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

Abstract

To uniformize image quality of a nozzle overlap region on head ends of adjacent liquid discharge heads.SOLUTION: A liquid discharge head, which has a plurality of heads for arraying a nozzle array composed of a plurality of nozzles and selectively discharging a droplet from the nozzles, and has the adjacent heads provided so as to have a nozzle overlap region on the end in the array direction of the nozzle array, includes a discharge control part such that as for a mask pattern of the nozzle overlap region, data in a direction parallel to the array direction of the nozzle array is composed of both pixel data by one head of the plurality of heads and pixel data by the other head of the plurality of heads, and data in a direction crossing the array direction of the nozzle array is composed of any one of the pixel data by the one head and the pixel data by the other head.SELECTED DRAWING: Figure 9

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] Conventionally, techniques relating to image processing of nozzle overlap regions at the ends of adjacent liquid ejection heads have been devised and are already known.

[0003] Patent Document 1 discloses a technique for suppressing degradation of image quality in the nozzle overlap region of a liquid ejection head by masking the nozzle overlap region and creating an image by mixing print dots from two liquid ejection heads. Summary of the Invention [Problem to be solved by the invention]

[0004] However, when printing dots are distributed to the nozzle overlap areas of two liquid ejection heads as in the conventional technology, the drive frequency per nozzle is lower than that of the normal nozzle area other than the nozzle overlap area. In general, the amount of droplets ejected from a liquid ejection head often varies depending on the drive frequency, so the dot size of the printing dots changes in the masked nozzle overlap area. This causes a problem in that the areas where the dot size of the printing dots changes in the nozzle overlap area are visually recognized as uneven density or streaks.

[0005] In addition, in the masked nozzle overlap area, it is ideal for the print dots ejected from the two liquid ejection heads to land in ideal positions. However, if the landing positions of the print dots from one liquid ejection head are relatively shifted due to misalignment between the two liquid ejection heads or differences in droplet speed, it becomes impossible to achieve the same density as in the normal nozzle area. In this way, there is also the problem that the areas where the same density as in the normal nozzle area cannot be achieved are visually recognized as uneven density or streaks.

[0006] The present invention has been made in view of the above, and has an object to make the image quality uniform in the nozzle overlap region at the head ends of adjacent liquid ejection heads. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the present invention provides a liquid ejection head having a plurality of heads which arrange a nozzle row consisting of a plurality of nozzles and selectively eject liquid droplets from the nozzles, and in which adjacent heads are installed with a nozzle overlap area at the end of the nozzle row in the row direction, the liquid ejection head is characterized in that it is equipped with an ejection control unit which configures, for a mask pattern of the nozzle overlap area, data in a direction parallel to the row direction of the nozzle row from both pixel data from one head of the plurality of heads and pixel data from another head of the plurality of heads, and configures data in a direction intersecting the row direction of the nozzle row from either pixel data from the one head or pixel data from the other head. Effect of the Invention

[0008] According to the present invention, it is possible to uniformize the image quality in the nozzle overlap region at the head ends of adjacent liquid ejection heads. [Brief description of the drawings]

[0009] [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 an example of a conventional mask pattern when the end nozzles of two heads aligned in the X direction are arranged so as to overlap each other. [Figure 6] FIG. 6 is a diagram showing the conventional characteristics of the drive frequency for the ejection droplet volume. [Figure 7] FIG. 7 is a diagram showing the characteristics of the driving frequency and a conventional mask pattern. [Figure 8] FIG. 8 is a diagram showing the Y-shift and a conventional mask pattern. [Figure 9] FIG. 9 is a diagram showing an example of a mask pattern according to the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a mask pattern according to the second embodiment. [Figure 11] FIG. 11 is a graph showing an example of the nozzle usage rate in the nozzle overlap region. [Figure 12] FIG. 12 is a diagram showing an example of a mask pattern according to the third embodiment. [Figure 13] FIG. 13 is a diagram showing another example of a mask pattern. [Figure 14] FIG. 14 is a diagram showing an example of a mask pattern according to the fourth embodiment. [Figure 15] FIG. 15 is a diagram illustrating an example of the state of ejected droplets in an end region of a liquid ejection head. [Figure 16] FIG. 16 is a diagram showing another example of a mask pattern. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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.

