JP2005067049A - Inkjet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always provide a good recording result by making a recording result such as white streaks in a recording result inconspicuous when there are a plurality of nozzle rows that eject the same ink and none of the nozzles adjacent in the main scanning direction is ejected. It is an object of the present invention to provide an ink jet recording apparatus that provides the above.
When a non-ejecting nozzle is generated in recording by a recording head having nozzles arranged in two rows in the main scanning direction, the non-ejecting nozzle does not perform the above-described non-ejecting operation on a pixel to which a dot should originally be printed. Other nozzles that are adjacent to the discharge nozzle in the main scanning direction are used to substitute dots instead. Further, when all of the nozzles adjacent in the main scanning direction are non-ejection nozzles, these non-ejection nozzles do not substitute dots for pixels to which dots are originally to be ejected, but for other pixels adjacent to the pixels. By increasing the dot shot amount to increase the recording density of adjacent pixels, the missing dots are made visually inconspicuous.
[Selection] FIG.

Description

  The present invention relates to an ink jet recording apparatus, and more particularly, to an ink jet recording apparatus that complements recording with other nozzles when an abnormal ejection nozzle occurs.

  Recording apparatuses such as printers, copiers, and facsimiles are often configured to record an image formed of a dot pattern on a recording medium such as paper or a plastic thin plate based on image information. Such a recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type, and the like according to a recording method, and an ink jet type (hereinafter, this type of recording apparatus is referred to as an “ink jet recording apparatus”). ) Is configured such that ink droplets are ejected and ejected from the ejection port of the recording head, and this is adhered to a recording medium for recording.

  This ink jet recording apparatus also has a plurality of ink ejection methods. For example, an electrothermal conversion element is provided in the nozzle of the recording head, and it is energized to generate heat, and the water that is the main component of the ink by the heat causes the ink to expand with the expansion force of bubbles generated by film boiling. There is a discharge method for discharging and flying, a so-called bubble jet (R) method.

  A general inkjet recording apparatus scans a recording head in which a plurality of nozzles are arranged on a recording medium in a direction orthogonal to the nozzle arrangement direction, and performs recording by ejecting ink from each nozzle during the scanning. . When the recording head moves to one end of the recording medium, a predetermined amount of paper is fed in a direction orthogonal to the scanning direction of the recording head, and recording scanning by the recording head is executed again. As described above, a serial type is widely used in which scanning of the recording head and paper feeding are alternately repeated to complete an image on the entire recording medium. In such a serial type recording apparatus, what will become the recording result when there is an abnormal nozzle will be described below with reference to the drawings.

  FIG. 12 is a diagram illustrating a conventional recording head and a recording result when the nozzle state is normal. FIG. 1A shows an example of a conventional recording head. A plurality of nozzles 2 are arranged in the recording head 1. FIG. 4B shows an image recorded by this recording head. Here, in order to simplify the description, the number of nozzles to be ejected is 16 and the image is a black solid with 16 pixels vertically and horizontally. The recording head has nozzles arranged in a vertical row, and ink is ejected in the direction perpendicular to the nozzle row of the recording head while main scanning is performed on the recording head to form an image on the recording medium. When all the nozzles discharge normally, there is no missing dot in the formed image, and a good recording result can be obtained.

  On the other hand, not all nozzles always perform proper ejection, and there are nozzles that cannot perform normal ejection due to deterioration due to repeated ejection operations and ink sticking inside the nozzles. In addition, nozzles that eventually fail to discharge (hereinafter referred to as “undischarge nozzles”) also occur. Further, the recording head tends to be lengthened in order to increase the recording speed. The longer the head, the greater the number of nozzles constituting the head, and the greater the number of nozzles, the greater the number of undischargeable nozzles. When recording is performed with a recording head having such an undischarge nozzle, white stripes parallel to the main scanning direction are formed, and the image quality is lowered.

  FIG. 13A shows a recording head including a discharge failure nozzle. In the figure, normal nozzles are indicated by “●”, and undischargeable nozzles are indicated by “•”. When recording is performed with a recording head having such an undischarge nozzle, as shown in FIG. 5B, ink is not ejected when the undischarge nozzle is main-scanned, resulting in white streaks.

  In order to solve such a problem, the following non-discharge nozzle complementing method is cited (see Patent Document 1).

