JP3184570B2 - Ink jet recording method and ink jet recording apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method and an ink jet recording apparatus for recording an image by discharging ink onto a recording material.

[0002]

2. Description of the Related Art With the spread of information processing devices such as copying machines, word processors, computers, and communication devices, a recording head of an ink jet system is used as one of image forming (recording) devices of those devices. Those that perform digital image recording are rapidly spreading. In such a printing apparatus, in order to improve the printing speed, a printing head in which a plurality of printing elements are integrated and arranged (hereinafter, referred to as a multi-head in this section) is one in which a plurality of ink ejection ports and liquid paths are integrated. In general, a plurality of the above-mentioned multi-heads are used for color.

[0003] In such an ink jet type color printer, different from a monochrome printer which prints only characters, printing a color image image requires various elements such as coloring, gradation and uniformity. Becomes Especially with regard to uniformity, slight variations in the nozzle unit caused by differences in the multi-head production process,
When printing, it affects the amount of ink ejected from each nozzle and the direction of the ejecting direction, and ultimately causes deterioration in image quality as density unevenness of a printed image.

A specific example will be described with reference to FIGS. 9 and 10. FIG. In FIG. 9A, reference numeral 91 denotes a multi-head,
It is assumed that it is constituted by eight multi-nozzles 92. Numeral 93 denotes an ink droplet ejected by the multi-nozzle 92. Normally, it is ideal that the ink is ejected in a uniform direction with a uniform ejection amount as shown in FIG. If such ejection is performed, dots of a uniform size are landed on the paper surface as shown in FIG. 9B, and a uniform image without density unevenness is obtained as a whole. (FIG. 9C).

However, actually, as described above, each nozzle has a variation, and if printing is performed in the same manner as described above, as shown in FIG. The size and direction of the ink drops ejected from the respective nozzles vary, and land on the paper as shown in FIG. 10B. According to this diagram, there are blank portions that do not periodically satisfy the area factor of 100% in the main scanning direction of the head, or dots overlap more than necessary, or as seen in the center of the diagram. White streaks have occurred. The collection of dots landed in such a state has a density distribution as shown in FIG. 10C in the nozzle arrangement direction, and as a result, these phenomena usually show the density unevenness as seen by human eyes. Is sensed as

Therefore, the following method has been devised as a countermeasure against the density unevenness. 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. 9 and 10, but an area of half a pixel unit is completed in two passes. In this case, the multi-head 8 nozzles
The dots that are divided into upper four nozzles and lower four nozzles and are printed by one nozzle in one scan are obtained by thinning out prescribed image data by about half in accordance with a predetermined image data arrangement. Then, dots are embedded in the remaining half of the image data at the time of the second scan, and printing in a 4-pixel unit area is completed. The above recording method is hereinafter referred to as a divided recording method.

When such a recording method is used, the influence on the print image specific to each nozzle is reduced by half even if the same multi-head as that shown in FIG. 10 is used. As shown in FIG. 10B, black streaks and white streaks as shown in FIG. 10B become less noticeable. Therefore, as shown in FIG. 11C, the density unevenness is considerably reduced as compared with the case of FIG.

In performing such recording, the first scan and the second scan
In the scan, the image data is divided in such a manner that the image data is complemented with each other in accordance with a certain arrangement. Usually, this image data arrangement (thinning-out pattern) is such that a vertical and horizontal one pixel is formed in a staggered pattern as shown in FIG. It is most common to use a suitable one.

Therefore, in the unit print area (here, in units of 4 pixels), the first scan for printing the staggered grid and the
The printing is completed by the second scan for printing the inverted staggered grid. FIGS. 12A, 12B, and 12C show how recording in a certain area is completed when the staggered and inverted staggered patterns are used, respectively.
As in the case of 1, the explanation is made using a multi-head having eight nozzles.

First, in the first scan, a staggered pattern is formed using the lower four nozzles.

[0011]

[Outside 1] Is recorded (FIG. 12A). Next, in the second scan, the paper is fed by 4 pixels (1/2 of the head length), and the inverted zigzag pattern 記録 is recorded (FIG. 12B). In the third scan, the paper is fed again by four pixels (1/2 of the head length) again, and the staggered pattern is recorded again (FIG. 12).
(C)). In this manner, the paper feed in units of four pixels and the recording of the zigzag and inverted zigzag patterns are alternately performed in this manner.
The recording area in pixel units is completed for each scan.

