JP6087800B2 - Recording apparatus and recording method - Google Patents

Description

  The present invention relates to a recording apparatus and a recording method for printing by controlling the operation of a print head. In particular, the present invention relates to an ink jet recording apparatus and a recording method.

  In a recording apparatus typified by an ink jet printer, high image quality is a major point that affects its performance as well as high printing speed. In order to achieve high image quality, it is necessary to land droplets ejected from the print head accurately and uniformly on a predetermined position on the paper. In particular, in the case of a color printer, it is important to improve the landing accuracy in order to prevent a so-called color misregistration problem that the hue is changed by shifting the landing position of each color.

  However, when bi-directional printing is performed, the order in which dots are ejected and landed from each color print head in the forward pass and the return pass is switched depending on the print head arrangement order. There is a problem that so-called bidirectional color banding occurs.

  For high image quality, there is a technique of using fine droplets. By reducing the size of the droplets and discharging a large number of droplets, the effect of reducing the influence of a single droplet, that is, the influence of the color overlapping order, can be obtained. However, in the first place, it is technically difficult to eject fine droplets, and a high printing speed cannot be realized unless the number of nozzles of the print head is increased. That is, the printer must be equipped with a large number of print heads, which increases the cost.

  Under these circumstances, inkjet printers that mainly output printed materials for outdoor sign use have used print heads that can eject droplets of a size that is somewhat large, while performing printing control at high speed and high density. We have dealt with the above-mentioned color misregistration and bidirectional color banding problems.

  For example, Japanese Patent Application Laid-Open No. 2011-173406 uses a non-uniform print mask in which the upper and lower portions are complementary to each other, and the probability of using nozzles corresponding to the peripheral region of the end portion is lower than other nozzles. A technique has been disclosed in which an image quality operation is made inconspicuous by performing a drawing operation based on the color swath.

JP 2011-173406 A

  However, various problems are caused by using large-sized droplets. That is, image quality defects are conspicuous, including the aforementioned bidirectional color banding and color misregistration. A large droplet size means that the amount of droplets, so-called drop volume, is large, and when using ink that is difficult to spread on the paper media, Dot formation becomes higher in the vertical direction, and the shielding rate of light within the dot increases despite the small dot diameter. As a result, the density of the dots increases, and the density difference from the background color of the paper media, generally white, becomes significant. This is an excellent feature for the purpose of high density printing, but appears as a graininess when trying to express a low tone color tone. This is shown in FIG.

  As a technique for reducing the graininess, there is a technique called multi-drop printing in which droplets of a plurality of types of sizes are mixed and discharged. In an image expressed with low gradation, it is possible to eliminate graininess as much as possible by using a large number of small droplets. This is shown in FIG. On the other hand, in an image expressed with high gradation, a large size droplet is frequently used to secure a density.

  Conventional ejection control has two types of ejection and non-ejection, and the information amount of one pixel is 1 bit per color, whereas multi-drop printing has information on the size of droplets including non-ejection as information. Since it is necessary, it has an information amount of at least 2 bits. In the case of 2 bits, there are four gradations of non-ejection, ejection at a small size, ejection at an intermediate size, and ejection at a large size. FIG. 8 shows an example of the dot diameter on the paper medium when using droplets of these sizes. FIG. 8A shows a small-size discharge, FIG. 8B shows a medium-size discharge, and FIG. 8C shows a large-size discharge. Although depending on the discharge control, the drop volume ratio of droplets of large, medium, and small sizes is generally 3: 2: 1. Depending on the drop volume ratio, droplets of each size may be referred to as 3 drops, 2 drops, 1 drop. However, the dot diameter on the paper media is not as great as the drop volume ratio. This is because, as described above, large-sized droplets become dots that are formed higher in the vertical direction than the paper medium. On the other hand, the concentration ratio substantially matches the drop volume ratio.

