Liquid discharge head, liquid discharge unit, liquid discharge apparatus and method, and computer program product

Abstract

The invention relates to a liquid discharge head, a liquid discharge unit, a liquid discharge apparatus, a liquid discharge method, and a computer program product. The objective of the invention is to make the image quality of nozzle overlapping areas of adjacent liquid discharge head ends uniform. A liquid discharge head according to the present invention has a plurality of discharge heads in which a nozzle row comprising a plurality of nozzles is arranged and liquid droplets are selectively discharged from the nozzles, and adjacent discharge heads in the liquid discharge heads are provided with nozzle overlap regions at the ends in the nozzle row direction. In the mask pattern of the nozzle overlap region, data in a direction parallel to the nozzle array direction is configured by both pixel data of one of the plurality of discharge heads and pixel data of another of the plurality of discharge heads, and data in a direction intersecting the nozzle array direction is configured by both pixel data of the other discharge head and pixel data of the other discharge head. The pixel data of any one of the pixel data of the one discharge head and the pixel data of the other discharge head is configured.

Description

Technical Field

[0001] The present invention relates to a liquid discharge head, a liquid discharge unit, a liquid discharge apparatus, a liquid discharge method, and a computer program product. Background Art

[0002] There are some disclosed technical proposals in the past regarding image processing of the nozzle overlap region between the end portions of adjacent liquid discharge heads.

[0003] Patent document JP Patent No. 3702711 discloses a technique for suppressing image quality degradation in the nozzle overlap region of the liquid discharge heads by forming a mask in the nozzle overlap region and mixing print dots with two liquid discharge heads to form an image.

[0004] However, as in the prior art, if the print dots are distributed in the nozzle overlap area of ​​the two liquid discharge heads, the driving frequency of each nozzle in the nozzle overlap area is lower than that of the ordinary nozzle area outside the nozzle overlap area. Generally speaking, the amount of droplets discharged by the liquid discharge head mostly changes with the driving frequency, thereby changing the size of the print dots in the nozzle overlap area where the mask is formed. In this way, there is a portion in the nozzle overlap area where the print dot size changes, resulting in uneven density or streaks.

[0005] It is ideal that the print dots discharged from the two liquid discharge heads in the nozzle overlap area forming the mask fall at the ideal position. However, if the positional deviation and the difference in the drop speed between the two liquid discharge heads cause the drop position of the print dots of one of the liquid discharge heads to deviate relatively, the same degree of concentration as that of the ordinary nozzle area cannot be obtained. In this way, the portion that cannot obtain the same degree of concentration as that of the ordinary nozzle area will also have problems of uneven concentration or stripes. Summary of the invention

[0006] The present invention is a technical solution proposed in view of the above-mentioned problem, and its object is to make the image quality of the nozzle overlapping area at the end portions of adjacent liquid discharge heads uniform.

[0007] In order to solve the above-mentioned problems and achieve the above-mentioned objectives, the present invention provides a liquid discharge head, which has a plurality of discharge heads, in which a nozzle column composed of a plurality of nozzles is arranged, and droplets are selectively discharged from the nozzles. Adjacent discharge heads in the liquid discharge heads are provided with nozzle overlapping areas at the ends in the column direction of the nozzle column. The head is characterized in that it is provided with a discharge control unit for constituting data in a direction parallel to the column direction of the nozzle column in a mask pattern of the nozzle overlapping area by both pixel data of one of the plurality of discharge heads and pixel data of another of the plurality of discharge heads, and data in a direction intersecting the column direction of the nozzle column by pixel data of either the one discharge head or the other discharge head.

[0008] The present invention has the effect of making the image quality uniform in the nozzle overlapping region at the head end portions of adjacent liquid discharge heads. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a perspective view of the inside of the image forming apparatus according to the first embodiment.

[0010] Figure 2 It is a schematic diagram of the structure of an image forming apparatus.

[0011] Figure 3 This is a block diagram of an example of the hardware structure of an image forming apparatus.

[0012] Figure 4 This is an example functional block diagram of the control unit.

[0013] Figure 5 This is a schematic diagram of an example of a conventional mask pattern when the end nozzles of two ejection heads arranged in the X direction are arranged in an overlapping manner.

[0014] Figure 6 This is a driving frequency characteristic diagram of the ejection droplet amount in the past.

[0015] Figure 7 This is a schematic diagram of the drive frequency characteristics and the conventional mask pattern.

[0016] Figure 8 It is a schematic diagram of Y deviation and past mask patterns.

[0017] Fig. 9 It is a schematic diagram of an example of a mask pattern involved in the first embodiment.

[0018] Fig.10 It is a schematic diagram of an example of a mask pattern involved in the second embodiment.

[0019] Fig.11This is a schematic diagram showing an example of graphing the nozzle usage rate in the nozzle overlap area.

[0020] Fig.12 It is a schematic diagram of an example of a mask pattern involved in the third embodiment.

[0021] Fig.13 is a schematic diagram of another example of a mask pattern.

[0022] Fig.14 It is a schematic diagram of an example of a mask pattern involved in the fourth embodiment.

[0023] Fig.15 is a schematic diagram of discharged liquid droplets at the end region of the liquid discharge head.

[0024] Fig.16 is a schematic diagram of another example of a mask pattern.

[0025] Explanation of symbols

[0026] 100 Liquid discharge device

[0027] 101 Control Department

[0028] 122 Liquid discharge head

[0029] 122a, 122b, 122c discharge head

[0030] 212 Discharge control unit

[0031] 300 Nozzle overlap area DETAILED DESCRIPTION

[0032] Embodiments of a liquid discharge head, a liquid discharge unit, a liquid discharge device, a liquid discharge method, and a computer program product are described in detail below with reference to the accompanying drawings.

[0033] Hereinafter, an image forming apparatus will be described as an example of a liquid ejecting apparatus applicable to the present invention, but the present invention is not limited thereto.

