Liquid discharge head, liquid discharge unit, liquid discharge device, liquid discharge method and program

Abstract

To suppress an impact position from shifting and discharged droplets from being curvedly jetted and suppress white stripes and black stripes from being generated at a joint of a head.SOLUTION: A liquid discharge head, which performs density-gradation expression corresponding to an input gradation value, by making nozzles selectively discharge two or more of kinds of liquid droplets having different discharge amounts, comprises a discharging control part that performs control so that the nozzles discharge only largest liquid droplets of the two or more of kinds of liquid droplets, at a high gradation part where the input gradation value is high and so that the number of the nozzles that do not discharge liquid droplets of all of the nozzles does not monotonically decrease but increase in a portion between a low gradation part where the input gradation value is low and the high gradation part.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a liquid ejection head, a liquid ejection unit, an apparatus for ejecting a liquid, a liquid ejection method, and a program.

Background Art

[0002] Patent Document 1 discloses a head control method and an image processing technique for performing gradation expression of density by sorting droplets (large droplets, medium droplets, small droplets, etc.) having different ejection droplet amounts in a liquid ejection head.

[0003] More specifically, Patent Document 1 discloses a technique in which, for the purpose of performing gradation expression of density, in the low gradation portion, it is expressed with a small dot size by small droplets, and in the intermediate gradation portion, the ratio of the small dot size is reduced and medium dots of medium droplet size are mixed, and in the high gradation portion, the ratio of the medium dot size is reduced and large dots of large droplet size are mixed.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the conventional technology, when the number of droplets ejected simultaneously during gradation expression increases, there is a problem that the airflows generated by the ejected droplets themselves interfere with each other, and the ejected droplets are bent. Such a problem becomes more prominent as the distance from the nozzles of the liquid ejection head to a recording medium such as paper increases.

[0005] Specifically, when satellites or the like are generated in the ejected droplets, the satellites are carried by the airflow and land, resulting in unevenness such as a wood grain pattern. Also, in the nozzles at the ends of the liquid ejection head, there is a bias in the airflow that is affected, and the landing position is likely to shift (bend easily). In particular, in the case of printing by arranging a plurality of liquid ejection heads side by side, white streaks / black streaks are likely to occur at the joints of the liquid ejection heads.

[0006] In order to solve the above problems, there is a method of increasing the number of non-ejecting nozzles of a liquid ejection head, but a more efficient method is required.

[0007] The present invention has been made in view of the above, and an object thereof is to suppress landing position deviation and ejection curve of ejected droplets, and to suppress white streaks / black streaks at the joints of the head.

Means for Solving the Problems

[0008] In order to solve the above-described problems and achieve the object, the present invention provides a liquid ejection head that selectively ejects two or more types of droplets having different ejection droplet amounts from nozzles to perform tone expression of a concentration corresponding to an input tone value. In the high-tone portion of the input tone value, only the largest droplet among the two or more types of droplets is ejected from the nozzle, and the number of non-ejecting nozzles among all the nozzles increases without monotonically decreasing from the low-tone portion to the high-tone portion of the input tone value. It is characterized by including an ejection control unit that controls so as to include a portion that increases.

Effects of the Invention

[0009] According to the present invention, there is an effect that landing position deviation and ejection curve of ejected droplets can be suppressed, and white streaks / black streaks at the joints of the head can be suppressed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of a liquid ejection head, a liquid ejection unit, an apparatus for ejecting a liquid, a liquid ejection method, and a program will be described in detail with reference to the accompanying drawings.

[0012] Hereinafter, as an example of an apparatus for ejecting a liquid to which the present invention is applied, an image forming apparatus which is an aspect of the apparatus for ejecting a liquid will be described as an example, but the present invention is not limited thereto.

[0013] (First Embodiment) FIG. 1 is a perspective view showing the interior of an image forming apparatus 100 according to the first embodiment in a perspective view. FIG. 2 is a diagram showing an outline of the configuration of the image forming apparatus 100. As shown in FIGS. 1 and 2, the image forming apparatus 100 according to the present embodiment is a wide-width serial type inkjet recording apparatus.

[0014] In addition, in this embodiment, an example in which the apparatus for discharging the liquid of the present invention is applied to a wide-width serial type inkjet is described. However, it can be applied to any image forming apparatus such as a multifunction peripheral having at least two functions among a copying function, a printer function, a scanner function, and a facsimile function, a copying machine, a printer, a scanner apparatus, and a facsimile apparatus.

[0015] As shown in FIGS. 1 and 2, the image forming apparatus 100 includes side plates 21A and 21B on the left and right of the apparatus main body 100a. The side plates 21A and 21B horizontally support a main guide rod 31 which is a guide member. The image forming apparatus 100 also includes a sub sheet metal guide 32. The main guide rod 31 and the sub sheet metal guide 32 slidably hold a carriage 121.

[0016] The carriage 121 moves in the direction of arrow G (carriage main scanning direction) via a timing belt that is rotationally driven by a main scanning motor 117 (see FIG. 3), and thus relatively moves with respect to a medium 40 which is a recording medium. The movement of the carriage 121 can also be referred to as scanning. The carriage 121 is equipped with an optical sensor 37 that detects an end portion (paper end portion) of the medium 40.

[0017] The optical sensor 37 is an example of a reading unit that outputs a reading signal of an image previously formed on the medium 40 by the image forming apparatus 100. In this embodiment, the image forming apparatus 100 detects an abnormality of the image based on the reading signal from the optical sensor 37. As the optical sensor 37, a device that detects by reflection density, a camera that images the image formed on the medium 40, or the like can be used. Note that in this embodiment, the abnormality of the image includes an omen of abnormality which is a state where an abnormality is likely to occur.