  For these reasons, large sized droplets are likely to combine with adjacent dots and cause dot swimming called mottling. When this occurs selectively, it causes image quality defects such as solid blur and streaks. FIG. 4B shows an example in which image quality failure occurs when selective mottling occurs with respect to the appropriate image shown in FIG.

  In Japanese Patent Application Laid-Open No. 2011-173406, for example, based on the print mode shown in FIG. 5, the image quality is reduced by changing to the print mode shown in FIG. 6. The print mode in FIG. 5 is also called four passes in order to complete an image of a certain area after four scans. On the other hand, in the printing mode of FIG. 6, a print mask in which the upper and lower blocks of the color swath are complementary as shown in FIG. 7 is applied, and the image is completed in 8 passes, which is twice as many as 4 passes.

  That is, when attention is paid to a certain pixel, if it is masked by the upper block of the color swath by the print mask, it is ejected by the corresponding lower block, and conversely if it is masked by the lower block, it is ejected by the corresponding upper block. This operation is uniformly applied to any number of drops even when multi-drop printing is used together. That is, it can be said that the complementary pixels that form a pair between the upper and lower blocks of the print mask have a chance of being ejected twice in 8 passes, but the ejection operation is performed only once among these. . FIG. 9 shows the relationship between the input drop number, the output drop number, and the print mask value.

  In the print mode of FIG. 6, the number of passes is double, which means that the print time is doubled. Therefore, when using such a print mode, it is necessary to increase the amount of media transport for one scan and decrease the number of passes by performing printing at a low resolution. In this case, however, it is necessary to use droplets of a size as large as possible in order to avoid density reduction and solid blurring at low resolution. That is, a contradiction arises in that, although it is desired to frequently use small-sized droplets in order to avoid solid blurring, large-sized droplets must be used in order to avoid a decrease in density and solid blurring.

  Furthermore, the discharge control of extremely large sized droplets is difficult as well as the technical control of the discharge of micro droplets. Therefore, it is also costly to use large-sized droplets that can withstand actual use in low-resolution printing without greatly changing the print head specifications.

  The present invention has been made in view of such circumstances, and makes solid blurring and streaks promoted by using large-sized droplets, such as color banding during bidirectional printing in a recording apparatus, inconspicuous. It is an object of the present invention to provide a recording apparatus and a recording method that are capable of reducing the density during low-resolution and high-speed printing.

The recording apparatus of the present invention includes a plurality of nozzles, a print head that discharges ink from the nozzles to a recording medium and forms dots of different sizes on the recording medium, and a conveying unit that conveys the recording medium; A carriage mounted with the print head and reciprocatingly scanned in a direction intersecting the conveyance direction of the recording medium, and a reference print mask for determining whether or not to eject the ink from the nozzles are input. Control means for generating print data indicating whether or not to eject the ink from the nozzles from the image data and the print mask, and controlling the ejection of the print head, and is included in the image data The pixel data for each dot formed on the recording medium includes a value corresponding to each of the sizes, and is generated by the control unit. A recording apparatus that ejects the ink from the print head based on character data has at least two print modes, a normal mode and a special mode, and the print mask is assigned one bit for each pixel data. The control means generates the different print data for each print mode. In the normal mode, the control means sets the pixel data value to the print data when the print mask value is one value. When the other value, the print data is set as a non-ejection value regardless of the value of the pixel data. In the special mode, the control means has a predetermined value when the pixel data is a predetermined value. and wherein when the value of the print mask of said one value, the advance of the predetermined forming a determined value following the dots first value said print data The value, the when and the value of the print mask when the pixel data is said predetermined value of said other value, when the value or more to form a minimum of the dot, and forms a maximum of the dot A predetermined second value that forms the dot corresponding to a value that is less than a predetermined value and that is larger than the predetermined value when the first value is added. When the pixel data is other than the predetermined value and the print mask value is the one value, the pixel data value is the print data value, and the pixel data is the pre-determined value. When the print mask value is other than the determined value and the print mask value is the other value, the print data is set to a non-ejection value regardless of the pixel data value, and the print head corresponds to the print data. And discharging the ink.

