). During the flushing process, the control unit 80 controls the main scanning motor 7M to bring the head unit 100 facing the ink receiving plate 59. After this, the control unit 80 controls the driver IC 35 based on the flushing data, causing each head 30 to eject ink onto the ink receiving plate 59.

[0100] When the process proceeds from any of the following steps S42-S44, S50, S52, or S55 to S40, a wipe process is performed immediately beforehand. Since the flushing process is performed immediately after the wipe process, the ink that has entered the nozzle N due to the wipe process can be discharged to the outside. Therefore, the ejection performance from the nozzle N can be maintained at a better level.

[0101] The flushing process in S40 is performed after S38, S42-S44, or any of the above. In other words, the flushing process is performed each time the variable M reaches MA a predetermined number of times. When such a flushing process is performed following any of S42-S44, the wipe process and the flushing process are performed consecutively. As a result, the number of movements of the head unit 100 in the main scanning direction is reduced compared to a configuration where the wipe process and the flushing process are performed at different timings and not consecutively. This results in a shorter printing time. The printing time is the time from the start to the end of the printing process in S3.

[0102] In S37, if the first cumulative discharge amount H1 is less than the first set threshold K1 (S37: NO), the control unit 80 proceeds to S41. In S41, the control unit 80 determines whether the first cumulative discharge amount C1 is equal to or greater than the second set threshold K2.

[0103] In S41, if the first cumulative ejection amount C1 is equal to or greater than the second setting threshold K2 (S41: YES), the control unit 80 performs a white head wipe process (S42). When proceeding from S37 to S41, not much ink is ejected from the white head 31, so the amount of ink mist generated is small. Therefore, the amount of ink mist adhering to the nozzle surface 30A of the white head 31 is small. Consequently, the ink adhering to the nozzle surface 30A of the white head 31 is in a state where it dries easily and solidifies easily. When the adhering ink is in such a state where it dries easily, the nozzle surface 30A of the white head 31 is wiped. S37 and S41 in this embodiment correspond to the "wipe determination process" of this disclosure.

[0104] In the white head wiping process in S42, the control unit 80 first controls the main scanning motor 7M to move the head unit 100 from the discharge area B2 to the cap position B1. When the head unit 100 reaches the cap position B1, the control unit 80 controls the wiper motor 54M to move the wiper 53 corresponding to the white head 31 to the wipe position. Normally, the two wipers 53 are positioned in contact with each other. After this, the control unit 80 controls the main scanning motor 7M to move the head unit 100 to the right, allowing it to pass over the wiper 53. As a result, the wiper 53 in the wipe position contacts the nozzle surface 30A of the white head 31 and wipes it. Figure 12 shows the state in which one head 30 is being wiped by the wiper 53. After the head unit 100 has passed over the wiper 53, the control unit 80 controls the wiper motor 54M to move the wiper 53 corresponding to the white head 31 to the contact position.

[0105] In S41, if the first cumulative ejection amount C1 is less than the second setting threshold K2 (S41: NO), the control unit 80 performs a wipe process on both heads (S43). When proceeding from S41 to S43, not much ink is ejected from the color head 32, so the amount of ink mist generated is small. Therefore, the amount of ink mist adhering to the nozzle surface 30A of the color head 32 is small. Consequently, the ink adhering to the nozzle surface 30A of the color head 32 is in a state where it dries easily and solidifies easily. Also, as described above, when proceeding from S37 to S41, the ink adhering to the nozzle surface 30A of the white head 31 is in a state where it dries easily and solidifies easily. When the adhering ink is in such a state where it dries easily, the nozzle surfaces 30A of the two heads 30 are wiped.

[0106] In the double head wipe process in S43, the control unit 80 first controls the main scanning motor 7M to move the head unit 100 from the discharge area B2 to the cap position B1. When the head unit 100 reaches the cap position B1, the control unit 80 controls the two wiper motors 54M to move the two wipers 53 to the wipe position. After this, the control unit 80 controls the main scanning motor 7M to move the head unit 100 to the right, allowing it to pass over the wipers 53. As a result, the two wipers 53 at the wipe position come into contact with the nozzle surfaces 30A of the two heads 30 and wipe. After the head unit 100 has passed over the wipers 53, the control unit 80 controls the two wiper motors 54M to move the two wipers 53 to the contact position.