[0018] The carriage 121 is provided with liquid ejection heads 122a, 122b, 122c (when not distinguished, these three liquid ejection heads 122a, 122b, 122c are collectively referred to as "liquid ejection head 122") that eject ink droplets (liquids) of various colors such as yellow (Y), cyan (C), magenta (M), black (K), orange (O), green (G), and clear (Cl) according to the mounted ink cartridge 10.

[0019] The medium 40 moves along the sub-scanning direction (the direction of arrow H), which is substantially orthogonal to the main scanning direction, by using a conveyance roller that is rotationally driven by a sub-scanning motor 118 (see FIG. 3), thereby relatively moving with respect to the liquid ejection head 122. However, the main scanning direction and the sub-scanning direction do not necessarily have to be substantially orthogonal, and it is sufficient if they intersect.

[0020] The liquid ejection head 122 arranges a nozzle row composed of a plurality of nozzles (not shown) in the sub-scanning direction. The liquid ejection head 122 is mounted with the ink droplet ejection direction from the nozzles facing downward. The liquid ejection heads 122a, 122b, 122c are each installed with a shift in the sub-scanning direction. The carriage 121 mounts a sub-tank to supply ink of various colors corresponding to the liquid ejection head 122.

[0021] The "liquid ejection head" is a functional component that ejects and sprays liquid from nozzles. The liquid to be ejected may be any liquid having a viscosity and surface tension that can be ejected from the liquid ejection head 122, and is not particularly limited, but it is preferably a liquid whose viscosity becomes 30 mPa·s or less at normal temperature and pressure or by heating and cooling. More specifically, it includes solutions, suspensions, emulsions, etc. containing solvents such as water and organic solvents, colorants such as dyes and pigments, functional imparting materials such as polymerizable compounds, resins, and surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, and edible materials such as natural pigments. These can be used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic elements and light-emitting elements, and liquids for forming electronic circuit resist patterns, and materials for three-dimensional modeling.

[0022] As an energy source for discharging a liquid, those using a piezoelectric actuator (such as a laminated piezoelectric element and a thin-film piezoelectric element) are included.

[0023] In addition, the "liquid discharge head" is not limited to the pressure generating means used. For example, in addition to the piezoelectric actuator as described above (which may use a laminated piezoelectric element), a thermal actuator using an electrothermal conversion element such as a heating resistor, an electrostatic actuator composed of a diaphragm and a counter electrode, etc. may also be used.

[0024] The image forming apparatus 100 includes a cartridge loading unit 1 for detachably mounting ink cartridges 10y, 10c, 10m, 10k of each color (referred to as "ink cartridge 10" when not distinguished).

[0025] The ink in the ink cartridge 10 is replenished and supplied to the sub-tank of the carriage 121 through the supply tubes 36 of each color by a supply pump unit. The supply pump unit and the supply tubes 36 constitute a supply mechanism. Note that the ink cartridge 10 may include a white ink cartridge.

[0026] 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 / or recovers the state of the nozzles of the liquid discharge head 122.

[0027] The maintenance and recovery mechanism 81 includes cap members 82a, 82b, 82c (referred to as "cap member 82" when not distinguished) for capping each nozzle surface of the liquid discharge head 122, a wiping unit 83 for wiping the nozzle surface, etc. In addition, 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 discharge head 122.

[0028] The "liquid ejection unit" is an integrated unit of a liquid ejection head 122 with functional components and mechanisms, and is an assembly of components related to liquid ejection. For example, the "liquid ejection unit" includes at least one of a head tank (sub-tank of the carriage 121), the carriage 121, a supply mechanism, a maintenance and recovery mechanism 81, and a main scanning movement mechanism combined with the liquid ejection head 122, etc.

[0029] Here, the integration means, for example, that the liquid ejection head 122 and the functional components and mechanisms are fixed to each other by fastening, adhesion, engagement, etc., or one is held movably with respect to the other. Also, the liquid ejection head 122 and the functional components and mechanisms may be configured to be detachable from each other.

[0030] For example, as a liquid ejection unit, there is one in which the liquid ejection head 122 and the head tank are integrated. Also, there is one in which the liquid ejection head 122 and the head tank are integrated by being connected to each other with a tube or the like. Here, a unit including a filter can also be added between the head tank of these liquid ejection units and the liquid ejection head 122.

[0031] Also, as a liquid ejection unit, there is one in which the liquid ejection head 122 and the carriage are integrated.

[0032] Also, as a liquid ejection unit, the liquid ejection head 122 is movably held on a main guide rod 31 which is a guide member constituting a part of the main scanning movement mechanism, and the liquid ejection head 122 and the main scanning movement mechanism are integrated. Also, there is one in which the liquid ejection head 122, the carriage, and the main scanning movement mechanism are integrated.

[0033] Also, as a liquid ejection unit, a cap member 82 which is a part of the maintenance and recovery mechanism 81 is fixed to the carriage to which the liquid ejection head 122 is attached, and the liquid ejection head 122, the carriage, and the maintenance and recovery mechanism 81 are integrated.

[0034] In addition, as a liquid ejection unit, there is one in which a supply tube 36 is connected to a liquid ejection head 122 to which a head tank or a flow path component is attached, and the liquid ejection head 122 and the supply mechanism are integrated. Through this tube, the liquid from the liquid storage source is supplied to the liquid ejection head 122.

[0035] The main scanning movement mechanism shall also include the main guide rod 31 alone which is a guide member. Also, the supply mechanism shall include the supply tube 36 alone and the cartridge loading section 1 alone.

