JP4217708B2 - Recording apparatus and recording method - Google Patents

Description

  The present invention relates to a recording method and a recording apparatus for obtaining an image on a recording material, and more particularly to a recording method and a recording apparatus for performing recording by so-called multipass recording.

  Conventionally, the ink jet recording method has advantages such as low noise, low running cost, easy downsizing of the apparatus, and easy colorization, and is widely used in printers and copiers. In such a recording apparatus, in order to improve the recording speed, a recording head in which a plurality of recording elements (nozzles for ejecting ink in the ink jet recording method) are integrated is used.

  By the way, in such a recording apparatus using a recording head in which a plurality of recording elements are arranged, as one of the factors that deteriorate the image quality, streaky density irregularities appearing periodically in the sub-scanning direction (recording medium conveyance direction). It has been known. Such periodic stripes are extremely visible. For example, in the case of an ink jet method, streaks are caused by variations in the discharge amount and discharge direction of each nozzle, a shift in paper feed amount and print pitch, and a change in density due to a print time difference between each scan. There is.

  On the other hand, various methods for reducing streak and improving image quality have been disclosed.

  For example, in Patent Document 1, a plurality of scans in the main scanning direction (hereinafter also simply referred to as “scans”) occur at the boundary of the area (hereinafter also referred to as “joint”) printed by the recording head for each scan. In order to eliminate the streak lines, the lower end of the portion printed in the previous scan overlaps the uppermost portion of the portion printed in the current scan, and printing is selectively performed in the two overlapping scans. Is disclosed.

  A well-known method for further improving image quality is a divided recording method (multipass recording method). Hereinafter, this divided recording method will be described.

  In an ink jet system, a recording head having a plurality of nozzles may cause slight variations from nozzle to nozzle in the manufacturing process. Such variations appear as variations in the ink ejection amount and ejection direction of each nozzle at the time of printing, and ultimately cause image quality to deteriorate as density unevenness such as stripe unevenness in the printed image. An example is shown in FIG. FIG. 10A shows that the volume and direction of ink ejected from each nozzle vary in a head constituted by eight ink ejection nozzles. When printing is performed as it is with nozzles having such variations in ejection characteristics, dots having different sizes and landing positions are formed for each print line corresponding to the nozzles, as shown in FIG. 10B. Become. As a result, a white background portion as seen in the central portion of the figure is present, or conversely, a dot overlaps more than necessary. FIG. 10C shows an image density distribution in which such dot formation has been performed. Such density unevenness is recognized as streak unevenness and causes a reduction in image quality.

  On the other hand, the divided printing method (multi-pass printing method) does not record all the recording pixels by one movement of the recording head in the main scanning direction (one scan), but divides it into a plurality of scans. In this method, the nozzles used for printing are different for each scanning. FIG. 11 is an explanatory diagram when multi-pass printing is performed using the same head as shown in FIG. As shown in FIG. 11A, the print head shown in FIG. 10 is scanned three times by the recording head, but each of the four vertical pixels, which is half of the print area, is scanned twice. Each print is completed. In this case, the 8 nozzles of the recording head are divided into groups of upper 4 nozzles and lower 4 nozzles, and the dots that one nozzle prints in a single scan halves the desired image data according to a predetermined method. Thinned out. Then, by feeding the paper for 4 pixels, a nozzle different from the nozzle used for the initial printing corresponds to the printing position, and the dot is complementarily formed by the image data thinned out for the remaining half. To complete the printing. When such a recording method is used, since one raster (one dot line in the main scanning direction) can be recorded with ink ejected from different nozzles, the influence of variations among nozzles can be reduced. As shown in (b) and (c), uneven density can be reduced.

  When such divided recording is performed, image data is extracted in accordance with a predetermined rule in the first scan and the second scan, and the image data is divided so as to be interpolated in two scans. This extraction is usually performed by mask processing, and the most common mask is a pattern that is exactly a staggered pattern for each vertical and horizontal pixel as shown in FIG. In the unit printing area (in this case, in units of four pixels), the first scan that prints a staggered pattern as shown in FIG. 12A and the second scan that prints an inverted staggered pattern as shown in FIG. Printing is completed by two scans (2 passes).

  Increasing the number of divisions (number of passes) in the multi-pass printing method as described above is effective for improving image quality. For example, when comparing two-pass printing and ten-pass printing, one raster is completed using two different nozzles in two-pass printing, whereas ten different nozzles are completed in ten-pass printing. The degree to which the variation in the ejection characteristics of the individual nozzles contributes to the printing result is relatively small, and the influence is small as a whole, and as a result, the unevenness becomes inconspicuous.

  In Patent Document 2, in addition to the above-described multi-pass printing method, for a recording medium that is particularly fast-absorbing for the purpose of further improving the image quality, the number of scans for the areas on both sides of the joint portion is compared with other areas. Focusing on the fact that the number of scans until the printing is completed is large, a method of reducing the printing ratio in the regions on both sides facing the boundary is disclosed.

  However, in any of the multi-pass printing described above, if the relationship between the paper feed amount and the nozzle pitch of the print head is deviated, it is inevitable that a so-called joining line will occur. This will be described with reference to FIG.

  FIG. 13 shows an example of printing in the case of two-division recording (two-pass recording), and shows the case where printing is performed using an 8-nozzle head, as described in FIG. For the sake of clarity, the description will be made assuming that the eight nozzles have no variation in ejection characteristics for each nozzle. The mask for division uses a houndstooth pattern. That is, the mask is used for the odd-numbered scan and the reverse-staggered-type mask is used for the even-numbered scan, and the recording is completed by two scans.

