JPH0640046A - Ink jet recording - Google Patents

Abstract

PURPOSE:To obtain a picture of high print quality even on a recording medium which absorbs ink slowly, by a method in which recording in an area, except a boundary area, of a unit picture-area is carried out by means of recording scan and recording in the boudary area is completed by means of recording scan subsequent to that. CONSTITUTION:In a first recording scan (a), only a picture-element row with one picture-element width, which is uppermost in the direction of recording, is left, and remaining three nozzles complete the recording of their corresponding images. In the subsequent second recording scan (b), recording in the uppermost picture-row, where recording was not carried out in the first recording scan (a), is carried out in the position which is the same as in the case of the first recording scan (a), so that a first picture-area is completed. In the first picture- area in this state, ink drawing forces are acting. In the subsequent third recording scan (c), a sheet is fed the distance corresponding to the head width, and then printing is carried out in a second picture-area by means of the lower three nozzles only again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method, and more particularly, to a transparency film (Trans).
The present invention relates to an inkjet recording method capable of properly recording an image even on a medium having a slow absorption rate, such as a parity film (hereinafter referred to as TP)).

[0002]

2. Description of the Related Art With the widespread use of copying machines, word processors, information processing equipment such as computers, and communication equipment, an ink jet type recording head is used as one of image forming (recording) equipment of these equipment. Those that record digital images are rapidly spreading. In such a recording apparatus, in order to improve the recording speed, a recording head in which a plurality of recording elements are integrated and arranged is used in which a plurality of ink ejection ports and liquid paths are integrated. Further, in recent years, a printer having a plurality of recording heads has been widely used for color printing.

By the way, as a recording medium for such an ink jet recording apparatus, there is a special paper having a coat layer made in consideration of the coloring property and fixing property of the ink, but in recent years, it is a plain paper or TP for OHP. Demand for a wide range of media such as paper is increasing. And with this, the recording device itself,
Adaptation (improvement of image quality) to various media is required.
However, since the ink adaptability to each medium is various, if the above printing method is used for all the media,
Depending on the medium, it will have many harmful effects. Especially T
P has a particularly slow ink absorption speed among various media,
Condensation force between ink droplets that have landed but are not completely absorbed exceeds the absorption force to the coat layer on TP. Therefore, as shown in FIG. 12, when two or more such ink droplets are present at a distance where they are in contact with each other, the ink droplets are attracted to each other and combined, and one large ink is displaced from the originally landed position. The phenomenon of forming drops occurs. This is a phenomenon peculiar to a recording medium such as TP having a low ink absorption speed, and is called beading.

Such a phenomenon is not limited to one dot unit. By moving a print head with a specified print width in the main scan direction and feeding the paper in the sub scan direction after the end of the main scan, the printing state of the area printed by simultaneous scanning by the normal serial type printing method is further increased. Consider the visual field using FIG. If the ink droplets are low-density (low-duty) prints that do not touch each other, the ink droplets do not exert forces on each other, and an independent state in which the dot center is located at the center of each pixel is obtained. Can be done. However, when the ink droplets have a high density (high duty) such that they are in contact with each other, the ink droplets try to condense with the ink droplets in the surroundings where they are in contact with each other. Therefore, a series of ink droplets located at the ends are attracted to the center of the printhead scanning width by a fairly strong condensing force, and at these true landing points, they are much thinner than the density that should actually be obtained. (FIG. 13A).

After the first scan recorded as described above, the second scan is similarly performed on the region which is in contact with and continues to this region. Even in this area, the condensing force between the ink droplets printed at the same time works, and the ink droplets at the end are attracted to the center of the second scanning width by the same phenomenon as in the first scan described above, and the density at the end is reduced. It becomes low (FIG. 13B).

When such scanning is continued, the end portions with reduced density are always adjacent to each other between the recording areas of the first scanning, the second scanning, and the plurality of subsequent scannings. become. Then, it becomes white stripes between the widths of the respective recording areas, impairs the uniformity of the entire image, and is significantly deteriorated (FIG. 13C).

In the above description, the head recording scan is performed only once for each print area width to complete the image. However, in the following patents, the same image area is recorded a plurality of times. There is a technical disclosure of a method of dividing the above into a plurality of sections and reducing the above-mentioned harmful effects.

In JP-A-55-113573,
A configuration is disclosed in which each scan prints only a checkered pattern (staggered pattern, reverse zigzag pattern) alternately arranged in the vertical and horizontal directions, and the image is completed by the forward scan and the backward scan. Then, in this case, it is an object to prevent adjacent dots from being imprinted continuously so that adjacent dots are imprinted before the printed dots are dried to cause dot distortion. Therefore, the thinning-out mask is limited to a twill pattern here.

On the other hand, JP-A-58 of the same applicant as the present invention
In No. 194541, a plurality of recording element arrays are arranged in parallel and reciprocally run in a direction perpendicular to the recording element arrays to perform main scanning for dot matrix recording. A smaller number of dots than all the dots to be recorded in at least one of each row and each column are intermittently recorded, and the remaining dots in at least one of each row and each column are intermittently recorded in the return path of the main scanning. By doing so, it is disclosed that the order of overlapping of recording in the overlapping recording dots by the plurality of recording element arrays is different between the forward pass and the return pass of the main scanning. As an effect, the image deterioration is prevented mainly due to the color tone deviation (color unevenness) of the recorded image based on the overlapping recording of the color inks. In this case, since the main purpose is to prevent this color shift, there is no special limitation on the dot position printed in each scan, and in the embodiment, in addition to the checkered pattern (staggered, reverse zigzag), It describes horizontal thinning in which only alternate recording is performed and vertical thinning in which alternate recording is repeated only in the horizontal direction.