  In this method, two recording heads, a first recording head and a second recording head, are provided for one ink color, and recording data is distributed to these two recording heads for recording. When the ejection failure nozzle detection unit detects ejection failure of the nozzles of the first recording head and the second recording head in advance, the data to be ejected by the nozzle is assigned to the nozzle of the other recording head, thereby ejecting the nozzle. Completion of

  Therefore, for example, when the nth nozzle of the first recording head is an undischarge nozzle, the data relating to the first recording head undischarge nozzle is the nth nozzle of the second recording head adjacent to the undischarge nozzle. Will be processed instead.

  In addition, a configuration in which two nozzle arrays are provided for one color in order to extend the life of the recording head has been proposed (see, for example, Patent Document 2). Here, when an abnormal nozzle occurs, data corresponding to the abnormal nozzle is added to the data of the other normal nozzle, thereby complementing pixels that are not recorded by the abnormal nozzle. However, in this configuration, when the number of abnormal nozzles increases, the process of recording with which nozzle row of the two nozzle rows becomes complicated, and the abnormal nozzle data is added to the normal nozzle data. Processing could be complicated.

JP 2001-010030 A Japanese Patent Laid-Open No. 10-006488

  However, such a conventional undischarge nozzle complementing method has the following problems. That is, in the same scanning, when both the adjacent nozzles of the first recording head and the second recording head are non-ejection, this non-ejection data cannot be complemented, so this portion is not recorded and the white stripe Will occur.

  The present invention has been made in view of such a problem, and when there are a plurality of nozzle rows that discharge the same ink and none of the nozzles adjacent in the main scanning direction discharges, white streaks or the like in the printing result are obtained. An object of the present invention is to provide an ink jet recording apparatus that makes recording defects inconspicuous and always provides good recording results.

  An ink jet recording apparatus of the present invention includes a recording operation in which a recording head having a plurality of nozzles arranged is scanned on a recording medium, and recording is performed by discharging ink from the nozzles during the scanning, and the scanning direction of the recording head In an ink jet recording apparatus that forms an image on the entire recording medium by alternately performing paper feeding for relatively moving the recording medium by a predetermined amount in a different direction, the recording head is the same in the scanning direction of the recording head At least two nozzles for ejecting ink are arranged, and a plurality of nozzles for ejecting the same ink in a direction different from the scanning direction of the recording head are arranged, and ejection data generation corresponding to each nozzle of the recording head is created Means, a recording head driving means for driving each nozzle of the recording head based on the ejection data creating means, and the recording A non-ejection detecting means for detecting ejection and non-ejection of each nozzle of the print head, and when all of the nozzles ejecting the same ink arranged in the scanning direction of the recording head are non-ejection, It is characterized by comprising ejection data correction means for correcting ejection data so as to increase the dot ejection amount for nozzles adjacent in a direction different from the scanning direction of the recording head.

  According to the above configuration, when a non-ejecting nozzle occurs, other nozzles adjacent to the non-ejecting nozzle will instead eject dots with respect to the pixels that the non-ejecting nozzle should originally eject dots. Specifically, when a nozzle adjacent in the scanning direction of the recording head is normal, the nozzle substitutes dots. Further, when all the nozzles adjacent in the scanning direction of the recording head are non-ejection nozzles, these non-ejection nozzles do not substitute dots for pixels that should originally be dot-implanted, and other nozzles adjacent to the pixels are not substituted. By increasing the dot injection amount to the pixel and increasing the recording density of the adjacent pixel, the missing dot is made visually inconspicuous.

  As described above, by using the present invention, it is possible to reduce white streaks in a recorded image caused by non-ejection nozzles and to suppress deterioration in image quality. In addition, since the complementary process can be executed without performing a plurality of scans on the same pixel, the time required for recording can be maintained the same as the normal state, and the recording speed is not reduced.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cutaway perspective view showing an ink jet recording apparatus according to an embodiment of the present invention.

  Reference numeral 1 denotes a recording head, and reference numeral 200 denotes a carriage. The recording head 1 is fixed to the carriage 200 such that the nozzle surface on which a plurality of nozzles are arranged faces the recording medium P.

  The carriage 200 is fixed to the endless belt 201 and is movable along the guide shaft 202. Endless belt 201 is wound around pulleys 203 and 204. A driving shaft of a carriage driving motor 204 is connected to the pulley 203. Therefore, the carriage 200 can reciprocate in the direction of arrow A along the guide shaft 202 by the rotational drive of the motor 204. This movement of the carriage 200 in the direction of arrow A is referred to as “main scanning”.

