JP2002011862A - Ink-jet recording device and image data correcting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record a high quality image by reducing generation of black stripes as density irregularity at a joint part between recording areas formed in each scanning of a recording head in an ink-jet recording device. SOLUTION: The number of dots as data to be ejected per each 8 pixels in the vicinity of the boundary of each area of the scanning operation of immediately before and the scanning operation for processing is counted for each image data to be supplied to a recording head of each color ink. Based on the total count value, the number of dots to be thinned is provided so that dots are thinned for the number of dots calculated from the data for 5 pixels in the process. Thereby, the ejected ink amount at the joint parts in the vicinity of the boundaries can be reduced so that black stripes can be reduced.

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 apparatus and an image data correcting method, and more particularly to a method for reducing density unevenness occurring at or near a boundary of a recording area formed in response to scanning of a recording head. And a method for correcting image data.

[0002] The present invention can be applied to all apparatuses that perform recording by an ink-jet method using a recording medium such as paper, cloth, nonwoven fabric, OHP paper, etc. Specifically, such apparatuses include printers, copiers, and the like. Examples include office equipment such as facsimile machines and mass production equipment such as printing machines.

[0003]

2. Description of the Related Art Conventionally, paper, cloth, plastic sheet, O
2. Description of the Related Art An ink jet recording apparatus capable of performing recording on a recording medium such as an HP sheet is often used as an information output apparatus in an information processing apparatus because it can perform high-density and high-speed recording. For example, it is used as a recording unit of a copying machine, a facsimile, an electronic typewriter, a word processor, a workstation, or the like, or as a printer for outputting information processed by a personal computer or a host computer connected via a network. Further, it is also used as a handy or portable printer provided in an optical disk device, a video device, and the like, and has been commercialized.

In this case, the ink jet recording apparatus, of course, has a configuration corresponding to the functions and usage forms specific to the used apparatuses, but the ink jet recording apparatus generally includes a recording head or a recording head and an ink tank. And a transport mechanism for transporting recording paper as a recording medium, and a control circuit for controlling these. Then, the recording head mounted on the carriage is caused to scan (hereinafter, also referred to as “scan”) the recording paper in a direction (hereinafter, also referred to as “main scanning direction”) orthogonal to the transport direction (hereinafter, also referred to as “sub-scanning direction”). During this scanning, the recording paper is conveyed according to the recording width in the scanning of the recording head, thereby sequentially recording on the recording paper.

According to this method, recording is performed by discharging ink from a nozzle of a recording head onto recording paper in accordance with a recording signal based on image data. Therefore, the running cost is low and the recording cost is reduced. Noise is also widely used as a relatively small recording method. In addition, by using a print head having a large number of nozzles arranged in the sub-scanning direction, the print width of a print area that can be printed by one scan can be increased, thereby achieving high-speed printing. More recently, an apparatus has been provided which is capable of performing full-color printing by mounting such a printing head for inks of three to four colors. Such an ink jet recording apparatus generally includes a recording head and an ink tank respectively corresponding to three primary colors of yellow (Y), magenta (M), and cyan (C) or four colors including black (Bk). It is provided.

An ink jet recording apparatus having such a configuration requires a certain degree of accuracy in ejecting ink from nozzles in a recording head or a paper feed amount performed in accordance with scanning of the recording head. That is, variations in the discharge amount and discharge direction of the print head appear as density unevenness in the print image, and variations in the paper feed amount cause black stripes at the boundary between print regions for each scan and at a joint portion near the boundary. And uneven density such as white stripes may occur.

[0007] It is difficult to completely eliminate these factors at the stage of manufacturing a recording head or an apparatus. Particularly, as the required image quality increases, the difficulty only increases. From this point, there has been proposed a recording method which does not completely eliminate the cause of the density unevenness, but makes the density inconspicuous even if there is some density unevenness.

Further, the number of occasions of recording on various recording media having different characteristics, such as plain paper, coated paper, and OHP paper, has increased, and a recording method suitable for each recording medium with respect to density unevenness has been required. I have. For example, in a recording medium, such as coated paper or plain paper, in which ink is absorbed relatively quickly, a connecting streak, which is one of the density unevenness, often appears as a black streak. As a particularly remarkable case, a black streak generated at a connection portion between recording regions caused by scanning of the recording head is raised. This can be explained as follows.