Further, as a recording medium, a recording medium that places particular importance on recording on a medium such as TP having a slow ink absorption speed has already been disclosed in US Pat. No. 4,748,453. Here, by performing complementary recording on pixels that are alternately positioned in the horizontal and vertical directions in the same recording area by the first and second (or more) divided recording scans, on a medium such as TP. In addition to preventing beading of ink,
When a color image is formed, the effect of being able to prevent color banding (color unevenness) by reversing the ink ejection order of the mixed color pixels between the first scan and the second scan (reciprocal recording) is described. In this case, the main purpose is to prevent beading between pixels, so
It is characterized that the pixels printed by one scanning are alternated in the horizontal and vertical directions (not adjacent to each other).

The structure common to the above three patents is to complete the printing of the pixel group in the same image area by a plurality of printing scans. Such a configuration is an effective means for a recording medium such as TP, which has a low ink absorption speed, because an image can be completed while gradually evaporating and absorbing each scan. In particular, if the dots are arranged in a staggered pattern in each scan, the dots printed in the same recording scan will not attract each other on the medium,
Since it is absorbed at the true pixel position over time, it is possible to prevent the beading problem peculiar to TP. Also, since a large amount of ink does not overflow into the recording area at one time,
Bleeding at the boundary of different colors is also prevented.

However, in the above-described connecting streak that occurred in each scan, these structures had no direct effect and remained unsolved.

However, according to the recording method shown in FIGS. 14 to 17 and the following two patents, these connecting lines can be improved to some extent. In addition, it is also a particularly effective method for eliminating image density due to nozzle variations of the multi-head.

In FIG. 14A, reference numeral 91 is a multi-head, and for the sake of simplicity, eight multi-nozzles (92) are now used.
It is assumed to be composed by. Reference numeral 93 is an ink droplet ejected by the multi-nozzle 92, and normally, it is ideal that ink is ejected in a uniform direction with a uniform discharge amount as shown in this figure. If such ejection is performed, dots of uniform size are landed on the paper surface as shown in FIG. 14B, and a uniform image without density unevenness is obtained as a whole. Yes (Fig. 14
(C)).

However, in reality, as described above, each nozzle has a variation, and if printing is performed in the same manner as described above, as shown in FIG. 15 (a). The sizes and directions of the ink drops ejected from the respective nozzles vary, and the ink drops land on the paper surface as shown in FIG. 15B. According to this figure, there is a white paper portion that cannot periodically satisfy the area factor 100% with respect to the main scanning direction of the head, and conversely dots are overlapped more than necessary, or as seen in the center of this figure. There are some white streaks. The collection of dots landed in such a state has the density distribution shown in FIG. 15C in the nozzle arrangement direction, and as a result, these phenomena cause the density unevenness to be seen by human eyes. Is perceived as. In order to eliminate the adverse effects on the image due to such variations in the ejection amount between nozzles and the ejection direction, the following print control method called a divided recording method has been devised.

The method will be described with reference to FIGS. According to this method, the multi-head 91 is scanned three times in order to complete the print area shown in FIGS. 14 and 15, but the area in units of 4 pixels is completed in two passes. In this case, the 8 nozzles of the multi-head are divided into a group of 4 upper nozzles and 4 lower nozzles, and 1 nozzle is 1 nozzle.
The dots printed by one scan are the prescribed image data thinned to about half according to a predetermined image data array. Then, at the time of the second scanning, the remaining half of the image data heads are embedded to complete the printing of the 4-pixel unit area. The recording method as described above is hereinafter referred to as a divided recording method. If such a divided recording method is used, even if the same recording head as that used in FIG. 13 is used, the effect on the print image peculiar to each nozzle is halved, so the printed image is shown in FIG. 13), the black streaks and white streaks as seen in FIG. 13B become less noticeable. Therefore, the uneven density is also shown in Fig. 1.
As shown in FIG. 4 (c), it is considerably relaxed as compared with the case of FIG.

When performing such recording, the first scan and the second scan
In the scan, the image data is divided in such a manner as to fill each other according to a certain array, and this image data array (thinning-out pattern) normally forms a houndstooth check for each vertical and horizontal pixel as shown in FIG. It is most common to use something like this. Therefore, in the unit printing area (here, in units of 4 pixels), the printing is completed by the first scan for printing the zigzag lattice and the second scan for printing the inverse zigzag lattice. 17 (a), (b),
(C) shows how the recording of a certain area is completed when using these zigzag and reverse zigzag patterns, respectively, using a multi-head having 8 nozzles, as in FIGS. Is. First, in the first scan, the bottom 4
The staggered pattern 〇 is recorded using the nozzle (Fig. 17).
(A)). Next, in the second scan, the paper is fed by 4 pixels (1/2 of the head length) to record the reverse zigzag pattern ◯ (FIG. 17B). Further, in the third scan, the paper is fed again by 4 pixels (1/2 of the head length), and the staggered pattern is recorded again (FIG. 17C). In this way, the paper feeding in units of 4 pixels and the recording of the staggered pattern and the reverse zigzag pattern are alternately performed in this manner to complete the recording region in units of 4 pixels for each scan.