[0036] FIG. 3 is a block diagram showing an example of the hardware configuration of the image forming apparatus 100. As shown in FIG. 3, the image forming apparatus 100 includes a control unit 101, an operation panel 114, an environment sensor 115, an optical sensor 37, a head driver 116, a main scanning motor 117, a sub-scanning motor 118, a fan 119, a heater 120, a liquid ejection head 122, and a movement mechanism 140.

[0037] As shown in FIG. 3, the control unit 101 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 103, a RAM (Random Access Memory) 104, a non-volatile memory (NVRAM: Non-Volatile RAM) 105, an ASIC (Application Specific Integrated Circuit) 106, an I / F 107, a print control unit 108, a main scanning motor drive unit 109, a sub-scanning motor drive unit 110, a fan control unit 111, a heater control unit 112, and an I / O 113. Note that the control unit 101 may include configurations other than those described above.

[0038] The CPU 102, ROM 103, RAM 104, non-volatile memory 105, ASIC 106, I / F 107, print control unit 108, main scanning motor drive unit 109, sub-scanning motor drive unit 110, fan control unit 111, heater control unit 112, and I / O 113 are connected to be communicable with each other via, for example, a bus or the like.

[0039] The CPU 102 controls the operation of the entire image forming apparatus 100. Specifically, the CPU 102 realizes each function by executing a program stored in the ROM 103 or the like.

[0040] The ROM 103 stores programs executed by the CPU 102 and other fixed data, etc. The RAM 104 temporarily stores image data, etc. The non-volatile memory 105 retains data even while the power supply of the image forming apparatus 100 is cut off. The ASIC 106 is a circuit for performing various signal processes, image processing such as rearrangement, and processing input / output signals for controlling the entire apparatus.

[0041] The I / F 107 is an interface circuit for transmitting and receiving data and signals to and from the host side. Specifically, the I / F 107 receives print data (image data) generated by a printer driver of a host such as an information processing apparatus, an image reading apparatus, and an imaging apparatus via a cable, a network, or the like. That is, the generation and output of print data to the control unit 101 may be performed by the printer driver on the host side.

[0042] The print control unit 108 is a circuit for generating a drive waveform for driving the liquid ejection head 122 and selectively driving a pressure generating means for generating a pressure for the liquid ejection head 122 to eject liquid (ink) from the nozzles, and outputting print data and various accompanying data to the head driver 116.

[0043] The main scanning motor drive unit 109 is a circuit for driving the main scanning motor 117. The sub-scanning motor drive unit 110 is a circuit for driving the sub-scanning motor 118. The fan control unit 111 is a circuit for controlling the output of the fan 119 so that air is blown at a predetermined temperature and air volume.

[0044] The heater control unit 112 is a circuit for controlling the heater 120 so as to reach the set temperature. The I / O 113 is a circuit for acquiring information from the environment sensor 115 and extracting information required for controlling each part of the image forming apparatus 100. Note that the I / O 113 also inputs detection signals from various sensors (for example, the optical sensor 37) other than the environment sensor 115.

[0045] The operation panel 114 is a device for inputting and displaying various information such as user-specified resolution. The operation panel 114 is communicably connected to the CPU 102 etc. via the bus of the control unit 101, for example.

[0046] The environment sensor 115 is a sensor for detecting, for example, the environment temperature, environment humidity, etc. The environment sensor 115 is connected to the I / O 113 of the control unit 101.

[0047] The head driver 116 is a circuit for driving the liquid ejection head 122 by selectively applying drive pulses that constitute a drive waveform given from the print control unit 108 to the pressure generation means of the liquid ejection head 122 based on the input image data (for example, dot pattern data). The head driver 116 is connected to the print control unit 108 of the control unit 101. Note that the control of the ejection amount is performed by controlling the amplitude of the drive waveform input to the pressure generation means of the liquid ejection head 122, for example, but the ejection amount may be controlled using other means.

[0048] The main scanning motor 117 is a device that rotationally drives a timing belt by driving and moves the carriage 121 equipped with the liquid ejection head 122 in the main scanning direction (the direction of arrow G). The main scanning motor 117 is connected to the main scanning motor drive unit 109 of the control unit 101.

[0049] The sub-scanning motor 118 is a device that operates a conveyance roller that conveys the medium 40, which is an object to be discharged with liquid (ink) by the liquid discharge head 122, in the sub-scanning direction by driving. The sub-scanning motor 118 is connected to the sub-scanning motor drive unit 110 of the control unit 101.

[0050] The movement mechanism 140 relatively moves the liquid discharge head 122 and the medium 40. The movement mechanism 140 includes a main guide rod 31, a sub sheet metal guide 32, a carriage 121, a conveyance roller, etc., and constitutes a main scanning movement mechanism.

[0051] The movement mechanism 140 relatively moves the liquid discharge head 122 and the medium 40 along the main scanning direction by the main guide rod 31, the sub sheet metal guide 32, the carriage 121, etc. Also, the movement mechanism 140 relatively moves the liquid discharge head 122 and the medium 40 along the sub-scanning direction by a conveyance roller that conveys the medium 40. In the present embodiment, the relative movement in the sub-scanning direction by the movement mechanism 140 is an intermittent movement. The intermittent movement means a movement that alternately performs movement and stop.

[0052] The fan 119 is a device that promotes the convection of air inside the image forming apparatus 100 by driving and prevents the upper part of the image forming apparatus 100 from excessively rising in temperature due to the retention of warmed air. The fan 119 is connected to the fan control unit 111 of the control unit 101.

[0053] FIG. 4 is a block diagram showing an example of the functional configuration of the control unit 101. Note that the description of the components overlapping with FIG. 3 is omitted.

