Liquid dispensing device, liquid dispensing method, and program

Abstract

To provide a liquid discharge device, a liquid discharge method and a program which can maintain productivity while preventing deterioration in image quality due to poor drying.SOLUTION: The liquid discharge device comprises: a first head having a nozzle that prints a first image on a recording medium while discharging liquid to the recording medium; a second head, provided closer to a downstream side than the first head in a conveying direction, which has a plurality of nozzles, provided along the conveying direction of the recording medium, which print second images on the recording medium while discharging liquid to the recording medium; and a control part that when performing multi-layer printing for printing the second image on the first image, makes an amount of liquid made to adhere to the recording medium by a nozzle at an upstream side in the conveying direction smaller than an amount of liquid made adhere to the recording medium by a nozzle at a downstream side in the conveying direction, in the second head.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] The present invention relates to a liquid ejection device, a liquid ejection method, and a program.

Background Art

[0002] In liquid ejection devices such as inkjet printers, techniques have been developed in which a first printing is performed with a special color (such as white) as a background color, and then a color image is overprinted on it with a second printing. According to this technique, printing with enhanced color development is possible regardless of the printing substrate. Conversely, in a liquid ejection device, a multilayer printing technique for use in a window film or the like has been developed by printing a color image with a first printing on a transparent substrate and then printing a special color (such as white) with a second printing on it.

[0003] <000001​​​​​​​​​​​​​​The present invention has been made in view of the above, and aims to provide a liquid dispensing device, a liquid dispensing method, and a program that can maintain productivity while preventing a decrease in image quality due to drying defects. [Means for solving the problem]

[0006] To solve the above-mentioned problems and achieve the objective, the present invention comprises: a first head having a nozzle for discharging liquid onto a recording medium to print a first image; a second head provided along the transport direction of the recording medium and having a plurality of nozzles for discharging liquid onto the recording medium to print a second image, and provided downstream of the first head in the transport direction; and, when performing multilayer printing to print the second image on the first image, the second head, which reduces the amount of liquid adhering to the recording medium by the nozzles on the upstream side in the transport direction compared to the amount of liquid adhering to the recording medium by the nozzles on the downstream side in the transport direction. When performing multilayer printing, the control unit increases the amount of liquid adhering to the recording medium by the nozzles of the second head as it moves from the upstream side to the downstream side in the transport direction. . [Effects of the Invention]

[0007] According to the present invention, productivity can be maintained while preventing a decrease in image quality due to insufficient drying. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing the configuration of an image forming apparatus to which the liquid dispensing device according to this embodiment is applied. [Figure 2] Figure 2 shows an example of a control block for an image forming apparatus according to this embodiment. [Figure 3] Figure 3 is a schematic diagram showing the configuration of the heater unit included in the image forming apparatus according to this embodiment. [Figure 4] Figure 4 is a flowchart showing an example of the flow of the ink adhesion amount control process by the image forming apparatus according to this embodiment. [Figure 5]Figure 5 is a diagram illustrating an example of multilayer printing in an image forming apparatus according to this embodiment. [Figure 6] Figure 6 is a diagram illustrating an example of the ink adhesion amount control process in the image forming apparatus according to this embodiment. [Figure 7] Figure 7 is a diagram illustrating an example of the ink adhesion amount control process in the image forming apparatus according to this embodiment. [Figure 8] Figure 8 is a diagram illustrating an example of the ink adhesion amount control process in the image forming apparatus according to this embodiment. [Figure 9] Figure 9 is a diagram illustrating an example of the ink adhesion amount control process in the image forming apparatus according to this embodiment. [Figure 10] Figure 10 is a diagram illustrating an example of the ink adhesion amount control process in the image forming apparatus according to this embodiment. [Figure 11] Figure 11 is a diagram illustrating an example of the ink adhesion amount control process in the image forming apparatus according to this embodiment. [Figure 12] Figure 12 is a diagram illustrating an example of the ink adhesion amount control process in the image forming apparatus according to this embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the liquid dispensing device, liquid dispensing method, and program will be described in detail below with reference to the attached drawings.

[0010] Figure 1 is a schematic diagram showing the configuration of an image forming apparatus to which the liquid ejection device according to this embodiment is applied. As shown in Figure 1, the image forming apparatus 100 according to this embodiment is a wide-width serial inkjet recording apparatus.

