JP2009160876A - Image recording method and image recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the quality of an image by suppressing generation of streaky irregularities while lowering the visibility of an overlap region in the image recorded. <P>SOLUTION: The printer is equipped with a plurality of nozzle units. Drawing of dots is carried out by the plurality of nozzle units to a plurality of strip-shaped regions extended in a scanning direction on a printing paper, respectively. In the overlap region 711 where two strip-shaped regions adjacent to each other in a width direction perpendicular to the scanning direction partially overlap with each other, one of a first drawing action by one nozzle unit to one strip-shaped region and a second drawing action by other nozzle units to the other strip-shaped region is assigned to each drawing position where the dot can be drawn. A density of the drawing positions assigned to the first drawing action decreases as the drawing position is farther from a non overlap region of the strip-shaped region corresponding to the first drawing action. Accordingly, generation of streaky irregularities can be suppressed while the visibility of the overlap region 711 is lowered in the printing image. Improvement of the quality of the printing image is thus attained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for recording an image on an object.

  Conventionally, a large number of ejection openings are arranged in a range corresponding to the width of the printing paper in the width direction perpendicular to the scanning direction, and printing is performed at high speed by one scanning (one pass) on the printing paper of the head unit. A type of printing device is known. In such a printing apparatus, in general, a plurality of nozzle units in which a plurality of discharge ports are arranged and formed at a predetermined pitch are arranged in the width direction, but the width between the discharge ports in two adjacent nozzle units. When the distance in the direction is larger or smaller than the pitch of the discharge ports in the nozzle unit due to a mounting error or a positional deviation due to vibration during printing operation, the image printed on the printing paper extends in the scanning direction. A stripe-like density unevenness (hereinafter, simply referred to as “straight spot”) occurs.

  Therefore, in Patent Document 1, the width between the discharge port (nozzle) of one nozzle unit and the discharge port of the other nozzle unit while overlapping the ends of two adjacent nozzle units (short heads) in the scanning direction. The distance in the direction is set to be smaller than the pitch of the discharge ports in the nozzle unit, and the overlapping drive area (connection area) on the recording medium through which the two nozzle units pass has a predetermined drive pattern. There is disclosed a technique for suppressing the occurrence of uneven stripes in an overlapping region by driving or stopping two nozzle units.

Further, in Patent Document 2, in two adjacent nozzle units (print heads), ejection ports (nozzles) positioned at the ends are arranged in the scanning direction so as to be on a line extending in the scanning direction on the printing paper. A method is disclosed in which the printing quality is improved while suppressing the occurrence of uneven stripes by drawing each dot alternately or randomly at the two ejection openings corresponding to the line.
JP 2002-144542 A Japanese Patent Laid-Open No. 2002-210942

  By the way, in the method of Patent Document 1, since the discharge ports are intentionally shifted in the width direction in two adjacent nozzle units, the edge (outline) of the image to be printed is temporarily positioned on the overlapping region. In such a case, the edge is rattled and the quality of the printed image is degraded.

  On the other hand, in an ink jet printing apparatus, there is a case where the density of an image printed on a printing paper is different due to a difference in ink discharge amount between two nozzle units. When the method is employed, the overlapping area has a density that is substantially intermediate between the densities corresponding to the two nozzle units. In this case, the overlap area is easily recognized in the print image, and the quality of the print image is deteriorated.

  In addition, in a printing apparatus having only one nozzle unit, even when printing an image by repeating scanning in the scanning direction of the nozzle unit and intermittent relative movement in the width direction, the printing is performed on the printing paper. Since stripes may occur between the area drawn during scanning and the area adjacent to this area and drawn during other scans, the areas drawn during these scans partially overlap each other. As described above, it is conceivable to perform printing by setting an overlapping area. In this case as well, it is possible to apply the method of the above-mentioned Patent Document 2, but the density of the image drawn by the discharge port near one end of the nozzle unit and the drawing by the discharge port near the other end. If the density of the printed image is different, the overlapping area is likely to be recognized in the printed image as described above.

  The present invention has been made in view of the above problems, and an object of the present invention is to improve the quality of an image by suppressing the occurrence of unevenness while reducing the visibility of an overlapping area in a recorded image.

  According to the first aspect of the present invention, a plurality of drawing mechanisms for drawing dots on an object, and positions on the object on which dots are drawn by the plurality of drawing mechanisms are at least predetermined with respect to the object. An image recording method for recording an image with an image recording apparatus including a scanning mechanism that moves relatively in a scanning direction, the image recording method extending in the scanning direction and arranged in a direction perpendicular to the scanning direction on the object. A plurality of band-like areas in which dots are respectively drawn by the plurality of drawing mechanisms are set, and each band-like area and a band-like area adjacent in a direction perpendicular to the scanning direction partially overlap, and the image recording A) generating drawing data for the plurality of drawing mechanisms from image data; and b) using the plurality of drawing mechanisms based on the drawing data. A first drawing mechanism for one of the two belt-like regions at each drawing position where dots can be drawn in an overlapping region where two adjacent belt-like regions overlap each other. One of the first drawing operation by the second drawing operation and the second drawing operation by the second drawing mechanism for the other band-like region is assigned, and the drawing data generated in the step a) generates the first drawing operation in the overlapping region. The density of the drawing positions assigned to one drawing operation decreases as the distance from the non-overlapping area of the one band-like area increases.

  The invention according to claim 2 is the image recording method according to claim 1, wherein each drawing mechanism has a plurality of dot output elements, and each drawing mechanism is in the scanning direction with respect to the object. By relatively moving once, dots are drawn in one band-like region.

  A third aspect of the present invention is the image recording method according to the second aspect, wherein each of the plurality of dot output elements has an ejection port that ejects a micro droplet of ink toward the object. .

  A fourth aspect of the present invention is the image recording method according to the second or third aspect, wherein the plurality of drawing mechanisms are provided on all the belt-like regions arranged in a direction perpendicular to the scanning direction on the object. Each corresponds.

  The invention according to claim 5 is the image recording method according to claim 1, wherein each of the plurality of drawing mechanisms has one dot output element, and in step b), the plurality of dot output elements The position on the object on which dots are drawn is moved in the scanning direction and in a direction perpendicular to the scanning direction.

  The invention according to claim 6 is a drawing mechanism for drawing dots on an object, and a position on the object on which dots are drawn by the drawing mechanism with respect to the object in a predetermined scanning direction and the scanning. An image recording method for recording an image with an image recording apparatus including a scanning mechanism that moves relatively in a direction perpendicular to the direction, the direction extending in the scanning direction on the object and perpendicular to the scanning direction A plurality of band-like areas are set in which dots are sequentially drawn by the drawing mechanism, and each band-like area and a band-like area adjacent in a direction perpendicular to the scanning direction partially overlap, and the image A recording method includes: a) generating drawing data for the drawing mechanism from image data; and b) sequentially writing the plurality of band-like regions by the drawing mechanism based on the drawing data. A step of drawing an image, and in the step b), the drawing mechanism having a plurality of dot output elements moves relative to the object once in the scanning direction to thereby form one band shape. The first drawing by the drawing mechanism for one of the two band-like areas is drawn at each drawing position where dots can be drawn in the overlapping area where two adjacent band-like areas overlap each other. One of the operation and the second drawing operation by the drawing mechanism for the other band-like region is assigned, and is assigned to the first drawing operation in the overlapping region by the drawing data generated in the step a) The density of the drawn drawing positions decreases as the distance from the non-overlapping area of the one band-like area increases.

  A seventh aspect of the present invention is the image recording method according to any one of the first to sixth aspects, wherein the drawing position assigned to the first drawing operation in the overlapping region where the two band-like regions overlap is provided. Matrix data to be shown is prepared in advance, and in the step a), the drawing data is generated using the matrix data.

  The invention according to claim 8 is the image recording method according to claim 7, wherein the drawing positions assigned to the first drawing operation are scattered while following the density distribution of the drawing positions.

  A ninth aspect of the present invention is the image recording method according to any one of the first to sixth aspects, wherein a drawing position assigned to the first drawing operation in the overlapping region where the two belt-like regions overlap is provided. These are determined by comparing sequentially generated random numbers with a threshold corresponding to the density of the drawing positions.

  A tenth aspect of the present invention is the image recording method according to any one of the first to ninth aspects, wherein the steps a) and b) are performed for each of a plurality of color components of the image. The positions of the overlapping regions of the plurality of color components in the direction perpendicular to the scanning direction are different.

  The invention according to claim 11 is an image recording apparatus for recording an image on an object, a holding unit for holding the object, a plurality of drawing mechanisms for drawing dots on the object, and the plurality A scanning mechanism that moves a position on the object on which dots are drawn by the drawing mechanism relative to the object in at least a predetermined scanning direction, and extends in the scanning direction on the object. In addition, a plurality of belt-like regions arranged in a direction perpendicular to the scanning direction and in which dots are drawn by the plurality of drawing mechanisms are set, and the belt-like regions adjacent to the belt-like regions in the direction perpendicular to the scanning direction are set. In the overlapping area where the area partially overlaps and two adjacent band-like areas overlap, the first drawing with respect to one of the two band-like areas is drawn at each drawing position where dots can be drawn. One of the first drawing operation by the mechanism and the second drawing operation by the second drawing mechanism with respect to the other band-like region is assigned, and the density of drawing positions assigned to the first drawing operation in the overlapping region is The distance decreases as the distance from the non-overlapping area of the one band-shaped area increases.

  The invention according to claim 12 is the image recording apparatus according to claim 11, wherein each drawing mechanism has a plurality of dot output elements, and each drawing mechanism is in the scanning direction with respect to the object. By relatively moving once, dots are drawn in one band-like region.

  A thirteenth aspect of the present invention is the image recording apparatus according to the twelfth aspect, wherein each of the plurality of dot output elements has a discharge port that discharges a fine droplet of ink toward the object. .

  The invention according to a fourteenth aspect is the image recording apparatus according to the twelfth or thirteenth aspect, wherein the plurality of drawing mechanisms are arranged on all the belt-like regions arranged in a direction perpendicular to the scanning direction on the object. Each corresponds.

  According to a fifteenth aspect of the present invention, in the image recording apparatus according to the eleventh aspect, each of the plurality of drawing mechanisms has one dot output element, and the plurality of band-shaped regions have dot dots. When drawing, the position on the object on which dots are drawn by the plurality of drawing mechanisms is moved in the scanning direction and in a direction perpendicular to the scanning direction.