[0107] In S38, if the first cumulative ejection amount C1 is less than the second setting threshold K2 (S38: NO), the control unit 80 performs a color head wipe process (S44). When proceeding from S38 to S44, not much ink is ejected from the color head 32, so the amount of ink mist generated is also small. As a result, the ink adhering to the nozzle surface 30A of the color head 32 is prone to drying and solidifying. When the adhering ink is in such a state that it is prone to drying, the nozzle surface 30A of the color head 32 is wiped. S38 in this embodiment corresponds to the "wipe determination process" of this disclosure.

[0108] In the color head wipe process in S44, the control unit 80 first controls the main scanning motor 7M to move the head unit 100 from the discharge area B2 to the cap position B1. When the head unit 100 reaches the cap position B1, the control unit 80 controls the wiper motor 54M to move the wiper 53 corresponding to the color head 32 to the wipe position. After this, the control unit 80 controls the main scanning motor 7M to move the head unit 100 to the right, passing over the wiper 53. As a result, the wiper 53 at the wipe position comes into contact with the nozzle surface 30A of the color head 32 and wipes it. After the head unit 100 has passed over the wiper 53, the control unit 80 controls the wiper motor 54M to move the wiper 53 corresponding to the color head 32 to the contact position.

[0109] After S42, the control unit 80 resets the second cumulative discharge amount H2 to 0 (S45). Then, the process proceeds to S39.

[0110] After S43, the control unit 80 resets the second cumulative discharge amounts H2 and C2 to 0 (S46). Then, the process proceeds to S39.

[0111] After S44, the control unit 80 resets the second cumulative discharge amount C2 to 0 (S47). Then, the process proceeds to S39.

[0112] In S36, if the variable M has not reached the predetermined number of times MA (S36: NO), the control unit 80 proceeds to S48. In S48, the control unit 80 determines whether the second cumulative discharge amount H2 is equal to or greater than the first upper limit value U1.

[0113] In S48, if the second cumulative discharge amount H2 is greater than or equal to the first upper limit value U1 (S48: YES), the control unit 80 proceeds to S49. In S49, the control unit 80 determines whether or not the second cumulative discharge amount C2 is greater than or equal to the second upper limit value U2.

[0114] In S49, if the second cumulative ejection amount C2 is less than the second upper limit value U2 (S49: NO), the control unit 80 performs a white head wipe process (S50). When proceeding from S48 to S49, a large amount of ink has been ejected from the white head 31 during the current printing process. As a result, a large amount of ink mist adheres to the nozzle surface 30A of the white head 31. When the amount of ink adhering to the nozzle surface 30A is too large, the adhering ink is more likely to enter the nozzle N. Therefore, when the amount of ink adhering increases significantly, the nozzle surface 30A of the white head 31 is wiped.

[0115] The white head wiping process in S50 performs the same process as the white head wiping process in S42 described above. As a result, the wiper 53 at the wiping position comes into contact with the nozzle surface 30A of the white head 31 and wipes. After the head unit 100 passes the wiper 53, the control unit 80 controls the wiper motor 54M to move the wiper 53 corresponding to the white head 31 to the contact position.

[0116] Next, the control unit 80 resets the second cumulative discharge amount H2 to 0 (S51). Then, the process proceeds to S40.

[0117] In S49, if the second cumulative ejection amount C2 is greater than or equal to the second upper limit value U2 (S49: YES), the control unit 80 performs a wipe operation on both heads (S52). When proceeding from S49 to S52, a large amount of ink has been ejected from the color head 32 during the current printing process. As a result, a large amount of ink mist adheres to the nozzle surface 30A of the color head 32. Also, as described above, when proceeding from S48 to S49, a large amount of ink mist adheres to the nozzle surface 30A of the white head 31. When the amount of ink adhering to the nozzle surface 30A of each head 30 is too large, the adhering ink is likely to enter the nozzle N. For this reason, when the amount of ink adhering increases significantly, the nozzle surfaces 30A of both heads 30 are wiped.