  FIG. 13A shows a printing result in a case where paper feeding of 4 pixels is performed accurately in each of two paper feedings. For the sake of simplicity of explanation, the dots printed in the first scan and the dots printed in the third scan are displayed on the right side of the figure, and the dots printed in the second scan are not shown. The lower end of the area printed in the first scan is adjacent to the upper end of the area printed in the third scan, and the boundary between these areas forms a joint between the scans. As shown in FIG. 13 (a), when paper feed for 8 pixels is accurately performed by paper feed twice, the dots to be recorded are accurately arranged at the joint of the scan, and no streak is generated.

  On the other hand, FIG. 13B shows a printing result when the paper feed amount is larger than the normal amount for four pixels. As in FIG. 13A, only the dots printed by the first scan and the third scan are shown on the right side of the figure. Paper feed is performed twice from the first scan to the third scan, but since each paper feed is larger than 4 pixels, the paper feed is larger than 8 pixels between the first scan and the third scan. Is done. Therefore, the dot group printed by the third scan is recorded away from the dot group printed by the first scan by the paper feed error. The gap between the scans is recognized as a white streak in the image and causes a high image quality.

  If the paper feed amount is less than normal and the error appears negative, it is recognized as a black streak. Further, in this description, there is no error in the nozzle group, and the paper feed error is described. However, when the pitch of the nozzle is larger than the whole or smaller, the black stripe and the white stripe are respectively similarly applied. Will occur.

  Even if the paper feed error is zero when averaged over the entire recording medium, if the total paper feed amount of two times is more or less than 8 pixels, the same phenomenon as described above will occur. Occur. The paper feed amount varies depending on the error such as the outer diameter of the paper feed roller, the printing environment, and the type and condition of the recording medium such as paper. Have difficulty.

  As described above, splice lines are also generated in the multi-pass recording method. In particular, increasing the number of multi-pass divisions is effective in mitigating splice lines. This is because when the number of multi-pass divisions is increased, the number of dots printed in one scan is reduced, so that even if a streak is generated due to a paper feed error or the like, the density of the streak itself is reduced. In addition, the human eye has a characteristic that the sensitivity varies depending on the spatial frequency, and even with the same dark stripe, it may be noticeable or not noticeable depending on the interval of the stripe.

  This characteristic is shown in FIG. The vertical axis represents the intensity of sensitivity, and the horizontal axis represents the spatial frequency (cycles / mm). As can be seen, the highest sensitivity is in the vicinity of 1.1 cycles / mm, in other words, the 0.9 mm wide streak is the most noticeable. In the case of a head in which 80 nozzles are arranged with a nozzle pitch of 600 dpi, the generation cycle of streaks when performing multipass printing is as follows. When 2-pass printing and 10-pass printing are compared, the paper feed is 40 nozzles when 2-pass printing is performed, and the streak generation period is 1.69 mm (25.4 mm / 600 dpi x 40 pixels) for the 40 nozzle width. It becomes. That is, the spatial frequency is 0.59 cycles / mm. On the other hand, if printing is performed in 10 passes, the paper feed is 8 nozzles, and the streak generation period is 0.338 mm (25.4 mm / 600 dpi × 8 pixels) for the width of 8 nozzles. Is 3.0cycles / mm. In this case, as is apparent from FIG. 14, it can be seen that the streak cycle generated during 10-pass printing is less noticeable than the streak cycle generated during 2-pass printing.

  However, when the number of divisions is increased, there is a problem in that the print area that is completed for each scan is reduced, and the time for printing the entire image is increased. For example, if the number of divisions is increased and 2-pass printing is changed to 10-pass printing, it will take five times as long if considered simply.

Japanese Patent Publication No.59-31949 JP-A-6-143618

  An object of the present invention is to provide a recording apparatus and a recording method capable of solving the problem of splicing and achieving high image quality without lowering the throughput while taking advantage of the features of multipass printing described above. .

Therefore, in the present invention, there is provided a recording apparatus for recording on a recording medium using a recording head having a recording element array in which a plurality of recording elements are arranged, and scanning the recording head in the scanning direction with respect to the recording medium. The number of recording elements belonging to the recording element array and having a width smaller than the width of the recording element array in a transport direction different from the scanning direction between the scanning means and the scanning of the recording head In each scan of the recording head, the recording allowable ratio of the recording elements at both ends of the recording element array is equal to the both ends in each scan of the recording head by a width in which a number of recording elements not a divisor is arranged. and a recording control means for recording on said recording medium in accordance with the mask pattern defined lower than the print permitting ratios of the recording elements other than the recording element parts, said recording control means, the transport direction Recording on each of the unit areas on the recording medium having a width smaller than the width of the recording element array is completed by two or more predetermined scans of the recording head or one more scan than the predetermined times. Features.

