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

Abstract

To suppress discharged airflow, prevent the discharged airflow from interfering with each other and suppress discharged droplets from being jetted veeringly.SOLUTION: A liquid discharge head, which selectively discharges two or more kinds of droplets whose discharged droplet volumes are different from each other from nozzles to perform gradation expression with densities corresponding to an input gradation value, is provided with a discharge control part that makes the nozzles discharge only a largest droplet of the two or more kinds of droplets, at a high gradation part of the input gradation value, and performs control so that the number of the nozzles that cannot discharge droplets of all of the nozzles decreases monotonically from a low gradation part toward the high gradation part, in the input gradation value.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Patent Document 1 discloses a head control method and image processing technology that uses a liquid ejection head to eject droplets of different ejection volumes (large, medium, small, etc.) to express density gradations. More specifically, Patent Document 1 discloses a technology that expresses low gradation areas with small dot sizes using small droplets, reduces the ratio of small dot sizes and mixes in medium dot sizes using medium droplets in intermediate gradation areas, and reduces the ratio of medium dot sizes and mixes in large dots using large droplets in high gradation areas.

[0003] Patent Document 2 discloses a technique for an inkjet recording device in which, when the density gradation value set in the image data is low, the ejected dots are composed of only small droplets, but as the density gradation value increases, the proportion of large droplets is increased. According to the technique disclosed in Patent Document 2, the area covered by ink in a recorded image, i.e., the number of ejected dots per unit area, increases as the density gradation value (gradation value) set in the image data increases. Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional technology, when the number of droplets discharged simultaneously increases to express gradations, the air currents generated by the droplets themselves interfere with each other, causing the droplets to bend. This problem becomes more pronounced the greater the distance between the nozzles of the liquid discharge head and the recording medium, such as paper.

[0005] Specifically, if satellites or the like are formed in the ejected droplets, the satellites are carried away by the air current and land on the nozzles, resulting in unevenness like wood grain. Also, at the nozzles at the ends of the liquid ejection head, the air current that is affected is biased, making the landing position more likely to shift (bend). In particular, when printing with multiple liquid ejection heads lined up, white / black streaks are more likely to occur at the joints between the liquid ejection heads.

[0006] In addition, when expressing gradations, it is ideal that the number of ejection dots increases monotonically, in other words, the number of non-ejecting nozzles decreases monotonically, as one moves from low to high gradations. However, according to the technology disclosed in Patent Document 2, the number of ejection dots does not increase monotonically (the number of non-ejecting nozzles does not decrease monotonically), which makes it difficult to maintain the continuity of gradations.

[0007] The present invention has been made in view of the above, and has an object to suppress ejection air currents, prevent interference between the ejection air currents, and suppress deflection of ejected droplets. [Means for solving the problem]

[0008] In order to solve the above-mentioned 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 volumes from a nozzle to express a gradation of density according to an input gradation value, the liquid ejection head being equipped with an ejection control unit that ejects only the largest droplet of the two or more types of droplets from the nozzle in the high gradation part of the input gradation value, and controls so that the number of nozzles that do not eject among all the nozzles monotonically decreases from the low gradation part to the high gradation part of the input gradation value. Effect of the Invention

[0009] According to the present invention, it is possible to suppress the discharge air currents, prevent interference between the discharge air currents, and suppress deflection of the discharged droplets. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing the inside of an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an outline of the configuration of the image forming apparatus. [Diagram 3] FIG. 3 is a block diagram showing an example of a hardware configuration of the image forming apparatus. [Figure 4] FIG. 4 is a block diagram illustrating an example of a functional configuration of the control unit. [Diagram 5] FIG. 5 is a diagram showing the relationship between the Input Level and the Drop Ratio. [Figure 6] FIG. 6 is a diagram showing the relationship between Input Level and Output Level. [Figure 7] FIG. 7 is a diagram showing the relationship between the input level and the brightness. [Figure 8] FIG. 8 is a diagram showing the relationship between the Input Level and the Drop Ratio according to the second embodiment. [Figure 9] FIG. 9 is a diagram showing the relationship between Input Level and Output Level. [Figure 10] FIG. 10 is a diagram showing the relationship between the Input Level and the Drop Ratio according to the third embodiment. [Figure 11] FIG. 11 is a diagram showing the relationship between Input Level and Output Level. [Figure 12] FIG. 12 is a diagram showing the relationship between the Input Level and the Drop Ratio according to the fourth embodiment. [Figure 13] FIG. 13 is a diagram showing the relationship between Input Level and Output Level. [Figure 14] FIG. 14 is a diagram showing the relationship between the Input Level and the Drop Ratio according to the fifth embodiment. [Figure 15] FIG. 15 is a diagram showing the relationship between Input Level and Output Level. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the accompanying drawings, embodiments of a liquid ejection head, a liquid ejection unit, a liquid ejection device, a liquid ejection method, and a program will be described in detail.

