Patent Application
20100277521
The present invention relates to an ink jet recording apparatus which records an image on recording medium while moving its ink applying means (recording head), which is capable of applying multiple kinds of ink, in a manner to scan the recording medium. It also relates to an ink jet recording method.
An ink jet recording apparatus is superior to a recording apparatus of the other type in that it is capable of recording at a higher density and a higher speed, is lower in cost, and is quieter than the recording apparatus of the other type. It has been commercialized in various forms, for example, an outputting device for various apparatuses, a portable printer, etc. In recent years, there have come to be offered various ink jet recording apparatuses capable of forming a color image with the use of multiple inks different in color.
Generally, an ink jet recording apparatus has: a recording means (recording head) which jets ink in response to recording signals; a carriage on which the recording head and an ink container (or ink containers) are mounted; a conveying means which conveys recording medium; and a controlling means which controls the preceding means. In the case of an ink jet recording apparatus of the serial scan type, an image is formed in steps by the alternate repetitions of the carriage movement and the recording medium movement. Hereafter, the direction of the carriage movement will be referred to as the primary recording scan direction, and the direction of recording medium, which is intersectional to the primary recording scan direction, will be referred to as the secondary scan direction. The carriage of a full-color ink jet recording apparatus carries four or more ink containers, which are different in the color of the ink they contains. Thus, it can output a full-color image by applying, to recording medium, each of the multiple inks independently from the other inks, and/or applying in combination two or more among the multiple inks to generate colors different from the color of any of the multiple inks, on the recording medium.
By the way, in the field of ink jet recording method, it has been known that the order in which inks are applied to recording medium has various effects upon how an intended image will come out on the recording medium. For example, a phenomenon is disclosed in Japanese Laid-open Patent Application 2002-248798 that the chromaticity of an image, that is, tone of an image, is affected by the order in which inks are applied to recording medium. According to this document, in a case where multiple inks, different in color, are applied to a given spot on a sheet of recording medium specifically made for ink jet recording, the earlier in the order in which an ink among multiples inks is applied to the recording medium, the stronger the effects of the ink upon the resulting color of the spot.
Further, in Japanese Laid-open Patent Application 2005-81754, a technology for improving an image in friction resistance is disclosed. According to this technology, an image formed with color inks is improved in friction resistance by applying a liquid coat upon the image after the formation of the image. Here, “friction resistance” means the resistance of an image to the friction which occurs between an image (recording medium) and a nail, cloth, etc., as the image (recording medium) is rubbed by the nail, cloth, etc. The protecting coat of the liquid type is designed to be applied to recording medium after the formation of an image on recording medium. Thus, applying the protective coat of liquid type to recording medium before the formation of an image on the recording medium makes the protective coat of the liquid type reduces the protective coat in effectiveness.
As described above, intentionally changing the order in which inks are applied to recording medium by an ink jet recording apparatus can significantly improve the ink jet recording apparatus in terms of the quality of an image it forms. One of the factors which are essential for the control of the order in which inks are applied to recording medium is the structure of an ink jet head, more specifically, the order in which the multiple columns of nozzles, which are different in the color, or type, of the ink they jet, are arranged.
Generally speaking, in terms of the recording head structure, the color ink jet recording apparatuses of the serial type can be separated into two groups, that is, a vertical arrangement group and a horizontal arrangement group. In the case of the vertical arrangement group, the multiple columns of nozzles of a recording head are aligned in a single line which is parallel to the secondary scan direction, whereas in the case of the horizontal arrangement group, the columns of nozzles of a recording head are arranged in tandem in the direction perpendicular to the secondary scan direction, although each nozzles columns is parallel to the secondary scan direction. Next, the structure of the recording head in each group will be described one by one.
In the case of a recording head structured so that its nozzle columns are aligned in a single line which is parallel to the secondary scan direction, the order in which inks are applied to recording medium can be fixed, but, it is difficult to change the order in response to the circumstantial changes. Further, the multiple nozzle columns, different in ink color or type, are aligned in a single line which is parallel to the secondary scan direction. Therefore, it is likely to be longer in terms of the secondary scan direction than recording heads of the other type. The lengthening of a recording head requires increase in the overall size of an image forming apparatus, and also, requires an image forming apparatus to be provided with a complicated mechanism for keeping recording medium flatly held. In other words, the lengthening of a recording head increases in cost the main assembly of an image forming apparatus, as well as the cost of the recording head itself.
In the case of a recording head, the nozzle columns of which are aligned in a single line perpendicular to the recording medium conveyance direction (horizontal nozzle column arrangement type), each time the recording head is moved in the primary scan direction to recording an image on recording medium, multiple inks which are different in color are applied to the same area of the recording medium. Thus, when the recording head is moved in the outward direction, the inks are applied in the order of yellow→magenta→cyan→black, whereas when the recording head is moved in the return direction, the inks are applied in the opposite order. As described above, the tone of an image to be formed by an ink jet recording apparatus is affected by the order in which inks are applied to recording medium. Thus, the reversal in the ink application order, which occurs each time recording medium is conveyed, is one of the causes of the formation of an image inferior in quality. For example, if a blue image, the color of which is generated by the mixture of cyan and magenta inks, is formed with the use of an ink jet head of this type, the resultant blue image will be made up of multiple alternately positioned horizontal blue strips of two kinds (different in tone), that is, a blue strips generated as cyan and magenta were applied in an order of cyan→magenta, and a blue strips generated as cyan and magenta inks were applied in an order of magenta→cyan. The presence of these alternately positioned blue strips different in toner makes the blue image appear nonuniform in color.
Thus, in order to deal with the above-described problem, an ink jet recording apparatus is generally designed to employ the so-called multi-pass recording method. The multi-pass recording method completes an image in steps by moving a recording head multiple times in the primary scan direction across each portion of recording medium, while thinning the image data recordable per primary scan, with the use of mask patterns prepared in advance.
The employment of a multi-pass recording method, such as the one described above, makes it possible to make the cells of each mask pattern different in recording permission ratio, for each color, even when a recording head, the nozzle columns of which are arranged in tandem and in parallel, is used (specification of U.S. Pat. No. 6,779,873). Further, it makes it possible to control to some degrees the order in which inks are applied to recording medium, as it is possible when an ink jet recording apparatus, the nozzle columns of which are aligned in a single line, is used.
Disclosed in Japanese Laid-open Patent Application 2004-209943 is a technology for changing the nozzle usage ratio of a recording head according to the recording duty of image data. The method disclosed in this patent application also can control the order in which inks are applied in layers, according to recording duty.
As described above, by preparing multi-pass recording masks in advance according to various usages, it is possible to properly control the order in which inks are applied to recording medium, even in a case where the ink jet recording apparatus used for a recording operation employs a recording head structured so that its nozzles columns are arranged in tandem and in parallel.
However, in a case where mask patterns, such as those shown in
As described above, in the case of any of the conventional structures for an ink jet recording head, the multiple passes are fixed in the recording permission ratio for each ink, and therefore, the above described unevenness was unnecessary large.
The present invention is made in consideration of the above-described problems. Thus, its primary object is to control the order in which a specific ink and the other inks are applied in layers, while preventing the unevenness, in terms of the recording permission ratio for a specific ink, among the multiple recording passes from becoming unnecessarily large.
In order to accomplish the object, the present invention provides an ink jet recording apparatus capable of effecting recording onto a unit pixel of a recording material by a plurality of scannings of ink applying means for applying inks including a specific ink, said ink jet recording apparatus comprising determining means for determining a recording permission ratio of the specific ink onto the unit pixel in response to information relating to the specific ink and at least one of the inks other than the specific ink to be applied to the unit pixel.
