JP2003136702A - Recorder, recording method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recorder, a recording method and a storage medium in which the unevenness of an image, e.g. white streak caused by non-ejected dots, is eliminated and rendered unrecognizable with human eyes while suppressing cost increase in a recording head, and a high print speed can be realized. SOLUTION: The recorder for recording a color image on a recording medium using a recording head arranged with a plurality of recording elements comprises means for driving the plurality of recording elements of the recording head depending on image data to record an image on the recording medium, a plurality of means for complementing the defect of an image caused by recording elements not performing recording operation among the plurality of recording elements by different methods, and means for controlling the complementary recording control operation using the plurality of complementary means selectively depending on the image being recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus and a recording method for recording by using a recording head in which a plurality of recording elements are arranged. More specifically, the present invention relates to an inkjet recording apparatus that uses a recording head having a plurality of nozzles arranged to eject ink from the nozzles for recording.

[0002]

2. Description of the Related Art In recent years, an ink jet type recording apparatus for recording ink on a recording medium by ejecting ink from nozzles arranged in a recording head has been widely applied to printers, fax machines, copying machines and the like. In particular, it can be said that a color printer capable of recording a color image by using inks of a plurality of colors shows remarkable growth as its image quality is improved. In addition to high image quality, high speed is also an important factor in the recording apparatus. As the frequency of driving liquid droplet ejection from the head is increased, the speed is also increased by increasing the number of nozzles arranged in the recording head. It's starting.

However, in the ink jet head, what is called "dust" is caused by dust that has entered the nozzles of the print head at the time of manufacture, deterioration of the nozzles due to long-term use, deterioration of elements for ejecting ink, and the like. In some cases, there may be a case where the ink droplet cannot be ejected, which is "non-ejection". If the latter is a cause, ejection failure may occur accidentally during the period of use of the recording apparatus.

In addition, a state in which the ejection direction of the ink droplets is deviated to a greater degree than a desired direction without being completely in a non-ejection state (hereinafter, also referred to as "ejection deflection") or the ejection amount of the ink droplets is desired. In some cases, the state may be significantly different from that of the above (hereinafter, also referred to as “dispersion of drop diameter”).
A nozzle that has deteriorated to such a degree that the quality of a printed image is greatly deteriorated when used for printing is in a state that does not correspond to a nozzle that performs printing, and will be described below as “non-ejection”.

Such non-ejection and the like can be suppressed in frequency by improving the manufacturing environment and the like, and it has not been a serious problem in the past. However, as described above, when the number of nozzles arranged in the recording head is increased to increase the speed, it becomes a problem that cannot be ignored. In particular, in order to manufacture a printhead that does not include nozzles in a non-ejection state or a good printhead in which non-ejection does not easily occur, manufacturing cost increases, and as a result, the printhead becomes expensive.

When these non-ejections occur, defects such as white streaks occur on the image. In order to supplement such white streaks, a technique is proposed in which a divided print method is used in which the print head is scanned a plurality of times for printing, and the white spots are complemented by other normal nozzles for printing. Has been done.

[0007]

However, in order to achieve the above-described high-speed recording, it is preferable to perform so-called one-pass printing, which completes the printing by one scanning. In printing, it is very difficult to complement or make inconspicuous a portion that is not ejected and is not recorded. Further, even in a so-called "multi-scan" printing method in which a print head scans a predetermined area on a print medium a plurality of times, printing may be performed depending on the position or number of nozzles in which ejection failure occurs. In some cases, it is difficult to supplementally record the position.

The present invention has been made in view of the above-mentioned problems, and eliminates image unevenness such as white streaks that occurs in a recorded image due to non-printing of dots due to non-ejection, and non-ejection occurs. Even when it occurs, it is an object of the present invention to provide an ink jet recording apparatus that prevents white stripes and image unevenness from being recognized by human eyes, suppresses an increase in cost of the recording head, and further enables a high printing speed. To do.

[0009]

The present invention can solve the above-mentioned problems by providing the following constitutions.

(1) In a recording apparatus for recording a color image on a recording medium using a recording head in which a plurality of recording elements are arranged, recording is performed by driving the plurality of recording elements of the recording head according to image data. A plurality of complementing means for complementing the recording head driving means for recording an image on the medium by different methods and a plurality of complementing means selectively depending on the recording medium, and complementing A recording device having a control unit for controlling recording control operation.

(2) The plurality of complementary means perform complementary recording on a recording position corresponding to a recording element that does not perform a recording operation, by using a color different from the recording color of the recording element that does not perform the recording operation. The recording apparatus according to the above item (1), including the complementary means of 1.

(3) Based on the image data corresponding to the recording element that does not perform the recording operation, the plurality of complementing means obtains the image data corresponding to the recording element that is located near the recording element that does not perform the recording operation. The recording apparatus according to (1) above, including a second complementing unit that complements the defect in the recorded image by correcting the defect.

(4) The plurality of complementary means perform complementary recording at a recording position corresponding to a recording element that does not perform a recording operation with a color different from the recording color of the recording element that does not perform the recording operation. By correcting the image data corresponding to the recording element located in the vicinity of the recording element that does not perform the recording operation based on the complementary means of No. 1 and the image data that corresponds to the recording element that does not perform the recording operation, The recording apparatus according to (1) above, further comprising a second complementing means for complementing the defect (1).

(5) The recording medium comprises a first and a second recording medium.
In the case of the first recording medium, the control means selectively controls only the second complementing means, and in the case of the second recording medium, at least the first complementing means is selectively controlled. The recording apparatus according to (1) above.

(6) The bleeding rate of the first recording medium is 2.
The bleeding rate of the second recording medium is 2.
The recording apparatus according to (5) above, which is less than 5.

(7) The first complementing means performs recording corresponding to a plurality of different colors, and complements recording with a color having a lightness similar to that of a recording element that does not perform a recording operation. The recording apparatus according to any one of 2), (4), and (5).

(8) The first complementing means has a compensating means for compensating the image data corresponding to the recording element which does not perform the recording operation according to the recording color corresponding to the recording element which performs the complementary recording. The recording apparatus according to item (7), wherein complementary recording is performed based on the image data corrected by the correction means.

(9) The second complementing means represents the image data corresponding to the recording elements in the vicinity according to the density represented by the multivalued image data indicating the density corresponding to the recording element that does not perform the recording operation. The recording apparatus according to any one of (3) to (5) above, which corrects the density.

(10) The recording apparatus according to any one of the above items (1) to (9), wherein the recording element that does not perform the recording operation includes a recording element that is in an inoperable state.

(11) The recording head is an ink jet head having a plurality of nozzles and performing recording by ejecting ink from the nozzles by driving the recording element. The recording device according to 1.

(12) The recording element as described in the above item (11), wherein the recording element is composed of an electrothermal converter that gives heat energy to the ink, and bubbles are generated in the ink by the heat energy to eject the ink from the nozzle. apparatus.

(13) In a recording method of recording a color image on a recording medium based on image data by using a recording head in which a plurality of recording elements are arranged, no recording operation is performed among the plurality of recording elements. A plurality of different complementary methods for identifying a recording element, a step of recognizing a recording medium, and a complementary method for complementing a defect in a recorded image by a recording element that does not perform a recording operation based on the recognition result. A recording method including a step of selectively controlling from among the above, and a step of performing recording by complementing an image to be recorded by a recording element which does not perform a recording operation by the selected complementing method.

(14) In the plurality of complementary methods, complementary recording is performed at a recording position corresponding to a recording element that does not perform a recording operation with a color different from the recording color of the recording element that does not perform the recording operation. 1 including the complement method of (1)
The recording method described in 3).

(15) The plurality of complementing methods are based on image data corresponding to a printing element that does not perform a printing operation.
A second complementing method for compensating for a defect in a recorded image by correcting image data corresponding to a recording element located in the vicinity of a recording element that does not perform the recording operation (1)
The recording method described in 3).

(16) In the plurality of complementary methods, complementary recording is performed at a recording position corresponding to a recording element that does not perform a recording operation with a color different from the recording color of the recording element that does not perform the recording operation. Based on the complementary method of No. 1 and the image data corresponding to the recording element that does not perform the recording operation, the image data corresponding to the recording element that is located in the vicinity of the recording element that does not perform the recording operation is corrected. And a second complementing method for complementing the defect of
The recording method described in 3).

(17) The recording according to any one of (14) to (16) above, wherein the first complementary method performs complementary recording with a color that is similar in brightness to a recording color of a recording element that does not perform a recording operation. Method.

(18) The first complementary method has a step of correcting image data corresponding to a recording element that does not perform a recording operation according to a recording color corresponding to a recording element that performs complementary recording. The recording method according to item (17), wherein complementary recording is performed based on the image data corrected in the process.

(19) In the second complementary method, the image data corresponding to the recording elements in the vicinity represent the density corresponding to the density represented by the multivalued image data indicating the density corresponding to the recording element that does not perform the recording operation. The recording method according to (15) above, in which the density is corrected.

(20) In the case of the second recording medium, at least the first complementary method is selectively used, and in the case of the first recording medium, only the second complementary method is used. The recording method according to the above item (16), which selectively uses.

(21) The recording according to (20) above, wherein the first recording medium has a bleeding rate of 2.5 or more and the second recording medium has a bleeding rate of less than 2.5. Method.

(22) The recording method according to any one of (13) to (19) above, wherein the recording element that does not perform the recording operation includes a recording element that is in a state in which the recording operation is impossible.

(23) A storage medium storing a program for realizing the recording method described in (13) above.

(24) The recording apparatus according to any one of the above items (1) to (12), comprising a measuring means for measuring the bleeding rate of the recording medium.

(25) In the case of the first recording medium, in order to perform the complementation only by the second complementing means, the control means for controlling the ejection amount of the recording head is provided (1) to (24). ) The recording apparatus according to any one of 1).

