WO2012023411A1

WO2012023411A1 - Printing system and printing method

Info

Publication number: WO2012023411A1
Application number: PCT/JP2011/067445
Authority: WO
Inventors: 節竹内
Original assignee: 株式会社セイコーアイ・インフォテック
Priority date: 2010-08-20
Filing date: 2011-07-29
Publication date: 2012-02-23
Also published as: JP5877666B2; JP2012061846A

Abstract

The present invention provides a printing system which enables high-gloss print at a high concentration while reducing defective print such as color banding. The present invention makes it possible to use the effects of "spreading" to prevent defective print such as bi-directional banding which is caused by printing colors over another in two ways each in a different order, boundary banding, beading, and solid faint print. It is also possible to prevent the occurrence of a slight feeling of graininess and the degradation of the feeling of gloss, which can be said to be adverse effects of the "spreading." Furthermore, the white streaking or solid faint print or the like which may particularly occur in a combination with paper sheets having reduced dot diameters can be made unnoticeable by increasing the amount of discharge per unit area without decreasing the print speed. It can be thus expected to achieve a high print quality with stability.

Description

Recording apparatus and recording method

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 stacking order of dots ejected and landed from each color print head in the forward pass and the return pass is changed depending on the print head arrangement order. There is a problem that so-called bidirectional color banding occurs.

For example, Japanese Patent Application Laid-Open No. 2003-226004 discloses a drawing based on a color swath to which a non-uniform print mask function is applied, which lowers the probability of using nozzles corresponding to the peripheral region at the end compared to other nozzles. A technique for making bidirectional color banding inconspicuous by performing an operation is disclosed.

JP 2003-226004 A

As described above, the cause of the bi-directional color banding is that the color stacking order differs between the forward pass and the return pass. Among them, the first scan (first scan) and the last scan (first scan) drawn on the paper are among them. The contribution rate of the final scan is high. The former is explained by the fact that the ink ejected on the paper for the first time spreads in a short time and forms large dots, and the ink ejected later forms a slightly smaller dot on the spread ink. it can. In other words, the influence of the first ejected color in the first scan and the print head color positioned in the front of the carriage traveling direction become strong. For the latter, the influence of this color is strong because the print head color located at the end of the final scan, that is, the rear of the carriage traveling direction is at the top of the print surface. An example of typical bidirectional color banding is shown in FIG. FIG. 3A shows a proper image. FIG. 3B is a diagram illustrating an example of bidirectional banding. Striped patterns appear in images with bidirectional banding, and the quality is poor compared to proper images.

Also, bi-directional color banding may occur between the left and right edges of the print area. Even within an area where the order of color overlap is the same, the time difference between the forward path and the backward path is large near the origin in the main scanning direction (direction in which the carriage scans). In other words, it takes time to draw at the beginning of the outbound trip and at the end of the return trip. On the other hand, at the end opposite to the origin, the time difference drawn from the forward path to the return path is small. This time difference causes a difference in the dry state of the dots on the paper in the immediately preceding scan, so that the nature of the ink ejected thereon naturally changes. In other words, color banding occurs due to the time difference.

If you want to print large posters or advertisements, there is a technique called tiling that arranges multiple small prints horizontally to make a large print. When there is color banding at the left and right ends, when tiling, the color difference between the joints of the printed matter becomes conspicuous, and the image quality may be significantly reduced.

In Japanese Patent Laid-Open No. 2003-226004, a non-uniform print mask function is applied to the color swath for dark ink colors (for example, cyan, magenta, and black), and a uniform print mask function is applied to light ink colors (for example, yellow). This makes bidirectional color banding less noticeable.

However, by applying a non-uniform print mask function, when attention is paid to a certain scan, the difference in nozzle use probability increases near the non-uniform end of the color swath. This is nothing but a difference between the drawing process for forming dots in a certain area and the drawing process for forming dots in another area. This is the same as the cause of the color banding due to the time difference between the left and right ends. This is more conspicuous when the print mask function uses a polygonal line or S-shaped gradation curve and has a steep slope such as 0% to 100% or 100% to 0%. Color banding corresponding to the gradation curve constituting the non-uniform print mask function will occur.