[0054] As shown in FIG. 4, the control unit 101 includes a color separation data generation unit 211 and a discharge control unit 212. The discharge control unit 210 controls the discharge of ink.

[0055] In the present embodiment, the control unit 101 includes a color separation data generation unit 211 and a discharge control unit 212.

[0056] When the image data to be printed is input, the color separation data generation unit 211 generates color separation data for each color of ink implemented in the image forming apparatus 100 from the input image data (an example of the input image). For example, when the image forming apparatus 100 performs printing using CMYK inks, the color separation data generation unit 211 generates color separation data for each of the CMYK colors from the input image data.

[0057] The ejection control unit 212 generates dot data by applying a dot data generation mask to the color separation data for each color generated by the color separation data generation unit 211. Here, the dot data generation mask is, for example, a dither mask with a set threshold value used for halftone processing. At that time, the ejection control unit 212 converts the image data into dot data including at least two or more types of dots.

[0058] In the present embodiment, the dot data has a four-tone level including small-drop dots, large-drop dots with a larger droplet volume than the small-drop dots, and medium-drop dots with a larger droplet volume than the small-drop dots and a smaller droplet volume than the large-drop dots. In the present embodiment, an example in the case where the ejection droplet volume of the small drops is 6 pL, the ejection droplet volume of the medium drops is 12 pL, and the ejection droplet volume of the large drops is 18 pL is shown.

[0059] The control unit 101 realizes these functions (the color separation data generation unit 211, the ejection control unit 212) by the CPU 102 executing a predetermined program. Further, the control unit 101 may realize some or all of these functions by one or a plurality of processing circuits.

[0060] The "processing circuit" includes a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, an ASIC (Application Specific Integrated Circuit) designed to execute each function described above, a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and devices such as conventional circuit modules.

[0061] The control unit 101 controls the liquid ejection head 122 and the moving mechanism 140 so as to dispose ink on the medium 40 while relatively moving the liquid ejection head 122 and the medium 40 a plurality of times. The ink disposed on the medium 40 forms dots in the image by fixing to the medium 40. More specifically, after one ink droplet formed by the ink ejected from the liquid ejection head 122 lands on the medium 40 and dries to fix to the medium 40, one dot in the image is formed. The image is formed as an aggregate of a plurality of dots.

[0062] Next, an example of dot classification for each dot type (hereinafter referred to as droplet type) by the ejection control unit 212 will be described.

[0063] Here, FIG. 5 is a diagram showing the relationship between the conventional Input Level and Drop Ratio. In FIG. 5, the horizontal axis represents the Input Level (input gradation value), and the vertical axis represents the Drop Ratio (drop rate). The Input Level represents the level of density. In terms of grayscale representation, 0% represents white and 100% represents black for the Input Level. The Drop Ratio indicates the usage ratio of the ejected droplets or dot sizes at that time. The Drop Ratio represents that 0% means not in use and 100% means filling the entire area with that dot.

[0064] In FIG. 5, "Small" represents a droplet or dot size, "Middle" represents a medium droplet or dot size, "Large" represents a large droplet or dot size, and "White Pixel" represents that no droplet has been hit.

[0065] In the example shown in FIG. 5, when the Input Level is 0%, Small, Middle, and Large are all 0%, indicating that no droplet has been hit. Therefore, White Pixel is 100%. Also, when the Input Level is 16.7%, since the usage ratio of Small is 50% and Middle and Large are 0%, White Pixel is 50%. Furthermore, when the Input Level is 50%, since the usage ratios of Small and Middle are each 50% and Large is 0%, White Pixel is 0%.

[0066] In the tone expression as shown in FIG. 5, the small dot size is used up to 100%, then replaced by the medium droplet, and when the medium droplet reaches 100%, it is replaced by the large droplet this time, so a smooth tone expression is possible.

[0067] However, in the example shown in FIG. 5, when the Input Level is 33%, White Pixel becomes 0%, and the airflow caused by the ejected droplets themselves becomes large.

[0068] In addition, when the distance from the nozzle of the liquid ejection head 122 to the medium 40 is short (usually about 1 - 2 mm), since it lands on the medium 40 before being affected by the airflow caused by the ejected droplets themselves, the influence on the landing position deviation and jet bending is minor. However, when the distance from the nozzle of the liquid ejection head 122 to the medium 40 becomes long, it is affected by the airflow caused by the ejected droplets themselves, resulting in landing position deviation, jet bending, etc. In particular, droplets with a relatively small droplet size like small droplets and medium droplets are more easily affected by the airflow caused by the ejected droplets themselves, and landing position deviation and jet bending are more likely to occur.

[0069] Therefore, in the present embodiment, the ejection airflow is suppressed, interference between ejection airflows is prevented, and the ejection droplets are suppressed from bending during ejection. This will be described in detail below.

[0070] Here, FIG. 6 shows the relationship between the Input Level and the Drop Ratio, and FIG. 7 shows the relationship between the Input Level and the Output Level. In FIG. 6, the horizontal axis represents the Input Level (input gradation value), and the vertical axis represents the Drop Ratio (drop ratio). In FIG. 7, the horizontal axis represents the Input Level (input gradation value), and the vertical axis represents the Output Level (ejection droplet amount of each droplet type).

[0071] The droplet types used for printing are controlled and replaced as shown in FIG. 6. For example, as shown in FIG. 6, the ejection control unit 212 converts the input image into dot data such that in the low gradation portion, the ratio of dots of small droplets and medium droplets in all dots is larger and the ratio of dots of large droplets in all dots is smaller than in the high gradation portion.