In another embodiment of the present invention, there is provided a recording apparatus that performs recording on a recording medium using a recording head having a recording element array in which n recording elements are arranged at a predetermined pitch p. Scanning means for scanning the recording head in the scanning direction, and m (m is an integer smaller than n and not a divisor of n) in a transport direction different from the scanning direction between scanning of the recording head ) X at the end of the recording element array in each scanning of the recording head and the conveying means for conveying the recording medium by an amount of xp (s is the remainder when n is divided by m) number of printing elements and the other of the s of the recording elements at the ends print permitting ratios other than the recording elements in the one and the other ends (n-2s) lower than the print permitting ratio of number of recording elements the SL in accordance with the mask pattern defined Recording control means for recording on a medium, wherein the recording control means performs recording on each of the unit areas on the recording medium having a width of s × p in the transport direction by k times of the recording head or It is characterized by being completed by scanning (k + 1) times (k is a quotient obtained by dividing n by m and is an integer of 2 or more).

According to another aspect of the present invention, there is provided a recording method for performing recording on a recording medium using a recording head having a recording element array in which a plurality of recording elements are arranged, the recording head being connected to the recording medium. Between the scanning step of scanning in the scanning direction and the scanning of the recording head, the width is smaller than the width of the recording element array and belongs to the recording element array in a transport direction different from the scanning direction. In the transport process for transporting the recording medium by a width in which a number of recording elements that are not divisors of the number of recording elements are arranged, and in each scan of the recording head, the recording allowance of the recording elements at both ends of the recording element array and a recording step ratio for recording on the recording medium in accordance with the mask pattern defined lower than the print permitting ratios of the recording elements other than the recording element of said end portions, said recording step, the transport direction Recording on each of the unit areas on the recording medium having a width smaller than the width of the recording element array is completed by two or more predetermined scans of the recording head or one more scan than the predetermined times. Features.

According to another aspect of the present invention, there is provided a recording method for recording on a recording medium using a recording head having a recording element array in which n recording elements are arranged at a predetermined pitch p. M (m is an integer smaller than n and not a divisor of n) between a scanning step of scanning the recording head in the scanning direction and a transport direction different from the scanning direction between scanning of the recording head ) S at one end of the recording element array in the transporting process for transporting the recording medium by the amount of xp and each scan of the recording head (s is the remainder when n is divided by m) number of printing elements and the other of the s of the recording elements at the ends print permitting ratios other than the recording elements in the one and the other ends (n-2s) lower than the print permitting ratio of number of recording elements the SL in accordance with the mask pattern defined A recording step of recording on a medium, wherein in the recording step, recording is performed for each of the unit areas on the recording medium having a width of s × p in the transport direction, or k times (k + 1) of the recording head. ) Times (k is a quotient obtained by dividing n by m and is an integer of 2 or more).

According to the above configuration, a number of printing elements having a width smaller than the width of the printing element row and not a divisor of the number of printing elements belonging to the printing element row are arranged between the scans of the printing head. The recording medium is conveyed by the width of the recording element, and the recording ratio of the recording elements at the end of the recording element array is lower than the recording ratio of the recording elements other than the recording elements at the end in each scanning of the recording head. Recording is performed according to the determined mask pattern . Thereby, it becomes possible to make a connecting stripe inconspicuous.

  As a result, it is possible to make the streak inconspicuous while taking advantage of the characteristics of multi-pass recording without a significant decrease in throughput, and to achieve high image quality.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic perspective view showing an example of an ink jet recording apparatus to which the present invention can be applied. The recording medium 106 inserted in the paper feeding position of the recording apparatus 100 is conveyed to a recordable area by the recording head unit 103 by a feed roller 109. A platen 108 is provided below the recording medium in the recordable area. The carriage 101 is slidably engaged with the two guide shafts of the guide shaft a104 and the guide shaft b105, and is provided so as to be movable in the direction along them. The recording area can be reciprocally scanned. Mounted on the carriage 101 is a recording head unit 103 that includes a plurality of recording heads that eject inks of different colors and an ink tank that supplies ink to each recording head. The inks of a plurality of colors provided in the ink jet recording apparatus of this example are four colors of black (Bk), cyan (C), magenta (M), and yellow (Y) as described later with reference to FIG.

  On the left side of the area where the carriage can move, a recovery system unit 110 is provided below the movement area, and is used for discharge recovery processing such as capping the discharge port of the recording head during non-recording. This left end is called the home position of the recording head.

  Reference numeral 107 denotes a switch unit and a display element unit. The switch unit is used when turning on / off the power of the recording apparatus or setting various recording modes, and the display element unit functions to display various states of the recording apparatus. .

  FIG. 2 is a perspective view showing a schematic configuration of the recording head unit 103. The carriage 101 is mounted with a recording head 102 that ejects Bk, C, M, and Y inks, and a Bk tank 20K, a C tank 20C, an M tank 20M, and a Y tank 20Y. Each tank is connected to the recording head via a connection portion with the recording head, and supplies ink to the corresponding recording head. These recording heads and ink tanks are provided so that they can be attached and detached independently.

  The four color ink tanks may have an integrated structure, or the tanks of inks of colors other than black may have an integrated structure. Furthermore, in order to use inks of different colors for similar color inks in order to improve image quality, these recording heads and ink tanks may be further provided.

  FIG. 3 is a block diagram mainly showing a control configuration in the ink jet recording apparatus of the present embodiment.

  Character and image data to be recorded (hereinafter referred to as “image data”) sent from the host computer is temporarily stored in the reception buffer 301 of the recording apparatus. Further, data for confirming whether or not the data is correctly transferred and data for informing the operation state of the recording apparatus are returned from the recording apparatus to the host computer. The data stored in the reception buffer 301 is transferred to the RAM (random access memory) of the memory unit 303 under the management of the control unit 302 having the CPU, and is temporarily stored.