Such a recording method has already been disclosed in JP-A-60-1.
It is disclosed in No. 07975 and USP4967203, and it is described that its effect on density unevenness and connecting lines is also effective. Regarding the former, "a means for reducing the paper feed of each main scan smaller than the width of the main scan and overlapping two adjacent main scans to form an overlapping portion,
It is characterized in that a means for arranging the print dots in the overlapping portion so as not to overlap in two main scans is provided. " According to the present case, as described above, the thinning mask may be set to "print the odd-numbered steps and the even-numbered steps alternately in every other column", but in addition, the odd-numbered steps and the second-time steps may be performed in the first main scanning. There are cases in which even-numbered stages are printed in the above scanning, or printing is performed randomly in each scanning, and the thinning mask and the paper feed width are not completely limited.

On the other hand, in the latter USP4967203, "a) in the first pass, only the upper half of the first band is printed with alternating pixel positions which are not horizontally and vertically adjacent, and b) the second pass. At a pixel that was not printed in the first pass in the first swath and in the lower half of the first swath in alternating horizontal and vertical non-adjacent pixels, and c) in the third pass. 1, print the pixels in the first swath that were not printed in the second pass,
We will make a first pass on the sash that immediately follows. " As described above, in this case, the alternating pixel array which is not adjacent in the vertical and horizontal directions is limited as the thinning mask for performing the divided recording.

As a configuration to be further added in this case,
A recording method is disclosed in which several pixels are collectively formed as a pseudo pixel (super pixel) for gradation expression and multi-color expression, and alternating thinning printing that is not adjacent in the horizontal and vertical directions in units of pseudo pixel (super pixel) is performed. ing. According to this method, "Once the system for implementing the above method is installed in either the program software or the printer software, the program can be called with the combination of color numbers specified for superpixels. This print quality is achieved without unnecessarily complicating the task of creating a computer program to produce multiple colors. "And simplifies programming for multicolored presentations. As It also states that color bleeding within a superpixel is harmless because each superpixel is intended to be perceived as a single, homogeneous color.

As described above, since printing is completed by two different types of nozzles in the same area, density unevenness in the same image area can be prevented, while end nozzles are adjacent to each other. If the split recording method is used, even half-way stitches for each matching scan are printed by the nozzles at the end of the head and the nozzles at the center of the head, so the variations in the paper feed scan that appear here can be halved. Can be done.

By the divided recording method described above, T
Even with a recording medium having a low ink absorption speed such as P, it has been attempted to obtain an image in which beading, paper feeding connecting stripes, bleeding at different color boundaries, or nozzle unevenness is prevented.

[0023]

However, in comparison with coated paper or the like, which is made in consideration of ink absorbency, various plain papers that do not take into consideration the absorbency and TP, etc., which has a small ink allowance, are Some of them have a remarkably slow absorption speed, and the above-described divisional recording method divided into two recording scans still has insufficient points. Especially for beading and paper feed splicing lines, where the absorption speed directly affects
The split recording of about 2 passes has not overcome it. The state of the connecting stripes that appear when the divided recording method is performed will be described below.

FIG. 18 illustrates division printing in which an image is completed by scanning twice in a unit image area. Here, for simplicity, a case of recording with a head having 8 nozzles is shown. First, in the first printing scan (a), printing is performed on the image area 1 in a zigzag pattern with a duty of 50%. At this time, no recording is made in the second image area. If the dots recorded here are recorded at positions adjacent to each other, these dots attract each other and cause beading or the like, as described with reference to FIG. 12 or FIG. However, since the dots are arranged so that they are not adjacent to each other,
These remain in place from the true pixel position. However, in this drawing, since the absorption speed of the recording medium is slow, these ink droplets are not completely absorbed on the medium and are arranged as droplets.

In the next second recording scan (b), the first image area is recorded in the pixels not recorded in the first recording scan. At the same time, with respect to the second image area, recording is performed on pixels at positions not adjacent to each other as illustrated. At this time,
The pixels recorded between the second image areas maintain their respective positions without attracting each other, as in the case of the first recording scan. However, in the first image area, since the medium absorption rate is slow, the first image area still remains as droplets on the medium.
There is an ink drop recorded by the recording scan. Therefore, the ink droplets printed by the second printing scan this time and the ink droplets are adjacent to each other, attract each other, and try to aggregate toward the center of the first image area. The condensing force of the first image area as described above extends to the pixel row that is closest to the first image area in the second image area. At the moment when this scanning is performed and the first image area is completed, these pixels are in a relationship of being adjacent to the end pixels of the first image area, and due to the strong cohesive force of the completed first image area, It is drawn in the direction. Therefore, in the one row closest to the first image area side of the second image area, dots do not exist in the true pixel row,
This portion becomes a white stripe with a low density.

Next, the third recording scan will be described. Similar to the second printing scan, this scanning also completes the second image area and prints pixels that are not adjacent to each other in the third image area.
Then, as in the case of the second print scan, the ink condensing force is generated in the second image area, and the ink in the area and the ink at the end of the third image area are drawn toward the center of the second image area. (FIG.18 (c)). At this time, the end pixel row on the side of the first image area in the second image area is adjacent to not only the pixels in the second image area, but also the unabsorbed pixel rows in the first image area. ing. Therefore, both the force toward the center of the second image region and the force toward the center of the first image region act on this edge pixel row. However, the ink in the first image area has been printed from the second previous print scan, while the ink in the second image area has been completed for the first time in this scan. Therefore, since the absolute amount of ink droplets on the medium which has not been completely absorbed is larger in the second recording area, these inquiries are strongly directed toward the second image area and are attracted toward this direction. . Therefore, there will be a state in which a connecting white line is generated between the completed first image area and second image area.

