JP2009018487A - Liquid discharge method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a printing time, and to print an image of a high image quality. <P>SOLUTION: The liquid discharge method has the step of performing resolution conversion of pixel data corresponding to a first region among a plurality of pixel data which constitute image data of one page to a first resolution, and performing resolution conversion of pixel data corresponding to a second region among the plurality of pixel data to a second resolution different from the first resolution; and the step of forming dots by the first resolution to a region corresponding to the first region on a medium on the basis of the pixel data subjected to the resolution conversion to the first resolution, and forming dots by the second resolution to a region corresponding to the second region on the medium on the basis of the pixel data subjected to the resolution conversion to the second resolution. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid ejection method.

  Nozzle rows (heads) arranged along the transport direction move in the movement direction, and the dot forming operation for ejecting ink from the nozzles during the movement and the transport operation for transporting the medium in the transport direction are repeated alternately. A serial type ink jet printer that completes a printed image is known.

  By one dot forming operation, a band (an image in which dot rows (raster lines) along the moving direction are arranged at intervals of the nozzle pitch) is formed as a band-like image. Band printing is known in which an image is completed by arranging a plurality of bands in the transport direction.

Also, as a method of printing with higher resolution in the transport direction than band printing, after a raster line is formed by one dot formation operation, the medium is transported by a predetermined transport amount, and in the next dot formation operation, the previous dot There has been proposed interlaced printing in which raster lines are formed between raster lines formed by the forming operation, and printing is performed while complementing the raster lines (Patent Document 1).
Japanese Patent Laid-Open No. 7-242025

However, in the interlace printing of Patent Document 1, the medium is finely fed at the beginning and end of printing in order to print with higher resolution in the transport direction than in band printing. That is, since the medium is transported with a transport amount smaller than the predetermined transport amount at the beginning and end of printing, the entire printing time is long. Conversely, band printing has a shorter printing time than interlaced printing, but cannot print images with higher image quality than interlaced printing.
Therefore, the present embodiment aims to reduce the printing time and print a high-quality image.

A main invention for solving the problem is that the pixel data corresponding to a first region of a plurality of pixel data constituting one page of image data is converted into a first resolution, and the plurality of pixel data Converting the pixel data corresponding to the second region to a second resolution different from the first resolution, and the first data on the medium based on the pixel data converted to the first resolution. The second resolution is formed in the region corresponding to the second region on the medium based on the pixel data formed by forming dots at the first resolution in the region corresponding to the region and converting the resolution to the second resolution. Forming dots at
This is a liquid discharge method.

  Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

=== Summary of disclosure ===
At least the following will become apparent from the description of the present specification and the accompanying drawings.

That is, the pixel data corresponding to the first region of the plurality of pixel data constituting one page of image data is converted to a first resolution, and the second region of the plurality of pixel data corresponding to the second region is converted. Converting the pixel data to a second resolution different from the first resolution; and, based on the pixel data converted to the first resolution, an area corresponding to the first area on the medium. Forming dots at a second resolution and forming dots at the second resolution in an area corresponding to the second area on the medium based on the pixel data converted to the second resolution. And realizing a liquid discharging method.
According to such a liquid ejection method, it is possible to shorten the liquid ejection time and obtain a high-quality image.

In this liquid ejection method, a plurality of nozzles from which liquid is ejected, a transport mechanism for transporting a medium in the transport direction, and the plurality of nozzles and the medium are relatively moved in a moving direction intersecting the transport direction. In the liquid ejecting apparatus comprising a moving mechanism, the plurality of nozzles constitute a nozzle row arranged at a constant interval along the transport direction, and relatively moving the nozzle row and the medium in the moving direction, Dots are formed in all the pixels by alternately repeating a dot forming operation for discharging a liquid from the nozzle to form a dot row along the moving direction and a transport operation for transporting the medium in the transport direction. The dot row is formed by another dot forming operation between the dot rows formed at the predetermined intervals in the transport direction by the dot forming operation. An image is formed, and the number of dot rows formed between the dot rows formed at regular intervals in the first region which is an end region in the transport direction of the image is Less than the number of dot rows formed in the second region, which is the central region in the transport direction of the image, between the dot rows formed at regular intervals.
According to such a liquid discharge method, the liquid discharge time can be shortened.

In this liquid ejection method, the medium is transported by a constant transport amount in the transport operation.
According to such a liquid discharge method, the liquid discharge time can be shortened.

In this liquid ejection method, there is a liquid that does not land on the medium among the liquid ejected from the nozzle.
According to such a liquid ejection method, the end region (first region) can be made as narrow as possible.

In this liquid ejection method, the minimum dot interval in the movement direction of the dot row formed in the first area and the minimum dot interval in the movement direction of the dot row formed in the second area are Equality.
According to such a liquid ejection method, the difference in image quality between the first region and the second region can be reduced.

In this liquid ejection method, when the second resolution is higher than the first resolution, the dot generation rate with respect to a predetermined gradation value indicated by the pixel data corresponding to the first region is greater. The dot generation rate for the predetermined gradation value indicated by the pixel data corresponding to the second region is larger.
According to such a liquid ejection method, the density indicated by the dots formed in the first area with respect to the predetermined gradation value is made closer to the density indicated by the dots formed in the second area with respect to the predetermined gradation value. be able to.

In this liquid ejection method, when the second resolution is higher than the first resolution, the dot diameter formed in the first region is the dot formed in the second region. It must be larger than the diameter.
According to such a liquid ejection method, the density indicated by the first area can be made closer to the density indicated by the second area.

In this liquid ejection method, when the second resolution is higher than the first resolution, the resolution conversion step converts all of the plurality of pixel data to the second resolution. If a certain pixel data is not the specific gradation value using a color conversion table in which the specific gradation value and the color conversion data are associated with each other, the identification in any of the vicinity of the pixel data is performed. The color conversion data corresponding to the gradation value of the image is stochastically selected and color-converted, and the pixel data corresponding to the first region of the plurality of pixel data subjected to color conversion is set to the first resolution. Resolution conversion.
According to such a liquid ejection method, color conversion can be performed more accurately.

=== About serial printers ===
Hereinafter, an embodiment will be described by taking a liquid ejecting apparatus as an ink jet printer and taking a serial printer (printer 1) in the ink jet printer as an example.

  FIG. 1 is a block diagram showing the overall configuration of the printer 1 according to this embodiment. 2A is a perspective view of the printer 1, and FIG. 2B is a cross-sectional view of the printer 1. The printer 1 that has received print data from the computer 60 that is an external device controls each unit (conveyance unit 20, carriage unit 30, head unit 40) by the controller 10, and forms an image on the sheet S (medium). Further, the detector group 50 monitors the situation in the printer 1, and the controller 10 controls each unit based on the detection result.

  The controller 10 is a control unit for controlling the printer 1. The interface unit 11 is for transmitting and receiving data between the computer 60 as an external device and the printer 1. The CPU 12 is an arithmetic processing unit for controlling the entire printer 1. The memory 13 is for securing an area for storing the program of the CPU 12 and a work area. The CPU 12 controls each unit by a unit control circuit 14 according to a program stored in the memory 13.

