JP2021017006A - Liquid discharge device, liquid discharge method and program - Google Patents

Abstract

To provide a liquid discharge device that is able to prevent a decrease in image quality even if an air current occurs due to movement of a discharge head.SOLUTION: In a liquid discharge device 10, based on an interval, in a conveyance direction, between a first dot d1 formed by a small drop ejected from an upstream end nozzle 21u in a first path process and a second dot d2 formed by a small drop ejected from a downstream end nozzle 21d in a second path process, a control unit 42 sets a conveyance amount of a medium 3 on which recording is to be carried out in the conveyance direction. In a case where a third dot d3 formed by a third liquid drop, or a middle drop, from the upstream end nozzle 21u in a third path process and a fourth dot d4 formed by a fourth drop, or a middle drop, from the downstream end nozzle 21d in a fourth path process are adjacent to each other in the conveyance direction in image data, the control unit 42 changes at least one of the third drop and the fourth drop, or the middle drops, ejected in a recording process into a large drop.SELECTED DRAWING: Figure 2

Description

The present invention relates to a liquid discharge device, a liquid discharge method and a program.

As a conventional liquid ejection device, the print control apparatus of Patent Document 1 has an ejection head that moves in the main scanning direction while ejecting ink droplets from a nozzle. In this print control device, the ink droplets are ejected so that the subsequent ink droplets catch up with the earlier ink droplets and coalesce before the first ink droplets land on the print medium among the plurality of ink droplets continuously ejected. It is being discharged.

Japanese Patent No. 6197713

By the way, the position where the ink droplets land on the print medium may change due to the air flow generated by the movement of the ejection head. On the other hand, in the print control device of Patent Document 1, a plurality of ink droplets are combined to increase the weight, thereby preventing a change in the landing position due to an air flow.

Here, with respect to the same direction as the moving direction (main scanning direction) of the ejection head, the position of each ink droplet to be combined can be controlled by adjusting the ejection timing of the ink droplets. However, the airflow generated by the movement of the discharge head includes not only the airflow in the main scanning direction but also the airflow in the sub-scanning direction orthogonal to the main scanning direction. In this case, since it is difficult to adjust the ejection locus of the ink droplets in the sub-scanning direction, it is considered that a plurality of inks cannot be combined when an air flow in the sub-scanning direction is generated.

Further, even if a plurality of ink droplets can be combined, the combined ink droplets may not be spherical and may become long in the sub-scanning direction. Further, if the latter ink droplet hits the end of the earlier ink droplet, even if these are combined, the combined ink droplet may rotate and split, and the split ink droplet may land at a desired position. is there. In such a case, the image quality is deteriorated.

The present invention has been made to solve such a problem, and provides a liquid discharge device, a liquid discharge method, and a program capable of suppressing deterioration of image quality even when an air flow is generated due to the movement of the discharge head. It is intended to be provided.

The liquid discharge device according to an aspect of the present invention includes a discharge head having a plurality of nozzles, a scanning mechanism for moving the discharge head in the scanning direction, and a transport for moving the recording medium in a transport direction orthogonal to the scanning direction. The control unit includes a mechanism and a control unit, and the plurality of nozzles have an upstream end nozzle arranged at the upstream end in the transport direction and a downstream end nozzle arranged at the downstream end, and the control unit has an image. Based on the data, the recording process of forming dots on the recording medium by ejecting droplets having different liquid amounts from the nozzles while moving the ejection head in the scanning direction in one pass, and the subject. A pass process including a transfer process for moving the recording medium in the transfer direction is executed, and the control unit is formed by a first droplet of small droplets ejected from the upstream end nozzle in the first pass process. On the recorded medium formed by the first dot on the recorded medium and the second droplet of small droplets ejected from the downstream end nozzle in the second pass process following the first pass process. Based on the distance between the second dot and the second dot in the transport direction, the transport amount of the recording medium in the transport direction is set, and in the image data, the third liquid from the upstream end nozzle in the third pass processing. The third dot on the recording medium formed by the droplets and the third dot on the recording medium formed by the fourth droplet from the downstream end nozzle in the fourth pass processing following the third pass processing. When the four dots are adjacent to each other in the transport direction and the third droplet and the fourth droplet are both medium droplets having a larger amount of liquid than the small droplets, they are ejected in the recording process. At least one of the third droplet and the fourth droplet is converted from the middle droplet to a large droplet having a liquid volume larger than that of the middle droplet.

According to this, the transport amount in the transport direction is determined by the first interval between the first dot and the second dot formed by the droplets, respectively. In this case, the middle droplet having a larger amount of liquid than the small droplet is less affected by the air flow than the small droplet, so that the second interval between the first dot and the second dot formed by the middle droplet is the second. It will be larger than one interval.

On the other hand, the size of the dots is increased by changing the droplets forming at least one of the first dot and the second dot from medium droplets to large droplets. The enlarged dots can reduce the distance between the first dot and the second dot, and can suppress the deterioration of the image.

According to the present invention, it is possible to provide a liquid discharge device, a liquid discharge method, and a program capable of suppressing deterioration of image quality even when an air flow is generated due to the movement of the discharge head.

FIG. 1 is a schematic view showing a schematic configuration of a liquid discharge device according to a first embodiment of the present invention. FIG. 2 is a block diagram showing a functional configuration of the liquid discharge device of FIG. FIG. 3 is a cross-sectional view of the discharge head of FIG. FIG. 4 is a diagram schematically showing the relationship between the discharge surface of FIG. 1 and the dots discharged from the nozzle holes on the discharge surface. FIG. 5A is a diagram schematically showing the first dot and the second dot when the upstream end first dot and the downstream end second dot are narrower than a predetermined range, and FIG. 5B is an upstream diagram. FIG. 5C is a diagram schematically showing the first dot and the second dot when the first end dot and the second downstream end dot are wider than a predetermined range, and FIG. 5 (c) shows the first dot at the upstream end and the first dot at the downstream end. It is a figure which shows typically the 1st dot and the 2nd dot when 2 dots are a predetermined range. FIG. 6 is a flowchart showing an example of a transport amount setting process. 7 (a) to 7 (f) are diagrams schematically showing the third dot at the upstream end and the fourth dot at the downstream end. FIG. 8 is a flowchart showing an example of a liquid discharge method using the liquid discharge device of FIG. 9 (a) and 9 (b) are diagrams schematically showing the third dot at the upstream end and the fourth dot at the downstream end by the liquid discharge device according to the first modification. FIG. 10 is a block diagram showing a functional configuration of the liquid discharge device according to the second embodiment. FIG. 11 is a flowchart showing an example of a liquid discharge method using the liquid discharge device of FIG. FIG. 12 is a diagram schematically showing the upstream end third dot and the downstream end fourth dot by the liquid discharge device of FIG. FIG. 13 is a flowchart showing an example of a liquid discharge method using the liquid discharge device according to the modified examples 2 and 3.

(Embodiment 1)
<Outline configuration of image recording device>
As shown in FIG. 1, the image recording device 1 according to the first embodiment is a multifunction device having a printing function and an image input function, and includes a liquid discharge device 10 and an image input device 2. Details of the liquid discharge device 10 will be described later.

The image input device 2 is, for example, a scanner that reads an image by an image sensor. The image input device 2 generates image data (scan data) from the read image and stores it inside the image recording device 1. Alternatively, the image input device 2 prints the read image on the recording medium 3 supplied from the outside of the image recording device 1 by the liquid discharge device 10.

<Configuration of liquid discharge device>
The liquid discharge device 10 according to the first embodiment of the present invention is a device that discharges a liquid as shown in FIGS. 1 and 2. Hereinafter, an example in which the liquid ejection device 10 is applied to an inkjet printer that ejects a liquid such as ink will be described, but the liquid ejection device 10 is not limited thereto.

