Liquid discharge device, image formation device, liquid discharge method, and program

Abstract

To provide a liquid discharge device, an image formation device, a liquid discharge method, and program that can suppress image quality disturbance caused by air current.SOLUTION: The present invention comprises: a liquid discharge head which can discharge two or more kinds of liquid droplets having different sizes; and a control part that discharges only the largest liquid droplet at a high gradation part of an input gradation value, does not cause a ratio of non-discharge nozzle of nozzles of the liquid discharge head to increase toward the high gradation part from a low graduation part of the input graduation value, and includes at least one portion with no change in inclination thereof.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus, an image forming apparatus, a liquid ejection method, and a program. [Background technology]

[0002] A common method of expressing gradation is to use small dot sizes created by small droplets in low gradation areas, reduce the proportion of small dot sizes in intermediate gradation areas while mixing in medium dot sizes created by medium droplets, and reduce the proportion of medium dot sizes in high gradation areas while mixing in large dot sizes created by large droplets.However, as the number of droplets ejected at the same time (ejected droplets) increases, the air currents generated by the ejected droplets themselves interfere with each other, causing the ejected droplets to bend.

[0003] This becomes particularly noticeable the greater the distance between the nozzle and the recording medium, such as paper. If satellites or the like are formed in the ejected droplets, they are carried away by the air current and land, causing unevenness like woodgrain, and the nozzles at the ends of the liquid ejection head are affected by a bias in the air current, making the landing position more likely to be displaced (bent). In particular, when printing using multiple liquid ejection heads lined up, white or black streaks are more likely to occur at the joints between the liquid ejection heads.

[0004] A technique has been devised in which large droplets are used for the same gradation, taking into consideration the balance of the droplet configuration. Patent Document 1 describes that only the largest droplets are ejected in the high gradation area, and that the number of non-ejecting nozzles does not increase (decreases) from the low gradation area to the high gradation area. Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the above-mentioned droplet configuration, simply changing the droplet size results in a space between droplets equal to the input number, resulting in narrower spacing between droplets and making the droplets more susceptible to airflow. Also, two different droplet sizes are used for each input level, which creates the problem of greater susceptibility to the effects of the smaller droplet.

[0006] The present invention has been made in view of the above, and has an object to provide a liquid ejection apparatus, an image forming apparatus, a liquid ejection method, and a program that can suppress image quality disturbance caused by air currents. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the present invention comprises a liquid ejection head capable of ejecting two or more types of droplets of different sizes, and a control unit that ejects only the largest droplets in the high tone part of the input tone value, and that ensures that the proportion of non-ejecting nozzles among the nozzles of the liquid ejection head does not increase from the low tone part to the high tone part of the input tone value and that includes at least one part where the slope does not change. [Effects of the Invention]

[0008] According to the present invention, even if the ejection volume is the same, by increasing the number of larger ejected droplets, it is possible to provide as much space between the ejected droplets as possible, thereby achieving the effect of suppressing image quality disturbance caused by air currents. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram for explaining an example of a conventional method for expressing gradation. [Figure 2] FIG. 2 is a perspective view showing the inside of an image forming apparatus to which the liquid ejection apparatus according to the first embodiment is applied. [Figure 3] FIG. 3 is a diagram illustrating an outline of the configuration of the image forming apparatus according to the first embodiment. [Figure 4A]FIG. 4A is a block diagram illustrating an example of a hardware configuration of the image forming apparatus according to the first embodiment. [Figure 4B] FIG. 4B is a diagram illustrating an example of how liquid droplets land on a medium in the image forming apparatus according to the first embodiment. [Figure 5A] FIG. 5A is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the first embodiment. [Figure 5B] FIG. 5B is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the first embodiment. [Figure 6A] FIG. 6A is a diagram showing the image quality when a white pixel is filled with only small droplets. [Figure 6B] FIG. 6B is a diagram showing the image quality when the white pixel is filled with only medium droplets. [Figure 6C] FIG. 6C is a diagram showing the image quality when the white pixel is filled with only large droplets. [Figure 7] FIG. 7 is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the second embodiment. [Figure 8] FIG. 8 is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the second embodiment. [Figure 9] FIG. 9 is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the third embodiment. [Figure 10] FIG. 10 is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the third embodiment. [Figure 11] FIG. 11 is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the fourth embodiment. [Figure 12] FIG. 12 is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the fourth embodiment. [Figure 13] FIG. 13 is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the fifth embodiment. [Figure 14]FIG. 14 is a diagram for explaining an example of a gradation expression method in the liquid ejection device according to the fifth embodiment. [Figure 15] FIG. 15 is a schematic diagram showing an example of an electrode manufacturing apparatus to which the liquid discharge apparatus according to the second embodiment is applied. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a liquid ejection apparatus, an image forming apparatus, a liquid ejection method, and a program will be described in detail with reference to the accompanying drawings.

[0011] FIG. 1 is a diagram illustrating an example of a conventional gradation representation method. In FIG. 1, the vertical axis represents the Drop Ratio, and the horizontal axis represents the Input Level. Here, the Input Level (an example of an input gradation value) represents the density level, with 0% representing white and 100% representing black in grayscale representation. The Drop Ratio indicates the usage ratio of the droplets (droplets ejected from the liquid ejection head) or dot size at that time, with 0% representing no use and 100% representing the entire surface being filled with those dots. Small represents small droplets or small dot size, Middle represents medium droplets or medium dot size, Large represents large droplets or large dot size, and White Pixel represents a dot where no droplets are ejected.