The pulling of the end pixels due to the ink condensing force is certainly weakened as the number of divisions in the division recording method increases. However, as long as the divided recording is performed, the difference in the degree of printing completion between the image areas during printing appears more or less. Then, at the moment when the areas where the printing completion degree is high reach the duty where the dots are adjacent to each other, the end pixels of the adjacent areas where the printing completion degree is low are attracted, which causes a white stripe. Therefore, increasing the number of divisions cannot itself be a fundamental solution to the white streak. Not only that, but if the number of divisions increases, the number of printing scans of the unit area also increases, which causes a new problem of increasing the printing time cost.

As described above, a satisfactory high-quality image has not yet been obtained on a medium such as TP having a slow ink absorption rate.

The present invention has been made in view of the above points,
An object of the invention is to provide an ink jet recording method capable of obtaining an image of image quality or the like even on a recording medium having a low ink absorption speed.

[0030]

According to the present invention, a recording head in which a plurality of ink ejection elements are arranged scans in a direction different from the ink ejection element arrangement direction and has a predetermined width in a direction different from the scanning. In an ink jet recording method in which a print image is completed on a recording medium by relatively moving the recording head and the recording medium, recording of a unit image area is completed by a plurality of recording scans of the recording head. At the same time, an area other than a boundary area with respect to another unit image area of the unit image area is completed by the preceding recording scan, and the boundary area is completed by another recording scan subsequent thereto. .

Further, according to the present invention, a recording head having a plurality of ink ejection elements arranged scans in a direction different from the arrangement direction of the ink ejection elements, and the recording is relatively performed by a predetermined width in a direction different from the scanning. In an ink jet recording method in which a print image is completed on a recording material by moving a head and a recording medium, the recording area of the recording head is divided into a plurality of recording areas, and the same image area on the recording medium is obtained. The image is sequentially completed by performing a plurality of print scans by the plurality of print areas with respect to each other, and at least in the last print scan for each image area, a boundary with the already completed image area is displayed. The print ratio for the pixel groups in the lined-up image area is 100%
In addition, the print ratio is lower than the print ratio for the pixels of the entire image area.

According to the present invention, an area other than the boundary area between the unit image areas and another unit area is completed by the preceding recording scan, and then the boundary area is completed to be recorded. Prevents the occurrence of joining stripes.

Further, by printing a large number of pixels located in the boundary area in the last printing scan for the unit image area, it is possible to prevent the occurrence of connecting stripes between printing scans.

[0034]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a schematic structure of an ink jet recording apparatus to which the present invention can be applied. In this figure, reference numeral 701 is an ink cartridge. These are 4
It is composed of an ink tank filled with each color ink, black (K), cyan (C), magenta (M), and yellow (Y), and a multi-head 702 corresponding to each color. FIG. 2 shows the state of the multi-nozzles arranged in this multi-head from the z direction.
Reference numeral 01 is a multi-nozzle arranged on the multi-head 702.

Although the multi-nozzles 801 are arranged in parallel along the Y-axis in this figure, they may have some inclination on the XY plane of the figure, for example. In this case, while the head moves in the traveling direction X, each nozzle performs printing while shifting the timing.

Returning to FIG. 1 again. A paper feed roller 703 rotates in the direction of the arrow in the figure while holding the print paper P together with the auxiliary roller of 704, and feeds the print paper P in the Y direction at any time. Reference numeral 705 denotes a paper feed roller, which feeds printing paper, and also feeds paper 703 and auxiliary roller 7.
Similar to 04, it also plays a role of suppressing the printing paper P. Reference numeral 706 is a carriage that supports four ink cartridges and moves them with printing. The carriage 706 stands by at the home position h at the position shown by the dotted line in the figure when printing is not performed or when the recovery work of the multi-head is performed.

In the present embodiment, the recording head of each ink jet cartridge ejects ink droplets by causing the ink to change its state using thermal energy.

Here, the four mounted on the carriage 706.
The individual inkjet cartridges are arranged so that the black ink, the cyan ink, the magenta ink, and the yellow ink are superposed in this order when the carriage moves forward. Therefore, when the carriage moves backward, the inks are superposed in the reverse order of the forward movement. The intermediate color can be realized by appropriately superimposing ink dots of C, M, and Y colors. That is, red is M
And Y, blue is C and M, and green is Cy and Y.

In general, black can be realized by superimposing three colors of Cy, M, and Y. However, black coloring at this time is poor, and it is difficult to superimpose them with high precision, and thus framing of chromatic colors occurs. Only black is separately ejected because the ink ejection density per unit time becomes too high.

FIG. 3 is a block diagram showing a control section of the ink jet recording apparatus shown in FIG. In the figure, 1201 is C
It is a control unit mainly composed of PU, ROM, RAM and the like, and controls each unit of the device according to a program stored in the ROM. A driver 1202 drives a carriage motor 1205 for moving (main scanning) the carriage 706 in the x direction based on a signal from the control unit 1201. A reference numeral 1203 indicates a paper feed roller 705 and a paper sheet based on a signal from the control unit 1201. A transport motor 120 for driving the feed roller 703 to transport (sub-scan) the recording material in the y direction.
The driver 1204 drives the multi-heads 1207 to 1 for each color based on the print data from the control unit 1201.
A driver for driving 210 (corresponding to 702 in FIG. 1), 1
Reference numeral 211 is an operation display unit for inputting various keys and various displays, and 1212 is a host device for supplying print data to the control unit 1201.

