JP2005059364A - Inkjet recording method, inkjet recorder, and inkjet recording system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method whereby a trouble caused by superposing of inks having different colors on a recording medium is suppressed as much as possible even when the recording is performed by using the plurality of inks, and an inkjet recording system. <P>SOLUTION: When density data quantized in several steps is converted to final binary data by using a predetermined dot positioning pattern, different dot positioning patterns are prepared with respect to the plurality of inks. As a result, capability of superposing of the ink on a recording medium can be reduced as much as possible and the coloring property of each color ink can be efficiently enhanced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording method, an ink jet recording apparatus, and an ink jet recording system capable of expressing predetermined density information by recording a plurality of inks on a recording medium.

  With the recent spread of information processing equipment such as personal computers, recording devices as image forming terminals have been rapidly developed and spread. Among various recording apparatuses, an ink jet recording apparatus that performs recording on a recording medium such as paper, cloth, a plastic sheet, and an OHP sheet by ejecting ink from an ejection port is a low-noise non-impact recording method. It has excellent features such as high-density and high-speed recording operations, easy compatibility with color recording, and low cost, and is now the mainstream of personal-use recording devices. ing.

  Advances in ink-jet recording technology have promoted higher image quality, higher speed, and lower cost of recording, and can be integrated into personal computers and digital cameras (which function alone as well as other devices such as mobile phones) In addition to the widespread use of the recording apparatus, it has been a great contribution to the effect of spreading the recording apparatus to personal users. However, with such widespread use, personal users are demanding further improvements in image quality. Especially in recent years, printing systems and silver halide photography that can easily print photos at home are used. There is a demand for quality images that match.

  Compared with so-called general silver salt photographs, the inkjet recording apparatus has been regarded as a problem for a long time because of its unique graininess. Therefore, various measures for reducing the graininess have been proposed in recent years, and many recording apparatuses incorporating such measures have been provided. For example, there is an ink jet recording apparatus including an ink system in which light cyan or light magenta having a lower density is added in addition to normal cyan, magenta, yellow, and black. With such an ink system, graininess can be reduced by using light cyan or light magenta in a low density region. Further, in a high density region, it is possible to realize wider color reproduction and smooth gradation by recording with normal cyan and magenta.

  Furthermore, there is a method for reducing the graininess by designing the size of the dots that land on the recording medium to be smaller, and for this purpose, there is also a technique for reducing the amount of ink droplets ejected from each recording element arranged in the recording head. It has been advanced. In this case, not only a small amount of ink droplets but also a larger number of recording elements having a higher arrangement density makes it possible to simultaneously obtain a high-resolution image without impairing the recording speed.

  In addition, new ink colors such as red (R), green (G), and blue (B) are used to expand the color gamut that can be expressed because it approaches or exceeds the image quality of silver halide photography. In addition, a recording apparatus for recording with the addition of has been proposed. The R, G, and B are so-called secondary colors, and are colors that can be expressed by superimposing cyan, magenta, and yellow, which are originally primary colors. However, in actuality, when these primary colors are superimposed on the recording medium, there is a tendency that the color development effect of each other tends to be reduced. It is generally known that an image can be obtained. Hereinafter, for example, inks such as red, green, and blue that are applied with emphasis on color development on a recording medium will be referred to as “special color inks”.

  By the way, when performing so-called binarization processing for converting multi-value gradation data indicating the density of an image to be recorded into binary data indicating whether or not an ink droplet is to be recorded on a recording medium, there are already many methods. It is proposed and disclosed, and basically any method can be adopted. However, if the recording resolution and the type of ink color of the recording apparatus tend to increase as in recent years, it may be too heavy to perform binarization processing of all colors by the same means and the same process. . Therefore, for example, after performing a quantization process that reduces to several gradation levels by a printer driver installed in a host device connected to the recording apparatus, a final process is performed inside the recording apparatus. Recently, many recording apparatuses that perform binarization processing with a two-stage configuration have been provided. In this case, since one pixel output from the host device is expressed by gradation using a plurality of levels of density, it can be said to be a suitable method for applications in which gradation is important, such as photographic image quality.

  Several proposals and implementations have already been made for a method of converting multi-level density data in several stages into binary data (see, for example, Patent Document 1). According to Japanese Patent Laid-Open No. 2004-260260, a method of expressing gradation by recording / non-recording four dots in a 2 × 2 area for one input pixel having five gradation values is disclosed. Further, according to the same document, a plurality of patterns are prepared for the same gradation value for dot arrangement in a 2 × 2 area, and these plurality of dot arrangement patterns are sequentially or randomly assigned. A method of arranging is also disclosed. Doing so does not fix the dot arrangement pattern for each gradation, so that the pseudo contour and the so-called “fraying phenomenon” appearing at the edge of the image when pseudo halftone processing is performed can be reduced. It is also described that there is an effect on the use averaging of a plurality of recording elements arranged in the above.

  Furthermore, a conversion method having a configuration in which the above-described technology is further evolved in response to the higher accuracy of the recording apparatus has been proposed (for example, see Patent Document 2). According to Patent Document 2, a recording head having two recording element arrays having different characteristics while discharging ink droplets of the same color is used, or recording / non-recording is performed for each column in order to shorten the recording time. A recording apparatus that performs recording while adopting a method of switching recording (column thinning) is disclosed. A method for periodically arranging a plurality of patterns for preparing a plurality of dot arrangement patterns having different dot arrangements even with the same gradation value while preventing various harmful effects. Is disclosed.