As shown in FIGS. 1 and 2, the liquid discharge device 10 adopts a serial head system, and includes a platen 11, a transfer mechanism 12, a scanning mechanism 13, a head unit 14, a storage tank 15, and a controller 40.

The head unit 14 has a carriage 14a, a discharge head 20, and one or more (for example, four) sub tanks 14b. The discharge head 20 and the four sub tanks 14b are mounted on the carriage 14a and reciprocate together with the carriage 14a in the scanning direction.

The discharge head 20 has a flow path forming body and a volume changing portion. A liquid flow path is formed inside the flow path forming body, and a plurality of nozzle holes 21a are opened on the lower surface (discharge surface 22a). The volume change section is driven to change the volume of the liquid flow path. At this time, in the nozzle hole 21a, the meniscus is displaced and vibrates, and liquid particles (droplets) are discharged. The details of the discharge head 20 will be described later.

The platen 11 is a flat plate member, and the recording medium 3 is arranged on the upper surface thereof. The platen 11 determines the distance between the recording medium 3 and the discharge head 20 provided so as to face the recording medium 3. The discharge head 20 side of the platen 11 is referred to as an upper side, and the opposite side is referred to as a lower side, but the arrangement of the liquid discharge device 10 is not limited to this.

The transport mechanism 12 has, for example, two transport rollers 12a and a transport motor 12b. The two transfer rollers 12a sandwich the platen 11 in the transfer direction and are arranged in parallel. The transfer motor 12b is connected to the transfer roller 12a. When the transfer motor 12b is driven, the transfer roller 12a rotates, and the recording medium 3 on the platen 11 is conveyed in the transfer direction. The transport direction is a direction that intersects (for example, orthogonally) with the scanning direction.

The scanning mechanism 13 has two guide rails 13a, a scanning motor 13b, an endless belt, and the like. The carriage 14a of the head unit 14 is supported by two guide rails 13a and is connected to an endless belt. When the scanning motor 13b is driven, the endless belt runs. At this time, the carriage 14a reciprocates in the scanning direction along the guide rail 13a.

The storage tank 15 is, for example, a removable cartridge, and is provided for each type of ink. For example, there are four storage tanks 15 that store black, yellow, cyan, and magenta inks, respectively. Each storage tank 15 is connected to the corresponding sub tank 14b via a tube, and ink is supplied to the nozzle hole 21a via the sub tank 14b.

The controller 40 is connected to each drive circuit that drives each unit, and controls the drive of each unit by outputting control data to each drive circuit. For example, the controller 40 is connected to the transfer motor drive circuit 16 that drives the transfer motor 12b, is connected to the scanning motor drive circuit 17 that drives the scanning motor 13b, and is connected to the actuator drive circuit 18 that drives the actuator 33 of the volume changing unit. It is connected.

As a result, the controller 40 performs the recording process of forming dots on the recording medium 3 by ejecting droplets having different amounts of liquid from the nozzle holes 21a while moving the ejection head 20 in the scanning direction, and the recording medium 3. The path process including the transfer process of transporting in the transport direction is executed. The printing process proceeds by alternately repeating the recording process and the transport process with the recording process and the transport process as one pass. The details of the controller 40 and each drive circuit will be described later.

<Discharge head configuration>
As shown in FIGS. 3 and 4, the discharge head 20 has a flow path forming body and a volume changing portion. The flow path forming body is a laminated body of a plurality of plates. The plurality of plates include a nozzle plate 22, a first flow path plate 23, a second flow path plate 24, a third flow path plate 25, a fourth flow path plate 26, and a fifth flow path plate 27, and are laminated in this order. Has been done.

Holes and grooves of various sizes are formed in each plate. In the laminated body in which each plate is laminated, holes and grooves are combined to form a plurality of flow paths. This flow path includes a plurality of nozzles 21, a plurality of individual flow paths (channels), and a manifold 29.

The nozzle 21 is formed so as to penetrate the nozzle plate 22 in the thickness direction thereof, and is open to the lower surface (discharge surface 22a) of the nozzle plate 22. The plurality of nozzles 21 have an upstream end nozzle 21u arranged at the upstream end in the transport direction and a downstream end nozzle 21d arranged at the downstream end.

The openings (nozzle holes 21a) of the plurality of nozzles 21 are arranged in the conveying direction to form a nozzle row, and the four nozzle rows are arranged in the scanning direction. Each nozzle row corresponds to inks of different colors (eg, black, yellow, cyan and magenta). The plurality of nozzles 21 may be arranged in a direction intersecting the transport direction. Further, the nozzle rows may be arranged in a direction intersecting the scanning direction.

The manifold 29 extends in the transport direction and has supply ports and return ports at both ends thereof. The supply port is connected to the sub tank 14b (FIG. 1) by the supply path, and the return port is connected to the sub tank 14b by the return path. As a result, the manifold 29 and the sub tank 14b form a circulation path.

The individual flow path reaches from the manifold 29 to the nozzle 21, and has a throttle flow path 30, a pressure chamber 31, and a communication flow path 32 between them, and these are connected in this order. Therefore, the pressure chamber 31 communicates with the nozzle 21.

In such a liquid flow path, the liquid flows from the sub tank 14b through the supply path and flows into the manifold 29 through the supply port. While the liquid is flowing through the manifold 29, a part of the liquid flows into the individual flow paths. The liquid flows through the throttle flow path 30, the pressure chamber 31, and the communication flow path 32 in this order in the individual flow paths, and flows into the nozzle 21. Further, the remaining liquid flows out from the manifold 29 through the return port, passes through the return path, and returns to the sub tank 14b.

The volume changing portion is arranged on the fifth flow path plate 27 and includes the actuator 33 and the diaphragm 34. The pressure chamber 31 is formed so as to penetrate the fifth flow path plate 27 in the thickness direction thereof. The diaphragm 34 is fixed on the fifth flow path plate 27 and covers the opening of the pressure chamber 31.

The actuator 33 is a piezoelectric element including a common electrode 33a, a piezoelectric layer 33b, and an individual electrode 33c, and is arranged on the diaphragm 34. The common electrode 33a covers the entire surface of the diaphragm 34, and the piezoelectric layer 33b is laminated on the common electrode 33a, and is provided on the piezoelectric layer 33b for each individual electrode 33c and pressure chamber 31. One actuator 33 is configured by the one individual electrode 33c, the common electrode 33a, and the partial piezoelectric layer 33b sandwiched between the two electrodes.

The individual electrode 33c is connected to the actuator drive circuit 18, and a drive signal from the actuator drive circuit 18 is applied. On the other hand, the common electrode 33a is always held at the ground potential.

In a state where no drive signal is applied to the individual electrodes 33c, the individual electrodes 33c and the common electrode 33a have the same potential. When the drive signal is applied to the individual electrodes 33c, the active portion of the piezoelectric layer 33b (the partial piezoelectric layer 33b sandwiched between the individual electrodes 33c and the common electrode 33a) expands and contracts in the plane direction together with the two electrodes 33a and 33c. The diaphragm 34 deforms in cooperation with the actuator 33 to change the volume of the pressure chamber 31. As a result, pressure is applied to the liquid in the pressure chamber 31. As a result, the meniscus of the nozzle hole 21a vibrates, and droplets are ejected from the nozzle hole 21a.

<Controller and drive circuit>
As shown in FIG. 2, the controller 40 includes a network interface (I / F41), a control unit 42, and a storage unit. Further, the drive circuit includes a transfer motor drive circuit 16, a scanning motor drive circuit 17, and an actuator drive circuit 18, which are electrically connected to the controller 40.