Before the start of printing, the carriage 706 at the position shown in the figure (home position) moves forward in the x direction when the print start command arrives, and moves to n on the multi-head 702.
Printing is performed on the paper surface by the multi-nozzles 801.
When the printing of the data is completed up to the edge of the paper and the reversal position is reached, the carriage starts returning to the home position,
Print the data again. The sheet feeding roller 703 rotates in the arrow direction from the end of the first printing due to the forward movement of the carriage to the start of the second printing due to the backward movement of the carriage. Feed paper in the specified direction. In this way, by repeating the printing by the multi-head and the paper feeding (sub scanning) according to the scanning (main scanning) of the carriage, the data printing on one paper surface is completed.

A specific example of the recording method performed by the ink jet recording apparatus having the above-mentioned structure will be further described.

(First Embodiment) A first embodiment will be described below.
FIG. 4 shows an example of recording with a 4-nozzle head in this embodiment. Here, 1 between the two image areas
The process of recording these across the boundary area of the pixel width will be described with respect to the attraction force. The present embodiment represents a basic specific example of the present invention, and division printing due to nozzle variation is not particularly performed here. According to FIG. 4, in the first printing scan, only the pixel row of one pixel width located at the uppermost position in the printing direction is left, and printing of each image is completed by the other three nozzles (FIG. 4).
(A)). Then, in the next second printing scan, the uppermost pixel row not printed in the first printing scan is printed at the same print head position as the first printing scan to complete the first image area (FIG. 4 (b)). In the first image area in this state, the ink pulling force in the image area as described above acts as illustrated. In the next third recording scan, after the paper is fed by the width of the head, only the lower three nozzles print again on the second image area. In the second image area, the same ink attracting force as in the first image area during the second recording scan occurs. At this time, since the first image area and the second image area are completed independently by separating the boundary area for one pixel, the ink pulling forces do not affect each other (FIG. 4).
(C)). The last fourth printing scan is performed at the same head position as the third printing scan, and printing is performed in the one pixel width between the already completed first image area and second image area. Both image areas have already been fixed to a certain extent, and the ink attraction forces of both inks are almost equally stable, so that the boundary pixels to be recorded can be stabilized at the landing position. Therefore, unlike the boundary shown in FIG. 3, the ink droplet at the end is not attracted to one image area.

In the above description, the pixel area forming the boundary is fixed to one pixel width, but the size of this pixel width is not limited. For example, when the same recording as that described above is performed with the 5-nozzle head shown in FIG. 5, even if the boundary pixels have a width of 2 pixels as shown in the figure, substantially the same effect can be obtained.

In FIG. 5, a head consisting of 5 nozzles has a width of 3 nozzles and a width of 2 with the upper 2 pixel width area as a boundary area.
Recording has been completed by alternately recording areas of the nozzle width. Thus, if the pixel width of the boundary area is within a certain width, a good image can be obtained. However, in order to express the effect of the present invention, when the boundary portion of the second image area is recorded,
The ink pulling force acting from both sides must be higher than the internal condensing force and should be as uniform as possible. Therefore, the second image area other than the boundary portion must have an ink attraction force of a wide area on the side of the first image area that has already been recorded and an ink attraction force that can oppose the ink condensation force in the boundary area. Therefore, it is considered necessary to have a pixel width larger than at least the boundary area.

As described above, in the present embodiment, the boundary portion of each image area is independently subjected to the print scan after the print scan of the other areas, so that the print medium such as TP having a slow ink absorption speed is obtained. It is possible to prevent the joining streak.

(Second Embodiment) A second embodiment will be described below.
FIG. 6 shows a printing state when recording is performed by a head having 16 nozzles in this embodiment. In this embodiment, as one unit for simultaneously recording two consecutive dots in the horizontal direction,
A staggered thinning mask is used. Hitting these two dots at the same time helps to counteract the ink condensation force in the paper feed direction by intentionally creating the ink condensation force of each other in a direction different from the joint portion. Furthermore, it can be confirmed that even with a general halftone pattern as shown in FIG. 8, this mask is always equally divided into two scans as compared with the staggered mask. FIG. 8 shows the print state in each scan when the conventional staggered zigzag mask pattern is used for the print data by the binarization method called the Bayer type in the dither method, and the mask pattern in this embodiment. It shows the printing state in each scan when used. In the case of divided recording, it is a condition for obtaining the effect that the data can be equally divided in each recording scan. Further, particularly in a recording medium such as TP having a low absorption speed, the beading state greatly varies depending on the number of dots printed in each scan. Therefore,
If there is a large difference in the number of dots between the two print scans as in the conventional staggered mask, regions with different beading states are repeated for each image region, which may cause unevenness in the paper feed width. Therefore, in this embodiment, the mask is intentionally used.

By the way, USP49, which has already been shown in the conventional example, has a structure similar to such a group of plural dots.
67203 is given. Also in this case, among the pixels arranged on the paper, several pixels (m ×
It is disclosed that n) is defined as one group (super pixel), a plurality of groups which are alternately arranged and are not adjacent to each other are recorded in the first scan, and the remaining groups are recorded in the second scan. However, this matter is limited to multi-color image images or multi-gradation image images, and explained using the equal arrangement method for each color, and to express the gradations and color tones determined in each group as accurately as possible. It is listed as one of the goals. On the other hand, the configuration of the present embodiment is nothing but means for simply determining the printing order, because the two pixels in the dot group have no relation to each other on the image.

Returning to FIG. 6 again. In this embodiment, out of all the nozzles arranged in the head, only every fourth nozzle from the head in the paper feed direction prints as a head group in a scan different from the others. These two scans are always continuous, and the print scan of the head group is performed after the print scans of the other nozzle groups. No paper feed scan is inserted between these two scans, and the paper feed scan is performed once every two print scans. The effect produced by such a configuration will be described with reference to FIG.

