Printing device and control program

Abstract

To suppress the occurrence of a malfunction due to reaction between ink in a nozzle and a volatile component of pretreatment liquid.SOLUTION: A control unit of a printer causes a head to execute non-discharge driving in at least a partial period other than a discharge period that discharges ink toward a printing medium from a nozzle by causing the head to execute discharge driving in a case where the head faces the printing medium applied with pretreatment liquid containing a volatile component.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a printing apparatus and a control program capable of printing by discharging ink onto a printing medium coated with a pretreatment liquid containing a volatile component that reacts with the ink.

Background Art

[0002] Patent Document 1 describes a printing apparatus including an inkjet head that evaporates a pretreatment agent before discharging color ink onto a printing medium coated with the liquid pretreatment agent and then discharges the color ink. Thereby, drying of the pretreatment agent can be appropriately promoted before discharging the color ink. [

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the printing apparatus described in Patent Document 1 above, when the pretreatment agent applied to the printing medium volatilizes during printing, the volatile component may react with the ink in the nozzles of the inkjet head. When the ink and the volatile component of the pretreatment agent react, problems such as the ink in the nozzles aggregating and causing ejection failure or color change in the ink may occur.

[0005] Therefore, an object of the present invention is to provide a printing apparatus and a control program capable of suppressing problems caused by the reaction between the ink in the nozzles and the volatile component of the pretreatment liquid.

Means for Solving the Problems

[0006] The printing apparatus of the present invention comprises a head having nozzles for ejecting ink, a platen capable of supporting a printing medium coated with a pretreatment liquid containing volatile components that react with ink, and a control unit. The control unit can cause the head to perform an ejection drive to eject ink from the nozzles and a non-ejection drive to not eject ink from the nozzles. When the head and the printing medium are facing each other, the control unit causes the head to perform the non-ejection drive for at least a portion of the period other than the ejection period in which the ejection drive is performed to eject ink from the nozzles toward the printing medium.

[0007] The control program of the present invention enables the control unit of a printing apparatus comprising a head having nozzles for ejecting ink and a platen capable of supporting a printing medium coated with a pretreatment liquid containing volatile components that react with ink, to cause the head to perform an ejection drive to eject ink from the nozzles and a non-ejection drive to not eject ink from the nozzles, and when the head and the printing medium are facing each other, to cause the head to perform the non-ejection drive for at least a portion of the period other than the ejection period in which the ejection drive is performed to eject ink from the nozzles toward the printing medium. [Effects of the Invention]

[0008] According to the printing apparatus and control program of the present invention, when the head and the printing medium are facing each other, it is possible to have the head perform a non-ejection drive for at least a portion of the period other than the ejection period. The non-ejection drive vibrates the ink to the extent that it does not eject ink from the nozzle, and stirs the ink near the meniscus with the ink upstream of the meniscus. By performing the non-ejection drive for at least a portion of the period other than the ejection period in this way, the ink near the meniscus that has reacted with the volatile components of the pretreatment liquid is stirred with the ink upstream. Therefore, it is possible to suppress problems caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic perspective view of a printing apparatus according to one embodiment of the present invention. [Figure 2] Figure 1 is a plan view showing the internal structure of the printing apparatus. [Figure 3] Figure 1 is a front view showing the internal structure of the printing apparatus. [Figure 4] This is a schematic diagram of the carriage as viewed from below. [Figure 5] This block diagram shows the electrical configuration of the printing apparatus shown in Figure 1. [Figure 6] This is a waveform diagram of the pulse signal output from the control unit when the discharge mechanism is activated. [Figure 7] This is a waveform diagram of the pulse signal output from the control unit when the device is not being driven for discharge. [Figure 8] This flowchart shows an example of the processing procedure executed when a print command is input to the printing device shown in Figure 1. [Figure 9] (a) is a diagram showing the situation when the platen is transported from the support position to the pre-printing standby position, and (b) is a diagram showing the situation when the platen is transported from the pre-printing standby position to the printing position. [Figure 10] This is a schematic plan view of a printing apparatus according to a modified example of the present invention. [Figure 11] Figure 10 is a flowchart showing an example of the processing procedure executed when a print command is input to the printing device. [Modes for carrying out the invention]

[0010] The printing apparatus 1 of the present invention will be described with reference to the drawings. In the following description, the vertical and horizontal directions (the "intersecting directions" of the present invention) are defined based on the state in which the printing apparatus 1 is installed for use (the state in Figure 1), and the left-right direction (the "unidirectional direction" of the present invention) is defined when viewing the printing apparatus 1 from the front.

[0011] 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 can print color images onto a printing medium using five colors of ink: white, black, yellow, cyan, and magenta. The printing medium can be fabric, paper, etc. In this embodiment, the printing medium is, for example, a T-shirt containing polyester fibers. When the printing device 1 performs printing on the printing medium (T-shirt), the printing medium, which has been pre-treated with a pre-treatment solution, is placed on the platen 12. The pre-treatment solution reacts with the ink ejected onto the pre-treatment solution, causing the ink components to coagulate and preventing bleeding. The volatile components of the pre-treatment solution include organic acids such as formic acid.

[0012] Hereinafter, the white ink among the five inks will be referred to as "white ink" (the "first ink" of this invention). The four inks of black, cyan, yellow, and magenta among the five inks will be referred to collectively as "color ink" (the "second ink" of this invention) when none of them are specified. When white ink and color ink are referred to collectively as, or when none of them are specified, they will simply be referred to as "ink". White ink is used in printing to represent the white parts of an image or as a base for color ink. Color ink is ejected onto a white ink base and used for printing color images.

