Patent Grant
8201908
Japanese Patent application No. 2009-188944 is hereby incorporated by reference in its entirety.
1. Field of Invention
The present invention relates to a fluid ejecting apparatus and a fluid ejecting method.
2. Description of Related Art
An ink-jet printer having a plurality of nozzles from which ink (fluid) is ejected onto a print target medium is known as an example of a fluid ejecting apparatus. The nozzles are aligned in a predetermined direction to constitute a nozzle line(s). Some known ink-jet printers performs operation for ejecting ink from nozzles while moving nozzle lines in a movement direction, which is the direction that is orthogonal to the predetermined direction, and operation for transporting a print target medium in the predetermined direction repeatedly.
A printing apparatus that performs printing by using white ink in addition to color ink such as cyan, magenta, and yellow ink is known in the art. An example of such a printer is disclosed in JP-A-2002-038063. The printer such as the disclosed one uses white ink for base coat treatment. The white base coating makes it possible to form a color print image having excellent color development property without being influenced by the ground color of a print target medium.
An example of base coat treatment with the use of white ink is the printing of a background image on a print target medium by using white ink first and the printing of a color image on the background image by using color ink thereafter. Generally, the colors of ink called roughly as white ink actually differ from one to another in the strict sense. In view of such color differences, in some cases, printing is performed with the use of white ink and color ink to form a desired white background image. When the base coat treatment is performed, a color image is printed after the lapse of drying time, which is the time for drying a background image after the printing of the background image. By this means, it is possible to prevent ink from running thereon. However, if the length of the background drying time is not constant, the depth of shade of an image obtained will not be uniform.
An advantage of some aspects of the invention is to provide a technique for suppressing variation in the length of drying time.
In order to offer the above advantage, though not limited thereto, a main aspect of the invention provides a fluid ejecting apparatus that includes: a first nozzle line that includes a plurality of first nozzles that are aligned in a predetermined direction, first fluid being ejected from the first nozzles; a second nozzle line that includes a plurality of second nozzles that are aligned in the predetermined direction, second fluid being ejected from the second nozzles; a movement mechanism that moves the first nozzle line and the second nozzle line relative to a target medium in a movement direction, the movement direction being orthogonal to the predetermined direction; a transportation mechanism that transports the target medium relative to the first nozzle line and the second nozzle line in the predetermined direction; a controlling section that performs control for repeating image formation operation and transportation operation, the image formation operation being operation for ejecting the first fluid from the first nozzles and ejecting the second fluid from the second nozzles while moving the first nozzle line and the second nozzle line in the movement direction by means of the movement mechanism, the transportation operation being operation for transporting the target medium relative to the first nozzle line and the second nozzle line in the predetermined direction by predetermined transportation amount by means of the transportation mechanism; and a group of nozzles that are not the first nozzles nor the second nozzles, wherein the image formation operation includes a certain image formation operation and another image formation operation, the controlling section performs control for forming a first image by using the first fluid and the second fluid in the certain image formation operation, the controlling section performs control for forming a second image on the first image by using at least the second fluid in the another image formation operation after lapse of time for drying the first image, the first nozzles and the second nozzles that are used for forming the first image are located upstream of the second nozzles that are used for forming the second image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles are located downstream of the first nozzles and the second nozzles that are used for forming the first image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles are located upstream of the second nozzles that are used for forming the second image in the predetermined direction, length of an area where the group of nozzles that are not the first nozzles nor the second nozzles are located in the predetermined direction is an integral multiple of the predetermined transportation amount, and the group of nozzles that are not the first nozzles nor the second nozzles do not eject any fluid.
Other features and advantages offered by the invention will be fully understood by referring to the following detailed description in conjunction with the accompanying drawings.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Referring to the following detailed description in conjunction with the accompanying drawings, one will fully understand at least the following inventive concept of the invention.
A fluid ejecting apparatus having the following features is disclosed in the detailed description of the invention and the accompanying drawings. The fluid ejecting apparatus includes: a first nozzle line that includes a plurality of first nozzles that are aligned in a predetermined direction, first fluid being ejected from the first nozzles; a second nozzle line that includes a plurality of second nozzles that are aligned in the predetermined direction, second fluid being ejected from the second nozzles; a movement mechanism that moves the first nozzle line and the second nozzle line relative to a target medium in a movement direction, the movement direction being orthogonal to the predetermined direction; a transportation mechanism that transports the target medium relative to the first nozzle line and the second nozzle line in the predetermined direction; a controlling section that performs control for repeating image formation operation and transportation operation, the image formation operation being operation for ejecting the first fluid from the first nozzles and ejecting the second fluid from the second nozzles while moving the first nozzle line and the second nozzle line in the movement direction by means of the movement mechanism, the transportation operation being operation for transporting the target medium relative to the first nozzle line and the second nozzle line in the predetermined direction by predetermined transportation amount by means of the transportation mechanism; and a group of nozzles that are not the first nozzles nor the second nozzles, wherein the image formation operation includes a certain image formation operation and another image formation operation, the controlling section performs control for forming a first image by using the first fluid and the second fluid in the certain image formation operation, the controlling section performs control for forming a second image on the first image by using at least the second fluid in the another image formation operation after lapse of time for drying the first image, the first nozzles and the second nozzles that are used for forming the first image are located upstream of the second nozzles that are used for forming the second image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles are located downstream of the first nozzles and the second nozzles that are used for forming the first image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles are located upstream of the second nozzles that are used for forming the second image in the predetermined direction, length of an area where the group of nozzles that are not the first nozzles nor the second nozzles are located in the predetermined direction is an integral multiple of the predetermined transportation amount, and the group of nozzles that are not the first nozzles nor the second nozzles do not eject any fluid. A fluid ejecting apparatus according to the above aspect of the invention is capable of making the length of time for drying the first image constant. For example, if the fluid ejecting apparatus is a printing apparatus, it is possible to suppress non-uniformity in the depth of shade of an image obtained.
