JP2010208121A - Liquid jetting head and liquid jetting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To relieve the formation of stripes at a band boundary when jetting liquid in a band system. <P>SOLUTION: A nozzle array 101 provided for jetting liquid is composed of large nozzles 102 arranged at the center of the nozzle array 101 and comparatively large in the quantity of liquid jetted, and small nozzles 103 arranged on at least one end side of the nozzle array 101 and comparatively small in the quantity of liquid jetted. The large nozzles 102 have respective liquid jet ports formed in mutually equal size. The small nozzles 103 also have respective liquid jet ports formed in mutually equal size. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus.

  2. Description of the Related Art As a liquid ejecting apparatus that ejects liquid onto an object, an ink jet printer that uses a recording medium such as recording paper as an object and ejects (discharges) ink onto the recording medium to record characters and images is well known. Yes. Also, in the process of manufacturing a display such as a liquid crystal display, a plasma display, an organic EL (Electro Luminescence) display, or a field emission display, various liquid forms for forming color materials, electrodes, etc. 2. Description of the Related Art Liquid ejecting apparatuses that eject material and land on a pixel formation region, an electrode formation region, or the like are used.

  When the liquid ejecting apparatus is used as a printer, ink is ejected while a print head is scanned with respect to a recording medium to perform recording / printing. As the print head, a plurality of nozzles for ejecting ink are arranged for each ink to form a nozzle row, and a plurality of lines are recorded and printed in one scan. Hereinafter, scanning in the direction intersecting with the nozzle row direction, that is, scanning in which the print head simultaneously records and prints a plurality of lines is referred to as main scanning, and scanning in the direction from one main scanning to the next main scanning is referred to as sub scanning. In the case of a general ink jet printer that scans the print head perpendicular to the conveyance direction while conveying the recording medium (paper feeding), the conveyance direction of the recording medium is the sub-scanning direction, and the direction orthogonal to the conveyance direction is It becomes the main scanning direction.

  In addition, there are an interlace method and a band method as a method for recording and printing with a print head having a nozzle array. The interlace method is a method in which the main scanning is repeated by finely shifting the nozzle rows in the sub-scanning direction, and an image having a higher resolution than the nozzle interval (pitch) in the nozzle rows can be printed. On the other hand, the band method is a method of printing an area (band) corresponding to the width of the nozzle row for each main scan, and high-speed printing is possible. For example, Patent Documents 1 and 2 describe band-type printing. In the technique described in Patent Document 1, intermittent printing is performed on the same band in the main scanning direction, and one band is filled by repeating this printing. Hereinafter, the main scanning to the same band including such repeated main scanning is referred to as “one-pass main scanning”.

JP 2003-246054 A JP 2007-144788 A

  In band-type printing, for example, when printing a dark image on a recording medium that tends to bleed, such as plain paper, the bleed becomes noticeable especially at the edge of the dry band where the ink is not landed next. Black stripes may occur due to the overlap of the band boundaries. This black streak can be prevented by adjusting the relative movement amount of the print head and the recording medium in the sub-scanning. That is, by increasing the band interval for each main scan, it is possible to prevent the overlapping of blurs and the occurrence of black stripes. However, when a light-colored image is printed in such an adjusted state, the amount of ink is small, so that bleeding is small and white streaks occur between bands.

  If the amount of sub-scanning movement can be adjusted for each band corresponding to the image to be printed, such black stripes and white stripes can be prevented. However, such control is complicated. On the other hand, Patent Document 2 describes that the number of nozzles at the end portion to be used is changed according to the duty of an image in order to prevent the occurrence of streaks in band printing. However, the technique described in Patent Document 2 suppresses streaks by providing a grade at the band boundary.

  SUMMARY An advantage of some aspects of the invention is to provide a liquid ejecting head and a liquid ejecting apparatus that can alleviate the generation of streaks at a band boundary when performing liquid ejecting in a band system.

  According to a first aspect of the present invention, in a liquid ejecting head provided with a nozzle row for ejecting liquid, the nozzle row is arranged in the center of the nozzle row and has a large nozzle that ejects a relatively large amount of liquid; The small nozzles are arranged at least on one end side and have a relatively small amount of liquid to be ejected. The large nozzles are formed with the same size of the respective liquid ejection ports, and the small nozzles have the same liquid ejection ports. A liquid ejecting head having a size is provided.