In addition, there is provided an ink jet recording apparatus capable of effecting recording onto a unit pixel of a recording material by a plurality of scannings of ink applying means for applying inks including a specific ink, said ink jet recording apparatus comprising processing means capable of executing process for making higher a recording permission ratio of the specific ink to be applied to the unit pixel in at least one of a latter part scanning and a final scanning of the plurality of scannings than a recording permission ratio of the ink other than the specific ink, on the basis of information relating to the specific ink to be applied to the unit pixel and the ink other than the specific ink.
In addition, there is provided an ink jet recording apparatus capable of effecting recording onto a unit pixel of a recording material by a plurality of scannings of ink applying means for applying inks including a specific ink, said ink jet recording apparatus comprising processing means capable of executing process for making higher a recording permission ratio of the specific ink to be applied to the unit pixel in at least one of an early part scanning and an initial scanning of the plurality of scannings than a recording permission ratio of the ink other than the specific ink, on the basis of information relating to the specific ink to be applied to the unit pixel and the ink other than the specific ink.
In addition, there is provided an ink jet recording apparatus capable of effecting recording onto a unit pixel of a recording material by a plurality of scannings of ink applying means for applying inks including a specific ink, said ink jet recording apparatus comprising determining means for determining a recording permission ratio of the specific ink onto the unit area on the basis of RGB information corresponding to the unit pixel, for each scanning.
In addition, there is provided an ink jet recording method for effecting recording onto a unit pixel of a recording material by a plurality of scannings of ink applying means for applying inks including a specific ink, said ink jet recording method comprising determining step of determining a recording permission ratio of the specific ink onto the unit pixel in response to information relating to the specific ink to be applied to the unit pixel and at least one of the inks other than the specific ink; and a control step of controlling application of the specific ink onto the unit pixel on the basis of the recording permission ratio determined in said determining step.
In addition, there is provided an ink jet recording method for effecting recording onto a unit pixel of a recording material by a plurality of scannings of ink applying means for applying inks including a specific ink, said ink jet recording method comprising discriminating step of discriminating as to whether to execute process for making higher a recording permission ratio of the specific ink to be applied to the unit pixel in at least one of a latter part scanning and a final scanning of the plurality of scannings than a recording permission ratio of the ink other than the specific ink, on the basis of information relating to the specific ink to be applied to the unit pixel and the ink other than the specific ink; and a control step of controlling application of the specific ink onto the unit pixel on the basis of the result of discrimination of said discrimination step.
In addition, there is provided an ink jet recording method for effecting recording onto a unit pixel of a recording material by a plurality of scannings of ink applying means for applying inks including a specific ink, said ink jet recording method comprising discriminating step of discriminating as to whether to execute process for making higher a recording permission ratio of the specific ink to be applied to the unit pixel in at least one of an early part scanning and an initial scanning of the plurality of scannings than a recording permission ratio of the ink other than the specific ink, on the basis of information relating to the specific ink to be applied to the unit pixel and the ink other than the specific ink; and a control step of controlling application of the specific ink onto the unit pixel on the basis of the result of discrimination of said discrimination step.
In addition, there is provided an ink jet recording apparatus capable of effecting recording onto a unit pixel of a recording material by a plurality of scannings of ink applying means for applying inks including a specific ink, said ink jet recording apparatus comprising processing means capable of executing a process for changing a ratio of the specific ink applied onto the unit pixel in a scanning later than application of the ink other than the specific ink onto the unit pixel, in accordance with information relating to the specific ink and the ink other than the specific ink to be applied to the unit pixel to be applied to the unit pixel.
Hereafter, the preferred embodiments of the present invention will be described in detail. First, the characteristics of the preferred embodiments will be simply described. One of the characteristics of the embodiments of the present invention, which will be described later, is that when setting the ratio with a specific ink is permitted to be applied during each of the multiple recording passes for a unit pixel, not only the information regarding the specific ink, but also, the information regarding at least one of the inks other than the specific ink, are taken into consideration. That is, the ratio with which the specific ink is applied per unit pixel is set based on the information regarding the specific ink and nonspecific inks to be applied to the unit pixel (for example, CMYK information, RGB information, etc.). Thus, the primary recording scan, during which the specific ink is applied in concentration is changeable (modifiable), based on the conditions under which the specific ink and nonspecific inks are applied. Therefore, it is possible to change the ratio with the specific ink is applied before the recording pass(es) during which the other inks are applied, and the ratio with which the specific ink is applied after the recording pass(es) during which the other inks area applied. Therefore, it becomes possible to control the order in which the specific ink and the other ink(s) are applied in layers. In the preferred embodiments of the present invention, which will be described next, image processing steps for changing the ratio with which the specific ink is applied to each unit pixel during a relatively later primary recording pass than the primary recording passes during which the nonspecific inks are applied to the unit pixel, are carried out.
It is preferable that the decision regarding the recording permission ratio is made in accordance with the selection made regarding the “recording permission ratio setting pattern”. “Recording permission ratio setting pattern” means the pattern for selecting recording permission ratio for a specific ink, for each of unit pixels. Hereafter, for convenience sake, this recording permission ratio setting pattern will be referred to as “mask pattern”. As the recording permission ratio setting pattern, there are a set of binary mask patterns used in the first preferred embodiment, a set of multi-value mask patterns (for example, mask patterns in
In the preferred embodiments which will be described later, one mask pattern is selected among the multiple mask patterns, which are different in the recording permission ratio for at least the latter half of the multiple recording scan, or the last recording scan. To describe in more detail, a parameter (mask selection parameter MP, MP′, etc.) for selecting one mask pattern among these multiple mask patterns is obtained based on the above described information regarding specific and nonspecific inks. Then, one of the patterns is selected based on the selection parameter obtained as described above. It is by the mask pattern selection, such as the above-described one, that the ratio with which a specific ink is permitted to be recorded during each primary recording scan. Incidentally, in the fifth embodiment, the RGB information regarding each unit pixel is used as the indirect information regarding the specific and nonspecific inks applied to the unit pixel. In the fifth embodiment, therefore, the abovementioned recording permission ratio for the specific ink is set based on the RGB information regarding each of the unit pixels.
It is preferable that the selected parameter, described above, is related to the relationship between the amounts A and B (densities) by which a specific ink and nonspecific ink(s) are applied to each unit pixel, in particular, the ratio (A/B) of the amount A by which the specific ink is applied, and the amount B by which the nonspecific ink(s) is applied. For example, it is desired that there is such a relationship between the selected parameter, described above, and the above described ratio, that the smaller the above described ratio, which is set based on the abovementioned information regarding the specific and nonspecific ink(s), the higher the selected pattern in the recording permission ratio of the specific ink, at least during the latter half of the multiple primary scans, or during the last recording scan of the multiple primary scans. With the presence of this relationship, it is possible to set the recording permission ratio for the specific ink so that the smaller the abovementioned ratio (the more dominant the nonspecific ink(s)), the higher the recording permission ratio for the specific ink during the latter half of the multiple recoding scans or the last of the multiple recording scan.
Further, another characteristic of the preferred embodiments which will be described next is that whether or not the process for making the recording permission ratio for the specific ink higher than the recording permission ratio for the nonspecific inks during at least the latter half, or the last, of the multiple recording scans, is to be carried out, is determined based on the information, such as the above described one, regarding the information regarding the specific and nonspecific inks to be applied to each of the unit pixels. With the employment of this characteristic feature, it is possible to increase the ratio with which the specific ink is applied during the later primary recording scan(s) than the primary recording scan(s) for the nonspecific ink(s).