In the configuration of a fluid ejecting apparatus according to the above aspect of the invention, it is preferable that the length of the area in the predetermined direction should vary depending on drying characteristics of the first image formed on the target medium. A fluid ejecting apparatus having such a preferred configuration makes it possible to avoid deterioration in image quality due to the running of fluid reliably and shorten time required for image formation operation as much as possible.
In the configuration of a fluid ejecting apparatus according to the above aspect of the invention, it is preferable that each of length of an area where the first nozzles and the second nozzles that are used for forming the first image are located in the predetermined direction and length of an area where the second nozzles that are used for forming the second image are located in the predetermined direction should be an integral multiple of the predetermined transportation amount. A fluid ejecting apparatus having such a preferred configuration is capable of making the number of times of execution of image formation operation constant for each of the images.
In the configuration of a fluid ejecting apparatus according to the above aspect of the invention, it is preferable that the second image should be formed by using the first fluid and the second fluid, the first nozzles and the second nozzles that are used for forming the first image should be located upstream of the first nozzles and the second nozzles that are used for forming the second image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles should be located downstream of the first nozzles and the second nozzles that are used for forming the first image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles should be located upstream of the first nozzles and the second nozzles that are used for forming the second image in the predetermined direction, the length of the area where the group of nozzles that are not the first nozzles nor the second nozzles are located in the predetermined direction should be an integral multiple of the predetermined transportation amount, and the group of nozzles that are not the first nozzles nor the second nozzles do not eject any fluid. A fluid ejecting apparatus having such a preferred configuration is capable of suppressing non-uniformity in the depth of shade of an image obtained. For example, if the fluid ejecting apparatus is a printing apparatus, it is possible to improve the color reproduction property of the second image.
A fluid ejecting apparatus according to another aspect of the invention includes: a first nozzle line that includes a plurality of first nozzles that are aligned in a predetermined direction, first fluid being ejected from the first nozzles; a second nozzle line that includes a plurality of second nozzles that are aligned in the predetermined direction, second fluid being ejected from the second nozzles; a movement mechanism that moves the first nozzle line and the second nozzle line relative to a target medium in a movement direction, the movement direction being orthogonal to the predetermined direction; a transportation mechanism that transports the target medium relative to the first nozzle line and the second nozzle line in the predetermined direction; a controlling section that performs control for repeating image formation operation and transportation operation, the image formation operation being operation for ejecting the first fluid from the first nozzles and ejecting the second fluid from the second nozzles while moving the first nozzle line and the second nozzle line in the movement direction by means of the movement mechanism, the transportation operation being operation for transporting the target medium relative to the first nozzle line and the second nozzle line in the predetermined direction by predetermined transportation amount by means of the transportation mechanism; and a group of nozzles that are not the first nozzles nor the second nozzles, wherein the image formation operation includes a certain image formation operation and another image formation operation, the controlling section performs control for forming a first image by using the first fluid in the certain image formation operation, the controlling section performs control for forming a second image on the first image by using the first fluid and the second fluid in the another image formation operation after lapse of time for drying the first image, the first nozzles that are used for forming the first image are located upstream of the first nozzles and the second nozzles that are used for forming the second image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles are located downstream of the first nozzles that are used for forming the first image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles are located upstream of the first nozzles and the second nozzles that are used for forming the second image in the predetermined direction, length of an area where the group of nozzles that are not the first nozzles nor the second nozzles are located in the predetermined direction is an integral multiple of the predetermined transportation amount, and the group of nozzles that are not the first nozzles nor the second nozzles do not eject any fluid. A fluid ejecting apparatus according to the above aspect of the invention is capable of making the length of time for drying the first image constant. For example, if the fluid ejecting apparatus is a printing apparatus, it is possible to suppress non-uniformity in the depth of shade of an image obtained.
A fluid ejecting method used by a fluid ejecting apparatus is also provided. The fluid ejecting apparatus has a first nozzle line and a second nozzle line. The first nozzle line includes a plurality of first nozzles that are aligned in a predetermined direction for ejecting first fluid therefrom. The second nozzle line includes a plurality of second nozzles that are aligned in the predetermined direction for ejecting second fluid therefrom. The fluid ejecting method includes: image formation operation for ejecting the first fluid from the first nozzles and ejecting the second fluid from the second nozzles while moving the first nozzle line and the second nozzle line in a movement direction that is orthogonal to the predetermined direction, the image formation operation including a certain image formation operation, and another image formation operation; and transportation operation for transporting a target medium relative to the first nozzle line and the second nozzle line in the predetermined direction by predetermined transportation amount, wherein the image formation operation and the transportation operation are performed repeatedly, in order to form a first image by using the first fluid and the second fluid in the certain image formation operation and form a second image on the first image by using the second fluid in the another image formation operation after lapse of time for drying the first image, the first fluid and the second fluid are respectively ejected from the first nozzles and the second nozzles that are used for forming the first image, and in addition, the second fluid is ejected from the second nozzles that are used for forming the second image and are located downstream of the first nozzles and the second nozzles that are used for forming the first image in the predetermined direction, a group of nozzles that are not the first nozzles nor the second nozzles are located downstream of the first nozzles and the second nozzles that are used for forming the first image in the predetermined direction, the group of nozzles that are not the first nozzles nor the second nozzles are located upstream of the second nozzles that are used for forming the second image in the predetermined direction, length of an area where the group of nozzles that are not the first nozzles nor the second nozzles are located in the predetermined direction is an integral multiple of the predetermined transportation amount, and the group of nozzles that are not the first nozzles nor the second nozzles do not eject any fluid. A fluid ejecting method according to the above aspect of the invention makes it possible to make the length of time for drying the first image constant. For example, if the fluid ejecting method is a printing method, it is possible to suppress non-uniformity in the depth of shade of an image obtained.
