Liquid discharge device and control method for liquid discharge device

Abstract

To provide a liquid discharge device capable of improving discharge stability and a control method for the liquid discharge device.SOLUTION: A controller 7 of a liquid discharge device calculates a printing section S representing a position of a discharge head 4 at which ink 51 is discharged from the discharge head 4 in each pass on the basis of image data and a non-printing section R representing a position of the discharge head 4 at which ink 51 is not discharged from the discharge head 4, and controls a valve 6 such that an aperture of a supply flow path 5 becomes smaller than an aperture of the valve 6 in the printing section S in an aperture limiting section Rr being a section of at least a part of the non-printing section R.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus and a method for controlling the liquid ejection apparatus. [Background technology]

[0002] BACKGROUND ART Inkjet recording apparatuses have been known for some time (see, for example, Patent Document 1).

[0003] This inkjet recording device is equipped with a movable valve provided in a movable valve chamber inside the recording head unit, and a biasing means for biasing the movable valve so as to open the ink flow path when the carriage is moving at a constant speed or is stopped, and to close the ink flow path when the carriage is moving at an accelerated or decelerated speed. As a result, when the recording head unit mounted on the carriage is moving at an accelerated or decelerated speed, the movable valve moves by inertia force to a position where it closes the ink flow path, preventing the dynamic pressure generated in the ink inside the tube from being transmitted to the recording head. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-268448 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the inkjet recording device described in Patent Document 1 had a problem in that when the acceleration was below a certain level, the inertial force required for the movable valve to move to a position where it would block the ink flow path did not act, and the dynamic pressure generated in the ink in the tube could not be prevented from being transmitted to the recording head. [Means for solving the problem]

[0006] In order to solve the above problem, a liquid ejection device according to one aspect of the present disclosure comprises an ejection head having nozzles capable of ejecting ink toward a recording medium, a carriage that supports the ejection head and moves back and forth, a tank that stores the ink, a supply flow path that connects the tank to the ejection head and supplies the ink to the nozzles, a valve that is provided in the supply flow path and is capable of adjusting the opening of the supply flow path, and a controller, wherein the controller calculates, based on image data, a printing section, which is the position of the ejection head where the ink is ejected from the ejection head, and a non-printing section, which is the position of the ejection head where the ink is not ejected from the ejection head, for each pass, and controls the valve in an opening restriction section, which is at least a part of the non-printing section, so that the opening of the supply flow path is smaller than the opening of the valve in the printing section.

[0007] According to this configuration, it is possible to mitigate dynamic pressure, which is fluctuations in the internal pressure inside the ejection head caused by movement of the carriage, and to improve ejection stability. [Effects of the Invention]

[0008] The present disclosure provides an effect of improving ejection stability. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of a liquid ejection device according to a first embodiment. [Figure 2] 2 is a block diagram showing an example of a functional configuration of the liquid ejection device of FIG. 1. FIG. [Figure 3] 2 is a diagram showing an example of the configuration of a valve of the liquid ejection device of FIG. 1. [Figure 4] 2 is a flowchart showing an example of the operation of the liquid ejection device of FIG. [Figure 5] 1. FIG. 4 is a diagram showing the relationship between the position of the carriage, the opening degree of a supply flow path, and the speed of the carriage in the liquid ejection device of FIG. [Figure 6] 10A and 10B are diagrams illustrating other relationships between the position of the carriage of the liquid ejection device, the opening degree of the supply flow path, and the speed of the carriage. [Figure 7] 10A and 10B are diagrams illustrating still another relationship between the position of the carriage of the liquid ejection device, the opening degree of the supply flow path, and the speed of the carriage. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments. In addition, the same or corresponding elements will be denoted by the same reference numerals throughout the drawings, and redundant description will be omitted.

[0011] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0012] (Embodiment 1) FIG. 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100 according to the first embodiment.

[0013] The liquid ejection device 100 is a device that prints an image on a recording medium 110 using liquid ejected from an ejection head 4 based on image data. In the following, an inkjet printer that ejects ink of four colors, cyan, magenta, yellow, and black, will be described as the liquid ejection device 100.

[0014] The liquid ejection device 100 is a serial head type inkjet printer, and alternates between a step of ejecting ink to form an image on a recording medium 110 while the ejection head 4 moves (scans) in a main scanning direction, and a step of transporting the recording medium 110 in a sub-scanning direction. Note that, hereinafter, the direction in which the ejection head 4 moves back and forth is referred to as the first direction or main scanning direction, and a direction perpendicular to the first direction, which is the transport direction of the recording medium 110, is referred to as the second direction or sub-scanning direction. Furthermore, a direction perpendicular to both the first direction and the second direction is referred to as the third direction. The third direction is, for example, the up-down direction. In this way, the main scanning direction, the sub-scanning direction, and the third direction are perpendicular to each other, but this is not limited to this and they may intersect each other.