[0012] For example, when the Input Level is 0%, Small, Middle, and Large are all 0%, which means that no droplets are being applied. Therefore, the White Pixel is 100%. When the Input Level is 16.7%, the usage ratio of Small is 50%, and the usage ratios of Middle and Large are each 0%, so the White Pixel is 50%. When the Input Level is 50%, the usage ratios of Small and Middle are each 50%, and the usage ratio of Large is 0%, so the White Pixel is 0%.

[0013] With this method of gradation expression, small dot size is used up to 100%, then replaced with medium droplets, and when the medium droplets reach 100%, they are replaced with large droplets, making it possible to express smooth gradation.

[0014] However, when the Input Level is 33%, the White Pixel is 0%, and the airflow caused by the ejected droplets (liquid droplets) themselves becomes large. When the distance from the nozzle of the liquid ejection head to the recording medium is short (usually about 1 to 2 mm), the droplets land on the recording medium before being affected by the airflow, so the impact on landing position deviation and jet deflection is minor. However, when the distance is long, the droplets are affected by the airflow, causing landing position deviation and jet deflection. In particular, relatively small droplets, such as small and medium droplets, are more susceptible to the influence of the airflow, making them more likely to be affected by landing position deviation and jet deflection.

[0015] (First embodiment) Fig. 2 is a perspective view showing the inside of an image forming apparatus to which a liquid ejection device according to the first embodiment is applied. Fig. 3 is a diagram showing an outline of the configuration of the image forming apparatus according to the first embodiment. As shown in Figs. 2 and 3, the image forming apparatus 100 according to this embodiment is a wide-width serial inkjet recording apparatus.

[0016] In this embodiment, the liquid ejection device of the present invention will be described by taking an example in which it is applied to a wide serial inkjet, but it can also be applied to any image forming device such as a multifunction device, copier, printer, scanner device, or facsimile device that has at least two of the functions of copying, printing, scanning, and facsimile.

[0017] 2 and 3, the image forming apparatus 100 includes side plates 21A and 21B on the left and right sides of the apparatus main 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-metal guide 32. The main guide rod 31 and the sub-metal guide 32 slidably support the carriage 121.

[0018] The carriage 121 moves relative to the medium 40 by moving in the direction of arrow Y (main scanning direction) via a timing belt that is driven to rotate by a main scanning motor 117 (see FIG. 4). 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).

[0019] 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. 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.

[0020] The carriage 121 is equipped with heads 122a, 122b, and 122c (these three heads 122a, 122b, and 122c are collectively referred to as liquid ejection heads 122) that eject ink droplets (liquid) of various colors, such as yellow (Y), cyan (C), magenta (M), black (K), orange (O), green (G), and clear (Cl), depending on the ink cartridge 10 installed.

[0021] The medium 40 moves along a sub-scanning direction (direction of arrow X) that is substantially perpendicular to the main scanning direction (direction Y) using a transport roller that is rotationally driven by a sub-scanning motor 118 (see FIG. 4), thereby moving relatively to the liquid ejection head 122. However, the main scanning direction (direction Y) and the sub-scanning direction (direction X) do not necessarily have to be substantially perpendicular, as long as they intersect.

[0022] Heads 122a, 122b, and 122c have nozzle rows each consisting of a plurality of nozzles arranged in the sub-scanning direction (X direction). Heads 122a, 122b, and 122c are mounted so that the ink droplets ejected from the nozzles face downward (Z direction). Heads 122a, 122b, and 122c are installed so as to overlap each other in the sub-scanning direction (X direction). Carriage 121 is equipped with sub-tanks to supply ink of each color to heads 122a, 122b, and 122c.

[0023] A liquid ejection head is a functional component that ejects and sprays liquid from nozzles. The ejected liquid may have any viscosity and surface tension that allows it to be ejected from the liquid ejection head 122. While there are no particular limitations on the ejected liquid, it is preferable that the viscosity of the ejected liquid be 30 mPa·s or less at room temperature and pressure, or upon heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, or the like 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, or an edible material such as a natural dye. These liquids can be used for applications such as inkjet inks, surface treatment solutions, liquids for forming components of electronic devices or light-emitting elements, or resist patterns for electronic circuits, and material liquids for 3D modeling.

[0024] Energy sources for discharging liquid from a liquid discharge head include those that use pressure generating means such as piezoelectric actuators (laminated piezoelectric elements and thin film piezoelectric elements).

[0025] Furthermore, the pressure generating means used in the liquid ejection head is not limited. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element) as described above, 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.

[0026] The image forming apparatus 100 includes a cartridge loading section 1 into which ink cartridges 10y, 10c, 10m, and 10k of the respective colors (hereinafter referred to as ink cartridges 10 when no distinction is made) are detachably mounted.

[0027] The ink in the ink cartridges 10 is replenished and supplied to the sub-tanks of the carriage 121 by a supply pump unit via supply tubes 36 of each color. The supply pump units and supply tubes 36 constitute a supply mechanism. The ink cartridges 10 may also include a white ink cartridge.