[0118] The double-head wiping process in S52 performs the same process as the double-head wiping process in S43 described above. As a result, the two wipers 53 at the wiping position come into contact with the nozzle surfaces 30A of the two heads 30 and wipe. After the head unit 100 has passed the wipers 53, the control unit 80 controls the two wiper motors 54M to move the two wipers 53 to the contact position.

[0119] Next, the control unit 80 resets the second cumulative discharge amounts H2 and C2 to 0 (S53). Then, the process proceeds to S40.

[0120] In S48, if the second cumulative discharge amount H2 is less than the first upper limit value U1 (S48: NO), the control unit 80 proceeds to S54. In S54, the control unit 80 determines whether the second cumulative discharge amount C2 is equal to or greater than the second upper limit value U2.

[0121] In S54, if the second cumulative ejection amount C2 is greater than or equal to the second upper limit value U2 (S54: YES), the control unit 80 performs a color head wipe process (S55). When proceeding from S54 to S55, a large amount of ink has been ejected from the color head 32 during the current printing process. As a result, a large amount of ink mist adheres to the nozzle surface 30A of the color head 32. When the amount of ink adhering to the nozzle surface 30A is too large, the adhering ink is more likely to enter the nozzle N. Therefore, when the amount of ink adhering increases significantly, the nozzle surface 30A of the color head 32 is wiped.

[0122] The color head wipe process in S55 performs the same process as the color head wipe process in S44 described above. As a result, the wiper 53 at the wipe position comes into contact with the nozzle surface 30A of the color head 32 and wipes. After the head unit 100 passes the wiper 53, the control unit 80 controls the wiper motor 54M to move the wiper 53 corresponding to the color head 32 to the contact position. Steps S48 to S50, S52, S54 and S55 in this embodiment correspond to the "forced wipe process" of this disclosure.

[0123] Next, the control unit 80 resets the second cumulative discharge amount C2 to 0 (S56). Then, the process proceeds to S40.

[0124] In S54, if the second cumulative discharge amount C2 is less than the second upper limit value U2 (S54: NO), the control unit 80 returns to S32.

[0125] In S34, when printing is completed (S34: YES), the control unit 80 proceeds to S57. In S57, the control unit 80 resets the first cumulative discharge amounts C1, H1, the second cumulative discharge amounts C2, H2, and the variable M to 0. Thus, the printing process in S3 shown in Figure 11 is completed.

[0126] Next, returning to Figure 10, the control unit 80 performs an ejection process to eject the printing medium (S4). In the ejection process, the control unit 80 controls the sub-scanning motor 14M to move the platen 12 to the set position P1 and stop it. The operator removes the printing medium with the printed image from the platen 12 located at the set position P1. At this time, the control unit 80 also controls the main scanning motor 7M to move the head unit 100 to the left and stop it at the cap position B1. The nozzle surface 30A of each head 30 located at the cap position B1 comes into contact with and is covered by the corresponding cap 51. Thus, the flow in Figure 10 is completed.

[0127] As described above, according to the printing apparatus 1 of this embodiment, when proceeding from S38 to S39, a large amount of ink adheres to each nozzle surface 30A, and the ink adhered to the nozzle surface 30A does not dry easily. On the other hand, when proceeding from S38 to S44, a small amount of ink adheres to the nozzle surface 30A of the color head 32, and the ink adhered to the nozzle surface 30A dries easily. Also, when proceeding from S41 to S42, a small amount of ink adheres to the nozzle surface 30A of the white head 31, and the ink adhered to the nozzle surface 30A dries easily. Also, when proceeding from S41 to S43, a small amount of ink adheres to the nozzle surfaces 30A of the two heads 30, and the ink adhered to the nozzle surface 30A dries easily. In this configuration, wiping by the wiper 53 is performed when the ink adhered to the nozzle surface 30A dries easily, and wiping by the wiper 53 is not performed when the ink adhered to the nozzle surface 30A dries difficult to dry. By determining whether to perform a wipe according to the drying state of the ink adhering to the nozzle surface 30A in this way, it becomes possible to maintain good ejection performance while reducing deterioration of the wiper 53.