The I / F 41 receives various data such as image data from an external device 4 such as a computer, a camera, a network, and a recording medium. The image data indicates an image to be printed on the recording medium 3, and has color information and gradation information.

The storage unit is accessible from the control unit 42 and has a RAM 43 and a ROM 44. The RAM 43 temporarily stores various data. Examples of the various data include image data and data converted by the control unit 42.

The ROM 44 stores a computer program and a control program for performing various data processing. The computer program may be acquired from the external device 4 via the I / F 41.

The control unit 42 has an arithmetic processing unit such as a processor, and controls each unit by executing a computer program stored in the ROM 44. For example, the control unit 42 stores various data received by the I / F 41 and image data (scan data) from the image input device 2 in the RAM 43.

Further, the control unit 42 executes an image acquisition unit 42a, a data creation unit 42b, a setting unit 42c (setting means), a droplet conversion unit 42d (conversion means), and an execution unit 42e (execution means) by executing a computer program. Demonstrate the function of.

The image acquisition unit 42a acquires image data from the external device 4 via the I / F 41, or acquires image data (scan data) from the image input device 2. When this image data is data represented in the RGB color space, the image acquisition unit 42a converts this data into data represented in the CMYK color space. The image data has a gradation value of the image for each color.

The data creation unit 42b creates dot data from the image data obtained by the image acquisition unit 42a. For example, the data creation unit 42b creates dot data for each pixel from the gradation value of the image data for each color. The dot data has dot position information and dot size information, and is, for example, halftone. The dot size includes dots with a small dot size (small dot sd), dots larger than the small dot sd (medium dot md), dots larger than the medium dot md (large dot ld), and no dots formed. Have.

The droplet conversion unit 42d converts a droplet satisfying a predetermined condition in the droplet data based on the dot data by the data creation unit 42b. The conversion process of the droplet will be described later.

The droplet data defines the ejection of droplets for creating dots, and has a nozzle 21 for ejecting droplets, an ejection timing, and a liquid amount. The nozzle 21 for ejecting droplets is defined by the color of dots, the order of control data supplied from the control unit 42 to the actuator drive circuit 18, and the like.

The ejection timing is defined by the position of dots in the image formed on the recording medium 3, the speed of the ejection head 20 moving in the scanning direction, and the like. The speed of the discharge head 20 in this scanning direction is predetermined.

The amount of liquid is defined by the size of the dots. For example, the medium dot md is defined as a medium droplet having a predetermined volume (liquid volume), the small dot sd is defined as a small droplet having a liquid volume smaller than the medium droplet, and the large dot ld is defined as a medium droplet. Large droplets, which are droplets having a larger liquid volume than droplets, are defined, and no liquid volume is defined as no dots.

The setting unit 42c records the conveyed amount of the recording medium 3 in a predetermined area of the RAM 43 based on the positions of the dots formed on the recording medium 3 by the ejected droplets. The process of setting the transport amount will be described later. Further, the execution unit 42e generates control data for controlling each drive circuit based on the image data and the droplet data by the droplet conversion unit 42d, and outputs the control data to each drive circuit.

The transfer motor drive circuit 16 controls the drive of the transfer motor 12b based on the transfer motor control data from the execution unit 42e. At this time, the execution unit 42e refers to the processing area of the RAM 43, and the clock frequency period of the control unit 42 of several to several hundreds so that the recording medium 3 is conveyed by the transfer amount stored by the setting unit 42c. A command is output to the transfer motor drive circuit 16 each time. In response to this, the transfer motor 12b is driven.

The scanning motor drive circuit 17 controls the driving of the scanning motor 13b based on the scanning motor control data from the execution unit 42e. The actuator drive circuit 18 has a waveform generation circuit 18a, and controls the drive of the actuator 33 based on the actuator control data from the execution unit 42e. The waveform generation circuit 18a generates a drive signal of a voltage waveform indicating on / off of droplet ejection based on the droplet data by the droplet conversion unit 42d, and supplies the drive signal to the actuator 33.

<Transport volume setting process (setting step)>
As shown in FIG. 4, the movement of the discharge head 20 in the scanning direction generates an air flow flowing to the outside of the discharge head 20 in the transport direction. Due to this air flow, the droplets ejected from the nozzle 21 are flown in the transport direction, and the landing position (dot d formation position) of the droplets is displaced. Therefore, as shown in FIG. 5, the setting unit 42c transfers the amount of the recorded medium 3 in the transport process in the transport direction to the RAM 43 based on the distance between the first dot d1 and the second dot d2 in the transport direction. Record.

Here, the amount of deviation of the landing position of the droplet becomes larger as the amount of liquid in the droplet is smaller and as for the nozzle 21 at the end of the plurality of nozzles 21 arranged in the transport direction. Therefore, as the first dot d1, a dot on the recording medium 3 (upstream end first dot ud1) formed by the first droplet of small droplets ejected from the upstream end nozzle 21u in the first pass processing is used. .. Further, the second dot d2 is a dot (downstream end) on the recording medium 3 formed by the second droplet of small droplets ejected from the downstream end nozzle 21d in the second pass processing following the first pass processing. The second dot dd2) is used.

Specifically, for example, the transport amount is set according to the flowchart of FIG. This transport amount setting process is performed, for example, at any time such as every predetermined period, every maintenance, or a request by the user.

The execution unit 42e executes the first pass processing (step S1). In the first pass process, the first droplet of small droplets is ejected from the nozzle 21 while the ejection head 20 moves in the scanning direction. As shown in FIG. 5, the first droplets form the first dot d1 on the recording medium 3.

When the first droplet is ejected from each nozzle 21 at predetermined time intervals by the recording process in the first pass process, the first dots d1 are lined up in the scanning direction at predetermined intervals corresponding to the predetermined time. Further, in the transport direction, a plurality of first dots d1 by the first droplets ejected from the plurality of nozzles 21 in each nozzle row are lined up. The first image is formed on the recording medium 3 by the plurality of first dots d1 arranged in the scanning direction and the transport direction.

After that, the execution unit 42e performs the transfer process of the first pass process. As a result, the recording medium 3 is transported in the transport direction by the initial value or the previously set transport amount, and the first pass process is completed.

Subsequently, the execution unit 42e executes the second pass processing (step S2). In the recording process of the second pass process, the second droplet of small droplets is ejected from the nozzle 21 while the ejection head 20 moves in the scanning direction. The second droplet forms the second dot d2 on the recording medium 3. Here, as in the first pass processing, the second image is formed on the recording medium 3 by the plurality of second dots d2 arranged in the scanning direction and the conveying direction.

The second image is formed at a position moved from the first image by the amount of the recorded medium 3 transported in the first pass processing in the transport direction. Therefore, the first dot d1 (upstream end first dot ud1) formed by the first droplet ejected from the upstream end nozzle 21u in the first pass processing and the downstream end nozzle 21d ejected in the second pass processing. The positional relationship with the second dot d2 (downstream end second dot dd2) formed by the second droplet is determined by the amount of transport in the first pass processing.

Therefore, the image acquisition unit 42a reads the image including the first image and the second image by the image input device 2, and acquires the scan data of this image from the image input device 2 (step S3). The data creation unit 42b creates dot data from the scan data and acquires the dot positions of the first dot d1 and the second dot d2. The setting unit 42c calculates the interval (dot interval) between adjacent dot positions in the transport direction from each dot position of the first dot d1 and the second dot d2 (step S4).