[0034] <First Embodiment>

[0035] Figure 1 It is a perspective view of the inside of the image forming apparatus 100 according to the first embodiment. Figure 2 Schematic diagram of the structure of the image forming apparatus 100. Figure 1 and Figure 2 As shown, the image forming apparatus 100 of the present embodiment is a wide-format serial inkjet recording apparatus.

[0036] This embodiment uses a wide-format serial inkjet printer as an example to illustrate a liquid injection device suitable for the present invention, but any image forming device such as a multifunction peripheral, printer, scanner, fax device, etc. that has at least two of the copying function, printing function, scanning function and fax function can be applicable to the present invention.

[0037] like Figure 1 and Figure 2 As shown, the image forming apparatus 100 includes side plates 21A and 21B on the left and right sides of the apparatus body 100a. The side plates 21A and 21B are used to mount a main guide rod 31 as a guide member. The image forming apparatus 100 further includes an auxiliary metal plate guide rail 32. The main guide rod 31 and the auxiliary metal plate guide rail 32 hold the carriage 121, and the carriage 121 can slide.

[0038] The carriage 121 is driven by the main scanning motor 117 (see Figure 3 ) is driven to rotate the timing belt, moves in the direction of arrow Y (main scanning direction), and moves relative to the medium 40. The movement of the carriage 121 can also be called scanning. The carriage 121 is also equipped with an optical sensor 37 for detecting the end of the medium 40 (paper end).

[0039] The optical sensor 37 is an example of a reading unit for outputting a read signal of an image previously formed on the medium 40 by the image forming apparatus 100. As the optical sensor 37, a device for detecting reflection density, a camera for photographing an image formed on the medium 40, or the like can be used.

[0040] The carriage 121 has discharge heads 122a, 122b, and 122c (these three discharge heads 122a, 122b, and 122c are collectively referred to as "liquid discharge heads 122") for discharging ink droplets (liquids) of various colors, such as yellow (Y), cyan (C), magenta (M), black (K), orange (O), green (G), and transparent (Cl), according to the installed ink cartridge 10.

[0041] The conveying roller is driven by the sub-scanning motor 118 (see Figure 3 ) is driven to rotate, so that the medium 40 moves in a sub-scanning direction (the direction of arrow X) that is substantially orthogonal to the main scanning direction (the Y direction), thereby moving relative to the liquid discharge head 122. However, the main scanning direction (the Y direction) and the sub-scanning direction (the X direction) do not necessarily need to be substantially perpendicular, and they only need to intersect.

[0042] The nozzle array composed of a plurality of nozzles (not shown) of the discharge heads 122a, 122b, and 122c is arranged in the sub-scanning direction (X direction). The discharge heads 122a, 122b, and 122c are installed so that the discharge direction of ink droplets discharged from the nozzles is oriented downward (Z direction, see Fig.15The ejection heads 122a, 122b, and 122c are respectively arranged to overlap in the sub-scanning direction (X direction). The carriage 121 carries a sub-tank for supplying inks of respective colors corresponding to the ejection heads 122a, 122b, and 122c.

[0043] The "liquid discharge head" refers to a functional component that discharges or ejects liquid from a nozzle. The discharged liquid is not particularly limited as long as it has a viscosity or surface tension that can be discharged from the liquid discharge head 122, but preferably has a viscosity of 30 MPa·s or less at room temperature and pressure or after heating or cooling. More specifically, it is a solvent, suspension, emulsion, etc. containing solvents such as water or organic solvents, colorants such as dyes or pigments, functional materials such as polymers, resins, surfactants, biocompatible materials such as DNA, amino acids or proteins, calcium, edible materials such as natural dyes, etc. These can be used, for example, for inkjet inks, surface treatment liquids, components of electronic components or light-emitting components, or circuit anti-etching pattern forming liquids, three-dimensional modeling material liquids, etc.

[0044] The energy generation source for discharging liquid as the “liquid discharge head” includes a device using a pressure generating device such as a piezoelectric actuator (a stacked piezoelectric element and a thin film piezoelectric element).

[0045] There is no limitation on the pressure generating device used in the "liquid discharge head". For example, in addition to using the piezoelectric actuator (stacked piezoelectric element) as described above, a thermal actuator using an electrothermal conversion element such as a heating resistor, an electrostatic actuator composed of a vibration plate and an opposing electrode, etc. may also be used.

[0046] The image forming apparatus 100 includes a cartridge loading unit 1 in which ink cartridges 10y, 10c, 10m, and 10k (collectively referred to as “ink cartridges 10” when not distinguished) of respective colors are detachably mounted.

[0047] The ink in the ink cartridge 10 is supplied to the sub-tank on the carriage 121 through the supply pipes 36 for each color by the supply pump unit for replenishment. The supply pump unit and the supply pipe 36 constitute a supply mechanism. The ink cartridge 10 may also include a white ink cartridge.

[0048] The image forming apparatus 100 includes a maintenance recovery mechanism 81 in a non-printing area in the main scanning direction (Y direction) of the carriage 121. The maintenance recovery mechanism 81 maintains and / or recovers the state of the nozzles of the liquid discharge head 122.

[0049] The maintenance recovery mechanism 81 includes cap members 82a, 82b, 82c (collectively referred to as "cap members 82" when not distinguished) for covering the nozzle surfaces of the liquid discharge head 122, a wiping unit 83 for wiping the nozzle surfaces, etc. A replaceable waste liquid tank is provided below the maintenance recovery mechanism 81 of the liquid discharge head 122 to store waste liquid generated by the maintenance recovery action.

[0050] The "liquid discharge unit" is an integrated unit that integrates functional components and mechanisms in the liquid discharge head 122, and is a collection of components related to liquid ejection. For example, the "liquid discharge unit" includes a unit that combines at least one of the discharge head tank (sub-tank of the carriage 121), the carriage 121, the supply mechanism, the maintenance recovery mechanism 81, and the main scanning movement mechanism with the liquid discharge head 122.