[0013] 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 display screen 16. The housing 8 has a roughly rectangular parallelepiped shape, with rectangular platen openings 13 formed approximately in the center of the front surface in the left / right and up / down directions. Five cartridges (not shown) containing five colors of ink are housed inside the housing 8. As shown in Figure 2, the platen 12 consists of a plate-like member with a roughly rectangular planar shape. The upper surface of the platen 12 is a support surface 12a that supports the printing medium.

[0014] The operation unit 15 is provided at both left and right ends of a platen support portion 37 (described later) that protrudes forward from the platen opening 13. The operation unit 15 outputs information corresponding to an operation by the user to a control unit 80 described later. By operating the operation unit 15, the user can input to the control unit 80 a print instruction (including print data) for starting printing by the printing apparatus 1 and the like. The display screen 16 is provided at the upper right side of the front surface of the housing 8, which is closer to the right side than the platen opening 13. The display screen 16 displays various information. Accordingly, the operator operates the printing apparatus 1 on the front side of the printing apparatus 1.

[0015] The conveyance mechanism 14 conveys the platen 12 on which the print medium is placed between the inside and the outside of the housing 8 through the platen opening 13. When the platen 12 is disposed at a printing position P3 (a position indicated by a two-dot chain line in FIG. 2) inside the housing 8 shown in FIG. 2, ink is ejected from a head 30 described later and printing is performed. As shown in FIG. 2, the conveyance mechanism 14 includes a platen support portion 37, a pair of left and right rails 38, a transmission member 39, and a sub-scanning motor 26 (see FIG. 5).

[0016] As shown in FIGS. 2 and 3, the platen support portion 37 supports the platen 12 from below. The pair of left and right rails 38 extend in the front-rear direction and support the platen support portion 37 so as to be movable in the front-rear direction. The front ends of the pair of rails 38 are located in front of the front surface of the housing 8. The transmission member 39 is connected to the platen support portion 37 and the sub-scanning motor 26, and moves the platen support portion 37 in the front-rear direction along a conveyance path defined by the pair of left and right rails 38 in response to the drive of the sub-scanning motor 26. That is, the platen 12 moves in the front-rear direction by the drive of the sub-scanning motor 26. In the present embodiment, the front-rear direction is the sub-scanning direction. Further, the left-right direction is the scanning direction of the head 30 described later, and in the present embodiment, the left-right direction is the main scanning direction. In the following description, the left-right direction may be referred to as the main scanning direction, and the front-rear direction may be referred to as the sub-scanning direction.

[0017] In a state where the platen 12 is disposed in front of the front surface of the housing 8, that is, outside the housing 8, an operator places a printing medium on the support surface 12a of the platen 12. That is, the position of the platen 12 shown in FIG. 2 is the support position P1 for supporting the printing medium on the platen 12. Further, before printing on the printing medium, the platen 12 moves from the support position P1 to a pre-print standby position P2 (a position indicated by a two-dot chain line in FIG. 2). The pre-print standby position P2 is behind the printing position P3 and is at the rear end of the conveyance path of the platen 12. The platen 12 disposed at the pre-print standby position P2 does not face the head 30 described later even when the head 30 moves in the main scanning direction. The printing position P3 is a position where the movement path of the head 30 in the main scanning direction overlaps with the platen 12 in the vertical direction in the conveyance path of the platen 12. The movement path of the head 30 in the main scanning direction is a path between the rear end of the rearmost head 30 (white head 31) and the front end of the foremost head 30 (color head 34).

[0018] Referring to FIGS. 2 to 4, the internal structure of the printing apparatus 1 will be described. As shown in FIG. 2, the printing apparatus 1 includes a frame body 2, heads 31 to 34, and a moving mechanism 77 inside the housing 8. The frame body 2 is formed in a lattice shape by a plurality of shafts extending in the front-rear direction, left-right direction, or up-down direction. The moving mechanism 77 includes a guide shaft 20 and a carriage 6 fixed to the frame body 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 as shown in FIG. 2.

[0019] As shown in FIG. 2, the front shaft 21 is disposed at the front end portion of the frame body 2 and extends in the left-right direction from the left end portion to the right end portion of the frame body 2. The rear shaft 22 is disposed substantially at the center in the front-rear direction of the frame body 2 and extends in the left-right direction from the left end portion to the right end portion of the frame body 2. The left shaft 23 is disposed at the left end portion of the frame body 2 and extends in the front-rear direction from the left end of the front shaft 21 to the left end of the rear shaft 22. The right shaft 24 is disposed at the right end portion of the frame body 2 and extends in the front-rear direction from the right end of the front shaft 21 to the right end of the rear shaft 22. The front shaft 21 and the rear shaft 22 support the carriage 6. The conveyance mechanism 14 is fixed to the frame body 2.

[0020] As shown in Figure 2, the carriage 6 is supported by 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-right, and right directions. The carriage 6 extends from the front shaft 21 to the rear shaft 22.

[0021] As shown in Figures 2 and 4, the carriage 6 is provided with white heads (the "first head portion" of the present invention) 31 and 32, and color heads (the "second head portion" of the present invention) 33 and 34. These white heads 31 and 32 and color heads 33 and 34 constitute the "head" of the present invention.

[0022] The white heads 31 and 32 and the color heads 33 and 34 each have the same structure and, in this embodiment, are rectangular parallelepipeds. Hereinafter, when the white heads 31 and 32 and the color heads 33 and 34 are referred to collectively, or when none of them are specified, they will be referred to as "head 30". The white heads 31 and 32 are located at the rear of the carriage 6, as shown in Figure 4. White head 31 is located at the right rear of the carriage 6. White head 32 is located to the left of white head 31 and is shifted forward relative to white head 31. The rear of white head 32 overlaps with the front of white head 31 in the left-right direction.

