JPH09248921A - Device and method for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the bleeding of a boundary without the deterioration of printing speed and the formation of an image by identifying whether the boundary is formed or not between a black image area and a color image area and substituting a dot of shading for the color used in the color image area for at least one dot on the black image area side of the boundary. SOLUTION: When a boundary is formed between a black image area and a color image area, at least one dot on the black image area side of the boundary is substituted by a dot of a color forming a shading of the color used in the color image area adjoining the black image area. A shading dot SD recorded by a penetration color ink for forming the shading of the color of a color dot CD is interposed between a black dot BD recorded by the black ink of high surface tension and the color dot CD recorded by the penetration color ink. At that time, as the penetration ink is used for the color dot CD and the shading dot SD, bleeding is scarcely generated between the two dots CD and SD.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording apparatus and an inkjet recording method, and more particularly to an inkjet recording apparatus and an inkjet recording method for recording a color image.

[0002]

2. Description of the Related Art Since an ink jet recording apparatus has almost no vibration or noise during recording and it is particularly easy to color,
In addition to a printer that outputs data from a digital processing device such as a computer, it is also used for facsimile machines, copiers, and the like. With the expansion of the use of such inkjet recording apparatuses, what was used to color the graphs or emphasize words and phrases in the past was changed to full-color graphics, output of captured images from a video or scanner, postcards, etc. Functions that can be used for various purposes such as output are required.

By the way, in such an ink jet recording apparatus, the ink jet head for ejecting ink droplets and the ink used are important factors due to its constitution. Particularly, regarding ink, since various types of recording media are used such as special paper, plain paper, recycled paper, and OHP, these various recording media (hereinafter referred to as “paper”).
Various developments have been made to obtain good image quality, and by adding surfactants and lubricants, penetrability into paper,
Ink with improved fixability is often used.

If this is normal ink, FIG.
As shown in (a), two different color ink drops I1, I
2 is ejected onto the paper P and landed on the paper P adjacently as shown in FIG.
After forming an ink pool due to surface tension, 1 and I2 permeate into the paper P and evaporate into the air, but at this time, because of poor permeability, they overflow each other in the state of ink pool, As shown in FIG. 3C, the bleeding occurs when the inks of the two colors are mixed with each other, causing bleeding, and blurring of individual dots, which deteriorates the image quality.

On the other hand, when a penetrating ink is used,
As shown in FIG. 17A, two different color ink droplets I
When 1 and I2 are ejected onto the paper P and land adjacently on the paper P as shown in FIG. 2B, ink drops 1 and 2 are accumulated due to the influence of a surfactant or the like. Since the ink is small and penetrates more quickly than the normal ink, the inks of the two colors do not penetrate into the paper P before the ink overflows and bleeds as shown in FIG. Can be expressed and the image quality is improved.

However, since such penetrative ink has high penetrability, the ink spreads along the fibers on the surface of the paper and causes feather-like blurring,
Since it penetrates deeply into the paper, the amount of coloring material on the paper surface is reduced, causing problems such as insufficient density and strikethrough. This is not a big problem for a graphic image that does not require much edge sharpness, but it is a big problem as quality deterioration in the output of text such as a line drawing or a sentence seen in a drawing or the like.

In order to solve this problem, black ink mainly used for line drawings and texts has a high surface tension. This is because penetrability is sacrificed to some extent, and beautiful dots can be formed by preventing feathering, and since it does not easily penetrate into the inside of the paper, the coloring agent stays near the surface of the paper and sufficient image density can be obtained. .

However, when the black ink having a high surface tension and the penetrating ink are used in combination, a new problem occurs. That is, as shown in FIG. 18A, an ink droplet I1 of another color (a color other than black) using the permeable ink.
And a high surface tension black ink droplet I2 are ejected adjacently to the paper P and land adjacently on the paper P as shown in FIG.
No. 1 immediately penetrates and forms no ink pool on the paper as described above, while the ink drop I of high surface tension ink
2 does not penetrate into the paper all at once due to its surface tension, but gradually penetrates into the paper while forming an ink pool on the surface of the paper. Therefore, as shown in FIG.
When the second ink reservoir touches the ink droplet I1 of the permeable ink, it is affected by the surfactant, which is a component of the permeable ink, and overflows into the dot due to the ink droplet I1 of the permeable ink at once. Bleeding occurs. Particularly, since the high surface tension ink is the most conspicuous black ink, the influence on the image quality becomes large.

Although such blurring is not noticeable in a graphic such as a photograph having a relatively small solid portion, a background color is set in the text for highlighting a color graph in which characters and line drawings are included in the background color. In such a case, the viewer will perceive it as a remarkable blur.

