JP3058238B2 - Color inkjet recording method and recording apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color ink jet recording method and a recording apparatus capable of recording a color image with a clear and high density. More specifically, the present invention relates to a color ink such as yellow, magenta or cyan and a black ink. The present invention relates to a color ink jet recording method and a recording apparatus used.

[0002] The present invention relates to paper, cloth, nonwoven fabric, and OHP.
The present invention can be applied to all devices using a recording medium such as paper, and specific devices include office equipment such as printers, copiers and facsimiles, and mass production equipment.

[0003]

2. Description of the Related Art Ink jet recording methods are used in printers, copier facsimile machines, and the like because of their low noise, low running cost, easy downsizing of their apparatuses, and easy colorization.

When an ink jet recording method is applied to a color recording apparatus, it is necessary to use "special paper" having an absorption layer in order to obtain a high-color image without bleeding of ink. In recent years, inks having improved printability on “plain paper” by improving ink have been put to practical use. However, at present, the print quality on “plain paper” is still at an insufficient level.
The biggest factors are the bleeding of the ink between the colors and the black recording quality (especially black character recording quality).
It is compatible.

[0005]

Generally, when a color image is obtained on plain paper by an ink jet recording method, a quick-drying ink having a high penetration rate into plain paper is used. For this reason, the color image portion becomes a high-quality image with no ink bleeding between colors, but the black image portion has a low density, and so-called feathering, in which ink bleeds along the paper fibers, occurs.

For example, in the case where a black image is present in the background of a color image portion, the above-mentioned problem of the black image portion is relatively inconspicuous and does not significantly lower the quality. If it exists independently of the image part, the quality will be degraded. Further, when the black image is a character, the character becomes indistinct because the image is unclear and lacks sharpness.

In order to obtain a high-quality image in which the density of the black image portion is high and feathering does not occur, it is necessary to eject ink having a relatively low penetration rate into plain paper to some extent. However, in this case, bleeding of the black ink and the color ink occurs at the adjacent boundary between the black image portion and the color image portion, and the quality is significantly deteriorated.

Although the problem relating to ink bleeding can be improved to some extent by the so-called fine mode in which an image is formed by dividing the image into a plurality of main scans, the problem of the black image quality has not been essentially solved. is the current situation.

Therefore, the present applicant has filed a Japanese Patent Application No. Hei 4-20554.
No. 8, Japanese Patent Application No. 4-293022, and the like, a method for preventing bleeding in the boundary area between black and color by forming a black area along the boundary area between black and color by overprinting color ink. Proposed. The black formed using the color ink in this manner is referred to as PCBk (Process Color Bk). In this method, the color tone of a black portion formed by the color ink and a portion formed by mixing black and color at a certain ratio becomes a problem.

In the above-mentioned method of replacing Bk at the boundary with PCBk, the simplest method is to apply a specific mask pattern when replacing black data with color data. One example is shown in FIG. this is,
This is a replacement mask pattern when 100% of Bk is replaced at a ratio of Bk to 50% C to 50% M to 25% Y to 50%. The PCBk formed at this ratio has a color tone of Bk10
It is set to be close to 0%.

However, it is not possible to make the colors exactly the same. Therefore, in the boundary portion, the portion where the PCBk is replaced and the portion where 100% of Bk are adjacent to each other are:
The difference in the color tone becomes uncomfortable and is recognized by the user, resulting in an adverse effect on the image quality at the boundary between the black image and the color image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is an object of the present invention to record a black image area in contact with a color image area, thereby suppressing color blur without changing color tone. It is an object to provide a recording method and a recording device.

Furthermore, not only excellent recording quality with no ink bleeding between black and each color but also excellent recording quality with little feathering in a black image area, that is,
It is an object of the present invention to provide a color inkjet recording method and a recording apparatus which can realize both high-quality black recording and high-quality color recording.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a color ink jet recording method and a recording apparatus, wherein a color ink jet recording method and a color ink jet recording method are used. In the process of generating the multi-valued black recording data indicating the black density, the multi-valued black recording data corresponding to the determination target pixel is generated based on the multi-valued color recording data corresponding to the determination target pixel, and the determination target pixel is generated. When the multi-valued color print data corresponding to surrounding pixels indicates a color image, the ratio of generating multi-valued black print data corresponding to the pixel to be determined is changed to be low.

Further, according to the present invention, the multi-valued black print data is generated from the multi-valued color print data corresponding to the pixel to be determined, and the multi-valued color print data of pixels surrounding the pixel to be determined is determined. The multi-valued black print data of the determination pixel is converted into the multi-valued color print data according to the determination result of the multi-valued color print data of the surrounding pixels.

[0016]

According to the above arrangement, the amount of Bk data generated from color data for one pixel can be changed in accordance with information on surrounding pixels, so that bleeding and changes in color tone are not noticeable. The recording data can be formed at the same time.

That is, in the present invention, since the recording data is handled as multi-valued information, the Bk data amount gradually changes at the boundary between the color image and the black image, so that the color tone change is not noticeable. Also, the bleeding is not conspicuous because the boundary between the color and Bk is hardly generated.
As a result, a smoother boundary can be formed.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the premise of each embodiment will be described.