[0011] 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.

[0012] (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.

[0013] 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.

[0014] 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.

[0015] The carriage 121 moves 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. 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).

[0016] 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 based on reflection density, a camera that captures the image formed on the medium 40, or the like can be used.

[0017] 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 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.

[0018] 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. 3), 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 to each other, as long as they intersect.

[0019] Heads 122a, 122b, and 122c have nozzle rows each consisting of a plurality of nozzles (not shown) arranged in the sub-scanning direction (X direction). Heads 122a, 122b, and 122c are mounted so that the ink droplet ejection direction from the nozzle faces downward (Z direction: see FIG. 15). 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.

[0020] 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.

[0021] The energy generation source for ejecting liquid from the "liquid ejection head" includes those that use pressure generating means such as a piezoelectric actuator (a laminated type piezoelectric element and a thin film type piezoelectric element).

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Furthermore, there is a liquid ejection unit in which the liquid ejection head 122 and the carriage 121 are integrated.

[0031] In addition, there is a liquid ejection unit in which 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 addition, there is a liquid ejection unit in which the liquid ejection head 122, the carriage 121, and the main scanning movement mechanism are integrated together.

[0032] Also, as a liquid ejection unit, there is one 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, so that the liquid ejection head 122, the carriage 121, and the maintenance and recovery mechanism 81 are integrated.

[0033] Also, as a liquid ejection unit, there is one 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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).

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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 Y). The main scanning motor 117 is connected to a main scanning motor driving unit 109 of the control unit 101.

[0048] 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 110 of the control unit 101.

[0049] 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.

[0050] The movement mechanism 140 moves the liquid ejection head 122 and the medium 40 relatively along the main scanning direction (Y 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 (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 moving and stopping.

[0051] 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.

[0052] 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.

[0053] 4, the control unit 101 has a color plane division data generating unit 211 and an ejection control unit 212. The ejection control unit 212 generally controls the ejection of ink.

[0054] 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.

[0055] The ejection control unit 212 generates print dot data by applying a dot data generation mask to the color plate division data of each color generated by the color plate division data generation unit 211. Here, the dot data generation mask is, for example, a mask pattern for forming an image by mixing print dots by two liquid ejection heads in the nozzle overlap region at the ends of the adjacent heads 122a, 122b, and 122c.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] Here, the problems with the conventional technology will be described.

[0060] Fig. 5 is a diagram showing an example of a conventional mask pattern when the end nozzles of two heads 201a, 201b arranged in the X direction are arranged in an overlapping manner, Fig. 6 is a diagram showing the conventional characteristics of the drive frequency for the amount of ejected droplets, Fig. 7 is a diagram showing the characteristics of the drive frequency and the conventional mask pattern, and Fig. 8 is a diagram showing the Y shift and the conventional mask pattern. Note that in Fig. 5, the number of nozzles in the nozzle overlap area 202, which is arranged in an overlapping manner, is 12 for both head 201a and head 201b, but it may be more or less than this.

[0061] 5 shows the state of printed dots when droplets ejected from head 201a and head 201b land at ideal positions on recording medium 203. Landed dot A includes normal portion A1, normal portion A2, and mask portion A3 corresponding to nozzle overlap region 202.

[0062] As shown in FIG. 5, the normal portion A1 of the landing dot A is formed by droplets ejected from the head 201a, and the normal portion A2 is formed by droplets ejected from the head 201b.

[0063] As shown in Fig. 5, the mask portion A3 of the landing dot A is formed by droplets ejected from the nozzles in the nozzle overlap region 202 of the head 201a and the head 201b. The mask portion A3 of the landing dot A shown in Fig. 5 shows an example in which XY uniform mask processing has been performed in which the print dots formed by the head 201a and the head 201b are arranged alternately in both the X and Y directions. This XY uniform mask processing creates an image in the mask portion A3 by mixing the print dots of the two heads 201a and 201b, thereby suppressing image quality degradation such as uneven density and streaks caused by variations in the ejection characteristics of the heads 201a and 201b and landing deviations caused by air currents at the ends of the liquid ejection heads.