Printing System
In the following description of exemplary embodiments of the invention, an ink-jet printer is explained as an example of a fluid ejecting apparatus. Among various ink-jet printers, a serial printer (hereinafter referred to as “printer 1”) is taken as an example.
The controller 10 (controlling section) is a controlling unit, which controls the operation of the printer 1. An interface unit 11 is used for performing data transmission/reception between the computer 60 and the printer 1. A CPU 12 is a central processing unit that performs arithmetic processing for controlling the entire operation of the printer 1. A memory 13 provides a memory area for storing programs, a work area, and the like for the operation of the CPU 12. In accordance with a program stored in the memory 13, the CPU 12 controls each unit through a unit controlling circuit 14.
A transportation unit 20 (transportation mechanism) is a unit that picks up the print target medium S and then feeds it to a position where an image can be printed thereon. In addition, the transportation unit 20 transports the print target medium S in a transportation direction (predetermined direction) by predetermined transportation amount during printing. The transportation unit 20 includes a paper-feed roller 21, a transportation roller 22, and a paper-eject roller 23. The paper-feed roller 21 is rotated to feed a sheet of the print target medium S on which an image is to be printed to the transportation roller 22. The controller 10 causes the transportation roller 22 to rotate to set the position of the print target medium S for starting printing operation (i.e., at a print start position). The carriage unit 30 (movement mechanism) is a unit that moves a head 41 in the direction that is orthogonal to the transportation direction (hereinafter referred to as “movement direction”). The carriage unit 30 includes a carriage 31.
The head unit 40, which includes the head 41, is a unit that ejects ink onto the print target medium S. The head 41 travels in the movement direction together with the carriage 31. A plurality of nozzles is formed through the bottom plate of the head 41. The nozzles function as openings from which ink is ejected. An ink chamber, which is a compartment in which ink can be retained, is formed for each of the nozzles. The ink compartments are not illustrated in the drawing.
The printer 1 having the configuration described above performs dot formation processing and medium transportation processing repeatedly. In the dot formation processing, the printer 1 discharges ink droplets from the head 41, which travels in the movement direction, intermittently to form dots on a print target medium. In the medium transportation processing, the printer 1 transports the print target medium in the transportation direction to change the position of the print target medium relative to the position of the head 41. The medium transportation processing is an example of transportation operation according to an aspect of the invention. The repeated operation explained above makes it possible to form dots at a certain position (i.e., area) on a print target medium that is not the same as a position where dots have already been formed thereon as a result of preceding execution of the dot formation processing, thereby forming a two-dimensional image on the print target medium. In this specification, the traveling of the head 41 in the movement direction once while discharging ink droplets is defined as “pass”. The pass corresponds to the execution of the dot formation processing once. The dot formation processing is an example of image formation operation according to an aspect of the invention.
Method for Printing Two Images in Layers
Printed Matter
In the following description, a printed matter that includes a color image that is formed by means of ink of four colors (YMCK) on a white background image is taken as an example of a printed matter that includes two images one of which is printed on the other. Even when an image is printed on a transparent film, such a printed matter prevents the opposite face thereof from being seen therethrough. In addition, such a printed matter makes it possible to print an image having excellent color development property.
If a white background image is printed with the use of white ink only, the color of the white ink determines the color of the background image. Strictly speaking, the colors of ink called roughly as white ink actually differ from one to another. For this reason, in some cases, it is practically impossible to print a desired white image by using white ink only.
In view of the above fact, in the present embodiment of the invention, white ink only is used to print a background image at every area where an overlapping color image will be printed thereon in the entire area of the background image. This area is hereinafter referred to as “overlapping white area”. On the other hand, ink of four colors (YMCK) is used as may be necessary in addition to white ink to print the background image at every area where no overlapping color image will be printed thereon in the entire area of the background image. This area is hereinafter referred to as “non-overlapping white area”. In this way, a desired white background image is printed. The above image formation makes it possible to ensure that the color of the exposed white part of the background image that an observer can see, that is, the color of the non-overlapping white area, is the desired white. Since an observer cannot see the overlapping white area when it is observed from the printed-face side, white ink only is used for printing at the overlapping white area. By this means, it is possible to reduce the amount of consumption of ink. However, the scope of the invention is not limited to such an example. Color ink may be mixed with white ink for printing the non-exposed white part of the background image at the overlapping white area in the same manner as done at the non-overlapping white area.
In this specification, the meaning of the term “white” is not limited to white in its technically strict sense, which is the color of a surface of an object that perfectly reflects visible light of all wavelengths (100%). The term “white” used in this specification has a broader meaning that encompasses colors that are deemed as white from common sense. It includes but not limited to whitish or white-tinged colors. In the following description, the adjustment of white by mixing ink of a certain color(s) other than white in (or with) white ink is referred to as “white adjustment”. The color that is produced as a result of the white adjustment (i.e., white having been subjected to the white adjustment) is referred to as “adjusted white”.
In the present embodiment of the invention, when two images are printed in layers, that is, with one of the two images being printed on the other, both the white ink nozzle line W and the four-color ink nozzle line YMCK are used to print a background image having the color of adjusted white at a certain area of the print target medium S in a preceding set of passes. Thereafter, the four-color ink nozzle line YMCK only are used to print a color image on the background image at the same area in a succeeding set of passes. The white ink nozzle line W is an example of a first nozzle line according to an aspect of the invention. The four-color ink nozzle line YMCK is an example of a second nozzle line according to an aspect of the invention. In this way, the color image is printed on the background image. In the following description, the yellow ink nozzle line Y, the magenta ink nozzle line M, the cyan ink nozzle line C, and the black ink nozzle line K are collectively referred to as “color nozzle line Co”. The white ink nozzle line is referred to as “white nozzle line W”.