As described above, by completing printing in the same area using two different types of nozzles, it is possible to obtain a high quality image without density unevenness.

[0013]

However, even when such divisional recording is performed, the above density unevenness is not eliminated at all depending on the duty, and new density unevenness is confirmed especially in an intermediate color or a mixed color portion. Or be done. The phenomenon will be described below.

Normally, the image data to be recorded in a certain area received by the printer is already regularly arranged. On the printer side, these data are stored in the buffer in a certain amount, and a new mask (image arrangement pattern) of staggered or inverted staggered as described above is applied.
The printing of the pixel is performed only when both are turned on.

FIGS. 13 to 15 illustrate this state. In FIG. 13, reference numeral 131 denotes already-arranged data stored in the buffer, 132 denotes a staggered pattern mask indicating pixels that can be printed in the first pass, and 133 denotes pixels that can be printed in the second pass. Reverse staggered pattern mask,
Reference numerals 134 and 135 represent pixels to be printed in the first pass and the second pass, respectively.

In FIG. 13, the buffer has an area 2
When printing at 5%, data that has already been arranged is stocked. In general, this data is arranged in a state where print data varies as much as possible in order to maintain a uniform density in a specified fixed area. What kind of image arrangement these are depends on what area gradation method is performed at the time of image processing before being transferred to the printer.

FIG. 131 shows an example of a certain image arrangement for 25% data. If such data is printed with masks of 132 and 133, respectively, the first and second passes are performed. Are distributed and recorded in a state where the data is just equally divided as shown in 134 and 135.

However, as shown in FIG.
When 0% of data arrives, the data 141 and the staggered pattern mask (14
It can easily be imagined that either 2) or the inverted zigzag pattern mask (143) will be in an aligned state completely coincident.

When this occurs, the first pass (14)
In 4), printing of all the image data is completed, and in the second pass (145), no printing is performed at all. That is, all the print data (141) is printed by the same nozzle. Therefore, the influence of the nozzle variation is directly reflected on the density unevenness, and the original purpose of the above-described divided recording method cannot be achieved.

FIG. 15 shows a print state when arrayed image data with a duty higher than that of FIGS. 13 and 14 is input. In this case, too, the first pass and the second pass are shown. It can be seen that there is a considerable difference in the number of prints. As described above, there is a problem that the density unevenness which has been improved at the high duty and the low duty near 100% appears again at the data near 50%.

As shown in FIG. 12, the head always prints either staggered or inverted staggered patterns using all nozzles. Therefore, in the printing area of FIG. 12, the upper half of the four pixels is landed in a staggered pattern first, and then the inverted staggered pattern is landed. After the inverted staggered pattern was landed,
A staggered pattern is landed. In other words, when this is combined with the above problem, a print area in which many dots land in the first pass and then a small number of dots land in the second pass,
An area where printing is scarcely performed in the first pass and a large amount of dots are printed in the second pass appears alternately by half the width of the head. From such a phenomenon, there are also the following adverse effects particularly in the color mixing portion of the ink jet system.

The disadvantages will be schematically described in the case where four multi-heads of eight nozzles are used for each color similarly to the above. In this case, the four colors are cyan (Cy), magenta (M), yellow (Y), and black (Bk). Here, a case will be described in which intermediate color (yellow-green) printing is performed as print image data, as shown in FIG. 19A, with a print duty of Cy 62.5% and Y 100% superimposed. When the intermediate color shown in FIG. 19A is printed using a staggered grid mask, Cy and Y are printed on all the masks permitted by the staggered grid with a 50% duty in the first pass (FIG. 19B )). In the second pass, printing for the remaining duty, that is, Cy 50% and Y 12.5% is performed. When these (B) and (C) are viewed by recording head (by color), FIGS. 19D and 19E and FIG.
(F) and (G) indicate that each head is discharging.

FIG. 20 schematically shows the ejection positions of the Cy recording head and the Y recording head at the first scanning in the L / 2 paper feed printing method and the resulting dot formation state on the recording medium. The vertical stripe pattern indicates that Cy and Y are discharging to the same pixel, and the oblique line pattern indicates that only Y is discharging. In the first scan, each print head uses the four nozzles of the print area (1) to print in a staggered manner, and as a result, dots on which Cy and Y overlap are formed in a staggered manner on the print medium. Here, the paper is fed in the width of L / 2, and the dots recorded in the first scan are recorded in the recording area (2).
Move to.