Therefore, in the prior art, Japanese Patent Laid-Open No. 4-364961
If there is another color image area adjacent to the black image area as described in Japanese Patent Publication No. JP-A-2004-115, before the black ink used for the black image area is ejected, the color of the color used for the adjacent color image area is changed. For example, the ink may be ejected first.
As described in JP-A-162339, the dots at the boundary between the black image area and another color image area adjacent to the black image area are thinned out or whitened.
When there is another color image area adjacent to the black image area as described in Japanese Patent Laid-Open Publication No. 2004-53242, the ink forming the black image area is changed from the black ink to the composite black expressing cyan, magenta and yellow in an overlapping manner. It is proposed to switch.

[0011]

However, among the above-mentioned conventional ink jet recording methods, the printing method in which two types of inks are ejected with a time difference, the printing speed is reduced. Further, in the printing method of thinning the boundary portion, it is recognized as a white stripe or a contour when the black dot diameter is not sufficient due to the characteristics of the high surface tension ink that is difficult to spread, that is, difficult to spread, and environmental temperature and paper quality, Image quality is degraded. Further, in the printing method in which the black ink is replaced with the composite black, the color tone itself changes, and the amount of ink that is applied to the paper at one time increases, causing strikethrough and cockling of the ink.

The present invention has been made in view of the above points, and it is an object of the present invention to suppress bleeding at a color boundary portion without lowering printing speed and image quality.

[0013]

In order to solve the above-mentioned problems, the ink jet recording apparatus according to claim 1 can use a black ink whose permeability or fixability to a recording medium is different from other color inks. In the ink jet recording apparatus, a determining unit that determines whether or not a black image area to be recorded using the black ink is in contact with a color image area to be recorded using the other color ink, and a determining unit. When the black image area touches the boundary with the color image area according to the determination result of, at least one dot on the black image area side of the boundary is a complementary color of the color used in the color image area touching the black image area. And a replacement unit that replaces the dot with a color of

An ink jet recording apparatus according to a second aspect is the ink jet recording apparatus according to the first aspect, wherein the determining means determines whether or not the color used in the color image area in contact with the black image area is blue. According to the result of this discrimination, the replacing means is provided with means for replacing with red or green when the color used in the color image area is blue.

According to a third aspect of the present invention, there is provided the ink jet recording apparatus according to the first or second aspect, in which the determining means refers to eight dots in the vicinity of each dot of the black image data, and the dots of other colors are It is determined whether or not there are one or more and less than four, and the replacement means determines one or more and four or more dots of other colors within the eight dots in the vicinity of the black image data dot of interest according to the determination result. When there is less than the above, the dot of the focused black image data is replaced.

An ink jet recording apparatus according to a fourth aspect is the ink jet recording apparatus according to the third aspect, in which 8 is provided in the vicinity of the dot of the black image data focused by the discrimination means.
The replacement means comprises means for extracting the largest number of colors of the dots of the other colors included in the dots, and the replacing means forms the dots of the noted black image data according to the extraction result. It is configured to have a means for substituting the dots. .

According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus according to the fourth aspect, wherein the discrimination means is provided with 8 in the vicinity of the dot of the black image data focused on by the discrimination means.
A means for determining whether or not the dots of other colors included in the dots are all different color dots, and the replacing means determines that the dots of the other colors are all different color dots according to the determination result. At a certain time, a configuration is provided in which the dot of the focused black image data is not replaced.

According to a sixth aspect of the present invention, there is provided an ink jet recording apparatus according to any one of the first to fifth aspects, wherein an ink of another color having a higher permeability or a drying property than the black ink is used. And

According to a seventh aspect of the present invention, there is provided an ink jet recording apparatus according to any one of the first to sixth aspects, wherein a black ink having a higher surface tension than the other color inks is used.

In the ink jet recording method according to the eighth aspect, recording is performed by using the black ink in a color ink jet recording apparatus capable of using a black ink having different penetrability or fixability to a recording medium from inks of other colors. It is determined whether or not the black image area is in contact with the color image area to be printed by using the other color ink, and when the black image area is in contact with the color image area, the black of the boundary is determined. At least one dot on the image area side is replaced with a dot of a color that is a complementary color to the color used in the color image area adjacent to the black image area.

An ink jet recording method according to a ninth aspect is the ink jet recording method according to the eighth aspect, wherein it is determined whether or not the color used in the color image area in contact with the black image area is blue, and the color image area is determined. When the color used in is blue, it is replaced with red or green.

According to a tenth aspect of the present invention, there is provided an ink jet recording method comprising:
In the inkjet recording method according to claim 8 or 9, it is determined whether or not there are one or more and less than four dots of other colors by referring to the neighboring 8 dots for each dot of the black image data, When there are one or more and less than four dots of other colors within the eight dots near the focused black image data dot, the focused black image data dot is replaced.