FIG. 1 schematically shows a cross section in the thickness direction of the recording paper in the state of ink on the recording paper when recording is performed by two scans of the recording head, and is realized by the state. It shows the optical reflection density. The ink ejected in the preceding scan is denoted by the symbol A on the paper.
And indicates the concentration due to the penetration. After the recording paper is conveyed according to the recording width, the ink discharged in the subsequent scanning penetrates as shown in B in the figure. At this time, in a portion adjacent to the permeation region A, the permeation in a state of being attracted toward the permeation region A occurs, and a portion like the region C is generated. This is a state in which the ink that has been ejected in the preceding scan and has penetrated the recording paper has increased the penetrating power to the recording paper, and as a result, the ink in the next scan is drawn by the penetrated ink in the preceding scan. It is thought that it will be in a state. Due to such a bias of ink penetration, the density of the connecting portion becomes high, and black stripes are generated. The above description relates to a method of performing printing by performing only one scan on each print area.

In order to solve the density unevenness as described above, for example, Japanese Patent Application Laid-Open No. 5-220977 discloses a method for controlling density unevenness for each raster (data) of image data corresponding to each nozzle of a print head during printing. A so-called head shading method has been proposed in which density unevenness is reduced by performing correction.

Further, the applicant of the present application has proposed that a recording head supplied to a recording head to record at least one of a plurality of connection regions which are predetermined regions adjacent to boundaries between recording regions by scanning. There has been proposed a method of calculating the total signal value and correcting the magnitude of the recording signal value for recording the connection area according to the magnitude of the total recording signal value.

[0012]

However, the above-described structure can reduce the density unevenness generated at the joint, but has a problem in mounting.

That is, when the inkjet recording apparatus is used by being connected to a host computer, including a system configured via a network, processing having a large load such as image processing such as color processing of image data to be recorded is performed by the host computer. A configuration is widely used in which a computer performs the processing and sends the image data to the recording apparatus as image data in a form that directly indicates whether or not ink is to be ejected by the recording head of the recording apparatus. Have been. On the other hand, on the recording apparatus side, for example, JP-A-8-2073
As disclosed in Japanese Patent Application Publication No. 99-99, there is a case where a special recording head moves or a recording medium is conveyed such that recording is performed by skipping a blank portion of image data in order to increase the recording speed. For this reason, when the host computer finally creates binary image data by image processing, the print head or the print head in the printing apparatus is used to determine a joint between print areas formed by scanning the print head in advance. It is necessary to consider the operation of the recording medium, and there is a problem that the processing speed is reduced by the processing. On the other hand, it is considered that the recording device corrects the joint between the recording areas. However, since the binarized image data sent from the host computer has a small amount of information relating to the density unevenness, an accurate correction amount is required. Is relatively difficult to calculate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems.
It is an object of the present invention to provide an ink jet printing apparatus and an image data correction method capable of printing a high-quality image by reducing the occurrence of a connecting streak due to printing scan.

[0015]

According to the present invention, there is provided:
A print head having a plurality of nozzles and capable of discharging ink from the plurality of nozzles is used. The image data sent from the host device directly represents whether or not to discharge ink for each nozzle of the print head. In an ink jet recording apparatus that performs recording by discharging ink on a recording medium based on image data, the recording head and the recording medium are relatively moved, and ink is discharged from the recording head in accordance with the image data. Recording control means for sequentially forming predetermined recording areas to be recorded adjacent to each other, and counting the number of data indicating that ink is to be ejected for at least one of the image data of the connecting portion in the adjacent recording areas, and The number of data for ink ejection in the image data of the connection portion is reduced accordingly. Characterized in that comprises a means.

In another embodiment, a recording head having a plurality of nozzles and capable of discharging ink from the plurality of nozzles is used, and ink is discharged from each nozzle of the recording head as image data sent from a host device. In a method of correcting image data in an ink jet recording apparatus that performs recording by ejecting ink to a recording medium based on image data in a form that directly represents whether or not the recording head and the recording medium are relatively moved, and A predetermined recording area to be recorded by ink ejection is sequentially formed by ejecting ink from the recording head in accordance with the image forming apparatus, and at the time of performing the formation, at least one of image data of a joint portion in the adjacent recording area is formed. The number of data indicating that ink is to be ejected is counted, and the connecting portion is counted according to the counted value. Corrects to reduce the number of data to the effect that ejects ink in the image data, characterized in that comprising the step.