[0128] The wipe determination processes in S37, S38, and S41 can be executed between the start and end of the printing process in S3. This reduces the increase in the number of wipe operations during the printing process. Therefore, the printing time can be reduced.

[0129] Furthermore, the wipe determination processes in S37, S38, and S41 are executed in S36 when the variable M reaches a predetermined number of MA values ​​(S36: YES). In other words, the wipe determination processes in S37, S38, and S41 are executed when the number of movements of the head unit 100 in the main scanning direction reaches a predetermined number. This makes it easier to control the timing of the wipe determination process.

[0130] The movement of the head unit 100 in the main scanning direction during the scanning process in S32 includes movements in which ink is ejected from the white head 31 but not from the color head 32. Furthermore, the movement of the head unit 100 in the main scanning direction also includes movements in which ink is not ejected from the white head 31 but is ejected from the color head 32. Thus, in a single ejection scan, movements in which ink is ejected from one head 30 but not from the other head 30 are also counted in S33. As a result, the variable M is more likely to reach a predetermined number of times MA than when the above movements are not counted in S33. In other words, the execution timing of the wipe determination processes in S37, S38, and S41 increases. Therefore, the determination of whether to perform a wipe can be made at a more appropriate timing.

[0131] S39 is executed after going through one of S37, S38, or S41. As a result, the first cumulative ejection amount H1 of white ink is the cumulative amount of ink ejected from the white head 31 until the variable M reaches a predetermined number of times MA. Similarly, the first cumulative ejection amount C1 of color ink is the cumulative amount of ink ejected from the color head 32 until the variable M reaches a predetermined number of times MA. Therefore, the first cumulative ejection amounts H1 and C1 can be easily derived.

[0132] The second threshold corresponding to the first cumulative discharge amount C1 of the color ink is smaller than the first threshold corresponding to the first cumulative discharge amount H1 of the white ink. The second threshold is set lower than that of the white ink in order to reduce the drying time of the color ink. This reduces the number of times the nozzle surface 30A of the color head 32 is wiped. As a result, it is possible to reduce the deterioration of the wiper 53 that wipes the nozzle surface 30A of the color head 32.

[0133] In S31, the control unit 80 sets a first setting threshold K1 and a second setting threshold K2 based on the temperature detected by the temperature sensor 57. As a result, when the ambient temperature of the nozzle surface 30A exceeds a predetermined temperature and the ink adhering to the nozzle surface 30A dries easily, the first setting threshold K1 and the second setting threshold K2 are set to the first upper threshold and the second upper threshold. The wipe determination process in S37, S38, and S41 is determined by the thresholds set in S31. Therefore, when the ambient temperature of the nozzle surface 30A exceeds a predetermined temperature, wiping is more likely to be performed than when the first setting threshold K1 and the second setting threshold K2 are set to the first threshold and the second threshold. Consequently, it becomes possible to effectively remove the ink adhering to the nozzle surface 30A by wiping with the wiper 53.

[0134] As a modified example, a humidity sensor 58 may be provided instead of the temperature sensor 57. The humidity sensor 58 is located inside the housing 8 and detects the ambient humidity around the nozzle surface 30A of the head unit 100. The humidity sensor 58 is shown by a dashed line in Figure 9. In this modified example, the first threshold is set when the humidity detected by the humidity sensor 58 is above a predetermined humidity. The first threshold is set to an amount of ink that makes it difficult for the white ink adhering to the nozzle surface 30A to dry, even when the ambient humidity around the nozzle surface 30A is at the predetermined humidity.

[0135] The first upper threshold is a threshold set when the humidity detected by the humidity sensor 58 is below a predetermined humidity. The first upper threshold is a higher value than the first threshold, and is set to an amount of ink that prevents the white ink adhering to the nozzle surface 30A from drying out easily, even when the ambient humidity around the nozzle surface 30A is below the predetermined humidity.

