JP5464923B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus including an ink head that discharges a plurality of types of ink.

  In general, this type of ink jet recording apparatus has an ink head including a plurality of print heads for ejecting ink. The ink head moves in a predetermined direction (hereinafter, this direction is referred to as a main scanning direction), and a recording medium such as recording paper is conveyed in a sub-scanning direction orthogonal to the main scanning direction. The ink head ejects ink toward the recording medium while moving in the main scanning direction, and printing is performed on the recording medium with these inks.

  By the way, in recent years, the demand for higher image quality has become very strong. As means for responding to such a request, for example, increasing the type of ink or increasing the number of nozzles provided in the print head (that is, increasing the density of the nozzles) is performed. However, in order to increase the number of ink types, the number of print heads must be increased, which increases the size of the ink head. There is a problem of increasing manufacturing costs in increasing the density of nozzles.

  As an invention made in order to reduce the size of the ink head, for example, there is the one shown in Patent Document 1. This conventional one is a yellow print head that is considered to have a relatively small influence on image quality among yellow (Y), magenta (M), cyan (C), and black (K) so-called process colors. The nozzle pitch is roughened (see FIG. 7 of Patent Document 1). According to this, since the yellow nozzle row can be halved as the nozzle pitch is increased, the ink head can be reduced in size.

  Further, this Patent Document 1 also discloses that a process color and a so-called light color are used in combination for cyan and magenta. That is, Patent Document 1 discloses an ink head using six types of inks of black (K), cyan (C), light cyan (LC), magenta (M), light magenta (LM), and yellow (Y). (See FIG. 8 of Patent Document 1). In this ink head, the nozzle pitch of black is smaller than the nozzle pitches of other colors. For cyan and magenta, the process color nozzle pitch and the light color nozzle pitch are the same.

JP 2000-141714 A

  In the above conventional technique, as a means for reducing the size of the ink head, a means for increasing the nozzle pitch for one of the process colors (specifically, yellow) is employed. However, the process color is an important color that is indispensable for image formation of printed matter. For this reason, the above-described conventional technique is not necessarily preferable from the viewpoint of maintaining high image quality of the printed matter, and it cannot be denied that the image quality is deteriorated to some extent. In other words, this conventional technique has a large reduction in image quality required as a compensation for downsizing the ink head.

  The present invention has been made in view of the above points, and an object of the present invention is to reduce the size of the ink head while suppressing deterioration of the image quality of the printed matter. Another object of the present invention is to obtain a printed matter with higher image quality while maintaining the size of a conventional ink head.

An ink jet recording apparatus according to the present invention is an ink jet recording apparatus including an ink head that moves relative to a recording medium in a main scanning direction, and the ink head is in a direction orthogonal to the main scanning direction. A nozzle row composed of a plurality of nozzles arranged at a predetermined nozzle pitch in the sub-scanning direction is arranged such that the nozzles of each nozzle row are arranged at positions shifted in the sub-scanning direction with respect to the nozzles of the other nozzle rows. A plurality of print heads provided in two rows in the scanning direction, wherein the print head is constituted by the two nozzle rows of the print head, and ejects ink of any one of the process colors from each nozzle; a plurality of process color nozzle array is constituted by one nozzle arrays of the nozzle arrays of the two rows of the print head, the flop A light color nozzle row that discharges a light color of any one of the process colors from each of the nozzles, and the nozzle pitches in the sub-scanning direction of the plurality of process color nozzle rows are equal to each other The nozzle pitch in the sub-scanning direction of the light color nozzle row is larger than the nozzle pitch of the process color nozzle row.

  According to the present invention, it is possible to reduce the size of the ink head while suppressing deterioration of the image quality of the printed matter. Further, it is possible to obtain a printed matter with higher image quality while maintaining the size of the conventional ink head.

1 is a front view illustrating a part of an inkjet printer according to an embodiment of the present invention. It is a schematic diagram which shows one Embodiment of an ink supply path | route. It is a back view which shows the ink head which concerns on 1st Embodiment. 3 is a block diagram illustrating an embodiment of a control system that controls the operation of the ink head. FIG. It is a front view which shows a part of inkjet printer which concerns on 2nd Embodiment. It is a back view which shows the ink head which concerns on 2nd Embodiment. It is a back view which shows the ink head which concerns on 3rd Embodiment. It is a reverse view which shows the ink head which concerns on 4th Embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, as an example of an ink jet recording apparatus, an ink jet printer 1 that performs printing on a recording sheet as a recording medium will be described.