  The invention according to claim 16 is an image recording apparatus that records an image on an object, and includes a holding unit that holds the object, a drawing mechanism that draws dots on the object, and the drawing mechanism. A scanning mechanism that moves a position on the object on which dots are drawn relative to the object in a predetermined scanning direction and a direction perpendicular to the scanning direction, and the scanning direction on the object A plurality of band-like areas that are arranged in a direction perpendicular to the scanning direction and in which dots are sequentially drawn by the drawing mechanism are set, and each band-like area is adjacent to each other in the direction perpendicular to the scanning direction. The drawing mechanism having a plurality of dot output elements moves relative to the object once in the scanning direction when drawing a dot on the plurality of strip-like regions. By doing so, the drawing of dots in one band-shaped area is performed, and in the overlapping area where two adjacent band-shaped areas overlap each other, the drawing position for one band-shaped area of the two band-shaped areas is set at each drawing position where dots can be drawn. One of the first drawing operation by the drawing mechanism and the second drawing operation by the drawing mechanism with respect to the other band-shaped region is assigned, and the density of drawing positions assigned to the first drawing operation in the overlapping region is The distance decreases as the distance from the non-overlapping area of the one band-shaped area increases.

  According to the present invention, it is possible to improve the quality of an image to be recorded while suppressing the occurrence of unevenness while reducing the visibility of an overlapping region.

  In the inventions of claims 2 and 12, an image can be recorded on an object in a short time. In the inventions of claims 3 and 13, the quality of an image printed by an ink jet method is improved. Can do.

  In the invention of claim 7, the drawing data can be easily generated. In the invention of claim 9, when the dots are drawn in one belt-like area, the period is set at the position of the dots drawn in the overlapping area. In the invention of claim 10, in the color image, the occurrence of a peculiar part in the image can be suppressed by shifting the overlapping area for each color component.

  FIG. 1 is a diagram showing a configuration of an ink jet printing apparatus 1 according to a first embodiment of the present invention. The printing apparatus 1 is an image recording apparatus that records an image on a printing paper 9. The printing apparatus 1 includes a main body 12 of the printing apparatus 1 and a computer 11 connected to the main body 12, and the main body 12 discharges a fine droplet of ink toward a printing paper 9 to be printed. A paper feed mechanism 29 that moves the printing paper 9 in the (+ Y) direction in FIG. 1 below the unit 20 and a main body control unit 13 that controls the discharge unit 20 and the paper feed mechanism 29 are provided.

  The paper feed mechanism 29 has two belt rollers 291 connected to a motor (not shown) and a belt 292 hung between the two belt rollers 291. The printing paper 9 is guided and held on a belt 292 that is a holding unit via a roller 293 provided above the (−Y) side belt roller 291, and passes below the discharge unit 20 together with the belt 292. Move to the (+ Y) side. In the following description of the printing apparatus 1 in FIG. 1, the relative movement direction (Y direction) of the ejection unit 20 with respect to the printing paper 9 is referred to as a scanning direction. In the paper feeding mechanism 29, a suction part is provided at a position facing the discharge part 20 inside the annular belt 292, and a minute suction hole is formed in the belt 292, whereby the printing paper 9 is sucked on the belt 292. It may be held by adsorption.

  The ejection unit 20 is provided with a head unit 21 having a plurality (four in this embodiment) of head units 23. The plurality of head portions 23 eject inks of C (cyan), M (magenta), Y (yellow), and K (black), respectively, and are arranged in the Y direction.

  FIG. 2 is a bottom view showing one head unit 23. In FIG. 2, the scanning direction (that is, the Y direction) of the printing paper 9 with respect to the ejection unit 20 is illustrated vertically. A plurality of nozzle units 251 (in FIG. 2, two nozzle units are denoted by reference numerals 251a and 251b) are perpendicular to the scanning direction and extend along the printing paper 9 (see FIG. 1). The X direction is the direction corresponding to the width of the printing paper 9 and is therefore arranged in a staggered manner in the printing apparatus 1 along the “width direction”. The discharge ports 241 are arranged at a constant pitch in the width direction. Further, in the two nozzle units 251 adjacent in the width direction, a plurality of discharge ports 241 in the vicinity of the end portions are arranged so as to overlap in the scanning direction. For example, in the nozzle units denoted by reference numerals 251a and 251b in FIG. 2, a plurality of (−X) side discharge ports 241a in the (+ X) side nozzle unit 251a and a (−X) side nozzle unit 251b ( The (X) side discharge ports 241b are (ideally) arranged at the same position in the width direction (that is, the two nozzle units 251 scan with an overlap amount that is an integral multiple of the pitch of the discharge ports 241). Overlapping directions). In FIG. 2, the number of pairs of discharge ports 241 arranged at the same position by two adjacent nozzle units 251 is three. In the following description, a combination of two discharge ports 241 arranged in the scanning direction by two adjacent nozzle units 251 is referred to as a discharge port pair 242.

  In the nozzle unit 251 that is a drawing mechanism, a piezoelectric element is provided for each discharge port 241, and by driving the piezoelectric element, a minute droplet of ink is applied to the printing paper 9 from the discharge port 241 that is a dot output element. In this way, dots are drawn on the printing paper 9. Actually, a large number of nozzle units 251 are arranged, and the plurality of discharge ports 241 included in the head unit 23 are arranged over the entire width of the printing area on the printing paper 9 in the width direction. The printing apparatus 1 can perform high-speed printing in one pass.

  Further, the ejection unit 20 of FIG. 1 includes a head moving mechanism 22 that moves the head unit 21 in the width direction. The head moving mechanism 22 is provided with an annular timing belt 222 that is elongated in the width direction. When the motor 221 rotates the timing belt 222, the head unit 21 moves smoothly in the width direction. When the printing apparatus 1 is not printing, the head moving mechanism 22 places the head unit 21 at a predetermined retracted position, and the plurality of discharge ports 241 of each head portion 23 of the head unit 21 are closed by a lid member at the retracted position. Further, it is possible to prevent the ink in the vicinity of the ejection port 241 from drying and clogging the ejection port 241.

  The main body control unit 13 generates, for each color component, a bitmap image indicating ON / OFF of dot drawing at each position on the printing paper 9 from an image to be printed (hereinafter referred to as “original image”). A generation unit 131 and a drawing data generation unit 132 that generates drawing data for a plurality of nozzle units 251 that eject ink of the color from a bitmap image of each color component are provided.

  Next, an operation in which the printing apparatus 1 performs printing (that is, records an image on the printing paper 9) will be described with reference to FIG. When printing is performed by the printing apparatus 1, first, color multi-gradation original image data is input from the computer 11 to the image generation unit 131, and halftoning processing (shading processing) is performed on the original image. ) To generate a bitmap image which is a halftone image of each color component (step S11). In the bitmap image, a plurality of pixels are arranged in a row direction corresponding to the width direction and a column direction corresponding to the scanning direction. When the original image is prepared as vector data such as character data or line drawing, the image generation unit 131 converts the data into a bitmap, thereby generating a bitmap image. In the following description, attention is paid to only one of the four colors of black, cyan, magenta, and yellow, but the same processing is performed for the other colors.

  Subsequently, in the drawing data generation unit 132, one of the ejection ports 241 of the head unit 23 is assigned to each pixel in the bitmap image, and dots at a plurality of positions on the printing paper 9 through which each ejection port 241 passes. Drawing data for instructing the ejection port 241 to turn on / off the drawing is generated (step S12). Details of the process in step S12 will be described later.

  In the printing apparatus 1 of FIG. 1, when drawing data of a portion to be printed first in the original image is generated, the printing paper 9 starts to move in the scanning direction by driving the paper feeding mechanism 29 that is a scanning mechanism. In step S13, ink is ejected from the plurality of ejection ports 241 included in each nozzle unit 251 in synchronization with the relative movement of the position on the printing paper 9 on which the dots are drawn by the head unit 23 with respect to the printing paper 9. Is controlled based on the drawing data (step S14). Note that the drawing of dots on the printing paper 9 is performed in parallel with the processing related to the generation of drawing data.

  FIG. 4 is a diagram showing the ejection positions of the ink from the ejection ports 241 on the printing paper 9. In FIG. 4, the ink discharge positions from the respective discharge ports 241 are indicated by thin line circles denoted by reference numeral 51, and a plurality of discharge positions 51 (corresponding to a plurality of discharge ports 241 included in one nozzle unit 251 are illustrated. Hereinafter, the “discharge position group” is surrounded by a thin line rectangle denoted by reference numeral 52. In FIG. 4, the three discharge position groups 52 are illustrated on the assumption that the discharge ports 241 of the three nozzle units 251 are arranged over the entire width of the print area of the printing paper 9 in the width direction. As described above, actually, a large number of nozzle units 251 are arranged in the width direction.

  FIG. 4 also shows a drawing position array 80 set on the printing paper 9. The drawing position array 80 is a set of a plurality of drawing positions arranged at a uniform density in the width direction (X direction) and the scanning direction (Y direction) on the printing paper 9. In FIG. This is indicated by a broken-line rectangle attached with. The pitch in the width direction of the drawing position 81 is the same as the pitch of the discharge ports 241 in the nozzle unit 251. Therefore, if a set of drawing positions 81 arranged in the scanning direction is a drawing position column 820, all the drawing positions 81 included in each drawing position column 820 are the discharge positions 51 of one discharge port 241 or one discharge port pair. The discharge positions 51 of the two discharge ports 241 of 242 pass and dots can be drawn at all the drawing positions 81.

  Actually, in each drawing position sequence (the drawing position sequence to which reference numeral 820a is attached, which will be referred to as “overlapping drawing position sequence 820a”) through which the ejection positions 51 of the two ejection ports 241 of the ejection port pair 242 pass, each. At the drawing position 81, dots are drawn by the drawing operation of only one of the two ejection ports 241 based on the drawing data. In addition, since the discharge position group 52 on the (+ X) side and (−X) side of the central discharge position group 52 in FIG. 4 is located on the (+ Y) side from the central irradiation position group 55, the central irradiation is performed. The position group 55 passes through the position after being delayed at the time when the position group 55 passes through a certain position in the scanning direction on the printing paper 9.

  On the printing paper 9, the region where the ejection position group 52 corresponding to each nozzle unit 251 passes and the dot drawing is performed by the nozzle unit 251 is a band extending in the scanning direction (in FIG. 4, The region is indicated by a rectangle denoted by reference numeral 71. Hereinafter, the region is referred to as a “band region”), and the plurality of band regions 71 corresponding to the plurality of nozzle units 251 are arranged in the width direction. As described above, since the end portion of each irradiation position group 55 overlaps the end portion of the adjacent irradiation position group 55 in the scanning direction, each band-like region 71 partially overlaps with the adjacent band-like region 71 in the width direction. Thus, the plurality of band-like regions 71 are set on the printing paper 9.

  When an area where two adjacent band-like areas 71 overlap (area with parallel diagonal lines in FIG. 4) is called an overlapping area 711, each overlapping area 711 includes only a plurality of overlapping drawing position rows 820a, and the band-like area In 71, an area other than the overlapping area 711 (hereinafter also referred to as “non-overlapping area”) does not include the overlapping drawing position sequence 820a. Accordingly, at each drawing position 81 included in the non-overlapping area, dots are drawn by the drawing operation of the corresponding one nozzle unit 251, and at each drawing position 81 included in the overlapping area 711, two corresponding nozzle units are drawn. A dot is drawn by one of the drawing operations of 251.