FIG. 1 is a perspective view of a recording apparatus which carries out the ink jet recording method of the present invention. The carriage 101 has a recording head 102 and a cartridge guide 103 mounted thereon, and can scan on guide shafts 104 and 105.

The recording paper 106 is fed into the main body by a paper feed roller 107, is sandwiched by a paper feed roller 108 and a pinch roller (not shown), and is fed to the entire surface of the paper feed roller 108 by a paper pressing plate 109 to be printed. You. There are two types of ink cartridges, a color ink cartridge 110 containing three colors of yellow, magenta, and cyan, and a black ink cartridge 111, which are separately inserted into the cartridge 103 and communicate with the recording head 102.

The yellow, magenta, and cyan inks contained in the color ink cartridge 110 have a high permeation rate to the recording paper so as to prevent ink bleeding at a color boundary when a color image is formed. Used. On the other hand, the black (black) ink stored in the black ink cartridge 111 is relatively higher in recording paper than the above three types of color inks, so that a black image has a high density and a high quality with little ink bleeding. A material having a low permeation rate is used.

FIG. 2 shows the recording head 102. On the front surface of the recording head 102, ejection port groups for yellow, magenta, cyan, and black are arranged in a straight line. Each group has 24 ejection openings for yellow, magenta, and cyan, and 64 ejection openings for black, and the interval between colors is equal to or greater than the nozzle pitch.

Each of these discharge ports is provided with an ink liquid path communicating with the discharge port, and a common liquid for supplying ink to these liquid paths is provided behind the portion where the ink liquid path is provided. A room is provided. An ink liquid path corresponding to each of the discharge ports is provided with an electrothermal converter that generates thermal energy used for discharging ink droplets from these discharge ports and an electrode wiring for supplying power thereto. ing. These electrothermal transducers (discharge heaters) and electrode wires are formed by a film forming technique on a 201 substrate made of silicon or the like. Further, on this substrate, a resin, a partition made of a glass material,
The discharge port, the ink liquid path, and the common liquid chamber are formed by stacking a top plate and the like. Further behind, a drive circuit for driving the electrothermal transducer based on a recording signal is provided in the form of a printed circuit board.

Alternatively, a grooved top plate (orifice plate) provided with partitions for partitioning a plurality of ink flow paths, a common liquid chamber, and the like, and the substrate are stuck together without using the glass material. It may be configured to be formed. The grooved top plate is integrally molded, and the integral molding material is preferably polysulfone, but other molding resin materials may be used.

The silicon substrate and the printed circuit board 202 are parallel to the same aluminum plate 203,
Reference numerals 04 to 207 protrude from a plastic member 208 called a distributor extending in the vertical direction with respect to the silicon substrate, and further communicate with an internal flow path, which communicates with a common liquid chamber.

There are four flow paths in the distributor, one for yellow, one for magenta, one for cyan, and one for black, which connect the respective common liquid chambers and pipes.

Although the present embodiment uses a configuration in which the ink tanks can be replaced independently for the color ink and the Bk ink, a disposable recording head in which the ink tank and the print head are integrated may be used. .

The ejection openings for yellow, magenta, and cyan provided on the recording head 102 are approximately 40 ng.
Is about 80n from the black orifice
g of ink is ejected.

The components of the ink used in this embodiment are as follows. 1. Y (yellow) C.I. I. Direct Yellow 86 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetylenol EH (Kawaken Chemical) 1 part Water remaining part 2. M (magenta) C.I. I Acid Red 289 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetylenol EH (Kawaken Chemical) 1 part Water balance 3 C (cyan) C.I. 3. I Direct Blue 199 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Acetylenol EH (Kawaken Chemical) 1 part Water remaining part 4. Bk (black) C.I. I Direct Black 154 3 parts Diethylene glycol 10 parts Isopropyl alcohol 2 parts Urea 5 parts Water balance

As described above, the penetration of cyan, magenta, and yellow is improved by adding 1% of acetylenol EH to black. The addendum is
In addition, there are other surfactants and alcohols.

FIG. 3 is an electric control block diagram of the above-described color ink jet printer.

Reference numeral 301 denotes a system controller for controlling the entire apparatus, and a storage element (RO) storing therein a control program including a microprocessor.
M), a storage element (RAM) used when the microprocessor performs processing, and the like are arranged. 302, a driver for driving the print head in the main scanning direction;
Similarly, reference numeral 303 denotes a driver for moving in the sub-scanning direction. Reference numerals 304 and 305 denote motors corresponding to the driver, which operate by receiving information such as speed and moving distance from the driver.

Reference numeral 306 denotes a host computer, which is a device for transferring information to be printed to the printing device of the present invention. Reference numeral 307 denotes a reception buffer for temporarily storing data from the host computer 306, and accumulates data until data is read from the system controller 301. A frame memory 308 expands data to be printed into image data, and has a memory size necessary for printing. In this embodiment, a frame memory capable of storing one print sheet will be described, but the present invention is not limited to the size of the frame memory.