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a schematic diagram showing a missing condition and a complementing condition of a printed image, and a graph showing a relationship between a clear visual distance and a missing width. FIG. 2 shows all of the low print duty and the high print duty.
FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D are block diagrams showing a method of complementing the nozzle portion of the ejection failure head with only Bk.
(E) and (f) are explanatory views showing an example in the case of an image design of 1 dot per pixel, FIG. 4 is a graph showing the output value of the brightness of each color with respect to the input value, and FIGS. 5 and 6 are FIG. 7 is a graph showing an example of conversion for complement by different colors, FIG. 7 is a graph showing an example of conversion for complement by different colors, FIG. 8 is a flowchart showing processing of the data conversion arithmetic circuit, and FIG. 10 is a graph showing an example of conversion for complementation, FIG. 10 is a side sectional view showing a configuration of a color copying machine as an example of the ink jet recording apparatus in this embodiment, and FIG. 11 is a detail of a CCD line sensor (light receiving element). Explanatory drawing, FIG. 12 is an external perspective view of the inkjet cartridge, FIG. 13 is a perspective view showing details of the printed circuit board 85, FIG.
16B is an explanatory diagram showing a circuit configuration of a main part on the printed circuit board 85, FIG. 15 is an explanatory diagram showing an example of a time-division drive chart of the heating element 857, and FIG. 16A is an ideal recording head. 17B is a schematic diagram showing a recording state in FIG. 17B, FIG. 17B is a schematic diagram showing a state in which there is variation in drop diameter, and there is wobbling.
1A is a schematic diagram showing a state of 50% halftone by an ideal recording head, FIG. 1B is a schematic diagram showing a state of 50% halftone with variations in drop diameter, and FIG.
8 is a block diagram showing a configuration example of the image processing unit in the present embodiment, FIG. 19 is a graph showing an input / output relationship of the γ conversion circuit 95, and FIG. 20 is a main configuration showing a function of the data processing unit 100. Example block diagram, FIG. 21 is a graph showing an example of a density correction table for nozzles, FIG. 22 is a graph showing an example of a non-linear density correction table for nozzles, and FIG.
24 is an external perspective view of the inkjet recording apparatus main body, FIG.
FIG. 25 is an explanatory view of the print output status of the uneven read pattern.
26A and 26B are explanatory views showing an example of a print pattern by a print head including 128 nozzles.
27C is an explanatory diagram showing a pattern of read print density data, FIG. 27 is an explanatory diagram showing a pattern of print density corresponding to nozzles, FIG. 28 is an explanatory diagram showing a situation of pixels in a read region, and FIG. 29 is , An explanatory view of pixel density data, FIG.
Is a relationship graph in which the horizontal axis is the gray lightness (lightness of the portion b) and the vertical axis is the clear visual distance at which evenness is not visible after the complementation, and (b) is complemented by the minimum lightness (about 56). In the case of and the case of not complementing, the horizontal axis is the clear visual distance,
A relational graph showing the vertical axis as a missing width at which the unevenness cannot be seen, (c) is a graph showing the relationship in FIG. (B) in detail in a narrow portion, and FIG. 31 (a) shows the missing portion b by Bk. Explanatory diagram showing an example of complementing with a pattern of thinned dots,
32B is a partially enlarged view of FIG. 32A, FIG. 32A is an example of complementation with Bk dots when adjacent complementation is performed,
FIG. 33B is an image unevenness evaluation table for the human eye, and FIG.
It is explanatory drawing which made 2 into a graph.

In the following description, the nozzle in which ejection failure has occurred, the nozzle in which the ink droplet ejection direction is biased more largely than the desired direction, and the ejection amount of the ink droplet are significantly different from the desired amount. The nozzles in the state will be described as nozzles in a state in which recording cannot be performed. The present invention treats these nozzles as nozzles that do not perform printing, or print elements that do not perform printing, and performs printing so as to complement the positions that are not printed by these nozzles, or the positions that are not printed. Explained. It should be noted that the nozzles and recording elements that are in a state where normal recording cannot be performed will be described as defective nozzles and defective recording elements.

The inventor of the present invention has earnestly studied the discharge failure complement method when a discharge failure nozzle occurs, and has found that it is preferable to use a plurality of discharge failure complement methods properly according to the recording medium.

That is, since the bleeding of the landed ink drop differs depending on the non-recording medium, the method of complementing to eliminate streak unevenness in the case of ejection failure differs.

Here, in the following description, the bleeding rate will be defined. Although the ink droplets ejected from the recording head land on the recording medium and the ink droplet spreads to form dots, the bleeding rate is the ratio of the dot diameter to the diameter of the ink droplet before landing.

About 2.5 times was considered as the criterion for the large or small bleeding rate.

That is, when ink droplets are ejected by the ink jet recording apparatus and land on the recording medium,
It has been found that the diameter of the landed ink droplet is approximately twice the diameter of the flying ink droplet.

After that, the landed ink droplets are absorbed into the recording medium, but when the ink permeability is high, a so-called plain paper containing a sizing agent as an anti-bleeding agent is included in the PPC (Plain Paper Copi).
er) paper, the bleeding rate is 2.5 because it penetrates sufficiently.
More than double. On the other hand, when the ink permeability is low, the ink does not penetrate so much even after landing, and dots are formed due to the evaporation of volatile components in the ink and the expansion order into the paper, so the bleeding ratio does not become more than double. However, it may be double or less.

Further, the special medium having the coat layer formed is formed so as to control the ink bleeding regardless of the ink permeability, and there is a medium for increasing the bleeding rate. In order to improve the graininess and the image quality, it is the mainstream to reduce the dot diameter, and glossy paper has a bleeding rate of about double.

That is, it is formed so as to prevent horizontal permeation on the surface of the medium.

Therefore, in the recording medium having a large bleeding rate, if the width of the non-ejection portion is relatively small, the unevenness can be seen by printing many dots of the neighboring nozzles including the dots of the nozzles adjacent to the non-ejection nozzle. It is possible to make it difficult. That is, in the high print duty, for example, in the case of a solid image, when the amount of ink per unit area in the paper increases, the bleeding of the dot group spreads in the area of the non-ejection portion of the paper, and is recognized as the non-ejection image. I found that I could not do it.

On the other hand, in the low print duty, a large number of dots of neighboring nozzles including dots of nozzles adjacent to the discharge failure nozzle are printed as shown in FIG. 3 regardless of the recording medium, thereby complementing the macro density. As a result, it becomes possible to make it difficult to recognize as unevenness.

The width of the non-ejection portion, which makes it difficult to see the unevenness by complementing the non-ejection nozzle in the vicinity of the nozzle, varies depending on the amount of ink droplets, but is preferably about 70 μm or less.

If it is plain paper, an ink having high permeability is preferable. The bleeding rate is preferably 2.5 times or more. 1. Even coated ink with low penetrability 2.
A bleeding rate of 5 times or more is preferable.

On the other hand, in a medium having a bleeding rate of less than 2.5 times, such as glossy paper, the original dot diameter is small, and even if a large number of adjacent dots are printed, there is almost no spread as a dot group, and there is a discharge failure portion. Is hard to complement. Therefore, complementing with dots of other colors is effective.

Whether or not to complement other colors as the recording medium may be set in advance by the main body or the printer driver, but an ink droplet is printed on the front end of the printed matter and the dot diameter is set. A configuration in which the bleeding rate of the recording medium is recognized by measuring with the main body or the like is preferable.

A method of complementing a portion which is not printed by the defective nozzle of the present invention to perform printing and a method of making white lines inconspicuous will be described individually and in detail.

<Brightness Complementation> In the following example, instead of a nozzle in which recording cannot be performed due to occurrence of ejection failure or the like, a dot having a color different from the color of ink ejected from that nozzle is used. For complementing printing, based on output data (hereinafter also referred to as image data) corresponding to the nozzle in which ejection failure has occurred, the brightness of the image printed by the output data and In order to match the brightness of the image recorded by the nozzles of other colors with a certain level, output data corresponding to the complementary nozzle is generated and complementary recording is performed. still,
Regarding the lightness, the lightness when the color of the non-ejection nozzle is uniformly recorded according to the corresponding output data is matched with the lightness when the color used for complementing is uniformly recorded at a certain level. , To generate output data corresponding to nozzles of colors used for complementation. By adjusting the brightness at a certain level in this manner, even if printing is performed so that a portion where printing is not performed due to non-ejection is complemented by another color, the non-ejection portion can be made inconspicuous. it can.

Regarding the color to be complemented, it is preferable to complement the color having a close chromaticity. For example, it is known that a general color inkjet printer uses four color inks of cyan (C), magenta (M), yellow (Y), and black (Bk), and inks of such a plurality of colors are used. In the configuration using B, when complementing the non-ejection of the C (cyan) nozzle, M (magenta) having almost the same lightness among the four colors and B having a relatively close lightness.
Complementation can be performed by using nozzles of a recording head that ejects ink such as k (black). Specifically, originally C
The brightness of the image recorded by the data to be output by the nozzle is converted into Bk or M data in which the brightness difference is within a certain range, and the converted Bk or M data and the original Bk or M data are converted. The data is added and output.

Therefore, even if there is ejection failure, for example, by performing the processing described below with reference to FIG. 2, it is possible to supplement the intended ejection failure.

FIG. 2 is a block diagram / flowchart for explaining the above-described brightness complementing method. First, step S
In 1, the non-ejection head and nozzle are recognized. This is because the nozzle that has not ejected is detected in advance when the head is manufactured.
^{2 The} data written in the PROM is read, or the non-ejection nozzle is determined from the image output by the recording device, or the detection is performed by a sensor that can detect the non-ejection nozzle.

As for the structure for detecting, various structures such as a structure for optically detecting the ejection state of ink, a structure for reading a test-recorded image to detect a non-ejection portion, and the like can be applied. Is possible. Next, in step S2, the color output data (multivalued data) of the non-ejection nozzle is read, and the lightness is obtained from the data. Subsequently, in step S3, the color data of the ink used for the complement is generated according to the lightness value of the data corresponding to the non-ejection nozzle. The generation of the complementary data is performed so that the brightness is matched at a certain level as described above. Note that this process can be performed by a process of converting the output data value corresponding to each color and the brightness value corresponding thereto according to the output data corresponding to the non-ejection nozzle. It should be noted that the table indicated by 21 in FIG. 2 is a table used for processing in the complementation with black ink described later.

According to the present inventor, as shown in FIG.
If the printed image is missing in the width of, the line is recognized as it is, but if the missing part b is printed so as to complement other colors, if the width of d is sufficiently narrow, the complementary color It has been found that by setting the lightness near to the original color a, it is difficult to distinguish it by assimilating it with the surrounding color even though it is a different color.

Specifically, FIG. 1A shows a state in which a missing portion b having a width d has occurred in the image of color a, and FIG.
Is a state in which the missing portion is complemented with other colors so that the lightness is approximated, and when the width d is changed with the color of the portion a being C (cyan) or M (magenta), the missing portion b is complemented. Experiments were performed by changing the distance between the observed image and the eyes (clear vision distance) to determine whether or not the unevenness can be recognized depending on whether the image is left as it is on a white background or is supplemented with Bk (black). .