  The “recording medium” in the present invention is not only a recording medium made of paper such as plain paper but also a resin material such as PVC and polyester, a metal such as aluminum or iron, wood, and other various materials. A wide range of recording media shall be included. Further, the “inkjet type” in the present invention means a printing method based on an inkjet technique. Furthermore, “inkjet” includes various known methods, for example, various continuous methods such as a binary deflection method or a continuous deflection method, and various on-demand methods such as a thermal method or a piezoelectric element method. .

<First Embodiment>
As shown in FIG. 1, the ink jet printer 1 includes an apparatus main body 2 and a guide rail 3 fixed to the apparatus main body 2. The apparatus main body 2 is provided with a platen 4 that supports the recording paper P. The guide rail 3 extends in the left-right direction. Hereinafter, the longitudinal direction of the guide rail 3 is referred to as a main scanning direction Y.

  A carriage 5 is engaged with the guide rail 3. Although not shown, rollers are provided on the right end side and the left end side of the guide rail 3. An endless belt 6 is wound around these rollers. The carriage 5 is fixed to the belt 6. When the belt 6 travels, the carriage 5 moves in the main scanning direction Y. That is, the carriage 5 is movable in the main scanning direction Y along the guide rail 3. The recording paper P is transported in the sub-scanning direction, which is a direction orthogonal to the main scanning direction Y.

  Six main tanks 30 and 31 are detachably attached to the apparatus main body 2 (in other words, exchangeable). That is, the main tanks 30 and 31 are so-called ink cartridges. The main tank 30 stores cyan, magenta, yellow, and black inks that are process colors, and the main tank 31 stores light cyan and light magenta inks that are light colors. The apparatus main body 2 includes a control device 7 that controls the operation of each unit of the inkjet printer 1.

  An ink head 40 is provided on the carriage 5. In the present embodiment, the ink head 40 includes a total of five print heads 41 and 42. Specifically, the ink head 40 according to the present embodiment includes first to fourth print heads 41 and a fifth print head 42. The configurations of the first to fifth print heads 41 and 42 are the same.

  As shown in FIG. 2, two ink chambers 41 a and 41 b are partitioned inside the first to fourth print heads 41 by a partition wall 47. The ink chambers 41a and 41b are each connected to a damper 52 via an ink supply path 50c. The damper 52 is a container that can store a predetermined amount of ink, and is formed of, for example, a flexible material. The damper 52 is connected to the ink tube 50b. An ink tube 50 a is connected to the main tank 30, and the ink tube 50 a is connected to two ink tubes 50 b via a three-way joint 51. Similarly, two ink chambers 42 a and 42 b are partitioned inside the fifth print head 42 by a partition wall 47. The ink chambers 42a and 42b are each connected to the damper 52 via the ink supply path 53b. Each main tank 31 is connected to a damper 52 via an ink tube 53a. As described above, ink is supplied from the single main tank 30 to the first to fourth print heads 41. Ink is supplied from the plurality of main tanks 31 to the fifth print head 42. As shown in FIG. 1, the ink tubes 50a and 53a are accommodated in a cable bear 54 having flexibility.

  In this embodiment, the ink tube 50a extending from the main tank 30 is branched into two ink tubes 50b via the three-way joint 51. However, the two ink tubes 50a are connected to the main tank 30, respectively. It is also possible to connect the ink tube 50a to the damper 52 without branching. Alternatively, the main tank 30 may be divided into two tanks, and an ink tube 50a may be connected to each tank.

  In the present embodiment, process color ink is supplied to the first to fourth print heads 41, and light color ink is supplied to the fifth print head 42. For example, as shown in FIG. 3, cyan (C), magenta (M), yellow (Y), and black (K) inks are supplied to the first to fourth print heads 41 from the front left side. Light cyan (LC) and light magenta (LM) inks are supplied to the ink chambers 42a and 42b of the fifth print head 42, respectively. The arrangement order of the print heads 41 and 42 is not limited to the above, and can be changed as appropriate. The length of each print head 41, 42 in the sub-scanning direction X is set to about 1 inch. However, the specific length is not limited to this, and may be 2 inches, for example.