JP-A-9-46522 JP 2002-29097 A

  However, the conventional methods for converting multi-level density data in several steps into binary data, as represented by the above-mentioned patent document, overcome a number of adverse effects that occur when printing using single color ink. However, no consideration has been given to the problems peculiar to the application of inks of a plurality of colors. As described in the background art section, generally, when inks of different colors overlap each other on a recording medium, a phenomenon occurs in which the respective coloring properties are reduced. In particular, when a large number of inks are applied simultaneously as in recent years, the probability that different colors overlap each other is increased, which becomes a serious problem.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is that even when recording is performed using a plurality of inks, the inks of different colors overlap each other on the recording medium. To provide an ink jet recording method, an ink jet recording apparatus, and an ink jet recording system in which adverse effects that occur are suppressed as much as possible.

  Therefore, according to the present invention, in an ink jet recording method for forming a color image on a recording medium using a recording head that discharges a plurality of colors of ink, the multi-value density data is converted into lower-level multi-value density data. A first quantization step, a second quantization step for performing a dot arrangement patterning process for converting the density data into binary data by adapting a dot arrangement pattern corresponding to the data value, and the dot arrangement patterning And a step of ejecting ink onto the recording medium by the recording head in accordance with binary data obtained by the processing, and in the second quantization step, for at least one color of the plurality of colors, The dot arrangement pattern different from that of other color inks is prepared.

  Also, an ink jet recording method for forming a color image on a recording medium using a recording head that discharges a plurality of colors of ink, wherein each pixel represented by a multi-value level corresponds to each pixel level. A step of assigning an arrangement pattern, and a step of ejecting ink from the recording head to the recording medium based on the dot arrangement pattern assigned to each pixel, wherein one of the plurality of colors is selected. The dot arrangement of the dot arrangement pattern used for ink has an exclusive relationship with the dot arrangement of the dot arrangement pattern used for at least one other color ink.

  In addition, in an ink jet recording system that forms a color image on a recording medium using a recording head that discharges a plurality of colors of ink, a first quantization that converts multi-value density data into lower-level multi-value density data Obtained by the dot arrangement patterning process, the second quantization means for performing the dot arrangement patterning process for converting the density data into binary data by adapting the dot arrangement pattern corresponding to the data value, and the dot arrangement patterning process. And means for ejecting ink onto the recording medium by the recording head in accordance with the binary data, wherein the second quantizing means uses other colors for at least one color of the plurality of colors. The dot arrangement pattern different from that of the ink is adapted.

  In addition, an inkjet recording apparatus that forms a color image on a recording medium using a recording head that discharges a plurality of colors of ink, and for each pixel represented by a multi-level, a dot corresponding to the level of each pixel Means for assigning an arrangement pattern, and means for causing ink to be ejected from the recording head onto the recording medium based on the dot arrangement pattern assigned to each pixel. The dot arrangement of the dot arrangement pattern used for ink has an exclusive relationship with the dot arrangement of the dot arrangement pattern used for at least one other color ink.

  In addition, in an ink jet recording method for forming a color image on a recording medium using a recording head that discharges a plurality of colors of ink, a first quantization that converts multi-value density data into lower-level multi-value density data Obtained by the step, the second quantization step for performing the dot arrangement patterning process for converting the density data into binary data by adapting the dot arrangement pattern corresponding to the data value, and the dot arrangement patterning process. And ejecting ink onto the recording medium by the recording head according to the binary data, and in the second quantization step, for the same value obtained by the first quantization step, A plurality of dot arrangement patterns different from each other are applied according to a predetermined arrangement rule, and at least one ink of the plurality of colors is different in other colors. Wherein the link between said different arrangement rules are prepared.

  Also, an ink jet recording method for forming a color image on a recording medium using a recording head that discharges a plurality of colors of ink, wherein each pixel represented by a multi-value level corresponds to each pixel level. When assigning an arrangement pattern, based on an assignment step of assigning one dot arrangement pattern among a plurality of different dot arrangement patterns corresponding to the same level in a predetermined order or randomly, and the dot arrangement pattern assigned to each pixel And a step of ejecting ink from the recording head onto the recording medium, and in the assigning step, the assignment order of the plurality of different dot arrangement patterns is one color of the plurality of colors. And at least one other color ink.

  In addition, in an ink jet recording system that forms a color image on a recording medium using a recording head that discharges a plurality of colors of ink, a first quantization that converts multi-value density data into lower-level multi-value density data Obtained by the dot arrangement patterning process, the second quantization means for performing the dot arrangement patterning process for converting the density data into binary data by adapting the dot arrangement pattern corresponding to the data value, and the dot arrangement patterning process. Means for ejecting ink to the recording medium by the recording head in accordance with the binary data, and the second quantization means is configured to output the same value obtained by the first quantization means, A plurality of different dot arrangement patterns are adapted according to a predetermined arrangement rule, and at least one of the plurality of colors is replaced with another color Characterized in that it is prepared the arrangement rules different from the ink.

  Furthermore, an inkjet recording apparatus that forms a color image on a recording medium using a recording head that discharges a plurality of colors of ink, and for each pixel represented by a multi-value level, a dot corresponding to the level of each pixel When allocating an arrangement pattern, an allocation means for allocating one dot arrangement pattern among a plurality of different dot arrangement patterns corresponding to the same level in a predetermined order or at random, and the dot arrangement pattern assigned to each pixel And means for ejecting ink from the recording head onto the recording medium, wherein the assigning means assigns the plurality of different dot arrangement patterns in the case of one color of the plurality of colors. And at least one other color ink.

  In this specification, “special color” refers to a color different from the hues of yellow, magenta, and cyan, which are basic color recording agents, in a broad sense. In a narrow sense, in the CIE-L * a * b * color space, a color reproduction area expressed on a recording medium by a combination of any two of the basic color recording agents of magenta, yellow, and cyan. Refers to a color that can express higher brightness and shows a hue angle within a color reproduction region expressed by a combination of any two of the above recording agents, or CIE-L * a * b * color space 2 can express brightness and saturation higher than the color reproduction region expressed on the recording medium by a combination of any two of the basic color recording materials of magenta, yellow, and cyan. A color indicating a hue angle in a color reproduction region expressed by a combination of two recording agents.