FIG. 21 schematically shows the ejection position in the second scan and the resulting dot formation state on the recording medium. At this time, printing is performed in reverse zigzag in all the recording areas (1) and (2). Then, as a result, the recording area (2)
Then, the printing is completed by overlapping the dots printed in a zigzag pattern in the first scan. Here, the sheet is fed in the width of L / 2, the recording area (2) moves out of the recording area, and the recording area (1) moves toward the recording area (2).

It should be noted here that when another dot is superimposed on a previously recorded dot, the dot struck later than the previously recorded dot has a greater depth in the overlapping portion. That it tends to sink in the vertical direction.
FIG. 23 is a cross-sectional view schematically showing this. this is,
Dyes such as dyes in the ejected ink are physically and chemically bonded to the recording medium.However, at this time, the bonding between the recording medium and the dyes is finite, and the bonding strength depends on the type of dye. As long as there is no difference, the ink dye that has been ejected earlier and the recording medium are prioritized, so much remains on the surface of the recording medium, and the ink dye that is later struck is less likely to be combined on the surface of the recording medium, It is thought that it sinks in the direction and dyes.

Therefore, also in FIG. 21, the dots recorded in the second scan are represented so as to overlap below the dots recorded in the first scan.

FIG. 22 schematically shows the ejection position in the third scan and the resulting dot formation state on the recording medium.

At this time, printing is performed in a zigzag direction opposite to the second scanning in all the recording areas (1) and (2). Then, as a result, in the printing area (2), the printing is completed by overlapping the dots printed in reverse zigzag at the second scan.

However, at this time, although the same amount of ink is applied to the portion of the recording region (2) and the portion outside the recording region where printing has been completed in the second scan before the recording region (2), the color tone is not improved. Different color unevenness has occurred.

This is because a portion outside the recording area is printed in a zigzag pattern beforehand, so that there are many portions where Cy and Y are ejected to the same pixel on the surface of the recording medium. It is probable that the portion (2) became yellow-green, which has a relatively strong yellowish color, because many portions recorded only with Y existed on the surface of the recording medium.

The above-described two harmful items have been used to correct nozzle variations.
Conventional multi-pass printing has still only provided insufficient image quality with respect to density unevenness.

The present invention has been made in view of the above points,
It is an object of the present invention to provide an ink jet recording method and an ink jet recording apparatus capable of recording a high-quality image by eliminating density unevenness and the like.

[0033]

Means and Action for Solving the Problems That is, the present invention provides:
A main scan is performed using a recording head having a plurality of ink ejection ports, and after the main scan is completed, a sub-scan is performed in a sub-scan direction different from the main scan direction, and the main scan is formed according to a predetermined area gradation method. In an ink jet recording method for recording an image on a recording material by discharging ink from the discharge ports in accordance with image data, the plurality of ink discharge ports are divided into a plurality of blocks, and a recording material is formed using different blocks. The upper predetermined area is main-scanned a plurality of times, and an image thinned out according to a different mask pattern in each main scan is recorded in the predetermined area, and the dot arrangement of the different thinning pattern is different from the mask pattern. It is characterized in that it is asynchronous with the dot arrangement of an image according to the predetermined area gradation method having the same recording duty.

Also, the present invention provides a first recording head having a plurality of ink ejection ports for ejecting a first color ink and a plurality of ink ejection ports for ejecting a second color ink. A main scan is performed using the second recording head provided, and after the main scan is completed, a sub-scan is performed in a sub-scan direction different from the main scan direction, and the main scan is performed in accordance with image data formed according to a predetermined area gradation method. Inkjet recording in which a color image is recorded on a recording material by ejecting a first color ink and a second color ink from an ink ejection port of the first recording head and an ink ejection port of the second recording head. In the method, a plurality of ink ejection ports of the first recording head and a plurality of ink ejection ports of the second recording head are divided into a plurality of blocks, and a predetermined area on a recording material is mainly used a plurality of times using different blocks. Scan A color image thinned out according to a different mask pattern in each main scan is recorded in the predetermined area, and the dot arrangement of the different mask pattern has the same print duty as the mask pattern. It is asynchronous with the dot arrangement of the image according to the area gradation method.