Printing Method without Drying Pass
When printing is performed near the upper edge of a print target medium or the lower edge thereof, the number of nozzles from which ink droplets are discharged is usually changed. Alternatively, or in addition thereto, the amount of transportation of the print target medium is changed.
To print a color image in a succeeding set of passes after the printing of a background image at the same area on a print target medium, one half of nozzles belonging to the white nozzle line W at the upstream side in the transportation direction (nozzles #13 to #24) are set as nozzles from which ink droplets are discharged (hereinafter referred to as “active ejection nozzles”), whereas the other half of nozzles belonging to the white nozzle line W at the downstream side in the transportation direction (nozzles #1 to #12) are set as nozzles from which no ink droplet is discharged (defined as “inactive nozzles”). On the other hand, one half of nozzles belonging to the color nozzle line Co at the downstream side in the transportation direction (nozzles #1 to #12) are set as active ejection nozzles used for printing the color image, whereas the other half of nozzles belonging to the color nozzle line Co at the upstream side in the transportation direction (nozzles #13 to #24) are set as active ejection nozzles used in combination with the nozzles #13 to #24 belonging to the white nozzle line W for printing the background image.
Since the active ejection nozzles of the color nozzle line Co and the white nozzle line W are set as explained above, a certain area of a print target medium first arrives at a position where the area faces the active ejection nozzles of the nozzle lines W and Co formed at the upstream side in the transportation direction (nozzles #13 to #24). As a result, a background image having the color of adjusted white is printed thereat. Thereafter, the above area of the print target medium moves downstream due to transportation to face the active ejection nozzles of the color nozzle line Co formed at the downstream side in the transportation direction (nozzles #1 to #12). As a result, a color image is printed on the background image.
In the illustrated example of
As described above, the printer 1 performs image formation operation by discharging ink droplets from the twelve upstream active ejection nozzles of the white nozzle line W, the twelve upstream active ejection nozzles of the color nozzle line Co, and the twelve downstream active ejection nozzles of the color nozzle line Co. The printer 1 performs transportation operation in which a print target medium is transported by unit amount that is four times as large as the nozzle pitch d (i.e., 4d). The image formation operation and the transportation operation are repeated alternately. By this means, the printer 1 can print a background image in a preceding set of three passes and print a color image on the background image in a succeeding set of three passes.
In the right part of
In the illustrated example of
To dry background well, it is possible to set one or more passes in which image formation operation is not performed (hereinafter referred to as “drying pass”) during time from the end of the printing of a background image to the start of the printing of a color image by setting some nozzles from which no ink droplet is discharged (hereinafter referred to as “drying nozzle”) between active ejection nozzles for the color image and active ejection nozzles for the background image. A more detailed explanation thereof will be given later. However, in a case where white ink and color ink that are ejected before the printing of a color image have excellent drying property or where a print target medium has excellent ink-absorbing property, a background image dries easily. Therefore, it is not necessary to set long drying time in such a case. If long drying time is not necessary, as illustrated in
Printing Method with Drying Pass According to Comparative Example
In a case where white ink and color ink that are ejected before the printing of a color image have poor drying property or where a print target medium has poor ink-absorbing property, a background image does not dry easily. In such a case, if the printing of a color image is started in the next pass immediately after the completion of the printing of a background image in a certain pass as done in the printing method illustrated in
In addition, the remaining four nozzles (#10 to #13), which are located upstream of the nine nozzles (#1 to #9) for printing a color image (color nozzle line Co) in the transportation direction and downstream of the nine nozzles (#14 to #22) for printing a background image (white nozzle line W, color nozzle line Co) in the transportation direction, are set as drying nozzles (i.e., nozzles from which no ink droplet is discharged) in each of the nozzle lines W and Co. The drying nozzle is denoted as a cross (×) in the drawing. In other words, the nozzles (#10 to #13) located between the active ejection nozzles for a color image (#1 to #9) and the active ejection nozzles for a background image having the color of adjusted white (#14 to #22) in a nozzle line (#1 to #22) are set as drying nozzles. With the above nozzle configuration, it is possible to set a drying pass (passes), that is, a pass in which image formation operation is not performed, during time from the end of the printing of the background image to the start of the printing of the color image. The drying pass makes it possible to prevent ink used for printing the color image from running on the background image, which would otherwise deteriorate image quality.
Printing operation is explained below. A certain area of a print target medium first arrives at a position where the area faces the active ejection nozzles of the white nozzle line W and the color nozzle line Co formed at the upstream side in the transportation direction (denoted as white circles and shaded circles, respectively). As a result, a background image is printed thereat. Then, the above area of the print target medium moves downstream due to transportation to face the drying nozzles (denoted as crosses). Therefore, no ink droplet is discharged onto the background image at this position. The background image dries during this time period. Thereafter, the above area of the print target medium moves downstream due to transportation to face the active ejection nozzles of the color nozzle line Co formed at the downstream side in the transportation direction (denoted as black circles). As a result, a color image is printed on the background image.
In a printing method according to the above comparative example, printing for three raster lines is completed at each execution of transportation operation. The nozzles enclosed by thick lines in the right part of
As will be understood by referring to the nozzles shown inside the thick lines in the right part of
In a printing method according to the above comparative example, the transportation amount of a print target medium in each execution of transportation operation is equal to the width of an image formed by means of three nozzles, which is three times as large as the nozzle pitch d, that is, 3d (three quadrangular cells). On the other hand, the number of drying nozzles in a nozzle line is set as four. In addition, the length of a dry area, which means a nozzle area where the drying nozzles are located, in the transportation direction is four times as great as the nozzle pitch d, that is, 4d (four quadrangular cells). For this reason, the number of times of drying-pass execution could differ from one raster line to another. That is, in the above comparative example, the length of the nozzle area where the drying nozzles are located (i.e., the length of a line of nozzles that are not used for forming an image) in the transportation direction, which is 4d, is not an integral multiple of the transportation amount of a print target medium in each execution of transportation operation, which is 3d (×4/3).