Reference numeral 309 denotes a storage element for temporarily storing data to be printed, and the storage capacity varies depending on the number of nozzles of the print head. Reference numeral 310 denotes a print control unit for appropriately controlling the print head according to a command from the system controller, and for controlling the ejection speed, the number of print data, and the like. Reference numeral 311 denotes a nozzle (head) 312Y for discharging yellow ink, a nozzle (head) 312M for discharging magenta ink, and a nozzle (head) 312 for discharging cyan ink.
C, nozzle (head) 31 for discharging black ink
A driver for driving 2Bk is controlled by a signal from the print control unit 310.

(Image Processing) Next, an image processing function for outputting image data to be printed by the recording apparatus will be described. As shown in the block diagram of FIG. 4, the image processing function 500 includes the following five functions.

(1) Input γ conversion 501 (2) UCR (Under Color Remove) and black generation 502 (3) Masking 503 (4) Output γ conversion 504 (5) Halftone processing 505

As a function other than such image processing, there is a function having a function of enlarging image data. In the present embodiment, as shown in an example of an overall block diagram in FIG. 5, a plurality of input data formats are supported, and two input interfaces, SCSI 604 and Centro 605, are also provided.

In addition to the image processing section 500, a SCSI control section 606, an input / output control section 607, memories 608, 608 for two rasters toggling, and a CPU for controlling them.
602, program memory 601 and work memory 6
03. The work memory 603 includes an output buffer for storing data binarized by the image processing unit 610.

(1) Input γ Conversion In general, color image data used by a computer expresses its color by R, G, B intensity (light intensity). Also,
In the printing apparatus, the same color is represented by ejection amounts (densities) of cyan (C), magenta (M), and yellow (Y), which are complementary colors to R, G, and B. Therefore, it is necessary to convert the R, G, B data input from the computer into C, M, Y density data by some method. Since the density can be obtained by logarithmic conversion of the reciprocal of the reflectance, the reciprocal of R, G, B (light amount) data is logarithmically converted to density data. Assuming that the converted density data is C, M, and Y, respectively, the conversion equation is as shown in equation (1).

C = −255 / a _r · log (R / 255) M = −255 / a _g · log (R / 255) (1) Y = −255 / a _b · log (R / 255) In order to reproduce the image displayed on the display, it is necessary to convert the picture as shown in the following equation (1 ') in order to compensate for the non-linearity of the picture tube.

C = −255 / a _r · log (R ^2.2 / 255) M = −255 / a _g · log (R ^2.2 / 255) (1 ′) Y = −255 / a _b · log ( R ^2.2 / 255) (However, 0 ≤ R, G, B, C, M, Y ≤ 255, a _r , a _g , a _b are constants)

In practice, this logarithmic conversion function is performed in advance by (1)
The value calculated by the equation or the equation (1 ′) is L. U. T
(Look Up Table), and as shown in FIG. 6, the densities (C, M, and C) corresponding to the inputs (R, G, and B).
Y) is output.

(2) UCR and black generation The UCR is defined as a ratio of achromatic color components that do not contribute to color from the respective values of C, M, and Y obtained by the above formula (1) or (1 '). To get rid of it. Black generation is the addition of black at some rate to compensate for the achromatic color that has been removed. FIG. 7 shows the state of UCR and black generation.

FIG. 7A shows the respective concentrations of C, M, and Y obtained by the above equation (1) or (1 ') and the UCR at that time (in this case, 70% of the minimum value Y). Is shown). On the other hand, FIG. 7B shows the respective densities of C ′, M ′, Y ′, and K ′ after performing the UCR and black generation in FIG. In the example, the amounts of UCR and black generation are each 70% of the achromatic color component G, but these amounts are usually determined empirically. The ink densities after UCR and black generation are as shown in equation (2).

C ′ ← C−α _u · min (C, M, Y) M ′ ← M−α _u · min (C, M, Y) (2) Y ′ ← Y−α _u · min (C, M, Y) K '← α _s・ min (C, M, Y)

Here, min (C, M, Y) indicates the minimum value of C, M, Y obtained by the equation (1) or (1 '). α _u is a UCR amount, and α _s is a coefficient for determining a black generation amount.

As described above, there are two main reasons for using black ink in color printing. 1. The higher density portion is made darker than in the case where only the three colors of cyan, magenta and yellow are expressed, and more excellent gradation is obtained. 2. Reduce the amount of ink ejected on the recording paper.

(3) Masking C, M, and Y inks, which have complementary colors with R, G, and B, ideally absorb only R for C ink, only G for M ink, and only B for Y ink. is there. However, real ink does not have such ideal absorption characteristics, and C ink absorbs not only R but also G and B to a large extent. Other inks also absorb colors other than the complementary colors. Masking corrects these unnecessary absorptions, and the correction formula is (3)
It is shown in the formula.

[0049] _{C '= P 11 · C +} P 12 · M + P 13 · Y M' = P 21 · C + P 22 · M + P 23 · Y ··· (3) Y '= P 31 · C + P ₃₂ · M + P ₃₃ · Y Parameters P _{11 to} P used in equation (3)
₃₃ is the color of the input image represented by R, G, B, C ′,
The determination is made such that the difference between the color reproduced by M ′ and Y ′ is minimized.

Next, an example of UCR, black generation and masking performed in the present embodiment is shown in equation (4).