Incidentally, there are cases in which it is more effective to apply a specific ink so that the specific ink is applied more during the front half of the multiple primary recording scans, or the last of the multiple primary recording scans, that is, the opposite of the above described arrangement. In such cases, it is necessary to carry out a process for increasing, as necessary, the ratio with which the specific ink is permitted to be applied during the front half of the multiple primary recording scans, or the first of the multiple primary recording scans. For this purpose, it is preferable to prepare multiple sets of mask patterns, which are different in the ratio with which the specific ink is permitted to be applied at least during the front half of the multiple primary recording scans, or during the last of the multiple recording scans, so that one of the mask pattern can be selected from among the multiple masks different in pattern. Obviously, it is also the information regarding the specific and nonspecific inks applied to each unit pixel that is used as the information for selecting the mask pattern. In the case of the structural setup of this type, it is preferable that the pattern is selected so that the smaller the ratio (=A/B) of the amount A by which the specific ink is applied, to the amount B by which the nonspecific ink(s) is applied, the higher the selected pattern, in the ratio with which the specific ink is permitted to be applied at least during the front half of the multiple primary recording scans, or the last of the multiple primary recording scans.
It is also desirable that whether or not to carry out the process for making the recording permission ratio for the specific ink higher than that for the nonspecific inks at least during the front half of the multiple primary recording scans, or the last of the multiple primary recording scans, is determined based on the information such as those described above. By making decision based on the above described information, it is possible to increase, as necessary, the ratio with which the specific ink is applied during the prior primary recording scan(s) to the primary recording scan(s) for the nonspecific ink(s).
Incidentally, in a case where the number of the primary recording scans in the latter (or front) half of the multiple primary recording scans is one, the “recording permission ratio during the latter (or front) half of the primary recording scans” means the recording permission ratio for this one and only primary recording scans. Further, in a case where the number of the primary recording scans in the latter (or front) half of the multiple primary recording scans is two or more, the “recording permission ratio during the latter (or front) half of the primary recording scans” means the sum or average value of the two or more recording permission ratios which correspond, one for one, to the multiple primary recording scans in the latter half (or front half) of the multiple scans. Further, “the recording permission ratio for the specific ink in the last (or first) primary recording scan” means the recording permission ratio for the specific ink, for the last (or first) primary recording scan.
As a recording operation start command is inputted from a host apparatus externally connected to the ink jet recording apparatus, one of the sheets of recording medium stored in layers in a sheet feeder tray 15 is fed to the position where an image can be recorded on the sheet of recording medium by the recording head on the carriage 11. Then, an intended image is formed, in sequential parallel strips, on the sheet of recording medium, by the alternate repetitions of the movement which the recording head makes in the primary scan direction while jetting ink according to the binary image formation data, and the conveyance of the recording medium by a preset amount.
The ink jet recording apparatus is provided with a recovery means 14 for carrying out the maintenance operation for the recording head. The recovery means 14 is located at one end of the moving range of the carriage 11. It is provided with: a cap 141 for suctioning ink through the nozzles and protecting the recording head surface where the nozzles open, while the ink jet recording apparatus is left unused; an ink catcher 142 for catching the image protection liquid jetted during a recording head performance (ink jetting performance) restoration operation; an ink catcher 143 for catching the inks jetted during the recording head performance (ink jetting performance) restoration operation; etc. A wiper blade 144 wipes the recording head surface having the nozzle openings while moving in the direction indicated by an arrow mark.
Designated by a referential number 306 is the externally connected host apparatus, which transfers the information of an image (to recorded), to the ink jet recording apparatus in this embodiment. As for the form of the host apparatus 306, the host apparatus 306 may be a computer as an information processing apparatus, or an image reader. Designated by a referential number 307 is a reception buffer for temporarily store the data from the host apparatus 306. The reception buffer 307 stores the received data until the data are read by the system controller 301.
Designated by referential numbers 308 (308k, 308c, 308m, and 308y) are frame memories for developing the nonbinary image data transferred from the reception buffer 307, into binary image data. The frame memory 308 is large enough in capacity to store image data for each ink. In this embodiment, the frame memory 308 is large enough to store the image data equivalent to a single sheet of recording medium. Needless to say, the frame memory 308 is not limited in size. Designated by referential numbers 309 (309k, 309c, 309m, and 309y) are buffers for temporarily storing the binary image data for each ink. The storage capacity of the buffers 309 corresponds to the nozzle count of the recording head.
Designated by a referential number 310 is a recording operation controlling portion, which controls the recording head 17, in recording speed, recording data count, etc., in response to the commands from the system controller 301. Designated by a referential number 311 is a recording head driver, which is controlled by the signals from the recording operation controlling portion 310. The recording head driver 311 actuates the recording head 17 in order to make the recording head 17 jet inks.
As image data are supplied from the host apparatus 306 to the ink jet recording apparatus structured as described above, the image data are transferred to the reception buffer 307, and are temporarily stored therein. Then, they are developed by the system controller 301, into the frame memory 308 for each color (ink). Then, the developed image data are read out, and are subjected to a preset image processing operation, by the system controller 301. During the final stage of this preset image processing operation, the image data are subjected to master pattern processing steps, and then, the binary data which controls whether or not each ink is permitted to be applied during each of the multiple primary recording scans, is developed into the buffers 309. The recording operation controlling portion 310 controls the operation of the recording head 17 based on the binary data in each buffer.
Next, the ingredients of each ink of the ink set used in this embodiment, and the method for producing the inks used in this embodiment, will be described.
First, the following pigment (10 parts), anionic high polymer (30 parts), and pure water (60 parts) are mixed:
Pigment: C.I. pigment yellow 74 (Hansa Brilliant Yellow 5GX (product name of Clariant (Japan) K.K)
Anionic high polymer P-1: copolymer of styrene/butyl alcohol/acrylic acid (copolymer ratio (weight ratio)=30/40/30, 202 in acid value, 6,500 in weight average molecular weight, 10% water solution, potassium hydroxide (neutralizer)) 30 parts
Next, the following ingredients are placed in a vertical sand mill of the batch type (product of Imex Co., Ltd.), and then, the sand mill is filled with 150 parts of zirconia beads (0.3 mm in diameter). Then, the mixture is stirred, while being water cooled, for 12 hours to evenly disperse the ingredients. Then, the large particles are removed by placing the mixture in a centrifugal separator, obtaining thereby the final product, in which pigments 1, which are 120 nm in weight average diameter and roughly 12.5% in solid content. Then, the obtained pigment mixture was used to make ink with the use of the following method:
The following ingredients are thoroughly mixed, stirred, dissolved, and dispersed. Then, the mixture was filtered with a Microfilter (product of Fuji Film), which was 1.0 μm in pore size, while applying pressure, obtaining thereby Ink 1.
Pigment containing mixture 1:40 parts
Glycerine: 9 parts
Ethylene glycol: 6 parts
Acetylene glycol ethylene oxide (acetylene derivative) (product name: Acetylenol EH): 1 part
1,2-hexane diol: 3 parts
Polyethylene glycol (1,000 in molecular weight): 4 parts
Water: 37 parts
The ingredients were benzyl acrylate and methacylic acid. First, block polymer of A-B type, which was 300 in acid value, and 2,500 in numerical average molecular weight, was made, using one of the ordinary method. Then, the block polymer was neutralized with water solution of potassium hydroxide, and then, was diluted with ion exchange water, obtaining thereby homogenous water solution of the block polymer, which is 50% in mass. Then, 100 g of the above described water solution of the polymer was mixed with 100 g of C.I. pigment red 122, and 300 g of ion exchange water. Then, the mixture was mechanically stirred for 0.5 hour. Then, the mixture was put through five times through an interaction chamber under a liquid pressure of roughly 70 Mpa, with the use of a micro-fluidizer. Further, the ingredients, inclusive of large particles of magenta pigment, which do not remain dispersed in the thus obtained liquid, in which the pigment red particles had been dispersed, were removed with the use of a centrifugal separated (for 20 minutes at 12,000 rpm). The obtained liquid in which magenta pigments remained dispersed was 10% (mass) in pigment and 5% (mass) in dispersant density.