[0015] The ejection head 4 is housed in a housing 10 of the liquid ejection device 100. The ejection head 4 has a nozzle surface 40 in which a plurality of nozzles 41 capable of ejecting ink toward a recording medium 110 based on image data are formed. The nozzle surface 40 has nozzle rows in which the nozzles 41 are aligned in the sub-scanning direction, and a plurality of nozzle rows are arranged in the main scanning direction. For example, four nozzle rows are provided, one for each ink color. The ejection head 4 is also provided with a head drive unit 42 (see FIG. 2 ) for each nozzle 41. The head drive unit 42 includes a drive element, and when driven, applies pressure to the ink in the nozzle 41 to eject ink from the corresponding nozzle 41, thereby ejecting the ink from the nozzle 41. In this way, the ejection head 4 is capable of ejecting ink of a plurality of colors.

[0016] The ejection head 4 is also provided with ink supply ports 43 through which ink supplied from the outside flows in. An ink supply port 43 is provided for each ink color. The ink supply ports 43 and the nozzles 41 are connected by an internal head flow path 62 for each ink color, and the ink that flows into the ink supply ports 43 is supplied to the nozzles 41 through the internal head flow path 62.

[0017] The liquid ejection device 100 is equipped with a platen 11 disposed opposite the ejection head 4. The platen 11 is positioned below the ejection head 4 at a predetermined distance, and has a flat upper surface. The upper surface of the platen 11 supports the recording medium 110 from below.

[0018] Furthermore, the liquid ejection device 100 includes a transport unit 12 that transports the recording medium 110 on the platen 11 in the sub-scanning direction. The transport unit 12 includes, for example, two transport rollers 13 and a transport motor. The two transport rollers 13 extend in the main scanning direction and, when viewed from the third direction, are spaced apart in the sub-scanning direction so as to sandwich the platen 11 between them. Each transport roller 13 is connected to the rotating shaft of the transport motor via a reducer. Therefore, when the transport motor is driven, the two transport rollers 13 rotate around their axes, transporting the recording medium 110 on the platen 11 in the sub-scanning direction.

[0019] The liquid ejection device 100 also includes a reciprocating movement unit 2 that moves the ejection head 4 back and forth in the main scanning direction within a predetermined reciprocating movement range. The reciprocating movement unit 2 includes a carriage 21 that supports the ejection head 4 and moves back and forth in the main scanning direction together with the ejection head 4, and a carriage drive unit 22 that drives the carriage 21. The carriage drive unit 22 includes two guide rails 26, an endless belt 27, two pulleys 28, and a movement motor 29. When viewed from the third direction, the two guide rails 26 extend in the main scanning direction so as to cross the platen 11, and are spaced apart in the sub-scanning direction. The two guide rails 26 support the carriage 21 and guide it in the main scanning direction.

[0020] Two pulleys 28 are provided near both ends of one of the guide rails 26. An endless belt 27 is wound around the two pulleys 28. The carriage 21 is connected to a predetermined position on the endless belt 27. One of the pulleys 28 is connected to the rotation shaft of a movement motor 29 via a reducer. Therefore, when the movement motor 29 is driven, the endless belt 27 moves in a circular motion, and the carriage 21 supporting the ejection head 4 moves along the guide rail 26 in the main scanning direction.

[0021] The liquid ejection device 100 also includes tanks 3 that store ink to be supplied to the ejection heads 4. A tank 3 is provided for each ink color, and four tanks 3 are provided in the present disclosure. The tanks 3 are, for example, cartridge-type tanks, and are held at predetermined positions within the housing 10. Therefore, the ejection heads 4 move relative to the tanks 3 as the carriage 21 moves. The tanks 3 are covered by an openable cover provided on the housing 10. The tanks 3 can be attached to or detached from the liquid ejection device 100 by opening the cover.

[0022] The liquid ejection device 100 also includes a conduit 61 that connects the tank 3 and the ejection head 4 and supplies the ink stored in the tank 3 to the nozzles 41. The conduit 61 is, for example, a flexible resin tube, and when the distance between the carriage 21 and the tank 3 changes due to movement of the carriage 21, the conduit 61 flexes and deforms, maintaining the connection between the tank 3 and the ejection head 4. The conduit 61 is provided for each ink color, and in the ink flow direction, the upstream end is connected to the tank 3 of the corresponding ink color, and the downstream end is connected to the ink supply port 43 of the corresponding ink color of the ejection head 4. The conduit 61 has an upstream portion 61a that extends in a straight line to one side in the main scanning direction across the reciprocating movement range of the carriage 21, a curved portion 61b that is located downstream of the upstream portion 61a and extends while curving back, and a downstream portion 61c that is located downstream of the curved portion 61b and extends in a straight line to the other side in the main scanning direction, with its upstream end connected to the ink supply port 43 of the ejection head 4. When the carriage 21 moves, the downstream portion 61c moves in the main scanning direction in conjunction with the movement of the carriage 21, and the curved portion 61b is deformed by being pulled by the downstream portion 61c so as to move in the main scanning direction of the carriage 21. The conduit 61 and the intra-head flow path 62 form a supply flow path 5, and the supply flow path 5 supplies ink to the nozzles 41.