[0051] Here, the so-called integration means, for example, a unit including the liquid discharge head 122 and the functional components and mechanisms being fixed to each other by fastening, bonding, snapping, etc., and one being held movably relative to the other. The liquid discharge head 122, the functional components and the mechanisms may also be configured to be detachable from each other.

[0052] As for the liquid discharge unit, there is a unit in which the liquid discharge head 122 and the discharge head tank are integrally formed, for example. There is also a unit in which the liquid discharge head 122 and the discharge head tank are connected to each other by a pipe or the like so that the liquid discharge head 122 and the discharge head tank are integrated. A unit including a filter may be added between the discharge head tank and the liquid discharge head 122 of these liquid discharge units.

[0053] An integrated unit of the liquid discharge head 122 and the carriage 121 may also serve as a liquid discharge unit.

[0054] As a liquid discharge unit, there is a structure in which the liquid discharge head 122 is held movably on a main guide rod 31 as a guide member constituting a part of the main scanning movement mechanism, so that the liquid discharge head 122 and the main scanning movement mechanism are integrated. There is also a structure in which the liquid discharge head 122, the carriage 121 and the main scanning movement mechanism are integrated.

[0055] As the liquid discharge unit, there is a cap member 82 as a part of the maintenance and recovery mechanism 81 fixed to the carriage 121 provided with the liquid discharge head 122, so that the liquid discharge head 122, the carriage 121 and the maintenance and recovery mechanism 81 are integrally formed.

[0056] Furthermore, as a liquid discharge unit, there is a structure in which a supply pipe 36 is connected to a liquid discharge head 122 equipped with a discharge head tank (sub-tank of the carriage 121) or a flow path member, and the liquid discharge head 122 is integrally formed with a supply mechanism. Liquid from a liquid storage source is supplied to the liquid discharge head 122 through the pipe.

[0057] The main scanning movement mechanism further includes a main guide rod 31 as a guide member. The supply mechanism further includes a supply pipe 36 and a cartridge loading unit 1.

[0058] Figure 3 FIG. 1 is a block diagram of an example of a hardware structure of the image forming apparatus 100. Figure 3As shown, the image forming apparatus 100 includes a control unit 101, an operation panel 114, an environmental 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 discharge head 122, and a moving mechanism 140.

[0059] like Figure 3 As shown, the control unit 101 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 103, a RAM (Random Access Memory) 104, an 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 driving unit 109, a sub-scanning motor driving unit 110, a fan control unit 111, a heater control unit 112, and an I / O (input / output) 113. The control unit 101 may also include components other than those described above.

[0060] CPU 102 , ROM 103 , RAM 104 , NVRAM 105 , ASIC 106 , I / F (interface) 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 in a manner that allows them to communicate with each other, such as via a bus.

[0061] CPU 102 controls the overall operation of image forming apparatus 100. Specifically, CPU 102 implements various functions by executing programs stored in ROM 103 or the like.

[0062] ROM 103 stores programs and other fixed data executable by CPU 102. RAM 104 temporarily stores image data. NVRAM 105 retains data even when the power of image forming apparatus 100 is turned off. ASIC 106 is a circuit for processing image processing such as various signal processing and rearrangement, and for controlling input and output signals of other devices as a whole.

[0063] I / F 107 is an interface circuit for sending and receiving data and signals with a host. Specifically, 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 or a network. That is, the generation and output of print data for the control unit 101 can also be performed by the printer driver of the host.

[0064] The print control unit 108 is a circuit that generates a drive waveform for driving the liquid discharge head 122 and outputs print data for selecting a drive pressure generating mechanism and various accompanying data to the discharge head driver 116. The pressure generated by the pressure generating mechanism causes the liquid discharge head 122 to discharge liquid (ink) from the nozzle.

[0065] The main scanning motor driving unit 109 is a circuit for driving the main scanning motor 117. The sub-scanning motor driving 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 as to blow air at a predetermined temperature and volume.

[0066] The heater control unit 112 is a circuit for controlling the heater 120 to reach a set temperature. The I / O 113 is a circuit for obtaining information from the environment sensor 115 and extracting information required for controlling each unit of the image forming apparatus 100. The I / O 113 also inputs detection signals from various sensors other than the environment sensor 115 (for example, the optical sensor 37).

[0067] The operation panel 114 is a device for inputting and displaying various information such as user specification of 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 communicable with each other.

[0068] The environment sensor 115 is a sensor that detects, for example, environment temperature or environment humidity, etc. The environment sensor 115 is connected to the I / O 113 of the control unit 101 .

[0069] The discharge head driver 116 is a circuit that drives the liquid discharge head 122 by selectively applying a drive pulse constituting a drive waveform supplied from the print controller 108 to a pressure generating device of the liquid discharge head 122 according to input image data (e.g., dot pattern data). The discharge head driver 116 is connected to the print control section 108 of the control section 101. For example, the ejection amount is controlled by controlling the amplitude of the drive waveform input to the pressure generating device of the liquid discharge head 122, but other means may be used to control the liquid discharge amount.

[0070] The main scanning motor 117 drives a timing belt to rotate and moves a carriage 121 having a liquid discharge head 122 in a main scanning direction (direction of arrow Y). The main scanning motor 117 is connected to a main scanning motor driving unit 109 of the control unit 101 .

[0071] The sub-scanning motor 118 is a device that drives the medium 40, which is the object to be ejected by the liquid ejection head 122, to be transported in the sub-scanning direction (X direction). The sub-scanning motor 118 is connected to the sub-scanning motor driving unit 110 of the control unit 101.

[0072] The moving mechanism 140 relatively moves the liquid discharge head 122 and the medium 40. The moving mechanism 140 includes the main guide rod 31, the auxiliary metal plate guide 32, the carriage 121, and the conveying roller, and constitutes a main scanning moving mechanism.