  The transport unit 20 feeds the paper S to a printable position, and transports the paper S by a predetermined transport amount in the transport direction during printing. The paper feed roller 21, the transport motor 22, and the transport roller 23, a platen 24, and a paper discharge roller 25. The paper feed roller 21 is rotated, and the paper S to be printed is sent to the transport roller 23. When the paper detection sensor 44 detects the position of the leading edge of the paper S sent from the paper supply roller 21, the controller 10 rotates the carry roller 23 to position the paper S at the print start position. When the paper S is positioned at the print start position, at least some of the nozzles of the head 41 face the paper S.

  The carriage unit 30 is for moving the head 41 in a direction intersecting the transport direction (hereinafter referred to as a movement direction), and includes a carriage 31 and a carriage motor 32.

  The head unit 40 is for ejecting ink onto the paper S and has a head 41. A plurality of nozzles, which are ink discharge portions, are provided on the lower surface of the head 41, and each nozzle is provided with an ink chamber (not shown) containing ink.

  In the serial printer, the ink is intermittently ejected from the head 41 moving in the moving direction to form dots on the paper, and the paper is relatively moved along the transport direction with respect to the head 41. By alternately repeating the transport process to be moved, dots are formed at positions different from the positions of the dots formed by the previous dot formation process, and the image is completed.

<Nozzle surface>
FIG. 3A is a diagram illustrating a nozzle arrangement on the lower surface of the head 41. Four nozzle rows along the transport direction are formed on the lower surface of the head 41, and the black ink nozzle row K, the cyan ink nozzle row C, and the like in order from the left side in the movement direction (left side when viewed from the lower surface of the head 41). A magenta ink nozzle row M and a yellow ink nozzle row Y are provided.

  Each nozzle row includes 800 nozzles, and the 800 nozzles are aligned at a constant interval k · D in the transport direction. In each nozzle row, a lower number is assigned to the nozzle on the downstream side in the transport direction (# i = 1 to 800). D of the nozzle pitch k · D is the minimum dot pitch (minimum interval between dots formed on the paper S) in the transport direction, and k is an integer of 1 or more. In the present embodiment, since the nozzle pitch k · D is 800 dpi and the minimum dot pitch D in the transport direction is 3200 dpi, k = 4.

  FIG. 3B is a diagram illustrating a reference example of the nozzle arrangement. In the nozzle row of the present embodiment, the nozzles are arranged at a high density (800 dpi) in the transport direction. However, the size of the nozzle pitch may be limited by manufacturing problems. Therefore, as shown in FIG. 3B, when the minimum nozzle pitch D1 that can be manufactured is 200 dpi, the nozzle rows (N1 to N4) in the four rows are shifted at equal intervals D (800 dpi) in the transport direction, thereby reducing the nozzles. Can be arranged at high density in the transport direction.

=== About interlaced printing ===
Assume that the printer 1 of the present embodiment performs printing by an interlace printing method. In interlaced printing, dots are formed differently at the beginning (front end printing) and end (rear end printing) of printing and at intermediate printing (normal printing). Therefore, first, normal printing will be described.

<Normal printing>
FIG. 4 is an explanatory diagram of normal printing. Hereinafter, for convenience of explanation, only one nozzle row is shown, and the number of nozzles in the nozzle row (eight) is also reduced. Assume that ink is ejected from all usable nozzles. Although the head 41 (nozzle row) is illustrated as moving in the transport direction, the sheet S is actually transported in the transport direction with respect to the head 41. In FIG. The positional relationship is shown. For the sake of explanation, the pixels arranged in the direction corresponding to the moving direction are referred to as “rows”, and the pixels on the downstream side in the transport direction are set to lower numbered rows.

  In normal printing of interlaced printing, a dot row (raster line) along the moving direction is formed by a single dot forming operation (pass) in the moving direction of the head 41, and the paper S is conveyed in a certain direction in the conveying direction. After transporting by the amount F, a raster line is formed again by moving the head 41. At that time, the sheet S is transported so that the raster line is formed immediately above (downstream side) the raster line recorded in the immediately preceding pass.

  For example, as shown in FIG. 4, in pass n + 1, a raster line is formed at the pixel (L28) in the 28th row by nozzle # 7, and a raster line is formed at the pixel (L32) in the 32nd row by nozzle # 8. Suppose that In the next pass n + 2, the raster line is formed at the pixel (L31) in the 31st row immediately downstream of the pixel in the 32nd row by the nozzle # 6. Is done.

  That is, in normal printing, a raster line is formed in another pass between raster lines recorded in a certain pass, and printing is performed while complementing between the raster lines. Therefore, raster lines can be formed at a higher density in the transport direction than the nozzle pitch k · D, and the print resolution in the transport direction can be increased. In addition, since raster lines adjacent in the transport direction are formed by different nozzles, the influence of wrinkles unique to each nozzle, variations in nozzle pitch, and the like are alleviated, and high-quality images can be obtained.

  In order to realize such interlaced printing, the following conditions are required. First, (1) the number of nozzles N (integer) that can eject ink is relatively prime to k (nozzle pitch k · D). (2) The transport amount F is set to N · D. The number N of nozzles that can eject ink is not necessarily the number of nozzles included in the nozzle row. For example, in FIG. 4, the number of nozzles included in the nozzle row is 8, but in this embodiment, the nozzle pitch is 4 · D (k = 4). Therefore, in order to satisfy the above condition, 7 nozzles are used. Are usable nozzles (N = 7, # 2 to # 8). The constant transport amount F of the paper S is F = 7 · D.

  Further, since the nozzle pitch is 4 · D, three raster lines are formed in another three passes between the raster ins formed in one pass. In this embodiment, since the nozzle pitch k · D is set to 800 dpi (1/800 inch), the raster line interval (minimum dot pitch D) is 3200 dpi (1/3200 inch) in the normal printing region where normal printing is performed. Become. That is, the resolution in the transport direction in the normal printing area is 3200 dpi.

<Front / rear end printing of comparative example>
First, after showing front / rear end printing of a comparative example, front / rear end printing of the present embodiment will be described.

  FIG. 5 is an explanatory diagram of leading edge / rear edge printing of the first comparative example. During front-end / rear-end printing in the first comparative example, the paper S is transported with a transport amount (1 · D or 2 · D) smaller than the transport amount (7 · D) of the paper S during normal printing. Also, the nozzles used are irregular, and there are also passes that are printed with a smaller number of nozzles than the number of nozzles (7) during normal printing. In FIG. 5, the first five passes are leading edge printing, and the last five passes are trailing edge printing.

  If the paper S is transported at the beginning of printing by the same transport amount F (= 7 · D) as in normal printing, the area between the raster lines on the downstream side formed in the first pass of printing. In the next pass, (the front end portion of the paper S) passes under the head 41 and cannot face the nozzle. Similarly, if the paper S is transported at the end of printing with the same transport amount F (= 7 · D) as in normal printing, the area between the raster lines (paper S) formed in the pass at the end of printing. The rear end) cannot face the nozzle in the next pass. Therefore, in the leading edge / rear edge printing of the first comparative example, printing is performed while the paper S is finely fed.