Furthermore, in the color swath, the difference between the non-uniform portion of the print mask function and the uniform portion may appear as color banding. This is because the non-uniform upper and lower areas of the print mask function complement each other and form a conventional dot for one scan. The number will increase. That is, a difference occurs in the time until the image is completed. This difference is exactly the cause of the color banding because it is different between the drawing process for forming dots in one area and the drawing process for forming dots in another area.

For bi-directional color banding, instead of bi-directional printing, uni-directional printing can be used to unify the ink color stacking order and time difference for the entire drawing area. This reduces color banding, but is not practical because the printing speed is reduced by a factor of 1/2 compared to bidirectional printing. In addition, in unidirectional printing, image quality defects due to specific vibrations on the carriage travel path are accumulated every scan, which may lead to image quality defects such as vertical stripes and color unevenness.

In addition, by mounting two or more print heads for each color so that the colors are arranged symmetrically on the carriage, it is possible to unify the color stacking order regardless of the forward or backward path. Since a double or more head is required, the cost increases such as an increase in the size and weight of the carriage and an increase in the size of an actuator for driving the carriage.

In addition, when the positioning accuracy at the time of paper conveyance is poor or the paper conveyance amount itself is not appropriate, streaks that darken or lighten may appear at the upper and lower ends of the color swath. These are border bandings called black stripes, white stripes, and so on. An example of this is shown in FIGS. 4 (a) and 4 (b). FIG. 4A shows an example of boundary banding. FIG. 4B is an example of boundary banding. These appear as streaks with a difference in color density between the upper and lower ends of the color swath and the other portions. In order to prevent these problems, it is necessary to adjust the sheet conveyance amount as appropriate. However, it is difficult to keep the conveyance amount constant for a long period of time.

Boundary banding can also occur on a specific sheet due to slow drying after ink landing. Inside the color swath, since ink is present with high probability around the ink, the ink becomes a wall and the movement of the ink is prevented. However, at the end of the color swath, that is, the edge, there is a space where nothing exists on one side, so that the ink easily moves. A so-called phenomenon called “mottling” occurs, and as a result, only this edge portion causes a change in hue from other regions. This phenomenon is sometimes called beading.

Furthermore, for certain paper, the dot diameter after landing may be small. In this case, density unevenness easily occurs due to slight deviation in landing. In general, the density strength often appears as horizontal stripes in the paper feed direction. This is a phenomenon called “hot weather”. An example of this is shown in FIG. FIG. 5 is a diagram showing an example of blurring. This is an example in which density unevenness occurs in a portion where landing deviation occurs and appears as white streaks.

On the other hand, a non-uniform print mask function is applied in which the probability of using the nozzle corresponding to the peripheral area of the edge of the color swath drawn in one scan during bidirectional printing is lower than that of other nozzles. The width of the peripheral area substantially matches the width of a positive integer multiple of the transport pitch when transporting the recording medium, so that the color stacking order differs depending on the forward path and the backward path. In addition, it is known to be effective for various printing defects such as boundary banding, beading, and blurring. At this time, as in the printing mode shown in FIG. 7, it is extremely effective for various printing defects to have a relationship in which the upper and lower blocks of the color swath drawn in one scan are completely complemented. In this case, although the printing speed is reduced to ½, the effect is more effective than simply doubling the number of passes or reducing color banding by unidirectional printing as in the conventional high-quality printing mode. Is big. This is because all the dots to be drawn are complemented equally by the upper and lower blocks, and all mechanical errors and the selective and intensive behavior of ink are alleviated. This is a so-called “scattering” effect.