According to the above arrangement, for example, when recording is performed on the recording medium by forming adjacent recording areas for each successive scanning by scanning of the recording head and conveyance of the recording medium, each recording area is formed. For the image data of the joint portion, which is a predetermined area near the boundary, the number of data indicating that ink is to be ejected is counted, and correction is performed to reduce the number of data indicating that ink is ejected in the image data of the joint portion in accordance with the counted value. Accordingly, it is possible to reduce the amount of ink ejected at the connection portion, and thereby it is possible to reduce density unevenness due to a difference in ink permeation occurring at a boundary between recording areas.

[0018]

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

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIGS.

<Outline of Recording Apparatus> FIG. 2 is a perspective view showing the schematic arrangement of an ink jet recording apparatus according to this embodiment.

In FIG. 2, reference numeral 1 denotes a recording sheet as a recording medium made of paper or a plastic sheet;
A plurality of sheets 1 stacked on a cassette or the like (not shown) are supplied one by one by a paper feed roller (not shown). The fed recording sheet 1 is arranged in a direction indicated by an arrow A in the figure by a first transport roller pair 3 and a second transport roller pair 4 which are arranged at a predetermined interval and are driven by respective stepping motors (not shown). Transported to

The recording heads 5 prepared for the respective inks of C, M, Y, and Bk are removably mounted on the carriage 6 for each of the recording heads. A predetermined number, for example, 256 ink ejection ports (nozzles) are arranged in the scanning direction). The ink used in each recording head 5 is similarly supplied from a corresponding ink cartridge (not shown) mounted on the carriage 6, so that ink can be ejected from each nozzle according to a recording signal. Each recording head has an electrothermal conversion element in an ink path corresponding to each nozzle, and the electrothermal conversion element generates bubbles in the ink using thermal energy generated by application of an electric pulse corresponding to a recording signal. The ink is ejected by the generation pressure of the bubbles. A part of the belt 7 is joined to the carriage 6, whereby the driving force of the carriage motor 23 is transmitted via the belt and the pulleys 8a and 8b, and the carriage 6 can be moved. On the other hand, the carriage 6 is configured to slidably engage with the guide shaft 9 and to reciprocate along the guide shaft 9. With the above-described carriage configuration, scanning for recording, in which recording is performed by ejecting ink onto the recording sheet 1 in accordance with a recording signal while the recording head 5 moves in the direction of arrow B in the drawing, becomes possible.

The recording head 5 moves to the home position as required, and performs a predetermined recovery operation by the discharge recovery device 2. For example, the cap of the recovery device 2 covers the surface of each recording head where the nozzles are provided, and forcibly discharges ink from inside the nozzles, preliminary recovery that performs suction recovery and discharge that does not involve recording from each nozzle of the recording head, and the like. Can be performed. This recovery operation makes it possible to eliminate clogging or the like caused by the thickened ink that may have occurred in each nozzle.

In the above arrangement, the recording head 5 and the conveyance of the recording sheet 1 in an amount corresponding to the width of the recording area to be recorded by the scanning are repeated, so that the recording according to the image data is recorded on the recording sheet 1. It can be carried out.

FIG. 3 is a block diagram showing the configuration of a control system in the ink jet recording apparatus.

As shown in FIG. 3, the control system of this embodiment is as follows.
For example, CPU 20a such as a microprocessor, CPU 2
ROM2 for storing the control program of Oa and various data
0b, a control system 20 having a RAM 20c for temporarily storing various data such as image data and the like, which is used as a work area of the CPU 20a, an interface 21, an operation panel 22, and each motor (a motor 23 for driving a carriage). , A motor 27 for driving the paper feed roller, a motor 25 for driving the first conveyor roller pair, a driver 27 for driving the second motor for driving the conveyor roller pair, and a print head driving driver 28. I have.

The control unit 20 receives various information (for example, character pitch, character type, etc.) from the operation panel 22 and I / O such as image data with an external device 29 which is a host device such as a personal computer via an interface 21. O
(Input and output of information). The control unit 20 outputs ON and OFF signals for driving the motors 23 to 26 via the interface 21, and outputs various control signals and recording signals for each head to the head driver 28. Then, the ink ejection according to the scanning of each recording head is controlled.