  As a result, the normal printing area (second area / center) is also used in the leading edge printing area (corresponding to the first area / edge area) where the leading edge printing is performed and the trailing edge printing area where the trailing edge printing (first area) is performed. As in the case of (corresponding to the area), the raster lines formed in one pass are completely complemented. That is, the raster lines of the front end print area and the rear end print area of the first comparative example are continuously arranged in the transport direction at an interval of 3200 dpi, and the print resolution in the transport direction is 3200 dpi.

  That is, in the leading edge / rear edge printing of the first comparative example, the paper S is finely fed in order to print at the same printing resolution as that of the normal printing. Therefore, the printing time per unit area is longer in the front end / rear end printing of the first comparative example than in the normal printing, and when the front end / rear end printing of the first comparative example is performed, the entire printing time is longer. End up.

  FIG. 6 is an explanatory diagram of leading edge printing of the second comparative example. As described above, if the paper S is transported at the beginning of printing by the same transport amount F (= 7 · D) as that in normal printing, it is between the raster lines on the downstream side formed in the first pass of printing. Is not completely complemented. Therefore, in the first pass of printing in the second comparative example, printing is performed using only some of the nozzles on the upstream side of the nozzle row, and printing is performed by gradually increasing the number of nozzles used.

  As shown in FIG. 6, in pass 1, two raster lines are formed using only the two upstream nozzles (# 7 and # 8). Next, in pass 2, four raster lines are formed using four nozzles (# 5 to # 8) on the upstream side. At this time, raster lines (L2 and L6) are formed in pass 2 immediately downstream of the two raster lines (L3 and L7) formed in pass 1. In pass 3, six nozzles (# 3 to # 8) on the upstream side are used to form six raster lines. In pass 4, seven nozzles are used as in normal printing. (# 2 to # 8). As a result, three raster lines are formed between the two raster lines (L3 and L7) formed in pass 1, and the raster lines are continuously formed at an interval of 3200 dpi in the transport direction. In FIG. 6, pass 1 to pass 3 are leading edge printing, and pass 4 to 7 nozzles are used for normal printing.

  In other words, in the first pass of printing, only raster lines that are partially upstream are used to form only raster lines that are completely complemented between the raster lines in subsequent passes. In the pass at the end of printing, conversely, only some of the nozzles on the downstream side are used, and the number of nozzles used is gradually reduced (not shown).

  As described above, in the front-end / rear-end printing of the second comparative example, the paper S is transported by the same transport amount F (7 · D) as in normal printing, but the number of raster lines formed in one pass is normal. Less than printing. Therefore, the printing time per unit area is longer in the front and rear end printing of the second comparative example than in normal printing, and the whole printing time is longer when the front and rear end printing of the second comparative example is performed. End up.

  FIG. 7A is a schematic diagram of leading edge printing of the first comparative example, and FIG. 7B is a schematic diagram of leading edge printing of the second comparative example. In the first comparative example, fine feed is performed, and in the second comparative example, some of the upstream nozzles are used. As described above, in the front-end / rear-end printing of the comparative example, in order to make the printing resolution (3200 dpi) in the transport direction equal to that of normal printing, printing is performed by finely feeding or reducing the number of nozzles. It takes a long time. Therefore, an object of the present embodiment is to shorten the printing time.

<Front / Rear end printing of this embodiment>
FIG. 8 is a diagram illustrating front / rear end printing and normal printing according to the present embodiment. In the present embodiment, a method for complementing raster lines for leading and trailing edges, and a method for complementing raster lines for regular printing, so that the printing time per unit area for leading and trailing edges is the same as that for regular printing. Make them different.

  As shown in FIG. 8, in the front end printing of this embodiment, seven raster lines are formed by using the same seven nozzles as in normal printing in pass 1. Thereafter, the paper S is transported by the same transport amount F (= 7 · D) as in normal printing. Similarly, after pass 2, printing is performed by alternately repeating a raster line forming operation using seven nozzles and a transport operation for transporting the paper S with a transport amount F (= 7 · D).

  As a result, when looking between the raster lines formed in pass 1, no raster line is formed between the first row L1 and the fifth row L5. One raster line is formed between the 5th line L5 and the 9th line L9, and between the 9th line L9 and the 13th line L13, and between the 13th line L13 and the 17th line L17, Two raster lines are formed between the 17th line L17 and the 21st line L21. Three raster lines are formed between the 21st row L21 and the 25th row L25. In the present embodiment, the area from the first line L1 to the twentieth line L20 in which the raster lines are not completely complemented is defined as the leading edge print area.

  That is, in the leading edge printing region of this embodiment, the number of raster lines (from 0 to 2) formed between the raster lines formed at every nozzle pitch (k · D = 800 dpi) in one pass is normal. In the print area, the number is less than the number of raster lines (three lines) formed between raster lines formed at every nozzle pitch. In other words, the print resolution in the transport direction in the leading print area is lower than the print resolution in the transport direction in the normal print area.

  For example, one dot is formed in four pixels arranged in the transport direction from the first row L1 to the fourth row L4. Since the size of one pixel in the carrying direction is 3200 dpi, it is the same as that one dot is formed on a pixel (800 dpi) having a size of four pixels arranged in the carrying direction. That is, it can be said that the print resolution in the transport direction of the area of the paper S corresponding to the pixels in the first line L1 to the fourth line L4 is 800 dpi.

  Two dots are formed in each of the four pixels arranged in the transport direction from the fifth row L5 to the eighth row L8 and the four pixels from the ninth row L9 to the twelfth row L12. That is, it is the same as that two dots are formed on a pixel (800 dpi) having a size of four pixels arranged in the transport direction. That is, it can be said that the print resolution in the transport direction of the area of the paper S corresponding to the pixels in the fifth line L5 to the twelfth line L12 is 1600 dpi.

  Furthermore, three dots are formed in each of the four pixels arranged in the transport direction from the 13th row L13 to the 16th row L16 and the 4 pixels from the 17th row L17 to the 20th row L20. That is, it is the same as that three dots are formed on a pixel (800 dpi) having a size corresponding to four pixels, and in the transport direction of the area of the paper S corresponding to the pixels on the 13th row L13 to the 20th row L20. It can be said that the printing resolution is 2400 dpi.

  In the trailing edge printing area, the number of raster lines formed between raster lines formed in one pass is equal to the number of raster lines formed between raster lines formed in one pass in the normal printing area. The number of lines (3 lines) is smaller, and the printing resolution in the conveyance direction for trailing edge printing is lower than the printing resolution in the conveyance direction for normal printing.