According to the present invention, the main scanning is performed by using a recording head having a plurality of ink ejection ports, and after the main scanning is completed, the sub scanning is performed in a sub scanning direction different from the main scanning direction. In an ink jet recording apparatus that records an image on a recording material by discharging ink from the discharge ports according to image data formed according to the area gradation method of
Scanning means for main scanning a predetermined area on a recording material a plurality of times using different blocks among a plurality of ink ejection ports of the recording head divided into a plurality of blocks, and different mask patterns in each main scanning Driving means for driving the print head based on print data obtained by masking the image data, and in each main scan, an image thinned out according to the mask pattern is formed. The dot array of the different mask pattern recorded in a predetermined area is asynchronous with the dot array of an image according to the predetermined area gradation method having the same print duty as the mask pattern. .

The present invention also provides a first recording head having a plurality of ink ejection ports for ejecting a first color ink and a plurality of ink ejection ports for ejecting a second color ink. Main scanning is performed using the second recording head provided, and after the main scanning is completed, sub-scanning is performed in a sub-scanning direction different from the main scanning direction, and a first color formed according to a predetermined area gradation method in the main scanning. By discharging the first color ink and the second color ink from the ink discharge port of the first recording head and the ink discharge port of the second recording head according to the image data and the second color image data, In an ink jet recording apparatus for recording a color image on a recording material, a difference between a plurality of ink ejection ports of the first recording head and a plurality of ink ejection ports of the second recording head, each divided into a plurality of blocks. Ru block And a main scanning unit for performing main scanning of a predetermined area on the recording material a plurality of times, and masking the first color image data and the second color image data according to different mask patterns in each main scanning. And driving means for driving the first print head and the second print head based on the first print data and the second print data obtained by performing A color image thinned out according to the predetermined area is recorded in the predetermined area, and the dot arrangement of the different mask pattern is the same as that of the image according to the predetermined area gradation method having the same recording duty as the mask pattern. It is characterized by being asynchronous with the dot array.

Thus, a thinned-out image is recorded by using different blocks of the recording head in a plurality of main scans, and the difference in the amount of ink applied in each main scan is reduced. Record high quality images.

[0038]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 7A is a perspective view showing a schematic configuration of an ink jet recording apparatus to which the present invention can be applied.

In this figure, reference numeral 701 denotes an ink cartridge. These are composed of ink tanks packed with four color inks, black, cyan, magenta, and yellow, respectively, and a multi-head 702. FIG. 7B shows the state of the multi-nozzles arranged on the multi-head from the z direction.
Reference numeral 1 denotes a multi-nozzle arranged on the multi-head 702. In the present embodiment, the multi-head 702 has a thermal energy generating element for each nozzle, and the thermal energy generated from the thermal energy generating element generates bubbles in the ink to cause a state change to cause a change in each ink ejection port. This is to discharge more ink. FIG. 7A again
Return to Reference numeral 703 denotes a paper feed roller which rotates in the direction of the arrow in the figure while holding down the print paper 707 together with the auxiliary roller 704, and feeds the print paper 707 in the y direction as needed. 70
Reference numeral 5 denotes a paper feed roller for feeding print paper and
Similarly to 03 and 704, it also plays the role of suppressing the printing paper 707. A carriage 706 supports the four ink cartridges and moves them together with printing. The carriage 706 stands by at a home position h at a position indicated by a dotted line in the drawing when printing is not being performed or when performing a multi-head recovery operation or the like.

Here, the 4 mounted on the carriage 706
The individual inkjet cartridges are arranged so that the inks are superposed in the order of black ink, cyan ink, magenta ink, and yellow ink. The color intermediate color can be realized by appropriately overlapping the ink dots of Cy, M, and Y. That is, red can be realized by overlapping M and Y, blue can be realized by overlapping Cy and M, and green can be realized by overlapping Cy and Y.

In general, black can be realized by superimposing the three colors of Cy, M, and Y. However, if the color of black is poor at this time, it is difficult to superimpose with high accuracy, so that chromatic color fringing occurs, and Because the density of the ink is too high, only black is separately ejected.

FIG. 8 is a block diagram showing a control section of the ink jet recording apparatus shown in FIG. In the figure, reference numeral 201 denotes a control unit mainly including a CPU, a ROM, a RAM, and the like, which controls each unit of the apparatus according to a program stored in the ROM. A driver 202 drives a carriage motor 205 for moving (main scanning) the carriage 706 in the x direction based on a signal from the control unit 201.
03 is a sheet feed roller 7 based on a signal from the control unit 201.
A driver 204 drives the transport motor 206 for transporting the recording material in the y-direction (sub-scanning) by driving the paper feed roller 05 and the paper feed roller 703. The driver 204 controls the multi-heads 207 to 210 for each color based on print data from the control unit 201. A driving driver 211 is an operation display unit for performing various key inputs and various displays, and a reference numeral 212 is a host device for supplying print data to the control unit 201.

