Printing device, program for controlling printing device, method of controlling printing device, printing data creating device, program for controlling printing data and method of creating printing data

RELATED APPLICATIONS

This application claims priority to Japanese Patent Application Nos. 2005-072423 filed Mar. 15, 2005 and 2005-353529 filed Dec. 7, 2005 which are hereby expressly incorporated by reference herein in their entirety.

BACKGROUND

1. Technical Field

The present invention relates to a printing device used for a facsimile device, a copy machine, an office automation (OA) device, or the like, a program for controlling a printing device, and a method of controlling a printing device. More particularly, the present invention relates to a printing device suitable for a so-called inkjet type printing process for ejecting minute particles of a plurality of colors of liquid ink onto printing paper (recording material) so as to draw a predetermined character or image, a program for controlling a printing device, a method of controlling a printing device, a printing data creating device, a program for creating printing data, and a method of creating printing data.

2. Related Art

Hereinafter, a printing device, particularly, an inkjet type of printer (hereinafter, referred to as ‘inkjet printer’) will be described.

Generally, since the inkjet printer has merits in that it is inexpensive and a color printing material of a high quality can be easily obtained, it has widely spread for office and general use as personal computers and digital cameras have widely spread.

This inkjet printer generally has the following structure. According to this structure, a movable body called a carriage, in which an ink cartridge and a printing head are integrally formed, ejects particles of liquid ink in a dot shape through nozzles of the printing head on a printing medium (paper) while reciprocally moving on the recording medium in a direction vertical to a paper transporting direction, and a predetermined character or image is drawn on the printing medium so as to create a desired printing material. In addition, the carriage includes ink cartridges of four colors (black, yellow, magenta, and cyan) including black and printing heads for the respective four colors, so that not only black-and-white printing but also full color printing having combined the respective colors are easily performed (In addition, ink cartridges of six colors including the above-mentioned four colors, light cyan, and light magenta or seven or eight colors has been practically used).

As such, in the inkjet printer in which the printing is performed while reciprocally moving the printing head of the carriage on the recording medium in a direction vertical to a paper transporting direction, the printing head needs to perform a reciprocal motion several tens of times to several hundred times or more so as to clearly perform printing corresponding to one page. Therefore, it takes a lot of time for the inkjet printer to perform printing, as compared with another type of printing device, for example, a laser printer using the electrophotographic technology of a copy machine or the like.

In the meantime, in an inkjet printer in which a printing head having a length corresponding to the same size (or a larger size) as a width of printing paper is arranged and a carriage is not used, since it is unnecessary for the printing head to move in a width direction of the printing paper and the printing can be made through so-called one scan (one pass), high speed printing can be performed in the same manner as the laser printer. In addition, since there is no need to provide the carriage mounting the printing heads thereon and a driving system moving it, a printer case becomes small-sized and light, and noise can be further reduced. The inkjet printer of the former is generally called a ‘multipass-type printer’ and the inkjet printer of the latter is generally called a ‘line-head-type printer’.

In the meantime, in the printing head necessary for the inkjet printer, minute nozzles each having a very small diameter within a range of 10 to 70 μm are disposed in one row or a plurality of rows in a printing direction at predetermined intervals. As a result, an ink ejection direction of some nozzles may be inclined or the nozzle position may deviate from an ideal position due to a manufacturing error, so that a landing position of each dot formed by the nozzles may deviate from an ideal position, thereby causing a so-called ‘flying curve phenomenon’ to occur. In addition, the nozzles may have a large variation, each of which having an ink amount that increases or decreases extremely compared with an ideal ink amount, due to the variation characteristics of the nozzle.

As a result, a printing failure known as a so-called ‘banding (stripe) phenomenon’ occurs in a portion having been printed by using the defective nozzles, so that a printing quality may be extremely lowered. Specifically, if the ‘flying curve’ phenomenon occurs, the distance between dots ejected by adjacent nozzles does not become uniform. At this time, ‘white stripes (in a case in which the printing paper is white)’ occur in a portion where the distance between adjacent dots is larger than the normal distance, and ‘thick stripes’ occur in a portion where the distance between adjacent dots is smaller than the normal distance. In addition, even in a case in which an ink amount is different from an ideal ink amount, thick stripes occur in dots formed by the nozzles ejecting a large amount of ink, and white stripes occur in dots formed by the nozzles ejecting a small amount of ink.

Specifically, it is likely for the banding phenomenon to occur more in ‘a line-head-type printer’ where the printing head or the printing medium is fixed (one pass printing) than in the above-mentioned ‘multipass-type printer’ (in the multipass-type printer, there is a technology in which the printing head performs a reciprocal motion many times to prevent the banding from occurring).