Ink was made from the above described liquid in which magenta pigments were dispersed. To this liquid, the following ingredients were added so that the density of the mixture became as preset. After the mixture of these ingredients were thoroughly mixed by stirring, the mixture was filtered under pressure with a Microfilter (product of Fuji Film), which was 2.5 μm in pore size, yielding pigment ink, which was 4% (mass) in pigment density and 2% (mass) in dispersant density.
Magenta pigment containing liquid mixture 1:40 parts
Glycerine: 10 parts
Di-ethylene glycol: 10 parts
Acetylene glycol ethylene oxide (acetylene derivative) (product name: Acetylenol EH): 0.5 part
Ion exchange water (product of Kawaken Fine Chemicals Co., Ltd.): 39.5 parts.
The materials for the liquid dispersion medium are benzyl acrylate and methacylic acid. First, block polymer of A-B type, which was 2,500 in acid value, and 3,000 in numerical average molecular weight, was made, using one of the ordinary method. Then, the block polymer was neutralized with water solution of potassium hydroxide, and then, was diluted with ion exchange water, obtaining thereby homogenous water solution of the block polymer, which was 50% in mass. Then, 180 g of the above described water solution of the polymer was mixed with 100 g of C.I. pigment blue 153 and 220 g of ion exchange water. The mixture was mechanically stirred for 0.5 hour. Then, the mixture was put through five times through an interaction chamber under a liquid pressure of roughly 70 Mpa, with the use of a micro-fluidizer. Further, the ingredients, inclusive of large particles of magenta pigment, which did not remain dispersed in the thus obtained liquid, in which the pigment red particles were dispersed, were removed with the use of a centrifugal separated (for 20 minutes at 12,000 rpm). The obtained liquid in which cyan pigments remained dispersed was 10% (mass) in pigment density and 10% (mass) in dispersant density.
Ink was made from the above described liquid in which cyan pigments remained dispersed. To this liquid, the following ingredients were added so that the density of the mixture became as preset. After the mixture of these ingredients were thoroughly mixed by stirring, the mixture was filtered under pressure with a Microfilter (product of Fuji Film), which was 2.5 μm in pore size, yielding pigment ink, which was 2% (mass) in pigment density and 2% (mass) in dispersant density.
Cyan pigment containing liquid mixture: 20 parts
Glycerine: 10 parts
Di-ethylene glycol: 10 parts
Acetylene glycol ethylene oxide (acetylene derivative): 0.5 part
Ion exchange water (product of Kawaken Fine Chemicals Co., Ltd.): 53.5 parts
100 g of the above described water solution of the polymer, which was used for the production of yellow ink 1, was mixed with 100 g of carbon black, and 300 g of ion exchange water. Then, the mixture was mechanically stirred for 0.5 hour. Then, the mixture was put five times through an interaction chamber under a liquid pressure of roughly 70 Mpa, with the use of a micro-fluidizer. Further, the ingredients, inclusive of large particles of magenta pigment, which did not remain dispersed in the thus obtained liquid, in which the pigment black particles were dispersed, were removed with the use of a centrifugal separated (for 20 minutes at 12,000 rpm). The obtained liquid in which black pigments remained dispersed was 10% (mass) in pigment density and 6% (mass) in dispersant density.
Ink is made from the above-described liquid in which black pigments remained dispersed. To this liquid, the following ingredients were added so that the density of the mixture became as preset. After the mixture of these ingredients were thoroughly mixed by stirring, the mixture was filtered under pressure with a Microfilter (product of Fuji Film), which was 2.5 μm in pore size, yielding pigment ink, which was 5% (mass) in pigment density and 3% (mass) in dispersant density.
Mixture of liquid dispersant and black pigment: 50 parts
Glycerine: 10 parts
Tri-ethylene glycol: 10 parts
Acetylene glycol ethylene oxide (acetylene derivative): 0.5 part
Ion exchange water (product of Kawaken Fine Chemicals Co., Ltd.): 25.5 parts
The results of the test carried out by the inventors of the present invention in order to examine the difference in friction resistance among the inks described above are given in Table 1. In this test, the friction resistance was subjectively evaluated based on how easily the images formed with the use of these inks became scarred when scratched with nails. In the table, G means that the images were not scarred at all; F means that the images were slightly scarred; and NG means that the images peeled. The recording medium used in this test was glossy photographic paper (product of Canon: glossy photo-paper [thin] LFM-GP421 R (commercial name)). The above-described patches were recorded with the use of a recording method, in which each of the regions 1-8 of the recording head were equal in recording ratio. Each patch was recorded by eight passes (mask pattern which made each pass 12.5% in recording ratio).
It is evident from Table 1 that in the case of the set of inks in this embodiment, the yellow ink was superior in friction resistance to the other inks. It may be thought that the reason therefor is that the coefficient of friction between the portion of the recording medium surface covered with the yellow ink and the nails was lower than the portion of the recording medium surface covered with any of the other inks and the nails.
Next, the inventors of the present invention carried out a test for studying the friction resistance of green (secondary color) images, which were formed with the use of the cyan and yellow inks. In the test, three kinds of image, which were different in the order in which the cyan and yellow inks were applied. The method used for testing the images was the same as that was used to obtain the results shown in Table 1. More specifically, the patches were record by applying both the cyan and yellow inks at 100% (total of 200%), under that same condition as that was used to test the black, cyan, magenta, and yellow inks. In order to control the order in which inks were applied, two kinds of mask pattern were created, which were specific in form. One kind of mask pattern (mask pattern 1) was such that cyan ink was applied at a ratio of 25% (therefore, total ratio of 100%) during each of the front four passes, and then, yellow ink was applied at a ratio of 25% (therefore, total ratio of 100%) during each of the latter four passes). Another mask pattern (mask pattern 2) was opposite in the relationship between the two inks. There was also prepared an ordinary mask pattern (mask patter 3), which allowed both yellow and cyan inks to be applied at a ratio of 12.5% per pass. Then, the green images formed with the use of the cyan and yellow inks and the three kinds of mask pattern were tested for friction resistance. The obtained
results were shown in Table 2.
(Table 2: Relationship between friction resistance, and order in which inks were applied)
It is evident from Table 2 that even though two kinds of green image were the same in appearance, those formed by apply yellow ink after cyan ink were superior in friction resistance. It may be reasonable to think that this result is attributable to the fact that applying the yellow ink after the cyan ink yielded images, the surface of which was lower in frictional resistance than those formed by applying the yellow ink before the cyan ink. It may also be reasonable to think that the reason why applying the yellow ink before the cyan ink resulted in the formation of the green images which were inferior in friction resistance than the green images formed by applying the yellow ink after the cyan ink is that as the cyan ink was applied on the layer of the yellow ink, it did not firmly bond to the layer of the yellow ink.
Based on the result of tests given above, the inventor of the present invention determined that in a case where yellow ink is mixed with ink of another color, or inks of other colors, to yield ink of secondary color, increasing yellow ink in the ratio with which it is applied after the other inks, is effective to yield an image which is higher in friction resistance. However, always applying the yellow ink only during the latter half passes in order to apply the yellow ink as late as possible compared to the other inks makes the nozzles uneven in the frequence of usage, and/or makes unnecessarily uneven the recording passes of the ink jet head across recording medium. It is desired that causing the unnecessarily higher level of unevenness is avoided as much as possible.