[0051] _{C '= P 11 · C +} P 12 · M + P 13 · Y + P 14 · Bk + P 15 · Bk 2 M' = P 21 · C + P 22 · M + P 23 · Y + P ₂₄・ Bk + P ₂₅・ Bk ²・ ・ ・ (4) Y '= P ₃₁・ C + P ₃₂・ M + P ₃₃・ Y + P ₃₄・ Bk + P ₃₅・ Bk ² K ′ = P ₄₁・ C _{+ P 42 · M + P 43} · Y + P 44 · Bk + P 45 · Bk 2 , provided that Bk = min (C, M, Y). Also (4)
The equation takes into account the second order term of Bk (Bk ² ). This term has little effect in the highlight portion of the image data, and its effect becomes large in the high density portion. Usually, UCR and black generation are not performed in a bright portion of an image, but are performed in a portion having a certain density or higher. By using this Bk ² term, the above-described effects can be obtained.

(4) Output γ conversion The output γ conversion function includes the ink densities C ′, M ′, Y ′, and K ′ obtained by the aforementioned UCR, black generation and masking functions.
And synthesizes three tables of gradation correction, brightness adjustment, and color balance.

In the gradation correction, correction is performed so that the recording density becomes linear. Normally, the gradation characteristics of the recording density vary depending on the type of ink used, the size of ink droplets, the type of recording paper, and the method of the pseudo intermediate gradation processing. The correction method is simple. An input density correction table is created in advance so that the recording density becomes linear, and the ink densities C ′, M ′, Y ′, and K ′ obtained by the color correction function are used. Correction is performed using this correction table. Then, the corrected ink densities C ", M", Y ", and K" are input to the pseudo halftone processing. This correction table is prepared for each color. FIG.
(A) shows the gradation characteristics of the recording density without correction.
FIG. 8B shows a correction (conversion) table in that case.

In the brightness adjustment, the brightness of the recording density is adjusted, and each ink density is uniformly converted as shown in FIG. The color balance converts the ink density independently for each color.

(5) Halftone processing The halftone processing function performs pseudo halftone processing for expressing a grayscale image by the number of dots per unit area. Here, for the multi-valued C ″, M ″, Y ″, K ″ data, the binary c,
m, y, and k data are output. This binary data is shown in FIG.
Print data 308. The pseudo halftone processing method includes a well-known dither method and an error diffusion method.
The error diffusion method is often used recently because excellent gradation characteristics can be obtained without reducing the apparent resolution.

(Embodiment 1) As a first embodiment, UCR
A case where the rate of black generation in the processing and black generation is changed according to the surrounding density data will be described.

By UCR processing and black generation, C,
Although the density data of M, Y, and K is determined, in the present embodiment, the amount considered as the UCR during the UCR process is changed according to the surrounding density data. That is, α _u and α _s in the equation (2) are functions having surrounding density data (C, M, Y) as parameters.

The manner in which the UCR amount is determined by focusing on a certain pixel will be described with reference to FIG. In FIG. 10, the pixel whose address is 22 is determined. First, density data at a pixel around the determination pixel, for example, address: 11, that is, each value of C, M, and Y obtained by the equation (1) or (1 ′) is fetched. When the UCR process and the black generation are performed, when the three values are close to each other, there are many portions that become black, and few portions remain as components of the color (C, M, Y).
If they are equal, they are all replaced with black. Therefore, the data of black characters and the like have the maximum density for all colors, and are replaced with black because the densities are equal.

Further, the density of the part without data, that is, the white part is equal because the density is all 0, but black is not generated. On the other hand, if the color data is a primary color, only one of C, M, and Y exists, and black is not generated. Also in the case of a secondary color, only two colors of C, M, and Y exist, and black is not generated. Therefore, it can be assumed from the respective density data of C, M, and Y whether the pixel is black, color, or not printed.

From the above, it can be assumed from the density data at address: 11 what color component the pixel will be. Similarly, surrounding pixels can be assumed from the density data by further shifting the address. Here, since the surrounding color components are known, it is possible to set an optimal value for how much black may be generated in the determination pixel, that is, the ratio of the amount of black generation.

FIG. 11 shows a sequence for changing the black generation amount of the judgment pixel, assuming the color components of the surrounding pixels. First, in Step-1, density data of a determination pixel and surrounding pixels is fetched. In this case, the amount to be taken can be set according to the range to be determined, but the determination can be made with data of at least one dot around the dot.

Next, the color components of the surrounding pixels are determined in Step-2. It is assumed that the color component of the pixel is subjected to the UCR process and the black generation process from each density data. According to the color components, the ratio G of the black generation amount is determined in Steps 3 to 5. Black portion in FIG. 11, the white portion, is divided into three color portions, if even one color pixel among the peripheral pixels, selects the G _c (Step-3). If there is no color pixel in the surrounding pixels and at least one black pixel exists, _Gb is selected (Step-4). If neither a color pixel nor a black image exists, _Gw is selected as a white portion (Step-5). Then, in Step-6, St
UCR processing and black generation processing are performed according to the ratio of the black generation amount determined in ep-3 to ep-5.