[0023] The supply flow channel 5 is provided with a valve 6 that can adjust the aperture of the supply flow channel 5. The aperture of the supply flow channel 5 and the valve 6 refers to the ratio of the aperture area of ​​the valve 6 when it is open or closed to the aperture area of ​​the valve 6 when it is fully open. FIG. 3 is a diagram showing an example of the configuration of the valve 6. In this embodiment, a valve 6 is provided for each ink color, and the aperture of the supply flow channel 5 can be adjusted for each ink color. The valve 6 is, for example, a solenoid valve, and as shown in FIG. 3, includes a valve element 65 and a valve driver. When closing the supply flow channel 5, the valve element 65 advances into the supply flow channel 5 to at least partially block the flow of ink through the supply flow channel 5. The aperture of the supply flow channel 5 can be adjusted by adjusting the degree to which the valve element 65 advances into the supply flow channel 5. The valve driver drives the valve element 65 based on an input control signal to adjust the aperture of the supply flow channel 5. The valve driver also controls the speed at which the aperture is adjusted based on the input control signal.

[0024] The liquid ejection device 100 also includes a thermometer 8 that can detect the temperature of the ink or the temperature of the atmosphere.

[0025] Fig. 2 is a block diagram showing the functional configuration of the liquid ejection device 100. As shown in Fig. 2, the liquid ejection device 100 includes a controller 7. The controller 7 includes, as a functional configuration mainly made up of hardware, a control unit 71, a storage unit 72 connected to the control unit 71, and an interface 73. The control unit 71 is also connected to the head drive unit 42, the transport unit 12, the reciprocating unit 2, the thermometer 8, and the valve 6 described above.

[0026] The control unit 71 is, for example, a computer, and includes a processor such as an MPU, or a circuit such as an integrated circuit such as an ASIC. The storage unit 72 is a memory accessible from the control unit 71, and includes, for example, RAM and ROM. The RAM temporarily stores image data and various data used during calculations by the control unit 71. The ROM stores computer programs and data for various data processing operations. Therefore, the control unit 71 controls the operation of each unit of the liquid ejection device 100 by executing the computer program while referencing the data stored in the storage unit 72.

[0027] The interface 73 is a connection device that connects the control unit 71 to devices external to the liquid ejection device 100. Examples of external devices include other computers, communication networks, recording media, displays, and other liquid ejection devices. The liquid ejection device 100 acquires image data and print setting information from external devices, such as computers, via this interface 73. This image data includes raster data that indicates an image to be printed on the recording medium 110 and has RGB value gradation information.

[0028] The head drive unit 42 has a nozzle drive circuit electrically connected to each drive element of the ejection head 4, and controls the operation of the drive elements of each nozzle 41 based on instructions from the control unit 71. That is, the control unit 71 outputs a control signal to the nozzle drive circuit to drive the drive elements, and the nozzle drive circuit generates a drive signal based on the input control signal and outputs this drive signal to each drive element. As a result, each drive element is driven based on the corresponding drive signal and operates to apply a predetermined ejection pressure to the ink in the nozzle 41 at a predetermined carriage position. Therefore, the ejection timing and size of the ink ejected from each nozzle 41 (volume of ink droplets) can be controlled.

[0029] The transport unit 12 has a transport drive circuit electrically connected to the transport motor described above, and the operation of the transport motor is controlled by the control unit 71 via the transport drive circuit. This allows the transport unit 12 to transport the recording medium 110 on the platen 11 intermittently or continuously in the forward and backward directions, and also to stop and hold the recording medium 110 at a predetermined position on the platen 11.

[0030] The reciprocating unit 2 has a movement drive circuit electrically connected to the movement motor 29 described above, and the operation of the movement motor 29 is controlled by the control unit 71 via the movement drive circuit. This allows the reciprocating unit 2 to move the carriage 21 supporting the ejection head 4 in the main scanning direction at any speed, and to stop the carriage 21 at any position within the reciprocating movement range AR. Therefore, the ejection head 4 mounted on the carriage 21 is moved back and forth in the main scanning direction (first direction) relative to the recording medium 110 by the reciprocating unit 2.

[0031] The valve 6 has a drive circuit electrically connected to a valve drive unit, and the operation of the valve drive unit is controlled by a control unit 71 via the drive circuit. The control unit 71 outputs a control signal including commands related to the opening and opening adjustment speed of the valve 6 to the drive circuit, and the drive circuit generates a drive signal based on the control signal. The valve drive unit operates based on the drive signal, and operates the valve element 65 so that the opening and opening adjustment speed of the valve 6 correspond to the commands.