In
A case where a difference in the number of times of drying-pass execution (i.e., the length of time for drying a background image) depending on raster line arises is not limited to the above example. Though not illustrated in the drawing, it differs depending on raster line in a case where the number of drying nozzles is smaller than the number of nozzles corresponding to amount by which the positions of nozzles relative to the position of the print target medium are shifted in each execution of transportation operation (e.g., in a case where the length of the nozzle area where the drying nozzles are located in the transportation direction is one third or two thirds of transportation amount). For example, let the number of drying nozzles be two. Let the number of nozzles corresponding to amount by which the positions of nozzles relative to the position of a print target medium are shifted in each execution of transportation operation be three. In this example, when a certain area of a print target medium on which a background image has been printed moves downstream due to transportation by the transportation amount corresponding to three nozzles, though the upstream part of the area of the print target medium faces the two drying nozzles, the downstream part of the area thereof faces an active ejection nozzle of the color nozzle line Co for printing a color image without facing either of the two drying nozzles. Therefore, the same image contains a part printed with a drying pass and a part printed without a drying pass, which causes non-uniformity in the depth of shade.
To sum up, in a printing method according to the above comparative example, since the length of a nozzle area where drying nozzles are located in the transportation direction (or the number of the drying nozzles) is not an integral multiple of the unit transportation amount of a print target medium (or the number of nozzles corresponding to amount by which the positions of nozzles relative to the position of the print target medium are shifted in each execution of transportation operation), the length of time for drying a background image (i.e., the number of times of drying-pass execution) is not constant. For this reason, the depth of shade of an image obtained will not be uniform. In view of the above, the present embodiment of the invention aims to make time from the end of the printing of a background image to the start of the printing of a color image at a certain area of a print target medium (the length of time for drying the background image, the number of times of drying-pass execution) constant.
Printing Method with Drying Pass According to Present Embodiment of the Invention
In addition, in order to set a drying pass during time from the end of the printing of the background image to the start of the printing of the color image, the remaining three nozzles (#10, #11, and #12), which are located upstream of the active ejection nozzles (#1 to #9) of the color nozzle line Co for printing the color image in the transportation direction and downstream of the active ejection nozzles (#13 to #21) of the white nozzle line W and the color nozzle line Co for printing the background image in the transportation direction, are set as drying nozzles (i.e., nozzles from which no ink droplet is discharged) in each of the nozzle lines W and Co. That is, the length of the nozzle area where the drying nozzles are located in the transportation direction corresponds to three nozzles, which is three times as great as the nozzle pitch d, that is, 3d (three quadrangular cells). To sum up, in a printing method according to the present embodiment of the invention, the length of the nozzle area where the drying nozzles are located in the transportation direction, 3d, is equal to (which is a kind of an integral multiple of) the transportation amount of a print target medium in each execution of transportation operation, 3d. In other words, the number of the drying nozzles (three) is an integral multiple of (equal to, ×1) the number of nozzles corresponding to amount by which the positions of nozzles relative to the position of a print target medium are shifted in each execution of transportation operation (three).
Printing operation according to the present embodiment of the invention is explained below. A certain area of a print target medium (e.g., an area where three raster lines will be formed) moves downstream due to transportation by the transportation amount corresponding to three nozzles at a time. In each pass, the area faces three of the active ejection nozzles set for the background image (#13 to #24). Three passes complete the printing of the background image. In the next transportation operation, the area moves downstream to face the three drying nozzles (#10, #11, and #12). The background image dries during this time period. Thereafter, the area moves downstream due to transportation to face three of the active ejection nozzles set for the color image (#1 to #9) in each pass. Three passes complete the printing of the color image. By this means, it is possible to make the number of times of drying-pass execution at the above area of the print target medium during time from the end of the printing of the background image to the start of the printing of the color image constant. That is, drying pass is executed once in a uniform manner. Thus, it is possible to prevent the number of times of drying-pass execution from being different from one raster line to another.
For example, the nozzles arranged in the movement direction inside the thick lines in the right part of
As explained above, in a printing method according to the present embodiment of the invention, the length of a nozzle area where drying nozzles are located in the transportation direction (or the number of the drying nozzles), which is 3d, is an integral multiple of the unit transportation amount of a print target medium (or the number of nozzles corresponding to amount by which the positions of nozzles relative to the position of the print target medium are shifted in each execution of transportation operation), which is 3d. More specifically, in the illustrated example of
In
In contrast, in
For this reason, as illustrated in
For example, a certain area of a print target medium where three raster lines will be formed moves downstream due to transportation by the transportation amount corresponding to three nozzles at a time. The area faces the active ejection nozzles set for the background image (◯) (W and Co) in three passes. As a result of the next transportation operation, the downstream part of the area faces the drying nozzles (×), whereas the upstream part of the area faces an active ejection nozzle set for the background image (◯) again. That is, the background image is printed in three passes at the downstream part of the area, whereas the background image is printed in four passes at the upstream part of the area. As explained above, if the length of a nozzle area where active ejection nozzles are located in the transportation direction is not an integral multiple of the transportation amount of a print target medium, the number of passes for printing an image (a background image or a color image) differs depending on raster line.