For this reason, in order to prevent the printing failure caused by ‘the banding phenomenon’, research and development have been performed for hardware, such as improving a manufacturing technology of the printing head and design improving thereof. However, it is not possible to provide a printing head capable of preventing the ‘banding phenomenon’ perfectly because of the limits imposed by manufacturing cost or technology.

Accordingly, in addition to the improvement in the hardware, a technology which reduces the ‘banding phenomenon’ by using printing control, that is, a software-like method, which will be described in detail below, has been used.

For example, in JP-A-2002-19101 or JP-A-2003-136702, which will be described below, in order to resolve problems of the nozzle variation or non-ejection of the ink, the problem of the head variation is resolved by using a shading correction technology in a portion having the low printing density, and the problem of the banding or variation is resolved by using another color (for example, when being printed with black, cyan or magenta is alternatively used) in a portion having the high printing density.

Further, in JP-A-2003-63043, which will be described below, a method has been suggested in which for a solid image (that is, a base is covered such that the base is not seen), an ink ejection amount of each nozzle adjacent to the non-ejection nozzle is increased and a solid image is formed using all of nozzles.

Furthermore, in JP-A-05-30361, a method is used in which a variation amount of each nozzle is fed back to an error spreader, so that the variation of the ink ejection amount of the nozzle is absorbed, thereby preventing a banding phenomenon from occurring.

However, according to the methods disclosed in JP-A-2002-19101, JP-A-2003-136702, JP-A-2003-63043, and JP-A-5-30361, since the process, which reduces an image quality from being deteriorated due to the banding phenomenon, is controlled so as to be performed at all portions which become the process subject (locations where the banding occurs), a correction process is performed with respect to locations where deterioration of an image quality (banding phenomenon) is not observed even when the correction process is not performed. As a result, deterioration of another image quality may be observed at these locations due to the correction process.

SUMMARY

An advantage of some aspects of the invention is that it provides a printing device capable of avoiding or reducing deterioration of an image quality caused by a banding phenomenon occurring due to a flying curve phenomenon and controlling an execution range of a process for avoiding or reducing deterioration of an image quality, a program for controlling a printing device, a method of controlling a printing device, a printing data creating device, a program for creating printing data, and a method of controlling printing data.

Another advantage of some aspects of the invention is that it provides a printing device capable of avoiding or reducing deterioration of an image quality caused by a banding phenomenon occurring due to an ejection failure of ink and controlling an execution range of a process for avoiding or reducing deterioration of an image quality, a program for controlling a printing device, a method of controlling a printing device, a printing data creating device, a program for creating printing data, and a method of controlling printing data.

According to a first aspect of the invention, there is provided a printing device which prints an image on a printing medium by a printing head, the printing head having a plurality of nozzles for forming a dot on the printing medium. The printing device includes: a printing unit that executes a printing process for reducing deterioration of a printing quality caused by a banding phenomenon; and a printing control unit that controls a printing process for reducing the deterioration on the basis of nozzle information indicating a characteristic of each nozzle and characteristic information for every predetermined region of the image.

According to this aspect, the printing process, which reduces the deterioration of the printed image quality due to the banding phenomenon, can be executed by the printing unit, and the printing process, which reduces the deterioration of the printed image quality, can be controlled by the printing control unit on the basis of the nozzle information indicating the characteristic of each nozzle and the characteristic information of the image.

That is, so long as the creating process of the information for reducing the deterioration of the printed image quality due to the banding (the correction process of the pixel value or the like) is performed, the image quality is improved before performing the creating process of the information for reducing the deterioration of the image quality. However, if the correction process is performed, since the image deterioration (the color change, the deterioration of granularity, or the like) necessarily occurs. As a result, the control can be performed such that the correction process is performed as little as one can at the locations where the banding is not seen even though the banding occurs or the locations where the deterioration may increase more and more even though the correction process is performed.

Accordingly, for example, when executing the printing process for reducing the deterioration of the printed image quality such as ‘the white stripes’ or ‘thick stripes’ caused by ‘the banding phenomenon’ occurring by ‘the flying curve phenomenon’ of the nozzle whose dot forming position deviates from the ideal position, it is possible to control the execution content such as the existence and nonexistence of the execution of the printing process on the basis of the characteristic information of the predetermined region of the image corresponding to the banding phenomenon. Thereby, since the printing process can be executed at only locations where the process for reducing the image deterioration is necessary (for example, locations where the banding can be easily seen), it is possible to effectively reduce the deterioration of the printed image quality such as ‘the white stripes’ or ‘thick stripes’ caused by ‘the banding phenomenon’, and it is possible to suppress an adverse effect for the original quality of printed image caused by the process for reducing the corresponding image deterioration at the minimum.