[0028] 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 (Y 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.

[0029] The maintenance and recovery mechanism 81 includes cap members 82a, 82b, and 82c (referred to as cap members 82 when not distinguishing between them) for capping the nozzle faces of the liquid ejection head 122, and a wiping unit 83 for wiping the nozzle faces. Also, 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.

[0030] A liquid ejection unit is a collection of components related to ejecting liquid, in which functional parts and mechanisms are integrated with the liquid ejection head 122. For example, the liquid ejection unit may include a combination of the liquid ejection head 122 with at least one of the following components: 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.

[0031] Here, "integrated" includes, for example, the liquid ejection head 122 and the functional parts or mechanisms being fixed to each other by fastening, bonding, engaging, etc., or one being held movably relative to the other. The liquid ejection head 122 and the functional parts or mechanisms may also be configured to be detachable from each other.

[0032] For example, some liquid ejection units have the liquid ejection head 122 and a head tank integrated together. Other liquid ejection units have the liquid ejection head 122 and head tank 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.

[0033] Furthermore, there is a liquid ejection unit in which the liquid ejection head 122 and the carriage 121 are integrated.

[0034] In some liquid ejection units, the liquid ejection head 122 is movably held on a main guide rod 31, which is a guide member that constitutes 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, carriage 121, and main scanning movement mechanism are integrated together.

[0035] In addition, 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 121 on which a liquid ejection head 122 is attached, thereby integrating the liquid ejection head 122, the carriage 121, and the maintenance and recovery mechanism 81.

[0036] Also, there is a liquid ejection unit in which a supply tube 36 is connected to a head tank (a sub-tank of the carriage 121) or a liquid ejection head 122 to which 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.

[0037] The main scanning movement mechanism includes the main guide rod 31 alone, which is a guide member. The supply mechanism also includes the supply tube 36 alone and the cartridge loading unit 1 alone.

[0038] Fig. 4A is a block diagram showing an example of the hardware configuration of an image forming apparatus according to the first embodiment. As shown in Fig. 4A, 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. In this embodiment, the control unit 101, the head driver 116, and the liquid ejection head 122 function as an example of the liquid ejection apparatus.

[0039] 4A, 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 123, 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.

[0040] 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 123, fan control unit 111, heater control unit 112 and I / O 113 are connected to each other so that they can communicate with each other, for example, via a bus or the like.

[0041] 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.

[0042] The ROM 103 stores programs executed by the CPU 102 and other fixed data. The RAM 104 temporarily stores image data and the like. 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.

[0043] 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, image reading device, or imaging device via a cable, 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.

[0044] 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 selectively drives a pressure generating means that generates pressure for the liquid ejection head 122 to eject liquid (ink) from the nozzles.

[0045] Main scanning motor drive unit 109 is a circuit for driving main scanning motor 117. Sub scanning motor drive unit 123 is a circuit for driving sub scanning motor 118. Fan control unit 111 is a circuit for controlling the output of fan 119 so that air is blown at a predetermined temperature and volume.

[0046] Heater control unit 112 is a circuit for controlling heater 120 to maintain 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 (for example, optical sensor 37).

[0047] The operation panel 114 is a device for inputting and displaying various information such as user-specified resolution, etc. The operation panel 114 is connected to the CPU 102 and the like via the bus of the control unit 101, for example, so as to be able to communicate with each other.

[0048] 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.

[0049] 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 (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 ejection amount is controlled by, for example, controlling the amplitude of the drive waveform input to the pressure generating means of the liquid ejection head 122, but the ejection amount may also be controlled using other means.

[0050] The main scanning motor 117 is a device that drives and rotates a timing belt to move a carriage 121 equipped with a liquid ejection head 122 in the main scanning direction (the direction of arrow Y). The main scanning motor 117 is connected to a main scanning motor drive unit 109 of the control unit 101.

[0051] The sub-scanning motor 118 is a device that, when driven, operates a transport roller that transports, in the sub-scanning direction (X direction), the medium 40, which is the target 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 123 of the control unit 101.

[0052] 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-metal guide plate 32, the carriage 121, the transport rollers, and the like, and constitutes a main scanning movement mechanism.

[0053] The movement mechanism 140 moves the liquid ejection head 122 and the medium 40 relative to each other in the main scanning direction (Y direction) using the main guide rod 31, the sub-metal guide 32, the carriage 121, etc. The movement mechanism 140 also moves the liquid ejection head 122 and the medium 40 relative to each other in the sub-scanning direction (X direction) using a transport roller that transports the medium 40, etc. In this embodiment, the relative movement in the sub-scanning direction (X direction) by the movement mechanism 140 is intermittent movement. Intermittent movement refers to movement that alternates between movement and stopping.

[0054] Fan 119 is a device that, when driven, promotes air convection inside image forming apparatus 100 and prevents excessive temperature rise due to stagnation of heated air at the top of image forming apparatus 100. Fan 119 is connected to fan control unit 111 of control unit 101.

[0055] Here, an example of a characteristic operation of the image forming apparatus 100 (an example of a liquid ejection apparatus) according to this embodiment will be described.