If the number of passes for printing an image in some raster lines is different from that in other raster lines, complex processing for assigning dots for raster-line formation to passes (nozzles) is required when print data is created. For the purpose of further explanation, it is assumed that no ink droplet is discharged from the nozzle corresponding to the pass X+5 among four color-image nozzles in the group of nozzles that form the raster line L2 shown in
To avoid the above disadvantages, it is preferable that not only the length of a nozzle area where drying nozzles are located in the transportation direction but also the length of a nozzle area where active ejection nozzles for forming a background image or a color image are located in the transportation direction should be an integral multiple of the unit transportation amount of a print target medium. With such a preferred configuration, the number of passes for forming each of the images becomes constant.
In order to make the length of background drying time greater than that of the printing method illustrated in
As the nozzles arranged in the movement direction inside the thick lines in the right part of
When a plurality of images is printed in layers, time required for drying a lower-layer image differs depending on the drying property of ink ejected before the printing of an upper-layer image or the ink-absorbing property of a print target medium. Therefore, it is preferable to change the number of drying nozzles depending on the property of ink or the property of a print target medium, that is, depending on the drying characteristics of an image formed on the print target medium. For example, to lengthen time for drying a background image, the number of drying nozzles is increased, which increases the number of times of drying-pass execution. In other words, it is preferable to change the ratio of the length of a nozzle area where drying nozzles are located in the transportation direction (6d in
As explained above, it is possible to lengthen time for drying a background image by increasing the number of drying nozzles, thereby avoiding deterioration in image quality due to the running of ink reliably. However, since the number of nozzles that belong to a nozzle line is predetermined (one hundred and eighty in
For example, in
Method for Printing Three Images in Layers
In
With the above nozzle configuration, the background image is printed in the first set of two passes. The color image is printed in the next set of two passes. The clear ink image is printed in the last set of two passes. In
In this example, it is assumed that the background image is harder to dry than the color image. Therefore, it is desired to set the length of background drying time longer than the length of color drying time. In other words, it is desired to set the number of times of drying-pass execution during time from the end of the printing of the background image to the start of the printing of the color image larger than that during time from the end of the printing of the color image to the start of the printing of the clear ink image at a certain area of a print target medium.
In order to set the length of background drying time longer than the length of color drying time, the nozzles are configured as follows. The number of drying nozzles set between the active ejection nozzles for the background image (denoted as white circles and shaded circles) and the active ejection nozzles for the color image (denoted as black circles), which is eight (=eight quadrangular cells), is twice as large as the number of nozzles corresponding to the unit transportation amount 4d, which is four (=four quadrangular cells). The number of drying nozzles set between the active ejection nozzles for the color image (denoted as black circles) and the active ejection nozzles for the clear ink image (denoted as triangles), which is four (=four quadrangular cells), is equal to the number of nozzles corresponding to the unit transportation amount 4d, which is four. That is, the number of the drying nozzles set between the active ejection nozzles for the background image and the active ejection nozzles for the color image is larger than the number of the drying nozzles set between the active ejection nozzles for the color image and the active ejection nozzles for the clear ink image.
With the above nozzle configuration, a certain area of a print target medium faces drying nozzles in two passes after the printing of a background image. Thereafter, the area faces drying nozzles in one pass after the printing of a color image. In this way, it is possible to set the number of times of drying-pass execution after the printing of the background image (i.e., twice) larger than that after the printing of the color image (i.e., once). This will be understood by referring to the nozzles arranged in the movement direction inside the thick lines in the right part of
If the length of drying time (the number of times of drying-pass execution) is not constant after the printing of an image (which is a background image in
Method for Printing Four Images in Layers
In
It is assumed that each of the background image and the text image has poor drying characteristics, whereas the color image has excellent drying characteristics. In view of the above drying characteristics, six drying nozzles (for each nozzle line) are set between the active ejection nozzles for the background image in the white nozzle line W and the color nozzle line Co (YMCK) and the active ejection nozzles for the three-color image in the three-color nozzle line (YMC). In addition, six drying nozzles are set between the active ejection nozzles for the text image in the black nozzle line K and the active ejection nozzles for the clear ink image in the clear ink nozzle line (C1).
No drying nozzle is set between the active ejection nozzles for the three-color image and the active ejection nozzles for the text image. That is, the interval between the downstream-end one of the active ejection nozzles for the three-color image (denoted as a black circle) and the upstream-end one of the active ejection nozzles for the text image (denoted as a black square) is set as the nozzle pitch d. Therefore, drying pass is executed twice after the printing of each of the background image and the text image at a certain area of a print target medium. The text image is printed immediately after the printing of the three-color image without any drying pass. Likewise the foregoing embodiments, in
As explained above, when three or more images are printed in layers, drying pass may be executed after the printing of some kinds (or a certain kind) of image (e.g., a background image and a text image), whereas drying pass may be omitted after the printing of another kind (or the other kinds) of image (e.g., a color image). By this means, it is possible to avoid deterioration in image quality due to the running of ink reliably and shorten printing time as much as possible.
Background Image Having Color of Adjusted White
In the foregoing description, it is explained that drying nozzles are set between active ejection nozzles for a background image having the color of adjusted white and active ejection nozzles for a color image when the color image is printed with the use of color ink on the background image printed with the use of white ink and the color ink (CMYK). Next, processing for setting adjusted white to output desired white by mixing color ink with white ink is explained below. In addition, processing for creating print data is explained. The print data is used for printing a background image having the color of adjusted white. A printer driver installed in the computer 60, which is connected to the printer 1 as an external device, performs the processing explained below.