When outputting the image data, the control unit 20 determines whether or not the image data is a connection portion, as described later. The image data according to the image data from the host computer is sent to the recording head.

The composition of the ink used in this embodiment is shown below.

(Black (Bk) ink) Glycerin 7.5 parts by weight Thiodiglycol 7.5 parts by weight Urea 7.5 parts by weight IJA260 (10% aqueous solution) 10.0 parts by weight Project Fast Black 2 (5% aqueous solution) 36.5 parts by weight Isopropyl alcohol 2.0 parts by weight Ammonium sulfate 1.0 part by weight Na @ H 1.0 part by weight Acetylenol EH 1.0 part by weight Water remaining part

(Yellow (Y) ink) Glycerin 7.5 parts by weight Thiodiglycol 7.5 parts by weight Urea 7.5 parts by weight Project Fast Yellow 2 (4.3% aqueous solution) 43.48 parts by weight Daiwa Yellow 330EP 0 0.5 parts by weight Isopropyl alcohol 2.0 parts by weight Ammonium sulfate 1.0 part by weight 4N-Li @ H 1.0 part by weight Acetylenol EH 1.2 parts by weight Water balance

(Magenta (M) ink) Glycerin 7.5 parts by weight Thiodiglycol 7.5 parts by weight Urea 7.5 parts by weight Project Fast Magenta 2 (4% aqueous solution) 45.0 parts by weight Isopropyl alcohol 3.0 parts by weight Part Ammonium sulfate 1.0 part by weight 10% Li @ Ac 1.0 part by weight Acetylenol EH 1.0 part by weight Water balance

(Cyan (C) ink) 7.5 parts by weight of glycerin 7.5 parts by weight of thiodiglycol 7.5 parts by weight of urea 28.0 parts by weight of Direct Blue 199 (10% aqueous solution) 2.0 parts by weight of isopropyl alcohol Ammonium sulfate 1.0 part by weight 10% Li @ c 1.0 part by weight Acetylenol EH 1.0 part by weight Water balance

A method of correcting image data relating to the reduction of black stripes, which is performed in the above-described ink jet recording apparatus, will be specifically described below.

<Joint Correction Method> In the joint correction of the present embodiment, the image data to be printed in each scan corresponds to five nozzles corresponding to the upper five nozzles in the nozzle array of the print head.
The image data for the pixels and the image data for the three pixels corresponding to the three nozzles at the lower end in the scan immediately before the scan are used as the data for the connection portion, and the data for ejection included in this data (hereinafter simply referred to as In this process, dots are thinned out from the image data of the scan by the number obtained according to the number of dots. It should be noted that image data sent from an external device as a host device is used as it is for image data other than the connection portion.

FIG. 4 is a flowchart showing the procedure of the thinning process. FIG. 5 is a diagram schematically showing a table for determining the number of thinned dots in accordance with the number of ejection data.
FIG. 4 is a diagram for explaining a thinning process based on image data in an image data buffer.

The image data transferred from the host computer, which is an external device, is developed in the image data buffer of the RAM 20b, and the image data of the upper five nozzles in the nozzle array of the print head constituting the data of the connection portion is As shown in the data D0 in FIG. 6, similarly to the previous scan, the data is developed together with the image data of the three nozzles at the lower end of the nozzle array, and these are subjected to thinning processing. In FIG. 6, one grid corresponds to one pixel, and the grid shown in black represents data (dots) indicating ejection. In the present embodiment, the image data developed in this buffer is cyan, magenta, yellow,
A binary two-dimensional image plane is formed for each color of black.

More specifically, the image data buffer is set to be three rasters larger than the pixel area for one line for one scan, and as shown at D0 in FIG. The data of () is image data corresponding to the 254th nozzle in the immediately preceding scan, that is, the third nozzle from the lowermost end. The second raster from the top of the buffer corresponds to the 255th nozzle, and the third raster is the 256th, that is, image data corresponding to the lowermost nozzle in the nozzle array.

The fourth and subsequent rasters are the image data used in the scanning for the processing, and the fourth raster is the uppermost image in the nozzle array, that is, the image data corresponding to the first nozzle. . Similarly, the fifth raster corresponds to the second nozzle, and subsequently the sixth to eighth rasters are image data corresponding to the third to fifth nozzles. Constitute.