[0032] The liquid ejection device 100 forms an image on the recording medium 110 in each pass by ejecting ink while moving the ejection head 4 using the reciprocating unit 2. That is, the liquid ejection device 100 transports the recording medium 110 using the transport unit 12 and stops it at a predetermined position on the platen 11. Next, the reciprocating unit 2 moves the ejection head 4 in one direction in the main scanning direction while ejecting ink to land on the recording medium 110. In this way, a partial image for one pass is formed on the stopped recording medium 110 by ink ejected while the ejection head 4 is moving. Then, after the partial image for one pass is formed, the recording medium 110 is transported again by the transport unit 12 a predetermined distance and stopped. Then, the reciprocating unit 2 moves the ejection head 4 in the other direction in the main scanning direction while ejecting ink, thereby forming a partial image for the next pass. The liquid ejection device 100 alternately repeats the transport of the recording medium 110 and the ejection of ink in this manner, thereby printing an entire image consisting of one or more partial images on the recording medium 110.

[0033] In addition to the above, the liquid ejection device 100 may also have, as functional hardware components, output devices such as a display and a speaker that output various types of information to the outside, and input devices such as a touch panel and a physical switch that accept input of information from the outside.

[0034] [Example of operation] Next, an example of the operation of the printing process of the liquid ejection device 100 will be described in detail.

[0035] Fig. 4 is a flowchart showing an example of the operation of the liquid ejection device 100 according to embodiment 1. Fig. 5 is a diagram showing the relationship between the position of the carriage 21, the opening degree of the supply flow path 5, and the speed of the carriage 21 according to embodiment 1.

[0036] First, the controller 7 starts the printing process by receiving a print job input, for example, from the interface 73. The print job includes image data including RGB values, and the image data is stored in the storage unit 72 (step S1).

[0037] When the controller 7 receives a print job, it performs halftone processing on the image data containing RGB values. This halftone processing generates print data for ejecting ink from the ejection head 4. This print data is data that expresses the color of each pixel represented in the original image data using ink of predetermined colors, such as cyan, yellow, magenta, and black. This halftone processing can employ known data conversion methods, such as dithering and error diffusion. Then, pass print data is generated from the print data, in which pass print data for one pass corresponding to a partial image to be formed on the recording medium 110 by ejecting ink from the ejection head 4 while the ejection head 4 is moved in one direction of the main scanning direction is arranged in pass printing order (step S2). The pass print data is data that indicates the drive mode of the head drive unit 42 for each position of the carriage 21 within the reciprocating movement range of the carriage 21.

[0038] Next, the controller 7 calculates, for each pass of the pass print data generated based on the image data, a print section S and a non-print section R within the reciprocating movement range of the carriage 21 (step S3). The non-print section R may be a section other than the print section S. In this case, only one of the non-print section R and the print section S may be explicitly calculated, and the other section may be implicitly treated as the other section. The print section S and non-print section R are calculated for each ink color. The print section S is a section indicating the position of the ejection head 4 that ejects ink from the ejection head 4. The non-print section R is a section indicating the position of the ejection head 4 that does not eject ink from the ejection head 4. In the column labeled "print section S" in FIG. 5, the print section S is indicated by a thick solid line, and the non-print section R is indicated by a dashed line. In this embodiment, the print section S is located in the middle of the reciprocating movement range AR of the carriage 21. The non-printing section R is set in a section other than the printing section S within the reciprocating movement range AR of the carriage 21, i.e., at both ends of the reciprocating movement range AR of the carriage 21. One end of the reciprocating movement range AR of the non-printing section R includes a non-printing acceleration section Ra, which is a section in which the carriage 21 accelerates, and the other end includes a non-printing deceleration section Rd, which is a section in which the carriage 21 decelerates. In this way, the non-printing acceleration section Ra, the printing section S, and the non-printing deceleration section Rd are aligned in one direction of the reciprocating movement of the carriage 21.

[0039] Next, the controller 7 sets an opening degree limiting section Rr. The opening degree limiting section Rr is a section in which the valve 6 is controlled so that the opening degree of the supply flow path 5 is smaller than the opening degree of the supply flow path 5 in the printing section S. The opening degree limiting section Rr is set for each ink color. The controller 7 sets at least a portion of the non-printing section R as the opening degree limiting section Rr (step S4). In the column labeled "opening degree limiting section" in FIG. 5, the opening degree limiting section Rr is indicated by a thick solid line. In this embodiment, the opening degree limiting section Rr is the same section as the non-printing section R. In this case, the controller 7 may not explicitly set the opening degree limiting section Rr, but may implicitly treat the non-printing section R as the opening degree limiting section Rr.

[0040] Next, the controller 7 controls the operations of the head drive unit 42, the transport unit 12, the reciprocating unit 2, and the valve 6 to execute the printing operation (step S5). First, the operation of the carriage 21 in the printing operation of one pass's worth of partial images made up of a single ink color will be described. At the start of the pass printing operation, the carriage 21 is positioned at one end of the reciprocating movement range AR. When the printing operation starts, the controller 7 accelerates the carriage 21 and moves the carriage 21 at a constant speed V1 in the printing section S. Then, when the carriage 21 approaches the other end of the reciprocating movement range AR, the controller 7 decelerates the carriage 21 and stops it at the other end of the reciprocating movement range AR.