  In the printing apparatus 1, for black, cyan, magenta, and yellow, an operation of generating drawing data and recording an image on the printing paper 9 according to the drawing data is performed in parallel, and a color original image is printed on the printing paper 9. A color bitmap image (printed image) representing the above is printed. When the entire bitmap image is printed on the printing paper 9, the movement of the printing paper 9 is stopped, and the printing operation in the printing apparatus 1 is finished (step S15).

  Next, details of the process of step S12 in which the drawing data generation unit 132 generates drawing data will be described. As described above, the bitmap image generated by the image generation unit 131 is an image printed on the printing paper 9, and in the bitmap image, the column corresponding to the row direction corresponding to the width direction and the scan direction. The plurality of pixels arranged in the direction respectively correspond to the plurality of drawing positions 81 arranged and set on the printing paper 9 in the width direction and the scanning direction. Therefore, in the drawing data generation unit 132, the pixel values of the plurality of pixels of the bitmap image corresponding to the drawing position column 820 through which only the discharge position 51 of one discharge port 241 passes in the drawing position array 80 are the print paper 9. It is a value that instructs the ejection port 241 to turn on / off dot drawing at a plurality of positions in the upper scanning direction.

  On the other hand, the pixel values of the plurality of pixels of the bitmap image corresponding to the overlapping drawing position row 820a through which the discharge positions 51 of the two discharge ports 241 of the discharge port pair 242 pass are obtained by the following method. 241 is assigned.

  FIG. 5 is a diagram showing the allocation matrix 6 stored in the drawing data generation unit 132. The allocation matrix 6 is used for allocation of pixel values of a bitmap image. FIG. 6 is an allocation matrix 6a in which the values “0” and “1” of the element 61 in the allocation matrix 6 of FIG. 5 are respectively represented by a symbol “L” indicating the left side and a symbol “R” indicating the right side. The allocation matrix 6 in FIG. 5 (and the allocation matrix 6a in FIG. 6) is an element array of 12 rows and 3 columns, and the row direction (x direction in FIGS. 5 and 6) is in the width direction, similarly to the bitmap image. Correspondingly, the column direction (the y direction in FIGS. 5 and 6) corresponds to the scanning direction. In the present embodiment, the data of the allocation matrix 6 is generated in advance by the operator and input to the drawing data generation unit 132. Note that the number of elements in the row direction of the allocation matrix is the same as the number of overlapping drawing position columns 820a in the overlapping region 711, and the number of elements in the column direction is greater than or equal to the number of elements in the row direction.

  For example, in the drawing position array 80 shown in FIG. 4, an overlapping region 711 (hereinafter referred to as “overlapping region 711”) in which the central strip region 71 overlaps with the strip region 71 adjacent to the (−X) side (left side in FIG. 4) , Referred to as “attention overlapping area 711”), the attention overlapping area 711 includes three overlapping drawing position rows 820a. Conceptually, the drawing data generation unit 132 superimposes the 12-row / 3-column allocation matrix 6 of FIG. 5 on the plurality of pixels corresponding to the target overlapping region 711 in the bitmap image while repeating them in the column direction. Further, the pixel value of the pixel in the bitmap image corresponding to the element 61 of the value 0 in the allocation matrix 6 (“L” in the allocation matrix 6a in FIG. 6) is the left band-like region 71 ((−X) side). Of the pixel in the bitmap image corresponding to the element 61 of the value 1 in the assignment matrix 6 (“R” in the assignment matrix 6a in FIG. 6) assigned to the discharge port 241 of the nozzle unit 251 corresponding to the belt-like region 71). The pixel value is assigned to the ejection port 241 of the nozzle unit 251 corresponding to the right belt-like region 71 (center belt-like region 71).

  In this way, in the overlapping region 711 where two adjacent belt-like regions 71 overlap, the drawing operation by the nozzle unit 251 with respect to one belt-like region 71 of the two belt-like regions 71 and the nozzle unit 251 with respect to the other belt-like region 71. Any of the drawing operations is assigned to each drawing position 81, and drawing data is generated.

  FIG. 7 is a diagram illustrating dots drawn on the printing paper 9 in accordance with the drawing data generated by the above-described processing in the drawing data generation unit 132. The upper part of FIG. 7 shows ejection position groups (reference numerals 52a, 52b, and 52c) on the printing paper 9, and the middle part of FIG. 7 shows dots drawn on the printing paper 9 (however, at all the drawing positions 81). It is assumed that dots are drawn.) The lower part of FIG. 7 shows the average density of the image at each position in the width direction (X direction). Also, the dots shown in the middle part of FIG. 7 are given parallel oblique lines of the same type as the parallel oblique lines attached to the corresponding ejection positions 51 in the upper part of FIG. 7 and are drawn by the ejection port pair 242 (see FIG. 2). The outer edge of each dot is indicated by a thicker line than other dots (dots included in the non-overlapping area) (the same applies to FIGS. 8 to 10 and FIG. 16 described later).

  Here, in the allocation matrix 6 of FIG. 5, a plurality of elements 61 arranged in the y direction are set as an element column 610, and elements 61 having a value 0 (or elements 61 having a value 1) are randomly arranged in each element column 610. In the three element rows 610 arranged in the (+ x) direction from the (−x) side, the ratio of the elements 61 having the value 0 (“L” in the assignment matrix 6a in FIG. 6) is 75%, 50%, The ratio of the elements 61 having the value 1 (“R” in the allocation matrix 6a in FIG. 6) is 25%, 50%, and 75%, respectively. As described above, in the allocation matrix 6 of FIG. 5, the elements 61 (or the elements 61 of the value 1) having the value 0 are scattered in the element column 610, and the value 0 is increased from the (−x) side to the (+ x) side. The ratio of the element 61 is gradually decreased (the ratio of the element 61 having the value 1 is gradually increased).

  Therefore, a plurality of dots arranged in the scanning direction (Y direction) in the middle stage of FIG. 7 are arranged as a dot row in the overlap region 711 on the left side ((−X) side) 3 arranged in the (+ X) direction from the (−X) side. In each dot row, the ratios of dots drawn by ejecting ink from the ejection port 241 of the nozzle unit 251 corresponding to the ejection position group 52a in the upper stage of FIG. 7 are 75%, 50%, and 25%, respectively. 7 are 25%, 50%, and 75%, respectively, when the ink is ejected from the ejection ports 241 of the nozzle unit 251 corresponding to the ejection position group 52b in the upper stage of FIG. Further, in the three dot rows arranged in the (+ X) direction from the (−X) side in the overlapping region 711 on the right side ((+ X) side), the nozzle unit 251 corresponding to the ejection position group 52b in the upper stage of FIG. The ratios of dots drawn by ejecting ink from the ejection ports 241 are 75%, 50%, and 25%, respectively, and the inks from the ejection ports 241 of the nozzle unit 251 corresponding to the ejection position group 52c in the upper part of FIG. The proportions of dots drawn by ejection are 25%, 50%, and 75%, respectively.

  As described above, in the printing apparatus 1, in the two nozzle units 251 respectively corresponding to the two adjacent band-like regions 71 in FIG. 4, the drawing operation on the band-like region 71 by one nozzle unit 251 is the first drawing operation. When the drawing operation for the band-like region 71 by the other nozzle unit 251 is the second drawing operation, the plurality of overlapping drawing position rows 820a of the overlapping region 711 where the two band-like regions 71 overlap is assigned to the first drawing operation. The ratio (α / β) between the number α of the drawing positions 81 and the number β of the drawing positions 81 assigned to the second drawing operation is determined from the non-overlapping region in the band-like region 71 where drawing is performed by the first drawing operation. Drawing data is generated so that the distance between the overlapping drawing position columns 820a becomes smaller.

  In other words, the density of the drawing positions 81 assigned to the first drawing operation in the overlapping area 711 (that is, the first drawing operation in the overlapping drawing position sequence 820a) by the drawing data generated by the drawing data generation unit 132. This is the ratio of the assigned drawing position 81, and can also be regarded as the usage rate of the discharge port 241 that performs the first drawing operation in each discharge port pair 242). As the distance from the non-overlapping area increases, the density decreases (the density of the drawing positions 81 assigned to the second drawing operation increases). In the overlapping region 711, the drawing positions 81 assigned to the first drawing operation (or the second drawing operation) are scattered while following the density distribution of the drawing positions 81 described above.

  Here, in the two nozzle units 251 respectively corresponding to the two adjacent band-like regions 71, a difference occurs in the ink discharge amount due to variations in processing accuracy, etc., and the density of the printed image (parts thereof) is different. In this case, as shown in the upper and middle stages of FIG. 8, if all the dots in each dot row in the overlapping area 711 are drawn by ejecting ink from the ejection ports of one nozzle unit, the lower part of FIG. As shown, the density of the image changes abruptly in the overlapping region, and the position (boundary line) in the X direction where the nozzle unit is switched in the printed image is likely to be visually recognized.

  In addition, the position in the width direction of the discharge port pair 242 may slightly shift due to an attachment error of the plurality of nozzle units 251 in the head unit 23 (see the discharge position 51 in the upper stage of FIG. 9). In this case, similarly to the case shown in the middle stage of FIG. 8, when all the dots in the dot row are drawn by the ink ejection from one ejection port 241 of the ejection port pair 242, the middle and lower stages of FIG. In addition, streaky density unevenness (that is, uneven stripes) extending in the scanning direction occurs in the image printed on the printing paper 9.

  With respect to these problems, in the printing apparatus 1, in a plurality of dot rows in the overlapping region 711 where two adjacent belt-like regions 71 overlap (see the middle stage in FIG. 7), the space between one belt-like region 71 and the non-overlapping region As the distance between the dot rows is longer, the ratio of dots drawn by the nozzle unit 251 corresponding to the band-like region 71 (the ratio of dots when the dots are virtually drawn at all the drawing positions 81) decreases. As a result, even when the density of the printed image is different in the two nozzle units 251 respectively corresponding to the two adjacent belt-like regions 71, as shown in the lower part of FIG. Can be gradually changed, and the visibility of the overlapping area 711 in the printed image (that is, the degree that the overlapping area 711 can be clearly recognized) can be reduced.

  In the printing apparatus 1, the drawing position 81 assigned to the nozzle unit 251 corresponding to one of the two band-like areas 71 in each overlapping drawing position row 820 a and the nozzle unit corresponding to the other band-like area 71. Even if the position in the width direction slightly shifts in the discharge port pair 242 due to the mixture of the drawing positions 81 assigned to 251 (see the discharge position 51 in the upper stage of FIG. 10), As shown in the middle stage and the lower stage, it is possible to suppress the occurrence of stripe unevenness (that is, a rapid change in concentration with a large degree). As a result, the printing apparatus 1 can improve the quality of an image printed by the inkjet method.