  In the present invention, it is preferable to use the above-mentioned “spot color” recording agent in a narrow sense, but it is also possible to use a “spot color” recording agent in a broad sense.

  According to the present invention, it is possible to reduce the probability that inks of different colors overlap each other on the recording medium as much as possible, so that the color developability of each ink can be efficiently exhibited.

Hereinafter, embodiments of the present invention will be described in detail.
(First embodiment)
FIG. 1 is a block diagram for explaining the flow of image data conversion processing in the recording system applied in this embodiment. The ink jet recording apparatus applied in this embodiment includes light cyan (LC) and light magenta (LM) in addition to inks that are basic colors of cyan (C), magenta (M), yellow (Y), and black (K). Recording is performed with red (R), which is a special color, and a recording head J0010 for discharging these seven colors of ink is prepared. As shown in FIG. 1, each process shown here is assumed to be constituted by a recording device and a personal computer (PC) as a host device.

  There are an application and a printer driver as programs that operate in the operation system of the host device, and the application J0001 executes processing for creating image data to be recorded by the recording device. At the time of actual recording, image data created by the application is passed to the printer driver.

  Assume that the printer driver in this embodiment includes a pre-stage process J0002, a post-stage process J0003, a γ correction J0004, a halftoning J0005, and a print data creation J0006. Here, each process will be briefly described. The pre-stage process J0002 performs color gamut mapping. Then, data conversion is performed to map the color gamut reproduced by the image data R, G, B of the sRGB standard into the color gamut reproduced by the recording apparatus. Specifically, 256-gradation data in which R, G, and B are each expressed in 8 bits is converted into 8-bit data of R, G, and B having different contents by using a three-dimensional LUT.

  The post-process J0003 is based on the data R, G, and B on which the color gamut is mapped, and the color separation data Y, M, C, K, LC, and LM corresponding to the combination of inks that reproduce the color represented by the data. And R are obtained. Here, similarly to the pre-processing, it is assumed that interpolation calculation is performed in combination with a three-dimensional LUT.

  The γ correction J0004 performs density value (tone value) conversion for each color data of the color separation data obtained by the post-processing J0003. Specifically, by using a one-dimensional LUT corresponding to the gradation characteristics of each color ink of the recording apparatus, conversion is performed so that the color separation data is linearly associated with the gradation characteristics of the recording apparatus.

  Halftoning J0005 performs quantization that converts 8-bit color separation data Y, M, C, K, LC, LM, and R into 4-bit data. In the present embodiment, 256-bit 8-bit data is converted into 9-gradation 4-bit data using a multilevel error diffusion method. The 4-bit data is data (gradation value information) that serves as an index for indicating the arrangement pattern of the dot arrangement patterning process in the printing apparatus.

  At the end of the processing performed by the printer driver, print data is created by adding print control information to the print image information containing the 4-bit index data by print data creation processing J0006.

  The printing apparatus performs a dot arrangement patterning process J0007 and a mask data conversion process J0008 on the input print data.

  The dot arrangement patterning process J0007, which is the most characteristic part of the present invention and this embodiment, will be described below. In the halftoning J0005 described above, the number of levels is reduced from 256-level multi-value density information (8-bit data) to 9-level tone value information (4-bit data). However, information that can be actually recorded by the ink jet recording apparatus of the present embodiment is binary information indicating whether or not to record ink. The dot arrangement patterning process J0007 plays a role of reducing the multi-value level of 0 to 8 to a binary level that determines the presence or absence of dots. Specifically, a dot arrangement pattern corresponding to a gradation value (levels 0 to 8) is assigned to 4-bit data that is an output value from halftoning J0005.

  FIG. 2 shows dot arrangement patterns to be converted for levels 0 to 8, respectively. Each level value shown on the left of the figure corresponds to level 0 to level 8 which are output values from the halftone processing unit. Each area composed of 2 vertical areas x 4 horizontal areas arranged on the right side corresponds to an area of one pixel (pixel) output by halftone processing, and 600 ppi (pixels / inch; reference value) in both vertical and horizontal directions. The size corresponds to the pixel density. Each area in one pixel corresponds to a minimum unit in which dot recording / non-recording is defined, and corresponds to a recording density of 1200 dpi (dot / inch; reference value) in the vertical direction and 2400 dpi in the horizontal direction. It is. In the recording apparatus of the present embodiment, a desired density can be obtained by recording one 2 pl ink droplet for one area represented by about 20 μm in length and about 10 μm in width corresponding to the recording density. It is designed like this. Further, with respect to 2 vertical areas × 4 horizontal areas, the vertical direction is the direction in which the ejection ports of the recording head are arranged, and the arrangement density of the areas, the ejection openings, and the arrangement density match with a value of 1200 dpi. The horizontal direction indicates the scanning direction of the recording head. In this embodiment, recording is performed at a density of 2400 dpi. In the dot arrangement patterning process J0007, 1-bit ejection data of “1” or “0” is arranged on the printing elements and printing columns corresponding to each of a plurality of areas forming one pixel. Defines dot recording / non-recording for the area. That is, a dot arrangement pattern corresponding to the level of the pixel is assigned to one pixel expressed by a multi-value level.

  In FIG. 2, the area filled with a circle indicates an area where dots of each color are recorded, and the number of dots to be recorded increases by one as the number of levels increases.

  In this embodiment, the dot arrangement pattern for each level is made different for each ink color. That is, even when the same level is input, a plurality of patterns are prepared so as to be arranged differently depending on the ink color. In particular, the special color red ink used for expanding the color gamut is configured so as not to overlap with other colors at level 4 or lower. Conversely, magenta (M) and light magenta (LM), cyan (C) and light cyan (LC), and yellow (Y) and black (K), which hardly overlap each other, form substantially the same hue angle. Are configured to use the same dot arrangement pattern.