[0073] The moving mechanism 140 moves the liquid discharge head 122 and the medium 40 relatively along the main scanning direction (Y direction) through the main rod 31, the auxiliary metal plate guide 32, and the carriage 121. The moving mechanism 140 moves the liquid discharge head 122 and the medium 40 relatively along the secondary scanning direction (X direction) through the conveying roller that conveys the medium 40. In this embodiment, the relative movement of the moving mechanism 140 in the secondary scanning direction (X direction) is intermittent movement. Intermittent movement refers to movement in which movement and stop are performed alternately.

[0074] The fan 119 is a device that promotes air convection inside the image forming apparatus 100 by being driven to prevent the upper portion of the image forming apparatus 100 from excessively increasing in temperature due to stagnation of heated air. The fan 119 is connected to the fan control unit 11 of the controller 101 .

[0075] Figure 4 FIG. 1 is a functional block diagram of the control unit 101. Figure 3 Repeat the part.

[0076] like Figure 4 As shown, the control unit 101 includes a color plane division data generating unit 211 and a discharge control unit 212. The discharge control unit 212 basically controls the discharge of ink.

[0077] When the image data to be printed is input, the color plate segmentation data generating unit 211 generates color plate segmentation data for each ink color installed in the image forming apparatus 100 based on the input image data (for example, the input image). For example, when the image forming apparatus 100 prints using CMYK ink, the color plate segmentation data generating unit 211 generates color separation data for each color of CMYK based on the input image data.

[0078] The discharge control unit 212 generates printing dot data by using a dot data generation mask for 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 with two liquid discharge heads in the nozzle overlap region at the ends of the adjacent discharge heads 122a, 122b, and 122c.

[0079] The control unit 101 implements these functions (color plane division data generating unit 211, discharge control unit 212) by executing a predetermined program by the CPU 102. The control unit 101 may implement part or all of these functions by one or more processing circuits.

[0080] "Processing circuit" includes: a processor that is programmed by software to perform various functions, such as a processor installed through a circuit; and devices such as ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array) or existing circuit modules designed to perform the functions described above.

[0081] The control unit 101 controls the liquid discharge head 122 and the moving mechanism 140 to move the liquid discharge head 122 and the medium 40 relative to each other multiple times, and at the same time, the ink is arranged on the medium 40. The ink arranged on the medium 40 is fixed to the medium 40 to form a dot in the image. More specifically, after a single ink droplet formed by the ink discharged from the liquid discharge head 122 falls on the medium 40, it dries and is fixed on the medium 40, thereby forming a dot on the image. The image is formed by a collection of multiple dots.

[0082] Here, the problems of the conventional technology are described.

[0083] Figure 5 FIG. 1 is a schematic diagram of a mask pattern when the end nozzles of two discharge heads 201 a and 201 b arranged in the X direction are overlapped in the prior art. Figure 6 This is a graph showing the relationship between the discharge droplet amount and the driving frequency characteristics of the prior art. Figure 7 is a schematic diagram of the driving frequency characteristics and the mask pattern of the prior art, Figure 8 Schematic diagram of Y deviation and mask pattern of the prior art. Figure 5 In the embodiment, the number of nozzles in the overlapping nozzle overlap region 202 of the nozzles 201a and 201b is set to 12, but it can also be more or less.

[0084] Figure 5 The droplet A shown shows the state of a print dot when droplets discharged from the discharge heads 201a and 201b drop to an ideal position on the recording medium 203. The droplet A includes a normal portion A1, a normal portion A2, and a mask portion A3 corresponding to the nozzle overlap region 202.

[0085] like Figure 5As shown, the general portion A1 of the droplet point A is formed by the liquid droplets discharged from the discharge head 201a, and the general portion A2 is formed by the liquid droplets discharged from the discharge head 201b.

[0086] like Figure 5 As shown, the mask portion A3 of the droplet point A is formed by the liquid droplets discharged from the nozzles of the nozzle overlap region 202 of the discharge head 201 a and the discharge head 201 b . Figure 5 The mask portion A3 of the drop point A shown in the figure represents an example of XY uniform masking in which the print dots formed by the discharge head 201a and the discharge head 201b are alternately arranged in the X direction and the Y direction. Through this XY uniform masking, the mask portion A3 mixes the print dots of the two discharge heads 201a and 201b to form an image, thereby suppressing the deviation of the discharge characteristics of the discharge head 201a and the discharge head 201b, and the uneven concentration and streaks caused by the deviation of the drop caused by the airflow at the end of the liquid discharge head.

[0087] like Figure 6 As shown, generally, the residual vibration of the residual pressure wave after discharge varies with the driving frequency of the driving waveform, thereby causing the discharge amount of the liquid discharge head to vary. Figure 6 This is an example in which "liquid drop volume 1" at a driving frequency of F is reduced to "liquid drop volume 2" when the driving frequency is changed to (1 / 2)F.

[0088] Specifically, if Figure 7 As shown in (a), XY uniform masking is performed in the nozzle overlap area 202 of the two ejection heads 201a and 201b, and when distributing print dots, the ejection interval of a single ejection head on the mask portion A3 is different from the ejection interval on the ordinary portions A1 and A2. Figure 7 As shown in (b), the driving frequency of each nozzle of the mask portion A3 corresponding to the drop point A of the nozzle overlap area 202 is reduced to (1 / 2)F compared with the ordinary portions A1 and A2. As a result, the ordinary portions A1 and A2 are printed with "droplet amount 1", and the mask portion A3 is printed with "droplet amount 2", so that the mask portion A3 is sparser than the ordinary portions A1 and A2, resulting in white spots.

[0089] In addition, if Figure 8 As shown, due to the positional deviation (△Y) between the two discharge heads 201a and 201b in the Y direction or the difference in the drop speed between the two discharge heads 201a and 201b, if the drop position of the print dots of one discharge head is relatively deviated, the print dots of the discharge heads 201a and 201b overlap and drop, and the same degree of density as that of the ordinary parts A1 and A2 cannot be obtained in the mask part A3. This also presents the problem of uneven density or streaks.