  In FIG. 8, the 41st line L41 to the 60th line L60 are defined as the trailing edge print area. The print resolution in the transport direction of the area of the paper S corresponding to the 41st line L41 to the 48th line L48, in which two raster lines are formed between the raster lines formed in the final pass 6, is 2400 dpi, 49 lines. The print resolution in the transport direction of the area of the paper S corresponding to the 56th line L56 from the eyes L49 is 1600 dpi, and the print resolution in the transport direction of the area of the paper S corresponding to the 57th line L57 to the 60th line L60 is 800 dpi. .

  In summary, the leading edge and trailing edge printing of the present embodiment uses the same number of nozzles (7) as that in normal printing, and transports the paper S with the same transport amount F (= 7 · D) as in normal printing. The printing time per unit area is faster than that of the comparative example. However, in the comparative example, the same number of raster lines as in normal printing is formed between raster lines formed at every nozzle pitch, whereas in this embodiment, between raster lines formed at every nozzle pitch. The number of raster lines to be formed is smaller than that in normal printing. In other words, the leading edge / rear edge printing resolution in the transport direction (corresponding to the first resolution) of the present embodiment is lower than the printing resolution in the transport direction of normal printing (corresponding to the second resolution). The printing time per unit area for edge printing is set equal to the printing time per unit area for normal printing. As a result, in this embodiment, the printing time can be shortened compared to the comparative example.

  In this embodiment, the print resolution in the transport direction for leading / rear end printing is lower than that for normal printing, but the print resolution (3200 dpi) in the moving direction for leading / rear end printing is equal to that for normal printing. If the print resolution in the moving direction of the leading edge / rear edge printing is also lower than that in the normal printing, the movement of the head 41 in the moving direction can be made faster, so that the printing time can be further shortened. However, as in the present embodiment, lowering only the print resolution in the transport direction of the leading edge / rear edge printing compared to normal printing can reduce the difference in image quality between the leading edge / rear edge printing area and the normal printing area. it can.

  In the nozzle row of the head 41 of this embodiment, the nozzles are densely arranged (800 dpi), and the print resolution in the normal print area is relatively high, so the print resolution in the leading and trailing print areas is higher than that in the normal print area. Even if it is low, image quality degradation is not noticeable. Further, the minimum dot interval D (= 3200 dpi) formed in the paper S in the transport direction is also narrow. In FIG. 8, for the sake of explanation, the dots are drawn side by side at intervals of 3200 dpi (= 0.008 mm) without overlapping each other, but the dots overlap each other when the actually formed dot diameter is assumed. Printed. Therefore, even if the printing resolution of the leading and trailing printing areas is set lower than that of the normal printing area, it is possible to prevent a large gap from being formed between raster lines (white streaks are generated).

  Furthermore, since the leading edge / rear edge printing area is narrower than the normal printing area, even if the printing resolution of the leading edge / rear edge printing area is lower than the printing resolution of the normal printing area, it is difficult for a person to visually recognize. In the present embodiment, an area corresponding to the pixels from the first line L1 to the twentieth line L20 is defined as the leading edge print area. Since the length of one pixel in the carrying direction is 3200 dpi, the leading edge printing area is 3200 dpi × 20 = 1/160 inch = 0.16 mm. For example, when printing the longer side (297 mm) of A4 size paper along the transport direction, 0.05% ((0.16 / 297) × 100 (%)) of A4 size paper is leading edge printed. Corresponds to the area.

  9A is an explanatory diagram for printing an image from the leading edge of the paper S, and FIG. 9B is an explanatory diagram for printing an image on the center of the paper S. FIG. 9A, when printing is performed from the leading edge to the trailing edge of the paper S, the printing resolution on the leading edge side and the trailing edge side of the paper S is lower than the printing resolution of the central portion of the paper S. In FIG. 9B, since an image (shaded area) is printed at the center of the sheet S, the upstream end and the downstream end of the image correspond to the leading and trailing end printing areas. 9B, the low-resolution area is located at the center of the paper S, whereas the low-resolution area is located at the leading and trailing edges of the paper S in FIG. 9A. That is, in FIG. 9A, since the print resolution of the region that is difficult for humans to visually recognize (the leading edge and the trailing edge of the paper) is low, the image quality difference between the leading edge and trailing edge printing area and the normal printing area is lower than that in FIG. Can be said to be inconspicuous.

If the nozzles are arranged at a higher density than the nozzle row of the head 41 of this embodiment, and the nozzle pitch in the transport direction is 1600 dpi, for example, the print resolution in the front and rear end print areas is 1600 dpi, 3200 dpi, and 4800 dpi. The print resolution of the normal print area is 6400 dpi, and it is possible to print with higher image quality.
Further, in this embodiment, since the number of raster lines formed between the raster lines formed at every nozzle pitch in the normal printing region is three, assuming that the nozzle pitch of the nozzle row is 1600 dpi, the leading edge / rear edge The lowest print resolution in the print area is 1600 dpi, and the print resolution in the normal print area is 6400 dpi. Here, for example, if the number of raster lines formed between the raster lines formed every nozzle pitch in the normal print area is two, the print resolution of the normal print area is 4800 dpi, and the leading and trailing end print areas Since the difference between the lowest print resolution (1600 dpi) and the print resolution of the normal print area (4800 dpi) is small, the difference in image quality between the leading and trailing print areas and the normal print area becomes inconspicuous.

=== About Print Data Creation Processing ===
In the present embodiment, the print resolution differs between the front / rear end print area and the normal print area. Also, the printing resolution varies depending on the area in the leading edge / rear edge printing area. That is, even in the case of an image to be printed on one sheet of paper S (one page), the print resolution varies depending on the area. For this reason, when converting image data transmitted from application software of a computer into print data, it is necessary to convert the resolution for each region having a different print resolution. Of the above-described leading and trailing edge printing areas, an area where the resolution in the conveyance direction is 800 dpi is “800 dpi printing area”, an area where the resolution in the conveyance direction is 1600 dpi is “1600 dpi area”, and the resolution in the conveyance direction is 2400 dpi. This area is referred to as “2400 dpi area”.

  Note that the image data is composed of pixel data, and dots may or may not be formed in each pixel based on the pixel data. If the image data is data with 256 gradations, one pixel is expressed with 256 gradations, and one pixel data is 8-bit data (2 8 = 256). If the image data is data of two gradations, one pixel is expressed by two gradations, one pixel data is 1-bit data, and the pixel data indicates whether or not to form a dot on the pixel. become. Note that print data transmitted from the computer to the printer is created according to a printer driver stored in the memory of the computer. That is, the printer driver is a program for causing the computer 60 to create print data and sending the print data to the printer 1.

<Print data creation processing: first example>
FIG. 10 is a flowchart of a first example of print data creation processing. When receiving image data from the application software, the printer driver determines for each pixel data which print resolution area corresponds to the data. Then, resolution conversion processing is performed for each area (800 dpi print area, 1600 dpi print area, 2400 dpi print area, normal print area).

  First, the printer driver receives image data from application software (S001). The printer driver acquires the input resolution x of the received image data (S002). In this embodiment, the resolution of the image data from the application software is “conveyance direction × movement direction = 400 dpi × 400 dpi”.