  On the carriage 200, a recording head 1 in which a plurality of ejection nozzles are arranged in parallel and an ink tank 205 as a container for storing ink are mounted.

  In the recording head 1, a plurality of ink ejection openings arranged in parallel in the transport direction of the paper P are formed on the surface facing the paper P as a recording medium. The recording head 1 is provided with an ink path that communicates with each of the plurality of ejection openings, and an electrothermal converter that generates thermal energy for ink ejection is provided corresponding to each ink path. ing. The electrothermal transducer generates heat by applying an electric pulse in accordance with driving data, thereby causing film boiling in the ink, and ejecting ink from the ejection port as the bubbles are generated. Each ink path is provided with a common liquid chamber that communicates with them in common, and this common liquid chamber is connected to the ink tank 205.

  In addition, this apparatus is provided with a linear encoder 206 for detecting the movement position of the carriage. That is, there is a linear scale 207 along the moving direction of the carriage 200, and slits are formed in the linear scale 207 at equal intervals such as 600 pieces per inch. On the other hand, the carriage 200 is provided with, for example, a slit detection system 208 having a light emitting unit and a light receiving sensor and a signal processing circuit. Therefore, the encoder 206 outputs a signal indicating ink ejection timing and carriage position information as the carriage 200 is moved. If ink is ejected for each slit detection, it is possible to execute recording with a resolution of 600 dpi in the main scanning direction.

  The recording paper P as a recording medium is intermittently conveyed in the direction of arrow B perpendicular to the scanning direction of the carriage 200. The recording paper P is supported by a pair of upstream roller units 209 and 210 and a pair of downstream roller units 211 and 212, and is conveyed in a state in which a certain tension is applied and flatness with respect to the head 1 is ensured. . In this case, the driving force for each roller unit is applied by a paper conveyance motor (PF motor) (not shown).

  With such a configuration, printing is performed on the entire recording paper P while alternately repeating printing of a width corresponding to the array width of the head ejection openings and feeding of the recording paper P as the carriage 200 moves.

  The carriage 200 stops at the home position as necessary at the start of recording or during recording. A cap member 213 for capping the ejection surface side of each head is provided at the home position, and the cap member 213 forcibly absorbs ink from the ejection port and prevents clogging of the ejection port. A suction recovery means (not shown) is connected.

FIG. 2 shows the configuration of the control system of the ink jet recording apparatus.
When the CPU 100 is a central processing unit and receives recording information from the host device, the CPU 100 executes control of each part of the recording device and data processing. The ROM 101 stores a processing program related to each processing procedure of the CPU 100, and the RAM 102 is used as a work area when the processing procedure is executed. That is, the CPU 100 executes processing such as processing image information received from the host device using a peripheral unit such as the RAM 102 and converting it into recording data by a control program stored in the ROM 101. In addition, the CPU 100 outputs the drive data, that is, the recording data and the drive control signal of the electrothermal transducer to the head driver 103. The head driver 103 drives the electrothermal transducer of the recording head 1 based on the input drive data, and discharges and records ink.

  The CPU 100 also controls a carriage drive motor 204 for reciprocating the carriage 200 and a paper transport (PF) motor 104 for transporting the recording paper P via motor drivers 105 and 106, respectively. The head driver 103 receives an ejection timing signal and carriage position information from the encoder 206.

  Reference numeral 108 denotes a discharge failure detection unit, which includes a pair of a light emitting element such as an LED and a light sensor such as a silicon photosensor (SPD) or a phototransistor. The ink of the nozzle to be checked is ejected and illuminated by the light emitting element. A shadow generated when the light passes through the light sensor is received by a light sensor, and a change in light input is detected to determine whether or not ink has blown. In an abnormal discharge failure nozzle, ink is not discharged, so the output of the optical sensor remains unchanged. In this way, ink is ejected for each nozzle of interest, nozzle non-ejection and ejection are confirmed, and all nozzles are checked.

  FIG. 3 is a diagram showing the relationship between the nozzle array of the recording head, the corresponding mask data, and the recording result.

  FIG. 4A is a schematic diagram showing the nozzle rows of the recording head. Here, in order to simplify the explanation, it is assumed that the horizontal 16 rows are 16 nozzles. In the figure, reference numerals 2 and 3 denote nozzles from which the same color ink is ejected. In the drawing, the left column of the nozzle 2 is indicated by “●”, and the right column of the nozzle 3 is indicated by “◎”. The recording head moves in a direction perpendicular to the nozzle row, and ink is ejected during this movement to form an image. Here, since there are two nozzle rows that eject the same color ink, at one point, one of the two nozzles adjacent in the moving direction of the recording head, that is, the main scanning direction, ejects ink. In order to realize such an operation, the present embodiment uses the following mask data.