[0023] The ink jet recording method according to claim 11 is characterized in that:
11. The inkjet recording method according to claim 10, wherein the largest number of dots of other colors included in 8 dots near the dot of the noted black image data are extracted, and the noted black image data is extracted. The dots are replaced with the dots of the extracted color.

According to a twelfth aspect of the present invention, there is provided an ink jet recording method comprising:
The ink jet recording method according to claim 11, wherein it is determined whether or not all the dots of other colors included in the eight dots in the vicinity of the noted black image data dot are dots of different colors, and the other When all the color dots are different color dots, the dot of the focused black image data is not replaced.

The ink jet recording method of claim 13 is
In the ink jet recording method according to any one of claims 8 to 12, it is configured to use an ink of another color that is used because it has better permeability or dryness than the black ink.

The ink jet recording method of claim 14 is:
In the ink jet recording apparatus according to any one of claims 8 to 13, the black ink having a higher surface tension than the inks of other colors is used.

[0027]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a schematic plan view of an inkjet recording apparatus to which the present invention is applied, and FIG. 2 is a schematic side view of the recording apparatus.

In this ink jet recording apparatus, a carriage 4 is slidably mounted on a front guide 2 and a guide shaft 3 provided between left and right main scanning frames 1 and 1, and a recording consisting of an ink jet head is formed on a lower surface of the carriage 4. In addition to mounting the head 5, an ink cartridge 6 is detachably provided on the upper surface.

A main scanning drive motor 8 is attached to a substantially L-shaped stay 7 provided between the left and right main scanning frames 1 and 1, and a motor pulley 9 and a stay mounted on a rotary shaft of the main scanning drive motor 8 are attached to the stay 7. 7. A belt 11 is stretched between the side pulley 10 attached to the belt 7, and the carriage 4 is fixed to the belt 11 by a belt clamp 12 as shown in FIG. The carriage 4 is scanned in the direction of arrow A in FIG. 1 (main scanning direction). The side pulley 10 is attached so as to be able to move slightly in the main scanning direction, and tension is applied to the belt 11 by a tension spring 13.

On the other hand, the platen 16 is rotatably mounted between the left and right sub-scanning frames 15 and is pressed against the peripheral surface of the platen 16 as shown in FIG.
7 and 18 are arranged, and a paper pan 19 for guiding the paper is arranged along the peripheral surface of the platen 16. Then, the paper feed tray 21 set on the lower front side of the recording apparatus.
The paper 24, which is a recording medium loaded on the rising tray 23 urged by the rising spring 22 of FIG. And guides to the peripheral surface of the platen 16.

A paper guide 28, which is a paper guide, is arranged near the paper exit of the platen 16 so as to face the carriage 4, and the paper 24 sent out from the platen 16 is pressed near the entrance of the paper guide 28. A paper retainer 29 is provided, and a paper discharge roller 31 and a spur roller 3 for discharging the paper 24 to a paper discharge tray 30 are provided near the exit.
2 are arranged.

Further, as shown in FIG. 1, the sub-scanning drive motor 34 is attached to the sub-frame 33 attached to the main scanning frame 1.
The motor gear 35 is attached to the rotary shaft of the sub-scanning drive motor 34, the idler gear 36 is meshed with the motor gear 35, and the idler gear 37 integrated with the idler gear 36 is meshed with the platen gear 38 attached to the end of the platen 16. Then, the rotation of the sub-scanning drive motor 34 is transmitted to the platen 16 and also to various rollers and rollers. By rotating the sub-scanning drive motor 34, the platen 16 and various rollers and rollers are rotated, and the paper 24 Is conveyed in the direction of arrow B (sub-scanning direction) on the paper guide 28.

With such a configuration, the recording head 5
While moving (scanning) the (carriage 4) in the main scanning direction,
A desired image is recorded on the paper 24 by conveying the paper 24 in the sub-scanning direction and ejecting ink droplets from the nozzles of the recording head 5.

As shown in FIG. 3, the recording head 5 has an ink jet head 5Y having a nozzle row 41Y composed of a plurality of nozzles 41 for ejecting yellow (Y) ink.
An inkjet head 5M having a nozzle row 41M for ejecting magenta (M) ink, an inkjet head 5C having a nozzle row 41C for ejecting cyan (C) ink, and a nozzle row 41K for ejecting black (K) ink are provided. Inkjet heads 5K, which are four inkjet heads, are connected to the nozzle rows 41Y, 41M,
41C and 41K are arranged in the main scanning direction on the carriage 4 so that 41C and 41K are arranged in the sub scanning direction.