The recording method of the present invention comprises a plurality of nozzles, a print head that discharges ink from the nozzles to a recording medium and forms dots of different sizes on the recording medium, and a conveying unit that conveys the recording medium; A carriage mounted with the print head and reciprocatingly scanned in a direction intersecting the conveyance direction of the recording medium, and a reference print mask for determining whether or not to eject the ink from the nozzles are input. Control means for generating print data indicating whether or not to eject the ink from the nozzles from the image data and the print mask, and controlling the ejection of the print head, and is included in the image data The pixel data for each dot formed on the recording medium includes a value corresponding to each of the sizes, and is generated by the control unit. In a recording method of a recording apparatus that discharges the ink from the print head based on character data, the print mask has at least two print modes of a normal mode and a special mode, and the print mask has one bit for one pixel data And the control means includes a step of generating different print data for each print mode, and a step of discharging the ink from the print head in correspondence with the print data. In the case of the normal mode among the steps of generating, the step of setting the value of the pixel data as the value of the print data when the value of the print mask is one value, and the value of the pixel data when the value of the print mask is the other value Regardless of whether the print data is a non-discharge value, and in the case of the special mode in the step of generating the print data, When the and the print value of the mask is one of the values when the value of the raw data is predetermined, the advance of the predetermined forming a determined value following the dots first value of the print data value And when the pixel data is the predetermined value and the value of the print mask is the other value, the maximum dot is equal to or greater than the value forming the minimum dot. when the value form below, and a predetermined second value the print data forming the dots the corresponding value that is a predetermined value larger predetermined value than when adding the first value And when the pixel data is other than the predetermined value and the print mask value is the one value, the pixel data value is the print data value. , The pixel When the data is other than the predetermined value and the value of the print mask is the other value, the print data is set to a non-ejection value regardless of the value of the pixel data. Features.

  According to the present invention, in addition to bi-directional banding caused by the color stacking order differing between the forward path and the return path, image quality defects seen when discharging large-sized droplets such as solid blur and streaks are suppressed. Therefore, it is possible to avoid a decrease in density during low resolution and high speed printing.

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention. FIG. 2 is a schematic view of the carriage mechanism. FIG. 3A is a diagram illustrating an example of a granular feeling when a large-sized droplet is used. FIG. 3B is a diagram illustrating an example of an effect of suppressing graininess when a small-sized droplet is used. FIG. 4A is an example showing a proper print image. FIG. 4B is a diagram illustrating an example of image quality defects such as solid blur and streaks. FIG. 5 is a diagram showing the principle of drawing in a printing mode called 4-pass. FIG. 6 is a diagram illustrating an example of a print mode in which a print mask in which upper and lower regions divided into two have a complementary relationship is applied. FIG. 7 is a diagram illustrating an example of a print mask in which upper and lower regions divided into two have a complementary relationship. FIG. 8 is a diagram illustrating an example of three different sized droplets that perform mixed ejection operations in multi-drop printing. FIG. 9 is a diagram showing an example of the relationship between the number of input drops and the number of output drops when a conventional print mask process is performed in multi-drop printing. FIG. 10 is a diagram illustrating an example of the relationship between the number of input drops and the number of output drops when the print mask process of the present invention is performed in multi-drop printing. FIG. 11 is a flowchart for explaining the printing operation. FIG. 12 is a diagram illustrating an example in which the relationship between the number of input drops and the number of output drops is selectively used depending on the scan direction and the dot order of the main scan.