As an example, an experimental example will be described in which the portion a shown in FIG. 1 is red with a lightness of about 51, and the portion b shown in FIG. 1 is complemented by a gray color with a changed lightness. To do.

In FIG. 30 (a), the horizontal axis represents the lightness of gray (the lightness of the portion b) complemented, and the vertical axis represents the clear visual distance at which unevenness is not visible after the complementation.

As the paper, coated paper (model number HR101) manufactured by Canon Inc. was used, and printing was carried out in one pass using an inkjet printer BJF850 manufactured by Canon. Gray was formed by mixing cyan (C), magenta (M), yellow (Y), and black (Bk).

Therefore, the halftone is so-called process Bk using three colors of C, M and Y, and when the gradation value becomes high, B
A process of mixing k and gradually removing C, M, and Y was performed. Such a process for forming gray using the color ink and the black ink was performed by referring to the table corresponding to the gradation value.

In FIG. 30 (a), it can be understood that the distance at which the streak is invisible (clear viewing distance) varies depending on the brightness of the complemented portion b, but what can be said in this figure is the missing width d which is a parameter. That is, the closer the brightness of b is to the brightness of about 51 of a, irrespective of the value of, the smaller the distance at which unevenness such as white lines cannot be seen.

From FIG. 30 (a), it can be seen that a correction effect can be obtained by setting the difference between the brightness of b and the brightness of b within ± 10. The value of ± 10 is about 20% with respect to the lightness 51 of a, but the same relationship was obtained even when an experiment was conducted by changing the lightness of a and printing.

Preferably, the difference in brightness between b and a is within ± 10% with respect to the brightness of a, so that the complementary effect is high.

Here, as the missing width d becomes shorter, the brightness of b is slightly larger (slightly brighter) than the brightness of a.
In this case, the distinct visual distance where the unevenness is less noticeable is shorter, but this is because the boundary part where the color of b part and the color of a part overlap due to ink bleeding is dark (low in lightness) It is thought to be because it has become.

In particular, since the gray color was formed by the above-mentioned process Bk, the bleeding portion was relatively wide.

Incidentally, in this example, the brightness of the white background portion of the paper is about 92.

FIG. 30 (b) shows the relationship in which the horizontal axis represents the clear visual distance and the vertical axis represents the missing width at which unevenness cannot be seen, in the case of complementing with the minimum brightness (about 56) in this figure and in the case of not complementing. ).

FIG. 30 (c) shows this relationship in detail in the part where the missing width is narrow.

Then, the width d, which is the recognition boundary of the white background, is as shown by a circle (white circle) in FIG. 1 (c). Here, when the width d of the missing portion is about 30 μm, the distance 100
It means that the missing part is not recognized at the boundary of cm and when the width of the missing part is about 5 μm, at the distance of 20 cm as the boundary. That is, a missing portion of about 30 μm is difficult to recognize as a missing portion when viewed with a distance of 100 cm, and a missing portion of about 5 μm is viewed with a distance of 20 cm. It will be difficult to recognize it as a missing part.

On the other hand, when the missing portion b is complementarily recorded in gray color so that the lightness is adjusted at a certain level,
The width d at which the complemented portion cannot be visually recognized is shown in FIG.
As shown by the black circle in (c). The position indicated by the black circle is difficult to be recognized when looking at a missing portion having a width of about 130 μm from a distance of 100 cm,
It also means that even a missing portion of about 40 μm is difficult to be recognized when viewed from a distance of more than about 20 cm. Therefore, by performing complementary recording with another color so as to match the lightness at a certain level, the missing portion is less likely to be recognized than when the missing portion is not complementally recorded.

As can be seen from these results, it was found that the white line recognition degree can be reduced by setting the lightness of the portion b to an appropriate value and complementing it with another color.

In the above experiment, the gray colors are C, M,
It is formed by the so-called process Bk, which is a mixed color of Y and / or Bk inks, but even when the missing portion b is complemented by a pattern in which Bk dots are thinned out,
The results were almost the same.

FIG. 34 shows an example of complementing the missing portion b with a pattern in which Bk dots are thinned out. FIG. 31 (b)
[Fig. 31] is a partially enlarged view of Fig. 31 (a). Reference numeral 341 in FIG. 31B indicates thinned Bk dot patterns 342 and 3.
Reference numeral 43 shows an example in which the missing part b of the image a is complemented by a pattern in which Bk dots are thinned out.

When the unevenness disappears, the lightness is measured by increasing the area of the portion b, and the relationship with the lightness of the portion a is examined. It turned out to be a close value.

Here, one of the reasons why the Bk dot is used is that the Bk dot itself has a low lightness, and therefore the pattern in which the Bk dots are thinned out has a low lightness in the high print duty portion including the secondary color. This is because they can be matched.

Here, an example of a detailed complementing method when the value of the missing width d is about 200 μm or less will be described.

Specifically, one pixel was formed at a resolution of 1200 × 1200 dpi using a head having a resolution of 1200 dpi, and printing was performed on the Canon coated paper HR101 with an ink droplet of about 4 pl.

Regarding the discharge failure, the image was adjusted so that there was no discharge failure in continuous nozzles and discharge failure was one, and a uniform gradation pattern was printed with C ink.

Bk ink dots were used as complementary dots for the non-ejection portion.

Here, as will be described below, a condition was determined so that the discharge failure portion could not be recognized as unevenness when viewed at a certain distance.

Actually, printing was performed as shown in FIG. Each of the squares was based on a uniform pattern with a certain gradation, and some of the squares were crafted so as not to discharge.

The non-ejection parts were provided in several places dispersed in one square.

The gradation is changed by 8 bits in the vertical direction from 0 to 255, and the 8-bit output corresponding to the gradation is output.
By multiplying Data by a certain ratio, OutputData as a complementary dot is obtained, and the ratio is shaken in the left-right direction.

For example, when the ratio indicated by the circle A is 0.2 and the OutputData indicated by the circle B is 255, the OutputData of the complementary dot is 255 × 0.2 = 51.
Becomes

Then, since the unevenness of the squares for that portion cannot be seen, it was evaluated as ◯ and expressed as shown in FIG. 32 (b). The subtle parts that are visible or invisible are indicated by △, and the visible parts are indicated by ×.

The same operation is performed for the other squares as shown in FIG.
The table of 2 (b) was completed.

FIG. 33 is shown based on FIG. 32 (b).

In FIG. 33, only the evaluations ◯ and Δ are shown here, and × is omitted.

Actually, the evaluation was performed in detail by changing the ratio of the squares in FIG. 32 more finely, and a complementary curve as shown by the solid line in FIG. 33 was obtained.

The upper and lower broken lines sandwiching the solid line are portions where the unevenness is not noticeable within the range.

Here, in the example shown in FIGS. 32 and 33, by multiplying the multi-valued data of the adjacent nozzles at both ends in one ejection failure by 1.5 times, the number of dots of the nozzle is increased by 1.5 times. Bk in the case of doing so, that is, in the case of performing adjacent complement
An example of dot completion is shown.

On the other hand, the pattern as shown in FIG. 32 (a) is printed as an inspection pattern on the main body and is read by, for example, a scanner or a sensor mounted on the main body.
You may make a judgment like (b) or FIG. In this case, by defocusing the sensor or the like, the sensitivity corresponding to the distance actually seen by the eyes is set, and it is possible to detect clearly white lines and clearly black lines in one square. It is conceivable to select an intermediate part in the set of squares excluding the ones, and by doing so, FIG.
You may obtain a correction curve like this.

Although an example of the correction method has been described in detail above, the case of complementing the discharge failure portion of magenta (M) with Bk is the same as that of C.

As described above, by complementing the color near the lightness of the original color to the part where the discharge failure occurs and the white streaks are generated,
It was found that if the width of non-ejection with respect to the clear viewing distance was sufficiently narrow, it would be difficult to be recognized as "streaking".

According to the present examination, by setting the color to be complemented to the lightness of the original color ± 20%, the unevenness is improved at least as compared with the case where the color is not complemented (on the contrary, black stripes etc. are not deteriorated). ) It has been found that it is possible to improve dramatically by setting the color within the lightness of the original color ± 10%.

Further, in the above example, an example in which complementary recording is performed in black has been given, but the same can be said for other colors.

It should be noted that by multiplying the multi-valued data of the adjacent nozzles at both ends in one ejection failure by 1.5 times on the plain paper, the number of dots of the nozzles is increased by 1.5 times. If the ink penetrability is high, the printed pattern will be 400d even if it is not complemented by other colors.
If the missing portion of the non-ejection portion is about 60 μm in pi, a large amount of ink is printed on the adjacent nozzles, and as a result, the ink bleeds into the non-ejection portion and streaks cannot be seen. However, when the ejection amount from the head is small and the dot diameter is small, the gap due to ejection failure may not always be filled.

Assuming such a case, it is preferable to change the ejection amount of the head so that the unevenness cannot be seen even when the above-mentioned printing pattern is printed, and to supplement the ink.

An example of printing on coated paper, which is a paper having a small bleeding rate and a bleeding rate of about 2.0, will be described below. Since the bleeding rate is small, complement with other colors.

<Example of Lightness Complementation Using Bk Ink>
A method of supplementing with Bk dots instead of the ejection failure nozzles will be described.

In this method, the dot for complementing has the lightness when the dot is uniformly printed based on the output data, and the lightness when the dot is uniformly printed by the output data of the ejection failure nozzle portion. On the other hand, it is characterized in that the recording is carried out based on the image data which is within a certain constant brightness difference.

Regarding the color to be complemented, it is natural that it is preferable to complement the color having similar chromaticity. For example, in the case of complementing the non-ejection nozzle of the head for cyan ink, it is possible to complement by matching the brightness using magenta or black ink. However, from the viewpoint of chromaticity, the boundary portion is relatively conspicuous due to the difference in chromaticity between cyan and magenta, and it is more preferable to complement with Bk. Specifically, it is converted into Bk data having a lightness that is within a certain lightness difference with respect to the lightness of the data to be originally output by the C nozzle, and the converted Bk data and the original Bk data are converted. Is added and output.

For example, an example of the conversion from C to Bk is performed as follows.

FIG. 4 is an example of a graph showing the lightness when gradation recording is performed on coated paper having a small bleeding rate with each color ink. The horizontal axis represents the input value corresponding to each color and the vertical axis represents the lightness. expressing.

Here, the cyan (C) data is "19".
When the value is "2", the lightness L ^* is about 56. On the other hand, the brightness at Bk is about 56 when the input value is about 56.