In FIG. 4, first, in step S41, as shown in D1 of FIG. 6, the number of dots (data indicating ejection) included in the image data of eight pixels in the first column is counted for the image data of each color. Get the sum. In the present embodiment, the count value relating to the total of the dots in the eight pixels, that is, the number of dots included in the eight pixels for four colors is 4 colors × the number of pixels, and thus is in the range of 0 to 32.

Next, in step S42, the number of dots to be thinned is determined by referring to the table shown in FIG. 5 based on the count value. The table of the present embodiment is
Although the number of thinned dots is set regardless of the ink color, it goes without saying that the contents of this table may be changed according to the ink color.

In steps S43, S44 and S45, addition of errors, thinning processing based on the added errors, and propagation of the errors generated in the processing to the next column are performed.

The rule of how to thin out the dots is to thin out the dots of the pixels close to the boundary b with respect to the image data of each color by priority, and when the same distance from the boundary b is the same between different colors, the closeness is set to 8 In consideration of the number of dots included in the pixel, it is determined which color dot is to be thinned out. Specifically, as shown at D1 in FIG. 6, the total dot count of the eight pixels for each color required for the processing is 14, and the count value 14 refers to the table to determine the number of thinned dots.
Get 5. Then, as indicated by D2 in FIG. 6, the dots are thinned out from cyan, magenta, and yellow, each of which has a dot at the pixel corresponding to the first nozzle closest to the boundary b among the thinning numbers 5.5. Next, dots corresponding to the pixels corresponding to the second and subsequent nozzles are thinned out according to the above-described thinning rule.
A total of 5 dots, 1 dot for magenta and 3 dots for yellow.

Here, the error in thinning out, that is, Δ =
0.5 is accumulated in the error buffer and added in the processing of the next column. If the amount of thinning is larger than the number of dots, the number of unsuccessful thinnings is also stored in the error buffer. As shown in FIG. 6, in the decimation process from D2 to D3 in FIG. 6, an error 0.5 relating to the processing of the preceding column is added to the decimation amount 3.6 obtained from the table by the count value 11, and 4 .1 is the thinning amount.

By repeating the above process for each column of 8 pixels, it is possible to perform the correction processing of the connection portion for one line for scanning, and further to perform the correction processing for one line for each scan. Accordingly, it is possible to reduce streak-like density unevenness that may occur at a joint portion of a print area formed for each scan in the entire image to be printed.

In the above description, the image data for counting the number of dots includes the data of the immediately preceding scan. However, it is a matter of course that the present invention is not limited to such a configuration in order to obtain the effects of the present invention. is there. That is, without considering the image data of the scan performed immediately before, the data of the connection portion in the image data related to the scan, the first to
The dots may be counted for the data of the pixel corresponding to the fifth nozzle.

The detailed procedure of the above-described thinning-out processing of this embodiment is summarized as follows.

I) The number of ejected dots in an area (row) to be thinned out is counted for each color and ranked, and the number of dots to be thinned out is obtained by referring to a table based on the total of the count values.

In the case of the example shown in FIG. 6, (yellow = 6)>
(Cyan = 5)> (Magenta = 3)> (Black = 0) count value, ranking, and the number of dots to be thinned are shown in FIG.
Is 5.5 from the table shown in FIG.

Ii) The number of ejection dots of the pixel closest to the boundary of each color is compared with the number of dots to be thinned out, and if the number of dots to be thinned is large, all the dots are thinned. On the other hand, if the number of dots to be thinned is small, thinning is performed from the color having the large number of ejected dots in accordance with the above order.

In the example shown in FIG. 6, since the ejection dots exist for cyan, magenta, and yellow in the pixel closest to the boundary, that is, the pixel corresponding to the first nozzle of each color, the number of ejection dots of the pixel closest to the boundary is calculated. = 3) <(the number of dots to be thinned out = 5.5). Therefore, all the ejection dots of these pixels are thinned out. As a result, for the cyan, magenta, and yellow, one dot from the pixel closest to the connection portion (first pixel), ie, a total of three dots, is thinned out.

Iii) The number of dots to be thinned out is reduced by the number of thinned out in the process of ii). As a result, the number of dots to be thinned is 1
If so, the above process ii) is repeated. on the other hand,
When the number of dots to be thinned becomes 1 or less, the number of dots to be thinned is added to the error buffer, and the process proceeds to the next area (row).