  Hereinafter, a recording apparatus and a recording method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this figure, the recording apparatus 1 is an ink jet printer. The recording apparatus 1 includes a control unit 20 that controls the operation of the entire apparatus. The control unit 20 includes a CPU 21 of a control unit that performs overall control of processing operations in the control unit 20, a ROM 22 of a storage unit in which programs for performing various controls and printing operations of the recording apparatus 1, and the execution of the printing operation are performed. The RAM 23 of the storage means used as a working storage area by each control unit, the EEPROM 24 of the storage means configured by a non-volatile memory for storing setting values and data immediately before the power is turned off, and the state operated in the operation panel 44 are read. At the same time, the operation panel control unit 25 that displays information on the display unit included in the operation panel 44, the print control unit 26 that is a control unit that controls the print operation by the print head 41 with respect to the recording medium, and the operation of the carriage mechanism 42 are performed. From a carriage control unit 27 as a control means for controlling, a grid roller or the like for conveying a sheet as a recording medium A sheet conveyance control unit 28 which is a control means for controlling the operation of the sheet conveyance mechanism 43 to be formed, an image memory 30 for storing an image to be printed, and an image memory writing / reading control for writing / reading control to the image memory 30 And a host I / F unit 29 which is an interface for inputting / outputting image data and control commands to / from the host computer.

  The print control unit 26 and the carriage control unit 27 control the printing operation while coordinating the print positions based on the carriage position read by the linear encoder 45.

  FIG. 2 is a schematic view of an example constituting the carriage mechanism. The carriage mechanism 42 is provided with means for detecting the position of the print head 41. When ejecting droplets from the print head 41 in the recording apparatus 1, a linear encoder 45 incorporating a scale sensor attached to the carriage 420 and a linear scale 421 fixed along the traveling path of the carriage 420 are used. The current position during the reciprocation of the carriage 420 is detected, and information is input to the control unit 20. The control unit 20 recognizes the position of the print head 41 and generates ink ejection timing, thereby improving the positional accuracy of the droplets that have landed on the paper 422. In this example, four color print heads are mounted in the order of K (black), C (cyan), M (magenta), and Y (yellow) from the left side when viewed from the paper 422 feeding direction, that is, from the head in the forward direction. . In the forward direction, ink colors are formed on the paper 422 in this order, and the reverse is the reverse direction.

  Ink jet printers using these configurations require multiple scans and bi-directional carriage scans in order to suppress the deflection and omission of the nozzles of the print head 41 and periodic unevenness caused by vibration of the drive system. Usually, a certain area is drawn. This is generally called a multipath method. In the multi-pass method in which an image of a certain region is completed by n scans, the number of dots ejected in one scan is 1 / n with respect to the total dots constituting a certain region. For example, in a printing mode called 4-pass that completes an image in 4 scans, a quarter of dots constituting a certain area are ejected for each scan, and the image is completed by conveying the paper 422 each time. I will let you. In this case, the conveyance pitch of the paper 422 is approximately ¼ of the color swath constituted by the total number of nozzles of the print head 41. FIG. 5 shows this state focusing only on a certain print color. The conveyance pitch of the paper 422 is ¼ of the used nozzle range of the print head 41, and ¼ constituent dots of the image are ejected by the color swath created in one scan. It can be seen that the image is completed by taking 4 scans for each area.

  An example of a print mode to which an embodiment of the present invention is applied will be described with reference to FIG. At the time of 4-pass printing, ¼ of the used nozzle range of the head is used as the paper conveyance amount, but here, ８ of the used nozzle range is used for it. Further, as shown in FIG. 7, the print mask is not uniform over the entire range of nozzles used in the print head, and the upper and lower regions are in a complementary relationship. When printing is performed in the print mode of FIG. 6, the nozzle usage efficiency of the print head is reduced by a factor of 1/2 compared to the normal four passes. This means that the printing speed is halved, but this problem is reduced by reducing the output resolution and reducing the number of passes, and the image data to be input to the printer has a high gradation part. The problem is solved by ensuring the concentration of the droplets to be formed as large as possible.