Here, a plurality of first dots d1 and a plurality of second dots d2 are arranged in the transport direction. Therefore, there are a plurality of dot intervals between the first dots d1 adjacent to each other, between the second dots d2, and between the first dot ud1 and the second dot dd2. Therefore, the setting unit 42c may calculate all the dot spacing including the dot spacing of the upstream end first dot ud1 and the downstream end second dot dd2. Further, since the upstream end first dot ud1 and the downstream end second dot dd2 are arranged in the central region in the transport direction, the setting unit 42c sets the upstream end first dot ud1 and the downstream end dot ud1 and the downstream end first based on such positions. 2 dots dd2 may be specified and the dot interval may be calculated. Further, the first dot d1 and the second dot d2 are formed in different colors, and the setting unit 42c identifies the upstream end first dot ud1 and the downstream end second dot dd2 based on this color, and this dot The interval may be calculated.

The setting unit 42c determines whether or not the calculated dot spacing is within a predetermined range (step S5). The predetermined range is determined in consideration of the dot spacing corresponding to the nozzle 21 spacing in the transport direction and the amount of deviation of the dot position due to the air flow. That is, since the deviation amount is larger and the dot spacing is larger toward the end in the transport direction in each image, a predetermined range is predetermined by experiments, calculation formulas, and the like accordingly. The predetermined range may be specified from a predetermined calculation formula based on the amount of change in the dot spacing arranged in the transport direction.

For example, as shown in FIG. 5A, if the dot spacing is smaller than the predetermined range (step S5: NO), the conveyed amount is smaller than the appropriate value. In this case, the upstream end first dot ud1 and the downstream end second dot dd2 may overlap, or the distance between the upstream end first dot ud1 and the downstream end second dot dd2 may be much narrower than the other dot spacing. .. As a result, so-called black streaks BS are formed.

Therefore, the setting unit 42c obtains a correction value of the transport amount so as to increase the transport amount, and changes the correction value to the transport amount corrected by the correction value (step S6). Then, the process returns to the process of step S1 and the processes of steps S1 to S5 are performed. In the processes of steps S1 and S2, the recording medium 3 conveys the amount of transfer changed by the process of step S6. The correction value of the conveyed amount may be determined based on the difference between the dot interval and the predetermined range.

Further, as shown in FIG. 4B, if the dot spacing is larger than the predetermined range (step S5: NO), the conveyed amount is larger than the appropriate value. In this case, the upstream end first dot ud1 and the downstream end second dot dd2 are much larger than the other dot intervals, and the so-called white is formed between the upstream end first dot ud1 and the downstream end second dot dd2. Muscle WS is formed.

Therefore, the setting unit 42c obtains a correction value of the transport amount so as to reduce the transport amount, and changes the correction value to the transport amount corrected by the correction value (step S6). Then, the process returns to the process of step S1 and the processes of steps S1 to S5 are performed. Returning to the process of step S1, the processes of steps S1 to S5 are performed. In the processes of steps S1 and S2, the recording medium 3 conveys the amount of transfer changed by the process of step S6. The correction value of the conveyed amount may be determined based on the difference between the dot interval and the predetermined range.

On the other hand, as shown in FIG. 4C, if the dot spacing is within a predetermined range (step S5: YES), the conveyed amount is an appropriate value. Therefore, the setting unit 42c sets the transport amount in the first pass processing as the optimum transport amount (step S7).

As described above, in the setting process, if the dot spacing between the first dot d1 and the second dot d2 is not within a predetermined range, the first pass process and the second pass process in which the transport amount is changed are executed. If the dot spacing between the first dot d1 and the second dot d2 is within a predetermined range, the transport amount of the recording medium 3 in the transport process in the transport direction is set based on the spacing.

<Droplet conversion process (conversion step)>
Next, as described above, the transport amount of the recording medium 3 is set based on the interval of the small dots sd formed by the small droplets. In this case, since the deviation of the landing position of the large droplet due to the influence of the air flow is smaller than that of the small droplet, white streaks WS may occur. However, as shown in FIG. 7A, since the large dot ld formed by the large droplet is larger than the small dot sd, the distance between the upstream end first dot ud1 and the downstream end second dot dd2 is narrowed, and white. The generation of muscle WS is suppressed.

On the other hand, as shown in FIG. 7B, the deviation of the landing position of the middle drop due to the influence of the air flow is smaller than that of the small drop, and the middle dot md formed by the middle drop is smaller than that of the large dot ld. .. Therefore, white streaks WS may occur.

Therefore, the droplet conversion unit 42d sets a predetermined condition that the third dot d3 and the fourth dot d4 are adjacent to each other in the transport direction and the third and fourth droplets are both medium droplets based on the image data. Determine if it meets the requirements. When the predetermined condition is satisfied, at least one of the third droplet and the fourth droplet to be ejected in the recording process is converted from a medium droplet to a large droplet. As a result, the generation of white streaks WS is suppressed. The image data also includes dot data, droplet data, and the like created or converted based on the image data.

The third dot d3 is a dot (upstream end third dot ud3) formed on the recording medium 3 by the third droplet ejected from the upstream end nozzle 21u in the third pass processing. The fourth dot d4 is a dot formed on the recording medium 3 by the fourth droplet ejected from the downstream end nozzle 21d in the fourth pass processing executed after the third pass processing (downstream end fourth dot dd4). ). In the third pass process and the fourth pass process, the transfer process is executed with the transfer amount set by the above-mentioned transfer amount setting process.

Specifically, the third dot d3 shown in FIG. 7C is formed on the recording medium 3 by the third droplets ejected from each nozzle 21 in the third pass processing. The plurality of third dots d3 are arranged in the scanning direction by moving each nozzle 21 of the discharge head 20 in the scanning direction. Further, the plurality of third dots d3 are arranged in the transport direction because the plurality of nozzles 21 are arranged in the transport direction in the discharge head 20.

Similarly, the fourth dot d4 is formed on the recording medium 3 by the fourth droplet ejected from each nozzle 21 by the fourth pass processing. The plurality of fourth dots d4 by each nozzle 21 are arranged in the scanning direction, and the plurality of fourth dots d4 by each nozzle row are arranged in the conveying direction.

Therefore, among the plurality of third dots d3, the plurality of third dots d3 (upstream end third dot ud3) by the upstream end nozzle 21u are arranged in the scanning direction. Further, among the plurality of fourth dots d4, the plurality of fourth dots d4 (downstream end fourth dot dd4) by the downstream end nozzle 21d are arranged in the scanning direction.

The upstream end third dot ud3 and the downstream end fourth dot dd4 are small dot sd, medium dot md, or large dot ld, respectively. Therefore, the combination of the upstream end third dot ud3 and the downstream end fourth dot dd4 arranged in the transport direction is as follows: small dot sd, medium dot md, large dot ld, small dot sd and medium dot md, small dot sd. There are large dot ld, medium dot md and large dot ld.

Of these, when the combination of the upstream end third dot ud3 and the downstream end fourth dot dd4 adjacent to each other in the transport direction is medium dot md, the droplet conversion unit 42d uses the third dot d3 and the fourth dot d4. Are adjacent to each other in the transport direction, and it is determined that both the third droplet and the fourth droplet are medium droplets.

Here, the droplet conversion unit 42d creates droplet data based on the dot data and decomposes the droplet data for each path. As a result, for the droplets corresponding to the dots in the image to be printed, the nozzle 21 (ejection nozzle 21) for ejecting the droplets, the ejection timing of the droplets, and the amount of the droplets (liquid amount) can be obtained.