Here, the ink jet heads 5Y, 5
As shown in FIG. 4, M, 5C, and 5K are provided with a nozzle plate 44 having a plurality of nozzles 41 formed on the front surface of a liquid chamber forming member 43 that forms a liquid chamber 42. By applying pressure to the ink in the liquid chamber 42 by an actuator, which is an energy generating means such as a heater, the ink in the liquid chamber 42 flies from the nozzle 41 of the nozzle plate 44 into an ink droplet 45 and is ejected onto the paper 24. Attach as dots. At this time, a desired image can be printed by selectively driving an actuator that applies pressure to each liquid chamber 42.

Next, the control section of this ink jet recording apparatus will be described with reference to FIG. This control unit corresponds to each of the microcomputer (hereinafter, referred to as “CPU”) 50 that controls the entire recording apparatus and each of the inkjet heads 5Y, 5M, 5C, and 5K of the recording head 5, and each has four units. Frame memories 51Y, 51M, 5
1C, 51K, line buffers 52Y, 52M, 52
C, 52K and head drivers 53Y, 53M, 53
C, 53K, a reception buffer 54 for receiving print data transferred from the host side, a color processing circuit 55 for separating print data into necessary color data, and an image for performing color boundary determination and replacement processing. Memory 56 and motor driver 5
7, 58 and the like.

Then, the print data received by the receive buffer 54 is processed by the color processing circuit 55, stored in the image memory 56, and subjected to the necessary discrimination and replacement processing.
Each frame memory 51Y, as print data of a required color,
It stores in 51M, 51C, and 51K. Of the printing data of each color stored in the frame memories 51Y, 51M, 51C and 51K, the data to be printed by one main scan is transferred to the line buffers 52Y, 52M, 52C and 52K.

Then, the line buffers 52Y and 52Y
From M, 52C to each inkjet head 5Y, 5M, 5
Data corresponding to the number of nozzles of C and 5K are sequentially read and given to the head drivers 53Y, 53M, 53C and 53K, so that the head drivers 53Y, 53M and 53C.
According to the print data, each inkjet head 5Y, 5
The M, 5C, and 5K actuators are driven to eject ink droplets of a desired color.

In this case, since the main scanning direction is the arrangement direction of the ink jet heads 5Y, 5M, 5C and 5K of the recording head 5 as described above, ink droplets of a plurality of colors are applied to the same printing dot position for each color. When landing with ink drops or when using black, each nozzle row 4
Inkjet heads 5C, 5M, 5Y are based only on the delay time obtained from the distance between 1Y, 41M, 41C and the main scanning speed, for example, with reference to inkjet head 5K.
The driving timing of each of the above is sequentially delayed by the delay time.

On the other hand, by rotating the main scanning motor 8 via the motor driver 57, the carriage 4 is reciprocated in the main scanning direction, and at the same time, the motor driver 58.
The sub-scanning motor 34 is rotationally driven via the platen 16
Is rotated to feed the paper 24 in the sub-scanning direction, whereby a color image corresponding to the recording data on the paper 24 is printed.

Next, the operation of this ink jet recording apparatus configured as described above will be described with reference to FIG. 6 and subsequent figures. First, in this ink jet recording apparatus, a high surface tension ink having a higher surface tension than other color inks (colors other than black) is used as the black ink, and the ink having a color other than black is more permeable or A penetrable ink having excellent dryness shall be used.

By using the high surface tension ink for the black ink and the ink penetrating ink of other colors in this way, it is possible to prevent feathering in text output and to record in other colors. It is possible to prevent the color mixture at the boundary between the colors in the color image area, and improve the image quality.

Here, as shown in FIG. 6, the black image area to be recorded using the black ink is the color image area to be recorded using the ink of a color other than the black ink (hereinafter,
Also referred to as "color image area". 7), when the black ink is a high surface tension ink and the other color inks (hereinafter referred to as “color inks”) are penetrating inks, as shown in FIG. The black dot DB recorded with the black ink overflows on the color dot CD recorded with the color ink to cause bleeding.

Therefore, in the present invention, as shown in FIG.
When a black image area recorded using black ink touches a boundary with a color image area, a small dot of 1 on the black image area side of the boundary is a complementary color of the color used in the color image area touching this black image area. Replace it with a dot of the color. That is, as shown in an enlarged view of the main part of FIG. 8 in FIG. 9, black dots BD recorded with black ink of high surface tension are used.
And a color dot CD recorded with a penetrating color ink
, And a complementary color dot SD of a color recorded with a penetrating color ink having a complementary color relationship with the color of the color dot CD is interposed between and.