  Then, it is determined whether or not certain pixel data in the image data belongs to the normal print area (S003). If the pixel data belongs to the normal printing area (YES), the resolution of the pixel data is converted to “conveyance direction × movement direction = 3200 dpi × 3200 dpi” (S004).

  FIG. 11A is an image diagram of resolution conversion of pixel data belonging to the normal print area. The resolution of the image data from the application software is “400 dpi × 400 dpi”, and data is provided for each area (pixel) of 400 dpi × 400 dpi. Since the print resolution of the normal print area is “3200 dpi × 3200 dpi”, one pixel data is converted to a resolution of 8 times (= 3200/400) in the transport direction and 8 times (= 3200/400) in the movement direction. Convert to the resolution.

  That is, as shown in FIG. 11A, a pixel of 400 dpi × 400 dpi is divided into 64 (8 × 8 divisions) and converted into pixels matching the print resolution of 3200 dpi × 3200 dpi. Here, for the sake of explanation, the pixel in the image data from the application software is referred to as “image pixel”, and the pixel that matches the print resolution is referred to as “print pixel”. The data (tone value) indicated by the upper left image pixel data in FIG. 11A is “A”, and all the data indicated by the 64 print pixel data corresponding to the positions of the upper left image pixels is also “A”. To do. Note that the print pixel data (A) at this time is 256-gradation data represented by an RGB space.

  Next, a color conversion process is performed on the print pixel data of the normal print area whose resolution has been converted (S005). The color conversion process is a process of converting data represented by the RGB space into YMCK data represented by the YMCK space corresponding to the ink of the printer 1. This color conversion process is performed by the printer driver referring to a color conversion table in which the gradation value of RGB data is associated with the gradation value of YMCK data.

  Thereafter, halftone processing (S006) is performed. The halftone process is a process of converting high gradation number data (256 gradations) into gradation number data that can be formed by the printer 1. If the printer 1 of this embodiment forms dots of one type, one pixel can be expressed in two ways: “form dots” or “do not form dots”. That is, in the halftone process, 256 gradation print pixel data is converted into two gradation print pixel data.

  The image pixel data that does not belong to the normal printing area (S003 → NO) is data that belongs to the leading edge / rear edge printing area. As described above, since printing is performed at three types (800 dpi, 1600 dpi, 2400 dpi) in the leading edge / rear edge printing area, the image pixel data belonging to the leading edge / rear edge printing area belongs to any of the three types of printing areas. It is determined whether it is data (S007, S011).

  FIG. 11B is an image diagram of resolution conversion of pixel data belonging to the 800 dpi print area. When a certain image pixel data belongs to the 800 dpi print area (S007 → YES), the image pixel data is converted into a double resolution (= 800/400) in the transport direction, and 8 times (= 3200/400) in the movement direction. ) Resolution (S008). As a result, a 400 dpi × 400 dpi area (image pixel) is divided into 16 areas of 800 dpi × 3200 dpi (print pixels). Thereafter, the print pixel data belonging to the 800 dpi print area is subjected to color conversion processing (S009), and halftone processing (S010) is performed.

  Similarly, image pixel data (S011 → YES) belonging to the 1600 dpi print area is converted to a resolution of 4 times (= 1600/400) in the transport direction and converted to a resolution of 8 times (= 3200/400) in the movement direction. (S012). Then, color conversion processing is performed on print pixel data belonging to the 1600 dpi print area (S013), and halftone processing is performed (S014). The image pixel data belonging to the 2400 dpi print area (S011 → NO) is converted to a resolution of 6 times (= 2400/400) in the transport direction and converted to an resolution of 8 times (= 3200/400) in the movement direction. (S015). Thereafter, the print pixel data belonging to the 2400 dpi print area is subjected to color conversion processing (S016), and halftone processing (S017) is performed.

  In this way, the print pixel data that has undergone resolution conversion, color conversion, and halftone processing for each print region is rasterized (S018), and is sent to the printer 1 together with command data (conveyance amount, etc.) (S019). . The printer 1 forms dots on each pixel or does not form dots based on the print pixel data. Thus, an image composed of dots is completed. The rasterizing process is a process of rearranging the matrix-like print data for each print pixel data in the order of data to be transferred to the printer 1.

  By the way, in the present embodiment, not only resolution conversion but also halftone processing is performed for each print region, and different halftone processing is performed for each print region. Hereinafter, halftone processing will be described.

  FIG. 12A is an explanatory diagram of a dot generation rate table. The horizontal axis of the graph represents the gradation value, the left side of the vertical axis is the dot generation rate (0 to 100%), and the right side of the vertical axis is the level data. The dot generation rate is the rate at which dots are formed in pixels in a unit area when the gradation value of the unit area is constant. For example, when the unit area is composed of 16 × 16 pixels, the gradation value of all print pixel data in the unit area is a constant value, and n dots are formed in the unit area, the gradation value The dot generation rate is {n / (16 × 16)} × 100 (%). The level data refers to data representing the dot generation rate in 256 gradations of values 0 to 255.

  FIG. 12B is a diagram showing a state of dot on / off determination by the dither method. The printer driver derives level data (d) corresponding to the gradation value (gr) indicated by the print pixel from the dot generation rate table, and compares the level data (d) with the threshold value of the dither matrix corresponding to the pixel. . If the level data value is larger than the threshold value, a dot is formed. If the threshold value value is larger than the level data value, no dot is formed.

  In the present embodiment, different halftone processing is performed for each printing area. This is because, in this embodiment, the size of dots that can be formed is one type, so if the same dot generation rate is set for the same gradation value, the area with higher print resolution is within the unit area. This is because the number of dots that can be formed increases, resulting in dark printing. That is, even if the print resolution is different, if the same dot generation rate is set for the same gradation value, the leading edge / rear edge printing area is printed lighter than the normal printing area. Therefore, even in regions with different print resolutions, if the tone values are the same, the dot generation rate of the low-resolution print region can be increased so that the image can be viewed at the same density when viewed macroscopically. The dot generation rate of the resolution printing area is set higher.

  FIG. 13 is a diagram illustrating a difference in dot generation rate due to a difference in print area. Here, the unit area is set to “conveyance direction × movement direction = 800 dpi × 800 dpi”, and the size of the print pixel in each print area is also shown in the drawing. In the 800 dpi print area, the size of one pixel is “conveyance direction × movement direction = 800 dpi × 3200 dpi”, so the number of print pixels in the unit area is four. In the 1600 dpi print area, the number of print pixels in the unit area is 8, in the 2400 dpi print area, the number of pixels in the unit area is 12, and in the normal print area, the number of print pixels in the unit area is 16. is there.

  In the figure, four dots are formed in all the unit areas in order to equalize the density indicated by the unit areas regardless of the printing area (printing resolution). In the normal print area, dots are formed in 4 print pixels out of 16 print pixels in the unit area, and no dots are formed in the remaining 12 print pixels. That is, the dot generation rate is 25% (= (4/16) × 100). In the 2400 dpi printing area, the dot generation rate is 33% (= (4/12) × 100), and in the 1600 dpi printing area, the dot generation rate is 50% (= (4/8) × 100), and the 800 dpi printing is performed. In the area, the dot generation rate is 100%.