In the example shown in FIG. 6, when the number (3) thinned out in the processing of ii) is reduced, the number of dots to be thinned out becomes 2.5, and (the number of ejection dots of the pixel closest to the boundary = 3)> (the number of dots to be thinned out) = 2.5), so according to the ranking determined in i) above,
The dots of the second pixel of yellow and then the second pixel of cyan are thinned out. As a result, the error becomes 0.5.

As described above, dots of 2, 1, and 2 are thinned out for cyan, magenta, and yellow, respectively. Then, the final error is 0.5, and the process moves to the next column in addition to the error buffer.

(Second Embodiment) In the first embodiment, the thinning method or the thinning amount is the same for all colors. On the other hand, in the present embodiment, the thinning amount is changed according to the type or color of the ink.

As described above, the streak-like density unevenness that can occur at the joint occurs due to the manner of penetration of the ink into the recording medium. However, it is relatively difficult to make the permeability of the ink to the recording medium equal for all the inks in view of the difference in the dyes and the like of the inks, the storage stability to be satisfied as the ink, and the stability of the ejection.
On the other hand, there is also a fact that the stripe-shaped density unevenness generated at the seam of scanning depends on the total ejected ink amount of all colors. For this reason, it is difficult to perform an appropriate correction by setting a correction table for each ink and determining a thinning amount for each ink accordingly. Therefore, in the present embodiment, when counting the number of dots, weighting is performed for each ink (permeability).

The composition of the ink used in this embodiment is shown below.

(Black ink) Glycerin 7.5 parts by weight Thiodiglycol 7.5 parts by weight Urea 7.5 parts by weight IJA260 (10% aqueous solution) 10.0 parts by weight Project Fast Black 2 (5% aqueous solution) 36.5 Parts by weight Daiwa Yellow 330EP 0.3 parts by weight Direct Blue 199 (10% aqueous solution) 7.2 parts by weight Isopropyl alcohol 2.0 parts by weight Ammonium sulfate 1.0 part by weight Na @ H 1.0 part by weight Acetylenol EH 1.0 part by weight Water Rest

(Yellow ink) Glycerin 7.5 parts by weight Thiodiglycol 7.5 parts by weight Urea 7.5 parts by weight Acid Yellow 23 (5% aqueous solution) 60.0 parts by weight Daiwa Yellow 330EP 0.5 parts by weight Isopropyl alcohol 2.0 parts by weight Ammonium sulfate 1.0 part by weight 4N-Li @ H 1.0 part by weight Acetylenol EH 1.0 part by weight Water balance

(Magenta ink) Glycerin 7.5 parts by weight Thiodiglycol 7.5 parts by weight Urea 7.5 parts by weight Project Fast Magenta (4% aqueous solution) 45.0 parts by weight Isopropyl alcohol 3.0 parts by weight Ammonium sulfate 1. 0 parts by weight 10% Li @ Ac 1.0 parts by weight Acetylenol EH 1.0 parts by weight Water balance

(Cyan Ink) Glycerin 7.5 parts by weight Thiodiglycol 7.5 parts by weight Urea 7.5 parts by weight Direct Blue 199 (10% aqueous solution) 28.0 parts by weight Isopropyl alcohol 2.0 parts by weight Ammonium sulfate 1. 0 parts by weight 10% LiAc 1.0 parts by weight Acetylenol EH l. 0 parts by weight water balance

In the present embodiment, since the yellow ink has low permeability, the value of the dot count for yellow is multiplied by 0.5 as a weight. As a result, it was possible to reduce streak-like density unevenness occurring at a scanning joint portion.

(Other Embodiments) When a recording head capable of modulating the amount of ink ejected from one nozzle is used, the ink amount at the connecting portion may be corrected using this characteristic.

[0064]

As is apparent from the above description, according to the present invention, for example, recording is performed on a recording medium by forming a recording area adjacent to each scanning sequentially by scanning the recording head and transporting the recording medium. When the process is performed, the number of data indicating that ink is to be ejected is counted for the image data of the connection portion which is a predetermined region near each recording region boundary, and the ink in the image data of the connection portion is discharged in accordance with the counted value. Since the correction for reducing the number of data to be performed is performed, it is possible to reduce the amount of ink ejected at the connection portion, and thereby it is possible to reduce unevenness in density due to a difference in ink penetration at a boundary between recording areas.