The inventors of the present invention reached the following conclusion through the ardent study of the results of the tests: In order to yield an image, which is superior in friction resistance while preventing the unevenness among the nozzles in terms of usage and the unevenness among the recording passes (scans) in terms of recording ratio, it is effective to change the passes (scans) for applying yellow ink from the default setup only when a set of preset conditions are met. To describe in more detail, making the mask pattern changeable per unit pixel so that the yellow ink is applied during as late as possible passes, or during the last pass, only for the areas (unit pixels) of recording medium, which satisfy the conditions under which the yellow ink is applied along with another ink or other inks.
Incidentally, in this specification, the ink(s) which is switched in the order of application based on whether it is applied to yield a unit pixel which satisfies the preset conditions, or a unit pixel which does not satisfy the preset conditions, is defined as “specific ink”. The number of “specific inks” is not limited to one; it may be two or more. On the other hand, any of the inks other than the “specific ink” are defined as a “nonspecific ink”. In the case of the present invention, yellow ink comes under the definition of “specific ink”, whereas cyan, magenta, and black inks come under the definition of “nonspecific ink”. Also in this embodiment, yellow ink, which is excellent in friction resistance, is listed as the specific ink. However, the selection of inks which are excellent in friction resistance is not limited to yellow ink. That is, if cyan ink, magenta ink, etc., could meet certain criteria, they might be inks which are excellent in friction resistance. In such a case, the cyan and magenta inks, which are excellent in friction resistance, come under the definition of “specific ink”.
Hereafter, the concrete structural setup for making it possible to carry out the control, which characterizes this embodiment of the present invention, will be described.
Generally, first, the printer driver installed in the host apparatus receives pixel data having the RGB (red, green, blue) data 101 from application software, or the like. Then, in a resolution changing step 102, it converts the pixel data into RGB data 103, which are proper in resolution to be outputted to the recording apparatus. The resolution after this conversion is different from the final resolution (2,400 dpi×1,200 dpi), that is, the resolution with which the recording apparatus records dots. In the following step, or a color adjustment step 104, the print driver adjusts in color the RGB data 103 of each pixel to create R′G′B′ data 105, which are suitable for the recording apparatus. In this color adjustment step 104, a lookup table, which has been prepared in advance, is referenced.
In a color separation step 106, the R′G′B′ data 105 are converted into density data for CMYK (cyan, magenta, yellow, and black), which correspond to the colors of the inks used by the recording apparatus. Generally, also in the color separation step, a lookup table is referenced. As for a concrete color conversion method, a certain portion of the nonchromatic components of the RGB data is replaced with K (black), while the RGB data are replaced with CMY (complementary colors, respectively, of RGB). The density data 107 obtained in the color separation step 106 are 8 bit data, which have 256 levels of tone. However, in a 4 bit data conversion step 108, the density data 107 are converted into density data 109, which have 9 levels of tone which are expressed in 4 bits. As a multi-value (nonbinary) conversion, such as this one, an ordinary nonbinary error dispersion process can be employed. In this step, the density data which have 9 levels of tone which are expressed in 4 bits, are density data having 9 levels of tone which have values of 0000-1000 in binary system.
On the other hand, the 8 bit density data for CMYK, which were created in the color separation step 106, are also used in a mask selection parameter computation step 110, in which a mask selection parameter MP 111, which has information made up of 0 or 1, is selected by computation, with reference to the density data for four colors.
Table 3 shows the density data CMYK used in the mask selection parameter computation step 110, and intermediary numerical values which resulted during the process for obtaining the intermediary mask selection parameter MP′ from the combinations of these data. In this embodiment, the coefficients for weighting the C, M, and K are set to 0.16, and the coefficient for weighting the Y is set to 0.5. Further, the constant B used in the computation step 1103 is set to 128. As will be evident from the table, in a case where the ratio (A/B) of a density A for Y (amount by which Y is applied) relative to the density B for the other colors (amount by which C, M, and Y are applied) is small, the value of the intermediary mask selection parameter MP′ is likely to be relatively large. On the other hand, in a case where the ratio of the density value A of Y to the density value B of the other colors, the is, A/B, is small, the value of the intermediary mask selection parameter MP′ is likely to be relatively large. That is, the intermediary mask selection parameter MP′ is related to the relationship between the specific ink and nonspecific ink(s); the smaller the above described ratio (A/B), the larger the MP′ is likely to be, and therefore, the larger will be the probability with which a pattern (mask pattern B) which is relatively high in the record permission ratio during the latter half of the passes (scans) is selected, as will be
described later.
Described above, various computations are made for each pixel, following the flowchart in
As the intermediary mask selection parameter 1104 is obtained by calculation, a one bit (binary) mask selection parameter MP 111 is obtained by in a binarization step 1105. As the binalizing process used in the binalizing step 1105, an ordinary error diffusing method or dithering method may be used.
The 4-bit density data for each color, and mask selection parameter MP111, which are obtained in the sequence of steps described with reference to
By employing an index developing process such as the one described above, it is possible to reduce the amount of the load to which the host apparatus is subjected for image processing, and the amount of the data which have to be transferred from the host apparatus to the recording apparatus. For example, in order to accurately specify which pixels among all the pixels in each of the groups of 4×2 pixel sets, information equivalent to 8 bits is necessary. That is, in order for the host apparatus to inform the recording apparatus of the data regarding a set of 4×2 pixels, the host apparatus has to transfer information which is equivalent to 8 bits. However, if the recording apparatus is provided with an index pattern, such as the one shown in
The following steps 1308-1312 are steps for selecting one of the two mask patterns stored in the ROM, and producing recording data used for recording dots during each recording pass (scan). More specifically, first, in Step 1308, it is determined whether the data to be processed is for yellow. It if it is determined that the data to be process is for colors other than yellow, Step 1311 is taken, in which a recording datum 1312 is produced with the use of the mask pattern A. In other words, in the case of the data for cyan, magenta, and black, the mask pattern A, which is less uneven in recording permission ratio among recording passes (scans) is selected, whereby the recording permission ratio for each recording pass (scan) for cyan, magenta, and black is set by this selection.
On the other hand, if it is determined in Step 1308 that the datum to be processed is for yellow, Step 1309 is taken, in which the mask selection parameter MP111 for a target unit pixel is checked in value. If MP=1, Step 1301 is taken, in which a recording datum 1312 is generated with the use of the mask pattern B. If MP=0, Step 1311 is taken, in which a recording datum 1312 is generated with the use of the mask pattern A. That is, in the case of yellow color, the mask pattern A, or the mask pattern B which is greater in the recording permission ratio during the latter half of recording passes (scans) than the mask pattern A, is selected based on the information regarding the yellow ink and the inks other than the yellow ink, applied to each unit pixel. Further, by selecting the mask pattern as described above, it is possible to variably set the recording permission ratio for each primary recording pass (scan) for applying yellow ink. The relationship between the mask selection parameter MP generated as described above, and the mask pattern to be used, is as shown in Table 4.
a) and 12(b) are drawings for describing the details of the mask patterns A and B, respectively. Regarding both drawings, designated by a referential number 71 are the nozzle columns, which are the same in the color of the inks they jet. They have 1,280 nozzles (ink jetting openings), which are arranged in the direction parallel to the secondary scan direction, at 1,200 dpi. These nozzles are separated into eight nozzle groups made up of consecutively positioned nozzles. The nozzle groups are used with mask patterns 73a-73h, or mask patterns 73i-73p, respectively, which are shown on the right side of the nozzle groups. For example, in the case of
In the case of the mask pattern A in
In
To summarize, the image processing sequence shown in
The drawings 142C-142K represent binary data after the index development of the density data 109 of 141C-141K, respectively. As described above, each unit pixel in this embodiment is made up of eight pixels. Whether or not each pixel is to be recorded is determined by converting the density data 141C-141K into index patterns (dot patterns) such as those shown in
Designated by a referential symbols 143MP is the mask selection parameter MP obtained by calculation based on the image data of 141C-141K. The ratio of the Y signal value (141Y) of the area A to the CMK signal value (sum of 141C, 141M, and 141K) is relatively small. Therefore, the mask selection parameter MP becomes 1 for three unit pixels among the four unit pixels in the area A. That is, as the mask pattern used for recording the yellow ink in the area A, the mask pattern B is selected for the three unit pixels among the four unit pixel, and the mask pattern A is selected for the remaining one. On the other hand, the ratio of the Y signal value (141Y) in the area B to the CMK signal value (sum of 141C, 141M, and 141K) is relatively high. Therefore, the mask selection pattern MP becomes 0 for all of the four pixels. Therefore, as the mask pattern to be used for recording the yellow ink for the area B, the mask pattern A is selected for all of the four pixels.