  A plurality of small nozzles can be arranged at both ends of the nozzle row. In this case, the area that covers the ejection target with the liquid ejected from the small nozzle is set to half of the area that covers the ejection target with the liquid ejected from the large nozzle.

  The centers of the large nozzle and the small nozzle can be arranged at equal intervals between the large nozzles, between the small nozzles, and between the large nozzle and the small nozzle.

  According to the second aspect of the present invention, the main scanning is performed by relatively moving the liquid ejecting head shown in the first aspect and the liquid ejecting head and the ejecting target in a direction intersecting the column direction of the nozzle rows. Main scanning means for performing sub-scanning by relatively moving the ejection target and the liquid ejecting head so that the position of the liquid ejected from the liquid ejecting head on the ejection target is shifted every main scanning. The sub-scanning means generates a vacant area between areas where the liquid is ejected by the large nozzle on the ejection target in one main scanning and the next main scanning, and the liquid by the small nozzle is formed in this vacant area. And the liquid ejection position on the ejection target by the small nozzle is shifted in the column direction of the nozzle row from the cycle of the liquid ejection position by the large nozzle on the ejection target in the previous main scanning or the next main scanning. To do sub-scanning The liquid ejecting apparatus is provided, wherein.

  According to a third aspect of the present invention, in the first aspect, a liquid ejecting head having a configuration in which a plurality of small nozzles are arranged at both ends of the nozzle row, and the liquid ejecting head and the ejection target are arranged in the row direction of the nozzle row. The main scanning means for performing main scanning by relatively moving in the intersecting direction, and the ejection target and the liquid ejecting head so that the position of the liquid ejected from the liquid ejecting head on the ejection target is shifted every main scanning. Sub-scanning means for performing sub-scanning by relatively moving the sub-scanning means between the areas where the liquid is ejected by the large nozzle on the ejection target in one main scanning and the next main scanning. An empty area is generated, and liquid is ejected by a small nozzle in this empty area, and the liquid ejection position on the ejection target by the small nozzle on one end side of the nozzle row in one main scan in the same empty area And main scan before and after A liquid jet position on the injection subject with small nozzles at the other end of the nozzle array definitive is, the liquid-jet apparatus characterized by performing a sub-scan is provided to be shifted in the column direction of the nozzle array mutually.

  According to the present invention, when liquid is ejected by the band method, the generation of streaks at the band boundary can be reduced by performing the liquid ejection by the small nozzle on the band boundary portion by the large nozzle.

It is a figure explaining the structure of the liquid ejecting apparatus which concerns on embodiment of this invention, and shows the schematic structure of a mechanism system, and the block structure of the control system which controls this mechanism system. It is a figure explaining the blur in the boundary part of a band. It is a figure explaining the relationship between a conveyance adjustment value and generation | occurrence | production of a white stripe and a black stripe. FIG. 2 is a diagram illustrating a nozzle arrangement of a liquid ejecting head used in the liquid ejecting apparatus illustrated in FIG. 1. FIG. 5 is a diagram for explaining the operation of the liquid jet head having the nozzle arrangement shown in FIG. FIG. 5 is a diagram for explaining the operation of the liquid ejecting head having the nozzle arrangement shown in FIG. 4 when the ejection target has a transport error in the liquid ejecting apparatus shown in FIG. 1, and FIG. Indicates a case where the transport error is negative.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Overall configuration]
FIG. 1 is a diagram illustrating a configuration of a liquid ejecting apparatus according to an embodiment of the present invention, and shows a schematic structure of a mechanism system and a block configuration of a control system that controls the mechanism system. Here, an ink jet printer will be described as an example of the liquid ejecting apparatus.

  The liquid ejecting apparatus shown in FIG. 1 is an apparatus that records and prints an image by ejecting liquid ink onto a recording medium 10 that is an ejecting target, and includes a print head 11 serving as a liquid ejecting head as a mechanism system, and main scanning. It has a carriage 12 that constitutes part of the means, and a transport device 13 that constitutes part of the sub-scanning means. The print head 11 is provided with a nozzle row for ejecting ink, as will be described later. Although not shown, the carriage 12 includes a mechanism for supplying ink to the print head 11 and a mechanism for moving the print head 11 relative to the recording medium 10 (this is referred to as “main scanning”). Provided. Although only the roller is shown in FIG. 1, the transport device 13 is for moving the recording medium 10 relative to the print head 11 (this is called “sub-scanning”).