At this time, since the color dot CD and the complementary color dot SD both use the penetrating ink, bleeding hardly occurs between these two dots CD and SD. Further, since these two dots CD and SD have a complementary color relationship to each other, the overlapping portion DD where the dots CD and SD overlap each other becomes black. On the other hand, between the black dot BD and the complementary color dot SD, the black dot B
Since D uses the high surface tension ink and the complementary color dot SD uses the penetrating ink, the black dot BD comes to bleed to the complementary color dot SD side.

In this case, since the complementary color dot SD exists in the black image area, the black dot BD bleeds, and the one portion of the complementary color dot CD is in contact with the black of the overlapping portion DD of the color dot CD and the complementary color dot SD. It is preferable that it is reduced.

Therefore, a first example of the replacement process performed by the control unit will be described with reference to FIG. In this replacement process,
After the image data of at least the data amount that can reflect the color boundary portion is fetched and expanded and stored in the image memory 56, the black image area to be recorded with the black ink is in contact with another color (color) image area to be recorded with the color ink. Or not. When the black image area touches the boundary with the color image area (when there is a boundary), 1 on the black image area side is set.
The dots are replaced with dots of a color that is a complementary color of the color used in the color image area, and the dots are developed as print data in a required frame memory.

After that, it is judged whether the replacement of the data expanded in the image memory 56 is completed, and if the replacement is completed, it is judged whether there is no data in the reception buffer.
If data remains in the receive buffer, the above process is repeated. If no data exists in the receive buffer, this replacement process ends.

As described above, when the black image area touches the boundary with the color image area, at least one dot on the black image area side of the boundary becomes a complementary color of the color used in the color image area which touches the black image area. By substituting the color dots for the high surface tension ink, it is possible to prevent the black ink from seeping out to the color image area recorded by the adjacent penetrating ink even when the black ink is used. Further, since the time difference printing or the like is not performed, the printing speed does not decrease, and the processing such as thinning is not performed, so that white spots or white streaks do not occur and the image quality does not deteriorate.

Next, a second example of the replacing process will be described with reference to FIG. In this replacement process, when the color used in the color image area adjacent to the black dot is a specific color, the color is replaced with a color including the complementary color instead of the complementary color itself of the other color.

That is, when the black dots are replaced with the complementary color dots as described above, depending on the environmental temperature and the paper quality,
There is a possibility that the original color of the complementary color dots may be partially exposed because the black dots do not sufficiently spread on the complementary color dots. At this time, if the color dots in the color image area bordering the black image area are primary colors such as yellow, magenta, and cyan, the complementary color dots are likely to have a higher density than blue, green, red, in other words,
Since it is a color with low lightness, it is hardly noticeable by adjoining black with the lowest lightness, and since it is a secondary color generated by superimposing two colors of ink, the amount of ink per dot also increases and black ink Is more easily drawn in, and the number of areas where the complementary color dots remain alone is reduced.

On the contrary, in the case of a combination in which the complementary color dots are cyan, magenta, and yellow, which have relatively high lightness, the adjacent dots are secondary colors, and the complementary color dots are more than usual. Since it overflows, the area where the complementary color dots remain alone is reduced.

On the other hand, depending on the color, there are some colors that are sufficiently conspicuous even if there are few overlapping portions remaining. For example,
When the color dots are blue and the complementary color dots are yellow, the combination of yellow and black is originally very conspicuous, and the combination of yellow and blue is also relatively conspicuous. May be done.

Therefore, in this replacement processing, it is determined whether or not the black image area borders the color image area in the processing of FIG. 10, and when the black image area borders the color image area. The color (other color) is also discriminated, and when there is a boundary, it is discriminated whether or not the color (other color) used in the color image area is blue, and when the other color is blue, the black image area is determined. One dot on the side is replaced with a red (or green) dot, and when the other color is other than blue, one dot on the side of the black image region is replaced with a dot of a color that is a complementary color of the color used in the color image region. .

As described above, when the color used in the color image area in contact with the black image area is blue, the black dot is replaced with the red or green dot containing yellow. It is possible to prevent the overlap remaining portion from being conspicuous, and it is possible to suppress deterioration of image quality.

Next, a third example of the replacing process will be described with reference to FIGS. 12 and 13. This third example refers to the neighboring 8 dots for each dot of black image data,
When there are one or more and less than four dots of a color (color) other than black, the dots of the black image data of interest are replaced.

That is, the image having the boundary portion printed by the recording apparatus is various from a block diagram having a clear boundary to a gradation image having a photograph or a gradation such that the boundary is not clear. There is. Therefore, when there is a black image area in contact with the color image area, if the process of always replacing one dot on the black image area side is performed, the color tone itself changes, which may cause a significant image deterioration. There is. In particular, there may be a case where there is no dot to be replaced with a complementary color dot, for example, in a portion where a halftone is expressed by a set of isolated dots instead of solid black. Also, the boundary is determined for all these isolated points,
If the dot replacement process is performed, it takes a long time.