[0064] Incidentally, the amount of droplets discharged from a liquid discharge head generally varies due to the difference in the residual vibration of the pressure wave remaining after discharge depending on the drive frequency of the drive waveform, as shown in Figure 6. Figure 6 shows an example in which a droplet amount of 1 at drive frequency F drops to a droplet amount of 2 when the drive frequency becomes (1 / 2)F.

[0065] More specifically, as shown in Fig. 7(a), when the XY uniform mask process is performed in the nozzle overlap region 202 of the two heads 201a and 201b to distribute the print dots, the ejection interval in the masked portion A3 for a single head differs from the ejection interval in the normal portions A1 and A2. As a result, as shown in Fig. 7(b), the drive frequency per nozzle in the masked portion A3 of the landing dot A corresponding to the nozzle overlap region 202 is lowered to (1 / 2)F compared to the drive frequency F of the normal portions A1 and A2. Therefore, the normal portions A1 and A2 are formed with print dots of "droplet volume 1", and the masked portion A3 is formed with print dots of "droplet volume 2", so that the masked portion A3 becomes thinner than the normal portions A1 and A2, resulting in white unevenness.

[0066] 8, if the landing position of the print dots of one head is relatively shifted due to the positional misalignment (ΔY) between the two heads 201a and 201b in the Y direction or the difference in droplet speed between the two heads 201a and 201b, the print dots of heads 201a and 201b will land overlapping, and the masked area A3 will not be able to achieve the same density as the normal areas A1 and A2. This also poses the problem of being visually recognized as uneven density or streaks.

[0067] Therefore, in this embodiment, the image quality in the nozzle overlap region 300 at the ends of two adjacent heads (see FIG. 9) is made uniform by using a mask pattern that reduces the occurrence of density unevenness and streaks caused by differences in the characteristics of the drive frequency of the ejection droplet volume between the heads, or differences in positional misalignment and droplet speed between the heads.

[0068] 9 is a diagram showing an example of a mask pattern according to the first embodiment. Here, a nozzle overlap region 300 of two heads 122a and 122b will be described as an example.

[0069] 9, mask portion A3 of landing dot A is formed by droplets ejected from nozzles in nozzle overlap region 300 of head 122a and head 122b. Here, the length of mask portion A3 in the X direction is 12 pixels. Meanwhile, nozzle overlap region 300 can be imaged with a total of 24 nozzles, consisting of 12 nozzles of head 122a and 12 nozzles of head 122b, so there are twice as many nozzles as in normal portions A1 and A2.

[0070] As shown in FIG. 9, the ejection control unit 212 of the control unit 101 sets the nozzles 1a that are odd-numbered from the head end to "used" in the nozzle row of the nozzle overlap region 300 of the head 122a, and sets the nozzles 1b that are even-numbered from the head end to "unused". Also, the ejection control unit 212 of the control unit 101 sets the nozzles 2a that are odd-numbered from the head end to "used" in the nozzle row of the nozzle overlap region 300 of the head 122b, and sets the nozzles 2b that are even-numbered to "unused". As a result, as shown in FIG. 9, in the nozzle overlap region 300, the nozzles 1a (used) of the head 122a and the nozzles 2b (unused) of the head 122b overlap, and the nozzles 1b (unused) of the head 122a and the nozzles 2a (used) of the head 122b overlap.

[0071] In this way, as shown in Figure 9, in masking the nozzle overlap region 300, the ejection control unit 212 of the control unit 101 alternates between printing dots formed by head 122a and head 122b in the X direction, but creates a vertical striped mask pattern in which printing dots formed by the same heads 122a and 122b are continuous in the Y direction.

[0072] In the example shown in Fig. 9(a), the ejection interval in the masked portion A3 for a single head is the same as the ejection interval in the normal portions A1 and A2, so that the print dots in the normal portions A1 and A2 and the masked portion A3 have the same drive frequency. Therefore, since there is no effect from the drive frequency characteristics as shown in Fig. 6, there is no difference in droplet volume due to the difference in drive frequency characteristics as shown in Fig. 7, and the dot sizes of the print dots in the normal portions A1 and A2 and the masked portion A3 can be matched.