[0063] G _b is set to be the maximum value (all replaced with black). Thus, the quality of a single black character or the like is not impaired. G
_c is varied according to the amount of surrounding color pixels. If the amount of color pixels is large, G _c will decrease,
If the number of color pixels is small, G _c will be large. Also,
G _w is determined pixel has is isolated, it is not necessary to consider the like bleeding with the surrounding pixels, are set to be the maximum value (all replaced with black).

The portion for determining whether the surrounding pixels are black or color in this embodiment will be described in detail with reference to the sequence of FIG.

First, in Step-11, density data of a judgment pixel and surrounding pixels is fetched. The amount to be taken can be set according to the determination range, and the determination can be made with data of at least one dot around the periphery. Next, in Step-12, the maximum density: max (C, M, Y) = _Dmax is calculated from the density of each pixel. In Step-13, the minimum density is calculated from the density of each pixel:
Calculate min (C, M, Y) = D _min . This D _max ,
The color component of the pixel is determined from D _min . Step-1
At 4, the difference between _Dmax and _Dmin is taken and is set as _Dij . Step
At -15, a black generation amount: G is determined from a table (described later) based on this D _ij . Then, in Step-16, UCR
By performing the processing and the black generation processing, the color component of the determination pixel is determined.

Here, the relationship between D _max and D _min is shown in FIG.
3 will be described. FIG. 13 shows that the density is 8 gradations (12.5
In this case, the percentage of black and color at the pixel is shown in the case where the value is expressed in percentages and rounded off in the figure). The higher the values of _Dmax and _Dmin, the higher the density. The larger _Dmax is, the more black or color components are.
_{If max} is small, there will be no black and no color, and white parts will appear. Also, the larger the _Dmin is, the more the black component is. On the contrary, the smaller the _Dmin is, the less the black component is.

Therefore, the color component increases as going to the upper right in FIG. 13, that is, the color component increases as the difference between _Dmax and _Dmin increases. Conversely, D _max
The smaller the difference between _Dmin and _Dmin , that is, the closer to zero, the fewer the color components. That is, the difference between _Dmax and _Dmin ,
The color component of the pixel can be determined from D _ij .

FIG. 14 shows a table corresponding to D _ij .
The value shown in the figure corresponds to the black generation amount: G. The amount of black generation is determined using this table in Step-15 of FIG. In the present embodiment, this table is set to 2 of _Dmax and _Dmin.
Although a dimension is used, a table using only D _ij as one parameter may be used more simply. As mentioned above,
If D _ij is large, the color components are large, and if D _ij is small, the color components are small.

In actual judgment, judgment is made from a plurality of surrounding pixels. First, density data (C, M, Y) at a pixel around the determination pixel, for example, address: 11, is fetched, and its maximum value and minimum value are obtained. Then, the minimum value is subtracted from the maximum value. The difference is defined as D11. As shown in equation (5), similarly, a value is obtained by subtracting the minimum value from the maximum value of the other surrounding dots. _{D 11 = max (C 11,} M 11, Y 11) -min (C 11, M 11, Y 11) D 12 = max (C 12, M 12, Y 12) -min (C 12, M 12, Y _{12) D 13 = max (C} 13, M 13, Y 13) -min (C 13, M 13, Y 13) D 21 = max (C 21, M 21, Y 21) -min (C 21, M 21 , Y ₂₁ ) D ₂₂ = max (C ₂₂ , M ₂₂ , Y ₂₂ ) −min (C ₂₂ , M ₂₂ , Y ₂₂ ) (5) D ₂₃ = max (C ₂₃ , M ₂₃ , Y ₂₃ ) _{-min (C 23, M 23,} Y 23) D 31 = max (C 31, M 31, Y 31) -min (C 31, M 31, Y 31) D 32 = max (C 32, M 32, Y _{32) -min (C 32, M} 32, Y 32) D 33 = max (C 33, M 33, Y 33) -min (C 33, M 33, Y 33)

Here, D _ij obtained by the equation (5) corresponds to step-14 in FIG. The black generation amount of the determination pixel is determined from this D _ij, and the pixel having the largest color component among the plurality of D _ij , that is, the largest D _ij is used in FIG.
In step-15, the amount of black generation is determined.

As a result, even if one pixel is in contact with a color, a black generation amount corresponding to the color component of the color pixel is used. Therefore, it is possible to set the optimum amount of black generation, the amount of black generation that does not cause harm such as blurring at the boundary between color and black, and the density of black characters and the like does not decrease for each pixel. .

As described above, it is possible to determine a color component from the density of the color of the surrounding pixels for each pixel and to set an optimal black generation amount for the pixel. Since the determination is made with the multi-valued information as it is, when recording a black image area in contact with the color image area, black is generated so as not to change the color tone abruptly. it can. Further, in a normal black image area, Bk ink which can perform excellent recording quality with little feathering can be used. That is, both high-quality black recording and high-quality color recording can be realized.

(Embodiment 2) As a second embodiment, as in the first embodiment, the black generation amount of the judgment pixel is changed according to the color components of the surrounding pixels, but according to the distance between the judgment pixel and the surrounding pixels. The case where the degree of influence is changed will be described.