In this case, the dot refers to one region formed by landing the ink ejected from one or a plurality of nozzles on the recording medium. In addition, the area of ‘the dot’ is not ‘zero’, the dot has a predetermined size (area), and a plurality of different kinds of dots exists for every size. However, the dot formed by ejecting the ink is not necessarily a circular shape. When the dot is formed to have an elliptical shape other than a circular shape, the average diameter may be handled as the dot diameter or by assuming an equivalent dot of a circular shape having the same area as an area of the dot formed by ejecting any amount of ink, the diameter of the equivalent diameter may be handled as the dot diameter. In addition, as a method of selectively impacting the dot having the different density, for example, a method of impacting each dot having the same dot size and the different density, a method of impacting each dot having the same density and the different dot size, and a method of differentiating the density of each dot having the same density and the different ink ejection amount by the overlapping impacting may be considered. In addition, in a case in which one ink drop ejected from one nozzle is divided into small ink drops and then lands, it is assumed as one dot. However, in a case in which dots of two or more sequentially formed from two nozzles or one nozzle are coupled with each other, it is assumed that two dots are formed. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, ‘the nozzle information’ refers to information indicating whether each nozzle of the printing head is related to the banding or not, information which can determine whether each nozzle is related to the banding or not, or the like. For example, the nozzle information refers to information indicating the deviated amount from the ideal forming location of the actually formed dot, the information indicating the deviated amount between the actually formed dot size and the ideal dot size, and the information which can easily control each deviated amount (for example, format converted into a flag indicating whether each nozzle of the printing head is related to the banding or the like). Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, ‘the characteristic information’ refers to specific information of each image obtained by analyzing the image data or the like, information indicating a color, a density, and a luminance of the image, and high-frequency information of the image (including information about the edge of the image). Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, ‘the adverse affect’ refers to the deterioration of the granularity of the printed image which occurs by forming large dots (which is originally unnecessary) in order to reduce the deterioration of the printed image quality and mixing the large dots with each other. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, the ‘banding phenomenon’ refers to a printing failure in which ‘white stripes’ and ‘thick stripes’ simultaneously occur in the printing result because of a so-called ‘flying curve phenomenon’ caused by the nozzle whose dot forming position deviates from the ideal dot forming position. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, ‘the flying curve phenomenon’ is different from the simple ink non-ejection phenomenon of some of nozzles, which has been described above. Specifically, it refers to a phenomenon that the ink is ejected, but the ink ejection direction of some of nozzles is inclined and the position of the dot deviates from the ideal position. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, ‘the white stripe’ refers to a portion (region) where the phenomenon that the distance between adjacent dots becomes larger than the predetermined distance by ‘the flying curve phenomenon’ continuously occurs and the color of the base of the printing medium is visible in a stripe shape. In addition, ‘the thick stripe’ refers to a portion (region) where the phenomenon that the distance between adjacent dots becomes smaller than the predetermined distance by ‘the flying curve phenomenon’ continuously occurs and the color of the base of the printing medium is not seen or where the distance between the dots becomes smaller than the predetermined distance and the color of the base of the printing medium is relatively thickly seen or where a part of the dots formed so as to be deviated from the normal position overlaps the normal dot and the overlapping portion is visible in a thick stripe shape. In addition, the white stripe may occur due to the nozzle having a small ink ejection amount and the thick stripe may occur due to the nozzle having a large ink ejection amount. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, ‘the printing process for reducing the deterioration of the printed image quality’ refers to the process which reduces the deterioration of the printed image quality which occurs due to the result that the dot forming location of the nozzle deviates from the ideal dot forming location. For example, it refers to a process by which the dot forming by using the nozzle is not made with respect to at least one of the nozzle related to the banding phenomenon and the nozzle adjacent to the nozzle related to the banding phenomenon or the dot is formed with the dot pattern in which the banding is not seen with respect to the image portion corresponding to the corresponding nozzle. However, the printing process about the dot forming content is different from the process about the dot forming content with respect to the same pixel value in a case of the normal nozzle which is not related to the banding phenomenon in the content. Hereinafter, this is applicable to ‘a program for controlling a printing device’ of the form 13, ‘a method of controlling a printing device’ of the form 24, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

According to a second aspect of the invention, there is provided a printing device which prints an image on a printing medium by a printing head, the printing head having a plurality of nozzles for forming a dot on the printing medium. The printing device includes: a nozzle information storing unit that stores nozzle information indicating characteristics of the respective nozzle; an image data acquiring unit that acquires image data having a plurality of pixel data corresponding to a pixel value of an M value (M≧2) constituting the image; a pixel data selecting unit that selects predetermined pixel data from the image data; a banding determining unit that determines whether the selected pixel data is related to a banding phenomenon or not on the basis of the nozzle information; a characteristic information extracting unit that extracts characteristic information of an image of a predetermined region formed by including a pixel of the selected pixel data having been determined that the selected pixel data is related to the banding phenomenon; a deterioration determining unit that determines whether deterioration of a printed image quality caused by the banding phenomenon is visible or not; a printing data creating unit that creates printing data having information about dot forming contents of each pixel value of the image data; and a printing unit that prints the image on the recording medium by the printing head on the basis of the printing data. Further, the printing data creating unit performs a process of creating information concerning the dot forming contents including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon with respect to only a part or all of the image of the predetermined region having been determined in the deterioration determining unit that the deterioration of the printed image quality is visible.