Therefore, when the data corresponding to the cyan non-ejection nozzle is "192", this data is converted to the black ink data "56".

B complemented with C and M thus obtained
The relationship with k is shown in FIG. FIG. 5 is a graph showing the output data for the complementary recording after the conversion with respect to the input data corresponding to the non-ejection nozzle. In the figure, #C_Bk shows the relationship when complementing cyan with black ink, and #M_Bk shows the relationship when complementing magenta with black ink. When the missing portion due to non-ejection of cyan or magenta is to be complemented with black ink, Bk obtained by converting the data corresponding to the missing portion using a table for conversion as shown in FIG.
By adding the data of B to the original Bk data and outputting the data, it is possible to reduce the influence of discharge failure. Regarding Y (yellow), originally, the brightness does not change much with respect to the paper surface. That is, since it is hard to see, it is not necessary to supplement with a different color. In FIG. 5, #Bk
_Cmy shows an example of complementing a black missing portion with three colors of C, M, and Y. It is also possible to compensate for discharge failure of Bk by using C, M, and Y. .

<Complementation by Head Shading> Next, a method of making a missing portion less noticeable by head shading processing will be described. Here, the head shading is a technique used to correct the density unevenness that is mainly caused by the variation in the ejection characteristics of the plurality of nozzles provided in the print head, and to make the density uniform. By setting the correction data of (1) corresponding to each nozzle, the density unevenness is made less noticeable. Specifically, read the density of the image experimentally recorded by the recording head with a scanner, set the correction data to increase the density for the nozzles corresponding to the low density area, and conversely for the high density area. By setting the correction data for lowering the density for the corresponding nozzle, the density is made uniform.

By performing this head shading processing, the print duty is corrected to be higher than the area corresponding to the discharge failure portion (missing portion) of the original image, at least around the pixels adjacent to the area. , It is possible to make the discharge failure part less noticeable.

That is, specifically, as will be described later, the head shading is performed by reading the density of the test pattern recorded by the recording head and changing the output γ of each nozzle according to the density unevenness. However, in the case of the output of the resolution of 400 dpi to 600 dpi, the reading density unevenness data is obtained by taking the average value of the densities of the target nozzle and the nozzle portions on both sides of the target nozzle as described below. It is regarded as the density and is corrected.

Therefore, if there is a nozzle in which ejection failure has occurred, the density corresponding to the nozzle portions on both sides of the nozzle will also decrease as a result. Therefore, the head shading process will cause the nozzle portions at both ends of the nozzle in which ejection failure has occurred. The print data is corrected to increase the density.

As a result, in the vicinity of the pixel corresponding to the non-ejection nozzle, the number of print dots is the same when both of its neighbors are included, as compared with the case where there is no non-ejection, so that it cannot be recognized as unevenness.

FIGS. 3A to 3E schematically show a state where the image data of the nozzle adjacent to the non-ejection nozzle is corrected by the head shading.

FIGS. 3A to 3D show an example in which four dots are recorded in each grid when dots are recorded with a duty of 100%. Also, FIG. 3 (e)
When dots are printed at 100% duty,
An example in which two dots are recorded in one grid is shown. Further, it is an image recorded by a recording head in which nozzles are arranged in the vertical direction of the figure, and a portion indicated by A in the figure is
The position where printing is not performed by the non-ejection nozzle is shown.

FIG. 3A shows an image recorded with a duty of 1/4, and the head shading processing corrects the data of the nozzles adjacent to the non-ejection nozzle so as to increase the density. As a result, the number of dots recorded increases. Further, FIG. 3E shows an image recorded with a duty of 1/8. When the duty is low as described above, the "streaks" generated by the non-ejection nozzles are not conspicuous, and the number of dots recorded by the adjacent nozzles increases, so that the apparent density is also recorded by the normal recording head. Compared with, there is no big difference.

FIG. 3B shows a duty of 50% (50%).
%), And FIG. 3C shows an image recorded with a duty of 3/4 (75%). In the example of FIG. 3C, the duty is high,
Since the density of the image corresponding to the non-ejection nozzle cannot be reproduced only by the nozzles adjacent to the non-ejection nozzle, correction is performed to increase the density of the nozzle at the second nozzle position from the non-ejection nozzle.

As shown in FIGS. 3 (b) and 3 (c), as the density of dots to be recorded increases, the missing portion at the position corresponding to the non-ejection nozzle (the position indicated by arrow A in the figure) It becomes "streaks" and becomes more noticeable.

Therefore, the above-described head shading processing can particularly effectively suppress a decrease in density caused by image loss due to non-ejection in an image area having a low duty.

FIG. 3 (f) shows an example of γ correction in the nozzle portion adjacent to the nozzle judged as non-ejection by the above head shading or the like. In the figure, 4a indicates a tilt without correction. 4b is for the original image data,
An example of correction for increasing the density by 1.5 times by γ correction will be shown.
In this way, for the nozzle adjacent to the non-ejection nozzle,
Gamma correction may be performed to increase the density up to 1.5 times.

As described above, in the case of a uniform print pattern, the low print dut is obtained by the head shading process.
In the case of y, the number of print dots in the vicinity of the non-ejection nozzle is almost the same as that of the surrounding area, and even with a high print duty, if the medium has a large bleed rate and a large dot diameter, it can be bleed to the non-ejection portion. , It becomes difficult to recognize as “unevenness” in almost all print duties.

Another example of printing on coated paper, which is a small bleeding rate with a bleeding rate of about 2.0, will be described below. Since the bleeding rate is small, complement with other colors is performed, but head shading is also performed.

<Combination of Lightness Complementation and Head Shading> A combination of the above-described method of compensating the discharge failure portion with another color and the method of using the nozzles on both sides of the discharge failure portion. To use.

Next, by combining the above-described method of matching the lightness and complementing with another color and the above-described head shading method, it is possible to more effectively make the loss of the image due to the non-ejection nozzle inconspicuous. Will be described.

At this time, it is preferable to appropriately correct and optimize various correction amounts for use. Low print dut
In the area y, due to the head shading, the number of dots printed in the vicinity of the pixel corresponding to the ejection failure nozzle is the same as that in the case where there is no ejection failure. It becomes unrecognizable (Fig. 3
(See (a) to (e)).

However, in the above-described head shading method, in the case of an image having a high print duty such as a solid image on a medium having a small bleeding rate, the portion corresponding to the non-ejection nozzle is easily visible as white streaks. It is recognized as "streak-like unevenness". Therefore, when the low print duty is corrected by head shading, and when the high print duty is supplemented by dots of other colors,
It is possible to suppress the deterioration of the image due to the non-ejection nozzle regardless of the difference in the print duty of the image.

FIG. 3 (f) shows an example in which the head shading process and the complementary process with another color are combined. For example, for the nozzles adjacent to the non-ejection nozzle, the correction is performed according to the straight line indicated by 4b in the figure, and when the duty is high, the portion corresponding to the non-ejection nozzle is complemented by another color. . Correction straight line 4b
Indicates γ correction for increasing the image density by 1.5 times. Further, for image data with a duty exceeding 2/3 (67%), the image data indicated by the dotted line 4c in the drawing is generated in correspondence with another color. By performing such processing, when the duty is lower than ⅔, the image density at the position corresponding to the adjacent nozzle is increased,
When the duty ratio is higher than ⅔, it is possible to perform complementary recording so as to match the lightness of the missing portion due to non-ejection with another color.

Hereinafter, based on the above-described complementary method of the present invention, an ink jet recording apparatus will be described in detail as an example.

In the present invention, any printer having a scanner function or a printer capable of inputting data obtained by reading a pattern for measuring density unevenness and discharge failure nozzles can be implemented. An inkjet type color copying machine capable of reading and recording images will be described as an example.

(First Example) An example in which the main body or the like judges that coated paper having a low bleeding rate is used will be described below.

<Method by Combination of Lightness Complementation and Bk Complementation> In this embodiment, different colors for ejection failure nozzles, especially black (B) for cyan (C) and magenta (M).
The ink of (k) is used to complement the lightness based on the image data corresponding to the ejection failure nozzle.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 10 is a side sectional view showing the structure of a color copying machine using the ink jet recording apparatus of this embodiment.

This color copying machine includes an image reading and image processing unit (hereinafter referred to as a reader unit 24) and a printer unit 44.
It consists of and. The reader unit 24 reads an image while scanning the original 2 placed on the original glass 1 by the CCD line sensor 5 having filters of three colors of R, G, and B, and processes the read image by an image processing circuit. do it,
The printer unit 44 records an image on paper or other recording medium (hereinafter also referred to as recording paper) by an inkjet head of four colors of cyan (C), magenta (M), yellow (Y), and black (Bk). There is.

It is also possible to input image data from the outside, process this data in the image processing circuit, and record it in the printer section 44.

The operation of the apparatus will be described in detail below.

The reader unit 24 is composed of members or parts 1 to 23, and the printer unit 44 is composed of members or parts 25 to 43. Further, in FIG. 10, the upper left side of the drawing is the front surface facing the operator.

The printer section 44 is provided with an ink jet head (hereinafter, also referred to as a recording head) 32 for recording by ejecting ink. The recording head 32 has, for example, one nozzle for ejecting ink.
28 nozzles are arranged, and discharge ports are formed on the discharge direction side of the nozzles. Here, 128 ejection ports are arranged side by side in a predetermined direction (sub-scanning direction described later) at a pitch of 63.5 μm, and a width of 8.128 mm can be recorded. Therefore, when recording on a recording sheet, the conveyance of the recording sheet (conveyance in the sub-scanning direction) is once stopped, and in this state, the recording head 32 is moved in the direction perpendicular to the drawing to obtain a necessary distance of 8.128 mm. After recording only, the operation of feeding the recording paper by 8.128 mm and stopping it, and recording the next image with a width of 8.128 mm is repeated. This recording direction is called the main scanning direction, and the paper feed direction is called the sub-scanning direction.

In the structure of this embodiment, the main scanning direction is as shown in FIG.
The direction perpendicular to the sub-scanning direction is the left-right direction in FIG.

Further, the reader unit 24 repeats the operation of reading the original 2 with a width of 8.128 mm corresponding to the printer unit 44, but the reading direction is the main scanning direction and the moving direction for the next reading is the sub direction. This is called the scanning direction. In the configuration of this embodiment, the main scanning direction is the left-right direction in FIG. 10, and the sub-scanning direction is the direction perpendicular to FIG.

The operation of the reader section 24 will be described below.