Referential symbols 144A and 144B correspond to the mask patterns A and B, which correspond to the area 8 (group 8) in
The drawings 145C-145K show the results of the logical multiplication of the binary data 142C-142K after the index development, and the mask pattern A (144A) or mask pattern B (144B), which is selected for each unit pixel. The drawings 144A and 144B show the portions of the mask patterns A and B, which correspond to the area 8, showing therefore the pixels permitted to be recorded during the last recording pass (scan). It is not always true that the value of the density signal of the yellow in the area A in the drawing 141Y is as great as expected than the density signal value of the other colors (141C, 141M, and 141K). However, the ratio of the pixels (dots) to be recorded during the last recording pass (scan), that is, the ratio of the black square in the area A of the 145Y, is larger than the that in the area A of the other colors (145C, 145M, and 145K). The reason for this is that in the case of yellow which is not as large in density data as it thought it would be than the other colors, the mask pattern is selected so that the last of the multiple passes will be as high as possible in the ratio of the amount of ink to be applied, by the sequences of processes described with reference to
Table 5 shows the results (evaluations in terms of friction resistance and nonuniformity) of a test in which the mask pattern A was used for all the colors, a test in which the mask pattern B was used for all the unit pixel of yellow, and a test in which images were recorded in accordance with this embodiment.
Referring to Table 5, using the mask pattern B for all the unit pixels of only yellow increases the probability with which the yellow ink, which is greater in friction resistance than the other inks, is applied in a manner to cover the other inks. Therefore, it makes it possible to form an image, the entirety of which is superior in friction resistance. On the other hand, the mask pattern B makes the nozzles significantly nonuniform in usage frequency, which in turn reduces the merits of the multi-pass recording method. In particular, an image, the image data of yellow of which is high in density, will be recorded so that it will be conspicuously nonuniform.
In comparison, in this embodiment, for a unit pixel, which is relatively large in the ratio of the data value of yellow, to the data values of the other color, nonuniformity is taken more seriously than friction resistance, and therefore, the mask pattern A is selected, which is less in the nonuniformity in recording permission ratio among the multi-passes than the mask pattern B. On the other hand, for a unit pixel, which is relatively small in the data value of yellow, to the data values of the other colors, being therefore likely to be inferior in friction resistance, but, unlikely to be conspicuously nonuniform, the mask pattern B is selected, which is greater in the recording permission ratio during the latter half of recording passes (scans) or the last recording pass.
As described above, in this embodiment, the recording permission ratio for a specific ink (which in this embodiment is yellow ink) is made variable by selecting the mask pattern for the specific ink, based on the conditions (for example, information about amount by which ink is applied) under which the specific ink and nonspecific inks (inks other than yellow ink) are applied to each unit pixel to which the specific ink is to be applied. Thus, a unit pixel to which both the specific and nonspecific inks are applied is higher in the probability with which the specific ink is applied during the last half of the recording passes, or the last recording pass. Consequently, the probability with which the specific ink is applied during the later recording passes than the recording passes during which the nonspecific inks are applied, is higher. Thus, the specific ink, which is superior in friction resistance to the other inks, can be applied later than the other inks. Therefore, it is possible to form an image which is superior in friction resistance than an image formed with the use of the conventional recording method. In this embodiment, in order to achieve the above described effects, such a mask pattern that can make it possible to control only the order in which inks are applied to specific unit pixels is selected from among the multiple mask patterns prepared in advance.
Incidentally, the host apparatus in this embodiment described above was designed to transfer to the recording apparatus, the 4-bit data 109 generated by converting (Step 108) the 8-bit density data 107 obtained by separating (Step 106) optical image of the image to be recorded. Further, the recording apparatus (system controller) was designed to convert the received 4-bit data 109 into the binary data 1307 with the use of the index development process 1306. By designing the host apparatus and recording apparatus as described above, it is possible to reduce the amount of the data which the host apparatus has to process, and therefore, it is possible to reduce the length of time it takes for the data to be transferred to the recording apparatus. This embodiment, however, is not intended to limit the image processing steps to those described above. For example, the image processing steps may be such that the host apparatus converts the nonbinary (multi-value) density data 109 obtained by the color separation process 106 (step), into binary data, and then, transfers the binary image data (1,200 dpi×2,400 dpi) to the recording apparatus. Such a design can also provide the same effects as those which characterize this embodiment of the present invention, as the designs of the host apparatus and recording apparatus in this embodiment.
Further, in this embodiment, the image processing steps in
Also in this embodiment, the same inks as those used in the first embodiment are used by the same ink jet recording apparatus as the one used in the first embodiment and shown in
Further, in this embodiment, the recording apparatus does not prepare the binary mask patterns such as those in the first embodiment. Instead, it prepares mask patterns (recording permission ratio determining patterns) which determine only the recording permission ratio for each region of the recording head.
a) and 16(b) are drawings for describing the two kinds of mask patterns, that is, a mask pattern A and a mask pattern B, prepared in this embodiment. In the case of the mask pattern A, which is shown in
In this embodiment, first, in Step 1701, it is determined whether the inputted 8-bit density data 107 is for yellow color or the other colors. If it is determined that the data is for the colors other than yellow, Step 1704 is taken, in which an output datum 1705 is generated with the use of the mask pattern A. That is, for cyan, magenta, and black, the mask pattern A is used, which is less nonuniformity in recording permission ratio among the multiple recording passes (scans).
On the other hand, if it is determined that the data to be processed is for yellow ink, Step 1702 is taken, in which the value of the mask selection parameter MP111, which corresponds to the unit pixel which includes this data, is confirmed. If MP=1, Step 1703 is taken, in which an 8-bit datum 1705 is generated with the use of the mask pattern B, which is greater in the recording permission ratio for the latter half of the recording passes (scans). If MP=0, Step 1704 is taken, in which an output datum 1705 is generated with the use of the mask pattern A. In this embodiment, the output datum 1705 is obtained by the multiplication between the 8-bit density data 107 for the pertaining unit pixel, and the recording permission ratio stored in the mask pattern A or mask pattern B. Thereafter, a 1-bit recording data 1707 is obtained by carrying out a binarization process 1706 (Step 1706). That is, a pixel (or pixels) into which a dot is to be recorded during each recording pass (scan) is determined.