[0041] Then, while moving the carriage 21, the controller 7 drives the head drive unit 42 in the printing section S to eject ink from the nozzles 41, thereby forming a partial image for one pass on the recording medium 110. In this way, the controller 7 cooperatively controls the reciprocating unit 2 and the head drive unit 42.

[0042] When the carriage 21 moves, the downstream portion 61c of the conduit 61 moves in the main scanning direction, and an inertial force acts on the ink in the conduit 61. At the same time, the movement of the carriage 21 deforms the curved portion 61b so that it moves in the main scanning direction of the carriage 21. These inertial forces and deformation of the conduit 61 cause pressure fluctuations in the conduit 61. If this pressure fluctuation propagates to the ejection head 4 and generates dynamic pressure, which is a fluctuation in the internal pressure of the nozzle 41 due to the movement of the carriage 21, in the ejection head 4, this can cause fluctuations in the amount of ink ejected from the nozzle 41 and ejection defects, resulting in a deterioration in the recorded image quality. The controller 7 of the liquid ejection device 100 controls the valve 6 during pass printing processing, and keeps the valve 6 fully open, i.e., the valve 6 is opened 100 percent, outside the opening limit section. Furthermore, when the carriage 21 is located in the aperture restriction section Rr, the controller 7 controls the valve 6 to make the aperture of the supply flow path 5 smaller than the aperture of the supply flow path 5 in the printing section S. As a result, during sections in which the carriage 21 is accelerating and decelerating, the valve 6 is controlled to make the aperture of the supply flow path 5 smaller, thereby suppressing the flow of ink in the conduit 61 caused by inertial force. As a result, fluctuations in the amount of ink ejected from the nozzles 41 and ejection failures can be prevented. The operation of the valve 6 will be described below.

[0043] As shown in FIG. 5 , when the carriage 21 is positioned at one end of the reciprocating movement range AR, the valve 6 is fully open. Then, when the controller 7 starts accelerating the carriage 21 to perform pass printing, it reduces the opening of the valve 6 at a predetermined adjustment speed. This operation of reducing the opening of the valve 6 is performed over a predetermined range from the start point of the non-printing acceleration section Ra. Then, while maintaining the reduced opening of the valve 6, as the end point of the non-printing acceleration section Ra approaches, the valve 6 is increased at a predetermined adjustment speed, and at the end point of the non-printing acceleration section Ra, the valve 6 is fully opened. This operation of increasing the opening of the valve 6 is performed over a predetermined range from the end point of the non-printing acceleration section Ra.

[0044] Then, in the printing section S, the controller 7 drives the head drive unit 42 while maintaining the speed V1, causing ink to be ejected from the nozzles 41. At this time, the valve 6 is fully open, allowing ink to be smoothly supplied to the nozzles 41. Also, in the printing section S, the controller 7 moves the carriage 21 at a constant speed V1, making it difficult for large dynamic pressure to be generated in the ejection head 4.

[0045] Then, when the carriage 21 leaves the printing section S and the controller 7 begins to decelerate the carriage 21, it reduces the opening of the valve 6 at a predetermined adjustment speed. This operation of reducing the opening of the valve 6 is performed over a predetermined range from the start of the non-printing deceleration section Rd. Then, while maintaining the reduced opening of the valve 6, as the end of the non-printing deceleration section Rd approaches, the controller 7 increases the opening of the valve 6 at a predetermined adjustment speed, until the valve 6 is fully open at the end of the non-printing deceleration section Rd. This operation of increasing the opening of the valve 6 is performed over a predetermined range from the end of the non-printing deceleration section Rd.

[0046] In this way, the controller 7 actively reduces the opening of the valve 6 in the non-printing acceleration section Ra and the non-printing deceleration section Rd based on the image data, thereby suppressing the dynamic pressure that occurs when the carriage 21 accelerates or decelerates.

[0047] Then, when the printing operation of the partial image for one pass is completed and the carriage 21 is positioned at the other end of the reciprocating movement range AR, the controller 7 temporarily stops the carriage 21 and transports the recording medium 110 by one pass. Then, the controller 7 executes the printing operation of the partial image for the next pass. In this printing operation, the movement direction of the carriage 21 is reversed.

[0048] The controller 7 controls the valve 6 so that it is partially closed rather than completely closed, and limits the opening of the valve 6 in the opening restriction section Rr to 50 percent. This makes it possible to suppress fluctuations in the internal pressure of the conduit 61 and deterioration of the ink caused by the opening and closing operation of the valve 6. Note that if the fluctuations in the internal pressure of the conduit 61 caused by the opening and closing operation of the valve 6 are small or if there is no concern about deterioration of the ink, the controller 7 may also fully close the valve 6. This makes it possible to effectively suppress the flow of ink in the conduit 61.