[0072] More specifically, as shown in FIG. 6, in the present embodiment, the ejection control unit 212 suppresses the usage ratio of small droplets and starts using medium droplets from 10% of the low Input Level. The ejection control unit 212 also reduces the usage ratio of small droplets from 10% of the Input Level at which medium droplets start to be used.

[0073] In the present embodiment, the ejection control unit 212 increases the Drop Ratio (ejection nozzle) for medium droplets up to 15%.

[0074] Similarly, in this embodiment, the ejection control unit 212 also suppresses the usage ratio of medium droplets and reduces the usage ratio of medium droplets starting from Input Level 13% at which large droplets begin to be used. The ejection control unit 212 stops the use of medium droplets at 15% before the Input Level reaches 100%. This control is because large droplets are less affected by the airflow compared to medium and small droplets, and large droplets spread more than medium and small droplets, so the appearance does not change.

[0075] Also, as shown in FIG. 7, when determining the usage ratio, it is desirable that the ratio of the Output Level to the Input Level has a substantially linear relationship. That is, the ejection control unit 212 controls so as not to decrease the ratio of the Output Level (the ejection droplet volume of each droplet type) as the Input Level (input gradation value) increases. The Output Level at this time may be the amount of liquid adhesion per unit area or the image density, etc. By making the Output Level to the Input Level have a linear relationship, it becomes possible to minimize the influence of gradation jumps in the γ curve or color matching for determining the final color tone, etc.

[0076] As described above, in the high gradation part of the input gradation value, the ejection control unit 212 ejects only the largest droplet among two or more types of droplets from the nozzles, and makes the number of nozzles that do not eject among all the nozzles include a part that increases without monotonically decreasing from the low gradation part to the high gradation part of the input gradation value.

[0077] In other words, in the high gradation part of the input gradation value, the ejection control unit 212 performs patterning only in terms of dot size, and makes it include a part where the ratio of pixels where dots are not arranged increases from the low gradation part to the high gradation part with respect to the input gradation value.

[0078] Here, in the graph shown in FIG. 6, the reason for the temporary increase in White Pixel when suppressing the usage ratio of small droplets and starting to use medium droplets from 10% of the low Input Level will be explained.

[0079] Here, FIG. 8 is a diagram showing a transition example of a white pixel. The grid shown in FIG. 8 corresponds to a white pixel. As shown in FIG. 8(a), conventionally, when increasing the drop ratio (discharge nozzle) with droplets, the empty grids, that is, the white pixels, will decrease. At this time, in the case where the drop ratio is 100%, it is the state of discharging from all nozzles. That is, in the case where the drop ratio is 100%, since it is discharging from many nozzles, it is in a state where it is easily affected by the air flow.

[0080] On the other hand, as shown in FIG. 8(b), in the present embodiment, by replacing the portions drawn with droplets with medium droplets or large droplets, the number of nozzles for discharging is reduced without changing the drawing density. By reducing the number of nozzles for discharging in this way, it becomes possible to reduce the influence of the air flow by the discharged droplets themselves.

[0081] Also, at the same time, when comparing with 100% of small droplets, when replaced with medium droplets or large droplets, the blank grids = white pixels will increase. That is, in the graph shown in FIG. 6, when suppressing the use ratio of small droplets and starting to use medium droplets from 10% of the low input level, the white pixels will increase temporarily.

[0082] According to this embodiment, the usage ratio of small droplets is suppressed. For example, medium droplets are started to be used from 10% of the low Input Level. From 10% of the Input Level at which medium droplets are started to be used, the usage ratio of small droplets is also decreased. The medium droplets are increased up to 15%, but the number of nozzles used with medium droplets can be reduced compared to the nozzles used with small droplets to ensure the same printing density. Moreover, at low printing density, by creating a portion where the white pixels increase, even though the printing density increases, the number of non-ejecting nozzles can be reduced. Compared to the droplet configuration where the number of non-ejecting nozzles does not decrease, the number of droplets ejected simultaneously can be reduced efficiently, the influence of the ejection airflow can be suppressed, and the interference between the ejection airflows can be prevented. Thereby, the deviation of the landing position and the bending of the ejected droplets can be suppressed, and the white streaks / black streaks at the joints of the head can be suppressed.

[0083] The program executed in the image forming apparatus 100 of this embodiment is provided by being recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disc) in an installable format or an executable format file.

[0084] Further, the program executed in the image forming apparatus 100 of this embodiment may be configured to be stored on a computer connected to a network such as the Internet and downloaded via the network. Further, the program executed in the image forming apparatus 100 of this embodiment may be configured to be provided or distributed via a network such as the Internet.

[0085] Further, the program executed in the image forming apparatus 100 of this embodiment may be configured to be provided by being pre-embedded in a ROM or the like.

[0086] The program executed by the image forming apparatus 100 according to the present embodiment has a module configuration including the above-described respective units (color separation data generation unit 211, ejection control unit 212). As actual hardware, the CPU (processor) reads the program from the storage medium and executes it, whereby the above-described respective units are loaded onto the main storage device, and the color separation data generation unit 211 and the ejection control unit 212 are generated on the main storage device.

[0087] (Second Embodiment) Next, a second embodiment will be described.

[0088] The second embodiment is different from the first embodiment in that the usage ratio and usage range of small droplets and medium droplets are expanded as compared with the first embodiment, and the increase amount of white pixels is reduced. In the following description of the second embodiment, the description of the same parts as those of the first embodiment will be omitted, and the parts different from those of the first embodiment will be described.

[0089] Here, FIG. 9 is a diagram showing the relationship between the input level and the drop ratio according to the second embodiment, and FIG. 10 is a diagram showing the relationship between the input level and the output level.