[0011] As shown in Figure 1, the image forming apparatus 100 is equipped with side plates 21A and 21B on the left and right sides of the apparatus body 100a. The side plates 21A and 21B horizontally support the main guide rod 31, which is a guide member. The image forming apparatus 100 is also equipped with a sub-sheet metal guide 32. The main guide rod 31 and the sub-sheet metal guide 32 slidably hold the carriage 121. The carriage 121 moves and scans in the direction of arrow A (main carriage scanning direction) via a timing belt that is rotationally driven by the main scanning motor. The carriage 121 is also equipped with an optical sensor 37 that detects the edge (paper edge) of a medium P (an example of a recording medium) such as paper.

[0012] The carriage 121 is equipped with liquid ejection heads (examples of heads) 122a, 122b, and 122c that eject ink droplets (examples of liquids) of various colors such as yellow (Y), cyan (C), magenta (M), black (K), orange (O), green (G), and clear (Cl), depending on the installed ink cartridge 10. Hereinafter, when liquid ejection heads 122a, 122b, and 122c are not distinguished, they will be referred to as liquid ejection head 122.

[0013] The liquid ejection head 122 has a nozzle row consisting of multiple nozzles arranged in the sub-scanning direction (the transport direction of the medium P). That is, the liquid ejection head 122 has multiple nozzles that are provided along the sub-scanning direction and eject ink droplets onto the medium P to print an image. Here, the sub-scanning direction (direction of arrow B) is perpendicular to the carriage main scanning direction (direction of arrow A). The liquid ejection head 122 is mounted with the ink droplet ejection direction from the nozzles facing downwards.

[0014] The liquid ejection heads 122a, 122b, and 122c are each installed with a shift in the sub-scanning direction. That is, the liquid ejection head 122b (an example of the second head) is provided downstream of the liquid ejection head 122c (an example of the first head) in the sub-scanning direction. Also, the liquid ejection head 122a (an example of the second head) is provided downstream of the liquid ejection head 122b (an example of the first head) in the sub-scanning direction. The carriage 121 mounts sub-tanks to supply inks of respective colors corresponding to the liquid ejection heads 122.

[0015] The image forming apparatus 100 includes a cartridge loading portion 1 for detachably mounting ink cartridges 10y, 10c, 10m, and 10k of respective colors. In the following description, when the ink cartridges 10y, 10c, 10m, and 10k are not distinguished, they are referred to as the ink cartridge 10. The ink in the ink cartridge 10 is replenished and supplied to the sub-tank of the carriage 121 through supply tubes 36 of respective colors by a supply pump unit. Note that the ink cartridge 10 may include a white ink cartridge.

[0016] The image forming apparatus 100 includes a maintenance and recovery mechanism 81 in a non-printing area on one side in the main scanning direction of the carriage 121. The maintenance and recovery mechanism 81 maintains and recovers the state of the nozzles of the liquid ejection head 122. The maintenance and recovery mechanism 81 includes cap members (hereinafter referred to as caps) 82a, 82b, and 82c for capping each nozzle surface of the liquid ejection head 122, a wiping unit 83 for wiping the nozzle surface, and the like. In the following description, when the caps 82a, 82b, and 82c are not distinguished, they are referred to as the cap 82. Also, a replaceable waste liquid tank for storing waste liquid generated by the maintenance and recovery operation is provided below the maintenance and recovery mechanism 81 of the liquid ejection head 122.

[0017] FIG. 2 is a diagram showing an example of a control block of an image forming apparatus according to the present embodiment. As shown in FIG. 2, the image forming apparatus 100 according to the present embodiment includes an image processing unit 200 and a printer main body 300. The image processing unit 200 converts an input image to be printed on a medium P into dot data printable by the printer main body 300, and inputs the converted dot data to the printer main body 300.

[0018] For example, the image processing unit 200 executes various image processes such as resolution conversion processing, color conversion processing using a color conversion table, halftone processing, and rasterization processing on the input image. Thereafter, the image processing unit 200 converts the input image on which the image processing has been executed into dot data of each color, and inputs the dot data to the printer main body 300.

