JP2006247918A - Printing device, printing program, printing method, image processing device, image processing program, image processing method, and recording medium on which the program is recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing device and a program and a printing method which can efficiently realize the reducing process of a banding phenomenon by accurately judging the occurrence of the banding phenomenon, and to provide an image processing device, the program, and the method and so forth. <P>SOLUTION: This inkjet method printing device comprises a printing head which can selectively type different dot sizes. The occurrence of the banding phenomenon is judged from nozzle characteristic information of the printing head 200, printing data and picture quality judging information. When the occurrence of the banding phenomenon is judged, the banding phenomenon is reduced by correcting the dot size of that region. Thus, the reducing process of the banding phenomenon can efficiently be realized by accurately judging the occurrence of the banding phenomenon. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing apparatus such as a facsimile machine, a copying machine, or a printer for office automation equipment, and in particular, draws a predetermined character or image by ejecting fine particles of liquid ink of a plurality of colors onto a printing paper (recording material). The present invention relates to a so-called inkjet printing apparatus, printing program, printing method and image processing apparatus, image processing program, image processing method, and recording medium on which the program is recorded.

Printers that employ such an ink jet method (hereinafter referred to as “inkjet printers”) are generally inexpensive and can easily obtain high-quality color prints, so with the spread of personal computers and digital cameras, It has become widespread for general users.
In general, such an ink jet printer has a print head in which a moving body called a carriage, which is integrally provided with an ink cartridge and a print head, reciprocates on the print medium (paper) in the right and left directions in the paper feed direction. By ejecting (injecting) liquid ink particles from the nozzles in the form of dots, predetermined characters and images are drawn on the printing paper to create a desired printed matter. The carriage is equipped with four color (yellow, magenta, cyan) ink cartridges including black (black) and a print head for each color, so that not only monochrome printing but also full-color printing combining each color is easy. (Furthermore, 6-color, 7-color, or 8-color colors obtained by adding light cyan, light magenta, etc. to these colors are also in practical use).

  In addition, in this type of ink jet printer in which printing is performed while the print head on the carriage is reciprocated in the left and right direction (width direction of the printing paper) in the paper feeding direction, printing is performed in order to print the entire page cleanly. Since it is necessary to reciprocate the head several tens of times to 100 times or more, the printing time is significantly longer than that of other types of printing apparatuses such as laser printers using electrophotographic technology such as copying machines. There is such a drawback.

  On the other hand, in an ink jet printer that does not use a carriage with a long print head having the same dimensions as the width of the print paper, it is not necessary to move the print head in the width direction of the print paper. Therefore, high-speed printing similar to that of the laser printer is possible. In addition, since a carriage for mounting the print head and a drive system for moving the print head are not required, the printer housing can be reduced in size and weight, and the quietness can be greatly improved. Yes. The former inkjet printer is generally referred to as a “multi-pass printer”, and the latter inkjet printer is generally referred to as a “line head printer”.

  By the way, a print head indispensable for such an ink jet printer is formed by arranging fine nozzles having a diameter of about 10 to 70 μm in series at a predetermined interval or in multiple stages in the printing direction. Depending on the error, the ink ejection direction of some nozzles may be tilted, or the position of the nozzles may be shifted from the ideal position, and the dots formed by the nozzles may be shifted from the target point. A so-called “flight bend phenomenon” may occur.

  As a result, a printing defect referred to as a so-called “banding (streaks) phenomenon” may occur in a print portion corresponding to the defective nozzle portion, and the print quality may be significantly reduced. That is, when the “flying curve phenomenon” occurs, the distance between adjacent dots becomes non-uniform, and “white streaks (when the printing paper is white)” occurs in a portion where the distance between adjacent dots is long. A “dark streak” occurs in a portion where the distance is short.

  In particular, such banding phenomenon is caused by the fact that the print header is fixed (one-pass printing) and the number of nozzles is much larger than that of the multi-pass printer, as compared with the case of the “multi-pass printer” as described above. This is more likely to occur in the “line head type printer” (in a multi-pass type printer, there is a technique for making the white stripe inconspicuous by making the print head reciprocate several times).

Therefore, in order to prevent a kind of printing failure due to such "banding phenomenon", research and development in the so-called hardware part, such as improvement of print head manufacturing technology and design improvement, has been earnestly advanced. It is difficult to provide a print head that does not cause 100% “banding phenomenon” due to manufacturing cost, print quality, and technical aspects.
Therefore, in addition to the improvement in the hardware part as described above, a technology that reduces such “banding phenomenon” using a so-called software method such as printing control as described below is used in combination. Has been.

For example, in Patent Document 1 and Patent Document 2 shown below, the dot diameter is positively changed based on the knowledge that the banding phenomenon becomes conspicuous when the dot recording pitch and the dot diameter become equal to halfway. A technique for reducing the banding phenomenon by making it different from the above is disclosed.
Further, in Patent Document 3 shown below, in order to prevent the dot recording pitch and the dot diameter from becoming substantially the same, “large”, “medium”, and “small” dots are divided, A technique is disclosed in which when the dots have the same diameter as the recording pitch, the banding phenomenon is reduced by replacing the data with odd (or even) lines immediately before the dot.
JP-A-1-235655 JP-A-1-235656 Japanese Patent Laid-Open No. 11-254662

  By the way, in the method shown in the above-mentioned patent document, the banding phenomenon occurs mechanically uniformly when the dot recording pitch and the dot diameter are equal or when the dot recording pitch and the dot diameter are almost the same. Since the banding reduction process is performed as if it were a case, there is a problem that the process takes time when such a case covers a wide range.

In addition, the conspicuousness of white stripes and black stripes due to the banding phenomenon varies greatly depending on the relationship with the dot diameter, resolution, flight curve, dot color, etc., so even areas where banding reduction processing is unnecessary are wasted Efficient processing is difficult, for example, processing is not performed on a portion that has been processed or where banding reduction processing is required.
Therefore, the present invention has been devised to effectively solve such a problem, and the purpose thereof is to accurately determine the occurrence of the banding phenomenon and implement an efficient banding reduction process. A novel printing apparatus, printing program, printing method and image processing apparatus, image processing program, image processing method, and recording medium on which the program is recorded are provided.

[Mode 1] In order to solve the above problems, a printing apparatus according to mode 1
Print head having a plurality of nozzles that can divide dots of different sizes, nozzle characteristic information acquisition means for acquiring nozzle characteristic information relating to dot landing positions for each nozzle of the print head, and image data acquisition means for acquiring image data A print data generation unit that sets a dot of a predetermined size based on the pixel value for each pixel of the image data acquired by the image data acquisition unit, and generates print data; and the print data generation unit Banding determination means for determining occurrence of a banding phenomenon when the print data is printed by the print head based on the print data generated in step 1 and the nozzle characteristic information of the print head acquired by the nozzle characteristic information acquisition means; When the banding determination means determines that the banding phenomenon has occurred, And dot size correcting means for correcting the dot size involved in bindings phenomenon, is characterized in that and a print unit that executes print based on the print data corrected in the dot size correction means.

This makes it possible to accurately determine the occurrence of the banding phenomenon and perform banding reduction processing only on areas where “white lines” and “dark lines” are particularly noticeable. On the other hand, it is possible to realize an efficient printing process as compared with the case where it is uniformly performed.
Here, the “banding phenomenon” means not only “white streaks” caused by the “flight bend phenomenon” but also printing defects in which “dark streaks” occur simultaneously with the “white streaks” ( The following forms related to “printing apparatus”, forms related to “printing program”, forms related to “printing method”, forms related to “image processing apparatus”, forms related to “image processing program”, forms related to “image processing method”, and “the above-mentioned The same applies to the description of the form relating to the “recording medium on which the program is recorded” and the column of the best mode for carrying out the invention.

  In addition, as described above, the “flight bend phenomenon” is different from the non-ejection phenomenon of some nozzles, as described above. Although ink is ejected, the ejection direction of some of the nozzles is inclined and the dots are positioned at the target position. Phenomenon that is formed more deviated (forms relating to “printing apparatus”, forms relating to “printing program”, forms relating to “printing method”, forms relating to “image processing apparatus”, forms relating to “image processing program”, The same applies to the description relating to the “image processing method”, the description relating to the “recording medium on which the program is recorded”, the best mode for carrying out the invention, and the like.