[0023] As shown in Figures 2 and 4, the color heads 33 and 34 are positioned in front of the white heads 31 and 32. The color heads 33 and 34 are positioned in the same location as the white heads 31 and 32 in the left-right direction. In other words, the white heads 31 and 32 and the color heads 33 and 34 are arranged side by side along the sub-scanning direction. The color head 34 is positioned to the left of the color head 33 and is shifted in front of the color head 33. The rear of the color head 34 overlaps with the front of the color head 33 in the left-right direction.

[0024] As shown in Figure 4, a nozzle surface 311 is provided on the lower surface of the white head 31. The nozzle surface 311 extends in the front-back, left-right, and right directions. Multiple nozzle rows 312 are formed on the nozzle surface 311. The multiple nozzle rows 312 are arranged in the left-right direction. Each nozzle row 312 consists of multiple nozzles 313 arranged in a single row at equal intervals in the front-back direction. The multiple nozzles 313 are openings and eject white ink downwards.

[0025] Similar to the configuration of the white head 31, nozzle surfaces 321, 331, and 341 are provided on the lower surfaces of the white head 32, color heads 33, and 34, respectively. The nozzle surfaces 321, 331, and 341 extend in the front-back, left-right, and right directions. Multiple nozzle rows 322, 332, and 342 are formed on the nozzle surfaces 321, 331, and 341, respectively. The multiple nozzle rows 322, 332, and 342 are arranged in the left-right direction. Each nozzle row 322, 332, and 342 consists of multiple nozzles 323, 333, and 343 arranged in a single row at equal intervals in the front-back direction.

[0026] Multiple nozzles 323 eject white ink downwards. Multiple nozzle rows 332 each correspond to a different color ink. That is, multiple nozzles 333 eject the color ink of the color corresponding to each of the multiple nozzle rows 332 downwards. Multiple nozzle rows 342 each correspond to a different color ink. Multiple nozzles 343 eject the color ink of the color corresponding to each of the multiple nozzle rows 342 downwards.

[0027] As shown in Figures 2 and 4, the separation distance between the white head 31 and the color head 33 in the sub-scanning direction is greater than the separation distance between the two white heads 31 and 32 in the main scanning direction. The separation distance between the white head 32 and the color head 34 in the sub-scanning direction is also greater than the separation distance between the two white heads 31 and 32 in the main scanning direction.

[0028] The moving mechanism 77 includes a drive belt 98 and a main scanning motor 99. The drive belt 98 is connected to the rear end of the carriage 6. The drive belt 98 is mounted on the rear shaft 22 and extends in the left-right direction. The left end of the drive belt 98 is connected to the main scanning motor 99. When the main scanning motor 99 is driven, the drive belt 98 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 77 moves the carriage 6 on which the head 30 is mounted in the main scanning direction. Figures 2 and 3 show the state in which the carriage 6 is located at the right end of the movement range R.

[0029] In Figures 2 and 3, the movement range R of the head 30 is shown at the center of the carriage 6 in the left-right direction. As shown in Figure 3, the head 30 is mainly positioned in one of three positions by the movement mechanism 77: maintenance position B1, ejection position B2, and head standby position B3. Maintenance position B1 is at the left end of the movement range R of the head 30, and is the position where the head 30 is maintained by a maintenance unit such as a wiper or cap (not shown). When not printing, the printing device 1 moves the head 30 to maintenance position B1 and performs maintenance by the maintenance unit. Ejection position B2 is a position between maintenance position B1 and head standby position B3 in the main scanning direction, and above the platen 12 located at the printing position P3. With the head 30 positioned at ejection position B2, the head 30 ejects ink according to the print data, and printing is performed on the printing medium on the platen 12 located at the printing position P3. The head standby position B3 is located at the right end of the movement range R of the head 30, and is the position where an operator is positioned when performing operations such as cleaning on the head 30. The printing device 1 moves the head 30 to the head standby position B3 and puts it into standby mode, for example, based on instructions input from the control unit 15 by the user.

[0030] The printing apparatus 1 moves the platen 12 in the sub-scanning direction by driving the sub-scanning motor 26 at the printing position P3, and moves the carriage 6 in the main scanning direction by driving the main scanning motor 99 at the ejection position B2, thereby moving the printing medium relative to the head 30 in the sub-scanning direction and the main scanning direction.

[0031] The operation of moving the head 30 in the main scanning direction and ejecting ink onto the printing medium when the head 30 is facing the printing medium is called "ejection scanning." The printing device 1 prints on the printing medium by repeating ejection scanning and moving the platen 12 in the sub-scanning direction. For example, during ejection scanning, the printing device 1 ejects white ink from the white heads 31 and 32 to form a base layer on the printing medium. On top of the base layer formed on the printing medium during ejection scanning, the printing device 1 ejects color ink from the color heads 33 and 34 to print a color image.

[0032] Referring to Figure 5, the electrical configuration of the printing device 1 will be explained. The printing device 1 has a control unit 80. 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, information required by the CPU 81 when executing various programs, etc. For example, the ROM 82 stores the positions of the carriage 6 (head 30) based on the rotation angle of the main scanning motor 99, and stores the positions of the platen 12 based on the rotation angle of the sub-scanning motor 26. The RAM 83 temporarily stores various data used in the control program, etc. The flash memory 84 is non-volatile and stores printing data, etc. for printing.

[0033] As shown in Figure 5, the control unit 80 is electrically connected to the main scanning motor 99, the sub-scanning motor 26, the four head drive units 301 to 304, and the operation unit 15. The main scanning motor 99, the sub-scanning motor 26, and the head drive units 301 to 304 are driven by control from the control unit 80.