  First, mask data when all nozzles of the recording head are determined to be only normal nozzles by the discharge failure detection unit will be described.

  FIG. 6B shows mask data corresponding to the recording head of FIG. 5A at normal time, and is data indicating which nozzle is used for recording. This is mask data for recording a solid image. When the discharge nozzle is “●”, it is “0”, and when it is “◎”, it is “1”. In the embodiment of the present invention, the mask size in the direction parallel to the nozzle row is the same as the number of nozzles of the recording head. Although the direction orthogonal to the nozzle row is displayed for 16 pixels, the image size to be normally recorded is larger, so that the 16th and subsequent pixels of the mask are repeated and used in the first row.

  FIG. 6C is a schematic diagram showing a recording result recorded based on the mask data of FIG. Since the mask data repeats “0” and “1” every other column, the nozzle 2 and the nozzle 3 are used alternately for each column in the printing result.

  Generation of mask data when all the nozzles are normal is performed using the following matrix.

FIG. 4 is a diagram showing a matrix for generating normal mask data.
In the figure, the upper left matrix is “a”, the upper right matrix is “b”, the lower left matrix is “c”, and the lower right matrix is “d”. Here, a = 0, b = 1, c = 0, and d = 1. Then, when the matrix of 2 columns and 2 rows is copied seven times and connected to the right, the matrix becomes 16 columns and 2 rows. If this is copied seven times and connected side by side, a 16 × 16 matrix matrix can be created as shown in FIG. As shown in FIG. 3B, this mask has an odd-numbered column “0” from the left in the figure, 2, 4, 6,...・ Even numbered column is “1”. Therefore, when recording is performed by performing main scanning from the left to the right in the drawing using the recording head of FIG. 3A and the mask of FIG. 3B, the “●” is displayed as shown in FIG. Rows and “◎” rows are recorded alternately. In the drawing, the ink dots are indicated by “●” and “◎” in order to explain which row of nozzles the ink is ejected from, but in actuality, both are dots of the same color. In consideration of one nozzle, without discharging continuously, when one discharge is performed, the next period is a rest. Therefore, even if the discharge frequency is constant, the main scanning speed can be doubled, so that the recording time can be shortened.

  In addition, since this mask pattern records one pixel by alternately ejecting two nozzles, the image quality is improved by reducing the swaying of the nozzles and the non-ejection to half. Therefore, even if there is a discharge failure nozzle, it is possible to suppress deterioration in image quality caused by it.

  Specifically, as shown in FIG. 5 (a), there is a case where there is a discharge failure nozzle “•” in a part of the nozzle row, and the discharge data is obtained by the mask pattern diagram 5 (b) similar to FIG. 3 (b). FIG. 5C shows the recording result when the data is created and recorded. As shown in this figure, every other missing dot due to the discharge failure nozzle is not continuous in the main scanning direction, so the white streak is not a straight line but a dotted line. Since the white streaks are not conspicuous visually, image quality deterioration can be alleviated. FIG. 5D is a diagram in which the normal nozzle in FIG. 5A is changed to “●” and the undischarge nozzle is changed to “•”. FIG. 5E is a diagram showing the recording result of FIG. 5C with the discharge failure set to blank and the discharge changed to “●”. As can be seen from this figure, since the lack of dots is not continuous, the degree of conspicuous white streaks is alleviated compared to the recording result shown in FIG.

  That is, in this mask pattern, dot missing will not continue in the main scanning direction unless both nozzles adjacent in the main scanning direction fail to discharge.

  Although the number of nozzle rows in this embodiment is two, the number of nozzle rows that eject the same color ink may be increased to three rows and four rows. When the number of rows is increased, the image quality is improved by reducing nozzle sway and discharge failure to 1 / row (half for 2 rows and 1/4 for 4 rows).

  The mask data shown in FIG. 3B is a pattern that is alternately used for each nozzle row based on the matrix shown in FIG. 4, but this mask pattern may have randomness. That is, even if the above-described regular mask pattern is not used, if one dot is ejected in the same row by alternately using two adjacent nozzles in the main scanning direction, one nozzle is temporarily not ejected. If the other nozzle is normal, the missing dots will not continue in a straight line.