[0136] The second threshold is set when the humidity detected by the humidity sensor 58 is above a predetermined humidity. The second threshold is smaller than the first threshold and is set to an amount of ink that prevents the color ink adhering to the nozzle surface 30A from drying out, even when the ambient humidity around the nozzle surface 30A is at the predetermined humidity.

[0137] The second upper threshold is set when the humidity detected by the humidity sensor 58 is below a predetermined humidity. The second upper threshold is a higher value than the second threshold, and is set to an ink amount that prevents the color ink adhering to the nozzle surface 30A from drying out easily, even when the ambient humidity around the nozzle surface 30A is below the predetermined humidity.

[0138] In S31, the control unit 80 sets a first threshold as the first setting threshold K1 and a second threshold as the second setting threshold K2 when the humidity detected by the humidity sensor 58 is equal to or greater than a predetermined humidity. On the other hand, when the humidity detected by the humidity sensor 58 is less than a predetermined humidity, the control unit 80 sets a first upper threshold as the first setting threshold K1 and a second upper threshold as the second setting threshold K2.

[0139] According to this modified version, in an environment where the ambient humidity around the nozzle surface 30A is below a predetermined humidity and the ink adhering to the nozzle surface 30A dries easily, the first setting threshold K1 and the second setting threshold K2 are set to the first upper threshold and the second upper threshold. The wipe determination process in S37, S38, and S41 is determined by the threshold set in S31. Therefore, when the ambient humidity around the nozzle surface 30A is below a predetermined humidity, wiping is more likely to be performed than when the first setting threshold K1 and the second setting threshold K2 are set to the first threshold and the second threshold. Consequently, it becomes possible to effectively remove the ink adhering to the nozzle surface 30A by wiping with the wiper 53.

[0140] When the second cumulative discharge amount H2 of white ink is greater than or equal to the first upper limit U1, a forced wipe process is performed from S48 to S50. When the second cumulative discharge amount C2 of color ink is greater than or equal to the second upper limit U2, a forced wipe process is performed from S54 to S55. When the second cumulative discharge amount H2 is greater than or equal to the first upper limit U1 and the second cumulative discharge amount C2 is greater than or equal to the second upper limit U2, a forced wipe process is performed from S49 to S52. If too much ink adheres to the nozzle surface 30A, the adhered ink is likely to enter the nozzle. In such a situation, performing a forced wipe process as in this configuration makes it possible to reduce the amount of ink that enters the nozzle N. This reduces the disturbance in the direction of ink discharge from the nozzle N.

[0141] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible as long as they are within the scope of the claims.

[0142] In the above-described embodiment, the head unit 100 has two heads 30, but it may be composed of one or three or more heads 30. The head unit 100 may have two or more white heads 31. The head unit 100 may also have two or more color heads 32. When the number of heads 30 constituting the head unit 100 is three or more, the control unit 80 only needs to store the first cumulative discharge amount corresponding to each head 30. At this time, a threshold value should be set that determines whether or not to perform wiping of the nozzle surface 30A, corresponding to each first cumulative discharge amount.

[0143] The nozzle surfaces 30A of the two heads 30 of the head unit 100 may be connected to each other. In this case, there may be one wiper 53 corresponding to one connected nozzle surface 30A. It is preferable to have one wiper 53 corresponding to one nozzle surface 30A, but there may also be one wiper that corresponds to multiple nozzle surfaces 30A.

[0144] In the above-described embodiment, the first cumulative ejection amounts H1, C1 and the second cumulative ejection amounts H2, C2 are the cumulative amounts of ink ejected from the corresponding head 30 during ejection scanning. However, the first cumulative ejection amounts H1, C1 and the second cumulative ejection amounts H2, C2 may also include the amount of ink ejected from the corresponding head 30 when not performing ejection scanning. The amount of ink ejected from the head 30 when not performing ejection scanning may include the amount of ink ejected by either flushing or purging, or both. Furthermore, the first cumulative ejection amounts H1, C1 and the second cumulative ejection amounts H2, C2 may also include the amount of ink ejected from the corresponding head 30 when not performing ejection scanning.