[0034] Encoders 991 and 261 are provided for the main scanning motor 99 and the sub-scanning motor 26, respectively. Encoder 991 detects the rotation angle of the main scanning motor 99 and outputs the detection result to the control unit 80. Encoder 261 detects the rotation angle of the sub-scanning motor 26 and outputs the detection result to the control unit 80.

[0035] The four head drive units 301 to 304 correspond to the white heads 31 and 32 and the color heads 33 and 34 in order, and are contained within these heads 31 to 34. Each head drive unit 301 to 304 is composed of multiple drive elements (piezoelectric elements or heating elements) capable of selectively supplying energy to the ink in multiple individual channels that communicate with multiple nozzles of the head 30. By being driven, each of these head drive units 301 to 304 supplies energy to the ink in the white heads 31 and 32 and the color heads 33 and 34, and selectively ejects or agitates the ink from the corresponding nozzles 313, 323, 333, and 343 without ejecting it.

[0036] This section describes the ejection drive, which ejects ink from the nozzles of the head 30, and the non-ejection drive, which does not eject ink. The ejection drive is an operation in which energy is applied to the ink in the head 30 by the drive of the head drive units 301 to 304, causing the ink to be ejected from the corresponding nozzles. In other words, the control unit 80 outputs a pulse signal with a pulse width T1 as shown in Figure 6 to the corresponding drive elements of the head drive units 301 to 304 for one printing cycle T. The pulse width T1 is long enough for ink to be ejected from the head 30. When the ejection drive is performed with the head 30 and the printing medium facing each other, the ink ejected from the corresponding nozzle lands on the printing medium, forming a background or image on the printing medium. One printing cycle T is the time required for the printing medium and the head 30 to move relative to each other by a unit distance corresponding to the printing resolution in the main scanning direction.

[0037] Non-ejection drive is an operation in which the head drive units 301 to 304 drive the ink in the head 30 to vibrate the ink in the corresponding nozzles by applying energy to the ink in the head 30 within a range that does not cause ink to be ejected from the nozzles of the head 30. In other words, the control unit 80 outputs a pulse signal with a pulse width T2 as shown in Figure 7 to the corresponding drive elements of the head drive units 301 to 304 for one printing cycle T. The pulse width T2 is short enough that ink is not ejected from the head 30, and is shorter than the pulse width T1. Alternatively, non-ejection drive may be performed by applying a voltage smaller than the voltage V1 used during ejection drive to apply energy to the ink in the head 30 within a range that does not cause ink to be ejected from the head 30. When non-ejection drive is performed, the ink near the meniscus and the ink upstream of the meniscus are stirred.

[0038] <Printing control> Referring to Figure 8, the control by the control unit 80 when printing an image on a printing medium will be explained. When the user operates the operation unit 15 and a print command is input to the printing device 1, the control unit 80 reads the control program from the ROM 82 and executes the flow shown in Figure 8. The flow shown in Figure 8 will be explained below.

[0039] The control unit 80 first determines whether or not a print command has been input (S1). Before the user operates the operation unit 15 to input a print command, the user applies a pre-treatment liquid to the printing medium. The pre-treatment liquid may be applied from an application mechanism such as a spray or head, which is provided separately from the printing device 1, when a print start command is input. The printing medium (T-shirt) is then placed on the support surface 12a of the platen 12 before the volatile components of the pre-treatment liquid applied to the printing medium have finished evaporating. In other words, the printing medium can be placed on the platen 12 immediately after the pre-treatment liquid has been applied, without any special treatment such as drying. In this embodiment, when S1 is processed, the printing medium is supported on the platen 12 immediately after the pre-treatment liquid has been applied. Therefore, during the printing process described later, organic acids evaporate from the pre-treatment liquid applied to the printing medium. The platen 12 is positioned at the support position P1 when not printing. When not printing, the printing apparatus 1 normally has the print head 30 positioned at maintenance position B1, and the multiple nozzles of the print head 30 are capped by a cap of a maintenance unit (not shown).

[0040] If no print command is entered (S1:NO), S1 is repeated until a print command is entered. On the other hand, if a print command is entered (S1:YES), the control unit 80 executes the printing process (S2).

[0041] As shown in Figure 9(a), the control unit 80 controls the sub-scanning motor 26 based on the detection result from the encoder 261 to move the platen 12 from the support position P1 to the pre-print standby position P2. After this, as shown in Figure 9(b), the control unit 80 controls the sub-scanning motor 26 based on the detection result from the encoder 261 to move the platen 12 from the pre-print standby position P2 to the print position P3. At this time, the control unit 80 also performs uncapping, separating the cap from the head 30.

[0042] Then, the control unit 80 controls the main scanning motor 99 based on the detection result from the encoder 991, moving the carriage 6 from the maintenance position B1 to the ejection position B2, so that the head 30 faces the printing medium placed on the platen 12. At this time, the control unit 80 controls the head drive units 301 to 304 so that non-ejection drive is performed in all nozzles 313, 323, 333, 343 of the white heads 31, 32 and color heads 33, 34 for the entire period from when the head 30 moves from the maintenance position B1 to the ejection position B2.

[0043] The control unit 80 may also control the head drive units 301 to 304 so that non-ejection drive is performed in all nozzles 313, 323, 333, and 343 of the white heads 31 and 32 and the color heads 33 and 34 for a portion of the period (corresponding to one or more printing cycles T) while the head 30 is moving from the maintenance position B1 to the ejection position B2. By performing non-ejection drive for a portion of the period, the ink near the meniscus that has reacted with the volatile components of the pretreatment liquid is mixed with the ink on the upstream side, as described later. This makes it possible to suppress malfunctions caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid. The control unit 80 may also control the head drive units 301 to 304 so that non-ejection drive is performed in some nozzles 313, 323, 333, and 343 of the white heads 31 and 32 and the color heads 33 and 34 for a portion or all of the period while the head 30 is moving from the maintenance position B1 to the ejection position B2.