  The liquid ejecting apparatus illustrated in FIG. 1 also includes an operation control unit 20 and a data processing unit 30 as a control system. The operation control unit 20 includes a head drive unit 21, a carriage movement control unit 22 that forms part of the main scanning unit, and a conveyance control unit 23 that forms part of the sub-scanning unit. The head drive unit 21 controls the operation of the print head 11. The carriage movement control unit 22 controls the movement of the carriage 12 and relatively moves the print head 11 and the recording medium 10 in a direction intersecting the row direction of the nozzle rows of the print head 11 (in this embodiment, the print head 11 is moved) to perform main scanning. The conveyance control unit 23 controls the relative position movement between the print head 11 and the recording medium 101 so that the position of the ink ejected from the print head 11 on the recording medium 10 is shifted for each main scanning direction. Sub-scanning is performed by relatively moving the recording medium 10 and the print head 11 (in this embodiment, the recording medium 10 is moved). Here, for convenience of explanation, the head drive unit 21, the carriage movement control unit 22, and the conveyance control unit 23 are collectively shown in the operation control unit 20. However, practically, the head drive unit 21, the carriage movement control unit 22, and the conveyance control unit 23 are arranged integrally with each control target. The That is, the head drive unit 21 is provided integrally with the print head 11, the carriage movement control unit 22 is disposed in the carriage 12, and the transport control unit 23 is disposed in the transport device 13.

  The data processing unit 30 includes an external interface 31, a central processing unit (CPU) 32, a ROM 33, a RAM 34, and an internal interface 35. The external interface 31 is connected to an external device such as a host computer or a network, receives print data and control data from the external device, and notifies various data to the external device. The central processing unit 32 performs processing of print data and various types of data for controlling each unit in the liquid ejecting apparatus. The ROM 33 stores a program for the central processing unit 32 to perform processing and various fixed data necessary for the processing. The RAM 34 temporarily stores data transmitted / received via the external interface 31 and the internal interface 35, and temporarily stores data processed by the central processing unit 32.

[Operation]
The operation of the liquid ejecting apparatus shown in FIG. 1 will be described. When print data is input from an external device via the external interface 31, the print data is first stored in the RAM 34, and the central processing unit 32 converts the print data into dot pattern data corresponding to the ink dot pattern. , Temporarily stored in the RAM 34. When the dot pattern data printed by one main scan of the print head 11 is obtained, the central processing unit 32 reads the dot pattern data for the one main scan from the RAM 34, and via the internal interface 31, Output to the operation control unit 20.

  The head drive unit 21 in the operation control unit 20 supplies drive signals to the individual nozzles of the print head 11 in accordance with the input dot pattern data. As the print head 11, one that can adjust the amount of ink ejected from the nozzle by a drive signal can be used. For example, if the piezoelectric element applies pressure to the ink and ejects ink droplets from the nozzle, the amount of ink ejected from the same nozzle can be adjusted by changing the drive pulse waveform of the piezoelectric element. As a result, any one of three types of dots, for example, small dots, medium dots, and large dots can be formed on the recording medium 10.

  A carriage movement control unit 22 in the operation control unit 20 controls the movement of the carriage 12 to which the print head 11 is attached, and moves the print head 11 with respect to the recording medium 10 in the main scanning direction. The conveyance control unit 23 in the operation control unit 20 controls the conveyance device 13 to convey (paper feed) the recording medium 10, thereby moving the relative position of the print head 11 with respect to the recording medium 10 in the sub-scanning direction.

  When printing by the interlace method, the conveyance control unit 23 controls the conveyance amount of the recording medium 10 by the conveyance device 13 more finely than the nozzle interval of the print head 11, and separates between lines printed by one main scan. Print in main scan. On the other hand, in the band-type printing, the storage medium 10 is transported by an amount corresponding to the nozzle area width of the print head 11 after one pass of main scanning.