  A mechanical control unit 304 controls driving of a mechanical unit 305 such as a carriage motor or a line feed motor in response to a command from the control unit 302. The sensor / SW control unit 306 sends a signal from the sensor / SW unit 307 including various sensors and SW (switch) to the control unit 302. The display element control unit 308 controls the display element unit 309 composed of LEDs, liquid crystal display elements, and the like of the display panel group according to commands from the control unit 302. The recording head control unit 310 controls driving for ejecting ink in the recording head 102 according to a command from the control unit 302. Also, temperature information indicating the state of the recording head 102 is detected and transmitted to the control unit 302.

  A recording method according to an embodiment of the present invention performed by the ink jet recording apparatus described above will be described below.

(Embodiment 1)
In the first embodiment of the present invention, the nozzles of the recording head are divided into three nozzle groups, the print duty of the area printed by the nozzle groups at both ends in each scan is reduced, and the paper feed amount is reduced. A description will be given of a method for reducing the connecting stripe particularly by setting the amount corresponding to the number of nozzles that is not a divisor of the number of nozzles.

  FIG. 4 is a diagram illustrating a printing process using a thinning mask in the present embodiment.

  FIG. 4A is a diagram schematically showing a recording head 102 having ten nozzles 1021 and a mask M11 corresponding to the head. The mask M11 has a size corresponding to 10 pixels in the vertical direction and 4 pixels in the horizontal direction corresponding to the image data expressed in units of pixels, and a portion indicated by gray in the drawing is a portion for validating the image data. The ten nozzles 1021 are divided into three nozzle groups (nozzle groups a1, b1, and c1), and the corresponding mask M11 is divided into three regions as shown in the drawing. In the areas corresponding to the two nozzles corresponding to the nozzle groups a1 and c1 at both ends, the data of two pixels is valid for the eight pixels of the image data. This is called 1/4 duty or 25% duty. In the central 6 nozzle area corresponding to the nozzle group b1, 12 pixel data is valid for 24 pixels of image data, and this is called 1/2 duty or 50% duty. In each scan, the same mask always corresponds to the same nozzle as shown in FIG. Of course, the mask is configured so that, for each region, portions where data is valid in two or three scans complement each other as shown below. The specific configuration of the mask is configured by mask data as is well known, and the portion where the image data is valid is, for example, “1” as the mask data used for the logical product operation with the image data. It is a part having some data.

  FIG. 4B is a diagram showing a process of completing recording by the recording method of this embodiment using the recording head of FIG. 4A and the mask M11. In the illustrated example, it is assumed that the finally recorded image is a so-called solid rectangle that prints all pixels of horizontal 4 dots and vertical 16 dots or more. The paper feed amount is 4 nozzle widths (in this specification, this “nozzle width” represents the nozzle pitch), and the total number of nozzles used in this head is 10 nozzles. The amount is a nozzle width that is not a divisor of the total number of nozzles used. In addition, for the sake of explanation, the recorded area is divided into two vertical pixels to be area 11 to area 18.

  First, in order to complete the region 11, ½ duty is printed in each of the first scan and the second scan, and printing is completed in two scans. This is so-called two-pass printing. The area 12 is three-pass printing that prints at 1/4 duty in the first scan, 1/2 duty in the second scan, 1/4 duty in the third scan, and completes printing in a total of three scans. Similarly, in area 13, ½ duty is printed for each of the second and third scans for two-pass printing, and in area 14, printing is performed for the second, third, and fourth scans for three-pass printing, area 15 Are printed in the third scan and the fourth scan, and completed in two passes.

  As can be seen from FIG. 4B, in the recording method of this example, the end of each area printed in one scan is not adjacent to the end of the area printed in another scan. That is, in the conventional multi-pass printing method, for example, as shown in FIG. 13, in the case of two-pass printing, the lower end portion of the area printed in the first scan is adjacent to the upper end portion of the area printed in the third scan. Therefore, even if there is a slight paper feed error, the end portions are separated from each other (white stripes) or overlapped (black stripes) due to the error, and stitching tends to occur. On the other hand, in the method of this embodiment, since the end portions of the respective regions are not adjacent to each other, even if there is an error in paper feeding, the phenomenon of separation or overlap of the end portions does not occur, and streaks themselves are generated. Pressed.

  Also, because the printing duty at the edge of each area is low, the printing area between scans may be shifted due to paper feed errors, or even if the density of each area differs due to the printing time difference between each scan. Since the density is printed lightly, the influence of the error is less likely to appear as density unevenness such as joint lines. Furthermore, in conventional multi-pass printing, streaks occur in the paper feed amount cycle. In this example, the paper feed amount is equivalent to four nozzle widths, but printing that causes splices and the like occurs. As a result of preventing the ends from adjoining each other, the period of the end of the region becomes the width of two nozzles, and even if the splicing occurs, the generation period can be made shorter than the paper feed amount. The streak can be made inconspicuous without causing a decrease.