[0044] The control unit 80 controls the head drive units 301-304, the main scanning motor 99, and the sub-scanning motor 26 when the platen 12 is in the printing position P3 and the carriage 6 is in the ejection position B2, and prints on the printing medium by alternately repeating ejection scanning and the forward movement of the platen 12. In other words, when printing on the printing medium, the platen 12 is transported forward from the pre-printing standby position P2 to the printing position P3. First, ink is ejected from the nozzles of the white heads 31 and 32 onto the printing medium coated with pre-treatment liquid, forming a base layer. Then, ink is ejected from the nozzles of the color heads 33 and 34 onto the base layer formed on the printing medium after passing through the white heads 31 and 32, forming an image. The white areas of the image are represented by the base layer formed with white ink. Therefore, no color ink is ejected onto this base layer.

[0045] When printing on such a printing medium, the control unit 80 controls the head drive units 303 and 304 so that, for the entire duration of the ejection scan, non-ejection drive is performed at all nozzles 333 and 343 of the color heads 33 and 344, when the platen 12 has not been transported to a position where it can face the color heads 33 and 34, but has been transported to a position where it can face the white heads 31 and 32, and ink is ejected from the nozzles 313 and 323 of the white heads 31 and 32 onto the printing medium to form a base layer.

[0046] Furthermore, the control unit 80 may control the head drive units 303 and 304 so that non-ejection drive is performed in all nozzles 333 and 343 of the color heads 33 and 34 for a portion of the ejection scan period (a period corresponding to one or more printing cycles T) when a base layer is formed on the printing medium before the color heads 33 and 34 face the printing medium. By performing non-ejection drive for a portion of the period, it is possible to suppress malfunctions caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid, as described above. Alternatively, the control unit 80 may control the head drive units 303 and 304 so that non-ejection drive is performed in some nozzles 333 and 343 of the color heads 33 and 34 for a portion or all of the ejection scan period when a base layer is formed on the printing medium before the color heads 33 and 34 face the printing medium.

[0047] Furthermore, at this time, the control unit 80 controls the head drive units 301 and 302 so that, when the printing medium and the white heads 31 and 32 are facing each other, non-ejection drive is performed at each nozzle 313 and 323 during all periods other than the ejection period in which the ejection drive is performed by the white heads 31 and 32 to eject ink from the nozzles 313 and 323 to the printing medium. Note that if ink is ejected once or more within one printing cycle, that printing cycle is considered an ejection period.

[0048] Furthermore, the control unit 80 may control the head drive units 301 and 302 so that, when the printing medium and the white heads 31 and 32 are facing each other, non-ejection drive is performed in each nozzle 313 and 323 during a period other than the ejection period in which the white heads 31 and 32 are executed to eject ink from the nozzles 313 and 323 to the printing medium (a period corresponding to one or more printing cycles T). By performing non-ejection drive for a period of time, it is possible to suppress malfunctions caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid, as described above.

[0049] Furthermore, the control unit 80 controls the head drive units 301 to 304 so that when the platen 12 is transported to a position where it can face the white heads 31, 32 and the color heads 33, 34, and during ejection scanning, when ink is ejected from the nozzles 313, 323 of the white heads 31, 323 to form the base layer, and when ink is ejected from the nozzles 333, 343 of the color heads 33, 34 to form the image, non-ejection drive is performed at each nozzle 313, 323, 333, 343 for all periods other than the ejection period.

[0050] Furthermore, the control unit 80 may control the head drive units 301 to 304 so that, during ejection scanning, when ink is ejected from the nozzles 313 and 323 of the white heads 31 and 32 to form a base layer, and when ink is ejected from the nozzles 333 and 343 of the color heads 33 and 34 to form an image, non-ejection drive is performed in each nozzle 313, 323, 333, and 343 for a period other than the ejection period (a period corresponding to one or more printing cycles T). In this case as well, by performing non-ejection drive for a period of time, it is possible to suppress malfunctions caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid, as described above.

[0051] Furthermore, the control unit 80 controls the head drive units 301 and 302 so that non-ejection drive is performed at all nozzles 313 and 323 of the white heads 31 and 32 for the entire duration of the ejection scan when the entire platen 12 passes through the white heads 31 and 32 and only an image is formed on the printing medium (when the printing medium and the white heads 31 and 32 do not face each other, but the color heads 33 and 34 face each other, and ink is ejected from the nozzles 333 and 343 of the color heads 33 and 34 onto the printing medium to form an image).

[0052] The control unit 80 may also control the head drive units 301 and 302 so that non-ejection drive is performed in all nozzles 313 and 323 of the white heads 31 and 32 for a portion of the ejection scan period (a period corresponding to one or more printing cycles T) when the entire platen 12 passes through the white heads 31 and 32 and only an image is formed on the printing medium. Performing non-ejection drive for a portion of the period makes it possible to suppress malfunctions caused by reactions between the ink in the nozzles and volatile components of the pretreatment liquid, as described above. Alternatively, the control unit 80 may also control the head drive units 301 and 302 so that non-ejection drive is performed in some nozzles 313 and 323 of the white heads 31 and 32 for a portion or all of the ejection scan period when the entire platen 12 passes through the white heads 31 and 32 and only an image is formed on the printing medium.