A plurality of nozzles 44 for discharging each ink are provided on the lower surface of each print head 41, 42. The nozzles 44 located below the ink chambers 41a, 41b, 42a, and 42b communicate with the ink chambers 41a, 41b, 42a, and 42b, respectively. Specifically, the process color nozzle rows for cyan (C), magenta (M), yellow (Y), and black (K) (hereinafter referred to as process color nozzle rows) are each in the main scanning direction Y. Are composed of two nozzle rows arranged at a predetermined interval. The nozzles 44 in each nozzle row are arranged at a predetermined nozzle pitch (= 2P _P ) along the sub-scanning direction X. Further, the adjacent nozzle rows are arranged such that the nozzles 44 of one nozzle row are shifted from the nozzles 44 of the other nozzle row by a half pitch (= P _P ) in the sub-scanning direction X. As described above, the nozzles 44 of the process color nozzle row are arranged in a so-called staggered pattern. Such staggered, the nozzle pitch P _P in the sub-scanning direction of the process color nozzle array is a half of the nozzle pitch of each nozzle array, high density of the nozzle is achieved.

  In the present specification, the “nozzle pitch in the sub-scanning direction of the process color nozzle row” means that the process color nozzle row is composed of a plurality of nozzle rows (in this embodiment, two nozzle rows). In this case, it does not mean the nozzle pitch of each nozzle row, but means the nozzle pitch in the sub-scanning direction including all those nozzle rows. The same applies to “nozzle pitch in the sub-scanning direction of the light color nozzle row” to be described later.

Each nozzle row of light cyan (LC) and light magenta (LM) (hereinafter referred to as a light color nozzle row) is composed of one nozzle row extending in the sub-scanning direction X. Both the light color nozzle rows are arranged such that the nozzles 44 of one light color nozzle row are shifted by a half pitch in the sub-scanning direction X with respect to the nozzles 44 of the other light color nozzle row. Nozzle pitch L _P in the sub-scanning direction of the light color nozzle array is twice the nozzle pitch P _P of the process color nozzle array. The number of nozzles included in each nozzle row is 180. As a result, the process color print resolution is 360 dpi, and the light color print resolution is 180 dpi. However, the printing resolution of the process color and the light color is not particularly limited, and can be arbitrarily changed. In FIG. 2, the nozzles 44 in the middle of the print heads 41 and 42 are omitted and shown by dotted lines.

Thus, in the present embodiment, the nozzle pitch is finer for all four process colors than for the light color. Conversely, the nozzle pitch of the two light colors is coarser than that of the process color. The light color uses less ink than the process color, and the light color ink usage is actually about 50% or less of the process color ink usage. Therefore, be set to be larger than the nozzle pitch P _P of the nozzle pitch L _P of the process color nozzle array of the light color nozzle array, it is possible to minimize degradation in image quality of the printed matter.

  In the present embodiment, each of the first to fourth print heads 41 ejects one type of process color ink. On the other hand, the fifth print head 42 ejects two types of light color inks. A conventional ink head for six colors is composed of a total of six print heads. On the other hand, according to the present embodiment, the ink head 40 is configured by a total of five print heads, ie, the first to fourth print heads 41 and the fifth print head 42. For this reason, according to the present embodiment, the number of print heads can be reduced by one as compared with the prior art. As a result, the ink head 40 can be made smaller than before.

  In the present embodiment, the print heads 41 and 42 are provided with a piezo element 48 as a drive unit provided corresponding to each nozzle 44 as shown in FIG. A control device 7 is connected to the piezo element 48. The control device 7 receives print data from the outside of the inkjet printer 1 and applies a voltage to the predetermined piezo element 48 at a predetermined timing so that ink is ejected from the predetermined nozzle 44 at a predetermined timing. The piezo element 48 is deformed when it receives a voltage. By this deformation operation, the ink in the print heads 41 and 42 is ejected from the nozzles 44 at a desired timing. The ejected ink becomes ink droplets and deposits on the recording paper P to form an image or the like on the recording paper P. Note that the type of the drive unit is not limited at all, and may not be the piezo element 48.

  The control program provided in the control device 7 is configured to supply signals for two rows to the piezo elements 48 of the process color nozzle row having a two-row configuration. Further, the piezo elements 48 of the light color nozzle row having a single row structure are also configured to supply signals for two rows. Accordingly, the control program for two rows used for the conventional six-color ink head can be used as it is. For this reason, it is not necessary to create a new control program, and the creation cost can be reduced. In addition, a series of printing operations can be performed efficiently without reducing the printing speed. However, the control program is not limited to this. Of course, it is also possible to create a control program for one-row configuration and execute printing according to the control program.