[Generation of streaks at band boundaries]
FIG. 2 is a diagram for explaining bleeding at the boundary portion of the band. Here, the number of nozzles in the band is 360, and the nozzle number is also written at the left end. As described above, when printing is performed with high duty when the recording medium 10 is easy to bleed like plain paper, ink oozes out greatly at a dry boundary portion where the ink does not land next to it. Become. In FIG. 2, the oozing at the upper and lower writing portions is large.

  FIG. 3 is a diagram for explaining the relationship between the conveyance adjustment value and the occurrence of white stripes and black stripes. The carry amount of the carry device 13 in band printing can be adjusted by the carry control unit 23 according to an instruction from the data processing unit 30. Here, it is assumed that the conveyance adjustment value is zero when the interval between adjacent dots printed in the two-pass main scan is equal to the dot interval printed in each main scan. Further, it is assumed that the conveyance adjustment value is positive when the interval between adjacent dots printed in the two-pass main scan is wider than the dot interval printed in each main scan. When the conveyance adjustment value is zero, in low-duty printing with a small amount of ink, the dot intervals are uniform and good print quality is obtained. However, in high-duty printing with a large amount of ink, blurring may overlap at the band boundary, resulting in black streaks. Such black stripes can be prevented by making the conveyance adjustment value positive. However, if the conveyance adjustment value is set to a plus value, white streaks occur during low duty printing.

[Reduction of streaks]
In order to alleviate the occurrence of such black and white lines, the print head 11 of the liquid ejecting apparatus shown in FIG. 1 has dedicated nozzles for printing in a band system on both sides of a conventional normal nozzle. Is provided. This will be described below.

  FIG. 4 is a diagram illustrating the nozzle arrangement of the print head 11 used in the liquid ejecting apparatus shown in FIG. The print head 11 is provided with a nozzle row 101 for ejecting ink. The nozzle row 101 is arranged in the center of the nozzle row 101 and has a large nozzle area composed of large nozzles 102a with a relatively large amount of liquid (ink) to be ejected. 102, a small nozzle region 103 composed of a plurality of small nozzles 103a that is disposed on one end side of the nozzle row 101 and ejects a relatively small amount of liquid, and a liquid amount that is disposed on the other end side of the nozzle row 101 is relatively small. The small nozzle region 104 is composed of a small number of small nozzles 104a. In the large nozzle 102a, the liquid ejection ports are formed in the same size, and in the small nozzles 103a, 104a, the liquid ejection ports are formed in the same size. The area covering the recording medium 10 with the ink ejected from the small nozzles 103a and 104a is set to half of the area covering the recording medium 10 with the ink ejected from the large nozzle 102a. With such a setting, the density per area of the dots by the large nozzle is almost equal to the density per area of the dots by the small nozzle. Here, “half” does not mean strictly 0.5, but allows a slight error. For example, even if 1/3 or 2/3, a certain degree of effect can be obtained.

  Here, an example for single color printing is shown as the print head 11, but for color printing, a nozzle row 101 is provided for each ink type (color). However, if there are ink types that do not participate in band-type printing, it is not necessary to provide small nozzles for the nozzle row of that ink type.

  FIG. 5 is a diagram for explaining the operation of the print head 11 having the nozzle arrangement shown in FIG. 4 and shows the positional relationship of the nozzles in two-pass main scanning. The left nozzle row in FIG. 5 is the position of the nozzle on the recording medium 10 in the first pass, and the right nozzle row is the position of the nozzle on the recording medium 10 in the second pass.