[0053] Furthermore, at this time, the control unit 80 controls the head drive units 303 and 304 so that non-ejection drive is performed in each nozzle 333 and 343 during all periods other than the ejection period when the printing medium and the color heads 33 and 34 are facing each other.

[0054] Furthermore, the control unit 80 may control the head drive units 303 and 304 so that non-ejection drive is performed in each nozzle 333 and 343 for a period other than the ejection period (a period corresponding to one or more printing cycles T) when the printing medium and the color heads 33 and 34 are facing each other. In this case as well, by performing non-ejection drive for a period of time, it is possible to suppress malfunctions caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid, as described above.

[0055] Next, when printing on the printing medium based on the print data is completed, the control unit 80 controls the sub-scanning motor 26 based on the detection result from the encoder 261 to stop the platen 12 at the support position P1. The user removes the printed medium with the image formed on it from the platen 12 which is positioned at the support position P1. At this time, the control unit 80 also controls the main scanning motor 99 based on the detection result from the encoder 991 to move the carriage 6 to the left from the ejection position B2 and stop it at the maintenance position B1. Then, the control unit 80 caps the head 30 with the cap of the maintenance unit. This completes the flow shown in Figure 8.

[0056] As described above, according to the printing apparatus 1 of this embodiment, in ejection scanning, when the head 30 and the printing medium are facing each other, it is possible to have the head 30 perform a non-ejection drive for all periods other than the ejection period. The non-ejection drive vibrates the ink to the extent that it does not eject ink from the nozzle, and the ink near the meniscus and the ink upstream of the meniscus can be stirred. Because the non-ejection drive is performed for all periods other than the ejection period in this way, even if volatile components of the pretreatment liquid enter the nozzle, the ink near the meniscus that has reacted with these volatile components is stirred with the ink upstream. Therefore, it is possible to suppress malfunctions caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid. Furthermore, as described above, it is possible to suppress malfunctions caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid, so it is possible to use a pretreatment liquid that contains organic acids as volatile components.

[0057] As mentioned above, during ejection scanning, when the head 30 and the printing medium are facing each other, the head 30 may be made to perform a non-ejection drive for a period other than the ejection period. Although the frequency of ink agitation due to the non-ejection drive is reduced compared to the above embodiment, the ink near the meniscus that has reacted with the volatile components of the pretreatment liquid is agitated with the ink on the upstream side. Therefore, it is possible to suppress problems caused by the reaction between the ink in the nozzle and the volatile components of the pretreatment liquid.

[0058] Furthermore, the control unit 80 performs non-ejection drive in all nozzles of the white heads 31, 32 and color heads 33, 34 for the entire period from when the head 30 moves from the maintenance position B1 to the ejection position B2, and during ejection scanning, when the head 30 and the printing medium are facing each other, it causes the head 30 to perform non-ejection drive for the entire period other than the ejection period. In other words, when the head 30 is moving in the main scanning direction, the control unit 80 causes the head 30 to perform non-ejection drive for the entire period other than the ejection period. This makes it possible to further suppress malfunctions caused by reactions between the ink in nozzles 313, 323, 333, 343 and volatile components of the pretreatment liquid.

[0059] As a variation, the control unit 80 does not need to perform non-discharge drive while the head 30 moves from the maintenance position B1 to the discharge position B2.

[0060] Furthermore, during the ejection scan when printing to the printing medium, the control unit 80 performs a non-ejection drive in all nozzles 333, 343 of the color heads 33, 34 when a base layer is formed on the printing medium before the color heads 33, 34 come into contact with the printing medium, and performs a non-ejection drive in all nozzles 313, 323 of the white heads 31, 32 when the entire platen 12 passes through the white heads 31, 32 and an image is formed on the printing medium. In other words, if ink is ejected from only one of the heads (white head or color head) among the white heads 31, 32 and color heads 33, 34, the control unit 80 causes the other head (color head or white head) to perform a non-ejection drive. This makes it possible to suppress malfunctions caused by the reaction between the ink in the nozzles of the other head and the volatile components of the pretreatment liquid. Furthermore, when both the white heads 31, 32 and the color heads 33, 34 are facing the printing medium, if ink is ejected from only one head (either the white head or the color head), the same effect as described above can be obtained by causing the other head (either the color head or the white head) to perform a non-ejection drive.

[0061] Furthermore, the white heads 31, 32 and the color heads 33, 34 are arranged side by side along the sub-scanning direction. This allows the white ink ejection from the white heads 31, 32 to form the base layer on the printing medium and the color ink ejection from the color heads 33, 34 to form the image on the base layer of the printing medium to occur at the same time when the printing medium is facing the white heads 31, 32 and the color heads 33, 34. As a result, the printing time can be shortened.

[0062] In the above-described embodiment, a printing medium coated with a pre-treatment solution was placed on the platen 12 and printing was performed on the printing medium. However, the printing apparatus 1 may have a pre-treatment solution coating mechanism that coats the printing medium with a pre-treatment solution containing volatile components similar to those described above. Components similar to those in the above-described embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0063] In the modified printing apparatus 201, as shown in Figure 10, the pretreatment liquid application mechanism 202 is positioned between the support position P1 and the printing position P3 in the front-rear direction. The pretreatment liquid application mechanism 202 is also located inside the housing 8 and above the support surface 12a of the platen 12. The pretreatment liquid application mechanism 202 has a plurality of nozzles 203 that spray the pretreatment liquid in a mist downwards. The plurality of nozzles 203 are arranged in a line along the left-right direction so that the pretreatment liquid can be sprayed onto the entire upper surface of the printing medium. The printing apparatus 201 is also provided with a storage section (not shown) capable of storing the pretreatment liquid, and the pretreatment liquid is supplied from this storage section to the pretreatment liquid application mechanism 202.