  Next, the non-uniform print mask shown in FIG. 7 will be described. An example of the gradation curve constituting the probability distribution of the nozzles applied to the print mask will be described. Steepening the gradient curve gradient in a non-uniform region of the drawing results in color banding within this region, so it is desirable that the gradient be as gentle as possible. On the other hand, since the high printing rate at the end of the color swath causes boundary banding and beading, an appropriate gradation curve that balances these must be set. FIG. 7 shows an S-shaped gradation curve, which is devised to make the slope gentle by connecting the printing rate of the start point and the end point from 30% to 70%, and to suppress the occurrence of color banding and boundary banding. By using such a print mask, the printing rate of the first scan and the final scan, which is dominant with respect to the color banding, is necessarily reduced, so that there is an effect of suppressing bidirectional color banding. Further, since the printing rate at the end of the color swath is also reduced, there is an effect on boundary banding and beading. However, the selection of the shape of the gradation curve and the setting of the printing rate of the start point and the end point are preferably changed depending on the print mode and usage.

  Although the example in which the print head is complemented between the upper and lower blocks, that is, the upstream and downstream blocks in the conveyance direction of the recording medium has been shown. You may supplement. Furthermore, the image quality is improved. For example, each block may be divided into four areas, that is, the print head may be divided into 12 parts, printed in 12 passes, and the image may be completed on the recording medium. For example, in this case, the upper third of the gradation curve showing the distribution of the printing rate in FIG. 7 is printed by four-pass printing by the four areas of the most upstream block, and 4 by the four areas of the inner block. The upper 1/3 of the gradation curve may be printed by pass printing, and the lower 1/3 of the gradation curve may be printed by 4-pass printing by four areas of the downstream block. That is, the image may be divided into a plurality of blocks, and further divided into a plurality of regions, and the image may be completed by ejection from all the regions.

  Next, the principle of avoiding density reduction during low resolution and high speed printing will be described. Assuming multi-drop printing, for example, droplets of three types as shown in FIG. At this time, for a specific pixel, a small-sized droplet, i.e., 1 drop, and an intermediate-sized droplet, i.e., 2 drops, shown in Fig. 8 (a), are input. In the conventional manner, according to the print mask of FIG. 7, the ejection operation is performed by either the upper block or the lower block. Since the upper and lower blocks of the print mask are in a complementary relationship, droplets of any size are ejected only once.

  On the other hand, when 3 drops shown in FIG. 8C are input, control is performed that deviates from the meaning of ejection and non-ejection of the conventional print mask. That is, with respect to a specific pixel, when the mask value is 0, that is, in the case of conventional ejection, a 3-drop ejection operation is performed as usual, and when the mask value is 1, that is, in the case of conventional non-ejection, non-ejection is not performed. A one-drop ejection operation is performed. That is, for a pixel to which 3 drops are to be ejected, 3 drops are not ejected once, and ejection operations are performed twice, 3 drops and 1 drop. The drop volume ratio of each size is 1, 2: 3 for 1, 2, and 3 drops, and a total of 2 drops and 3 drops are discharged as a total of 4 drops. It corresponds to the case. In addition, the area of the droplets that have landed on the paper medium by the print head that can actually eject four drops does not become as large as the ratio of the droplet amounts according to the example of FIG. 8, whereas FIG. 8 (c) is combined. Although these are in different scans, since they are the same pixel, the discharge positions of the 3 drop and 1 drop should theoretically match, but in reality, a slight shift of the landing position occurs. As a result, the paper medium shielding area is increased and the dots are not formed higher in the vertical direction when the 3 drops and the 1 drop are discharged twice than when the 4 drops are discharged once. is there. This is nothing but reducing image quality defects such as solid blur and streaks when using large-sized droplets. As shown in FIG. 10, this discharge control is performed by converting the number of input drops into the number of output drops using a print mask.

  In the above description, a method of discharging a plurality of times in order to expand the input 3 drops to a larger size droplet has been described. It may be discharged. Furthermore, it is conceivable that the input 3 drops are expanded to a droplet size equivalent to 4 drops by ejecting 2 drops twice.