Processing for Setting Adjusted White
In the adjusted white setting window W1 illustrated in
In the adjusted white setting window W1, the value input boxes Bo1 are fields for setting “adjusted white” by inputting color coordinate values L*, a*, and b* in a L*a*b* color coordinate system and a T value therein. The color coordinate values L*, a*, and b* may be hereinafter denoted simply as L (L value), a (“a” value), and b (“b” value), respectively. The L value is a value that indicates the luminosity of adjusted white. The L value correlates with the amount of black ink (K) used when an image having the color of adjusted white is printed. The “a” and “b” values are values that indicate the chromaticity of adjusted white along a red-green axis and a yellow-blue axis, respectively. Each of these two values correlates with the amount of color ink (YMC) used when an image having the color of adjusted white is printed. The T value is a value that indicates the depth of shade (density). The T value correlates with the amount of ink used per unit area when an image having the color of adjusted white is printed. That is, the T value correlates with background color transmittance. A user can set adjusted white corresponding to the Lab values and the T value by operating the slider bars Sl1 and Sl2 and making adjustment in the a-b plane display area Pl instead of setting these values numerically.
The order-of-printing setting box Se1 in the adjusted white setting window W1 is a box for setting a print order as demanded by the application program. To simplify explanation, a box for setting the sequential order of printing two images in layers is taken as an example. In the foregoing description, it is explained that a background image having the color of adjusted white is printed first by using white ink and color ink (YMCK), followed by the printing of a color image on the background image by using the color ink. The foregoing printing scheme is called as surface printing. Surface printing is shown as “W-C print” in
When a user inputs values in the value input boxes Bo1, the color displayed in the sample image display area Sa changes into a color (adjusted white) that is specified by the input values. For example, when the user changes the a or b value (or a and b values), the hue (i.e., “color”) of the color displayed in the white image area of the sample image display area Sa changes. When the user changes the L value, the luminosity of the color displayed in the white image area of the sample image display area Sa changes. Since background color transmittance changes when the T value is changed, the luminosity of the color displayed in the white image area in the black background area of the sample image display area Sa changes, whereas the color displayed in the white image area in the white background area thereof does not change. Therefore, a user can easily recognize a change in color corresponding to the T value (density value) by comparing the black background area of the sample image display area Sa with the white background area thereof. Thus, the user can set adjusted white precisely and easily. When the color displayed in the white image area of the sample image display area Sa agrees with white that the user desires, they depress the OK button B2.
By this means, the printer driver can acquire values (the Lab values and the T value) related to the color of a user-desired adjusted white image. Incidentally, an image having the color of adjusted white may be actually printed on the basis of values (the Lab values and the T value) set by a user to carry out the color measurement of the printed image. On the basis of the result of measurement, the user can adjust values (the Lab values and the T value) related to the color of an adjusted white image more precisely and easily.
Processing for Creating Print Data
Next, the printer driver performs color conversion processing, ink color separation processing, and halftone processing for an adjusted white image. As a first step of print data creation processing, the printer driver performs the color conversion processing. In the color conversion processing, the Lab values set in the processing for setting adjusted white explained above are converted into YMCK values. To perform the color conversion processing, the printer driver looks up a table for an adjusted white image (hereinafter referred to as “adjusted white image lookup table”) LUTw1, which is not illustrated in the drawing. Lab values and YMCK values are pre-stored in association with each other in the adjusted white image lookup table LUTw1. That is, the adjusted white image lookup table LUTw1 contains correspondence therebetween. In the adjusted white image lookup table LUTw1, the tone value of each of Y, M, C, and K is set as a value that is not smaller than zero and not larger than one hundred (i.e., as a comparatively subtle color).
Next, the printer driver performs the ink color separation processing. The ink color separation processing is processing for converting a combination of the YMCK values, which have been obtained from the Lab values of the adjusted white image as a result of the color conversion explained above, and the T value into a tone value for each of ink colors. The printer 1 according to the present embodiment of the invention can use ink of five colors, which is cyan C, magenta M, yellow Y, black K, and white W, for printing. Therefore, in the ink color separation processing, a combination of the YMCK values and the T value is converted into a tone value for each of these five ink colors (YMCKW).
To perform the ink color separation processing, the printer driver looks up another adjusted white image lookup table LUTw2, which is not illustrated in the drawing. The adjusted white image lookup table LUTw2 contains correspondence between a combination of the YMCK values and the T value and a tone value for each of the five ink colors (YMCKW). In the adjusted white image lookup table LUTw2, the tone value for each of the five ink colors (YMCKW) is set as a value that is not smaller than zero and not larger than two hundred and fifty-five (i.e., in a 256 tone-value range).
Next, the printer driver performs the halftone processing for converting continuous tone data (i.e., 256 “high tone” data) into dot ON/OFF data that the printer 1 can reproduce (hereinafter referred to as “dot data”). For example, the printer driver performs the halftone processing as follows. A tone value for each ink color for a pixel (high tone data) is taken out. The value taken out is converted into low tone data (i.e., dot data) with reference to a dither pattern for each ink color.
As done for an adjusted white image, the printer driver performs the ink color separation processing and the halftone processing for a color image (YMCK image). The printer driver looks up a color image lookup table, which is not illustrated in the drawing. While referring to the table, the printer driver converts color image data into a tone value of each color of ink that the printer 1 can use (YMCK). For example, if color image data that the printer driver has received from the application program is RGB data, the printer driver performs the ink color separation processing to convert the RGB data into YMCK data. Then, the printer driver performs the halftone processing for the YMCK data for a color image, thereby converting high tone data into dot data.
As a result of the above processing, the printer driver obtains dot data for printing an image (background image) having the color of adjusted white (YMCKW) and dot data for printing a color image (YMCK). The printer driver sends the dot data obtained as explained above to the printer 1 together with other command data (e.g., ink type, order of printing, and the like).