  As described above, in order to express the same density as the high print resolution even at a low print resolution, it is necessary to increase the dot generation rate in the unit area with respect to the predetermined gradation value in the area where the print resolution is low. . For this purpose, for example, a dot generation rate table (FIG. 12A) for gradation values and a dither matrix (FIG. 12B) used for dot on / off determination may be made different depending on the print region. In addition, since the dot generation rate is determined based on the gradation value indicated by the print pixel data, when the same dot generation rate table is used for normal printing and front / rear end printing, the front / rear end printing area is used. The dot generation rate may be derived by multiplying the gradation value of the print pixel data belonging to the number a and leaving the gradation value of the print pixel data belonging to the normal print area as it is.

  In this way, the leading and trailing edge printing has a higher dot generation rate for the same gradation value than the normal printing, so that the density indicated by the leading and trailing edge printing areas and the normal printing area is equal. When the value is around 255 (solid printing), the dot generation rate approaches 100%, and therefore it is not possible to make a difference between the dot generation rates of the leading and trailing edge printing areas and the normal printing area. However, there is a limit to the amount of ink that permeates and fixes on the paper S. When the nozzle pitch is dense (800 dpi) as in the present embodiment, a large amount of ink is driven in solid printing in the normal printing area. Even so, there is a limit to the density that can be expressed, so there is no significant difference from solid printing in the front and rear printing areas.

  In FIG. 13, the unit area is set to “800 dpi × 800 dpi”. However, since a density difference of 256 gradations must be expressed in the unit area, a larger unit area may be actually set. Further, in FIG. 13, a dot is formed at the center of the print pixel conveyance direction, but this is not limiting, and as shown in FIG. 8, the upstream side and the downstream side of the print pixel depending on the positional relationship between the head 41 and the paper S. In some cases, the dots are formed unevenly.

<Print data creation processing: second example>
FIG. 14 is a flowchart of a second example of the print data creation process. In this second example, the image data received from the application software is once converted in resolution to the maximum print resolution. That is, the image data (400 dpi × 400 dpi) from the application software is converted into the resolution (3200 dpi × 3200 dpi) of the normal print area (S101).

  FIG. 15 is an image diagram of resolution conversion of image data to the highest resolution. One image pixel data is converted to a resolution of 8 times in the transport direction, converted to a resolution of 8 times in the moving direction, and divided into 64 pieces of pixel data (hereinafter referred to as the highest pixel data). Then, color conversion processing is performed on the resolution-converted RGB data (S102).

  Thereafter, it is confirmed whether or not each highest pixel data is data belonging to the normal print area (S103). If the highest pixel data belongs to the normal print area (YES), it is not necessary to match the print resolution, and then halftone processing is performed (S104). If the highest pixel data is not data belonging to the normal print area (NO), it is determined which of the three types of print areas, leading edge / rear edge printing (S105, S108).

  FIG. 16A is an image diagram for converting the resolution of the highest pixel data into print pixel data in an 800 dpi print region. The print resolution of the 800 dpi print area is “conveyance direction × movement direction = 800 dpi × 3200 dpi”. Since the highest pixel data has been converted to a print resolution of the 800 dpi print area with respect to the resolution in the moving direction, the resolution in the transport direction is converted to the print resolution of the 800 dpi print area. As shown in the figure, the four highest pixels arranged in the transport direction are combined into one pixel, and the print resolution in the transport direction is converted to 800 dpi. At this time, a value obtained by averaging the four highest pixel data arranged in the transport direction is set as print pixel data. For example, the average value of the data (A11, A12, A13, and A14) indicated by the upper left four pixels (in the thick frame) of the highest pixel data is the upper left print pixel data A1 of the 800 dpi print area (A1 = ( A11 + A12 + A13 + A14) / 4).

  If the highest pixel data belongs to the 1600 dpi print area (S008 → YES), the data represented by the two pixels arranged in the transport direction in order from the highest pixel data at the upper left is averaged to obtain print pixel data in the 1600 dpi print area.

  FIG. 16B is an image diagram for converting the resolution of the highest pixel data into print pixel data in a 2400 dpi print region. In order to match the resolution of the highest pixel data with the print resolution of the 2400 dpi print area, the resolution in the conveyance direction of the highest pixel data is 3/4 times (= 2400/3200). Specifically, the four highest pixels arranged in the transport direction are converted into three print pixels. For example, the average value A1 of the data (A11, A12) indicated by the two highest pixels at the upper left is the print pixel data A1 at the upper left of the 2400 dpi print area. Similarly, the average value A2 of the data (A12, A13) indicated by the second and third highest pixels from the upper left is the second print pixel data A2 from the upper left of the 2400 dpi print area, and the third and fourth from the upper left. The average value A3 of the data (A13, A14) indicated by the highest pixel is set as the third print pixel data A3 from the upper left of the 2400 dpi print area.

  In this way, the image data (maximum pixel data) converted to the highest resolution is converted to a resolution that matches the resolution of each print area. Then, as in the print data creation process of the first example, halftone processing is performed for each print region so that the dot generation rate for the same gradation value is higher in regions with lower print resolution. The print pixel data subjected to the halftone process is rasterized (S113) and transmitted to the printer 1 together with the command data (S114).

  In this way, even when the print resolution of an image printed on one sheet S (one page) varies from region to region, the image data from the application software can be converted into print data that can be printed by the printer. .

  By the way, in the print data creation process of the second example, first, all image pixel data is converted to the highest gradation value, color-converted, and then converted to a resolution suitable for the print area. By doing so, color conversion can be performed more accurately than in the print data creation process of the first example. The reason is shown below.

  FIG. 16C is a diagram showing a color conversion table. A color conversion table for converting RGB data (gradation values) into YMCK data (gradation values) has a huge amount of data when it is attempted to hold YMCK data corresponding to all RGB gradation values. For example, when the RGB data has 256 gradation values, if the color conversion table attempts to hold YMCK data corresponding to all RGB gradation values, YMCK data corresponding to 256 × 256 × 256 RGB data, respectively. All must be retained. Therefore, normally, only YMCK data (color conversion data) corresponding to RGB discrete gradation values (specific gradation values) is retained. For example, the color conversion table holds YMCK data corresponding to 8 × 8 × 8 RGB data every 32 gradations.

  Then, the color conversion table may not hold data that matches the RGB data (point A) indicated by certain image pixel data. In this case, one of the data (a to h) in the vicinity of the point A indicated by certain image pixel data is YMCK data of the certain image pixel data. That is, RGB data cannot be accurately converted to YMCK data in image pixel units.