The original 2 on the original platen glass 1 is illuminated by the lamp 3 on the main scanning carriage 7, and its image is passed through the lens array 4 to the light receiving element 5 (CCD line sensor).
Be led to. The main scanning carriage 7 is fitted on a main scanning rail 8 on the sub scanning unit 9 and is slidable. Further, the main scanning carriage 7 is connected to the main scanning belt 17 by an engaging member (not shown), and is moved in the vertical direction in FIG. 10 by the rotation of the main scanning motor 16,
The main scanning operation is performed.

The sub-scanning unit 9 is fitted on a sub-scanning rail 11 fixed to the optical frame 10 and is slidable. Further, since the sub-scanning unit 9 is connected to the sub-scanning belt 18 by an engaging member (not shown), the sub-scanning motor 19 rotates to move in the vertical direction in FIG.
The sub-scanning operation is performed.

Thus, the image signal read by the CCD 5 is transmitted to the sub-scanning unit 9 by the flexible signal cable 13 which can be curved in a loop. One end of the signal cable 13 is clamped (held) by the clamping unit 14 on the main scanning carriage 7, and the other end is fixed to the bottom surface 20 of the sub scanning unit by a member 21.
Sub-scanning unit 9 and electrical unit 26 of printer unit 44
It is connected to a sub-scanning signal cable 23 that connects to. Here, the signal cable 13 follows the movement of the main scanning carriage 9, and the sub-scanning signal cable 23 follows the movement of the sub-scanning unit 9.

FIG. 11 shows the CCD line sensor 5 of this embodiment.
It is a figure which shows the detail of. This line sensor 5 is provided with 498 light receiving cells in a line, and is composed of three R, G, and B pixels.
Since the pixels are formed, 166 pixels can be read substantially. Of these, the effective number of pixels is 144,
The pixel width composed of this number of pixels is approximately 9 mm.

The operation of the printer unit 44 will be described below.

The recording papers fed out one by one from the recording paper cassette 25 by the paper feed roller 27 driven by a power source (not shown) are two pairs of rollers 28 and 2.
Recording is performed by the recording head 32 between 9 and 30, 31. The recording head 32 is configured integrally with the ink tank 33, and is detachably mounted on the printer main scanning carriage 34. The printer main scanning carriage 34 is fitted on the printer main scanning rail 35 and is slidable.

Further, since the printer main scanning carriage 34 is connected to the main scanning belt 36 by an engaging member (not shown), the main scanning motor 37 rotates to move in the direction perpendicular to FIG. Perform a scanning operation.

The printer main scanning carriage 34 has an arm portion 38, and a printer signal cable 39 for transmitting a signal to the recording head 32 is fixed. The other end of the printer signal cable 39 is fixed to the printer middle plate 40 by a member 41, and is further connected to the electrical component unit 26. The printer signal cable 39 follows the movement of the printer main scanning carriage 34, and the upper optical frame 1
It is configured so that it never touches 0.

The sub-scanning of the printer unit 44 is performed by rotating the two pairs of rollers 28, 29 and 30, 31 by a power source (not shown) to convey the recording paper by 8.128 mm. 42 is a bottom plate of the printer unit 44, 4
Reference numeral 5 is an exterior plate, 46 is a pressure plate for pressure-bonding a document to the platen glass 1, 1009 is a paper discharge port (see FIG. 23), 47 is a paper discharge tray, and 48 is an electrical component of the operation surface.

FIG. 12 is a perspective view showing the outer appearance of the ink jet cartridge in the printer section 44 of the color copying machine of this embodiment. FIG. 13 is a perspective view showing details of the printed circuit board 85 of FIG.

In FIG. 13, 85 is a printed circuit board, and 8
Reference numeral 52 is an aluminum heat radiating plate, 853 is a heater board consisting of heating elements and a diode matrix, and 854 is a storage means for storing individual nozzle information in advance, which is an EEPROM.
A non-volatile memory such as the above and other appropriate forms are also possible.

In the present embodiment, the information on whether or not the nozzle is not ejected is stored, but it is also possible to store information such as density unevenness.

Reference numeral 855 is a contact electrode which serves as a joint with the main body. The ejection port group arranged in a line is not shown here.

By doing so, when the recording head 32 is mounted on the main body device, the main body device reads out information relating to the ejection failure nozzle from the recording head 32, and based on this information, predetermined control for improving uneven density is performed. To do. As a result, it is possible to secure high quality image quality.

14 (a) and 14 (b) are diagrams showing an example of a circuit configuration of a main part on the printed circuit board 85 of FIG. Here, the inside of the frame of the one-dot chain line shown in FIG. 14A is the circuit configuration inside the heater board 853, and this heater board 853 is provided with the heating element 857 and the diode 8 for preventing the sneak of current.
56 and an N × M matrix structure of circuits connected in series. That is, these heating elements 857 are driven in time division for each block as shown in FIG. 15, and the control of the supply amount of the driving energy is performed by the segment (Se).
It is realized by changing and controlling the pulse width (T) applied to the g) side.

FIG. 14B shows the EEPROM 85 of FIG.
4 is a diagram showing an example of No. 4, and in the present embodiment, information regarding a discharge failure nozzle is stored. This ejection failure nozzle information is output to the image processing unit on the main body apparatus side.

FIG. 18 shows an example of the arrangement of the image processing section in this embodiment.

In FIG. 18, an image signal read from the CCD sensor 5, which is one of the solid-state image pickup elements, has its sensor sensitivity corrected by a shading correction circuit 91, and the three primary colors R (red) of light are red by a color conversion circuit 92. ), G (green), B (blue) to print colors C (cyan), M
It is converted into (magenta), Y (yellow), and Bk (black).

This conversion is usually performed using a three-dimensional LUT (look-up table), but it is not particularly limited to this method. The print colors are C, M, Y, Bk.
Not only low density LC (light cyan), LM
It is applicable even when (light magenta) or the like is included.

It is also possible to directly input the image data from the outside to the color conversion circuit 92 for processing.

C, M, which are converted from these RGB,
The Y and Bk signals are input to the data conversion unit 94. In the data conversion unit 94, the ejection failure nozzle information of the storage unit 854 provided in the ink jet recording head or the ejection failure nozzle information calculated through the measurement of the ejection failure nozzle is used to perform data conversion as described later, It is supplied to the γ conversion circuit 95. The characteristics of each nozzle used here are stored in the memory in the data conversion unit 94.

The γ conversion circuit 95 has, for example, as shown in FIG. 19, a function of several steps for calculating output data with respect to input data, and is suitable for the density balance of each color and the user's preference of hue. The appropriate relationship is selected accordingly. Further, this function is determined according to the ink characteristics and the recording paper.
The γ conversion circuit 95 can be incorporated in the color conversion circuit 92. This output is sent to the binarization circuit.

In this embodiment, the error diffusion method (ED) is adopted.

The output of the binarization processing circuit 96 is the printer unit 4
4 and is recorded by the recording head 32.

Although the image is output using the binarization processing circuit in this embodiment, the present invention is not limited to this binarization processing circuit. For example, it may be ternarization using large and small dots, or an n + 1 binarization processing circuit by recording 0 to n dots in one pixel. It may be appropriately selected according to various output methods.

Hereinafter, the non-ejection nozzle / density unevenness measuring section 93 and the data converting section 94 which constitute the data processing section 100, which is the most important operation of the present invention, will be described.

FIG. 20 shows the data processing unit 1 in FIG.
10 is a block diagram of a configuration example of a main part showing a function of No. 00, and portions surrounded by broken lines respectively indicate discharge failure nozzle / density unevenness measuring section 93.
And the data conversion unit 94.

First, the discharge failure nozzle / density unevenness measuring section 93
The specific operation of will be described.

If it is necessary to update the information on the discharge failure nozzle, this processing consists of printing a discharge failure / unevenness reading pattern, reading the same pattern, and data calculation. It can be omitted if it is not necessary.

In this embodiment, the correction processing for the density unevenness is not performed, but the misfiring nozzle / density unevenness measuring section 93 can also obtain the information on the density unevenness and is used in other embodiments. Therefore, I will add the explanation.

When updating the information related to the discharge failure nozzle,
First, the discharge failure / unevenness reading pattern is printed.
Prior to that, the head recovery operation is first performed. This is a preparation for performing unevenness reading pattern printing in the best state by performing a series of operations such as removal of ink adhered to the recording head 32, removal of bubbles by sucking ink from the nozzles, and cooling of the head heater. It is a strongly desirable behavior.

Next, the unevenness reading pattern shown in FIG. 24 is printed out. The print pattern is a halftone with a density of 50%, printed in 4 blocks for each color in the vertical direction in the figure, for a total of 1
It consists of 6 blocks. The pattern is printed at a predetermined position on the recording paper. In addition, each block is made by printing three lines, and the first and third lines eject from only the 16 nozzles of the lower end and the upper end of the 128 nozzles, and the second line ejects from all 128 nozzles. By doing so, a halftone print block having a print width of 160 nozzles in total is obtained. The reason for recording each block with a width of 160 ejection ports is as follows.

As shown in FIG. 25, when a recording head 32 consisting of 128 nozzles is used, when the pattern recorded by the recording head 32 is read by the CCD sensor 5 or the like, the ground color of the recording paper is read. The density data An tends to lag due to the influence of (for example, white). Therefore, if each block is recorded with only 128 ejection ports, the reliability of the density data of the end ejection ports may be lost. Therefore, in this embodiment, printing is performed with 160 ejection ports, density data above a certain threshold is treated as valid data, and the center of the valid data is regarded as the central ejection port, and from that point, (number of ejection ports) / 2
(64 in this case) The data at points separated by 64 points were made to correspond to the first ejection port and the 128th ejection port, respectively.

The number of nozzles for printing the both-end pattern is
It is not particularly limited to 16 nozzles. In this embodiment, 16 nozzles are determined for the purpose of saving the data storage memory.

After the printing of the reading pattern is completed, the output recording paper 2 is placed on the document table 1 of FIG. 23 with the pattern facing downward, and four blocks of the same color are arranged in line in the main scanning direction of the CCD sensor 5. Start reading the uneven pattern.