  Further, in the drawing data generation unit 132 of the printing apparatus 1, the assignment matrix 6 indicating the drawing positions 81 assigned to the drawing operation of the nozzle unit 251 corresponding to one of the band-like areas 71 in the overlapping area 711 where the two band-like areas 71 overlap. Is used, drawing data can be easily generated.

  Next, a preferred method for generating allocation matrix data stored in the drawing data generation unit 132 will be described. In general printing, FM (Frequency) in which gradation expression is realized by changing the number of halftone dots (typically one dot (or pixel)) of a certain size arranged irregularly. Modulated) screen (also referred to as random screen) is used, and when the allocation matrix data used in the printing apparatus 1 in FIG. 1 is generated, first, the gradation level decreases (or increases) in the row direction. ) An image expressing the image (gradation image) to be expressed on the FM screen is prepared as shown in FIG. A plurality of pixels arranged in the column direction (y direction in FIG. 11) are pixel columns. The image in FIG. 11 includes six pixel columns, and the dots ( In FIG. 11, the number of parallel oblique lines is reduced (it can also be understood that the number of lit white pixels is increased). Then, by assigning a value of 0 to pixels in which dots are formed and assigning a value of 1 to white pixels in which dots are not formed, an allocation matrix having six element columns 610 as shown in FIG. 6b is generated.

  The allocation matrix 6b in FIG. 12 is used for an overlapping area 711 configured by six overlapping drawing position rows 820a. Thus, as in the case of using the allocation matrix 6 in FIG. 5, in the six overlapping drawing position rows 820 a of each overlapping region 711, one of the two strip regions 71 sharing the overlapping region 711. As the distance from the non-overlapping area 71 increases, the number of drawing positions 81 assigned to the drawing operation by the nozzle unit 251 corresponding to the band-like area 71 decreases in the overlapping drawing position line 820a, and each overlapping drawing position line 820a. The drawing position 81 exists at random. As a result, in the print image, it is possible to improve the quality of the print image by suppressing the occurrence of unevenness while reducing the visibility of the overlapping region 711. The assignment matrix data generated by this method is the printing apparatus 1 including the head unit 21 shown in FIG. A printing apparatus having a nozzle unit 251a of A, an electrophotographic printing apparatus 1a in FIG. 22, a plate making apparatus 1b in FIG. 24, and a plate making apparatus 1c in FIG. 26 (AM screen described below) The same applies to the method using the image expressed by (2), the method using different allocation matrices in the two overlapping regions 711 included in one band-like region 71, and the method for generating drawing data using random numbers.

  In the case where the overlapping area 711 is composed of three overlapping drawing position columns 820a as in the drawing position array 80 of FIG. 4, allocation matrix data is generated from a gradation image having three pixel columns. The Of course, in the allocation matrix 6b of FIG. 12, three element columns 610 (for example, the most (−x) side element column 610, the center element column 610 in the x direction, and the most (+ x) side element column 610). , An allocation matrix having three element columns may be generated. In addition, if the recording stability is low when dots are not drawn continuously, the allocation matrix may be generated so that at least two elements 61 having a value 1 or 0 are arranged in each element column 610. .

  In addition, an image expressing a gradation image on an AM (Amplitude Modulated) screen in which gradation expression is realized by changing the size of the regularly arranged halftone dots when generating the allocation matrix data is It may be prepared as shown in FIG. The image of FIG. 13 includes six pixel rows, and the number of dots (shown with parallel diagonal lines in FIG. 13) included in the pixel row decreases toward the (+ x) side. Yes. Then, by assigning a value of 0 to pixels in which dots are formed and assigning a value of 1 to white pixels in which dots are not formed, an allocation matrix having six element columns 610 as shown in FIG. 6c is generated. In the printing apparatus 1 of FIG. 1, by performing printing using the allocation matrix 6 c of FIG. 14, the quality of the printed image is improved by suppressing the occurrence of unevenness while reducing the visibility of the overlapping area 711 in the printed image. can do.

  In the printing apparatus 1, it is also possible to perform printing using different allocation matrices in the two overlapping areas 711 included in one band-like area 71. For example, the allocation matrix 6 shown in FIG. 5 and the allocation matrix 6d shown in FIG. 15 are prepared, and the allocation matrix 6 of FIG. 5 is used for the overlapping area 711 on the (−X) side in FIG. The allocation matrix 6d shown in FIG. In this case, when the ejection position group 52 shown in the upper part of FIG. 16 scans the printing paper 9, dots are drawn on the printing paper 9 as shown in the middle part of FIG. In each of the allocation matrix 6 in FIG. 5 and the allocation matrix 6d in FIG. 15, elements 61 having a value of 0 are randomly arranged in each element column 610, and three elements are arranged in the (+ x) direction from the (−x) side. In the element row 610, the ratio of the element 61 having a value of 0 is 75%, 50%, and 25%, respectively. As a result, as shown in the lower part of FIG. 16, in the two adjacent overlapping regions 711 (the overlapping region 711 on the (−X) side and the (+ X) side), the density of the image is gradually changed with respect to the X direction. The distribution of dots drawn by the nozzle unit 251 corresponding to the (-X) side (or (+ X) side) band-like region 71 can be made different while reducing the visibility of the overlapping region.

  Further, the printing apparatus 1 may generate drawing data without using an allocation matrix. For example, when each overlapping area 711 includes three overlapping drawing position rows 820a, such as the overlapping area 711 in the drawing position array 80 of FIG. 4, the most (−X) -side overlapping in the overlapping area 711. The drawing position 81 included in the drawing position column 820a is associated with a threshold value 0.25, and the drawing position 81 included in the overlapping drawing position column 820a adjacent to the (+ X) side of the overlapping drawing position column 820a has a threshold value 0. .50, and the drawing position 81 included in the most (+ X) side overlapping drawing position column 820a is associated with a threshold value 0.75. The drawing data generation unit 132 sequentially generates random numbers (pseudo-random numbers) from 0 to 1 for a plurality of drawing positions 81 in the overlapping area 711, and the drawing position 81 having a random number equal to or greater than the corresponding threshold has a value of 0. A value 1 is assigned to the drawing position 81 that is assigned and whose random number is smaller than the corresponding threshold value.

  Accordingly, in the three overlapping drawing position rows 820a arranged in the (+ X) direction from the (−X) side in the overlapping region 711, the density of the drawing positions 81 to which the value 0 is given (that is, in the overlapping drawing position row 820a). %) Can be stochastically set to 75%, 50%, 25% according to the corresponding thresholds 0.25, 0.50, 0.75. The drawing position 81 to which the value 0 is assigned is assigned to the drawing operation of the nozzle unit 251 corresponding to the band region 71 on the (−X) side of the two strip regions 71 sharing the overlapping region 711, and the value 1 is set. The assigned drawing position 81 is assigned to the drawing operation of the nozzle unit 251 corresponding to the band region 71 on the (+ X) side. The assignment of the drawing operation to the drawing position 81 in the overlapping area 711 acquired by the above processing is used in the same manner for all the overlapping areas 711. Note that the above processing may be performed individually for all the overlapping regions 711 depending on the calculation capability of the drawing data generation unit 132.

  Here, when an allocation matrix is used in the drawing data generation unit 132, it is possible to easily generate drawing data. However, as described above, the allocation matrix is repeated in the scanning direction, so that two data can be generated. When dots are drawn in one band-like area 71 in the overlapping area 711 where the band-like areas 71 overlap, periodicity (periodicity in the scanning direction) occurs at the positions of the dots drawn in the overlapping area 711.

  On the other hand, in the drawing data generation method using the random number, the drawing position 81 assigned to the drawing operation of the nozzle unit 251 corresponding to one band-like area 71 in the overlapping area 711 where the two band-like areas 71 overlap. Is determined by comparing sequentially generated random numbers with a threshold corresponding to the density of the drawing positions 81. As a result, it is possible to prevent the occurrence of periodicity at the positions of the dots drawn in the overlapping area 711 when the dots are drawn in the one band-like area 71.

  In the printing apparatus 1 of FIG. 1, the arrangement of the nozzle units 251 is the same in the plurality of head units 23 that eject inks of different colors, but in the more preferable printing apparatus 1, the nozzle units 251 in the plurality of head units 23. The arrangement of is different. FIG. 17 is a bottom view showing another example of the head unit 21. In FIG. 17, a plurality of nozzle units 251C of the head portion 23C that ejects C-color ink and M-color ink are ejected. A plurality of nozzle units 251M of the head portion 23M are illustrated. Actually, the head unit 21 is also provided with a head portion 23 for ejecting ink of other colors.

  As shown in FIG. 17, in the head unit 21, the positions of the ejection port pair 242 in the X direction are different in the head portions 23C and 23M. Therefore, in the process of step S12 in the printing operation of FIG. 3, the drawing data is generated for each color component while the positions in the x direction in the bitmap image where the allocation matrix is superimposed on the plurality of color components of the original image are different. In the processes of steps S13 and S14, dots of each color component are drawn on the plurality of band-like areas 71 on the printing paper 9 set so that the position in the width direction of the overlapping area 711 is different for each color component. Is called.

  Here, in the plurality of color components, when the positions of the overlapping areas 711 set on the printing paper 9 are the same (that is, the positions of the plurality of strip-shaped areas 71 are the same), the drawing data generation unit 132 Drawing data can be easily generated by performing the same processing on a bitmap image of a plurality of color components, but there is a peculiarity such as a difference in hue compared to other areas in an overlapping area 711 in a printed image. Part may occur. On the other hand, in the printing apparatus 1 including the head unit 21 of FIG. 17, it is possible to suppress the occurrence of a peculiar portion in a color print image by shifting the overlapping region 711 for each color component.

  Further, as shown in FIG. 18, the number of ejection ports 241 in the nozzle units 251C and 251M is made different for each color component, or as shown in FIG. 19, ejection port pairs in two nozzle units adjacent in the width direction. By making the number of 242 different for each color component, the position of the overlapping region 711 can be made different in the width direction for a plurality of color components. In the head unit 21 of FIG. 18, the number of ejection ports 241 in each nozzle unit 251C of the head portion 23C is 12, and the number of ejection ports 241 in each nozzle unit 251M of the head portion 23M is 10. In the head unit 21 of FIG. 19, the number of ejection port pairs 242 in the two adjacent nozzle units 251C in the head portion 23C is 3, and the ejection port pair 242 in the two adjacent nozzle units 251M in the head portion 23M. The number is five. In the head unit 21 of FIGS. 18 and 19, the number of nozzle units 251 is also different for each color component.