The droplet conversion unit 42d identifies the upstream end third dot ud3 from the discharge nozzle 21 based on the droplet data of the third pass processing, specifies the size of the upstream end third dot ud3 from the liquid amount, and discharge timing. The position of the third dot ud3 at the upstream end is specified from. Further, the droplet conversion unit 42d identifies the downstream end 4th dot dd4 from the discharge nozzle 21 based on the droplet data of the 4th pass processing, and specifies the size of the downstream end 4th dot dd4 from the liquid amount. The position of the fourth dot dd4 at the downstream end is specified from the discharge timing. Then, it is determined from the position of the upstream end third dot ud3 and the position of the downstream end fourth dot dd4 whether or not they are adjacent to each other.

Here, the droplet conversion unit 42d is at the same position in the scanning direction among the plurality of upstream end third dot ud3 and the plurality of downstream end fourth dot dd4 arranged in the scanning direction, and each other in the transport direction. Regarding the combination of the upstream end 3rd dot ud3 and the downstream end 4th dot dd4 that do not sandwich the other upstream end 3rd dot ud3 or the downstream end 4th dot dd4, it is determined that they are adjacent to each other in the transport direction. To do. Therefore, the upstream end third dot ud3 and the downstream end fourth dot dd4 adjacent to each other in the transport direction may overlap each other, may be in contact with each other, or may be separated from each other.

Then, the droplet conversion unit 42d receives at least one of a third droplet ejected from the upstream end nozzle 21u in the third pass processing and a fourth droplet ejected from the downstream end nozzle 21d in the fourth pass processing. Converts droplets from medium to large droplets.

As a result, as shown in FIG. 7D, the third droplet remains as a medium drop and the fourth droplet is converted from a medium drop to a large drop. As a result, the 4th dot dd4 at the downstream end increases from the medium dot md (FIG. 7B) to the large dot ld, the distance between the 3rd dot ud3 at the upstream end and the 4th dot dd4 at the downstream end becomes narrower, and the white streaks WS Is suppressed.

Further, as shown in FIG. 7 (e), when the third droplet is converted from the middle drop to the large drop while the fourth droplet remains as the middle drop, the upstream end third dot ud3 becomes the middle dot md (FIG. 7 (FIG. 7). b)) increases from) to large dot ld. As a result, the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 is narrowed, and the generation of white streaks WS is suppressed.

Further, as shown in FIG. 7 (f), both the third droplet and the fourth droplet are converted from medium droplets to large droplets. As a result, the upstream end third dot ud3 and the downstream end fourth dot dd4 increase from the medium dot md (FIG. 7 (b)) to the large dot ld, and the upstream end third dot ud3 and the downstream end fourth dot dd4 become larger. The interval is narrowed, and the occurrence of white streaks WS is suppressed.

<Liquid discharge method>
The liquid discharge method according to the embodiment is performed by the control unit 42 executing a computer program for operating the liquid discharge device 10 according to the flowchart shown in FIG.

The setting unit 42c of the control unit 42 sets the transport amount of the recording medium 3 by, for example, the setting process shown in the flowchart of FIG. 6 (step S10). The execution unit 42e of the control unit 42 controls the transfer motor 12b by outputting the transfer motor control data of the set transfer amount to the transfer motor drive circuit 16. The transport amount setting process in step S10 may be performed at a predetermined timing or an arbitrary timing without performing each of the droplet conversion processes in steps S11 to S15 described later.

The image acquisition unit 42a acquires image data from the external device 4 or the image input device 2, and temporarily stores the image data in the RAM 43 (step S11). The image acquisition unit 42a appropriately performs image processing on the acquired image data to create image data having gradation values for each color.

Next, the data creation unit 42b creates dot data from the image data obtained by the image acquisition unit 42a (step S12), and stores the dot data in the RAM 43. The dot data defines the position and size of dots in the image formed by the image data.

The droplet conversion unit 42d decomposes the dot data for each pass and creates the droplet data corresponding to the dots (step S13). The droplet conversion unit 42d determines a predetermined condition based on the ejection nozzle 21, ejection timing, and liquid amount of the droplet data (step S14). The predetermined conditions are a third droplet in which the upstream end third dot ud3 and the downstream end fourth dot dd4 are adjacent to each other in the transport direction and form the upstream end third dot ud3, and the downstream end fourth liquid. The drops are medium drops.

If the droplet conversion unit 42d satisfies the predetermined conditions (step S14: YES), the droplet conversion unit 42d transfers one of the third droplet and the fourth droplet to be ejected in the recording process from medium droplet to large droplet. And the converted droplet data is stored in the RAM 43 (step S15). Here, the other droplet is maintained as a medium droplet. However, the other droplet may also be converted from a medium droplet to a large droplet.

On the other hand, if the droplet conversion unit 42d does not satisfy the predetermined conditions (step S14: NO), the droplet conversion unit 42d stores the droplet data in the RAM 43.

The execution unit 42e generates actuator control data based on the droplet data and outputs the actuator control data to the actuator drive circuit 18. The actuator drive circuit 18 supplies a drive signal to the actuator 33 from the waveform generation circuit 18a based on the actuator control data. As a result, the actuator 33 is driven to eject droplets from the nozzle 21 corresponding to the actuator 33.

Further, the execution unit 42e generates scanning motor control data from the image data and outputs the scanning motor control data to the scanning motor drive circuit 17. Further, the execution unit 42e generates transfer motor control data from the transfer amount and image data from the setting unit 42c and outputs the transfer motor control data to the transfer motor drive circuit 16. As a result, pass processing including recording processing and transfer processing is executed, and printing is performed.

As described above, in the image data (for example, droplet data), the control unit 42 uses the third dot d3 on the recording medium 3 formed by the third droplet from the upstream end nozzle 21u in the third pass processing. And the fourth dot d4 on the recording medium 3 formed by the fourth droplet from the downstream end nozzle 21d in the fourth pass processing following the third pass processing are adjacent to each other in the transport direction and When both the third droplet and the fourth droplet are medium droplets having a larger liquid volume than the small droplet, at least one of the third droplet and the fourth droplet to be ejected in the recording process is selected. Converts from a medium drop to a large drop with a larger amount of liquid than the medium drop. As a result, even when an air flow is generated in the transport direction due to the movement of the discharge head 20 in the scanning direction, it is possible to suppress deterioration of print quality such as white streaks WS due to misalignment of the landing position of the middle droplet.

<Modification example 1>
In the liquid discharge device 10 according to the first modification, the control unit 42 is formed by the third dot d3 formed by the third droplet which is a middle drop and the fourth droplet which is a middle drop in the image data. When the fourth dot d4 forms a pair adjacent to each other in the transport direction and a plurality of sets are continuous in the scanning direction, the third dot d3 and the fourth dot d4 forming the respective sets to be ejected in the recording process. Converts a droplet of one of the dots from a medium droplet to a large droplet.

Specifically, in FIG. 7C, in the rows of the plurality of upstream end third dots ud3 arranged in the scanning direction and the rows of the plurality of downstream end fourth dots dd4 arranged in the scanning direction, the small dots sd and the middle are medium. Dot md and large dot ld are arranged. Therefore, a plurality of sets of the upstream end third dot ud3 of the middle dot md and the downstream end fourth dot dd4 of the middle dot md that are adjacent to each other in the transport direction are not continuous in the scanning direction. Therefore, the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 does not extend linearly in the scanning direction, and this distance is inconspicuous.

On the other hand, in FIG. 7B, a plurality of sets of the third dot ud3 at the upstream end of the middle dot md and the fourth dot dd4 at the downstream end of the middle dot md are continuous in the scanning direction. In this case, since the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 extends linearly in the scanning direction, the distance is easily noticeable.