  In the present embodiment, the configuration is focused on the color of red ink applied to expand the color gamut. In particular, on the low-level side where the brightness is high, consideration is given to ensuring that the red ink dots are overlapped with other ink dots as much as possible to ensure the red ink coloring effect. Regarding the other inks, the arrangement is such that the other ink colors are not overlapped as much as possible while being completely exclusive with the red ink at level 4 or lower. According to the dot arrangement patterning process J0007 described above, recording or non-recording of each color dot for each area on the recording medium is determined.

  Next, the mask data conversion process J0008 will be briefly described. In the mask data conversion process J0008, the dot arrangement of each color determined by the dot arrangement patterning process J0007 is masked using a plurality of mask patterns that are complementary to each other. The recording data obtained by each mask pattern is recorded on the recording medium by a plurality of continuous recording scans, and an amount of sub-scanning smaller than the recording width of the recording head is performed between each recording scan. Thereby, in the same area of the recording medium, images are sequentially formed by different recording elements in a plurality of recording scans. Recording performed by the above process is generally referred to as multipass recording. In images obtained by multi-pass printing, fine streaks due to variations peculiar to the printing elements and `` stitching streaks '' that appear at the sub-scanning pitch are dispersed throughout the image and become inconspicuous. Can be obtained.

  In the present embodiment, a plurality of mask data to be applied in a plurality of recording modes is stored in a memory in the recording apparatus main body. In the mask data conversion process J0008, the mask data and the dot arrangement patterning process described above are performed. By applying AND processing to the output signal, a recording dot that is actually ejected in each recording scan is determined and input to the drive circuit J0009 of the recording head H1001 as an output signal.

  In the above description, the multi-pass printing is applied to emphasize the image quality. However, the present invention and the present embodiment are not limited to this. When multi-pass printing is not applied, the mask data conversion process J0008 may be skipped, and the output signal of the dot arrangement patterning process may be input to the drive circuit J0009 as it is.

  The 1-bit data of each color input to the driving circuit J0009 is converted into a driving pulse for the recording head J0010, and ink is ejected from the recording head J0010 for each color at a predetermined timing.

  Note that the above-described dot arrangement patterning process and mask data conversion process in the printing apparatus are executed under the control of the CPU that constitutes the control unit of the printing apparatus using a dedicated hardware circuit.

The present embodiment is characterized in that the red ink, which is a special color applied to expand the color gamut, has a dot arrangement pattern that does not overlap with other ink colors on the low level side. In particular, the dot arrangement of magenta, light magenta, and yellow ink, which have a hue close to that of red ink and are often used at the same time, is completely exclusive with red ink, resulting in high saturation and lightness. This makes it possible to effectively express the color of the red ink in the state.
In the above description, the red ink is used as the special color ink for expanding the color gamut. However, the present invention is not limited to this. In addition to the red ink, for example, a special color such as blue ink or green ink may be used, or a combination of these may be used. Further, inks other than the special color inks (red ink, blue ink, green ink, etc.) are not limited to the above-described example, and for example, a configuration not using light cyan or light magenta may be used.

  FIG. 3 is an example showing the dot arrangement pattern of each color up to level 4 on the low level side when blue ink and green ink, which are also special colors, are applied in addition to the above-described red ink. As described above, when the number of ink types is further increased, it is difficult to make all ink colors completely exclusive with respect to all spot color inks even on the low level side. Therefore, in FIG. 3, the red, blue, and green ink colors are not completely exclusive, but examples of different dot arrangement patterns are shown.

  The effect of the present embodiment can be obtained even when the all colors are not completely exclusive dot arrangement patterns. In the configuration of the dot arrangement pattern, it is only necessary to maintain an appropriate relationship for each color in accordance with the type of ink color to be applied and the color development characteristics. In order to expand the color gamut as in this embodiment, When emphasizing the color developability of the special color ink prepared in the above, the effect of the present invention can be sufficiently obtained by applying the above-described configuration.

  In the above description, an example using a spot color is given and the description has been given for the purpose of effectively developing the color developability. However, the present invention does not necessarily apply the spot color ink. Even in an ink system to which no special color ink is applied, arranging the dots so that the dots do not overlap on the recording medium as much as possible makes it possible to effectively exhibit each other's color developability. For example, as an example of a system that does not use spot color inks, inks of six colors of magenta (M), light magenta (LM), cyan (C), light cyan (LC), yellow (Y), and black (K) are used. Can be considered. In this case, by using the dot arrangement pattern other than red (R) shown in FIG. 2, it is possible to prevent the dots of each color from overlapping as much as possible, and accordingly, the color developability of each color is effectively exhibited. be able to.

  Summarizing the above, it is possible to effectively exhibit the color developability of each color by using a dot arrangement pattern different from the ink of other colors for at least one of the plurality of colors used in the recording apparatus. To be able to.

  In the above description, input density data having a level of 9 gradations per pixel has been described as an example corresponding to a vertical 2 area × horizontal 4 area in the dot arrangement patterning process. Is not limited to this gradation and area.

(Second Embodiment)
The second embodiment of the present invention will be described below. Also in the present embodiment, it is assumed that the configuration shown in FIG. 1 can be applied to the flow of image data conversion processing as in the first embodiment.