According to this aspect, the nozzle information storing unit can store nozzle information indicating the characteristic of each nozzle, the image data acquiring unit can acquire image data having a pixel value of an M value (M≧2) constituting the image, the pixel data selecting unit can select the predetermined image data from the image data, the banding determining unit can determine whether selected pixel data is related to the banding phenomenon or not on the basis of the nozzle information, the characteristic information extracting unit can extract the characteristic amount of the image of the predetermined region constructed by including the pixel of the pixel data determined by the banding determining unit that the image data is related to the banding phenomenon, the deterioration determining unit can determine whether the deterioration of the printed image quality due to the banding phenomenon is visible or not on the basis of the characteristic information, the printing data creating unit can create the printing data having the information related to the dot forming content for each pixel value of the image data, and the printing unit can print the image on the printing medium by using the printing head on the basis of the printing data.

Further, the printing data creating unit can perform a creating process of information about the dot forming contents including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon with respect to only a part or all of the image of the predetermined region having been determined by the deterioration determining unit that the deterioration of the printed image quality is visible.

That is, so long as the creating process of the information for reducing the deterioration of the printed image quality due to the banding is performed, the image quality is improved before performing the creating process of the information for reducing the deterioration of the image quality. However, if the correction process is performed, since the image deterioration (the color change, the deterioration of granularity, or the like) necessarily occurs. As a result, the control can be performed such that the printing data creating process is performed as little as one can at the locations where the banding is not seen even though the banding occurs or the locations where the deterioration may increase more and more even though the correction process is performed.

Accordingly, for example, when executing the printing process for reducing the deterioration of the printed image quality such as ‘the white stripes’ or ‘thick stripes’ caused by ‘the banding phenomenon’ occurring by ‘the flying curve phenomenon’ of the nozzle whose dot forming position deviates from the ideal position, it is possible to control the execution content such as the existence and nonexistence of the execution of the printing process on the basis of the characteristic information of the predetermined region of the image corresponding to the banding phenomenon. Therefore, it is possible to effectively reduce the deterioration of the printed image quality such as ‘the white stripes’ or ‘thick stripes’ caused by ‘the banding phenomenon’, and it is possible to suppress an adverse effect for the original quality of printed image caused by the process for reducing the corresponding image deterioration at the minimum.

In addition, the image data acquiring unit acquires the image data inputted from an optical printing result reading unit such as a scanner or actively or passively acquires the image data stored in the external device through a network such as a LAN or a WAN, or acquires the image data from the recording medium such as a CD-ROM, a DVD-ROM or the like through a driving device such as a CD drive, a DVD drive or the like included in the printing device, or acquires the image data stored in the storage device included in the printing device. That is, the acquiring of the image data includes input, obtainment, reception or reading. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, ‘the nozzle information storing unit’ stores the nozzle information in all of the storing units at all times. In addition, it may store the nozzle information in advance and may store the nozzle information through the input from the external device at the time of operating the printing device without storing the nozzle information in advance. For example, before the printing device is manufactured and is then sold as the product at the time of a shipment in a factory, by an optical printing result reading unit such as a scanner or the like, the variation amount of the dot forming position of each nozzle constituting the printing head or the ink ejection state is tested from the printing result by the printing head and the test result is stored in advance. Alternatively, at the time of using the printing device, in the same manner as the time of shipment in the factory, the variation amount of the dot forming position of each nozzle constituting the printing head is tested, and the test result is stored. Like this, if being timing when the nozzle information can be stored at the time of using the product, any timing may be possible. In addition, after the printing device is used, in order to cope with the case in which the characteristic of the printing head is changed, the deviation amount of the position printed by the printing head or the ink ejection state of each nozzle is tested from the printing result through the printing head by using the optical printing result reading unit such as the scanner or the like, and the tested result and the data at the time of a shipment in the factory are stored or the tested result is overwritten on the data at the time of a shipment in the factor so as to be updated. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below).