  FIG. 6B shows mask data having randomness, and FIG. 6C shows a recording result recorded based on this mask data by the recording head of FIG. In order to simplify the explanation, the recording result of 16 × 16 pixels is shown by a 16-nozzle recording head as in FIG.

  Similarly to FIG. 3B, FIG. 6B also configures the data as “0” when using “●” and “1” when using “と し て” as the nozzle to be ejected.

  FIG. 7 shows a matrix used for generating the mask data. First, a matrix of 2 columns and 2 rows is formed. Next, the upper left matrix is “a”, the upper right matrix is “b”, the lower left matrix is “c”, and the lower right matrix is “d”. Here, it is assumed that a = 1 or 0 random number, b = 1−a, c = b, and d = a. The random number may be calculated by existing software of the CPU in order to create a normal mask. For example, a = ROUND (RAND (), 0) is a function used in spreadsheet software Excel (registered trademark of Microsoft Corporation), RAND () is a function that generates random numbers, and ROUND (number, 0) is This function rounds a number to 0 or 1. In accordance with random numbers generated using such existing software, a matrix of 2 columns and 2 rows is formed. And when this matrix is copied 7 times and connected to the right, it becomes a matrix with 16 columns and 2 rows. If this is copied seven times and connected side by side, a 16 × 16 matrix matrix can be created, as shown in FIG. 6 (b). Since this mask has a random pattern, the ejection frequency of the same nozzle varies randomly even when a solid image is recorded.

  By using this random pattern, in the arrangement of nozzle rows of the recording head, for example, the arrangement of “●” nozzles, the ratio of simultaneous ejection from adjacent nozzles is reduced. Due to the ink ejection structure, the pressure inside the ink liquid chamber, which is generated by the reaction when ejecting ink, becomes a pressure wave proportional to the ejection frequency. This pressure wave vibrates the meniscus (the air stretched around the ink discharge port and the ink level). When the discharge frequency matches the resonance frequency of the meniscus, the meniscus vibrates greatly. When the meniscus surface vibrates and the meniscus surface rises sharply, the ejection amount of ink increases when ejected, and when the meniscus surface retracts, the ejection amount decreases. Due to such a phenomenon, variation in ink ejection amount due to vibration of the meniscus surface occurs. This is undesirable because it is one of the causes of streaks and spots in the recorded image. Thus, by using a random mask in this manner, the ejection frequency is also random, so that the meniscus surface can be prevented from resonating and the image quality can be prevented from deteriorating. The recording with this mask data is as shown in FIG. “●” nozzles and “◎” nozzles are randomly used. In the figure, the ink dots are indicated by “●” or “◎” in order to explain which row of nozzles the ink was ejected from. There is no problem in terms of quality even if it is a random pattern mask.

  Next, a description will be given of a printing result when there is an undischarge nozzle when using this random mask data. Even in the case of this random pattern, one line is not recorded using either one of the two nozzles adjacent in the main scanning direction, but both are used randomly. The lack of is not in a straight line.

  As shown in FIG. 8, specifically, if “·” in FIG. 8A is an undischarge nozzle, the result of recording with the mask data in FIG. ). Note that the mask data in FIG. 8B is the same as the mask data in FIG. Further, in order to make it easy to understand the state of missing dots, FIG. 8D shows the normal nozzle in FIG. 8A changed to “●” and the undischarged nozzle to “•”. FIG. 8E shows the recording example of FIG. 8C with the discharge failure set to blank and the discharge changed to “●”. As can be seen from this figure, the missing dot is not a straight line but a random dotted line. Therefore, the white stripes are not visually noticeable, and the deterioration of the image quality can be alleviated.

  However, in these mask patterns, when there is an undischarge nozzle, the white stripe caused by it can be made inconspicuous, but the white stripe cannot be eliminated. Therefore, a mask pattern that complements the missing dot portion with dots from other nozzles will be described.

  FIG. 10A shows the arrangement of the nozzles of the recording head, and the nozzles are indicated by “●” and “◎”. In the “•” portion in the recording head, it is assumed that the nozzles do not discharge. FIG. 10C shows the result of recording on this recording head based on the mask data shown in FIG.