The sequence of image processing steps shown in
a)-(g) are drawings for explaining the 8-bit density data 107, mask selection parameter MP, mask pattern, and the example of the recording data 1707 obtainable from the proceeding variables.
b) is a drawing which shows an example of the mask selection parameter MP for a unit pixel, which was obtained from the above described density data for the yellow, and the unshown density data for the other three colors (cyan, magenta, and black).
c) and 18(d) show the portions of the mask patterns A and B shown in
e) is a drawing the mask pattern selected for each unit pixel, which corresponds to the region 8, based on the yellow density data shown in
f) is a drawing which shows the results of the product between the image data for yellow shown in
g) is a drawing which shows the results of the binarization of each unit pixel, in a format of (2 pixels×4 pixels). The black pixels are where the dots are to be recorded by the region 8, and the white pixels are where no dot is going to be recorded.
This embodiment described above is an adaptation of the recording method disclosed in Japanese Laid-open Patent Application 2000-103088. More specifically, disclosed in Japanese Laid-open Patent Application 2000-103088 is a recording head structure which uses nonbinary (multi-value) mask patterns, the recording permission ratio of which is as shown in
In this embodiment, not only the recording head structure disclosed in Japanese Laid-open Patent Application 2000-103088, but also, the recording head structure capable of changing the mask pattern to be used, for every unit pixel, are employed. Thus, not only does this embodiment provide the same effects as the first embodiment, but also, it provides the effects disclosed in the Japanese Laid-open Patent Application 2000-103088. In the case of the mask pattern shown in
Also in this embodiment, the same ink jet recording apparatus shown in
On the other hand, if it is determined that the inputted datum is for yellow (ink), Step 2101 is taken, in which a mask pattern, which corresponds to the value of the mask selection parameter MP′1104 for the pertaining unit pixel, is selected from among 32 different mask patterns shown in
Also in this embodiment, the output datum 2105 is obtained by the multiplication between the 8-bit image datum 107 for the pertaining unit pixel, and the recording permission ratio stored in the selected mask pattern. Thereafter, the binarization step 2106 is carried out to obtain the 1-bit recording datum 2107. That is, the pixel for which a dot is to be recorded per recording pass (scan) is determined.
As will be evident from the description given above, the series of image processing steps shown in
In this embodiment described above, the different mask patterns switchable for each unit pixel is prepared by a greater number than in the two embodiments described above. Therefore, this embodiment is more flexible than the preceding two embodiments, in terms of the response to the small changes in the density data. Thus, this embodiment can reduce the concern about image defects attributable to the switching between the two masks which are substantially different in recording permission ratio. Thus, it may be expected that the recording apparatus in this embodiment will output an image which is smoother in appearance than those which will be outputted by the recording apparatus in the preceding two embodiments.
In order to prevent the formation of an image which suffers from the nonuniformity in density, which is attributable to positional registration errors, the second and third embodiments, which adopted the structural arrangement disclosed in Japanese Laid-open Patent Application 2000-103088, binarized the nonbinary (multi-value) density datum after dividing the multiple data, which correspond one for one to multiple recording passes (scans) (which correspond to multiple nozzle groups; multiple regions of nozzle column). However, in case where the binarization process is carried out after the division of the density data into multiple data, there is no complementary positional relationship among the dots recorded during each recording scan, and therefore, there will be unit pixels into which no dot is recorded even if an image to be recorded is a 100% image, and/or unit pixels into which two or more dots are recorded in layers. Japanese Laid-open Patent Application 2000-103088 states that this kind of state is effective to suppress or minimize the density aberration attributable to the registering errors.
However, the employment of only the method described in Japanese Laid-open Patent Application 2000-103088 cannot provide the positional relationship between the dot recorded during one of the recording passes and the dot recorded during the other recording pass(s). Thus, it is likely to yield an image, the low frequency components of which are conspicuous. In other words, it is likely to yield a grainy image. In this embodiment, therefore, in order to ensure that a certain amount of complimentary positional relationship is maintained between a dot recorded during one of the multiple recording passes and a dot recorded during another recording pass, the information regarding the position of each of the recorded dot is obtained, and the position for the dots to be recorded during the following recording passes are selected so that the dots to be recorded will not be on the spot (unit pixel) on which the dot has already been recorded.
Also in this embodiment, the same ink jet recording apparatus, as those in the preceding embodiments, illustrated as in
On the other hand, if it is determined in Step 2201 that the inputted datum is for yellow (ink), Step 2201 is taken, in which a mask pattern, which corresponds to the value of the mask selection parameter MP′1104 for the pertaining unit pixel, is selected from among 32 different mask patterns shown in
In the following Step 2206, a new 8-bit CMYK information C″, M″, Y″ and K″ is obtained by processing the generated output datum 2205, based on the control information given in the next drawing, or
Next, a control information computation step 2210 for obtaining the control information for rectifying the output data 2205 for the following recording pass, is carried out, based on the obtained 1-bit recording datum 2209. Then, the obtained information is rewritten as new control information (Step 2211).
Next, this new control information 2306 is added to (subtracted from) the output datum 2205 (2301) for the (N+1)-th recording scan. The result of the binarization (Step 2308) of the thus obtained new 8-bit datum becomes the information (recording datum 2209) which indicates the position of the unit pixel, into which a dot is to be recorded by the nozzle group (N+1) during the (N+1)-th recording scan. Further, the data for the other nozzle groups are also repeatedly processed as described above to obtain the final binary data (position of unit pixels into which dots are to be recorded).
In this embodiment, the control information is written over each time cumulative number of recording scans increases, and therefore, a unit pixel selected as the unit pixel into which a dot is to be recorded increases in minus value, whereas a unit pixel, which has not been selected as the unit pixel into which no dot is to be recorded is likely to increase in plus value. Thus, once a dot is recorded into a given unit pixel, the datum for this unit pixel, which is created for the next group of nozzles, is likely to become zero as it is binarized. That is, once a dot is recorded into a given unit pixel, this unit pixel becomes smaller in the probability with which a dot will be recorded into this unit pixel. Therefore, each recording scan is likely to be exclusionary to the other recording scans in terms of the dot arrangement, making it possible to obtain an image which is uniform in that it is low in the number of low frequency components, appearing therefore less grainy.
a)-24(h) are drawings of the examples of the density datum 107, intermediary mask selection parameters MP′, mask patterns, and examples of recording data obtainable from the preceding variables.
b) is a drawing that shows an example of intermediary mask selection parameter MP′ for each unit pixel, which are obtainable from the abovementioned density datum for yellow, and the unshown density data for other three colors.
c) shows several mask patterns among the mask patterns 0-31 in
d) is a drawing which shows the selected mask patterns for the unit pixels which correspond to the region 1, and which correspond to the yellow density data shown in
e) is a drawing which shows the products of the multiplication between the density data for yellow, which is shown in
f) is a drawing which shows the results of the binarization of each value in
g) is a drawing which shows the results of the dispersion of the multi-value data into the pixels around the black pixel shown in
i) is a drawing which shows the result of the addition of the control information given in
As will be evident from
In this embodiment, the probability with which two or more dots are recording in layers during the multiple recording scans is minimized by the above described structural arrangement, in addition to that in the third embodiment. Thus, not only does this embodiment provide the effects provided by the above described third embodiment, but also, can yield an image which is not only smaller in the amount of low frequency components, but also, does not suffer from the nonuniformity in density, which is attributable to the misalignment in recording position among the multiple recording scans.
Also in this embodiment, the same ink jet recording apparatus as that used in the first embodiment, that is, the ink jet recording apparatus shown in
The intermediary mask selection parameter MP′ may be calculated with the use of a preset mathematical formula, as it is in Step 1103 described during the description of the first embodiment. Generally speaking, there is no linear relationship between the RGB data and CMYK data, and therefore, it is impossible to find such a proper mathematical formula that can unconditionally calculate the intermediary mask selection parameter MP′. Therefore, it is desirable that a three dimensional LUT, such as Table 6, in which the intermediary mask selection pattern MP′ is defined in advance in each cell of the three dimensional data for RGB, is provided so that a proper intermediary mask selection parameter MP′ is selected for each unit pixel.