  Also, “white streaks” are parts where the distance between adjacent dots continuously increases due to the “flying curve phenomenon” and the background color of the print medium stands out in a streak shape. The “dark streaks” are the same as the “flying bend phenomenon”, in which the phenomenon in which the distance between adjacent dots is continuously shorter than a predetermined distance and the color of the background of the print medium is changed. It becomes invisible or appears darker as the distance between the dots becomes shorter, and some of the dots that are separated from each other overlap normal dots, and the overlapped part becomes conspicuous in a dark streak shape A part (area) is referred to (a form relating to “printing apparatus” below, a form relating to “printing program”, a form relating to “printing method”, a form relating to “image processing apparatus”, “ Form about the image processing program ", a mode relating to an" image processing method ", and various types of 'a recording medium storing the program", is the same in the description, such as the best mode column for carrying out the invention).

[Mode 2] The printing apparatus of mode 2 is
In the printing apparatus according to aspect 1, the relationship between the resolution of the print data generated by the print data generation unit, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data The image quality determination information storage means for storing the recorded image quality determination information is provided, and the banding determination means is configured to print the print data generated by the print data generation means based on the image quality determination information stored in the image quality determination information storage means. It is characterized in that occurrence of a banding phenomenon is determined.

That is, as will be described in detail later in the description of the embodiment, the banding phenomenon described above includes the print data resolution, the dot size of each dot of the print data, and the landing position for each dot of the print data. Since the degree of conspicuousness varies greatly depending on the relationship with the error, in this embodiment, these relationships are stored in the image quality determination information storage means as image quality determination information, and the occurrence of a banding phenomenon of print data based on this image quality determination information Is determined.
As a result, it is possible to avoid an arbitrary (subjective) blurring of the banding phenomenon determination, and to objectively and accurately determine the occurrence of the banding phenomenon.

[Mode 3] The printing apparatus of mode 3 is
In the printing apparatus according to the second aspect, the image quality determination information storage unit further stores image quality determination information in which the dot color of the print data generated by the print data generation unit is recorded. It is.

In other words, the banding phenomenon described above is not limited to the relationship between the resolution of the print data, the dot size of each dot of the print data, and the landing position error for each dot of the print data, as shown in mode 2. In this embodiment, the dot color is also stored in the image quality determination information storage means in addition to the image quality determination information, and the banding phenomenon of the print data based on the image quality determination information. Is determined.
As a result, it is possible to avoid an arbitrary (subjective) blurring (sway) that is different for each dot color, and to objectively and accurately determine the occurrence of the banding phenomenon.

[Mode 4] A printing apparatus according to mode 4
In the printing apparatus according to the second or third aspect, the banding determination unit obtains the resolution of the print data generated by the print data generation unit from the minimum value of the empty space around the target dot. It is a feature.
As a result, the resolution of the print data generated by the print data generation means can be easily obtained by examining only the minimum value of the empty space around the target dot, and the processing can be performed more quickly.

[Mode 5] A printing apparatus according to mode 5
The printing apparatus according to any one of Forms 1 to 4, wherein the print head is a line head type print head.
As a result, as described above, it is possible to efficiently reduce the banding phenomenon that is particularly likely to occur when a line head type print head that completes printing in one pass is used.

[Mode 6] A printing apparatus according to mode 6 includes:
The printing apparatus according to any one of Forms 1 to 4, wherein the print head is a multipass print head.

The banding phenomenon described above is conspicuous in the case of a line head type print head, but also occurs in the case of a multi-pass type print head. Therefore, if the printing method according to any one of the first to fourth aspects is applied to a multi-pass type print head, the banding phenomenon generated in the multi-pass type print head can be efficiently reduced. it can.
Further, in the case of a multi-pass type print head, it is possible to avoid the banding phenomenon as described above by taking measures such as repeating scanning of the print head. If it is applied, since it is not necessary to scan the same portion over and over again, it is possible to realize higher speed printing.

[Mode 7] The print program of mode 7 is
Nozzle characteristic information acquisition means for acquiring nozzle characteristic information related to dot landing positions for each nozzle of a print head provided with a plurality of nozzles capable of differentiating dots of different sizes, image data acquisition means for acquiring image data, A print data generating unit that generates a print data by setting a dot of a predetermined size based on the pixel value for each pixel of the image data acquired by the image data acquiring unit, and generated by the print data generating unit Banding determination means for determining occurrence of a banding phenomenon when the print data is printed by the print head based on the printed print data and the nozzle characteristic information of the print head acquired by the nozzle characteristic information acquisition means, When it is determined by the banding determination means that a banding phenomenon has occurred, And a dot size correcting unit that corrects a dot size related to the ding phenomenon and a printing unit that performs printing based on the print data corrected by the dot size correcting unit. .

As in Form 1, it is possible to accurately determine the occurrence of the banding phenomenon, and to perform banding reduction processing only on the areas where “white streaks” and “dark streaks” are particularly noticeable. As compared with the case where the banding occurrence is uniformly performed, it is possible to realize an efficient printing process.
In addition, most printing apparatuses on the market such as inkjet printers are equipped with a computer system including a central processing unit (CPU), a storage device (RAM, ROM), an input / output device, and the like. Since each means can be realized by software, it can be realized more economically and easily than a case where dedicated means is created to realize each means.
Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 8] The print program of mode 8 is
In the printing program according to the seventh aspect, the relationship among the resolution of the print data generated by the print data generation unit, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data The image quality determination information storage means for storing the recorded image quality determination information is provided, and the banding determination means is configured to print the print data generated by the print data generation means based on the image quality determination information stored in the image quality determination information storage means. It is characterized in that occurrence of a banding phenomenon is determined.

As a result, similarly to the second aspect, it is possible to avoid an arbitrary (individual) banding phenomenon determination fluctuation (vibration) and to objectively and accurately determine the occurrence of the banding phenomenon.
Further, since each means can be realized by software using a computer system provided in most printing apparatuses currently on the market as in the case of Form 8, dedicated hardware is created to create each of the above-mentioned means. It can be realized economically and easily as compared with the case of realizing the means.
Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 9] The print program of mode 9 is
In the printing program according to the eighth aspect, the image quality determination information storage unit further stores image quality determination information in which the dot color of the print data generated by the print data generation unit is recorded. It is.

As a result, similarly to the third aspect, it is possible to avoid an arbitrary (individual) determination blur that varies for each dot color, and to objectively and accurately determine the occurrence of the banding phenomenon.
Further, since each means can be realized by software using a computer system provided in most printing apparatuses currently on the market as in the case of Form 8, dedicated hardware is created to create each of the above-mentioned means. It can be realized economically and easily as compared with the case of realizing the means.
Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 10] The print program of mode 10 is
In the printing program according to the eighth or ninth aspect, the banding determination unit obtains the resolution of the print data generated by the print data generation unit from the minimum value of the empty space around the target dot. It is a feature.

As a result, it is possible to easily obtain the resolution of the print data generated by the print data generation means by simply examining the minimum value of the empty space around the target dot, as in the case of the fourth aspect. Yes.
Further, since each means can be realized by software using a computer system provided in most printing apparatuses currently on the market as in the case of Form 8, dedicated hardware is created to create each of the above-mentioned means. It can be realized economically and easily as compared with the case of realizing the means.
Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 11] The computer-readable recording medium of mode 11 is
A computer-readable recording medium on which the printing program according to any one of forms 7 to 10 is recorded.
Accordingly, the printing program according to any one of forms 7 to 10 can be easily made available to users such as users via a computer-readable storage medium such as a CD-ROM, DVD-ROM, FD, or semiconductor chip. And can be provided reliably.

[Mode 12] The printing method of mode 12 is
Nozzle characteristic information acquisition step for acquiring nozzle characteristic information related to dot landing positions for each nozzle of a print head provided with a plurality of nozzles capable of sorting dots of different sizes, an image data acquisition step for acquiring image data, and the image data For each pixel of the image data acquired in the acquisition step, a print data generation step for generating printing data by setting a dot of a predetermined size based on the pixel value, and the print generated in the print data generation step A banding determination step for determining occurrence of a banding phenomenon when the print data is printed by the print head based on the data and the nozzle characteristic information of the print head acquired in the nozzle characteristic information acquisition step; and the banding determination step. It is determined that the banding phenomenon has occurred. A dot size correcting step for correcting the dot size related to the banding phenomenon when the printing operation is performed, and a printing step for executing printing based on the print data corrected in the dot size correcting step. It is.

  As in Form 1, it is possible to accurately determine the occurrence of the banding phenomenon, and to perform banding reduction processing only on the areas where “white streaks” and “dark streaks” are particularly noticeable. As compared with the case where the banding occurrence is uniformly performed, it is possible to realize an efficient printing process.