  First, random mask data is created by the random mask pattern generation method shown in FIG. Then, the non-ejection nozzle is detected by the non-ejection detection means. As for the method of detecting the discharge failure nozzle, the light receiving element is irradiated with the light emitting element, and ink is ejected one nozzle at a time, the ink is detected to be blocked, and the discharge failure nozzle is detected as the discharge failure nozzle. And a method of recording a pattern for ejecting ink for each nozzle and knowing an undischarge nozzle from the lack of the pattern are known. When the non-discharge nozzle is detected in this way, the mask of the data portion corresponding to the non-discharge nozzle is changed as follows in order not to use the non-discharge nozzle. In FIG. 9A, when the “●” nozzle is a discharge failure nozzle, the mask data corresponding to this nozzle is changed from “0” to “1”. On the other hand, if the “◎” nozzle is a non-discharge nozzle, the mask data corresponding to this nozzle is changed from “1” to “0”. In other words, the data is changed so that all the rows having undischarge nozzles are recorded by the other nozzle. In the example of the recording head in FIG. 9A, since the fifth nozzle from the top of the left column (“●” side) is a discharge failure nozzle, the mask data in FIG. 9B is set to “1” in the fifth row. To do. In addition, since the eleventh nozzle from the top of the right column (“」 ”side) of the recording head is a discharge failure nozzle, the eleventh line from the top of the mask in FIG. 9B is set to“ 0 ”. When recording is performed based on the mask data, as shown in FIG. 9C, the fifth line is the “◎” nozzle, the eleventh line from the top is the “●” nozzle, and the other lines are randomly “●” nozzle and “ ◎ ”recorded with nozzle. Thus, if there is a discharge failure nozzle, it can be complemented and recorded using the next (horizontal in the figure) nozzle. FIG. 9D is a diagram in which the normal nozzle in FIG. 9A is changed to “•” and the undischargeable nozzle is changed to “•”. FIG. 11E is a diagram illustrating the recording example of FIG. 11C in which discharge failure is blank and discharge is changed to “●”. Even if there is an undischarge nozzle, it is complemented and recorded using the adjacent nozzle, so no white streak occurs.

  However, if none of the nozzles adjacent in the main scanning direction is non-ejection, it cannot be complemented by the adjacent nozzles in the main scanning direction, so even if random mask data is used, printing is shown in FIG. White streaks appear. Therefore, the following processing is used in this embodiment in order to alleviate white streaks.

  FIG. 11A shows the arrangement of the nozzles of the recording head, and the nozzles are indicated by “◯” and “と”. In the “•” portion in the recording head, it is assumed that the nozzles do not discharge. FIG. 11C shows the recording head recorded based on the mask data of FIG. 11B.

  First, similarly to the mask pattern data generation of FIG. 6B, mask pattern data is created using the matrix of FIG. Next, when an undischarge nozzle is detected by the undischarge detection unit, if the nozzle adjacent to the undischarge nozzle in the main scanning direction is normal, the mask data is changed by the complementary processing described with reference to FIG. .

  On the other hand, when the nozzles adjacent to the non-discharge nozzle are also non-discharge nozzles, that is, when all the nozzles adjacent to the main scan direction are non-discharge, the mask data is changed as follows. In the recording head of FIG. 11A, when the nozzle “◯” is an undischarge nozzle, the mask data corresponding to this row is set to “1”, and when the nozzle “◎” is an undischarge nozzle, Set the mask data corresponding to the row to “0”. Up to this point, the process is the same as in FIG. Therefore, when the mask data conversion process is performed from the “◯” nozzle side, if both nozzles are non-discharge nozzles, the process ends with the “◎” nozzle, so “○” and “◎” The data in the row corresponding to the part where all of the nozzles are undischargeable nozzles is “0”. This is an example of processing, and the data in the row corresponding to the ejection failure nozzle may be any of “0”, “1”, and “2”.

  Next, the mask data of the pixels in the odd columns in the pixels in the row + 1 row corresponding to the ejection failure nozzle and the pixels in the odd columns in the row-1 row corresponding to the ejection failure nozzle are set to “2”. In the example of the head shown in FIG. 11A, the nozzles in the fifth and eleventh rows from the top are both “◯” nozzles and “ノ ズ ル” nozzles, which are non-ejection nozzles. The mask data of the even columns of the 6th and 12th rows that are +1 is “2”, and the odd columns of the 4th and 10th rows that are -1 of the 5th and 11th rows of the discharge failure nozzle. The mask data is also “2”.

  In this mask data, “0” nozzle is used when “0”, “時” nozzle is used when “1”, and both “◯” nozzle and “◎” nozzle are discharged when “2”. When recording is performed based on the mask data, the result is as shown in FIG. Here, “◯” is recorded using the “◯” nozzle, and “◎” is recorded using the “◎” nozzle. “●” is used for both the “◯” nozzle and the “◎” nozzle, so two dots are shot at the same location.