[0012] An image forming apparatus, which is one aspect of a device that ejects liquid, will be described below as an example of a device that ejects liquid to which the present invention can be applied, but the present invention is not limited to this.

[0013] (First embodiment) Fig. 1 is a perspective view showing the inside of an image forming apparatus 100 according to a first embodiment. 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 this embodiment is a wide-width serial type inkjet recording apparatus.

[0014] In this embodiment, an example will be described in which the liquid ejecting device of the present invention is applied to a wide serial type inkjet, but the device can be applied to any image forming device such as a multifunction device, copier, printer, scanner device, facsimile device, etc. that has at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function.

[0015] 1 and 2, the image forming apparatus 100 includes side plates 21A and 21B on the left and right sides of an apparatus body 100a. The side plates 21A and 21B 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 hold the carriage 121 so that it can slide freely.

[0016] The carriage 121 moves in the direction of arrow G (carriage main scanning direction) via a timing belt that is driven to rotate by a main scanning motor 117 (see FIG. 3), thereby moving relatively to the medium 40. The movement of the carriage 121 can also be referred to as scanning. The carriage 121 also has an optical sensor 37 mounted thereon that detects the edge of the medium 40 (paper edge).

[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 in the image based on the reading signal by the optical sensor 37. As the optical sensor 37, a device that detects by reflection density, a camera that captures the image formed on the medium 40, or the like can be used. Note that in this embodiment, an abnormality in the image also includes a sign of an abnormality that is a state in which an abnormality is likely to occur.

[0018] The carriage 121 is equipped with liquid ejection heads 122a, 122b, and 122c (when no distinction is required, these three liquid ejection heads 122a, 122b, and 122c are collectively referred to as "liquid ejection heads 122") that eject ink droplets (liquid) of each color, such as yellow (Y), cyan (C), magenta (M), black (K), orange (O), green (G), and clear (Cl), depending on the installed ink cartridge 10.

[0019] The medium 40 moves along a sub-scanning direction (direction of arrow H) that is substantially perpendicular to the main scanning direction using a transport roller that is rotationally driven by a sub-scanning motor 118 (see FIG. 3), thereby moving relatively to the liquid ejection head 122. However, the main scanning direction and the sub-scanning direction do not necessarily have to be substantially perpendicular to each other, as long as they intersect.

[0020] The liquid ejection head 122 has a nozzle row made up of a plurality of nozzles (not shown) arranged in the sub-scanning direction. The liquid ejection head 122 is mounted so that the ink droplets ejected from the nozzles face downward. The liquid ejection heads 122a, 122b, and 122c are installed so as to be shifted from one another in the sub-scanning direction. The carriage 121 is equipped with sub-tanks to supply ink of each color to the liquid ejection heads 122.

[0021] The "liquid ejection head" is a functional component that ejects and sprays liquid from a nozzle. The ejected liquid may have a viscosity and surface tension that allows it to be ejected from the liquid ejection head 122, and is not particularly limited. However, it is preferable that the viscosity of the ejected liquid is 30 mPa·s or less at room temperature and pressure, or by heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, etc. that contains a solvent such as water or an organic solvent, a colorant such as a dye or a pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, calcium, an edible material such as a natural colorant, etc., and these can be used for applications such as inkjet ink, surface treatment liquid, a liquid for forming a component of an electronic element or a light-emitting element, an electronic circuit resist pattern, a material liquid for three-dimensional modeling, etc.

[0022] The energy source for discharging liquid includes those that use piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements).

[0023] Furthermore, the pressure generating means used in the "liquid ejection head" is not limited. For example, in addition to the above-mentioned piezoelectric actuator (which may use a laminated piezoelectric element), a thermal actuator using an electrothermal conversion element such as a heating resistor, or an electrostatic actuator consisting of a vibration plate and an opposing electrode may be used.

[0024] The image forming apparatus 100 includes a cartridge loading section 1 into which ink cartridges 10y, 10c, 10m, and 10k of each color (referred to as "ink cartridges 10" when no distinction is made) are detachably mounted.

[0025] The ink in the ink cartridges 10 is replenished and supplied to the sub-tanks of the carriage 121 through the supply tubes 36 of each color by the supply pump units. The supply pump units and the supply tubes 36 constitute a supply mechanism. The ink cartridges 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 ejection head 122.