[0090] In this regard, in this embodiment, the nozzle overlap region 300 (see Fig. 9 ) is used to homogenize the image quality of the nozzle overlap area 300 at the end of the discharge head by reducing the difference in the driving frequency characteristics of the droplet discharge amount between the discharge heads, or the mask pattern that reduces the concentration unevenness or streaks caused by the position deviation or droplet speed difference between the discharge heads.

[0091] Fig. 9 1 is a schematic diagram of an example of a mask pattern according to the first embodiment. Here, the nozzle overlap region 300 of two discharge heads 122a and 122b is described as an example.

[0092] like Fig. 9 As shown, the mask portion A3 of the droplet point A is formed by the droplets discharged from the nozzles of the nozzle overlap region 300 of the discharge head 122a and the discharge head 122b. Here, the length of the mask portion A3 in the X direction is 12 pixels. On the other hand, the nozzle overlap region 300 can be imaged using 12 nozzles of the discharge head 122a and 12 nozzles of the discharge head 122b, a total of 24 nozzles, so there are twice as many nozzles in the nozzle overlap region 300 as in the normal portions A1 and A2.

[0093] like Fig. 9 As shown, the discharge control unit 212 of the control unit 101 sets the odd-numbered nozzles 1a from the end of the discharge head 122a as "in use" and the even-numbered nozzles 1b from the end of the discharge head as "unin use". The discharge control unit 212 of the control unit 101 also sets the odd-numbered nozzles 2a from the end of the discharge head 122b as "in use" and the even-numbered nozzles 2b as "unin use". Fig. 9 As shown, in the nozzle overlap region 300, the nozzle 1a (used) of the discharge head 122a and the nozzle 2b (unused) of the discharge head 122b overlap, and the nozzle 1b (unused) of the discharge head 122a and the nozzle 2a (used) of the discharge head 122b overlap.

[0094] So Fig. 9 As shown, in the mask pattern formed by the discharge control unit 212 of the control unit 101 in the mask processing of the nozzle overlap area 300, the printing dots formed by the discharge head 122a and the printing dots formed by the discharge head 122b in the X direction are arranged alternately, and the printing dots formed by the same discharge heads 122a and 122b in the Y direction are continuously in the shape of vertical stripes.

[0095] exist Fig. 9In the example shown in (a), since the ejection interval of the mask part A3 of the single ejection head is the same as the ejection interval of the ordinary parts A1 and A2, the driving frequency of the print dots of the ordinary parts A1 and A2 and the mask part A3 is the same. Figure 6 The driving frequency characteristics shown will not affect Figure 7 The difference in droplet amount caused by the difference in driving frequency characteristics shown can make the print dot sizes of the ordinary parts A1, A2 and the mask part A3 consistent.

[0096] And if Fig. 9 As shown in (b) of FIG. 1 , even if the positional deviation (Y deviation) ΔY occurs between the two discharge heads 122a and 122b in the Y direction, the print dots formed by the same discharge heads 122a and 122b in the Y direction in the mask pattern are in the shape of continuous vertical stripes, so that the print dots will not be as Figure 8 Therefore, the mask pattern of this embodiment can suppress the phenomenon of image quality degradation such as density unevenness and streaks in the nozzle overlap region 300 between the adjacent ejection heads 122a and 122b, as compared with the mask pattern of the prior art.

[0097] Thus, in this embodiment, the mask pattern of the nozzle overlap region 300 of the discharge head ends of the adjacent discharge heads 122a and 122b is configured so that the print dots formed by the discharge head 122a and the print dots formed by the discharge head 122b are alternately arranged in the X direction, and the print dots formed by the same discharge head are used only in the Y direction. In this way, it is possible to suppress the occurrence of density unevenness or streaks caused by the difference in the driving frequency characteristics of the discharge droplet amount between the two discharge heads 122a and 122b, or the positional deviation or droplet velocity difference between the two discharge heads 122a and 122b in the nozzle overlap region 300 of the discharge head ends of the adjacent discharge heads 122a and 122b, thereby equalizing the image quality in the nozzle overlap region 300 of the discharge head ends of the adjacent discharge heads 122a and 122b.

[0098] Furthermore, even if a positional deviation (Y deviation) ΔY occurs between the two discharge heads 122a and 122b in the Y direction, this embodiment can suppress image quality degradation such as density unevenness or streaks in the nozzle overlap region 300 of the adjacent discharge heads 122a and 122b.

[0099] The computer program executed in the image forming apparatus 100 of the present embodiment is provided as an installable or executable file recorded in a computer-readable recording medium such as a CD-ROM, a floppy disk (FD), a CD-R, or a DVD (Digital Versati le Disc).

[0100] In addition, the computer program executed by the 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 downloading the computer program from the network. Furthermore, the computer program executed by the image forming apparatus 100 of the present embodiment may be provided or distributed via a network such as the Internet.

[0101] Furthermore, the computer program executed in the image forming apparatus 100 of the present embodiment may be provided by being installed in advance in a ROM or the like.

[0102] The computer program executed in the image forming device 100 of the present embodiment is constructed in a modular manner to include the above-mentioned parts (color version segmentation data generation part 211, discharge control part 212), and as actual hardware, the CPU (processor) reads out the computer program product from the above-mentioned storage medium and executes it, so that the above-mentioned parts are called to the main storage device, and the color version segmentation data generation part 211 and the discharge control part 212 are generated on the main storage device.

[0103] <Second Embodiment>

[0104] Next, a second embodiment will be described.

[0105] The second embodiment is different from the first embodiment in that the usage rate of the nozzle at the end of the discharge head is reduced. In the following description of the second embodiment, the description of the same parts as the first embodiment is omitted, and only the differences from the first embodiment are described.

[0106] Fig.10 is a schematic diagram of an example of a mask pattern of the second embodiment, Fig.11 FIG. 3 is a schematic diagram of an example of nozzle usage rate in the nozzle overlap area 300 .