  In view of this, the shift generated during color conversion for each pixel is eliminated in an area (unit region) larger than the pixel. For example, when the RGB data indicated by the image pixel data in the unit area is a point A, a certain image pixel data in the unit area is color-converted based on the point a closest to the point A (data lighter than the point A). Then, the RGB data indicated by the other image pixel data in the unit area is color-converted based on the point g farthest from the point A (data darker than the point A). As a result, RGB shades indicated by the unit area can be expressed by YMCK by the unit area including the image pixels. For this reason, when color conversion is performed using a large number of image pixel data, a shift that occurs during color conversion for each pixel can be reliably eliminated, and color conversion can be performed accurately. That is, color conversion can be performed more accurately by performing color conversion after converting the image pixel to the highest resolution (after conversion to the highest pixel data) as in the second example.

  For example, in the received image data, it is assumed that the RGB data of a certain image pixel data is point A data (tone value). In the print data creation process of the second example, 64 pieces of RGB data that are the same as the data of point A are created by the resolution conversion to the highest resolution in S101, and color conversion processing is performed on each of the 64 RGB data. Become. Then, by the color conversion process, the 64 RGB data are respectively converted to the point a in FIG. 16C so that the unit area composed of the 64 pixels (the highest pixel) looks macroscopically. To YMCK data corresponding to any one of .about.h. On the other hand, in the first example, for example, S009, the 16 RGB data are each subjected to color conversion processing to YMCK data so that the unit area having only 16 pixels has a hue close to the point A. Comparing the second example and the first example, the color shift after the color conversion process can be reduced in the second example that can express the point A that is an intermediate gradation value of many pixels.

  Also, when reducing the resolution of the color-converted maximum pixel data, the print area should not be damaged so as not to destroy the hue represented by a large number of maximum pixel data (displacement caused by each pixel). It is necessary to reduce the resolution to match the resolution. Therefore, in the second example, as described above, when the resolution is reduced, one of the plurality of highest pixel data is not extracted, but the plurality of highest pixel data is averaged. Values are used (FIGS. 16A and 16B). In this way, the hue (RGB data) indicated by the image data from the application software can be printed and expressed using YMCK ink.

=== Second Embodiment ===
FIG. 17 is a diagram illustrating a state in which characters and photographs are printed on one sheet of paper S. In the above-described embodiment, the printing resolution of the leading and trailing printing areas is set lower than that of the normal printing area in one printing paper S. On the other hand, in the second embodiment, even in the single printing paper S, the printing resolution is changed if the type of image to be printed (characters, graphics, etc.) is different.

  In FIG. 17, two types of images of characters and photographs are printed on one print sheet S (in one page of print image). In such a case, in the second embodiment, the print resolution of an area where characters are printed (hereinafter, character print area T) is higher than the print resolution of an area where photos are printed (hereinafter, photo print area P). To do. This is because “characters” need to have a smoother character outline than “photos”, so that high-quality images cannot be obtained unless printing is performed at the highest possible resolution. On the other hand, even if the print resolution of “photo” is not set as high as the print resolution of “character”, a high-quality image can be obtained if printing is performed at a certain print resolution. In addition, for example, even if the printing resolution of the solid printing area is further lower than the printing resolution of the photo printing area, the problem of image quality deterioration does not occur as long as the ink ejection amount is the same.

  Temporarily, the printing resolution in one printing paper S is made constant regardless of the type of image. Then, for example, when it is desired to print characters with high image quality, the photo printing area is also printed at a higher resolution than necessary, and the printing time is increased. On the other hand, if the printing resolution of the character printing area is set to a low resolution in accordance with the printing resolution of the photo printing area, the printing time is shortened, but the image quality of the character is deteriorated.

  Therefore, in the second embodiment, when printing characters and photos on one printing sheet, for example, “characters” are printed by an interlaced printing method, and “photographs” are printed by a band printing method. As a result, the character image is printed so that the resolution in the conveyance direction is higher than that of the photographic image, so that a high-quality image is obtained, and the photographic image has a lower printing resolution than the character image, but the printing time is shortened as much as possible. can do.

  That is, in the second embodiment, when a plurality of types of images are included in one print image, printing is performed at a print resolution suitable for each image. As a result, it is possible to shorten the printing time as much as possible and obtain a high-quality image.

  In the above-described embodiment, only the print resolution in the transport direction is changed between the front and rear end print areas and the normal print area. However, in the second embodiment, the transport direction and the movement direction for each type of image. Both print resolutions may be changed, or one of the print resolutions in the transport direction and the movement direction may be changed.

=== Other Embodiments ===
Each of the above embodiments has been described mainly with respect to a printing system having an ink jet printer, but includes a disclosure of a printing method and the like. The above-described embodiments are for facilitating understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About dot generation rate>
In the above-described embodiment, the leading edge / rear edge printing has a lower printing resolution than the normal printing, and the size of the formed dots is uniform. Printing has a higher dot generation rate than normal printing. In this way, even if the printing resolution is different, the same density can be visually recognized. However, the present invention is not limited to this.

  For example, in the above-described embodiment, only one type of dot is formed from the printer 1, but the size of the formed dot may be changed between normal printing and leading edge / rear edge printing. Areas with different print resolutions by making the dot diameter (hereinafter referred to as the second dot diameter) formed in the leading and trailing end printing areas larger than the dot diameter (hereinafter referred to as the first dot diameter) formed in the normal printing area Thus, even if the dot generation rate for the gradation value is not changed, printing can be performed so as to be visually recognized at the same density.

For this purpose, as shown in FIG. 18A, the drive signals to be used may be changed in the normal printing area and the leading and trailing edge printing areas. Ink is ejected by applying a drive pulse included in the drive signal to the drive element. For example, the driving signal C used in the normal printing area has only one driving pulse W1, whereas the driving signal A used in the leading and trailing printing areas has two driving pulses W1 and W2. By having it, the second dot diameter (ink discharge amount) formed in the leading / rear end printing region can be made larger than the first dot diameter (ink discharge amount) formed in the normal printing region.
Further, if the voltage amount V2 of the drive pulse W3 of the drive signal B used in the leading / rear end printing region is larger than the voltage amount V1 of the drive pulse W1 of the drive signal C used in the normal printing region, the first The two dot diameter can be made larger than the first dot diameter. That is, when printing one page image, different drive signals are used depending on the region.

  FIG. 18B is a diagram showing a difference in dot generation rate when two types of dots can be formed. In the above-described embodiment, the dot generation rate for the same gradation value is changed for each print area, but the type (combination) of dots for the same gradation value may be changed for each print area. For this reason, for example, large dots start to be formed from a gradation value of 30 in the leading and trailing edge printing areas (areas with low printing resolution), whereas in the normal printing area (area with high printing resolution) Large dots may begin to be formed from a value of 40. In this case, for example, when printing is performed with a gradation value of 40, only small dots are formed in the normal printing area, whereas small dots and large dots are formed in the leading and trailing printing areas. In this way, printing can be performed so that even areas with different print resolutions are visually recognized with the same density.

<Borderless printing>
FIG. 19 is a diagram illustrating a state of borderless printing. In borderless printing, in order to print so that there is no margin at the edge of the paper, the area where ink is ejected is set larger than the paper, and printing is performed in a state of protruding from the paper. By doing so, it is possible to print without margins regardless of variations in paper size and paper position. An area where ink (liquid that does not land on the medium) is discarded outside the edge of the paper is defined as a leakage area (shaded area), and the leading edge printing area can be reduced by the amount of the leakage area. That is, by performing borderless printing, compared with bordered printing (FIG. 9A), it is possible to narrow a region having a low printing resolution, and therefore it is possible to print with higher image quality.