[0027] The maintenance and recovery mechanism 81 includes cap members 82a, 82b, and 82c (referred to as "cap members 82" when no distinction is made) for capping the nozzle faces of the liquid ejection head 122, and a wiping unit 83 for wiping the nozzle faces. In addition, below the maintenance and recovery mechanism 81 for the liquid ejection head 122, a replaceable waste liquid tank is provided for storing waste liquid generated by the maintenance and recovery operation.

[0028] The "liquid ejection unit" is a collection of parts related to ejecting liquid, in which functional parts and mechanisms are integrated with the liquid ejection head 122. For example, the "liquid ejection unit" includes a combination of at least one of the following components with the liquid ejection head 122: a head tank (a sub-tank for the carriage 121), the carriage 121, a supply mechanism, a maintenance and recovery mechanism 81, and a main scanning movement mechanism.

[0029] Here, integration includes, for example, the liquid ejection head 122 and the functional parts or mechanisms being fixed to each other by fastening, bonding, engagement, etc., or one being held movably relative to the other. Also, the liquid ejection head 122 and the functional parts or mechanisms may be configured to be detachable from each other.

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

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

[0032] In some liquid ejection units, 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 together. In other liquid ejection units, the liquid ejection head 122, a carriage, and the main scanning movement mechanism are integrated together.

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

[0034] In addition, there is a liquid ejection unit 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 a supply mechanism are integrated. Liquid from a liquid storage source is supplied to the liquid ejection head 122 via this tube.

[0035] The main scanning movement mechanism includes the main guide rod 31 alone, which is a guide member. The supply mechanism includes the supply tube 36 alone and the cartridge loading unit 1 alone.

[0036] Fig. 3 is a block diagram showing an example of a 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] 3, the control unit 101 has 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 components 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 each other so as to be able to communicate with each other, for example, via a bus or the like.

[0039] The CPU 102 controls the overall operation of the image forming apparatus 100. Specifically, the CPU 102 executes programs stored in the ROM 103 or the like to realize various functions.

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

[0041] The I / F 107 is an interface circuit that transmits and receives 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 device, an image reading device, or an imaging device via a cable, a network, or the like. In other words, the print data may be generated and output to the control unit 101 by a printer driver on the host side.

[0042] The print control unit 108 is a circuit that generates a drive waveform for driving the liquid ejection head 122, and outputs print data and various associated data to the head driver 116, which selects and drives a pressure generating means that generates pressure for the liquid ejection head 122 to eject liquid (ink) from the nozzles.

[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 volume.

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

[0045] The operation panel 114 is a device for inputting and displaying various information such as a user's specification of a resolution, etc. The operation panel 114 is connected to the CPU 102 and the like via a bus of the control unit 101 so as to be able to communicate with each other.

[0046] The environmental sensor 115 is a sensor that detects, for example, the environmental temperature, the environmental humidity, etc. The environmental 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 constituting a drive waveform provided by the print control unit 108 to the pressure generating means of the liquid ejection head 122 based on input image data (e.g., dot pattern data). The head driver 116 is connected to the print control unit 108 of the control unit 101. Note that the ejection amount is controlled, for example, by controlling the amplitude of the drive waveform input to the pressure generating means of the liquid ejection head 122, but the ejection amount may be controlled using other means.

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

[0049] The sub-scanning motor 118 is a device that, when driven, operates a transport roller that transports in the sub-scanning direction the medium 40, which is an object onto which liquid (ink) is ejected by the liquid ejection head 122. The sub-scanning motor 118 is connected to a sub-scanning motor drive unit 110 of the control unit 101.

[0050] The movement mechanism 140 moves the liquid ejection head 122 relative to the medium 40. The movement mechanism 140 includes the main guide rod 31, the sub sheet metal guide 32, the carriage 121, the transport rollers, and the like, and constitutes a main scanning movement mechanism.

[0051] The movement mechanism 140 moves the liquid ejection head 122 and the medium 40 relatively along the main scanning direction using the main guide rod 31, the sub metal sheet guide 32, the carriage 121, etc. The movement mechanism 140 also moves the liquid ejection head 122 and the medium 40 relatively along the sub-scanning direction using a transport roller that transports the medium 40, etc. In this embodiment, the relative movement in the sub-scanning direction by the movement mechanism 140 is intermittent movement. Intermittent movement refers to movement that alternates between moving and stopping.

[0052] Fan 119 is a device that, when driven, promotes air convection inside image forming apparatus 100 and prevents an excessive temperature rise due to stagnation of heated air at the upper part of image forming apparatus 100. Fan 119 is connected to fan control unit 111 of control unit 101.