FIG. 7 is a partial view of FIG. 6, particularly the joint portion. By comparing with FIG. 18 of the conventional example, the effect of the present embodiment on the joint line is shown.
(A) shows a printing state after the second printing scan is completed, and at this stage, printing of half of the entire first image area has already been completed. After feeding the paper, in the next third recording scan,
The nozzle at the position corresponding to the joint portion of the second recording area having a low degree of completion is not recorded (b). Therefore, even if a strong ink pulling force is generated toward the center of the first recording area, this force has no effect on the ink drop in the second image area as in the conventional example. The next fourth recording scan is performed at the same head position as the third recording scan. Only for this scanning, half of the pixel rows at the boundary are printed (c). At this time, since the ink liquid that has been ejected during the third recording scan in the first image area has already fixed to some extent,
The ink pulling force toward the center of the first image area is the third
It is much weaker than during recording scan. Therefore, the ink liquid recorded on the boundary portion by this scanning can be fixed with almost no deviation from the true landing position. The next fifth print scan is performed again after the paper feed scan, and the nozzles at the boundary also do not print at this time (d). By this printing scan, the areas on both sides of the boundary are completely printed, and the conditions on both sides for the several ink dots located at the boundary are also substantially stable. In the next sixth recording scan, the paper feed scan is not performed again,
The boundary pixel row of the last remaining second image area is completed (e). Since the state of the ink that has already landed on both sides of this pixel row is almost the same, the ink pulling force is also
Almost equally balanced, this border pixel row can be stably fixed at that recorded position. As described above, the basic idea of the present invention and the present embodiment is to complete the recording completion degree on both sides (two image areas) when completing the boundary portion between two image areas having different recording completion timings. The goal is to complete the recording at the end, after making them even in a high state, or as much as possible when they are fixed. In the present embodiment, the number of printing scans is basically larger than that in FIG. 18, so that the effect of increasing the time taken for printing is also included. However, it has already been confirmed that even if the simple divided recording is performed four times or eight times, which is the same as in the present embodiment, the same effect on the joint line as in the present embodiment cannot be obtained.

The idea and effect of such a connecting streak has already been confirmed by the present inventors. The description will be given below.

FIG. 9 shows four types of division recording methods for completing the same image area by four recording scans.
An example of the 4-pass divided recording method will be described later in detail as a fourth example. Here, a comparative study for clarifying the idea of the present invention will be briefly described. A head having 16 nozzles is equally divided into four print areas, and in each print area, printing is always performed using a fixed mask shown on the left side. The state of the recorded image according to each mask is shown on the right side of each scan. Here, the pixels filled in black represent pixels printed in each printing scan, and the gray pixels represent pixels printed in the previous scan. According to this, in (a), after the recording of the boundary portion of each image area corresponding to the joint portion is completed by the first scan and the second scan, the inside thereof is recorded by the third and fourth scans. In (h), with respect to the paper feeding direction, the boundary portion of the trailing edge portion is completed by the first and second scanning, and the leading edge portion is completed by the third and fourth scanning, respectively. On the contrary, in (c),
The boundary portion of the front end portion is first completed in the first and second scans, and the rear end portion is completed later in the third and fourth scans. In the final (d), by the second scan, the entire area is completed in a staggered manner, then in the third scan, the areas other than the boundary portion are completed first, and in the final fourth scan, the boundaries of both ends are completed. The division has completed recording. According to the actual recording using the above four types of masks, (b) and (d) were almost equal to each other, whereas (a) and (c) were significantly deteriorated at the joint line. confirmed.

From the above results, the following can be confirmed / verified. In other words, "at the boundary of the two image areas,
It is preferable that the boundary pixel row on the side of the area with low printing completion be completed by the last recording scan of the image area. " To further scrutinize, "The recording of the boundary portion of the image area where a difference in the ink amount (recording completion degree) occurs during printing is completed when the recording of the image areas contacting both sides is completed, and the same completion degree (100%) is reached. It is better to carry out the recording scan of. ” In (c), the boundary pixels of the image area on the side of high completion are completed first, but in this scanning, the recording of the image area of low completion adjacent to this is not yet completed. Therefore, since it is necessary to further print on this area by scanning after printing the boundary portion, it can be understood that a good image cannot be obtained by the printing method of (c).

Incidentally, in the present embodiment (FIG. 6), it has been explained that in addition to the leading nozzle in the paper feeding direction, every other four nozzles perform printing scanning at the same timing. For example, the nozzle drive timing is set to 4 every 4 nozzles.
The blocks are classified into two blocks, and the nozzles in each block are assumed to be controlled by the same drive.
With the driving method having such a configuration, the present embodiment can be realized by switching only the driving control of one block including the head nozzle to the other, without performing fine driving control for each nozzle. However, such a configuration may be adopted as long as it is possible to realize a drive in which only the head nozzle is different from the others in the paper feeding direction at all times. In this case, since the pixel row at the boundary can be completely independent from the others, the attracting force with other ink droplets to be recorded at the same time is completely cut off, and a high-quality image can be expected.

As described above, when performing divided recording printing, this is the same after dividing several nozzles including the head nozzle in the paper feed direction from other nozzles and completing the recording scan of the other nozzles. The print ratio of other nozzles is 0 in the image area
By performing printing by scanning, it is possible to obtain a high-quality image without density unevenness due to nozzle variation, beading, bleeding between different-color boundaries, and joint streaks in paper feed.