In addition, ‘the pixel data determined that it is related to the banding phenomenon’ refers to the pixel data in which the dot corresponding to the selected pixel data is formed by the nozzle causing ‘the flying curve phenomenon to occur and the dot forming location deviates from the ideal dot forming location, or the pixel data in which the dot is formed by the nozzle having the non-proper ink ejection amount and the corresponding dot forming size is different from the ideal dot forming size. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, the information related to the dot forming content of the nozzle includes information, such as information about the dot existence or non-existence with respect to each pixel value of the image data (indicating where the dot is formed or not by the nozzle) and information about the dot forming size (for example, any one of three kinds of large, middle, and small), which are necessary for forming the dot by the nozzle. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, ‘the information for reducing the deterioration of the printed image quality’ refers to the information that reduces the deterioration of the printed image quality occurring when the dot forming location by the nozzle is deviated from the ideal location. For example, it becomes a type of information which is related to the dot forming content like a case in which the dot is not formed by at least one of the nozzle related to the banding or the peripheral nozzle of the corresponding nozzle or a case in which the dot is formed with the dot pattern in which the banding is not seen with respect to the image portion corresponding to the nozzle related to the banding. The information related to the dot forming content is different from the information related to the dot forming content in the case with respect to the same pixel value and the normal nozzle not related to the banding in the contents. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

In addition, examples of the process for creating the information, which is related to the dot forming content including the information for reducing the deterioration of the printed image quality due to the banding phenomenon, include the printing data creating processes for avoiding or reducing the deterioration of the printed image quality due to the banding phenomenon, which are respectively disclosed in JP-A-2004-292205, JP-A-2004-339909, JP-A-2004-359542, JP-A-2005-016490, and JP-A-2005-035641. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

Preferably, the deterioration determining unit compares a characteristic amount indicating the characteristic information with a predetermined threshold value, and determines that the deterioration of the printed image quality caused by the banding phenomenon is visible, when the characteristic amount is equal to or greater than the predetermined threshold value.

According to this structure, in accordance with the nature of the characteristic, for example, by setting the threshold value obtained by the experiment or the like, it is possible to easily determines whether the deterioration of the printed image quality due to the banding phenomenon is visible or not.

Preferably, the printing device further includes a region dividing unit that divides the image data region into a plurality of image data region. Further, an image of each of the plurality of image data region is set as an image of the predetermined region, and the characteristic information extracting unit extracts the characteristic information for each image of the predetermined region.

According to this structure, the image data region is previously divided into the plurality of image data regions, and the image of each image data region is set to the image of the predetermined region. Therefore, it is possible to perform each determination process at a high speed without setting a predetermined region for each of the selected pixel data.

Preferably, the characteristic information includes density information of the image of the predetermined region.

According to this structure, since the number of the physically formed dots is small in a region where the density (the luminance is high) is thin, it is difficult for the deviation of the deviation of one nozzle to be seen (since the distance between the forming location of the physically formed dot and the forming location of another dot increases, the deviation amount relatively decreases). Further, in this region, the area density difference (luminance difference) with the medium used for the printing (for example, the printing medium) becomes smaller, and even though deviation occurs in the dot forming location, it is not seen. Accordingly, the control is performed on the basis of the luminance information such that the printing process or the information forming process for reducing the deterioration of the printed image quality due to the banding phenomenon is not performed in a portion where the banding is not seen, so that the above-mentioned processes can be performed at only the suitable portion, and it is possible to obtain the printed result in which the process for reducing the deterioration of the printed image quality is suitably performed.

In this case, the density information refers to the information about the density of the image represented with the density value or the luminance value. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

Preferably, the characteristic information extracting unit extracts density information for each color of ink corresponding to the printing head.

According to this structure, the printing process or the information creating process for reducing the deterioration of the printed image quality due to the banding phenomenon can controlled on the basis of the density information extracted for ink of each color, and the control can be properly performed for ink of each color. It is possible to obtain the printed result in which the process is properly performed for reducing the deterioration of the printed image quality.

Preferably, the printing data creating unit performs a process of creating information concerning the dot forming contents including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon with respect to only a part or all of the image of the predetermined region which is determined in the deterioration determining unit that the deterioration of the printed image quality is visible and of which a density value indicating the density information is equal to or greater than a predetermined density value.

According to this structure, the control is performed such that for example, the creating process of information about the dot forming contents including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon is performed with respect to the pixel data within the density range of the halftone and the density range of the high density, and such that the creating process of the information for reducing the deterioration of the printed image quality is not performed with respect to the low density region where the deterioration of the printed image quality due to the banding phenomenon is seldom seen. Accordingly, it is possible to obtain the printed result in which the process for reducing the deterioration of the printed image quality is properly performed.

In this case, preferably, the density value, which is equal to or greater than the predetermined density value, becomes the density within the halftone and the high density, as described above. Therefore, for example, in the case of CMYK, if the number of the maximally printed dots becoming the maximum density of each color (different for each kind of the printing device) is set to 100%, the black (Bk) becomes, for example, the density value of the density range which is equal to or greater than 25% of the number of the maximally printed dots, the cyan (Cy) and the magenta (Mg) become, for example, the density value of the density range which is equal to or greater than 30% of the number of the maximally printed dots, and the yellow (Ye) becomes, for example, the density value of the density range which is equal to or greater than 60% of the number of the maximally printed dots. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

According to this structure, the control is performed such that for example, the creating process of information about the dot forming contents including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon is performed with respect to the pixel data within the density range of the halftone (in other words, “middle tone”), and such that the creating process of the information for reducing the deterioration of the printed image quality is not performed with respect to the low density region and the high density region other than the halftone range where the deterioration of the printed image quality due to the banding phenomenon is seldom seen. Accordingly, it is possible to obtain the printed result in which the process for reducing the deterioration of the printed image quality is properly performed.