[0064] <Printing control> Referring to Figure 11, the control by the control unit 80 when printing an image on a printing medium will be explained. Similar to the embodiment described above, when the user operates the operation unit 15 and a print command is input to the printing device 201, the control unit 80 reads the control program from the ROM 82 and operates, executing the flow shown in Figure 11. The flow shown in Figure 11 will be explained below.

[0065] The control unit 80 first performs F1, which is the same as S1 described above. In this modified example, since there is a pretreatment liquid coating mechanism 202, the user places the printing medium (T-shirt), which has not been pre-coated with pretreatment liquid, on the support surface 12a of the platen 12 before operating the operation unit 15 to input a print command. In this modified example as well, when F1 is processed, the printing medium is supported by the platen 12. The platen 12 is positioned at the support position P1 when not printing.

[0066] If no print instruction is entered (F1:NO), F1 is repeated until a print instruction is entered. On the other hand, if a print instruction is entered (F1:YES), the control unit 80 determines whether the entered print instruction includes an instruction to apply a pretreatment liquid containing volatile components to the printing medium (F2).

[0067] If a pretreatment solution is applied to the printing medium (F2:YES), the control unit 80 executes the first printing process (F3). In this modified example, the first printing process is performed in the same manner as in the above embodiment after applying the pretreatment solution to the printing medium.

[0068] The control unit 80 controls the sub-scanning motor 26 based on the detection result from the encoder 261 to move the platen 12 from the support position P1 to the pre-printing standby position P2. At this time, the control unit 80 controls the pre-treatment liquid application mechanism 202 so that the pre-treatment liquid is sprayed in a mist onto the printing medium as the printing medium passes through the area facing the multiple nozzles 203. This allows the pre-treatment liquid to be applied to the upper surface of the printing medium.

[0069] Next, the control unit 80 controls the sub-scanning motor 26 based on the detection result from the encoder 261 to move the platen 12 from the pre-print standby position P2 to the print position P3. At this time, the control unit 80 also performs uncapping, separating the cap from the head 30. Then, it performs the same printing process as in the embodiment described above to form an image on the printing medium.

[0070] Next, when printing on the printing medium based on the print data is completed, the control unit 80 controls the sub-scanning motor 26 based on the detection result from the encoder 261 to stop the platen 12 at the support position P1. The user removes the printed medium with the image formed on it from the platen 12 which is positioned at the support position P1. At this time, the control unit 80 also controls the main scanning motor 99 based on the detection result from the encoder 991 to move the carriage 6 to the left from the ejection position B2 and stop it at the maintenance position B1. Then, the control unit 80 caps the head 30 with the cap of the maintenance unit. This completes the flow shown in Figure 11.

[0071] On the other hand, if no pretreatment solution is applied to the printing medium in F2 (F2:NO), the control unit 80 executes the second printing process (F4). In this modified example, the second printing process is mainly performed when printing a test pattern to check whether or not the nozzles of the head 30 are ejecting ink, but it is not particularly limited and applies to any printing process that ejects ink onto a printing medium to which no pretreatment solution has been applied. In the second printing process, the non-ejection drive described above is not performed.

[0072] In the second printing process, the platen 12, on which the printing medium (e.g., paper) that has not been coated with pretreatment solution is placed, is moved from the support position P1 to the pre-printing standby position P2. After this, the platen 12 is moved from the pre-printing standby position P2 to the printing position P3. Then, the carriage 6 is moved from the maintenance position B1 to the ejection position B2, and the head 30 is brought into contact with the printing medium placed on the platen 12. After this, printing is performed on the printing medium by alternately repeating ejection scanning and the forward movement of the platen 12 based on the print data.

[0073] Next, when printing on the printing medium based on the print data is completed, the control unit 80 controls the sub-scanning motor 26 based on the detection result from the encoder 261 to stop the platen 12 at the support position P1. The user removes the printed medium with the image formed on it from the platen 12 which is positioned at the support position P1. At this time, the control unit 80 also controls the main scanning motor 99 based on the detection result from the encoder 991 to move the carriage 6 to the left from the ejection position B2 and stop it at the maintenance position B1. Then, the control unit 80 caps the head 30 with the cap of the maintenance unit. This completes the flow shown in Figure 11.

[0074] As described above, the printing apparatus 201 in this modified example has a pretreatment liquid application mechanism 202, which makes it possible to apply a pretreatment liquid to the printing medium. Therefore, it is not necessary to apply a pretreatment liquid to the printing medium in advance.

[0075] Furthermore, if the pretreatment solution is not applied to the printing medium (F2:NO), the control unit 80 does not perform a non-ejection drive at F4. In this case, since the printing medium is not coated with a pretreatment solution containing volatile components, the ink in the nozzle does not react with the volatile components of the pretreatment solution. In this way, when no problems occur due to the reaction between the ink and volatile components, it is possible to suppress power consumption by not performing a non-ejection drive.

[0076] Furthermore, the pretreatment liquid application mechanism 202 is configured to spray the pretreatment liquid onto the printing medium in a mist. This makes it possible to apply a large amount of pretreatment liquid to a wide area of ​​the printing medium in a short time. The pretreatment liquid application mechanism 202 is not particularly limited as long as it is capable of applying the pretreatment liquid to the printing medium. For example, the pretreatment liquid may be applied to the printing medium with a roller, or the pretreatment liquid may be discharged from a nozzle in a manner other than mist and applied to the printing medium.