[0053] Fig. 4 is a block diagram showing an example of the functional configuration of the control unit 101. Note that a description of components that overlap with those in Fig. 3 will be omitted.

[0054] 4, the control unit 101 includes a color plane division data generating unit 211 and an ejection control unit 212. The ejection control unit 210 controls the ejection of ink.

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

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

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

[0058] In this embodiment, the dot data has four gradations including small dots, large dots having a larger amount than the small dots, and medium dots having a larger amount than the small dots and a smaller amount than the large dots. In this embodiment, an example is shown in which the ejection amount of small droplets is 6 pL, the ejection amount of medium droplets is 12 pL, and the ejection amount of large droplets is 18 pL.

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

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

[0061] The control unit 101 controls the liquid ejection head 122 and the movement mechanism 140 so as to place ink on the medium 40 while moving the liquid ejection head 122 and the medium 40 relative to each other multiple times. The ink placed on the medium 40 forms a dot in the image by being fixed on the medium 40. More specifically, one ink droplet formed by the ink ejected from the liquid ejection head 122 lands on the medium 40, dries, and is fixed on the medium 40 to form one dot in the image. The image is formed as a collection of multiple dots.

[0062] Next, an example of how the ejection control unit 212 ejects dots according to the dot type (hereinafter, referred to as droplet type) will be described.

[0063] Here, Fig. 5 shows the relationship between Input Level and Drop Ratio, Fig. 6 shows the relationship between Input Level and Output Level, and Fig. 7 shows the relationship between Input Level and brightness. In Fig. 5, the horizontal axis represents Input Level (input gradation value), and the vertical axis represents Drop Ratio (drop rate). In Fig. 6, the horizontal axis represents Input Level (input gradation value), and the vertical axis represents Output Level (ejected droplet amount of each droplet type). In Fig. 7, the horizontal axis represents Input Level (input gradation value), and the vertical axis represents image brightness.

[0064] The droplet types used in printing are controlled and replaced as shown in Fig. 5. For example, as shown in Fig. 5, the discharge control unit 212 converts the input image into dot data so that in low gradation areas, the proportion of small and medium droplets among all dots is greater than in high gradation areas, and the proportion of large droplets among all dots is smaller.

[0065] 5, in this embodiment, the discharge control unit 212 suppresses the use ratio of small droplets and starts using medium droplets from 10% of the low Input Level. The discharge control unit 212 also reduces the use ratio of small droplets from 10% of the Input Level where the use of medium droplets begins.

[0066] Similarly, in this embodiment, the discharge control unit 212 also suppresses the usage ratio of medium drops, lowering the usage ratio of medium drops from the Input Level of 30% where large drops start to be used. The discharge control unit 212 stops using medium drops at 70% before the Input Level reaches 100%. This control is performed because large drops are less susceptible to the effect of air currents than medium and small drops, and because large drops spread out more than medium and small drops, the appearance remains the same.

[0067] In addition, as shown in FIG. 6, when determining the usage ratio, it is desirable that the ratio of the output level to the input level has an approximately linear relationship. The output level in this case may be the amount of liquid attached per unit area, or may be image brightness as shown in FIG. 7. In the case of brightness, the brightness decreases with respect to the input level. By making the output level have a linear relationship with the input level, it is possible to minimize the influence of gradation jumps in the gamma curve and color matching for determining the final color tone. Alternatively, the ratio of the output level to the input level may have an approximately linear relationship as a result of gamma correction and color matching.

[0068] At this time, the discharge control unit 212 makes the white pixel monotonically decrease with respect to the input level. In other words, the discharge control unit 212 makes the ratio of the white pixel gradually decrease as the input level increases. The gradual decrease in the ratio of the white pixel indicates that the ratio of the large droplets, medium droplets, and small droplets used for image formation gradually increases, and it becomes easier to maintain the continuity of the gradation of the output level with respect to the input level.

[0069] In this way, according to this embodiment, by using the ratio of large, medium, and small droplets as described above, white pixels exist at input levels other than 100%, reducing the number of droplets ejected simultaneously, suppressing the effects of the ejected air currents, and preventing interference between the ejected air currents. This makes it possible to suppress deviations in landing positions and deflections in the ejected droplets, as well as white / black streaks at the joints of the heads.

[0070] The program executed by the image forming apparatus 100 of this embodiment is provided in an installable or executable format file recorded on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disc).

[0071] The program executed by the image forming apparatus 100 of the present embodiment may be stored in a computer connected to a network such as the Internet and provided by being downloaded via the network. The program executed by the image forming apparatus 100 of the present embodiment may be provided or distributed via a network such as the Internet.