[0090] As shown in FIG. 9, in the present embodiment, the ejection control unit 212 suppresses the usage ratio of small droplets and starts using medium droplets from 10% of the low input level. The ejection control unit 212 also reduces the usage ratio of small droplets from 10% of the input level at which the use of medium droplets is started.

[0091] On the other hand, in the present embodiment, the ejection control unit 212 also expands the usage ratio of medium droplets and reduces the usage ratio of medium droplets from 20% of the input level at which large droplets are started to be used. The ejection control unit 212 stops using medium droplets when the input level reaches 30%.

[0092] Further, as shown in FIG. 10, the ejection control unit 212 has a substantially linear relationship between the Output Level and the Input Level. In this embodiment, the usage ratio and the usage range of medium droplets are larger than those in the first embodiment. However, the ratio of the Output Level to the Input Level is substantially linear, and the White Pixel also monotonically decreases from the low gradation part to the high gradation part.

[0093] The influence on the image such as black streaks / white streaks due to landing position deviation or ejection bending also varies depending on the liquid (ink) used, the medium 40, the distance from the nozzle to the medium 40, the printing speed, and the like. By reducing the usage ratio of small droplets and medium droplets, the influence of landing position deviation and ejection bending can be suppressed, but the image granularity tends to deteriorate. Therefore, it is necessary to balance according to the printing conditions.

[0094] Therefore, this embodiment aims to improve the granularity in the low gradation range more than the first embodiment.

[0095] Thus, according to this embodiment, the usage ratio and the usage range of small droplets and medium droplets are expanded more than those in the first embodiment, and the increase amount of the White Pixel is reduced. However, by making the Output Level with respect to the Input Level substantially linear, the White Pixel exists when the Input Level is other than 100%. At the same time, the number of droplets ejected can be suppressed, the influence of the ejection airflow can be suppressed, and the interference between the ejection airflows can be prevented. As a result, it is possible to suppress the landing position deviation and the ejection bending of the ejected droplets, and to suppress the white streaks / black streaks at the joints of the head.

[0096] (Third Embodiment) Next, the third embodiment will be described. Hereinafter, in the description of the third embodiment, the description of the same parts as those in the first embodiment and the second embodiment will be omitted, and the parts different from the first embodiment and the second embodiment will be described.

[0097] <Electrode Manufacturing Apparatus> The "device for discharging a liquid" according to the present invention also includes a manufacturing apparatus for electrodes and electrochemical elements. Hereinafter, the electrode manufacturing apparatus will be described.

[0098] FIG. 11 is a schematic diagram showing an example of an electrode manufacturing apparatus according to the third embodiment. The electrode manufacturing apparatus is an apparatus that manufactures an electrode including a layer having an electrode material by discharging a liquid composition using a head module including the liquid discharge head 122 described in the first and second embodiments.

[0099] <Forming Means for a Layer Containing an Electrode Material, Forming Step for a Layer Containing an Electrode Material> The discharging means provided in the electrode manufacturing apparatus shown in FIG. 11 is the head module according to the embodiment of the present invention. By discharging the liquid composition from the discharge head included in the head module, the liquid composition is applied onto the object, and a liquid composition layer is formed. The object (hereinafter, may be referred to as the "discharge object") is not particularly limited as long as it is an object on which a layer containing an electrode material is to be formed, and can be appropriately selected according to the purpose. For example, examples of the object include an electrode substrate (current collector), an active material layer, and a layer containing a solid electrode material. Further, the object may be an electrode composite layer containing an active material on an electrode substrate (current collector). Further, the discharging means and the discharging step may be means and steps for forming a layer having an electrode material by directly discharging the liquid composition as long as it is possible to form a layer having an electrode material on the discharge object. Further, the discharging means and the discharging step may be means and steps for forming a layer having an electrode material by indirectly discharging the liquid composition.

[0100] <Other Configurations, Other Steps> As other components included in the manufacturing apparatus for the electrode composite material layer, there are no particular limitations as long as the effects of the present invention are not impaired, and they can be appropriately selected according to the purpose. Similarly, other steps included in the manufacturing method for the electrode composite material layer also have no particular limitations as long as the effects of the present invention are not impaired, and they can be appropriately selected according to the purpose. For example, as components and steps included in the manufacturing apparatus and manufacturing method for the electrode composite material layer, heating means and a heating step can be mentioned.

[0101] <Heating means, heating step> The heating means included in the manufacturing apparatus for the electrode composite material layer is means for heating the liquid composition discharged by the discharging means. Also, the heating step included in the manufacturing method for the electrode composite material layer is a step of heating the liquid composition discharged in the discharging step. By heating the liquid composition, the liquid composition layer can be dried.

[0102] <Configuration for forming a layer containing an electrode material by directly discharging a liquid composition> Here, as an example of the manufacturing apparatus for an electrode, a manufacturing apparatus for an electrode that forms an electrode composite material layer containing an active material on an electrode substrate (current collector) will be described. As shown in FIG. 11, the manufacturing apparatus for an electrode includes a discharging process section 140 that includes a step of applying a liquid composition onto a printing substrate 704 having an object to be discharged to form a liquid composition layer, and a heating process section 130 that includes a heating step of heating the liquid composition layer to obtain an electrode composite material layer.

[0103] The manufacturing apparatus for an electrode includes a conveying section 705 that conveys the printing substrate 704. The conveying section 705 conveys the printing substrate 704 at a preset speed in the order of the discharging process section 140 and the heating process section 130. As the manufacturing method for the printing substrate 704 having an object to be discharged such as an active material layer, there are no particular limitations, and a known method can be appropriately selected. The discharging process section 140 includes a liquid discharge head 122 that realizes an application step of applying a liquid composition onto the printing substrate 704, a storage container 281b that stores the liquid composition 707, and a supply tube 281c that supplies the liquid composition 707 stored in the storage container 281b to the liquid discharge head 122.