[0056] First, the liquid ejection head 122 is an example of a liquid ejection head capable of ejecting two or more types of droplets (e.g., ink droplets) of different sizes. The control unit 101 controls the head driver 116 to eject only the largest droplets (e.g., large droplets) in the high gradation portion of the input gradation value (e.g., Input Level) of the liquid ejection head 122. The control unit 101 is also an example of a control unit that does not increase the proportion of non-ejecting nozzles (non-ejecting nozzle rate) among the nozzles of the liquid ejection head 122 from the low gradation portion to the high gradation portion of the input gradation value, and includes at least one portion where the slope does not change. This allows for the same ejection volume to be ejected with an increased number of larger ejected droplets, thereby ensuring the maximum spacing between ejected droplets, thereby suppressing image quality disturbances due to airflow. In this embodiment, the control unit is implemented by the control unit 101 external to the liquid ejection head 122, but may also be implemented within the liquid ejection head 122.

[0057] Furthermore, the control unit 101 does not need to decrease the droplet deposition amount per unit area or the ejection droplet volume ratio, which is the image density, as the input tone value increases.

[0058] Furthermore, the control unit 101 may also cause the liquid ejection head 122 to eject the smallest droplets (for example, small droplets) only at 20% or less of the input gradation value.

[0059] Furthermore, the control unit 101 may cause the liquid ejection head 122 to eject only the smallest droplets when the input gradation value is 5% or less.

[0060] Furthermore, the liquid ejection head 122 may be capable of ejecting three or more different sizes of droplets (for example, small droplets, medium droplets, and large droplets).The control unit 101 may then eject the second smallest droplet (for example, medium droplets) at 20% or less of the input gradation value.

[0061] Furthermore, the control unit 101 may also make at least one portion of the liquid ejection head 122 where the slope of the non-ejecting nozzle rate does not change exist where the input gradation value is 20% or less.

[0062] Furthermore, the control unit 101 may cause two of the portions of the liquid ejection head 122 where the slope of the non-ejecting nozzle rate does not change to exist at an input gradation value of 40% or less, and one of those to exist at an input gradation value of 20% or less.

[0063] FIG. 4B is a diagram showing an example of droplets landing on a liquid medium in an image forming apparatus according to the first embodiment. Diagrams A and C of FIG. 4B are the same diagram, showing an example of droplets landing on a medium consisting of a small droplet (S droplet) 1 and four white pixels 3. Conventionally, when increasing the input level 4, the small droplets were simply replaced with medium droplets (M droplets) 2 to increase density, and small droplets were also added to improve graininess. Therefore, increasing the input level 4 reduces the void ratio. In other words, the number of white pixels 3 decreases.

[0064] Therefore, in this embodiment, the control unit 101 replaces small droplets 1 with medium droplets 2, which have a volume greater than the total volume of small droplets 1, without adding small droplets 1, and the void ratio remains unchanged. In other words, the number of white pixels 3 remains unchanged. Since medium droplets 2 are not affected by the curvature of the droplet airflow, they are closer to the landing position in Figure D than in Figure B. The droplet spacing also becomes wider.

[0065] (First Example) 5A and 5B are diagrams illustrating an example of a gradation expression method in the liquid ejection device according to the first embodiment. In FIG. 5A, the vertical axis represents the drop ratio, and the horizontal axis represents the input level. In FIG. 5B, the vertical axis represents the output level, and the horizontal axis represents the input level. Here, the output level represents the density of the output image. In this embodiment, an example is shown in which small droplets are X1 pL, medium droplets are Y1 pL, and large droplets are Z1 pL. Here, X1 is less than Y1, and Y1 is less than Z1.

[0066] The control unit 101 suppresses the use rate of small droplets and starts using medium droplets from a low input level of 5%. The control unit 101 also reduces the use rate of small droplets from the input level of 5% where medium droplets began to be used. That is, the control unit 101 causes the liquid ejection head 122 to eject small droplets only at or below 20% of the input gradation value. The use rate of medium droplets is increased to 15%, but the number of nozzles used for medium droplets can be reduced relative to the number of nozzles used for small droplets to ensure the same print density. Moreover, despite the increased print density, the proportion of non-ejecting nozzles that do not eject droplets (non-ejecting nozzle rate) can be maintained at a high level of 80%, reducing the impact position deviation and jet deflection of ejected droplets compared to when the droplet configuration has a non-ejecting nozzle rate below 80%.

[0067] Similarly, the control unit 101 also suppresses the use rate of medium droplets, lowering it from 15% of the input level, where the use of large droplets begins. The use of medium droplets is stopped at 30%, well before the input level reaches 100%. As shown in FIG. 5B, when determining this use rate, it is desirable for the output level to have a roughly linear relationship with the input level. However, to ensure a more constant non-ejecting nozzle rate, the control unit 101 allows for some deviation, but ensures that the non-ejecting nozzle rate increases. In other words, the control unit 101 causes the liquid ejection head 122 to eject only large droplets in the high gradation range of the input level. Furthermore, the control unit 101 does not increase the non-ejecting nozzle rate from the low gradation range to the high gradation range of the input level, and includes at least one portion where the slope does not change.

[0068] The Output Level in this case may be the amount of liquid deposited per unit area or the image density. By maintaining a linear and increasing relationship between the Input Level and the Output Level, the control unit 101 can minimize the effects of gradation jumps in the gamma curve and color matching used to determine the final color tone. In other words, the control unit 101 does not reduce the amount of liquid deposited per unit area or the ejected droplet volume ratio, which is the image density, as the Input Level increases.