[0019] Specifically, when performing multi-layer printing in which a second image is printed on a first image, the image processing unit 200 (an example of a control unit) reduces the amount of ink adhesion to the medium P by the nozzles on the upstream side in the conveyance direction of the medium P in the liquid ejection head 122 that prints the second image, compared with the amount of ink adhesion to the medium P by the nozzles on the downstream side in the conveyance direction of the medium P. As a result, after the first image such as a background image is printed on the medium P, the degree of dryness of the ink used for printing the first image becomes high, and then the number of nozzles used for printing the second image such as a color image is increased, so that the dot embedding of the second image with respect to the first image can be suppressed. As a result, it is possible to maintain productivity while preventing a decrease in image quality due to poor drying.

[0020] Here, the first image is an image printed by the nozzles of the liquid ejection head 122 provided on the upstream side in the conveyance direction of the medium P among the liquid ejection heads 122a, 122b, 122c (hereinafter referred to as the upstream side head). Further, here, the second image is an image printed by the nozzles of the liquid ejection head provided on the downstream side of the upstream side head 122 in the conveyance direction of the medium P among the liquid ejection heads 122a, 122b, 122c (hereinafter referred to as the downstream side head).

[0021] Furthermore, when performing multilayer printing, the image processing unit 200 may reduce the amount of ink deposited on the medium P by the nozzle on the downstream side in the transport direction of the medium P at the upstream head 122 compared to the amount of ink deposited on the medium P by the nozzle on the upstream side in the transport direction of the medium P.

[0022] Furthermore, when performing multilayer printing, the image processing unit 200 may increase the amount of ink deposited on the medium P by the nozzles of the downstream head 122 as the transport direction of the medium P progresses from upstream to downstream. In addition, when performing multilayer printing, the image processing unit 200 may decrease the amount of ink deposited on the medium P by the nozzles of the upstream head 122 as the transport direction of the medium P progresses from upstream to downstream.

[0023] In the printer unit 300, which receives dot data, the controller unit 301 controls and drives various printing units based on the dot data to print an image onto the medium P. In the image forming apparatus 100 according to this embodiment, the number of nozzles used by the liquid ejection head 122 and the amount of ink droplets attached (ink adhesion amount) for each scan are determined based on the dot data, and the controller unit 301 changes the control of each unit according to the determined ink adhesion amount and other conditions.

[0024] In this embodiment, the printer body 300 includes a controller unit 301, an interface 302, a paper feed unit 303, a transport unit 304, a paper output unit 305, a heater unit 306, an ink supply unit 307, a carriage 121, a liquid ejection head 122, and the like.

[0025] The I / F 302 inputs the input image from the image processing unit 200 to the printer body 300. The paper feed unit 303 feeds the medium P into the image forming apparatus 100. The transport unit 304 transports the medium P that has been fed into the image forming apparatus 100. The paper discharge unit 305 discharges the medium P on which the input image has been printed. The heater unit 306 dries any ink droplets adhering to the medium P. The ink supply unit 307 supplies ink from the ink cartridge 10 to the liquid ejection head 122.

[0026] The controller unit 301 includes a CPU (Central Processing Unit) 301a and memory 301b. Memory 301b includes ROM (Read Only Memory) 301c and RAM (Random Access Memory) 301d. ROM 301c stores various programs. RAM 301d is used as a workspace when the CPU 301a executes various programs.

[0027] The CPU 301a controls the overall operation of the image forming apparatus 100. Specifically, the CPU 301a is an example of a processor that uses the RAM 301d as a workspace and executes various programs stored in the memory 301b.

[0028] Figure 3 is a schematic diagram showing the configuration of the heater unit included in the image forming apparatus according to this embodiment. In the example shown in Figure 3, for simplicity, two liquid discharge heads 122a and 122b are shown as the liquid discharge head 122, and the liquid discharge head 122c is not described.

[0029] As shown in Figure 3, the heater 120 of the heater unit 306 includes a preheater 120a, a print heater 120b, a print heater 120c, a postheater 120d, and a drying heater 120e. Each of these heaters 120 is equipped with a temperature sensor, such as a thermistor, for temperature control.