[Mode 13] The printing method of mode 13 is
In the printing method according to aspect 12, the relationship between the resolution of the print data generated in the print data generation step, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data Print data generated in the print data generation step based on the image quality determination information stored in the image quality determination information storage step, the image quality determination information storage step storing the recorded image quality determination information It is characterized by determining the occurrence of the banding phenomenon.
As a result, as in the case of the second aspect, it is possible to avoid an arbitrary (individual) banding phenomenon determination fluctuation (sway) and to objectively and accurately determine the occurrence of the banding phenomenon.

[Form 14] The printing method of form 14 is as follows:
In the printing method according to the thirteenth aspect, the image quality determination information storage step further stores image quality determination information in which the dot color of the print data generated in the print data generation step is recorded. It is.
As a result, similar to the third aspect, it is possible to avoid an arbitrary (individual) determination blurring (swing) that differs for each dot color, and to objectively and accurately determine the occurrence of the banding phenomenon.

[Mode 15] The printing method of mode 15 is
In the printing method according to the thirteenth or fourteenth aspect, the banding determination step obtains the resolution of the print data generated in the print data generation step from the minimum value of the empty space around the target dot. It is a feature.
As a result, it is possible to easily obtain the resolution of the print data generated by the print data generation means by simply examining the minimum value of the empty space around the dot of interest, as in the case of form 4, so that the processing can be performed more quickly. .

[Mode 16] An image processing apparatus according to mode 16
Nozzle characteristic information acquisition means for acquiring nozzle characteristic information related to the dot landing position for each nozzle of a print head provided with a plurality of nozzles that can divide dots of different sizes, and based on the pixel value for each pixel of the acquired image data Print data generation means for setting a dot of a predetermined size to generate data for printing, print data generated by the print data generation means, and nozzle characteristic information of the print head acquired by the nozzle characteristic information acquisition means Banding determination means for determining the occurrence of a banding phenomenon when the print data is printed by the print head based on the above, and the banding phenomenon when the banding determination means determines that the banding phenomenon has occurred. And dot size correction means for correcting the dot size involved. It is an butterfly.

This makes it possible to accurately determine the occurrence of the banding phenomenon and perform banding reduction processing only on areas where “white lines” and “dark lines” are particularly noticeable. On the other hand, it is possible to realize an efficient print data correction (creation) process as compared with a case where the process is uniformly performed.
Moreover, since each means can be implemented on software, it can be easily realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 17] An image processing apparatus according to mode 17
The relationship between the resolution of the print data generated by the print data generation unit, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data in the image processing device according to mode 16. The image quality determination information storage means for storing the image quality determination information recorded in the print data, and the banding determination means is the print data generated by the print data generation means based on the image quality determination information stored in the image quality determination information storage means. It is characterized in that the occurrence of the banding phenomenon is judged.

As a result, it is possible to avoid an arbitrary (individual) banding phenomenon determination shake, and to objectively and accurately determine the occurrence of the banding phenomenon.
Moreover, since each means can be implemented on software, it can be easily realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 18] An image processing apparatus according to mode 18
In the image processing apparatus according to the seventeenth aspect, the image quality determination information storage unit further stores image quality determination information in which the dot color of the print data generated by the print data generation unit is recorded. Is.

As a result, it is possible to avoid an arbitrary (individual) determination blur that varies for each dot color, and to objectively and accurately determine the occurrence of the banding phenomenon.
Moreover, since each means can be implemented on software, it can be easily realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 19] An image processing apparatus according to mode 19
In the image processing device according to Form 17 or 18, the banding determination unit obtains the resolution of the print data generated by the print data generation unit from the minimum value of the empty space around the target dot. It is characterized by.

As a result, the resolution of the print data generated by the print data generation means can be easily obtained simply by examining the minimum value of the empty space around the target dot, so that the data correction process can be performed more quickly.
Moreover, since each means can be implemented on software, it can be easily realized by an information processing apparatus such as a general-purpose personal computer.

[Mode 20] The image processing program of mode 20 is
Nozzle characteristic information acquisition means for acquiring dot characteristic information related to dot landing positions for each nozzle of a print head provided with a plurality of nozzles capable of sorting dots of different sizes, and for each pixel of the acquired image data A print data generation unit configured to set a dot of a predetermined size based on the value to generate print data, the print data generated by the print data generation unit, and the print head acquired by the nozzle characteristic information acquisition unit Banding determination means for determining occurrence of a banding phenomenon when the print data is printed by the print head based on nozzle characteristic information, and when the banding determination means determines that the banding phenomenon has occurred, Dot size correction means for correcting the dot size related to the banding phenomenon; It is characterized in that to to function.

As a result, it is possible to accurately determine the occurrence of the banding phenomenon as in the form 16, and to perform the banding reduction process only on the portion where “white streaks” and “dark streaks” are particularly noticeable. It is possible to realize an efficient print data correction (creation) process as compared with the case where the banding occurrence is uniformly performed.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC), it is more economical and easier than the case where the means are realized by creating dedicated hardware. Can be realized. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 21] The image processing program of mode 21 is
In the image processing program according to the form 20, the relationship between the resolution of the print data generated by the print data generation unit, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data The image quality determination information storage means for storing the image quality determination information recorded in the print data, and the banding determination means is the print data generated by the print data generation means based on the image quality determination information stored in the image quality determination information storage means. It is characterized in that the occurrence of the banding phenomenon is judged.

As a result, similarly to the seventeenth aspect, it is possible to avoid an arbitrary (individual) banding phenomenon determination fluctuation (vibration) and to objectively and accurately determine the occurrence of the banding phenomenon.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the form 21, compared with a case where dedicated hardware is created and each means is realized. Economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 22] The image processing program of mode 22 is
In the image processing program according to aspect 21, the image quality determination information storage unit further stores image quality determination information in which the dot color of the print data generated by the print data generation unit is recorded. Is.

As a result, similarly to the form 18, it is possible to avoid an arbitrary (individual) blurring (swing) that differs for each dot color, and to objectively and accurately determine the occurrence of the banding phenomenon.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the form 21, compared with a case where dedicated hardware is created and each means is realized. Economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Form 23] The image processing program of form 23 is
In the image processing program according to the form 21 or 22, the banding determination unit obtains the resolution of the print data generated by the print data generation unit from the minimum value of the empty space around the target dot. It is characterized by.

Thus, as in the form 19, it is possible to easily obtain the resolution of the print data generated by the print data generation means simply by examining the minimum value of the empty space around the target dot. It can be done more quickly.
Further, since each means can be realized by software using a general-purpose computer system such as a personal computer (PC) in the same manner as in the form 21, compared with a case where dedicated hardware is created and each means is realized. Economically and easily. Furthermore, it is possible to easily upgrade the version by modifying or improving the function by rewriting a part of the program.

[Mode 24] The computer-readable recording medium of mode 24 is
A computer-readable recording medium on which the image processing program according to any one of forms 20 to 23 is recorded.
As a result, the image processing program according to any one of the above forms 20 to 23 is sent to a user such as a user via a computer-readable storage medium such as a CD-ROM, DVD-ROM, FD, or semiconductor chip. It can be provided easily and reliably.

[Mode 25] An image processing method according to mode 25 is
A nozzle characteristic information acquisition step for acquiring nozzle characteristic information related to the dot landing position for each nozzle of a print head having a plurality of nozzles that can divide dots of different sizes, and based on the pixel value for each pixel of the acquired image data Print data generation step for generating print data by setting dots of a predetermined size, print data generated in the print data generation step, and nozzle characteristic information of the print head acquired in the nozzle characteristic information acquisition step Based on the banding determination step for determining the occurrence of the banding phenomenon when the print data is printed by the print head, and the banding phenomenon when the banding determination step determines that the banding phenomenon has occurred. Dot size compensation to correct the dot size involved And steps are those comprising a.

  As a result, it is possible to accurately determine the occurrence of the banding phenomenon as in the form 16, and to perform the banding reduction process only on the portion where “white streaks” and “dark streaks” are particularly noticeable. It is possible to realize an efficient print data correction (creation) process as compared with the case where the banding occurrence is uniformly performed.

[Mode 26] An image processing method according to mode 26 is
In the image processing method according to mode 25, the relationship between the resolution of the print data generated in the print data generation step, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data An image quality determination information storage step in which image quality determination information recorded is stored, and the banding determination step is a print generated in the print data generation step based on the image quality determination information stored in the image quality determination information storage step. It is characterized by determining occurrence of a data banding phenomenon.
As a result, similarly to the seventeenth aspect, it is possible to avoid an arbitrary (individual) banding phenomenon determination fluctuation (vibration) and to objectively and accurately determine the occurrence of the banding phenomenon.