[0069] By using such a ratio of large, medium, and small droplets, white pixels exist at input levels other than 100%, and by creating a constant ratio of white pixels at low print densities, the number of droplets ejected simultaneously can be efficiently reduced and the effects of ejection airflow can be suppressed. This makes it possible to suppress misalignment of landing positions, deflection of ejection, and white or black streaks at the joints of the heads.

[0070] FIG. 6A is a diagram showing the image quality when a white pixel is filled with only small droplets. FIG. 6B is a diagram showing the image quality when a white pixel is filled with only medium droplets. FIG. 6C is a diagram showing the image quality when a white pixel is filled with only large droplets. Here, an example of how black streaks appear depending on the size of the droplets will be described. FIGS. 6A to 6C show how black and white streaks appear at the joints of the liquid ejection heads 122, droplet flow (wood grain), and granularity.

[0071] As shown in Figure 6A, to ensure image quality using only small droplets, it is desirable to use a white pixel of 0 to less than 10%, although this depends on the printing conditions. Also, as shown in Figure 6B, to ensure image quality using only medium droplets, it is desirable to use a white pixel of less than 20%. Furthermore, as shown in Figure 6C, to ensure image quality using only large droplets, it is better to avoid using large droplets with low white pixels in order to ensure balanced image quality, from the perspective of graininess.

[0072] Therefore, in this embodiment, the control unit 101 changes the way white pixels are filled from low gradation areas to high gradation areas by using larger droplets, which allows printing to be performed with good streaks at the joints of the liquid ejection head 122, droplet flow, and graininess.

[0073] (Second Example) 7 and 8 are diagrams for explaining an example of a gradation expression method in the liquid ejection device according to the second embodiment. In Fig. 7, the vertical axis represents the drop ratio, and the horizontal axis represents the input level. In Fig. 8, the vertical axis represents the output level, and the horizontal axis represents the input level.

[0074] First, the area where the slope of the ratio of the first white pixel does not change is set within the range where small and medium droplets switch, as in the first embodiment. This is because medium droplets are added before small droplets become noticeable, and small droplets are used only up to the range where they do not bend and cause black or white stripes. Furthermore, the control unit 101 controls the liquid ejection head 122 to eject only small droplets when the input level is 5% or less. Another difference from the first embodiment is that a region where the slope of the ratio of the second white pixel does not change is also set, even in the relationship between medium and large droplets. In the area where the slope of the ratio of the second white pixel does not change, large droplets are added starting from the point where the ratio of medium droplets is the highest. Medium droplets are set to a ratio where white or black stripes are least noticeable, and the best image can be obtained by changing the print density using large droplets where white or black stripes are least noticeable.

[0075] The first embodiment is an example in which white pixels are increased as much as possible in gradations of 20% or less. This is because when a gradation of 20% or more is created using only small droplets, white or black streaks occur at 20% or more. This can be achieved by not creating a gradation of 20% or more using small droplets. In other words, the control unit 101 ensures that, among the portions of the liquid ejection head 122 where the slope of the non-ejecting nozzle rate does not change, at least one portion exists where the input level is 20% or less. In this case, the control unit 101 ensures that, among the portions of the liquid ejection head 122 where the slope of the non-ejecting nozzle rate does not change, two portions exist where the input level is 40% or less, and one of those portions exists where the input level is 20% or less.

[0076] This embodiment also shows an example in which the white pixel is not reduced as much as possible in the gradation of the mid-range (for example, 15 to 40%). Even when the gradation is composed of only medium droplets, white or black stripes increase when the ratio exceeds 20%, just like with small droplets. Therefore, the droplet configuration is allocated so that the usage ratio of medium droplets does not exceed 20% even in the mid-range. Here, the droplet configuration refers to the respective usage ratios of small droplets, medium droplets, and large droplets.

[0077] Here, although the Output Level deviates slightly from a linear relationship with the Input Level, it always rises in the same manner as the Input Level rises, so no gradation reversal occurred. In reality, the impact on the image, such as white or black streaks caused by misaligned landing positions or deflected jetting, varies depending on the liquid (e.g., ink) used, the recording medium, the distance from the nozzle to the recording medium, the printing speed, and other factors. Reducing the proportion of small and medium droplets used can help to reduce the impact of misaligned landing positions and deflected jetting, but this tends to worsen the graininess of the image, so fine adjustments may be necessary to achieve a balance depending on the printing conditions.

[0078] (Third Example) 9 and 10 are diagrams illustrating an example of a gradation expression method in a liquid ejection device according to a third embodiment. In FIG. 9, the vertical axis represents the drop ratio, and the horizontal axis represents the input level. In FIG. 10, the vertical axis represents the output level, and the horizontal axis represents the input level. This embodiment shows an example in which the droplet volume of medium droplets or larger is increased to further increase the white pixel. The droplet volumes are X1 pL for small droplets, Y2 pL for medium droplets, and Z2 pL for large droplets. Here, Y2 is greater than Y2, and Z2 is greater than Z1.