Before the start of printing, the carriage 706 at the position (home position) shown in FIG.
The multi-nozzles 801 perform printing for each recording area divided on the paper surface. When printing of data to the end of the sheet is completed, the carriage returns to the original home position, and performs printing in the x direction again. After the first printing is completed and before the second printing starts, the paper feed roller 703 is used.
Is rotated in the direction of the arrow to feed the paper in the y direction by the width of the divided recording area. In this manner, data printing on one sheet is completed by repeating the printing by the multi-head and the paper feeding (sub-scanning) for each one scan (main scan) of the carriage.

First, an example of a thinning pattern at the time of two-pass printing of the ink jet recording apparatus will be described with reference to FIGS. In the present embodiment, a so-called Bayer type based on a dither method, which is one of the most common methods, is used as the area gradation method of an already binarized image data array. Here, the description will be made in a 4 × 4 matrix. FIG. 2 shows how the first pass and the second pass are printed for each duty when such arrangement data is stored in the buffer and the conventional staggered and inverted staggered patterns are applied. It is what expressed. Where 2
Reference numeral 1 denotes a first-pass mask (staggered-thin pattern), and reference numeral 22 denotes a second-pass mask (inverse staggered-thin pattern). When the array data of various duties on the left pass through the masks 21 and 22, what kind of printing is performed in the first pass and the second pass is shown on the right.

FIG. 1 best illustrates the invention.
The thinning-out printing is performed by the thinning-out patterns (101, 102) unique to the present embodiment. according to this,
In FIG. 2, printing is completed in the first pass up to a printing duty of 50%, and printing of the second pass is performed only after the printing duty exceeds 50%. On the other hand, in the present embodiment, as shown in FIGS. 11 and 12, the same dither method is used by using masks of complementary thinning patterns arranged in a zigzag or inverted zigzag pattern with dots continuous in the horizontal direction as one unit. Even in the arrangement pattern, the number of print dots is always equally divided in the first pass and the second pass from the low duty to the high duty. The masks may be complementary thinning patterns arranged in a zigzag or inverted zigzag pattern with dots that are continuous in the vertical direction as one unit.

The method of solving the density unevenness due to nozzle variation shown in the above-mentioned conventional example is effective only when the nozzles to be printed in the first pass and the second pass are changed, and substantially the same number of dots are landed by different nozzles. Was something.

The color unevenness peculiar to the color mixing shown in the above-mentioned conventional example is also caused by such a difference in the number of dots in the first pass and the second pass. Therefore, the mask of the present embodiment in which the number of print dots is almost equally divided in the first pass and the second pass is shown in FIG.
It is clear that the masks 21 and 22 are more effective at all duties.

As described above, in the arrangement pattern of the most common Bayer type of the dither method shown here, the arrangement state is not synchronized with the arrangement state at the time of area gray scale having the same duty as the mask (thinning pattern). By performing the thinning-out printing with the above mask such as 12 at the same position using different nozzles, it is possible to obtain a high-quality image without density unevenness over the entire duty.

Second Embodiment Next, as a second embodiment, a case where the dither pattern used in the first embodiment is printed in four passes will be described. In this method, printing in the same area is completed four times by using four types of nozzles to complete printing. Therefore, the paper feed is also performed for all multi-nozzles n
Is performed in units of 1/4 pixel, and four types of masks of the thinning pattern that allow printing of 25% are required. Now, it is assumed that there is a mask with a 25% duty as a certain thinning pattern. The head and paper feed drive at that time will be described with reference to FIG.

In this figure, the vertical axis represents the arrangement of n multi-nozzles and the address on the paper corresponding thereto, and the horizontal axis represents the printing time of each pass. c1 to c4 denote heads of four colors of black (Bk), cyan (Cy), magenta (M), and yellow (Y). Indicates whether printing has been performed or which printing has been performed in the past (in parentheses). The paper moves in the Y direction by n / 4 pixels (L / 4) sequentially from the first pass to the second pass,....

According to this, for example, d1 of width L / 4 on the paper surface
In the area of, the first pass, the second pass, the third pass,
Bk, Cy, M, Y are masked by different parts of the head from the pass, that is, different nozzles,
, And printing is completed in this order. In the next print area d2, in the order of.
,..., Etc., the order of the print masks differs depending on the area.