FIG. 15 shows the relationship between the judgment pixel and the surrounding pixels. When the judgment is made for the judgment pixel of address: 33, some surrounding pixels are set as judgment pixels, and the degree of the influence of the color component is changed according to the distance from the judgment pixel.
For example, in FIG.
Assuming that it receives 00%, the influence degree is set to 50% in the area of the surrounding pixels 2.

More specifically, a description will be given using the sequence of FIG. First, in Step-11, the density data of the determination pixel and the surrounding pixels are fetched. Next, in Step-12, the maximum density: max (C, M, Y) = D from the density of each pixel.
Calculate _max . In Step-13, the minimum density: min (C, M, Y) = _Dmin is calculated from the density of each pixel.
The color component of the pixel is determined from _Dmax and _Dmin . S
taking the difference between D _max and D _min in tep-14, and D _ij.

Here, in the area of the surrounding pixel 1, that is, D
The values of ₂₂ , D ₂₃ , D ₂₄ , D ₃₂ , D ₃₄ , D ₄₂ , D ₄₃ , and D ₄₄ are used as they are, and the values of D ₁₁ ,
_{D 12, D 13, D 14} , D 15, D 21, D 25, D 31, D 35, D
₄₁ , D ₄₅ , D ₅₁ , D ₅₂ , D ₅₃ , D ₅₄ , and D ₅₅ use half (50%) of the values. In Step-15, a value of black generation: G is determined from a table (described later) on the basis of this D _ij based on the value of D _ij having the largest color component among them. Then, in Step-16, the UCR process and the black generation process are performed to determine the color component of the determination pixel.

Although the present embodiment divides the surrounding pixels into two regions, it may be divided into more stages for more effective. In that case, the UCR process and the black generation process can be performed more effectively by changing the degree of influence in multiple stages according to the distance between the surrounding pixels and the determination pixel.

As described above, by changing the degree of influence of a plurality of surrounding pixels and changing the amount of black generation in accordance with the color components of each surrounding pixel, the boundary between color and black is smoother. A great change in color tone can be realized. Therefore, it is possible to more effectively set the amount of black generation with respect to bleeding at the boundary. Further, as in the first embodiment, it is possible to use a Bk ink which can perform excellent recording quality with little feathering in a normal black image area. That is, both high-quality black recording and high-quality color recording can be realized.

(Embodiment 3) As a third embodiment, UCR
A case where black and color are replaced again according to the surrounding pixels after performing the processing and the black generation processing will be described.

In this embodiment, in order to surely prevent adverse effects such as bleeding at the boundary between color and black, the UCR process and the black generation process are performed once, and then the black data is replaced with the color again. In this embodiment, the amount of black is adjusted after the color components have already been determined, so that the color density at the boundary between color and black is not impaired, and the amount of black at the boundary is reliably limited. it can.

FIG. 16 shows the sequence. This embodiment is a determination process after the UCR process and the black generation process are performed. First, UCR processing and black generation processing are performed in Step-21, and the color components of each pixel are determined. Then S
At step-22, the density data of the determination pixel and the surrounding pixels are fetched. In Step-23, the color components of the surrounding pixels are determined.

If there is no color at all, this sequence is terminated without converting black to color. if,
If at least one color is in the surrounding pixels, convert black to color. Although black is converted to color in Step-24, the amount of conversion may be set in advance and all black may be converted to color (C, M, Y), or a certain ratio, for example, 50 You may make it convert into color only by%. Further, the conversion amount may be changed according to the color components of the surrounding pixels. Further, the amount of conversion from black to color may be determined based on the color components of a plurality of surrounding pixels in combination with the second embodiment.

As described above, after the UCR processing and the black generation processing are performed, the black is converted into the color again according to the color components of the surrounding pixels, so that the boundary between the black and the color can be more reliably determined. It is possible to suppress adverse effects such as bleeding.

(Embodiment 4) FIG. 17 is a schematic view of another color ink jet printer to which the present invention can be applied. 1y is a recording head for yellow ink, 1m is a recording head for magenta ink, and 1c is a recording head for magenta ink. A recording head for cyan ink, 1b is a recording head for the first black ink, 1k is a recording head for the second black ink, 2 is a carriage on which the recording head is mounted, and 3 is for sending an electric signal from the printer body to the recording head. 4 is a cap unit having recovery means, 5y, 5m, 5c and 5k are cap members corresponding to the recording heads 1y, 1m, 1c and 1k, and 6 is a wiper blade made of a member such as rubber.

The configuration of the nozzles of the recording heads 1y, 1m, 1c and 1k is basically the same as that of the recording head 102 shown in the above embodiment, and each head has 128 ejection ports. Approximately 40 ng of ink is ejected from each nozzle of the recording heads 1y, 1m and 1c, and approximately 80ng of ink is ejected from the nozzles of the recording head 1k. For the recording heads 1y, 1m, and 1c, ink having a high permeation rate to the recording paper is used as described above, and for the recording head 1k, ink having a low permeation rate to the recording paper is used.

The present invention can be applied to the above printer. The feature of this embodiment is that the recording time is short because the recording heads of the same size are arranged in parallel.