[0072] Furthermore, the programs executed by image forming apparatus 100 of the present embodiment may be provided by being pre-installed in a ROM or the like.

[0073] The program executed by the image forming apparatus 100 of this embodiment has a modular structure including the above-mentioned units (color plate split data generation unit 211, ejection control unit 212), and in terms of actual hardware, the CPU (processor) reads the program from the above-mentioned storage medium and executes it, thereby loading the above-mentioned units onto the main memory device, and the color plate split data generation unit 211 and ejection control unit 212 are generated on the main memory device.

[0074] (Second embodiment) Next, a second embodiment will be described.

[0075] The second embodiment differs from the first embodiment in that it aims to improve the granularity in the mid-range more than the first embodiment. In the following description of the second embodiment, the description of the same parts as the first embodiment will be omitted, and only the parts that differ from the first embodiment will be described.

[0076] Here, FIG. 8 is a diagram showing the relationship between the Input Level and the Drop Ratio according to the second embodiment, and FIG. 9 is a diagram showing the relationship between the Input Level and the Output Level.

[0077] 8, in this embodiment, the discharge control unit 212 suppresses the use ratio of small droplets, and starts using medium droplets from 10% of the low Input Level. The discharge control unit 212 also reduces the use ratio of small droplets from 10% of the Input Level where the use of medium droplets begins.

[0078] On the other hand, in this embodiment, the discharge control unit 212 also increases the usage ratio of medium drops, and decreases the usage ratio of medium drops from the Input Level of 40% where the use of large drops begins. The discharge control unit 212 stops the use of medium drops at 80% before the Input Level reaches 100%.

[0079] 9, the discharge control unit 212 sets the ratio of the output level to the input level in a substantially linear relationship. In this embodiment, the usage ratio and range of medium drops are expanded compared to the first embodiment, but the ratio of the output level to the input level is substantially linear, and the white pixel also monotonically decreases from the low gradation area to the high gradation area.

[0080] The impact on an image, such as black or white streaks caused by misaligned landing positions or deflected jetting, varies depending on the liquid (ink) used, the recording medium, the distance from the nozzle to the recording medium, the printing speed, etc. By reducing the ratio of small and medium droplets used, the impact of misaligned landing positions and deflected jetting can be suppressed, but this tends to worsen the graininess of the image, so a balance must be achieved depending on the printing conditions.

[0081] Therefore, the present embodiment aims to improve the granularity in the mid-range more than the first embodiment.

[0082] In this way, according to this embodiment, by using the ratio of large, medium, and small droplets as described above, white pixels exist at input levels other than 100%, reducing the number of droplets ejected simultaneously, suppressing the effects of the ejected air currents, and preventing interference between the ejected air currents. This makes it possible to suppress deviations in landing positions and deflections in the ejected droplets, as well as white / black streaks at the joints of the heads.

[0083] (Third embodiment) Next, a third embodiment will be described.

[0084] The third embodiment differs from the first or second embodiment in that the ratio of small droplets used is reduced compared to the first or second embodiment. In the following description of the third embodiment, the description of the same parts as the first or second embodiment will be omitted, and only the parts that differ from the first or second embodiment will be described.

[0085] Here, FIG. 10 is a diagram showing the relationship between the Input Level and the Drop Ratio according to the third embodiment, and FIG. 11 is a diagram showing the relationship between the Input Level and the Output Level.

[0086] 10, in this embodiment, the discharge control unit 212 suppresses the use ratio of small droplets, and starts using medium droplets from 5% of the low Input Level. The discharge control unit 212 also reduces the use ratio of small droplets from 5% of the Input Level where the use of medium droplets begins.

[0087] In this embodiment, the discharge control unit 212 reduces the usage ratio of medium drops from the Input Level of 20%, when the use of large drops begins. The discharge control unit 212 stops the use of medium drops when the Input Level is 50%, before it reaches 100%.

[0088] 11, the discharge control unit 212 sets the ratio of the output level to the input level in a substantially linear relationship. In this embodiment, the ratio of small droplets used is reduced compared to the first and second embodiments, but the ratio of the output level to the input level is substantially linear, and the white pixel also monotonically decreases from the low gradation area to the high gradation area.

[0089] As described above, the use ratio of small droplets is reduced compared to the first and second embodiments in order to improve the deviation of the landing position and the deflection of the jet in low gradation areas.

[0090] In this way, according to this embodiment, by using the ratio of large, medium, and small droplets as described above, white pixels exist at input levels other than 100%, reducing the number of droplets ejected simultaneously, suppressing the effects of the ejected air currents, and preventing interference between the ejected air currents. This makes it possible to suppress deviations in landing positions and deflections in the ejected droplets, as well as white / black streaks at the joints of the heads.