[Mode 27] An image processing method according to mode 27 is
27. The image processing method according to claim 26, wherein the image quality determination information storage step further stores image quality determination information in which the dot color of the print data generated in the print data generation step is recorded. Is.
As a result, similarly to the form 18, it is possible to avoid an arbitrary (individual) blurring (swing) that differs for each dot color, and to objectively and accurately determine the occurrence of the banding phenomenon.

[Mode 28] An image processing method according to mode 28 is
In the image processing method according to Form 26 or 27, the banding determination step obtains the resolution of the print data generated in the print data generation step from the minimum value of the empty space around the target dot. It is characterized by.

  Thus, as in the form 19, it is possible to easily obtain the resolution of the print data generated by the print data generation means simply by examining the minimum value of the empty space around the target dot. It can be done more quickly.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.
1 to 25 show an embodiment relating to a printing apparatus 100, a printing program, a printing method, an image processing apparatus, an image processing program, an image processing method, and a computer-readable recording medium according to the present invention.
FIG. 1 is a functional block diagram showing an embodiment of a printing apparatus 100 according to the present invention.

  As shown in the figure, the printing apparatus 100 includes a print head 200 having a plurality of nozzles capable of sorting dots of different sizes, and nozzle characteristic information for acquiring nozzle characteristic information regarding the dot landing position for each nozzle of the print head 200. An acquisition unit 10, an image data acquisition unit 12 that acquires multi-value image data, and a dot of a predetermined size is set for each pixel of the image data acquired by the image data acquisition unit 12 based on the pixel value. Based on the print data generation means 14 for generating print data, the print data generated by the print data generation means 14 and the nozzle characteristic information of the print head 200 acquired by the nozzle characteristic information acquisition means 10. Banding for determining occurrence of banding phenomenon when the print data is printed by the print head 200 The determination unit 16, the dot size correction unit 18 that corrects the dot size related to the banding phenomenon based on the determination result of the banding determination unit 16, and the printing based on the print data corrected by the dot size correction unit 18 Ink-jet printing means 20 for executing the above, the resolution of the print data generated by the print data generation means 14, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data, The image quality determination information storage means 22 that stores the image quality determination information in which the relationship is recorded is mainly configured.

First, the print head 200 applied to the present invention will be described.
FIG. 3 is a partially enlarged bottom view showing the structure of the print head 200, and FIG. 4 is a partially enlarged side view thereof.
As shown in FIG. 3, the print head 200 has a long structure extending in the paper width direction of printing paper used in a so-called line head type printer, and has a nozzle N for discharging black (K) ink exclusively. A plurality (18 in the figure) of black nozzle modules 50 arranged in a straight line in the main scanning direction and a plurality of nozzles N dedicated to eject yellow (Y) ink are also arranged in a straight line in the main scanning direction. Yellow nozzle module 52, a plurality of nozzles N that specifically eject magenta (M) ink, and a magenta nozzle module 54 that is also linearly arranged in the main scanning direction, and cyan (M) ink exclusively Four nozzle modules 50, 52, 5 such as a cyan nozzle module 56 in which a plurality of nozzles N are arranged in a straight line in the main scanning direction. , 56 which are arranged integrally so as to overlap in the paper feeding direction (sub-scanning direction). In the case of a print head intended for monochrome, only the black (K) nozzle module, and in the case of a print head targeting a high-quality image, a nozzle module dedicated to ejecting ink such as light magenta or light cyan In some cases, 6-color or 7-color ink to which is added is used. In addition, the number of nozzles provided in one nozzle module is not particularly limited because it varies depending on the resolution. For example, in the case of a so-called multi-pass type as described later, In the case of the line head type, about 180 "pieces are often around a few hundred.

  FIG. 4 shows, for example, the black nozzle module 50, which is one of these four nozzle modules 50, 52, 54, and 56, from the side, and the sixth nozzle N6 from the left has a flight bend phenomenon. This shows a state in which ink is ejected obliquely from the nozzle N6 and dots are printed (ink landing) in the vicinity of the adjacent normal nozzle N7.

  Therefore, when printing is performed using the black nozzle module 50, as shown in FIG. 5, in the state where no flying curve occurs, all dots are printed at the specified printing position (ideal As shown in FIG. 6, for example, when the sixth nozzle N6 from the left has undergone a flight bending phenomenon, the dot printing position is a normal nozzle N7 next to the target printing position by a distance a. As a result, it is shifted to the side. In the examples of FIGS. 4 and 6, the case where only one nozzle causes the flight bending phenomenon has been described in order to explain the flight bending phenomenon in an easy-to-understand manner. The fact is that most of the nozzles cause a flight bend phenomenon to some extent.

Next, the nozzle characteristic information acquisition means 10 provides a function of acquiring nozzle characteristic information related to the dot landing position for each nozzle of the print head 200, and actual dots corresponding to the regular dot landing position for each nozzle. A function of detecting the landing position error (μm) and recording the information is exhibited.
FIG. 8 shows an example of a landing position error table 300 </ b> B showing dot landing position errors (amount of flight bending) of the print head 200 acquired by the nozzle characteristic information acquisition unit 10.

In the illustrated example, one print head 200 is provided with 180 nozzles per inch, and a unique nozzle number is assigned to each nozzle from “0” to “179”. The actual dot landing position error (flight curve amount) (μm) with respect to the regular dot landing position is recorded.
For example, the dot landing position errors of the nozzle number “0” and the nozzle number “1” are “1.94” and “11.1” in one direction of the main scanning direction (nozzle arrangement direction) with respect to the normal dot landing position, respectively. The dot landing position errors of the nozzle numbers “177” and “178” are the other directions (indicated by “−”) in the main scanning direction (nozzle arrangement direction) with respect to the regular dot landing positions, respectively. "(-) 0.04" and "(-) 3.83". In the example of FIG. 8, the landing position errors of the nozzle numbers “1” and “2” are particularly large as “11.42” and “16.03” compared to the other nozzles, and the portions corresponding to these nozzles. It is expected that a remarkable banding phenomenon will occur.

  Note that the flight bending directions of these nozzles actually include all 360 ° directions including not only the main scanning direction but also the sub-scanning direction (paper feeding direction), but the flight bending in the sub-scanning direction is a banding phenomenon. Is not so much affected, the landing position error only in the main scanning direction is shown in the example of FIG. Further, as shown in FIG. 1, the nozzle characteristic information acquisition unit 10 further includes a nozzle characteristic information storage unit 10a or a nozzle characteristic information detection unit 10b, which is stored in advance in the nozzle characteristic information storage unit 10a. Further, it is possible to easily acquire the nozzle characteristic information of the print head 200 at a necessary time by reading the characteristics of the print head 200 or reading the characteristics of the print head 200 detected by the nozzle characteristic information detection unit 10b. It is like that.

  Here, the nozzle characteristic information storage unit 10a reads, for example, a print head nozzle characteristic test result written when the print head 200 is manufactured or incorporated into the printing apparatus 100 (printing means 20). The nozzle characteristic information detection unit 10b includes a scanner such as a free ROM and a RAM. The nozzle characteristic information detection unit 10b scans the nozzle periodically or at a predetermined time to cope with a change in the nozzle characteristic of the print head 200 after use. The characteristics of the print head 200 are inspected from the print result by the print head 200 using an optical print result reading means such as a means, and the inspection result is combined with the data of the nozzle characteristic information storage unit 10a or the data. It is to be saved by overwriting. The characteristics of the print head 200 are fixed to some extent at the manufacturing stage, and it is considered that it is relatively rare to change after manufacturing, except for ejection failures due to ink clogging.

  Next, the image data acquisition means 12 network multi-valued color image data to be used for printing sent from a printing instruction device (not shown) such as a personal computer (PC) or a printer server connected to the printing device 100 over a network. Etc., or a function to read and acquire directly from an image (data) reading device such as a scanner or a CD-ROM drive (not shown), and to obtain a multi-valued color image If the data is multi-value RGB data, for example, image data in which the gradation (luminance value) for each color (R, G, B) per pixel is represented by 8 bits and 256 gradations (0 to 255), A function of converting this into multi-value CMYK (in the case of four colors) data corresponding to each ink of the print head 200 is also exhibited at the same time. That.