  FIG. 4 shows an example of a dot arrangement pattern applied in the present embodiment. In FIG. 4, patterns A to H show eight types of dot arrangement patterns corresponding to level 1. Here, in order to simplify the explanation, the description will be limited to level 1. In actuality, however, it is assumed that patterns of different arrangements are prepared after level 2 as well as level 1. In this embodiment, a plurality of different dot arrangement patterns for the same level are associated with the same ink color in a predetermined order or randomly. That is, when the same level is input uniformly, the eight types of dot arrangement patterns A to H shown on the recording medium are recorded in the predetermined order or randomly arranged. To have such a configuration, as described in the above-mentioned patent document, the effect of equalizing the number of ejections between the recording elements located in the upper part of the dot arrangement pattern and the recording elements located in the lower part, The effect of dispersing various noises peculiar to the recording apparatus can be obtained.

  FIGS. 5A to 5C show the red ink (R) applied in the present embodiment and the magenta ink (M), light magenta ink (LM), and yellow (red) to be set as exclusive as possible. Y) An arrangement example of the dot arrangement patterns A to H on the recording medium in the ink is shown. The vertical direction in the figure coincides with the vertical direction of the individual dot arrangement patterns A to H, that is, the arrangement direction of the recording elements of the recording head. Further, the horizontal direction coincides with the scanning direction of the recording head. As can be seen from the figure, the present embodiment is characterized in that the arrangement order of the dot arrangement patterns is different for each color while the dot arrangement patterns A to H are used for all ink colors. With such a configuration, even if dots of different colors overlap in a certain 2 × 4 area (area corresponding to one pixel surrounded by a circle in FIG. 5A), many other areas Can prevent dots from overlapping each other. Therefore, if it is determined in an area having a certain size, the color developability of the special color ink can be effectively maintained. 5A to 5C show an example in which a plurality of dot arrangement patterns A to H are arranged differently for each color at random.

  FIGS. 6A to 6C show an arrangement example using the four dot arrangement patterns A to D shown in FIG. For example, FIG. 6A shows a dot arrangement pattern of red ink, and in the uppermost pixel row, four dot arrangement patterns circulate in the order of A → B → C → D. The second row of pixels is arranged in a state shifted by one pixel to the right with respect to the uppermost row of pixels, and the third and subsequent rows are also shifted to the right one pixel at a time relative to the adjacent upper row. The arrangement is arranged.

  FIGS. 6B and 6C show arrangement examples of ink colors (for example, magenta, light magenta, and yellow) for which dot arrangement is to be configured as exclusively as possible with the red ink of FIG. 6A. is there. Here, in the uppermost pixel column, both (b) and (c) have the same arrangement as (a). However, in the second to fourth stage rasters, the shift amount from the upper stage differs from (a). In (b), the dot arrangement pattern is shifted by two pixels in the right direction, and in (c), the dot arrangement pattern is shifted by −1 pixel in the right direction (one pixel in the left direction). In this way, if the shift amount is different for each color, it is possible to realize a state in which dots do not overlap each other in most parts, as in the random arrangement described with reference to FIG. On the other hand, since it is only necessary to shift the predetermined array by a predetermined amount, it is possible to reduce the memory required for the dot arrangement pattern stored in the printing apparatus as compared with the case of FIG.

  As described above, several other methods for creating a plurality of different dot arrangements using, for example, four types of dot arrangement patterns A to D can be proposed. An example is briefly described below.

  FIG. 7 shows an example in which an arrangement as exclusive as possible with the red ink in FIG. 6A is created by a method different from the method described in FIG. In this method, the order of arrangement in the horizontal direction is the same as that in FIG. 6A, but the dot arrangement pattern applied to the pixel at the start point (uppermost and leftmost) is different from that in FIG. 6A. There is a special feature. For example, in FIG. 6A, the starting pixel corresponds to the dot arrangement pattern A, and the respective patterns are arranged in the order of A → B → C → D → A → B → C → D → in the horizontal direction. Yes. On the other hand, in FIG. 7, the pixel at the starting point corresponds to the dot arrangement pattern C, and the respective patterns are arranged in this order from C → D → A → B → C → D → A → B →. The subsequent lower stage has a configuration in which a dot arrangement pattern is arranged by shifting one pixel to the right with respect to the adjacent upper stage every time one stage is lowered, as in FIG.

  In this way, the method of arranging the start points different from each other while using the same arrangement pattern is similar to the method described in FIG. 6 in that the memory required for the dot arrangement pattern stored in the printing apparatus is reduced. It is possible to form an exclusive array in all areas at level 1 while keeping the capacity low.

  FIG. 8 shows a case where the arrangement period in the horizontal direction is made different from the arrangement example shown in FIG. That is, in FIG. 6A, four types of dot arrangement patterns A to D are arranged while being shifted regularly, whereas in FIG. 8, five types of dot arrangement patterns A to E are arranged. These are arranged with regular shifting.

  As described above, there are various methods for creating different dot arrangement patterns, and this embodiment is effective regardless of which method is employed. For example, as described with reference to FIG. 6, when the arrangement of the dot arrangement pattern is shifted at each stage, the shift amount may be changed at random.

  The feature of this embodiment is that a plurality of dot arrangement patterns (for example, A to H) are prepared for the same input signal level, and these dot arrangement patterns are arranged in different orders for different ink colors. It is to record in the state. Such a configuration can suppress the possibility that different color dots overlap each other on the low level side as much as possible, but has a color development property in a wider area compared to the first embodiment for more ink colors. Can be considered effectively.

In this embodiment, as in the first embodiment, in addition to the red ink, for example, a special color such as blue ink or green ink may be used, or a combination of all of these may be used. Further, inks other than the special color inks (red ink, blue ink, green ink, etc.) are not limited to the above-described example, and for example, light cyan or light magenta may be used.
Also in this embodiment, as in the first embodiment, the special color ink does not necessarily have to be applied. Even in an ink system to which no special color ink is applied, arranging the dots so that the dots do not overlap on the recording medium as much as possible makes it possible to effectively exhibit each other's color developability.

  Further, in the present embodiment, similarly to the first embodiment, the input density data having 9 gradation levels per pixel is limited to an example corresponding to a vertical 2 area × horizontal 4 area region. is not.