However, in the first place, this technology can be rephrased as a technology that makes the impact of all disturbances less noticeable by slightly deteriorating the dot landing accuracy, that is, by “scattering”. Therefore, as a result of slightly deteriorating the landing accuracy, it is inevitable that the finished printed product will have a graininess and a matte feeling. This can also be explained by an increase in the number of nozzles that are not ejected in one scan, that is, a decrease in the head duty and a decrease in the apparent ejection frequency in order to achieve complete complementation by the upper and lower blocks. Depending on the combination of ink and head, a decrease in the discharge frequency means a decrease in the dot volume. In particular, depending on the combination with paper that has a small dot diameter and that has poor wettability, a slight graininess may be produced. is there. Furthermore, a decrease in head duty also means a decrease in the probability of ink being ejected continuously. Like in the printing mode shown in FIG. 6, since the continuous ejection is performed in the high printing rate area unless the head duty is 100%, that is, the upper and lower blocks are complemented, the probability of the connection of adjacent dots on the paper. It can be said that the horizontal line can be drawn without any break. On the other hand, in the vertical complement, since one horizontal line is divided by a plurality of scans, it can be said that the probability that one line is divided increases. This means that the glossiness is lost in exchange for suppressing selective and intensive printing defects such as white streaks and shading.

Also, especially in combination with paper that lands with a small dot diameter, simply increasing the printing resolution may be a measure against white streaks and blurring. This is a measure for improving printing defects such as solid printing mainly having a high printing rate by increasing the discharge amount per unit area, that is, the dot density. The conventional high density printing mode can be said to be the same idea. However, increasing the printing resolution and the high density printing mode are accompanied by a decrease in the carriage speed and an increase in the number of passes, so a decrease in the printing speed is inevitable.

The present invention has been made in view of such circumstances, and color banding at the time of bidirectional printing in the recording apparatus, boundary banding and beading, white streaks and blurring can be made inconspicuous, It is an object of the present invention to provide a recording apparatus and a recording method that suppress the occurrence of slight graininess and the decrease in glossiness that appear as adverse effects. Further, a recording apparatus and a recording method capable of making white stripes, blurring, etc. inconspicuous in combination with a paper having a small dot diameter and landing by increasing the discharge amount per unit area without reducing the printing speed The purpose is to provide.

The recording apparatus of the present invention is a recording apparatus which ejects ink while scanning the same recording area of the recording medium a plurality of times to form an image on the recording medium, and the nozzles of the printing head are recorded on the recording medium. Divided into a plurality of nozzle groups for each width of the medium transport amount, the nozzle group is divided into a plurality of blocks, and at least two of the blocks are in the transport direction of the recording medium with the center of the nozzle row as a boundary Arranged separately on the upstream side and the downstream side in the transport direction, each of the nozzle groups included in the two blocks has a lower printing rate as the nozzle is closer to the end of the print head, and the printing rate is lower than that of the image. A print mask for selectively ejecting the ink from the nozzles according to a non-uniform print mask function having a value in which a part of dots on the same line along the scanning direction overlap. The print head discharges the ink to the recording medium based on the print mask, and dots formed on the recording medium by the ink discharged from the nozzle groups included in the different two blocks are formed. It overlaps with a predetermined probability.

Also, the recording method of the present invention is a recording method for a recording apparatus that forms an image on the recording medium by ejecting ink while causing the printing head to scan the same recording area of the recording medium a plurality of times. The nozzles are divided into a plurality of nozzle groups for each conveyance amount width of the recording medium, the nozzle groups are divided into a plurality of blocks, and at least two of the blocks are recorded on the boundary of the center of the nozzle row. The nozzle group is arranged separately on the upstream side and the downstream side in the transport direction of the medium, and each of the nozzle groups included in the two blocks has a lower print rate as the nozzle is closer to the end of the print head, and the print rate Is a pre-jet that selectively ejects the ink from the nozzles according to a non-uniform print mask function having a value in which some of the dots on the same line along the scanning direction of the image overlap. The print head discharges the ink to the recording medium based on the print mask, and is formed on the recording medium by the ink discharged from the nozzle groups included in the different two blocks. And a step of performing a drawing operation in which dots overlap each other with a predetermined probability, and a step of transporting the recording medium at a transport pitch having a width of the nozzle group.