Therefore, if the same number of prints are performed from one pass to four passes, variations in the nozzles are most reduced, and an image without color unevenness is obtained.

FIGS. 4 to 6 show some thinning patterns that can be considered as four passes, and the state of print data at various duties when the above-described binarized data is passed. In these, while FIG. 4 has a considerable offset, in FIG. 5, the offset is considerably reduced.
In FIG. 6, it can be seen that the 4 × 4 matrix has the least deviation. Therefore, as mentioned earlier,
For correcting the density unevenness of each nozzle, the method of FIG. 6 having the most variation is the most effective. However, in FIG. 6, there is a high possibility that adjacent dots are printed at the same time, and there may be a case where bleeding is particularly bad in an image. In such a case, although there is a slight offset, it is possible to print at landing points that are not adjacent in one pass.
If the above method is favorable, this method may be used.

As described above, for the image data array of the Bayer type, which is the most common pattern of the dither method shown in this embodiment, the print duty 2
By providing four types of masks with a print duty of 25% that are not synchronized at 5% as shown in FIGS. 4 and 5, it is possible to obtain a high-quality image free from density unevenness or color unevenness described in the above conventional example. It is.

Third Embodiment Next, a third embodiment will be described with reference to FIGS. The image data array patterns used here are the first and second
Unlike the embodiment, even the same dither method is particularly called a fatning type. The pattern of each duty by this has the form as shown in FIG. 16 and FIG. 17, and is quite different from the Bayer type of the above embodiment. Considering that data arranged in such a manner is printed in four passes in the same manner as in the second embodiment, as shown in FIG. 16, the best mask in the second embodiment is used. It can be seen that the use of 61, 62, 63, and 64 also allows print dots to be equally divided into four passes. However, in this case, in the second embodiment, even in the masks 41, 42, 43, and 44 where the print dots are considerably offset, the dots are evenly distributed from one pass to four passes (FIG. 17).

Therefore, in the area gradation pattern of the dither method in this embodiment, it is considered that the number of print dots performed in one pass is almost the same regardless of whether the mask shown in FIG. 16 or FIG. 17 is used.

However, when considering simultaneous printing of four color inks or printing on bleeding paper such as plain paper, the dots printed by one ejection should be located as far away as possible. It is preferred to be located. Therefore, taking this into consideration, the printing method using the masks 61 to 64 as shown in FIG.
It is considered preferable to use the masks No. to No. 44.

When a mask such as 41 to 44 is used, a 4 × 4 mask has been provided so far. However, as shown in FIG. 18, a 2 × 2 mask of 181 to 184 is used. Equivalent to four arranged vertically and horizontally.

Therefore, in this case, since a mask having a size of 1/4 may be provided on the printer side, the cost of the printer itself or the printing time can be reduced.

In this embodiment, two types of masks are assumed to correspond to the two area dither methods, the Bayer type described in the second embodiment and the fatting type described in the present embodiment. Patterns 61-64 and 181-
184 are provided. These mask patterns are selected by the user using keys on the operation unit. The user corresponds to the binarized patterns sent to the printer, and can select these to always obtain a good image.

As described above, the area gray scale patterns of the Bayer type and the fatting type, which are the most common patterns of the dither method shown in this embodiment, are described below.
Each mask pattern 61 with a print duty of 25% that is not synchronized with the dot arrangement at a print duty of 25%
By providing ６４64 and 181１〜184, it is possible to obtain a high-quality image without density unevenness or color unevenness described in the above conventional example.

It should be noted that the present invention provides an excellent effect particularly in an ink jet recording apparatus in which a flying droplet is formed by utilizing thermal energy and recording is performed among ink jet recording methods.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method 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, the liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding each boiling point, to an electrothermal transducer arranged corresponding to the sheet or liquid path in which This is effective because heat energy is generated in the electrothermal transducer, causing film boiling on the heat-acting surface of the recording head, and as a result, air bubbles in the liquid (ink) corresponding one-to-one to this drive signal can be formed. It is. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, A configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600 which discloses a configuration in which the heat acting portion is arranged in a bending region may be adopted.

In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, or absorbs pressure waves of thermal energy. A configuration based on JP-A-59-138461, which discloses a configuration in which an opening corresponds to a discharge unit, may be used.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above-mentioned specification. This may be either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally.

In addition, the print head is exchangeable with a print head of the chip type, which can be electrically connected to the main body of the apparatus or supplied with ink from the main body of the apparatus, or is integrated with the print head itself. The present invention is also effective when a cartridge type recording head provided with an ink tank is used.