[0073] Furthermore, as shown in Fig. 9(b), even if a position shift (Y shift) ΔY occurs in the Y direction between the two heads 122a, 122b, the mask pattern is vertically striped to connect print dots formed by the same heads 122a, 122b in the Y direction, so the print dots do not overlap as in Fig. 8. Therefore, the mask pattern according to this embodiment can suppress image quality degradation such as uneven density and streaks in the nozzle overlap region 300 between the adjacent heads 122a, 122b more effectively than the conventional mask pattern.

[0074] Thus, according to this embodiment, the mask pattern of the nozzle overlap region 300 at the head end of the adjacent heads 122a and 122b is arranged such that the print dots formed by the head 122a and the print dots formed by the head 122b are alternately arranged in the X direction, but in the Y direction, it is composed of only print dots formed by the same head. This makes it possible to suppress the occurrence of uneven density and streaks in the nozzle overlap region 300 at the head end of the two adjacent heads 122a and 122b due to the difference in the characteristics of the drive frequency of the ejection droplet volume between the two heads 122a and 122b, or the difference in positional deviation or droplet speed between the two heads 122a and 122b, and makes it possible to uniform the image quality of the nozzle overlap region 300 at the head end of the adjacent heads 122a and 122b.

[0075] Furthermore, according to this embodiment, even if a position shift (Y shift) △Y occurs in the Y direction between the two heads 122a, 122b, it is possible to suppress image quality degradation such as uneven density and streaks in the nozzle overlap area 300 between the adjacent heads 122a, 122b.

[0076] 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).

[0077] 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.

[0078] 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.

[0079] 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.

[0080] Second embodiment Next, a second embodiment will be described.

[0081] The second embodiment differs from the first embodiment in that the usage rate of the end nozzles of the head is reduced. In the following description of the second embodiment, the description of the same parts as in the first embodiment will be omitted, and only the parts that are different from the first embodiment will be described.

[0082] FIG. 10 is a diagram showing an example of a mask pattern according to the second embodiment, and FIG. 11 is a graph showing an example of the nozzle usage rate in the nozzle overlap region 300. As shown in FIG.

[0083] As shown in FIG. 10, in the mask processing of the nozzle overlap area 300 of the heads 122a and 122b, the ejection control unit 212 of the control unit 101 of this embodiment mixes the printing dots formed by the head 122a and the printing dots formed by the head 122b in the X direction, and creates a vertical striped mask pattern in which the printing dots formed by the same heads 122a and 122b are connected in the Y direction.

[0084] 9 described in the first embodiment, the print dots formed by the head 122a and the print dots formed by the head 122b are arranged alternately in the X direction. On the other hand, the ejection control unit 212 of the control unit 101 of this embodiment reduces the nozzle usage rate of the heads 122a and 122b as they approach the ends of the heads 122a and 122b, as shown in FIGS.

[0085] 10, the ejection control unit 212 of the control unit 101 sets the 3rd, 6th, 8th, 9th, 11th, and 12th nozzles 1a from the head end in the nozzle row of the nozzle overlap region 300 of the head 122a to "use" and sets the 1st, 2nd, 4th, 5th, 7th, and 10th nozzles 1b from the head end in "non-use". Also, the ejection control unit 212 of the control unit 101 sets the 3rd, 6th, 8th, 9th, 11th, and 12th nozzles 2a from the head end in the nozzle row of the nozzle overlap region 300 of the head 122b to "use" and sets the 1st, 2nd, 4th, 5th, 7th, and 10th nozzles 2b in "non-use".

[0086] In the example shown in Figures 10 and 11, as in Figure 9, the ejection interval in the masked portion A3 for a single head is the same as the ejection interval in the normal portions A1 and A2, so that the print dots in the normal portions A1 and A2 and the masked portion A3 have the same drive frequency. Therefore, there is no effect from the drive frequency characteristics as in Figure 6, and no difference in droplet volume due to the difference in drive frequency characteristics as in Figure 7 occurs.