[0079] In this embodiment, as shown in FIG. 9, the control unit 101 suppresses the use ratio of small droplets more than in the first embodiment, and limits the use ratio of small droplets to a maximum of 10% when the input level is 3%. Medium droplets begin to be used from 3%, and the maximum use of small droplets is reached up to this point. For medium droplets, a droplet configuration of 10% is used when the input level is 6%, and the droplet configuration is increased to 15% up to the input level of 10%. The droplet configuration is further decreased up to the input level of 17%, and then dropped to 0%. After that, the droplet configuration is made up of only large droplets. In other words, the control unit 101 ejects medium droplets at an input level of 20% or less.

[0080] By using the droplet configuration described above, it was possible to ensure a non-ejecting nozzle rate (non-ejection level) of over 80%, compared to Example 1. In other words, by increasing the White Pixel on the low print density side, where the effects of misalignment and curvature of the droplets are most likely to appear in the image quality, an image with fewer white or black streaks can be obtained.

[0081] 10, the output level is approximately linear relative to the input level, making it possible to achieve a smooth gradation pattern. In the second embodiment, small and medium droplets were used up to a high input level, which resulted in a slight deviation in the output level relative to the input level being approximately linear, but in the third embodiment, the input level is limited to 17% in the region where small and medium droplets are used, which makes the gradation pattern smoother.

[0082] (Fourth Example) 11 and 12 are diagrams for explaining an example of a gradation expression method in a liquid ejection device according to Example 4. In Fig. 11, the vertical axis represents Drop Ratio, and the horizontal axis represents Input Level. In Fig. 12, the vertical axis represents Output Level, and the horizontal axis represents Input Level.

[0083] In this embodiment, in order to further increase the white pixel, the droplet volume of small droplets is increased and the range of medium droplets used is reduced compared to the third embodiment. As in the third embodiment, the droplet volumes are X2 pL for small droplets, Y2 pL for medium droplets, and Z2 pL for large droplets. Here, X2 is greater than X1 and less than Y1.

[0084] As shown in Figure 12, small droplets were used up to a maximum of 10% at an input level of 3%, just like in the third embodiment. Because the amount of small droplets was slightly greater, the gradation was slightly smoother than in the third embodiment. Medium droplets were used from an input level of 3% onwards, and at an input level of 6%, the maximum drop ratio was set to 10%, similar to the small droplets. Large droplets were used from an input level of 6% onwards because the amount of medium droplets was kept low. Since medium droplets ceased to exist at an input level of 12%, the proportion of large droplets was increased at input levels of 12% and above. This droplet configuration allowed the non-ejecting nozzle rate to be kept at 90% in the range where small and medium droplets were used, resulting in images with fewer white or black stripes. Furthermore, as shown in Figure 11, the output level versus input level is more linear than in the third embodiment, achieving a smoother gradation pattern.

[0085] (Fifth Example) 13 and 14 are diagrams illustrating an example of a gradation expression method in a liquid ejection device according to a fifth embodiment. In FIG. 13, the vertical axis represents the drop ratio, and the horizontal axis represents the input level. In FIG. 14, the vertical axis represents the output level, and the horizontal axis represents the input level. This embodiment shows an example in which the droplet volumes of medium and large droplets are increased to further increase the white pixel. The droplet volumes are X2 pL for small droplets, Y2 pL for medium droplets, and Z3 pL for large droplets. Here, Z3 is greater than Z2.

[0086] As shown in Figure 13, small droplets are used at a maximum usage ratio of 50% when the input level is 15%, improving granularity. The amount of small droplets used is reduced when the input level is 15% or higher, reducing the visibility of white or black stripes. Medium droplets are used from an input level of 15%, which maximizes the small droplet usage ratio, up to a drop ratio of 50% when the input level is 36%, improving granularity in medium-density printing. Large droplets are used from an input level of 36%, which maximizes the medium droplet usage ratio, with a usage ratio of 50% when the input level is 50%, and a usage ratio of 100% when the input level is 100%. As shown in Figure 14, the output level varies approximately linearly with the input level, achieving a smooth gradation pattern.

[0087] In this way, according to the liquid ejection device of the first embodiment, even if the ejection volume is the same, by increasing the number of larger ejected droplets, it is possible to set as much spacing between the ejected droplets as possible, thereby suppressing image quality disturbance caused by air currents.

[0088] (Second embodiment) In this embodiment, the liquid ejection device is applied to an apparatus for manufacturing electrodes and electrochemical elements. The apparatus for manufacturing electrodes will be described below.

[0089] 15 is a schematic diagram showing an example of an electrode manufacturing apparatus to which the liquid ejection apparatus according to the second embodiment is applied. The electrode manufacturing apparatus is an apparatus for manufacturing an electrode including a layer having an electrode material by ejecting a liquid composition using a head module including a liquid ejection head.

[0090] <Means for forming layer containing electrode material, and process for forming layer containing electrode material> The discharge means provided in the electrode manufacturing apparatus shown in FIG. 15 is a head module according to the embodiment of the present invention. A liquid composition is applied to a target object by being discharged from a discharge head included in the head module, thereby forming a liquid composition layer. The target object (hereinafter sometimes referred to as a discharge target 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 depending on the purpose. For example, examples of the target object include an electrode substrate (current collector), an active material layer, and a layer containing a solid electrode material. The target object may also be an electrode mixture layer containing an active material on an electrode substrate (current collector). The discharge means and discharge step may also be a means and step for directly discharging a liquid composition to form a layer containing an electrode material, as long as it is possible to form a layer containing an electrode material on the discharge target object. The discharge means and discharge step may also be a means and step for indirectly discharging a liquid composition to form a layer containing an electrode material.