  In the printing apparatus 1 described above, a plurality of discharge ports 241 are arranged in a row in the width direction in each nozzle unit 251. For example, as shown in FIG. 20, the discharge ports 241 are arranged in the width direction (X direction). A nozzle unit 251 in which a plurality of ejection port arrays 240 arranged in a line is arranged in the scanning direction (Y direction) may be used. In each nozzle unit 251 in FIG. 20, when focusing only on the width direction, between the two discharge ports 241 adjacent in the width direction in one discharge port row 240, the other two discharge port rows 240. Each of the discharge ports 241 is arranged, and in the entire head portion 23, a large number of discharge ports 241 are arranged in the width direction. Also in the head unit 23 of FIG. 20, an ejection port pair 242 is provided in two adjacent nozzle units 251.

  In the printing apparatus, printing may be performed by the head unit performing main scanning and sub-scanning on the printing paper 9. Specifically, FIG. As shown in A, one nozzle unit 251 a in which the discharge ports 241 are arranged in the Y direction is provided in the head unit 23. FIG. In A (and FIGS. 21B to 21F described later), only the nozzle unit 251a of one color is shown superimposed on the printing paper 9, and actually, the nozzle units of a plurality of colors are arranged in the X direction. Arranged. FIG. The configuration of the printing apparatus having the A nozzle unit 251a is the same as that of the printing apparatus 1 of FIG. 1 except for the orientation and number of the nozzle units 251a and the arrangement of nozzle units of a plurality of colors.

  FIG. In the printing operation in the printing apparatus having the A nozzle unit 251a, drawing data is generated after the bitmap image is generated in the same manner as in the printing apparatus 1 in FIG. 1 (the generation of the drawing data will be described later). (FIG. 3: Steps S11 and S12). Subsequently, FIG. As indicated by the arrow labeled A1 in A, the nozzle unit 251a is continuously moved in the (+ X) direction from the (−X) side of the printing paper 9 by the head moving mechanism 22 (see FIG. 1) (mainly Scanning) (step S13), FIG. As shown in B, dots are drawn in an area 71a on the printing paper 9 through which the nozzle unit 251a has passed (an area with parallel diagonal lines in FIG. 21B) (step S14).

  FIG. When the nozzle unit 251a moves to the (+ X) side of the printing paper 9 as shown in FIG. As indicated by the arrow labeled A2 in C, the paper feeding mechanism 29 moves the printing paper 9 in the (+ Y) direction (that is, the nozzle unit 251a performs sub-scanning with respect to the printing paper 9). Then, FIG. D thru | or FIG. As shown in F, when the nozzle unit 251a continuously moves in the (−X) direction, the region 71b on the printing paper 9 through which the nozzle unit 251a has passed (in FIGS. 21E and 21F). Dots are drawn in a region with parallel diagonal lines in a different direction from the region 71a. When printing is performed on the entire printing paper 9 by repeating the above operation, the movement of the nozzle unit 251a by the head moving mechanism 22 and the intermittent movement of the printing paper 9 by the paper feeding mechanism 29 are stopped. The operation is completed (step S15).

  Thus, FIG. In the printing apparatus having the A nozzle unit 251a, the head moving mechanism 22 and the paper feeding mechanism 29 serve as scanning mechanisms, and the positions on the printing paper 9 on which dots are drawn by the nozzle unit 251a are set in the main scanning direction (that is, continuous scanning). Direction) and a sub-scanning direction (that is, an intermittent movement direction) perpendicular to the main scanning direction. Of course, the printing apparatus may be provided with a mechanism for moving the printing paper 9 in the main scanning direction and a mechanism for moving the nozzle unit 251a in the sub-scanning direction.

  Here, in the printing apparatus having the nozzle unit 251a, each of the areas 71a and 71b is called a band-like area like the band-like area 71 in the drawing position array 80 of FIG. 4, and the area 711 where the band-like areas 71a and 71b overlap (that is, 21E and 21F are referred to as overlapping regions), a plurality of strip-like regions 71a each extending in the continuous scanning direction (X direction) on the printing paper 9. , 71b are considered to be arranged in the Y direction perpendicular to the scanning direction. Then, the nozzle unit 251a moves relative to the printing paper 9 once in the scanning direction, so that dots are drawn in one belt-like region, and the plurality of belt-like regions 71a and 71b are drawn by the nozzle unit 251a. Sequential dots are drawn.

  Also in the printing apparatus having the nozzle unit 251a, in the two adjacent belt-like regions 71a and 71b, the drawing operation by the nozzle unit 251a with respect to one belt-like region 71a is the first drawing operation and the nozzle unit 251a with respect to the other belt-like region 71b. When the drawing operation is the second drawing operation, in the overlapping region 711 where the two band-like regions 71a and 71b overlap, the density of the drawing position assigned to the first drawing operation increases as the distance from the non-overlapping region of the band-like region 71a increases. One of the first drawing operation and the second drawing operation is assigned to each drawing position in the overlapping area 711 where dots can be drawn by the drawing data generated in the process of step S12 so as to decrease. Thereby, for the reason of the structure of the nozzle unit 251a, the amount of ink discharged from the plurality of discharge ports 241 gradually increases (decreases) from one end to the other end (for example, the nozzle unit In the overlapping area 711 in the printed image, the density of the image is gradually changed in the Y direction to reduce the visibility of the overlapping area 711. Generation of uneven stripes can be suppressed, and the quality of the printed image can be improved.

  FIG. 22 is a diagram showing a configuration of an electrophotographic printing apparatus 1a according to the second embodiment of the present invention. The printing apparatus 1a is an image recording apparatus that records an electrostatic latent image on a photosensitive drum. In the printing apparatus 1a, a toner image obtained by applying toner to the electrostatic latent image on the photosensitive drum is printed on a printing sheet. Printing is performed by transferring the image on the upper surface 9. In FIG. 22, the main body control unit 13 is not shown (the same applies to the plate making apparatuses 1b and 1c shown in FIGS. 24 and 26 described later).

  The printing apparatus 1a of FIG. 22 includes a photosensitive drum 31 that holds (forms) a photosensitive member 311 on its outer surface and rotates about a predetermined rotation axis J1 by a motor 312. Around the photosensitive drum 31, a charger 32 that generates ions to charge the photosensitive member 311, a head unit 33 that emits image recording light and records an electrostatic latent image on the photosensitive member 311, and the photosensitive member A developing unit 34 that applies toner to the electrostatic latent image recorded on the image 311 and develops it; a transfer unit 37 that transfers the toner on the photoconductor 311 to the printing paper 9; a cleaner 35 that cleans the surface of the photoconductor 311; In addition, a static eliminator 36 that emits light and neutralizes the photosensitive member 311 is sequentially arranged clockwise.

  FIG. 23 is a diagram illustrating a part of the head portion 33. As shown in FIG. 23, in the head unit 33, a plurality of LED arrays 331 are parallel to the rotation axis J1 of the photosensitive drum 31 (the direction shown as the X direction in FIG. 23). , Which are referred to as “width direction”) over the entire width of the photosensitive drum 31, and a plurality of LEDs 332 are arranged in the width direction in each LED array 331. Light from each LED 332 is guided onto the photoconductor 311 via an optical system (not shown), and dots are drawn in the region on the photoconductor 311 irradiated with the light. Thus, in the LED array 331 which is a drawing mechanism, each LED 332 is a dot output element for drawing a dot. Similar to the nozzle unit 251 of the head portion 23 in the first embodiment, in the two LED arrays 331 adjacent to each other in the width direction, the plurality of LEDs 332 in the vicinity of the end portion are perpendicular to the width direction and are on the outer surface of the photosensitive drum 31. Are arranged so as to overlap with each other (a vertical direction perpendicular to the X direction in FIG. 23).

  In the printing apparatus 1a, the photosensitive drum 31 serving as a holding unit for the photosensitive member 311 rotates clockwise about the rotation axis J1 (in the direction indicated by the arrow labeled A3 in FIG. 22), so that the head The irradiation position of light irradiated from the section 33 onto the photosensitive drum 31 (that is, the position irradiated with light when each LED 332 is turned on) is perpendicular to the rotation axis J1 and outside the photosensitive drum 31. It moves relative to the photoreceptor 311 in a direction along the side surface (hereinafter referred to as “scanning direction” in the printing apparatus 1a). In the following description, a combination of two LEDs 332 in which light irradiation positions on the photoreceptor 311 pass through the same positions in two adjacent LED arrays 331 is referred to as an LED pair.

  When printing is performed by the printing apparatus 1a, a bitmap image is generated by the image generation unit 131 of the main body control unit 13 as in the first embodiment (FIG. 4: step S11), and drawing is performed. The data generation unit 132 generates drawing data (step S12). Subsequently, the motor 312 that is a scanning mechanism is driven to start the rotation of the photosensitive drum 31, so that the positions on the photosensitive member 311 where dots are drawn by the head unit 33 (that is, the plurality of LEDs 332 respectively correspond). (A set of a plurality of irradiation positions) starts to move in the scanning direction relative to the photoconductor 311 (step S13), and emission of light from the head unit 33 is controlled to draw dots on the photoconductor 311. (Step S14).

  Actually, in the printing apparatus 1a, an electrostatic latent image, which is a set of dots, is recorded on each part on the photoreceptor 311 by the head unit 33, and the electrostatic latent image is developed with toner by the developing unit 34. A toner image is formed, and then the toner image is transferred onto the printing paper 9 by the transfer unit 37. Thus, in the printing apparatus 1a, the photosensitive member 311 of the photosensitive drum 31 is an object on which dots (elements of an electrostatic latent image) are drawn by light irradiation from the head unit 33, and is a set of dots. An image (bitmap image) is printed on the printing paper 9 using the photoreceptor 311 on which the electrostatic latent image is recorded. When the entire bitmap image is printed on the printing paper 9, the photosensitive drum 31 stops rotating and the printing operation in the printing apparatus 1a is completed (step S15).

  Here, in the printing apparatus 1 a, as in the drawing position array 80 of FIG. 4, a plurality of drawing positions are arranged on the photoconductor 311 in the width direction and the scanning direction, and dots are drawn by one LED array 331. A plurality of band-like areas are arranged in the width direction at a pitch smaller than the width of the band-like area. Actually, the plurality of LED arrays 331 of the head portion 33 correspond to all the strip-like regions arranged over almost the entire width of the photosensitive member 311, and the strip-like regions adjacent to the respective strip-like regions in the width direction. A region where and partially overlap each other is an overlapping region through which the irradiation position of the light of the LED pair passes.