[0091] (Fourth embodiment) Next, a fourth embodiment will be described.

[0092] The fourth embodiment differs from the first or second embodiment in that the ratio of small and medium droplets used is reduced compared to the first or second embodiment. In the following description of the fourth embodiment, the description of the same parts as the first or second embodiment will be omitted, and only the parts that differ from the first or second embodiment will be described.

[0093] Here, FIG. 12 is a diagram showing the relationship between the Input Level and the Drop Ratio according to the fourth embodiment, and FIG. 13 is a diagram showing the relationship between the Input Level and the Output Level.

[0094] 12, in this embodiment, the discharge control unit 212 suppresses the use ratio of small droplets and starts using medium droplets from 5% of the low Input Level. The discharge control unit 212 also reduces the use ratio of small droplets from 5% of the Input Level where the use of medium droplets begins.

[0095] On the other hand, in this embodiment, the discharge control unit 212 also suppresses the usage ratio of medium drops, lowering the usage ratio of medium drops from the Input Level of 15%, where the use of large drops begins. The discharge control unit 212 stops the use of medium drops at 30%, before the Input Level reaches 100%.

[0096] 13, the discharge control unit 212 sets the ratio of the output level to the input level in a substantially linear relationship. In this embodiment, the ratio of small and medium droplets used is reduced compared to the first and second embodiments, but the ratio of the output level to the input level is substantially linear, and the white pixel also monotonically decreases from the low gradation area to the high gradation area.

[0097] As described above, the use ratio of small and medium droplets is reduced compared to the first and second embodiments in order to improve the deviation of the landing position and the deflection of the jet in low gradation areas.

[0098] In this way, according to this embodiment, by using the ratio of large, medium, and small droplets as described above, white pixels exist at input levels other than 100%, reducing the number of droplets ejected simultaneously, suppressing the effects of the ejected air currents, and preventing interference between the ejected air currents. This makes it possible to suppress deviations in landing positions and deflections in the ejected droplets, as well as white / black streaks at the joints of the heads.

[0099] (Fifth embodiment) Next, a fifth embodiment will be described.

[0100] The fifth embodiment differs from the first embodiment in that it has three gradations using large and small droplets. In the following description of the fifth embodiment, the description of the same parts as in the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0101] Here, FIG. 14 is a diagram showing the relationship between the Input Level and the Drop Ratio according to the fifth embodiment, and FIG. 15 is a diagram showing the relationship between the Input Level and the Output Level.

[0102] In the first embodiment, the dot data had four gradations including small droplet dots, large droplet dots with a larger droplet volume than the small droplet dots, and medium droplet dots with a larger droplet volume than the small droplet dots but smaller droplet volume than the large droplet dots, whereas in this embodiment, the dot data has three gradations including only small droplet dots and large droplet dots with a larger droplet volume than the small droplet dots.

[0103] 14, in this embodiment, the discharge control unit 212 suppresses the usage ratio of small droplets and starts using large droplets from the low Input Level of 10%. From the Input Level of 10% where the use of large droplets begins, the usage ratio of small droplets is also reduced. The discharge control unit 212 stops using small droplets at 30%, before the Input Level reaches 100%.

[0104] Also, as shown in FIG. 15, the discharge control unit 212 sets the ratio of the output level to the input level in a substantially linear relationship, and also sets the white pixel to monotonically decrease from the low gradation part to the high gradation part.

[0105] In this way, according to this embodiment, by using the ratio of large and small droplets as described above, white pixels exist at input levels other than 100%, the number of droplets ejected simultaneously is reduced, the effects of the ejected air currents are suppressed, and interference between the ejected air currents can be prevented. This makes it possible to suppress deviations in landing positions and deflections in the ejected droplets, as well as white / black streaks at the joints of the heads.

[0106] In this application, a "liquid ejecting device" is a device that includes a liquid ejection head 122 or a liquid ejection unit, and ejects liquid by driving the liquid ejection head 122. A liquid ejecting device includes not only a device that can eject liquid onto an object to which the liquid can adhere, but also a device that ejects liquid into air or liquid.

[0107] This "liquid ejecting device" can also include means for feeding, transporting, and discharging items onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0108] For example, examples of "devices that eject liquid" include image forming devices that eject ink to form an image on paper, and three-dimensional modeling devices that eject modeling liquid onto a powder layer formed by layering powder in order to create a three-dimensional object (a three-dimensional model).