In the above-described embodiments, the black generation amount or the black amount is changed in the UCR process and the black generation process. However, the binarization process may be changed. FIG.
When performing the binarization processing in the halftone processing 505, the color components of the surrounding pixels are determined in the same manner as the UCR processing and the black generation processing instead of simply performing the binarization processing on each color independently. The binarization process may be changed according to the color component. For example, the binarization mask is changed according to the color components of surrounding pixels.

Therefore, since the processing is performed based on the multi-value information, the adverse effects at the boundary between black and color are suppressed and a boundary of a smooth color tone change is formed as in the first, second and third embodiments. It is possible to do.

In each of the above-described embodiments, the determination of the image
A case has been described in which control / processing means such as determination processing, image expansion processing / replacement processing, etc. are all controlled by the control unit in the recording apparatus based on data received from the host computer. It is not limited.

For example, it is also possible to extend the control and processing means to a system in which an external device executes all of the control and processing means by a printer driver or the like and receives actual recording data after the pixel replacement processing is completed. In many cases, the external device connected to the recording device is a host computer,
The host computer has better processing power and RAM capacity for performing the above processing.

The image determination processing may be performed by the host computer, and the image development processing may be performed by the printer.

In each of the above-described embodiments, a so-called bubble jet recording method has been described in which the recording head uses an electrothermal transducer to generate bubbles in the ink and causes the ink to fly by the action of the bubbles. Needless to say, the present invention can be applied to a so-called piezo-type ink jet recording system in which ink is jetted by an electromechanical converter.

The present invention particularly provides an excellent effect in a recording apparatus using a recording head of an ink jet system in which a flying liquid is formed by utilizing thermal energy in the ink jet recording system to perform recording.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to the drive signal
This is effective because air bubbles in the interior can be formed. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

The recording head may have a combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned specifications. U.S. Pat. No. 4,558,333 and U.S. Pat.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

In addition, even in the case of the serial type as described above, a recording head fixed to the apparatus main body or an electric connection with the apparatus main body or ink from the apparatus main body is mounted on the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

Further, it is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

Further, as for the type and number of the recording heads to be mounted, two or more recording heads may be provided corresponding to a plurality of inks having different recording colors and densities. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, in order to positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, the ink is solidified in a standing state and heated. May be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, the ink
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

Further, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

[0102]

According to the present invention, Bk is detected by detecting the boundary.
Is not replaced by PCBk, but in the UCR process of generating Bk data from C, M, and Y color data before performing the binarization process, that is, multi-valued black image data Changes the rate at which
At the boundary between the color image area and the black image area, there is no sharp color tone change, and the color tone changes smoothly, so that it is possible to make the color inconspicuous.

As a result, excellent recording quality with less feathering in the black image area can be realized, and excellent recording quality without ink bleeding between black and each color can be achieved. It is possible to realize both high-quality color printing.

[Brief description of the drawings]

FIG. 1 is a perspective view of an inkjet recording apparatus to which the present invention can be applied.

FIG. 2 is a head mechanism diagram of an ink jet recording apparatus to which the present invention can be applied.

FIG. 3 is a control circuit block diagram of an ink jet recording apparatus to which the present invention can be applied.

FIG. 4 is a block diagram of image processing to which the present invention can be applied.

FIG. 5 is a block diagram showing the inside of a color printer to which the present invention can be applied.

FIG. 6 is a diagram showing input (R, G, B) -output (C, M, Y) characteristics in image processing.

FIG. 7 is a diagram illustrating a UCR process and a black generation process.

FIG. 8 is a diagram illustrating a gradation characteristic of a recording density and a correction table characteristic.

FIG. 9 is a diagram illustrating recording density adjustment.

FIG. 10 is a diagram illustrating a determination pixel and surrounding pixels according to the first embodiment.

FIG. 11 is a sequence of changing a black generation amount performed in the first embodiment.

FIG. 12 is a sequence of changing a black generation amount including a specific color component determination performed in the first embodiment.

FIG. 13 is a diagram illustrating color components determined from the relationship between D _max and D _{min in} the first embodiment.

FIG. 14 is a table of a black generation amount determined from a relationship between D _max and D _{min in} the first embodiment.

FIG. 15 is a diagram illustrating a determination pixel and surrounding pixels in a second embodiment.

FIG. 16 is a sequence of converting black to color performed in the third embodiment.

FIG. 17 is a perspective view of another inkjet recording apparatus to which the present invention can be applied, which is used in Embodiment 4.

FIG. 18 is a diagram showing a basic pattern of a PCBk mask used at the time of PCBk replacement.