[0049] When a partial image for one pass is composed of multiple ink colors, the non-printing section R varies for each ink color depending on the image data. Furthermore, because the nozzle rows for each ink color are aligned in the main scanning direction, the position of the nozzle rows relative to the carriage position differs for each ink color. Therefore, due to this structure, the non-printing section R, which is based on the carriage position, differs for each ink color. The controller 7 controls the aperture of the valve 6 for each ink color, thereby controlling the valve 6 so that the aperture of the supply flow path 5 corresponding to the ink color is smaller than the aperture of the supply flow path 5 in the printing section S in the aperture restriction section Rr corresponding to the non-printing section R for each ink color. This allows the valve 6 to be closed sequentially, starting with the nozzle row for the ink color that has reached the aperture restriction section Rr, effectively suppressing the dynamic pressure generated in the ejection head 4.

[0050] In this way, the liquid ejection device 100 calculates the non-printing section R, in which ink is not ejected from the nozzles 41, based on image data, and actively reduces the opening of the valve 6 in the opening restriction section Rr corresponding to this non-printing section R, thereby suppressing pressure fluctuations in the conduit 61 caused by movement of the carriage 21. This makes it possible to improve ejection stability. Also, a damper built into the ejection head 4 can be omitted in order to absorb the dynamic pressure generated in the ejection head 4.

[0051] (Embodiment 2) In the first embodiment described above, a valve 6 is provided for each ink color. Then, in step S3, the controller 7 calculates a printing section S and a non-printing section R for each ink color. Then, in step S4, the controller 7 sets an opening limit section Rr for each ink color. Then, in step S5, the controller 7 controls the opening of the valve 6 for each ink color, and controls the valve 6 so that, in the opening limit section Rr for each ink color, the opening of the supply flow path 5 corresponding to that ink color is smaller than the opening of the supply flow path 5 in the printing section S.

[0052] On the other hand, in this embodiment, the valve 6 is a valve that can collectively adjust the aperture of multiple supply flow paths 5 provided for each ink color. Then, in step S3, the controller 7 calculates, based on image data for one pass, a printing section S within the one-way movement section in which at least one color of ink is ejected from the ejection head 4 and a non-printing section R in which ink is not ejected from the ejection head 4. Then, in step S4, the controller 7 sets at least a portion of the non-printing section R as an aperture restriction section Rr. Then, in step S5, the controller 7 controls the valve 6 so that the aperture of the valve 6 in the aperture restriction section Rr is smaller than the aperture of the valve 6 in the printing section S.

[0053] As a result, the openings of the plurality of supply flow paths 5 are collectively adjusted by the valves 6 to be smaller, thereby suppressing the dynamic pressure generated in the discharge head 4. In particular, during the section where the carriage 21 is accelerating and decelerating, where large dynamic pressure due to inertial force can be generated, the dynamic pressure generated in the discharge head 4 can be effectively suppressed with a simple configuration.

[0054] (Embodiment 3) FIG. 6 is a diagram showing the relationship between the position of the carriage 21, the opening degree of the supply flow path 5, and the speed of the carriage 21 according to the third embodiment.

[0055] In the first embodiment, as shown in FIG. 5, the controller 7 completes acceleration and deceleration of the carriage 21 in the non-printing section R, and ejects ink while moving the carriage 21 at a constant speed V1 in the printing section S.

[0056] On the other hand, in this embodiment, the controller 7 controls the carriage 21 so that printing starts while the carriage 21 is accelerating and ends after the carriage 21 starts to decelerate. That is, the controller 7 accelerates the carriage 21 not only in the non-printing section R but also in the sections at the beginning and end of the printing section S. Therefore, in order to enable ink to be ejected in the sections at the beginning and end of the printing section S, the controller 7 sets the opening degree limiting section Rr in step S4 so that a section within a predetermined range from the end point of the section in which the carriage 21 is accelerating and a section within a predetermined range from the start point of the section in which the carriage 21 is decelerating are outside the opening degree limiting section. Note that in the sections at the beginning and end of the printing section S, the dynamic pressure generated in the ejection head 4 is limited and has little effect on the recording image quality. Therefore, the printing section S can be extended while minimizing the effect on the recording image quality. In this embodiment, the controller 7 controls the carriage 21 so that both the section within a predetermined range from the end point of the section in which the carriage 21 accelerates, and the section within a predetermined range from the start point of the section in which the carriage 21 decelerates, are outside the opening degree restriction section Rr, but this is not limited to this, and either section may be outside the opening degree restriction section.

[0057] (Fourth embodiment) In the first embodiment, when the controller 7 changes the opening of the valve 6 in step S5, the speed at which the opening of the valve 6 is adjusted may be changed at a predetermined speed that differs for each ink color.

[0058] When the viscosity differs for each ink color or type, there will also be differences in fluctuations in the internal pressure of the conduit 61 caused by the opening and closing operation of the valve 6. By changing the adjustment speed of the valve 6 opening degree at a predetermined speed that differs for each ink color, it is possible to more effectively suppress fluctuations in the internal pressure of the conduit 61 caused by the opening and closing operation of the valve 6.