  Further, in the present embodiment, the arrangement period of each dot arrangement pattern is not limited to the above-described configuration, and a longer period or a shorter period may be applied in the vertical direction and the horizontal direction. You may arrange | position so that it may not have periodicity completely.

  To summarize the above, by assigning different allocation orders of a plurality of different dot arrangement patterns corresponding to the same level between at least one of the plurality of colors and other colors, each color The color developability can be effectively exhibited.

(Other configurations)
Here, a configuration of a suitable inkjet recording apparatus capable of realizing the first embodiment and the second embodiment of the present invention will be described. In the following, the case where seven colors of cyan, light cyan, magenta, light magenta, yellow, black, and red are used as inks to be used will be described. It is not limited to.

(Schematic structure of the mechanism part of the inkjet device)
First, a schematic configuration of the mechanism unit of the ink jet recording apparatus will be described. The main body of the recording apparatus according to the present embodiment includes a paper feed unit, a paper transport unit, a carriage unit, a paper discharge unit, a cleaning unit, and an exterior unit that protects them and has design properties from the role of each mechanism. The outline of these will be described below.

  FIG. 9 is a perspective view of the recording apparatus. 10 and 11 are diagrams for explaining the internal mechanism of the recording apparatus main body. FIG. 10 is a perspective view from the upper right part, and FIG. 11 is a side sectional view of the recording apparatus main body. is there.

  When paper feeding is performed in the recording apparatus, first, only a predetermined number of recording media are sent to a nip portion including a paper feed roller M2080 and a separation roller M2041 in a paper feed unit including a paper feed tray M2060. The sent recording medium is separated at the nip portion, and only the uppermost recording medium is conveyed to the sheet conveying portion. The recording medium sent to the paper transport unit is guided by the pinch roller holder M3000 and the paper guide flapper M3030, and is sent to the roller pair of the transport roller M3060 and the pinch roller M3070. A roller pair composed of a conveyance roller M3060 and a pinch roller M3070 is rotated by driving of an LF motor, and the recording medium is conveyed on the platen M3040 by this rotation.

  The carriage unit has a carriage M4000 for mounting the recording head H1001, and the carriage M4000 is supported by a guide shaft M4020 and a guide rail M1011. The guide shaft M4020 is attached to the chassis M1010 and guides and supports the carriage M4000 to reciprocate in a direction perpendicular to the recording medium conveyance direction. The carriage M4000 is driven via a timing belt M4041 by a carriage motor E0001 attached to the chassis M1010. Further, a flexible cable E0012 (not shown) for transmitting a drive signal from the electric board E0014 to the recording head H1001 is connected to the carriage M4000. When an image is formed on a recording medium in such a configuration, a pair of rollers including a conveyance roller M3060 and a pinch roller M3070 conveys and positions the recording medium in the conveyance direction (column direction). Further, with respect to the scanning direction (raster direction), the carriage M4000 is moved in a direction perpendicular to the transport direction by the carriage motor E0001, and the recording head H1001 (FIG. 12) is arranged at a target image forming position. The positioned recording head H1001 ejects ink to the recording medium in accordance with a signal from the electric substrate E0014. Although a detailed configuration of the recording head H1001 will be described later, in the recording apparatus according to the present embodiment, a recording medium is scanned by the carriage M4000 while recording is performed by the recording head H1001, and a recording medium is conveyed by the conveying roller M3060. An image is formed on a recording medium by alternately repeating sub-scanning.

  The recording medium on which the image has been finally formed is sandwiched between nips of the first paper discharge roller M3110 and the spur M3120 at the paper discharge unit, conveyed, and discharged to the paper discharge tray M3160.

  In the cleaning unit, for the purpose of cleaning the recording head H1001 before and after image recording, if the pump M5000 is operated with the cap M5010 in close contact with the ink discharge port of the recording head H1001, it is unnecessary from the recording head H1001. Ink or the like is sucked. Further, by sucking the ink remaining in the cap M5010 with the cap M5010 opened, consideration is given to preventing the remaining ink from sticking and the subsequent adverse effects.

(Recording head configuration)
The configuration of the head cartridge H1000 that can be applied in the above embodiment will be described below. The head cartridge H1000 has a recording head H1001, means for mounting the ink tank H1900, and means for supplying ink from the ink tank H1900 to the recording head, and is detachably mounted on the carriage M4000. .

  FIG. 12 is a diagram showing how the ink tank H1900 is mounted on the head cartridge H1000 applicable in the above embodiment. Since the recording apparatus forms an image with seven colors of ink of cyan, light cyan, magenta, light magenta, yellow, black and red, the ink tank H1900 is also prepared for seven colors independently. As shown in the figure, each is detachable from the head cartridge H1000. The ink tank H1900 can be attached and detached while the head cartridge H1000 is mounted on the carriage M4000.

  FIG. 13 is an exploded perspective view of the head cartridge H1000. In the figure, a head cartridge H1000 includes a first recording element substrate H3600, a second recording element substrate H3601, a first plate H1200, a second plate H1400, an electric wiring substrate H1300, a tank holder H1500, and a flow path forming member H1600. , Filter H1700, seal rubber H1800, and the like.

  The first recording element substrate H3600 and the second recording element substrate H3601 are Si substrates, and a plurality of recording elements (nozzles) for ejecting ink are formed on one side thereof by photolithography. Electric wiring such as Al for supplying electric power to each recording element is formed by a film forming technique, and a plurality of ink flow paths corresponding to individual recording elements are also formed by a photolithography technique. Further, an ink supply port for supplying ink to the plurality of ink flow paths is formed to open on the back surface.