[0091] <Other components and processes> Other components included in the manufacturing apparatus for an electrode mixture layer are not particularly limited as long as they do not impair the effects of this embodiment, and can be selected appropriately depending on the purpose. Furthermore, other steps included in the manufacturing method for an electrode mixture layer are also not particularly limited as long as they do not impair the effects of this embodiment, and can be selected appropriately depending on the purpose. For example, components and steps included in the manufacturing apparatus and manufacturing method for an electrode mixture layer include a heating means and a heating step.

[0092] <Heating means, heating process> The heating means included in the manufacturing device for the electrode mixture layer is a means for heating the liquid composition ejected by the ejection means. Also, the heating step included in the manufacturing method for the electrode mixture layer is a step of heating the liquid composition ejected in the ejection step. By heating the liquid composition, the liquid composition layer can be dried.

[0093] <Configuration for forming a layer containing an electrode material by directly ejecting a liquid composition> Here, as an example of an electrode manufacturing apparatus, an electrode manufacturing apparatus that forms an electrode mixture layer containing an active material on an electrode substrate (current collector) will be described. As shown in Fig. 15, the electrode manufacturing apparatus includes a discharge process unit 110 that includes a step of applying a liquid composition to a printing substrate 704 having an object to be discharged to form a liquid composition layer, and a heating process unit 130 that includes a heating step of heating the liquid composition layer to obtain an electrode mixture layer.

[0094] The electrode manufacturing apparatus includes a conveying unit 705 that conveys the printing substrate 704. The conveying unit 705 conveys the printing substrate 704 at a preset speed through the discharging process unit 110 and the heating process unit 130 in that order. There are no particular limitations on the method for manufacturing the printing substrate 704 having a discharge target such as an active material layer, and any known method can be selected as appropriate. The discharging process unit 110 includes a liquid discharge head 281a (an example of a liquid discharge head) that performs the 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 281a.

[0095] In the discharge process unit 110, liquid composition 707 is discharged from liquid discharge head 281a and applied to printing substrate 704, thereby forming a thin film of the liquid composition layer. Note that storage container 281b may be configured as an integral part of the electrode mixture layer manufacturing apparatus, or may be configured as a removable part from the electrode mixture layer manufacturing apparatus. Furthermore, storage container 281b may be a container used for adding the liquid to a storage container integrated with the electrode mixture layer manufacturing apparatus, or a storage container removable from the electrode mixture layer manufacturing apparatus.

[0096] The storage container 281b and the supply tube 281c can be selected arbitrarily as long as they can stably store and supply the liquid composition 707.

[0097] In the heating process section 130, a solvent removal step is carried out in which the solvent remaining in the liquid composition layer is heated and removed. Specifically, the solvent remaining in the liquid composition layer is heated and dried by the heating device 703 in the heating process section 130, thereby removing the solvent from the liquid composition layer. This results in the formation of an electrode mixture layer. The solvent removal step in the heating process section 130 may also be carried out under reduced pressure.

[0098] The heating device 703 is not particularly limited and can be appropriately selected depending on the purpose. For example, the heating device 703 can be a substrate heater, an IR heater, a hot air heater, or the like. The heating device 703 may also be a combination of at least two of the substrate heater, the IR heater, and the hot air heater. The heating temperature and heating time can be appropriately selected depending on the boiling point of the solvent contained in the liquid composition 707 or the thickness of the formed film.

[0099] By using the electrode manufacturing apparatus according to this embodiment, it is possible to eject a liquid composition at a targeted location on an object to be ejected. The electrode mixture layer can be suitably used, for example, as part of the configuration of an electrochemical element. There are no particular restrictions on the components other than the electrode mixture layer in the electrochemical element, and known components can be appropriately selected. For example, components other than the electrode mixture layer include a positive electrode, a negative electrode, a separator, etc.

[0100] In this way, the liquid ejection device according to the second embodiment can achieve the same effects as those of the first embodiment.

[0101] The program executed by image forming apparatus 100 of this embodiment is provided by being pre-installed in ROM 103 or the like. The program executed by image forming apparatus 100 of this embodiment may be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disk).

[0102] Furthermore, the program executed by image forming apparatus 100 of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the program executed by image forming apparatus 100 of the present embodiment may be provided or distributed via a network such as the Internet.

[0103] The program executed by the image forming apparatus 100 of this embodiment has a modular structure including each of the above-mentioned parts (an example of a control unit), and in actual hardware, an example of a processor such as CPU 102 reads and executes the program from the above-mentioned ROM 103, thereby loading each of the above-mentioned parts onto the main memory device and generating an example of a control unit on the main memory device.

[0104] In the above embodiment, the image forming apparatus of the present invention is described as being applied to a multifunction peripheral having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function, but the present invention can be applied to any image forming apparatus such as a copier, printer, scanner device, or facsimile device.