It is preferable to add recovery means for the recording head, preliminary auxiliary means, and the like, since the effects of the present invention can be further stabilized. Specific examples include capping means for the recording head, cleaning means, pressurizing or suction means, an electrothermal transducer or a preheating means using a heating element or a combination thereof separately from the recording head, It is also effective to perform the preliminary ejection mode in which the ejection is performed in order to perform stable printing.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be a single recording head or a combination of plural recording heads. Alternatively, the device may be provided with at least one of full colors by color mixture.

In the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or below and which softens at room temperature, or which is liquid, In general, in the ink jet method, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. What is necessary is just to be liquid.

In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from the solid state to the liquid state, or solidified in a standing state for the purpose of preventing evaporation of the ink. Either ink may be used, or in any case, the ink may be liquefied by application of heat energy according to the recording signal and ejected as a liquid ink, or may already start to solidify when reaching the recording medium. Alternatively, the ink may be liquefied for the first time by thermal energy. In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held as a liquid or solid in a concave portion or through hole of a porous sheet, It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition to the above, the recording device according to the present invention may be combined with a reader or the like in addition to the above-described one provided as an image output terminal of an information processing device such as a word processor or a computer. A copier, or a facsimile machine having a transmission / reception function may be used.

[0074]

As described above, a mask which is not synchronized with the image data array by the area gradation method is provided, and based on the mask, divisional printing is performed by using different portions on the print head in several scans. Thus, a high-quality image without density unevenness can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a thinning pattern and a printing pattern in each pass according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a print pattern using a staggered or inverted staggered thinning pattern.

FIG. 3 is a diagram illustrating a head and a print area during four-pass printing according to a second embodiment of the present invention.

FIG. 4 is a diagram of a division recording method used for explaining a second embodiment.

FIG. 5 is a diagram showing a thinning pattern and a printing pattern in each pass in the second embodiment.

6 is a diagram showing a thinning pattern shown in FIG. 5 and a printing pattern in each pass.

FIG. 7 is a diagram showing a thinning pattern and a printing pattern in each pass in a third embodiment of the present invention.

8 is a diagram showing a thinning pattern shown in FIG. 7 and a printing pattern in each pass.

FIG. 9 is a diagram illustrating a mask according to a third embodiment.

FIG. 10 is a diagram showing a schematic configuration of an ink jet recording apparatus to which the present invention can be applied.

11 is a block diagram illustrating a control unit of the inkjet recording apparatus illustrated in FIG.

FIG. 12 is a diagram illustrating an ideal printing state of the ink jet printer.

FIG. 13 is a diagram illustrating a printing state of an inkjet printer having uneven density.

FIG. 14 is a diagram illustrating divided printing.

FIG. 15 is a diagram illustrating divided printing using a staggered and inverted staggered pattern.

FIG. 16 is a diagram showing 25% data and print dots in conventional divided printing.

FIG. 17 is a diagram showing 50% data and print dots in conventional divided printing.

FIG. 18 is a diagram showing 63% data and print dots at the time of conventional divided printing.

FIG. 19 is a view for explaining divisional recording when printing of an intermediate color is performed.

FIG. 20 is a diagram illustrating a dot formation state in a first pass.

FIG. 21 is a diagram illustrating a dot formation state in a second pass.

FIG. 22 is a diagram illustrating a dot formation state in the third pass.

FIG. 23 is a diagram schematically showing a state in which dots are overlapped.

[Explanation of symbols]

 701 Ink cartridge 702 Multi-nozzle 703 Paper feed roller 705 Paper feed roller 706 Carriage

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiichiro Takahashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shigetasu Nagoshi 3-30-2 Shimomaruko, Ota-ku, Tokyo (56) References JP-A-62-104758 (JP, A) JP-A-63-209842 (JP, A) JP-A-59-68245 (JP, A) JP-A-1-1633071 (JP , A) JP-A-3-61045 (JP, A) JP-A-3-146351 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/21 B41J 2/07 B41J 2/205 B41J 2/485

Claims (14)