Therefore, in this replacement process, data is read from the reception buffer and it is determined whether or not the data is black data (black image data). If it is not black data, the process is terminated and the black If it is data, pay attention to each dot of black data,
As shown in FIG. 13, data of 8 dots to 8 in the vicinity of the focused dot is sequentially referred to, and when the data is a color dot other than black, the counter is incremented (+1) to count the number of color dots.

When the reference of the data of 8 dots to the vicinity of the focused dot is completed, whether or not the count of the number of color dots is "1" or more, that is, whether there is a colored dot in the vicinity of the focused black dot. If there is a color dot, it is determined whether the count value is less than "4". In other words, the 8
It is determined whether or not the dots ~ include one or more and less than four color dots.

At this time, when there are one or more and less than four color dots, the noted black dot is replaced with a complementary color dot, and when there are four or more color dots, the black dot is directly replaced without replacement. To do. Further, when there is no color dot, the noted dot is a dot that does not touch the boundary with the color image area, and therefore replacement is not performed. Then, if the reference to the black image data is completed and there is no data in the reception buffer, the process is replaced.

By doing so, it is possible to speed up the process and prevent the image quality from being deteriorated due to a change in color tone. It should be noted that, as described in the second example described above, it is possible to determine whether the color dot is blue or not, and replace the dot to be replaced with red or green when it is blue.

Next, a fourth example of the replacing process will be described with reference to FIG. In the fourth example, the dots of the black image data noticed in the third example are replaced with the complementary color of the largest number of the dots of colors other than black included in the eight dots in the vicinity thereof. It was done.

That is, referring to the figure, similarly to the third example, for each dot of the black image data, the data of 8 dots to 8 dots in the vicinity thereof are sequentially referred to. If it is a dot, the number of color dots is counted for each color. Then, when the reference for 8 dots is completed, it is determined whether or not there are one or more and less than 4 color dots other than black. If there are 1 or more and less than 4 color dots, the color dot is determined. The most frequent color is extracted by checking the count value of each color dot, and the focused black dot is replaced with the complementary color dot of the extracted color.

By doing so, the processing speed can be increased, the change in the color tone can be further suppressed, and the deterioration of the image quality can be further reduced.

Next, a fifth example of the replacing process will be described with reference to FIG. In the fifth example, when all the color dots other than black included in the neighboring 8 dots in the third example have different colors, the replacement is not performed.

That is, referring to FIG.
Similarly, for each dot of the black image data, the count value for each color of the color dots other than black is obtained for the 8 dots in the vicinity of each dot, and 1 or more and less than 4 color dots are provided in the 8 dots in the vicinity of the focused black dot. When present,
Check the count value of each color dot to determine if they are all different colors. If they are all different colors,
The target black dot is not replaced and the process proceeds to the next process.

By doing so, the processing speed can be increased, the change in the color tone can be further suppressed, and the deterioration of the image quality can be further reduced.

[0068]

As described above, according to the ink jet recording apparatus of the first aspect, the black image area to be recorded using the black ink is a boundary with the color image area to be recorded using the ink of another color. And a determination unit that determines whether the black image region contacts the color image region in accordance with the determination result of the determination unit. Since a replacement unit that replaces a dot of a color that is a complementary color of the color used in the color image image area in contact with the area is provided, bleeding can be prevented,
By not thinning out, white gaps and white lines do not occur,
Image quality is improved.

According to the ink jet recording apparatus of the second aspect, in the ink jet recording apparatus of the first aspect,
The discriminating means includes means for discriminating whether or not the color used in the color image area in contact with the black image area is blue, and the replacing means determines that the color used in the color image area is blue according to the result of the discrimination. In this case, since the means for replacing with red or green is provided, it is difficult to recognize as a color streak even if there is a portion without replacement dot bleeding, and it is possible to suppress deterioration of image quality.

According to the ink-jet recording apparatus of the third aspect, in the ink-jet recording apparatus of the first or second aspect, the discriminating means refers to the neighboring 8 dots for each dot of the black image data, and refers to the dots of other colors. 1 or more 4
If there are less than one and less than four dots of another color exist within the eight dots in the vicinity of the dot of the black image data of interest according to this determination result. Since the dot of the noted black image data is replaced, the processing speed can be improved and the change in color tone due to careless replacement can be reduced.

According to the ink jet recording apparatus of the fourth aspect, in the ink jet recording apparatus of the third aspect,
The discriminating means is provided with means for extracting the largest number of other color dots included in the eight dots in the vicinity of the focused black image data dot, and the replacing means pays attention according to the extraction result. Since the configuration is provided with means for replacing the dots of the black image data with the dots of the largest number of colors, it is possible to improve the processing speed and further reduce the change in color tone due to careless replacement.