  In the above example, an example in which printing is completed in two passes and three passes with a paper feed of about half the width of all nozzles has been shown. However, further image quality increases the number of multi-pass passes. Can be achieved. FIG. 5 is a diagram showing an example of a mask when the number of passes is further increased. As in the above example, the mask M12 corresponds to a print head having 10 nozzles, and has a size corresponding to 10 pixels in the vertical direction and 6 pixels in the horizontal direction. It is a part to do. The mask M12 is divided into three areas as in the above example, and in the area of 1 nozzle width above and below, if the data of 1 pixel is valid for 6 pixels, the print ratio is 1/6 duty, and the center 8 The area for the nozzle width is 1/3 duty which makes data of 16 pixels effective for 48 pixels. When the paper feed amount is set to a 3-nozzle width using this mask, the recording of each area is completed by three or four scans.

  Of course, the shape and size of the mask are not limited to the above examples. Making a mask of a larger size and imparting randomness to the effective portion of the mask are effective for improving the image quality. In any case, a plurality of nozzles of the recording head are set as nozzle groups for each predetermined number of adjacent nozzles, and the duty printed by each nozzle group is made different. In particular, the recording duty of the nozzle group at the end that forms the printing boundary portion is set. The effect of the present embodiment can be obtained by reducing the paper feed amount to an amount corresponding to a number that is not a divisor of the number of print nozzles. That is, the edges of the print area, which is the main cause of the connecting lines, are prevented from being adjacent to each other, the connecting lines are less likely to occur, and even if the connecting lines are generated, the density of the connected areas is reduced. The period of is shortened. As a result, streaks are less noticeable, and high-quality recording can be realized without a significant decrease in throughput.

(Embodiment 2)
In the first embodiment described above, the plurality of nozzles of the recording head is divided into several nozzle groups, the recording duty of the nozzle group at the end is reduced, and the paper feed amount is a divisor of the total number of used nozzles of the recording head. The width corresponding to a different number of nozzle widths was used to reduce the occurrence or manifestation of splice lines. However, as described above, it is possible to reduce the occurrence of the connecting stripe particularly by simply reducing the recording duty for the end nozzle group, and this embodiment shows this example.

  FIG. 6 is a diagram for explaining the process of multi-pass printing using a thinning mask in this embodiment.

  FIG. 6A is a diagram schematically showing a recording head having nine nozzles and a mask M21 used when generating ejection data of the head. The mask M21 has a size corresponding to the vertical 9 pixels and horizontal 4 pixels of the image data, and the portion indicated by gray in the figure is a portion that makes the image data effective. The nine nozzles are divided into three nozzle groups (nozzle groups a2, b2, c2), while the mask M21 corresponding to each nozzle is also divided into three regions as shown in the figure. In the area corresponding to the nozzle group a2 and the nozzle group c2, the data of 3 images is valid for 12 pixels, and the printing ratio is 1/4 duty. The area for three nozzles in the center corresponding to the nozzle group b2 makes data of 6 pixels effective for 12 pixels, and the printing ratio becomes 1/2 duty. As in the first embodiment, the same mask always corresponds to the same nozzle in each scan. Of course, the mask pattern of the nozzle group a2, the mask pattern of the nozzle group b2, and the mask pattern of the nozzle group c2 are complementary to each other.

  FIG. 6B is a diagram illustrating a process of completing recording when recording is performed using the recording head and the mask illustrated in FIG. In this embodiment, the paper feed amount is 3 nozzle widths. As a result, unlike the above-described embodiment, the end portions of the print areas of each scan are adjacent to each other. For example, in the example shown in FIG. 6B, the lower end of the print area of the first scan and the upper end of the print area of the fourth scan are adjacent. As a result, it is not possible to suppress the occurrence of splicing lines, and the effect of shortening the streak period cannot be obtained, but as shown below, by reducing the recording duty of the end nozzle group, Even if the connecting stripes are generated, the concentration can be reduced and the connection can be made inconspicuous.

  In other words, if the recorded area is divided by 3 pixels in the vertical direction to be the areas 21 to 24, first, in order to complete the area 21, ¼ duty printing is performed in the first scan, and 1 in the second scan. Print 2/2 duty, print the remaining 1/4 duty in the third scan, and complete the print in 3 scans. The area 22 is printed by 1/4 duty in the second scan, 1/2 duty in the third scan, and 1/4 duty in the fourth scan, thereby completing the recording. Thereafter, all the areas are similarly completed in three scans.

  According to such a recording method of the present embodiment, there is a possibility that the upper end portion and the lower end portion of the print area of each scan may be connected adjacent to the lower end portion and the upper end portion of the print area of other scans. However, since the duty per scan of the nozzle group that records the print area including the upper and lower ends is set to be low, the density can be reduced even if the connecting stripe occurs. It is possible to make the connection lines inconspicuous.

(Embodiment 3)
In the first and second embodiments, an example is shown in which one type of thinning mask is set, the same thinning mask is used every scan, and the paper feed amount is constant each time. In this example, an example in which the mask and the paper feed amount are different for each scan is shown.

  FIG. 7 is a diagram for explaining a printing process using a thinning mask in this embodiment.

  FIG. 7A is a diagram schematically showing a recording head having 10 nozzles and two types of recording masks M31 and M32 corresponding to image data supplied to the head, as in the first embodiment. The masks M31 and M32 have a size corresponding to 10 pixels in the vertical direction and 4 pixels in the horizontal direction, and a portion indicated by gray in the figure is a portion that makes the image data effective. The ten nozzles are divided into three nozzle groups (nozzle groups a3, b3, and c3), and the corresponding masks M31 and M32 are divided into three regions as shown in the figure. In the upper and lower two nozzle width areas corresponding to the nozzle group a3 and the nozzle group c3, the data of 2 pixels is valid for 8 pixels, and the duty is 1/4 duty. In the region corresponding to the center 6 nozzle width corresponding to the nozzle group b3, the data of 12 pixels is valid for 24 pixels, and the duty is 1/2 duty.