(57) [Claims] 1. A main scan is performed using a recording head having a plurality of ink discharge ports, and after the main scan is completed, a sub-scan is performed in a sub-scan direction different from the main scan direction. In an ink jet recording method for recording an image on a recording material by discharging ink from the discharge ports according to image data formed according to a method, the plurality of ink discharge ports are divided into a plurality of blocks, and different blocks are provided. The main scanning of the predetermined area on the recording material a plurality of times using the, and while the image thinned out according to a different mask pattern in each main scanning is recorded in the predetermined area, the dot arrangement of the different thinning pattern is An ink jet recording method which is asynchronous with a dot arrangement of an image according to the predetermined area gradation method having the same recording duty as the mask pattern. 2. The ink jet recording method according to claim 1, wherein the area gradation method is a dither method. 3. The ink jet recording method according to claim 1, wherein the recording head discharges the ink from the discharge port by causing a state change of the ink by thermal energy. 4. A first recording head having a plurality of ink ejection ports for ejecting a first color ink, and a second recording head having a plurality of ink ejection ports for ejecting a second color ink. A main scan is performed using a recording head, and after the main scan is completed, a sub-scan is performed in a sub-scan direction different from the main scan direction. A first color ink and a second color ink from the ink ejection port of the recording head and the ink ejection port of the second recording head;
An ink jet recording method for recording a color image on a recording material by discharging ink of the following colors: a plurality of ink discharge ports of the first recording head and the second
The plurality of ink ejection ports of the recording head are divided into a plurality of blocks, a predetermined area on the recording material is main-scanned a plurality of times using different blocks, and thinned out according to a different mask pattern in each main scan. While recording a color image in the predetermined area, the dot arrangement of the different mask pattern,
An ink jet recording method, which is asynchronous with a dot arrangement of an image according to the predetermined area gradation method having the same recording duty as the mask pattern. 5. The ink jet recording method according to claim 4, wherein the first recording head and the second recording head are arranged at a predetermined interval in the main scanning direction. 6. The ink jet recording method according to claim 4, wherein the area gradation method is a dither method. 7. The ink jet recording method according to claim 4, wherein the recording head causes a state change of the ink by thermal energy to discharge the ink from the discharge port. 8. A main scan is performed using a recording head having a plurality of ink ejection ports, and after the main scan is completed, a sub-scan is performed in a sub-scan direction different from the main scan direction. In an ink jet recording apparatus that records an image on a recording material by discharging ink from the discharge ports according to image data formed according to a method, a plurality of ink discharge ports of the print head divided into a plurality of blocks are provided. Scanning means for main scanning a predetermined area on the recording material a plurality of times using different blocks, and in each main scanning, the recording data obtained by masking the image data according to a different mask pattern. And a driving unit for driving the recording head based on the image data. In each main scan, an image thinned according to the mask pattern is recorded in the predetermined area. , The dot arrangement of different Ru mask pattern, an ink jet recording apparatus wherein the a dot arrangement asynchronous image corresponding to the mask pattern predetermined area gradation method having the same print duty and. 9. The ink jet recording apparatus according to claim 8, wherein the area gradation method is a dither method. 10. The ink jet recording apparatus according to claim 8, wherein the recording head discharges the ink from the discharge port by causing a state change of the ink by thermal energy. 11. A first recording head having a plurality of ink ejection ports for ejecting a first color ink, and a second recording head having a plurality of ink ejection ports for ejecting a second color ink. A main scan is performed using a recording head, and after the main scan is completed, a sub-scan is performed in a sub-scan direction different from the main scan direction. The first color ink and the second color ink are ejected from the ink ejection port of the first recording head and the ink ejection port of the second recording head in accordance with the second color image data, so that the ink is ejected onto the recording material. In an ink jet recording apparatus for recording a color image, a different block among a plurality of ink ejection ports of the first recording head and a plurality of ink ejection ports of the second recording head, each divided into a plurality of blocks, is used. hand Main scanning means for main scanning a predetermined area on a recording material a plurality of times; and masking the first color image data and the second color image data in each main scan according to different mask patterns. Driving means for driving the first print head and the second print head based on the first print data and the second print data to be obtained, and thinning out in accordance with a different mask pattern in each main scan. While recording the color image on the predetermined area,
The ink jet recording apparatus according to claim 1, wherein the dot arrangement of the different mask patterns is asynchronous with the dot arrangement of an image according to the predetermined area gradation method having the same recording duty as the mask pattern. 12. The ink jet recording apparatus according to claim 11, wherein the first recording head and the second recording head are arranged at a predetermined interval in the main scanning direction. 13. The ink jet recording apparatus according to claim 11, wherein the area gradation method is a dither method. 14. The ink jet recording apparatus according to claim 11, wherein the recording head discharges the ink from the discharge port by causing a state change of the ink by thermal energy.