[0087] Furthermore, in the example shown in Figures 10 and 11, even if a position shift (Y shift) △Y occurs in the Y direction between the two heads 122a, 122b, the mask pattern is vertically striped to make the printing dots formed by the same heads 122a, 122b continuous in the Y direction, so the printing dots do not overlap as in Figure 8.

[0088] Furthermore, generally, nozzles closer to the ends of a liquid ejection head are more likely to be affected by air currents and become curved, or have differences in characteristics such as crosstalk. However, in the example shown in Figures 10 and 11, by reducing the usage rate of the end nozzles of the two heads 122a, 122b, degradation in image quality due to the effects of air currents and the like can be made less noticeable.

[0089] Thus, according to this embodiment, in addition to the effects described in the first embodiment, by reducing the frequency of use of the end nozzles of the two heads 122a, 122b in the nozzle overlap region 300, it is possible to reduce the usage rate of the end nozzles of the liquid ejection heads, which are prone to differences in characteristics such as bending and crosstalk due to the influence of air currents, and therefore it is possible to make image quality degradation due to the influence of air currents, etc. less noticeable.

[0090] (Third embodiment) Next, a third embodiment will be described.

[0091] The third embodiment differs from the first embodiment in that a mask pattern is used that does not use nozzles on the most upstream side of the airflow caused by movement of the carriage in the Y direction. In the following description of the third 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.

[0092] Fig. 12 is a diagram showing an example of a mask pattern according to the third embodiment. As shown in Fig. 12, the heads 122a and 122b of this embodiment have two nozzle rows each consisting of a plurality of nozzles. The two nozzle rows of the heads 122a and 122b of this embodiment are obtained by dividing the single nozzle row in the first embodiment into two rows, one every other nozzle row.

[0093] As shown in FIG. 12, in the mask processing of the nozzle overlap region 300, the ejection control unit 212 of the control unit 101 of this embodiment mixes the printing dots formed by the head 122a and the printing dots formed by the head 122b in the X direction, and creates a vertical striped mask pattern in the Y direction by connecting the printing dots formed by the same heads 122a and 122b.

[0094] In the example shown in Fig. 12, the carriage 121 moves from top to bottom in Fig. 12. As shown in Fig. 12, the head 122b is disposed upstream of the head 122a in the movement direction of the carriage 121. As shown in Fig. 12, the ejection control unit 212 of the control unit 101 of this embodiment sets to "unused" the nozzle 2b in the nozzle row on the most upstream side in the movement direction of the carriage 121 in the nozzle overlap region 300 of the head 122b, which is susceptible to the influence of air currents accompanying the movement of the carriage 121 in the Y direction.

[0095] In the example shown in Fig. 12, as in Fig. 9, the ejection interval in the masked portion A3 for a single head is the same as the ejection interval in the normal portions A1 and A2, so that the drive frequency is the same for the printed dots in the normal portions A1 and A2 and the masked portion A3. Therefore, there is no effect of the characteristics of the drive frequency as shown in Fig. 6, and there is no difference in droplet volume due to the difference in the characteristics of the drive frequency as shown in Fig. 7. Also, even if a position shift (Y shift) △Y occurs in the Y direction between the two heads 122a and 122b, the vertical stripe mask pattern makes the printed dots formed by the same heads 122a and 122b continuous in the Y direction, so the printed dots do not overlap as in Fig. 8.

[0096] Furthermore, in the example shown in FIG. 12, the mask pattern does not use the nozzles on the most upstream side in the moving direction of the carriage 121, so degradation of image quality caused by droplet bending due to air currents can be made less noticeable.

[0097] In addition, when the airflow accompanying the movement of the carriage 121 in the Y direction is upside down in Fig. 12, the ejection control unit 212 of the control unit 101 in this embodiment sets to "unused" the nozzle 1b of the nozzle row most upstream in the movement direction of the carriage 121 in the nozzle overlap region 300 of the head 122a, which is easily affected by the airflow. This makes it possible to apply it to multi-pass printing.

[0098] Thus, according to this embodiment, in addition to the effects described in the first embodiment, by not using the nozzles on the most upstream side in the direction of movement of the carriage 121 (the direction intersecting the row direction of the nozzle rows) in the nozzle overlap area 300 of the heads 122a and 122b, it is possible to make image quality degradation caused by droplet bending due to air currents less noticeable.