[0059] Furthermore, when changing the opening degree of the valve 6 in step S5, the controller 7 may change the speed at which the opening degree of the valve 6 is adjusted in accordance with the ink temperature detected by the thermometer 8 or the atmospheric temperature.

[0060] When the temperature of the ink or the temperature of the atmosphere differs, there will also be differences in the fluctuations in the internal pressure of the conduit 61 caused by the opening and closing operation of the valve 6. By changing the adjustment speed of the valve 6 opening degree at a predetermined speed that differs for each temperature, it is possible to more effectively mitigate the fluctuations in the internal pressure of the conduit 61 caused by the opening and closing operation of the valve 6.

[0061] (Embodiment 5) In the first embodiment, when the controller 7 changes the opening degree of the valve 6 in step S5, the controller 7 may set the opening degree of the valve 6 to a predetermined opening degree that differs for each ink color.

[0062] When the viscosity differs for each ink color or type, there will also be differences in the dynamic pressure generated in the ejection head 4. By setting the opening of the valve 6 to a predetermined opening that differs for each ink color, it is possible to effectively suppress the dynamic pressure generated in the ejection head 4 and improve ejection stability.

[0063] (Sixth embodiment) In the above-mentioned embodiment 1, the controller 7 may make the opening degree of the valve 6 in the opening degree limiting section Rr when the carriage 21 moves in one of the reciprocating directions different from the opening degree of the valve 6 in the opening degree limiting section Rr when the carriage 21 moves in the other of the reciprocating directions.

[0064] Due to the fact that the direction in which the inertial force acts differs when the carriage 21 moves in one direction and when it moves in the other direction, a difference also occurs in the internal pressure of the conduit 61. By varying the opening degree of the valve 6 when the carriage 21 moves in one direction and when it moves in the other direction, it is possible to appropriately suppress the dynamic pressure generated in the ejection head 4, and to improve ejection stability.

[0065] Furthermore, the controller 7 may adjust the opening of the valve 6 at a different speed when the carriage 21 moves in one of the reciprocating directions from the speed when the carriage 21 moves in the other direction. For example, the controller 7 may reduce the opening of the valve 6 at a first adjustment speed in a predetermined range from the start point of the opening limit section Rr when the carriage 21 moves in one of the reciprocating directions, and may reduce the opening of the valve 6 at a second adjustment speed different from the first adjustment speed in a predetermined range from the start point of the opening limit section Rr when the carriage 21 moves in the other of the reciprocating directions.

[0066] This makes it possible to appropriately suppress the dynamic pressure generated in the ejection head 4, as in the case where the opening degree is varied, and improves ejection stability.

[0067] (Embodiment 7) FIG. 7 is a diagram showing the relationship between the position of the carriage 21, the opening degree of the supply flow path 5, and the speed of the carriage 21 according to the seventh embodiment.

[0068] The dynamic pressure of the ejection head 4 differs between when the carriage 21 is accelerating and when it is decelerating, due to factors such as the fact that the direction in which the inertial force acts is different. For example, if the dynamic pressure generated in the ejection head 4 is lower when the carriage 21 is decelerating than when it is accelerating, as shown in FIG. 7 , in the first embodiment, the controller 7 may reduce the opening of the valve 6 at a first adjustment speed A1 in the opening limit section Rr of the non-printing acceleration section Ra, and reduce the opening of the valve 6 at a second adjustment speed A2 different from the first adjustment speed A1 in the opening limit section Rr of the non-printing deceleration section Rd. This allows the opening of the valve 6 to be gradually reduced during deceleration compared to during acceleration, thereby effectively suppressing fluctuations in the internal pressure of the conduit 61 and deterioration of the ink caused by the opening and closing operation of the valve 6.

[0069] (Embodiment 8) In the first embodiment described above, the controller 7 may execute a flushing process in which ink is ejected from the nozzles 41 in a section that includes the opening limit section Rr. The controller 7 executes the flushing process, for example, in the opening limit section Rr of the non-printing acceleration section Ra or the opening limit section Rr of the non-printing deceleration section Rd. Because the amount of ink ejected from the nozzles 41 during the flushing process is small, the flushing process in which ink is ejected from the nozzles 41 can be executed smoothly even when the valve 6 is closed and the supply of ink to the nozzles 41 is restricted. This reduces the time required for the printing operation for each pass.

[0070] (Embodiment 9) In the first embodiment, the valve 6 has the valve element 65 protruding into the supply flow path 5. However, the present invention is not limited to this. For example, the valve 6 may include a pressing member that compresses the pipe line 61. When the opening of the supply flow path 5 is to be reduced, the pipe line 61 may be compressed to reduce the opening area of ​​the pipe line 61. The valve 6 may also be provided inside the tank 3 or the discharge head 4 .