[0077] Furthermore, the pretreatment liquid coating mechanism 202 described above may be configured to selectively coat the printing medium with a pretreatment liquid containing volatile components and a pretreatment liquid that does not contain volatile components. In this case, when a pretreatment liquid that does not contain volatile components is coated onto the printing medium, first, the pretreatment liquid that does not contain volatile components is coated onto the printing medium, as in the application of pretreatment liquid to the printing medium in the first printing process, and then, as in the second printing process, printing is performed on the printing medium without executing a non-discharge drive.

[0078] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible as long as they are within the scope of the claims.

[0079] In the embodiments and modifications described above, underlay printing, which forms a base on the printing medium coated with pretreatment liquid, and image printing, which forms an image on the base, are performed during a single transport process in which the platen 12 is transported from the pre-printing standby position to the support position. However, underlay printing may be performed only during the first transport process, and image printing only during the second transport process. In this case, when the head 30 is moving in the main scanning direction during the first transport process, non-ejection drives may be continuously or intermittently performed at the nozzles of the color heads 33 and 34, and when the head 30 is moving in the main scanning direction during the second transport process, non-ejection drives may be continuously or intermittently performed at the nozzles of the white heads 31 and 32.

[0080] Furthermore, in the above-described embodiment, the platen 12 moves along the sub-scanning direction (front-to-back direction) together with the printing medium by the transport mechanism 14, but the platen 12 may be positioned so as not to move at the printing position P3. In this case, the platen 12 only needs to be able to support the transported printing medium (e.g., paper or roll paper) at the printing position P3.

[0081] Furthermore, although the above-described embodiment describes an example in which the head 30 is a so-called serial head that ejects ink from multiple nozzles while moving along the main scanning direction (left-right direction) by a moving mechanism 77, the present invention is not limited to this. For example, the present invention can also be applied to a printing device equipped with a line head that extends along the entire length of the printing medium (platen 12) in the main scanning direction and is immovably positioned at the ejection position B2. In this case, when the printing medium is transported in the sub-scanning direction and comes into contact with the printing medium (printing medium coated with pretreatment liquid), the non-ejection drive should be performed at the same timing as described above.

[0082] Furthermore, in the above-described embodiments and their respective modifications, the control unit 80 may use a microcomputer, ASIC (Application Specific Integrated Circuits), FPGA (Field Programmable Gate Array), 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. Non-temporary storage media do not necessarily have to include temporary storage media (e.g., transmitted signals). The control program may be downloaded from, for example, a server connected to a network (not shown) (i.e., transmitted as a transmission signal) and stored in ROM 82 or flash memory 84. In this case, the control program only needs to be stored in a non-temporary storage medium such as an HDD provided in the server. [Explanation of Symbols]

[0083] 1,201 Printing equipment 31, 32 Head (First head section) 33,34 Head (Second Head Section) 12 Platen 77 Moving mechanism 80 Control Unit 202 Pretreatment liquid application mechanism 313,323,333,343 nozzles

Claims

1. A head having a nozzle for ejecting ink, A platen capable of supporting a printing medium coated with a pretreatment solution containing volatile components that react with ink, A pretreatment liquid application mechanism for applying the pretreatment liquid to a printing medium, It includes a control unit, The control unit, The head can be made to perform an ejection drive that ejects ink from the nozzle and a non-ejection drive that does not eject ink from the nozzle. When the head and the printing medium are facing each other, the non-ejection drive is performed on the head during at least a portion of the period other than the ejection period in which the ejection drive is performed to eject ink from the nozzle toward the printing medium. A printing apparatus characterized in that, if the pretreatment liquid has not been applied to the printing medium by the pretreatment liquid application mechanism, the head is not allowed to perform the non-discharge drive.

2. The system further includes a moving mechanism that moves the head so that it moves relative to the platen in one direction. The printing apparatus according to claim 1, characterized in that the control unit causes the head to perform the non-ejection drive for at least a portion of the period other than the ejection period when the head is moving in the one direction.

3. The printing apparatus according to claim 2, characterized in that the control unit causes the head to perform the non-ejection drive during all periods other than the ejection period when the head is moving in the one direction.

4. The head comprises a first head section having a nozzle for ejecting a first ink, and a second head section having a nozzle for ejecting a second ink different from the first ink onto the first ink. The printing apparatus according to any one of claims 1 to 3, characterized in that when the control unit causes one of the first head unit and the second head unit to perform the ejection drive, it causes the other head unit to perform the non-ejection drive.

5. The system further includes a moving mechanism that moves the head so that it moves relative to the platen in one direction. The printing apparatus according to claim 4, characterized in that the first head portion and the second head portion are arranged side by side along an intersecting direction that intersects the aforementioned one direction.

6. The printing apparatus according to any one of claims 1 to 5, characterized in that the pretreatment liquid application mechanism is configured to spray the pretreatment liquid onto the printing medium in a mist.

7. The printing apparatus according to any one of claims 1 to 6, characterized in that the pretreatment liquid contains an organic acid as a volatile component.

8. A control unit of a printing apparatus comprising a head having a nozzle for ejecting ink, a platen capable of supporting a printing medium coated with a pretreatment liquid containing volatile components that react with the ink, and a pretreatment liquid coating mechanism for coating the printing medium with the pretreatment liquid, This enables the head to perform both an ejection drive, which ejects ink from the nozzle, and a non-ejection drive, which does not eject ink from the nozzle. A control program characterized in that, when the head and the printing medium are facing each other, the head is made to perform the non-ejection drive for at least a portion of the period other than the ejection period in which the ejection drive is performed to eject ink from the nozzle toward the printing medium, and the head is not made to perform the non-ejection drive if the pretreatment liquid has not been applied to the printing medium by the pretreatment liquid application mechanism.

Images