  FIG. 7B is a diagram illustrating a process of completing recording when recording is performed using the recording head and the masks M31 and M32 illustrated in FIG. In FIG. 7B, the mask M31 is used for odd-numbered scans and the mask M32 is used for even-numbered scans. The paper feed amount is 2 nozzle widths after odd scan printing and 6 nozzle widths after even scan printing. In the figure, if the recorded area is divided into two vertical pixels and divided into areas 31 to 38, first, in order to complete the areas 31 and 32, 1 is required for each of the first scan and the second scan. / 2-duty printing that prints every 2 duty and completes printing in two scans. The area 33 is three-pass printing in which 1/4 duty is printed in the first scan, 1/2 duty is printed in the second scan, 1/4 duty is printed in the third scan, and printing is completed in a total of three scans. Similarly, in the area 34, printing is performed by the second scan, the third scan, and the fourth scan to perform 3-pass printing. In the area 35 and the area 36, printing is performed by the third scan and the fourth scan, and each recording is performed by the 2-pass printing. Completed. Of course, the masks M31 and M32 are complementary patterns so that there is no omission of image data for each region in the recording by the above-mentioned multiple scans.

  The method according to the present embodiment is effective in making the connection streaks inconspicuous because the recording duty of the nozzle group corresponding to the end of the print area is lowered. Furthermore, by changing the paper feed amount for each scan, the period of streaking is shortened, and the connecting lines are less noticeable.

  In this example, the mask and paper feed amount are set for each scan. However, only the mask may be set for each scan, and the paper feed amount may be set to the same amount for each scan. Also, only one type of mask may be used. The paper feed amount may be set for each scan. In any case, it is only necessary to set a mask and paper feed amount that can finally complement printing and reduce stitching.

(Embodiment 4)
In the above-described first, second, and third embodiments, the recording method has been described in which the ejection duty is changed between the central portion and the end portion of the nozzle group of the recording head to make the joint inconspicuous. On the other hand, in the present embodiment, a recording method for making the connecting stripes less visible by generating the connecting stripes with a fine cycle that is difficult to be recognized by human eyes will be described by focusing attention on the generation cycle of the connecting stripes.

  FIG. 8 is a diagram illustrating a printing process using a thinning mask in the present embodiment.

  FIG. 8A is a diagram schematically showing a recording head having 10 nozzles and a recording mask M41 used when creating ejection data of this head, as in the first embodiment. The mask M41 has a size corresponding to 10 pixels in the vertical direction and 4 pixels in the horizontal direction, and the portion indicated by gray in the figure is a portion that makes the image data effective. The recording nozzle is divided into three regions as shown in the figure. The upper four nozzles are set as a nozzle group a4, and the mask for the nozzle group a4 is a staggered pattern mask, which is 1/2 duty in which data of 8 pixels is valid for 16 pixels. The lower four nozzles are set as a nozzle group c4, and the mask for the nozzle group c4 is a mask with an inverted staggered pattern, and the duty is 1/2 duty. Two nozzles in the center are set as a nozzle group b4, and the mask corresponding to the nozzle group is 0% duty, that is, printing is not performed by these nozzle groups. In each scan, the same mask always corresponds to the same nozzle.

  FIG. 8B is a diagram illustrating a process of completing recording when recording is performed using the recording head and the mask M41 illustrated in FIG. As in the above-described embodiments, it is assumed that the finally recorded image is a 100% duty (solid) rectangle of 4 dots horizontally and 16 dots vertically. The paper feed amount is 4 nozzle widths. For the sake of explanation, the recorded area is divided into two vertical pixel widths to be areas 41 to 48.

  First, in order to complete the area 41, ½ duty is printed in each of the first scan and the second scan, and printing is completed in two scans, resulting in two-pass printing. In order to complete the area 42, printing is performed for each scan 1/2 duty in the first scan and the third scan, and the scan is performed three times. Of these, the printing is completed in two scans. Similarly, two-pass printing is performed. Similarly, the region 43, the region 44, the region 45... And all the regions are completed in two passes.

  A position where a connecting line may occur on the left side of FIG. 8B is indicated by an arrow. In the figure, the ends of the nozzle group a4 and the nozzle group c4 are adjacent to each other at the joint of the scan, such as the first scan and the second scan, the second scan and the third scan, the third scan and the fourth scan, and so on. The connecting lines are generated as in the conventional case. In this case, the connecting line cycle is the same as the paper feed amount (4 nozzle width in this example). However, in the case of the present embodiment, since the nozzles used in the head are limited (because the nozzle group b4 is not used), the connection lines generated by the nozzle group a4 (the position of the double arrow in the figure), and the nozzle group The connecting line (indicated by the arrow in the figure) generated by c4 is shifted by the width of two nozzles. As a result, the connecting lines of the recorded images look like a cycle of 2 nozzles, the connecting lines become fine, and the lines are not noticeable.