[0030] The preheater 120a is a device that preheats the medium P to a temperature suitable for forming the liquid-coated surface. For example, the preheater 120a (upper margin +2°C, lower margin 0°C) is an aluminum foil cord heater. The preheater 120a is attached to the back surface of the transport guide plate 130. The preheater 120a heats the medium P by heating the transport guide plate 130 itself. The preheated medium P is then sent by the transport rollers 123a and 123b to the image forming unit 50 where the liquid discharge head 122 is located.

[0031] In the image forming unit 50, the medium P is kept warm by the print heaters 120b and 120c, and a liquid such as ink is ejected from the liquid ejection head 122 to form a liquid-coated surface. The heated air rises along with the steam, but to prevent the upper part of the image forming apparatus 100 from overheating due to its stagnation, a fan 119 promotes air convection.

[0032] Print heaters 120b and 120c are devices that maintain the temperature of the medium P when forming a liquid coating surface on the medium P. For example, print heaters 120b and 120c (upper margin +0.5°C, lower margin -0.5°C) are cord heaters embedded in a platen 131 made of aluminum. Print heaters 306b and 306c heat the medium P by heating the platen 131 itself.

[0033] The post-heater 120d and drying heater 120e are devices that heat the medium P on which the liquid-coated surface is formed in order to dry and fix the liquid such as ink. For example, the post-heater 120d (upper margin +2°C, lower margin 0°C) is an aluminum foil cord heater. The post-heater 120d is attached to the back surface of the transport guide plate 132. The post-heater 120d heats the medium P by heating the transport guide plate 132 itself. Also, for example, the drying heater 120e (upper margin +0.5°C, lower margin -0.5°C) is an IR heater. The drying heater 120e dries the liquid-coated surface of the medium P by radiating IR radiation. The drying heater 120e may be equipped with a fan to send hot air to the liquid-coated surface of the medium P.

[0034] Figure 4 is a flowchart showing an example of the flow of the ink adhesion amount control process by the image forming apparatus according to this embodiment. When the printing operation starts (step S401), the image processing unit 200 reads image data of the input image to be printed on the medium P from an external device (step S402). Next, the image processing unit 200 determines whether or not to perform multilayer printing of the read image data (step S403).

[0035] If multilayer printing of the loaded image data is not performed (Step S403: No), the image processing unit 200 converts the image data into dot data for each color (Step S404) and inputs the dot data to the printer unit 300 (Step S405). The printer unit 300 then prints the input image data (Step S406).

[0036] On the other hand, when performing multilayer printing of the read image data (step S403: Yes), the image processing unit 200 reduces the amount of ink deposited on the medium P by the nozzle on the downstream side in the transport direction of the medium P at the upstream head 122 compared to the amount of ink deposited on the medium P by the nozzle on the upstream side in the transport direction of the medium P (step S407). Furthermore, the image processing unit 200 increases the amount of ink deposited on the medium P by the nozzle on the downstream side in the transport direction of the medium P at the downstream head 122 compared to the amount of ink deposited on the medium P by the nozzle on the upstream side in the transport direction of the medium P (step S407). After that, the process proceeds to steps S404 to S406, similar to the case when multilayer printing of the image data is not performed.

[0037] Figure 5 illustrates an example of multilayer printing in the image forming apparatus according to this embodiment. For example, in normal printing without multilayer printing, a color image is printed on a printing substrate (an example of a medium P). However, in the case of multilayer printing, a background image (such as a white image) is printed on the printing substrate, and then the color image is printed on top of it. In this case, the color image may be printed before the background image dries, potentially resulting in an undesirable image quality.

[0038] Therefore, in the image forming apparatus 100 according to this embodiment, the image processing unit 200, as described above, reduces the amount of ink adhering to the medium P by the nozzles on the upstream side in the transport direction of the medium P in the downstream head 122 compared to the amount of ink adhering to the medium P by the nozzles on the downstream side in the transport direction of the medium P. As a result, after the first image, such as a background image, is printed on the medium P, the number of nozzles used to print the second image, such as a color image, is increased only after the ink used to print the first image has dried sufficiently, thereby suppressing the dots of the second image from being embedded in the first image. Consequently, productivity can be maintained while preventing a decrease in image quality due to poor drying.