  FIG. 14 is an enlarged front view for explaining the configuration of the first recording element substrate H3600 and the second recording element substrate H3601. H4000 to H4600 are nozzle rows corresponding to different ink colors, and the first printing element substrate H4700 has a nozzle row H4000 supplied with light magenta, a nozzle row H4100 supplied with red ink, and a black ink supply. There are configured nozzle rows for four colors, a nozzle row H4200 to be supplied and a nozzle row H4300 to which light cyan ink is supplied. In addition, the second recording element substrate H3601 includes nozzle rows for three colors: a nozzle row H4400 to which cyan ink is supplied, a nozzle row H4500 to which magenta ink is supplied, and a nozzle row H4600 to which yellow ink is supplied. Is formed.

Each nozzle row is composed of 768 nozzles arranged at an interval of 1200 dpi (dot / inch; reference value) in the conveyance direction of the recording medium, and ejects approximately 2 picoliters of ink droplets. The opening area at each nozzle outlet is set to approximately 100 square μm ² . In addition, the first recording element substrate H3600 and the second recording element substrate H3601 are bonded and fixed to the first plate H1200, and here, the first recording element substrate H3600 and the second recording element substrate H3601 are attached. An ink supply port H1201 for supplying ink is formed.

  Further, a second plate H1400 having an opening is bonded and fixed to the first plate H1200, and the second plate H1400 includes the electric wiring board H1300, the first recording element substrate H3600, and the second plate H1400. The electric wiring substrate H1300 is held so as to be electrically connected to the recording element substrate H3601.

  The electrical wiring substrate H1300 applies an electrical signal for ejecting ink from each nozzle formed on the first recording element substrate H3600 and the second recording element substrate H3601, and the first recording element substrate The electric wiring corresponding to the H3600 and the second recording element substrate H3601 and an external signal input terminal H1301 for receiving an electric signal from the recording apparatus main body located at the end of the electric wiring. The external signal input terminal H1301 is positioned and fixed on the back side of the tank holder H1500.

  On the other hand, in a tank holder H1500 that holds the ink tank H1900, a flow path forming member H1600 is fixed by, for example, ultrasonic welding to form an ink flow path H1501 that communicates from the ink tank H1900 to the first plate H1200.

  A filter H1700 is provided at the ink tank side end of the ink flow path H1501 that engages with the ink tank H1900, and can prevent dust from entering from the outside. Further, a seal rubber H1800 is attached to the engaging portion with the ink tank H1900 so that ink can be prevented from evaporating from the engaging portion.

  Further, as described above, the tank holder portion composed of the tank holder H1500, the flow path forming member H1600, the filter H1700, and the seal rubber H1800, the first recording element substrate H3600, the second recording element substrate H3601, and the first plate. The head cartridge H1000 is configured by bonding the recording head unit H1001 including the H1200, the electric wiring substrate H1300, and the second plate H1400 by bonding or the like.

  The present invention can be used in a recording system capable of expressing predetermined density information by recording a plurality of colors of ink on a recording medium.

It is a block diagram for demonstrating the flow of the image data conversion process in the recording system applied by embodiment of this invention. It is the figure which showed the dot arrangement pattern with respect to the levels 0-8 in the 1st Embodiment of this invention. It is the figure which showed to the level 4 the dot arrangement pattern of the blue ink and the green ink in the 1st Embodiment of this invention. It is the figure which showed the example of the dot arrangement pattern applied in the 2nd Embodiment of this invention. (A)-(c) is the figure which showed the example of an arrangement | sequence on the recording medium of the dot arrangement pattern applied in the 2nd Embodiment of this invention. (A)-(c) is the figure which showed the example of an arrangement | sequence using the four dot arrangement pattern applicable in the 2nd Embodiment of this invention. It is the figure which showed the example of an arrangement | sequence using the four dot arrangement pattern applicable in the 2nd Embodiment of this invention. It is the figure which showed the example of an arrangement | sequence using the five dot arrangement pattern applicable in the 2nd Embodiment of this invention. 1 is a perspective view of an inkjet recording apparatus applicable in an embodiment of the present invention. It is a figure for demonstrating the internal mechanism of the inkjet recording device applicable with embodiment of this invention. It is a figure for demonstrating the internal mechanism of the inkjet recording device applicable with embodiment of this invention. FIG. 2 is a configuration diagram of a head cartridge and an ink tank applicable in the embodiment of the present invention. It is a disassembled perspective view of the head cartridge applicable in the embodiment of the present invention. FIG. 3 is a configuration diagram of a first recording element substrate and a second recording element substrate.

Explanation of symbols

J0001 Application J0002 First stage J0003 Second stage J0004 Gamma correction J0005 Half toning J0006 Print data creation J0007 Dot arrangement patterning process J0008 Mask data conversion process J0009 Head drive circuit J0010 Recording head M1010 Chassis M1011 Guide rail M2041 Separating roller M2060 Paper feed tray M2080 Paper feed tray M2080 Roller M3000 Pinch roller holder M3030 Paper guide flapper M3040 Platen M3060 Transport roller M3070 Pinch roller M3100 First paper discharge roller M3160 Paper discharge tray M4000 Carriage M4020 Guide shaft M4041 Timing belt M5000 Pump M5010 Cap M7030 Access cover E0 001 Carriage motor E0012 Flexible cable E0014 Electric substrate H1000 Head cartridge H1001 Recording head H1200 First plate H1201 Ink supply port H1400 Second plate H1500 Tank holder H1501 Ink channel H1600 Channel forming member H1700 Filter H1800 Seal rubber H1900 Ink tank H3600 First One printing element substrate H3601 Second printing element substrate H4000 Light magenta nozzle row H4100 Red nozzle row H4200 Black nozzle row H4300 Light cyan nozzle row H4400 Cyan nozzle row H4500 Magenta nozzle row H4600 Yellow nozzle row

Claims (12)