[0099] In this embodiment, heads 122a, 122b having two nozzle rows have been described, but this is not limited to this and may be a liquid ejection head having eight nozzle rows as shown in FIG. 13 or a liquid ejection head with another row configuration.

[0100] In this embodiment, the multi-pass method in which the carriage 121 reciprocates to drop ink has been described, but the present invention is not limited to this, and can also be applied to a line head method in which the liquid ejection head is fixed and the medium is moved. In the case of the line head method, a mask pattern that does not use the most upstream nozzles that are susceptible to the air current in the medium transport direction (the direction intersecting the row direction of the nozzle rows) can be used.

[0101] (Fourth embodiment) Next, a fourth embodiment will be described.

[0102] The fourth embodiment differs from the first embodiment in that the usage rate of nozzles in the end region of the head where droplet bending occurs is reduced. In the following explanation of the fourth embodiment, the explanation of the same parts as in the first embodiment will be omitted, and only the parts different from the first embodiment will be explained.

[0103] FIG. 14 is a diagram showing an example of a mask pattern according to the fourth embodiment, and FIG. 15 is a diagram showing an example of the state of ejected droplets in an end region of a liquid ejection head.

[0104] As shown in FIG. 14, in masking the nozzle overlap area 300 of the heads 122a and 122b, the ejection control unit 212 of the control unit 101 of this embodiment mixes the printing dots formed by the head 122a and the printing dots formed by the head 122b in the X direction, and creates a vertical striped mask pattern in which the printing dots formed by the same heads 122a and 122b are connected in the Y direction.

[0105] As shown in FIG. 15, the heads 122a and 122b can land droplets a, which are ejected from the center of the heads 122a and 122b in the vertical direction (Z direction) toward the medium 40, at target positions on the medium 40.

[0106] On the other hand, as shown in Fig. 15, the heads 122a and 122b eject droplets b ejected from the head ends of the heads 122a and 122b in a vertical direction toward the medium 40 are blown away by the end air currents, and the landing position is shifted from the target position on the medium 40. Note that Fig. 15 shows a case where the landing position is bent from the target position on the medium 40 to the outside of the head, but depending on conditions such as the drive frequency, droplet size, and print gap, it may be bent toward the center of the head. In this way, if the heads 122a and 122b eject droplets b ejected from the head ends are used in large quantities in the mask pattern of the nozzle overlap region 300, there is a problem that image quality deterioration becomes noticeable.

[0107] 14, the ejection control unit 212 of the control unit 101 of this embodiment sets the distance X1 from the most end nozzle to the second end nozzle in the nozzle overlap region 300 of the head 122a to be longer than the distance X2 from the second end nozzle to the nozzle inside the second end nozzle. This makes it possible to reduce the nozzle usage rate in the head end region of the head 122a where droplet bending occurs, making image quality degradation less noticeable.

[0108] 14, the ejection control unit 212 of the control unit 101 sets the 1st, 6th, 8th, 9th, 10th, and 11th nozzles 1a from the head end in the nozzle row of the nozzle overlap region 300 of the head 122a to "used", and sets the 2nd, 3rd, 4th, 5th, 7th, and 12th nozzles 1b from the head end in "unused". Also, the ejection control unit 212 of the control unit 101 sets the 1st, 6th, 8th, 9th, 10th, and 11th nozzles 2a from the head end in the nozzle row of the nozzle overlap region 300 of the head 122b to "used", and sets the 2nd, 3rd, 4th, 5th, 7th, and 12th nozzles 2b in "unused".

[0109] In the example shown in Fig. 14, as in Fig. 9, the ejection interval in the masked portion A3 for a single head is the same as the ejection interval in the normal portions A1 and A2, so that the print dots in the normal portions A1 and A2 and the masked portion A3 have the same drive frequency. Therefore, there is no effect of the drive frequency characteristics as in Fig. 6, and there is no difference in droplet volume due to the difference in drive frequency characteristics as in Fig. 7. Also, even if a position shift (Y shift) △Y occurs between the two heads 122a and 122b in the Y direction, the mask pattern is vertically striped to make the print dots formed by the same heads 122a and 122b continuous in the Y direction, so the print dots do not overlap as in Fig. 8.