[0039] Figures 6 and 7 illustrate an example of the ink adhesion control process in the image forming apparatus according to this embodiment. In Figure 7, the vertical axis represents the dot diameter of the second image, and the horizontal axis represents the drying time of the first image. As shown in Figures 6 and 7, the spread of the dots of the color image (color ink) printed on the background image changes depending on the degree of dryness of the background image (background color). Specifically, when the degree of dryness of the background image is low, the dots of the color image become embedded in the background image, and their dot diameter becomes smaller. On the other hand, when the degree of dryness of the background image is high and the background image dries, the dots of the color image are no longer embedded in the background image, and their dot diameter becomes larger.

[0040] Furthermore, because the degree to which dots are embedded in the background image differs for each color in the color image, the dot diameters of each color will not be the same even with the same drying time for the background image. Therefore, in this embodiment, the image processing unit 200 can also change the amount by which the downstream head 122 reduces the amount of ink deposited on the medium P by the nozzle on the upstream side in the transport direction of the medium P compared to the amount of ink deposited on the medium P by the nozzle on the downstream side in the transport direction of the medium P (hereinafter referred to as the reduction amount) for each color in the color image. For example, if the color image contains black (Bk) dots and cyan (Cy) dots, the image processing unit 200 sets the reduction amount for black, which is more difficult to dry, to be greater than the reduction amount for cyan.

[0041] Figures 8-12 illustrate an example of the ink deposition amount control process in the image forming apparatus according to this embodiment. Here, the upstream head 122 is described as a head that prints a white image, and the downstream head 122 is described as a head that prints a color image (Bk, Cy, Ma, Ye). The color configuration of the upstream head 122 and the downstream head 122 may be reversed. Furthermore, in the following description, of the nozzle areas of the upstream head 122 and the downstream head 122, the area indicated by reference numeral 801 is considered the nozzle area used for ejecting ink, and the area indicated by reference numeral 802 is considered the nozzle area not used for ejecting ink.

[0042] For example, as shown in Figure 8, if the nozzle usage area is not reduced, that is, if no unused nozzle area is provided and the number of nozzles used is not changed, the printing of white images and color images is performed consecutively. As a result, there is insufficient drying time for the white images, and drying defects are highly likely to occur.

[0043] On the other hand, as shown in Figure 9, if the nozzle area used is reduced in both the upstream head 122 and the downstream head 122 to increase drying time, the image quality may decrease because the printed image must be completed in 12 scans due to the reduction in the nozzle area used. Also, as shown in Figure 10, if the number of printed scans is maintained while reducing the number of nozzle areas used, productivity decreases because blank scans must be included to compensate for the reduced nozzle area used.

[0044] Therefore, in this embodiment, as shown in Figure 11, the image processing unit 200 does not remove the nozzle area being used, but at the upstream head 122, it reduces the amount of ink deposited per scan as it moves downstream in the transport direction of the medium P, and at the downstream head 122, it increases the amount of ink deposited as it moves downstream in the transport direction of the medium P. This allows for printing that maintains the number of scans and prevents a decrease in image quality, while also being advantageous for drying.

[0045] Alternatively, in this embodiment, as shown in Figure 12, the image processing unit 200 reduces the amount of ink adhering to the upstream side in the transport direction of the medium P at the downstream head 122. On the other hand, when printing a white image that does not significantly affect image quality, the image processing unit 200 reduces the nozzle area used by the upstream head 122. This allows for printing that is advantageous for drying, and for the printed portion at the downstream head 122 where image quality is required, the amount of ink adhering is changed to allow for a higher number of scans and is advantageous for drying.

[0046] Thus, according to the image forming apparatus 100 of this embodiment, after a first image such as a background image is printed on the medium P, the number of nozzles used to print a second image such as a color image is increased only after the ink used to print the first image has dried sufficiently. This suppresses the dots of the second image from being embedded in the first image. As a result, productivity can be maintained while preventing a decrease in image quality due to poor drying.

[0047] The program executed by the image forming apparatus 100 in this embodiment is provided pre-installed in ROM or the like. Alternatively, the program executed by the image forming apparatus 100 in this embodiment may be provided as an installable or executable file recorded on a computer-readable recording medium such as a CD-ROM, flexible disk (FD), CD-R, or DVD (Digital Versatile Disk).

[0048] Furthermore, the program executed by the image forming apparatus 100 of this embodiment may be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. Alternatively, the program executed by the image forming apparatus 100 of this embodiment may be provided or distributed via a network such as the Internet.