(Third Embodiment) Next, a third embodiment will be described. This embodiment is also a two-pass divided recording method, but unlike the first embodiment, the paper feed scanning is always performed between each recording scanning. Further, the nozzles arranged in the head are equally divided into two recording areas, and the same thinning mask is always used for each area. FIG. 10 shows the recording state of this embodiment. The head consisting of 16 nozzles on the left side of the drawing is divided into two areas as shown in the drawing. The mask shown on the right side corresponds to each nozzle, and each nozzle prints according to this mask in every scan. The image recording state in each recording scan is as shown in the right figure, and the pixels filled in black are
It indicates that printing is performed at each printing scan, and that gray pixels have already been printed in the previous scanning.

According to this, in the boundary pixel rows on both sides sandwiching the paper feed connecting portion indicated by the dotted line, the 4-pixel width area on the higher completion side (first image area) is already formed by the second recording scan. While the recording is completed, the 4-pixel width area on the lower completion side (second image area) is the last 3rd scan and the print ratio is 3 /
The record is completed in 4. In the second image area, the first printing is performed at the print ratio of 1/2 of the entire area in the second printing scan, but at this time, in the 4 pixel row which is in contact with the boundary with the first image area, the entire printing is performed. Only 1/4 is recorded. On the other hand, in the third printing scan corresponding to the second scanning of this area, half the pixels of the entire area are printed, but
In the 4-pixel column in contact with the image area, the printing ratio is 3/4 of the total.

According to the present embodiment, the division ratio of each pixel row is not equal in the nozzle main scanning direction. Therefore, it is possible that the nozzle variation is less likely to be eliminated as compared with the normal divided recording method as in the first embodiment. However, since the recording is performed by another nozzle at a ratio of 1/4, the effect of the divided recording method is not lost at all. On the contrary, considering that it is better that the two areas are independent when the degree of perfection of the adjacent image areas is different, it is more important than the fourth scanning of the first embodiment. Since the number of dots in the boundary having the width of 4 pixels in the case of 2 scans is smaller, it is possible to expect a good image regarding the connection stripes.

(Fourth Embodiment) Further, a recording method which is a development of the above embodiment will be shown in a third embodiment. This embodiment also shows an image forming state in FIG. 11 as in the above embodiment. In the present embodiment, the head print scan is performed three times for the unit image area, and the head divides a series of nozzles used for printing into three print areas. As in the second embodiment, a fixed thinning mask is always used for each recording area,
The paper is fed by 1/3 head width for each recording scan. In this embodiment, almost the same effect as in the second embodiment can be obtained, but since the mask of this embodiment has a period of 3 pixels in the main scanning direction, it usually has a period of a multiple of 2. It is difficult to synchronize with the input binarized image data, and even if the image data of any duty is 2
It is possible to perform divided recording with different types of nozzles. Also,
Compared to the third embodiment, the unit image area is completed by three print scans at a print ratio of 1/3, and therefore better results can be expected even in the case of a boundary between different colors on the TP.

(Fifth Embodiment) Further, as a fourth embodiment, 4
An example of the path division recording method will be shown. The 4-pass divided recording method using FIG. 9 has already been described in the second embodiment, and among these, (b),
And (d) are good. In both (b) and (d), the boundary portion of the second image area on the side of the first image area is printed in the fifth scan, thereby completing all the printing scans of the area. Both have a print ratio of 1/4 to the second recording area.
The print ratio at the boundary with the first image area is 1/2. The difference between them appears in the first to third scans.
In (b), a pixel row for which printing has been completed in the second scan,
Pixel columns that have not been recorded at all are arranged alternately. In (d), the entire image area is printed in a staggered pattern at the end of the second scan, and then the second scan is performed in the third scan except for the portion other than the connecting portion.
The pixel width is completed first. In (b), the boundary with the first image area is printed in the last two scans, whereas
In (d), recording of half the pixels in the boundary has already been completed in the first scan. According to the theory explained so far, it seems that it is better to complete the recording of the boundary portion at the end as much as possible (b). But,
In (d), since a line having a width of 2 pixels has already been formed in the area in the third scan, a large ink line is formed in advance in the same direction as the connecting line due to the ink condensing force. By increasing the frequency of the horizontal stripes, the effect of making the connecting stripes inconspicuous can be obtained.

In the present embodiment, an ink jet recording apparatus for recording by forming flying droplets by utilizing thermal energy among the ink jet recording methods has been described as an example. Regarding the configuration and the principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal which gives a rapid temperature rise over each boiling corresponding to the recorded information to the electric heat exchanger, the electric heat exchanger is caused to generate thermal energy, and This is effective because film boiling is caused on the heat acting surface, and as a result, bubbles can be formed in the liquid (ink) that correspond one-to-one to this drive signal. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with particularly 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. still,
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 electric heat exchanger (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. A configuration using US Pat. No. 4,558,333 or US Pat. No. 4,459,600, which discloses a configuration in which a heat action is arranged in a bending region, may be used.

In addition, Japanese Patent Application Laid-Open No. 59-123670 discloses a structure in which a common slit is used as a discharge portion of an electric heat exchanger for a plurality of electric heat exchangers, and a pressure wave of thermal energy is absorbed. A configuration based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a configuration in which an opening corresponds to a discharge portion, may be adopted.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium which can be recorded by the recording apparatus, a combination of a plurality of recording heads as disclosed in the above-mentioned specification is used. Either a structure satisfying the length or a structure as one recording head integrally formed may be used.

In addition, a replaceable chip-type recording head that can be electrically connected to the apparatus body and can be supplied with ink from the apparatus body by being attached to the apparatus body,
Alternatively, the present invention is also effective when a cartridge type recording head in which the recording head itself is integrally provided with an ink tank is used.