Second Embodiment
In the first embodiment, two colors of light cyan and light magenta are used as the light color ink. However, if further higher image quality is desired, the ink head 40 can be configured as follows. The ink jet printer 1 according to this embodiment has a high image quality while maintaining the ink head 40 in the same size as the conventional one.

  As shown in FIGS. 5 and 6, the ink head 40 of this embodiment further includes a sixth print head 45 having the same configuration as that of the fifth print head 42. Light yellow (LY) and light black (LK) inks are respectively supplied to the ink chambers 45 a and 45 b of the sixth print head 45 from a main tank 31 additionally provided in the apparatus main body 2. That is, in this embodiment, two new light colors are added, and a total of four color light colors are used together with a total of four process color inks.

  According to the present embodiment, the size of the ink head 40 is increased as compared with the first embodiment by the addition of the sixth print head 45. However, the number of print heads is only six, and the size thereof is equivalent to a conventional so-called six-color ink head. On the other hand, by adding a new light color, it is possible to obtain an image quality superior to the conventional one. Therefore, according to the present embodiment, it is possible to achieve high image quality of the printed matter while maintaining the size of the conventional ink head.

<Third Embodiment>
As described above, according to the first embodiment, it is possible to obtain an image quality equivalent to that of the conventional art using only the first to fifth print heads 41 and 42. When a total of six print heads are used as in the conventional case, it is possible to eject ink that has not been used conventionally from the sixth print head. In the second embodiment, another light color ink is ejected from the sixth print head 45. However, the type of ink ejected from the sixth print head 45 is not limited to the light color.

  In the third embodiment, so-called spot color ink is ejected from the sixth print head 45. Specifically, as shown in FIG. 7, in the third embodiment, white ink (W) is supplied to the sixth print head 45. As the spot color, for example, ink of gold, silver, fluorescent color or the like can be used instead of white. According to this, it is possible to perform printing using a color that cannot be expressed well only by the process color, for example, a fluorescent color. Alternatively, the sixth print head 45 may eject ink used in a single color such as red. Normally, red is produced by mixing magenta and yellow, but the mixed red is less vivid than the single red. Therefore, the image quality can be further improved by separately using a single color red ink. Similarly, other single color inks can be used. Further, transparent ink may be ejected from the sixth print head 45.

<Fourth embodiment>
In the second embodiment, only the light color is discharged from the fifth and sixth print heads 42 and 45. However, both the process color and the light color can be ejected from the fifth or sixth print heads 42 and 45. In the present embodiment, as shown in FIG. 8, cyan ink and light cyan ink are supplied to the ink chambers 42a and 42b of the fifth print head 42, respectively. Also, magenta ink and light magenta ink are supplied to the ink chambers 45a and 45b of the sixth print head 45, respectively.

  According to the present embodiment, the amount of ink that can be ejected is increased for cyan and magenta, which are process colors. Therefore, it becomes possible to obtain a more vivid printed matter. As a result, the image quality of the printed material can be improved. The fifth and sixth print heads 42 and 45 may be supplied with other process colors and light color inks.

<Other embodiments>
Note that the light color used in the inkjet printer 1 may be any one of the process colors, and it is not always necessary to use two or more colors as in the above embodiments. When only one light color is used, for example, one of the ink chambers 42a and 42b of the print head 42 may be used.

  In the embodiment, the print heads 41, 42, and 45 have two nozzle rows. However, the number of nozzle rows of each print head 41, 42, 45 may be three or more. The nozzle rows of the print heads 41, 42, and 45 are not necessarily the same. At least one of the print heads 41, 42, and 45 may have more or less nozzle rows than the other print heads.

  In the above embodiment, the ink head 40 is configured by combining a plurality of print heads separable from each other. However, the ink head 40 may be composed of a single print head. In other words, in the above embodiment, a plurality of print heads may be integrally formed so as not to be separated from each other.