[0104] In the ejection engineering department 140, the liquid composition 707 is ejected from the liquid ejection head 122, and the liquid composition 707 is applied onto the printing substrate 704, thereby forming a liquid composition layer in a thin film shape. Note that the storage container 281b may be configured to be integrated with the manufacturing apparatus for the electrode paste layer, or may be configured to be removable from the manufacturing apparatus for the electrode paste layer. Further, the storage container 281b may be a container used for adding to a storage container integrated with the manufacturing apparatus for the electrode paste layer or a storage container removable from the manufacturing apparatus for the electrode paste layer.

[0105] The storage container 281b and the supply tube 281c can be arbitrarily selected as long as they can stably store and supply the liquid composition 707.

[0106] In the heating engineering department 130, a solvent removal process is performed to heat and remove the solvent remaining in the liquid composition layer. Specifically, the solvent remaining in the liquid composition layer is heated and dried by the heating device 703 in the heating engineering department 130, thereby removing the solvent from the liquid composition layer. Thereby, the electrode paste layer is formed. Further, the solvent removal process in the heating engineering department 130 may be performed under reduced pressure.

[0107] There is no particular limitation on the heating device 703, and it can be appropriately selected according to the purpose. For example, examples of the heating device 703 include substrate heating, an IR heater, and a hot air heater. Further, the heating device 703 may be a combination of at least two of substrate heating, an IR heater, and a hot air heater. Further, regarding the heating temperature and the heating time, they can be appropriately selected according to the boiling point of the solvent contained in the liquid composition 707 or the formed film thickness.

[0108] By using the manufacturing apparatus for an electrode according to an embodiment of the present invention, the liquid composition can be ejected to a target position of the ejection object. The electrode paste layer can be suitably used, for example, as a part of the configuration of an electrochemical element. There is no particular limitation on the configuration other than the electrode paste layer in the electrochemical element, and known ones can be appropriately selected. For example, examples of the configuration other than the electrode paste layer include a positive electrode, a negative electrode, and a separator.

[0109] In the present application, the "device for discharging a liquid" includes a liquid discharge head 122 or a liquid discharge unit, and is a device that drives the liquid discharge head 122 to discharge the liquid. The device for discharging a liquid includes not only a device capable of discharging the liquid onto an object to which the liquid can adhere, but also a device capable of discharging the liquid into the air or into a liquid.

[0110] This "device for discharging a liquid" can also include means related to the feeding, conveying, and paper discharging of an object to which the liquid can adhere, as well as other pretreatment devices, post-treatment devices, and the like.

[0111] For example, as the "device for discharging a liquid", there are an image forming device that discharges ink to form an image on paper, and a three-dimensional modeling device (three-dimensional shaping device) that discharges a shaping liquid onto a powder layer formed by layering powder in order to model a three-dimensional object (three-dimensional shaped object).

[0112] In addition, the "device for discharging a liquid" is not limited to those in which a significant image such as characters or figures is visualized by the discharged liquid. For example, those that form a pattern having no meaning by itself, and those that model a three-dimensional image are also included.

[0113] The above-mentioned "object to which the liquid can adhere" means an object to which the liquid can adhere at least temporarily, and includes those that adhere and adhere firmly, those that adhere and penetrate, etc. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, media such as inspection cells, and include all objects to which the liquid adheres unless otherwise particularly limited.

[0114] The material of the above-mentioned "object to which the liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as the liquid can adhere even temporarily.

[0115] Further, the "liquid" may be any liquid that can be discharged from the liquid discharge head 122, and is not particularly limited, but preferably has a viscosity of 30 mPa·s or less at normal temperature and pressure, or by heating or cooling. More specifically, it includes solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional material-imparting materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, and edible materials such as natural pigments, etc., and these can be used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic elements and light-emitting elements, and liquids for forming electronic circuit resist patterns, and material liquids for three-dimensional modeling.

[0116] In addition, the "device for discharging a liquid" includes, but is not limited to, a device in which the liquid discharge head 122 and an object to which the liquid can adhere move relative to each other. Specific examples include a serial type device that moves the liquid discharge head 122 and a line type device that does not move the liquid discharge head 122.

[0117] In addition, other examples of the "device for discharging a liquid" include a treatment liquid application device that discharges a treatment liquid onto paper for the purpose of modifying the surface of the paper, and an injection granulation device that granulates fine particles of raw materials by injecting a composition liquid in which the raw materials are dispersed in a solution through a nozzle.