According to the present invention, in addition to bi-directional banding caused by the difference in color stacking order between the forward path and the return path, printing defects such as boundary banding, beading, and blurring can be suppressed using the “scattering” effect. In addition, it is possible to suppress the occurrence of graininess and the reduction in glossiness, which can be said to be a negative effect of “scattering”. Further, according to the present invention, by increasing the discharge amount per unit area without reducing the printing speed, it is possible to make inconspicuous white streaks and blurring caused particularly in combination with a paper having a small dot diameter.

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 shows a proper image. FIG. 3B is a diagram illustrating an example of bidirectional color banding. FIG. 4A is a diagram illustrating an example of boundary banding. FIG. 4B is a diagram illustrating an example of boundary banding. FIG. 5 is a diagram illustrating an example of smoothness. FIG. 6 is a diagram showing the principle of drawing in a printing mode called 4-pass. FIG. 7 is a diagram showing the principle of drawing in the print mode to which an embodiment of the present invention is applied. FIG. 8 is a diagram illustrating an example of a color swath having a large effect of suppressing boundary banding and beading to which a non-uniform print mask function is applied. FIG. 9 is a diagram illustrating an example of a color swath that applies a non-uniform print mask function, has a large effect of suppressing boundary banding and beading, and has a print rate of 130%. FIG. 10 is a diagram illustrating an example of a color swath that applies a non-uniform print mask function, has a large effect of suppressing boundary banding and beading, and has a print rate of 150%. FIG. 11 is a diagram showing the principle of drawing in the print mode to which a different embodiment of the present invention is applied. FIG. 12 is a diagram illustrating an example of a color swath that emphasizes glossiness.

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 controls the overall processing operation in the control unit 20, a ROM 22 of a storage unit in which a program for performing a printing operation and the like are stored in advance, and each control unit is operated during the execution of the printing operation. The RAM 23 serving as a storage unit used as a storage area, the EEPROM 24 serving as a storage unit configured by a non-volatile memory that stores setting values and data immediately before the power is turned off, and the operation panel 44 are equipped with an operation panel. An operation panel control unit 25 that displays information on the display unit, a print control unit 26 that is a control unit that controls the printing operation of the recording medium by the print head 41, and a carriage that is a control unit that controls the operation of the carriage mechanism 42. The control unit 27 controls the operation of the paper transport mechanism 43 composed of grid rollers and the like to transport the paper. A sheet conveyance control unit 28 as control means, an image memory 30 for storing an image to be printed, an image memory writing / reading control unit 31 for performing writing / reading control on the image memory 30, a host computer and image data and control commands The host I / F unit 29 is an interface for inputting / outputting.

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

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 increasing the positional accuracy of the droplets that have landed on the paper 422 as a recording medium. In this example, four color print heads 41 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. Yes. 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. 6 shows this state focusing on only 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 was used as the paper conveyance amount, but here, ８ of the used nozzle range is used. The non-uniform area of the print mask function is ½ each above and below the used nozzle range of the head. That is, the print head is divided into 8 nozzle groups for each conveyance amount, and the upper and lower blocks are divided into the upper 4 nozzle group and the lower 4 nozzle group.