  Of course, the thinning mask pattern is not limited to the above example. Any pattern can be used as long as it is short enough to create a stripe with a non-obtrusive period. The division of the nozzle group is not limited to three divisions and may be more or less. For example, as shown in FIG. 9, the nozzle group is divided into five regions (nozzle group a5 to nozzle group e5), and the nozzle group b5 and nozzle group d5 do not validate the image data (the nozzle group is not used). As for the mask, a 1/2 duty mask may be set for the nozzle group a5, the nozzle group c5, and the nozzle e5. In this case, when the paper feed amount is set to the width of 4 nozzles, the connecting stripe has a cycle of 2 nozzle widths due to a shift of the portion where the paper feed may occur.

  Furthermore, imparting randomness to the mask pattern is effective in making mechanical noise such as carriage shift and head noise such as ink ejection direction inconspicuous. Furthermore, in this example, one type of mask is set and the paper feed amount is fixed every time. However, even if a plurality of types of masks are set and changed for each scan, or irregular paper feed is performed. Good. In particular, in the case of this embodiment, since there are nozzles that are not used for printing, it is possible to disperse nozzles that do not perform printing by preparing multiple types of masks and changing them for each scan. This is effective in extending the life of the battery. Furthermore, it is also effective for extending the life of the head to prepare a plurality of types of masks having different nozzle positions that are not used for printing and to change them for each page. Of course, whatever pattern is used, the finally printed image must be complemented without missing data.

  As described above, by setting the nozzle groups other than the end portions among the nozzles of the recording head so as not to be used for printing, it is possible to disperse the locations where the connecting lines are generated and to shorten the period. As a result, it is possible to improve the image quality by making the connection lines inconspicuous.

  In each of the embodiments described above, an example using an ink jet recording head has been described. However, the application of the present invention is not limited to such a method, and for example, the recording head may be used for a thermal transfer method, a thermal method, or the like. Of course you can.

(Other)
The present invention includes means (for example, an electrothermal converter, a laser beam, etc.) that generates thermal energy as energy used for ejecting ink, particularly in the ink jet recording system, and the ink is generated by the thermal energy. In the recording head and the recording apparatus of the type that causes the state change, excellent effects are brought about. This is because such a system can achieve high recording density and high definition.

  As for the typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 are preferable. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, the thermal energy is generated in the electrothermal transducer, and the recording head This is effective because film boiling occurs on the heat acting surface of the liquid and, as a result, bubbles in the liquid (ink) corresponding one-to-one with the drive signal can be formed. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable that the drive signal has a pulse shape, since the bubble growth and contraction is performed immediately and appropriately, and thus it is possible to achieve discharge of a liquid (ink) having particularly excellent responsiveness. As this pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employing the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface.

  As the configuration of the recording head, in addition to the combination configuration (straight liquid channel or right angle liquid channel) of the discharge port, the liquid channel, and the electrothermal transducer as disclosed in each of the above-mentioned specifications, the heat acting part The configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose the configuration in which the lens is disposed in the bending region, are also included in the present invention. In addition, for a plurality of electrothermal transducers, Japanese Patent Application Laid-Open No. Sho 59-123670 that discloses a configuration in which a common slit is used as a discharge portion of the electrothermal transducer or an aperture that absorbs pressure waves of thermal energy is provided. The effect of the present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 59-138461 which discloses a configuration corresponding to the discharge unit. That is, whatever the form of the recording head is, according to the present invention, recording can be performed reliably and efficiently.

  In addition, even the serial type as shown in the above example can be connected to the main body of the recording head or attached to the main body of the device so that electrical connection with the main body of the device and ink supply from the main body are possible. The present invention is also effective when a replaceable chip type recording head or a cartridge type recording head in which an ink tank is integrally provided in the recording head itself is used.

  In addition, it is preferable to add a recording head ejection recovery means, a preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention, since the effects of the present invention can be further stabilized. Specifically, heating is performed using a capping unit, a cleaning unit, a pressurizing or suction unit, an electrothermal transducer, a heating element different from this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

  Also, regarding the type or number of recording heads to be mounted, for example, a plurality of recording heads are provided corresponding to a plurality of inks having different recording colors and densities, in addition to one provided corresponding to a single color ink. May be used. That is, for example, as a recording mode of the recording apparatus, not only a recording mode of only a mainstream color such as black, but also a recording head may be configured integrally or by a combination of a plurality of different colors, Alternatively, the present invention is extremely effective for an apparatus having at least one of full-color recording modes by color mixing.

  In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, ink that is solidified at room temperature or lower and that softens or liquefies at room temperature may be used. In the ink jet method, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that it is in the stable discharge range. A liquid material may be used. In addition, it is solidified and heated in an untreated state in order to actively prevent the temperature rise caused by thermal energy from being used as the energy for changing the state of the ink from the solid state to the liquid state, or to prevent the ink from evaporating. You may use the ink which liquefies by. In any case, by applying thermal energy according to the application of thermal energy according to the recording signal, the ink is liquefied and liquid ink is ejected, or when it reaches the recording medium, it already starts to solidify. The present invention can also be applied to the case of using ink having the property of liquefying for the first time. The ink in such a case is in a state of being held as a liquid or a solid in a porous sheet recess or through-hole as described in JP-A-54-56847 or JP-A-60-71260. Alternatively, the electrothermal converter may be opposed to the electrothermal converter. In the present invention, the most effective one for each of the above-described inks is to execute the above-described film boiling method.

  In addition, the ink jet recording apparatus according to the present invention may be used as an image output terminal of an information processing device such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. The thing etc. may be sufficient.