As a result, high-quality printing with reduced density unevenness such as black stripes can be performed with a simple configuration without requiring any processing in the host device.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining density unevenness occurring at a joint portion of a print area for each scan of a print head.

FIG. 2 is a perspective view illustrating a schematic configuration of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a control system of the printing apparatus.

FIG. 4 is a flowchart illustrating a thinning-out process of a connecting portion according to the embodiment of the present invention.

FIG. 5 is a diagram schematically showing a table used for the thinning processing.

FIG. 6 is a diagram illustrating the thinning process in the form of image data in a buffer.

[Explanation of symbols]

 5 Recording Head 6 Carriage 20 Controller 20a CPU 20b RAM 20c ROM 21 Interface 22 Operation Panel 23 Carriage Motor 24 Feed Motor 25 First Transport Roller Drive Motor 26 Second Transport Roller Drive Motor 27 Driver 28 Driver 29 External Device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Daigoro Kanematsu 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Masao Kato 3-30-2 Shimomaruko, Ota-ku, Tokyo Non-corp. F term (reference) 2C056 EA06 EA08 EB49 EB58 EC71 EC79 FA03 FA10 2C057 AF25 AF31 AF39 AF91 AL32 AM28 AM40 AN01 CA05

Claims (8)

[Claims] 1. A printhead comprising a plurality of nozzles and capable of discharging ink from the plurality of nozzles, and determining whether or not to discharge ink for each nozzle of the printhead as image data sent from a host device. In an ink jet recording apparatus that performs recording by discharging ink to a recording medium based on image data in a form that directly expresses, the recording head and the recording medium are relatively moved and the recording head discharges ink according to the image data. A recording control means for sequentially forming a predetermined recording area to be recorded by ink ejection, and counting the number of data indicating that ink is to be ejected for at least one of image data of a joint portion in the adjacent recording area. A data indicating that ink is to be ejected in the image data of the connection portion according to the count value. An ink jet recording apparatus characterized in that comprising a correction means for reducing the number, the. 2. The image forming apparatus according to claim 1, wherein the correction unit counts the number of data indicating that the ink is to be ejected for a pixel row corresponding to each nozzle of a recording head that forms a joint and ejects ink for recording the joint. The ink jet recording apparatus according to claim 1, wherein: 3. An amount by which the number of data for ejecting the ink is reduced according to the count value is determined in advance, and the correction means calculates an error between the predetermined amount and the amount that can be actually reduced. The inkjet recording apparatus according to claim 2, wherein is added to a reduction amount of another pixel row in the connection portion. 4. The ink jet recording apparatus according to claim 1, wherein the recording head generates bubbles in the ink by using thermal energy, and discharges the ink by the pressure of the bubbles. . 5. Using a recording head having a plurality of nozzles and capable of discharging ink from the plurality of nozzles, determining whether or not to discharge ink for each nozzle of the recording head as image data sent from a host device. A method of correcting image data in an ink jet recording apparatus that performs recording by ejecting ink to a recording medium based on image data in a form that directly represents the image data, wherein the recording head and the recording medium are relatively moved and recording is performed according to the image data. By ejecting ink from the head, predetermined recording areas to be recorded by ink ejection are sequentially formed adjacent to each other, and at the time of performing the formation, ink is applied to at least one of the image data of the joint portion in the adjacent recording area. The number of data indicating that the ink is to be ejected is counted, and the image data of the connection portion is calculated according to the counted value. Corrects to reduce the number of data to the effect that ejects definitive ink, a method of correcting the image data, characterized in that it has a step. 6. The step of correcting includes counting a number of data indicating that the ink is to be ejected for a pixel row corresponding to each nozzle of a recording head that constitutes a joint and ejects ink for recording the joint. 6. The method according to claim 5, wherein the image data is corrected. 7. An amount by which the number of data for ejecting the ink is reduced in accordance with the count value is determined in advance, and the step of correcting includes determining the predetermined amount and the amount that can be actually reduced. 7. The image data correction method according to claim 6, wherein the error is added to a reduction amount of another pixel row in the connection portion. 8. The image data according to claim 5, wherein the recording head generates bubbles in the ink using thermal energy, and discharges the ink by the pressure of the bubbles. Correction method.