1 Inkjet recording device (inkjet printer)
7 Control device 40 Ink head 41, 42, 45 Print head 44 Nozzle 48 Drive unit (piezo element)
P Recording medium (recording paper)
X Sub-scanning direction Y Main-scanning direction P Nozzle pitch of _P process color nozzle row L Nozzle pitch of _P light color nozzle row

Claims (7)

An ink jet recording apparatus including an ink head that moves relative to a recording medium in a main scanning direction,
The ink head includes a nozzle array composed of a plurality of nozzles arranged at a predetermined nozzle pitch in a sub-scanning direction that is a direction orthogonal to the main scanning direction, and the nozzles of each nozzle array are compared to the nozzles of the other nozzle arrays. A plurality of print heads provided in two rows in the main scanning direction so as to be arranged at positions shifted in the sub-scanning direction;
The print head is constituted by the two nozzle rows of the print head, and a plurality of process color nozzle rows that discharge ink of any one of the process colors from the nozzles, and the print head. A light color nozzle row configured by one nozzle row of the two nozzle rows and ejecting a light color which is a light color of any one of the process colors from each of the nozzles;
The nozzle pitches in the sub-scanning direction of the plurality of process color nozzle rows are equal to each other,
An ink jet recording apparatus in which a nozzle pitch in the sub-scanning direction of the light color nozzle row is larger than the nozzle pitch of the process color nozzle row. The process colors are yellow, magenta, cyan, and black,
The ink jet recording apparatus according to claim 1, wherein the light colors are light cyan and light magenta. The ink head includes first to fifth print heads arranged in the main scanning direction,
The process colors are yellow, magenta, cyan, and black,
The yellow, magenta, cyan, and black nozzle rows are each constituted by the two nozzle rows of the first to fourth print heads,
The light colors are light cyan and light magenta,
One of the light cyan nozzle row and the light magenta nozzle row is constituted by one nozzle row of the two nozzle rows of the fifth print head, and the other is the first nozzle row. 2. The ink jet recording apparatus according to claim 1 , wherein the ink jet recording apparatus is configured by another one nozzle row of the two nozzle rows of the five print heads. The ink head includes first to sixth print heads arranged in the main scanning direction,
The process colors are yellow, magenta, cyan, and black,
The yellow, magenta, cyan, and black nozzle rows are each constituted by the two nozzle rows of the first to fourth print heads,
The light color is light yellow, light magenta, light cyan, and light black,
The light yellow nozzle row, the light magenta nozzle row, the light cyan nozzle row, and the light black nozzle row are one of the two nozzle rows of the fifth or sixth print head. The ink jet recording apparatus according to claim 1 , wherein the ink jet recording apparatus is configured by a nozzle row of rows. The ink head includes first to sixth print heads arranged in the main scanning direction,
The process colors are yellow, magenta, cyan, and black,
The yellow, magenta, cyan, and black nozzle rows are each constituted by the two nozzle rows of the first to fourth print heads,
The light colors are light cyan and light magenta,
One of the light cyan nozzle row and the light magenta nozzle row is constituted by one nozzle row of the two nozzle rows of the fifth print head, and the other is the first nozzle row. The other two nozzle rows of the two print heads of the five print heads,
The ink jet recording apparatus according to claim 1 , wherein the sixth print head ejects ink of a color other than yellow, magenta, cyan, black, light cyan, and light magenta. Printhead having a nozzle array for said write color from other one row nozzles of the nozzle row of the two rows, to discharge any color of ink of the process color ink jet according to claim 1 Recording device. An ink jet recording apparatus including an ink head that moves relative to a recording medium in a main scanning direction, wherein the ink head includes:
A plurality of nozzles for a process color having at least a plurality of nozzles arranged in a sub-scanning direction that is a direction orthogonal to the main scanning direction, and discharging ink of any one of the process colors from each of the nozzles;
A plurality of nozzles arranged at least in the sub-scanning direction, and a light color nozzle row that discharges a light color that is one of the process colors from each of the nozzles, and
The ink jet recording apparatus is provided corresponding to the nozzles, and each controls a plurality of driving units that apply a driving force for ejection to the ink in the nozzles, and a control that supplies a driving signal to the driving units. a device and the, the,
Each of the process color nozzle rows includes a plurality of nozzles arranged at a predetermined nozzle pitch in the sub-scanning direction, and the nozzles in each nozzle row are in the sub-scanning direction with respect to the nozzles of the other nozzle rows. Two rows are provided in the main scanning direction so as to be arranged at shifted positions,
The light color nozzle row includes one nozzle row composed of a plurality of nozzles arranged at the nozzle pitch in the sub-scanning direction,
The nozzle pitches in the sub-scanning direction of the plurality of process color nozzle rows are equal to each other,
The nozzle pitch in the sub-scanning direction of the light color nozzle row is larger than the nozzle pitch of the process color nozzle row,
The control device supplies signals for two rows to the driving unit of the process color nozzle row constituted by two nozzle rows, and the light color nozzle row constituted by one nozzle row An ink jet recording apparatus that supplies signals for two rows to the driving unit.

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