The print data generation unit 14 generates N-valued data by converting the multivalued image data acquired by the image data acquisition unit 12 into N-valued data, and a dot of a predetermined size for each pixel of the N-valued data. A function for generating data for printing by setting is provided.
In other words, the print data generation unit 14 specifies the pixel value (density or luminance) of each pixel of the image data acquired by the image data acquisition unit 12 with 8 bits (0 to 256 gradations), for example. When this is converted into four values, the pixel values of each pixel are classified into four gradations using three threshold values as shown in the dot / gradation conversion table 300A of FIG.

First, the right column of the dot / gradation conversion table 300A in FIG. 7 shows the relationship between the threshold value and each pixel value when the multivalued pixel value is converted into a quaternary value.
According to the dot / conversion table 300A, when the pixel value (density value) of each pixel of multi-valued image data is specified by 8 bits and 256 gradations (0 to 255), “42 (first threshold value) ) ”,“ 126 (second threshold) ”,“ 210 (third threshold) ”, and when the pixel value is“ 0 to 42 ”, the gradation value is 1 (density“ 0 ”). When the pixel value is “43 to 126”, the gradation value is 2 (density “84”), and when the pixel value is “127 to 210”, the gradation value is 3 (density “168”), the pixel When the value is “211 to 255”, the gradation value is 4 (density “255”), and the four values are obtained.

The print data generation unit 14 further sets a corresponding dot for each pixel of the N-valued data that is N-valued for each pixel in this way, and uses it in the inkjet printing unit 20. Generate data for printing.
The left column of the dot / gradation conversion table 300A in FIG. 7 is a reference diagram showing the relationship between the gradation value of each pixel of the N-ary data previously performed and the dot size.

  In the example of the figure, the dot size in the case of the gradation value “1” regarding the density value is “no dot”, and the dot size in the case of the gradation value “2” is the “small dot” (dot diameter) with the smallest dot diameter. The dot size in the case of the gradation value “3” is “medium dot” (dot diameter: 60 μm) slightly larger than the small dot, and the dot size in the case of the gradation value “4” is dot size. Are converted into “large dots” (dot diameter: 90 μm). When a “brightness value” is used as the pixel value, each pixel value is converted into a dot having a reverse relationship to the “density value”.

  Next, the banding determination unit 16 will be described in detail later. The print data generated by the print data generation unit 14 and the nozzle characteristic information of the print head 200 acquired by the nozzle characteristic information acquisition unit 10 are described below. As shown in FIG. 9 and the like, a function for determining occurrence of a banding phenomenon when the print data is printed by the print head 200 is provided.

The dot size correction means 18 will be described in detail later, but based on the determination result of the banding determination means 16, the dot size involved in the banding phenomenon is changed to the original size as shown in FIGS. Provides the ability to correct (change) to different sizes.
The printing means 20 is configured to dot ink from each nozzle of the nozzle modules 50, 52, 54, and 56 formed on the print head 200 while moving one or both of the print medium (paper) S and the print head 200. In addition to the print head 200 described above, the print head 200 is placed on the print medium S to form a predetermined image consisting of a large number of dots on the print medium S. A print head feeding mechanism (not shown) that reciprocates the paper in the width direction (multi-pass type), a paper feeding mechanism (not shown) for moving the print medium S, and the ink of the print head 200 based on the printing data. It comprises known components such as a print controller mechanism (not shown) that controls the discharge.

The image quality determination information storage unit 22 indicates the relationship between the resolution of the print data generated by the print data generation unit 14, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data. The recorded image quality determination information is stored, and the image quality determination information is provided to the banding determination means 16 as necessary.
FIG. 12 shows an example of the data structure of the image quality determination information. In the figure, the X-axis is the dot recording pitch equal to the resolution of the print head 200, the Y-axis is the dot diameter, and Z in the figure. The axis indicates the accuracy of the direct bullet position error (flight curve amount).

  FIG. 14 shows three types of recording pitches (μm) and three types of dot diameters (μm) when the accuracy of the direct bullet position error defined on the Z axis is (±) 10 μm. ) Shows an example of the inspection patch showing the relationship with A solid image is printed for each combination of the three factors of the recording pitch / dot diameter that can be realized by the printing means 20 and the landing position error accuracy, and the combination is measured to determine how many people can actually perceive the banding phenomenon. Is for. Note that the lightness and darkness of the squares in the figure corresponds to the actual color density of the printed matter, and the darker the portion, the darker the color is printed.

In general, the banding phenomenon associated with the flight bend phenomenon tends to be inconspicuous in the low concentration region and the high concentration region and is most noticeable in the intermediate concentration region when the flight bend amount is constant. The actual density of the printed matter is determined according to the relationship between the recording pitch and the dot diameter.
Accordingly, as shown in the figure, for example, in the case of the “large dot (dot diameter 90 μm)” having the largest dot diameter, when the recording pitch is low resolution (180 dpi), the landing position error (± 10 μm) with respect to the recording pitch. ) Is relatively small, the banding phenomenon is hardly noticeable. However, when the intermediate resolution (360 dpi) is reached, the landing position error (± 10 μm) increases with respect to the recording pitch, so that the banding phenomenon is conspicuous. Become. However, when the recording pitch is further reduced and the resolution becomes high (720 dpi), the gap between the dots disappears, the dots partially overlap each other and the ground color of the printing medium cannot be seen, and the landing position error is about ± 10 μm. Even if it occurs, the background color of the print medium remains invisible, so the banding phenomenon becomes almost inconspicuous.

FIG. 15 and FIG. 16 are schematic diagrams showing such a phenomenon more easily.
First, FIG. 15 shows dot patterns of medium resolution (360 dpi: 70.6 μm) and low resolution (180 dpi: 141 μm) using medium dots having a dot diameter of 60 μm.
FIG. 16 shows that in the dot pattern having such a relationship, the nozzle corresponding to the second dot from the left causes a flight curve in the main scanning direction, and the landing position of the dot corresponding to the nozzle is shifted to the right by 10 μm. It shows the state that has been.

In such a case, as shown in FIG. 16, in the intermediate resolution area (360 dpi), a part of the dot whose landing position has shifted is overlapped with the adjacent dot on the right side, and a dark vertical stripe is generated in that part. It can be seen that the distance from the adjacent dot to the left increases and white vertical streaks appear in that area.
On the other hand, in the low resolution area (360 dpi), even if such a landing position shift occurs, the positional relationship with the surrounding dots hardly changes, so the same amount as the intermediate resolution area (360 dpi). It can be seen that even if a landing position error occurs, the banding phenomenon is hardly noticeable.

  FIG. 13 shows an example of an image quality deterioration value graph showing the relationship between the recording pitch of the area indicated by the dotted arrow in FIGS. 12 and 14 and the image quality deterioration value (ease of conspicuous banding phenomenon (streaks)). The image quality degradation value is low in the area where the recording pitch is small (high resolution area) and in the area where the recording pitch is large (low resolution area), and the recording pitch is the highest in the intermediate area (intermediate resolution area). Is shown.

  The image quality determination information in FIGS. 12 to 14 shows the case where the ink (dot) color is black. Such image quality determination information is the color of the print head 200 capable of color printing. Each image quality determination information (for example, image quality determination information for yellow, image quality determination information for magenta, image quality determination information for cyan, image quality determination information for light magenta, etc.) is stored and saved.

  Here, the printing apparatus 100 according to the present embodiment having such a configuration includes various controls for printing, the nozzle characteristic information acquisition unit 10, the image data acquisition unit 12, the print data generation unit 14, and the dot size correction unit. 18 includes a computer system for realizing the printing means 20, the image quality determination information storage means 22 and the like on software, and the hardware configuration thereof is a central operation for various controls and arithmetic processing as shown in FIG. Between a CPU (Central Processing Unit) 60 that is a processing device, a RAM (Random Access Memory) 62 that constitutes a main storage device (Main Storage), and a ROM (Read Only Memory) 64 that is a read-only storage device. PCI (Peripheral Com It is connected to various internal and external buses 68 such as a point interconnect (ISA) bus and an ISA (Industrial Standard Architecture) bus, and is connected to the bus 68 via an input / output interface (I / F) 66 and an external device such as an HDD (Hard Disk Drive). A network for communicating with a storage device (Secondary Storage) 70, an output device 72 such as a printing means 20, a CRT, and an LCD monitor, an input device 74 such as an operation panel, a mouse, a keyboard, and a scanner, and a print instruction device (not shown). L or the like is connected.