  Then, in two adjacent strip regions, the drawing operation by the LED array 331 corresponding to one strip region is a first drawing operation, and the drawing operation by the LED array 331 corresponding to the other strip region is a second drawing operation. In this case, in the overlapping region where the two strip regions overlap, the density of the drawing position assigned to the first drawing operation decreases as the distance from the non-overlapping region of the strip region corresponding to the LED array 331 performing the first drawing operation decreases. One of the first drawing operation and the second drawing operation is assigned to each drawing position of the overlapping region by the drawing data so as to reduce (the density of the drawing positions assigned to the second drawing operation increases). As a result, even if there is a difference in the intensity of light emitted from the LEDs 332 in the two adjacent LED arrays 331, the printing apparatus 1a reduces the visibility of the overlapping region in the printed image. However, the occurrence of uneven stripes can be suppressed, and the quality of the printed image can be improved.

  In the above description, the case where the printing apparatus 1a prints an image of one color has been described. However, in the printing apparatus 1a, there are four printing apparatuses 1a corresponding to four color toners of K, C, M, and Y, respectively. A color image may be printed in a row, and in this case, the four printing apparatuses 1a are regarded as one image recording apparatus that records an image on the object with a set of four photoconductors as the object. be able to. Further, in such an image recording apparatus, it is possible to prevent occurrence of a peculiar portion in a color print image by shifting the position of the overlapping region on the photoconductor in the width direction for each color component. Of course, in the printing apparatus 1a of FIG. 22, four printing units for K, C, M, and Y may be arranged around one photosensitive drum 31 to realize color printing.

  FIG. 24 is a diagram showing a configuration of a plate making apparatus 1b according to the third embodiment of the present invention. The plate making apparatus 1b includes a head unit 41 that emits a light beam, and a holding drum 42 that is a holding unit that holds a printing plate 9a on which an image is recorded on an outer surface. The printing plate 9a is irradiated with the light beam from the head unit 41 while being scanned, whereby an image is recorded (that is, the image is drawn by light irradiation). In the present embodiment, the plate making apparatus 1b is an apparatus for CTP (Computer To Plate), but it may be used as an image setter.

  The holding drum 42 is rotated by the motor 421 about the central axis of the cylindrical surface, so that the head portion 41 is relatively constant in the circumferential direction around the rotation axis J2 of the holding drum 42 with respect to the printing plate 9a. Move at speed. The head portion 41 can be moved in a direction parallel to the rotation axis J2 of the holding drum 42 (hereinafter referred to as “width direction” in the plate making apparatus 1b) by a head moving mechanism 430 having a motor 431 and a ball screw 432. The position of the head portion 41 is detected by the encoder 433. Thus, the scanning mechanism including the motor 421 and the head moving mechanism 430 allows the irradiation position on the printing plate 9a of the light beam from the head portion 41 to be relatively relative to the printing plate 9a in the circumferential direction at a constant speed. While moving, it is also relatively movable in the width direction (moves intermittently in the width direction as will be described later).

  The head unit 41 has a plurality of light irradiation units 411 arranged in the width direction. Each light irradiation unit 411 includes a light source unit 412 having a semiconductor laser that emits a high-intensity light beam, and an optical system 413 that guides the light beam emitted from the light source unit 412 onto the printing plate 9a. Dots are drawn in the area on the printing plate 9a irradiated with light from 412. Thus, in the light irradiation part 411 which is a drawing mechanism, the light source part 412 is a dot output element. The irradiation positions of a plurality of light beams respectively corresponding to the plurality of light irradiation units 411 on the printing plate 9a are arranged with a certain interval in the width direction. The light source unit 412 is connected to the main body control unit 13 (see FIG. 1), and the main body control unit 13 controls ON / OFF of the light beam from the semiconductor laser.

  When printing is performed by the plate making apparatus 1b, a bitmap image is generated by the image generation unit 131 of the main body control unit 13 as in the first embodiment (FIG. 4: step S11), and drawing is performed. The data generation unit 132 generates drawing data (step S12). Subsequently, when the holding drum 42 starts to rotate, a position on the printing plate 9a where dots are drawn by the head unit 41 (that is, a set of a plurality of irradiation positions from the plurality of light irradiation units 411) is the printing plate. The movement in the circumferential direction is started relative to 9a (step S13), the emission of light from the head portion 41 is controlled, and dots are drawn on the printing plate 9a (step S14).

  FIG. 25 is a diagram showing the outer surface of the holding drum 42 in a developed state. Similar to the drawing position array 80 in FIG. 4, they are arranged on the printing plate 9 a in the circumferential direction (shown as Y direction in FIG. 25) and in the width direction (shown as X direction in FIG. 25). A drawing position array 80 which is a set of a plurality of drawing positions 81 is set. As described above, a plurality of irradiation positions respectively corresponding to the plurality of light irradiation units 411 (that is, positions where light is irradiated when the light source unit 412 is turned on, the reference numeral 53 in FIG. Are indicated by a solid circle with a gap in the width direction, and a plurality of irradiation positions 53 are relatively arranged with respect to the printing plate 9a in the circumferential direction which is the scanning direction by the rotation of the holding drum 42. By moving, dots are drawn in a drawing position column 820 that is a set of drawing positions 81 arranged in the Y direction. In the following description, the circumferential positions of the plurality of irradiation positions 53 shown in FIG. 25 are referred to as “circumferential drawing start positions”.

  When the plurality of irradiation positions 53 reach the end on the (+ Y) side of the printing plate 9a, the plurality of irradiation positions 53 are not present on the printing plate 9a (that is, the head portion 41 is on the outer surface of the holding drum 42). While facing the portion without the printing plate 9a), the head moving mechanism 430 moves the head portion 41 in the (+ X) direction, and each irradiation position 53 in the X direction is the drawing position where the dot was drawn immediately before. It becomes the same position as the drawing position row 820 adjacent to the (+ X) side of the row 820 (that is, each irradiation position 53 moves in the (+ X) direction by a distance corresponding to the width of the drawing position 81 in the X direction). Thereafter, the plurality of irradiation positions 53 reach the drawing start position in the circumferential direction, and dots are drawn at the drawing position 81 in the drawing position row 820 by the light source unit 412 of each light irradiation unit 411. In the plate making apparatus 1b, the operation of moving each irradiation position 53 from the drawing start position in the circumferential direction to the (+ Y) side and returning to the same position in the circumferential direction by rotating the holding drum 42 once is one of the irradiation positions 53. The irradiation position 53 is intermittently moved in the width direction while the irradiation position 53 does not exist on the printing plate 9a.

  In the plate making apparatus 1b, each irradiation position 53 (excluding the irradiation position 53 closest to the (+ X) side) is moved to the (+ X) side by repeating the scanning of the irradiation position 53 and the intermittent movement in the width direction a predetermined number of times. An adjacent irradiation position 53 (hereinafter referred to as “adjacent irradiation position 53”) reaches the drawing position row 820 that has passed during the first scan, and dots are drawn in this drawing position row 820 (as will be described later). Dots are not drawn at all the drawing positions 81). Subsequently, the scanning of the irradiation position 53 and the intermittent movement in the width direction are further repeated. When each irradiation position 53 passes through the drawing position row 820 through which the adjacent irradiation position 53 has already passed, a dot is drawn. The rotation of the drum 42 is stopped, and the image recording operation in the plate making apparatus 1b is completed (step S15). In FIG. 25, the irradiation position 53 in the last scan is indicated by a broken-line circle.

  As described above, the plate making apparatus 1b is an image recording apparatus that records an image on the printing plate 9a. By printing on the printing plate 9a using another device, a bitmap is formed on the printing paper. An image is printed (the same applies to the plate making apparatus 1c in FIG. 26 described later).

  Here, in the printing plate 9a, a region where dots are drawn by the irradiation position 53 of one light irradiation unit 411 (light source unit 412) being repeatedly scanned and intermittently moved in the width direction is defined as a band-shaped region 71. It can be understood that the belt-like regions 71 are arranged in the width direction, and a region where each belt-like region 71 and the belt-like region 71 adjacent in the width direction partially overlap (regions with parallel diagonal lines in FIG. 25). It becomes the overlapping area | region 711 through which the irradiation position of two light irradiation parts 411 overlaps. Then, in two adjacent band regions 71, the drawing operation by one light irradiation unit 411 for one band region 71 is set as a first drawing operation, and the drawing operation by another light irradiation unit 411 for the other band region 71 is a first drawing operation. In the case of two drawing operations, in the overlapping region 711 where the two band regions 71 overlap, the density of the drawing positions 81 assigned to the first drawing operation corresponds to the band shape corresponding to the light irradiation unit 411 that performs the first drawing operation. One of the first drawing operation and the second drawing operation is assigned to each drawing position 81 of the overlapping region 711 by the drawing data so as to decrease as the distance from the non-overlapping region of the region 71 increases. As a result, even if the intensity of light emitted from the light source unit 412 is different between the two adjacent light irradiation units 411, the plate making apparatus 1b can improve the visibility of the overlapping region 711 in the printed image. It is possible to suppress the occurrence of uneven stripes while reducing the quality of the printed image.

  In the plate making apparatus 1b, by the above operation, a bitmap image of the first color component is recorded on the printing plate of the first color component, and the printing plate on the holding drum 42 prints the second color component. After the replacement with the plate, the bitmap image of the second color component may be recorded on the printing plate of the second color component by the same operation as described above. In this case, the plate making apparatus 1b is configured to collect a printing plate on which a bitmap image of the first color component is recorded and a set of printing plates on which a bitmap image of the second color component is recorded (of course, other colors). A printing plate on which a bitmap image of the component is recorded may be included), and is regarded as an image recording apparatus that records an image on the object. By performing printing, a color bitmap image is printed on the printing paper. Further, in such an image recording apparatus, it is possible to prevent occurrence of a peculiar portion in a color print image by shifting the position of the overlapping region on the printing plate in the width direction for each color component (described later). The same applies to the plate making apparatus 1c of FIG.

  FIG. 26 is a diagram showing another example of the plate making apparatus. The plate making apparatus 1c in FIG. 26 is different from the plate making apparatus 1b in FIG. 24 only in the configuration of the head portion 41a, and the other configurations are the same, and are denoted by the same reference numerals.

  The head unit 41a has one light irradiation unit 411a in which a plurality of light source units 412a are arranged in the width direction, and light beams from the plurality of light source units 412a are guided onto the holding drum 42 by the optical system 413a. As shown in FIG. 27 in which the printing plate 9a is developed, a plurality of lines are continuously arranged on the printing plate 9a in the width direction (shown as the X direction in FIG. 27) and respectively correspond to the plurality of light source units 412a. An irradiation position 54 (indicated by a thin line circle in FIG. 27) is irradiated with a light beam. In the following description, a set of a plurality of irradiation positions 54 is referred to as an irradiation position group 55. In FIG. 27, it is assumed that the printing plate 9a is provided almost entirely in the circumferential direction on the holding drum.