Therefore, the droplet conversion unit 42d creates droplet data based on the dot data and decomposes the droplet data for each path. The droplet conversion unit 42d identifies the upstream end third dot ud3 and the downstream end fourth dot dd4 from the discharge nozzle 21 based on the droplet data of the third pass processing and the fourth pass processing, respectively, and from the liquid volume thereof. Each dot size is specified, and each dot position is specified from the ejection timing. Further, in the droplet conversion unit 42d, from the position of the upstream end third dot ud3 and the position of the downstream end fourth dot dd4 of the middle dot md, the upstream end third dot ud3 and the downstream end fourth dot dd4 of the middle dot md are It is determined whether or not the pairs are adjacent to each other, and whether or not a plurality of pairs are continuous in the scanning direction.

Then, in the droplet conversion unit 42d, if a plurality of sets of middle dots md of the upstream end third dot ud3 and the downstream end fourth dot dd4 are continuous in the scanning direction, the upstream end third dot ud3 in this set At least one of the third droplet forming the above and the fourth droplet forming the downstream end fourth dot dd4 is converted from a medium droplet to a large droplet.

For example, as shown in FIG. 7D, the fourth droplet forming the downstream end fourth dot dd4 may be converted from a medium droplet to a large droplet. Further, as shown in FIG. 7E, the third droplet forming the upstream end third dot ud3 may be converted from a medium droplet to a large droplet. Further, as shown in FIG. 7 (f), both the third droplet forming the upstream end third dot ud3 and the fourth droplet forming the downstream end fourth dot dd4 are converted from medium droplets to large droplets. You may. As a result, the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 is narrowed, and this distance can be made inconspicuous.

Further, as shown in FIG. 9A, the droplet forming at least one of the set of the upstream end third dot ud3 and the downstream end fourth dot dd4 is converted from a medium droplet to a large droplet. You may. That is, a plurality of sets continuous in the scanning direction maintain the upstream end third dot ud3 as a middle drop, and convert the downstream end fourth dot dd4 from a medium drop to a large drop, the upstream end third dot ud3. A set that converts from a medium drop to a large drop and keeps the 4th dot dd4 at the downstream end as a medium drop, and a set that converts both the 3rd dot ud3 at the upstream end and the 4th dot dd4 at the downstream end from a medium drop to a large drop. Have at least two of them.

As a result, the pair of the medium dot md and the large dot ld, the pair of the large dot ld and the medium dot md, and the pair of the large dot ld and the large dot ld are arranged in the scanning direction. Therefore, the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 is narrowed, and the distance does not extend linearly, so that the distance can be made inconspicuous.

Further, as shown in FIG. 9B, the droplet conversion unit 42d converts the droplet forming a dot of any one of the set of the upstream end third dot ud3 and the downstream end fourth dot dd4. It may be converted from a medium drop to a large drop so that the large dots ld formed by the subsequent large drops are arranged in a dusty pattern. As a result, the pair of the medium dot md and the large dot ld and the pair of the large dot ld and the medium dot md are alternately arranged in the scanning direction. Therefore, the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 is narrowed, and the distance does not extend linearly, so that the distance can be made inconspicuous.

(Embodiment 2)
As shown in FIG. 10, the liquid discharge device 10 according to the second embodiment further includes a switching unit 42f in addition to each configuration of the liquid discharge device 10 according to the first embodiment. The switching unit 42f switches between a normal mode and an eco mode in which the amount of droplets is reduced as compared with the normal mode. The switching unit 42f is realized as a function by the control unit 42 executing a computer program.

The mode switching request between the normal mode and the eco mode may be included in the image information or the setting information acquired from the external device 4 or the image input device 2, or the key button or the like provided in the liquid discharge device 10. It may be input by the user operating the input device 19. The switching unit 42f switches the mode in response to the mode switching request.

When the normal mode is set by mode switching by the switching unit 42f, as described above, in the droplet conversion unit 42d, the upstream end third dot ud3 and the downstream end fourth dot dd4, which are adjacent to each other in the transport direction, are both medium dots. A predetermined condition which is md is determined. When the predetermined conditions are satisfied, the droplet conversion unit 42d converts the droplet forming at least one of the dots of the upstream end third dot ud3 and the downstream end fourth dot dd4 from medium droplets to large droplets. .. As a result, the occurrence of white streaks WS is suppressed.

On the other hand, when the eco-mode is set by the mode switching by the switching unit 42f, in the droplet conversion unit 42d, the upstream end third dot ud3 and the downstream end fourth dot dd4, which are adjacent to each other in the transport direction, are both medium dot md. Judge a certain predetermined condition. When the predetermined conditions are satisfied, the droplet conversion unit 42d converts the droplet forming one dot of the upstream end third dot ud3 and the downstream end fourth dot dd4 from a medium drop to a large drop, and the other. Converts the droplets that form the dots from medium droplets to small droplets. As a result, the consumption of droplets can be reduced and energy saving can be realized.

The liquid discharge method is performed, for example, by the control unit 42 executing a computer program for operating the liquid discharge device 10 according to the flowchart shown in FIG. The processing of steps S20 to S23 of FIG. 11 is executed after the processing of step S14 of FIG. Since the processing of steps S10 to S15 of FIG. 11 is the same as that of FIG. 8, the description thereof will be omitted.

If the droplet conversion unit 42d satisfies the predetermined conditions (step S14: YES), the droplet conversion unit 42d determines whether or not the switching unit 42f has switched to the eco mode (step S20). Here, if the eco mode is not set (step S20: NO), the normal mode is set.

Therefore, the droplet conversion unit 42d converts one of the third droplet and the fourth droplet to be ejected in the recording process from a medium droplet to a large droplet, and converts the converted droplet data into the RAM 43. Store (step S15). As a result, at least one of the upstream end third dot ud3 and the downstream end fourth dot dd4 becomes a large dot ld. Here, the other droplet is maintained as a medium droplet. However, the other droplet may also be converted from a medium droplet to a large droplet.

On the other hand, if the eco mode is set (step S20: YES), the droplet conversion unit 42d changes one of the third droplet and the fourth droplet to be ejected in the recording process from a medium droplet to a large droplet. It is converted, the other droplet is converted from a medium droplet to a small droplet, and the converted droplet data is stored in the RAM 43 (step S21). As a result, one of the upstream end third dot ud3 and the downstream end fourth dot dd4 becomes a large dot ld, and the other dot becomes a small dot sd.

Further, the droplet conversion unit 42d has the third dot ud3 and the middle dot md at the upstream end of the middle dot md adjacent to each other in the transport direction based on the droplet data created in step S13 before conversion in step S15 or S21. It is determined whether or not a plurality of sets of the fourth dot dd4 at the downstream end of the above are continuous in the scanning direction (step S22).

Here, when a plurality of sets are not continuous (step S22: NO), the droplet data obtained by converting the droplets in steps S15 or S21 is stored in the RAM 43. In this case, since the distance between the third dot ud3 at the upstream end of the middle dot md and the fourth dot dd4 at the downstream end of the middle dot md does not extend linearly, the distance is not noticeable.

On the other hand, when a plurality of sets are continuous (step S22: YES), large dots ld and small dots sd are alternately alternated in the scanning direction in the continuous sets based on the droplet data obtained by converting the droplets in step S21. , The droplets are converted so as to form a dusty array, and the converted droplet data is stored in the RAM 43 (step S23).

As a result, as shown in FIG. 12, pairs of small dots sd and large dots ld and pairs of large dots ld and small dots sd are alternately arranged in the scanning direction. Therefore, by changing the middle dot md to the small dot sd, the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 becomes large, but the distance does not extend linearly, so the distance is conspicuous. It can be difficult.

<Modification 2>
As shown in FIG. 10, the liquid discharge device 10 according to the modified example 2 has a paper type acquisition unit 42g for acquiring the paper type of the recording medium 3 in addition to each configuration of the liquid discharge device 10 according to the second embodiment. Is further equipped. The liquid discharge device 10 according to the second modification does not have to include the switching unit 42f.