Conventionally, for example, the print mask function shown in FIG. 8, that is, the gradation curve thereof, is S-shaped, the upper block connecting 30% to 70%, and the lower block connecting 70% to 30%. In this case, the dots constituting the entire drawing area are complemented by the upper and lower blocks. Since all the dots are in a complementary relationship, a large “scattering” effect can be provided, and various printing defects that have been a problem in the past can be suppressed. The upper end to the lower end indicated by the arrow of the color swath width in FIG. 8 correspond to the nozzle use range of the head, and the line indicating the distribution of the print ratio on the right is the print rate of each nozzle within the nozzle use range of the head. Is shown. The line from the top to the bottom corresponds to the print mask function. The printing rate is uniquely specified for each nozzle and indicates the probability that ink can be ejected in one scan. A print mask is configured in accordance with the print mask function, and ink is selectively ejected from the head by the print mask. If the blocks are divided into upper and lower parts, thereby complementing the respective recording ranges, and the image is completed in 8 scans, the head is divided into 8 equal parts, and 1/4 of the completed image per scan. Will be printed at a predetermined printing rate. If the print mask function is uniform, the printing rate of one scan is 50% in any nozzle of each divided head region. However, if a non-uniform print mask function is used, the print mask function is configured so that the sum of the print ratios of nozzles in a complementary relationship becomes 100%. That is, if the printing rate of the nozzles at the upper end of the upper block for creating the color swath in FIG. 8 is 30%, when an image is completed in 8 scans, the image is 1/4 of the completed image. The print mask is configured so that ink can be ejected with a probability of 30%. Then, the printing rate of the nozzle complementary to the nozzle, that is, the nozzle at the end on the upper block side of the lower block is 70%. Then, it is determined whether or not the image data is selectively ejected according to the print mask, and ink is ejected from the head accordingly. Similarly, the print mask function is S-shaped in the range of 30% to 70% so that the sum of the printing ratios of the other nozzles that are complementary to each other is 100%, depending on the position of the nozzle. It forms non-uniform print mask functions with different print rates. In FIG. 8, the head is divided into an upper block and a lower block. The print mask is configured so that the dots of the image that is completed in 4 scans using the upper block and the dots that are completed in 4 scans using the lower block do not overlap each other, and ink is ejected to areas where no dots are formed. Will be.

Next, FIG. 9 shows a print mask function used in an embodiment of the present invention. In this case, the print mask function is a non-uniform print mask function in which the printing rate is lower as the nozzle is closer to the end of the print head. The gradation curve is S-shaped, and the upper block connects 45% to 85% and the lower block connects from 85% to 45%. If the gradation curves of the upper and lower blocks are added together, it becomes 130% at any point by simple calculation. That is, as in the case shown in FIG. 8, up to 100% of the added gradation maintains the relationship in which one dot is complemented by the upper and lower blocks, while the upper and lower portions are up and down, up to 130%. Dots are drawn with overlapping blocks. Strictly speaking, these dots are ejected at the same position, but they often land at a slightly deviated point due to the effect of “scattering” described above. Eventually, since there are 30% overlapping dots due to the upper and lower blocks, the image is completed with the total number of dots of 130% of the conventional. In other words, it can be said that high density printing was performed with a printing rate of 130%.

Similarly, if the print mask function shown in FIG. 10 is used, when the gradation curves of the upper and lower blocks are added together, it becomes 150% at any point by simple calculation. That is, in this case, it can be said that high density printing with a printing rate of 150% was performed.

As shown in these examples, in addition to bidirectional banding, in the print mode supplemented by the upper and lower blocks as shown in FIG. 7 to suppress printing defects such as boundary banding, beading, white streaks, and shading. Thus, a certain amount of high density printing can be performed without changing the printing speed. As a result, the above-described various printing defects can be suppressed, and the occurrence of slight graininess and a decrease in glossiness, which can be said to be an adverse effect of “scattering”, can be suppressed. Also, white streaks and blurring caused by a combination with paper having a small dot diameter can be suppressed by the effect as if high density printing was performed.

However, the effect of “scattering” and the effect of “high density printing” are contradictory within the same printing speed category, and the balances of the examples of the printing rates of 100%, 130%, and 150% shown above were changed. It should be noted that it is only. That is, at the printing rate of 100% by the print mask function shown in FIG. 8, “high density printing” is not performed with emphasis on “spattering”. At the printing rate of 130% by the print mask function shown in FIG. While emphasizing “scattering”, the print mask function shown in FIG. 10 gives the effect of “high-density printing” to a print rate of 150%. Even if “scattering” is slightly sacrificed, “high-density printing” It is said to increase the effect of. In principle, if the print mask function is set to 100% for both the upper and lower blocks, all the dots that make up the entire drawing area will be ejected in duplicate. Is equivalent to This can be said to be specialized for “high density printing” without any “scattering”.