After the intermediary mask selection parameter MP′ is set as described above, it is binarized (Step 2603) to obtain the 1-bit mask selection parameter 2604, which is transmitted to the recording apparatus. Thereafter, the mask patterns are selected in the recording apparatus, following the flowchart in
In the five embodiments described above, the present invention was described with reference to the recording method which applies yellow ink later than the other inks, based on the fact that yellow ink is superior in friction resistance than the other inks. However, in a case where there is an ink which is superior in friction resistance than yellow ink, the same effects as those obtained by the preceding embodiments can be obtained by converting the signal value of this ink in the same manner as the above described datum for the yellow ink is converted. Further, in a case where there is an ink (of a color) which is inferior in friction resistance than the other inks (of other colors), the above described recording method can be used to apply this specific ink earlier than the other inks while defining this ink as the specific ink.
For example, a case in which an ink which is lighter in color than ordinary inks is prepared; an ingredient or ingredients, such as wax, which can yield an image superior in friction resistance, are mixed into the prepared ink; and the order in which this ink is applied is controlled, instead of the order in which yellow ink is applied, falls within the scope of the present invention. In this case, the ink of the lighter color falls under the definition of “special ink”.
Further, in a case of an embodiment of the present invention, in which a clear ink, that is, an ink which does not contain coloring agent, and this clear ink is most friction resistant, the clear ink falls under the definition of “specific ink”. In other words, a “specific ink” may be a transparent ink. Thus, an embodiment of the present invention, in which the specific ink is a transparent ink, also falls within the scope of the present invention.
Further, the number of the “specific inks” does not need to be limited to one. For example, in a case where four different inks, such as the CMYK inks in the above described embodiments, are used, two inks, for example, C and Y inks, may be designated as “specific inks”, and the other inks, that is, M and K inks, may be designated as the “nonspecific inks”. In this case, each ink may be made different from the other inks in the method for calculating the mask selection parameter, or the same parameter may be shared by all the inks. Further, each method for calculating the mask selection parameter may be varied. For example, if it is desired to switch the mask pattern according to the color combination between the specific two inks, the mask selection parameter may be calculated using only the data for the two colors, instead of taking into consideration the density data for all the colors as in the computation step 1103 in
In all the embodiments of the present invention described above, multiple mask patterns are prepared for only the specific ink which an operator wants to control in the application timing, and the nonspecific inks were made the same in mask pattern. Needless to say, however, various mask patterns may be prepared in advance so that each ink is provided with a mask pattern different from those for the other inks.
Also in the above described embodiments, when selecting the parameter (mask pattern) to set the recording permission ratio for each of the recording scan for the specific ink (yellow), the information regarding all of the nonspecific inks to be applied to each unit pixel is taken into consideration. However, the datum (data) to be taken into consideration may be the information regarding only a part (for example, C) or parts (for example, M and K) of the nonspecific inks. That is, the present invention may be embodied in such a form that only the nonspecific inks (for example, M and K inks) which are involved in the determination of the recording permission ratio for the specific ink (Y), but also, a nonspecific ink (for example, C) which is not involved in the determination of the recording permission ratio with which the specific ink (Y) is applied. As will be evident from the description of the present invention given above, the essence of the present invention is that the ratio with which a specific ink is applied to each unit pixel is determined based on the information regarding the specific ink applied to each unit pixel and the information regarding to the nonspecific inks to be applied to the unit pixel, after the completion of the preceding recording scan.
Also in the embodiments of the present invention described above, the described control was carried out because the yellow ink was superior in friction resistance. However, the friction resistance of an ink is affected by other factors, for example, the type of the recording medium. Therefore, the nonuniformity in the frequency with which each nozzle is used can be reduced more by preparing two or more recording modes, and using the above described method only when the recording apparatus is operated in the mode in which friction resistance is the main concern.
As described above, according to the present invention, it is possible to control the order in which a specific ink is applied to each unit pixel, to which the specific ink is to be applied, without making each nozzle significantly different from the other nozzles in terms of the frequency of usage. Thus, the present invention enables the multi-pass recording method to fully display its effect, making it possible to output a high quality image which is uniform in appearance, and also, excellent in terms of friction resistance.
However, the property for determining whether an ink is a specific ink or a nonspecific ink does not need to be frictional resistance. The above described control structure in this embodiment effectively functions as long as it is employed by a recording apparatus which is structured so that it outputs an image which reflects the effect of applying a specific ink later (or earlier) than the nonspecific ink(s). For example, the present invention is applicable, with preferable results, to a case where the order in which color inks are applied is controlled to aggressively widen the color range.
Also in the above described embodiments, all the nozzle columns were divided into 8 regions (N=8).
That is, they were described with reference to an example of multi-pass recording method, the number of passes was 8 (N=8). However, the present invention can be embodied regardless of the value of N. Further, as for the direction in which the recording head is moved, it may be only one direction, or both directions. That is, the effects of the present invention remain roughly the same whether the recording head is moved in only one direction or both directions.
Further, the preceding embodiments were described as an ink jet recording system made up the host apparatus and recording apparatus, with reference to
Further, in the above described embodiments, the recording permission ratio is set by the selection of the mask pattern. However, the method for setting the recording permission ratio does not need to be limited to this method. For example, the present invention may be embodied as follows: A default recording permission ratio is prepared for all the unit pixels, and the recording permission ratio is changed only for a unit pixels identified as the pixel to be changed in recording permission ratio, based on the information regarding the ink to be applied to the unit pixel. In this case, therefore, the means for identifying a unit pixel to be changed in recording permission ratio may be a means for selecting the value for the recording permission ratio, or a means for changing the recording permission ratio in value.
Further, the present invention can be embodied by a set of program codes for making the host apparatus and/or recording apparatus carry out the above described processes (processes for determining recording scan for applying specific ink(s)) which characterize the present invention, or a storage medium in which the set of program codes is stored. In this case, the above described processes are read and carried out by the computer (or CPU or MPU). As will be evident from the description of the present invention given above, the programs for making a computer perform the above described processes which characterize the present invention, or the storage medium in which the programs are stored, are also included in the scope of the present invention. As the storage media for supplying the program codes, a floppy (registered commercial name) disk, a hard disk, an optical disk, a photo-magnetic disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, etc., can be used, for example. Further, the present invention may be embodied in such a form that as the sets of program codes read by a computer are carried out, the processes in the above described embodiments are carried out in entirety, or that the processes are partly or entirely carried out by the OS, which is in operation in the computer, based on the instructions of the program codes.
a) is a schematic drawing which shows the mask pattern A applicable to the first embodiment, and
a) is a schematic drawing of the mask pattern A applicable to the second embodiment, and
a)-18(g) are drawings for describing the image data, mask selection parameter MP, mask pattern, and example of recording data obtainable from the preceding variables.
a)-(i) are drawings for describing the image data, mask selection parameter, mask pattern, and the recording data obtainable from the preceding variables, in the fourth embodiment.
The present invention makes it possible to change, as necessary, the ratio with which recording is permitted for a specific ink, in any one of the multiple recording scans, based on the information regarding the specific ink applied to each unit pixel, and the information regarding the inks other than the specific ink. Therefore, it can change the recording scan to which the application of the specific ink is concentrate, making it possible to change the ratio with which the specific ink is applied before or after the other inks. Therefore, it can control the order in which the specific ink and the other inks are applied in layers.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-011834 | Jan 2008 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2009/051388 | Jan 2009 | US |
| Child | 12839086 | US |