[0109] In addition, the term "liquid ejection device" is not limited to devices that use ejected liquid to visualize meaningful images such as letters and figures. For example, it also includes devices that form patterns that have no meaning in themselves and devices that create three-dimensional images.

[0110] The above-mentioned "object to which liquid can adhere" means an object to which liquid can adhere at least temporarily, and to which the liquid adheres and sticks, or to which the liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, and other recording media, electronic boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects to which liquid can adhere.

[0111] The material of the above-mentioned "object to which liquid can adhere" may be any material to which liquid can adhere even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, and ceramics.

[0112] The "liquid" is not particularly limited as long as it has a viscosity and surface tension that allows it to be discharged from the liquid discharge head 122, but it is preferable that the viscosity of the liquid is 30 mPa·s or less at room temperature and pressure, or by heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, etc., containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, or calcium, an edible material such as a natural colorant, etc., and these can be used for applications such as inkjet ink, surface treatment liquid, liquid for forming components of electronic elements or light-emitting elements or electronic circuit resist patterns, material liquid for three-dimensional modeling, etc.

[0113] Furthermore, the "liquid ejection device" may be a device in which the liquid ejection head 122 and an object to which liquid can adhere move relatively, but is not limited to this. Specific examples include a serial type device in which the liquid ejection head 122 moves, a line type device in which the liquid ejection head 122 does not move, and the like.

[0114] Other examples of "liquid ejecting devices" include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0115] For example, aspects of the present invention are as follows. <1> A liquid ejection head selectively ejects from a nozzle two or more types of liquid droplets having different ejection droplet volumes to express a density gradation according to an input gradation value, a discharge control unit that controls the nozzles to discharge only the largest droplets of the two or more types of droplets in a high gradation portion of the input gradation value, and controls the number of the nozzles that do not discharge to monotonically decrease from the low gradation portion to the high gradation portion of the input gradation value. A liquid ejection head comprising: <2> the ejection control unit controls the ratio of the ejection droplet volume to the input gradation value so as to be approximately linear; Characterized by <1> The liquid ejection head according to claim 1. <3> the ejection control unit controls the ejection of the smallest droplet of the two or more types of droplets only at 20% or less of the input gradation value; Characterized by <1> or <2> The liquid ejection head according to claim 1 . <4> the ejection control unit controls the ejection of the smallest droplet of the two or more types of droplets only at 5% or less of the input gradation value; Characterized by <1> Or <3> 13. The liquid ejection head according to claim 12, <5> Three or more types of droplets having different droplet volumes are selectively ejected from the nozzles, the discharge control unit controls the second smallest droplet among the three or more types of droplets to be discharged at 30% or less of the input gradation value; Characterized by <1> The liquid ejection head according to claim 1. <6> Three or more types of droplets having different droplet volumes are selectively ejected from the nozzles, the discharge control unit controls a gradation value of an upper limit of discharge of the smallest droplet among the three or more types of droplets and a gradation value discharged by only the second smallest droplet among the three types of droplets so that the gradation value is the same. Characterized by <1> The liquid ejection head according to claim 1 . <7> the discharge control unit controls so that a ratio of the discharge droplet volume of the smallest droplet among the two or more types of droplets to the input gradation value is 40% or less. Characterized by <1> or <2> The liquid ejection head according to claim 1. <8> the discharge control unit controls so that a ratio of the discharge droplet volume of the smallest droplet among the two or more types of droplets to the input gradation value is 20% or less. Characterized by <1> or <2> The liquid ejection head according to claim 1. <9> Three or more types of droplets having different droplet volumes are selectively ejected from the nozzles, the discharge control unit controls so that a ratio of the discharge droplet volume of the second smallest droplet among the three or more types of droplets to the input gradation value is 40% or less. Characterized by <1> or <2> The liquid ejection head according to claim 1. <10> Three or more types of droplets having different droplet volumes are selectively ejected from the nozzles, the discharge control unit controls so that a ratio of the discharge droplet volume of the second smallest droplet among the three or more types of droplets to the input gradation value is 30% or less. Characterized by <1> or <2> The liquid ejection head according to claim 1. <11> <1> Or <10> A liquid ejection head according to any one of the above items, At least 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 comprising: <12> <1> Or <10> A liquid ejection head according to any one of the above items, A control unit that drives the liquid ejection head to eject liquid; A liquid ejection device comprising: <13> A liquid ejection method for a liquid ejection head, which selectively ejects two or more types of liquid droplets having different ejection droplet volumes from a nozzle to express a density gradation according to an input gradation value, comprising: a discharge control step of discharging only the largest droplet of the two or more types of droplets from the nozzle in a high tone portion of the input tone value, and controlling the number of the nozzles that do not discharge from all of the nozzles to monotonically decrease from the low tone portion to the high tone portion of the input tone value, A liquid ejection method comprising: <14> A computer that controls a liquid ejection head that selectively ejects two or more types of liquid droplets with different ejection droplet amounts from a nozzle to express a density gradation according to an input gradation value. and functioning as an ejection control unit that controls the nozzles to eject only the largest droplets of the two or more types of droplets in a high gradation portion of the input gradation value, and controls the number of the nozzles that do not eject droplets among all of the nozzles to monotonically decrease from the low gradation portion to the high gradation portion of the input gradation value. A program characterized by: [Explanation of symbols]