In this case, the halftone density range is different for each ink color. For example, in the case of CMYK, if the number of the maximally printed dots becoming the maximum density of each color (different for each kind of the printing device) is set to 100%, the density range which becomes 25 to 90% of the number of the maximally printed dots becomes the halftone density range in the black (Bk), the density range which becomes 30 to 90% of the number of the maximally printed dots becomes the halftone density range in the cyan (Cy) and the magenta (Mg), and the density range which becomes 60 to 90% of the number of the maximally printed dots becomes the halftone density range in the yellow (Ye). However, the halftone density range needs to be set in accordance with a dot production rate, the function of the printing device, a binarization method, or the like, in addition to the ink color. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

Preferably, the characteristic information includes frequency information of the image of the predetermined region.

According to this structure, for example, in a portion where the frequency of the image of the predetermined region is low, it is difficult to visually recognize the banding caused by the deviation of the nozzle characteristic. In addition, in a region where the frequency is high, that is, a region where the image content (luminance or density) frequently changes, it is not almost possible to visually recognize the banding caused by the image change. In the region where it is difficult to perform the visual recognition, the control is performed such that the information creating process or the printing process for reducing the deterioration of the printed image quality due to the banding phenomenon is not performed. Therefore, the above-mentioned processes can be performed in only the proper portions, so that it is possible to obtain the printed result in which the process for reducing the deterioration of the printed image quality is more properly performed.

In this case, the frequency information refers to the information which is capable of determining whether the frequency of the image of the predetermined region is high or low, like the information of the output value after performing the filtering using an HPF (bypass filter) or the information obtained by converting the image signal into the frequency region through Fourier transform (FT, FFT, or the like), discrete cosine transform (DCT), Hadamard transform, or the like. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

Preferably, the frequency information includes edge information of the image of the predetermined region.

According to this structure, it is possible to easily extract the edge information of each predetermined region serving as the frequency information by an edge extracting filter or the like, and it is possible to apprehend the image change of each region (level of the frequency) from the edge information. The control can be performed on the basis of the above-mentioned information such that the printing process or the information creating process for reducing the deterioration of the printed image quality due to the banding phenomenon is not formed in a portion where the banding is not seen. Therefore, it is possible to perform the above-mentioned process at only the proper portion, and it is possible to obtain the printing result in which the process for reducing the deterioration of the printed image quality is properly performed.

Preferably, the characteristic information extracting unit extracts the frequency information for each color of ink corresponding to the printing head.

According to this structure, the printing process or the information creating process for reducing the deterioration of the printed image quality due to the banding phenomenon is controlled on the basis of the frequency information of each color, so that the proper control can be performed for each color. Accordingly, it is possible to obtain the printed result in which the process for reducing the printed image quality is properly performed.

Preferably, the printing data creating unit performs a creating process of information including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon as information about the dot forming contents with respect to only a part or all of the image of the predetermined region which is determined in the deterioration determining unit that the deterioration of the printed image quality is visible and of which a frequency indicating the frequency information is not more than a predetermined frequency.

According to this structure, for example, in a portion where the frequency of the image of the predetermined region is low, it is difficult to visually recognize the banding caused by the deviation of the nozzle characteristic. In addition, in a region where the frequency is high, that is, a region where the image content (luminance or density) frequently changes, it is not almost possible to recognize visually the banding caused by the image change. In the region where it is difficult to perform the visual recognition, the control is performed such that the information creating process or the printing process for reducing the deterioration of the printed image quality due to the banding phenomenon is not performed. Therefore, the above-mentioned processes can be performed in only the proper portions, so that it is possible to obtain the printed result in which the process for reducing the deterioration of the printed image quality is more properly performed.

Preferably, the nozzle information includes information indicating whether an ink ejection failure of each nozzle exists or not.

According to this structure, it is possible to simply determine the nozzle having the ink ejection failure that causes the banding to occur. Thereby, the printing process or the information creating process for reducing the deterioration of the printed image quality due to the banding phenomenon can be performed with respect to only at least of the pixel data corresponding to the nozzle having the ink ejection failure that causes the banding to occur or the peripheral pixel data of the pixel data corresponding to the nozzle having the ink ejection failure. Therefore, it is possible to reduce the deterioration of the image quality occurring in the printed result due to the banding phenomenon without changing by the reduction process the image quality of the portion which is not related to the banding.