[0049] The program executed in the image forming apparatus 100 of this embodiment has a modular configuration that includes the above-described parts (image processing unit 200). In actual hardware, the CPU (an example of a processor) reads the program from the ROM and executes it, thereby loading the above-described parts onto the main memory, and creating the image processing unit 200 on the main memory.

[0050] In the above embodiment, the image forming apparatus 100 of the present invention is described as being applied to a multifunction device having at least two functions from among a copy function, a printer function, a scanner function, and a facsimile function. However, it can be applied to any image forming apparatus such as a copier, printer, scanner, or facsimile device. [Explanation of Symbols]

[0051] 100 Image forming apparatus 121 Carriage 122 Liquid dispensing head 200 Image Processing Unit 300 Printer body [Prior art documents] [Patent Documents]

[0052] [Patent Document 1] Japanese Patent Publication No. 2021-66064

Claims

1. A first head having a nozzle that ejects liquid onto a recording medium to print a first image, A second head is provided along the transport direction of the recording medium and has a plurality of nozzles that discharge liquid onto the recording medium to print a second image, and is provided downstream of the first head in the transport direction, When performing multilayer printing in which the second image is printed on the first image, the second head includes a control unit that reduces the amount of liquid adhering to the recording medium by the nozzle on the upstream side in the transport direction compared to the amount of liquid adhering to the recording medium by the nozzle on the downstream side in the transport direction, Equipped with, The control unit, when performing multilayer printing, is a liquid dispensing device that increases the amount of liquid adhering to the recording medium by the nozzles of the second head as it moves from the upstream side to the downstream side in the transport direction.

2. A first head having a plurality of nozzles provided along the transport direction of the recording medium and discharging liquid onto the recording medium to print a first image, A second head is provided along the transport direction of the recording medium and has a plurality of nozzles that discharge liquid onto the recording medium to print a second image, and is provided downstream of the first head in the transport direction, When performing multilayer printing in which the second image is printed on the first image, the second head reduces the amount of liquid adhering to the recording medium by the nozzle on the upstream side in the transport direction compared to the amount of liquid adhering to the recording medium by the nozzle on the downstream side in the transport direction, and the first head reduces the amount of liquid adhering to the recording medium by the nozzle on the downstream side in the transport direction compared to the amount of liquid adhering to the recording medium by the nozzle on the upstream side in the transport direction, Equipped with, The control unit, when performing multilayer printing, is a liquid dispensing device that reduces the amount of liquid adhering to the recording medium by the nozzles of the first head as it moves from the upstream side to the downstream side in the transport direction.

3. A liquid dispensing method performed by a liquid dispensing device comprising: a first head having a nozzle; and a second head having a plurality of nozzles arranged along the transport direction of the recording medium and located downstream of the first head in the transport direction, A step of printing a first image by ejecting liquid from a nozzle of the first head onto the recording medium, A step of printing a second image by ejecting liquid from a nozzle of the second head onto the recording medium, When performing multilayer printing in which the second image is printed on the first image, the second head includes a reduction step in which the amount of liquid adhering to the recording medium by the nozzle on the upstream side in the transport direction is reduced to the amount of liquid adhering to the recording medium by the nozzle on the downstream side in the transport direction, Includes, The reduction step is a liquid discharge method in which, when performing multilayer printing, the amount of liquid adhering to the recording medium by the nozzles of the second head increases from the upstream side to the downstream side in the transport direction.

4. A computer controls a liquid dispensing device having a first head having a nozzle for dispensing liquid onto a recording medium to print a first image, and a second head provided along the transport direction of the recording medium and having a plurality of nozzles for dispensing liquid onto the recording medium to print a second image, and provided downstream of the first head in the transport direction. When performing multilayer printing in which the second image is printed on the first image, the second head has a control unit that reduces the amount of liquid adhering to the recording medium by the nozzle on the upstream side in the transport direction compared to the amount of liquid adhering to the recording medium by the nozzle on the downstream side in the transport direction. To make it function as, The control unit, when performing multilayer printing, has a program that increases the amount of liquid adhering to the recording medium by the nozzles of the second head as it moves from the upstream side to the downstream side in the transport direction.

Images