  When printing is performed by the plate making apparatus 1c, a bitmap image is generated by the image generation unit 131 of the main body control unit 13 as in the first embodiment (FIG. 4: step S11), and drawing is performed. The data generation unit 132 generates drawing data (step S12). Subsequently, when the holding drum 42 starts to rotate, the irradiation position group 55 on the printing plate 9a starts to move in the circumferential direction of the holding drum 42 relative to the printing plate 9a. Further, the head portion 41a is continuously moved in the width direction at a constant speed by the head moving mechanism 430 (step S13), and the irradiation position group 55 is moved in the width direction and the circumferential direction in FIG. 27 (Y in FIG. 27). Relative to the printing plate 9a in a direction inclined with respect to the printing plate 9a (a direction indicated by an arrow labeled A4 in FIG. 27 and hereinafter referred to as a “scanning direction” in the plate making apparatus 1c). Move on. Then, the light irradiation unit 411a is controlled in synchronization with the scanning of the irradiation position group 55, whereby dots are drawn on the printing plate 9a (step S14).

  At this time, in the plate making apparatus 1c, while the irradiation position group 55 performs one scan (that is, while the holding drum 42 rotates once), the irradiation position group 55 is in the (+ X) direction. It moves by a distance narrower than the width in the width direction. Specifically, when focusing on the drawing start position in the circumferential direction (position in the Y direction of the irradiation position group 55 in FIG. 27), the (−X) side of the irradiation position group 55 in the second and subsequent scans. The head portion 41a moves in the width direction (spiral exposure) so that the plurality of irradiation positions 54 exactly overlap with the same number of irradiation positions 54 on the (+ X) side of the irradiation position group 55 at the time of the previous scan. When dots are drawn on the entire plate 9a, the rotation of the holding drum 42 and the movement of the head portion 41a are stopped, and the image recording operation in the plate making apparatus 1c is completed (step S15).

  As described above, in the plate making apparatus 1c, the irradiation position group 55 moves relative to the printing plate 9a in the scanning direction (direction indicated by the arrow A4 in FIG. 27). 27, a plurality of drawing positions 81 indicated by broken parallelograms (only a part of the drawing positions 81 are shown in FIG. 27) are arranged in the scanning direction and the width direction. It is done. Moreover, the area | region where a dot is drawn by one scan of the irradiation position group 55 is made into the strip | belt-shaped area | region 71, the some strip | belt-shaped area | region 71 is arranged in the width direction, and the strip | belt-shaped area | region adjacent to each strip | belt-shaped area 71 in the width direction. A region that partially overlaps 71 (a region indicated by parallel oblique lines in FIG. 27) becomes an overlapping region 711 through which the irradiation position 54 passes through two consecutive scans of the irradiation position group 55.

  Then, in two adjacent band-like regions 71, the drawing operation at the time of scanning the irradiation position group 55 for one band-like region 71 is set as a first drawing operation, and the drawing operation at the time of scanning of the irradiation position group 55 for the other band-like region 71 is performed. In the overlapping region 711 where the two band-like regions 71 overlap, the density of the drawing positions 81 assigned to the first drawing operation is not the same as that of the band-like region 71 corresponding to the first drawing operation. One of the first drawing operation and the second drawing operation is assigned to each drawing position 81 of the overlapping area 711 by the drawing data so as to decrease as the distance from the overlapping area increases. Thereby, in the light irradiation part 411a, even when the intensity of the light beam emitted from the plurality of light source parts 412a gradually increases (decreases) from one end to the other end, the plate making is performed. In the device 1c, it is possible to improve the quality of the printed image by suppressing the occurrence of unevenness while reducing the visibility of the overlapping region 711 in the printed image.

  In addition, in the head portion 41a of FIG. 26, a plurality of light irradiation portions 411a may be arranged at intervals in the width direction as in the head portion 41 of FIG. 24. In this case, as shown in FIG. On the printing plate 9a, a plurality of irradiation position groups 55a (each irradiation position 54 is indicated by a thin solid circle) are arranged at intervals in the width direction (indicated as the X direction in FIG. 28). Is done. Then, dots are drawn on the printing plate 9a while the irradiation position group 55a on the printing plate 9a continuously moves in the circumferential direction (shown as the Y direction in FIG. 28) and the width direction.

  In such a plate making apparatus, a plurality of irradiation position groups 55a are relatively relative to the printing plate 9a in the scanning direction inclined with respect to the width direction and the circumferential direction (the direction indicated by the arrow labeled A4 in FIG. 28). 27, as in FIG. 27, it is considered that a plurality of drawing positions 81 indicated by broken parallelograms in FIG. 28 are arranged in the scanning direction and the width direction on the printing plate 9a. be able to. Moreover, the area | region where a dot is drawn by one scan of each irradiation position group 55a is made into the strip | belt-shaped area | region 71, the some strip | belt-shaped area | region 71 is arranged in the width direction, and strip | belt-shaped adjacent to each strip | belt-shaped area | region 71 in the width direction. A region that partially overlaps the region 71 is an overlapping region 711 where the irradiation position 54 overlaps through two consecutive scans of the same irradiation position group 55a (region that is cross-hatched in FIG. 28). Or, it becomes an overlapping region 711 (region with parallel oblique lines (excluding cross-hatching) in FIG. 28) through which the irradiation positions 54 of the two light irradiation units 411a pass. In FIG. 28, the irradiation position group 55a at the time of the next scanning of the irradiation position group 55a indicated by a solid circle is indicated by a broken circle.

  Then, in the two adjacent belt-like regions 71, the drawing operation at the time of scanning the irradiation position group 55a with respect to one belt-like region 71 is set as the first drawing operation, and the drawing operation at the time of scanning of the irradiation position group 55a with respect to the other belt-like region 71. In the overlapping region 711 where the two band-like regions 71 overlap, the density of the drawing positions 81 assigned to the first drawing operation is not the same as that of the band-like region 71 corresponding to the first drawing operation. As the distance from the overlap region decreases, or in two adjacent band regions 71, the drawing operation by one light irradiation unit 411a for one band region 71 is set as the first drawing operation, and the other band region 71 is When the drawing operation by the other light irradiation unit 411a is the second drawing operation, in the overlapping region 711 where the two band-like regions 71 overlap, the first The drawing data 81 is assigned to each drawing position 81 in the overlapping area 711 so that the density of the drawing position 81 assigned to the drawing action decreases as the density of the drawing area 81 decreases from the non-overlapping area of the band-like area 71 corresponding to the first drawing action. One of the first drawing operation and the second drawing operation is assigned. Thereby, in the light irradiation part 411a, when the intensity | strength of the light beam radiate | emitted from several light source parts 412a toward one end part from the other end gradually increases (decreases), or two adjacent lights Even when the intensity of the light emitted from the irradiation unit 411a is different, the plate making apparatus can suppress the occurrence of uneven stripes while reducing the visibility of the overlapping region 711 in the print image. Can improve the quality.

  Further, in a plate making apparatus provided with a plurality of light irradiation units 411a and each light irradiation unit 411a having a plurality of light source units 412a, the light irradiation unit 411a moves relative to the printing plate 9a once in the scanning direction. As a result, the drawing of dots in one band-like region 71 is performed (completed). Thereby, in the plate making apparatus, an image can be recorded in a shorter time than the plate making apparatus 1b in FIG. 24 and the plate making apparatus 1c in FIG.

  As described above, as described in the ink jet printing apparatus 1 in FIG. 1, the electrophotographic printing apparatus 1a in FIG. 22, and the plate making apparatus 1b in FIG. 24, two belt-like regions in which dots are drawn by different drawing mechanisms. In the overlapping region 711 in which the two belt-like regions 71 overlap while the two belt-like regions 71 overlap, the density of the drawing position 81 assigned to the drawing operation by the drawing mechanism corresponding to one belt-like region 71 is A technique for suppressing the occurrence of unevenness while reducing the visibility of the overlapping area 711 by generating drawing data so as to decrease as the distance from the non-overlapping area decreases. Multiple drawing mechanisms for drawing dots on an object And a scanning mechanism that moves a position on the object on which dots are drawn by a plurality of drawing mechanisms at least in a predetermined scanning direction with respect to the object. It can be employed in various image recording apparatus to obtain.

  FIG. As described in the printing apparatus having the A nozzle unit 251a and the plate making apparatus 1c in FIG. 26, the two belt-like regions 71 on which dots are drawn at the time of different scanning of the same drawing mechanism are partially overlapped. In the overlapping area 711 where the two band-like areas 71 overlap, the density of the drawing positions 81 assigned to the drawing operation at the time of scanning corresponding to the one band-like area 71 decreases as the distance from the non-overlapping area of the band-like area 71 decreases. In this way, by generating drawing data as described above, a technique for suppressing the occurrence of stripe unevenness while reducing the visibility of the overlapping region 711 includes a drawing mechanism for drawing dots on an object, and an object on which dots are drawn by the drawing mechanism. A scanning mechanism that moves the position on the object in a predetermined scanning direction and a direction perpendicular to the scanning direction with respect to the object, and outputs a plurality of dots Drawing mechanism having a prime can be be employed in various image recording apparatus for drawing a dot to one band-like region by once relatively moved in the scanning direction relative to the object.

  In the plate making apparatus 1c shown in FIG. 26, a print in which dots are drawn by the light irradiation unit 411a by the head moving mechanism 430 that moves the light irradiation unit 411a, which is a drawing mechanism, in a direction parallel to the rotation axis J2 of the holding drum 42. It can be said that the position on the plate 9a has moved in a direction substantially perpendicular to the scanning direction.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible.

  In the above embodiment, a binary bitmap image is generated by the image generation unit 131. For example, in an ink jet printing apparatus, the amount of ink discharged from each discharge port 241 of the nozzle unit 251 is changed. Thus, it is possible to form (n-1) types of dots (n is a natural number of 2 or more) in size, that is, when n values can be output (including those in which dots are not formed). In the image generation unit 131, the original image of m gradations (where m is a natural number larger than n) is halftoned, or the character data or vector data is converted into a bitmap. , N-value bitmap images may be generated.

  Each overlapping area 711 is a plurality of (more preferably, three or more) overlapping drawing position sequences (that is, a plurality of drawing positions 81 arranged in the scanning direction within the overlapping area 711, in FIGS. 25, 27, and 28. The same is true)), the number of overlapping drawing position rows in a plurality of overlapping regions 711 (that is, the width of the overlapping region 711 in the direction perpendicular to the scanning direction) may be different.

  In the printing apparatus 1 of FIG. 1, the plurality of nozzle units 251 respectively correspond to all the band-like regions 71 arranged in the width direction perpendicular to the scanning direction on the printing paper 9, thereby allowing an image to be captured in a very short time by one pass. It is possible to print (record) the whole, but the head unit 23 having a plurality of nozzle units 251 scans a plurality of times while moving relative to the printing paper 9 in the width direction and intermittently. By performing the above, the image may be printed on the entire printing paper 9. In this case, a plurality of ejection position groups 52 respectively corresponding to the plurality of nozzle units 251 may be arranged at intervals in the width direction, like a plurality of irradiation position groups 55a shown in FIG.