[0107] like Fig.10 As shown, the mask pattern formed by the discharge control unit 212 of the control unit 101 of this embodiment in the mask processing of the nozzle overlapping area 300 of the discharge heads 122a and 122b is that the printing dots formed by the discharge head 122a in the X direction and the printing dots formed by the discharge head 122b are mixed, and the printing dots formed by the same discharge heads 122a and 122b in the Y direction are continuously in the shape of vertical stripes.

[0108] In the first embodiment, Fig. 9 In the mask portion A3, the print dots formed by the ejection head 122a and the print dots formed by the ejection head 122b in the X direction are alternately arranged at intervals of one dot. Fig.10 and Fig.11As shown, the discharge control unit 212 of the control unit 101 of the present embodiment reduces the nozzle usage rate of the discharge heads 122a and 122b as approaching the ends of the discharge heads 122a and 122b.

[0109] Specifically, if Fig.10 As shown, the discharge control unit 212 of the control unit 101 sets the 3rd, 6th, 8th, 9th, 11th, and 12th nozzles 1a from the end of the discharge head to "use" and the 1st, 2nd, 4th, 5th, 7th, and 10th nozzles 1b from the end of the discharge head to "unuse". The discharge control unit 212 of the control unit 101 also sets the 3rd, 6th, 8th, 9th, 11th, and 12th nozzles 2a from the end of the discharge head to "use" and the 1st, 2nd, 4th, 5th, 7th, and 10th nozzles 2b from the end of the discharge head to "unuse" in the nozzle column of the nozzle overlap region 300 of the discharge head 122b.

[0110] Fig.10 and Fig.11 The example shown is similar to Fig. 9 Similarly, by making the ejection interval of the mask part A3 of the single ejection head the same as the ejection interval of the ordinary parts A1 and A2, the drive frequency of the print dots between the ordinary parts A1 and A2 and the mask part A3 is kept consistent. Figure 6 The driving frequency characteristics shown will not affect Figure 7 The difference in drive frequency characteristics shown causes the difference in droplet volume.

[0111] exist Fig.10 and Fig.11 In the example shown, even if the positions of the two heads 122a and 122b deviate in the Y direction (Y deviation) by ΔY, the mask pattern is formed by continuously forming vertical stripes in the Y direction using the print dots formed by the same heads 122a and 122b. Figure 8 That way the printed dots overlap each other.

[0112] Furthermore, generally speaking, the closer the nozzle is to the end of the liquid discharge head, the more it is affected by the airflow and bends, or has characteristics such as crosstalk. Fig.10 and Fig.11 In the example shown, by reducing the usage rate of the end nozzles of the two discharge heads 122 a and 122 b , it is possible to make image quality degradation due to the influence of airflow and the like less noticeable.

[0113] Thus, in addition to the effects described in the first embodiment, this embodiment can reduce the usage rate of the end nozzles of the liquid discharge heads that are easily affected by airflow and have characteristic differences such as bending or crosstalk by reducing the frequency of use of the end nozzles of the two discharge heads 122a and 122b in the nozzle overlap area 300, thereby making the image quality degradation caused by airflow influence, etc. less obvious.

[0114] <Third Embodiment>

[0115] The third embodiment differs from the first embodiment in that the nozzle at the most upstream of the airflow accompanying the movement of the carriage in the Y direction is not used. In the following description of the third embodiment, the description of the same parts as the first embodiment is omitted, and only the differences from the first embodiment are described.

[0116] Fig.12 FIG. 1 is a schematic diagram of an example of a mask pattern of the third embodiment. Fig.12 As shown, the discharge heads 122a and 122b of this embodiment have two nozzle rows consisting of a plurality of nozzles. The two nozzle rows of the discharge heads 122a and 122b of this embodiment are formed by dividing the nozzle row of the first embodiment into two rows every other nozzle.

[0117] like Fig.12 As shown, the mask pattern formed by the discharge control unit 212 of the control unit 101 of this embodiment in the mask processing of the nozzle overlap area 300 is that the printing dots formed by the discharge head 122a in the X direction and the printing dots formed by the discharge head 122b are mixed together, and the printing dots formed by the same discharge heads 122a and 122b in the Y direction are continuously in the shape of vertical stripes.

[0118] exist Fig.12 In the example shown, the carriage 121 is Fig.12 Move from top to bottom. Fig.12 As shown, the discharge head 122b is arranged upstream of the discharge head 122a in the moving direction of the carriage 121. Fig.12 As shown, the discharge control unit 212 of the control unit 101 of this embodiment sets the nozzle 2b of the nozzle row at the upstream end of the moving direction of the carriage 121 in the nozzle overlap area 300 of the discharge head 122b which is easily affected by the airflow generated by the movement of the carriage 121 in the Y direction to "unused".

[0119] Fig.12 The example shown is similar to Fig. 9 Similarly, the discharge interval of the mask part A3 of the single discharge head is the same as the discharge interval of the ordinary parts A1 and A2, so that the driving frequency of the printing dots between the ordinary parts A1 and A2 and the mask part A3 is consistent, so there is no Figure 6The driving frequency characteristics shown in the figure will not be affected. Figure 7 Furthermore, even if the positions of the two ejection heads 122a and 122b are offset in the Y direction (Y offset) by ΔY, the mask pattern in the Y direction is a vertical stripe pattern in which the print dots are continuous and formed by the same ejection heads 122a and 122b. Figure 8 That way, the printed dots overlap each other.

[0120] Furthermore, in Fig.12 In the example shown, since the mask pattern of the nozzle most upstream in the moving direction of the carriage 121 is not used, the image quality degradation caused by the bending of the droplets due to the airflow is not noticeable.

[0121] In addition, the airflow generated by the movement of the carriage 121 in the Y direction is Fig.12 When the top and bottom are reversed, the discharge control unit 212 of the control unit 101 of this embodiment sets the nozzle 1b of the nozzle row most upstream in the moving direction of the carriage 121 in the nozzle overlap area 300 of the discharge head 122a which is easily affected by the airflow as "non-use". Therefore, this embodiment can also be applied to multi-pass printing.