1 is a perspective view illustrating an example of a recording apparatus to which the present invention can be applied. FIG. 2 is a perspective view of a recording head unit used in the recording apparatus. It is a block diagram which mainly shows the control structure of the said recording device. (A) And (b) is a figure explaining the mask used for the multipass printing which concerns on the 1st Embodiment of this invention, and the process of completion of printing. It is a figure explaining the other example of the mask which can be used in the said 1st Embodiment. (A) And (b) is a figure explaining the process used to complete the mask and printing used for multipass printing according to the second embodiment of the present invention. (A) And (b) is a figure explaining the process used to complete the mask and printing used for multipass printing according to the third embodiment of the present invention. (A) And (b) is a figure explaining the process used to complete the mask and printing used for multipass printing according to the fourth embodiment of the present invention. It is a figure explaining the other example of the mask which can be used in the said 4th Embodiment. (A), (b) and (c) are diagrams for explaining a recording state with uneven density. (A), (b), and (c) are figures explaining multipass printing (divided recording). (A), (b) and (c) is a figure explaining the printing process by multipass printing. (A) And (b) is a figure explaining the state which a streak generate | occur | produces by the mismatch of paper feed and printing pitch in the case of multipass printing. It is a figure explaining the spatial frequency characteristic of human eyes.

Explanation of symbols

20K, 20C, 20M, 20Y Ink tank 101 Carriage 102 Recording head 302 Control unit 303 Memory unit 304 Mechanical control unit 305 Mechanical unit 306 Sensor / SW control unit 307 Sensor / SW unit 308 Display element control unit 309 Display element unit 310 Head control Part 330 Output buffer

Claims (8)

A recording apparatus for recording on a recording medium using a recording head having a recording element array in which a plurality of recording elements are arranged,
Scanning means for scanning the recording head in the scanning direction with respect to the recording medium;
A number smaller than the width of the recording element array and not a divisor of the number of recording elements belonging to the recording element array in a transport direction different from the scanning direction between scanning of the recording head. Conveying means for conveying the recording medium by the width in which the recording elements are arranged ;
At each scanning of the recording head, the recording medium in accordance with the mask pattern print permitting ratios of the recording element at both ends is defined lower than the print permitting ratios of the recording elements other than the recording element of the both end portions in the recording element array Recording control means for performing recording,
The recording control unit performs recording on each of the unit areas on the recording medium having a width smaller than the width of the recording element array in the transport direction by scanning the recording head two or more predetermined times or the predetermined times. The recording apparatus is also completed by one more scan.   The recording apparatus according to claim 1, wherein the two or more predetermined times are two times.   The recording apparatus according to claim 1, wherein the two or more predetermined times are three times. A recording apparatus for recording on a recording medium using a recording head having a recording element array in which n recording elements are arranged at a predetermined pitch p,
Scanning means for scanning the recording head in the scanning direction with respect to the recording medium;
Between the scans of the recording head, the recording medium is conveyed by an amount of m (m is an integer smaller than n and not a divisor of n) × p in a conveyance direction different from the scanning direction. Conveying means;
In each scan of the recording head, s (s is the remainder when n is divided by m) recording elements at one end of the recording element array and s recording elements at the other end. recording control means for recording allowable ratio for recording on the recording medium in accordance with the mask pattern defined lower than the print permitting ratios other than the recording element of the (n-2s) pieces of the recording elements in said one and the other end and the With
The recording control means performs recording on each of the unit areas on the recording medium having a width of s × p in the transport direction, k times or (k + 1) times of the recording head (k is n in m And a quotient obtained by dividing by an integer greater than or equal to 2).   The recording apparatus according to claim 4, wherein the k is two.   The recording apparatus according to claim 4, wherein the k is three. A recording method for recording on a recording medium using a recording head having a recording element array in which a plurality of recording elements are arranged,
A scanning step of scanning the recording head with respect to the recording medium in a scanning direction;
A number smaller than the width of the recording element array and not a divisor of the number of recording elements belonging to the recording element array in a transport direction different from the scanning direction between scanning of the recording head. A conveying step of conveying the recording medium by the width in which the recording elements are arranged ;
At each scanning of the recording head, the recording medium in accordance with the mask pattern print permitting ratios of the recording element at both ends is defined lower than the print permitting ratios of the recording elements other than the recording element of the both end portions in the recording element array A recording process for recording,
In the recording step, recording on each of the unit areas on the recording medium having a width smaller than the width of the recording element array in the transport direction is performed two or more predetermined scans of the recording head or more than the predetermined times. A recording method, wherein the printing is completed by one scan. A recording method for recording on a recording medium using a recording head having a recording element array in which n recording elements are arranged at a predetermined pitch p,
A scanning step of scanning the recording head with respect to the recording medium in a scanning direction;
Between the scans of the recording head, the recording medium is conveyed by an amount of m (m is an integer smaller than n and not a divisor of n) × p in a conveyance direction different from the scanning direction. Conveying process;
In each scan of the recording head, s (s is the remainder when n is divided by m) recording elements at one end of the recording element array and s recording elements at the other end. and a recording step of recording allowable ratio for recording on the recording medium in accordance with the mask pattern defined lower than the print permitting ratios of the one and the other than the recording element at the end of the (n-2s) pieces of recording elements Prepared,
In the recording step, recording on each of the unit areas on the recording medium having a width of s × p in the transport direction is performed k times or (k + 1) times (k is n divided by m) of the recording head. And a quotient obtained by scanning with an integer of 2 or more).

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