The paper type is the type of paper that is the recording medium 3, and is classified into the degree of spread of droplets that have landed on the paper according to the type of paper material, surface treatment, and the like. The correspondence between the paper type and the spread degree of the droplets is preset and stored in the ROM 44. For example, the degree of spreading has at least a degree in which the droplets are easy to spread (relatively easy to spread) and a degree in which the droplets are relatively difficult to spread (relatively difficult to spread) than the degree in which the droplets are easy to spread. ing.

The paper type acquisition unit 42g is realized as a function by the control unit 42 executing a computer program. The paper type may be included in the image information or setting information acquired from the external device 4 or the image input device 2, or is input by the user operating the input device 19 provided in the liquid discharge device 10. You may. Further, the paper type may be detected by the paper type detecting unit 50 provided in the liquid ejection device 10. The paper type detection unit 50 is, for example, a sensor having a light emitting element and a light receiving element, and outputs the detected paper type to the paper type acquisition unit 42g. The paper type acquisition unit 42g acquires the paper type from this, and determines the degree of spread of the droplets from a predetermined correspondence relationship based on the paper type.

When the droplet conversion unit 42d converts a droplet of one of the third dot d3 and the fourth dot d4 from a medium droplet to a large droplet in the recording process, the droplet landing on the recording medium 3 is generated. For a paper type that is relatively difficult to spread, the droplets of the other dot are maintained as medium droplets, while the control unit 42 is a paper type in which the droplets that land on the recording medium 3 are relatively easy to spread. The other dot droplet is converted from a medium droplet to a small droplet.

For example, the liquid discharge method is executed according to the flowchart of FIG. The process of step S24 of FIG. 13 is executed after the process of step S20 of FIG. Since the processes of steps S10 to S15 and S20 to S23 of FIG. 13 are the same as those of FIG. 11, the description thereof will be omitted. If the liquid discharge device 10 according to the second modification does not include the switching unit 42f, the process of S20 may be omitted, and the process of S24 may be executed after the process of S14.

If the eco-mode is not set by the switching unit 42f (step S20: NO), the droplet conversion unit 42d determines whether or not the paper type acquired by the paper type acquisition unit 42g is relatively easy to spread (step S20: NO). Step S24).

Here, based on a predetermined correspondence relationship between the predetermined paper type and the degree of spread, if the paper type is relatively difficult to spread (step S24: NO), the droplet conversion unit 42d ejects the paper in the recording process. Either one of the third droplet and the fourth droplet is converted from a medium droplet to a large droplet, and the converted droplet data is stored in the RAM 43 (step S15). Here, the other droplet is maintained as a medium droplet. However, the other droplet may also be converted from a medium droplet to a large droplet.

As a result, even in a paper type in which droplets are difficult to spread, at least one of the upstream end third dot ud3 and the downstream end fourth dot dd4 becomes a large dot ld. Therefore, the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 can be made inconspicuous.

On the other hand, if the paper type is relatively easy to spread (step S24: YES), the droplet conversion unit 42d drops one of the third droplet and the fourth droplet ejected in the recording process as medium droplets. Is converted into a large droplet, the other droplet is converted from a medium droplet to a small droplet, and the converted droplet data is stored in the RAM 43 (step S21).

As a result, one of the upstream end third dot ud3 and the downstream end fourth dot dd4 becomes a large dot ld, and the other dot becomes a small dot sd. In this way, even if the small dots sd are formed, the landed droplets spread widely on the recording medium 3, so that the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 can be made inconspicuous. ..

<Modification example 3>
The liquid discharge device 10 according to the third modification further includes a paper grain acquisition unit 42h for acquiring the paper grain of the recording medium 3 in addition to each configuration of the liquid discharge device 10 according to the second embodiment. The liquid discharge device 10 according to the second modification does not have to include the switching unit 42f.

The grain is the direction in which the fibers of the paper, which is the recording medium 3, extend. For example, in the paper arranged on the platen 11, the fibers extend in the transport direction (vertical grain) or the scanning direction (horizontal grain). Paper is classified according to the degree of spread of droplets landing on the paper according to the grain of the paper. The correspondence between the grain and the spread degree of the droplets is preset and stored in the ROM 44. For example, the degree of spreading has at least a degree in which the droplets are easy to spread (relatively easy to spread) and a degree in which the droplets are relatively difficult to spread (relatively difficult to spread) than the degree in which the droplets are easy to spread. ing.

The paper grain acquisition unit 42h is realized as a function by the control unit 42 executing a computer program. The paper grain may be included in the image information or setting information acquired from the external device 4 or the image input device 2, or is input by the user operating the input device 19 provided in the liquid discharge device 10. You may. Further, the paper grain may be detected by the paper grain detection unit 51 provided in the liquid discharge device 10. The paper grain detection unit 51 is, for example, a sensor having a light emitting element and a light receiving element, and outputs the detected paper grain to the paper grain acquisition unit 42h.

The paper grain acquisition unit 42h acquires the paper grain from this, determines the paper grain with respect to the transport direction (vertical grain parallel to the transport direction, or horizontal grain perpendicular to the transport direction), and based on this, from a predetermined correspondence relationship. Determine the extent of droplet spread.

When the droplet conversion unit 42d converts a droplet of one of the third dot d3 and the fourth dot d4 from a medium droplet to a large droplet in the recording process, the droplet landing on the recording medium 3 is generated. For a paper grain that is relatively difficult to spread, the droplet of the other dot is maintained as a medium drop, while the control unit 42 keeps the droplet that has landed on the recording medium 3 relatively easy to spread. The other dot droplet is converted from a medium droplet to a small droplet.

For example, the liquid discharge method is executed according to the flowchart of FIG. Since the processing other than the processing in step S24 is the same as the modification 2, the description thereof will be omitted.

If the eco-mode is not set by the switching unit 42f (step S20: NO), the droplet conversion unit 42d determines whether or not the paper grain acquired by the paper grain acquisition unit 42h is relatively easy to spread (step S20: NO). Step S24).

Here, based on a predetermined correspondence relationship between the predetermined paper grain and the degree of spread, if the paper grain is relatively difficult to spread (step S24: NO), the droplet conversion unit 42d discharges in the recording process. Either one of the third droplet and the fourth droplet is converted from a medium droplet to a large droplet, and the converted droplet data is stored in the RAM 43 (step S16). Here, the other droplet is maintained as a medium droplet. However, the other droplet may also be converted from a medium droplet to a large droplet. As a result, at least one of the upstream end third dot ud3 and the downstream end fourth dot dd4 becomes a large dot ld, so that the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 is increased. It can be made inconspicuous.

On the other hand, if the grain is relatively easy to spread (step S24: YES), the droplet conversion unit 42d drops one of the third droplet and the fourth droplet ejected in the recording process as medium droplets. Is converted into a large droplet, the other droplet is converted from a medium droplet to a small droplet, and the converted droplet data is stored in the RAM 43 (step S21).

As a result, one of the upstream end third dot ud3 and the downstream end fourth dot dd4 becomes a large dot ld, and the other dot becomes a small dot sd. In this way, even if the small dots sd are formed, the landed droplets spread widely on the recording medium 3, so that the distance between the upstream end third dot ud3 and the downstream end fourth dot dd4 can be made inconspicuous. ..

In addition, all the above-described embodiments may be combined with each other as long as the other party is not excluded from each other. For example, in the liquid discharge device 10 of the modification 2, the droplet conversion process of the modification 3 may be further performed.