  When the power is turned on, a system program such as BIOS stored in the ROM 64 or the like is stored in various dedicated computer programs stored in the ROM 64 in advance, or in a CD-ROM, DVD-ROM, flexible disk (FD), or the like. Various dedicated computer programs installed in the storage device 70 via the medium or the communication network L such as the Internet are similarly loaded into the RAM 62, and the CPU 60 performs various operations according to instructions described in the program loaded in the RAM 62. Each function of each means as described above can be realized on software by making full use of resources and performing predetermined control and arithmetic processing.

Next, an example of the flow of printing processing using the printing apparatus 100 configured as described above will be described with reference mainly to the flowcharts of FIGS.
Note that the flowchart in FIG. 17 shows an example of the overall flow of the printing process, FIG. 18 shows the flowchart of the example of the banding determination process in step S104 in FIG. 17, and FIGS. The flowchart of 20 shows an example of the flow of the dot size correction process. In addition, as described above, the print head 200 for printing dots generally can print dots of a plurality of types of colors such as four colors and six colors almost simultaneously, but in the following example, the explanation is easy to understand. Therefore, it is assumed that each dot is printed by any one (single color) print head 200 (monochrome image).

  First, as shown in the flowchart of FIG. 17, after a predetermined initial operation for printing processing is completed after the power is turned on, the printing apparatus 100 proceeds to the first step S100 and displays a personal computer or the like. If the print instruction terminal is not connected, the image data acquisition unit 12 monitors whether there is an explicit print instruction from the print instruction terminal. Along with the print instruction, it is determined whether multi-value image data to be printed has been sent.

  As a result, for example, when it is determined that the predetermined image data has not been sent even after a predetermined time, the processing is terminated as it is, but when it is determined that the predetermined image data has been transmitted within the predetermined time. The image data acquisition means 12 acquires the image data and proceeds to the next step S102, and the print data generation means 14 determines the image based on the dot / gradation conversion table 300A as shown in FIG. Generate print data from the data.

At this time, when the image data acquired by the image data acquisition means 12 is multi-value RGB data, as described above, this is converted to multi-value CMYK data corresponding to the ink used based on a predetermined conversion algorithm. The conversion process is also performed at the same time.
When the print data to be processed is generated in this way, the process proceeds to the next step S104, and the print data is based on the nozzle characteristic information acquired by the nozzle characteristic information acquisition unit 10 by the banding determination unit 16. Perform the banding judgment process.

In this banding determination process, first, as shown in step S200 of FIG. 18, a predetermined target pixel in the print data to be determined is determined, and the recording pitch (Pmn) of the unit area of the target pixel is calculated. The resolution of the unit area is obtained.
The method for calculating the resolution of the print data in step S200 is not particularly limited. For example, as shown in FIGS. 21A to 21C, the standard recording pitch of the print head 200 and the pixel P of interest are set. It can be obtained from the relationship with the left and right (surrounding) minimum values.

  FIG. 21A shows a state in which one left and right of the target pixel P are vacant, and the recording pitch (resolution) of the unit area of the target pixel P is a recording pitch of standard recording pitch / 2. (Pmn). FIG. 21B shows a state in which two pixels on the left and right of the target pixel P are vacant, and the recording pitch (resolution) of the region of the target pixel P is a recording with a standard recording pitch / 3. This is the pitch (Pmn).

Note that, as shown in FIG. 21C, when the left side of the target pixel P is vacant by one and the right side is vacant by two, the minimum value of the vacant is the one of the left side of the target pixel P. Therefore, the recording pitch in this case is the recording pitch (Pmn) of the standard recording pitch / 2 as in the case of FIG.
As another method for calculating the resolution of the print data in step S200, not only the left and right as described above, but also the minimum empty space around the target pixel P including the vertical and horizontal directions of the target pixel P and the diagonal 45 ° direction. It can be obtained from the relationship with the value. That is, with respect to the vertical direction of the target pixel P, the same algorithm as the above left and right can be used. The same algorithm can be used as long as

  When the recording pitch (Pmn) of the unit area of the target pixel is calculated in this way, the process proceeds to the next step S202, and the print head 200 responsible for the target pixel by the nozzle characteristic information acquisition means 10 is obtained. The characteristic information of the nozzle is read out, and the landing position error (Emn) of the dot printed by the nozzle is obtained. Then, the process proceeds to the next step S204, and the dot diameter (Rmn) corresponding to the pixel value of the target pixel. ).

If the recording pitch (Pmn) of the unit area of the target pixel, the landing position error (Emn) of the dot corresponding to the target pixel, and the dot diameter (Rmn) of the target pixel are thus obtained. For example, the process proceeds to the next step S206, and the image quality deterioration value (Qmn = f (Pmn-Rmn-Emn)) of the unit area of the target pixel is obtained from these three functions.
Here, the image quality degradation value is an index indicating the conspicuousness of streaks (“white streaks” and “dark streaks”) due to the banding phenomenon, and a threshold value th is set to a certain value as shown in FIG. The threshold value th is used as a criterion for determining whether or not subsequent dot size correction is necessary.

  When the predetermined image quality degradation value (Qmn) is obtained in this way, the process proceeds to the last step S208, where it is determined whether or not the image quality degradation value (Qmn) exceeds a predetermined threshold th. When it is determined that the threshold value th is not exceeded (No), regarding the unit area of the target pixel, it is assumed that a particularly noticeable banding phenomenon has not occurred, and a subsequent dot size correction process (banding phenomenon reduction process) is performed. When it is determined that the image quality degradation value (Qmn) exceeds the threshold value th (No), a noticeable banding phenomenon has occurred in the unit area of the target pixel. Therefore, it is determined that the subsequent dot size correction process (banding phenomenon reduction process) is necessary, and the banding determination process is terminated.

Returning to the flow of FIG. 17, when the banding determination process in step S104 is completed in this way, the process proceeds to the next step S106 and the banding is performed for the unit area determined to require the dot size correction process. A dot size correction process is executed to reduce the phenomenon.
In the dot size correction process in step S106, as shown in the flow of FIG. 19, first, in the first step S300 and step S302, attention is focused on the Y coordinate (main scanning direction) and the X coordinate (sub scanning direction). It is determined whether or not there is a pixel. When it is determined that there is any pixel (Yes), the process proceeds to step 304 to determine whether or not the target pixel is a dot size correction target pixel.

As a result of this determination processing, when it is determined that the pixel is not the dot size correction target pixel (No), the process returns to step S302. However, when it is determined that the pixel is the dot size correction target pixel (Yes), the next step In step S306, the dot size changing process is performed on the target pixel.
Here, the dot size changing process in step S306 is not particularly limited, and a known method can be used. For example, as shown in FIG. 9, the target pixel causes a flight curve. If it is one of the dots (rows), the dot size is reduced by one ("medium dot" → "small dot").

As a result, as shown in FIG. 10, the overlap between the dot corresponding to the target pixel and the adjacent dot on the right side is avoided, and the “dark streaks” of the banding phenomenon that has occurred in the overlapped portion can be eliminated. it can.
Further, as shown in FIG. 9, when the target pixel is one of the normal dots (rows) located on the left side of the dot (row) causing the flight curve, the dot size is increased by one size. ("Medium dot" → "large dot").

As a result, as shown in FIG. 11, “white streaks” can be eliminated from the banding phenomenon occurring between the dot corresponding to the target pixel and the dot causing the flight bending phenomenon.
In addition, by making the dot size of the dots near the flying bent dots downsized in this way larger than the original size, it becomes possible to compensate for the error density of that part, and the original area gradation of the unit region can be adjusted. It can also be maintained.

In addition to this example, as the dot size changing process in step S306, for example, the size of the left and right dots can be changed while leaving the size of the dot (row) causing the flying curve unchanged, Or there are various methods depending on the dot size, such as eliminating some of the dots.
In addition, the necessity of correction is determined based on the threshold th, and if “necessary”, the image quality deterioration value (Qmn) is changed such that the strength of correction is changed according to the magnitude of the image quality deterioration value (Qmn). It can also be used.

In the dot size correction process shown in FIG. 19, it is determined whether or not all pixels are pixels subject to dot size correction. In this determination, the nozzle characteristic information acquisition means 10 is used. If the determination is made by taking into account the nozzle characteristic information acquired by the above, more efficient processing can be performed.
FIG. 20 shows a dot size in which whether or not the pixel of interest in the unit area is a pixel to be corrected for dot size is determined by taking into account the nozzle characteristic information acquired by the nozzle characteristic information acquisition unit 10 in this way. An example of a correction process is shown.