  When printing is performed by the print head 11, the conveyance control unit 23 prints an area in which printing is performed by the large nozzle 102 a on the recording medium 10 in one main scanning and the next main scanning (ink is ejected by the large nozzle 102 a. A large inter-nozzle region W is generated as an empty region between the large nozzles), and printing (liquid ejection) is performed in the large inter-nozzle region W by the small nozzles 103a and 104a without using the large nozzle 102a. Sub scan is performed. Further, the transport control unit 23 ejects ink from the large nozzles 102a on the recording medium 10 in the previous main scanning or the next main scanning when the printing position (liquid ejection position) on the recording medium 10 by the small nozzles 103a and 104a. Sub-scanning is performed so as to deviate from the position cycle in the direction of the nozzle row. Alternatively, when a plurality of small nozzles 103 a and 104 a are arranged on both sides of the nozzle row 101 as shown in FIG. 4, the transport control unit 23 performs one main scan in the same large nozzle area W. The printing position on the recording medium 10 by the small nozzle 103a or 104a on one end side of the nozzle row 101 and the recording medium 10 by the small nozzle 104a or the small nozzle 103a on the other end side of the nozzle row in the main scanning before and after that. Sub-scanning is performed so that the liquid ejection position is shifted in the row direction of the nozzle row 101 from each other. Each of the small nozzles 103a and 104a is set to a value that can ensure a margin for the conveyance adjustment amount. In the following, in order to avoid redundancy, the description will be made using the nozzle numbers instead of the reference numbers 102a, 103a and 104a of the large nozzle and the small nozzle.

  In the example shown in FIG. 5, the positions of the large nozzles # 362 to 365 and the small nozzles # 366 to # 370 in the first pass and the small positions in the next pass are determined as the positional relationship of the nozzles near the band boundary in the main scan of two passes. It represents the positions of nozzles # 1 to # 5 and large nozzles # 6 to # 9. The conveyance adjustment value is set so that the dot bleeding boundary 111 by the large nozzle # 365 in the first pass and the dot bleeding boundary 112 by the large nozzle # 6 in the next pass do not overlap during high duty printing. Is done. Then, the resolution is increased by the small nozzles # 366 and # 367 in the first pass, and the small nozzles # 4 and # 5 in the next pass, and the density of the normal dots by the large nozzles is secured in the vicinity of the small dots. In general, small dots have little blur, and there is little possibility of blur due to small nozzles # 366 and # 5 overlapping. On the other hand, at the time of low-duty printing, the dot blur boundary 121 by the large nozzle # 365 and the dot blur boundary 122 by the large nozzle # 6 are relatively far apart. Also in this case, the vicinity of the normal dot density is secured by the small nozzles # 366 and # 367 in the first pass and the small nozzles # 4 and # 5 in the next pass. In this way, bleeding at the band boundary is alleviated, and white and black lines can be alleviated with one conveyance adjustment value from high duty to low duty.

  6 is a diagram for explaining the operation of the print head 11 having the nozzle arrangement shown in FIG. 4 when the recording medium 10 to be ejected in the liquid ejecting apparatus shown in FIG. 1 has a transport error. 6A shows a case where the transport error is positive, and FIG. 6B shows a case where the transport error is negative. A positive conveyance error means a state where the recording medium 10 is fed too much. Further, a negative conveyance error means a state where the recording medium 10 is not fed sufficiently. When the transport error is positive, the large nozzles # 365 and # 6 have a large dot interval between passes. Therefore, in that case, more small nozzles # 366 to # 368 and # 3 to # 5 shown in FIG. Further, when the transport error is negative, the interval between the dots of the large nozzles # 365 and # 6 is narrowed. Therefore, the smaller nozzles # 368 and # 5 smaller than those shown in FIG. . Since the transport error depends on each liquid ejecting apparatus and does not change so much after manufacture, the number of small nozzles to be used is set in accordance with each liquid ejecting apparatus.

  In the above description, the small nozzle regions 103 and 104 are arranged on both sides of the nozzle row 101, but may be arranged only at one end of the nozzle row 101. In that case, it is not possible to secure a density close to that of the large nozzle 102a, but if a conveyance adjustment value is set so that black streaks do not occur during high-duty printing, white streaks that occur during low-duty printing can be set. Dots can also be formed on the portions, and white streaks can be alleviated to some extent.

  The ink ejection positions on the recording medium 10 by the small nozzles 103a and 104a are set so as not to overlap each time of main scanning at the time of manufacture in consideration of transport errors. However, there is a possibility that a deviation occurs due to a secular change or the like of the transport device 13. In order to cope with such a situation, it is desirable that a test pattern can be printed and proofread even after manufacture.

  The liquid ejecting apparatus according to the embodiment of the present invention has been described above, but the present invention can be variously modified without changing the gist. For example, the main scanning can be performed by the method described in Patent Document 1. Further, by combining the techniques described in Patent Document 2, the number of small nozzles 103a and 104a used can be changed according to the duty of the image.