This technique is particularly effective for dark colors that make heavy use of solid images. On the other hand, for light colors, it is not necessary to perform this process if there are few large-sized droplets in the first place.
Furthermore, this method has different effects depending on the dot formation characteristics on the paper medium depending on the physical properties of the ink and the behavior when the ink is placed on the ink. It is necessary to tune how to convert the number of drops according to the ink color and ink type.

  For example, for media on which it is difficult for ink to spread on the media, even if 3 drops and 1 drop are overlapped and expanded to a droplet equivalent to 4 drops, solid filling may be incomplete. In this case, as already described, it is effective to expand the droplet size to a droplet size equivalent to 4 drops by overlapping 2 drops twice. This is because the discharge feature is more stable and the drop volume is slightly larger when 2 drops are continuously discharged than when 3 drops and 1 drop are alternately switched.

  However, in this case, the slight scattering effect when alternately discharging 3 drops and 1 drop is impaired, and there is a concern about image quality defects such as white stripes due to the periodicity of dots in the main scanning direction. In order to avoid this, as shown in FIG. 12, there can be considered a method of selectively using the relationship between the number of input drops and the number of output drops by the forward scan and the backward scan. In the printing mode of FIG. 6, the forward scan is always complemented by the forward scan. For example, the dots ejected in one scan and the dots ejected in 5 scans have a complementary relationship, and if these are ejected in 3 drops and 1 drop, the droplet size is equivalent to 4 drops. Here, it is assumed that the relationship between the number of input drops and the number of output drops is based on FIG. On the other hand, the return scan is always complemented by the return scan. For example, there is a relationship between 2 scans and 6 scans. It is assumed that the relationship between the number of input drops and the number of output drops is based on FIG. As a result, the forward scan has 3 drops and 1 drop superimposed to give a considerable scattering effect, and the return scan has 2 drops applied twice to give a solid filling improvement effect. You can design.

  Furthermore, it is conceivable to use these relations separately for even-numbered dots and odd-numbered dots in the main scanning direction. For example, in all scans, even-numbered dots use FIG. 12A and odd-numbered dots use FIG. 12B. As a result, odd-numbered dots always have 2 drops arranged in the sub-scanning direction, and even-numbered dots have both 3 drops and 1 drop. This is effective in terms of providing periodicity in the sub-scanning direction when dot coupling in the main scanning direction is likely to occur and horizontal stripes are conspicuous.

  As described above, the color swath created in one scan during bidirectional printing is performed by applying a print mask in which each region divided by an integer of 2 or more is in a complementary relationship, and a specific specific For input gradations that mean droplets of a size, it deviates from the meaning of ejection or non-ejection of the print mask, and the droplets are ejected multiple times on the same pixel in different scans, so that the order of color overlap is forward In addition to bi-directional banding caused by differences depending on the return path, printing defects such as boundary banding, beading, solid blur and streaks can be suppressed, and the droplet size that can be ejected by the print head can be expanded. As a result, it can be expected to stably achieve high print image quality while avoiding density reduction during low resolution and high speed printing.

  FIG. 11 is a flowchart for explaining the printing operation. When performing the printing process, it is first determined whether the print mask is used in the normal mode or the special mode. If the normal mode, the process proceeds to step S2, and if the special mode, the process proceeds to step S5 (step S1). This is determined by, for example, a binary flag indicating the print mask function. This flag is set in advance by the user to “0” in the normal mode and “1” in the special mode. The migration destination is determined according to the value. For example, each ink color is divided into a normal mode and a special mode. This may cause a significant problem for each color. In particular, the problem is solved by setting a special color to a significant color. Alternatively, all-color normal mode or all-color special mode may be used. Further, it may be set so that only one mode, for example, the special mode is used in advance.

  In step S2, when the print mask functions in the normal mode, the following operation is performed. When the mask value of the print mask is “0”, ejection data for ejecting ink corresponding to the value of the number of drops in the input gradation of the image data is generated. When the mask value of the print mask is “1”, ejection data that does not eject ink is generated regardless of the value of the number of drops in the input gradation of the image data. When the ejection data for one pass is generated, the process proceeds to step S3.