[0145] In the above-described embodiment, the color ink as the second liquid dries less easily than the white ink as the first liquid. However, the first liquid may dry less easily than the second liquid. In this case, it is desirable that the first threshold is smaller than the second threshold.

[0146] Furthermore, when flushing, ink may be ejected into the cap 51. In this case, it is not necessary to provide an ink receiving plate 59, which contributes to miniaturization of the printing device. In this modified example, the cap 51 corresponds to the "receiving member" of this disclosure.

[0147] Furthermore, the printing apparatus 1 in the above-described embodiment has a head 30, which is a so-called serial head, that ejects ink while moving along the main scanning direction by a moving mechanism 7. However, the printing apparatus may also have a head, which is a line head, that extends along the entire length of the platen 12 in the main scanning direction and is immovably positioned in the ejection area B2. In other words, it is also possible to apply this disclosure to a printing apparatus equipped with a line head. In this case, it is not necessary to have a moving mechanism 7. Also, in the case of a printing apparatus equipped with a line head, it is sufficient to determine at an appropriate timing whether the first cumulative ejection amount is above a threshold and to determine whether or not to perform a wipe. As an appropriate timing, for example, it may be set to every predetermined elapsed time from the start of printing, or every predetermined transport amount of the platen 12. In the printing apparatus 1 in this embodiment as well, as an appropriate timing, it may be set to every predetermined elapsed time from the start of printing, or every predetermined transport amount of the platen 12.

[0148] The printing apparatus 1 in the above-described embodiment does not need to have a temperature sensor 57. Also, in the printing process of S3, the processes S48 to S56 do not need to be executed. In this case, if the answer in S36 is NO, the process can return to S32. Also, in this case, the processes S45 to S47 do not need to be executed. Also, in this case, the control unit 80 does not need to store the second cumulative ejection amounts C2 and H2.

[0149] Furthermore, in the above-described embodiments and their respective modifications, the control unit 80 may use a microcomputer, ASIC, FPGA, etc., as the processor instead of the CPU 81. In this case, the main processing may be distributed among multiple processors. Non-temporary storage media such as ROM 82 and flash memory 84 can be any storage medium capable of retaining information regardless of the period for which the information is stored. The control program may be downloaded, for example, from a server connected to a network (not shown) and stored in ROM 82 or flash memory 84. In this case, the control program may be stored in a non-temporary storage medium such as an HDD provided on the server.

[0150] While the present invention has been described in the context of a printing apparatus that prints on a printing medium by ejecting ink from a nozzle, the invention is not limited to this. For example, the present invention may be applied to a liquid dispensing apparatus other than a printing apparatus that dispenses a liquid other than ink, such as a liquid resin or metal, onto a dispensing medium. The dispensing medium is not limited to cloth, but may be paper, a resin material, or the like.

[0151] The program disclosed herein can be distributed by storing it on removable storage media such as flexible disks or fixed storage media such as hard disks, and can also be distributed via communication lines.

[0152] 1 Printing device 7 Moving mechanism 30 Head 30A Nozzle surface 53 Wiper 57 Temperature sensor 58 Humidity sensor 59 Ink receiving plate 80 Control unit 100 Head unit N Nozzle

Claims

1. A liquid dispensing device comprising: a nozzle surface having a nozzle for dispensing liquid; a wiper for wiping the nozzle surface; and a control unit, wherein the control unit is capable of performing a wipe determination process, in which wiping by the wiper is not performed when a first cumulative amount of liquid discharged from the nozzle is equal to or greater than a threshold, and wiping by the wiper is performed when it is less than the threshold.

2. The liquid dispensing device according to claim 1, wherein the control unit is capable of performing a printing process in which it discharges liquid from the nozzle toward a printing medium based on image data and prints an image on the printing medium, and performs the wipe determination process between the start and end of the printing process.