Processing of Printer 1
The controller 10 stores dot data related to a color image in the color image raster buffer 132c. The controller 10 stores dot data related to a white image (adjusted white image, background image) in the white image raster buffer 132w. As illustrated in
The head buffer is shown at the lower part of
Each area in the head buffer is subdivided into an upstream sub area (142u) and a downstream sub area (142l). As illustrated in
To perform printing for a certain area part of image data (e.g., an area corresponding to one pass), as a first step, the controller 10 stores dot data corresponding to the area into the raster buffer for each ink color. Thereafter, the controller 10 transfers the data stored in the raster buffer to the head buffer in synchronization with print timing. Then, the controller 10 controls the head 41 to discharge ink droplets from each of the nozzle lines (YMCKW) for printing an image on the basis of the dot data, which is stored in the head buffer. After transferring the stored dot data to the head buffer, the controller 10 stores new dot data into the raster buffer until printing is completed while using all dot data.
In the present embodiment of the invention, after the printing of a background image having the color of adjusted white by using a mixture of white ink (W) and color ink (YMCK), a color image is printed on the background image by using the color ink (YMCK). For example, as illustrated in
In some cases, a color image is printed first on a print target medium such as a transparent film; thereafter, a background image having the color of adjusted white is printed on the color image. In such a printing scheme, in normal printing, nozzles belonging to the color nozzle line Co at the upstream side in the transportation direction are used to print a color image first. Then, nozzles belonging to each of the white nozzle line W and the color nozzle line Co at the downstream side in the transportation direction are used to print a background image on the color image. Therefore, the controller 10 transfers the dot data stored in the color image raster buffer 132c to the upstream head buffer 142u and transfers the dot data stored in the white image raster buffer 132w to the downstream head buffer 142l.
The foregoing exemplary embodiments of the invention are primarily directed to a printing system that includes an ink-jet printer. However, they also include the disclosure of a method for suppressing (e.g., correcting) non-uniformity in the depth of shade without any limitation thereto. Although the technical concept of the present invention is explained above with the disclosure of exemplary embodiments, the specific embodiments are provided solely for the purpose of facilitating the understanding of the invention. The above explanatory embodiments should not be interpreted to limit the scope of the invention. The invention may be modified, altered, changed, adapted, and/or improved within a range not departing from the gist and/or spirit of the invention apprehended by a person skilled in the art from explicit and implicit description made herein, where such a modification, an alteration, a change, an adaptation, and/or an improvement is also encompassed within the scope of the appended claims. It is the intention of the inventor/applicant that the scope of the invention covers any equivalents thereof. As specific examples, the following variations are encompassed within the scope of the invention.
Printed Matter
In the foregoing embodiments of the invention, a printed matter that includes a background image having the color of adjusted white that is printed by using white ink and color ink is taken as an example. However, the scope of the invention is not limited to such an example. For example, a background image may be printed with the use of ink other than white ink (e.g., color ink or metallic ink); then, the hue (i.e., color) of the background image may be adjusted by means of ink that is used for printing an image on the background image. As another modification example, for the purpose of improving the color reproduction property of an image, both color ink (YMCK) and white ink may be used to print a color image on a background image having the color of adjusted white.
As still another modification example, after the printing of a background image by using white ink only, a color image may be printed on the background image by using the white ink and color ink (YMCK). To produce such a modified printed matter, for example, in normal printing, nozzles belonging to the white nozzle line W at the upstream side in the transportation direction (e.g., nozzles #13 to #21 in
Printing Method
In the foregoing embodiments of the invention, an overlap printing scheme is taken as an example. However, the scope of the invention is not limited to such an example. As an example of other printing schemes, a plurality of raster lines may be formed in different passes between raster lines that are arranged at intervals of nozzle pitch as in interlace printing. In a printing scheme such as band printing in which a print target medium is transported by transportation amount that is equal to the width of an image formed in one pass, for example, nozzles that belong to each of the white nozzle line W and the color nozzle line Co at the upstream side and occupy one third of the nozzle line are set as active ejection nozzles; in addition, nozzles that belong to the color nozzle line Co at the downstream side and occupy one third of the nozzle line are set as active ejection nozzles. In such a printing scheme, since the transportation amount of a print target medium in each execution of transportation operation is equal to one third of the entire length of the nozzle line, the remaining one third of nozzles at the center area of the nozzle line are set as drying nozzles.
Fluid Ejecting Apparatus
In the foregoing embodiments of the invention, an ink-jet printer is explained as an example of a fluid ejecting apparatus. However, the scope of the invention is not limited to such an example. The invention can be applied not only to a printer but also to various industrial apparatuses that eject fluid. Examples of a fluid ejecting apparatus according to aspects of the invention include but not limited to: a textile printing apparatus for patterning textile, a color filter manufacturing apparatus, a display manufacturing apparatus used for manufacturing display devices such as organic electroluminescence (EL) displays, and a DNA chip manufacturing apparatus used for manufacturing DNA chips by applying solution in which DNA is dissolved to chips. A piezoelectric ejection scheme can be used for ejecting fluid. In the piezoelectric ejection scheme, a voltage is applied to driving elements (i.e., piezoelectric elements) to expand and contract ink chambers. The fluid is ejected due to pressure in the ink chambers. Alternatively, a thermal ejection scheme may be used for ejecting fluid. In the thermal ejection scheme, heater elements are used to form air bubbles in nozzles. The fluid is ejected due to the air bubbles. Ultraviolet ray curing ink, which hardens when exposed to ultraviolet rays, may be used as ink ejected from the head 41. When ultraviolet ray curing ink is used, it is preferable to mount a head that ejects the ultraviolet ray curing ink and an irradiator that irradiates the ultraviolet ray curing ink with ultraviolet rays on the carriage 31. The head 41 may eject powder.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-188944 | Aug 2009 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6511144 | Otsuki | Jan 2003 | B2 |
| 7267425 | Kawase et al. | Sep 2007 | B2 |
| Number | Date | Country |
|---|---|---|
| 2002-038063 | Feb 2002 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20110043560 A1 | Feb 2011 | US |