[0105] For example, aspects of the present invention are as follows. <1> a liquid ejection head capable of ejecting two or more types of droplets having different sizes; A liquid ejection device equipped with a control unit that ejects only the largest droplets in the high tone part of the input tone value, and that ensures that the proportion of non-ejecting nozzles among the nozzles of the liquid ejection head does not increase from the low tone part to the high tone part of the input tone value and that includes at least one part where the slope does not change. <2> the control unit does not decrease the droplet deposition amount per unit area or the ejection droplet volume ratio, which is the image density, as the input gradation value increases; <1> The liquid ejection device according to claim 1. <3> the control unit controls the liquid ejection head to eject the smallest droplets only when the droplets are equal to or smaller than 20% of the input gradation value; <1> or <2> The liquid ejection device according to claim 1. <4> the control unit causes the liquid ejection head to eject only the smallest droplets when the input gradation value is 5% or less. <1> from <3> 10. The liquid ejection device according to claim 9, wherein <5> the liquid ejection head is capable of ejecting three or more types of droplets of different sizes; the control unit ejects the second smallest droplet at 20% or less of the input gradation value. <3> The liquid ejection device described above. <6> the control unit causes at least one portion of the liquid ejection head where the slope of the ratio does not change to exist where the input gradation value is 20% or less. <1> or <2> The liquid ejection device according to claim 1. <7> the control unit causes two of the portions of the liquid ejection head where the slope of the ratio does not change to have the input gradation value of 40% or less, and causes one of the portions to have the input gradation value of 20% or less. <1> or <2> The liquid ejection device according to claim 1. <8> <1> from <7> 10. An image forming apparatus including the liquid ejection device according to any one of claims 1 to 9. <9> A liquid ejection method carried out by a liquid ejection device having a liquid ejection head capable of ejecting two or more types of droplets with different sizes, a step of discharging only the largest droplets in the high tone portion of the input tone value; a step in which the ratio of non-ejecting nozzles that do not eject among the nozzles of the liquid ejection head does not increase from a low gradation portion to a high gradation portion of the input gradation value and includes at least one portion in which there is no change in slope; A liquid ejection method comprising: <10> A computer that controls a liquid ejection device having a liquid ejection head that can eject two or more types of droplets with different sizes, a control unit that ejects only the largest droplets in a high gradation portion of the input gradation value, and that causes the ratio of non-ejecting nozzles among the nozzles of the liquid ejection head to not increase from a low gradation portion to a high gradation portion of the input gradation value, and that includes at least one portion where there is no change in slope; A program to make it function as such. [Explanation of symbols]

[0106] 100 Image forming device 101 Control section 102 CPU 103 ROM 104 RAM 105 NVRAM 108 Printing control unit 116 Head Driver 122,281a ​​Liquid ejection head [Prior art documents] [Patent documents]

[0107] [Patent Document 1] Japanese Patent Application Publication No. 2019-134416

Claims

1. a liquid ejection head capable of ejecting two or more types of droplets having different sizes; a control unit that ejects only the largest droplets in a high gradation portion of the input gradation value, and that causes the ratio of non-ejecting nozzles among the nozzles of the liquid ejection head to not increase from a low gradation portion to a high gradation portion of the input gradation value, and that includes at least one portion where there is no change in slope; A liquid ejection device comprising:

2. The liquid ejection device according to claim 1 , wherein the control unit does not decrease the ejection droplet volume ratio, which is the amount of droplets deposited per unit area or the image density, as the input gradation value increases.

3. 3. The liquid ejection device according to claim 1, wherein the control unit controls the liquid ejection head to eject the smallest droplets only when the smallest droplets are equal to or smaller than 20% of the input gradation value.

4. The liquid ejection device according to claim 1 , wherein the control unit causes the liquid ejection head to eject only the smallest droplets when the input gradation value is 5% or less.

5. the liquid ejection head is capable of ejecting three or more types of droplets having different sizes; The liquid ejection device according to claim 3 , wherein the control unit ejects the second smallest droplet at 20% or less of the input gradation value.

6. 3. The liquid ejection device according to claim 1, wherein the control unit causes at least one portion of the liquid ejection head where the slope of the ratio does not change to exist where the input gradation value is 20% or less.

7. The liquid ejection device according to claim 1 or 2, wherein the control unit causes two of the portions of the liquid ejection head where the slope of the ratio does not change to have the input gradation value of 40% or less, and causes one of those portions to have the input gradation value of 20% or less.

8. An image forming apparatus comprising the liquid ejection device according to claim 1 .

9. A liquid ejection method carried out by a liquid ejection device having a liquid ejection head capable of ejecting two or more types of droplets with different sizes, comprising: a step of discharging only the largest droplets in the high tone portion of the input tone value; a step in which the ratio of non-ejecting nozzles that do not eject among the nozzles of the liquid ejection head does not increase from a low gradation portion to a high gradation portion of the input gradation value and includes at least one portion in which there is no change in slope; A liquid ejection method comprising:

10. A computer that controls a liquid ejection device having a liquid ejection head that can eject two or more types of droplets with different sizes, a control unit that ejects only the largest droplets in a high gradation portion of the input gradation value, and that causes the ratio of non-ejecting nozzles among the nozzles of the liquid ejection head to not increase from a low gradation portion to a high gradation portion of the input gradation value, and that includes at least one portion where there is no change in slope; A program to make it function as such.

Images