[0110] Thus, according to this embodiment, in addition to the effects described in the first embodiment, by increasing the distance between the nozzles used toward the ends of the liquid ejection head, the nozzle usage rate in the head end regions of the liquid ejection head where droplet bending due to air currents is likely to occur is reduced, making image quality degradation less noticeable.

[0111] In this embodiment, the heads 122a and 122b having two nozzle rows have been described, but the present invention is not limited to this and may be a liquid ejection head having eight nozzle rows as shown in Fig. 16, or a liquid ejection head having another row configuration. In the example shown in Fig. 16, the distance X1 from the endmost used nozzle to the second end used nozzle in the X direction in the nozzle overlap region 300 of the head 122a is longer than the distance X2 between the second end used nozzle and the used nozzle inside it.

[0112] 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.

[0113] 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.

[0114] 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).

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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. [Explanation of symbols]

[0121] 100 Liquid ejection device 101 Control section 122 Liquid ejection head 122a, 122b, 122c Head 212 Discharge control section 300 Nozzle overlap area [Prior art documents] [Patent documents]

[0122] [Patent Document 1] Japanese Patent Publication No. 3702711

Claims

1. A liquid ejection head has a plurality of heads which selectively eject liquid droplets from nozzles arranged in a nozzle row, the nozzles being each made up of a plurality of nozzles, the adjacent heads being disposed at ends of the nozzle rows in a row direction such that a nozzle overlap region is provided, an ejection control unit that configures data of a mask pattern in the nozzle overlap region in a direction parallel to the row direction of the nozzle row with both pixel data by one head of the plurality of heads and pixel data by another head of the plurality of heads, and configures data of a direction intersecting the row direction of the nozzle row with either pixel data by the one head or pixel data by the other head; A liquid ejection head comprising:

2. the ejection control unit reduces a usage rate of end nozzles of the one head and the other head in the nozzle overlap region, 2. The liquid ejection head according to claim 1.

3. the discharge control unit disables the nozzles of the nozzle row on the most upstream side in a direction intersecting the row direction of the nozzle rows in the nozzle overlap region.

2. The liquid ejection head according to claim 1.

4. the discharge control unit makes a distance from a most end use nozzle to a second end use nozzle in the nozzle overlap region longer than a distance from the second end use nozzle to a use nozzle located inside the second end use nozzle; 2. The liquid ejection head according to claim 1.

5. The nozzle overlap region has twice the number of nozzles as the number of nozzles in a normal region other than the nozzle overlap region.

2. The liquid ejection head according to claim 1.

6. A liquid ejection head according to claim 1 , 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:

7. A liquid ejection head according to claim 1 , A control unit that drives the liquid ejection head to eject liquid; A liquid ejection device comprising:

8. A liquid ejection method for a liquid ejection head, comprising: a plurality of heads each having a nozzle row including a plurality of nozzles arranged therein and each of which selectively ejects liquid droplets from the nozzles; and adjacent heads are disposed at ends of the nozzle rows in a row direction such that a nozzle overlap area is provided between the adjacent heads, the method comprising the steps of: an ejection control step of configuring data in a direction parallel to the column direction of the nozzle row with respect to a mask pattern in the nozzle overlap region by both pixel data by one head of the plurality of heads and pixel data by another head of the plurality of heads, and configuring data in a direction intersecting the column direction of the nozzle row by either pixel data by the one head or pixel data by the other head; A liquid ejection method comprising:

9. a computer for controlling a liquid ejection head, the liquid ejection head having a plurality of heads for selectively ejecting liquid droplets from nozzles arranged in a nozzle row, the heads being adjacent to each other and provided with a nozzle overlap area at an end of the nozzle row in a row direction; functioning as an ejection control unit that configures data in a direction parallel to the column direction of the nozzle array with respect to a mask pattern in the nozzle overlap region using both pixel data from one head of the plurality of heads and pixel data from another head of the plurality of heads, and configures data in a direction intersecting the column direction of the nozzle array using either pixel data from the one head or pixel data from the other head; A program characterized by:

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