[0122] Thus, in addition to the effects described in the first embodiment, this embodiment does not use the nozzle located most upstream in the moving direction of the slide 121 (a direction intersecting the column direction of the nozzle column) in the nozzle overlapping area 300 of the discharge heads 122a and 122b, thereby making it possible to make the image quality degradation caused by the bending of droplets due to the airflow less obvious.

[0123] In this embodiment, an example of the discharge heads 122a and 122b having two nozzle rows is described, but the present invention is not limited thereto and may also be as follows: Fig.13 The liquid discharge head shown has eight nozzle rows or a liquid discharge head having other nozzle rows.

[0124] In this embodiment, a multi-pass method in which the carriage 1211 drips ink back and forth is described, but the present invention is not limited thereto and is also applicable to a linear discharge head method in which the liquid discharge head is fixed and the medium is moved. In the case of the linear discharge head method, a mask pattern that does not use the most upstream nozzle that is easily affected by the airflow in the medium conveying direction (the direction intersecting the row direction of the nozzle row) can be used.

[0125] <Fourth Embodiment>

[0126] The fourth embodiment differs from the first embodiment in that the nozzle usage rate in the end region of the discharge head where droplet bending occurs is reduced. In the following description of the fourth embodiment, the description of the same parts as the first embodiment is omitted, and only the differences from the first embodiment are described.

[0127] Fig.14 is a schematic diagram of an example of a mask pattern of the fourth embodiment, Fig.15 It is a schematic diagram showing the state of discharged liquid droplets in the end area of ​​the liquid discharge head.

[0128] like Fig.14 As shown, the mask pattern in the mask processing of the nozzle overlapping area 300 of the discharge heads 122a and 122b by the discharge control unit 212 of the control unit 101 of this embodiment is that the print dots formed by the discharge head 122a and the print dots formed by the discharge head 122b in the X direction are mixed together, and the print dots formed by the same discharge heads 122a and 122b in the Y direction are continuously presented in the shape of vertical stripes.

[0129] like Fig.15 As shown, the discharge heads 122 a and 122 b can drop discharge liquid droplets a discharged from the middle portions of the discharge heads 122 a and 122 b toward the medium 40 in the vertical direction (Z direction) to target positions on the medium 40 .

[0130] On the other hand Fig.15 As shown, the discharged liquid droplets b ejected from the discharge head ends of the discharge heads 122 a and 122 b in the vertical direction toward the medium 40 are swept away by the end airflow, so that the droplet positions deviate from the target positions on the medium 40 . Fig.15 The curve from the target position on the medium 40 to the drop position is shown to bend toward the outside of the discharge head, but it may bend toward the center of the discharge head depending on the driving frequency, droplet size, printing gap, etc. In this way, if a large number of discharge drops b discharged from the ends of the nozzles 122a and 122b are used in the mask pattern of the nozzle overlap area 300, there will be a problem of significant image quality degradation.

[0131] In this regard, Fig.14 As shown, the discharge control unit 212 of the control unit 101 of this embodiment makes the distance X1 from the outermost end use nozzle to the second end use nozzle of the nozzle overlap area 300 of the discharge head 122a greater than the distance X2 from the second end use nozzle to the use nozzle further inside than the second end use nozzle. In this way, the nozzle use rate of the discharge head end area of ​​the discharge head 122a where droplet bending occurs can be reduced, making the image quality degradation less noticeable.

[0132] Specifically, if Fig.14As shown, the discharge control unit 212 of the control unit 101 sets the 1st, 6th, 8th, 9th, 10th, and 11th nozzles 1a from the end of the discharge head to "use", and sets the 2nd, 3rd, 4th, 5th, 7th, and 12th nozzles 1b from the end of the discharge head to "unuse". The discharge control unit 212 of the control unit 101 also sets the 1st, 6th, 8th, 9th, 10th, and 11th nozzles 2a from the end of the discharge head to "use", and sets the 2nd, 3rd, 4th, 5th, 7th, and 12th nozzles 2b from the end of the discharge head to "unuse".

[0133] Fig.14 Examples of Fig. 9 Similarly, by making the ejection interval of the mask part A3 of the single ejection head consistent with the ejection interval of the ordinary parts A1 and A2, the driving frequency of the print dots of the ordinary parts A1 and A2 and the mask part A3 is the same. Figure 6 The driving frequency characteristics shown will not produce Figure 7 Even if the position deviation (Y deviation) ΔY occurs between the two ejection heads 122a and 122b in the Y direction, the mask pattern of the vertical stripe shape in which the print dots are formed by the same ejection heads 122a and 122b in the Y direction is used, so that the above-mentioned difference in the amount of droplets does not occur. Figure 8 That way the printed dots overlap each other.

[0134] As described above, in addition to the effects described in the first embodiment, in this embodiment, the closer to the end of the liquid discharge head, the larger the distance between the nozzles used, thereby reducing the nozzle usage rate in the end area of ​​the liquid discharge head where droplets are easily bent due to airflow, thereby making the image quality degradation less obvious.

[0135] In this embodiment, the discharge heads 122a and 122b having two nozzle rows are described, but the present invention is not limited thereto and may also be as follows: Fig.16 The liquid discharge head having 8 nozzle rows as shown or a liquid discharge head having other rows. Fig.16 In the example shown, in the nozzle overlap region 300 of the discharge head 122a, the distance X1 from the outermost end nozzle to the second end nozzle in the X direction is greater than the distance X2 from the second end nozzle to the inner nozzle.

[0136] The "liquid discharge device" in the present invention is a liquid discharge device having a liquid discharge head 122 or a liquid discharge unit, and driving the liquid discharge head 122. The liquid discharge device includes a liquid discharge device for discharging liquid into gas or liquid in addition to a liquid discharge device for discharging liquid into an object to which liquid can adhere.

[0137] The "liquid discharge device" includes a mechanism for conveying, transporting, and discharging objects to which liquid can be attached, and may also include a pre-processing device, a post-processing device, etc.