  FIG. 11D is a diagram in which the normal nozzle of FIG. 11A is changed to “•” and the undischargeable nozzle is changed to “•”. FIG. 11E is a diagram showing the recording example of FIG. 11C with non-discharge being blank, 1-dot ejection being “●”, and 2-dot ejection being changed to a black square. As shown in the figure, two-dot ejection is performed across a line in which dots are missing, and pixels with two dots are staggered around the line in which the dots are missing. Yes. Therefore, the ink does not overflow more than necessary and does not overflow the ink in a specific area.

That is, in a row with an undischarge nozzle, ink cannot be ejected. However, since two dots are driven into one pixel for pixels in both adjacent rows, the portion becomes darker than the others, and visually. White streaks become inconspicuous.
FIG. 11 (e) shows a continuous white streak of missing dots as in FIG. 10 (e), but in actuality, the size of the dots generated by the ink landing on the recording paper P is shown. Since it is about twice as large as the nozzle interval (recording density), it spreads so as to cover the missing dot portion, and the white streak is not straight. And it becomes almost unnoticeable.

  These mask patterns are selected by the CPU 100 in accordance with the detection result of the discharge failure nozzle from the discharge failure detection unit. The proper use of the random mask pattern (see FIG. 6) and the normal mask pattern (see FIG. 3) that is not so may be determined based on a predetermined condition according to the state of the image to be recorded.

  As described above, when a non-ejection nozzle is generated by using the present invention, other nozzles adjacent to the non-ejection nozzle can be substituted for the pixel that the non-ejection nozzle should originally drive a dot. It comes to shoot dots. Specifically, when a nozzle adjacent in the scanning direction of the recording head is normal, the nozzle substitutes dots. Further, when all the nozzles adjacent in the scanning direction of the recording head are non-ejection nozzles, these non-ejection nozzles do not substitute dots for pixels that should originally be dot-implanted, and other nozzles adjacent to the pixels are not substituted. By increasing the dot injection amount with respect to the pixel and increasing the recording density of the adjacent pixel, it is possible to prevent the missing dot from being visually noticeable. Therefore, it is possible to reduce white streaks in the recorded image caused by the non-ejection nozzles and to suppress deterioration in image quality. In addition, since the complementary process can be executed without performing a plurality of scans on the same pixel, the time required for recording can be maintained the same as the normal state, and the recording speed is not reduced.

1 is a cutaway perspective view showing an ink jet recording apparatus according to an embodiment of the present invention. It is a block diagram which shows the electric constitution of an inkjet recording device. (A) shows a recording head in an embodiment of the present invention, (b) shows an example of mask data, (c) shows a recording result recorded by the recording head of (a) based on the mask data of (b). FIG. It is a figure which shows the matrix for producing the mask data of FIG.3 (b). (A) shows a recording head including an ejection failure nozzle, (b) shows an example of mask data similar to FIG. 3 (b), and (c) shows the recording of (a) based on the mask data of (b). (D) shows the recording result recorded by the head, (d) shows the ejection nozzle for the recording head of (a) with “●”, the undischarged nozzle with “•”, and (e) shows the dot that has been ejected with “●”. It is a schematic diagram of the recording result shown. (A) shows a recording head in an embodiment of the present invention, (b) shows an example of mask data, (c) shows a recording result recorded by the recording head of (a) based on the mask data of (b). FIG. It is a figure which shows the matrix for producing the mask data of FIG.6 (b). (A) shows a recording head including an ejection failure nozzle, (b) shows an example of mask data similar to FIG. 6 (b), and (c) shows the recording of (a) based on the mask data of (b). (D) shows the recording result recorded by the head, (d) shows the ejection nozzle for the recording head of (a) with “●”, the undischarged nozzle with “•”, and (e) shows the dot that has been ejected with “●”. It is a schematic diagram of the recording result shown. (A) shows a recording head including an ejection failure nozzle, (b) shows an example of mask data complementing the ejection failure nozzle portion, and (c) shows a recording head of (a) based on the mask data of (b). (D) indicates the discharge nozzle for the recording head of (a), “•” indicates the discharge nozzle, “•” indicates the discharge failure nozzle, and (e) indicates the dot that has been printed by “●”. It is a schematic diagram of the recorded result. (A) shows a recording head including an ejection failure nozzle, (b) shows an example of mask data subjected to the same complementary processing as FIG. 9 (b), and (c) is based on the mask data of (b) ( (a) shows the recording result recorded by the recording head, (d) shows the discharge nozzle for the recording head of (a) with “●”, the undischarge nozzle with “•”, and (e) shows the dot that has been implanted. It is a schematic diagram of a recording result indicated by “●”. (A) shows a recording head including an ejection failure nozzle, (b) shows an example of mask data obtained by complementing a nozzle adjacent to the ejection failure nozzle portion, and (c) shows the mask data of (b). (D) shows the recording result recorded with the recording head of (a), (d) shows the discharge nozzle for the recording head of (a) with “●” and the undischarge nozzle with “•”, and (e) is driven FIG. 6 is a schematic diagram of a recording result in which one dot is indicated by “●” and two dots are indicated by black squares. (A) shows a conventional recording head when the nozzle state is normal, and (b) is a diagram showing a recording result by the recording head of (a). (A) shows the conventional recording head containing an undischarge nozzle, (b) is a figure which shows the recording result by the recording head of (a).