  Further, the scanning of the print head 11 with respect to the recording medium 10 may be performed without moving the recording medium 10. Conversely, the recording medium 10 can be moved without moving the print head 11. The distance between the large nozzle 102a and the small nozzles 103a and 104a is based on the relationship between the structure for supplying ink and the structure for ejecting ink, so that the large nozzles 102a, the small nozzles 103a, and the small nozzles 104a are mutually connected. In reality, the centers of the nozzles are arranged at equal intervals between the large nozzle 102a and the small nozzle 103a. However, it is not always necessary to form them at regular intervals. In addition, the large nozzles 102 a and the small nozzles 103 a and 104 a are not arranged in a line on a straight line, but at least a part of them can be arranged so as to be shifted from the center line of the nozzle array 101.

  DESCRIPTION OF SYMBOLS 10 Recording medium, 11 Print head (liquid ejecting head), 12 Carriage (a part of main scanning means), 13 Conveyance apparatus (a part of sub-scanning means), 20 Operation control part, 21 Head drive part, 22 Carriage movement control Section (part of main scanning means), 23 transport control section (part of sub scanning means), 30 data processing section, 31 external interface, 32 central processing section, 33 ROM, 34 RAM, 35 internal interface, 101 nozzle array , 102 Large nozzle, 103, 104, 105 Small nozzle area, 103a, 104a, 105a to 105e Small nozzle, W Large nozzle area

Claims (6)

In a liquid ejecting head provided with a nozzle row for ejecting liquid,
The nozzle row is composed of a large nozzle that is disposed in the center of the nozzle row and has a relatively large amount of liquid to be ejected, and a small nozzle that is disposed on at least one end side of the nozzle row and has a relatively small amount of liquid to be ejected.
The large nozzles are formed in the same size for each liquid jet,
The liquid ejecting head, wherein each of the small nozzles is formed in an equal size to each other. The liquid ejecting head according to claim 1,
A plurality of the small nozzles are respectively disposed at both ends of the nozzle row. The liquid ejecting head according to claim 2.
The liquid ejecting head, wherein an area covering the ejection target with the liquid ejected from the small nozzle is set to a half of an area covering the ejection target with the liquid ejecting from the large nozzle. The liquid ejecting head according to any one of claims 1 to 3,
The centers of the large nozzle and the small nozzle are arranged at equal intervals between the large nozzles, between the small nozzles, and between the large nozzle and the small nozzle. Liquid ejecting head. A liquid jet head according to any one of claims 1 to 4,
Main scanning means for performing main scanning by relatively moving the liquid ejecting head and the ejection target in a direction intersecting the row direction of the nozzle row;
Sub-scanning means for performing sub-scanning by relatively moving the ejection target and the liquid ejecting head so that the position of the liquid ejected from the liquid ejecting head on the ejection target is shifted every main scanning. Have
The sub-scanning means generates a vacant area between areas where liquid is ejected by the large nozzle on the ejection target in one main scanning and the next main scanning. The liquid ejection position on the ejection target by the small nozzle is ejected from the period of the liquid ejection position by the large nozzle on the ejection target in the previous main scan or the next main scan. A liquid ejecting apparatus that performs sub-scanning so as to be displaced in a row direction. A liquid jet head according to any one of claims 2 to 4,
Main scanning means for performing main scanning by relatively moving the liquid ejecting head, the ejection target, and the direction of the nozzle row intersecting with each other;
Sub-scanning means for performing sub-scanning by relatively moving the ejection target and the liquid ejecting head so that the position of the liquid ejected from the liquid ejecting head on the ejection target is shifted every main scanning. Have
The sub-scanning means generates a vacant area between areas where liquid is ejected by the large nozzle on the ejection target in one main scanning and the next main scanning. In the same empty area, the liquid ejection position on the ejection target by the small nozzles on one end side of the nozzle row in one main scanning and the nozzles in the main scanning before and after the ejection are performed. A liquid ejecting apparatus, wherein sub-scanning is performed such that a liquid ejecting position on the ejection target by the small nozzle on the other end side of the row is shifted in the row direction of the nozzle row.

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