[0071] From the above description, many modifications and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present invention. [Explanation of symbols]

[0072] R Non-printing section S Printing Section 2. Reciprocating unit 3 Tank 4 Discharge head 5 Supply Channel 6 valves 7 Controller 41 nozzle 100 Liquid dispensing device 110 Recording medium

Claims

1. an ejection head having nozzles capable of ejecting ink toward a recording medium; a carriage that supports the ejection head and moves back and forth; a tank that contains the ink; a supply flow path that connects the tank and the ejection head and supplies the ink to the nozzles; a valve provided in the supply flow path and capable of adjusting an opening degree of the supply flow path; a controller; The controller A liquid ejection device that calculates, based on image data, a printing section, which is the position of the ejection head where the ink is ejected from the ejection head, and a non-printing section, which is the position of the ejection head where the ink is not ejected from the ejection head, for each pass, and controls the valve so that the opening of the supply flow path is smaller than the opening of the valve in the printing section in an opening restriction section, which is at least a part of the non-printing section.

2. The liquid ejection device according to claim 1 , wherein the controller controls the valve so that the valve is partially opened in the opening degree limiting section.

3. The liquid ejection device according to claim 1 , wherein the controller controls the valve so as to fully close the valve in the opening degree restricted section.

4. the ejection head is capable of ejecting ink of a plurality of colors, the tank, the nozzle, the supply flow path, and the valve are provided for each of the ink colors, 2. The liquid ejection device according to claim 1, wherein the controller calculates the printing section and the non-printing section for each ink color based on the image data for one pass, and controls the valve so that the valve opening in the opening restriction section for each ink color is smaller than the valve opening in the printing section.

5. the ejection head is capable of ejecting ink of a plurality of colors, the tank, the nozzle, and the supply flow path are provided for each ink color, the valve is capable of collectively adjusting the opening degrees of the plurality of supply flow paths provided for the respective ink colors, The liquid ejection device described in claim 1, wherein the controller calculates a printing period in which at least one color of ink is ejected from the ejection head and a non-printing period in which the ink is not ejected from the ejection head based on the image data for one pass, and controls the valve so that the opening degree of the valve in the opening degree limited period is smaller than the opening degree of the valve in the printing period.

6. a non-printing acceleration section, which is a section of the non-printing section in which the carriage is accelerated, the printing section, and a non-printing deceleration section, which is a section of the non-printing section in which the carriage is decelerated, are aligned along one direction of the reciprocating movement of the carriage, 2. The liquid ejection device according to claim 1, wherein the controller reduces the valve opening at a first adjustment speed in the opening limit section of the non-printing acceleration section, and reduces the valve opening at a second adjustment speed different from the first adjustment speed in the opening limit section of the non-printing deceleration section.

7. 2. The liquid ejection device of claim 1, wherein the controller reduces the opening of the valve at a first adjustment speed in a section of the opening restriction section from a starting point to a predetermined range when the carriage moves in one of the reciprocating directions, and reduces the opening of the valve at a second adjustment speed different from the first adjustment speed in a section of the opening restriction section from a starting point to a predetermined range when the carriage moves in the other of the reciprocating directions.

8. The liquid ejection device according to claim 1, wherein the controller differentiates the opening degree of the valve in the opening degree limiting section when the carriage moves in one of the reciprocating directions from the opening degree of the valve in the opening degree limiting section when the carriage moves in the other of the reciprocating directions.

9. a head driving unit that ejects the ink from the nozzles; The liquid ejection device according to claim 1 , wherein the controller executes a flushing process for ejecting the ink from the nozzles in a section that includes the opening degree limited section.

10. a thermometer capable of detecting the temperature of the ink or the temperature of the atmosphere; The liquid ejection device according to claim 1 , wherein the controller changes a speed at which the valve opening is adjusted in accordance with the temperature detected by the thermometer.

11. the ejection head is capable of ejecting ink of a plurality of colors, the tank, the nozzle, and the supply flow path are provided for each ink color, The liquid ejection device according to claim 1 , wherein the controller changes the adjustment speed of the valve opening for each ink color.

12. a carriage drive unit that drives the carriage, The liquid ejection device according to claim 1, wherein the controller sets at least one of a section within a predetermined range from an end point of the section in which the carriage is accelerated and a section within a predetermined range from a start point of the section in which the carriage is decelerated outside the opening degree limiting section.

13. an ejection head having nozzles capable of ejecting ink toward a recording medium; a carriage that supports the ejection head and moves back and forth; a tank that contains the ink; a supply flow path that connects the tank and the ejection head and supplies the ink to the nozzles; a valve provided in the supply flow path and capable of adjusting an opening degree of the supply flow path, Based on the image data, a printing section, which is a position of the ejection head where the ink is ejected from the ejection head, and a non-printing section, which is a position of the ejection head where the ink is not ejected from the ejection head, are calculated for each pass; A method for controlling a liquid ejection device, comprising: making the opening degree of the supply flow path smaller in an opening degree limited section that is at least a part of the non-printing section than in the printing section.

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