[0138] Examples of "liquid discharge devices" include devices that discharge ink to form an image on paper, i.e., image forming devices, and three-dimensional modeling devices (three-dimensional modeling devices) that discharge modeling liquid into a powder layer formed as a layered powder in order to form a three-dimensional modeled object (three-dimensional modeled object).

[0139] In addition, the "liquid discharge device" is not limited to a device that makes a meaningful image such as text or graphics visible by the discharged liquid. For example, a device that forms a pattern that itself has no meaning, etc., also includes a device that forms a three-dimensional image.

[0140] The above-mentioned "objects to which liquid can be attached" refers to objects to which liquid can be attached at least temporarily, that is, objects to which liquid can be attached and fixed, objects to which liquid can be attached and penetrated, etc. For example, there are recording media such as paper, recording paper, recording paper, film, cloth, electronic components such as electronic circuit substrates, piezoelectric components, powder layers, organ models, inspection units, etc., and as long as there are no special restrictions, all media to which liquid can be attached are included.

[0141] The material of the above-mentioned "object to which liquid can adhere" can be any material as long as it is paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, etc., which can adhere to liquid even temporarily.

[0142] In addition, the "liquid" is not particularly limited as long as it has a viscosity or surface tension that can be ejected from the liquid discharge head 122, but preferably a liquid with a viscosity of 30 MPa·s or less at normal temperature and pressure or by heating or cooling. More specifically, it is a solution, suspension, emulsion, etc. containing solvents such as water or organic solvents, colorants such as dyes or pigments, functional materials such as polymers, resins, surfactants, biocompatible materials such as DNA, amino acids or proteins, calcium, edible materials such as natural pigments, etc., and can be used in applications such as inkjet ink, surface treatment liquid, liquid for forming structural elements or circuit anti-etching patterns of electronic components or light-emitting elements, and material liquid for three-dimensional modeling.

[0143] The "liquid discharge device" has a device that allows the liquid discharge head 122 and an object to which liquid can be attached to move relative to each other, but the present invention is not limited to this and can also include, for example, a serial device that moves the liquid discharge head 122, a linear device that moves the liquid discharge head 122 without moving, etc.

[0144] In addition, the "liquid discharge device" also includes a treatment liquid coating device, a jet granulation device, etc. The treatment liquid coating device coats the surface of the paper with a treatment liquid for the purpose of changing the surface properties of the paper, and discharges the treatment liquid onto the paper. The jet granulation device sprays a component liquid for dispersing the raw material into a solution through a nozzle to form fine particles of the raw material.

Claims

1. A liquid discharge head, comprising a plurality of discharge heads, wherein a nozzle array consisting of a plurality of nozzles is arranged in the discharge head, and liquid droplets are selectively discharged from the nozzles, and adjacent discharge heads in the liquid discharge head are provided with nozzle overlapping areas at the ends of the nozzle array in the row direction, characterized in that: The invention is provided with an ejection control unit for forming data of a direction parallel to the column direction of the nozzle array in the mask pattern of the nozzle overlapping area by using both pixel data of one of the plurality of ejection heads and pixel data of another of the plurality of ejection heads, and forming data of a direction intersecting the column direction of the nozzle array by using pixel data of the one ejection head and pixel data of any one of the pixel data of the other ejection head.

2. The liquid discharge head according to claim 1, wherein The discharge control section reduces usage rates of nozzles at respective ends of the one discharge head and the other discharge head in the nozzle overlap region.

3. The liquid discharge head according to claim 1, wherein The discharge control unit sets the nozzles of the nozzle row most upstream in a direction intersecting the row direction of the nozzle row of the nozzle overlapping region to be unused.

4. The liquid discharge head according to claim 1, wherein The discharge control unit makes the distance from the outermost end use nozzle to the second end use nozzle of the nozzle overlap region greater than the distance from the second end use nozzle to the use nozzle closer to the inner side of the second end use nozzle.

5. The liquid discharge head according to claim 1, wherein The number of nozzles present in the nozzle overlap region is twice the number of nozzles present in the general region outside the nozzle overlap region.

6. A liquid discharge unit, characterized in that: A liquid discharge head according to any one of claims 1 to 5, and at least one of a discharge head tank, a carriage, a supply mechanism, a maintenance recovery mechanism, and a main scanning movement mechanism.

7. A liquid discharge device, characterized in that: have: The liquid discharge head according to any one of claims 1 to 5; and The control unit is used to drive the liquid discharge head to discharge liquid.

8. A liquid discharge method for a liquid discharge head, the liquid discharge head having a plurality of discharge heads, a nozzle array consisting of a plurality of nozzles arranged in the discharge head, liquid droplets are selectively discharged from the nozzles, adjacent discharge heads in the liquid discharge head are provided with nozzle overlapping areas at the ends of the nozzle array in the row direction, characterized in that: The method comprises a discharge control process, wherein data of a direction parallel to the column direction of the nozzle array in the mask pattern of the nozzle overlapping area is composed of both pixel data of one of the multiple discharge heads and pixel data of another of the multiple discharge heads, and data of a direction intersecting the column direction of the nozzle array is composed of pixel data of the one discharge head and pixel data of any one of the other discharge heads.

9. A computer program product for computer-controlled liquid discharge heads, the liquid discharge heads comprising a plurality of discharge heads, a nozzle column consisting of a plurality of nozzles arranged in the discharge heads, droplets selectively discharged from the nozzles, adjacent discharge heads in the liquid discharge heads being provided with nozzle overlapping areas at the ends in the column direction of the nozzle column, the computer program product being characterized in that the computer functions as a discharge control unit, data in a direction parallel to the column direction of the nozzle column in a mask pattern of the nozzle overlapping area is constituted by both pixel data of one of the plurality of discharge heads and pixel data of another of the plurality of discharge heads, and data in a direction intersecting the column direction of the nozzle column is constituted by pixel data of either the one discharge head or the other discharge head.

Images