According to the ink jet recording apparatus of the fifth aspect, in the ink jet recording apparatus of the fourth aspect,
The discriminating means is provided with means for discriminating whether or not all the dots of other colors included in the eight dots in the vicinity of the focused black image data dot are dots of different colors, and the replacing means responds to this discrimination result. When the other color dots are all different color dots, the configuration is provided so as not to replace the dot of the focused black image data, so that the processing speed can be improved and careless replacement can be achieved. It is possible to further reduce the change in color tone due to.

According to the ink jet recording apparatus of the sixth aspect, in the ink jet recording apparatus according to any one of the first to fifth aspects, an ink of another color which is superior in penetrability or drying property to the black ink is used. With this configuration, it is possible to prevent color mixture at the boundary between the colors in the color image area and improve the image quality.

According to the ink jet recording apparatus of the seventh aspect, in the ink jet recording apparatus according to any one of the first to sixth aspects, the black ink having a higher surface tension than the inks of other colors is used. Feathering in text output can be prevented.

According to the eighth aspect of the ink jet recording method, it is determined whether or not the black image area recorded using the black ink is in contact with the color image area recorded using the other color ink. , When the black image area touches the boundary with the color image area, at least one dot on the black image area side of the boundary is replaced with a dot having a color complementary to the color used in the color image area touching the black image area. With this configuration, it is possible to prevent bleeding, and by not performing thinning or the like, white spots and white lines are not generated and the image quality is improved.

According to the ink jet recording method of claim 9, in the ink jet recording method of the above item 8,
It is determined whether or not the color used in the color image area in contact with the black image area is blue, and when the color used in the color image area is blue, it is replaced with red or green. Even if a portion without bleeding remains, it is difficult to recognize as a color stripe, and it is possible to suppress deterioration of image quality.

According to the ink jet recording method of the tenth aspect, in the ink jet recording method of the eighth or ninth aspect, the neighboring eight dots of the individual dots of the black image data are used.
By referring to the dots, it is determined whether or not there are one or more and less than four dots of other colors, and one or more dots of other colors are present within the eight dots near the noted black image data dot. When there are less than 4 dots, the dot of the noted black image data is replaced, so that the processing speed can be improved and the change in color tone due to careless replacement can be reduced.

According to the ink jet recording method of the eleventh aspect, in the ink jet recording method of the tenth aspect, the highest number among the dots of other colors included in the eight dots in the vicinity of the dot of the black image data of interest. Since many colors are extracted and the dots of the black image data of interest are replaced with the extracted dots, the processing speed can be improved and the change in color tone due to careless replacement can be further reduced. it can.

According to the ink jet recording method of the twelfth aspect, in the ink jet recording method of the eleventh aspect, all the other color dots included in the eight dots in the vicinity of the focused black image data dot are of different colors. It is determined whether or not it is a dot, and when all the dots of other colors are dots of different colors, the configuration does not replace the dot of the noted black image data, so that the processing speed can be improved and It is possible to further reduce the change in color tone due to careless replacement.

According to the ink jet recording method of the thirteenth aspect, in the ink jet recording method according to any one of the eighth to twelfth aspects, an ink of another color which is superior in penetrability or drying property to the black ink is used. With this configuration, it is possible to prevent color mixture at the boundary between the colors in the color image area and improve the image quality.

According to the ink jet recording method of the fourteenth aspect, in the ink jet recording apparatus according to any one of the eighth to thirteenth aspects, the black ink having a higher surface tension than the inks of other colors is used. Feathering in text output can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic plan view of an inkjet recording apparatus to which the present invention is applied.

FIG. 2 is a schematic side view of the recording apparatus.

FIG. 3 is a schematic perspective view showing an example of the recording head.

FIG. 4 is an enlarged sectional view of a main part of the recording head.

FIG. 5 is a block diagram of a control unit of the inkjet recording apparatus.

FIG. 6 is an explanatory diagram for explaining a boundary portion between a black image area and a color image area.

FIG. 7 is an explanatory diagram illustrating a state in which a boundary blur occurs at the boundary portion.

FIG. 8 is an explanatory diagram for explaining a case where a replacement process is performed on the same boundary portion.

FIG. 9 is an explanatory diagram for explaining an enlarged boundary portion when the same replacement process is performed.

FIG. 10 is a flowchart showing a first example of replacement processing performed by a control unit.

FIG. 11 is a flowchart showing a second example of replacement processing performed by the control unit.

FIG. 12 is a flowchart showing a third example of replacement processing performed by the control unit.