Prior to the discharge failure / unevenness reading, the shading processing of the CCD sensor 5 is first performed using the reference white plate 1002 of FIG. 23, and then the unevenness reading pattern is read. Here, one line refers to one main scan of the CCD sensor that reads four blocks of a certain color at one time. Therefore, by reading one line, a black pattern for four blocks is stored in the memory. The read data (density data) of each of the four blocks is printed at a predetermined position on the recording paper so as to fit in a predetermined area of the memory. The shape of the read data is normally as shown in FIG. Here, the horizontal axis represents the reader address and the vertical axis represents the density. As described above, the range above a certain density level is set as the print area. Here, it is confirmed whether the address X1 of the density which exceeds the threshold for the first time is within the allowable range. . If the print start position starts at X from the beginning of reading by the reader, it is checked whether X1 is within X ± Δx, and further at the position of X1 + 160 ± Δx, whether the data falls below the threshold.

If this is not satisfied, there is a possibility of diagonal placement, so it is judged as an error and the processing is retried or data rotation processing is performed, and then the check is performed again. In this way, there is a one-to-one correspondence between data and nozzles. In the ejection failure nozzle detection, the density data in the range from X1 to X2, which is determined as the print area, is taken out pixel by pixel, and it is checked whether the density data is below the threshold for the ejection failure nozzle.

Generally, as shown in FIG. 26C, when only one nozzle is not ejected, the density of the area does not drop to the same level as the blank area. Therefore, in the present embodiment, a threshold for detecting the ejection failure nozzle is separately provided, and it is determined that ejection failure occurs when the data in the print area is lower than this threshold.

By the way, when the state of the head itself is unstable, the ejection port may suddenly fail to eject.

For example, if all four of the four print patterns in FIG. 24 have ejection failure, this is complete ejection failure. However, if there is no ejection failure other than one area,
It is also possible to judge that the portion where there is no ejection is sudden and to use only the remaining portion for calculation, or to start printing again as an error. It should be noted that it is possible to detect the non-ejection threshold value at the same time by providing the print area threshold value described above at a slightly higher position without providing a special threshold value.

Now, these data are input to the discharge failure / unevenness calculation circuit 135 (FIG. 20).

The calculation in this embodiment is the ejection failure nozzle determination processing, but the density ratio determination processing for unevenness correction is also shown.

Here, from the point where data is actually input in the form as shown in FIG. 26C, description will be made sequentially with reference to FIG. First, the rising positions X1 and X2 at both ends are averaged to obtain the center value of the print area. This is determined to be the central portion of the nozzle row, that is, between the 64th and 65th nozzles. Therefore, the data at the positions of 64 pixels before and after the central portion are the densities of the 1st nozzle and the 128th nozzle. As a result, the print density n (i) including the joints at both ends is obtained at each nozzle. Here, when the print density n (i) for each nozzle is smaller than the threshold for detecting the discharge failure nozzle,
The nozzle is determined to be an ejection failure nozzle, and the density ratio information of the nozzle is set to d (i) = 0. Further, in this embodiment, since the density ratio calculation shown below is not performed, the density ratio information of the other nozzles is set to d (i) = 1.

The density ratio information can be set as follows.

Average density A of all nozzles excluding discharge failure nozzles
VE is obtained, and the density ratio d (i) = n (i) / AVE of each nozzle to the average density is used as the density ratio information of each nozzle.

However, it is not preferable to use the density data of the area having only the width of one pixel as the density data of the nozzle as it is. This is because, as shown in FIG. 28, it is certain that one pixel of the reading area also includes the density of the dots ejected from the nozzles on both sides, and it is somewhat left or right for any nozzle. This is because it is unavoidable to be dependent. Furthermore, it is desirable to take into consideration that the density unevenness seen by the human eye is influenced according to the surrounding situation including the pixel of interest.

Therefore, practically, before determining the density of each nozzle, as shown in FIG. 29, the density data (A _i-1 , A _i , A _{i) of} about 3 pixels including the pixel and the pixels on both sides are included. ₊₁
), The average value of the
(I), and using this value, the density ratio information d of each nozzle
It is preferable that (i) = ave (i) / AVE.
A correction table described below is created using this density ratio information.

The density ratio information d (i) is processed in the correction table calculation circuit 136 (see FIG. 20) to set the correction table for each nozzle.

If the table number of this determinant is T (i), then T (i) = # 63: 1.31 <d (i) # (d (i) -1) × 100 + 32: 0.69 ≦ d (I) ≦ 1.31 # 1: 0 <d (i) <0.69 # 0: d (i) = 0. Here, as shown in FIG. 21, 64 correction tables # 0 to # 63 are prepared, and the table number # 3
The slope is increased / decreased little by little around 2.

The table number # 32 is a straight line having a slope 1 in which the input value and the output value are always equal. This is a table to be taken by the ejection ports for obtaining the average density of 128 ejection ports. The remaining curves, which are shaken up and down, have a table at a density of 50% (80H), which is the same as the print sample, centered at # 32 in 1% steps.

Therefore, T (i) obtained by the above equation is always 8
In the input signal of 0H, the signal value conversion matching the density ratio is performed. In addition, # 0 corresponds to the non-ejection nozzle, and the outputs thereof are all set to 0.

When 128 T (i) have been obtained in this way, the 1-line correction table number calculation ends.

In this embodiment, since the density ratio determination process is not performed, # 0 or # 32 is calculated for all nozzles.

As described above, the discharge failure nozzles and unevenness for one line, that is, one color, and the calculation of the correction table number for each nozzle corrected from the data are completed. The same process is performed for. After the correction table numbers for four colors are calculated, the correction table number holding unit 137 is updated next. The correction table number read from the recording head storage information 854 which is a storage unit is stored therein, and the latest correction table number calculated here is the correction table number holding unit 137 and the recording head storage information. It is rewritten to the contents of 854.

That is, when the non-ejection / unevenness detection is not performed, the correction table number held in the print head storage information 854 is used for the following processing.

In the data conversion arithmetic circuit 138, the image signal to be output is output using the above-mentioned correction table for each nozzle and converted into a signal for each head. The flow of this processing is shown in FIG.

C, M, Y, input to the data conversion unit 94
The K image signal is associated with the nozzle that actually prints. Further, when recording is performed, data of each color having the same pixel is selected and collectively processed.

Here, the density correction table for each nozzle is referred to and the data is converted. This data conversion is roughly classified into two cases, that is, the correction tables # 1 to # 63 and # 0, that is, the ejection failure.

When the correction tables are # 1 to # 63,
The input signal is sent as it is to the color-specific data addition unit.

On the other hand, when the correction table is # 0, that is, when the nozzle is not ejected, complementary data for compensating for it is created. For example, when the input signal is C, # C-K
If the correction table, the input signal is M, the # M-K correction table is used to create Bk data. When the input signal is Y, Bk data is not created, and when it is Bk, # Bk-cmy is used to create C, M, and Y data.

This complementary data is, in the present embodiment,
As described above, it is created so that the brightness is almost equal. FIG. 4 is a graph showing the output value of the brightness of each color with respect to the input value, and a complementary table is created based on this graph.
For example, when the cyan (C) data is "192" (8-bit input), the brightness is about 56.

On the other hand, the brightness of black (Bk) is about 56 when the 8-bit input value is about 56 (Bk = 5).
6) As a result, C = 192 is converted into Bk = 56. Black (B) for magenta (M) obtained in the same manner
The supplementary table (# M-K) of k) is also shown in FIG.

On the other hand, the complement of yellow (Y) is not particularly performed in consideration of the fact that the brightness of yellow (Y) is always high. In addition, for complementing black (Bk), C, M, and Y are complemented at the same rate.
The complementary table obtained as a result is shown in FIG. 5 as # Bk-cmy.

Although complementary data is created using these complementary tables, it is actually desirable to consider the relationship between the dot diameter to be printed and the pixel pitch. For example,
In this embodiment, the dot diameter to be recorded is about 95 μm and the pixel pitch is 63.5 μm. This is 100
This is because the area factor is set to 100% even if there is some landing deviation when printed.

Therefore, for example, in the case where only one nozzle is not ejected, the pixels recorded on both sides of the pixel for which the ejection failure nozzle is affected are considerably affected.

In other words, the complemented dots recorded in the ejection failure nozzle portion have a considerable influence on the pixels on both sides thereof.

This is equivalent to that the data to be supplemented may be smaller than the value obtained from the relationship with the brightness if the non-ejection nozzles are not continuous.

Therefore, in this embodiment, the complementary table as shown in FIG. 6 was used.

The complementary data created here is sent to the data addition section for each color.

The data addition unit has a function of holding data for each color and a function of arithmetic processing. When the data input to this data addition unit is the first time, the data is held as it is. If the data is already held, the data is added. If the added data exceeds 255 (FFH), it is held as 255. Although the simple addition process is performed in this embodiment, various calculations and processes using tables may be performed as necessary.

After the data addition processing is performed for all the colors of C, M, Y and Bk, this data is passed to the data correction section, the data of the data addition section is reset, and the processing of the next pixel is performed. Will be waiting for. The data passed to the data correction unit is converted according to the correction table (# 0 to # 63) of the nozzle, and the series of data conversion ends.

The data thus converted is output as an image through the γ conversion circuit 95, the binarization processing circuit 96 and the like.

When the images thus obtained were closely approached and gazed, the non-ejection part could be recognized, but the image as a whole was almost good.

<Example of Processing by Head Shading>
What will be described here is that the ejection failure nozzle is corrected in a series of operations of head shading, so-called “density unevenness” correction. This will be specifically described below.

This example is also carried out by the same system as that of the above-mentioned embodiment. The difference is that unevenness correction is performed.
It is not to create complementary data with different colors.

Focusing on these two points, the following data conversion processing,
That is, the processing of the discharge failure nozzle / density unevenness measuring unit 93 and the data converting unit 94 will be described.

In FIG. 18, the processing in the discharge failure nozzle / density unevenness measuring section 93 is basically the same as that in the above-mentioned embodiment. As shown in the block diagram of FIG. 20, first, a discharge failure / unevenness reading pattern is printed, then this image data is read using a CCD sensor, and processing such as addition and averaging is performed, and then, as shown in FIG. A print density n (i) associated with such a nozzle can be obtained.

Now, in order to facilitate understanding of this example, first, the basic factors causing uneven density will be described.

FIG. 16A shows an ideal recording head 32.
FIG. 3 is a schematic diagram showing an enlarged recording state in FIG. 6 in the figure
Reference numeral 1 denotes an ink ejection port. When recording is performed by the recording head 32, ink spots 60 having a uniform drop diameter (droplet diameter) are aligned and recorded on the paper.

Incidentally, in the same figure, the case of so-called full discharge (all discharge ports are ON) is shown, but density unevenness does not occur even in the case of halftone such as 50% output.