In this case, the ink ejection failure refers to a state in which the ideal ink ejection cannot be performed, like a case in which the ink cannot be ejected, a case in which the ink ejection amount is insufficient, a case in which the ink ejection amount is excessively much, a case in which the ink cannot be ejected onto the ideal location, or the like. In addition, since the CCD sensor provided in the printing device can detect whether the ink ejection failure exists or not in the corresponding nozzle, it is possible to create the information indicating whether the ink ejection failure exists or not on the basis of the detected result. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

Preferably, the nozzle information includes information of a positionally deviated amount between an actual forming position of the dot and an ideal forming position of the dot in each nozzle.

According to this structure, it is possible to easily discriminate the nozzle which causes ‘the so-called flying curve phenomenon’ occurring by the phenomenon that the dot forming location deviates from the ideal dot forming location. Therefore, it is possible to reduce, with the proper control content, the deterioration of the printed image quality, such as ‘the white stripes’ or ‘the thick stripes’, which occurs by ‘the banding phenomenon’ caused by ‘the flying curve phenomenon’.

Preferably, the nozzle information includes information about a deviated amount between a density value of the dot which each nozzle actually forms and an ideal density value of the corresponding dot.

According to this structure, it is possible to easily discriminate the nozzle which causes ‘the so-called density deviation’ occurring by the phenomenon that the density of the formed dot deviates from the ideal density. Therefore, it is possible to reduce, with the proper control content, the deterioration of the printed image quality, such as ‘the white stripes’ or ‘the thick stripes’, which occurs by ‘the banding phenomenon’ caused by ‘the density deviation’.

Preferably, in the printing head, the nozzles are continuously arranged over a range larger than a region where the printing medium is mounted, and the printing head can perform printing through one scanning operation.

According to this structure, as described above, it is possible to create the printing data suitable for making not be seen the deterioration of the printed image quality, such as ‘the white stripes’ or ‘the thick stripes’ caused by the banding phenomenon, which easily occurs in particular when the using the line-head-type printing head in which the printing is completed with so-called one scanning (one pass).

In this case, ‘the printing of one scanning’ means to the printing method in which with respect to the one line of the paper transporting direction becoming the printing subject (head moving direction), the one line is printed with only the corresponding nozzles of the respective nozzles which correspond to the one line, and when the corresponding nozzles pass once, the printing of the one line is completed. Hereinafter, this is applicable to various types of ‘a program for controlling a printing device’, various types of ‘a method of controlling a printing device’, various types of ‘a printing data creating device’, various types of ‘a program for creating printing data’, various types of ‘a method of creating printing data’, various types of ‘a recording medium where the program is recorded’, and preferred embodiments, which will be described in detail below.

Preferably, the printing head performs printing while performing a reciprocal motion in a direction orthogonal to a paper transporting direction of the printing medium.

The above-mentioned banding phenomenon strikingly occurs in the line-head-type printing head, but it occurs in the multipass-type printing head. Accordingly, if the above-mentioned printing method according to the above-mentioned aspect is applied to the multipass-type printing head, ‘the white stripes’ or ‘the thick stripes’, which is caused by ‘the banding phenomenon’ occurring in the multipass-type printing head are not seen, so that it is possible to perform the proper printing process or printing data creating process.

In addition, in the case of the multipass-type printing head, the above-mentioned banding phenomenon can be avoided by performing the process which repeats the scanning of the printing head, but if the printing device according to the above-mentioned aspect is applied, since it is not necessary to repeatedly perform the scanning operation many times at the same locations by using the printing head, it is possible to achieve the high-speed printing.

According to a third aspect of the invention, there is provided a program for controlling a printing device which is used for controlling the printing device which prints an image on a printing medium by a printing head, the printing head having a plurality of nozzles for forming a dot on the printing medium, the program being used to allow a computer to execute: executing a printing process for reducing deterioration of a printed image quality caused by a banding phenomenon; and controlling a printing process for reducing the deterioration on the basis of nozzle information indicating a characteristic of each nozzle and characteristic information for every predetermined region of the image.

According to this structure, if the computer reads out the program and then executes the process in accordance with the read program, it is possible to achieve the same effects as the first aspect of the invention.

In addition, all of the printing devices, such as the inkjet printer or the like, which are on the market, includes a computer system having a central processing unit (CPU), storing units (RAM and ROM), and an input/output unit. In addition, since the respective units can be implemented through software by the computer system, it may be chiefly and easily achieved, as compared with the case in which the respective units are implemented by creating the exclusive hardware.

In addition, updated versions may be easily made by the function change or improvement through the change of the portion of the program. Hereinafter, this is applicable to ‘a program for controlling a printing device’ according to the aspect, and preferred embodiments, which will be described in detail below.