[Explanation of symbols]

Reference Signs List 101 carriage 102 recording head 103 cartridge 110 color ink cartridge 111 black ink cartridge 301 system controller 306 host computer 307 reception buffer 308Y, 308M, 308C, 308Bk frame memory of each color 309Y, 309M, 309C, 309Bk data buffer of each color 310 print control unit 311 print driver 312Y, 312M, 312C, 312Bk Recording head of each color

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Arai 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc. (72) Inventor Kentaro Yano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside the Company (72) Inventor Osamu Iwasaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Daigoro Kanematsu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. ( 72) Inventor Toshi Inui 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Isao Ebisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Nao Yaegashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Nobuyuki Kuwahara 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Non-corporation (72) Inventor Yuji Akiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-53351 (JP, A) JP-A-1-135268 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/21

Claims (10)

(57) [Claims] 1. A method of using a black ink and a plurality of color inks having different recording medium penetration characteristics from the black ink ,
A color inkjet recording method for performing recording by discharging ink on a recording medium , comprising: a multi-valued color indicating a density corresponding to each of the plurality of colors.
Multi-valued black recording data indicating the density of black based on the recording data
A multi-valued color print data and the generation step.
Based on the generated multi-value black recording data,
The recording is performed by discharging the color ink of the color and the black ink.
Recording step , wherein the generation step corresponds to the pixel to be determined.
The determination target image based on the multi-valued color print data.
Generating the multi-value black recording data corresponding to the element
The multi-valued camera corresponding to pixels surrounding the pixel to be determined
If the color recording data indicates a color image,
For generating the multi-value black recording data corresponding to the pixel
A color ink jet recording method, wherein the color ink jet recording method is changed so as to lower the ink jet recording density. 2. The method according to claim 1, wherein the generating step includes:
The surrounding image based on the corresponding multi-valued color print data.
If it is determined whether the element indicates a black pixel or a color pixel,
Both have multiple generation ratios determined according to the judgment result
The ratio of generating the multi-value black recording data based on the
The color ink jet according to claim 1, wherein
Jet recording method. 3. The method according to claim 1, wherein the generating step includes :
Before indicated by the corresponding multi-valued color record data
The multi-valued black recording data is obtained based on the density of each of the plurality of colors.
2. The method according to claim 1, wherein the rate of generating the data is changed.
The color ink jet recording method as described above. 4. The method according to claim 1, wherein the generating step includes :
Multiple surrounding pixels included within a distance of multiple pixels from the element
A plurality of areas according to the distance from the pixel to be determined
And corresponding to each of the plurality of areas.
The plurality of areas based on the multi-valued color print data.
2. The color ink jet recording method according to claim 1 , wherein the color components of black and the plurality of colors in each area are determined, and a generation ratio of the multi-value black recording data is changed . 5. Use of black ink and a plurality of color inks having a recording medium penetration characteristic different from the black ink,
A color ink jet recording method for performing recording by discharging ink on a recording medium , comprising: a density corresponding to each of the plurality of colors of a pixel to be determined
Is determined based on the multi-valued color print data indicating
Generate multi-value black recording data indicating the black density of the pixel
A generating step; and the multi-valued color corresponding to pixels surrounding the pixel to be determined.
-Determine the color of the surrounding pixels based on the recording data
A determining step , based on the determination result of the determining step,
When the pixel indicates the plurality of colors, the pixel to be determined is
The density of the multi-valued black recording data of
Change the multi-level color print data corresponding to the pixel of
And a multi-valued color record data obtained by the changing step.
The plurality of colors based on the data and the multi-valued black recording data.
Recording by discharging the color ink and the black ink
Color ink jet recording side, characterized in that it consists: a recording step,
Law. 6. The multi-value black recording data.
Data and the density of each of the multi-valued color print data
Is indicated by the multi-valued color print data.
6. The color ink jet recording method according to claim 5, wherein the color ink is made different depending on the color components of the surrounding pixels . 7. The method according to claim 7, wherein each of the inks is heated by heat energy.
7. The color inkjet recording method according to claim 1, wherein the ink is ejected using an inkjet head that ejects the ink . 8. Use of black ink and a plurality of color inks having a recording medium penetration characteristic different from the black ink,
The black ink and the plurality of color inks are used in black density.
And the density of each of the plurality of colors.
Discharge based on the multi-valued color print data shown
Color ink jet recording a color image on a recording medium
A jet recording device, which corresponds to each of the plurality of colors of pixels around a pixel to be determined.
For determining multi-valued color print data indicating
According to the step and the generation ratio according to the determination result by the determination means,
From the multi-valued color print data of the determination pixel, the determination image
Generating means for generating multi-value black recording data corresponding to the element,
And the multi-level color print data corresponding to the surrounding pixels is
Color pixel, compared to the case of black pixel,
A color ink jet printing apparatus characterized in that a generation ratio for generating multi-value black print data is reduced . 9. Using a black ink and a plurality of color inks having a recording medium penetration characteristic different from the black ink,
The black ink and the plurality of color inks are used in black density.
And the density of each of the plurality of colors.
Discharge based on the multi-valued color print data shown
Color ink jet recording a color image on a recording medium
A jet recording apparatus, wherein the multi-level color recording data corresponding to the pixel to be determined is
Generating means for generating multi-valued black recording data , corresponding to each of the plurality of colors of pixels around the pixel to be determined
For determining multi-valued color print data indicating
And determining the multi-valued black recording data of the determination pixel generated by the generation unit according to the determination result by the determination unit.
Conversion means for converting to multi-valued color print data of the target pixel , wherein the conversion means corresponds to the surrounding pixels
If the multi-valued color recording data indicates color pixels,
The multi-valued black recording data is compared with the multi-valued
A color inkjet recording apparatus characterized in that the amount of conversion into color recording data is increased . 10. The color ink jet recording apparatus according to claim 8, wherein each of the inks is ejected by thermal energy.