Further, it is preferable to add recovery means, preliminary auxiliary means, etc. to the recording head because the effects of the present invention can be further stabilized. Specifically, capping means for the recording head,
Cleaning means, pressurization or suction means, electric heat exchanger, or a heating element separately from this, preheating means by a combination of these, predischarge mode for performing discharge other than recording, stable recording is also possible. Effective to do.

In this embodiment described above, the ink is described as a liquid, but it is an ink that solidifies at room temperature or lower and that softens at room temperature, or is a liquid, or the above-mentioned ink jet. In the method, the temperature of the ink itself is adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. Any material that is in liquid form may be used.

In addition, the temperature rise due to the thermal energy is positively prevented by using it as the energy for the state change of the ink from the solid state to the liquid state, or the ink is solidified in the standing state for the purpose of preventing the evaporation of the ink. Depending on the type of ink used, the ink liquefies by applying heat energy in accordance with the recording signal and is ejected as a liquid ink, or when it reaches the recording medium, it begins to solidify. It is also possible to use an ink that has the property of being liquefied only by heat energy. In such a case, the ink is retained as a liquid or solid in the recesses or through holes of the porous sheet as described in JP-A-54-56847 or JP-A-60-71260. In such a state, the electric heat exchanger may be opposed to the heat exchanger. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

Further, as a form of the recording apparatus according to the present invention, the recording apparatus according to the present invention may be integrally or separately provided as an image output terminal of the information processing equipment such as the word processor or the computer, or may be combined with a reader or the like. It may be a copying machine or a facsimile machine having a transmission / reception function.

Further, the present invention is not limited to the ink jet method using heat energy, but the present invention can be applied to the ink jet method using a piezo element or the like.

[0073]

As described above, according to the first aspect of the present invention, recording is completed in the boundary area of the unit image area after the other areas.

According to the second aspect of the invention, a large number of pixels located at the boundary are printed in the last printing scan in which there is no difference in the degree of completion of printing. As a result, even on a recording medium such as TP having a low ink absorbing power, the connecting stripes at the boundary between both image regions due to the ink condensing force caused by the difference in the degree of recording completion can be prevented, and a high quality image can be obtained. .

[Brief description of drawings]

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

FIG. 2 is a diagram showing a recording head.

3 is a block diagram showing a control unit of the inkjet recording apparatus shown in FIG.

FIG. 4 is a diagram illustrating a recording state in the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a recording state in the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a recording state in the second embodiment.

FIG. 7 is a diagram showing a state where ink is attracted in the second embodiment.

FIG. 8 is a diagram for explaining the effect of the thinning mask in the first embodiment.

FIG. 9 is a diagram illustrating a recording state in a fifth embodiment.

FIG. 10 is a diagram illustrating a recording state in the third embodiment.

FIG. 11 is a diagram illustrating a recording state in the fourth embodiment.

FIG. 12 is a diagram illustrating the principle of beading.

FIG. 13 is a diagram for explaining the principle of occurrence of connecting stripes.

FIG. 14 is a diagram showing an ideal printing state of an inkjet printer.

FIG. 15 is a diagram showing a printing state of an inkjet printer having uneven density.

FIG. 16 is a diagram illustrating divided recording.

FIG. 17 is a diagram showing a printing state by division recording.

FIG. 18 is a diagram for explaining the principle of the generation of joint stripes during 2-pass divided recording.

[Explanation of symbols]

 701 Ink Cartridge 702 Multi Head 703 Paper Feed Roller 704 Auxiliary Roller 705 Paper Feed Roller 706 Carriage 801 Multi Nozzle 1201 Control Unit 1205 Carriage Motor 1206 Carrying Motor 1207-1210 Multi Head 1212 Host Device

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[Procedure amendment]

[Submission date] June 25, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigetasu Nagoshi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hitoshi Sugimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Masaya Uetsuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Fumihiro Goto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Within

Claims (5)

[Claims] 1. A recording head in which a plurality of ink ejection elements are arranged scans in a direction different from the ink ejection element arrangement direction, and the recording head and a recording medium are relatively moved in a direction different from the scanning by a predetermined width. In an ink jet recording method for completing a print image on a recording medium by moving and, the recording of the unit image area is completed by a plurality of recording scans of the recording head, and the other of the unit image areas is recorded. 2. An ink jet recording method, characterized in that an area other than the boundary area with respect to the unit image area is completed by the preceding recording scan, and the boundary area is completed by another recording scan subsequent thereto. 2. The ink jet recording method according to claim 1, wherein the width of the boundary area is not more than half the width of the unit image area. 3. The ink jet recording method according to claim 1, wherein the recording head ejects an ink droplet from an ejection port by causing a state change in the ink by using thermal energy. 4. A recording head in which a plurality of ink ejection elements are arranged scans in a direction different from the direction in which the ink ejection elements are arranged, and recording is performed relative to the recording head in a direction different from the scanning by a predetermined width. In an inkjet recording method for completing a print image on a recording medium by moving the medium, the recording area of the recording head is divided into a plurality of recording areas, and the same image area on the recording medium is The images are sequentially completed by performing a plurality of recording scans by the plurality of recording regions, and at least the last recording scan for each image region, the images aligned on the boundary with the already completed image region. The print ratio for the pixel group in the area is less than 100%, and is higher than the print ratio for the pixels in the entire image area. Characteristic inkjet recording method. 5. The ink jet recording method according to claim 4, wherein the recording head ejects an ink droplet from an ejection port by causing a state change in the ink by using thermal energy.