[0118] Aspects of the present invention are as follows, for example. <1> In a liquid discharge head that selectively discharges two or more types of droplets with different discharge droplet amounts from a nozzle to perform tone expression with a concentration corresponding to an input tone value, in the high tone portion of the input tone value, only the largest droplet among the two or more types of droplets is discharged from the nozzle, and a discharge control unit is provided that controls so as to include a portion where the number of nozzles that do not discharge among all the nozzles increases without monotonically decreasing from the low tone portion to the high tone portion of the input tone value. A liquid discharge head characterized by the above. <2> The ejection control unit controls so as not to decrease the ratio of the ejection droplet volume as the input gradation value increases. The liquid ejection head according to <1>, characterized in that. <3> The ejection control unit controls so as to eject only the smallest droplet among the two or more types of droplets at 13% or less of the input gradation value. The liquid ejection head according to <1> or <2>, characterized in that. <4> The ejection control unit controls so as to eject only the smallest droplet among the two or more types of droplets at 10% or less of the input gradation value. The liquid ejection head according to any one of <1> to <3>, characterized in that. <5> It selectively ejects three or more types of droplets having different ejection droplet volumes from the nozzles, The ejection control unit controls so as to eject the second smallest droplet among the three or more types of droplets at 15% or less of the input gradation value. The liquid ejection head according to <1> or <2>, characterized in that. <6> For the part where the number of the nozzles that do not eject among all the nozzles decreases from the low gradation part to the high gradation part of the input gradation value, the ejection control unit controls so that at least one place exists at 20% or less of the input gradation value. The liquid ejection head according to <1> or <2>, characterized in that. <7> For the part where the number of the nozzles that do not eject among all the nozzles decreases from the low gradation part to the high gradation part of the input gradation value, the ejection control unit controls so as to eject at least two or more types of droplets having different sizes. The liquid ejection head according to <1> or <2>, characterized in that. <8> The liquid ejection head according to any one of <1> to <7>, and at least any one of a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, and a main scanning movement mechanism, A liquid ejection unit characterized by comprising. <9> The liquid discharge head according to any one of <1> to <7>, a control unit that drives the liquid discharge head to discharge a liquid, and a device for discharging a liquid, characterized by comprising the same. <10> A liquid discharge method in a liquid discharge head that selectively discharges two or more types of droplets having different discharge droplet amounts from nozzles to perform gradation expression of a density corresponding to an input gradation value, wherein in a high gradation portion of the input gradation value, only the largest droplet among the two or more types of droplets is discharged from the nozzles, and a discharge control step is included for controlling so as to include a portion where the number of the nozzles that do not discharge among all the nozzles increases without monotonically decreasing from a low gradation portion to a high gradation portion of the input gradation value. A liquid discharge method characterized by the above. <11> A computer that controls a liquid discharge head that selectively discharges two or more types of droplets having different discharge droplet amounts from nozzles to perform gradation expression of a density corresponding to an input gradation value, wherein in a high gradation portion of the input gradation value, only the largest droplet among the two or more types of droplets is discharged from the nozzles, and the computer functions as a discharge control unit for controlling so as to include a portion where the number of the nozzles that do not discharge among all the nozzles increases without monotonically decreasing from a low gradation portion to a high gradation portion of the input gradation value. A program characterized by the above.

Explanation of Signs

[0119] 100 Device for discharging a liquid 101 Control unit 122 Liquid discharge head 212 Discharge control unit

Prior Art Documents

Patent Documents

[0120]

Patent Document 1

Claims

1. In a liquid ejection head that selectively ejects two or more types of droplets having different ejection droplet volumes from a nozzle to perform gradation expression of a concentration according to an input gradation value, in a high gradation portion of the input gradation value, only the largest droplet among the two or more types of droplets is ejected from the nozzle, and a number of the nozzles that do not eject among all the nozzles increases without monotonically decreasing from a low gradation portion to a high gradation portion of the input gradation value, and a discharge control unit for controlling to include a portion is provided. A liquid ejection head characterized by the above.

2. The discharge control unit controls so that a ratio of an ejection droplet volume does not decrease as the input gradation value increases. The liquid ejection head according to claim 1, characterized by the above.

3. The discharge control unit controls to eject the smallest droplet among the two or more types of droplets only at 13% or less of the input gradation value. The liquid ejection head according to claim 1, characterized by the above.

4. The discharge control unit controls to eject the smallest droplet among the two or more types of droplets only at 10% or less of the input gradation value. The liquid ejection head according to claim 1, characterized by the above.

5. Three or more types of droplets having different ejection droplet volumes are selectively ejected from the nozzle, and the discharge control unit controls to eject the second smallest droplet among the three or more types of droplets at 15% or less of the input gradation value. The liquid ejection head according to claim 1, characterized by the above.

6. For a portion where the number of the nozzles that do not eject among all the nozzles decreases from a low gradation portion to a high gradation portion of the input gradation value, the discharge control unit controls so that at least one place exists at 20% or less of the input gradation value. The liquid ejection head according to claim 1, characterized by the above.

7. For a portion where the number of the nozzles that do not eject among all the nozzles decreases from a low gradation portion to a high gradation portion of the input gradation value, the discharge control unit controls to eject at least two or more types of droplets having different sizes. The liquid ejection head according to claim 1, characterized by the above.

8. The liquid ejection head according to any one of claims 1 to 7, and at least any one of a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, and a main scanning movement mechanism. A liquid ejection unit characterized by including the above.

9. The liquid ejection head according to any one of claims 1 to 7, a control unit that drives the liquid ejection head to eject liquid; An apparatus for ejecting liquid, characterized by comprising the above.

10. A liquid ejection method in a liquid ejection head that selectively ejects two or more types of droplets with different ejection droplet amounts from nozzles to perform tone expression of a density corresponding to an input tone value, comprising: a discharge control step of discharging only the largest droplet among the two or more types of droplets from the nozzle in a high tone portion of the input tone value, and controlling so as to include a portion where the number of nozzles that do not discharge among all the nozzles increases without monotonically decreasing from a low tone portion to a high tone portion of the input tone value; A liquid ejection method characterized by the above.

11. A computer that controls a liquid ejection head that selectively ejects two or more types of droplets with different ejection droplet amounts from nozzles to perform tone expression of a density corresponding to an input tone value, functioning as a discharge control unit that discharges only the largest droplet among the two or more types of droplets from the nozzle in a high tone portion of the input tone value, and controls so as to include a portion where the number of nozzles that do not discharge among all the nozzles increases without monotonically decreasing from a low tone portion to a high tone portion of the input tone value; A program characterized by the above.

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