  That is, first, in step S400, the nozzle characteristic information acquired by the nozzle characteristic information acquisition means 10 is acquired, and then the process proceeds to the next step S402 to determine whether or not there is a next pixel in the Y coordinate (main scanning direction). When it is determined that there is no (no), the process is terminated as it is. When it is determined that there is (Yes), the process proceeds to the next determination step S404, and the characteristics of the nozzle corresponding to the next pixel are determined. It is determined whether or not (the amount of flight bend) is equal to or greater than the threshold “th1”. Here, the threshold value “th1” is not particularly limited, but empirically speaking, in consideration of variations in the degree of flight bending (± 2 to 3 μm), errors in paper feed accuracy, and the like, Since the flight bend amount of about 6 μm or less is not worth performing dot size correction processing, for example, about “6 μm” may be set as the threshold th1.

  Then, in this determination step S404, when it is determined that the characteristic of the nozzle corresponding to the target pixel is equal to or greater than the threshold “th1” (Yes), in the same manner as in the processing flow shown in FIG. The process proceeds to step S408 and step S410, and similar processing is performed. However, when it is determined in this determination step S404 that the characteristic of the nozzle corresponding to the target pixel is not equal to or greater than the threshold “th1” (No). Then, the subsequent process is omitted, and the process returns to the original step S402 and the same determination process is performed for the pixel of the next Y coordinate.

As a result, useless determination processing is omitted, and efficient dot size change processing can be performed.
As described above, the printing apparatus 100 according to the present invention can accurately determine and determine the occurrence of the banding phenomenon and its location.
This makes it possible to perform banding reduction processing only on areas where “white streaks” and “dark streaks” are particularly noticeable, so it is more efficient than if all bands are generated uniformly. Printing process can be realized.

  FIG. 22 shows an example of print pattern image data, in which data of luminance value “85” (256 gradations) is arranged in the center “180 × 180 (pixels)” area. , “Large”, “Medium”, “Small” dot size (inkjet) nozzles, and “180 × 180” “medium dots” for each pixel. There are the scales on the left and right of the figure for visually reading the line number (corresponding nozzle number) when the print result is markedly scanned.

FIG. 23 shows a print result of the print pattern of FIG. In general, when printing is performed without performing various corrections performed by the printer driver, variations in landing accuracy appear remarkably, and dark stripes and white stripes, which are one of the banding phenomena, occur. For example, the places marked with markers A and B are examples of portions where dark streaks are generated.
FIG. 24 is an enlarged image of a part of the lines of the markers A and B. Such a streak is caused by the dots being in contact with each other due to the flying bending phenomenon of ink as described above, and can be clearly recognized as a dark streak.

  In addition, as described above, the technique of dividing the dot size in one printed matter is a conventionally known technique, and is a technique that is frequently used particularly for obtaining a printed matter that achieves a high balance between printing speed and print image quality. . In other words, high image quality can be obtained by reducing the dot size, but high performance is required for machine accuracy when the dot size is reduced, and it is necessary to hit many dots to form a solid image with small dots. There is. Therefore, the printing speed and the image quality are realized with a high balance by using a dot size sorting technique such as reducing the dot size for a high-detail image portion and increasing the dot size for a solid image portion.

In addition, as a technical method for realizing the dot size sorting in this way, for example, in the case of a method using a piezo actuator for a print head, the voltage applied to the piezo element is changed to eject ink. It can be easily realized by controlling the amount.
Further, as shown in FIG. 7, there are four patterns of “large dots”, “medium dots”, “small dots”, and “no dots” as the sizes of dots to be sorted by the present invention and the normal print head 200. Although it is general, the kind of the dot size is not limited to this, and it is sufficient that there are at least two patterns other than “no dot”.

  Further, the print head 200 and the nozzle characteristic information acquisition unit 10 in the present embodiment correspond to the print head and the nozzle characteristic acquisition unit in the printing apparatus of the first embodiment described in the section for solving the problem, respectively. The image data acquisition unit 12 corresponds to the image data acquisition unit in the printing apparatus such as the first mode. The print data generation 14, the banding determination unit 16, the dot size correction unit 18, and the printing unit 20 correspond to print data generation, banding determination unit, dot size correction unit, and printing unit in the printing apparatus of the first aspect, respectively. The image quality determination information storage unit 22 corresponds to the image quality determination information storage unit in the second embodiment.

  The present invention is characterized in that the occurrence of the banding phenomenon is determined based on the print data and the nozzle characteristic information with almost no modification to the existing print head 200 and the printing means 20 itself. It is not necessary to prepare a dedicated one as the printing unit 20 or the like, and the existing ink jet type print head 200 and the printing unit 20 (printer) can be used as they are.

Therefore, if the print head 200 and the printing unit 20 are separated from the printing apparatus 100 of the present invention, the function can be realized only by a general-purpose information processing apparatus (image processing apparatus) such as a personal computer.
Further, the image data acquisition unit 12 and the print data generation unit 14 are separated and processed by another information processing apparatus, and the nozzle characteristic information acquisition unit 10, the banding determination unit 16, and the dot size correction unit 18 are used as one piece of information. You may make it implement | achieve with a processing apparatus.

  Further, the present invention is not limited to the flight bend phenomenon, but the ink ejection direction is vertical (normal), but the nozzle formation position is deviated from the normal position. As a result, the dots formed are the same as the flight bend phenomenon. Of course, the present invention can be applied in exactly the same manner. Furthermore, the present invention can be similarly applied to a problem in which ink is not discharged from a specific nozzle due to ink clogging or the like.

  Further, the printing apparatus 100 of the present invention can be applied not only to a line head type ink jet printer but also to a multi-pass type ink jet printer. If the line head type ink jet printer is used, a flight bending phenomenon occurs. However, it is possible to obtain a high-quality printed matter with almost no noticeable white or dark streaks in one pass, and a multi-pass ink jet printer can reduce the number of reciprocating operations. High-speed printing is also possible. For example, when a desired image quality can be realized by one printing, the printing time can be shortened to 1 / K as compared with the case where printing is performed by K reciprocating printing.

FIG. 25 shows respective printing methods using a line head type ink jet printer and a multi-pass type ink jet printer.
As shown in FIG. 3A, when the width direction of the rectangular printing paper P is the main scanning direction of the image data and the longitudinal direction is the sub-scanning direction of the image data, the line head type inkjet printer As shown in (B), the print head 200 has a length corresponding to the paper width of the printing paper S, the printing head 200 is fixed, and the printing paper S is sub-scanned with respect to the printing head 200. The printing is completed in one pass (operation) by moving in the direction. It is also possible to perform printing while fixing the printing paper S and moving the print head 200 side in the sub-scanning direction or moving both in the opposite direction as in a so-called flatbed scanner. It is. On the other hand, in the multi-pass type ink jet printer, as shown in FIG. 5C, the print head 200, which is much shorter than the paper width, is positioned in the direction perpendicular to the main scanning direction. Printing is executed by moving the printing paper S in the sub-scanning direction by a predetermined pitch while reciprocating in the main scanning direction many times. Therefore, the latter multi-pass type ink jet printer has a drawback that it takes longer printing time than the former line head type ink jet printer, but the print head 200 can be repeatedly positioned at an arbitrary position. Among the banding phenomenon as described above, it is possible to cope to some extent with respect to the reduction of the white streak phenomenon.

In this embodiment, an ink jet printer that performs printing by ejecting ink in dots has been described as an example. However, the present invention is another printing apparatus that uses a print head in which printing mechanisms are arranged in a line. For example, the present invention is also applicable to a thermal head printer called a thermal transfer printer or a thermal printer.
In FIG. 3, each nozzle module 50, 52, 54, 56 provided for each color of the print head 200 has a form in which the nozzles N are linearly continuous in the longitudinal direction of the print head 200. 26, each of these nozzle modules 50, 52, 54, 56 is composed of a plurality of short nozzle units 50a, 50b,... 50n, which are arranged before and after the movement direction of the print head 200. You may comprise as follows. In particular, if each nozzle module 50, 52, 54, 56 is configured with a plurality of short nozzle units 50a, 50b,... 50n, the yield is significantly higher than that of a long nozzle unit. improves.

  Each means for realizing the printing apparatus 100 of the present invention described above can be realized on software using a computer system incorporated in most existing printing apparatuses. In addition to being stored in a semiconductor ROM in advance in a product or distributed via a network such as the Internet, a computer-readable recording medium R such as a CD-ROM, DVD-ROM, or FD as shown in FIG. It is possible to easily provide it to a desired user or the like.