<About line head printer>
In the above-described embodiment, the serial ink jet printer is exemplified as the liquid ejecting apparatus that performs the liquid ejecting method, but the present invention is not limited thereto. For example, you may use the line head printer which has a nozzle row of the paper width length along the direction which cross | intersects the conveyance direction of a medium. In this case, although interlaced printing is not performed, even if it is an image of one page, the size of one pixel is reduced in the high-resolution printing region by changing the printing resolution for each type of image, so that the conveyance speed is increased. In the low resolution printing area, the conveyance speed is increased and the printing time can be shortened.

<About liquid ejection device>
Further, the liquid ejection device is not limited to the ink jet printer and can be applied to various industrial devices. For example, a textile printing device for patterning a fabric, a display manufacturing device such as a color filter manufacturing device or an organic EL display, a DNA chip manufacturing device for manufacturing a DNA chip by applying a solution in which DNA is dissolved in a chip, a circuit board manufacturing The present invention can be applied even to an apparatus or the like.
The liquid discharge method may be a piezo method that discharges liquid by applying voltage to the drive element (piezo element) to expand and contract the ink chamber, or generates bubbles in the nozzle using a heating element. It is also possible to use a thermal method in which liquid is discharged by the bubbles.

  In the above-described embodiment, since the printer driver in the computer 60 performs print data creation processing, a system that combines the printer 1 and the computer 60 is a liquid ejection apparatus. Note that the CPU 52 on the printer 1 side may perform print data creation processing. In this case, the printer 1 alone is a liquid ejection device.

1 is an overall configuration block diagram of a printer according to an embodiment. 2A is a perspective view of the printer, and FIG. 2B is a cross-sectional view of the printer. 3A is a nozzle arrangement diagram of the lower surface of the head, and FIG. 3B is a reference example of the nozzle arrangement. Explanatory drawing of normal printing. Explanatory drawing of front-end | tip end printing of a 1st comparative example. Explanatory drawing of the front end printing of a 2nd comparative example. FIG. 7A is a schematic diagram of leading edge printing of the first comparative example, and FIG. 7B is a schematic diagram of leading edge printing of the second comparative example. The figure which shows the front-end | tip end printing and normal printing of this embodiment. FIG. 9A is an explanatory diagram when an image is printed from the leading edge of the paper, and FIG. 9B is an explanatory diagram when an image is printed at the center of the paper. The flowchart of the 1st example of print data creation processing. 11A is an image diagram of resolution conversion of pixel data belonging to the normal print area, and FIG. 11B is an image diagram of resolution conversion of pixel data belonging to the 800 dpi print area. FIG. 12A is an explanatory diagram of a dot generation rate table, and FIG. 12B is a diagram showing a state of dot on / off determination by the dither method. The figure which shows the difference in the dot generation rate by the difference in a printing area | region. The flowchart of the 2nd example of print data creation processing. The image figure of resolution conversion to the highest resolution of image data. 16A is an image diagram for converting the resolution of the highest pixel data into print pixel data in the 800 dpi print region, FIG. 16B is an image diagram for converting the resolution of the highest pixel data into print pixel data in the 2400 dpi print region, and FIG. 16C is a diagram showing a color conversion table. . The figure which shows 2nd Embodiment. The figure which shows other embodiment. The figure which shows other embodiment.

Explanation of symbols

1 printer,
10 controller, 11 interface unit, 12 CPU, 13 memory,
14 unit control circuit, 20 transport unit, 21 paper feed roller,
22 transport motor, 23 transport roller, 24 platen, 25 discharge roller,
30 Carriage unit, 31 Carriage, 32 Carriage motor,
40 head units, 41 heads, 50 detector groups, 60 computers

Claims (8)

The pixel data corresponding to the first region of the plurality of pixel data constituting the image data of one page is converted into a first resolution, and the pixel data corresponding to the second region of the plurality of pixel data Converting the resolution to a second resolution different from the first resolution;
Based on the pixel data whose resolution has been converted to the first resolution, dots are formed at the first resolution in an area corresponding to the first area on the medium, and the pixels whose resolution has been converted to the second resolution Forming dots at the second resolution in an area corresponding to the second area on the medium based on the data;
A liquid ejection method comprising: The liquid discharge method according to claim 1,
Liquid ejection comprising: a plurality of nozzles from which liquid is ejected; a transport mechanism that transports the medium in the transport direction; and a moving mechanism that relatively moves the plurality of nozzles and the medium in a moving direction that intersects the transport direction. In the apparatus, the plurality of nozzles constitute a nozzle row arranged at regular intervals along the transport direction, and liquid is ejected from the nozzle while the nozzle row and the medium are relatively moved in the movement direction. The dot formation operation in which dots are formed in all pixels by alternately repeating a dot formation operation for forming a dot row along the moving direction and a transport operation in which the medium is transported in the transport direction. An image is formed by forming the dot rows by another dot forming operation between the dot rows formed at regular intervals in the transport direction by the operation. ,
The number of dot rows formed between the dot rows formed at regular intervals in the first region, which is an end region in the transport direction of the image, is a central region in the transport direction of the image. Less than the number of dot rows formed between the dot rows formed at regular intervals in the second region.
Liquid ejection method. The liquid discharge method according to claim 2,
In the transport operation, the medium is transported by a constant transport amount.
Liquid ejection method. A liquid ejection method according to claim 2 or claim 3, wherein
Among the liquid ejected from the nozzle, there is a liquid that does not land on the medium.
Liquid ejection method. A liquid discharge method according to any one of claims 2 to 4,
The minimum dot interval in the movement direction of the dot row formed in the first region is equal to the minimum dot interval in the movement direction of the dot row formed in the second region,
Liquid ejection method. A liquid discharge method according to any one of claims 1 to 5,
When the second resolution is higher than the first resolution,
The dot generation rate for the predetermined gradation value indicated by the pixel data corresponding to the first region is larger than the dot generation rate for the predetermined gradation value indicated by the pixel data corresponding to the second region,
Liquid ejection method. A liquid ejection method according to any one of claims 1 to 6,
When the second resolution is higher than the first resolution,
The dot diameter formed in the first region is larger than the dot diameter formed in the second region,
Liquid ejection method. A liquid ejection method according to any one of claims 1 to 7,
When the second resolution is higher than the first resolution,
In the step of converting the resolution,
Converting all of the plurality of pixel data to the second resolution;
Using a color conversion table in which specific gradation values and color conversion data are associated with each other, when certain pixel data is not the specific gradation value, any one of the specific levels in the vicinity of the pixel data is used. Probably select the color conversion data corresponding to the tone value and perform color conversion,
The pixel data corresponding to the first region of the plurality of pixel data subjected to color conversion is resolution-converted to the first resolution.
Liquid ejection method.