Up to this point, an example in which the upper and lower blocks of the head as shown in FIG. 7 completely complement each other has been described. However, as shown in FIG. Also good. In this case, since dots can be overlapped up to 1/5 minutes of the used nozzle range, the printing rate is about 125% at the maximum. That is, the head is divided into five nozzle groups, and the recording medium is conveyed for each width of the nozzle groups. Then, the image is completed in 5 scans, and in that case, in each 1 scan, the block at one end of the head and the block at the other end are 1/8 of the image to be completed, and the other 3 blocks are 1 of the image to be completed. By performing / 4 printing, printing without overlapping dots can be performed. At this time, the print mask according to the non-uniform distribution print mask function in which the dots formed in the block at one end and the block at the other end of the head do not overlap with each other, and the printing rate decreases as the position is closer to the end. Thus, dots are formed at positions that are not formed with each other. Further, the printing rate of the block at one end and the block at the other end of the head can be increased. In 5 scans, the image is completed. In each scan, the block at one end of the head and the block at the other end are 1/4 of the completed image, and the other 3 blocks are 1/4 of the completed image. Is printed, the dots formed by the block at one end of the head and the block at the other end all overlap. At this time, the overlapping amount of dots on the same line forming an image can be controlled by changing the printing rate of the block at one end and the block at the other end of the head. By forming the print ratio of the block at one end of the head and the block at the other end in the range of more than 50% and less than 100%, they are mutually formed by the print mask according to the non-uniform distribution print mask function It is possible to form dots at positions where no dot is formed and further overlap some dots. Strictly speaking, when the print mask function is made non-uniform, the printing rate is less than 125%. If the upper and lower blocks of 1/3 of the used nozzle range complement each other (not shown), the printing rate is about 150% at the maximum.

As described above, if the result of adding the gradation curves of the upper and lower blocks for the print mask function is made larger than 100%, it is possible to perform drawing with a printing rate larger than 100%. In other words, for each print mode, a print mask function for drawing at several print rate values is tabulated, and the user can select an arbitrary value from the print mask function to obtain a print image quality suitable for the user's application. You can choose. For example, this table is called “high density mode”, and weights from 1 to 4 are assigned. Usually, since priority is given to image quality, when printing on transparent paper for use in electrical decoration, Mode 1, which has the greatest “spattering” effect, is 100%. Mode 4 is obtained. If you are concerned about slight graininess or gloss reduction due to the effect of “scattering”, mode 2 can be printed with 130% printing ratio. In order to achieve this, it is conceivable that mode 3 in which a printing rate of 150% is obtained is selected. Further, for each paper to be used, the recommended values of the printing ratio may be stored on the printer side as preset values.

If “glossiness” is emphasized, the probability of overlapping dots is greatly changed for each line in the sub-scanning direction (paper feeding direction) of printing, so that the probability of hitting twice every other line is increased. It can also be considered. According to this, in a line with a high printing rate appearing every other line, in the main scanning direction (direction in which the carriage scans), the landing dots are promoted to be combined on the medium, and leveling, that is, a smoothing effect is brought about. An improvement in glossiness can be expected.

Also, as shown in FIG. 12, based on a fine periodic color swath, for example, every other dot in the main scanning direction, a fixed amount of dots are placed in the sparse, ie, originally masked portion, that is, the mask is released. You may create a color swath as you do. In this case, the fine periodic dot arrangement facilitates dot combination in the main scanning direction, and the probability that dots are combined in the sub-scanning direction is also periodically increased, which makes leveling easier. This can also be expected to improve glossiness. However, since the “scattering” effect is reduced by emphasizing the glossiness, it is preferable to use these color swaths properly depending on the image to be printed. In other words, if you want to print “solid” with an emphasis on glossiness, use these color swaths, and if you want to print with a “natural image” effect and focus on the effect, use the conventional color swaths. , And so on.