3. The liquid dispensing device according to claim 2, further comprising: a liquid dispensing head having the nozzle surface; and a moving mechanism for moving the liquid dispensing head in one direction along the nozzle surface, wherein the control unit controls the moving mechanism and the liquid dispensing head to move the liquid dispensing head in the one direction while dispensing liquid from the nozzle to print an image on a printing medium, and executes the wipe determination process when the movement of the liquid dispensing head in the one direction during the printing process reaches a predetermined number of times.

4. The liquid dispensing device according to claim 3, wherein the nozzle includes a first nozzle and a second nozzle, the nozzle surface includes a first nozzle surface having the first nozzle and a second nozzle surface having the second nozzle, and the movement in one direction includes movement of the liquid dispensing head such that liquid is discharged from one of the nozzles of the first nozzle surface and the second nozzle of the second nozzle surface, and liquid is not discharged from the other nozzle of the first nozzle surface and the second nozzle of the second nozzle surface.

5. The liquid dispensing device according to claim 3, characterized in that the first cumulative discharge volume is the amount of liquid discharged from the nozzle during the predetermined number of times the liquid dispensing head moves in one direction.

6. The liquid dispensing device according to claim 1, wherein the nozzle includes a first nozzle for dispensing a first liquid and a second nozzle for dispensing a second liquid that is less likely to dry than the first liquid; the nozzle surface includes a first nozzle surface having the first nozzle and a second nozzle surface having the second nozzle; the wiper includes a first wiper for wiping the first nozzle surface and a second wiper for wiping the second nozzle surface; the threshold includes a first threshold and a second threshold smaller than the first threshold; and in the wipe determination process, the control unit does not perform wiping with the first wiper when the cumulative amount of the first liquid discharged from the first nozzle is equal to or greater than the first threshold, and performs wiping with the first wiper when it is less than the first threshold; and does not perform wiping with the second wiper when the cumulative amount of the second liquid discharged from the second nozzle is equal to or greater than the second threshold, and performs wiping with the second wiper when it is less than the second threshold.

7. The liquid dispensing device according to claim 1, further comprising a temperature sensor for detecting the ambient temperature of the nozzle surface, wherein the control unit is capable of performing a setting process to set the threshold to a first set value when the temperature sensor detects a temperature below a predetermined temperature, and to set the threshold to a second set value higher than the first set value when the temperature sensor detects a temperature above the predetermined temperature.

8. The liquid dispensing device according to claim 1, further comprising a humidity sensor for detecting ambient humidity around the nozzle surface, wherein the control unit is capable of performing a setting process to set the threshold to a first set value when the humidity sensor detects humidity above a predetermined humidity, and to set the threshold to a second set value higher than the first set value when the humidity sensor detects humidity below the predetermined humidity.

9. The liquid dispensing device according to claim 1, further comprising a receiving member for receiving the liquid discharged from the nozzle, wherein the control unit can further perform a flushing process to discharge the liquid from the nozzle toward the receiving member based on flushing data, and the flushing process is performed following the wipe determination process.

10. The liquid dispensing apparatus according to claim 1, characterized in that the control unit can perform a forced wipe process to execute wiping by the wiper when the second cumulative discharge amount of liquid discharged from the nozzle exceeds an upper limit greater than the threshold.

11. A control method for a liquid dispensing device comprising a nozzle surface having a nozzle for dispensing liquid and a wiper for wiping the nozzle surface, characterized in that the control method is capable of performing a wipe determination process in which wiping by the wiper is not performed when a first cumulative amount of liquid discharged from the nozzle is equal to or greater than a threshold, and wiping by the wiper is performed when it is less than the threshold.

12. A program for a liquid dispensing device comprising a nozzle surface having a nozzle for dispensing liquid and a wiper for wiping the nozzle surface, wherein the control unit is configured to function as a wipe determination means, which does not perform wiping with the wiper when the first cumulative amount of liquid dispensed from the nozzle is equal to or greater than a threshold, and performs wiping with the wiper when it is less than the threshold.

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