  In the plate making apparatus 1b of FIG. 24, each light irradiation unit 411 is provided with a polygon mirror, and the irradiation position on the printing plate 9a of the light beam from the light irradiation unit 411 is within the range of the corresponding strip region 71 in the width direction. Alternatively, it may move in the scanning direction while moving at high speed. Further, in the electrophotographic printing apparatus 1a of FIG. 22, a similar head unit may be provided, and an image may be recorded on the photoreceptor 311 by a similar method. Thus, in the image recording apparatus, when the number of dot output elements included in each of the plurality of drawing mechanisms is one, the position on the object on which dots are drawn by the plurality of drawing mechanisms is set in the scanning direction and By moving in a direction perpendicular to the scanning direction, dots are drawn in a plurality of band-like regions.

  The image recording apparatus is particularly suitable for an application for recording an image on an object to be printed or an object to be used for printing, but may be used for applications other than printing (including plate making).

1 is a diagram illustrating a configuration of a printing apparatus according to a first embodiment. It is a bottom view which shows a head part. It is a figure which shows the flow of the operation | movement which records an image on a target object. It is a figure which shows the several strip | belt-shaped area | region set on printing paper. It is a figure which shows an allocation matrix. It is a figure which shows an allocation matrix. It is a figure which shows the dot drawn on a printing paper. It is a figure which shows the dot drawn on the printing paper by the method of a comparative example. It is a figure which shows the dot drawn on the printing paper by the method of a comparative example. It is a figure which shows the dot drawn on a printing paper. It is a figure which shows the image expressed with the FM screen. It is a figure which shows the other example of an allocation matrix. It is a figure which shows the image expressed with AM screen. It is a figure which shows the further another example of an allocation matrix. It is a figure which shows the further another example of an allocation matrix. It is a figure which shows the dot drawn on a printing paper. It is a bottom view which shows the other example of a head unit. It is a bottom view showing other examples of a head unit. It is a bottom view showing other examples of a head unit. It is a figure which shows the other example of a nozzle unit. It is a figure which shows the nozzle unit in the other example of a printing apparatus. It is a figure for demonstrating the printing operation in a printing apparatus. It is a figure for demonstrating the printing operation in a printing apparatus. It is a figure for demonstrating the printing operation in a printing apparatus. It is a figure for demonstrating the printing operation in a printing apparatus. It is a figure for demonstrating the printing operation in a printing apparatus. It is a figure which shows the structure of the printing apparatus which concerns on 2nd Embodiment. It is a figure which shows a part of head part. It is a figure which shows the structure of the plate making apparatus which concerns on 3rd Embodiment. It is a figure which expand | deploys and shows the outer surface of a holding drum. It is a figure which shows the other example of a plate-making apparatus. It is a figure which shows the several strip | belt-shaped area | region set on a printing plate. It is a figure which shows the other example of the some strip | belt-shaped area | region set on a printing plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Printing apparatus 1b, 1c Plate making apparatus 6, 6a-6d Allocation matrix 9 Printing paper 9a Printing plate 22 Head moving mechanism 29 Paper feed mechanism 31 Photosensitive drum 42 Holding drum 51 Discharge position 53, 54 Irradiation position 71, 71a, 71b Band-shaped area 81 Drawing position 241, 241a, 241b Discharge port 251, 251a, 251b, 251C, 251M Nozzle unit 292 Belt 311 Photoconductor 312, 421 Motor 331 LED array 332 LED
411,411a Light irradiation part 412,412a Light source part 430 Head moving mechanism 711 Overlapping area S12-S14 Step

Claims (16)

A plurality of drawing mechanisms for drawing dots on the object, and scanning that moves relative to the object at least in a predetermined scanning direction with respect to the position on the object on which dots are drawn by the plurality of drawing mechanisms An image recording method for recording an image with an image recording apparatus comprising a mechanism,
A plurality of band-like areas are set on the object that extend in the scanning direction and are arranged in a direction perpendicular to the scanning direction, and in which dots are drawn by the plurality of drawing mechanisms, respectively. The adjacent band-like region partially overlaps in the direction perpendicular to the scanning direction,
The image recording method comprises:
a) generating drawing data for the plurality of drawing mechanisms from image data;
b) drawing dots in the plurality of strip-like regions by the plurality of drawing mechanisms based on the drawing data;
With
In the overlapping area where two adjacent band-like areas overlap, at each drawing position where dots can be drawn, the first drawing operation by the first drawing mechanism for one band-like area of the two band-like areas and the other band-like area One of the second drawing operations by the second drawing mechanism is assigned,
According to the drawing data generated in the step a), the density of the drawing positions assigned to the first drawing operation in the overlapping area decreases as the distance from the non-overlapping area of the one band-like area decreases. A characteristic image recording method. The image recording method according to claim 1,
Each drawing mechanism has a plurality of dot output elements, and each drawing mechanism moves relative to the object once in the scanning direction to draw dots in one band-like region. An image recording method characterized by the above. The image recording method according to claim 2,
An image recording method, wherein each of the plurality of dot output elements has an ejection port that ejects a fine droplet of ink toward the object. The image recording method according to claim 2, wherein:
The image recording method, wherein the plurality of drawing mechanisms respectively correspond to all belt-like regions arranged in a direction perpendicular to the scanning direction on the object. The image recording method according to claim 1,
Each of the plurality of drawing mechanisms has one dot output element;
In the step b), the position on the object on which dots are drawn by the plurality of drawing mechanisms is moved in the scanning direction and in a direction perpendicular to the scanning direction. A drawing mechanism for drawing dots on the object, and a position on the object on which dots are drawn by the drawing mechanism relative to the object in a predetermined scanning direction and a direction perpendicular to the scanning direction An image recording method for recording an image with an image recording apparatus comprising a moving scanning mechanism,
A plurality of band-like areas are set on the object that extend in the scanning direction and are arranged in a direction perpendicular to the scanning direction and in which dots are sequentially drawn by the drawing mechanism, and each band-like area and the scanning direction are set. Partially overlaps the adjacent band-like region in the direction perpendicular to
The image recording method comprises:
a) generating drawing data for the drawing mechanism from image data;
b) sequentially drawing dots in the plurality of band-like regions by the drawing mechanism based on the drawing data;
With
In the step b), the drawing mechanism having a plurality of dot output elements moves relative to the object once in the scanning direction to draw a dot in one band-shaped region,
The first drawing operation by the drawing mechanism for one of the two band-like regions at the drawing position where the dot can be drawn in the overlapping region where two adjacent band-like regions overlap, and the above-mentioned for the other band-like region One of the second drawing operations by the drawing mechanism is assigned,
According to the drawing data generated in the step a), the density of the drawing positions assigned to the first drawing operation in the overlapping area decreases as the distance from the non-overlapping area of the one band-like area decreases. A characteristic image recording method. The image recording method according to any one of claims 1 to 6,
Matrix data indicating a drawing position assigned to the first drawing operation is prepared in advance in the overlapping region where the two belt-like regions overlap,
In the step a), the drawing data is generated using the matrix data. The image recording method according to claim 7, comprising:
The image recording method, wherein the drawing positions assigned to the first drawing operation are scattered while following the density distribution of the drawing positions. The image recording method according to any one of claims 1 to 6,
The drawing position assigned to the first drawing operation in the overlapping area where the two belt-like areas overlap is determined by comparing sequentially generated random numbers with a threshold corresponding to the density of the drawing positions. An image recording method. The image recording method according to any one of claims 1 to 9,
Steps a) and b) are performed for each of the plurality of color components of the image,
An image recording method, wherein positions of the overlapping regions of the plurality of color components in a direction perpendicular to the scanning direction are different. An image recording apparatus for recording an image on an object,
A holding unit for holding an object;
A plurality of drawing mechanisms for drawing dots on the object;
A scanning mechanism that moves a position on the object on which dots are drawn by the plurality of drawing mechanisms relative to the object in at least a predetermined scanning direction;
With
A plurality of band-like areas are set on the object that extend in the scanning direction and are arranged in a direction perpendicular to the scanning direction, and in which dots are drawn by the plurality of drawing mechanisms, respectively. The adjacent band-like region partially overlaps in the direction perpendicular to the scanning direction,
In the overlapping area where two adjacent band-like areas overlap, at each drawing position where dots can be drawn, the first drawing operation by the first drawing mechanism for one band-like area of the two band-like areas and the other band-like area One of the second drawing operations by the second drawing mechanism is assigned,
The image recording apparatus according to claim 1, wherein the density of the drawing positions assigned to the first drawing operation in the overlapping area decreases with increasing distance from the non-overlapping area of the one band-like area. The image recording apparatus according to claim 11,
Each drawing mechanism has a plurality of dot output elements, and each drawing mechanism moves relative to the object once in the scanning direction to draw dots in one band-like region. An image recording apparatus. The image recording apparatus according to claim 12, wherein
Each of the plurality of dot output elements has an ejection port that ejects a minute droplet of ink toward the object. The image recording apparatus according to claim 12 or 13,
The image recording apparatus, wherein the plurality of drawing mechanisms respectively correspond to all belt-like regions arranged in a direction perpendicular to the scanning direction on the object. The image recording apparatus according to claim 11,
Each of the plurality of drawing mechanisms has one dot output element;
When drawing dots in the plurality of belt-like regions, the position on the object on which dots are drawn by the plurality of drawing mechanisms is moved in the scanning direction and in a direction perpendicular to the scanning direction. A characteristic image recording apparatus. An image recording apparatus for recording an image on an object,
A holding unit for holding an object;
A drawing mechanism for drawing dots on the object;
A scanning mechanism that moves a position on the object on which dots are drawn by the drawing mechanism relative to the object in a predetermined scanning direction and a direction perpendicular to the scanning direction;
With
A plurality of band-like areas are set on the object that extend in the scanning direction and are arranged in a direction perpendicular to the scanning direction and in which dots are sequentially drawn by the drawing mechanism, and each band-like area and the scanning direction are set. Partially overlaps the adjacent band-like region in the direction perpendicular to
When performing drawing of dots in the plurality of band-like regions, the drawing mechanism having a plurality of dot output elements moves relative to the object once in the scanning direction, thereby causing one band-like region to be drawn. Dot drawing is done,
The first drawing operation by the drawing mechanism for one of the two band-like regions at the drawing position where the dot can be drawn in the overlapping region where two adjacent band-like regions overlap, and the above-mentioned for the other band-like region One of the second drawing operations by the drawing mechanism is assigned,
The image recording apparatus according to claim 1, wherein the density of the drawing positions assigned to the first drawing operation in the overlapping area decreases with increasing distance from the non-overlapping area of the one band-like area.

Images