On the other hand, in the case shown in FIG. 16B, the drop 6 of the second and (n−2) th discharge ports is
The diameters of Nos. 2 and 63 are smaller than the others, and the (n-2) th and the (n-1) th are recorded at positions displaced from the ideal landing center. That is, the (n−2) th drop 63 is recorded at the upper right of the center, and the (n−1) th drop 64 is recorded at the lower left of the center.

As a result of recording in this way, FIG.
The area A shown in (b) appears as thin lines, and the area B
Also in the region, the (n-1) th and (n-2) th center-to-center distances are larger than the average distance l ₀ between the drops, and as a result, appear as thinner lines than other regions. On the other hand, C
In the region, the (n-1) th and nth center-to-center distances are narrower than the average distance l ₀ , and therefore appear as darker lines than other regions.

As described above, the density unevenness mainly appears due to the variation in the drop diameter and the deviation from the center position (this is generally referred to as "wobble").

As a means for coping with the uneven density, it is effective to detect the image density in a certain area and control the amount of ink applied to the area based on the detected value.

For example, as shown in FIG. 17A, for 50% halftone recording by an ideal recording head,
In order to make the density unevenness inconspicuous in the recording by the recording head having the "dispersion" and "wobble" of the drop diameter as shown in FIG. That is, as an example, by bringing the total dot area in the area inside the broken line a shown in FIG. 17B close to the total dot area of the area a in FIG. 17A, the characteristics shown in FIG. Even when recording is performed by the recording head having the above, it is possible to visually perceive the same density as that in FIG.

By performing the same operation for the area b in FIG. 17B, the density unevenness can be practically eliminated.

Note that FIG. 17B shows the processing result of the density correction control as a model for simplification of the description, and α and β indicate correction dots.

Further, this system can be applied to the non-ejection nozzle by regarding that the ejected drop diameter approaches to "0" without limit.

From this point of view, the density ratio data corresponding to each nozzle is as shown in the above-mentioned embodiment.

[0233]

[Equation 1] Is important. That is, i₀Nozzle of discharge
If n (i₀) = D (i ₀) = 0. For that reason,
Nozzles i on both sides of the discharge nozzle₀+1, i₀At -1
Is the effective density ave (i₀+1), ave
(I₀-1) is n (i₀+1), n (i₀Compared to -1)
Will be a much smaller value. As a result, the density ratio information d
(I₀+1), d (i₀-1) becomes substantially smaller, which will be described later.
With the correction table, you can output higher density.
It is set and plays a role of supplementing the discharge failure nozzle. Servant
Calculation to calculate the effective density ave (i) for each nozzle.
The formula is limited to the average value of the three pixels before and after shown above.
Instead of, for example, ave (i) = (2n (i-1)
Appropriate weighting such as + 2n (i + 1) / 5
The average value may be used and can be selected as appropriate.
It

The density ratio information d (i) thus obtained
Is a correction table arithmetic circuit 136 in the data conversion unit 94.
And the correction table for each nozzle is set. This processing is the same as that shown in the above-mentioned embodiment, and detailed description will be omitted.

It should be noted that the density correction table shown in FIG.
Although it is a book, it can be increased or decreased as needed. Also, depending on the characteristics of the output medium or ink, for example, FIG.
It is also possible to use a non-linear correction table as shown in.

After setting the correction tables for all the heads as described above, the correction table number holding unit 13
7 and the contents of the printhead storage information 854 are updated.
The data conversion of the output image is performed by the data conversion arithmetic circuit 138 using the correction table set here. This conversion is almost the same as that of the above-described embodiment, but in this example, since complementation by a different color is not performed, it is further simplified.

The flow of the processing is as follows: judgment of the correction table in FIG. 8 (step S2003), creation of different color data (step S2005), data addition (step S2003).
2006), is omitted. The data complemented in this way passes through the γ conversion circuit 95 as necessary, and is binarized by the binarization processing circuit 96.
The image will be output.

The image thus obtained was a good image in which the influence of discharge failure was hardly seen particularly in the highlight portion.

However, in the high print duty portion, white streaks due to ejection failure may not always be compensated.

(Second Embodiment) In this embodiment as well, an example will be described in which printing is performed on coated paper, which is a paper with a low bleed rate of about 2.0.

<Complementation by Head Shading and Different Color> This embodiment is an embodiment in which discharge failure complement utilizing different colors of the first embodiment and discharge failure complement by head shading are combined. A system similar to the example of head shading in FIG.

The data conversion process showing the operation of this embodiment will be described below.

In the block diagrams of FIGS. 18 and 20, the ejection failure nozzle / density unevenness measuring section 93 operates in exactly the same manner as in the case of the second embodiment. The ejection / unevenness reading pattern is read, the ejection failure nozzles are detected, the print density for each nozzle is calculated, and the density ratio information for each nozzle is calculated.

The density ratio information thus obtained is processed by the correction table arithmetic circuit 136 in the data conversion unit 94 in the same manner as in the first embodiment, and the correction table for each nozzle is set. . This setting updates the contents of the correction table number holding unit 137 and the recording head storage information 854, and the contents are used by the data conversion arithmetic circuit 138. The processing in the data conversion arithmetic circuit 138 is
The processing is basically the same as the processing shown in the above-described embodiment (see FIG. 8).

The difference is that when the target nozzle is not ejected, that is, when the correction table number is # 0,
It is the contents of the different color correction table for creating complementary data of different color for complementing. In the present embodiment, since density correction is performed for each nozzle by head shading and correction is performed so that the nozzles on both sides of the non-ejection nozzle compensate for the non-ejection nozzle, it is not possible to complement a different color especially in a highlight portion having a low print duty. It is preferable not to do it. Further, even in a shadow portion having a relatively high print duty, since there is a correction effect by the nozzles on both sides of the above-mentioned non-ejection nozzle, the degree of complementation with a different color is small compared to the case of the above-mentioned embodiment. .

Specifically, when the complementary curve of Bk for C and M in FIG. 5 is f (x) (x is InputData), the new complementary curve of Bk is βf (x-δ).

Therefore, in this embodiment, the data conversion processing is performed using the different color complementation table as shown in FIG.

That is, since the above-described head shading processing causes a large number of dots to be recorded by the nozzles on both sides adjacent to the nozzle in which ejection failure has occurred, the number of dots to be recorded for complementing different colors can be small. For example, FIG. 4F is a diagram showing an image of the correction table,
For the input value as shown in FIG. 21, the nozzles adjacent to the non-ejection nozzle are not corrected (correction straight line 4
As compared with a), correction is performed to increase the density by 1.5 times (correction straight line 4b). This correction is shown in FIGS.
This corresponds to (d). 3 (a), (b), (c),
The grid shown in (d) shows the size in which four dots are recorded inside. Therefore, FIG. 3A shows a uniform pattern of low printing duty in which one dot is recorded in one grid.

The recording head for recording dots shown in FIG. 3 has nozzles arranged in the vertical direction of the drawing.
Here, the case where the nozzle corresponding to the third dot position from the top is not ejected is shown. A circle represented by a solid line shows a dot position printed by a normal nozzle, and a circle represented by a fine broken line shows a dot position that should be originally printed by a non-ejection nozzle. In addition, a rough dashed circle represents a dot recorded for complementation. As can be seen from this figure, it is preferable that the nozzles on both sides adjacent to the nozzle in which the ejection failure has occurred be recorded 1.5 times.

However, in an image having a high dot density, white streaks tend to stand out. In particular, since dots are formed small depending on the recording medium, white streaks are conspicuous even in an image having a duty exceeding 1/2. Thus, in an image with a high print duty, by recording dots of other colors at the positions corresponding to the ejection failure nozzles, it is possible to make the missing parts less noticeable. Therefore, here, 2/3 duty (6
In an image having a duty of 7% or more, a dot adjacent to the ejection failure nozzle is printed with a duty of 100%, and is also printed at a position corresponding to the ejection failure nozzle so as to be complemented with another color. It should be noted that, in order to make the missing portion inconspicuous only with the nozzles adjacent to the non-ejection nozzle, it is necessary in principle to print dots with a duty of 100% or more. Since the colors are complemented, the number of dots to be printed can be reduced to 100% for the nozzles adjacent to the ejection failure nozzle.

When the data was converted in this way and the image was output, a good image could be obtained over almost the entire area from the highlight portion to the shadow portion.

Whether or not the recording medium is to be complemented with another color may be set in advance by the main body or the printer driver. However, an ink droplet is printed on the front end of the printed matter and the dot is printed. A configuration in which the diameter is measured by a main body or the like and the bleeding rate of the recording medium is recognized is preferable.

The present invention is particularly equipped with means for generating thermal energy as energy used for ejecting ink (for example, an electrothermal converter or a laser beam) among the ink jet recording systems, and The effect is excellent in a recording head and a recording apparatus of a type that causes a change in ink state by energy.

This is because such a system can achieve high density recording and high definition recording.

Regarding its typical structure and principle, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both so-called on-demand type and continuous type,
In particular, in the case of the on-demand type, the electrothermal converter arranged corresponding to the sheet or the liquid path holding the liquid (ink) is capable of rapidly responding to the recorded information and exceeding the nucleate boiling. By applying at least one drive signal for increasing the temperature, heat energy is generated in the electrothermal converter, and film boiling is generated on the heat acting surface of the recording head.
As a result, it is possible to form bubbles in the liquid (ink) that correspond one-to-one to this drive signal, which is effective. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. 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 which can be recorded by the recording apparatus. 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 recording head integrally formed.

In addition, even in the case of the serial type as in the above example, when the recording head fixed to the apparatus main body or the apparatus main body is mounted, electrical connection with the apparatus main body and ink from the apparatus main body are generated. 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 integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add the ejection recovery means of the recording head, the auxiliary auxiliary means, etc. because the effects of the present invention can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or suctioning means, electrothermal converters or other heating elements,
Or preheating means for heating using a combination of these,
Preliminary ejection means for performing ejection different from recording can be mentioned.

Regarding the types and the number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, and a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode only for the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by mixed colors.

[0261]

EFFECTS OF THE INVENTION In addition to eliminating the unevenness of the image such as white streaks caused by the non-ejected dots, even if the non-ejection occurs, these irregularities cannot be recognized by the human eyes and the cost of the inkjet head is increased. This has the effect of suppressing and further increasing the printing speed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a missing state and a complementing state of a printed image and a graph showing a relationship between a clear visual distance and a missing width.

FIG. 2 is a block diagram showing a method of complementing a nozzle portion of a discharge failure head with Bk only for both low print duty and high print duty.