[0116] 100 Liquid ejection device 101 Control section 122 Liquid ejection head 212 Discharge control section [Prior art documents] [Patent documents]

[0117] [Patent Document 1] Patent No. 5709394 [Patent Document 2] JP 2019-119052 A

Claims

1. A liquid ejection head selectively ejects from a nozzle two or more types of liquid droplets having different ejection droplet volumes to express a density gradation according to an input gradation value, a discharge control unit that controls the nozzles to discharge only the largest droplets of the two or more types of droplets in a high gradation portion of the input gradation value, and controls the number of the nozzles that do not discharge to monotonically decrease from the low gradation portion to the high gradation portion of the input gradation value. A liquid ejection head comprising:

2. the ejection control unit controls the ratio of the ejection droplet volume to the input gradation value so as to be approximately linear; 2. The liquid ejection head according to claim 1.

3. the ejection control unit controls the ejection of the smallest droplet of the two or more types of droplets only at 20% or less of the input gradation value; 2. The liquid ejection head according to claim 1.

4. the ejection control unit controls the ejection of the smallest droplet of the two or more types of droplets only at 5% or less of the input gradation value; 2. The liquid ejection head according to claim 1.

5. Three or more types of droplets having different droplet volumes are selectively ejected from the nozzles, the discharge control unit controls the second smallest droplet among the three or more types of droplets to be discharged at 30% or less of the input gradation value; 2. The liquid ejection head according to claim 1.

6. Three or more types of droplets having different droplet volumes are selectively ejected from the nozzles, the discharge control unit controls a gradation value of an upper limit of discharge of the smallest droplet among the three or more types of droplets and a gradation value discharged by only the second smallest droplet among the three types of droplets so that the gradation value is the same.

2. The liquid ejection head according to claim 1.

7. the ejection control unit controls so that a ratio of an ejection droplet volume of the smallest droplet among the two or more types of droplets to the input gradation value is 40% or less; 2. The liquid ejection head according to claim 1.

8. the ejection control unit controls the ratio of the ejection droplet volume of the smallest droplet among the two or more types of droplets to the input gradation value to be 20% or less; 2. The liquid ejection head according to claim 1.

9. Three or more types of droplets having different droplet volumes are selectively ejected from the nozzles, the ejection control unit controls the ratio of the ejection droplet volume of the second smallest droplet among the three or more types of droplets to the input gradation value to be 40% or less; 2. The liquid ejection head according to claim 1.

10. Three or more types of droplets having different droplet volumes are selectively ejected from the nozzles, the ejection control unit controls the ratio of the ejection droplet volume of the second smallest droplet among the three or more types of droplets to the input gradation value to be 30% or less; 2. The liquid ejection head according to claim 1.

11. A liquid ejection head according to any one of claims 1 to 10, At least 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 comprising:

12. A liquid ejection head according to any one of claims 1 to 10, A control unit that drives the liquid ejection head to eject liquid; A liquid ejection device comprising:

13. A liquid ejection method for a liquid ejection head, which selectively ejects from a nozzle two or more types of liquid droplets having different ejection droplet volumes to express a density gradation according to an input gradation value, comprising the steps of: a discharge control step of discharging only the largest droplet of the two or more types of droplets from the nozzle in a high tone portion of the input tone value, and controlling the number of the nozzles that do not discharge from all of the nozzles to monotonically decrease from the low tone portion to the high tone portion of the input tone value, A liquid ejection method comprising:

14. A computer that controls a liquid ejection head that selectively ejects two or more types of liquid droplets having different ejection droplet amounts from a nozzle to express a density gradation according to an input gradation value. and functioning as an ejection control unit that controls the nozzles to eject only the largest droplets of the two or more types of droplets in a high gradation portion of the input gradation value, and controls the number of the nozzles that do not eject droplets among all of the nozzles to monotonically decrease from the low gradation portion to the high gradation portion of the input gradation value. A program characterized by:

Images