Also, from the above description, many improvements and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed only as an example and is provided for the purpose of teaching those skilled in the art the best aspects of carrying out the present invention. The details of its structure and / or function can be substantially changed without departing from the spirit of the present invention.

The present invention can be applied to a liquid discharge device, a liquid discharge method, and a program capable of suppressing deterioration of image quality even when an air flow is generated due to the movement of the discharge head.

3: Recording medium 10: Liquid discharge device 12: Conveyance mechanism 13: Scanning mechanism 20: Discharge head 21: Nozzle 21d: Downstream end nozzle 21u: Upstream end nozzle 42: Control unit 42f: Switching unit 42g: Paper type acquisition unit ( Acquisition department)
42h: Paper grain acquisition section (acquisition section)

Claims (9)

With a discharge head having multiple nozzles,
A scanning mechanism that moves the discharge head in the scanning direction,
A transport mechanism that moves the recording medium in a transport direction orthogonal to the scanning direction,
With a control unit
The plurality of nozzles have an upstream end nozzle arranged at the upstream end in the transport direction and a downstream end nozzle arranged at the downstream end.
Based on the image data, the control unit ejects droplets having different amounts of liquid from the nozzles while moving the ejection head in the scanning direction in one pass to form dots on the recording medium. A path process including a recording process and a transfer process for moving the recorded medium in the transfer direction is executed.
Further, the control unit
The first dot on the recording medium formed by the first droplet of small droplets ejected from the upstream end nozzle in the first pass processing, and the downstream in the second pass processing following the first pass processing. Based on the distance in the transport direction from the second dot on the recordable medium formed by the second droplet of the small droplets ejected from the end nozzle, the transport amount of the recordable medium in the transport direction is determined. Set,
In the image data, the third dot on the recording medium formed by the third droplet from the upstream end nozzle in the third pass processing and the downstream in the fourth pass processing following the third pass processing. The fourth dot on the recording medium formed by the fourth droplet from the end nozzle is adjacent to each other in the transport direction, and the third droplet and the fourth droplet are both small. When the amount of liquid is larger than that of the droplet, at least one of the third droplet and the fourth droplet to be ejected in the recording process is liquid from the middle drop to the middle drop. A liquid discharge device that converts a large amount of droplets into large droplets. In the image data, the control unit has the third dot formed by the third droplet which is the middle drop and the fourth dot formed by the fourth droplet which is the middle drop. When a plurality of the sets are continuous in the scanning direction, the third dot and the fourth dot of the third dot and the fourth dot, which form the respective set to be ejected in the recording process, form a set adjacent to each other in the transport direction. The liquid ejection device according to claim 1, wherein a droplet of any one of the dots is converted from the medium droplet to the large droplet. In the control unit, the droplets of any one of the third dot and the fourth dot forming the set are arranged in a dusty shape so that the dots formed by the large droplets after conversion are arranged in a dusty manner. The liquid discharge device according to claim 2, which converts droplets into the large droplets. A switching unit for switching between a normal mode and an eco mode in which the amount of droplets is reduced as compared with the normal mode is provided.
When the eco-mode is set, the control unit converts a droplet of one of the third dot and the fourth dot from the middle drop to the large drop in the recording process. The liquid ejection device according to claim 3, wherein the droplet of the other dot is converted from the medium droplet to the small droplet. It is provided with an acquisition unit for acquiring the paper type of the recording medium.
In the recording process, when the control unit converts a droplet of one of the third dot and the fourth dot from the middle droplet to the large droplet, the droplet landing on the recording medium is generated. For the paper type that is relatively difficult to spread, the droplets of the other dots are maintained as the middle droplets, while the droplets that land on the recording medium are relatively easy to spread for the paper type. The liquid ejection device according to claim 3 or 4, wherein the droplet of the other dot is converted from the medium droplet to the small droplet. It is provided with an acquisition unit for acquiring the grain of the recording medium.
In the recording process, when the control unit converts a droplet of one of the third dot and the fourth dot from the middle droplet to the large droplet, the droplet landing on the recording medium is generated. For the paper grain that is relatively difficult to spread, the droplets of the other dots are maintained as the middle droplets, while the droplets that have landed on the recording medium are relatively easy to spread for the paper grain. The liquid discharge device according to any one of claims 3 to 5, which converts a droplet of the other dot from the medium droplet to the small droplet. With a discharge head having multiple nozzles,
A scanning mechanism that moves the discharge head in the scanning direction,
A transport mechanism that moves the recording medium in a transport direction orthogonal to the scanning direction,
With a control unit
The plurality of nozzles are a liquid discharge method using a liquid discharge device having an upstream end nozzle arranged at the upstream end in the transport direction and a downstream end nozzle arranged at the downstream end.
Based on the image data, the recording process of forming dots on the recording medium by ejecting droplets having different amounts of liquid from the nozzles while moving the ejection head in the scanning direction in one pass, and the above-mentioned An execution step for executing a path process including a transfer process for moving the recording medium in the transfer direction, and an execution step.
The first dot on the recording medium formed by the first droplet of small droplets ejected from the upstream end nozzle in the first pass processing, and the downstream in the second pass processing following the first pass processing. Based on the distance in the transport direction from the second dot on the recordable medium formed by the second droplet of the small droplets ejected from the end nozzle, the transport amount of the recordable medium in the transport direction is determined. Setting steps to set and
In the image data, the third dot on the recording medium formed by the third droplet from the upstream end nozzle in the third pass processing and the downstream in the fourth pass processing following the third pass processing. The fourth dot on the recording medium formed by the fourth droplet from the end nozzle is adjacent to each other in the transport direction, and the third droplet and the fourth droplet are both small. When the amount of liquid is larger than that of the droplet, at least one of the third droplet and the fourth droplet to be ejected in the recording process is liquid from the middle drop to the middle drop. A liquid discharge method comprising a conversion step of converting into a large amount of large droplets. In the setting step, if the distance between the first dot and the second dot is not within a predetermined range, the first pass process and the second pass process in which the transport amount is changed are executed.
The liquid discharge method according to claim 7, wherein if the interval is within a predetermined range, the transfer amount of the recording medium in the transfer direction is set based on the interval. With a discharge head having multiple nozzles,
A scanning mechanism that moves the discharge head in the scanning direction,
A transport mechanism that moves the recording medium in a transport direction orthogonal to the scanning direction,
With a control unit
The plurality of nozzles are liquid discharge devices having an upstream end nozzle arranged at the upstream end in the transport direction and a downstream end nozzle arranged at the downstream end.
Based on the image data, the recording process of forming dots on the recording medium by ejecting droplets having different amounts of liquid from the nozzles while moving the ejection head in the scanning direction in one pass, and the above-mentioned An executing means for executing a transfer process including moving the recording medium in the transfer direction and a path process including the transfer process.
The first dot on the recording medium formed by the first droplet of small droplets ejected from the upstream end nozzle in the first pass processing, and the downstream in the second pass processing following the first pass processing. Based on the distance in the transport direction from the second dot on the recordable medium formed by the second droplet of the small droplets ejected from the end nozzle, the transport amount of the recordable medium in the transport direction is determined. Setting means to set and
In the image data, the third dot on the recording medium formed by the third droplet from the upstream end nozzle in the third pass processing and the downstream in the fourth pass processing following the third pass processing. The fourth dot on the recording medium formed by the fourth droplet from the end nozzle is adjacent to each other in the transport direction, and the third droplet and the fourth droplet are both small. When the amount of liquid is larger than that of the droplet, at least one of the third droplet and the fourth droplet to be ejected in the recording process is liquid from the middle drop to the middle drop. A computer program that acts as a conversion means to convert large volumes of large droplets.

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