In an inkjet recording method for forming a color image on a recording medium using a recording head that discharges ink of a plurality of colors,
A first quantization step of converting multi-value density data into lower-level multi-value density data;
A second quantization step for performing a dot arrangement patterning process for converting the density data into binary data by adapting a dot arrangement pattern corresponding to the data value;
And a step of ejecting ink onto the recording medium by the recording head in accordance with the binary data obtained by the dot arrangement patterning process, and in the second quantization step, at least one of the plurality of colors An ink jet recording method, wherein the dot arrangement pattern different from that of other color inks is prepared for color inks. An inkjet recording method for forming a color image on a recording medium using a recording head that discharges a plurality of colors of ink,
Assigning a dot arrangement pattern corresponding to the level of each pixel to each pixel represented by a multi-value level;
Discharging ink from the recording head to the recording medium based on a dot arrangement pattern assigned to each pixel;
The dot arrangement of the dot arrangement pattern used for one color ink of the plurality of colors has an exclusive relationship with the dot arrangement of the dot arrangement pattern used for at least one other color ink An ink jet recording method, comprising: In an inkjet recording system that forms a color image on a recording medium using a recording head that discharges ink of a plurality of colors,
First quantization means for converting multi-value density data into lower-level multi-value density data;
Second quantization means for performing dot arrangement patterning processing for converting the density data into binary data by adapting a dot arrangement pattern corresponding to the data value;
Means for ejecting ink to the recording medium by the recording head according to binary data obtained by the dot arrangement patterning process, and the second quantizing means includes at least one of the plurality of colors. An ink jet recording system characterized by adapting the dot arrangement pattern different from that of other color inks for color inks.   4. The first quantization means is provided in a host computer, and the second quantization means is provided in an ink jet recording apparatus that includes the recording head and is connected to the host computer. The inkjet recording system described in 1. An inkjet recording apparatus that forms a color image on a recording medium using a recording head that discharges a plurality of colors of ink,
Means for assigning a dot arrangement pattern corresponding to the level of each pixel to each pixel represented by a multi-valued level;
Means for ejecting ink from the recording head to the recording medium based on a dot arrangement pattern assigned to each pixel;
The dot arrangement of the dot arrangement pattern used for one color ink of the plurality of colors has an exclusive relationship with the dot arrangement of the dot arrangement pattern used for at least one other color ink An ink jet recording apparatus, comprising: In an inkjet recording method for forming a color image on a recording medium using a recording head that discharges ink of a plurality of colors,
A first quantization step of converting multi-value density data into lower-level multi-value density data;
A second quantization step for performing a dot arrangement patterning process for converting the density data into binary data by adapting a dot arrangement pattern corresponding to the data value;
And a step of ejecting ink onto the recording medium by the recording head in accordance with binary data obtained by the dot arrangement patterning process. In the second quantization step, the first quantization step A plurality of dot arrangement patterns different from each other are applied according to a predetermined arrangement rule for the same value obtained by the above, and the arrangement rule different from the inks of other colors is applied to at least one of the plurality of colors. An ink jet recording method characterized by being prepared. An inkjet recording method for forming a color image on a recording medium using a recording head that discharges a plurality of colors of ink,
When assigning a dot arrangement pattern corresponding to the level of each pixel to each pixel represented by a multilevel level, one dot arrangement pattern among a plurality of different dot arrangement patterns corresponding to the same level is assigned in a predetermined order. An assigning process that assigns at random or randomly,
Discharging ink from the recording head to the recording medium based on a dot arrangement pattern assigned to each pixel;
In the assignment step, the assignment order of the plurality of different dot arrangement patterns is different between the case of one color ink among the plurality of colors and the case of at least one other color ink. An inkjet recording method.   In the assigning step, the dot arrangement of the dot arrangement pattern used for the one color ink and the dot arrangement of the dot arrangement pattern used for the other one color ink have an exclusive relationship in the same pixel. The inkjet recording method according to claim 7, wherein the plurality of different dot arrangement patterns are assigned. In an inkjet recording system that forms a color image on a recording medium using a recording head that discharges ink of a plurality of colors,
First quantization means for converting multi-value density data into lower-level multi-value density data;
Second quantization means for performing dot arrangement patterning processing for converting the density data into binary data by adapting a dot arrangement pattern corresponding to the data value;
Means for ejecting ink to the recording medium by the recording head in accordance with binary data obtained by the dot arrangement patterning process, and the second quantizing means comprises the first quantizing means. A plurality of dot arrangement patterns different from each other are adapted according to a predetermined arrangement rule with respect to the same value obtained by the above, and the arrangement rule different from the inks of other colors is applied to at least one of the plurality of colors. An inkjet recording system characterized by being prepared.   10. The first quantization means is provided in a host computer, and the second quantization means is provided in an ink jet recording apparatus that includes the recording head and is connected to the host computer. The inkjet recording system described in 1. An inkjet recording apparatus that forms a color image on a recording medium using a recording head that discharges a plurality of colors of ink,
When assigning a dot arrangement pattern corresponding to the level of each pixel to each pixel represented by a multilevel level, one dot arrangement pattern among a plurality of different dot arrangement patterns corresponding to the same level is assigned in a predetermined order. An assigning means for assigning randomly or randomly,
Means for causing ink to be ejected from the recording head to the recording medium based on the dot arrangement pattern assigned to each pixel, and the assignment means determines the assignment order of the plurality of different dot arrangement patterns. 2. An ink jet recording apparatus, wherein the ink jet recording apparatus is different for one color ink among a plurality of colors and for at least one other color ink. The assigning means has an exclusive relationship between a dot arrangement of a dot arrangement pattern used for the one color ink and a dot arrangement of a dot arrangement pattern used for the other one color ink in the same pixel. The inkjet recording apparatus according to claim 11, wherein the plurality of different dot arrangement patterns are assigned.

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