Explanation of symbols

103 Head driver 104 Motor 105 Motor driver 200 Carriage 201 Endless belt 202 Guide shaft 203 Pulley 204 Carriage drive motor 204 Motor 205 Ink tank 206 Linear encoder 207 Linear scale 208 Detection system 209 Roller unit 211 Roller unit 213 Cap member

Claims (5)

A recording operation in which a recording head in which a plurality of nozzles are arranged is scanned on a recording medium, and recording is performed on the recording medium by ejecting ink from the nozzles during the scanning, and in a direction different from the scanning direction of the recording head. In an ink jet recording apparatus that forms an image on the entire recording medium by alternately performing paper feeding for relatively moving the quantitative recording medium,
The recording head includes at least two nozzles that eject the same ink along the scanning direction of the recording head, and nozzles that eject the same ink along a direction different from the scanning direction of the recording head. Are arranged,
Discharge data creation means corresponding to each nozzle of the print head, print head drive means for driving each nozzle of the print head based on the discharge data creation means,
Non-ejection detection means for detecting ejection and non-ejection of each nozzle of the recording head;
When all the nozzles that discharge the same ink arranged in the scanning direction of the recording head are non-ejecting, the dot ejection amount for the nozzles adjacent to the non-ejecting nozzle in a direction different from the scanning direction of the recording head An ink jet recording apparatus comprising: discharge data correcting means for correcting the discharge data so as to increase the amount of the ink.   The ejection data correction unit is arranged such that when all the nozzles ejecting the same ink arranged in the scanning direction of the recording head are non-ejection, the non-ejection nozzle corresponds to a pixel row in the scanning direction of the recording head. The ejection data of the nozzles adjacent to each other in a direction different from the scanning direction of the recording head is corrected so that two dots are shot in one pixel with respect to adjacent pixel rows in the same direction. 2. An ink jet recording apparatus according to 1.   3. The ink jet recording apparatus according to claim 2, wherein the two dots are placed every other pixel in a pixel row in the scanning direction of the recording head.   The ejection data correction unit, when any of the nozzles ejecting the same ink arranged in the scanning direction of the recording head is non-ejecting, for the pixels to which the non-ejecting nozzle corresponds, 2. The ink jet recording apparatus according to claim 1, wherein the ejection data is corrected so that dots are ejected from other nozzles ejecting the same ink arranged in the scanning direction of the recording head. A recording operation in which a recording head in which a plurality of nozzles are arranged is scanned on a recording medium, and recording is performed on the recording medium by ejecting ink from the nozzles during the scanning, and in a direction different from the scanning direction of the recording head. In an ink jet recording method using an ink jet recording apparatus that forms an image on the entire recording medium by alternately performing paper feeding for relatively moving the quantitative recording medium,
The recording head has at least two nozzles that eject the same ink in the scanning direction of the recording head, and a plurality of nozzles that eject the same ink in a direction different from the scanning direction of the recording head. ,
An ejection data creation step corresponding to each nozzle of the recording head;
A recording head driving step of driving each nozzle of the recording head based on the ejection data creation process;
A non-ejection detection step of detecting ejection and non-ejection of each nozzle of the recording head;
When all the nozzles that discharge the same ink arranged in the scanning direction of the recording head are non-ejecting, the dot ejection amount for the nozzles adjacent to the non-ejecting nozzle in a direction different from the scanning direction of the recording head An ink jet recording method comprising: an ejection data correction step for correcting ejection data so as to increase the amount of ink.

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