13 is an explanatory diagram for explaining FIG. 12;

FIG. 14 is a flowchart showing a fourth example of replacement processing performed by the control unit.

FIG. 15 is a flowchart showing a fifth example of replacement processing performed by the control unit.

FIG. 16 is an explanatory diagram illustrating a state of adjacent dots when using normal ink.

FIG. 17 is an explanatory diagram illustrating a state of adjacent dots when a permeable ink is used.

FIG. 18 is an explanatory diagram illustrating a state of adjacent dots when a permeable ink and a high surface tension ink are used.

[Explanation of symbols]

1 ... Main scanning frame, 2 ... Front guide, 3 ... Guide shaft, 4 ... Carriage, 5 ... Recording head, 8 ... Main scanning motor, 16 ... Platen, 24 ... Paper, 28 ... Paper guide.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04N 1/46 H04N 1/46 Z

Claims (14)

[Claims] 1. In a color ink jet recording apparatus capable of using a black ink having different penetrability or fixability to a recording medium from inks of other colors, a black image area recorded using the black ink is different from the black image area. When the black image area contacts the color image area and the boundary according to the result of the determination by the determination means that determines whether or not the boundary is in contact with the color image area to be recorded using the color ink, Ink jet recording, comprising at least one dot on the black image area side of the boundary, which is replaced with a dot of a color that is a complementary color of a color used in the color image image area in contact with the black image area. apparatus. 2. The ink jet recording apparatus according to claim 1, wherein the determining means includes means for determining whether or not a color used in a color image area in contact with the black image area is blue, and the replacing means. The ink jet recording apparatus is provided with means for substituting red or green when the color used in the color image area is blue according to the result of this discrimination. 3. The ink jet recording apparatus according to claim 1 or 2, wherein the determining unit refers to 8 dots in the vicinity of each dot of the black image data, and one or more dots of other colors are 4 or more. When there is one or more and less than four dots of another color within the eight dots in the vicinity of the black image data dot of interest, according to the result of this determination. An inkjet recording apparatus, characterized in that the dots of the noted black image data are replaced. 4. The ink jet recording apparatus according to claim 3, wherein the discriminating unit has the largest number of other color dots included in 8 dots in the vicinity of the noted black image data dot. The inkjet recording apparatus is characterized in that the replacing means comprises means for replacing the dots of the focused black image data with the dots of the largest number of colors in accordance with the extraction result. 5. The ink jet recording apparatus according to claim 4, wherein the determination unit determines that all the other color dots included in the eight dots near the noted black image data dot are different color dots. And a means for not replacing the noted black image data dot when the replacement means is a dot of a different color according to the result of this determination. An inkjet recording device characterized by the above. 6. The ink jet recording apparatus according to any one of claims 1 to 5, characterized in that an ink of another color having a higher permeability or drying property than the black ink is used. apparatus. 7. The ink jet recording apparatus according to claim 1, wherein a black ink having a higher surface tension than inks of other colors is used. 8. In a color ink jet recording apparatus capable of using a black ink having different penetrability or fixability to a recording medium from inks of other colors, a black image area recorded by using the black ink is different from the other one. It is determined whether or not a boundary is in contact with a color image area to be recorded using color inks, and when the black image area is in contact with the color image area, at least one dot on the black image area side of the boundary is determined. Is replaced with a dot of a color that is a complementary color of the color used in the color image area adjacent to the black image area. 9. The ink jet recording method according to claim 8, wherein it is determined whether or not the color used in the color image area in contact with the black image area is blue, and the color used in the color image area is determined. An ink jet recording method characterized in that when is blue, it is replaced with red or green. 10. The ink jet recording method according to claim 8 or 9, wherein for each dot of the black image data, by referring to the neighboring 8 dots, there are one or more and less than 4 dots of another color. It is determined whether or not there is one or more and less than four dots of another color in the 8 dots near the dot of the focused black image data, and the dot of the focused black image data is replaced. Characteristic inkjet recording method. 11. The ink jet recording method according to claim 10, wherein the largest number of dots of other colors included in 8 dots in the vicinity of the noted black image data dot is extracted, An ink jet recording method, wherein the noted black image data dot is replaced with the extracted color dot. 12. The ink jet recording method according to claim 11, wherein it is determined whether or not all the dots of other colors included in the eight dots in the vicinity of the noted black image data dot are dots of different colors. An ink jet recording method, characterized in that the dots of the black image data of interest are not replaced when the other color dots are all different color dots. 13. The ink jet recording method according to any one of claims 8 to 12, characterized in that an ink of another color having a higher permeability or drying property than the black ink is used. Method. 14. The inkjet recording method according to claim 8, wherein a black ink having a higher surface tension than the other color inks is used.