In step S3, ink is ejected from the nozzles based on the generated ejection data.
These operations are determined whether all the image data has been printed, and are repeated until all the image data has been printed (step S4).

  In step S5, when the print mask functions in the special mode, the following operation is performed. When the mask value of the print mask is “0”, ejection data for ejecting ink corresponding to the value of the number of drops in the input gradation of the image data is generated. When the mask value of the print mask is “1”, ejection data that does not eject ink is generated or ejection data that ejects ink is generated according to the value of the number of drops in the input gradation of the image data. Generated. For example, as shown in FIG. 10, when the input gradation is 3 drops, that is, the maximum gradation value, ejection data for ejecting 1 drop is generated. As a result, two drops of 3 drops and 1 drop are ejected at the same position, and the printed dots are emphasized, resulting in dots with high density and spread. Although it is the same position, it is actually a slightly shifted position. When the ejection data for one pass is generated, the process proceeds to step S6.

In step S6, ink is ejected from the nozzles based on the generated ejection data.
It is determined whether or not all the image data has been printed, and these operations are repeated until all the image data has been printed (step S7).
Here, an example of the operation has been described based on the mask pattern shown in FIGS. 9 and 10 and the number of drops of the input gradation of the image data.

  The present invention can be used for an ink jet printer.

DESCRIPTION OF SYMBOLS 1 ... Recording device, 20 ... Control part, 21 ... CPU, 22 ... ROM, 23 ... RAM, 24 ... EEPROM, 25 ... Operation panel control part, 26 ... Print control unit, 27 ... carriage control unit, 28 ... paper conveyance control unit, 29 ... host I / F unit, 30 ... image memory, 31 ... image memory write / read control unit , 41 ... print head, 42 ... carriage mechanism, 43 ... paper transport mechanism, 44 ... operation panel, 45 ... linear encoder

Claims (11)