3 (a), (b), (c), (d), (e),
(F) is an explanatory view showing an example in the case of an image design of 1 dot per pixel

FIG. 4 is a graph showing output values of lightness of each color with respect to input values.

FIG. 5 is a graph showing an example of conversion for complementing with different colors.

FIG. 6 is a graph showing an example of conversion for complementing with different colors.

FIG. 7 is a graph showing an example of conversion for complementing with different colors.

FIG. 8 is a flowchart showing processing of a data conversion arithmetic circuit.

FIG. 9 is a graph showing an example of conversion for complementing with different colors.

FIG. 10 is a side sectional view showing the configuration of a color copying machine as an example of an inkjet recording apparatus in this embodiment.

FIG. 11 is a detailed explanatory diagram of a CCD line sensor (light receiving element).

FIG. 12 is an external perspective view of an inkjet cartridge.

FIG. 13 is a perspective view showing details of a printed circuit board 85.

14A and 14B are explanatory views showing a circuit configuration of a main part on a printed circuit board 85.

FIG. 15 is an explanatory diagram showing an example of a time-division drive chart of the heating element 857.

FIG. 16A is a schematic diagram showing a recording state with an ideal recording head, and FIG. 16B is a schematic diagram showing a state in which there are variations in drop diameter and wobble.

FIG. 17A shows an ideal recording head 50.
% Is a schematic diagram showing a halftone state, and (b) is a schematic diagram showing a 50% halftone state with variations in drop diameter and wobble

FIG. 18 is a block diagram showing a configuration example of an image processing unit in this embodiment.

FIG. 19 is a graph showing the input / output relationship of the γ conversion circuit 95.

FIG. 20 is a block diagram of a configuration example of main parts showing the function of the data processing unit 100.

FIG. 21 is a graph showing an example of a density correction table for nozzles.

FIG. 22 is a graph showing an example of a non-linear density correction table for nozzles.

FIG. 23 is an external perspective view of the inkjet recording apparatus main body.

FIG. 24 is an explanatory diagram of the print output status of the unevenness reading pattern.

FIG. 25 is an explanatory diagram showing an example of a recording pattern by a recording head including 128 nozzles.

26 (a), (b), and (c) are explanatory views showing patterns of read print density data.

FIG. 27 is an explanatory diagram showing a pattern of print density corresponding to nozzles.

FIG. 28 is an explanatory diagram showing the state of pixels in the reading area.

FIG. 29 is an explanatory diagram of pixel density data.

FIG. 30 (a) is a relational graph in which the horizontal axis is the gray lightness (brightness of the portion b) and the vertical axis is the clear visual distance at which unevenness is not visible after the complement; (b) is the minimum value lightness (about 56) in the case of complementation and in the case of non-complementation, the horizontal axis is the clear visual distance, and the vertical axis is the missing width in which unevenness cannot be seen. (C) is the relationship graph in (b). Graph detailed in the section

FIG. 31 (a) is an explanatory view showing an example in which the missing portion b is complemented by a pattern in which Bk dots are thinned out, and FIG.
Partial enlarged view of

FIG. 32 (a) Bk in the case of performing adjacent complement
An example of dot complementation, (b) is an image unevenness evaluation table for the human eye

FIG. 33 is an explanatory diagram showing a graph of FIG. 32.

[Explanation of symbols]

1 Platen glass 2 manuscripts 3 lamps 4 lens array 5 CCD line sensor (light receiving element) 7 Main scanning carriage 8 main scanning rails 9 Sub-scanning unit 10 Optical frame 11 Sub-scanning rail 13 signal cable 14 Clamping part (holding part) 16 Main scanning motor 17,36 Main scanning belt 18 Sub scanning belt 19 Sub-scanning motor (of reader unit 24) 23 Sub scanning signal cable 24 Reader section 25 recording paper cassette 26 Electrical unit 27 paper feed roller 32 inkjet head (recording head) 34 Printer main scanning carriage 37 main scanning motor (of printer unit 44) 39 Printer signal cable 44 Printer unit (inkjet printer) 45 Exterior plate 46 Crimping plate 47 Output tray 85 printed circuit board 90 Image data signal 91 Shading correction circuit 92 color conversion circuit 93 Discharge nozzle / density unevenness measurement unit 94 Data converter 95 γ conversion circuit 96 binarization processing circuit 100 Data processing unit 854 recording head memory information

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Shibata             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2C056 EA08 EA09 EA11 EB13 EB27                       EB29 EB42 EC75 EC76 EC79                       ED01 ED05 EE02 EE03 FA03                 2C057 AF24 AF25 AF26 AF39 AL36                       AM15 AM28 CA01 CA05                 5C051 AA02 CA04 DA02 DB02 DE05                 5C074 AA08 BB16 DD06 DD15 DD16                       DD24 DD27 EE11 FF15 GG09

Claims (25)

[Claims] 1. In a recording apparatus for recording a color image on a recording medium using a recording head having a plurality of recording elements arranged therein, the recording medium is driven by driving the plurality of recording elements of the recording head according to image data. A plurality of complementary means for complementing the recording head driving means for recording an image on the recording medium and complementary recording means for complementing the recording head drive means, and the complementary recording means for selectively using the plurality of complementary means according to the recording medium. A recording device comprising: a control unit that controls a control operation. 2. The first complementary means performs complementary recording on a recording position corresponding to a recording element that does not perform a recording operation with a color different from a recording color of the recording element that does not perform the recording operation. The recording device according to claim 1, further comprising: 3. The plurality of complementing means corrects image data corresponding to a recording element located in the vicinity of the recording element not performing the recording operation, based on image data corresponding to the recording element not performing the recording operation. The recording apparatus according to claim 1, further comprising a second complementing unit that complements a defect in the recorded image. 4. The first complementary means performs complementary recording on a recording position corresponding to a recording element that does not perform a recording operation with a color different from a recording color of the recording element that does not perform the recording operation. Of the recorded image by correcting the image data corresponding to the recording element located in the vicinity of the recording element that does not perform the recording operation, based on the complementary means and the image data that corresponds to the recording element that does not perform the recording operation. The recording apparatus according to claim 1, further comprising a second complementing unit that complements the defect. 5. The recording medium is of two types, first and second, and in the case of the first recording medium, the control means selectively controls only the second complementing means, 2. The recording apparatus according to claim 1, wherein at least the first complementing unit is selectively controlled in the case of the recording medium. 6. The bleeding rate of the first recording medium is 2.5 or more, and the bleeding rate of the second recording medium is less than 2.5. The recording device described. 7. The first complementing means performs recording corresponding to a plurality of different colors, and complementary recording by a color having a lightness similar to that of a recording element that does not perform a recording operation. The recording apparatus according to any one of claims 2, 4, and 5. 8. The first complementing means has a compensating means for compensating image data corresponding to a recording element that does not perform a recording operation, according to a recording color corresponding to a recording element that performs complementary recording. The recording apparatus according to claim 7, wherein complementary recording is performed based on the image data corrected by the correction unit. 9. The second complementing means, in accordance with a density represented by multi-valued image data indicating a density corresponding to a recording element that does not perform a recording operation, a density represented by image data corresponding to a neighboring recording element. The recording apparatus according to any one of claims 3 to 5, characterized in that 10. The recording element which does not perform the recording operation,
The recording apparatus according to any one of claims 1 to 9, further comprising a recording element in a state in which recording operation is impossible. 11. The ink jet head having a plurality of nozzles, wherein the ink is ejected from the nozzles by driving the recording element to perform recording. The recording device according to claim 1. 12. The recording element comprises an electrothermal converter that applies heat energy to the ink, and bubbles are generated in the ink by the heat energy to eject the ink from the nozzle. The recording device described. 13. A recording method for recording a color image on a recording medium on the basis of image data using a recording head having a plurality of recording elements arranged therein, wherein recording is not performed among the plurality of recording elements. Based on the recognition result, the step of identifying the element, the step of recognizing the recording medium, and the complementary method for complementing the defect of the recorded image due to the recording element that does not perform the recording operation are different from each other. A recording method comprising: a step of selectively controlling from the inside, and a step of complementing and recording an image to be recorded by a recording element that does not perform a recording operation by a selected complementing method. 14. The first complementing method performs complementary recording at a recording position corresponding to a recording element that does not perform a recording operation with a color different from a recording color of a recording element that does not perform the recording operation. 14. The recording method according to claim 13, further comprising: 15. The plurality of complementary methods correct the image data corresponding to a recording element located in the vicinity of the recording element that does not perform the recording operation based on the image data that corresponds to the recording element that does not perform the recording operation. 14. The recording method according to claim 13, further comprising a second complementing method for complementing a defect in the recorded image. 16. The first complementary method performs complementary recording at a recording position corresponding to a recording element that does not perform a recording operation with a color different from a recording color of a recording element that does not perform the recording operation. Of the recorded image by correcting the image data corresponding to the recording element located in the vicinity of the recording element that does not perform the recording operation, based on the complementary method and the image data that corresponds to the recording element that does not perform the recording operation. The recording method according to claim 13, further comprising a second complementing method for complementing the defect. 17. The complementary recording method according to claim 14, wherein the first complementary method performs complementary recording with a color whose brightness is similar to that of a recording color of a recording element that does not perform a recording operation. Recording method. 18. The first complementing method includes a step of correcting image data corresponding to a recording element that does not perform a recording operation in accordance with a recording color corresponding to a recording element that performs complementary recording. 18. The recording method according to claim 17, wherein complementary recording is performed based on the image data corrected by. 19. The second complementary method is a density represented by image data corresponding to a recording element in the vicinity according to a density represented by multi-valued image data indicating a density corresponding to a recording element that does not perform a recording operation. Is corrected.
Recording method described in. 20. In the case of a second recording medium, selectively using at least the first complementary method,
The recording method according to claim 16, wherein only the second complementary method is selectively used in the case of the first recording medium. 21. The bleeding rate of the first recording medium is 2.5.
The bleeding rate of the second recording medium is 2.5 or more.
The recording method according to claim 20, wherein the recording amount is less than 20. 22. A recording element which does not perform the recording operation,
20. The recording method according to claim 13, further comprising a recording element in a recording-disabled state. 23. A storage medium on which a program for realizing the recording method according to claim 13 is stored. 24. The recording apparatus according to claim 1, further comprising a measuring unit that measures a bleeding rate of the recording medium. 25. In the case of the first recording medium, the control means for controlling the ejection amount of the recording head is provided in order to perform the complementation only by the second complementing means. 25. The recording device according to any one of 24 to 24.