1 is a functional block diagram illustrating an embodiment of a printing apparatus according to the present invention. It is a block diagram which shows the hardware constitutions of the computer system which implement | achieves the printing apparatus which concerns on this invention. FIG. 4 is a partially enlarged bottom view showing the structure of the print head according to the present invention. It is a partial enlarged side view showing the structure of the print head according to the present invention. It is a conceptual diagram which shows an example of the ideal dot pattern in which a flight bending phenomenon does not generate | occur | produce. It is a conceptual diagram which shows an example of the dot pattern formed by the flight curve phenomenon of one nozzle. 6 is a dot / gradation conversion table showing a conversion relationship between pixel values, gradation values, and dot sizes. It is a landing position error amount recording table showing the relationship between the nozzle and the flight bending amount. It is a schematic diagram which shows the relationship between a flight bending phenomenon and resolution (recording pitch). It is a schematic diagram which shows an example of a dot size correction process. It is a schematic diagram which shows an example of a dot size correction process. It is a figure which shows an example of the data structure of image quality determination information. It is a graph which shows the relationship between an image quality degradation value and its image quality degradation value, and a threshold value. It is an inspection patch showing the relationship between the recording pitch and the dot diameter when the landing position error accuracy is fixed. It is a schematic diagram which shows the relationship between an ideal dot pattern and resolution. It is a schematic diagram which shows the relationship between the dot pattern of the state in which the flight bending phenomenon occurred, and the resolution. FIG. 5 is a flowchart illustrating a flow of overall printing processing of the printing apparatus of the present invention. It is a flowchart figure which shows the flow of a banding determination process. It is a flowchart figure which shows an example of the flow of a dot size correction process. It is a flowchart figure which shows the other example of the flow of a dot size correction process. It is explanatory drawing which shows an example of the calculation method of a recording pitch. It is a figure which shows the image data of a printing pattern. It is a figure which shows the printing result of FIG. It is an enlarged image of the marker part of FIG. It is explanatory drawing which shows the difference in the printing system by a multipass type | mold inkjet printer and a line head type inkjet printer. It is a conceptual diagram which shows the other example of the structure of a print head. It is a conceptual diagram which shows an example of the computer-readable recording medium which recorded the program which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Printing apparatus, 200 ... Print head, 300A ... Dot / tone conversion table, 300B ... Landing position error (flight curve amount) recording table, 10 ... Nozzle characteristic information acquisition means, 10a ... Nozzle characteristic information recording unit, 10b ... Nozzle characteristic information detection unit, 12 ... Image data acquisition means, 14 ... Print data generation means, 16 ... Banding determination means, 18 ... Dot size correction means, 20 ... Printing means, 22 ... Image quality determination information storage means, ... Print head characteristics Storage unit 26... Print head characteristic detection unit 60... CPU, 62... RAM, 64... ROM, 66... Interface, 70. Yellow nozzle module, 54 ... Magenta nozzle module, 56 ... Cyan nozzle module, P ... Image , S ... print medium (paper), N ... nozzle, R ... recording medium, P ... pixel of interest.

Claims (13)

A print head equipped with a plurality of nozzles capable of sorting dots of different sizes;
Nozzle characteristic information acquisition means for acquiring nozzle characteristic information related to the dot landing position for each nozzle of the print head;
Image data acquisition means for acquiring image data;
Print data generation means for setting a dot of a predetermined size based on the pixel value for each pixel of image data acquired by the image data acquisition means and generating data for printing;
Determination of occurrence of banding phenomenon when the print data is printed by the print head based on the print data generated by the print data generation unit and the nozzle characteristic information of the print head acquired by the nozzle characteristic information acquisition unit Banding determination means to perform,
Dot size correcting means for correcting the dot size related to the banding phenomenon when it is determined by the banding determining means that the banding phenomenon has occurred;
And a printing unit that executes printing based on the print data corrected by the dot size correction unit. The printing apparatus according to claim 1,
Image quality that stores image quality determination information that records the relationship between the resolution of the print data generated by the print data generation means, the dot size of each dot of the print data, and the landing accuracy information for each dot of the print data A determination information storage means;
The banding determination unit is configured to determine the occurrence of a banding phenomenon in the print data generated by the print data generation unit based on the image quality determination information stored in the image quality determination information storage unit. Printing device to do. The printing apparatus according to claim 2,
The image quality determination information storage means further stores image quality determination information in which the dot color of the print data generated by the print data generation means is recorded. The printing apparatus according to claim 2 or 3,
The printing apparatus, wherein the banding determination means obtains the resolution of the print data generated by the print data generation means from the minimum value of the empty space around the target dot. The printing apparatus according to any one of claims 1 to 4,
The printing apparatus, wherein the print head is a line head type print head. The printing apparatus according to any one of claims 1 to 4,
The printing apparatus, wherein the print head is a multi-pass print head. Computer
Nozzle characteristic information acquisition means for acquiring nozzle characteristic information related to dot landing positions for each nozzle of a print head provided with a plurality of nozzles capable of differentiating dots of different sizes;
Image data acquisition means for acquiring image data;
Print data generation means for setting a dot of a predetermined size based on the pixel value for each pixel of image data acquired by the image data acquisition means and generating data for printing;
Determination of occurrence of banding phenomenon when the print data is printed by the print head based on the print data generated by the print data generation unit and the nozzle characteristic information of the print head acquired by the nozzle characteristic information acquisition unit Banding determination means to perform,
Dot size correcting means for correcting the dot size related to the banding phenomenon when it is determined by the banding determining means that the banding phenomenon has occurred;
A printing program that functions as a printing unit that executes printing based on print data corrected by the dot size correction unit.   A computer-readable recording medium on which the printing program according to claim 7 is recorded. Nozzle characteristic information acquisition step for acquiring nozzle characteristic information related to dot landing positions for each nozzle of a print head provided with a plurality of nozzles that can divide dots of different sizes;
An image data acquisition step for acquiring image data;
A print data generation step for setting a dot of a predetermined size for each pixel of the image data acquired in the image data acquisition step and generating data for printing;
Determination of occurrence of a banding phenomenon when the print data is printed by the print head based on the print data generated in the print data generation step and the nozzle characteristic information of the print head acquired in the nozzle characteristic information acquisition step. Banding judgment step to
A dot size correction step for correcting the dot size involved in the banding phenomenon when it is determined in the banding determination step that the banding phenomenon has occurred;
And a printing step for executing printing based on the print data corrected in the dot size correction step. Nozzle characteristic information acquisition means for acquiring nozzle characteristic information related to dot landing positions for each nozzle of a print head provided with a plurality of nozzles capable of differentiating dots of different sizes;
Print data generating means for generating data for printing by setting dots of a predetermined size based on the pixel value for each pixel of the acquired image data;
Determination of occurrence of banding phenomenon when the print data is printed by the print head based on the print data generated by the print data generation unit and the nozzle characteristic information of the print head acquired by the nozzle characteristic information acquisition unit Banding determination means to perform,
An image processing apparatus comprising: a dot size correcting unit that corrects a dot size related to a banding phenomenon when it is determined by the banding determining unit that a banding phenomenon has occurred. Computer
Nozzle characteristic information acquisition means for acquiring nozzle characteristic information related to dot landing positions for each nozzle of a print head provided with a plurality of nozzles capable of differentiating dots of different sizes;
Print data generating means for generating data for printing by setting dots of a predetermined size based on the pixel value for each pixel of the acquired image data;
Determination of occurrence of banding phenomenon when the print data is printed by the print head based on the print data generated by the print data generation unit and the nozzle characteristic information of the print head acquired by the nozzle characteristic information acquisition unit Banding determination means to perform,
An image processing program that functions as a dot size correction unit that corrects a dot size related to a banding phenomenon when it is determined by the banding determination unit that a banding phenomenon has occurred.   The computer-readable recording medium which recorded the image processing program of Claim 11. Nozzle characteristic information acquisition step for acquiring nozzle characteristic information related to dot landing positions for each nozzle of a print head provided with a plurality of nozzles that can divide dots of different sizes;
A print data generation step for generating print data by setting a dot of a predetermined size based on the pixel value for each pixel of the acquired image data;
Determination of occurrence of a banding phenomenon when the print data is printed by the print head based on the print data generated in the print data generation step and the nozzle characteristic information of the print head acquired in the nozzle characteristic information acquisition step. Banding judgment step to
And a dot size correcting step of correcting a dot size related to the banding phenomenon when it is determined in the banding determining step that the banding phenomenon has occurred.

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