According to a fourth aspect of the invention, there is provided a program for controlling a printing device which is used for controlling the printing device which prints an image on a printing medium by a printing head, the printing head having a plurality of nozzles for forming a dot on the printing medium, the program being used to allow a computer to execute: acquiring image data having a plurality of pixel data corresponding to a pixel value of an M value (M≧2) constituting the image; selecting predetermined pixel data from the image data; determining whether the selected pixel data is related to a banding phenomenon or not on the basis of the nozzle information; extracting characteristic information of an image of a predetermined region formed by including a pixel of the pixel data selected from the image data which is determined by the determining of the banding that the selected pixel data is related to the banding phenomenon; determining whether deterioration of a printed image quality caused by the banding phenomenon is visible or not on the basis of the characteristic information; creating printing data having information about dot forming contents of each pixel value of the image data; and printing the image on the recording medium by the printing head on the basis of the printing data. In addition, during the creating of the printing data, performed is a creating process of information about the dot forming contents including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon with respect to only a part or all of the image of the predetermined region having been determined in the determining of the deterioration that the deterioration of the printed image quality is visible.

Preferably, during the determination of the deterioration degree, when a characteristic amount indicating the characteristic information is compared with a predetermined threshold value and the characteristic amount is equal to or greater than the predetermined threshold value, it is determined that the deterioration of the printed image quality caused by the banding phenomenon is visible.

Preferably, in the program for controlling a printing device, the process executed by the computer further includes: dividing the image data region into a plurality of image data region. Further, an image of each of the plurality of image data regions is set as an image of the predetermined region. Furthermore, during the extracting of the characteristic information, the characteristic information is extracted for each image of the predetermined region.

Preferably, the characteristic information includes density information of the image of the predetermined region.

Preferably, during the extracting of the characteristic information, density information is extracted for each color of ink corresponding to the printing head.

Preferably, during the creating of the printing data, performed is a creating process of information about the dot forming contents including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon with respect to only a part or all of the image of the predetermined region which is determined in the determination of the deterioration that the deterioration of the printed image quality is visible and of which a density value indicating the density information is equal to or greater than a predetermined density value.

Preferably, the characteristic information includes frequency information of the image of the predetermined region.

Preferably, the frequency information includes edge information of the image of the predetermined region.

Preferably, during the extracting of the characteristic information, the frequency information is extracted for each color of ink corresponding to the printing head.

Preferably, during the creating of the printing data, performed is a creating process of information including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon as information about the dot forming contents with respect to only a part or all of the image of the predetermined region which is determined in the determination of the deterioration that the deterioration of the printed image quality is visible and of which a frequency indicating the frequency information is not more than a predetermined frequency.

Preferably, the nozzle information includes information indicating whether an ink ejection failure of each nozzle exists or not.

Preferably, the nozzle information includes information of a positionally deviated amount between an actual forming position of the dot and an ideal forming position of the dot in each nozzle.

According to a fifth aspect of the invention, there is provided a computer readable recording medium in which the above-mentioned printing device controlling program is recorded.

Thereby, it is possible to achieve the same effects as the above-mentioned printing device controlling program, and the printing program can be easily exchanged through a recording medium such as a CD-ROM or a DVD-ROM, an MO or the like.

According to a sixth aspect of the invention, there is provided a method of controlling a printing device which is used for controlling the printing device which prints an image on a printing medium by a printing head, the printing head having a plurality of nozzles for forming a dot on the printing medium. The method includes: executing a printing process for reducing deterioration of a printed image quality caused by a banding phenomenon; and controlling a printing process for reducing the deterioration on the basis of nozzle information indicating a characteristic of each nozzle and characteristic information for every predetermined region of the image.

Thereby, it is possible to achieve the same effects as the printing device according to the first aspect of the invention.

According to a seventh aspect of the invention, there is provided a method of controlling a printing device which is used for controlling a printing device which prints an image on a printing medium by a printing head, the printing head having a plurality of nozzles for forming a dot on the printing medium. The method includes: acquiring image data having a plurality of pixel data corresponding to a pixel value of an M value (M≧2) constituting the image; selecting predetermined pixel data from the image data; determining whether the selected pixel data is related to a banding phenomenon or not on the basis of the nozzle information; extracting characteristic information of an image of a predetermined region formed by including a pixel of the pixel data selected from the image data which is determined by the determining of the banding that the selected pixel data is related to the banding phenomenon; determining whether deterioration of a printed image quality caused by the banding phenomenon is visible or not on the basis of the characteristic information; creating printing data having information about dot forming contents of each pixel value of the image data; and printing the image on the recording medium by the printing head on the basis of the printing data. Further, during the creating of the printing data, performed is a creating process of information about the dot forming contents including the information for reducing the deterioration of the printed image quality caused by the banding phenomenon with respect to only a part or all of the image of the predetermined region which is determined in the determining of the deterioration that the deterioration of the printed image quality is visible.

Thereby, it is possible to achieve the same effects as the printing device according to the second aspect of the invention.