As described above, in addition to bi-directional banding, which is caused by the difference in color stacking order between the forward path and the return path, printing effects such as border banding, beading, and blurring are suppressed using the “scattering” effect. In addition, it is possible to suppress the occurrence of a very slight graininess and a decrease in glossiness, which can be said to be an adverse effect of “scattering”. In addition, by increasing the discharge rate per unit area without reducing the printing speed, it is possible to make the white streaks and shading caused by the combination with paper printed with a small dot diameter inconspicuous and stable. High print image quality can be expected.

The present invention can be used for an ink jet recording apparatus.

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

In a recording apparatus that ejects ink while scanning the print head multiple times with respect to the same recording area of the recording medium, and forms an image on the recording medium,
The nozzles of the print head are divided into a plurality of nozzle groups for each conveyance amount width of the recording medium, the nozzle groups are divided into a plurality of blocks, and at least two of the blocks are arranged at the center of the row of nozzles. The boundary between the recording medium upstream in the transport direction and the downstream in the transport direction is arranged, and each of the nozzle groups included in the two blocks has a lower printing rate as the nozzle is closer to the end of the print head. In addition, the print rate is configured to form a print mask that selectively ejects the ink from the nozzles according to a non-uniform print mask function having a value in which a part of dots on the same line along the scanning direction of the image overlap. The print head ejects the ink onto the recording medium based on the print mask, and the ink ejected from the nozzle groups included in the different two blocks. Recording apparatus dots formed on the recording medium by click, characterized in that the overlap with a predetermined probability.
The print mask function is configured so that the image formed on the recording medium has the same probability that the dots overlap each line along the scanning direction. The recording device described.
3. The recording apparatus according to claim 1, wherein the print mask has a sparse / dense distribution with a probability that the dots overlap in a predetermined cycle in the scanning direction.
Each of the two blocks includes the nozzle group disposed at the end of the print head,
4. The nozzle group that is not disposed at the end of the print head is interposed between the nozzle groups that are disposed at the end of the print head. Recording device.
Different combinations of the print head division number, the block division number, and the print mask function are stored in the storage means in association with each of a plurality of print modes, and when one of the print modes is selected, According to the selected print mode, the number of print head divisions, the number of blocks, and the print mask function associated with the selected print mode are acquired from the storage unit, and based on the acquired value Dividing the print head into a plurality of blocks, dividing the nozzles of the print head into a plurality of nozzle groups, and applying the acquired print mask function to eject the ink onto the recording medium. The recording apparatus according to claim 1, wherein the recording apparatus is a recording apparatus.
Different combinations of the print head division number, the block division number, and the print mask function associated with each print mode are stored in a table prepared in the storage means and operated by a user. The recording apparatus according to claim 5, wherein the printing mode is selected by an input unit.
In a recording method of a recording apparatus for ejecting ink while causing the print head to scan the same recording area of the recording medium a plurality of times and forming an image on the recording medium,
The nozzles of the print head are divided into a plurality of nozzle groups for each width of the conveyance amount of the recording medium, and the nozzle groups are divided into a plurality of blocks, and at least two of the blocks are bordered by the center of the row of nozzles. Are arranged separately on the upstream side and the downstream side in the transport direction of the recording medium, and the nozzle group included in the two blocks has a lower printing rate as the nozzle is closer to the end of the print head, and The print rate comprises a print mask that selectively ejects the ink from the nozzles according to a non-uniform print mask function having a value in which some of the dots on the same line along the scanning direction of the image overlap. The print head ejects the ink onto the recording medium based on the print mask, and the ink ejected from the nozzle groups included in the different two blocks. And a step of performing a drawing operation in which dots formed on the recording medium overlap each other with a predetermined probability, and a step of transporting the recording medium at a transport pitch of the width of the nozzle group. Method.