A print head comprising a plurality of nozzles, discharging ink from the nozzles to a recording medium, and forming dots of different sizes on the recording medium;
Conveying means for conveying the recording medium;
A carriage mounted with the print head and reciprocatingly scanned in a direction intersecting the conveyance direction of the recording medium;
A print mask serving as a reference for determining whether or not to eject the ink from the nozzle;
Control means for generating print data indicating whether or not to discharge the ink from the nozzles from the input image data and the print mask, and for controlling the discharge of the print head;
Have
The pixel data for each dot formed on the recording medium included in the image data includes a value corresponding to each of the sizes, and is based on the print data generated by the control unit. In a recording apparatus that ejects the ink from a print head,
The print mask has at least two print modes, a normal mode and a special mode, and the print mask is assigned 1 bit for each of the pixel data, and the control means generates the print data different for each print mode,
In the case of the normal mode, the control means
When the value of the print mask is one value, the value of the pixel data is the value of the print data, and when the value is the other value, the print data is a non-ejection value regardless of the value of the pixel data,
In the case of the special mode, the control means is
When the pixel data is a predetermined value and the value of the print mask is the one value, a predetermined first value for forming the dot equal to or less than the predetermined value is set to the print data. Value and
When the pixel data is the predetermined value and the value of the print mask is the other value, it is equal to or greater than the value that forms the minimum dot and less than or equal to the value that forms the maximum dot. Yes, and a predetermined second value which forms the dots the corresponding value that is a predetermined value larger predetermined value than the value of the print data when the sum of the first value,
When the pixel data is other than the predetermined value and the print mask value is the one value, the value of the pixel data is the value of the print data,
When the pixel data is other than the predetermined value and the print mask value is the other value, the print data is set as a non-ejection value regardless of the value of the pixel data.
A recording apparatus, wherein the ink is ejected from the print head in correspondence with the print data.   The recording apparatus according to claim 1, wherein the predetermined value is a value that forms a maximum one of the dots formed on the recording medium.   The recording apparatus according to claim 1, wherein the first value is a value that forms a minimum dot among the dots formed on the recording medium.   The recording apparatus according to any one of claims 1 to 3, wherein the normal mode and the special mode are determined for each color of the ink.   The nozzles of the print head are arranged along the transport direction, the nozzles are divided into a plurality of blocks in the transport direction, and the first value is set in one block among the divided blocks. 5. The method according to claim 1, wherein the second value is used as the value of the print data in one of the other blocks. The recording device described.   Each of the blocks is divided into a plurality of regions having the same width, and the transporting unit transports the recording medium according to the width of the divided region, and the region is arranged in a portion for each width of the region on the recording medium. 6. The recording apparatus according to claim 5, wherein the scanning is performed a number of times equal to the number of the inks, and the ink is ejected from the different regions for each scanning to complete an image on the recording medium.   The nozzle is divided into two blocks, the upstream block in the transport direction of the print head and the downstream block, and the upstream block uses the first value as the print data value. If the second block is used as the print data value in the downstream block, the second block is used as the print data value in the upstream block. The recording apparatus according to claim 5, wherein the first value is used as the value of the print data in the block.   The nozzles of the print head are divided into even regions of 4 or more, half of the regions are allocated to the upstream side of the regions, and the remaining half of the regions are allocated to the downstream side. Further, according to the width of the area, the transport means transports the recording medium, performs the scanning of the even number of four or more times on the part of the width of the area on the recording medium, and is different for each scanning. The recording apparatus according to claim 7, wherein the ink is ejected from a region to complete an image on the recording medium. The first value is a value that forms the largest dot among the dots formed on the recording medium, and the second value is the smallest value among the dots formed on the recording medium. The recording apparatus according to claim 2 , wherein the recording apparatus is a value forming a thing . And said first value said predetermined value, wherein the second value to claim 1, characterized in that a value for forming the smallest among the dots formed on the recording medium Recording device. A print head comprising a plurality of nozzles, discharging ink from the nozzles to a recording medium, and forming dots of different sizes on the recording medium;
Conveying means for conveying the recording medium;
A carriage mounted with the print head and reciprocatingly scanned in a direction intersecting the conveyance direction of the recording medium;
A print mask serving as a reference for determining whether or not to eject the ink from the nozzle;
Control means for generating print data indicating whether or not to discharge the ink from the nozzles from the input image data and the print mask, and for controlling the discharge of the print head;
Have
The pixel data for each dot formed on the recording medium included in the image data includes a value corresponding to each of the sizes, and is based on the print data generated by the control unit. In a recording method of a recording apparatus for discharging the ink from a print head,
A step of generating at least two print modes of a normal mode and a special mode, wherein the print mask is assigned one bit to the pixel data, and the control means generates the print data different for each print mode. And ejecting the ink in correspondence with the print data from the print head,
In the case of the normal mode in the step of generating the print data, the step of setting the value of the pixel data as the value of the print data when the value of the print mask is one value, and the case of the value when the value is the other A step of setting the print data to a non-ejection value regardless of the value of the pixel data,
In the case of the special mode in the process of generating the print data, when the pixel data is a predetermined value and the print mask value is the one value, the predetermined value or less. A step of setting the predetermined first value for forming the dot to the value of the print data, and when the pixel data is the predetermined value and the value of the print mask is the other value, and the minimum of the values forming the dot or more, and the maximum of the dot when the value form below, and said first value becomes the larger predetermined value than a predetermined value when the sum of the values A step of setting a predetermined second value for forming the dot corresponding to the value of the print data, and when the pixel data is other than the predetermined value and the value of the print mask is the one of the values when The step of setting the value of the pixel data as the value of the print data, and when the pixel data is other than the predetermined value and when the value of the print mask is the other value, regardless of the value of the pixel data And a step of setting the print data to a non-ejection value.